From 136a613cce6e119ba5e0a66767c041ce58f7e8c5 Mon Sep 17 00:00:00 2001
From: Guillaume Girol <symphorien+git@xlumurb.eu>
Date: Sun, 25 Jul 2021 12:00:00 +0000
Subject: [PATCH 001/567] nix-channel: use nix-env -i --remove-all to upgrade

Fixes #4110
---
 src/nix-channel/nix-channel.cc | 54 ++++++++++++++++++----------------
 1 file changed, 29 insertions(+), 25 deletions(-)

diff --git a/src/nix-channel/nix-channel.cc b/src/nix-channel/nix-channel.cc
index 3272c6125..eae15885a 100755
--- a/src/nix-channel/nix-channel.cc
+++ b/src/nix-channel/nix-channel.cc
@@ -88,15 +88,6 @@ static void update(const StringSet & channelNames)
     for (const auto & channel : channels) {
         auto name = channel.first;
         auto url = channel.second;
-        if (!(channelNames.empty() || channelNames.count(name)))
-            continue;
-
-        // We want to download the url to a file to see if it's a tarball while also checking if we
-        // got redirected in the process, so that we can grab the various parts of a nix channel
-        // definition from a consistent location if the redirect changes mid-download.
-        auto result = fetchers::downloadFile(store, url, std::string(baseNameOf(url)), false);
-        auto filename = store->toRealPath(result.storePath);
-        url = result.effectiveUrl;
 
         // If the URL contains a version number, append it to the name
         // attribute (so that "nix-env -q" on the channels profile
@@ -109,30 +100,43 @@ static void update(const StringSet & channelNames)
 
         std::string extraAttrs;
 
-        bool unpacked = false;
-        if (std::regex_search(filename, std::regex("\\.tar\\.(gz|bz2|xz)$"))) {
-            runProgram(settings.nixBinDir + "/nix-build", false, { "--no-out-link", "--expr", "import " + unpackChannelPath +
-                        "{ name = \"" + cname + "\"; channelName = \"" + name + "\"; src = builtins.storePath \"" + filename + "\"; }" });
-            unpacked = true;
-        }
+        if (!(channelNames.empty() || channelNames.count(name))) {
+            // no need to update this channel, reuse the existing store path
+            Path symlink = profile + "/" + name;
+            Path storepath = dirOf(readLink(symlink));
+            exprs.push_back("f: rec { name = \"" + cname + "\"; type = \"derivation\"; outputs = [\"out\"]; system = \"builtin\"; outPath = builtins.storePath \"" + storepath + "\"; out = { inherit outPath; };}");
+        } else {
+            // We want to download the url to a file to see if it's a tarball while also checking if we
+            // got redirected in the process, so that we can grab the various parts of a nix channel
+            // definition from a consistent location if the redirect changes mid-download.
+            auto result = fetchers::downloadFile(store, url, std::string(baseNameOf(url)), false);
+            auto filename = store->toRealPath(result.storePath);
+            url = result.effectiveUrl;
 
-        if (!unpacked) {
-            // Download the channel tarball.
-            try {
-                filename = store->toRealPath(fetchers::downloadFile(store, url + "/nixexprs.tar.xz", "nixexprs.tar.xz", false).storePath);
-            } catch (FileTransferError & e) {
-                filename = store->toRealPath(fetchers::downloadFile(store, url + "/nixexprs.tar.bz2", "nixexprs.tar.bz2", false).storePath);
+            bool unpacked = false;
+            if (std::regex_search(filename, std::regex("\\.tar\\.(gz|bz2|xz)$"))) {
+                runProgram(settings.nixBinDir + "/nix-build", false, { "--no-out-link", "--expr", "import " + unpackChannelPath +
+                            "{ name = \"" + cname + "\"; channelName = \"" + name + "\"; src = builtins.storePath \"" + filename + "\"; }" });
+                unpacked = true;
             }
-        }
 
-        // Regardless of where it came from, add the expression representing this channel to accumulated expression
-        exprs.push_back("f: f { name = \"" + cname + "\"; channelName = \"" + name + "\"; src = builtins.storePath \"" + filename + "\"; " + extraAttrs + " }");
+            if (!unpacked) {
+                // Download the channel tarball.
+                try {
+                    filename = store->toRealPath(fetchers::downloadFile(store, url + "/nixexprs.tar.xz", "nixexprs.tar.xz", false).storePath);
+                } catch (FileTransferError & e) {
+                    filename = store->toRealPath(fetchers::downloadFile(store, url + "/nixexprs.tar.bz2", "nixexprs.tar.bz2", false).storePath);
+                }
+            }
+            // Regardless of where it came from, add the expression representing this channel to accumulated expression
+            exprs.push_back("f: f { name = \"" + cname + "\"; channelName = \"" + name + "\"; src = builtins.storePath \"" + filename + "\"; " + extraAttrs + " }");
+        }
     }
 
     // Unpack the channel tarballs into the Nix store and install them
     // into the channels profile.
     std::cerr << "unpacking channels...\n";
-    Strings envArgs{ "--profile", profile, "--file", unpackChannelPath, "--install", "--from-expression" };
+    Strings envArgs{ "--profile", profile, "--file", unpackChannelPath, "--install", "--remove-all", "--from-expression" };
     for (auto & expr : exprs)
         envArgs.push_back(std::move(expr));
     envArgs.push_back("--quiet");

From 7cdaae6b9cc3ef5b64bbd7fd2776fa5e7572aa8d Mon Sep 17 00:00:00 2001
From: Viktor Kronvall <viktor.kronvall@gmail.com>
Date: Thu, 29 Jul 2021 01:44:19 +0900
Subject: [PATCH 002/567] Support SCP-like URLs in builtins.fetchGit attrs

This extends https://github.com/NixOS/nix/pull/4978 with
supporting the SCP-like urls in expressions like

```nix
builtins.fetchGit {
  url = "git@github.com:NixOS/nix.git";
  ref = "master";
}
```
---
 src/libexpr/primops/fetchTree.cc | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index 730db84ed..9ffd1c856 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -76,10 +76,24 @@ std::string fixURIForGit(std::string uri, EvalState & state)
         return fixURI(uri, state);
 }
 
-void addURI(EvalState &state, fetchers::Attrs &attrs, Symbol name, std::string v)
-{
+void addURI(
+    EvalState &state,
+    fetchers::Attrs &attrs,
+    Symbol name,
+    std::string v,
+    const std::optional<std::string> type
+) {
     string n(name);
-    attrs.emplace(name, n == "url" ? fixURI(v, state) : v);
+    if (n == "url") {
+        if (type == "git") {
+            attrs.emplace("type", "git");
+            attrs.emplace(name, fixURIForGit(v, state));
+        } else {
+            attrs.emplace(name, fixURI(v, state));
+        }
+    } else {
+        attrs.emplace(name, v);
+    }
 }
 
 struct FetchTreeParams {
@@ -112,10 +126,9 @@ static void fetchTree(
                     state,
                     attrs,
                     attr.name,
-                    state.coerceToString(*attr.pos, *attr.value, context, false, false)
+                    state.coerceToString(*attr.pos, *attr.value, context, false, false),
+                    type
                 );
-            else if (attr.value->type() == nString)
-                addURI(state, attrs, attr.name, attr.value->string.s);
             else if (attr.value->type() == nBool)
                 attrs.emplace(attr.name, Explicit<bool>{attr.value->boolean});
             else if (attr.value->type() == nInt)

From cb1ffb7789365d77e310a267dcc63c7518127045 Mon Sep 17 00:00:00 2001
From: Madeline Haraj <madeline.haraj@obsidian.systems>
Date: Thu, 5 Aug 2021 21:22:36 -0400
Subject: [PATCH 003/567] Use the store path as the context of the result of
 fetchTree, not the real path

---
 src/libexpr/primops/fetchTree.cc | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index 730db84ed..872ebd83c 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -229,20 +229,21 @@ static void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
         ? fetchers::downloadTarball(state.store, *url, name, (bool) expectedHash).first.storePath
         : fetchers::downloadFile(state.store, *url, name, (bool) expectedHash).storePath;
 
-    auto path = state.store->toRealPath(storePath);
+    auto realPath = state.store->toRealPath(storePath);
 
     if (expectedHash) {
         auto hash = unpack
             ? state.store->queryPathInfo(storePath)->narHash
-            : hashFile(htSHA256, path);
+            : hashFile(htSHA256, realPath);
         if (hash != *expectedHash)
             throw Error((unsigned int) 102, "hash mismatch in file downloaded from '%s':\n  specified: %s\n  got:       %s",
                 *url, expectedHash->to_string(Base32, true), hash.to_string(Base32, true));
     }
 
     if (state.allowedPaths)
-        state.allowedPaths->insert(path);
+        state.allowedPaths->insert(realPath);
 
+    auto path = state.store->printStorePath(storePath);
     mkString(v, path, PathSet({path}));
 }
 

From d56ddbb99965dc46cb80b05857588624c249aba6 Mon Sep 17 00:00:00 2001
From: Madeline Haraj <madeline.haraj@obsidian.systems>
Date: Fri, 6 Aug 2021 12:36:03 -0400
Subject: [PATCH 004/567] Fix disabled case in local store test

---
 tests/local-store.sh | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/tests/local-store.sh b/tests/local-store.sh
index 4ec3d64b0..0247346f1 100644
--- a/tests/local-store.sh
+++ b/tests/local-store.sh
@@ -15,6 +15,5 @@ PATH1=$(nix path-info --store ./x $CORRECT_PATH)
 PATH2=$(nix path-info --store "$PWD/x" $CORRECT_PATH)
 [ $CORRECT_PATH == $PATH2 ]
 
-# FIXME we could also test the query parameter version:
-# PATH3=$(nix path-info --store "local?store=$PWD/x" $CORRECT_PATH)
-# [ $CORRECT_PATH == $PATH3 ]
+PATH3=$(nix path-info --store "local?root=$PWD/x" $CORRECT_PATH)
+[ $CORRECT_PATH == $PATH3 ]

From 8438114399ce025b6977215dbaedc05697a6d958 Mon Sep 17 00:00:00 2001
From: Magic_RB <magic_rb@redalder.org>
Date: Mon, 3 May 2021 09:54:31 +0200
Subject: [PATCH 005/567] Add ignored_acls setting

Signed-off-by: Magic_RB <magic_rb@redalder.org>
---
 src/libstore/globals.hh     | 9 +++++++++
 src/libstore/local-store.cc | 4 +---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index 8784d5faf..7e01b4960 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -805,6 +805,15 @@ public:
           may be useful in certain scenarios (e.g. to spin up containers or
           set up userspace network interfaces in tests).
         )"};
+
+    Setting<StringSet> ignoredAcls{
+        this, {"security.selinux"}, "ignored-acls",
+        R"(
+          A list of ACLs that should be ignored, normally Nix attempts to
+          remove all ACLs from files and directories in the Nix store, but
+          some ACLs like `security.selinux` or `system.nfs4_acl` can't be
+          removed even by root. Therefore it's best to just ignore them.
+        )"};
 #endif
 
     Setting<Strings> hashedMirrors{
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 747eb205e..c6f774bc2 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -583,9 +583,7 @@ static void canonicalisePathMetaData_(const Path & path, uid_t fromUid, InodesSe
             throw SysError("querying extended attributes of '%s'", path);
 
         for (auto & eaName: tokenizeString<Strings>(std::string(eaBuf.data(), eaSize), std::string("\000", 1))) {
-            /* Ignore SELinux security labels since these cannot be
-               removed even by root. */
-            if (eaName == "security.selinux") continue;
+            if (settings.ignoredAcls.get().count(eaName)) continue;
             if (lremovexattr(path.c_str(), eaName.c_str()) == -1)
                 throw SysError("removing extended attribute '%s' from '%s'", eaName, path);
         }

From d90582be33601d9f25b9398e6938e84b5861d6cf Mon Sep 17 00:00:00 2001
From: Tom Bereknyei <tomberek@gmail.com>
Date: Sun, 22 Aug 2021 18:45:42 -0400
Subject: [PATCH 006/567] Allow use of path and filterSource in flakes

As filterSource and path perform work, add paths to allowedPaths.
---
 src/libexpr/primops.cc | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index bfe41c9fa..6c86aa4e1 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1886,6 +1886,20 @@ static void addPath(EvalState & state, const Pos & pos, const string & name, con
         dstPath = state.store->printStorePath(*expectedStorePath);
 
     mkString(v, dstPath, {dstPath});
+    if (state.allowedPaths)
+        state.allowedPaths->insert(v.string.s);
+
+    try {
+        state.realiseContext({});
+    } catch (InvalidPathError & e) {
+        throw EvalError({
+            .msg = hintfmt("cannot import '%1%', since path '%2%' is not valid", path, e.path),
+            .errPos = pos
+        });
+    } catch (Error & e) {
+        e.addTrace(pos, "while importing '%s'", path);
+        throw e;
+    }
 }
 
 

From 50edbc4ddf1f32fbf30ecaa7222beadf10947f5e Mon Sep 17 00:00:00 2001
From: Maximilian Bosch <maximilian@mbosch.me>
Date: Mon, 23 Aug 2021 23:47:29 +0200
Subject: [PATCH 007/567] nix-store --serve: pass on `settings.keepFailed` from
 SSH store

When doing e.g.

    nix-build -A package --keep-failed --option \
      builders \
      'ssh://mfhydra?remote-store=/home/bosch/store x86_64-linux - 10 4 big-parallel'

this doesn't work properly because this build-setting is ignored.

I changed this behavior by passing the `settings.keepFailed` through the
serve-protocol to remote machines to make sure that I can introspect the
build-directory (which is particularly helpful when I have to look at a
`config.log` from a failed build for instance).
---
 src/libstore/legacy-ssh-store.cc |  4 ++++
 src/libstore/serve-protocol.hh   |  2 +-
 src/nix-store/nix-store.cc       |  3 +++
 tests/build-remote.sh            | 13 +++++++++++++
 tests/failing.nix                | 22 ++++++++++++++++++++++
 5 files changed, 43 insertions(+), 1 deletion(-)
 create mode 100644 tests/failing.nix

diff --git a/src/libstore/legacy-ssh-store.cc b/src/libstore/legacy-ssh-store.cc
index 45eed5707..7da3b36b5 100644
--- a/src/libstore/legacy-ssh-store.cc
+++ b/src/libstore/legacy-ssh-store.cc
@@ -237,6 +237,10 @@ private:
             conn.to
                 << settings.buildRepeat
                 << settings.enforceDeterminism;
+
+        if (GET_PROTOCOL_MINOR(conn.remoteVersion) >= 7) {
+            conn.to << ((int) settings.keepFailed);
+        }
     }
 
 public:
diff --git a/src/libstore/serve-protocol.hh b/src/libstore/serve-protocol.hh
index 02d0810cc..3f76baa82 100644
--- a/src/libstore/serve-protocol.hh
+++ b/src/libstore/serve-protocol.hh
@@ -5,7 +5,7 @@ namespace nix {
 #define SERVE_MAGIC_1 0x390c9deb
 #define SERVE_MAGIC_2 0x5452eecb
 
-#define SERVE_PROTOCOL_VERSION (2 << 8 | 6)
+#define SERVE_PROTOCOL_VERSION (2 << 8 | 7)
 #define GET_PROTOCOL_MAJOR(x) ((x) & 0xff00)
 #define GET_PROTOCOL_MINOR(x) ((x) & 0x00ff)
 
diff --git a/src/nix-store/nix-store.cc b/src/nix-store/nix-store.cc
index b327793e7..f0ce0368a 100644
--- a/src/nix-store/nix-store.cc
+++ b/src/nix-store/nix-store.cc
@@ -801,6 +801,9 @@ static void opServe(Strings opFlags, Strings opArgs)
             settings.enforceDeterminism = readInt(in);
             settings.runDiffHook = true;
         }
+        if (GET_PROTOCOL_MINOR(clientVersion) >= 7) {
+            settings.keepFailed = (bool) readInt(in);
+        }
         settings.printRepeatedBuilds = false;
     };
 
diff --git a/tests/build-remote.sh b/tests/build-remote.sh
index 27d85a83d..806c6d261 100644
--- a/tests/build-remote.sh
+++ b/tests/build-remote.sh
@@ -53,3 +53,16 @@ nix path-info --store $TEST_ROOT/machine3 --all \
   | grep -v builder-build-remote-input-1.sh \
   | grep -v builder-build-remote-input-2.sh \
   | grep builder-build-remote-input-3.sh
+
+# Behavior of keep-failed
+out="$(nix-build 2>&1 failing.nix \
+  --builders "$(join_by '; ' "${builders[@]}")"  \
+  --keep-failed \
+  --store $TEST_ROOT/machine0 \
+  -j0 \
+  --arg busybox $busybox)" || true
+
+[[ "$out" =~ .*"note: keeping build directory".* ]]
+
+build_dir="$(grep "note: keeping build" <<< "$out" | sed -E "s/^(.*)note: keeping build directory '(.*)'(.*)$/\2/")"
+[[ "foo" = $(<"$build_dir"/bar) ]]
diff --git a/tests/failing.nix b/tests/failing.nix
new file mode 100644
index 000000000..2a0350d4d
--- /dev/null
+++ b/tests/failing.nix
@@ -0,0 +1,22 @@
+{ busybox }:
+with import ./config.nix;
+let
+
+  mkDerivation = args:
+    derivation ({
+      inherit system;
+      builder = busybox;
+      args = ["sh" "-e" args.builder or (builtins.toFile "builder-${args.name}.sh" "if [ -e .attrs.sh ]; then source .attrs.sh; fi; eval \"$buildCommand\"")];
+    } // removeAttrs args ["builder" "meta"])
+    // { meta = args.meta or {}; };
+in
+{
+
+  failing = mkDerivation {
+    name = "failing";
+    buildCommand = ''
+      echo foo > bar
+      exit 1
+    '';
+  };
+}

From 991cc53386cd68038e573f6e0f2da247ae533c07 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 15 Sep 2021 18:30:37 +0200
Subject: [PATCH 008/567] Revert "Disallow reading flake.lock"

This reverts commit e5596113f7fc5e47e058bb15afdf75eee02ed95e.
---
 src/libexpr/primops.cc | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 1de86ad04..8a087a781 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1412,11 +1412,6 @@ static void prim_readFile(EvalState & state, const Pos & pos, Value * * args, Va
 {
     PathSet context;
     Path path = state.coerceToPath(pos, *args[0], context);
-    if (baseNameOf(path) == "flake.lock")
-        throw Error({
-            .msg = hintfmt("cannot read '%s' because flake lock files can be out of sync", path),
-            .errPos = pos
-        });
     try {
         state.realiseContext(context);
     } catch (InvalidPathError & e) {

From 027344ce7e88bfcb6f8ed890299f286cc8e4156e Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 15 Sep 2021 18:31:42 +0200
Subject: [PATCH 009/567] If we can't write a lock file, pretend the top-level
 flake is dirty

Alternative to #4639. You can still read flake.lock, but at least in
reproducible workflows like NixOS configurations where you require a
non-dirty tree, evaluation will fail because there is no rev.
---
 src/libexpr/flake/flake.cc       | 12 +++++++++--
 src/libexpr/flake/flake.hh       | 11 ++++++----
 src/libexpr/primops/fetchTree.cc | 37 ++++++++++++++++++--------------
 3 files changed, 38 insertions(+), 22 deletions(-)

diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 010d97285..c1a099613 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -635,8 +635,10 @@ LockedFlake lockFlake(
                     }
                 } else
                     throw Error("cannot write modified lock file of flake '%s' (use '--no-write-lock-file' to ignore)", topRef);
-            } else
+            } else {
                 warn("not writing modified lock file of flake '%s':\n%s", topRef, chomp(diff));
+                flake.forceDirty = true;
+            }
         }
 
         return LockedFlake { .flake = std::move(flake), .lockFile = std::move(newLockFile) };
@@ -659,7 +661,13 @@ void callFlake(EvalState & state,
 
     mkString(*vLocks, lockedFlake.lockFile.to_string());
 
-    emitTreeAttrs(state, *lockedFlake.flake.sourceInfo, lockedFlake.flake.lockedRef.input, *vRootSrc);
+    emitTreeAttrs(
+        state,
+        *lockedFlake.flake.sourceInfo,
+        lockedFlake.flake.lockedRef.input,
+        *vRootSrc,
+        false,
+        lockedFlake.flake.forceDirty);
 
     mkString(*vRootSubdir, lockedFlake.flake.lockedRef.subdir);
 
diff --git a/src/libexpr/flake/flake.hh b/src/libexpr/flake/flake.hh
index d46da9d68..524b18af1 100644
--- a/src/libexpr/flake/flake.hh
+++ b/src/libexpr/flake/flake.hh
@@ -58,9 +58,10 @@ struct ConfigFile
 /* The contents of a flake.nix file. */
 struct Flake
 {
-    FlakeRef originalRef;   // the original flake specification (by the user)
-    FlakeRef resolvedRef;   // registry references and caching resolved to the specific underlying flake
-    FlakeRef lockedRef;     // the specific local store result of invoking the fetcher
+    FlakeRef originalRef; // the original flake specification (by the user)
+    FlakeRef resolvedRef; // registry references and caching resolved to the specific underlying flake
+    FlakeRef lockedRef; // the specific local store result of invoking the fetcher
+    bool forceDirty = false; // pretend that 'lockedRef' is dirty
     std::optional<std::string> description;
     std::shared_ptr<const fetchers::Tree> sourceInfo;
     FlakeInputs inputs;
@@ -140,6 +141,8 @@ void emitTreeAttrs(
     EvalState & state,
     const fetchers::Tree & tree,
     const fetchers::Input & input,
-    Value & v, bool emptyRevFallback = false);
+    Value & v,
+    bool emptyRevFallback = false,
+    bool forceDirty = false);
 
 }
diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index 9990a0207..53534c49e 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -16,7 +16,8 @@ void emitTreeAttrs(
     const fetchers::Tree & tree,
     const fetchers::Input & input,
     Value & v,
-    bool emptyRevFallback)
+    bool emptyRevFallback,
+    bool forceDirty)
 {
     assert(input.isImmutable());
 
@@ -33,24 +34,28 @@ void emitTreeAttrs(
     mkString(*state.allocAttr(v, state.symbols.create("narHash")),
         narHash->to_string(SRI, true));
 
-    if (auto rev = input.getRev()) {
-        mkString(*state.allocAttr(v, state.symbols.create("rev")), rev->gitRev());
-        mkString(*state.allocAttr(v, state.symbols.create("shortRev")), rev->gitShortRev());
-    } else if (emptyRevFallback) {
-        // Backwards compat for `builtins.fetchGit`: dirty repos return an empty sha1 as rev
-        auto emptyHash = Hash(htSHA1);
-        mkString(*state.allocAttr(v, state.symbols.create("rev")), emptyHash.gitRev());
-        mkString(*state.allocAttr(v, state.symbols.create("shortRev")), emptyHash.gitShortRev());
-    }
-
     if (input.getType() == "git")
         mkBool(*state.allocAttr(v, state.symbols.create("submodules")),
             fetchers::maybeGetBoolAttr(input.attrs, "submodules").value_or(true));
 
-    if (auto revCount = input.getRevCount())
-        mkInt(*state.allocAttr(v, state.symbols.create("revCount")), *revCount);
-    else if (emptyRevFallback)
-        mkInt(*state.allocAttr(v, state.symbols.create("revCount")), 0);
+    if (!forceDirty) {
+
+        if (auto rev = input.getRev()) {
+            mkString(*state.allocAttr(v, state.symbols.create("rev")), rev->gitRev());
+            mkString(*state.allocAttr(v, state.symbols.create("shortRev")), rev->gitShortRev());
+        } else if (emptyRevFallback) {
+            // Backwards compat for `builtins.fetchGit`: dirty repos return an empty sha1 as rev
+            auto emptyHash = Hash(htSHA1);
+            mkString(*state.allocAttr(v, state.symbols.create("rev")), emptyHash.gitRev());
+            mkString(*state.allocAttr(v, state.symbols.create("shortRev")), emptyHash.gitShortRev());
+        }
+
+        if (auto revCount = input.getRevCount())
+            mkInt(*state.allocAttr(v, state.symbols.create("revCount")), *revCount);
+        else if (emptyRevFallback)
+            mkInt(*state.allocAttr(v, state.symbols.create("revCount")), 0);
+
+    }
 
     if (auto lastModified = input.getLastModified()) {
         mkInt(*state.allocAttr(v, state.symbols.create("lastModified")), *lastModified);
@@ -167,7 +172,7 @@ static void fetchTree(
     if (state.allowedPaths)
         state.allowedPaths->insert(tree.actualPath);
 
-    emitTreeAttrs(state, tree, input2, v, params.emptyRevFallback);
+    emitTreeAttrs(state, tree, input2, v, params.emptyRevFallback, false);
 }
 
 static void prim_fetchTree(EvalState & state, const Pos & pos, Value * * args, Value & v)

From cbe9ddfd1ad189f3b4c0b43fabe0444437b1fdd7 Mon Sep 17 00:00:00 2001
From: Geoff Reedy <geoff@programmer-monk.net>
Date: Thu, 16 Sep 2021 15:58:21 -0600
Subject: [PATCH 010/567] Include subpath in flake fingerprint

Without this, flakes within the same tree and same lock data will have
the same fingerprint and the eval cache for one flake will be
incorrectly used for another.
---
 src/libexpr/flake/flake.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index c1a099613..6893f157e 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -710,8 +710,9 @@ Fingerprint LockedFlake::getFingerprint() const
     // and we haven't changed it, then it's sufficient to use
     // flake.sourceInfo.storePath for the fingerprint.
     return hashString(htSHA256,
-        fmt("%s;%d;%d;%s",
+        fmt("%s;%s;%d;%d;%s",
             flake.sourceInfo->storePath.to_string(),
+            flake.lockedRef.subdir,
             flake.lockedRef.input.getRevCount().value_or(0),
             flake.lockedRef.input.getLastModified().value_or(0),
             lockFile));

From fd67a0f927ec0711eba59714939ff939fc95db38 Mon Sep 17 00:00:00 2001
From: Gregor Kleen <20089782+gkleen@users.noreply.github.com>
Date: Fri, 17 Sep 2021 10:45:19 +0200
Subject: [PATCH 011/567] Fix scheme argument to s3 cache

---
 src/libstore/s3-binary-cache-store.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libstore/s3-binary-cache-store.cc b/src/libstore/s3-binary-cache-store.cc
index 6bfbee044..51d86c4e6 100644
--- a/src/libstore/s3-binary-cache-store.cc
+++ b/src/libstore/s3-binary-cache-store.cc
@@ -209,7 +209,7 @@ struct S3BinaryCacheStoreImpl : virtual S3BinaryCacheStoreConfig, public virtual
     S3Helper s3Helper;
 
     S3BinaryCacheStoreImpl(
-        const std::string & scheme,
+        const std::string & uriScheme,
         const std::string & bucketName,
         const Params & params)
         : StoreConfig(params)

From 374fe49ff78c13457c6cfe396f9ed0cb986c903b Mon Sep 17 00:00:00 2001
From: Michael Bishop <cleverca22@gmail.com>
Date: Sun, 19 Sep 2021 23:07:10 -0300
Subject: [PATCH 012/567] set the PER_LINUX32 personality flag, when building
 for armv6l-linux or armv7l-linux

this prevents 32bit builds from detecting a 64bit kernel and picking the wrong target
---
 src/libstore/build/local-derivation-goal.cc | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 518edae9c..21d7d7408 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -1778,6 +1778,10 @@ void LocalDerivationGoal::runChild()
             if (personality(PER_LINUX32) == -1)
                 throw SysError("cannot set i686-linux personality");
         }
+        if (drv->platform == "armv7l-linux" || drv->platform == "armv6l-linux") {
+          if (personality(PER_LINUX32) == -1)
+            throw SysError("cannot set 32bit linux personality");
+        }
 
         /* Impersonate a Linux 2.6 machine to get some determinism in
            builds that depend on the kernel version. */

From 81ed6ee20199e99d3f22bfcbd49eafc678608fc0 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Mon, 20 Sep 2021 14:37:09 +0200
Subject: [PATCH 013/567] flake: Use the real nixUnstable from nixpkgs
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Don’t let it pick our overriden lowdown as that would cause it not to be
cached in cache.nixos.org
---
 flake.nix | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/flake.nix b/flake.nix
index 9b737b850..5f77e42d1 100644
--- a/flake.nix
+++ b/flake.nix
@@ -259,11 +259,11 @@
       # 'nix.perl-bindings' packages.
       overlay = final: prev: {
 
-        # An older version of Nix to test against when using the daemon.
-        # Currently using `nixUnstable` as the stable one doesn't respect
-        # `NIX_DAEMON_SOCKET_PATH` which is needed for the tests.
         nixStable = prev.nix;
 
+        # Forward from the previous stage as we don’t want it to pick the lowdown override
+        nixUnstable = prev.nixUnstable;
+
         nix = with final; with commonDeps pkgs; stdenv.mkDerivation {
           name = "nix-${version}";
           inherit version;

From 5cbb9c5406f3058fcc9f99692490fbc5a4f57876 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 21 Sep 2021 13:19:26 +0200
Subject: [PATCH 014/567] path fetcher: Fix relative path check

---
 src/libfetchers/path.cc | 13 +++++++++----
 tests/flakes.sh         |  4 ++--
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/src/libfetchers/path.cc b/src/libfetchers/path.cc
index b6fcdac9e..b35c04cfc 100644
--- a/src/libfetchers/path.cc
+++ b/src/libfetchers/path.cc
@@ -85,18 +85,23 @@ struct PathInputScheme : InputScheme
         std::string absPath;
         auto path = getStrAttr(input.attrs, "path");
 
-        if (path[0] != '/' && input.parent) {
+        if (path[0] != '/') {
+            if (!input.parent)
+                throw Error("cannot fetch input '%s' because it uses a relative path", input.to_string());
+
             auto parent = canonPath(*input.parent);
 
             // the path isn't relative, prefix it
-            absPath = canonPath(parent + "/" + path);
+            absPath = nix::absPath(path, parent);
 
             // for security, ensure that if the parent is a store path, it's inside it
-            if (!parent.rfind(store->storeDir, 0) && absPath.rfind(store->storeDir, 0))
-                throw BadStorePath("relative path '%s' points outside of its parent's store path %s, this is a security violation", path, parent);
+            if (store->isInStore(parent) && !isInDir(absPath, parent))
+                throw BadStorePath("relative path '%s' [%s] points outside of its parent's store path '%s'", path, absPath, parent);
         } else
             absPath = path;
 
+        Activity act(*logger, lvlTalkative, actUnknown, fmt("copying '%s'", absPath));
+
         // FIXME: check whether access to 'path' is allowed.
         auto storePath = store->maybeParseStorePath(absPath);
 
diff --git a/tests/flakes.sh b/tests/flakes.sh
index 2ede7f72c..26cdf27b7 100644
--- a/tests/flakes.sh
+++ b/tests/flakes.sh
@@ -766,7 +766,7 @@ cat > $flakeFollowsA/flake.nix <<EOF
 {
     description = "Flake A";
     inputs = {
-        B.url = "path:./../../flakeB";
+        B.url = "path:../flakeB";
     };
     outputs = { ... }: {};
 }
@@ -774,7 +774,7 @@ EOF
 
 git -C $flakeFollowsA add flake.nix
 
-nix flake lock $flakeFollowsA 2>&1 | grep 'this is a security violation'
+nix flake lock $flakeFollowsA 2>&1 | grep 'points outside'
 
 # Test flake in store does not evaluate
 rm -rf $badFlakeDir

From 06557299b30f53c6d4a1a2e3068f36d9ef3df904 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 21 Sep 2021 13:45:11 +0200
Subject: [PATCH 015/567] Allow relative paths anywhere into the parent's store
 path

---
 src/libfetchers/path.cc | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/libfetchers/path.cc b/src/libfetchers/path.cc
index b35c04cfc..fb5702c4c 100644
--- a/src/libfetchers/path.cc
+++ b/src/libfetchers/path.cc
@@ -95,8 +95,11 @@ struct PathInputScheme : InputScheme
             absPath = nix::absPath(path, parent);
 
             // for security, ensure that if the parent is a store path, it's inside it
-            if (store->isInStore(parent) && !isInDir(absPath, parent))
-                throw BadStorePath("relative path '%s' [%s] points outside of its parent's store path '%s'", path, absPath, parent);
+            if (store->isInStore(parent)) {
+                auto storePath = store->printStorePath(store->toStorePath(parent).first);
+                if (!isInDir(absPath, storePath))
+                    throw BadStorePath("relative path '%s' points outside of its parent's store path '%s'", path, storePath);
+            }
         } else
             absPath = path;
 

From 60cc975d22c193cd70cc4e8d3fb5643728aec418 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 21 Sep 2021 14:07:16 +0200
Subject: [PATCH 016/567] Set input parent at construction time

---
 src/libexpr/flake/flake.cc    | 27 +++++++++++++++------------
 src/libexpr/flake/flakeref.cc |  6 +++++-
 2 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 6893f157e..492b47115 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -89,10 +89,12 @@ static void expectType(EvalState & state, ValueType type,
 }
 
 static std::map<FlakeId, FlakeInput> parseFlakeInputs(
-    EvalState & state, Value * value, const Pos & pos);
+    EvalState & state, Value * value, const Pos & pos,
+    const std::optional<Path> & baseDir);
 
 static FlakeInput parseFlakeInput(EvalState & state,
-    const std::string & inputName, Value * value, const Pos & pos)
+    const std::string & inputName, Value * value, const Pos & pos,
+    const std::optional<Path> & baseDir)
 {
     expectType(state, nAttrs, *value, pos);
 
@@ -116,7 +118,7 @@ static FlakeInput parseFlakeInput(EvalState & state,
                 expectType(state, nBool, *attr.value, *attr.pos);
                 input.isFlake = attr.value->boolean;
             } else if (attr.name == sInputs) {
-                input.overrides = parseFlakeInputs(state, attr.value, *attr.pos);
+                input.overrides = parseFlakeInputs(state, attr.value, *attr.pos, baseDir);
             } else if (attr.name == sFollows) {
                 expectType(state, nString, *attr.value, *attr.pos);
                 input.follows = parseInputPath(attr.value->string.s);
@@ -154,7 +156,7 @@ static FlakeInput parseFlakeInput(EvalState & state,
         if (!attrs.empty())
             throw Error("unexpected flake input attribute '%s', at %s", attrs.begin()->first, pos);
         if (url)
-            input.ref = parseFlakeRef(*url, {}, true);
+            input.ref = parseFlakeRef(*url, baseDir, true);
     }
 
     if (!input.follows && !input.ref)
@@ -164,7 +166,8 @@ static FlakeInput parseFlakeInput(EvalState & state,
 }
 
 static std::map<FlakeId, FlakeInput> parseFlakeInputs(
-    EvalState & state, Value * value, const Pos & pos)
+    EvalState & state, Value * value, const Pos & pos,
+    const std::optional<Path> & baseDir)
 {
     std::map<FlakeId, FlakeInput> inputs;
 
@@ -175,7 +178,8 @@ static std::map<FlakeId, FlakeInput> parseFlakeInputs(
             parseFlakeInput(state,
                 inputAttr.name,
                 inputAttr.value,
-                *inputAttr.pos));
+                *inputAttr.pos,
+                baseDir));
     }
 
     return inputs;
@@ -191,7 +195,8 @@ static Flake getFlake(
         state, originalRef, allowLookup, flakeCache);
 
     // Guard against symlink attacks.
-    auto flakeFile = canonPath(sourceInfo.actualPath + "/" + lockedRef.subdir + "/flake.nix");
+    auto flakeDir = canonPath(sourceInfo.actualPath + "/" + lockedRef.subdir);
+    auto flakeFile = canonPath(flakeDir + "/flake.nix");
     if (!isInDir(flakeFile, sourceInfo.actualPath))
         throw Error("'flake.nix' file of flake '%s' escapes from '%s'",
             lockedRef, state.store->printStorePath(sourceInfo.storePath));
@@ -219,7 +224,7 @@ static Flake getFlake(
     auto sInputs = state.symbols.create("inputs");
 
     if (auto inputs = vInfo.attrs->get(sInputs))
-        flake.inputs = parseFlakeInputs(state, inputs->value, *inputs->pos);
+        flake.inputs = parseFlakeInputs(state, inputs->value, *inputs->pos, flakeDir);
 
     auto sOutputs = state.symbols.create("outputs");
 
@@ -488,10 +493,8 @@ LockedFlake lockFlake(
 
                             // If this input is a path, recurse it down.
                             // This allows us to resolve path inputs relative to the current flake.
-                            if (localRef.input.getType() == "path") {
-                                localRef.input.parent = parentPath;
-                                localPath = canonPath(parentPath + "/" + *input.ref->input.getSourcePath());
-                            }
+                            if (localRef.input.getType() == "path")
+                                localPath = absPath(*input.ref->input.getSourcePath(), parentPath);
 
                             auto inputFlake = getFlake(state, localRef, useRegistries, flakeCache);
 
diff --git a/src/libexpr/flake/flakeref.cc b/src/libexpr/flake/flakeref.cc
index 833e8a776..29128d789 100644
--- a/src/libexpr/flake/flakeref.cc
+++ b/src/libexpr/flake/flakeref.cc
@@ -172,8 +172,12 @@ std::pair<FlakeRef, std::string> parseFlakeRefWithFragment(
         auto parsedURL = parseURL(url);
         std::string fragment;
         std::swap(fragment, parsedURL.fragment);
+
+        auto input = Input::fromURL(parsedURL);
+        input.parent = baseDir;
+
         return std::make_pair(
-            FlakeRef(Input::fromURL(parsedURL), get(parsedURL.query, "dir").value_or("")),
+            FlakeRef(std::move(input), get(parsedURL.query, "dir").value_or("")),
             fragment);
     }
 }

From 033081aec29e33428b338cbe081e1df86337a3cd Mon Sep 17 00:00:00 2001
From: "Travis A. Everett" <travis.a.everett@gmail.com>
Date: Tue, 21 Sep 2021 13:38:29 -0500
Subject: [PATCH 017/567] fix install on macOS monterey

---
 scripts/install-darwin-multi-user.sh | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/scripts/install-darwin-multi-user.sh b/scripts/install-darwin-multi-user.sh
index a5166de64..32a12f2ee 100644
--- a/scripts/install-darwin-multi-user.sh
+++ b/scripts/install-darwin-multi-user.sh
@@ -13,11 +13,22 @@ NIX_BUILD_USER_NAME_TEMPLATE="_nixbld%d"
 read_only_root() {
     # this touch command ~should~ always produce an error
     # as of this change I confirmed /usr/bin/touch emits:
+    # "touch: /: Operation not permitted" Monterey
     # "touch: /: Read-only file system" Catalina+ and Big Sur
     # "touch: /: Permission denied" Mojave
     # (not matching prefix for compat w/ coreutils touch in case using
     # an explicit path causes problems; its prefix differs)
-    [[ "$(/usr/bin/touch / 2>&1)" = *"Read-only file system" ]]
+    case "$(/usr/bin/touch / 2>&1)" in
+        *"Read-only file system") # Catalina, Big Sur
+            return 0
+            ;;
+        *"Operation not permitted") # Monterey
+            return 0
+            ;;
+        *)
+            return 1
+            ;;
+    esac
 
     # Avoiding the slow semantic way to get this information (~330ms vs ~8ms)
     # unless using touch causes problems. Just in case, that approach is:

From bcd73ebf60bb9ba6cb09f8df4366d5474c16e4a4 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 22 Sep 2021 12:14:50 +0200
Subject: [PATCH 018/567] Add missing #include

Fixes #5282.
---
 src/libstore/build/local-derivation-goal.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 518edae9c..de4c95e8e 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -24,6 +24,7 @@
 #include <sys/mman.h>
 #include <sys/utsname.h>
 #include <sys/resource.h>
+#include <sys/socket.h>
 
 #if HAVE_STATVFS
 #include <sys/statvfs.h>

From ff28fffce26bba37685f7e230d1285e7d034f748 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 22 Sep 2021 14:00:56 +0200
Subject: [PATCH 019/567] Don't cache realiseContext() errors

Errors that depend on the configuration (such as whether
allow-import-from-derivation is set) should not be cached.
---
 src/libexpr/primops.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 8a087a781..c98a30177 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -52,7 +52,8 @@ void EvalState::realiseContext(const PathSet & context)
     if (drvs.empty()) return;
 
     if (!evalSettings.enableImportFromDerivation)
-        throw EvalError("attempted to realize '%1%' during evaluation but 'allow-import-from-derivation' is false",
+        throw Error(
+            "cannot build '%1%' during evaluation because the option 'allow-import-from-derivation' is disabled",
             store->printStorePath(drvs.begin()->drvPath));
 
     /* For performance, prefetch all substitute info. */

From 8fdb1d057ac72d07b9e8c6e522d4d7f0a8bdf352 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 22 Sep 2021 14:12:31 +0200
Subject: [PATCH 020/567] Quiet

---
 doc/manual/local.mk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/manual/local.mk b/doc/manual/local.mk
index 5e61b2671..a8c52f841 100644
--- a/doc/manual/local.mk
+++ b/doc/manual/local.mk
@@ -92,7 +92,7 @@ doc/manual/generated/man1/nix3-manpages: $(d)/src/command-ref/new-cli
 	  lowdown -sT man -M section=1 $$tmpFile -o $(DESTDIR)$$(dirname $@)/$$name.1; \
 	  rm $$tmpFile; \
 	done
-	touch $@
+	@touch $@
 
 $(docdir)/manual/index.html: $(MANUAL_SRCS) $(d)/book.toml $(d)/custom.css $(d)/src/SUMMARY.md $(d)/src/command-ref/new-cli $(d)/src/command-ref/conf-file.md $(d)/src/expressions/builtins.md $(call rwildcard, $(d)/src, *.md)
 	$(trace-gen) RUST_LOG=warn mdbook build doc/manual -d $(DESTDIR)$(docdir)/manual

From d8c10028d96d49b2c783fe279daa91402e8a91da Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 22 Sep 2021 14:15:35 +0200
Subject: [PATCH 021/567] Make setDefault() typed

---
 src/libstore/binary-cache-store.cc      | 4 ++--
 src/libstore/http-binary-cache-store.cc | 4 ++--
 src/libstore/s3-binary-cache-store.cc   | 4 ++--
 src/libutil/config.cc                   | 5 -----
 src/libutil/config.hh                   | 3 +--
 5 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index 74eb0a9ab..3a6be541f 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -52,9 +52,9 @@ void BinaryCacheStore::init()
                     throw Error("binary cache '%s' is for Nix stores with prefix '%s', not '%s'",
                         getUri(), value, storeDir);
             } else if (name == "WantMassQuery") {
-                wantMassQuery.setDefault(value == "1" ? "true" : "false");
+                wantMassQuery.setDefault(value == "1");
             } else if (name == "Priority") {
-                priority.setDefault(fmt("%d", std::stoi(value)));
+                priority.setDefault(std::stoi(value));
             }
         }
     }
diff --git a/src/libstore/http-binary-cache-store.cc b/src/libstore/http-binary-cache-store.cc
index 0a3afcd51..605ec4b28 100644
--- a/src/libstore/http-binary-cache-store.cc
+++ b/src/libstore/http-binary-cache-store.cc
@@ -57,8 +57,8 @@ public:
     {
         // FIXME: do this lazily?
         if (auto cacheInfo = diskCache->cacheExists(cacheUri)) {
-            wantMassQuery.setDefault(cacheInfo->wantMassQuery ? "true" : "false");
-            priority.setDefault(fmt("%d", cacheInfo->priority));
+            wantMassQuery.setDefault(cacheInfo->wantMassQuery);
+            priority.setDefault(cacheInfo->priority);
         } else {
             try {
                 BinaryCacheStore::init();
diff --git a/src/libstore/s3-binary-cache-store.cc b/src/libstore/s3-binary-cache-store.cc
index 51d86c4e6..7accad7f4 100644
--- a/src/libstore/s3-binary-cache-store.cc
+++ b/src/libstore/s3-binary-cache-store.cc
@@ -232,8 +232,8 @@ struct S3BinaryCacheStoreImpl : virtual S3BinaryCacheStoreConfig, public virtual
     void init() override
     {
         if (auto cacheInfo = diskCache->cacheExists(getUri())) {
-            wantMassQuery.setDefault(cacheInfo->wantMassQuery ? "true" : "false");
-            priority.setDefault(fmt("%d", cacheInfo->priority));
+            wantMassQuery.setDefault(cacheInfo->wantMassQuery);
+            priority.setDefault(cacheInfo->priority);
         } else {
             BinaryCacheStore::init();
             diskCache->createCache(getUri(), storeDir, wantMassQuery, priority);
diff --git a/src/libutil/config.cc b/src/libutil/config.cc
index 2a5f913e6..c247c7dae 100644
--- a/src/libutil/config.cc
+++ b/src/libutil/config.cc
@@ -177,11 +177,6 @@ AbstractSetting::AbstractSetting(
 {
 }
 
-void AbstractSetting::setDefault(const std::string & str)
-{
-    if (!overridden) set(str);
-}
-
 nlohmann::json AbstractSetting::toJSON()
 {
     return nlohmann::json(toJSONObject());
diff --git a/src/libutil/config.hh b/src/libutil/config.hh
index df5c2226f..736810bf3 100644
--- a/src/libutil/config.hh
+++ b/src/libutil/config.hh
@@ -194,8 +194,6 @@ public:
 
     bool overridden = false;
 
-    void setDefault(const std::string & str);
-
 protected:
 
     AbstractSetting(
@@ -253,6 +251,7 @@ public:
     bool operator !=(const T & v2) const { return value != v2; }
     void operator =(const T & v) { assign(v); }
     virtual void assign(const T & v) { value = v; }
+    void setDefault(const T & v) { if (!overridden) value = v; }
 
     void set(const std::string & str, bool append = false) override;
 

From 8623a5b595af57c57e569d3b1e792aa640ceb980 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 22 Sep 2021 17:15:07 +0200
Subject: [PATCH 022/567] Disable IFD selectively

It's now disabled by default for the following:

* 'nix search' (this was already implied by read-only mode)
* 'nix flake show'
* 'nix flake check', but only on the hydraJobs output
---
 src/nix/flake.cc  | 39 ++++++++++++++++++++++++++++++---------
 src/nix/search.cc |  1 +
 2 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index a127c3ac0..7d7ada707 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -131,8 +131,18 @@ static void enumerateOutputs(EvalState & state, Value & vFlake,
 
     state.forceAttrs(*aOutputs->value);
 
-    for (auto & attr : *aOutputs->value->attrs)
-        callback(attr.name, *attr.value, *attr.pos);
+    auto sHydraJobs = state.symbols.create("hydraJobs");
+
+    /* Hack: ensure that hydraJobs is evaluated before anything
+       else. This way we can disable IFD for hydraJobs and then enable
+       it for other outputs. */
+    if (auto attr = aOutputs->value->attrs->get(sHydraJobs))
+        callback(attr->name, *attr->value, *attr->pos);
+
+    for (auto & attr : *aOutputs->value->attrs) {
+        if (attr.name != sHydraJobs)
+            callback(attr.name, *attr.value, *attr.pos);
+    }
 }
 
 struct CmdFlakeMetadata : FlakeCommand, MixJSON
@@ -269,7 +279,10 @@ struct CmdFlakeCheck : FlakeCommand
 
     void run(nix::ref<nix::Store> store) override
     {
-        settings.readOnlyMode = !build;
+        if (!build) {
+            settings.readOnlyMode = true;
+            evalSettings.enableImportFromDerivation.setDefault(false);
+        }
 
         auto state = getEvalState();
 
@@ -381,9 +394,13 @@ struct CmdFlakeCheck : FlakeCommand
 
                 for (auto & attr : *v.attrs) {
                     state->forceAttrs(*attr.value, *attr.pos);
-                    if (!state->isDerivation(*attr.value))
-                        checkHydraJobs(attrPath + "." + (std::string) attr.name,
-                            *attr.value, *attr.pos);
+                    auto attrPath2 = attrPath + "." + (std::string) attr.name;
+                    if (state->isDerivation(*attr.value)) {
+                        Activity act(*logger, lvlChatty, actUnknown,
+                            fmt("checking Hydra job '%s'", attrPath2));
+                        checkDerivation(attrPath2, *attr.value, *attr.pos);
+                    } else
+                        checkHydraJobs(attrPath2, *attr.value, *attr.pos);
                 }
 
             } catch (Error & e) {
@@ -447,8 +464,8 @@ struct CmdFlakeCheck : FlakeCommand
                 if (!v.isLambda())
                     throw Error("bundler must be a function");
                 if (!v.lambda.fun->formals ||
-                    v.lambda.fun->formals->argNames.find(state->symbols.create("program")) == v.lambda.fun->formals->argNames.end() ||
-                    v.lambda.fun->formals->argNames.find(state->symbols.create("system")) == v.lambda.fun->formals->argNames.end())
+                    !v.lambda.fun->formals->argNames.count(state->symbols.create("program")) ||
+                    !v.lambda.fun->formals->argNames.count(state->symbols.create("system")))
                     throw Error("bundler must take formal arguments 'program' and 'system'");
             } catch (Error & e) {
                 e.addTrace(pos, hintfmt("while checking the template '%s'", attrPath));
@@ -469,6 +486,8 @@ struct CmdFlakeCheck : FlakeCommand
                         fmt("checking flake output '%s'", name));
 
                     try {
+                        evalSettings.enableImportFromDerivation.setDefault(name != "hydraJobs");
+
                         state->forceValue(vOutput, pos);
 
                         if (name == "checks") {
@@ -603,7 +622,7 @@ struct CmdFlakeCheck : FlakeCommand
             store->buildPaths(drvPaths);
         }
         if (hasErrors)
-            throw Error("Some errors were encountered during the evaluation");
+            throw Error("some errors were encountered during the evaluation");
     }
 };
 
@@ -873,6 +892,8 @@ struct CmdFlakeShow : FlakeCommand, MixJSON
 
     void run(nix::ref<nix::Store> store) override
     {
+        evalSettings.enableImportFromDerivation.setDefault(false);
+
         auto state = getEvalState();
         auto flake = std::make_shared<LockedFlake>(lockFlake());
 
diff --git a/src/nix/search.cc b/src/nix/search.cc
index c52a48d4e..0d8fdd5c2 100644
--- a/src/nix/search.cc
+++ b/src/nix/search.cc
@@ -62,6 +62,7 @@ struct CmdSearch : InstallableCommand, MixJSON
     void run(ref<Store> store) override
     {
         settings.readOnlyMode = true;
+        evalSettings.enableImportFromDerivation.setDefault(false);
 
         // Empty search string should match all packages
         // Use "^" here instead of ".*" due to differences in resulting highlighting

From d1bf7431bbb9c38bdb577661d8511d506a3955c4 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 22 Sep 2021 17:25:25 +0200
Subject: [PATCH 023/567] Revert "Merge pull request #4922 from
 nrdxp/default-submodules"

This reverts commit 6678e98411cd3bfe8143a4ba1b35d1451babce32, reversing
changes made to 90b2dd570cbd8313a8cf45b3cf66ddef2bb06e07.
---
 src/libexpr/primops/fetchTree.cc |  2 +-
 src/libfetchers/git.cc           |  2 +-
 tests/fetchGitSubmodules.sh      | 12 ++++++------
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index d004b701b..06bdec003 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -36,7 +36,7 @@ void emitTreeAttrs(
 
     if (input.getType() == "git")
         mkBool(*state.allocAttr(v, state.symbols.create("submodules")),
-            fetchers::maybeGetBoolAttr(input.attrs, "submodules").value_or(true));
+            fetchers::maybeGetBoolAttr(input.attrs, "submodules").value_or(false));
 
     if (!forceDirty) {
 
diff --git a/src/libfetchers/git.cc b/src/libfetchers/git.cc
index 5af38dde9..bfc58f7a1 100644
--- a/src/libfetchers/git.cc
+++ b/src/libfetchers/git.cc
@@ -173,7 +173,7 @@ struct GitInputScheme : InputScheme
         std::string name = input.getName();
 
         bool shallow = maybeGetBoolAttr(input.attrs, "shallow").value_or(false);
-        bool submodules = maybeGetBoolAttr(input.attrs, "submodules").value_or(true);
+        bool submodules = maybeGetBoolAttr(input.attrs, "submodules").value_or(false);
         bool allRefs = maybeGetBoolAttr(input.attrs, "allRefs").value_or(false);
 
         std::string cacheType = "git";
diff --git a/tests/fetchGitSubmodules.sh b/tests/fetchGitSubmodules.sh
index 03d46088e..5f104355f 100644
--- a/tests/fetchGitSubmodules.sh
+++ b/tests/fetchGitSubmodules.sh
@@ -42,8 +42,8 @@ r1=$(nix eval --raw --expr "(builtins.fetchGit { url = file://$rootRepo; rev = \
 r2=$(nix eval --raw --expr "(builtins.fetchGit { url = file://$rootRepo; rev = \"$rev\"; submodules = false; }).outPath")
 r3=$(nix eval --raw --expr "(builtins.fetchGit { url = file://$rootRepo; rev = \"$rev\"; submodules = true; }).outPath")
 
-[[ $r1 == $r3 ]]
-[[ $r2 != $r1 ]]
+[[ $r1 == $r2 ]]
+[[ $r2 != $r3 ]]
 
 r4=$(nix eval --raw --expr "(builtins.fetchGit { url = file://$rootRepo; ref = \"master\"; rev = \"$rev\"; }).outPath")
 r5=$(nix eval --raw --expr "(builtins.fetchGit { url = file://$rootRepo; ref = \"master\"; rev = \"$rev\"; submodules = false; }).outPath")
@@ -52,13 +52,13 @@ r7=$(nix eval --raw --expr "(builtins.fetchGit { url = $rootRepo; ref = \"master
 r8=$(nix eval --raw --expr "(builtins.fetchGit { url = $rootRepo; rev = \"$rev\"; submodules = true; }).outPath")
 
 [[ $r1 == $r4 ]]
-[[ $r4 == $r6 ]]
+[[ $r4 == $r5 ]]
 [[ $r3 == $r6 ]]
 [[ $r6 == $r7 ]]
 [[ $r7 == $r8 ]]
 
 have_submodules=$(nix eval --expr "(builtins.fetchGit { url = $rootRepo; rev = \"$rev\"; }).submodules")
-[[ $have_submodules == true ]]
+[[ $have_submodules == false ]]
 
 have_submodules=$(nix eval --expr "(builtins.fetchGit { url = $rootRepo; rev = \"$rev\"; submodules = false; }).submodules")
 [[ $have_submodules == false ]]
@@ -66,8 +66,8 @@ have_submodules=$(nix eval --expr "(builtins.fetchGit { url = $rootRepo; rev = \
 have_submodules=$(nix eval --expr "(builtins.fetchGit { url = $rootRepo; rev = \"$rev\"; submodules = true; }).submodules")
 [[ $have_submodules == true ]]
 
-pathWithoutSubmodules=$(nix eval --raw --expr "(builtins.fetchGit { url = file://$rootRepo; rev = \"$rev\"; submodules = false; }).outPath")
-pathWithSubmodules=$(nix eval --raw --expr "(builtins.fetchGit { url = file://$rootRepo; rev = \"$rev\"; }).outPath")
+pathWithoutSubmodules=$(nix eval --raw --expr "(builtins.fetchGit { url = file://$rootRepo; rev = \"$rev\"; }).outPath")
+pathWithSubmodules=$(nix eval --raw --expr "(builtins.fetchGit { url = file://$rootRepo; rev = \"$rev\"; submodules = true; }).outPath")
 pathWithSubmodulesAgain=$(nix eval --raw --expr "(builtins.fetchGit { url = file://$rootRepo; rev = \"$rev\"; submodules = true; }).outPath")
 pathWithSubmodulesAgainWithRef=$(nix eval --raw --expr "(builtins.fetchGit { url = file://$rootRepo; ref = \"master\"; rev = \"$rev\"; submodules = true; }).outPath")
 

From 9d67332e4b8d75a101b8cf6e1d7e4dc8e99e964a Mon Sep 17 00:00:00 2001
From: Geoff Reedy <geoff@programmer-monk.net>
Date: Wed, 22 Sep 2021 20:30:31 -0600
Subject: [PATCH 024/567] Better eval error locations for interpolation and +

Previously, type or coercion errors for string interpolation, path
interpolation, and plus expressions were always reported at the
beginning of the outer expression. This leads to confusing evaluation
error messages making it hard to accurately diagnose and then fix the
error.

For example, errors were reported as follows.

```
cannot coerce an integer to a string
1| let foo = 7; in "bar" + foo
 |                 ^

cannot add a string to an integer
1| let foo = "bar"; in 4 + foo
 |                     ^

cannot coerce an integer to a string
1| let foo = 7; in "x${foo}"
 |                  ^
```

This commit changes the ExprConcatStrings expression vector to store a
sequence of expressions *and* their expansion locations so that error
locations can be reported accurately. For interpolation, the error is
reported at the beginning of the entire `${foo}`, not at the beginning
of `foo` because I thought this was slightly clearer. The previous
errors are now reported as:

```
cannot coerce an integer to a string
1| let foo = 7; in "bar" + foo
 |                         ^

cannot add a string to an integer
1| let foo = "bar"; in 4 + foo
 |                         ^

cannot coerce an integer to a string
1| let foo = 7; in "x${foo}"
 |                   ^
```

The error is reported at this kind of precise location even for
multi-line indented strings.

This probably helps with at least some of the cases mentioned in #561
---
 src/libexpr/eval.cc    |  8 ++++----
 src/libexpr/nixexpr.cc |  4 ++--
 src/libexpr/nixexpr.hh |  4 ++--
 src/libexpr/parser.y   | 38 +++++++++++++++++++-------------------
 4 files changed, 27 insertions(+), 27 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index bc41a2cd9..3f18ad1ed 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -1577,7 +1577,7 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
     bool first = !forceString;
     ValueType firstType = nString;
 
-    for (auto & i : *es) {
+    for (auto & [i_pos, i] : *es) {
         Value vTmp;
         i->eval(state, env, vTmp);
 
@@ -1598,19 +1598,19 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
                 nf = n;
                 nf += vTmp.fpoint;
             } else
-                throwEvalError(pos, "cannot add %1% to an integer", showType(vTmp));
+                throwEvalError(i_pos, "cannot add %1% to an integer", showType(vTmp));
         } else if (firstType == nFloat) {
             if (vTmp.type() == nInt) {
                 nf += vTmp.integer;
             } else if (vTmp.type() == nFloat) {
                 nf += vTmp.fpoint;
             } else
-                throwEvalError(pos, "cannot add %1% to a float", showType(vTmp));
+                throwEvalError(i_pos, "cannot add %1% to a float", showType(vTmp));
         } else
             /* skip canonization of first path, which would only be not
             canonized in the first place if it's coming from a ./${foo} type
             path */
-            s << state.coerceToString(pos, vTmp, context, false, firstType == nString, !first);
+            s << state.coerceToString(i_pos, vTmp, context, false, firstType == nString, !first);
 
         first = false;
     }
diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc
index 492b819e7..15d963d55 100644
--- a/src/libexpr/nixexpr.cc
+++ b/src/libexpr/nixexpr.cc
@@ -181,7 +181,7 @@ void ExprConcatStrings::show(std::ostream & str) const
     str << "(";
     for (auto & i : *es) {
         if (first) first = false; else str << " + ";
-        str << *i;
+        str << i.second;
     }
     str << ")";
 }
@@ -413,7 +413,7 @@ void ExprOpNot::bindVars(const StaticEnv & env)
 void ExprConcatStrings::bindVars(const StaticEnv & env)
 {
     for (auto & i : *es)
-        i->bindVars(env);
+        i.second->bindVars(env);
 }
 
 void ExprPos::bindVars(const StaticEnv & env)
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index 51a14cd59..d3f7f5bd6 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -321,8 +321,8 @@ struct ExprConcatStrings : Expr
 {
     Pos pos;
     bool forceString;
-    vector<Expr *> * es;
-    ExprConcatStrings(const Pos & pos, bool forceString, vector<Expr *> * es)
+    vector<std::pair<Pos, Expr *> > * es;
+    ExprConcatStrings(const Pos & pos, bool forceString, vector<std::pair<Pos, Expr *> > * es)
         : pos(pos), forceString(forceString), es(es) { };
     COMMON_METHODS
 };
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index e3749783a..c21d7b033 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -154,7 +154,7 @@ static void addFormal(const Pos & pos, Formals * formals, const Formal & formal)
 }
 
 
-static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols, vector<Expr *> & es)
+static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols, vector<std::pair<Pos, Expr *> > & es)
 {
     if (es.empty()) return new ExprString(symbols.create(""));
 
@@ -164,7 +164,7 @@ static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols, vector<Ex
     bool atStartOfLine = true; /* = seen only whitespace in the current line */
     size_t minIndent = 1000000;
     size_t curIndent = 0;
-    for (auto & i : es) {
+    for (auto & [i_pos, i] : es) {
         ExprIndStr * e = dynamic_cast<ExprIndStr *>(i);
         if (!e) {
             /* Anti-quotations end the current start-of-line whitespace. */
@@ -194,12 +194,12 @@ static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols, vector<Ex
     }
 
     /* Strip spaces from each line. */
-    vector<Expr *> * es2 = new vector<Expr *>;
+    vector<std::pair<Pos, Expr *> > * es2 = new vector<std::pair<Pos, Expr *> >;
     atStartOfLine = true;
     size_t curDropped = 0;
     size_t n = es.size();
-    for (vector<Expr *>::iterator i = es.begin(); i != es.end(); ++i, --n) {
-        ExprIndStr * e = dynamic_cast<ExprIndStr *>(*i);
+    for (vector<std::pair<Pos, Expr *> >::iterator i = es.begin(); i != es.end(); ++i, --n) {
+        ExprIndStr * e = dynamic_cast<ExprIndStr *>(i->second);
         if (!e) {
             atStartOfLine = false;
             curDropped = 0;
@@ -236,11 +236,11 @@ static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols, vector<Ex
                 s2 = string(s2, 0, p + 1);
         }
 
-        es2->push_back(new ExprString(symbols.create(s2)));
+        es2->emplace_back(i->first, new ExprString(symbols.create(s2)));
     }
 
     /* If this is a single string, then don't do a concatenation. */
-    return es2->size() == 1 && dynamic_cast<ExprString *>((*es2)[0]) ? (*es2)[0] : new ExprConcatStrings(pos, true, es2);
+    return es2->size() == 1 && dynamic_cast<ExprString *>((*es2)[0].second) ? (*es2)[0].second : new ExprConcatStrings(pos, true, es2);
 }
 
 
@@ -279,7 +279,7 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * err
   char * path;
   char * uri;
   std::vector<nix::AttrName> * attrNames;
-  std::vector<nix::Expr *> * string_parts;
+  std::vector<std::pair<nix::Pos, nix::Expr *> > * string_parts;
 }
 
 %type <e> start expr expr_function expr_if expr_op
@@ -366,7 +366,7 @@ expr_op
   | expr_op UPDATE expr_op { $$ = new ExprOpUpdate(CUR_POS, $1, $3); }
   | expr_op '?' attrpath { $$ = new ExprOpHasAttr($1, *$3); }
   | expr_op '+' expr_op
-    { $$ = new ExprConcatStrings(CUR_POS, false, new vector<Expr *>({$1, $3})); }
+    { $$ = new ExprConcatStrings(CUR_POS, false, new vector<std::pair<Pos, Expr *> >({{makeCurPos(@1, data), $1}, {makeCurPos(@3, data), $3}})); }
   | expr_op '-' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__sub")), $1), $3); }
   | expr_op '*' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__mul")), $1), $3); }
   | expr_op '/' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__div")), $1), $3); }
@@ -407,7 +407,7 @@ expr_simple
   }
   | path_start PATH_END { $$ = $1; }
   | path_start string_parts_interpolated PATH_END {
-      $2->insert($2->begin(), $1);
+      $2->insert($2->begin(), {makeCurPos(@1, data), $1});
       $$ = new ExprConcatStrings(CUR_POS, false, $2);
   }
   | SPATH {
@@ -445,13 +445,13 @@ string_parts
   ;
 
 string_parts_interpolated
-  : string_parts_interpolated STR { $$ = $1; $1->push_back($2); }
-  | string_parts_interpolated DOLLAR_CURLY expr '}' { $$ = $1; $1->push_back($3); }
-  | DOLLAR_CURLY expr '}' { $$ = new vector<Expr *>; $$->push_back($2); }
+  : string_parts_interpolated STR { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $2); }
+  | string_parts_interpolated DOLLAR_CURLY expr '}' { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $3); }
+  | DOLLAR_CURLY expr '}' { $$ = new vector<std::pair<Pos, Expr *> >; $$->emplace_back(makeCurPos(@1, data), $2); }
   | STR DOLLAR_CURLY expr '}' {
-      $$ = new vector<Expr *>;
-      $$->push_back($1);
-      $$->push_back($3);
+      $$ = new vector<std::pair<Pos, Expr *> >;
+      $$->emplace_back(makeCurPos(@1, data), $1);
+      $$->emplace_back(makeCurPos(@2, data), $3);
     }
   ;
 
@@ -470,9 +470,9 @@ path_start
   ;
 
 ind_string_parts
-  : ind_string_parts IND_STR { $$ = $1; $1->push_back($2); }
-  | ind_string_parts DOLLAR_CURLY expr '}' { $$ = $1; $1->push_back($3); }
-  | { $$ = new vector<Expr *>; }
+  : ind_string_parts IND_STR { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $2); }
+  | ind_string_parts DOLLAR_CURLY expr '}' { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $3); }
+  | { $$ = new vector<std::pair<Pos, Expr *> >; }
   ;
 
 binds

From 198fa786a11d8ccbbb3d9ef5a3d5de4fcf9e89ef Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 23 Sep 2021 11:42:33 +0200
Subject: [PATCH 025/567] Add some more instrumentation

---
 src/libstore/build/local-derivation-goal.cc | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index de4c95e8e..789a2ae65 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -938,7 +938,10 @@ void LocalDerivationGoal::startBuilder()
             try {
                 return readLine(builderOut.readSide.get());
             } catch (Error & e) {
-                e.addTrace({}, "while waiting for the build environment to initialize (previous messages: %s)",
+                auto status = pid.wait();
+                e.addTrace({}, "while waiting for the build environment for '%s' to initialize (%s, previous messages: %s)",
+                    worker.store.printStorePath(drvPath),
+                    statusToString(status),
                     concatStringsSep("|", msgs));
                 throw e;
             }

From 60642aa5e2ca0af15b86cbd76d624bd39d549978 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 23 Sep 2021 12:07:50 +0200
Subject: [PATCH 026/567] Remove risky char *

---
 src/libstore/build/local-derivation-goal.cc | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 789a2ae65..23a5df85e 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -1835,7 +1835,7 @@ void LocalDerivationGoal::runChild()
         /* Fill in the arguments. */
         Strings args;
 
-        const char *builder = "invalid";
+        std::string builder = "invalid";
 
         if (drv->isBuiltin()) {
             ;
@@ -1961,13 +1961,13 @@ void LocalDerivationGoal::runChild()
                 }
                 args.push_back(drv->builder);
             } else {
-                builder = drv->builder.c_str();
+                builder = drv->builder;
                 args.push_back(std::string(baseNameOf(drv->builder)));
             }
         }
 #else
         else {
-            builder = drv->builder.c_str();
+            builder = drv->builder;
             args.push_back(std::string(baseNameOf(drv->builder)));
         }
 #endif
@@ -2023,9 +2023,9 @@ void LocalDerivationGoal::runChild()
             posix_spawnattr_setbinpref_np(&attrp, 1, &cpu, NULL);
         }
 
-        posix_spawn(NULL, builder, NULL, &attrp, stringsToCharPtrs(args).data(), stringsToCharPtrs(envStrs).data());
+        posix_spawn(NULL, builder.c_str(), NULL, &attrp, stringsToCharPtrs(args).data(), stringsToCharPtrs(envStrs).data());
 #else
-        execve(builder, stringsToCharPtrs(args).data(), stringsToCharPtrs(envStrs).data());
+        execve(builder.c_str(), stringsToCharPtrs(args).data(), stringsToCharPtrs(envStrs).data());
 #endif
 
         throw SysError("executing '%1%'", drv->builder);

From 994348e9e070a07d9f86ce876415f5484e5b7e66 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 23 Sep 2021 17:48:52 +0200
Subject: [PATCH 027/567] SSHStore / LegacySSHStore: Show a better error
 message if the remote is "nologin"

Instead of

  error: serialised integer 7161674624452356180 is too large for type 'j'

we now get

  error: 'nix-store --serve' protocol mismatch from 'sshtest@localhost', got 'This account is currently not available.'

Fixes https://github.com/NixOS/nixpkgs/issues/37287.
---
 src/libstore/legacy-ssh-store.cc | 15 ++++++++++++---
 src/libstore/remote-store.cc     | 12 ++++++++++--
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/src/libstore/legacy-ssh-store.cc b/src/libstore/legacy-ssh-store.cc
index 45eed5707..5d006f6e2 100644
--- a/src/libstore/legacy-ssh-store.cc
+++ b/src/libstore/legacy-ssh-store.cc
@@ -82,9 +82,18 @@ struct LegacySSHStore : public virtual LegacySSHStoreConfig, public virtual Stor
             conn->to << SERVE_MAGIC_1 << SERVE_PROTOCOL_VERSION;
             conn->to.flush();
 
-            unsigned int magic = readInt(conn->from);
-            if (magic != SERVE_MAGIC_2)
-                throw Error("protocol mismatch with 'nix-store --serve' on '%s'", host);
+            StringSink saved;
+            try {
+                TeeSource tee(conn->from, saved);
+                unsigned int magic = readInt(tee);
+                if (magic != SERVE_MAGIC_2)
+                    throw Error("'nix-store --serve' protocol mismatch from '%s'", host);
+            } catch (SerialisationError & e) {
+                conn->sshConn->in.close();
+                auto msg = conn->from.drain();
+                throw Error("'nix-store --serve' protocol mismatch from '%s', got '%s'",
+                    host, chomp(*saved.s + msg));
+            }
             conn->remoteVersion = readInt(conn->from);
             if (GET_PROTOCOL_MAJOR(conn->remoteVersion) != 0x200)
                 throw Error("unsupported 'nix-store --serve' protocol version on '%s'", host);
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index 73f590e7b..c71eb4631 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -162,8 +162,16 @@ void RemoteStore::initConnection(Connection & conn)
     try {
         conn.to << WORKER_MAGIC_1;
         conn.to.flush();
-        unsigned int magic = readInt(conn.from);
-        if (magic != WORKER_MAGIC_2) throw Error("protocol mismatch");
+        StringSink saved;
+        try {
+            TeeSource tee(conn.from, saved);
+            unsigned int magic = readInt(tee);
+            if (magic != WORKER_MAGIC_2)
+                throw Error("protocol mismatch");
+        } catch (SerialisationError & e) {
+            auto msg = conn.from.drain();
+            throw Error("protocol mismatch, got '%s'", chomp(*saved.s + msg));
+        }
 
         conn.from >> conn.daemonVersion;
         if (GET_PROTOCOL_MAJOR(conn.daemonVersion) != GET_PROTOCOL_MAJOR(PROTOCOL_VERSION))

From ea9df6fe51cf52a8e9106cd62a195bf185e6c5f6 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 23 Sep 2021 18:01:04 +0200
Subject: [PATCH 028/567] Shut down write side before draining the read side

This is important if the remote side *does* execute
nix-store/nix-daemon successfully, but stdout is polluted
(e.g. because the remote user's bashrc script prints something to
stdout). In that case we have to shutdown the write side to force the
remote nix process to exit.
---
 src/libstore/legacy-ssh-store.cc | 2 ++
 src/libstore/remote-store.cc     | 3 +++
 src/libstore/remote-store.hh     | 3 ++-
 src/libstore/ssh-store.cc        | 5 +++++
 src/libstore/uds-remote-store.cc | 6 ++++++
 src/libstore/uds-remote-store.hh | 6 ++++++
 6 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/libstore/legacy-ssh-store.cc b/src/libstore/legacy-ssh-store.cc
index 5d006f6e2..c660d7f5b 100644
--- a/src/libstore/legacy-ssh-store.cc
+++ b/src/libstore/legacy-ssh-store.cc
@@ -89,6 +89,8 @@ struct LegacySSHStore : public virtual LegacySSHStoreConfig, public virtual Stor
                 if (magic != SERVE_MAGIC_2)
                     throw Error("'nix-store --serve' protocol mismatch from '%s'", host);
             } catch (SerialisationError & e) {
+                /* In case the other side is waiting for our input,
+                   close it. */
                 conn->sshConn->in.close();
                 auto msg = conn->from.drain();
                 throw Error("'nix-store --serve' protocol mismatch from '%s', got '%s'",
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index c71eb4631..b57a4cb05 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -169,6 +169,9 @@ void RemoteStore::initConnection(Connection & conn)
             if (magic != WORKER_MAGIC_2)
                 throw Error("protocol mismatch");
         } catch (SerialisationError & e) {
+            /* In case the other side is waiting for our input, close
+               it. */
+            conn.closeWrite();
             auto msg = conn.from.drain();
             throw Error("protocol mismatch, got '%s'", chomp(*saved.s + msg));
         }
diff --git a/src/libstore/remote-store.hh b/src/libstore/remote-store.hh
index 8901c79fc..ac1eaa19e 100644
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@@ -125,7 +125,6 @@ public:
 
     struct Connection
     {
-        AutoCloseFD fd;
         FdSink to;
         FdSource from;
         unsigned int daemonVersion;
@@ -133,6 +132,8 @@ public:
 
         virtual ~Connection();
 
+        virtual void closeWrite() = 0;
+
         std::exception_ptr processStderr(Sink * sink = 0, Source * source = 0, bool flush = true);
     };
 
diff --git a/src/libstore/ssh-store.cc b/src/libstore/ssh-store.cc
index f2caf2aeb..bb03daef4 100644
--- a/src/libstore/ssh-store.cc
+++ b/src/libstore/ssh-store.cc
@@ -57,6 +57,11 @@ private:
     struct Connection : RemoteStore::Connection
     {
         std::unique_ptr<SSHMaster::Connection> sshConn;
+
+        void closeWrite() override
+        {
+            sshConn->in.close();
+        }
     };
 
     ref<RemoteStore::Connection> openConnection() override;
diff --git a/src/libstore/uds-remote-store.cc b/src/libstore/uds-remote-store.cc
index cac4fa036..cfadccf68 100644
--- a/src/libstore/uds-remote-store.cc
+++ b/src/libstore/uds-remote-store.cc
@@ -45,6 +45,12 @@ std::string UDSRemoteStore::getUri()
 }
 
 
+void UDSRemoteStore::Connection::closeWrite()
+{
+    shutdown(fd.get(), SHUT_WR);
+}
+
+
 ref<RemoteStore::Connection> UDSRemoteStore::openConnection()
 {
     auto conn = make_ref<Connection>();
diff --git a/src/libstore/uds-remote-store.hh b/src/libstore/uds-remote-store.hh
index ddc7716cd..f8dfcca70 100644
--- a/src/libstore/uds-remote-store.hh
+++ b/src/libstore/uds-remote-store.hh
@@ -40,6 +40,12 @@ public:
 
 private:
 
+    struct Connection : RemoteStore::Connection
+    {
+        AutoCloseFD fd;
+        void closeWrite() override;
+    };
+
     ref<RemoteStore::Connection> openConnection() override;
     std::optional<std::string> path;
 };

From 58856e86f639a5b07ccd2fd157bddd828127f200 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 24 Sep 2021 15:21:22 +0200
Subject: [PATCH 029/567] flake.lock: Update
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Flake lock file changes:

• Updated input 'lowdown-src':
    'github:kristapsdz/lowdown/b4483d0ef85990f54b864158ab786b4a5b3904fa' (2021-08-06)
  → 'github:kristapsdz/lowdown/0b85e777f3cdacf4210f0d624a0ceec8df612e05' (2021-09-23)
---
 flake.lock | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/flake.lock b/flake.lock
index d562728e7..c477e7678 100644
--- a/flake.lock
+++ b/flake.lock
@@ -3,16 +3,15 @@
     "lowdown-src": {
       "flake": false,
       "locked": {
-        "lastModified": 1628247802,
-        "narHash": "sha256-4XSXGYvKqogR7bubyqYNwBHYCtrIn6XRGXj6+u+BXNs=",
+        "lastModified": 1632391204,
+        "narHash": "sha256-zjyNA4ZmaaIbbmz2JZDqMgY7+P/uGF0nLg28Nxfg5kI=",
         "owner": "kristapsdz",
         "repo": "lowdown",
-        "rev": "b4483d0ef85990f54b864158ab786b4a5b3904fa",
+        "rev": "0b85e777f3cdacf4210f0d624a0ceec8df612e05",
         "type": "github"
       },
       "original": {
         "owner": "kristapsdz",
-        "ref": "VERSION_0_8_6",
         "repo": "lowdown",
         "type": "github"
       }

From aedbc7b683c3110bb9627cbea376953b766eaf3d Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 24 Sep 2021 15:21:41 +0200
Subject: [PATCH 030/567] Use latest lowdown

This improves list rendering
(https://github.com/kristapsdz/lowdown/issues/73).
---
 flake.nix              | 4 ++--
 src/libcmd/markdown.cc | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/flake.nix b/flake.nix
index 5f77e42d1..fc4836864 100644
--- a/flake.nix
+++ b/flake.nix
@@ -2,7 +2,7 @@
   description = "The purely functional package manager";
 
   inputs.nixpkgs.url = "nixpkgs/nixos-21.05-small";
-  inputs.lowdown-src = { url = "github:kristapsdz/lowdown/VERSION_0_8_6"; flake = false; };
+  inputs.lowdown-src = { url = "github:kristapsdz/lowdown"; flake = false; };
 
   outputs = { self, nixpkgs, lowdown-src }:
 
@@ -350,7 +350,7 @@
         };
 
         lowdown = with final; stdenv.mkDerivation rec {
-          name = "lowdown-0.8.6";
+          name = "lowdown-0.9.0";
 
           /*
           src = fetchurl {
diff --git a/src/libcmd/markdown.cc b/src/libcmd/markdown.cc
index 737356284..29bb4d31e 100644
--- a/src/libcmd/markdown.cc
+++ b/src/libcmd/markdown.cc
@@ -25,7 +25,7 @@ std::string renderMarkdownToTerminal(std::string_view markdown)
     Finally freeDoc([&]() { lowdown_doc_free(doc); });
 
     size_t maxn = 0;
-    auto node = lowdown_doc_parse(doc, &maxn, markdown.data(), markdown.size());
+    auto node = lowdown_doc_parse(doc, &maxn, markdown.data(), markdown.size(), nullptr);
     if (!node)
         throw Error("cannot parse Markdown document");
     Finally freeNode([&]() { lowdown_node_free(node); });
@@ -40,7 +40,7 @@ std::string renderMarkdownToTerminal(std::string_view markdown)
         throw Error("cannot allocate Markdown output buffer");
     Finally freeBuffer([&]() { lowdown_buf_free(buf); });
 
-    int rndr_res = lowdown_term_rndr(buf, nullptr, renderer, node);
+    int rndr_res = lowdown_term_rndr(buf, renderer, node);
     if (!rndr_res)
         throw Error("allocation error while rendering Markdown");
 

From 81b8e910a0261572a3fedabfce5318fec3ffc95c Mon Sep 17 00:00:00 2001
From: oxalica <oxalicc@pm.me>
Date: Fri, 24 Sep 2021 22:01:27 +0800
Subject: [PATCH 031/567] Explicitly set initial branch name for git

---
 src/libfetchers/git.cc | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/libfetchers/git.cc b/src/libfetchers/git.cc
index bfc58f7a1..8468d2afc 100644
--- a/src/libfetchers/git.cc
+++ b/src/libfetchers/git.cc
@@ -13,6 +13,12 @@ using namespace std::string_literals;
 
 namespace nix::fetchers {
 
+// Explicit initial branch of our bare repo to suppress warnings from new version of git.
+// The value itself does not matter, since we always fetch a specific revision or branch.
+// It is set with `-c init.defaultBranch=` instead of `--initial-branch=` to stay compatible with
+// old version of git, which will ignore unrecognized `-c` options.
+const std::string gitInitialBranch = "__nix_dummy_branch";
+
 static std::string readHead(const Path & path)
 {
     return chomp(runProgram("git", true, { "-C", path, "rev-parse", "--abbrev-ref", "HEAD" }));
@@ -324,7 +330,7 @@ struct GitInputScheme : InputScheme
             lockFile(lock.get(), ltWrite, true);
 
             if (!pathExists(cacheDir)) {
-                runProgram("git", true, { "init", "--bare", repoDir });
+                runProgram("git", true, { "-c", "init.defaultBranch=" + gitInitialBranch, "init", "--bare", repoDir });
             }
 
             deleteLockFile(cacheDirLock, lock.get());
@@ -436,7 +442,7 @@ struct GitInputScheme : InputScheme
             Path tmpGitDir = createTempDir();
             AutoDelete delTmpGitDir(tmpGitDir, true);
 
-            runProgram("git", true, { "init", tmpDir, "--separate-git-dir", tmpGitDir });
+            runProgram("git", true, { "-c", "init.defaultBranch=" + gitInitialBranch, "init", tmpDir, "--separate-git-dir", tmpGitDir });
             // TODO: repoDir might lack the ref (it only checks if rev
             // exists, see FIXME above) so use a big hammer and fetch
             // everything to ensure we get the rev.

From 32669a6bc95e590c6b3421240b270fda99288a24 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 27 Sep 2021 10:31:13 +0200
Subject: [PATCH 032/567] Use separate lowdown

Overriding the lowdown in nixpkgs can break nixUnstable.
---
 flake.nix | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/flake.nix b/flake.nix
index fc4836864..43123ca7e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -70,7 +70,7 @@
           [
             buildPackages.bison
             buildPackages.flex
-            (lib.getBin buildPackages.lowdown)
+            (lib.getBin buildPackages.lowdown-nix)
             buildPackages.mdbook
             buildPackages.autoconf-archive
             buildPackages.autoreconfHook
@@ -89,7 +89,7 @@
             openssl sqlite
             libarchive
             boost
-            lowdown
+            lowdown-nix
             gmock
           ]
           ++ lib.optionals stdenv.isLinux [libseccomp]
@@ -349,16 +349,9 @@
 
         };
 
-        lowdown = with final; stdenv.mkDerivation rec {
+        lowdown-nix = with final; stdenv.mkDerivation rec {
           name = "lowdown-0.9.0";
 
-          /*
-          src = fetchurl {
-            url = "https://kristaps.bsd.lv/lowdown/snapshots/${name}.tar.gz";
-            hash = "sha512-U9WeGoInT9vrawwa57t6u9dEdRge4/P+0wLxmQyOL9nhzOEUU2FRz2Be9H0dCjYE7p2v3vCXIYk40M+jjULATw==";
-          };
-          */
-
           src = lowdown-src;
 
           outputs = [ "out" "bin" "dev" ];

From a15e65eef0443a4d41b1a9e9b1504234dc5f5947 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 27 Sep 2021 10:53:09 +0200
Subject: [PATCH 033/567] run(): Move

---
 src/libcmd/command.cc               | 4 ++--
 src/libcmd/command.hh               | 8 ++++----
 src/nix/copy.cc                     | 2 +-
 src/nix/make-content-addressable.cc | 2 +-
 src/nix/path-info.cc                | 2 +-
 src/nix/realisation.cc              | 2 +-
 src/nix/sigs.cc                     | 4 ++--
 src/nix/store-delete.cc             | 2 +-
 src/nix/store-repair.cc             | 2 +-
 src/nix/verify.cc                   | 2 +-
 10 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/src/libcmd/command.cc b/src/libcmd/command.cc
index 2daf43aa7..2b9902677 100644
--- a/src/libcmd/command.cc
+++ b/src/libcmd/command.cc
@@ -138,7 +138,7 @@ StorePathsCommand::StorePathsCommand(bool recursive)
 {
 }
 
-void StorePathsCommand::run(ref<Store> store, BuiltPaths paths)
+void StorePathsCommand::run(ref<Store> store, BuiltPaths && paths)
 {
     StorePaths storePaths;
     for (auto& builtPath : paths)
@@ -148,7 +148,7 @@ void StorePathsCommand::run(ref<Store> store, BuiltPaths paths)
     run(store, std::move(storePaths));
 }
 
-void StorePathCommand::run(ref<Store> store, std::vector<StorePath> storePaths)
+void StorePathCommand::run(ref<Store> store, std::vector<StorePath> && storePaths)
 {
     if (storePaths.size() != 1)
         throw UsageError("this command requires exactly one store path");
diff --git a/src/libcmd/command.hh b/src/libcmd/command.hh
index dac146d24..07f398468 100644
--- a/src/libcmd/command.hh
+++ b/src/libcmd/command.hh
@@ -169,7 +169,7 @@ public:
 
     using StoreCommand::run;
 
-    virtual void run(ref<Store> store, BuiltPaths paths) = 0;
+    virtual void run(ref<Store> store, BuiltPaths && paths) = 0;
 
     void run(ref<Store> store) override;
 
@@ -182,9 +182,9 @@ struct StorePathsCommand : public BuiltPathsCommand
 
     using BuiltPathsCommand::run;
 
-    virtual void run(ref<Store> store, std::vector<StorePath> storePaths) = 0;
+    virtual void run(ref<Store> store, std::vector<StorePath> && storePaths) = 0;
 
-    void run(ref<Store> store, BuiltPaths paths) override;
+    void run(ref<Store> store, BuiltPaths && paths) override;
 };
 
 /* A command that operates on exactly one store path. */
@@ -194,7 +194,7 @@ struct StorePathCommand : public StorePathsCommand
 
     virtual void run(ref<Store> store, const StorePath & storePath) = 0;
 
-    void run(ref<Store> store, std::vector<StorePath> storePaths) override;
+    void run(ref<Store> store, std::vector<StorePath> && storePaths) override;
 };
 
 /* A helper class for registering commands globally. */
diff --git a/src/nix/copy.cc b/src/nix/copy.cc
index 0489dfe06..197c85316 100644
--- a/src/nix/copy.cc
+++ b/src/nix/copy.cc
@@ -78,7 +78,7 @@ struct CmdCopy : BuiltPathsCommand
         BuiltPathsCommand::run(store);
     }
 
-    void run(ref<Store> srcStore, BuiltPaths paths) override
+    void run(ref<Store> srcStore, BuiltPaths && paths) override
     {
         ref<Store> dstStore = dstUri.empty() ? openStore() : openStore(dstUri);
 
diff --git a/src/nix/make-content-addressable.cc b/src/nix/make-content-addressable.cc
index f5bdc7e65..12f303a10 100644
--- a/src/nix/make-content-addressable.cc
+++ b/src/nix/make-content-addressable.cc
@@ -25,7 +25,7 @@ struct CmdMakeContentAddressable : StorePathsCommand, MixJSON
           ;
     }
 
-    void run(ref<Store> store, StorePaths storePaths) override
+    void run(ref<Store> store, StorePaths && storePaths) override
     {
         auto paths = store->topoSortPaths(StorePathSet(storePaths.begin(), storePaths.end()));
 
diff --git a/src/nix/path-info.cc b/src/nix/path-info.cc
index 518cd5568..3743d7504 100644
--- a/src/nix/path-info.cc
+++ b/src/nix/path-info.cc
@@ -79,7 +79,7 @@ struct CmdPathInfo : StorePathsCommand, MixJSON
         std::cout << fmt("\t%6.1f%c", res, idents.at(power));
     }
 
-    void run(ref<Store> store, StorePaths storePaths) override
+    void run(ref<Store> store, StorePaths && storePaths) override
     {
         size_t pathLen = 0;
         for (auto & storePath : storePaths)
diff --git a/src/nix/realisation.cc b/src/nix/realisation.cc
index d59e594df..dfa8ff449 100644
--- a/src/nix/realisation.cc
+++ b/src/nix/realisation.cc
@@ -44,7 +44,7 @@ struct CmdRealisationInfo : BuiltPathsCommand, MixJSON
 
     Category category() override { return catSecondary; }
 
-    void run(ref<Store> store, BuiltPaths paths) override
+    void run(ref<Store> store, BuiltPaths && paths) override
     {
         settings.requireExperimentalFeature("ca-derivations");
         RealisedPath::Set realisations;
diff --git a/src/nix/sigs.cc b/src/nix/sigs.cc
index c64b472b6..43e0d9148 100644
--- a/src/nix/sigs.cc
+++ b/src/nix/sigs.cc
@@ -27,7 +27,7 @@ struct CmdCopySigs : StorePathsCommand
         return "copy store path signatures from substituters";
     }
 
-    void run(ref<Store> store, StorePaths storePaths) override
+    void run(ref<Store> store, StorePaths && storePaths) override
     {
         if (substituterUris.empty())
             throw UsageError("you must specify at least one substituter using '-s'");
@@ -113,7 +113,7 @@ struct CmdSign : StorePathsCommand
         return "sign store paths";
     }
 
-    void run(ref<Store> store, StorePaths storePaths) override
+    void run(ref<Store> store, StorePaths && storePaths) override
     {
         if (secretKeyFile.empty())
             throw UsageError("you must specify a secret key file using '-k'");
diff --git a/src/nix/store-delete.cc b/src/nix/store-delete.cc
index 10245978e..e4a3cb554 100644
--- a/src/nix/store-delete.cc
+++ b/src/nix/store-delete.cc
@@ -30,7 +30,7 @@ struct CmdStoreDelete : StorePathsCommand
           ;
     }
 
-    void run(ref<Store> store, std::vector<StorePath> storePaths) override
+    void run(ref<Store> store, std::vector<StorePath> && storePaths) override
     {
         for (auto & path : storePaths)
             options.pathsToDelete.insert(path);
diff --git a/src/nix/store-repair.cc b/src/nix/store-repair.cc
index 1c7a4392e..8fcb3639a 100644
--- a/src/nix/store-repair.cc
+++ b/src/nix/store-repair.cc
@@ -17,7 +17,7 @@ struct CmdStoreRepair : StorePathsCommand
           ;
     }
 
-    void run(ref<Store> store, std::vector<StorePath> storePaths) override
+    void run(ref<Store> store, std::vector<StorePath> && storePaths) override
     {
         for (auto & path : storePaths)
             store->repairPath(path);
diff --git a/src/nix/verify.cc b/src/nix/verify.cc
index f5a576064..e92df1303 100644
--- a/src/nix/verify.cc
+++ b/src/nix/verify.cc
@@ -59,7 +59,7 @@ struct CmdVerify : StorePathsCommand
           ;
     }
 
-    void run(ref<Store> store, StorePaths storePaths) override
+    void run(ref<Store> store, StorePaths && storePaths) override
     {
         std::vector<ref<Store>> substituters;
         for (auto & s : substituterUris)

From 4b2b15113196e403bc32ce0d7b4338971d7954a8 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 27 Sep 2021 10:57:11 +0200
Subject: [PATCH 034/567] nix path-info -r: Don't duplicate the root paths

This fixes

  $ nix path-info -r $(type -P ls)
  /nix/store/vfilzcp8a467w3p0mp54ybq6bdzb8w49-coreutils-8.32
  /nix/store/5d821pjgzb90lw4zbg6xwxs7llm335wr-libunistring-0.9.10
  ...
  /nix/store/mrv4y369nw6hg4pw8d9p9bfdxj9pjw0x-acl-2.3.0
  /nix/store/vfilzcp8a467w3p0mp54ybq6bdzb8w49-coreutils-8.32

Also, output the paths in topologically sorted order like we used to.
---
 src/libcmd/command.cc | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/libcmd/command.cc b/src/libcmd/command.cc
index 2b9902677..0d61e12d0 100644
--- a/src/libcmd/command.cc
+++ b/src/libcmd/command.cc
@@ -120,7 +120,7 @@ void BuiltPathsCommand::run(ref<Store> store)
             // XXX: This only computes the store path closure, ignoring
             // intermediate realisations
             StorePathSet pathsRoots, pathsClosure;
-            for (auto & root: paths) {
+            for (auto & root : paths) {
                 auto rootFromThis = root.outPaths();
                 pathsRoots.insert(rootFromThis.begin(), rootFromThis.end());
             }
@@ -140,12 +140,15 @@ StorePathsCommand::StorePathsCommand(bool recursive)
 
 void StorePathsCommand::run(ref<Store> store, BuiltPaths && paths)
 {
-    StorePaths storePaths;
-    for (auto& builtPath : paths)
-        for (auto& p : builtPath.outPaths())
-            storePaths.push_back(p);
+    StorePathSet storePaths;
+    for (auto & builtPath : paths)
+        for (auto & p : builtPath.outPaths())
+            storePaths.insert(p);
 
-    run(store, std::move(storePaths));
+    auto sorted = store->topoSortPaths(storePaths);
+    std::reverse(sorted.begin(), sorted.end());
+
+    run(store, std::move(sorted));
 }
 
 void StorePathCommand::run(ref<Store> store, std::vector<StorePath> && storePaths)

From 8430a8f0866e4463a891ccce62779ea9ac0f3b38 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 27 Sep 2021 14:35:55 +0200
Subject: [PATCH 035/567] Don't copy in rethrow

---
 src/libexpr/primops.cc                      | 8 ++++----
 src/libstore/build/derivation-goal.cc       | 4 ++--
 src/libstore/build/local-derivation-goal.cc | 4 ++--
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index c98a30177..6ddd4a90d 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -125,7 +125,7 @@ static void import(EvalState & state, const Pos & pos, Value & vPath, Value * vS
         });
     } catch (Error & e) {
         e.addTrace(pos, "while importing '%s'", path);
-        throw e;
+        throw;
     }
 
     Path realPath = state.checkSourcePath(state.toRealPath(path, context));
@@ -579,7 +579,7 @@ static Bindings::iterator getAttr(
             // Adding another trace for the function name to make it clear
             // which call received wrong arguments.
             e.addTrace(pos, hintfmt("while invoking '%s'", funcName));
-            throw e;
+            throw;
         }
     }
 
@@ -1717,7 +1717,7 @@ static void prim_fromJSON(EvalState & state, const Pos & pos, Value * * args, Va
         parseJSON(state, s, v);
     } catch (JSONParseError &e) {
         e.addTrace(pos, "while decoding a JSON string");
-        throw e;
+        throw;
     }
 }
 
@@ -2902,7 +2902,7 @@ static void prim_concatMap(EvalState & state, const Pos & pos, Value * * args, V
             state.forceList(lists[n], lists[n].determinePos(args[0]->determinePos(pos)));
         } catch (TypeError &e) {
             e.addTrace(pos, hintfmt("while invoking '%s'", "concatMap"));
-            throw e;
+            throw;
         }
         len += lists[n].listSize();
     }
diff --git a/src/libstore/build/derivation-goal.cc b/src/libstore/build/derivation-goal.cc
index b58d04c05..0907120db 100644
--- a/src/libstore/build/derivation-goal.cc
+++ b/src/libstore/build/derivation-goal.cc
@@ -1009,7 +1009,7 @@ HookReply DerivationGoal::tryBuildHook()
                     return readLine(worker.hook->fromHook.readSide.get());
                 } catch (Error & e) {
                     e.addTrace({}, "while reading the response from the build hook");
-                    throw e;
+                    throw;
                 }
             }();
             if (handleJSONLogMessage(s, worker.act, worker.hook->activities, true))
@@ -1055,7 +1055,7 @@ HookReply DerivationGoal::tryBuildHook()
         machineName = readLine(hook->fromHook.readSide.get());
     } catch (Error & e) {
         e.addTrace({}, "while reading the machine name from the build hook");
-        throw e;
+        throw;
     }
 
     /* Tell the hook all the inputs that have to be copied to the
diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 23a5df85e..b0bc82ffc 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -943,7 +943,7 @@ void LocalDerivationGoal::startBuilder()
                     worker.store.printStorePath(drvPath),
                     statusToString(status),
                     concatStringsSep("|", msgs));
-                throw e;
+                throw;
             }
         }();
         if (string(msg, 0, 1) == "\2") break;
@@ -951,7 +951,7 @@ void LocalDerivationGoal::startBuilder()
             FdSource source(builderOut.readSide.get());
             auto ex = readError(source);
             ex.addTrace({}, "while setting up the build environment");
-            throw ex;
+            throw;
         }
         debug("sandbox setup: " + msg);
         msgs.push_back(std::move(msg));

From 9c766a40cbbd3a350a9582d0fd8201e3361a63b2 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 27 Sep 2021 14:44:21 +0200
Subject: [PATCH 036/567] Fix 'error: reading a line: Input/output error' in
 startBuilder()

With -vvvv, the ProgressBar was polluting the stderr of the child,
messing up its \2 message to the parent.
---
 src/libutil/util.cc    | 2 ++
 tests/ca/signatures.sh | 4 ++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 6c7f93d50..bc841f425 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1716,6 +1716,8 @@ string showBytes(uint64_t bytes)
 // FIXME: move to libstore/build
 void commonChildInit(Pipe & logPipe)
 {
+    logger = makeSimpleLogger();
+
     const static string pathNullDevice = "/dev/null";
     restoreProcessContext();
 
diff --git a/tests/ca/signatures.sh b/tests/ca/signatures.sh
index 4b4e468f7..0c7d974ea 100644
--- a/tests/ca/signatures.sh
+++ b/tests/ca/signatures.sh
@@ -22,8 +22,8 @@ testOneCopy () {
     rm -rf "$REMOTE_STORE_DIR"
 
     attrPath="$1"
-    nix copy --to $REMOTE_STORE "$attrPath" --file ./content-addressed.nix \
-        --secret-key-files "$TEST_ROOT/sk1"
+    nix copy -vvvv --to $REMOTE_STORE "$attrPath" --file ./content-addressed.nix \
+        --secret-key-files "$TEST_ROOT/sk1" --show-trace
 
     ensureCorrectlyCopied "$attrPath"
 

From bb1a851bcf1bf62b5d943ba25d57b680711a64c6 Mon Sep 17 00:00:00 2001
From: Maximilian Bosch <maximilian@mbosch.me>
Date: Sun, 26 Sep 2021 15:20:36 +0200
Subject: [PATCH 037/567] build: also throw hash-mismatch errors if `buildMode
 == bmCheck`

This actually bit me quite recently in `nixpkgs` because I assumed that
`nix-build --check` would also error out if hashes don't match anymore[1]
and so I wrongly assumed that I couldn't reproduce the mismatch error.

The fix is rather simple, during the output registration a so-called
`delayedException` is instantiated e.g. if a FOD hash-mismatch occurs.
However, in case of `nix-build --check` (or `--rebuild` in case of `nix
build`), the code-path where this exception is thrown will never be
reached.

By adding that check to the if-clause that causes an early exit in case
of `bmCheck`, the issue is gone. Also added a (previously failing)
test-case to demonstrate the problem.

[1] https://github.com/NixOS/nixpkgs/pull/139238, the underlying issue
    was that `nix-prefetch-git` returns different hashes than `fetchgit`
    because the latter one fetches submodules by default.
---
 src/libstore/build/local-derivation-goal.cc | 8 +++++++-
 tests/fixed.nix                             | 8 ++++++++
 tests/fixed.sh                              | 5 +++++
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 23a5df85e..9b59a4cf5 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -2474,7 +2474,13 @@ void LocalDerivationGoal::registerOutputs()
         infos.emplace(outputName, std::move(newInfo));
     }
 
-    if (buildMode == bmCheck) return;
+    if (buildMode == bmCheck) {
+        // In case of FOD mismatches on `--check` an error must be thrown as this is also
+        // a source for non-determinism.
+        if (delayedException)
+            std::rethrow_exception(delayedException);
+        return;
+    }
 
     /* Apply output checks. */
     checkOutputs(infos);
diff --git a/tests/fixed.nix b/tests/fixed.nix
index 76580ffa1..babe71504 100644
--- a/tests/fixed.nix
+++ b/tests/fixed.nix
@@ -21,6 +21,14 @@ rec {
     (f ./fixed.builder2.sh "recursive" "sha1" "vw46m23bizj4n8afrc0fj19wrp7mj3c0")
   ];
 
+  # Expression to test that `nix-build --check` also throws an error if the hash of
+  # fixed-output derivation has changed even if the hash exists in the store (in this
+  # case the hash exists because of `fixed.builder2.sh`, but building a derivation
+  # with the same hash and a different result must throw an error).
+  check = [
+    (f ./fixed.builder1.sh "recursive" "md5" "3670af73070fa14077ad74e0f5ea4e42")
+  ];
+
   good2 = [
     # Yes, this looks fscked up: builder2 doesn't have that result.
     # But Nix sees that an output with the desired hash already
diff --git a/tests/fixed.sh b/tests/fixed.sh
index 90c4c8c32..f1e1ce420 100644
--- a/tests/fixed.sh
+++ b/tests/fixed.sh
@@ -15,6 +15,11 @@ nix path-info --json $path | grep fixed:md5:2qk15sxzzjlnpjk9brn7j8ppcd
 echo 'testing good...'
 nix-build fixed.nix -A good --no-out-link
 
+if isDaemonNewer "2.4pre20210927"; then
+    echo 'testing --check...'
+    nix-build fixed.nix -A check --check && fail "should fail"
+fi
+
 echo 'testing good2...'
 nix-build fixed.nix -A good2 --no-out-link
 

From 34e8cc82874ffdbab01ef4d8122ea5a5a93a4eba Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 29 Sep 2021 10:16:52 +0200
Subject: [PATCH 038/567] flake.lock: Update
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Flake lock file changes:

• Updated input 'lowdown-src':
    'github:kristapsdz/lowdown/0b85e777f3cdacf4210f0d624a0ceec8df612e05' (2021-09-23)
  → 'github:kristapsdz/lowdown/6bd668af3fd098bdd07a1bedd399564141e275da' (2021-09-24)
• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/f6551e1efa261568c82b76c3a582b2c2ceb1f53f' (2021-08-11)
  → 'github:NixOS/nixpkgs/82891b5e2c2359d7e58d08849e4c89511ab94234' (2021-09-28)
---
 flake.lock | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/flake.lock b/flake.lock
index c477e7678..96a69345b 100644
--- a/flake.lock
+++ b/flake.lock
@@ -3,11 +3,11 @@
     "lowdown-src": {
       "flake": false,
       "locked": {
-        "lastModified": 1632391204,
-        "narHash": "sha256-zjyNA4ZmaaIbbmz2JZDqMgY7+P/uGF0nLg28Nxfg5kI=",
+        "lastModified": 1632468475,
+        "narHash": "sha256-NNOm9CbdA8cuwbvaBHslGbPTiU6bh1Ao+MpEPx4rSGo=",
         "owner": "kristapsdz",
         "repo": "lowdown",
-        "rev": "0b85e777f3cdacf4210f0d624a0ceec8df612e05",
+        "rev": "6bd668af3fd098bdd07a1bedd399564141e275da",
         "type": "github"
       },
       "original": {
@@ -18,11 +18,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1628689438,
-        "narHash": "sha256-YMINW6YmubHZVdliGsAJpnnMYXRrvppv59LgwtnyYhs=",
+        "lastModified": 1632864508,
+        "narHash": "sha256-d127FIvGR41XbVRDPVvozUPQ/uRHbHwvfyKHwEt5xFM=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "f6551e1efa261568c82b76c3a582b2c2ceb1f53f",
+        "rev": "82891b5e2c2359d7e58d08849e4c89511ab94234",
         "type": "github"
       },
       "original": {

From 2b02ce0e481b653bcc5b403ef5d9e3670a88e8e5 Mon Sep 17 00:00:00 2001
From: Maximilian Bosch <maximilian@mbosch.me>
Date: Tue, 28 Sep 2021 22:12:41 +0200
Subject: [PATCH 039/567] libexpr: throw a more helpful eval-error if a builtin
 is not available due to a missing feature-flag
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

I found it somewhat confusing to have an error like

    error: attribute 'getFlake' missing

if the required experimental-feature (`flakes`) is not enabled. Instead,
I'd expect Nix to throw an error just like it's the case when using e.g. `nix
flake` without `flakes` being enabled.

With this change, the error looks like this:

    $ nix-instantiate -E 'builtins.getFlake "nixpkgs"'
    error: Cannot call 'builtins.getFlake' because experimental Nix feature 'flakes' is disabled. You can enable it via '--extra-experimental-features flakes'.

           at «string»:1:1:

                1| builtins.getFlake "nixpkgs"
                 | ^

I didn't use `settings.requireExperimentalFeature` here on purpose
because this doesn't contain a position. Also, it doesn't seem as if we
need to catch the error and check for the missing feature here since
this already happens at evaluation time.
---
 src/libexpr/eval.cc        | 17 +++++++++++++++++
 src/libexpr/eval.hh        |  6 ++++++
 src/libexpr/flake/flake.cc |  4 +++-
 src/libexpr/primops.cc     | 19 ++++++++-----------
 src/libexpr/primops.hh     |  4 +---
 5 files changed, 35 insertions(+), 15 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index bc41a2cd9..800839a8d 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -465,6 +465,23 @@ EvalState::~EvalState()
 }
 
 
+void EvalState::requireExperimentalFeatureOnEvaluation(
+    const std::string & feature,
+    const std::string_view fName,
+    const Pos & pos)
+{
+    if (!settings.isExperimentalFeatureEnabled(feature)) {
+        throw EvalError({
+            .msg = hintfmt(
+                "Cannot call '%2%' because experimental Nix feature '%1%' is disabled. You can enable it via '--extra-experimental-features %1%'.",
+                feature,
+                fName
+            ),
+            .errPos = pos
+        });
+    }
+}
+
 Path EvalState::checkSourcePath(const Path & path_)
 {
     if (!allowedPaths) return path_;
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index b29feb134..9df6150c6 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -140,6 +140,12 @@ public:
         std::shared_ptr<Store> buildStore = nullptr);
     ~EvalState();
 
+    void requireExperimentalFeatureOnEvaluation(
+        const std::string & feature,
+        const std::string_view fName,
+        const Pos & pos
+    );
+
     void addToSearchPath(const string & s);
 
     SearchPath getSearchPath() { return searchPath; }
diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 492b47115..1a1fa6938 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -688,6 +688,8 @@ void callFlake(EvalState & state,
 
 static void prim_getFlake(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
+    state.requireExperimentalFeatureOnEvaluation("flakes", "builtins.getFlake", pos);
+
     auto flakeRefS = state.forceStringNoCtx(*args[0], pos);
     auto flakeRef = parseFlakeRef(flakeRefS, {}, true);
     if (evalSettings.pureEval && !flakeRef.input.isImmutable())
@@ -703,7 +705,7 @@ static void prim_getFlake(EvalState & state, const Pos & pos, Value * * args, Va
         v);
 }
 
-static RegisterPrimOp r2("__getFlake", 1, prim_getFlake, "flakes");
+static RegisterPrimOp r2("__getFlake", 1, prim_getFlake);
 
 }
 
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index c98a30177..ead8c1ded 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -3606,15 +3606,13 @@ static RegisterPrimOp primop_splitVersion({
 RegisterPrimOp::PrimOps * RegisterPrimOp::primOps;
 
 
-RegisterPrimOp::RegisterPrimOp(std::string name, size_t arity, PrimOpFun fun,
-    std::optional<std::string> requiredFeature)
+RegisterPrimOp::RegisterPrimOp(std::string name, size_t arity, PrimOpFun fun)
 {
     if (!primOps) primOps = new PrimOps;
     primOps->push_back({
         .name = name,
         .args = {},
         .arity = arity,
-        .requiredFeature = std::move(requiredFeature),
         .fun = fun
     });
 }
@@ -3688,14 +3686,13 @@ void EvalState::createBaseEnv()
 
     if (RegisterPrimOp::primOps)
         for (auto & primOp : *RegisterPrimOp::primOps)
-            if (!primOp.requiredFeature || settings.isExperimentalFeatureEnabled(*primOp.requiredFeature))
-                addPrimOp({
-                    .fun = primOp.fun,
-                    .arity = std::max(primOp.args.size(), primOp.arity),
-                    .name = symbols.create(primOp.name),
-                    .args = std::move(primOp.args),
-                    .doc = primOp.doc,
-                });
+            addPrimOp({
+                .fun = primOp.fun,
+                .arity = std::max(primOp.args.size(), primOp.arity),
+                .name = symbols.create(primOp.name),
+                .args = std::move(primOp.args),
+                .doc = primOp.doc,
+            });
 
     /* Add a wrapper around the derivation primop that computes the
        `drvPath' and `outPath' attributes lazily. */
diff --git a/src/libexpr/primops.hh b/src/libexpr/primops.hh
index 9d42d6539..5b16e075f 100644
--- a/src/libexpr/primops.hh
+++ b/src/libexpr/primops.hh
@@ -15,7 +15,6 @@ struct RegisterPrimOp
         std::vector<std::string> args;
         size_t arity = 0;
         const char * doc;
-        std::optional<std::string> requiredFeature;
         PrimOpFun fun;
     };
 
@@ -28,8 +27,7 @@ struct RegisterPrimOp
     RegisterPrimOp(
         std::string name,
         size_t arity,
-        PrimOpFun fun,
-        std::optional<std::string> requiredFeature = {});
+        PrimOpFun fun);
 
     RegisterPrimOp(Info && info);
 };

From f14660d5e20df07d7b32d7658c83a76c713bc915 Mon Sep 17 00:00:00 2001
From: Taeer Bar-Yam <taeer@bar-yam.me>
Date: Wed, 29 Sep 2021 19:37:51 -0400
Subject: [PATCH 040/567] reset yylloc when yyless(0) is called

---
 src/libexpr/lexer.l | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/libexpr/lexer.l b/src/libexpr/lexer.l
index 8ad6a1957..51593eccd 100644
--- a/src/libexpr/lexer.l
+++ b/src/libexpr/lexer.l
@@ -28,6 +28,8 @@ using namespace nix;
 
 namespace nix {
 
+// backup to recover from yyless(0)
+YYLTYPE prev_yylloc;
 
 static void initLoc(YYLTYPE * loc)
 {
@@ -38,6 +40,8 @@ static void initLoc(YYLTYPE * loc)
 
 static void adjustLoc(YYLTYPE * loc, const char * s, size_t len)
 {
+    prev_yylloc = *loc;
+
     loc->first_line = loc->last_line;
     loc->first_column = loc->last_column;
 
@@ -210,6 +214,7 @@ or          { return OR_KW; }
 {HPATH_START}\$\{ {
   PUSH_STATE(PATH_START);
   yyless(0);
+  *yylloc = prev_yylloc;
 }
 
 <PATH_START>{PATH_SEG} {
@@ -265,6 +270,7 @@ or          { return OR_KW; }
      context (it may be ')', ';', or something of that sort) */
   POP_STATE();
   yyless(0);
+  *yylloc = prev_yylloc;
   return PATH_END;
 }
 

From 5e222ac18b447ac22b55c71842bd61342e8929f1 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 17 Sep 2021 09:07:49 +0200
Subject: [PATCH 041/567] Release notes

---
 doc/manual/src/release-notes/rl-2.4.md | 498 ++++++++++++++++++++++++-
 1 file changed, 491 insertions(+), 7 deletions(-)

diff --git a/doc/manual/src/release-notes/rl-2.4.md b/doc/manual/src/release-notes/rl-2.4.md
index f7ab9f6ad..25db72b31 100644
--- a/doc/manual/src/release-notes/rl-2.4.md
+++ b/doc/manual/src/release-notes/rl-2.4.md
@@ -1,8 +1,492 @@
-# Release 2.4 (202X-XX-XX)
+# Release 2.4 (2021-10-XX)
 
-  - It is now an error to modify the `plugin-files` setting via a
-    command-line flag that appears after the first non-flag argument
-    to any command, including a subcommand to `nix`. For example,
-    `nix-instantiate default.nix --plugin-files ""` must now become
-    `nix-instantiate --plugin-files "" default.nix`.
-  - Plugins that add new `nix` subcommands are now actually respected.
+This is the first release in more than two years and is the result of
+more than 2800 commits from 195 contributors since release 2.3.
+
+## Highlights
+
+* Nix's **error messages** have been improved a lot. For instance,
+  evaluation errors now point out the location of the error:
+
+  ```
+  $ nix build
+  error: undefined variable 'bzip3'
+
+         at /nix/store/449lv242z0zsgwv95a8124xi11sp419f-source/flake.nix:88:13:
+
+             87|           [ curl
+             88|             bzip3 xz brotli editline
+               |             ^
+             89|             openssl sqlite
+  ```
+
+* The **`nix` command** has seen a lot of work and is now almost at
+  feature parity with the old command-line interface (the `nix-*`
+  commands). It aims to be [more modern, consistent and pleasant to
+  use](../contributing/cli-guideline.md) than the old CLI.
+
+* **Flakes** are a new format to package Nix-based projects in a more
+  discoverable, composable, consistent and reproducible way. A flake
+  is just a repository or tarball containing a file named `flake.nix`
+  that specifies dependencies on other flakes and returns any Nix
+  assets such as packages, Nixpkgs overlays, NixOS modules or CI
+  tests. The new `nix` CLI is primarily based around flakes; for
+  example, a command like `nix run nixpkgs#hello` runs the `hello`
+  application from the `nixpkgs` flake.
+
+  Flakes are currently marked as experimental. For an introduction,
+  see [this blog
+  post](https://www.tweag.io/blog/2020-05-25-flakes/). For detailed
+  information about flake syntax and semantics, see the [`nix flake`
+  manual page](../command-ref/new-cli/nix3-flake.md).
+
+* Nix's store can now be **content-addressed**, meaning that the hash
+  component of a store path is the hash of the path's
+  contents. Previously Nix could only build **input-addressed** store
+  paths, where the hash is computed from the derivation dependency
+  graph. Content-addressing allows deduplication, early cutoff in
+  build systems, and unpriviliged closure copying. This is still [an
+  experimental
+  feature](https://discourse.nixos.org/t/content-addressed-nix-call-for-testers/12881).
+
+* The Nix manual has been converted into Markdown, making it easier to
+  contribute. In addition, every `nix` subcommand now has a manual
+  page, documenting every option.
+
+* A new setting that allows **experimental features** to be enabled
+  selectively. This allows us to merge unstable features into Nix more
+  quickly and do more frequent releases.
+
+## Other features
+
+* There are many new `nix` subcommands:
+
+  - `nix develop` is intended to replace `nix-shell`. It has a number
+    of new features:
+
+    * It automatically sets the output environment variables (such as
+      `$out`) to writable locations (such as `./outputs/out`).
+
+    * It can store the environment in a profile. This is useful for
+      offline work.
+
+    * It can run specific phases directly. For instance, `nix develop
+      --build` runs `buildPhase`.
+
+    - It allows dependencies in the Nix store to be "redirected" to
+      arbitrary directories using the `--redirect` flag. This is
+      useful if you want to hack on a package *and* some of its
+      dependencies at the same time.
+
+  - `nix print-dev-env` prints the environment variables and bash
+    functions defined by a derivation. This is useful for users of
+    other shells than bash (especially with `--json`).
+
+  - `nix shell` was previously named `nix run` and is intended to
+    replace `nix-shell -p`, but without the `stdenv` overhead. It
+    simply starts a shell where some packages have been added to
+    `$PATH`.
+
+  - `nix run` (not to be confused with the old subcommand that has
+    been renamed to `nix shell`) runs an "app", a flake output that
+    specifies a command to run, or an eponymous program from a
+    package. For example, `nix run nixpkgs#hello` runs the `hello`
+    program from the `hello` package in `nixpkgs`.
+
+  - `nix flake` is the container for flake-related operations, such as
+    creating a new flake, quering the contents of a flake or updating
+    flake lock files.
+
+  - `nix registry` allows you to query and update the flake registry,
+    which maps identifiers such as `nixpkgs` to concrete flake URLs.
+
+  - `nix profile` is intended to replace `nix-env`. Its main advantage
+    is that it keeps track of the provenance of installed packages
+    (e.g. exactly which flake version a package came from). It also
+    has some helpful subcommands:
+
+    * `nix profile history` shows what packages were added, upgraded
+      or removed between each version of a profile.
+
+    * `nix profile diff-closures` shows the changes between the
+      closures of each version of a profile. This allows you to
+      discover the addition or removal of dependencies or size
+      changes.
+
+    **Warning**: after a profile has been updated using `nix profile`,
+    it is no longer useable with `nix-env`.
+
+  - `nix store diff-closures` shows the differences between the
+    closures of two store paths in terms of the versions and sizes of
+    dependencies in the closures.
+
+  - `nix store make-content-addressable` rewrites an arbitrary closure
+    to make it content-addressed. Such paths can be copied into other
+    stores without requiring signatures.
+
+  - `nix bundle` uses the [`nix-bundle`
+    program](https://github.com/matthewbauer/nix-bundle) to convert a
+    closure into a self-extracting executable.
+
+  - Various other replacements for the old CLI, e.g. `nix store gc`,
+    `nix store delete`, `nix store repair`, `nix nar dump-path`, `nix
+    store prefetch-file`, `nix store prefetch-tarball`, `nix key` and
+    `nix daemon`.
+
+* Nix now has an **evaluation cache** for flake outputs. For example,
+  a second invocation of the command `nix run nixpkgs#firefox` will
+  not need to evaluate the `firefox` attribute because it's already in
+  the evaluation cache. This is made possible by the hermetic
+  evaluation model of flakes.
+
+* The new `--offline` flag disables substituters and causes all
+  locally cached tarballs and repositories to be considered
+  up-to-date.
+
+* The new `--refresh` flag causes all locally cached tarballs and
+  repositories to be considered out-of-date.
+
+* Many `nix` subcommands now have a `--json` option to produce
+  machine-readable output.
+
+* `nix repl` has a new `:doc` command to show documentation about
+  builtin functions (e.g. `:doc builtins.map`).
+
+* Binary cache stores now have an option `index-debug-info` to create
+  an index of DWARF debuginfo files for use by
+  [`dwarffs`](https://github.com/edolstra/dwarffs).
+
+* To support flakes, Nix now has an extensible mechanism for fetching
+  source trees. Currently it has the following backends:
+
+  * Git repositories
+
+  * Mercurial repositories
+
+  * GitHub and GitLab repositories (an optimisation for faster
+    fetching than Git)
+
+  * Tarballs
+
+  * Arbitrary directories
+
+  The fetcher infrastructure is exposed via flake input specifications
+  and via the `fetchTree` built-in.
+
+* **Languages changes**: the only new language feature is that you can
+  now have antiquotations in paths, e.g. `./${foo}` instead of `./. +
+  foo`.
+
+* **New built-in functions**:
+
+  - `builtins.fetchTree` allows fetching a source tree using any
+    backends supported by the fetcher infrastructure. It replaces
+    `fetchGit`, `fetchMercurial` and `fetchTarball`.
+
+  - `builtins.getFlake` fetches a flake and returns its output
+    attributes. This function should not be used inside flakes! Use
+    flake inputs instead.
+
+  - `builtins.floor` and `builtins.ceil` round a floating-point number
+    down and up, respectively.
+
+* Experimental support for recursive Nix. This means that Nix
+  derivations can now call Nix to build other derivations. This is not
+  in a stable state yet and not well
+  [documented](https://github.com/NixOS/nix/commit/c4d7c76b641d82b2696fef73ce0ac160043c18da).
+
+* The new experimental feature `no-url-literals` disables URL
+  literals. This helps to implement [RFC
+  45](https://github.com/NixOS/rfcs/pull/45).
+
+* Nix now uses `libarchive` to decompress and unpack tarballs and zip
+  files, so `tar` is no longer required.
+
+* The priority of substituters can now be overriden using the
+  `priority` substituter setting (e.g. `--substituters
+  'http://cache.nixos.org?priority=100 daemon?priority=10'`).
+
+* `nix edit` now supports non-derivation attributes, e.g. `nix edit
+  .#nixosConfigurations.bla`.
+
+* The `nix` command now provides command line completion for `bash`,
+  `zsh` and `fish`. Since the support for getting completions is built
+  into `nix`, it's easy to add support for other shells.
+
+* The new `--log-format` flag selects what Nix's output looks like. It
+  defaults to a terse progress indicator. There is a new
+  `internal-json` output format for use by other programs.
+
+* `nix eval` has a new `--apply` flag that applies a function to the
+  evaluation result.
+
+* `nix eval` has a new `--write-to` flag that allows it to write a
+  nested attribute set of string leaves to a correspondingly directory
+  tree.
+
+* Memory improvements: many operations that add paths to the store or
+  copy paths between stores now run in constant memory.
+
+* Many `nix` commands now support the flag `--derivation` to operate
+  on a `.drv` file itself instead of its outputs.
+
+* There is a new store called `dummy://` that does not support
+  building or adding paths. This is useful if you want to use the Nix
+  evaluator but don't have a Nix store.
+
+* The `ssh-ng://` store now allows substituting paths on the remote,
+  as `ssh://` already did.
+
+* When auto-calling a function with an ellipsis, all arguments are now
+  passed.
+
+* New `nix-shell` features:
+
+  - It preserves the `PS1` environment variable if
+    `NIX_SHELL_PRESERVE_PROMPT` is set.
+
+  - With `-p`, it passes any `--arg`s as Nixpkgs arguments.
+
+* `nix-prefetch-url` has a new `--executable` flag.
+
+* On `x86_64` systems, [`x86_64` microarchitecture
+  levels](https://lwn.net/Articles/844831/) are mapped to additional
+  system types (e.g. `x86_64-v1-linux`).
+
+* The new `--eval-store` flag allows you to use a different store for
+  evaluation than for building or storing the build result. This is
+  primarily useful when you want to query whether something exists in
+  a read-only store, such as a binary cache:
+
+  ```
+  # nix path-info --json --store https://cache.nixos.org \
+    --eval-store auto nixpkgs#hello
+  ```
+
+  (Here `auto` indicates the local store.)
+
+* The Nix daemon has a new low-latency mechanism for copying
+  closures. This is useful when building on remote stores such as
+  `ssh-ng://`.
+
+* Plugins can now register `nix` subcommands.
+
+## Incompatible changes
+
+* The `nix` command is now marked as an experimental feature. This
+  means that you need to add
+
+  > experimental-features = nix-command
+
+  to your `nix.conf` if you want to use it, or pass
+  `--extra-experimental-features nix-command` on the command line.
+
+* `nix run` has been renamed to `nix shell`.
+
+* It is now an error to modify the `plugin-files` setting via a
+  command-line flag that appears after the first non-flag argument to
+  any command, including a subcommand to `nix`. For example,
+  `nix-instantiate default.nix --plugin-files ""` must now become
+  `nix-instantiate --plugin-files "" default.nix`.
+
+* We no longer release source tarballs. If you want to build from
+  source, please build from the Git repository.
+
+## Contributors
+
+This release has contributions from
+Adam Höse,
+Albert Safin,
+Alex Kovar,
+Alex Zero,
+Alexander Bantyev,
+Alexandre Esteves,
+Alyssa Ross,
+Anatole Lucet,
+Anders Kaseorg,
+Andreas Rammhold,
+Antoine Eiche,
+Antoine Martin,
+Arnout Engelen,
+Arthur Gautier,
+aszlig,
+Ben Burdette,
+Benjamin Hipple,
+Bernardo Meurer,
+Björn Gohla,
+Bjørn Forsman,
+Bob van der Linden,
+Brian Leung,
+Brian McKenna,
+Brian Wignall,
+Bruce Toll,
+Bryan Richter,
+Calle Rosenquist,
+Calvin Loncaric,
+Carlo Nucera,
+Carlos D'Agostino,
+Chaz Schlarp,
+Christian Höppner,
+Christian Kampka,
+Chua Hou,
+Chuck,
+Cole Helbling,
+Daiderd Jordan,
+Dan Callahan,
+Dani,
+Daniel Fitzpatrick,
+Danila Fedorin,
+Daniël de Kok,
+Danny Bautista,
+DavHau,
+David McFarland,
+Dima,
+Domen Kožar,
+Dominik Schrempf,
+Dominique Martinet,
+dramforever,
+Dustin DeWeese,
+edef,
+Eelco Dolstra,
+Emilio Karakey,
+Emily,
+Eric Culp,
+Ersin Akinci,
+Fabian Möller,
+Farid Zakaria,
+Federico Pellegrin,
+Finn Behrens,
+Florian Franzen,
+Félix Baylac-Jacqué,
+Gabriel Gonzalez,
+Geoff Reedy,
+Georges Dubus,
+Graham Christensen,
+Greg Hale,
+Greg Price,
+Gregor Kleen,
+Gregory Hale,
+Griffin Smith,
+Guillaume Bouchard,
+Harald van Dijk,
+illustris,
+Ivan Zvonimir Horvat,
+Jade,
+Jake Waksbaum,
+jakobrs,
+James Ottaway,
+Jan Tojnar,
+Janne Heß,
+Jaroslavas Pocepko,
+Jarrett Keifer,
+Jeremy Schlatter,
+Joachim Breitner,
+Joe Hermaszewski,
+Joe Pea,
+John Ericson,
+Jonathan Ringer,
+Josef Kemetmüller,
+Joseph Lucas,
+Jude Taylor,
+Julian Stecklina,
+Julien Tanguy,
+Jörg Thalheim,
+Kai Wohlfahrt,
+keke,
+Keshav Kini,
+Kevin Quick,
+Kevin Stock,
+Kjetil Orbekk,
+Krzysztof Gogolewski,
+kvtb,
+Lars Mühmel,
+Leonhard Markert,
+Lily Ballard,
+Linus Heckemann,
+Lorenzo Manacorda,
+Lucas Desgouilles,
+Lucas Franceschino,
+Lucas Hoffmann,
+Luke Granger-Brown,
+Madeline Haraj,
+Marwan Aljubeh,
+Mat Marini,
+Mateusz Piotrowski,
+Matthew Bauer,
+Matthew Kenigsberg,
+Mauricio Scheffer,
+Maximilian Bosch,
+Michael Adler,
+Michael Bishop,
+Michael Fellinger,
+Michael Forney,
+Michael Reilly,
+mlatus,
+Mykola Orliuk,
+Nathan van Doorn,
+Naïm Favier,
+ng0,
+Nick Van den Broeck,
+Nicolas Stig124 Formichella,
+Niels Egberts,
+Niklas Hambüchen,
+Nikola Knezevic,
+oxalica,
+p01arst0rm,
+Pamplemousse,
+Patrick Hilhorst,
+Paul Opiyo,
+Pavol Rusnak,
+Peter Kolloch,
+Philipp Bartsch,
+Philipp Middendorf,
+Piotr Szubiakowski,
+Profpatsch,
+Puck Meerburg,
+Ricardo M. Correia,
+Rickard Nilsson,
+Robert Hensing,
+Robin Gloster,
+Rodrigo,
+Rok Garbas,
+Ronnie Ebrin,
+Rovanion Luckey,
+Ryan Burns,
+Ryan Mulligan,
+Ryne Everett,
+Sam Doshi,
+Sam Lidder,
+Samir Talwar,
+Samuel Dionne-Riel,
+Sebastian Ullrich,
+Sergei Trofimovich,
+Sevan Janiyan,
+Shao Cheng,
+Shea Levy,
+Silvan Mosberger,
+Stefan Frijters,
+Stefan Jaax,
+sternenseemann,
+Steven Shaw,
+Stéphan Kochen,
+SuperSandro2000,
+Suraj Barkale,
+Taeer Bar-Yam,
+Thomas Churchman,
+Théophane Hufschmitt,
+Timothy DeHerrera,
+Timothy Klim,
+Tobias Möst,
+Tobias Pflug,
+Tom Bereknyei,
+Travis A. Everett,
+Ujjwal Jain,
+Vladimír Čunát,
+Wil Taylor,
+Will Dietz,
+Yaroslav Bolyukin,
+Yestin L. Harrison,
+YI,
+Yorick van Pelt,
+Yuriy Taraday and
+zimbatm.

From 242f9bf3dc04170502020fb0338b78ea76b9ebac Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Thu, 30 Sep 2021 21:31:21 +0000
Subject: [PATCH 042/567] `std::visit` by reference

I had started the trend of doing `std::visit` by value (because a type
error once mislead me into thinking that was the only form that
existed). While the optomizer in principle should be able to deal with
extra coppying or extra indirection once the lambdas inlined, sticking
with by reference is the conventional default. I hope this might even
improve performance.
---
 src/libcmd/command.cc                       |  4 +-
 src/libcmd/installables.cc                  | 14 +++----
 src/libexpr/primops.cc                      |  6 +--
 src/libstore/build/entry-points.cc          |  6 +--
 src/libstore/build/local-derivation-goal.cc | 18 ++++-----
 src/libstore/content-address.cc             | 16 ++++----
 src/libstore/daemon.cc                      |  4 +-
 src/libstore/derivations.cc                 | 44 ++++++++++-----------
 src/libstore/derived-path.cc                |  8 ++--
 src/libstore/legacy-ssh-store.cc            |  4 +-
 src/libstore/local-store.cc                 |  8 ++--
 src/libstore/misc.cc                        |  4 +-
 src/libstore/path-with-outputs.cc           |  4 +-
 src/libstore/remote-store.cc                |  8 ++--
 src/libstore/store-api.cc                   |  8 ++--
 src/nix/build.cc                            |  4 +-
 src/nix/log.cc                              |  4 +-
 src/nix/profile.cc                          |  4 +-
 src/nix/show-derivation.cc                  |  8 ++--
 19 files changed, 88 insertions(+), 88 deletions(-)

diff --git a/src/libcmd/command.cc b/src/libcmd/command.cc
index 0d61e12d0..fd3edfc46 100644
--- a/src/libcmd/command.cc
+++ b/src/libcmd/command.cc
@@ -203,10 +203,10 @@ void MixProfile::updateProfile(const BuiltPaths & buildables)
 
     for (auto & buildable : buildables) {
         std::visit(overloaded {
-            [&](BuiltPath::Opaque bo) {
+            [&](const BuiltPath::Opaque & bo) {
                 result.push_back(bo.path);
             },
-            [&](BuiltPath::Built bfd) {
+            [&](const BuiltPath::Built & bfd) {
                 for (auto & output : bfd.outputs) {
                     result.push_back(output.second);
                 }
diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index 8015cff4d..0f0fcf39e 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -697,13 +697,13 @@ std::shared_ptr<Installable> SourceExprCommand::parseInstallable(
 BuiltPaths getBuiltPaths(ref<Store> evalStore, ref<Store> store, const DerivedPaths & hopefullyBuiltPaths)
 {
     BuiltPaths res;
-    for (auto & b : hopefullyBuiltPaths)
+    for (const auto & b : hopefullyBuiltPaths)
         std::visit(
             overloaded{
-                [&](DerivedPath::Opaque bo) {
+                [&](const DerivedPath::Opaque & bo) {
                     res.push_back(BuiltPath::Opaque{bo.path});
                 },
-                [&](DerivedPath::Built bfd) {
+                [&](const DerivedPath::Built & bfd) {
                     OutputPathMap outputs;
                     auto drv = evalStore->readDerivation(bfd.drvPath);
                     auto outputHashes = staticOutputHashes(*evalStore, drv); // FIXME: expensive
@@ -823,10 +823,10 @@ StorePathSet toDerivations(
 {
     StorePathSet drvPaths;
 
-    for (auto & i : installables)
-        for (auto & b : i->toDerivedPaths())
+    for (const auto & i : installables)
+        for (const auto & b : i->toDerivedPaths())
             std::visit(overloaded {
-                [&](DerivedPath::Opaque bo) {
+                [&](const DerivedPath::Opaque & bo) {
                     if (!useDeriver)
                         throw Error("argument '%s' did not evaluate to a derivation", i->what());
                     auto derivers = store->queryValidDerivers(bo.path);
@@ -835,7 +835,7 @@ StorePathSet toDerivations(
                     // FIXME: use all derivers?
                     drvPaths.insert(*derivers.begin());
                 },
-                [&](DerivedPath::Built bfd) {
+                [&](const DerivedPath::Built & bfd) {
                     drvPaths.insert(bfd.drvPath);
                 },
             }, b.raw());
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 0422102a9..3bf091438 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1174,7 +1174,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
         // hash per output.
         auto hashModulo = hashDerivationModulo(*state.store, Derivation(drv), true);
         std::visit(overloaded {
-            [&](Hash h) {
+            [&](Hash & h) {
                 for (auto & i : outputs) {
                     auto outPath = state.store->makeOutputPath(i, h, drvName);
                     drv.env[i] = state.store->printStorePath(outPath);
@@ -1186,11 +1186,11 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
                         });
                 }
             },
-            [&](CaOutputHashes) {
+            [&](CaOutputHashes &) {
                 // Shouldn't happen as the toplevel derivation is not CA.
                 assert(false);
             },
-            [&](DeferredHash _) {
+            [&](DeferredHash &) {
                 for (auto & i : outputs) {
                     drv.outputs.insert_or_assign(i,
                         DerivationOutput {
diff --git a/src/libstore/build/entry-points.cc b/src/libstore/build/entry-points.cc
index 96deb81d1..2b77e4354 100644
--- a/src/libstore/build/entry-points.cc
+++ b/src/libstore/build/entry-points.cc
@@ -11,12 +11,12 @@ void Store::buildPaths(const std::vector<DerivedPath> & reqs, BuildMode buildMod
     Worker worker(*this, evalStore ? *evalStore : *this);
 
     Goals goals;
-    for (auto & br : reqs) {
+    for (const auto & br : reqs) {
         std::visit(overloaded {
-            [&](DerivedPath::Built bfd) {
+            [&](const DerivedPath::Built & bfd) {
                 goals.insert(worker.makeDerivationGoal(bfd.drvPath, bfd.outputs, buildMode));
             },
-            [&](DerivedPath::Opaque bo) {
+            [&](const DerivedPath::Opaque & bo) {
                 goals.insert(worker.makePathSubstitutionGoal(bo.path, buildMode == bmRepair ? Repair : NoRepair));
             },
         }, br.raw());
diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 3aa9f12fe..e91e35851 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -1094,10 +1094,10 @@ void LocalDerivationGoal::writeStructuredAttrs()
 static StorePath pathPartOfReq(const DerivedPath & req)
 {
     return std::visit(overloaded {
-        [&](DerivedPath::Opaque bo) {
+        [&](const DerivedPath::Opaque & bo) {
             return bo.path;
         },
-        [&](DerivedPath::Built bfd)  {
+        [&](const DerivedPath::Built & bfd)  {
             return bfd.drvPath;
         },
     }, req.raw());
@@ -2155,8 +2155,8 @@ void LocalDerivationGoal::registerOutputs()
                 /* Since we'll use the already installed versions of these, we
                    can treat them as leaves and ignore any references they
                    have. */
-                [&](AlreadyRegistered _) { return StringSet {}; },
-                [&](PerhapsNeedToRegister refs) {
+                [&](const AlreadyRegistered &) { return StringSet {}; },
+                [&](const PerhapsNeedToRegister & refs) {
                     StringSet referencedOutputs;
                     /* FIXME build inverted map up front so no quadratic waste here */
                     for (auto & r : refs.refs)
@@ -2192,11 +2192,11 @@ void LocalDerivationGoal::registerOutputs()
         };
 
         std::optional<StorePathSet> referencesOpt = std::visit(overloaded {
-            [&](AlreadyRegistered skippedFinalPath) -> std::optional<StorePathSet> {
+            [&](const AlreadyRegistered & skippedFinalPath) -> std::optional<StorePathSet> {
                 finish(skippedFinalPath.path);
                 return std::nullopt;
             },
-            [&](PerhapsNeedToRegister r) -> std::optional<StorePathSet> {
+            [&](const PerhapsNeedToRegister & r) -> std::optional<StorePathSet> {
                 return r.refs;
             },
         }, outputReferencesIfUnregistered.at(outputName));
@@ -2312,7 +2312,7 @@ void LocalDerivationGoal::registerOutputs()
         };
 
         ValidPathInfo newInfo = std::visit(overloaded {
-            [&](DerivationOutputInputAddressed output) {
+            [&](const DerivationOutputInputAddressed & output) {
                 /* input-addressed case */
                 auto requiredFinalPath = output.path;
                 /* Preemptively add rewrite rule for final hash, as that is
@@ -2331,14 +2331,14 @@ void LocalDerivationGoal::registerOutputs()
                     newInfo0.references.insert(newInfo0.path);
                 return newInfo0;
             },
-            [&](DerivationOutputCAFixed dof) {
+            [&](const DerivationOutputCAFixed & dof) {
                 auto newInfo0 = newInfoFromCA(DerivationOutputCAFloating {
                     .method = dof.hash.method,
                     .hashType = dof.hash.hash.type,
                 });
 
                 /* Check wanted hash */
-                Hash & wanted = dof.hash.hash;
+                const Hash & wanted = dof.hash.hash;
                 assert(newInfo0.ca);
                 auto got = getContentAddressHash(*newInfo0.ca);
                 if (wanted != got) {
diff --git a/src/libstore/content-address.cc b/src/libstore/content-address.cc
index 90a3ad1f5..974d1c471 100644
--- a/src/libstore/content-address.cc
+++ b/src/libstore/content-address.cc
@@ -31,10 +31,10 @@ std::string makeFixedOutputCA(FileIngestionMethod method, const Hash & hash)
 std::string renderContentAddress(ContentAddress ca)
 {
     return std::visit(overloaded {
-        [](TextHash th) {
+        [](TextHash & th) {
             return "text:" + th.hash.to_string(Base32, true);
         },
-        [](FixedOutputHash fsh) {
+        [](FixedOutputHash & fsh) {
             return makeFixedOutputCA(fsh.method, fsh.hash);
         }
     }, ca);
@@ -43,10 +43,10 @@ std::string renderContentAddress(ContentAddress ca)
 std::string renderContentAddressMethod(ContentAddressMethod cam)
 {
     return std::visit(overloaded {
-        [](TextHashMethod &th) {
+        [](TextHashMethod & th) {
             return std::string{"text:"} + printHashType(htSHA256);
         },
-        [](FixedOutputHashMethod &fshm) {
+        [](FixedOutputHashMethod & fshm) {
             return "fixed:" + makeFileIngestionPrefix(fshm.fileIngestionMethod) + printHashType(fshm.hashType);
         }
     }, cam);
@@ -104,12 +104,12 @@ ContentAddress parseContentAddress(std::string_view rawCa) {
 
     return std::visit(
         overloaded {
-            [&](TextHashMethod thm) {
+            [&](TextHashMethod & thm) {
                 return ContentAddress(TextHash {
                     .hash = Hash::parseNonSRIUnprefixed(rest, htSHA256)
                 });
             },
-            [&](FixedOutputHashMethod fohMethod) {
+            [&](FixedOutputHashMethod & fohMethod) {
                 return ContentAddress(FixedOutputHash {
                     .method = fohMethod.fileIngestionMethod,
                     .hash = Hash::parseNonSRIUnprefixed(rest, std::move(fohMethod.hashType)),
@@ -137,10 +137,10 @@ std::string renderContentAddress(std::optional<ContentAddress> ca)
 Hash getContentAddressHash(const ContentAddress & ca)
 {
     return std::visit(overloaded {
-        [](TextHash th) {
+        [](const TextHash & th) {
             return th.hash;
         },
-        [](FixedOutputHash fsh) {
+        [](const FixedOutputHash & fsh) {
             return fsh.hash;
         }
     }, ca);
diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index 487416a13..164a9b2be 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -395,13 +395,13 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
                 FramedSource source(from);
                 // TODO this is essentially RemoteStore::addCAToStore. Move it up to Store.
                 return std::visit(overloaded {
-                    [&](TextHashMethod &_) {
+                    [&](TextHashMethod &) {
                         // We could stream this by changing Store
                         std::string contents = source.drain();
                         auto path = store->addTextToStore(name, contents, refs, repair);
                         return store->queryPathInfo(path);
                     },
-                    [&](FixedOutputHashMethod &fohm) {
+                    [&](FixedOutputHashMethod & fohm) {
                         if (!refs.empty())
                             throw UnimplementedError("cannot yet have refs with flat or nar-hashed data");
                         auto path = store->addToStoreFromDump(source, name, fohm.fileIngestionMethod, fohm.hashType, repair);
diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index 899475860..ef8765841 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -10,18 +10,18 @@ namespace nix {
 std::optional<StorePath> DerivationOutput::path(const Store & store, std::string_view drvName, std::string_view outputName) const
 {
     return std::visit(overloaded {
-        [](DerivationOutputInputAddressed doi) -> std::optional<StorePath> {
+        [](const DerivationOutputInputAddressed & doi) -> std::optional<StorePath> {
             return { doi.path };
         },
-        [&](DerivationOutputCAFixed dof) -> std::optional<StorePath> {
+        [&](const DerivationOutputCAFixed & dof) -> std::optional<StorePath> {
             return {
                 dof.path(store, drvName, outputName)
             };
         },
-        [](DerivationOutputCAFloating dof) -> std::optional<StorePath> {
+        [](const DerivationOutputCAFloating & dof) -> std::optional<StorePath> {
             return std::nullopt;
         },
-        [](DerivationOutputDeferred) -> std::optional<StorePath> {
+        [](const DerivationOutputDeferred &) -> std::optional<StorePath> {
             return std::nullopt;
         },
     }, output);
@@ -332,22 +332,22 @@ string Derivation::unparse(const Store & store, bool maskOutputs,
         if (first) first = false; else s += ',';
         s += '('; printUnquotedString(s, i.first);
         std::visit(overloaded {
-            [&](DerivationOutputInputAddressed doi) {
+            [&](const DerivationOutputInputAddressed & doi) {
                 s += ','; printUnquotedString(s, maskOutputs ? "" : store.printStorePath(doi.path));
                 s += ','; printUnquotedString(s, "");
                 s += ','; printUnquotedString(s, "");
             },
-            [&](DerivationOutputCAFixed dof) {
+            [&](const DerivationOutputCAFixed & dof) {
                 s += ','; printUnquotedString(s, maskOutputs ? "" : store.printStorePath(dof.path(store, name, i.first)));
                 s += ','; printUnquotedString(s, dof.hash.printMethodAlgo());
                 s += ','; printUnquotedString(s, dof.hash.hash.to_string(Base16, false));
             },
-            [&](DerivationOutputCAFloating dof) {
+            [&](const DerivationOutputCAFloating & dof) {
                 s += ','; printUnquotedString(s, "");
                 s += ','; printUnquotedString(s, makeFileIngestionPrefix(dof.method) + printHashType(dof.hashType));
                 s += ','; printUnquotedString(s, "");
             },
-            [&](DerivationOutputDeferred) {
+            [&](const DerivationOutputDeferred &) {
                 s += ','; printUnquotedString(s, "");
                 s += ','; printUnquotedString(s, "");
                 s += ','; printUnquotedString(s, "");
@@ -420,13 +420,13 @@ DerivationType BasicDerivation::type() const
     std::optional<HashType> floatingHashType;
     for (auto & i : outputs) {
         std::visit(overloaded {
-            [&](DerivationOutputInputAddressed _) {
+            [&](const DerivationOutputInputAddressed &) {
                inputAddressedOutputs.insert(i.first);
             },
-            [&](DerivationOutputCAFixed _) {
+            [&](const DerivationOutputCAFixed &) {
                 fixedCAOutputs.insert(i.first);
             },
-            [&](DerivationOutputCAFloating dof) {
+            [&](const DerivationOutputCAFloating & dof) {
                 floatingCAOutputs.insert(i.first);
                 if (!floatingHashType) {
                     floatingHashType = dof.hashType;
@@ -435,7 +435,7 @@ DerivationType BasicDerivation::type() const
                         throw Error("All floating outputs must use the same hash type");
                 }
             },
-            [&](DerivationOutputDeferred _) {
+            [&](const DerivationOutputDeferred &) {
                deferredIAOutputs.insert(i.first);
             },
         }, i.second.output);
@@ -538,15 +538,15 @@ DrvHashModulo hashDerivationModulo(Store & store, const Derivation & drv, bool m
         const auto & res = pathDerivationModulo(store, i.first);
         std::visit(overloaded {
             // Regular non-CA derivation, replace derivation
-            [&](Hash drvHash) {
+            [&](const Hash & drvHash) {
                 inputs2.insert_or_assign(drvHash.to_string(Base16, false), i.second);
             },
-            [&](DeferredHash deferredHash) {
+            [&](const DeferredHash & deferredHash) {
                 isDeferred = true;
                 inputs2.insert_or_assign(deferredHash.hash.to_string(Base16, false), i.second);
             },
             // CA derivation's output hashes
-            [&](CaOutputHashes outputHashes) {
+            [&](const CaOutputHashes & outputHashes) {
                 std::set<std::string> justOut = { "out" };
                 for (auto & output : i.second) {
                     /* Put each one in with a single "out" output.. */
@@ -572,17 +572,17 @@ std::map<std::string, Hash> staticOutputHashes(Store & store, const Derivation &
 {
     std::map<std::string, Hash> res;
     std::visit(overloaded {
-        [&](Hash drvHash) {
+        [&](const Hash & drvHash) {
             for (auto & outputName : drv.outputNames()) {
                 res.insert({outputName, drvHash});
             }
         },
-        [&](DeferredHash deferredHash) {
+        [&](const DeferredHash & deferredHash) {
             for (auto & outputName : drv.outputNames()) {
                 res.insert({outputName, deferredHash.hash});
             }
         },
-        [&](CaOutputHashes outputHashes) {
+        [&](const CaOutputHashes & outputHashes) {
             res = outputHashes;
         },
     }, hashDerivationModulo(store, drv, true));
@@ -666,22 +666,22 @@ void writeDerivation(Sink & out, const Store & store, const BasicDerivation & dr
     for (auto & i : drv.outputs) {
         out << i.first;
         std::visit(overloaded {
-            [&](DerivationOutputInputAddressed doi) {
+            [&](const DerivationOutputInputAddressed & doi) {
                 out << store.printStorePath(doi.path)
                     << ""
                     << "";
             },
-            [&](DerivationOutputCAFixed dof) {
+            [&](const DerivationOutputCAFixed & dof) {
                 out << store.printStorePath(dof.path(store, drv.name, i.first))
                     << dof.hash.printMethodAlgo()
                     << dof.hash.hash.to_string(Base16, false);
             },
-            [&](DerivationOutputCAFloating dof) {
+            [&](const DerivationOutputCAFloating & dof) {
                 out << ""
                     << (makeFileIngestionPrefix(dof.method) + printHashType(dof.hashType))
                     << "";
             },
-            [&](DerivationOutputDeferred) {
+            [&](const DerivationOutputDeferred &) {
                 out << ""
                     << ""
                     << "";
diff --git a/src/libstore/derived-path.cc b/src/libstore/derived-path.cc
index 8da81d0ac..e55af21e9 100644
--- a/src/libstore/derived-path.cc
+++ b/src/libstore/derived-path.cc
@@ -24,8 +24,8 @@ StorePathSet BuiltPath::outPaths() const
 {
     return std::visit(
         overloaded{
-            [](BuiltPath::Opaque p) { return StorePathSet{p.path}; },
-            [](BuiltPath::Built b) {
+            [](const BuiltPath::Opaque & p) { return StorePathSet{p.path}; },
+            [](const BuiltPath::Built & b) {
                 StorePathSet res;
                 for (auto & [_, path] : b.outputs)
                     res.insert(path);
@@ -94,8 +94,8 @@ RealisedPath::Set BuiltPath::toRealisedPaths(Store & store) const
     RealisedPath::Set res;
     std::visit(
         overloaded{
-            [&](BuiltPath::Opaque p) { res.insert(p.path); },
-            [&](BuiltPath::Built p) {
+            [&](const BuiltPath::Opaque & p) { res.insert(p.path); },
+            [&](const BuiltPath::Built & p) {
                 auto drvHashes =
                     staticOutputHashes(store, store.readDerivation(p.drvPath));
                 for (auto& [outputName, outputPath] : p.outputs) {
diff --git a/src/libstore/legacy-ssh-store.cc b/src/libstore/legacy-ssh-store.cc
index c660d7f5b..7ae4e7c24 100644
--- a/src/libstore/legacy-ssh-store.cc
+++ b/src/libstore/legacy-ssh-store.cc
@@ -290,10 +290,10 @@ public:
         for (auto & p : drvPaths) {
             auto sOrDrvPath = StorePathWithOutputs::tryFromDerivedPath(p);
             std::visit(overloaded {
-                [&](StorePathWithOutputs s) {
+                [&](const StorePathWithOutputs & s) {
                     ss.push_back(s.to_string(*this));
                 },
-                [&](StorePath drvPath) {
+                [&](const StorePath & drvPath) {
                     throw Error("wanted to fetch '%s' but the legacy ssh protocol doesn't support merely substituting drv files via the build paths command. It would build them instead. Try using ssh-ng://", printStorePath(drvPath));
                 },
             }, sOrDrvPath);
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 634e9eb8b..5b2490472 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -681,7 +681,7 @@ void LocalStore::checkDerivationOutputs(const StorePath & drvPath, const Derivat
     std::optional<Hash> h;
     for (auto & i : drv.outputs) {
         std::visit(overloaded {
-            [&](DerivationOutputInputAddressed doia) {
+            [&](const DerivationOutputInputAddressed & doia) {
                 if (!h) {
                     // somewhat expensive so we do lazily
                     auto temp = hashDerivationModulo(*this, drv, true);
@@ -693,14 +693,14 @@ void LocalStore::checkDerivationOutputs(const StorePath & drvPath, const Derivat
                         printStorePath(drvPath), printStorePath(doia.path), printStorePath(recomputed));
                 envHasRightPath(doia.path, i.first);
             },
-            [&](DerivationOutputCAFixed dof) {
+            [&](const DerivationOutputCAFixed & dof) {
                 StorePath path = makeFixedOutputPath(dof.hash.method, dof.hash.hash, drvName);
                 envHasRightPath(path, i.first);
             },
-            [&](DerivationOutputCAFloating _) {
+            [&](const DerivationOutputCAFloating &) {
                 /* Nothing to check */
             },
-            [&](DerivationOutputDeferred) {
+            [&](const DerivationOutputDeferred &) {
             },
         }, i.second.output);
     }
diff --git a/src/libstore/misc.cc b/src/libstore/misc.cc
index b4929b445..f184dd857 100644
--- a/src/libstore/misc.cc
+++ b/src/libstore/misc.cc
@@ -166,7 +166,7 @@ void Store::queryMissing(const std::vector<DerivedPath> & targets,
         }
 
         std::visit(overloaded {
-          [&](DerivedPath::Built bfd) {
+          [&](const DerivedPath::Built & bfd) {
             if (!isValidPath(bfd.drvPath)) {
                 // FIXME: we could try to substitute the derivation.
                 auto state(state_.lock());
@@ -199,7 +199,7 @@ void Store::queryMissing(const std::vector<DerivedPath> & targets,
                 mustBuildDrv(bfd.drvPath, *drv);
 
           },
-          [&](DerivedPath::Opaque bo) {
+          [&](const DerivedPath::Opaque & bo) {
 
             if (isValidPath(bo.path)) return;
 
diff --git a/src/libstore/path-with-outputs.cc b/src/libstore/path-with-outputs.cc
index 865d64cf2..e5a121e00 100644
--- a/src/libstore/path-with-outputs.cc
+++ b/src/libstore/path-with-outputs.cc
@@ -31,14 +31,14 @@ std::vector<DerivedPath> toDerivedPaths(const std::vector<StorePathWithOutputs>
 std::variant<StorePathWithOutputs, StorePath> StorePathWithOutputs::tryFromDerivedPath(const DerivedPath & p)
 {
     return std::visit(overloaded {
-        [&](DerivedPath::Opaque bo) -> std::variant<StorePathWithOutputs, StorePath> {
+        [&](const DerivedPath::Opaque & bo) -> std::variant<StorePathWithOutputs, StorePath> {
             if (bo.path.isDerivation()) {
                 // drv path gets interpreted as "build", not "get drv file itself"
                 return bo.path;
             }
             return StorePathWithOutputs { bo.path };
         },
-        [&](DerivedPath::Built bfd) -> std::variant<StorePathWithOutputs, StorePath> {
+        [&](const DerivedPath::Built & bfd) -> std::variant<StorePathWithOutputs, StorePath> {
             return StorePathWithOutputs { bfd.drvPath, bfd.outputs };
         },
     }, p.raw());
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index b57a4cb05..fa5ea8af7 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -528,13 +528,13 @@ ref<const ValidPathInfo> RemoteStore::addCAToStore(
         if (repair) throw Error("repairing is not supported when building through the Nix daemon protocol < 1.25");
 
         std::visit(overloaded {
-            [&](TextHashMethod thm) -> void {
+            [&](const TextHashMethod & thm) -> void {
                 std::string s = dump.drain();
                 conn->to << wopAddTextToStore << name << s;
                 worker_proto::write(*this, conn->to, references);
                 conn.processStderr();
             },
-            [&](FixedOutputHashMethod fohm) -> void {
+            [&](const FixedOutputHashMethod & fohm) -> void {
                 conn->to
                     << wopAddToStore
                     << name
@@ -705,10 +705,10 @@ static void writeDerivedPaths(RemoteStore & store, ConnectionHandle & conn, cons
         for (auto & p : reqs) {
             auto sOrDrvPath = StorePathWithOutputs::tryFromDerivedPath(p);
             std::visit(overloaded {
-                [&](StorePathWithOutputs s) {
+                [&](const StorePathWithOutputs & s) {
                     ss.push_back(s.to_string(store));
                 },
-                [&](StorePath drvPath) {
+                [&](const StorePath & drvPath) {
                     throw Error("trying to request '%s', but daemon protocol %d.%d is too old (< 1.29) to request a derivation file",
                         store.printStorePath(drvPath),
                         GET_PROTOCOL_MAJOR(conn->daemonVersion),
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 970bafd88..b5ff3dccf 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -199,10 +199,10 @@ StorePath Store::makeFixedOutputPathFromCA(std::string_view name, ContentAddress
 {
     // New template
     return std::visit(overloaded {
-        [&](TextHash th) {
+        [&](const TextHash & th) {
             return makeTextPath(name, th.hash, references);
         },
-        [&](FixedOutputHash fsh) {
+        [&](const FixedOutputHash & fsh) {
             return makeFixedOutputPath(fsh.method, fsh.hash, name, references, hasSelfReference);
         }
     }, ca);
@@ -1114,10 +1114,10 @@ bool ValidPathInfo::isContentAddressed(const Store & store) const
     if (! ca) return false;
 
     auto caPath = std::visit(overloaded {
-        [&](TextHash th) {
+        [&](const TextHash & th) {
             return store.makeTextPath(path.name(), th.hash, references);
         },
-        [&](FixedOutputHash fsh) {
+        [&](const FixedOutputHash & fsh) {
             auto refs = references;
             bool hasSelfReference = false;
             if (refs.count(path)) {
diff --git a/src/nix/build.cc b/src/nix/build.cc
index ce6df7df8..6e31757a2 100644
--- a/src/nix/build.cc
+++ b/src/nix/build.cc
@@ -66,12 +66,12 @@ struct CmdBuild : InstallablesCommand, MixDryRun, MixJSON, MixProfile
                 for (const auto & [_i, buildable] : enumerate(buildables)) {
                     auto i = _i;
                     std::visit(overloaded {
-                        [&](BuiltPath::Opaque bo) {
+                        [&](const BuiltPath::Opaque & bo) {
                             std::string symlink = outLink;
                             if (i) symlink += fmt("-%d", i);
                             store2->addPermRoot(bo.path, absPath(symlink));
                         },
-                        [&](BuiltPath::Built bfd) {
+                        [&](const BuiltPath::Built & bfd) {
                             for (auto & output : bfd.outputs) {
                                 std::string symlink = outLink;
                                 if (i) symlink += fmt("-%d", i);
diff --git a/src/nix/log.cc b/src/nix/log.cc
index 962c47525..fd3c1d787 100644
--- a/src/nix/log.cc
+++ b/src/nix/log.cc
@@ -35,10 +35,10 @@ struct CmdLog : InstallableCommand
         RunPager pager;
         for (auto & sub : subs) {
             auto log = std::visit(overloaded {
-                [&](DerivedPath::Opaque bo) {
+                [&](const DerivedPath::Opaque & bo) {
                     return sub->getBuildLog(bo.path);
                 },
-                [&](DerivedPath::Built bfd) {
+                [&](const DerivedPath::Built & bfd) {
                     return sub->getBuildLog(bfd.drvPath);
                 },
             }, b.raw());
diff --git a/src/nix/profile.cc b/src/nix/profile.cc
index a1cb3fc76..c63ed9c88 100644
--- a/src/nix/profile.cc
+++ b/src/nix/profile.cc
@@ -260,11 +260,11 @@ struct CmdProfileInstall : InstallablesCommand, MixDefaultProfile
                     ProfileElement element;
 
                     std::visit(overloaded {
-                        [&](BuiltPath::Opaque bo) {
+                        [&](const BuiltPath::Opaque & bo) {
                             pathsToBuild.push_back(bo);
                             element.storePaths.insert(bo.path);
                         },
-                        [&](BuiltPath::Built bfd) {
+                        [&](const BuiltPath::Built & bfd) {
                             // TODO: Why are we querying if we know the output
                             // names already? Is it just to figure out what the
                             // default one is?
diff --git a/src/nix/show-derivation.cc b/src/nix/show-derivation.cc
index 2588a011d..c614be68d 100644
--- a/src/nix/show-derivation.cc
+++ b/src/nix/show-derivation.cc
@@ -65,18 +65,18 @@ struct CmdShowDerivation : InstallablesCommand
                     auto & outputName = _outputName; // work around clang bug
                     auto outputObj { outputsObj.object(outputName) };
                     std::visit(overloaded {
-                        [&](DerivationOutputInputAddressed doi) {
+                        [&](const DerivationOutputInputAddressed & doi) {
                             outputObj.attr("path", store->printStorePath(doi.path));
                         },
-                        [&](DerivationOutputCAFixed dof) {
+                        [&](const DerivationOutputCAFixed & dof) {
                             outputObj.attr("path", store->printStorePath(dof.path(*store, drv.name, outputName)));
                             outputObj.attr("hashAlgo", dof.hash.printMethodAlgo());
                             outputObj.attr("hash", dof.hash.hash.to_string(Base16, false));
                         },
-                        [&](DerivationOutputCAFloating dof) {
+                        [&](const DerivationOutputCAFloating & dof) {
                             outputObj.attr("hashAlgo", makeFileIngestionPrefix(dof.method) + printHashType(dof.hashType));
                         },
-                        [&](DerivationOutputDeferred) {},
+                        [&](const DerivationOutputDeferred &) {},
                     }, output.output);
                 }
             }

From 91b39eee25f74ddc4e0411ad08c7f643c09b4c6b Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 1 Oct 2021 14:18:07 +0200
Subject: [PATCH 043/567] Typo

Co-authored-by: Sebastian Ullrich <sebasti@nullri.ch>
---
 doc/manual/src/release-notes/rl-2.4.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/manual/src/release-notes/rl-2.4.md b/doc/manual/src/release-notes/rl-2.4.md
index 25db72b31..c0fcedefd 100644
--- a/doc/manual/src/release-notes/rl-2.4.md
+++ b/doc/manual/src/release-notes/rl-2.4.md
@@ -221,7 +221,7 @@ more than 2800 commits from 195 contributors since release 2.3.
   evaluation result.
 
 * `nix eval` has a new `--write-to` flag that allows it to write a
-  nested attribute set of string leaves to a correspondingly directory
+  nested attribute set of string leaves to a corresponding directory
   tree.
 
 * Memory improvements: many operations that add paths to the store or

From 43221bb319081f33d721d57f1b8905c78cf44e4e Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 1 Oct 2021 16:29:53 +0200
Subject: [PATCH 044/567] Comments

---
 doc/manual/src/release-notes/rl-2.4.md | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/doc/manual/src/release-notes/rl-2.4.md b/doc/manual/src/release-notes/rl-2.4.md
index c0fcedefd..3ddd53315 100644
--- a/doc/manual/src/release-notes/rl-2.4.md
+++ b/doc/manual/src/release-notes/rl-2.4.md
@@ -23,7 +23,9 @@ more than 2800 commits from 195 contributors since release 2.3.
 * The **`nix` command** has seen a lot of work and is now almost at
   feature parity with the old command-line interface (the `nix-*`
   commands). It aims to be [more modern, consistent and pleasant to
-  use](../contributing/cli-guideline.md) than the old CLI.
+  use](../contributing/cli-guideline.md) than the old CLI. It is still
+  marked as experimental but its interface should not change much
+  anymore in future releases.
 
 * **Flakes** are a new format to package Nix-based projects in a more
   discoverable, composable, consistent and reproducible way. A flake
@@ -180,8 +182,9 @@ more than 2800 commits from 195 contributors since release 2.3.
 * **New built-in functions**:
 
   - `builtins.fetchTree` allows fetching a source tree using any
-    backends supported by the fetcher infrastructure. It replaces
-    `fetchGit`, `fetchMercurial` and `fetchTarball`.
+    backends supported by the fetcher infrastructure. It subsumes the
+    functionality of existing built-ins like `fetchGit`,
+    `fetchMercurial` and `fetchTarball`.
 
   - `builtins.getFlake` fetches a flake and returns its output
     attributes. This function should not be used inside flakes! Use
@@ -247,6 +250,8 @@ more than 2800 commits from 195 contributors since release 2.3.
 
   - With `-p`, it passes any `--arg`s as Nixpkgs arguments.
 
+  - Support for structured attributes.
+
 * `nix-prefetch-url` has a new `--executable` flag.
 
 * On `x86_64` systems, [`x86_64` microarchitecture
@@ -281,7 +286,8 @@ more than 2800 commits from 195 contributors since release 2.3.
   to your `nix.conf` if you want to use it, or pass
   `--extra-experimental-features nix-command` on the command line.
 
-* `nix run` has been renamed to `nix shell`.
+* The old `nix run` has been renamed to `nix shell` (and there is a
+  new `nix run` that does something else, as described above).
 
 * It is now an error to modify the `plugin-files` setting via a
   command-line flag that appears after the first non-flag argument to
@@ -290,7 +296,7 @@ more than 2800 commits from 195 contributors since release 2.3.
   `nix-instantiate --plugin-files "" default.nix`.
 
 * We no longer release source tarballs. If you want to build from
-  source, please build from the Git repository.
+  source, please build from the tags in the Git repository.
 
 ## Contributors
 

From 0e3b8ca76701a86208d3a83db4f324ace9a28f23 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 1 Oct 2021 16:32:07 +0200
Subject: [PATCH 045/567] Typo

---
 doc/manual/src/release-notes/rl-2.4.md | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/doc/manual/src/release-notes/rl-2.4.md b/doc/manual/src/release-notes/rl-2.4.md
index 3ddd53315..def4a7b66 100644
--- a/doc/manual/src/release-notes/rl-2.4.md
+++ b/doc/manual/src/release-notes/rl-2.4.md
@@ -47,7 +47,7 @@ more than 2800 commits from 195 contributors since release 2.3.
   contents. Previously Nix could only build **input-addressed** store
   paths, where the hash is computed from the derivation dependency
   graph. Content-addressing allows deduplication, early cutoff in
-  build systems, and unpriviliged closure copying. This is still [an
+  build systems, and unprivileged closure copying. This is still [an
   experimental
   feature](https://discourse.nixos.org/t/content-addressed-nix-call-for-testers/12881).
 
@@ -96,7 +96,7 @@ more than 2800 commits from 195 contributors since release 2.3.
     program from the `hello` package in `nixpkgs`.
 
   - `nix flake` is the container for flake-related operations, such as
-    creating a new flake, quering the contents of a flake or updating
+    creating a new flake, querying the contents of a flake or updating
     flake lock files.
 
   - `nix registry` allows you to query and update the flake registry,
@@ -116,7 +116,7 @@ more than 2800 commits from 195 contributors since release 2.3.
       changes.
 
     **Warning**: after a profile has been updated using `nix profile`,
-    it is no longer useable with `nix-env`.
+    it is no longer usable with `nix-env`.
 
   - `nix store diff-closures` shows the differences between the
     closures of two store paths in terms of the versions and sizes of
@@ -205,7 +205,7 @@ more than 2800 commits from 195 contributors since release 2.3.
 * Nix now uses `libarchive` to decompress and unpack tarballs and zip
   files, so `tar` is no longer required.
 
-* The priority of substituters can now be overriden using the
+* The priority of substituters can now be overridden using the
   `priority` substituter setting (e.g. `--substituters
   'http://cache.nixos.org?priority=100 daemon?priority=10'`).
 

From 621aa65325f11769d33704b00dc15bc7dda49f0f Mon Sep 17 00:00:00 2001
From: Sergei Trofimovich <slyich@gmail.com>
Date: Thu, 30 Sep 2021 22:08:14 +0100
Subject: [PATCH 046/567] local-derivation-goal.cc: downgrade "warning:
 rewriting hashes in..." down to debug

Before the changes when building the whole system with
`contentAddressedByDefault = true;` we get many noninformative messages:

    $ nix build -f nixos system --keep-going
    ...
    warning: rewriting hashes in '/nix/store/...-clang-11.1.0.drv.chroot/nix/store/...-11.1.0'; cross fingers
    warning: rewriting hashes in '/nix/store/...-clang-11.1.0.drv.chroot/nix/store/...-11.1.0-dev'; cross fingers
    warning: rewriting hashes in '/nix/store/...-clang-11.1.0.drv.chroot/nix/store/...-11.1.0-python'; cross fingers
    error: 2 dependencies of derivation '/nix/store/...-hub-2.14.2.drv' failed to build
    warning: rewriting hashes in '/nix/store/...-subversion-1.14.1.drv.chroot/nix/store/...-subversion-1.14.1-dev'; cross fingers
    warning: rewriting hashes in '/nix/store/...-subversion-1.14.1.drv.chroot/nix/store/...-subversion-1.14.1-man'; cross fingers
    ...

Let's downgrade these messages down to debug().
---
 src/libstore/build/local-derivation-goal.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index e91e35851..b1852a6bb 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -2208,7 +2208,7 @@ void LocalDerivationGoal::registerOutputs()
         auto rewriteOutput = [&]() {
             /* Apply hash rewriting if necessary. */
             if (!outputRewrites.empty()) {
-                warn("rewriting hashes in '%1%'; cross fingers", actualPath);
+                debug("rewriting hashes in '%1%'; cross fingers", actualPath);
 
                 /* FIXME: this is in-memory. */
                 StringSink sink;

From 3e884aa0028a34a57856b6b009bfce5ccfdfd6ea Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Sat, 2 Oct 2021 10:17:45 +0300
Subject: [PATCH 047/567] Fix typo

---
 src/nix/flake.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/nix/flake.md b/src/nix/flake.md
index 3d273100b..3b5812a0a 100644
--- a/src/nix/flake.md
+++ b/src/nix/flake.md
@@ -225,7 +225,7 @@ Currently the `type` attribute can be one of the following:
   [flake:]<flake-id>(/<rev-or-ref>(/rev)?)?
   ```
 
-  These perform a lookup of `<flake-id>` in the flake registry. or
+  These perform a lookup of `<flake-id>` in the flake registry. For
   example, `nixpkgs` and `nixpkgs/release-20.09` are indirect flake
   references. The specified `rev` and/or `ref` are merged with the
   entry in the registry; see [nix registry](./nix3-registry.md) for

From 1e6faa7d06389b20946038dcdc85f7a1211c628d Mon Sep 17 00:00:00 2001
From: Sergei Trofimovich <slyich@gmail.com>
Date: Sat, 2 Oct 2021 11:09:30 +0100
Subject: [PATCH 048/567] mk/tests.mk: document 'check' and 'installcheck' in
 'make help'

---
 mk/tests.mk | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mk/tests.mk b/mk/tests.mk
index 21bdc5748..a2e30a378 100644
--- a/mk/tests.mk
+++ b/mk/tests.mk
@@ -13,3 +13,7 @@ define run-install-test
 endef
 
 .PHONY: check installcheck
+
+print-top-help += \
+  echo "  check: Run unit tests"; \
+  echo "  installcheck: Run functional tests";

From 638c73776aef397ff04209bb38279c72f0b85136 Mon Sep 17 00:00:00 2001
From: kvtb <76634406+kvtb@users.noreply.github.com>
Date: Sat, 2 Oct 2021 21:04:01 +0000
Subject: [PATCH 049/567] fix creation of NAR files >4GB on 32-bit platforms

`size_t` is 32-bit on 32-bit platforms, while the file size can be bigger
---
 src/libutil/archive.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libutil/archive.cc b/src/libutil/archive.cc
index ed0eb2fb5..d78ec2b93 100644
--- a/src/libutil/archive.cc
+++ b/src/libutil/archive.cc
@@ -42,7 +42,7 @@ static string caseHackSuffix = "~nix~case~hack~";
 PathFilter defaultPathFilter = [](const Path &) { return true; };
 
 
-static void dumpContents(const Path & path, size_t size,
+static void dumpContents(const Path & path, off_t size,
     Sink & sink)
 {
     sink << "contents" << size;
@@ -76,7 +76,7 @@ static void dump(const Path & path, Sink & sink, PathFilter & filter)
         sink << "type" << "regular";
         if (st.st_mode & S_IXUSR)
             sink << "executable" << "";
-        dumpContents(path, (size_t) st.st_size, sink);
+        dumpContents(path, st.st_size, sink);
     }
 
     else if (S_ISDIR(st.st_mode)) {

From a73f855bd4945f6f9d2e8d1d7b7c91509b3fd2ff Mon Sep 17 00:00:00 2001
From: Rafal Gwozdzinski <rafal.gwozdzinski@gmail.com>
Date: Sun, 3 Oct 2021 12:19:59 +0200
Subject: [PATCH 050/567] Fix typo

---
 doc/manual/src/installation/env-variables.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/manual/src/installation/env-variables.md b/doc/manual/src/installation/env-variables.md
index 4a49897e4..bb35c0e9f 100644
--- a/doc/manual/src/installation/env-variables.md
+++ b/doc/manual/src/installation/env-variables.md
@@ -40,7 +40,7 @@ export NIX_SSL_CERT_FILE=/etc/ssl/my-certificate-bundle.crt
 > **Note**
 > 
 > You must not add the export and then do the install, as the Nix
-> installer will detect the presense of Nix configuration, and abort.
+> installer will detect the presence of Nix configuration, and abort.
 
 ## `NIX_SSL_CERT_FILE` with macOS and the Nix daemon
 

From ef34fd0656e844ccc54fd105cdda9970d7e944b4 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 4 Oct 2021 13:47:38 +0200
Subject: [PATCH 051/567] scanForReferences(): Use a StorePathSet

---
 src/libstore/build/local-derivation-goal.cc |  3 +-
 src/libstore/references.cc                  | 35 ++++++++++-----------
 src/libstore/references.hh                  |  6 ++--
 3 files changed, 20 insertions(+), 24 deletions(-)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index b1852a6bb..2ba1b3f59 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -2140,8 +2140,7 @@ void LocalDerivationGoal::registerOutputs()
 
         /* Pass blank Sink as we are not ready to hash data at this stage. */
         NullSink blank;
-        auto references = worker.store.parseStorePathSet(
-            scanForReferences(blank, actualPath, worker.store.printStorePathSet(referenceablePaths)));
+        auto references = scanForReferences(blank, actualPath, referenceablePaths);
 
         outputReferencesIfUnregistered.insert_or_assign(
             outputName,
diff --git a/src/libstore/references.cc b/src/libstore/references.cc
index 3a07c1411..eb70844a2 100644
--- a/src/libstore/references.cc
+++ b/src/libstore/references.cc
@@ -72,43 +72,40 @@ struct RefScanSink : Sink
 };
 
 
-std::pair<PathSet, HashResult> scanForReferences(const string & path,
-    const PathSet & refs)
+std::pair<StorePathSet, HashResult> scanForReferences(
+    const string & path,
+    const StorePathSet & refs)
 {
     HashSink hashSink { htSHA256 };
     auto found = scanForReferences(hashSink, path, refs);
     auto hash = hashSink.finish();
-    return std::pair<PathSet, HashResult>(found, hash);
+    return std::pair<StorePathSet, HashResult>(found, hash);
 }
 
-PathSet scanForReferences(Sink & toTee,
-    const string & path, const PathSet & refs)
+StorePathSet scanForReferences(
+    Sink & toTee,
+    const Path & path,
+    const StorePathSet & refs)
 {
     RefScanSink refsSink;
     TeeSink sink { refsSink, toTee };
-    std::map<string, Path> backMap;
+    std::map<std::string, StorePath> backMap;
 
     for (auto & i : refs) {
-        auto baseName = std::string(baseNameOf(i));
-        string::size_type pos = baseName.find('-');
-        if (pos == string::npos)
-            throw Error("bad reference '%1%'", i);
-        string s = string(baseName, 0, pos);
-        assert(s.size() == refLength);
-        assert(backMap.find(s) == backMap.end());
-        // parseHash(htSHA256, s);
-        refsSink.hashes.insert(s);
-        backMap[s] = i;
+        std::string hashPart(i.hashPart());
+        auto inserted = backMap.emplace(hashPart, i).second;
+        assert(inserted);
+        refsSink.hashes.insert(hashPart);
     }
 
     /* Look for the hashes in the NAR dump of the path. */
     dumpPath(path, sink);
 
     /* Map the hashes found back to their store paths. */
-    PathSet found;
+    StorePathSet found;
     for (auto & i : refsSink.seen) {
-        std::map<string, Path>::iterator j;
-        if ((j = backMap.find(i)) == backMap.end()) abort();
+        auto j = backMap.find(i);
+        assert(j != backMap.end());
         found.insert(j->second);
     }
 
diff --git a/src/libstore/references.hh b/src/libstore/references.hh
index 4f12e6b21..73e674109 100644
--- a/src/libstore/references.hh
+++ b/src/libstore/references.hh
@@ -1,13 +1,13 @@
 #pragma once
 
-#include "types.hh"
 #include "hash.hh"
+#include "path.hh"
 
 namespace nix {
 
-std::pair<PathSet, HashResult> scanForReferences(const Path & path, const PathSet & refs);
+std::pair<StorePathSet, HashResult> scanForReferences(const Path & path, const StorePathSet & refs);
 
-PathSet scanForReferences(Sink & toTee, const Path & path, const PathSet & refs);
+StorePathSet scanForReferences(Sink & toTee, const Path & path, const StorePathSet & refs);
 
 struct RewritingSink : Sink
 {

From 77ebbc9f5425d84e1fed71c8b060c7cc1a57ae79 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 4 Oct 2021 14:29:42 +0200
Subject: [PATCH 052/567] Add a test for RefScanSink and clean up the code

Issue #5322.
---
 Makefile                         |  1 +
 src/libstore/references.cc       | 56 +++++++++++++++-----------------
 src/libstore/references.hh       | 18 ++++++++++
 src/libstore/tests/local.mk      | 15 +++++++++
 src/libstore/tests/references.cc | 45 +++++++++++++++++++++++++
 5 files changed, 105 insertions(+), 30 deletions(-)
 create mode 100644 src/libstore/tests/local.mk
 create mode 100644 src/libstore/tests/references.cc

diff --git a/Makefile b/Makefile
index c7d8967c8..5040d2884 100644
--- a/Makefile
+++ b/Makefile
@@ -4,6 +4,7 @@ makefiles = \
   src/libutil/local.mk \
   src/libutil/tests/local.mk \
   src/libstore/local.mk \
+  src/libstore/tests/local.mk \
   src/libfetchers/local.mk \
   src/libmain/local.mk \
   src/libexpr/local.mk \
diff --git a/src/libstore/references.cc b/src/libstore/references.cc
index eb70844a2..c369b14ac 100644
--- a/src/libstore/references.cc
+++ b/src/libstore/references.cc
@@ -11,11 +11,13 @@
 namespace nix {
 
 
-static unsigned int refLength = 32; /* characters */
+static size_t refLength = 32; /* characters */
 
 
-static void search(const unsigned char * s, size_t len,
-    StringSet & hashes, StringSet & seen)
+static void search(
+    std::string_view s,
+    StringSet & hashes,
+    StringSet & seen)
 {
     static std::once_flag initialised;
     static bool isBase32[256];
@@ -25,7 +27,7 @@ static void search(const unsigned char * s, size_t len,
             isBase32[(unsigned char) base32Chars[i]] = true;
     });
 
-    for (size_t i = 0; i + refLength <= len; ) {
+    for (size_t i = 0; i + refLength <= s.size(); ) {
         int j;
         bool match = true;
         for (j = refLength - 1; j >= 0; --j)
@@ -35,7 +37,7 @@ static void search(const unsigned char * s, size_t len,
                 break;
             }
         if (!match) continue;
-        string ref((const char *) s + i, refLength);
+        std::string ref(s.substr(i, refLength));
         if (hashes.erase(ref)) {
             debug(format("found reference to '%1%' at offset '%2%'")
                   % ref % i);
@@ -46,30 +48,23 @@ static void search(const unsigned char * s, size_t len,
 }
 
 
-struct RefScanSink : Sink
+void RefScanSink::operator () (std::string_view data)
 {
-    StringSet hashes;
-    StringSet seen;
+    /* It's possible that a reference spans the previous and current
+       fragment, so search in the concatenation of the tail of the
+       previous fragment and the start of the current fragment. */
+    auto s = tail;
+    s.append(data.data(), refLength);
+    search(s, hashes, seen);
 
-    string tail;
+    search(data, hashes, seen);
 
-    RefScanSink() { }
-
-    void operator () (std::string_view data) override
-    {
-        /* It's possible that a reference spans the previous and current
-           fragment, so search in the concatenation of the tail of the
-           previous fragment and the start of the current fragment. */
-        string s = tail + std::string(data, 0, refLength);
-        search((const unsigned char *) s.data(), s.size(), hashes, seen);
-
-        search((const unsigned char *) data.data(), data.size(), hashes, seen);
-
-        size_t tailLen = data.size() <= refLength ? data.size() : refLength;
-        tail = std::string(tail, tail.size() < refLength - tailLen ? 0 : tail.size() - (refLength - tailLen));
-        tail.append({data.data() + data.size() - tailLen, tailLen});
-    }
-};
+    auto tailLen = std::min(data.size(), refLength);
+    auto rest = refLength - tailLen;
+    if (rest < tail.size())
+        tail = tail.substr(tail.size() - rest);
+    tail.append(data.data() + data.size() - tailLen, tailLen);
+}
 
 
 std::pair<StorePathSet, HashResult> scanForReferences(
@@ -87,23 +82,24 @@ StorePathSet scanForReferences(
     const Path & path,
     const StorePathSet & refs)
 {
-    RefScanSink refsSink;
-    TeeSink sink { refsSink, toTee };
+    StringSet hashes;
     std::map<std::string, StorePath> backMap;
 
     for (auto & i : refs) {
         std::string hashPart(i.hashPart());
         auto inserted = backMap.emplace(hashPart, i).second;
         assert(inserted);
-        refsSink.hashes.insert(hashPart);
+        hashes.insert(hashPart);
     }
 
     /* Look for the hashes in the NAR dump of the path. */
+    RefScanSink refsSink(std::move(hashes));
+    TeeSink sink { refsSink, toTee };
     dumpPath(path, sink);
 
     /* Map the hashes found back to their store paths. */
     StorePathSet found;
-    for (auto & i : refsSink.seen) {
+    for (auto & i : refsSink.getResult()) {
         auto j = backMap.find(i);
         assert(j != backMap.end());
         found.insert(j->second);
diff --git a/src/libstore/references.hh b/src/libstore/references.hh
index 73e674109..a6119c861 100644
--- a/src/libstore/references.hh
+++ b/src/libstore/references.hh
@@ -9,6 +9,24 @@ std::pair<StorePathSet, HashResult> scanForReferences(const Path & path, const S
 
 StorePathSet scanForReferences(Sink & toTee, const Path & path, const StorePathSet & refs);
 
+class RefScanSink : public Sink
+{
+    StringSet hashes;
+    StringSet seen;
+
+    std::string tail;
+
+public:
+
+    RefScanSink(StringSet && hashes) : hashes(hashes)
+    { }
+
+    StringSet & getResult()
+    { return seen; }
+
+    void operator () (std::string_view data) override;
+};
+
 struct RewritingSink : Sink
 {
     std::string from, to, prev;
diff --git a/src/libstore/tests/local.mk b/src/libstore/tests/local.mk
new file mode 100644
index 000000000..6ae9a0285
--- /dev/null
+++ b/src/libstore/tests/local.mk
@@ -0,0 +1,15 @@
+check: libstore-tests_RUN
+
+programs += libstore-tests
+
+libstore-tests_DIR := $(d)
+
+libstore-tests_INSTALL_DIR :=
+
+libstore-tests_SOURCES := $(wildcard $(d)/*.cc)
+
+libstore-tests_CXXFLAGS += -I src/libstore -I src/libutil
+
+libstore-tests_LIBS = libstore
+
+libstore-tests_LDFLAGS := $(GTEST_LIBS)
diff --git a/src/libstore/tests/references.cc b/src/libstore/tests/references.cc
new file mode 100644
index 000000000..d91d1cedd
--- /dev/null
+++ b/src/libstore/tests/references.cc
@@ -0,0 +1,45 @@
+#include "references.hh"
+
+#include <gtest/gtest.h>
+
+namespace nix {
+
+TEST(references, scan)
+{
+    std::string hash1 = "dc04vv14dak1c1r48qa0m23vr9jy8sm0";
+    std::string hash2 = "zc842j0rz61mjsp3h3wp5ly71ak6qgdn";
+
+    {
+        RefScanSink scanner(StringSet{hash1});
+        auto s = "foobar";
+        scanner(s);
+        ASSERT_EQ(scanner.getResult(), StringSet{});
+    }
+
+    {
+        RefScanSink scanner(StringSet{hash1});
+        auto s = "foobar" + hash1 + "xyzzy";
+        scanner(s);
+        ASSERT_EQ(scanner.getResult(), StringSet{hash1});
+    }
+
+    {
+        RefScanSink scanner(StringSet{hash1, hash2});
+        auto s = "foobar" + hash1 + "xyzzy" + hash2;
+        scanner(((std::string_view) s).substr(0, 10));
+        scanner(((std::string_view) s).substr(10, 5));
+        scanner(((std::string_view) s).substr(15, 5));
+        scanner(((std::string_view) s).substr(20));
+        ASSERT_EQ(scanner.getResult(), StringSet({hash1, hash2}));
+    }
+
+    {
+        RefScanSink scanner(StringSet{hash1, hash2});
+        auto s = "foobar" + hash1 + "xyzzy" + hash2;
+        for (auto & i : s)
+            scanner(std::string(1, i));
+        ASSERT_EQ(scanner.getResult(), StringSet({hash1, hash2}));
+    }
+}
+
+}

From 08cc572f8935f9078ef3747187c65b904d5675c7 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 24 Aug 2021 12:31:49 +0200
Subject: [PATCH 053/567] Revert "Shorten the test drv name"

This reverts commit 5ec873b127139ca90cc31967c25c9a34fb4cc3e4.
---
 flake.nix | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/flake.nix b/flake.nix
index 43123ca7e..91341c97d 100644
--- a/flake.nix
+++ b/flake.nix
@@ -156,10 +156,7 @@
       testNixVersions = pkgs: client: daemon: with commonDeps pkgs; pkgs.stdenv.mkDerivation {
         NIX_DAEMON_PACKAGE = daemon;
         NIX_CLIENT_PACKAGE = client;
-        # Must keep this name short as OSX has a rather strict limit on the
-        # socket path length, and this name appears in the path of the
-        # nix-daemon socket used in the tests
-        name = "nix-tests";
+        name = "nix-tests-${client.version}-against-${daemon.version}";
         inherit version;
 
         src = self;

From 43d4d75e22ea1f7ee2936fe725c1f7ea7a5005e6 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 24 Aug 2021 13:52:55 +0200
Subject: [PATCH 054/567] Connect/bind Unix domain sockets in a child process

In the child process, we can do a chdir() and avoid the problem of the
path not fitting into sockaddr_un.
---
 src/libstore/uds-remote-store.cc | 11 +----
 src/libutil/util.cc              | 71 +++++++++++++++++++++++++++-----
 src/libutil/util.hh              |  8 +++-
 3 files changed, 69 insertions(+), 21 deletions(-)

diff --git a/src/libstore/uds-remote-store.cc b/src/libstore/uds-remote-store.cc
index cfadccf68..02e81b022 100644
--- a/src/libstore/uds-remote-store.cc
+++ b/src/libstore/uds-remote-store.cc
@@ -65,16 +65,7 @@ ref<RemoteStore::Connection> UDSRemoteStore::openConnection()
         throw SysError("cannot create Unix domain socket");
     closeOnExec(conn->fd.get());
 
-    string socketPath = path ? *path : settings.nixDaemonSocketFile;
-
-    struct sockaddr_un addr;
-    addr.sun_family = AF_UNIX;
-    if (socketPath.size() + 1 >= sizeof(addr.sun_path))
-        throw Error("socket path '%1%' is too long", socketPath);
-    strcpy(addr.sun_path, socketPath.c_str());
-
-    if (::connect(conn->fd.get(), (struct sockaddr *) &addr, sizeof(addr)) == -1)
-        throw SysError("cannot connect to daemon at '%1%'", socketPath);
+    nix::connect(conn->fd.get(), path ? *path : settings.nixDaemonSocketFile);
 
     conn->from.fd = conn->fd.get();
     conn->to.fd = conn->fd.get();
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index bc841f425..445875541 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1686,16 +1686,7 @@ AutoCloseFD createUnixDomainSocket(const Path & path, mode_t mode)
 
     closeOnExec(fdSocket.get());
 
-    struct sockaddr_un addr;
-    addr.sun_family = AF_UNIX;
-    if (path.size() + 1 >= sizeof(addr.sun_path))
-        throw Error("socket path '%1%' is too long", path);
-    strcpy(addr.sun_path, path.c_str());
-
-    unlink(path.c_str());
-
-    if (bind(fdSocket.get(), (struct sockaddr *) &addr, sizeof(addr)) == -1)
-        throw SysError("cannot bind to socket '%1%'", path);
+    bind(fdSocket.get(), path);
 
     if (chmod(path.c_str(), mode) == -1)
         throw SysError("changing permissions on '%1%'", path);
@@ -1707,6 +1698,66 @@ AutoCloseFD createUnixDomainSocket(const Path & path, mode_t mode)
 }
 
 
+void bind(int fd, const std::string & path)
+{
+    unlink(path.c_str());
+
+    struct sockaddr_un addr;
+    addr.sun_family = AF_UNIX;
+
+    if (path.size() + 1 >= sizeof(addr.sun_path)) {
+        Pid pid = startProcess([&]() {
+            auto dir = dirOf(path);
+            if (chdir(dir.c_str()) == -1)
+                throw SysError("chdir to '%s' failed", dir);
+            std::string base(baseNameOf(path));
+            if (base.size() + 1 >= sizeof(addr.sun_path))
+                throw Error("socket path '%s' is too long", base);
+            strcpy(addr.sun_path, base.c_str());
+            if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) == -1)
+                throw SysError("cannot bind to socket '%s'", path);
+            _exit(0);
+        });
+        int status = pid.wait();
+        if (status != 0)
+            throw Error("cannot bind to socket '%s'", path);
+    } else {
+        strcpy(addr.sun_path, path.c_str());
+        if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) == -1)
+            throw SysError("cannot bind to socket '%s'", path);
+    }
+}
+
+
+void connect(int fd, const std::string & path)
+{
+    struct sockaddr_un addr;
+    addr.sun_family = AF_UNIX;
+
+    if (path.size() + 1 >= sizeof(addr.sun_path)) {
+        Pid pid = startProcess([&]() {
+            auto dir = dirOf(path);
+            if (chdir(dir.c_str()) == -1)
+                throw SysError("chdir to '%s' failed", dir);
+            std::string base(baseNameOf(path));
+            if (base.size() + 1 >= sizeof(addr.sun_path))
+                throw Error("socket path '%s' is too long", base);
+            strcpy(addr.sun_path, base.c_str());
+            if (connect(fd, (struct sockaddr *) &addr, sizeof(addr)) == -1)
+                throw SysError("cannot connect to socket at '%s'", path);
+            _exit(0);
+        });
+        int status = pid.wait();
+        if (status != 0)
+            throw Error("cannot connect to socket ar '%s'", path);
+    } else {
+        strcpy(addr.sun_path, path.c_str());
+        if (connect(fd, (struct sockaddr *) &addr, sizeof(addr)) == -1)
+            throw SysError("cannot connect to socket at '%s'", path);
+    }
+}
+
+
 string showBytes(uint64_t bytes)
 {
     return fmt("%.2f MiB", bytes / (1024.0 * 1024.0));
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index bee77b53f..6d3e64949 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -259,7 +259,7 @@ void killUser(uid_t uid);
    pid to the caller. */
 struct ProcessOptions
 {
-    string errorPrefix = "error: ";
+    string errorPrefix = "";
     bool dieWithParent = true;
     bool runExitHandlers = false;
     bool allowVfork = true;
@@ -574,6 +574,12 @@ void commonChildInit(Pipe & logPipe);
 /* Create a Unix domain socket in listen mode. */
 AutoCloseFD createUnixDomainSocket(const Path & path, mode_t mode);
 
+/* Bind a Unix domain socket to a path. */
+void bind(int fd, const std::string & path);
+
+/* Connect to a Unix domain socket. */
+void connect(int fd, const std::string & path);
+
 
 // A Rust/Python-like enumerate() iterator adapter.
 // Borrowed from http://reedbeta.com/blog/python-like-enumerate-in-cpp17.

From 3b7f4c7d9d124283cec7f7d42e0eca3e2de64d5a Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 5 Oct 2021 11:04:46 +0200
Subject: [PATCH 055/567] Add FIXME about ptsname

---
 src/libstore/build/local-derivation-goal.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 2ba1b3f59..4cb43bc11 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -711,6 +711,7 @@ void LocalDerivationGoal::startBuilder()
     if (!builderOut.readSide)
         throw SysError("opening pseudoterminal master");
 
+    // FIXME: not thread-safe, use ptsname_r
     std::string slaveName(ptsname(builderOut.readSide.get()));
 
     if (buildUser) {

From b299560872e56fb8aed2d720f9c0b3df9c6265e3 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 25 Aug 2021 13:28:36 +0200
Subject: [PATCH 056/567] Typo

---
 src/libutil/util.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 445875541..feea9f48e 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1749,7 +1749,7 @@ void connect(int fd, const std::string & path)
         });
         int status = pid.wait();
         if (status != 0)
-            throw Error("cannot connect to socket ar '%s'", path);
+            throw Error("cannot connect to socket at '%s'", path);
     } else {
         strcpy(addr.sun_path, path.c_str());
         if (connect(fd, (struct sockaddr *) &addr, sizeof(addr)) == -1)

From e4a5d64a81bcefe8a08015a877492235b079a9e2 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 5 Oct 2021 12:26:04 +0200
Subject: [PATCH 057/567] Show failing PID

---
 src/libutil/util.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index feea9f48e..0b261ca60 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -903,7 +903,7 @@ int Pid::wait()
             return status;
         }
         if (errno != EINTR)
-            throw SysError("cannot get child exit status");
+            throw SysError("cannot get exit status of PID %d", pid);
         checkInterrupt();
     }
 }

From b14bc06955885f661e4af5f04513086d74f2cab7 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 5 Oct 2021 13:23:16 +0200
Subject: [PATCH 058/567] Don't ignore SIGCHLD in createUnixDomainSocket()

---
 src/nix/daemon.cc | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/nix/daemon.cc b/src/nix/daemon.cc
index 2cf2a04c9..6a40a0bd3 100644
--- a/src/nix/daemon.cc
+++ b/src/nix/daemon.cc
@@ -156,9 +156,6 @@ static void daemonLoop()
     if (chdir("/") == -1)
         throw SysError("cannot change current directory");
 
-    //  Get rid of children automatically; don't let them become zombies.
-    setSigChldAction(true);
-
     AutoCloseFD fdSocket;
 
     //  Handle socket-based activation by systemd.
@@ -176,6 +173,9 @@ static void daemonLoop()
         fdSocket = createUnixDomainSocket(settings.nixDaemonSocketFile, 0666);
     }
 
+    //  Get rid of children automatically; don't let them become zombies.
+    setSigChldAction(true);
+
     //  Loop accepting connections.
     while (1) {
 

From 223ab254c29313fff2a9af463baa2f0b68d7d83f Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 5 Oct 2021 14:50:55 +0200
Subject: [PATCH 059/567] Compatibility

---
 flake.nix | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/flake.nix b/flake.nix
index 91341c97d..d3486db4c 100644
--- a/flake.nix
+++ b/flake.nix
@@ -126,8 +126,7 @@
           ''
             mkdir -p $out/nix-support
 
-            # Converts /nix/store/50p3qk8kka9dl6wyq40vydq945k0j3kv-nix-2.4pre20201102_550e11f/bin/nix
-            # To 50p3qk8kka9dl6wyq40vydq945k0j3kv/bin/nix
+            # Converts /nix/store/50p3qk8k...-nix-2.4pre20201102_550e11f/bin/nix to 50p3qk8k.../bin/nix.
             tarballPath() {
               # Remove the store prefix
               local path=''${1#${builtins.storeDir}/}
@@ -153,10 +152,15 @@
             echo "file installer $out/install" >> $out/nix-support/hydra-build-products
           '';
 
-      testNixVersions = pkgs: client: daemon: with commonDeps pkgs; pkgs.stdenv.mkDerivation {
+      testNixVersions = pkgs: client: daemon: with commonDeps pkgs; with pkgs.lib; pkgs.stdenv.mkDerivation {
         NIX_DAEMON_PACKAGE = daemon;
         NIX_CLIENT_PACKAGE = client;
-        name = "nix-tests-${client.version}-against-${daemon.version}";
+        name =
+          "nix-tests"
+          + optionalString
+            (versionAtLeast daemon.version "2.4pre20211005" &&
+             versionAtLeast client.version "2.4pre20211005")
+            "-${client.version}-against-${daemon.version}";
         inherit version;
 
         src = self;

From d12bf8eff0e8c8f4197671f67b5c8117108e3769 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 6 Oct 2021 12:41:23 +0200
Subject: [PATCH 060/567] flake.lock: Update
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Flake lock file changes:

• Updated input 'lowdown-src':
    'github:kristapsdz/lowdown/6bd668af3fd098bdd07a1bedd399564141e275da' (2021-09-24)
  → 'github:kristapsdz/lowdown/d2c2b44ff6c27b936ec27358a2653caaef8f73b8' (2021-10-06)
---
 flake.lock | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/flake.lock b/flake.lock
index 96a69345b..861af1c54 100644
--- a/flake.lock
+++ b/flake.lock
@@ -3,11 +3,11 @@
     "lowdown-src": {
       "flake": false,
       "locked": {
-        "lastModified": 1632468475,
-        "narHash": "sha256-NNOm9CbdA8cuwbvaBHslGbPTiU6bh1Ao+MpEPx4rSGo=",
+        "lastModified": 1633514407,
+        "narHash": "sha256-Dw32tiMjdK9t3ETl5fzGrutQTzh2rufgZV4A/BbxuD4=",
         "owner": "kristapsdz",
         "repo": "lowdown",
-        "rev": "6bd668af3fd098bdd07a1bedd399564141e275da",
+        "rev": "d2c2b44ff6c27b936ec27358a2653caaef8f73b8",
         "type": "github"
       },
       "original": {

From 08aa7daee0b21049cd4aa75f2af14ddf46497cbd Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 6 Oct 2021 13:01:18 +0200
Subject: [PATCH 061/567] Remove links to .md files in help output

Fixes #5337.
---
 doc/manual/generate-manpage.nix | 8 ++++++--
 doc/manual/local.mk             | 2 +-
 src/nix/main.cc                 | 7 +++++--
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/doc/manual/generate-manpage.nix b/doc/manual/generate-manpage.nix
index 4fc9abea1..244cfa0c2 100644
--- a/doc/manual/generate-manpage.nix
+++ b/doc/manual/generate-manpage.nix
@@ -1,4 +1,4 @@
-command:
+{ command, renderLinks ? false }:
 
 with builtins;
 with import ./utils.nix;
@@ -20,7 +20,11 @@ let
            categories = sort (x: y: x.id < y.id) (unique (map (cmd: cmd.category) (attrValues def.commands)));
            listCommands = cmds:
              concatStrings (map (name:
-               "* [`${command} ${name}`](./${appendName filename name}.md) - ${cmds.${name}.description}\n")
+               "* "
+               + (if renderLinks
+                  then "[`${command} ${name}`](./${appendName filename name}.md)"
+                  else "`${command} ${name}`")
+               + " - ${cmds.${name}.description}\n")
                (attrNames cmds));
          in
          "where *subcommand* is one of the following:\n\n"
diff --git a/doc/manual/local.mk b/doc/manual/local.mk
index a8c52f841..e43d9f2fb 100644
--- a/doc/manual/local.mk
+++ b/doc/manual/local.mk
@@ -44,7 +44,7 @@ $(d)/src/SUMMARY.md: $(d)/src/SUMMARY.md.in $(d)/src/command-ref/new-cli
 
 $(d)/src/command-ref/new-cli: $(d)/nix.json $(d)/generate-manpage.nix $(bindir)/nix
 	@rm -rf $@
-	$(trace-gen) $(nix-eval) --write-to $@ --expr 'import doc/manual/generate-manpage.nix (builtins.readFile $<)'
+	$(trace-gen) $(nix-eval) --write-to $@ --expr 'import doc/manual/generate-manpage.nix { command = builtins.readFile $<; renderLinks = true; }'
 
 $(d)/src/command-ref/conf-file.md: $(d)/conf-file.json $(d)/generate-options.nix $(d)/src/command-ref/conf-file-prefix.md $(bindir)/nix
 	@cat doc/manual/src/command-ref/conf-file-prefix.md > $@.tmp
diff --git a/src/nix/main.cc b/src/nix/main.cc
index 8aaf08813..2c3976689 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -187,11 +187,14 @@ static void showHelp(std::vector<std::string> subcommand, MultiCommand & topleve
             , "/"),
         *vUtils);
 
-    auto vJson = state.allocValue();
+    auto vArgs = state.allocValue();
+    state.mkAttrs(*vArgs, 16);
+    auto vJson = state.allocAttr(*vArgs, state.symbols.create("command"));
     mkString(*vJson, toplevel.toJSON().dump());
+    vArgs->attrs->sort();
 
     auto vRes = state.allocValue();
-    state.callFunction(*vGenerateManpage, *vJson, *vRes, noPos);
+    state.callFunction(*vGenerateManpage, *vArgs, *vRes, noPos);
 
     auto attr = vRes->attrs->get(state.symbols.create(mdName + ".md"));
     if (!attr)

From 4d28cf836ac6328b900f023632c8995d000c64cd Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 6 Oct 2021 13:17:39 +0200
Subject: [PATCH 062/567] Disable testing against nixUnstable on macOS

This is failing randomly at the moment which isn't very helpful.
---
 flake.nix | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/flake.nix b/flake.nix
index d3486db4c..2a4149698 100644
--- a/flake.nix
+++ b/flake.nix
@@ -491,7 +491,11 @@
           let pkgs = nixpkgsFor.${system}; in
           pkgs.runCommand "install-tests" {
             againstSelf = testNixVersions pkgs pkgs.nix pkgs.pkgs.nix;
-            againstCurrentUnstable = testNixVersions pkgs pkgs.nix pkgs.nixUnstable;
+            againstCurrentUnstable =
+              # FIXME: temporarily disable this on macOS because of #3605.
+              if system == "x86_64-linux"
+              then testNixVersions pkgs pkgs.nix pkgs.nixUnstable
+              else null;
             # Disabled because the latest stable version doesn't handle
             # `NIX_DAEMON_SOCKET_PATH` which is required for the tests to work
             # againstLatestStable = testNixVersions pkgs pkgs.nix pkgs.nixStable;

From c6718a9d95021476f0cca47b61479e4046090f4e Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 6 Oct 2021 13:54:59 +0200
Subject: [PATCH 063/567] Don't reset the logger in a vfork

9c766a40cbbd3a350a9582d0fd8201e3361a63b2 broke logging from the
daemon, because commonChildInit is called when starting the build hook
in a vfork, so it ends up resetting the parent's logger. So don't
vfork.

It might be best to get rid of vfork altogether, but that may cause
problems, e.g. when we call an external program like git from the
evaluator.
---
 src/libstore/build/local-derivation-goal.cc | 8 ++------
 src/libutil/util.cc                         | 8 ++------
 src/libutil/util.hh                         | 2 +-
 3 files changed, 5 insertions(+), 13 deletions(-)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 4cb43bc11..3fc156108 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -755,7 +755,6 @@ void LocalDerivationGoal::startBuilder()
     result.startTime = time(0);
 
     /* Fork a child to build the package. */
-    ProcessOptions options;
 
 #if __linux__
     if (useChroot) {
@@ -798,8 +797,6 @@ void LocalDerivationGoal::startBuilder()
 
         userNamespaceSync.create();
 
-        options.allowVfork = false;
-
         Path maxUserNamespaces = "/proc/sys/user/max_user_namespaces";
         static bool userNamespacesEnabled =
             pathExists(maxUserNamespaces)
@@ -857,7 +854,7 @@ void LocalDerivationGoal::startBuilder()
             writeFull(builderOut.writeSide.get(),
                 fmt("%d %d\n", usingUserNamespace, child));
             _exit(0);
-        }, options);
+        });
 
         int res = helper.wait();
         if (res != 0 && settings.sandboxFallback) {
@@ -921,10 +918,9 @@ void LocalDerivationGoal::startBuilder()
 #endif
     {
     fallback:
-        options.allowVfork = !buildUser && !drv->isBuiltin();
         pid = startProcess([&]() {
             runChild();
-        }, options);
+        });
     }
 
     /* parent */
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 0b261ca60..563a72c12 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -939,9 +939,6 @@ void killUser(uid_t uid)
        users to which the current process can send signals.  So we
        fork a process, switch to uid, and send a mass kill. */
 
-    ProcessOptions options;
-    options.allowVfork = false;
-
     Pid pid = startProcess([&]() {
 
         if (setuid(uid) == -1)
@@ -964,7 +961,7 @@ void killUser(uid_t uid)
         }
 
         _exit(0);
-    }, options);
+    });
 
     int status = pid.wait();
     if (status != 0)
@@ -1085,8 +1082,7 @@ void runProgram2(const RunOptions & options)
     // vfork implies that the environment of the main process and the fork will
     // be shared (technically this is undefined, but in practice that's the
     // case), so we can't use it if we alter the environment
-    if (options.environment)
-        processOptions.allowVfork = false;
+    processOptions.allowVfork = !options.environment;
 
     /* Fork. */
     Pid pid = startProcess([&]() {
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 6d3e64949..29232453f 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -262,7 +262,7 @@ struct ProcessOptions
     string errorPrefix = "";
     bool dieWithParent = true;
     bool runExitHandlers = false;
-    bool allowVfork = true;
+    bool allowVfork = false;
 };
 
 pid_t startProcess(std::function<void()> fun, const ProcessOptions & options = ProcessOptions());

From 0574c1850a785297b7f28c6f286a23fa3eca14a8 Mon Sep 17 00:00:00 2001
From: happysalada <raphael@megzari.com>
Date: Wed, 6 Oct 2021 21:47:53 +0900
Subject: [PATCH 064/567] docs: add troubleshooting session in remote builds

---
 .../src/advanced-topics/distributed-builds.md      | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/doc/manual/src/advanced-topics/distributed-builds.md b/doc/manual/src/advanced-topics/distributed-builds.md
index 580b36736..23a179a2a 100644
--- a/doc/manual/src/advanced-topics/distributed-builds.md
+++ b/doc/manual/src/advanced-topics/distributed-builds.md
@@ -95,7 +95,7 @@ default, set it to `-`.
     there are multiple machines of the right type, Nix will prefer the
     fastest, taking load into account.
 
-6.  A comma-separated list of *supported features*. If a derivation has
+6.  A comma-separated list of _supported features_. If a derivation has
     the `requiredSystemFeatures` attribute, then Nix will only perform
     the derivation on a machine that has the specified features. For
     instance, the attribute
@@ -107,7 +107,7 @@ default, set it to `-`.
     will cause the build to be performed on a machine that has the `kvm`
     feature.
 
-7.  A comma-separated list of *mandatory features*. A machine will only
+7.  A comma-separated list of _mandatory features_. A machine will only
     be used to build a derivation if all of the machine’s mandatory
     features appear in the derivation’s `requiredSystemFeatures`
     attribute..
@@ -156,3 +156,13 @@ option `builders-use-substitutes` in your local `nix.conf`.
 
 To build only on remote builders and disable building on the local
 machine, you can use the option `--max-jobs 0`.
+
+## Troubleshooting
+
+### ssh
+
+even if the store is reachable with `nix store ping --store your_store_url`, the nix-daemon might not be able to reach it. nix-daemon operates as root so you need to make sure that the machine is reachable via ssh as root user.
+
+- add the `-vvv` flags to show more information on the potential problem.
+- make sure your store is reachable by the root user. `sudo ssh -i "your_ssh_key_path" your_user@your_hostname`
+- make sure your ssh_config is set for the root user to access that server or that your builders configuration contains the ssh_key, user and hostname

From f45b30de2f3e6ce8bfab999b0272e22da06491b3 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 6 Oct 2021 17:12:52 +0200
Subject: [PATCH 065/567] Revert "docs: add troubleshooting session in remote
 builds"

This reverts commit 0574c1850a785297b7f28c6f286a23fa3eca14a8.
---
 .../src/advanced-topics/distributed-builds.md      | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/doc/manual/src/advanced-topics/distributed-builds.md b/doc/manual/src/advanced-topics/distributed-builds.md
index 23a179a2a..580b36736 100644
--- a/doc/manual/src/advanced-topics/distributed-builds.md
+++ b/doc/manual/src/advanced-topics/distributed-builds.md
@@ -95,7 +95,7 @@ default, set it to `-`.
     there are multiple machines of the right type, Nix will prefer the
     fastest, taking load into account.
 
-6.  A comma-separated list of _supported features_. If a derivation has
+6.  A comma-separated list of *supported features*. If a derivation has
     the `requiredSystemFeatures` attribute, then Nix will only perform
     the derivation on a machine that has the specified features. For
     instance, the attribute
@@ -107,7 +107,7 @@ default, set it to `-`.
     will cause the build to be performed on a machine that has the `kvm`
     feature.
 
-7.  A comma-separated list of _mandatory features_. A machine will only
+7.  A comma-separated list of *mandatory features*. A machine will only
     be used to build a derivation if all of the machine’s mandatory
     features appear in the derivation’s `requiredSystemFeatures`
     attribute..
@@ -156,13 +156,3 @@ option `builders-use-substitutes` in your local `nix.conf`.
 
 To build only on remote builders and disable building on the local
 machine, you can use the option `--max-jobs 0`.
-
-## Troubleshooting
-
-### ssh
-
-even if the store is reachable with `nix store ping --store your_store_url`, the nix-daemon might not be able to reach it. nix-daemon operates as root so you need to make sure that the machine is reachable via ssh as root user.
-
-- add the `-vvv` flags to show more information on the potential problem.
-- make sure your store is reachable by the root user. `sudo ssh -i "your_ssh_key_path" your_user@your_hostname`
-- make sure your ssh_config is set for the root user to access that server or that your builders configuration contains the ssh_key, user and hostname

From cae41eebffce5802918ae3ceb7e7c669ea94243c Mon Sep 17 00:00:00 2001
From: Andreas Rammhold <andreas@rammhold.de>
Date: Wed, 6 Oct 2021 17:08:08 +0200
Subject: [PATCH 066/567] libexpr: remove matchAttrs boolean from ExprLambda

The boolean is only used to determine if the formals are set to a
non-null pointer in all our cases. We can get rid of that allocation and
instead just compare the pointer value with NULL. Saving up to
sizeof(bool) + platform specific alignment per ExprLambda instace.
Probably not a lot of memory but perhaps a few kilobyte with nixpkgs?

This also gets rid of a potential issue with dereferencing formals based on
the value of the boolean that didn't have to be aligned with the formals
pointer but was in all our cases.
---
 src/libexpr/eval.cc         | 6 +++---
 src/libexpr/flake/flake.cc  | 2 +-
 src/libexpr/nixexpr.cc      | 4 ++--
 src/libexpr/nixexpr.hh      | 6 +++---
 src/libexpr/parser.y        | 8 ++++----
 src/libexpr/primops.cc      | 2 +-
 src/libexpr/value-to-xml.cc | 2 +-
 src/nix/flake.cc            | 6 +++---
 8 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 800839a8d..2a79090cd 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -1316,13 +1316,13 @@ void EvalState::callFunction(Value & fun, Value & arg, Value & v, const Pos & po
 
     auto size =
         (lambda.arg.empty() ? 0 : 1) +
-        (lambda.matchAttrs ? lambda.formals->formals.size() : 0);
+        (lambda.hasFormals() ? lambda.formals->formals.size() : 0);
     Env & env2(allocEnv(size));
     env2.up = fun.lambda.env;
 
     size_t displ = 0;
 
-    if (!lambda.matchAttrs)
+    if (!lambda.hasFormals())
         env2.values[displ++] = &arg;
 
     else {
@@ -1402,7 +1402,7 @@ void EvalState::autoCallFunction(Bindings & args, Value & fun, Value & res)
         }
     }
 
-    if (!fun.isLambda() || !fun.lambda.fun->matchAttrs) {
+    if (!fun.isLambda() || !fun.lambda.fun->hasFormals()) {
         res = fun;
         return;
     }
diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 1a1fa6938..6a2902dff 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -231,7 +231,7 @@ static Flake getFlake(
     if (auto outputs = vInfo.attrs->get(sOutputs)) {
         expectType(state, nFunction, *outputs->value, *outputs->pos);
 
-        if (outputs->value->isLambda() && outputs->value->lambda.fun->matchAttrs) {
+        if (outputs->value->isLambda() && outputs->value->lambda.fun->hasFormals()) {
             for (auto & formal : outputs->value->lambda.fun->formals->formals) {
                 if (formal.name != state.sSelf)
                     flake.inputs.emplace(formal.name, FlakeInput {
diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc
index 492b819e7..0d0f3e469 100644
--- a/src/libexpr/nixexpr.cc
+++ b/src/libexpr/nixexpr.cc
@@ -124,7 +124,7 @@ void ExprList::show(std::ostream & str) const
 void ExprLambda::show(std::ostream & str) const
 {
     str << "(";
-    if (matchAttrs) {
+    if (hasFormals()) {
         str << "{ ";
         bool first = true;
         for (auto & i : formals->formals) {
@@ -348,7 +348,7 @@ void ExprLambda::bindVars(const StaticEnv & env)
 
     if (!arg.empty()) newEnv.vars[arg] = displ++;
 
-    if (matchAttrs) {
+    if (hasFormals()) {
         for (auto & i : formals->formals)
             newEnv.vars[i.name] = displ++;
 
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index 51a14cd59..851e875bd 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -233,11 +233,10 @@ struct ExprLambda : Expr
     Pos pos;
     Symbol name;
     Symbol arg;
-    bool matchAttrs;
     Formals * formals;
     Expr * body;
-    ExprLambda(const Pos & pos, const Symbol & arg, bool matchAttrs, Formals * formals, Expr * body)
-        : pos(pos), arg(arg), matchAttrs(matchAttrs), formals(formals), body(body)
+    ExprLambda(const Pos & pos, const Symbol & arg, Formals * formals, Expr * body)
+        : pos(pos), arg(arg), formals(formals), body(body)
     {
         if (!arg.empty() && formals && formals->argNames.find(arg) != formals->argNames.end())
             throw ParseError({
@@ -247,6 +246,7 @@ struct ExprLambda : Expr
     };
     void setName(Symbol & name);
     string showNamePos() const;
+    inline bool hasFormals() const { return formals != nullptr; }
     COMMON_METHODS
 };
 
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index e3749783a..8a0a79c96 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -324,13 +324,13 @@ expr: expr_function;
 
 expr_function
   : ID ':' expr_function
-    { $$ = new ExprLambda(CUR_POS, data->symbols.create($1), false, 0, $3); }
+    { $$ = new ExprLambda(CUR_POS, data->symbols.create($1), 0, $3); }
   | '{' formals '}' ':' expr_function
-    { $$ = new ExprLambda(CUR_POS, data->symbols.create(""), true, $2, $5); }
+    { $$ = new ExprLambda(CUR_POS, data->symbols.create(""), $2, $5); }
   | '{' formals '}' '@' ID ':' expr_function
-    { $$ = new ExprLambda(CUR_POS, data->symbols.create($5), true, $2, $7); }
+    { $$ = new ExprLambda(CUR_POS, data->symbols.create($5), $2, $7); }
   | ID '@' '{' formals '}' ':' expr_function
-    { $$ = new ExprLambda(CUR_POS, data->symbols.create($1), true, $4, $7); }
+    { $$ = new ExprLambda(CUR_POS, data->symbols.create($1), $4, $7); }
   | ASSERT expr ';' expr_function
     { $$ = new ExprAssert(CUR_POS, $2, $4); }
   | WITH expr ';' expr_function
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 3bf091438..8d4b817c9 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -2365,7 +2365,7 @@ static void prim_functionArgs(EvalState & state, const Pos & pos, Value * * args
             .errPos = pos
         });
 
-    if (!args[0]->lambda.fun->matchAttrs) {
+    if (!args[0]->lambda.fun->hasFormals()) {
         state.mkAttrs(v, 0);
         return;
     }
diff --git a/src/libexpr/value-to-xml.cc b/src/libexpr/value-to-xml.cc
index 2ddc5f751..b44455f5f 100644
--- a/src/libexpr/value-to-xml.cc
+++ b/src/libexpr/value-to-xml.cc
@@ -135,7 +135,7 @@ static void printValueAsXML(EvalState & state, bool strict, bool location,
             if (location) posToXML(xmlAttrs, v.lambda.fun->pos);
             XMLOpenElement _(doc, "function", xmlAttrs);
 
-            if (v.lambda.fun->matchAttrs) {
+            if (v.lambda.fun->hasFormals()) {
                 XMLAttrs attrs;
                 if (!v.lambda.fun->arg.empty()) attrs["name"] = v.lambda.fun->arg;
                 if (v.lambda.fun->formals->ellipsis) attrs["ellipsis"] = "1";
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 7d7ada707..7e4d23f6e 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -346,10 +346,10 @@ struct CmdFlakeCheck : FlakeCommand
         auto checkOverlay = [&](const std::string & attrPath, Value & v, const Pos & pos) {
             try {
                 state->forceValue(v, pos);
-                if (!v.isLambda() || v.lambda.fun->matchAttrs || std::string(v.lambda.fun->arg) != "final")
+                if (!v.isLambda() || v.lambda.fun->hasFormals() || std::string(v.lambda.fun->arg) != "final")
                     throw Error("overlay does not take an argument named 'final'");
                 auto body = dynamic_cast<ExprLambda *>(v.lambda.fun->body);
-                if (!body || body->matchAttrs || std::string(body->arg) != "prev")
+                if (!body || body->hasFormals() || std::string(body->arg) != "prev")
                     throw Error("overlay does not take an argument named 'prev'");
                 // FIXME: if we have a 'nixpkgs' input, use it to
                 // evaluate the overlay.
@@ -363,7 +363,7 @@ struct CmdFlakeCheck : FlakeCommand
             try {
                 state->forceValue(v, pos);
                 if (v.isLambda()) {
-                    if (!v.lambda.fun->matchAttrs || !v.lambda.fun->formals->ellipsis)
+                    if (!v.lambda.fun->hasFormals() || !v.lambda.fun->formals->ellipsis)
                         throw Error("module must match an open attribute set ('{ config, ... }')");
                 } else if (v.type() == nAttrs) {
                     for (auto & attr : *v.attrs)

From 83d86cc1b007fc9cac5e9fd64a211cf8d78c9365 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 6 Oct 2021 17:29:47 +0200
Subject: [PATCH 067/567] Cleanup

---
 src/libexpr/primops/fetchTree.cc | 50 ++++++++++----------------------
 1 file changed, 15 insertions(+), 35 deletions(-)

diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index 8ab9049a6..d598febbe 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -66,7 +66,7 @@ void emitTreeAttrs(
     v.attrs->sort();
 }
 
-std::string fixURI(std::string uri, EvalState &state, const std::string & defaultScheme = "file")
+std::string fixURI(std::string uri, EvalState & state, const std::string & defaultScheme = "file")
 {
     state.checkURI(uri);
     return uri.find("://") != std::string::npos ? uri : defaultScheme + "://" + uri;
@@ -81,37 +81,17 @@ std::string fixURIForGit(std::string uri, EvalState & state)
         return fixURI(uri, state);
 }
 
-void addURI(
-    EvalState &state,
-    fetchers::Attrs &attrs,
-    Symbol name,
-    std::string v,
-    const std::optional<std::string> type
-) {
-    string n(name);
-    if (n == "url") {
-        if (type == "git") {
-            attrs.emplace("type", "git");
-            attrs.emplace(name, fixURIForGit(v, state));
-        } else {
-            attrs.emplace(name, fixURI(v, state));
-        }
-    } else {
-        attrs.emplace(name, v);
-    }
-}
-
 struct FetchTreeParams {
     bool emptyRevFallback = false;
     bool allowNameArgument = false;
 };
 
 static void fetchTree(
-    EvalState &state,
-    const Pos &pos,
-    Value **args,
-    Value &v,
-    const std::optional<std::string> type,
+    EvalState & state,
+    const Pos & pos,
+    Value * * args,
+    Value & v,
+    const std::optional<std::string> & type,
     const FetchTreeParams & params = FetchTreeParams{}
 ) {
     fetchers::Input input;
@@ -126,14 +106,15 @@ static void fetchTree(
 
         for (auto & attr : *args[0]->attrs) {
             state.forceValue(*attr.value);
-            if (attr.value->type() == nPath || attr.value->type() == nString)
-                addURI(
-                    state,
-                    attrs,
-                    attr.name,
-                    state.coerceToString(*attr.pos, *attr.value, context, false, false),
-                    type
-                );
+            if (attr.value->type() == nPath || attr.value->type() == nString) {
+                auto s = state.coerceToString(*attr.pos, *attr.value, context, false, false);
+                attrs.emplace(attr.name,
+                    attr.name == "url"
+                    ? type == "git"
+                      ? fixURIForGit(s, state)
+                      : fixURI(s, state)
+                    : s);
+            }
             else if (attr.value->type() == nBool)
                 attrs.emplace(attr.name, Explicit<bool>{attr.value->boolean});
             else if (attr.value->type() == nInt)
@@ -159,7 +140,6 @@ static void fetchTree(
                     .errPos = pos
                 });
 
-
         input = fetchers::Input::fromAttrs(std::move(attrs));
     } else {
         auto url = state.coerceToString(pos, *args[0], context, false, false);

From 57a8eb4c018ff69304835b0bbbfd01294df07058 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 6 Oct 2021 17:39:02 +0200
Subject: [PATCH 068/567] fetchTree(): Parse type attribute first

The 'url' attribute depends on whether type == 'git', so this is needed for

  builtins.fetchTree {url = "git@github.com:NixOS/nix.git"; type = "git";}
---
 src/libexpr/primops/fetchTree.cc | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index d598febbe..1a69fe4e4 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -91,7 +91,7 @@ static void fetchTree(
     const Pos & pos,
     Value * * args,
     Value & v,
-    const std::optional<std::string> & type,
+    std::optional<std::string> type,
     const FetchTreeParams & params = FetchTreeParams{}
 ) {
     fetchers::Input input;
@@ -104,7 +104,23 @@ static void fetchTree(
 
         fetchers::Attrs attrs;
 
+        if (auto aType = args[0]->attrs->get(state.sType)) {
+            if (type)
+                throw Error({
+                    .msg = hintfmt("unexpected attribute 'type'"),
+                    .errPos = pos
+                });
+            type = state.forceStringNoCtx(*aType->value, *aType->pos);
+        } else if (!type)
+            throw Error({
+                .msg = hintfmt("attribute 'type' is missing in call to 'fetchTree'"),
+                .errPos = pos
+            });
+
+        attrs.emplace("type", type.value());
+
         for (auto & attr : *args[0]->attrs) {
+            if (attr.name == state.sType) continue;
             state.forceValue(*attr.value);
             if (attr.value->type() == nPath || attr.value->type() == nString) {
                 auto s = state.coerceToString(*attr.pos, *attr.value, context, false, false);
@@ -124,15 +140,6 @@ static void fetchTree(
                     attr.name, showType(*attr.value));
         }
 
-        if (type)
-            attrs.emplace("type", type.value());
-
-        if (!attrs.count("type"))
-            throw Error({
-                .msg = hintfmt("attribute 'type' is missing in call to 'fetchTree'"),
-                .errPos = pos
-            });
-
         if (!params.allowNameArgument)
             if (auto nameIter = attrs.find("name"); nameIter != attrs.end())
                 throw Error({

From 0dc8172458022bf412f6ffa1653802b2522514a6 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 6 Oct 2021 18:08:37 +0200
Subject: [PATCH 069/567] Remove no-op call to realiseContext()

---
 src/libexpr/primops.cc | 13 +------------
 1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index acb5d3cef..fbe39854d 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1891,20 +1891,9 @@ static void addPath(EvalState & state, const Pos & pos, const string & name, con
         dstPath = state.store->printStorePath(*expectedStorePath);
 
     mkString(v, dstPath, {dstPath});
+
     if (state.allowedPaths)
         state.allowedPaths->insert(v.string.s);
-
-    try {
-        state.realiseContext({});
-    } catch (InvalidPathError & e) {
-        throw EvalError({
-            .msg = hintfmt("cannot import '%1%', since path '%2%' is not valid", path, e.path),
-            .errPos = pos
-        });
-    } catch (Error & e) {
-        e.addTrace(pos, "while importing '%s'", path);
-        throw e;
-    }
 }
 
 

From a4a6ef4fb218d87bc7d359dcb467bcec0aad56dc Mon Sep 17 00:00:00 2001
From: ilkecan <ilkecan@protonmail.com>
Date: Wed, 22 Sep 2021 21:58:21 +0300
Subject: [PATCH 070/567] Add a warning to `filterSource`

Warn about the usage of `filterSource` with Nix store paths
---
 src/libexpr/primops.cc | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 8a087a781..15d56bd6d 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -413,7 +413,7 @@ static RegisterPrimOp primop_isNull({
       Return `true` if *e* evaluates to `null`, and `false` otherwise.
 
       > **Warning**
-      > 
+      >
       > This function is *deprecated*; just write `e == null` instead.
     )",
     .fun = prim_isNull,
@@ -1919,6 +1919,19 @@ static RegisterPrimOp primop_filterSource({
     .name = "__filterSource",
     .args = {"e1", "e2"},
     .doc = R"(
+      > **Warning**
+      >
+      > `filterSource` should not be used to filter store paths. Since
+      > `filterSource` uses the name of the input directory while naming
+      > the output directory, doing so will produce a directory name in
+      > the form of `<hash2>-<hash>-<name>`, where `<hash>-<name>` is
+      > the name of the input directory. Since `<hash>` depends on the
+      > unfiltered directory, the name of the output directory will
+      > indirectly depend on files that are filtered out by the
+      > function. This will trigger a rebuild even when a filtered out
+      > file is changed. Use `builtins.path` instead, which allows
+      > specifying the name of the output directory.
+
       This function allows you to copy sources into the Nix store while
       filtering certain files. For instance, suppose that you want to use
       the directory `source-dir` as an input to a Nix expression, e.g.
@@ -2519,7 +2532,7 @@ static RegisterPrimOp primop_tail({
       the argument isn’t a list or is an empty list.
 
       > **Warning**
-      > 
+      >
       > This function should generally be avoided since it's inefficient:
       > unlike Haskell's `tail`, it takes O(n) time, so recursing over a
       > list by repeatedly calling `tail` takes O(n^2) time.

From faeab0d5d58a0bf94fc127f6586a7d35bf0e3f2b Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 6 Oct 2021 18:29:20 +0200
Subject: [PATCH 071/567] Make Mercurial optional for the flakes tests

---
 flake.nix       |  2 +-
 tests/flakes.sh | 54 +++++++++++++++++++++++++------------------------
 2 files changed, 29 insertions(+), 27 deletions(-)

diff --git a/flake.nix b/flake.nix
index 2a4149698..26a83e64c 100644
--- a/flake.nix
+++ b/flake.nix
@@ -78,7 +78,7 @@
 
             # Tests
             buildPackages.git
-            buildPackages.mercurial
+            buildPackages.mercurial # FIXME: remove? only needed for tests
             buildPackages.jq
           ]
           ++ lib.optionals stdenv.hostPlatform.isLinux [(buildPackages.util-linuxMinimal or buildPackages.utillinuxMinimal)];
diff --git a/tests/flakes.sh b/tests/flakes.sh
index 26cdf27b7..c0f429d7c 100644
--- a/tests/flakes.sh
+++ b/tests/flakes.sh
@@ -5,11 +5,6 @@ if [[ -z $(type -p git) ]]; then
     exit 99
 fi
 
-if [[ -z $(type -p hg) ]]; then
-    echo "Mercurial not installed; skipping flake tests"
-    exit 99
-fi
-
 clearStore
 rm -rf $TEST_HOME/.cache $TEST_HOME/.config
 
@@ -579,45 +574,52 @@ nix build -o $TEST_ROOT/result git+file://$flakeGitBare
 
 # Test Mercurial flakes.
 rm -rf $flake5Dir
-hg init $flake5Dir
+mkdir $flake5Dir
 
 cat > $flake5Dir/flake.nix <<EOF
 {
   outputs = { self, flake1 }: {
     defaultPackage.$system = flake1.defaultPackage.$system;
-
     expr = assert builtins.pathExists ./flake.lock; 123;
   };
 }
 EOF
 
-hg add $flake5Dir/flake.nix
-hg commit --config ui.username=foobar@example.org $flake5Dir -m 'Initial commit'
+if [[ -n $(type -p hg) ]]; then
+    hg init $flake5Dir
 
-nix build -o $TEST_ROOT/result hg+file://$flake5Dir
-[[ -e $TEST_ROOT/result/hello ]]
+    hg add $flake5Dir/flake.nix
+    hg commit --config ui.username=foobar@example.org $flake5Dir -m 'Initial commit'
 
-(! nix flake metadata --json hg+file://$flake5Dir | jq -e -r .revision)
+    nix build -o $TEST_ROOT/result hg+file://$flake5Dir
+    [[ -e $TEST_ROOT/result/hello ]]
 
-nix eval hg+file://$flake5Dir#expr
+    (! nix flake metadata --json hg+file://$flake5Dir | jq -e -r .revision)
 
-nix eval hg+file://$flake5Dir#expr
+    nix eval hg+file://$flake5Dir#expr
 
-(! nix eval hg+file://$flake5Dir#expr --no-allow-dirty)
+    nix eval hg+file://$flake5Dir#expr
 
-(! nix flake metadata --json hg+file://$flake5Dir | jq -e -r .revision)
+    (! nix eval hg+file://$flake5Dir#expr --no-allow-dirty)
 
-hg commit --config ui.username=foobar@example.org $flake5Dir -m 'Add lock file'
+    (! nix flake metadata --json hg+file://$flake5Dir | jq -e -r .revision)
 
-nix flake metadata --json hg+file://$flake5Dir --refresh | jq -e -r .revision
-nix flake metadata --json hg+file://$flake5Dir
-[[ $(nix flake metadata --json hg+file://$flake5Dir | jq -e -r .revCount) = 1 ]]
+    hg commit --config ui.username=foobar@example.org $flake5Dir -m 'Add lock file'
 
-nix build -o $TEST_ROOT/result hg+file://$flake5Dir --no-registries --no-allow-dirty
-nix build -o $TEST_ROOT/result hg+file://$flake5Dir --no-use-registries --no-allow-dirty
+    nix flake metadata --json hg+file://$flake5Dir --refresh | jq -e -r .revision
+    nix flake metadata --json hg+file://$flake5Dir
+    [[ $(nix flake metadata --json hg+file://$flake5Dir | jq -e -r .revCount) = 1 ]]
 
-# Test tarball flakes
-tar cfz $TEST_ROOT/flake.tar.gz -C $TEST_ROOT --exclude .hg flake5
+    nix build -o $TEST_ROOT/result hg+file://$flake5Dir --no-registries --no-allow-dirty
+    nix build -o $TEST_ROOT/result hg+file://$flake5Dir --no-use-registries --no-allow-dirty
+fi
+
+# Test path flakes.
+rm -rf $flake5Dir/.hg $flake5Dir/flake.lock
+nix flake lock path://$flake5Dir
+
+# Test tarball flakes.
+tar cfz $TEST_ROOT/flake.tar.gz -C $TEST_ROOT flake5
 
 nix build -o $TEST_ROOT/result file://$TEST_ROOT/flake.tar.gz
 
@@ -632,8 +634,8 @@ nix build -o $TEST_ROOT/result "file://$TEST_ROOT/flake.tar.gz?narHash=sha256-qQ
 
 # Test --override-input.
 git -C $flake3Dir reset --hard
-nix flake lock $flake3Dir --override-input flake2/flake1 flake5 -vvvvv
-[[ $(jq .nodes.flake1_2.locked.url $flake3Dir/flake.lock) =~ flake5 ]]
+nix flake lock $flake3Dir --override-input flake2/flake1 file://$TEST_ROOT/flake.tar.gz -vvvvv
+[[ $(jq .nodes.flake1_2.locked.url $flake3Dir/flake.lock) =~ flake.tar.gz ]]
 
 nix flake lock $flake3Dir --override-input flake2/flake1 flake1
 [[ $(jq -r .nodes.flake1_2.locked.rev $flake3Dir/flake.lock) =~ $hash2 ]]

From dcb3bc614ccfbfccca5d5d8dea2b59bf53eb863a Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 6 Oct 2021 20:53:29 +0200
Subject: [PATCH 072/567] Add a test for builtins.path in a flake

---
 tests/flakes.sh | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/flakes.sh b/tests/flakes.sh
index c0f429d7c..f71c52f11 100644
--- a/tests/flakes.sh
+++ b/tests/flakes.sh
@@ -261,6 +261,7 @@ cat > $flake3Dir/flake.nix <<EOF
       mkDerivation {
         inherit system;
         name = "fnord";
+        dummy = builtins.readFile (builtins.path { name = "source"; path = ./.; filter = path: type: baseNameOf path == "config.nix"; } + "/config.nix");
         buildCommand = ''
           cat \${inputs.nonFlake}/README.md > \$out
         '';

From cfaad7168e7ac72d4b2024df2e093b86b45b70fc Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 7 Oct 2021 12:11:00 +0200
Subject: [PATCH 073/567] Refactoring: Add allowPath() method

---
 src/libexpr/eval.cc                   | 12 +++++++++---
 src/libexpr/eval.hh                   |  5 +++++
 src/libexpr/flake/flake.cc            |  3 +--
 src/libexpr/primops.cc                |  3 +--
 src/libexpr/primops/fetchMercurial.cc |  3 +--
 src/libexpr/primops/fetchTree.cc      |  6 ++----
 src/nix/profile.cc                    |  6 ++----
 7 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 2a79090cd..ce266f522 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -445,12 +445,12 @@ EvalState::EvalState(
                     StorePathSet closure;
                     store->computeFSClosure(store->toStorePath(r.second).first, closure);
                     for (auto & path : closure)
-                        allowedPaths->insert(store->printStorePath(path));
+                        allowPath(store->printStorePath(path));
                 } catch (InvalidPath &) {
-                    allowedPaths->insert(r.second);
+                    allowPath(r.second);
                 }
             } else
-                allowedPaths->insert(r.second);
+                allowPath(r.second);
         }
     }
 
@@ -482,6 +482,12 @@ void EvalState::requireExperimentalFeatureOnEvaluation(
     }
 }
 
+void EvalState::allowPath(const Path & path)
+{
+    if (allowedPaths)
+        allowedPaths->insert(path);
+}
+
 Path EvalState::checkSourcePath(const Path & path_)
 {
     if (!allowedPaths) return path_;
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 9df6150c6..f8c9cf5a7 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -150,6 +150,11 @@ public:
 
     SearchPath getSearchPath() { return searchPath; }
 
+    /* Allow access to a path. */
+    void allowPath(const Path & path);
+
+    /* Check whether access to a path is allowed and throw an error if
+       not. Otherwise return the canonicalised path. */
     Path checkSourcePath(const Path & path);
 
     void checkURI(const std::string & uri);
diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 6a2902dff..abb0fb0be 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -64,8 +64,7 @@ static std::tuple<fetchers::Tree, FlakeRef, FlakeRef> fetchOrSubstituteTree(
     debug("got tree '%s' from '%s'",
         state.store->printStorePath(tree.storePath), lockedRef);
 
-    if (state.allowedPaths)
-        state.allowedPaths->insert(tree.actualPath);
+    state.allowPath(tree.actualPath);
 
     assert(!originalRef.input.getNarHash() || tree.storePath == originalRef.input.computeStorePath(*state.store));
 
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 749afadd0..1b79785ff 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1892,8 +1892,7 @@ static void addPath(EvalState & state, const Pos & pos, const string & name, con
 
     mkString(v, dstPath, {dstPath});
 
-    if (state.allowedPaths)
-        state.allowedPaths->insert(v.string.s);
+    state.allowPath(v.string.s);
 }
 
 
diff --git a/src/libexpr/primops/fetchMercurial.cc b/src/libexpr/primops/fetchMercurial.cc
index 3f88ccb91..b51b155f7 100644
--- a/src/libexpr/primops/fetchMercurial.cc
+++ b/src/libexpr/primops/fetchMercurial.cc
@@ -84,8 +84,7 @@ static void prim_fetchMercurial(EvalState & state, const Pos & pos, Value * * ar
         mkInt(*state.allocAttr(v, state.symbols.create("revCount")), *revCount);
     v.attrs->sort();
 
-    if (state.allowedPaths)
-        state.allowedPaths->insert(tree.actualPath);
+    state.allowPath(tree.actualPath);
 }
 
 static RegisterPrimOp r_fetchMercurial("fetchMercurial", 1, prim_fetchMercurial);
diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index 1a69fe4e4..44f726f9b 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -169,8 +169,7 @@ static void fetchTree(
 
     auto [tree, input2] = input.fetch(state.store);
 
-    if (state.allowedPaths)
-        state.allowedPaths->insert(tree.actualPath);
+    state.allowPath(tree.actualPath);
 
     emitTreeAttrs(state, tree, input2, v, params.emptyRevFallback, false);
 }
@@ -245,8 +244,7 @@ static void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
                 *url, expectedHash->to_string(Base32, true), hash.to_string(Base32, true));
     }
 
-    if (state.allowedPaths)
-        state.allowedPaths->insert(realPath);
+    state.allowPath(realPath);
 
     auto path = state.store->printStorePath(storePath);
     mkString(v, path, PathSet({path}));
diff --git a/src/nix/profile.cc b/src/nix/profile.cc
index c63ed9c88..96a20f673 100644
--- a/src/nix/profile.cc
+++ b/src/nix/profile.cc
@@ -98,10 +98,8 @@ struct ProfileManifest
 
         else if (pathExists(profile + "/manifest.nix")) {
             // FIXME: needed because of pure mode; ugly.
-            if (state.allowedPaths) {
-                state.allowedPaths->insert(state.store->followLinksToStore(profile));
-                state.allowedPaths->insert(state.store->followLinksToStore(profile + "/manifest.nix"));
-            }
+            state.allowPath(state.store->followLinksToStore(profile));
+            state.allowPath(state.store->followLinksToStore(profile + "/manifest.nix"));
 
             auto drvInfos = queryInstalled(state, state.store->followLinksToStore(profile));
 

From 972405edf5ff0d90185fb4021993c4a942787578 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 7 Oct 2021 12:15:22 +0200
Subject: [PATCH 074/567] Allow access to path copied to the store

Fixes https://github.com/NixOS/nix/pull/5163#issuecomment-931733912.
---
 src/libexpr/eval.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index ce266f522..2483132f6 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -1897,6 +1897,7 @@ string EvalState::copyPathToStore(PathSet & context, const Path & path)
         dstPath = store->printStorePath(p);
         srcToStore.insert_or_assign(path, std::move(p));
         printMsg(lvlChatty, "copied source '%1%' -> '%2%'", path, dstPath);
+        allowPath(dstPath);
     }
 
     context.insert(dstPath);

From 7c5056878818e67f5b64c903c43d06847acfe315 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 7 Oct 2021 13:15:01 +0200
Subject: [PATCH 075/567] Remove unnecessary call to queryMissing()

Worker::run() already does this.
---
 src/libexpr/primops.cc | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 1b79785ff..77b27799f 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -56,13 +56,9 @@ void EvalState::realiseContext(const PathSet & context)
             "cannot build '%1%' during evaluation because the option 'allow-import-from-derivation' is disabled",
             store->printStorePath(drvs.begin()->drvPath));
 
-    /* For performance, prefetch all substitute info. */
-    StorePathSet willBuild, willSubstitute, unknown;
-    uint64_t downloadSize, narSize;
+    /* Build/substitute the context. */
     std::vector<DerivedPath> buildReqs;
     for (auto & d : drvs) buildReqs.emplace_back(DerivedPath { d });
-    store->queryMissing(buildReqs, willBuild, willSubstitute, unknown, downloadSize, narSize);
-
     store->buildPaths(buildReqs);
 
     /* Add the output of this derivations to the allowed

From 66c4b20d8bdfb9434329439a7314942b25c7ba50 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 7 Oct 2021 13:34:04 +0200
Subject: [PATCH 076/567] Typo

---
 src/libstore/build/worker.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libstore/build/worker.cc b/src/libstore/build/worker.cc
index a7a6b92a6..55afb5cca 100644
--- a/src/libstore/build/worker.cc
+++ b/src/libstore/build/worker.cc
@@ -239,7 +239,7 @@ void Worker::run(const Goals & _topGoals)
         }
     }
 
-    /* Call queryMissing() efficiently query substitutes. */
+    /* Call queryMissing() to efficiently query substitutes. */
     StorePathSet willBuild, willSubstitute, unknown;
     uint64_t downloadSize, narSize;
     store.queryMissing(topPaths, willBuild, willSubstitute, unknown, downloadSize, narSize);

From 4806f2f6b0fd2cae401b89fe19d8c528ffd88b5f Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 7 Oct 2021 13:43:17 +0200
Subject: [PATCH 077/567] Allow builtins.{path,filterSource} on paths with a
 context

We now build the context (so this has the side-effect of making
builtins.{path,filterSource} work on derivations outputs, if IFD is
enabled) and then check that the path has no references (which is what
we really care about).
---
 src/libexpr/primops.cc | 62 ++++++++++++++++++++++++++++--------------
 tests/flakes.sh        |  1 +
 2 files changed, 43 insertions(+), 20 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 77b27799f..67d670fb4 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1843,12 +1843,43 @@ static RegisterPrimOp primop_toFile({
     .fun = prim_toFile,
 });
 
-static void addPath(EvalState & state, const Pos & pos, const string & name, const Path & path_,
-    Value * filterFun, FileIngestionMethod method, const std::optional<Hash> expectedHash, Value & v)
+static void addPath(
+    EvalState & state,
+    const Pos & pos,
+    const string & name,
+    const Path & path_,
+    Value * filterFun,
+    FileIngestionMethod method,
+    const std::optional<Hash> expectedHash,
+    Value & v,
+    const PathSet & context)
 {
-    const auto path = evalSettings.pureEval && expectedHash ?
-        path_ :
-        state.checkSourcePath(path_);
+    try {
+        // FIXME: handle CA derivation outputs (where path_ needs to
+        // be rewritten to the actual output).
+        state.realiseContext(context);
+    } catch (InvalidPathError & e) {
+        throw EvalError({
+            .msg = hintfmt("cannot add path '%s', since path '%s' is not valid", path_, e.path),
+            .errPos = pos
+        });
+    } catch (Error & e) {
+        e.addTrace(pos, "while adding path '%s'", path_);
+        throw;
+    }
+
+    const auto path = evalSettings.pureEval && expectedHash
+        ? path_
+        : state.checkSourcePath(path_);
+
+    if (state.store->isInStore(path)) {
+        auto storePath = state.store->toStorePath(path).first;
+        auto info = state.store->queryPathInfo(storePath);
+        if (!info->references.empty())
+            throw EvalError("store path '%s' is not allowed to have references",
+                state.store->printStorePath(storePath));
+    }
+
     PathFilter filter = filterFun ? ([&](const Path & path) {
         auto st = lstat(path);
 
@@ -1876,6 +1907,7 @@ static void addPath(EvalState & state, const Pos & pos, const string & name, con
     std::optional<StorePath> expectedStorePath;
     if (expectedHash)
         expectedStorePath = state.store->makeFixedOutputPath(method, *expectedHash, name);
+
     Path dstPath;
     if (!expectedHash || !state.store->isValidPath(*expectedStorePath)) {
         dstPath = state.store->printStorePath(settings.readOnlyMode
@@ -1896,11 +1928,6 @@ static void prim_filterSource(EvalState & state, const Pos & pos, Value * * args
 {
     PathSet context;
     Path path = state.coerceToPath(pos, *args[1], context);
-    if (!context.empty())
-        throw EvalError({
-            .msg = hintfmt("string '%1%' cannot refer to other paths", path),
-            .errPos = pos
-        });
 
     state.forceValue(*args[0], pos);
     if (args[0]->type() != nFunction)
@@ -1911,7 +1938,7 @@ static void prim_filterSource(EvalState & state, const Pos & pos, Value * * args
             .errPos = pos
         });
 
-    addPath(state, pos, std::string(baseNameOf(path)), path, args[0], FileIngestionMethod::Recursive, std::nullopt, v);
+    addPath(state, pos, std::string(baseNameOf(path)), path, args[0], FileIngestionMethod::Recursive, std::nullopt, v, context);
 }
 
 static RegisterPrimOp primop_filterSource({
@@ -1977,18 +2004,13 @@ static void prim_path(EvalState & state, const Pos & pos, Value * * args, Value
     Value * filterFun = nullptr;
     auto method = FileIngestionMethod::Recursive;
     std::optional<Hash> expectedHash;
+    PathSet context;
 
     for (auto & attr : *args[0]->attrs) {
         const string & n(attr.name);
-        if (n == "path") {
-            PathSet context;
+        if (n == "path")
             path = state.coerceToPath(*attr.pos, *attr.value, context);
-            if (!context.empty())
-                throw EvalError({
-                    .msg = hintfmt("string '%1%' cannot refer to other paths", path),
-                    .errPos = *attr.pos
-                });
-        } else if (attr.name == state.sName)
+        else if (attr.name == state.sName)
             name = state.forceStringNoCtx(*attr.value, *attr.pos);
         else if (n == "filter") {
             state.forceValue(*attr.value, pos);
@@ -2011,7 +2033,7 @@ static void prim_path(EvalState & state, const Pos & pos, Value * * args, Value
     if (name.empty())
         name = baseNameOf(path);
 
-    addPath(state, pos, name, path, filterFun, method, expectedHash, v);
+    addPath(state, pos, name, path, filterFun, method, expectedHash, v, context);
 }
 
 static RegisterPrimOp primop_path({
diff --git a/tests/flakes.sh b/tests/flakes.sh
index f71c52f11..57d1b9aad 100644
--- a/tests/flakes.sh
+++ b/tests/flakes.sh
@@ -262,6 +262,7 @@ cat > $flake3Dir/flake.nix <<EOF
         inherit system;
         name = "fnord";
         dummy = builtins.readFile (builtins.path { name = "source"; path = ./.; filter = path: type: baseNameOf path == "config.nix"; } + "/config.nix");
+        dummy2 = builtins.readFile (builtins.path { name = "source"; path = inputs.flake1; filter = path: type: baseNameOf path == "simple.nix"; } + "/simple.nix");
         buildCommand = ''
           cat \${inputs.nonFlake}/README.md > \$out
         '';

From c4dcf3cf2578cb4d1a7105b32e27c5c6dd2ad9ba Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 7 Oct 2021 13:47:15 +0200
Subject: [PATCH 078/567] Add a trace to all errors in addPath()

---
 src/libexpr/primops.cc | 120 ++++++++++++++++++++---------------------
 1 file changed, 58 insertions(+), 62 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 67d670fb4..94e196d62 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1847,7 +1847,7 @@ static void addPath(
     EvalState & state,
     const Pos & pos,
     const string & name,
-    const Path & path_,
+    Path path,
     Value * filterFun,
     FileIngestionMethod method,
     const std::optional<Hash> expectedHash,
@@ -1855,72 +1855,68 @@ static void addPath(
     const PathSet & context)
 {
     try {
-        // FIXME: handle CA derivation outputs (where path_ needs to
+        // FIXME: handle CA derivation outputs (where path needs to
         // be rewritten to the actual output).
         state.realiseContext(context);
-    } catch (InvalidPathError & e) {
-        throw EvalError({
-            .msg = hintfmt("cannot add path '%s', since path '%s' is not valid", path_, e.path),
-            .errPos = pos
-        });
+
+        path = evalSettings.pureEval && expectedHash
+            ? path
+            : state.checkSourcePath(path);
+
+        if (state.store->isInStore(path)) {
+            auto storePath = state.store->toStorePath(path).first;
+            auto info = state.store->queryPathInfo(storePath);
+            if (!info->references.empty())
+                throw EvalError("store path '%s' is not allowed to have references",
+                    state.store->printStorePath(storePath));
+        }
+
+        PathFilter filter = filterFun ? ([&](const Path & path) {
+            auto st = lstat(path);
+
+            /* Call the filter function.  The first argument is the path,
+               the second is a string indicating the type of the file. */
+            Value arg1;
+            mkString(arg1, path);
+
+            Value fun2;
+            state.callFunction(*filterFun, arg1, fun2, noPos);
+
+            Value arg2;
+            mkString(arg2,
+                S_ISREG(st.st_mode) ? "regular" :
+                S_ISDIR(st.st_mode) ? "directory" :
+                S_ISLNK(st.st_mode) ? "symlink" :
+                "unknown" /* not supported, will fail! */);
+
+            Value res;
+            state.callFunction(fun2, arg2, res, noPos);
+
+            return state.forceBool(res, pos);
+        }) : defaultPathFilter;
+
+        std::optional<StorePath> expectedStorePath;
+        if (expectedHash)
+            expectedStorePath = state.store->makeFixedOutputPath(method, *expectedHash, name);
+
+        Path dstPath;
+        if (!expectedHash || !state.store->isValidPath(*expectedStorePath)) {
+            dstPath = state.store->printStorePath(settings.readOnlyMode
+                ? state.store->computeStorePathForPath(name, path, method, htSHA256, filter).first
+                : state.store->addToStore(name, path, method, htSHA256, filter, state.repair));
+            if (expectedHash && expectedStorePath != state.store->parseStorePath(dstPath))
+                throw Error("store path mismatch in (possibly filtered) path added from '%s'", path);
+        } else
+            dstPath = state.store->printStorePath(*expectedStorePath);
+
+        mkString(v, dstPath, {dstPath});
+
+        state.allowPath(v.string.s);
+
     } catch (Error & e) {
-        e.addTrace(pos, "while adding path '%s'", path_);
+        e.addTrace(pos, "while adding path '%s'", path);
         throw;
     }
-
-    const auto path = evalSettings.pureEval && expectedHash
-        ? path_
-        : state.checkSourcePath(path_);
-
-    if (state.store->isInStore(path)) {
-        auto storePath = state.store->toStorePath(path).first;
-        auto info = state.store->queryPathInfo(storePath);
-        if (!info->references.empty())
-            throw EvalError("store path '%s' is not allowed to have references",
-                state.store->printStorePath(storePath));
-    }
-
-    PathFilter filter = filterFun ? ([&](const Path & path) {
-        auto st = lstat(path);
-
-        /* Call the filter function.  The first argument is the path,
-           the second is a string indicating the type of the file. */
-        Value arg1;
-        mkString(arg1, path);
-
-        Value fun2;
-        state.callFunction(*filterFun, arg1, fun2, noPos);
-
-        Value arg2;
-        mkString(arg2,
-            S_ISREG(st.st_mode) ? "regular" :
-            S_ISDIR(st.st_mode) ? "directory" :
-            S_ISLNK(st.st_mode) ? "symlink" :
-            "unknown" /* not supported, will fail! */);
-
-        Value res;
-        state.callFunction(fun2, arg2, res, noPos);
-
-        return state.forceBool(res, pos);
-    }) : defaultPathFilter;
-
-    std::optional<StorePath> expectedStorePath;
-    if (expectedHash)
-        expectedStorePath = state.store->makeFixedOutputPath(method, *expectedHash, name);
-
-    Path dstPath;
-    if (!expectedHash || !state.store->isValidPath(*expectedStorePath)) {
-        dstPath = state.store->printStorePath(settings.readOnlyMode
-            ? state.store->computeStorePathForPath(name, path, method, htSHA256, filter).first
-            : state.store->addToStore(name, path, method, htSHA256, filter, state.repair));
-        if (expectedHash && expectedStorePath != state.store->parseStorePath(dstPath))
-            throw Error("store path mismatch in (possibly filtered) path added from '%s'", path);
-    } else
-        dstPath = state.store->printStorePath(*expectedStorePath);
-
-    mkString(v, dstPath, {dstPath});
-
-    state.allowPath(v.string.s);
 }
 
 

From d39692e6b3275c6f54c066554d2915e4b857bc3e Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 7 Oct 2021 14:07:51 +0200
Subject: [PATCH 079/567] Make builtins.{path,filterSource} work with chroot
 stores

---
 src/libexpr/eval.cc                   | 10 ++++++++--
 src/libexpr/eval.hh                   |  4 ++++
 src/libexpr/flake/flake.cc            |  2 +-
 src/libexpr/primops.cc                | 13 +++++++------
 src/libexpr/primops/fetchMercurial.cc |  2 +-
 src/libexpr/primops/fetchTree.cc      |  8 +++-----
 6 files changed, 24 insertions(+), 15 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 2483132f6..3ae05a8d8 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -445,7 +445,7 @@ EvalState::EvalState(
                     StorePathSet closure;
                     store->computeFSClosure(store->toStorePath(r.second).first, closure);
                     for (auto & path : closure)
-                        allowPath(store->printStorePath(path));
+                        allowPath(path);
                 } catch (InvalidPath &) {
                     allowPath(r.second);
                 }
@@ -488,6 +488,12 @@ void EvalState::allowPath(const Path & path)
         allowedPaths->insert(path);
 }
 
+void EvalState::allowPath(const StorePath & storePath)
+{
+    if (allowedPaths)
+        allowedPaths->insert(store->toRealPath(storePath));
+}
+
 Path EvalState::checkSourcePath(const Path & path_)
 {
     if (!allowedPaths) return path_;
@@ -1895,9 +1901,9 @@ string EvalState::copyPathToStore(PathSet & context, const Path & path)
             ? store->computeStorePathForPath(std::string(baseNameOf(path)), checkSourcePath(path)).first
             : store->addToStore(std::string(baseNameOf(path)), checkSourcePath(path), FileIngestionMethod::Recursive, htSHA256, defaultPathFilter, repair);
         dstPath = store->printStorePath(p);
+        allowPath(p);
         srcToStore.insert_or_assign(path, std::move(p));
         printMsg(lvlChatty, "copied source '%1%' -> '%2%'", path, dstPath);
-        allowPath(dstPath);
     }
 
     context.insert(dstPath);
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index f8c9cf5a7..7cc16ef0a 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -153,6 +153,10 @@ public:
     /* Allow access to a path. */
     void allowPath(const Path & path);
 
+    /* Allow access to a store path. Note that this gets remapped to
+       the real store path if `store` is a chroot store. */
+    void allowPath(const StorePath & storePath);
+
     /* Check whether access to a path is allowed and throw an error if
        not. Otherwise return the canonicalised path. */
     Path checkSourcePath(const Path & path);
diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index abb0fb0be..43bfc3644 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -64,7 +64,7 @@ static std::tuple<fetchers::Tree, FlakeRef, FlakeRef> fetchOrSubstituteTree(
     debug("got tree '%s' from '%s'",
         state.store->printStorePath(tree.storePath), lockedRef);
 
-    state.allowPath(tree.actualPath);
+    state.allowPath(tree.storePath);
 
     assert(!originalRef.input.getNarHash() || tree.storePath == originalRef.input.computeStorePath(*state.store));
 
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 94e196d62..f27331534 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1859,18 +1859,19 @@ static void addPath(
         // be rewritten to the actual output).
         state.realiseContext(context);
 
-        path = evalSettings.pureEval && expectedHash
-            ? path
-            : state.checkSourcePath(path);
-
         if (state.store->isInStore(path)) {
-            auto storePath = state.store->toStorePath(path).first;
+            auto [storePath, subPath] = state.store->toStorePath(path);
             auto info = state.store->queryPathInfo(storePath);
             if (!info->references.empty())
                 throw EvalError("store path '%s' is not allowed to have references",
                     state.store->printStorePath(storePath));
+            path = state.store->toRealPath(storePath) + subPath;
         }
 
+        path = evalSettings.pureEval && expectedHash
+            ? path
+            : state.checkSourcePath(path);
+
         PathFilter filter = filterFun ? ([&](const Path & path) {
             auto st = lstat(path);
 
@@ -1911,7 +1912,7 @@ static void addPath(
 
         mkString(v, dstPath, {dstPath});
 
-        state.allowPath(v.string.s);
+        state.allowPath(dstPath);
 
     } catch (Error & e) {
         e.addTrace(pos, "while adding path '%s'", path);
diff --git a/src/libexpr/primops/fetchMercurial.cc b/src/libexpr/primops/fetchMercurial.cc
index b51b155f7..1cd481243 100644
--- a/src/libexpr/primops/fetchMercurial.cc
+++ b/src/libexpr/primops/fetchMercurial.cc
@@ -84,7 +84,7 @@ static void prim_fetchMercurial(EvalState & state, const Pos & pos, Value * * ar
         mkInt(*state.allocAttr(v, state.symbols.create("revCount")), *revCount);
     v.attrs->sort();
 
-    state.allowPath(tree.actualPath);
+    state.allowPath(tree.storePath);
 }
 
 static RegisterPrimOp r_fetchMercurial("fetchMercurial", 1, prim_fetchMercurial);
diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index 44f726f9b..f570f19ae 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -169,7 +169,7 @@ static void fetchTree(
 
     auto [tree, input2] = input.fetch(state.store);
 
-    state.allowPath(tree.actualPath);
+    state.allowPath(tree.storePath);
 
     emitTreeAttrs(state, tree, input2, v, params.emptyRevFallback, false);
 }
@@ -233,18 +233,16 @@ static void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
         ? fetchers::downloadTarball(state.store, *url, name, (bool) expectedHash).first.storePath
         : fetchers::downloadFile(state.store, *url, name, (bool) expectedHash).storePath;
 
-    auto realPath = state.store->toRealPath(storePath);
-
     if (expectedHash) {
         auto hash = unpack
             ? state.store->queryPathInfo(storePath)->narHash
-            : hashFile(htSHA256, realPath);
+            : hashFile(htSHA256, state.store->toRealPath(storePath));
         if (hash != *expectedHash)
             throw Error((unsigned int) 102, "hash mismatch in file downloaded from '%s':\n  specified: %s\n  got:       %s",
                 *url, expectedHash->to_string(Base32, true), hash.to_string(Base32, true));
     }
 
-    state.allowPath(realPath);
+    state.allowPath(storePath);
 
     auto path = state.store->printStorePath(storePath);
     mkString(v, path, PathSet({path}));

From 158fa6870fef4b20fa55e872bf1c1f2cad408c65 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 7 Oct 2021 17:39:30 +0200
Subject: [PATCH 080/567] Bump version to 2.5

---
 .version | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.version b/.version
index 7208c2182..68151b2e1 100644
--- a/.version
+++ b/.version
@@ -1 +1 @@
-2.4
\ No newline at end of file
+2.5
\ No newline at end of file

From b976b34a5b05ba303904cc7b8e0a2579bdb52807 Mon Sep 17 00:00:00 2001
From: Tom Bereknyei <tomberek@gmail.com>
Date: Thu, 7 Oct 2021 11:54:58 -0400
Subject: [PATCH 081/567] Revert "mk: prefert inplace library paths to system
 ones"

This reverts commit 4993174be59adc688efad49f2f9205688bd2ee26.

buildStatic.x86_64-linux and buildStatic.aarch64-linux were broken, see https://hydra.nixos.org/build/151755012
---
 mk/libraries.mk | 4 ++--
 mk/programs.mk  | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/mk/libraries.mk b/mk/libraries.mk
index fd4d4ee72..07bd54dab 100644
--- a/mk/libraries.mk
+++ b/mk/libraries.mk
@@ -91,7 +91,7 @@ define build-library
     $(1)_PATH := $$(_d)/$$($(1)_NAME).$(SO_EXT)
 
     $$($(1)_PATH): $$($(1)_OBJS) $$(_libs) | $$(_d)/
-	$$(trace-ld) $(CXX) -o $$(abspath $$@) -shared $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE)) $$($(1)_LDFLAGS_UNINSTALLED) $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$($(1)_LDFLAGS_PROPAGATED)
+	$$(trace-ld) $(CXX) -o $$(abspath $$@) -shared $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$($(1)_LDFLAGS_PROPAGATED) $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE)) $$($(1)_LDFLAGS_UNINSTALLED)
 
     ifndef HOST_DARWIN
       $(1)_LDFLAGS_USE += -Wl,-rpath,$$(abspath $$(_d))
@@ -105,7 +105,7 @@ define build-library
     $$(eval $$(call create-dir, $$($(1)_INSTALL_DIR)))
 
     $$($(1)_INSTALL_PATH): $$($(1)_OBJS) $$(_libs_final) | $(DESTDIR)$$($(1)_INSTALL_DIR)/
-	$$(trace-ld) $(CXX) -o $$@ -shared $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE_INSTALLED)) $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$($(1)_LDFLAGS_PROPAGATED)
+	$$(trace-ld) $(CXX) -o $$@ -shared $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$($(1)_LDFLAGS_PROPAGATED) $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE_INSTALLED))
 
     $(1)_LDFLAGS_USE_INSTALLED += -L$$(DESTDIR)$$($(1)_INSTALL_DIR) -l$$(patsubst lib%,%,$$(strip $$($(1)_NAME)))
     ifndef HOST_DARWIN
diff --git a/mk/programs.mk b/mk/programs.mk
index 70b09f0dd..d0cf5baf0 100644
--- a/mk/programs.mk
+++ b/mk/programs.mk
@@ -32,7 +32,7 @@ define build-program
   $$(eval $$(call create-dir, $$(_d)))
 
   $$($(1)_PATH): $$($(1)_OBJS) $$(_libs) | $$(_d)/
-	$$(trace-ld) $(CXX) -o $$@ $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE)) $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS)
+	$$(trace-ld) $(CXX) -o $$@ $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE))
 
   $(1)_INSTALL_DIR ?= $$(bindir)
 
@@ -49,7 +49,7 @@ define build-program
       _libs_final := $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_INSTALL_PATH))
 
       $(DESTDIR)$$($(1)_INSTALL_PATH): $$($(1)_OBJS) $$(_libs_final) | $(DESTDIR)$$($(1)_INSTALL_DIR)/
-	$$(trace-ld) $(CXX) -o $$@ $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE_INSTALLED)) $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS)
+	$$(trace-ld) $(CXX) -o $$@ $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE_INSTALLED))
 
     else
 

From e33f74495b19a9134e1f7fd5b69d914ffc8a183e Mon Sep 17 00:00:00 2001
From: Arthur Gautier <baloo@superbaloo.net>
Date: Thu, 7 Oct 2021 16:58:15 +0000
Subject: [PATCH 082/567] Adds a test for nss preload mechanism

This tests for the fix implemented in #5224

Signed-off-by: Arthur Gautier <baloo@superbaloo.net>
---
 flake.nix             |   6 +++
 tests/nss-preload.nix | 123 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 129 insertions(+)
 create mode 100644 tests/nss-preload.nix

diff --git a/flake.nix b/flake.nix
index 26a83e64c..2d0c44889 100644
--- a/flake.nix
+++ b/flake.nix
@@ -444,6 +444,12 @@
           inherit (self) overlay;
         };
 
+        tests.nssPreload = (import ./tests/nss-preload.nix rec {
+          system = "x86_64-linux";
+          inherit nixpkgs;
+          inherit (self) overlay;
+        });
+
         tests.githubFlakes = (import ./tests/github-flakes.nix rec {
           system = "x86_64-linux";
           inherit nixpkgs;
diff --git a/tests/nss-preload.nix b/tests/nss-preload.nix
new file mode 100644
index 000000000..2610d2b30
--- /dev/null
+++ b/tests/nss-preload.nix
@@ -0,0 +1,123 @@
+{ nixpkgs, system, overlay }:
+
+with import (nixpkgs + "/nixos/lib/testing-python.nix") {
+  inherit system;
+  extraConfigurations = [ { nixpkgs.overlays = [ overlay ]; } ];
+};
+
+makeTest (
+
+rec {
+  name = "nss-preload";
+
+  nodes = {
+    http_dns = { lib, pkgs, config, ... }: {
+      networking.firewall.enable = false;
+      networking.interfaces.eth1.ipv6.addresses = lib.mkForce [
+        { address = "fd21::1"; prefixLength = 64; }
+      ];
+      networking.interfaces.eth1.ipv4.addresses = lib.mkForce [
+        { address = "192.168.0.1"; prefixLength = 24; }
+      ];
+
+      services.unbound = {
+        enable = true;
+        enableRootTrustAnchor = false;
+        settings = {
+          server = {
+            interface = [ "192.168.0.1" "fd21::1" "::1" "127.0.0.1" ];
+            access-control = [ "192.168.0.0/24 allow" "fd21::/64 allow" "::1 allow" "127.0.0.0/8 allow" ];
+            local-data = [
+              ''"example.com. IN A 192.168.0.1"''
+              ''"example.com. IN AAAA fd21::1"''
+              ''"tarballs.nixos.org. IN A 192.168.0.1"''
+              ''"tarballs.nixos.org. IN AAAA fd21::1"''
+            ];
+          };
+        };
+      };
+
+      services.nginx = {
+        enable = true;
+        virtualHosts."example.com" = {
+          root = pkgs.runCommand "testdir" {} ''
+            mkdir "$out"
+            echo hello world > "$out/index.html"
+          '';
+        };
+      };
+    };
+
+    # client consumes a remote resolver
+    client = { lib, nodes, pkgs, ... }: {
+      networking.useDHCP = false;
+      networking.nameservers = [
+        (lib.head nodes.http_dns.config.networking.interfaces.eth1.ipv6.addresses).address
+        (lib.head nodes.http_dns.config.networking.interfaces.eth1.ipv4.addresses).address
+      ];
+      networking.interfaces.eth1.ipv6.addresses = [
+        { address = "fd21::10"; prefixLength = 64; }
+      ];
+      networking.interfaces.eth1.ipv4.addresses = [
+        { address = "192.168.0.10"; prefixLength = 24; }
+      ];
+
+      nix.sandboxPaths = lib.mkForce [];
+      nix.binaryCaches = lib.mkForce [];
+      nix.useSandbox = lib.mkForce true;
+    };
+  };
+
+  nix-fetch = pkgs.writeText "fetch.nix" ''
+    derivation {
+        # This derivation is an copy from what is available over at
+        # nix.git:corepkgs/fetchurl.nix
+        builder = "builtin:fetchurl";
+
+        # We're going to fetch data from the http_dns instance created before
+        # we expect the content to be the same as the content available there.
+        # ```
+        # $ nix-hash --type sha256 --to-base32 $(echo "hello world" | sha256sum | cut -d " " -f 1)
+        # 0ix4jahrkll5zg01wandq78jw3ab30q4nscph67rniqg5x7r0j59
+        # ```
+        outputHash = "0ix4jahrkll5zg01wandq78jw3ab30q4nscph67rniqg5x7r0j59";
+        outputHashAlgo = "sha256";
+        outputHashMode = "flat";
+
+        name = "example.com";
+        url = "http://example.com";
+
+        unpack = false;
+        executable = false;
+
+        system = "builtin";
+
+        preferLocalBuild = true;
+
+        impureEnvVars = [
+            "http_proxy" "https_proxy" "ftp_proxy" "all_proxy" "no_proxy"
+        ];
+
+        urls = [ "http://example.com" ];
+      }
+  '';
+
+  testScript = { nodes, ... }: ''
+    http_dns.wait_for_unit("nginx")
+    http_dns.wait_for_open_port(80)
+    http_dns.wait_for_unit("unbound")
+    http_dns.wait_for_open_port(53)
+
+    client.start()
+    client.wait_for_unit('multi-user.target')
+
+    with subtest("can fetch data from a remote server outside sandbox"):
+        client.succeed("nix --version >&2")
+        client.succeed("curl -vvv http://example.com/index.html >&2")
+
+    with subtest("nix-build can lookup dns and fetch data"):
+        client.succeed("""
+          nix-build ${nix-fetch} >&2
+          """)
+  '';
+})

From 844dd901a7debe8b03ec93a7f717b6c4038dc572 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 7 Oct 2021 20:09:03 +0200
Subject: [PATCH 083/567] Start 2.5 release notes

---
 doc/manual/src/release-notes/rl-2.5.md | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 doc/manual/src/release-notes/rl-2.5.md

diff --git a/doc/manual/src/release-notes/rl-2.5.md b/doc/manual/src/release-notes/rl-2.5.md
new file mode 100644
index 000000000..ede614ca3
--- /dev/null
+++ b/doc/manual/src/release-notes/rl-2.5.md
@@ -0,0 +1,2 @@
+# Release 2.5 (2021-XX-XX)
+

From 0872659002d17dc7941b94075b3b9a54169d173f Mon Sep 17 00:00:00 2001
From: Maximilian Bosch <maximilian@mbosch.me>
Date: Thu, 7 Oct 2021 23:58:02 +0200
Subject: [PATCH 084/567] nix repl: properly deal with interruptions

When I stop a download with Ctrl-C in a `nix repl` of a flake, the REPL
refuses to do any other downloads:

    nix-repl> builtins.getFlake "nix-serve"
    [0.0 MiB DL] downloading 'https://api.github.com/repos/edolstra/nix-serve/tarball/e9828a9e01a14297d15ca41 error: download of 'https://api.github.com/repos/edolstra/nix-serve/tarball/e9828a9e01a14297d15ca416e5a9415d4972b0f0' was interrupted
    [0.0 MiB DL]
    nix-repl> builtins.getFlake "nix-serve"
    error: interrupted by the user
    [0.0 MiB DL]

To fix this issue, two changes were necessary:

* Reset the global `_isInterrupted` variable: only because a single
  operation was aborted, it should still be possible to continue the
  session.
* Recreate a `fileTransfer`-instance if the current one was shut down by
  an abort.
---
 src/libstore/filetransfer.cc | 21 +++++++++++++++++++--
 src/nix/repl.cc              |  2 ++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/src/libstore/filetransfer.cc b/src/libstore/filetransfer.cc
index 2cf35ec83..758862e60 100644
--- a/src/libstore/filetransfer.cc
+++ b/src/libstore/filetransfer.cc
@@ -716,15 +716,32 @@ struct curlFileTransfer : public FileTransfer
     }
 };
 
+ref<curlFileTransfer> makeCurlFileTransfer()
+{
+    return make_ref<curlFileTransfer>();
+}
+
 ref<FileTransfer> getFileTransfer()
 {
-    static ref<FileTransfer> fileTransfer = makeFileTransfer();
+    static ref<curlFileTransfer> fileTransfer = makeCurlFileTransfer();
+
+    // this has to be done in its own scope to make sure that the lock is released
+    // before creating a new fileTransfer instance.
+    auto needsRecreation = [&]() -> bool {
+        auto state = fileTransfer->state_.lock();
+        return state->quit;
+    };
+
+    if (needsRecreation()) {
+        fileTransfer = makeCurlFileTransfer();
+    }
+
     return fileTransfer;
 }
 
 ref<FileTransfer> makeFileTransfer()
 {
-    return make_ref<curlFileTransfer>();
+    return makeCurlFileTransfer();
 }
 
 std::future<FileTransferResult> FileTransfer::enqueueFileTransfer(const FileTransferRequest & request)
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index c1233ab46..4b2efa293 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -396,6 +396,8 @@ bool NixRepl::processLine(string line)
 {
     if (line == "") return true;
 
+    _isInterrupted = false;
+
     string command, arg;
 
     if (line[0] == ':') {

From d7d6fe44d690977e7a91b459c15c0d4e8bc09dce Mon Sep 17 00:00:00 2001
From: Sergei Trofimovich <slyich@gmail.com>
Date: Fri, 8 Oct 2021 07:13:59 +0100
Subject: [PATCH 085/567] libstore-tests: add libutil dependency (fix static
 link failure)

In https://github.com/NixOS/nix/pull/5350 we noticed link failures
pkgsStatic.nixUnstable. Adding explicit dependency on libutil fixes
libstore-tests linking.
---
 src/libstore/tests/local.mk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libstore/tests/local.mk b/src/libstore/tests/local.mk
index 6ae9a0285..f74295d97 100644
--- a/src/libstore/tests/local.mk
+++ b/src/libstore/tests/local.mk
@@ -10,6 +10,6 @@ libstore-tests_SOURCES := $(wildcard $(d)/*.cc)
 
 libstore-tests_CXXFLAGS += -I src/libstore -I src/libutil
 
-libstore-tests_LIBS = libstore
+libstore-tests_LIBS = libstore libutil
 
 libstore-tests_LDFLAGS := $(GTEST_LIBS)

From 0351422662133b6e51217e36c8bab539c855dfdc Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Fri, 8 Oct 2021 10:12:27 +0200
Subject: [PATCH 086/567] gitignore the `libstore-tests` executable

So that running `make` still leaves a clean tree
---
 .gitignore | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.gitignore b/.gitignore
index 86ffe9304..b6a5f6adc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -40,6 +40,7 @@ perl/Makefile.config
 
 # /src/libstore/
 *.gen.*
+/src/libstore/tests/libstore-tests
 
 # /src/libutil/
 /src/libutil/tests/libutil-tests

From 01e9f046a8f8fafb4d084153d4b30dd3a8d7aef5 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 8 Oct 2021 15:00:28 +0200
Subject: [PATCH 087/567] Update release script

---
 maintainers/upload-release.pl | 63 ++++++++++++++++++-----------------
 1 file changed, 33 insertions(+), 30 deletions(-)

diff --git a/maintainers/upload-release.pl b/maintainers/upload-release.pl
index 66ccf1443..f2d6896db 100755
--- a/maintainers/upload-release.pl
+++ b/maintainers/upload-release.pl
@@ -12,6 +12,7 @@ use LWP::UserAgent;
 use Net::Amazon::S3;
 
 my $evalId = $ARGV[0] or die "Usage: $0 EVAL-ID\n";
+my $nixRev = $ARGV[1] or die; # FIXME
 
 my $releasesBucketName = "nix-releases";
 my $channelsBucketName = "nix-channels";
@@ -19,6 +20,8 @@ my $nixpkgsDir = "/home/eelco/Dev/nixpkgs-pristine";
 
 my $TMPDIR = $ENV{'TMPDIR'} // "/tmp";
 
+my $isLatest = ($ENV{'IS_LATEST'} // "") eq "1";
+
 # FIXME: cut&paste from nixos-channel-scripts.
 sub fetch {
     my ($url, $type) = @_;
@@ -33,14 +36,15 @@ sub fetch {
 }
 
 my $evalUrl = "https://hydra.nixos.org/eval/$evalId";
-my $evalInfo = decode_json(fetch($evalUrl, 'application/json'));
+#my $evalInfo = decode_json(fetch($evalUrl, 'application/json'));
 #print Dumper($evalInfo);
 
-my $nixRev = $evalInfo->{jobsetevalinputs}->{nix}->{revision} or die;
+#my $nixRev = $evalInfo->{jobsetevalinputs}->{nix}->{revision} or die;
 
-my $tarballInfo = decode_json(fetch("$evalUrl/job/tarball", 'application/json'));
+my $buildInfo = decode_json(fetch("$evalUrl/job/build.x86_64-linux", 'application/json'));
+#print Dumper($buildInfo);
 
-my $releaseName = $tarballInfo->{releasename};
+my $releaseName = $buildInfo->{nixname};
 $releaseName =~ /nix-(.*)$/ or die;
 my $version = $1;
 
@@ -104,8 +108,6 @@ sub downloadFile {
     return $sha256_expected;
 }
 
-downloadFile("tarball", "2"); # .tar.bz2
-my $tarballHash = downloadFile("tarball", "3"); # .tar.xz
 downloadFile("binaryTarball.i686-linux", "1");
 downloadFile("binaryTarball.x86_64-linux", "1");
 downloadFile("binaryTarball.aarch64-linux", "1");
@@ -134,42 +136,43 @@ for my $fn (glob "$tmpDir/*") {
     }
 }
 
-exit if $version =~ /pre/;
-
 # Update nix-fallback-paths.nix.
-system("cd $nixpkgsDir && git pull") == 0 or die;
+if ($isLatest) {
+    system("cd $nixpkgsDir && git pull") == 0 or die;
 
-sub getStorePath {
-    my ($jobName) = @_;
-    my $buildInfo = decode_json(fetch("$evalUrl/job/$jobName", 'application/json'));
-    for my $product (values %{$buildInfo->{buildproducts}}) {
-        next unless $product->{type} eq "nix-build";
-        next if $product->{path} =~ /[a-z]+$/;
-        return $product->{path};
+    sub getStorePath {
+        my ($jobName) = @_;
+        my $buildInfo = decode_json(fetch("$evalUrl/job/$jobName", 'application/json'));
+        for my $product (values %{$buildInfo->{buildproducts}}) {
+            next unless $product->{type} eq "nix-build";
+            next if $product->{path} =~ /[a-z]+$/;
+            return $product->{path};
+        }
+        die;
     }
-    die;
+
+    write_file("$nixpkgsDir/nixos/modules/installer/tools/nix-fallback-paths.nix",
+               "{\n" .
+               "  x86_64-linux = \"" . getStorePath("build.x86_64-linux") . "\";\n" .
+               "  i686-linux = \"" . getStorePath("build.i686-linux") . "\";\n" .
+               "  aarch64-linux = \"" . getStorePath("build.aarch64-linux") . "\";\n" .
+               "  x86_64-darwin = \"" . getStorePath("build.x86_64-darwin") . "\";\n" .
+               "  aarch64-darwin = \"" . getStorePath("build.aarch64-darwin") . "\";\n" .
+               "}\n");
+
+    system("cd $nixpkgsDir && git commit -a -m 'nix-fallback-paths.nix: Update to $version'") == 0 or die;
 }
 
-write_file("$nixpkgsDir/nixos/modules/installer/tools/nix-fallback-paths.nix",
-           "{\n" .
-           "  x86_64-linux = \"" . getStorePath("build.x86_64-linux") . "\";\n" .
-           "  i686-linux = \"" . getStorePath("build.i686-linux") . "\";\n" .
-           "  aarch64-linux = \"" . getStorePath("build.aarch64-linux") . "\";\n" .
-           "  x86_64-darwin = \"" . getStorePath("build.x86_64-darwin") . "\";\n" .
-           "  aarch64-darwin = \"" . getStorePath("build.aarch64-darwin") . "\";\n" .
-           "}\n");
-
-system("cd $nixpkgsDir && git commit -a -m 'nix-fallback-paths.nix: Update to $version'") == 0 or die;
-
 # Update the "latest" symlink.
 $channelsBucket->add_key(
     "nix-latest/install", "",
     { "x-amz-website-redirect-location" => "https://releases.nixos.org/$releaseDir/install" })
-    or die $channelsBucket->err . ": " . $channelsBucket->errstr;
+    or die $channelsBucket->err . ": " . $channelsBucket->errstr
+    if $isLatest;
 
 # Tag the release in Git.
 chdir("/home/eelco/Dev/nix-pristine") or die;
 system("git remote update origin") == 0 or die;
 system("git tag --force --sign $version $nixRev -m 'Tagging release $version'") == 0 or die;
 system("git push --tags") == 0 or die;
-system("git push --force-with-lease origin $nixRev:refs/heads/latest-release") == 0 or die;
+system("git push --force-with-lease origin $nixRev:refs/heads/latest-release") == 0 or die if $isLatest;

From f147f42f462085f98434068d9e229ff195013200 Mon Sep 17 00:00:00 2001
From: Sergei Trofimovich <slyich@gmail.com>
Date: Fri, 8 Oct 2021 22:57:42 +0100
Subject: [PATCH 088/567] mk/libraries.mk: fix trace-ld and trace-ar expansions

Noticed this minor logging deficiency when debugged --disable-shared
build:

  LD
  AR
  LD
  CXX    src/libstore/local-store.o

After the change build is logged as expected:

  LD     src/libmain/libnixmain.a
  LD     src/libfetchers/libnixfetchers.a
  AR     src/libmain/libnixmain.a
  CXX    src/libstore/local-store.o
---
 mk/libraries.mk | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mk/libraries.mk b/mk/libraries.mk
index 07bd54dab..ffd7b5610 100644
--- a/mk/libraries.mk
+++ b/mk/libraries.mk
@@ -125,8 +125,8 @@ define build-library
     $(1)_PATH := $$(_d)/$$($(1)_NAME).a
 
     $$($(1)_PATH): $$($(1)_OBJS) | $$(_d)/
-	$(trace-ld) $(LD) -Ur -o $$(_d)/$$($(1)_NAME).o $$?
-	$(trace-ar) $(AR) crs $$@ $$(_d)/$$($(1)_NAME).o
+	$$(trace-ld) $(LD) -Ur -o $$(_d)/$$($(1)_NAME).o $$?
+	$$(trace-ar) $(AR) crs $$@ $$(_d)/$$($(1)_NAME).o
 
     $(1)_LDFLAGS_USE += $$($(1)_PATH) $$($(1)_LDFLAGS)
 

From e399c6ab7fbe21e32683a1a4128ff655b276c9bf Mon Sep 17 00:00:00 2001
From: Artturin <Artturin@artturin.com>
Date: Sat, 9 Oct 2021 01:19:50 +0300
Subject: [PATCH 089/567] nix develop: add --unpack

---
 src/nix/develop.cc | 6 ++++++
 src/nix/develop.md | 1 +
 2 files changed, 7 insertions(+)

diff --git a/src/nix/develop.cc b/src/nix/develop.cc
index c20b9f272..f22335023 100644
--- a/src/nix/develop.cc
+++ b/src/nix/develop.cc
@@ -392,6 +392,12 @@ struct CmdDevelop : Common, MixEnvironment
             .handler = {&phase},
         });
 
+        addFlag({
+            .longName = "unpack",
+            .description = "Run the `unpack` phase.",
+            .handler = {&phase, {"unpack"}},
+        });
+
         addFlag({
             .longName = "configure",
             .description = "Run the `configure` phase.",
diff --git a/src/nix/develop.md b/src/nix/develop.md
index c86c4872b..1f214966a 100644
--- a/src/nix/develop.md
+++ b/src/nix/develop.md
@@ -29,6 +29,7 @@ R""(
 * Run a particular build phase directly:
 
   ```console
+  # nix develop --unpack
   # nix develop --configure
   # nix develop --build
   # nix develop --check

From 4cff4130549abf65eb17242a373eb98953252895 Mon Sep 17 00:00:00 2001
From: John Chapman <thestar@fussycoder.id.au>
Date: Sat, 9 Oct 2021 12:03:34 +1100
Subject: [PATCH 090/567] Clarify that not all nix packages will use the
 default build phases

---
 doc/manual/src/command-ref/nix-shell.md | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/doc/manual/src/command-ref/nix-shell.md b/doc/manual/src/command-ref/nix-shell.md
index 72f6730f1..8bcad85e1 100644
--- a/doc/manual/src/command-ref/nix-shell.md
+++ b/doc/manual/src/command-ref/nix-shell.md
@@ -117,6 +117,12 @@ $ nix-shell '<nixpkgs>' -A pan
 [nix-shell]$ ./pan/gui/pan
 ```
 
+Note: Other packages may override these phases (the unpackPhase,
+configurePhase, buildPhase, etc).
+For those, it may be required to do something like
+`eval "$configurePhase-configurePhase"` or `eval "$configurePhase"`
+depending on how that package's nix files have been written.
+
 To clear the environment first, and do some additional automatic
 initialisation of the interactive shell:
 

From 7466048d397ed33d4bc28b6910c834cf1a17b0cb Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Mon, 11 Oct 2021 10:47:02 +0200
Subject: [PATCH 091/567] (partially) Revert "Don't copy in rethrow"
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This reverts some parts of commit
8430a8f0866e4463a891ccce62779ea9ac0f3b38 which was trying to rethrow
some exceptions while we weren’t in the context of a `catch` block,
causing some weird “terminate called without an active exception”
errors.

Fix #5368
---
 src/libexpr/primops.cc                      | 2 +-
 src/libstore/build/local-derivation-goal.cc | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index f27331534..4e0eda7f3 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -575,7 +575,7 @@ static Bindings::iterator getAttr(
             // Adding another trace for the function name to make it clear
             // which call received wrong arguments.
             e.addTrace(pos, hintfmt("while invoking '%s'", funcName));
-            throw;
+            throw e;
         }
     }
 
diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 3fc156108..8d245f84a 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -948,7 +948,7 @@ void LocalDerivationGoal::startBuilder()
             FdSource source(builderOut.readSide.get());
             auto ex = readError(source);
             ex.addTrace({}, "while setting up the build environment");
-            throw;
+            throw ex;
         }
         debug("sandbox setup: " + msg);
         msgs.push_back(std::move(msg));

From 03bb8f84e0f54d9980b160785f98da8ae07196fe Mon Sep 17 00:00:00 2001
From: Tom Bereknyei <tomberek@gmail.com>
Date: Tue, 12 Oct 2021 02:14:36 -0400
Subject: [PATCH 092/567] Add compression level for NARs

Based off on @dtzWill's #2276
---
 src/libstore/binary-cache-store.cc |  2 +-
 src/libstore/binary-cache-store.hh |  8 ++++++--
 src/libutil/compression.cc         | 22 +++++++++++++++-------
 src/libutil/compression.hh         |  4 ++--
 tests/compression-levels.sh        | 22 ++++++++++++++++++++++
 tests/local.mk                     |  1 +
 6 files changed, 47 insertions(+), 12 deletions(-)
 create mode 100644 tests/compression-levels.sh

diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index 3a6be541f..8fce94264 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -149,7 +149,7 @@ ref<const ValidPathInfo> BinaryCacheStore::addToStoreCommon(
     {
     FdSink fileSink(fdTemp.get());
     TeeSink teeSinkCompressed { fileSink, fileHashSink };
-    auto compressionSink = makeCompressionSink(compression, teeSinkCompressed);
+    auto compressionSink = makeCompressionSink(compression, teeSinkCompressed, parallelCompression, compressionLevel);
     TeeSink teeSinkUncompressed { *compressionSink, narHashSink };
     TeeSource teeSource { narSource, teeSinkUncompressed };
     narAccessor = makeNarAccessor(teeSource);
diff --git a/src/libstore/binary-cache-store.hh b/src/libstore/binary-cache-store.hh
index 657be2fcf..723f2e805 100644
--- a/src/libstore/binary-cache-store.hh
+++ b/src/libstore/binary-cache-store.hh
@@ -15,13 +15,17 @@ struct BinaryCacheStoreConfig : virtual StoreConfig
 {
     using StoreConfig::StoreConfig;
 
-    const Setting<std::string> compression{(StoreConfig*) this, "xz", "compression", "NAR compression method ('xz', 'bzip2', or 'none')"};
+    const Setting<std::string> compression{(StoreConfig*) this, "xz", "compression", "NAR compression method ('xz', 'bzip2', 'gzip', 'zstd', or 'none')"};
     const Setting<bool> writeNARListing{(StoreConfig*) this, false, "write-nar-listing", "whether to write a JSON file listing the files in each NAR"};
     const Setting<bool> writeDebugInfo{(StoreConfig*) this, false, "index-debug-info", "whether to index DWARF debug info files by build ID"};
     const Setting<Path> secretKeyFile{(StoreConfig*) this, "", "secret-key", "path to secret key used to sign the binary cache"};
     const Setting<Path> localNarCache{(StoreConfig*) this, "", "local-nar-cache", "path to a local cache of NARs"};
     const Setting<bool> parallelCompression{(StoreConfig*) this, false, "parallel-compression",
-        "enable multi-threading compression, available for xz only currently"};
+        "enable multi-threading compression for NARs, available for xz and zstd only currently"};
+    const Setting<int> compressionLevel{(StoreConfig*) this, -1, "compression-level",
+        "specify 'preset level' of compression to be used with NARs: "
+        "meaning and accepted range of values depends on compression method selected, "
+        "other than -1 which we reserve to indicate Nix defaults should be used"};
 };
 
 class BinaryCacheStore : public virtual BinaryCacheStoreConfig, public virtual Store
diff --git a/src/libutil/compression.cc b/src/libutil/compression.cc
index d26f68fde..4802edb78 100644
--- a/src/libutil/compression.cc
+++ b/src/libutil/compression.cc
@@ -16,6 +16,8 @@
 
 namespace nix {
 
+static const int COMPRESSION_LEVEL_DEFAULT = -1;
+
 // Don't feed brotli too much at once.
 struct ChunkedCompressionSink : CompressionSink
 {
@@ -65,14 +67,17 @@ struct ArchiveCompressionSink : CompressionSink
     Sink & nextSink;
     struct archive * archive;
 
-    ArchiveCompressionSink(Sink & nextSink, std::string format, bool parallel) : nextSink(nextSink) {
+    ArchiveCompressionSink(Sink & nextSink, std::string format, bool parallel, int _level = COMPRESSION_LEVEL_DEFAULT) : nextSink(nextSink) {
         archive = archive_write_new();
         if (!archive) throw Error("failed to initialize libarchive");
         check(archive_write_add_filter_by_name(archive, format.c_str()), "couldn't initialize compression (%s)");
         check(archive_write_set_format_raw(archive));
-        if (format == "xz" && parallel) {
+        if (parallel) {
             check(archive_write_set_filter_option(archive, format.c_str(), "threads", "0"));
         }
+        if (_level != COMPRESSION_LEVEL_DEFAULT){
+            check(archive_write_set_filter_option(archive, format.c_str(), "compression-level", std::to_string(_level).c_str()));
+        }
         // disable internal buffering
         check(archive_write_set_bytes_per_block(archive, 0));
         // disable output padding
@@ -126,7 +131,10 @@ private:
 struct NoneSink : CompressionSink
 {
     Sink & nextSink;
-    NoneSink(Sink & nextSink) : nextSink(nextSink) { }
+    NoneSink(Sink & nextSink, int level = COMPRESSION_LEVEL_DEFAULT) : nextSink(nextSink) {
+        if (level != COMPRESSION_LEVEL_DEFAULT)
+            printError("Warning: requested compression level '%d' not supported by compression method 'none'", level);
+    }
     void finish() override { flush(); }
     void write(std::string_view data) override { nextSink(data); }
 };
@@ -257,13 +265,13 @@ struct BrotliCompressionSink : ChunkedCompressionSink
     }
 };
 
-ref<CompressionSink> makeCompressionSink(const std::string & method, Sink & nextSink, const bool parallel)
+ref<CompressionSink> makeCompressionSink(const std::string & method, Sink & nextSink, const bool parallel, int level)
 {
     std::vector<std::string> la_supports = {
         "bzip2", "compress", "grzip", "gzip", "lrzip", "lz4", "lzip", "lzma", "lzop", "xz", "zstd"
     };
     if (std::find(la_supports.begin(), la_supports.end(), method) != la_supports.end()) {
-        return make_ref<ArchiveCompressionSink>(nextSink, method, parallel);
+        return make_ref<ArchiveCompressionSink>(nextSink, method, parallel, level);
     }
     if (method == "none")
         return make_ref<NoneSink>(nextSink);
@@ -273,10 +281,10 @@ ref<CompressionSink> makeCompressionSink(const std::string & method, Sink & next
         throw UnknownCompressionMethod("unknown compression method '%s'", method);
 }
 
-ref<std::string> compress(const std::string & method, const std::string & in, const bool parallel)
+ref<std::string> compress(const std::string & method, const std::string & in, const bool parallel, int level)
 {
     StringSink ssink;
-    auto sink = makeCompressionSink(method, ssink, parallel);
+    auto sink = makeCompressionSink(method, ssink, parallel, level);
     (*sink)(in);
     sink->finish();
     return ssink.s;
diff --git a/src/libutil/compression.hh b/src/libutil/compression.hh
index 338a0d9f2..9b1e4a9d4 100644
--- a/src/libutil/compression.hh
+++ b/src/libutil/compression.hh
@@ -19,9 +19,9 @@ ref<std::string> decompress(const std::string & method, const std::string & in);
 
 std::unique_ptr<FinishSink> makeDecompressionSink(const std::string & method, Sink & nextSink);
 
-ref<std::string> compress(const std::string & method, const std::string & in, const bool parallel = false);
+ref<std::string> compress(const std::string & method, const std::string & in, const bool parallel = false, int level = -1);
 
-ref<CompressionSink> makeCompressionSink(const std::string & method, Sink & nextSink, const bool parallel = false);
+ref<CompressionSink> makeCompressionSink(const std::string & method, Sink & nextSink, const bool parallel = false, int level = -1);
 
 MakeError(UnknownCompressionMethod, Error);
 
diff --git a/tests/compression-levels.sh b/tests/compression-levels.sh
new file mode 100644
index 000000000..85f12974a
--- /dev/null
+++ b/tests/compression-levels.sh
@@ -0,0 +1,22 @@
+source common.sh
+
+clearStore
+clearCache
+
+outPath=$(nix-build dependencies.nix --no-out-link)
+
+cacheURI="file://$cacheDir?compression=xz&compression-level=0"
+
+nix copy --to $cacheURI $outPath
+
+FILESIZES=$(cat ${cacheDir}/*.narinfo | awk '/FileSize: /{sum+=$2}END{print sum}')
+
+clearCache
+
+cacheURI="file://$cacheDir?compression=xz&compression-level=5"
+
+nix copy --to $cacheURI $outPath
+
+FILESIZES2=$(cat ${cacheDir}/*.narinfo | awk '/FileSize: /{sum+=$2}END{print sum}')
+
+[[ $FILESIZES -gt $FILESIZES2 ]]
diff --git a/tests/local.mk b/tests/local.mk
index b100e7f15..d88c3a875 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -33,6 +33,7 @@ nix_tests = \
   shell.sh \
   brotli.sh \
   zstd.sh \
+  compression-levels.sh \
   pure-eval.sh \
   check.sh \
   plugins.sh \

From 9ebe02a81e6ecb15abaa695c26b3773ce46ef155 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 12 Oct 2021 15:27:02 +0200
Subject: [PATCH 093/567] nix repl: Don't build in a child process

Fixes #5356. This is a bit risky due to interrupts, but we have to
deal with those anyway (#5353).
---
 src/nix/repl.cc | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index c1233ab46..fb33fc23e 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -498,17 +498,11 @@ bool NixRepl::processLine(string line)
         Path drvPathRaw = state->store->printStorePath(drvPath);
 
         if (command == ":b") {
-            /* We could do the build in this process using buildPaths(),
-               but doing it in a child makes it easier to recover from
-               problems / SIGINT. */
-            try {
-                runNix("nix", {"build", "--no-link", drvPathRaw});
-                auto drv = state->store->readDerivation(drvPath);
-                std::cout << std::endl << "this derivation produced the following outputs:" << std::endl;
-                for (auto & i : drv.outputsAndOptPaths(*state->store))
-                    std::cout << fmt("  %s -> %s\n", i.first, state->store->printStorePath(*i.second.second));
-            } catch (ExecError &) {
-            }
+            state->store->buildPaths({DerivedPath::Built{drvPath}});
+            auto drv = state->store->readDerivation(drvPath);
+            logger->cout("\nThis derivation produced the following outputs:");
+            for (auto & i : drv.outputsAndOptPaths(*state->store))
+                logger->cout("  %s -> %s", i.first, state->store->printStorePath(*i.second.second));
         } else if (command == ":i") {
             runNix("nix-env", {"-i", drvPathRaw});
         } else {

From f6cdae5181fb32231d75439635106e3d093931ad Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 12 Oct 2021 15:36:45 +0200
Subject: [PATCH 094/567] nix repl: Don't write to std::cout directly

Writing to std::cout doesn't play nice with ProgressBar.
---
 src/nix/repl.cc | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index fb33fc23e..68ed04a13 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -200,13 +200,13 @@ namespace {
 void NixRepl::mainLoop(const std::vector<std::string> & files)
 {
     string error = ANSI_RED "error:" ANSI_NORMAL " ";
-    std::cout << "Welcome to Nix version " << nixVersion << ". Type :? for help." << std::endl << std::endl;
+    notice("Welcome to Nix " + nixVersion + ". Type :? for help.\n");
 
     for (auto & i : files)
         loadedFiles.push_back(i);
 
     reloadFiles();
-    if (!loadedFiles.empty()) std::cout << std::endl;
+    if (!loadedFiles.empty()) notice("");
 
     // Allow nix-repl specific settings in .inputrc
     rl_readline_name = "nix-repl";
@@ -479,9 +479,10 @@ bool NixRepl::processLine(string line)
     else if (command == ":t") {
         Value v;
         evalString(arg, v);
-        std::cout << showType(v) << std::endl;
+        logger->cout(showType(v));
+    }
 
-    } else if (command == ":u") {
+    else if (command == ":u") {
         Value v, f, result;
         evalString(arg, v);
         evalString("drv: (import <nixpkgs> {}).runCommand \"shell\" { buildInputs = [ drv ]; } \"\"", f);
@@ -535,9 +536,9 @@ bool NixRepl::processLine(string line)
                     + concatStringsSep(" ", args) + "\n\n";
             }
 
-            markdown += trim(stripIndentation(doc->doc));
+            markdown += stripIndentation(doc->doc);
 
-            std::cout << renderMarkdownToTerminal(markdown);
+            logger->cout(trim(renderMarkdownToTerminal(markdown)));
         } else
             throw Error("value does not have documentation");
     }
@@ -620,9 +621,9 @@ void NixRepl::reloadFiles()
 
     bool first = true;
     for (auto & i : old) {
-        if (!first) std::cout << std::endl;
+        if (!first) notice("");
         first = false;
-        std::cout << format("Loading '%1%'...") % i << std::endl;
+        notice("Loading '%1%'...", i);
         loadFile(i);
     }
 }
@@ -633,7 +634,7 @@ void NixRepl::addAttrsToScope(Value & attrs)
     state->forceAttrs(attrs);
     for (auto & i : *attrs.attrs)
         addVarToScope(i.name, *i.value);
-    std::cout << format("Added %1% variables.") % attrs.attrs->size() << std::endl;
+    notice("Added %1% variables.", attrs.attrs->size());
 }
 
 

From 5176b072ed55d1528cb36e0c865e4fcffbc6a7a1 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 12 Oct 2021 16:43:00 +0200
Subject: [PATCH 095/567] Cleanup

---
 src/libstore/filetransfer.cc | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/src/libstore/filetransfer.cc b/src/libstore/filetransfer.cc
index 758862e60..37e17b397 100644
--- a/src/libstore/filetransfer.cc
+++ b/src/libstore/filetransfer.cc
@@ -725,16 +725,8 @@ ref<FileTransfer> getFileTransfer()
 {
     static ref<curlFileTransfer> fileTransfer = makeCurlFileTransfer();
 
-    // this has to be done in its own scope to make sure that the lock is released
-    // before creating a new fileTransfer instance.
-    auto needsRecreation = [&]() -> bool {
-        auto state = fileTransfer->state_.lock();
-        return state->quit;
-    };
-
-    if (needsRecreation()) {
+    if (fileTransfer->state_.lock()->quit)
         fileTransfer = makeCurlFileTransfer();
-    }
 
     return fileTransfer;
 }

From 8a3b8d0b33a7b1429311b041e10a8304f2cb6718 Mon Sep 17 00:00:00 2001
From: "Travis A. Everett" <travis.a.everett@gmail.com>
Date: Tue, 12 Oct 2021 18:17:27 -0500
Subject: [PATCH 096/567] darwin-install: fix incorrect fn name

---
 scripts/install-darwin-multi-user.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/install-darwin-multi-user.sh b/scripts/install-darwin-multi-user.sh
index 32a12f2ee..96eba8310 100644
--- a/scripts/install-darwin-multi-user.sh
+++ b/scripts/install-darwin-multi-user.sh
@@ -78,7 +78,7 @@ poly_service_installed_check() {
 poly_service_uninstall_directions() {
     echo "$1. Remove macOS-specific components:"
     if should_create_volume && test_nix_volume_mountd_installed; then
-        darwin_volume_uninstall_directions
+        nix_volume_mountd_uninstall_directions
     fi
     if test_nix_daemon_installed; then
         nix_daemon_uninstall_directions

From 0fac86fd6feea5f584cb5765b04baeba908bcc03 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 13 Oct 2021 11:00:10 +0200
Subject: [PATCH 097/567] Style tweaks

---
 src/libutil/compression.cc | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/libutil/compression.cc b/src/libutil/compression.cc
index 4802edb78..f80ca664c 100644
--- a/src/libutil/compression.cc
+++ b/src/libutil/compression.cc
@@ -67,17 +67,16 @@ struct ArchiveCompressionSink : CompressionSink
     Sink & nextSink;
     struct archive * archive;
 
-    ArchiveCompressionSink(Sink & nextSink, std::string format, bool parallel, int _level = COMPRESSION_LEVEL_DEFAULT) : nextSink(nextSink) {
+    ArchiveCompressionSink(Sink & nextSink, std::string format, bool parallel, int level = COMPRESSION_LEVEL_DEFAULT) : nextSink(nextSink)
+    {
         archive = archive_write_new();
         if (!archive) throw Error("failed to initialize libarchive");
         check(archive_write_add_filter_by_name(archive, format.c_str()), "couldn't initialize compression (%s)");
         check(archive_write_set_format_raw(archive));
-        if (parallel) {
+        if (parallel)
             check(archive_write_set_filter_option(archive, format.c_str(), "threads", "0"));
-        }
-        if (_level != COMPRESSION_LEVEL_DEFAULT){
-            check(archive_write_set_filter_option(archive, format.c_str(), "compression-level", std::to_string(_level).c_str()));
-        }
+        if (level != COMPRESSION_LEVEL_DEFAULT)
+            check(archive_write_set_filter_option(archive, format.c_str(), "compression-level", std::to_string(level).c_str()));
         // disable internal buffering
         check(archive_write_set_bytes_per_block(archive, 0));
         // disable output padding
@@ -131,9 +130,10 @@ private:
 struct NoneSink : CompressionSink
 {
     Sink & nextSink;
-    NoneSink(Sink & nextSink, int level = COMPRESSION_LEVEL_DEFAULT) : nextSink(nextSink) {
+    NoneSink(Sink & nextSink, int level = COMPRESSION_LEVEL_DEFAULT) : nextSink(nextSink)
+    {
         if (level != COMPRESSION_LEVEL_DEFAULT)
-            printError("Warning: requested compression level '%d' not supported by compression method 'none'", level);
+            warn("requested compression level '%d' not supported by compression method 'none'", level);
     }
     void finish() override { flush(); }
     void write(std::string_view data) override { nextSink(data); }

From 2f3c79c2415d6fefe73b0313fb178f58df52ff26 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 13 Oct 2021 11:11:26 +0200
Subject: [PATCH 098/567] Mention compression-level in the release notes

---
 doc/manual/src/release-notes/rl-2.5.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/doc/manual/src/release-notes/rl-2.5.md b/doc/manual/src/release-notes/rl-2.5.md
index ede614ca3..a95208b9e 100644
--- a/doc/manual/src/release-notes/rl-2.5.md
+++ b/doc/manual/src/release-notes/rl-2.5.md
@@ -1,2 +1,3 @@
 # Release 2.5 (2021-XX-XX)
 
+* Binary cache stores now have a setting `compression-level`.

From 4c0cde95ad8dc95f876e5cf32790e73e08f49b28 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 13 Oct 2021 11:39:54 +0200
Subject: [PATCH 099/567] Update release notes

---
 doc/manual/src/release-notes/rl-2.5.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/doc/manual/src/release-notes/rl-2.5.md b/doc/manual/src/release-notes/rl-2.5.md
index a95208b9e..9a29938c2 100644
--- a/doc/manual/src/release-notes/rl-2.5.md
+++ b/doc/manual/src/release-notes/rl-2.5.md
@@ -1,3 +1,5 @@
 # Release 2.5 (2021-XX-XX)
 
 * Binary cache stores now have a setting `compression-level`.
+
+* `nix develop` now has a flag `--unpack` to run `unpackPhase`.

From 8eac7dfad427acff412d2cd1a0de6e6e683aac0b Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 16 Aug 2021 13:52:19 +0200
Subject: [PATCH 100/567] Remove trash directory

---
 src/libstore/gc.cc          | 62 ++++---------------------------------
 src/libstore/local-store.cc |  1 -
 src/libstore/local-store.hh |  1 -
 3 files changed, 6 insertions(+), 58 deletions(-)

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 5a62c6529..5de09d8c2 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -465,11 +465,9 @@ struct LocalStore::GCState
     StorePathSet alive;
     bool gcKeepOutputs;
     bool gcKeepDerivations;
-    uint64_t bytesInvalidated;
-    bool moveToTrash = true;
     bool shouldDelete;
     GCState(const GCOptions & options, GCResults & results)
-        : options(options), results(results), bytesInvalidated(0) { }
+        : options(options), results(results) { }
 };
 
 
@@ -493,15 +491,12 @@ void LocalStore::deletePathRecursive(GCState & state, const Path & path)
 {
     checkInterrupt();
 
-    uint64_t size = 0;
-
     auto storePath = maybeParseStorePath(path);
     if (storePath && isValidPath(*storePath)) {
         StorePathSet referrers;
         queryReferrers(*storePath, referrers);
         for (auto & i : referrers)
             if (printStorePath(i) != path) deletePathRecursive(state, printStorePath(i));
-        size = queryPathInfo(*storePath)->narSize;
         invalidatePathChecked(*storePath);
     }
 
@@ -517,33 +512,10 @@ void LocalStore::deletePathRecursive(GCState & state, const Path & path)
 
     state.results.paths.insert(path);
 
-    /* If the path is not a regular file or symlink, move it to the
-       trash directory.  The move is to ensure that later (when we're
-       not holding the global GC lock) we can delete the path without
-       being afraid that the path has become alive again.  Otherwise
-       delete it right away. */
-    if (state.moveToTrash && S_ISDIR(st.st_mode)) {
-        // Estimate the amount freed using the narSize field.  FIXME:
-        // if the path was not valid, need to determine the actual
-        // size.
-        try {
-            if (chmod(realPath.c_str(), st.st_mode | S_IWUSR) == -1)
-                throw SysError("making '%1%' writable", realPath);
-            Path tmp = trashDir + "/" + std::string(baseNameOf(path));
-            if (rename(realPath.c_str(), tmp.c_str()))
-                throw SysError("unable to rename '%1%' to '%2%'", realPath, tmp);
-            state.bytesInvalidated += size;
-        } catch (SysError & e) {
-            if (e.errNo == ENOSPC) {
-                printInfo(format("note: can't create move '%1%': %2%") % realPath % e.msg());
-                deleteGarbage(state, realPath);
-            }
-        }
-    } else
-        deleteGarbage(state, realPath);
+    deleteGarbage(state, realPath);
 
-    if (state.results.bytesFreed + state.bytesInvalidated > state.options.maxFreed) {
-        printInfo(format("deleted or invalidated more than %1% bytes; stopping") % state.options.maxFreed);
+    if (state.results.bytesFreed > state.options.maxFreed) {
+        printInfo("deleted more than %d bytes; stopping", state.options.maxFreed);
         throw GCLimitReached();
     }
 }
@@ -607,7 +579,7 @@ void LocalStore::tryToDelete(GCState & state, const Path & path)
     checkInterrupt();
 
     auto realPath = realStoreDir + "/" + std::string(baseNameOf(path));
-    if (realPath == linksDir || realPath == trashDir) return;
+    if (realPath == linksDir) return;
 
     //Activity act(*logger, lvlDebug, format("considering whether to delete '%1%'") % path);
 
@@ -710,9 +682,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
     if (state.shouldDelete)
         deletePath(reservedPath);
 
-    /* Acquire the global GC root.  This prevents
-       a) New roots from being added.
-       b) Processes from creating new temporary root files. */
+    /* Acquire the global GC root. */
     AutoCloseFD fdGCLock = openGCLock(ltWrite);
 
     /* Find the roots.  Since we've grabbed the GC lock, the set of
@@ -739,18 +709,6 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
        increase, since we hold locks on everything.  So everything
        that is not reachable from `roots' is garbage. */
 
-    if (state.shouldDelete) {
-        if (pathExists(trashDir)) deleteGarbage(state, trashDir);
-        try {
-            createDirs(trashDir);
-        } catch (SysError & e) {
-            if (e.errNo == ENOSPC) {
-                printInfo("note: can't create trash directory: %s", e.msg());
-                state.moveToTrash = false;
-            }
-        }
-    }
-
     /* Now either delete all garbage paths, or just the specified
        paths (for gcDeleteSpecific). */
 
@@ -828,14 +786,6 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
         return;
     }
 
-    /* Allow other processes to add to the store from here on. */
-    fdGCLock = -1;
-    fds.clear();
-
-    /* Delete the trash directory. */
-    printInfo(format("deleting '%1%'") % trashDir);
-    deleteGarbage(state, trashDir);
-
     /* Clean up the links directory. */
     if (options.action == GCOptions::gcDeleteDead || options.action == GCOptions::gcDeleteSpecific) {
         printInfo("deleting unused links...");
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 5b2490472..3978f4eed 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -145,7 +145,6 @@ LocalStore::LocalStore(const Params & params)
     , linksDir(realStoreDir + "/.links")
     , reservedPath(dbDir + "/reserved")
     , schemaPath(dbDir + "/schema")
-    , trashDir(realStoreDir + "/trash")
     , tempRootsDir(stateDir + "/temproots")
     , fnTempRoots(fmt("%s/%d", tempRootsDir, getpid()))
     , locksHeld(tokenizeString<PathSet>(getEnv("NIX_HELD_LOCKS").value_or("")))
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index a01d48c4b..5215c9f02 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -87,7 +87,6 @@ public:
     const Path linksDir;
     const Path reservedPath;
     const Path schemaPath;
-    const Path trashDir;
     const Path tempRootsDir;
     const Path fnTempRoots;
 

From 9947f1646a26b339fff2e02b77798e9841fac7f0 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 17 Aug 2021 18:53:14 +0200
Subject: [PATCH 101/567] Remove syncWithGC()

---
 src/libstore/daemon.cc       |  2 +-
 src/libstore/gc.cc           | 17 ++++++-----------
 src/libstore/local-store.hh  |  2 --
 src/libstore/remote-store.cc |  9 ---------
 src/libstore/remote-store.hh |  2 --
 src/libstore/store-api.hh    | 20 --------------------
 6 files changed, 7 insertions(+), 45 deletions(-)

diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index 164a9b2be..3df88ff03 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -624,9 +624,9 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         break;
     }
 
+    // Obsolete.
     case wopSyncWithGC: {
         logger->startWork();
-        store->syncWithGC();
         logger->stopWork();
         to << 1;
         break;
diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 5de09d8c2..18328467b 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -71,12 +71,6 @@ static void makeSymlink(const Path & link, const Path & target)
 }
 
 
-void LocalStore::syncWithGC()
-{
-    AutoCloseFD fdGCLock = openGCLock(ltRead);
-}
-
-
 void LocalStore::addIndirectRoot(const Path & path)
 {
     string hash = hashString(htSHA1, path).to_string(Base32, false);
@@ -95,6 +89,12 @@ Path LocalFSStore::addPermRoot(const StorePath & storePath, const Path & _gcRoot
                 "creating a garbage collector root (%1%) in the Nix store is forbidden "
                 "(are you running nix-build inside the store?)", gcRoot);
 
+    /* Register this root with the garbage collector, if it's
+       running. This should be superfluous since the caller should
+       have registered this root yet, but let's be on the safe
+       side. */
+    addTempRoot(storePath);
+
     /* Don't clobber the link if it already exists and doesn't
        point to the Nix store. */
     if (pathExists(gcRoot) && (!isLink(gcRoot) || !isInStore(readLink(gcRoot))))
@@ -102,11 +102,6 @@ Path LocalFSStore::addPermRoot(const StorePath & storePath, const Path & _gcRoot
     makeSymlink(gcRoot, printStorePath(storePath));
     addIndirectRoot(gcRoot);
 
-    /* Grab the global GC root, causing us to block while a GC is in
-       progress.  This prevents the set of permanent roots from
-       increasing while a GC is in progress. */
-    syncWithGC();
-
     return gcRoot;
 }
 
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 5215c9f02..3b3f26162 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -148,8 +148,6 @@ public:
 
     void addIndirectRoot(const Path & path) override;
 
-    void syncWithGC() override;
-
 private:
 
     typedef std::shared_ptr<AutoCloseFD> FDPtr;
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index fa5ea8af7..7decc059c 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -797,15 +797,6 @@ void RemoteStore::addIndirectRoot(const Path & path)
 }
 
 
-void RemoteStore::syncWithGC()
-{
-    auto conn(getConnection());
-    conn->to << wopSyncWithGC;
-    conn.processStderr();
-    readInt(conn->from);
-}
-
-
 Roots RemoteStore::findRoots(bool censor)
 {
     auto conn(getConnection());
diff --git a/src/libstore/remote-store.hh b/src/libstore/remote-store.hh
index ac1eaa19e..a3036e6b0 100644
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@@ -101,8 +101,6 @@ public:
 
     void addIndirectRoot(const Path & path) override;
 
-    void syncWithGC() override;
-
     Roots findRoots(bool censor) override;
 
     void collectGarbage(const GCOptions & options, GCResults & results) override;
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 54471bdf2..35461b76d 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -561,26 +561,6 @@ public:
     virtual void addIndirectRoot(const Path & path)
     { unsupported("addIndirectRoot"); }
 
-    /* Acquire the global GC lock, then immediately release it.  This
-       function must be called after registering a new permanent root,
-       but before exiting.  Otherwise, it is possible that a running
-       garbage collector doesn't see the new root and deletes the
-       stuff we've just built.  By acquiring the lock briefly, we
-       ensure that either:
-
-       - The collector is already running, and so we block until the
-         collector is finished.  The collector will know about our
-         *temporary* locks, which should include whatever it is we
-         want to register as a permanent lock.
-
-       - The collector isn't running, or it's just started but hasn't
-         acquired the GC lock yet.  In that case we get and release
-         the lock right away, then exit.  The collector scans the
-         permanent root and sees ours.
-
-       In either case the permanent root is seen by the collector. */
-    virtual void syncWithGC() { };
-
     /* Find the roots of the garbage collector.  Each root is a pair
        (link, storepath) where `link' is the path of the symlink
        outside of the Nix store that point to `storePath'. If

From 8614cf13344eca75074cd4af20fd90238571b0b6 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 16 Aug 2021 20:03:32 +0200
Subject: [PATCH 102/567] Non-blocking garbage collector

The garbage collector no longer blocks other processes from
adding/building store paths or adding GC roots. To prevent the
collector from deleting store paths just added by another process,
processes need to connect to the garbage collector via a Unix domain
socket to register new temporary roots.
---
 src/libstore/build/local-derivation-goal.cc |   2 +-
 src/libstore/gc.cc                          | 524 +++++++++++---------
 src/libstore/local-store.cc                 |   9 +-
 src/libstore/local-store.hh                 |  28 +-
 src/libstore/pathlocks.cc                   |  13 +
 src/libstore/pathlocks.hh                   |  14 +
 src/libstore/uds-remote-store.cc            |   9 +-
 src/libutil/util.cc                         |  10 +-
 src/libutil/util.hh                         |   3 +
 tests/ca/build-with-garbage-path.sh         |   2 +-
 tests/repair.sh                             |   2 +-
 11 files changed, 344 insertions(+), 272 deletions(-)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 8d245f84a..bafa83a9d 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -1353,7 +1353,7 @@ void LocalDerivationGoal::startDaemon()
             AutoCloseFD remote = accept(daemonSocket.get(),
                 (struct sockaddr *) &remoteAddr, &remoteAddrLen);
             if (!remote) {
-                if (errno == EINTR) continue;
+                if (errno == EINTR || errno == EAGAIN) continue;
                 if (errno == EINVAL) break;
                 throw SysError("accepting connection");
             }
diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 18328467b..2d7734729 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -10,48 +10,22 @@
 #include <regex>
 #include <random>
 
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <sys/statvfs.h>
+#include <climits>
 #include <errno.h>
 #include <fcntl.h>
+#include <poll.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/statvfs.h>
+#include <sys/types.h>
+#include <sys/un.h>
 #include <unistd.h>
-#include <climits>
 
 namespace nix {
 
 
-static string gcLockName = "gc.lock";
-static string gcRootsDir = "gcroots";
-
-
-/* Acquire the global GC lock.  This is used to prevent new Nix
-   processes from starting after the temporary root files have been
-   read.  To be precise: when they try to create a new temporary root
-   file, they will block until the garbage collector has finished /
-   yielded the GC lock. */
-AutoCloseFD LocalStore::openGCLock(LockType lockType)
-{
-    Path fnGCLock = (format("%1%/%2%")
-        % stateDir % gcLockName).str();
-
-    debug(format("acquiring global GC lock '%1%'") % fnGCLock);
-
-    AutoCloseFD fdGCLock = open(fnGCLock.c_str(), O_RDWR | O_CREAT | O_CLOEXEC, 0600);
-    if (!fdGCLock)
-        throw SysError("opening global GC lock '%1%'", fnGCLock);
-
-    if (!lockFile(fdGCLock.get(), lockType, false)) {
-        printInfo("waiting for the big garbage collector lock...");
-        lockFile(fdGCLock.get(), lockType, true);
-    }
-
-    /* !!! Restrict read permission on the GC root.  Otherwise any
-       process that can open the file for reading can DoS the
-       collector. */
-
-    return fdGCLock;
-}
+static std::string gcSocketPath = "/gc-socket/socket";
+static std::string gcRootsDir = "gcroots";
 
 
 static void makeSymlink(const Path & link, const Path & target)
@@ -114,8 +88,6 @@ void LocalStore::addTempRoot(const StorePath & path)
     if (!state->fdTempRoots) {
 
         while (1) {
-            AutoCloseFD fdGCLock = openGCLock(ltRead);
-
             if (pathExists(fnTempRoots))
                 /* It *must* be stale, since there can be no two
                    processes with the same pid. */
@@ -123,10 +95,8 @@ void LocalStore::addTempRoot(const StorePath & path)
 
             state->fdTempRoots = openLockFile(fnTempRoots, true);
 
-            fdGCLock = -1;
-
-            debug(format("acquiring read lock on '%1%'") % fnTempRoots);
-            lockFile(state->fdTempRoots.get(), ltRead, true);
+            debug("acquiring write lock on '%s'", fnTempRoots);
+            lockFile(state->fdTempRoots.get(), ltWrite, true);
 
             /* Check whether the garbage collector didn't get in our
                way. */
@@ -142,24 +112,62 @@ void LocalStore::addTempRoot(const StorePath & path)
 
     }
 
-    /* Upgrade the lock to a write lock.  This will cause us to block
-       if the garbage collector is holding our lock. */
-    debug(format("acquiring write lock on '%1%'") % fnTempRoots);
-    lockFile(state->fdTempRoots.get(), ltWrite, true);
+ restart:
+    FdLock gcLock(state->fdGCLock.get(), ltRead, false, "");
 
+    if (!gcLock.acquired) {
+        /* We couldn't get a shared global GC lock, so the garbage
+           collector is running. So we have to connect to the garbage
+           collector and inform it about our root. */
+        if (!state->fdRootsSocket) {
+            state->fdRootsSocket = createUnixDomainSocket();
+
+            auto socketPath = stateDir.get() + gcSocketPath;
+
+            debug("connecting to '%s'", socketPath);
+
+            struct sockaddr_un addr;
+            addr.sun_family = AF_UNIX;
+            if (socketPath.size() + 1 >= sizeof(addr.sun_path))
+                throw Error("socket path '%s' is too long", socketPath);
+            strcpy(addr.sun_path, socketPath.c_str());
+
+            if (::connect(state->fdRootsSocket.get(), (struct sockaddr *) &addr, sizeof(addr)) == -1)
+                throw SysError("cannot connect to garbage collector at '%s'", socketPath);
+        }
+
+        try {
+            debug("sending GC root '%s'", printStorePath(path));
+            writeFull(state->fdRootsSocket.get(), printStorePath(path) + "\n", false);
+            char c;
+            readFull(state->fdRootsSocket.get(), &c, 1);
+            assert(c == '1');
+            debug("got ack for GC root '%s'", printStorePath(path));
+        } catch (SysError & e) {
+            /* The garbage collector may have exited, so we need to
+               restart. */
+            if (e.errNo == EPIPE) {
+                debug("GC socket disconnected");
+                state->fdRootsSocket.close();
+                goto restart;
+            }
+        } catch (EndOfFile & e) {
+            debug("GC socket disconnected");
+            state->fdRootsSocket.close();
+            goto restart;
+        }
+    }
+
+    /* Append the store path to the temporary roots file. */
     string s = printStorePath(path) + '\0';
     writeFull(state->fdTempRoots.get(), s);
-
-    /* Downgrade to a read lock. */
-    debug(format("downgrading to read lock on '%1%'") % fnTempRoots);
-    lockFile(state->fdTempRoots.get(), ltRead, true);
 }
 
 
 static std::string censored = "{censored}";
 
 
-void LocalStore::findTempRoots(FDs & fds, Roots & tempRoots, bool censor)
+void LocalStore::findTempRoots(Roots & tempRoots, bool censor)
 {
     /* Read the `temproots' directory for per-process temporary root
        files. */
@@ -174,35 +182,25 @@ void LocalStore::findTempRoots(FDs & fds, Roots & tempRoots, bool censor)
         pid_t pid = std::stoi(i.name);
 
         debug(format("reading temporary root file '%1%'") % path);
-        FDPtr fd(new AutoCloseFD(open(path.c_str(), O_CLOEXEC | O_RDWR, 0666)));
-        if (!*fd) {
+        AutoCloseFD fd(open(path.c_str(), O_CLOEXEC | O_RDWR, 0666));
+        if (!fd) {
             /* It's okay if the file has disappeared. */
             if (errno == ENOENT) continue;
             throw SysError("opening temporary roots file '%1%'", path);
         }
 
-        /* This should work, but doesn't, for some reason. */
-        //FDPtr fd(new AutoCloseFD(openLockFile(path, false)));
-        //if (*fd == -1) continue;
-
         /* Try to acquire a write lock without blocking.  This can
            only succeed if the owning process has died.  In that case
            we don't care about its temporary roots. */
-        if (lockFile(fd->get(), ltWrite, false)) {
+        if (lockFile(fd.get(), ltWrite, false)) {
             printInfo("removing stale temporary roots file '%1%'", path);
             unlink(path.c_str());
-            writeFull(fd->get(), "d");
+            writeFull(fd.get(), "d");
             continue;
         }
 
-        /* Acquire a read lock.  This will prevent the owning process
-           from upgrading to a write lock, therefore it will block in
-           addTempRoot(). */
-        debug(format("waiting for read lock on '%1%'") % path);
-        lockFile(fd->get(), ltRead, true);
-
         /* Read the entire file. */
-        string contents = readFile(fd->get());
+        string contents = readFile(fd.get());
 
         /* Extract the roots. */
         string::size_type pos = 0, end;
@@ -213,8 +211,6 @@ void LocalStore::findTempRoots(FDs & fds, Roots & tempRoots, bool censor)
             tempRoots[parseStorePath(root)].emplace(censor ? censored : fmt("{temp:%d}", pid));
             pos = end + 1;
         }
-
-        fds.push_back(fd); /* keep open */
     }
 }
 
@@ -299,8 +295,7 @@ Roots LocalStore::findRoots(bool censor)
     Roots roots;
     findRootsNoTemp(roots, censor);
 
-    FDs fds;
-    findTempRoots(fds, roots, censor);
+    findTempRoots(roots, censor);
 
     return roots;
 }
@@ -455,160 +450,141 @@ struct LocalStore::GCState
     const GCOptions & options;
     GCResults & results;
     StorePathSet roots;
-    StorePathSet tempRoots;
     StorePathSet dead;
     StorePathSet alive;
     bool gcKeepOutputs;
     bool gcKeepDerivations;
     bool shouldDelete;
+
+    struct Shared
+    {
+        // The temp roots only store the hash part to make it easier to
+        // ignore suffixes like '.lock', '.chroot' and '.check'.
+        std::unordered_set<std::string> tempRoots;
+
+        // Hash part of the store path currently being deleted, if
+        // any.
+        std::optional<std::string> pending;
+    };
+
+    Sync<Shared> shared;
+
+    std::condition_variable wakeup;
+
     GCState(const GCOptions & options, GCResults & results)
         : options(options), results(results) { }
 };
 
 
-bool LocalStore::isActiveTempFile(const GCState & state,
-    const Path & path, const string & suffix)
-{
-    return hasSuffix(path, suffix)
-        && state.tempRoots.count(parseStorePath(string(path, 0, path.size() - suffix.size())));
-}
-
-
-void LocalStore::deleteGarbage(GCState & state, const Path & path)
-{
-    uint64_t bytesFreed;
-    deletePath(path, bytesFreed);
-    state.results.bytesFreed += bytesFreed;
-}
-
-
-void LocalStore::deletePathRecursive(GCState & state, const Path & path)
-{
-    checkInterrupt();
-
-    auto storePath = maybeParseStorePath(path);
-    if (storePath && isValidPath(*storePath)) {
-        StorePathSet referrers;
-        queryReferrers(*storePath, referrers);
-        for (auto & i : referrers)
-            if (printStorePath(i) != path) deletePathRecursive(state, printStorePath(i));
-        invalidatePathChecked(*storePath);
-    }
-
-    Path realPath = realStoreDir + "/" + std::string(baseNameOf(path));
-
-    struct stat st;
-    if (lstat(realPath.c_str(), &st)) {
-        if (errno == ENOENT) return;
-        throw SysError("getting status of %1%", realPath);
-    }
-
-    printInfo(format("deleting '%1%'") % path);
-
-    state.results.paths.insert(path);
-
-    deleteGarbage(state, realPath);
-
-    if (state.results.bytesFreed > state.options.maxFreed) {
-        printInfo("deleted more than %d bytes; stopping", state.options.maxFreed);
-        throw GCLimitReached();
-    }
-}
-
-
-bool LocalStore::canReachRoot(GCState & state, StorePathSet & visited, const StorePath & path)
-{
-    if (visited.count(path)) return false;
-
-    if (state.alive.count(path)) return true;
-
-    if (state.dead.count(path)) return false;
-
-    if (state.roots.count(path)) {
-        debug("cannot delete '%1%' because it's a root", printStorePath(path));
-        state.alive.insert(path);
-        return true;
-    }
-
-    visited.insert(path);
-
-    if (!isValidPath(path)) return false;
-
-    StorePathSet incoming;
-
-    /* Don't delete this path if any of its referrers are alive. */
-    queryReferrers(path, incoming);
-
-    /* If keep-derivations is set and this is a derivation, then
-       don't delete the derivation if any of the outputs are alive. */
-    if (state.gcKeepDerivations && path.isDerivation()) {
-        for (auto & [name, maybeOutPath] : queryPartialDerivationOutputMap(path))
-            if (maybeOutPath &&
-                isValidPath(*maybeOutPath) &&
-                queryPathInfo(*maybeOutPath)->deriver == path
-                )
-                incoming.insert(*maybeOutPath);
-    }
-
-    /* If keep-outputs is set, then don't delete this path if there
-       are derivers of this path that are not garbage. */
-    if (state.gcKeepOutputs) {
-        auto derivers = queryValidDerivers(path);
-        for (auto & i : derivers)
-            incoming.insert(i);
-    }
-
-    for (auto & i : incoming)
-        if (i != path)
-            if (canReachRoot(state, visited, i)) {
-                state.alive.insert(path);
-                return true;
-            }
-
-    return false;
-}
-
-
-void LocalStore::tryToDelete(GCState & state, const Path & path)
+bool LocalStore::tryToDelete(
+    GCState & state,
+    StorePathSet & visited,
+    const Path & path,
+    bool recursive)
 {
     checkInterrupt();
 
     auto realPath = realStoreDir + "/" + std::string(baseNameOf(path));
-    if (realPath == linksDir) return;
+    if (realPath == linksDir) return false;
 
     //Activity act(*logger, lvlDebug, format("considering whether to delete '%1%'") % path);
 
     auto storePath = maybeParseStorePath(path);
 
-    if (!storePath || !isValidPath(*storePath)) {
-        /* A lock file belonging to a path that we're building right
-           now isn't garbage. */
-        if (isActiveTempFile(state, path, ".lock")) return;
+    /* Wake up any client waiting for deletion of this path to
+       finish. */
+    Finally releasePending([&]() {
+        auto shared(state.shared.lock());
+        shared->pending.reset();
+        state.wakeup.notify_all();
+    });
 
-        /* Don't delete .chroot directories for derivations that are
-           currently being built. */
-        if (isActiveTempFile(state, path, ".chroot")) return;
+    if (storePath) {
 
-        /* Don't delete .check directories for derivations that are
-           currently being built, because we may need to run
-           diff-hook. */
-        if (isActiveTempFile(state, path, ".check")) return;
-    }
+        if (!visited.insert(*storePath).second) return true;
 
-    StorePathSet visited;
+        if (state.alive.count(*storePath)) return false;
+
+        if (state.dead.count(*storePath)) return true;
+
+        if (state.roots.count(*storePath)) {
+            debug("cannot delete '%s' because it's a root", path);
+            state.alive.insert(*storePath);
+            return false;
+        }
+
+        if (isValidPath(*storePath)) {
+            StorePathSet incoming;
+
+            /* Don't delete this path if any of its referrers are alive. */
+            queryReferrers(*storePath, incoming);
+
+            /* If keep-derivations is set and this is a derivation, then
+               don't delete the derivation if any of the outputs are alive. */
+            if (state.gcKeepDerivations && storePath->isDerivation()) {
+                for (auto & [name, maybeOutPath] : queryPartialDerivationOutputMap(*storePath))
+                    if (maybeOutPath &&
+                        isValidPath(*maybeOutPath) &&
+                        queryPathInfo(*maybeOutPath)->deriver == *storePath)
+                        incoming.insert(*maybeOutPath);
+            }
+
+            /* If keep-outputs is set, then don't delete this path if there
+               are derivers of this path that are not garbage. */
+            if (state.gcKeepOutputs) {
+                auto derivers = queryValidDerivers(*storePath);
+                for (auto & i : derivers)
+                    incoming.insert(i);
+            }
+
+            for (auto & i : incoming)
+                if (i != *storePath
+                    && (recursive || state.options.pathsToDelete.count(i))
+                    && !tryToDelete(state, visited, printStorePath(i), recursive))
+                {
+                    state.alive.insert(*storePath);
+                    return false;
+                }
+        }
+
+        {
+            auto hashPart = std::string(storePath->hashPart());
+            auto shared(state.shared.lock());
+            if (shared->tempRoots.count(hashPart))
+                return false;
+            shared->pending = hashPart;
+        }
+
+        state.dead.insert(*storePath);
 
-    if (storePath && canReachRoot(state, visited, *storePath)) {
-        debug("cannot delete '%s' because it's still reachable", path);
-    } else {
-        /* No path we visited was a root, so everything is garbage.
-           But we only delete ‘path’ and its referrers here so that
-           ‘nix-store --delete’ doesn't have the unexpected effect of
-           recursing into derivations and outputs. */
-        for (auto & i : visited)
-            state.dead.insert(i);
         if (state.shouldDelete)
-            deletePathRecursive(state, path);
+            invalidatePathChecked(*storePath);
     }
+
+    if (state.shouldDelete) {
+        Path realPath = realStoreDir + "/" + std::string(baseNameOf(path));
+
+        struct stat st;
+        if (lstat(realPath.c_str(), &st)) {
+            if (errno == ENOENT) return true;
+            throw SysError("getting status of %1%", realPath);
+        }
+
+        printInfo("deleting '%1%'", path);
+
+        state.results.paths.insert(path);
+
+        uint64_t bytesFreed;
+        deletePath(realPath, bytesFreed);
+        state.results.bytesFreed += bytesFreed;
+
+        if (state.results.bytesFreed > state.options.maxFreed) {
+            printInfo("deleted more than %d bytes; stopping", state.options.maxFreed);
+            throw GCLimitReached();
+        }
+    }
+
+    return true;
 }
 
 
@@ -678,7 +654,104 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
         deletePath(reservedPath);
 
     /* Acquire the global GC root. */
-    AutoCloseFD fdGCLock = openGCLock(ltWrite);
+    FdLock gcLock(_state.lock()->fdGCLock.get(), ltWrite, true, "waiting for the big garbage collector lock...");
+
+    /* Start the server for receiving new roots. */
+    auto socketPath = stateDir.get() + gcSocketPath;
+    createDirs(dirOf(socketPath));
+    auto fdServer = createUnixDomainSocket(socketPath, 0666);
+
+    if (fcntl(fdServer.get(), F_SETFL, fcntl(fdServer.get(), F_GETFL) | O_NONBLOCK) == -1)
+        throw SysError("making socket '%1%' non-blocking", socketPath);
+
+    Pipe shutdownPipe;
+    shutdownPipe.create();
+
+    std::thread serverThread([&]() {
+        std::map<int, std::pair<std::unique_ptr<AutoCloseFD>, std::string>> fdClients;
+        bool quit = false;
+
+        while (!quit) {
+            std::vector<struct pollfd> fds;
+            fds.push_back({.fd = shutdownPipe.readSide.get(), .events = POLLIN});
+            fds.push_back({.fd = fdServer.get(), .events = POLLIN});
+            for (auto & i : fdClients)
+                fds.push_back({.fd = i.first, .events = POLLIN});
+            auto count = poll(fds.data(), fds.size(), -1);
+            assert(count != -1);
+
+            for (auto & fd : fds) {
+                if (!fd.revents) continue;
+                if (fd.fd == shutdownPipe.readSide.get())
+                    /* Parent is asking us to quit. */
+                    quit = true;
+                else if (fd.fd == fdServer.get()) {
+                    /* Accept a new connection. */
+                    assert(fd.revents & POLLIN);
+                    auto fdClient = std::make_unique<AutoCloseFD>(accept(fdServer.get(), nullptr, nullptr));
+                    if (*fdClient) {
+                        auto fd = fdClient->get();
+                        fdClients.insert({fd, std::make_pair(std::move(fdClient), "")});
+                    }
+                }
+                else {
+                    /* Receive data from a client. */
+                    auto fdClient = fdClients.find(fd.fd);
+                    assert(fdClient != fdClients.end());
+                    if (fd.revents & POLLIN) {
+                        char buf[16384];
+                        auto n = read(fd.fd, buf, sizeof(buf));
+                        if (n > 0) {
+                            fdClient->second.second.append(buf, n);
+                            /* Split the input into lines. */
+                            while (true) {
+                                auto p = fdClient->second.second.find('\n');
+                                if (p == std::string::npos) break;
+                                /* We got a full line. Send ack back
+                                   to the client. */
+                                auto path = fdClient->second.second.substr(0, p);
+                                fdClient->second.second = fdClient->second.second.substr(p + 1);
+                                auto storePath = maybeParseStorePath(path);
+                                if (storePath) {
+                                    debug("got new GC root '%s'", path);
+                                    auto hashPart = std::string(storePath->hashPart());
+                                    auto shared(state.shared.lock());
+                                    shared->tempRoots.insert(hashPart);
+                                    /* If this path is currently being
+                                       deleted, then we have to wait
+                                       until deletion is finished to
+                                       ensure that the client doesn't
+                                       start re-creating it before
+                                       we're done. FIXME: ideally we
+                                       would use a FD for this so we
+                                       don't block the poll loop. */
+                                    while (shared->pending == hashPart) {
+                                        debug("synchronising with deletion of path '%s'", path);
+                                        shared.wait(state.wakeup);
+                                    }
+                                } else
+                                    printError("received garbage instead of a root from client");
+                                // This could block, but meh.
+                                try {
+                                    writeFull(fd.fd, "1", false);
+                                } catch (SysError &) { }
+                            }
+                        } else if (n == 0)
+                            fdClients.erase(fdClient);
+                    } else
+                        fdClients.erase(fdClient);
+                }
+            }
+        }
+
+        debug("GC roots server shut down");
+    });
+
+    Finally stopServer([&]() {
+        writeFull(shutdownPipe.writeSide.get(), "x", false);
+        state.wakeup.notify_all();
+        if (serverThread.joinable()) serverThread.join();
+    });
 
     /* Find the roots.  Since we've grabbed the GC lock, the set of
        permanent roots cannot increase now. */
@@ -689,32 +762,26 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 
     for (auto & i : rootMap) state.roots.insert(i.first);
 
-    /* Read the temporary roots.  This acquires read locks on all
-       per-process temporary root files.  So after this point no paths
-       can be added to the set of temporary roots. */
-    FDs fds;
+    /* Read the temporary roots created before we acquired the global
+       GC root. Any new roots will be sent to our socket. */
     Roots tempRoots;
-    findTempRoots(fds, tempRoots, true);
+    findTempRoots(tempRoots, true);
     for (auto & root : tempRoots) {
-        state.tempRoots.insert(root.first);
+        state.shared.lock()->tempRoots.insert(std::string(root.first.hashPart()));
         state.roots.insert(root.first);
     }
 
-    /* After this point the set of roots or temporary roots cannot
-       increase, since we hold locks on everything.  So everything
-       that is not reachable from `roots' is garbage. */
-
     /* Now either delete all garbage paths, or just the specified
        paths (for gcDeleteSpecific). */
 
     if (options.action == GCOptions::gcDeleteSpecific) {
 
         for (auto & i : options.pathsToDelete) {
-            tryToDelete(state, printStorePath(i));
-            if (state.dead.find(i) == state.dead.end())
+            StorePathSet visited;
+            if (!tryToDelete(state, visited, printStorePath(i), false))
                 throw Error(
                     "cannot delete path '%1%' since it is still alive. "
-                    "To find out why use: "
+                    "To find out why, use: "
                     "nix-store --query --roots",
                     printStorePath(i));
         }
@@ -727,44 +794,21 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
             printInfo("determining live/dead paths...");
 
         try {
-
             AutoCloseDir dir(opendir(realStoreDir.get().c_str()));
             if (!dir) throw SysError("opening directory '%1%'", realStoreDir);
 
-            /* Read the store and immediately delete all paths that
-               aren't valid.  When using --max-freed etc., deleting
-               invalid paths is preferred over deleting unreachable
-               paths, since unreachable paths could become reachable
-               again.  We don't use readDirectory() here so that GCing
-               can start faster. */
+            /* Read the store and delete all paths that are invalid or
+               unreachable. We don't use readDirectory() here so that
+               GCing can start faster. */
             Paths entries;
             struct dirent * dirent;
             while (errno = 0, dirent = readdir(dir.get())) {
                 checkInterrupt();
                 string name = dirent->d_name;
                 if (name == "." || name == "..") continue;
-                Path path = storeDir + "/" + name;
-                auto storePath = maybeParseStorePath(path);
-                if (storePath && isValidPath(*storePath))
-                    entries.push_back(path);
-                else
-                    tryToDelete(state, path);
+                StorePathSet visited;
+                tryToDelete(state, visited, storeDir + "/" + name, true);
             }
-
-            dir.reset();
-
-            /* Now delete the unreachable valid paths.  Randomise the
-               order in which we delete entries to make the collector
-               less biased towards deleting paths that come
-               alphabetically first (e.g. /nix/store/000...).  This
-               matters when using --max-freed etc. */
-            vector<Path> entries_(entries.begin(), entries.end());
-            std::mt19937 gen(1);
-            std::shuffle(entries_.begin(), entries_.end(), gen);
-
-            for (auto & i : entries_)
-                tryToDelete(state, i);
-
         } catch (GCLimitReached & e) {
         }
     }
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 3978f4eed..faecdb00b 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -382,6 +382,11 @@ LocalStore::LocalStore(const Params & params)
                     (select id from Realisations where drvPath = ? and outputName = ?));
             )");
     }
+
+    Path fnGCLock = stateDir + "/gc.lock";
+    state->fdGCLock = open(fnGCLock.c_str(), O_RDWR | O_CREAT | O_CLOEXEC, 0600);
+    if (!state->fdGCLock)
+        throw SysError("opening global GC lock '%1%'", fnGCLock);
 }
 
 
@@ -1504,7 +1509,7 @@ bool LocalStore::verifyStore(bool checkContents, RepairFlag repair)
 
     /* Acquire the global GC lock to get a consistent snapshot of
        existing and valid paths. */
-    AutoCloseFD fdGCLock = openGCLock(ltWrite);
+    FdLock gcLock(_state.lock()->fdGCLock.get(), ltWrite, true, "waiting for the big garbage collector lock...");
 
     StringSet store;
     for (auto & i : readDirectory(realStoreDir)) store.insert(i.name);
@@ -1515,8 +1520,6 @@ bool LocalStore::verifyStore(bool checkContents, RepairFlag repair)
     StorePathSet validPaths;
     PathSet done;
 
-    fdGCLock = -1;
-
     for (auto & i : queryAllValidPaths())
         verifyPath(printStorePath(i), store, done, validPaths, repair, errors);
 
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 3b3f26162..85c6c4495 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -58,9 +58,15 @@ private:
         struct Stmts;
         std::unique_ptr<Stmts> stmts;
 
+        /* The global GC lock  */
+        AutoCloseFD fdGCLock;
+
         /* The file to which we write our temporary roots. */
         AutoCloseFD fdTempRoots;
 
+        /* Connection to the garbage collector. */
+        AutoCloseFD fdRootsSocket;
+
         /* The last time we checked whether to do an auto-GC, or an
            auto-GC finished. */
         std::chrono::time_point<std::chrono::steady_clock> lastGCCheck;
@@ -150,10 +156,7 @@ public:
 
 private:
 
-    typedef std::shared_ptr<AutoCloseFD> FDPtr;
-    typedef list<FDPtr> FDs;
-
-    void findTempRoots(FDs & fds, Roots & roots, bool censor);
+    void findTempRoots(Roots & roots, bool censor);
 
 public:
 
@@ -235,18 +238,11 @@ private:
 
     struct GCState;
 
-    void deleteGarbage(GCState & state, const Path & path);
-
-    void tryToDelete(GCState & state, const Path & path);
-
-    bool canReachRoot(GCState & state, StorePathSet & visited, const StorePath & path);
-
-    void deletePathRecursive(GCState & state, const Path & path);
-
-    bool isActiveTempFile(const GCState & state,
-        const Path & path, const string & suffix);
-
-    AutoCloseFD openGCLock(LockType lockType);
+    bool tryToDelete(
+        GCState & state,
+        StorePathSet & visited,
+        const Path & path,
+        bool recursive);
 
     void findRoots(const Path & path, unsigned char type, Roots & roots);
 
diff --git a/src/libstore/pathlocks.cc b/src/libstore/pathlocks.cc
index 926f4ea1e..2da74e262 100644
--- a/src/libstore/pathlocks.cc
+++ b/src/libstore/pathlocks.cc
@@ -176,4 +176,17 @@ void PathLocks::setDeletion(bool deletePaths)
 }
 
 
+FdLock::FdLock(int fd, LockType lockType, bool wait, std::string_view waitMsg)
+    : fd(fd)
+{
+    if (wait) {
+        if (!lockFile(fd, lockType, false)) {
+            printInfo("%s", waitMsg);
+            acquired = lockFile(fd, lockType, true);
+        }
+    } else
+        acquired = lockFile(fd, lockType, false);
+}
+
+
 }
diff --git a/src/libstore/pathlocks.hh b/src/libstore/pathlocks.hh
index 411da0222..919c8904c 100644
--- a/src/libstore/pathlocks.hh
+++ b/src/libstore/pathlocks.hh
@@ -35,4 +35,18 @@ public:
     void setDeletion(bool deletePaths);
 };
 
+struct FdLock
+{
+    int fd;
+    bool acquired = false;
+
+    FdLock(int fd, LockType lockType, bool wait, std::string_view waitMsg);
+
+    ~FdLock()
+    {
+        if (acquired)
+            lockFile(fd, ltNone, false);
+    }
+};
+
 }
diff --git a/src/libstore/uds-remote-store.cc b/src/libstore/uds-remote-store.cc
index 02e81b022..5c38323cd 100644
--- a/src/libstore/uds-remote-store.cc
+++ b/src/libstore/uds-remote-store.cc
@@ -56,14 +56,7 @@ ref<RemoteStore::Connection> UDSRemoteStore::openConnection()
     auto conn = make_ref<Connection>();
 
     /* Connect to a daemon that does the privileged work for us. */
-    conn->fd = socket(PF_UNIX, SOCK_STREAM
-        #ifdef SOCK_CLOEXEC
-        | SOCK_CLOEXEC
-        #endif
-        , 0);
-    if (!conn->fd)
-        throw SysError("cannot create Unix domain socket");
-    closeOnExec(conn->fd.get());
+    conn->fd = createUnixDomainSocket();
 
     nix::connect(conn->fd.get(), path ? *path : settings.nixDaemonSocketFile);
 
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 563a72c12..5945571b9 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1670,7 +1670,7 @@ std::unique_ptr<InterruptCallback> createInterruptCallback(std::function<void()>
 }
 
 
-AutoCloseFD createUnixDomainSocket(const Path & path, mode_t mode)
+AutoCloseFD createUnixDomainSocket()
 {
     AutoCloseFD fdSocket = socket(PF_UNIX, SOCK_STREAM
         #ifdef SOCK_CLOEXEC
@@ -1679,8 +1679,14 @@ AutoCloseFD createUnixDomainSocket(const Path & path, mode_t mode)
         , 0);
     if (!fdSocket)
         throw SysError("cannot create Unix domain socket");
-
     closeOnExec(fdSocket.get());
+    return fdSocket;
+}
+
+
+AutoCloseFD createUnixDomainSocket(const Path & path, mode_t mode)
+{
+    auto fdSocket = nix::createUnixDomainSocket();
 
     bind(fdSocket.get(), path);
 
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 29232453f..528d113db 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -571,6 +571,9 @@ extern PathFilter defaultPathFilter;
 /* Common initialisation performed in child processes. */
 void commonChildInit(Pipe & logPipe);
 
+/* Create a Unix domain socket. */
+AutoCloseFD createUnixDomainSocket();
+
 /* Create a Unix domain socket in listen mode. */
 AutoCloseFD createUnixDomainSocket(const Path & path, mode_t mode);
 
diff --git a/tests/ca/build-with-garbage-path.sh b/tests/ca/build-with-garbage-path.sh
index 9aa08a899..884cd2802 100755
--- a/tests/ca/build-with-garbage-path.sh
+++ b/tests/ca/build-with-garbage-path.sh
@@ -8,7 +8,7 @@ requireDaemonNewerThan "2.4pre20210621"
 
 # Get the output path of `rootCA`, and put some garbage instead
 outPath="$(nix-build ./content-addressed.nix -A rootCA --no-out-link)"
-nix-store --delete "$outPath"
+nix-store --delete $(nix-store -q --referrers-closure "$outPath")
 touch "$outPath"
 
 # The build should correctly remove the garbage and put the expected path instead
diff --git a/tests/repair.sh b/tests/repair.sh
index 12dcde8ea..1105b446b 100644
--- a/tests/repair.sh
+++ b/tests/repair.sh
@@ -30,7 +30,7 @@ nix-store --verify-path $path2
 chmod u+w $path2
 touch $path2/bad
 
-nix-store --delete $(nix-store -qd $path2)
+nix-store --delete $(nix-store -q --referrers-closure $(nix-store -qd $path2))
 
 (! nix-store --verify --check-contents --repair)
 

From ff453b06f94b4305694beac8255d9ff51bed1a63 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 19 Aug 2021 22:43:43 +0200
Subject: [PATCH 103/567] Fix auto-gc

---
 src/libstore/gc.cc          | 10 ++++++++--
 src/libstore/local-store.cc | 12 +++++++++---
 src/libstore/local-store.hh |  2 ++
 3 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 2d7734729..ff66c3938 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -112,6 +112,9 @@ void LocalStore::addTempRoot(const StorePath & path)
 
     }
 
+    if (!state->fdGCLock)
+        state->fdGCLock = openGCLock();
+
  restart:
     FdLock gcLock(state->fdGCLock.get(), ltRead, false, "");
 
@@ -653,8 +656,11 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
     if (state.shouldDelete)
         deletePath(reservedPath);
 
-    /* Acquire the global GC root. */
-    FdLock gcLock(_state.lock()->fdGCLock.get(), ltWrite, true, "waiting for the big garbage collector lock...");
+    /* Acquire the global GC root. Note: we don't use state->fdGCLock
+       here because then in auto-gc mode, another thread could
+       downgrade our exclusive lock. */
+    auto fdGCLock = openGCLock();
+    FdLock gcLock(fdGCLock.get(), ltWrite, true, "waiting for the big garbage collector lock...");
 
     /* Start the server for receiving new roots. */
     auto socketPath = stateDir.get() + gcSocketPath;
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index faecdb00b..0e6556e11 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -382,11 +382,16 @@ LocalStore::LocalStore(const Params & params)
                     (select id from Realisations where drvPath = ? and outputName = ?));
             )");
     }
+}
 
+
+AutoCloseFD LocalStore::openGCLock()
+{
     Path fnGCLock = stateDir + "/gc.lock";
-    state->fdGCLock = open(fnGCLock.c_str(), O_RDWR | O_CREAT | O_CLOEXEC, 0600);
-    if (!state->fdGCLock)
+    auto fdGCLock = open(fnGCLock.c_str(), O_RDWR | O_CREAT | O_CLOEXEC, 0600);
+    if (!fdGCLock)
         throw SysError("opening global GC lock '%1%'", fnGCLock);
+    return fdGCLock;
 }
 
 
@@ -1509,7 +1514,8 @@ bool LocalStore::verifyStore(bool checkContents, RepairFlag repair)
 
     /* Acquire the global GC lock to get a consistent snapshot of
        existing and valid paths. */
-    FdLock gcLock(_state.lock()->fdGCLock.get(), ltWrite, true, "waiting for the big garbage collector lock...");
+    auto fdGCLock = openGCLock();
+    FdLock gcLock(fdGCLock.get(), ltRead, true, "waiting for the big garbage collector lock...");
 
     StringSet store;
     for (auto & i : readDirectory(realStoreDir)) store.insert(i.name);
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 85c6c4495..12c057ec3 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -158,6 +158,8 @@ private:
 
     void findTempRoots(Roots & roots, bool censor);
 
+    AutoCloseFD openGCLock();
+
 public:
 
     Roots findRoots(bool censor) override;

From 262520fcfe2544a7278b6b5967d0d8b605fd89d9 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 20 Aug 2021 11:18:35 +0200
Subject: [PATCH 104/567] Use a thread per connection

---
 src/libstore/gc.cc  | 127 +++++++++++++++++++++-----------------------
 src/libutil/util.hh |  12 +++++
 2 files changed, 72 insertions(+), 67 deletions(-)

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index ff66c3938..bb76ee084 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -636,6 +636,7 @@ void LocalStore::removeUnusedLinks(const GCState & state)
 }
 
 
+
 void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 {
     GCState state(options, results);
@@ -674,83 +675,75 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
     shutdownPipe.create();
 
     std::thread serverThread([&]() {
-        std::map<int, std::pair<std::unique_ptr<AutoCloseFD>, std::string>> fdClients;
-        bool quit = false;
+        Sync<std::map<int, std::thread>> connections;
+        std::atomic_bool quit = false;
 
-        while (!quit) {
+        Finally cleanup([&]() {
+            debug("GC roots server shutting down");
+            while (true) {
+                auto item = remove_begin(*connections.lock());
+                if (!item) break;
+                auto & [fd, thread] = *item;
+                shutdown(fd, SHUT_RDWR);
+                thread.join();
+            }
+        });
+
+        while (true) {
             std::vector<struct pollfd> fds;
             fds.push_back({.fd = shutdownPipe.readSide.get(), .events = POLLIN});
             fds.push_back({.fd = fdServer.get(), .events = POLLIN});
-            for (auto & i : fdClients)
-                fds.push_back({.fd = i.first, .events = POLLIN});
             auto count = poll(fds.data(), fds.size(), -1);
             assert(count != -1);
 
-            for (auto & fd : fds) {
-                if (!fd.revents) continue;
-                if (fd.fd == shutdownPipe.readSide.get())
-                    /* Parent is asking us to quit. */
-                    quit = true;
-                else if (fd.fd == fdServer.get()) {
-                    /* Accept a new connection. */
-                    assert(fd.revents & POLLIN);
-                    auto fdClient = std::make_unique<AutoCloseFD>(accept(fdServer.get(), nullptr, nullptr));
-                    if (*fdClient) {
-                        auto fd = fdClient->get();
-                        fdClients.insert({fd, std::make_pair(std::move(fdClient), "")});
+            if (fds[0].revents)
+                /* Parent is asking us to quit. */
+                break;
+
+            if (fds[1].revents) {
+                /* Accept a new connection. */
+                assert(fds[1].revents & POLLIN);
+                AutoCloseFD fdClient = accept(fdServer.get(), nullptr, nullptr);
+                if (!fdClient) continue;
+
+                /* Process the connection in a separate thread. */
+                auto fdClient_ = fdClient.get();
+                std::thread clientThread([&, fdClient = std::move(fdClient)]() {
+                    Finally cleanup([&]() {
+                        connections.lock()->erase(fdClient.get());
+                    });
+
+                    while (true) {
+                        try {
+                            auto path = readLine(fdClient.get());
+                            auto storePath = maybeParseStorePath(path);
+                            if (storePath) {
+                                debug("got new GC root '%s'", path);
+                                auto hashPart = std::string(storePath->hashPart());
+                                auto shared(state.shared.lock());
+                                shared->tempRoots.insert(hashPart);
+                                /* If this path is currently being
+                                   deleted, then we have to wait until
+                                   deletion is finished to ensure that
+                                   the client doesn't start
+                                   re-creating it before we're
+                                   done. FIXME: ideally we would use a
+                                   FD for this so we don't block the
+                                   poll loop. */
+                                while (shared->pending == hashPart) {
+                                    debug("synchronising with deletion of path '%s'", path);
+                                    shared.wait(state.wakeup);
+                                }
+                            } else
+                                printError("received garbage instead of a root from client");
+                            writeFull(fdClient.get(), "1", false);
+                        } catch (Error &) { break; }
                     }
-                }
-                else {
-                    /* Receive data from a client. */
-                    auto fdClient = fdClients.find(fd.fd);
-                    assert(fdClient != fdClients.end());
-                    if (fd.revents & POLLIN) {
-                        char buf[16384];
-                        auto n = read(fd.fd, buf, sizeof(buf));
-                        if (n > 0) {
-                            fdClient->second.second.append(buf, n);
-                            /* Split the input into lines. */
-                            while (true) {
-                                auto p = fdClient->second.second.find('\n');
-                                if (p == std::string::npos) break;
-                                /* We got a full line. Send ack back
-                                   to the client. */
-                                auto path = fdClient->second.second.substr(0, p);
-                                fdClient->second.second = fdClient->second.second.substr(p + 1);
-                                auto storePath = maybeParseStorePath(path);
-                                if (storePath) {
-                                    debug("got new GC root '%s'", path);
-                                    auto hashPart = std::string(storePath->hashPart());
-                                    auto shared(state.shared.lock());
-                                    shared->tempRoots.insert(hashPart);
-                                    /* If this path is currently being
-                                       deleted, then we have to wait
-                                       until deletion is finished to
-                                       ensure that the client doesn't
-                                       start re-creating it before
-                                       we're done. FIXME: ideally we
-                                       would use a FD for this so we
-                                       don't block the poll loop. */
-                                    while (shared->pending == hashPart) {
-                                        debug("synchronising with deletion of path '%s'", path);
-                                        shared.wait(state.wakeup);
-                                    }
-                                } else
-                                    printError("received garbage instead of a root from client");
-                                // This could block, but meh.
-                                try {
-                                    writeFull(fd.fd, "1", false);
-                                } catch (SysError &) { }
-                            }
-                        } else if (n == 0)
-                            fdClients.erase(fdClient);
-                    } else
-                        fdClients.erase(fdClient);
-                }
+                });
+
+                connections.lock()->insert({fdClient_, std::move(clientThread)});
             }
         }
-
-        debug("GC roots server shut down");
     });
 
     Finally stopServer([&]() {
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 528d113db..76f80f7a4 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -511,6 +511,18 @@ std::optional<typename T::mapped_type> get(const T & map, const typename T::key_
 }
 
 
+/* Remove and return the first item from a container. */
+template <class T>
+std::optional<typename T::value_type> remove_begin(T & c)
+{
+    auto i = c.begin();
+    if (i == c.end()) return {};
+    auto v = std::move(*i);
+    c.erase(i);
+    return v;
+}
+
+
 template<typename T>
 class Callback;
 

From c24b9d68c564713309044c7c15983926556dc234 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 25 Aug 2021 14:05:25 +0200
Subject: [PATCH 105/567] tests/multiple-outputs.sh: Assert empty store

---
 tests/multiple-outputs.sh | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tests/multiple-outputs.sh b/tests/multiple-outputs.sh
index 0bca12b42..0d45ad35b 100644
--- a/tests/multiple-outputs.sh
+++ b/tests/multiple-outputs.sh
@@ -76,7 +76,10 @@ if nix-build multiple-outputs.nix -A cyclic --no-out-link; then
     exit 1
 fi
 
+# Do a GC. This should leave an empty store.
 echo "collecting garbage..."
 rm $TEST_ROOT/result*
 nix-store --gc --keep-derivations --keep-outputs
 nix-store --gc --print-roots
+rm -rf $NIX_STORE_DIR/.links
+rmdir $NIX_STORE_DIR

From dced45f146e5562b30ad8fb83260019a6f270ae5 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 17 Sep 2021 09:10:36 +0200
Subject: [PATCH 106/567] strcpy -> memcpy
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Jörg Thalheim <Mic92@users.noreply.github.com>
---
 src/libutil/util.cc | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 5945571b9..e99baf1fc 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1715,7 +1715,7 @@ void bind(int fd, const std::string & path)
             std::string base(baseNameOf(path));
             if (base.size() + 1 >= sizeof(addr.sun_path))
                 throw Error("socket path '%s' is too long", base);
-            strcpy(addr.sun_path, base.c_str());
+            memcpy(addr.sun_path, base.c_str(), base.size() + 1);
             if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) == -1)
                 throw SysError("cannot bind to socket '%s'", path);
             _exit(0);
@@ -1724,7 +1724,7 @@ void bind(int fd, const std::string & path)
         if (status != 0)
             throw Error("cannot bind to socket '%s'", path);
     } else {
-        strcpy(addr.sun_path, path.c_str());
+        memcpy(addr.sun_path, path.c_str(), path.size() + 1);
         if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) == -1)
             throw SysError("cannot bind to socket '%s'", path);
     }
@@ -1744,7 +1744,7 @@ void connect(int fd, const std::string & path)
             std::string base(baseNameOf(path));
             if (base.size() + 1 >= sizeof(addr.sun_path))
                 throw Error("socket path '%s' is too long", base);
-            strcpy(addr.sun_path, base.c_str());
+            memcpy(addr.sun_path, base.c_str(), base.size() + 1);
             if (connect(fd, (struct sockaddr *) &addr, sizeof(addr)) == -1)
                 throw SysError("cannot connect to socket at '%s'", path);
             _exit(0);
@@ -1753,7 +1753,7 @@ void connect(int fd, const std::string & path)
         if (status != 0)
             throw Error("cannot connect to socket at '%s'", path);
     } else {
-        strcpy(addr.sun_path, path.c_str());
+        memcpy(addr.sun_path, path.c_str(), path.size() + 1);
         if (connect(fd, (struct sockaddr *) &addr, sizeof(addr)) == -1)
             throw SysError("cannot connect to socket at '%s'", path);
     }

From 1785ba2980c9dd8274dd4bec5c0e46be02544b7e Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 8 Oct 2021 14:58:35 +0200
Subject: [PATCH 107/567] Simplify

---
 src/libstore/gc.cc          | 172 ++++++++++++++++++------------------
 src/libstore/local-store.hh |   4 +-
 2 files changed, 88 insertions(+), 88 deletions(-)

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index bb76ee084..969066092 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -479,21 +479,36 @@ struct LocalStore::GCState
 };
 
 
+void LocalStore::deleteFromStore(GCState & state, std::string_view baseName)
+{
+    Path path = storeDir + "/" + std::string(baseName);
+    Path realPath = realStoreDir + "/" + std::string(baseName);
+
+    printInfo("deleting '%1%'", path);
+
+    state.results.paths.insert(path);
+
+    uint64_t bytesFreed;
+    deletePath(realPath, bytesFreed);
+    state.results.bytesFreed += bytesFreed;
+
+    if (state.results.bytesFreed > state.options.maxFreed) {
+        printInfo("deleted more than %d bytes; stopping", state.options.maxFreed);
+        throw GCLimitReached();
+    }
+}
+
+
 bool LocalStore::tryToDelete(
     GCState & state,
     StorePathSet & visited,
-    const Path & path,
+    const StorePath & path,
     bool recursive)
 {
     checkInterrupt();
 
-    auto realPath = realStoreDir + "/" + std::string(baseNameOf(path));
-    if (realPath == linksDir) return false;
-
     //Activity act(*logger, lvlDebug, format("considering whether to delete '%1%'") % path);
 
-    auto storePath = maybeParseStorePath(path);
-
     /* Wake up any client waiting for deletion of this path to
        finish. */
     Finally releasePending([&]() {
@@ -502,89 +517,66 @@ bool LocalStore::tryToDelete(
         state.wakeup.notify_all();
     });
 
-    if (storePath) {
+    if (!visited.insert(path).second) return true;
 
-        if (!visited.insert(*storePath).second) return true;
+    if (state.alive.count(path)) return false;
 
-        if (state.alive.count(*storePath)) return false;
+    if (state.dead.count(path)) return true;
 
-        if (state.dead.count(*storePath)) return true;
-
-        if (state.roots.count(*storePath)) {
-            debug("cannot delete '%s' because it's a root", path);
-            state.alive.insert(*storePath);
-            return false;
-        }
-
-        if (isValidPath(*storePath)) {
-            StorePathSet incoming;
-
-            /* Don't delete this path if any of its referrers are alive. */
-            queryReferrers(*storePath, incoming);
-
-            /* If keep-derivations is set and this is a derivation, then
-               don't delete the derivation if any of the outputs are alive. */
-            if (state.gcKeepDerivations && storePath->isDerivation()) {
-                for (auto & [name, maybeOutPath] : queryPartialDerivationOutputMap(*storePath))
-                    if (maybeOutPath &&
-                        isValidPath(*maybeOutPath) &&
-                        queryPathInfo(*maybeOutPath)->deriver == *storePath)
-                        incoming.insert(*maybeOutPath);
-            }
-
-            /* If keep-outputs is set, then don't delete this path if there
-               are derivers of this path that are not garbage. */
-            if (state.gcKeepOutputs) {
-                auto derivers = queryValidDerivers(*storePath);
-                for (auto & i : derivers)
-                    incoming.insert(i);
-            }
-
-            for (auto & i : incoming)
-                if (i != *storePath
-                    && (recursive || state.options.pathsToDelete.count(i))
-                    && !tryToDelete(state, visited, printStorePath(i), recursive))
-                {
-                    state.alive.insert(*storePath);
-                    return false;
-                }
-        }
-
-        {
-            auto hashPart = std::string(storePath->hashPart());
-            auto shared(state.shared.lock());
-            if (shared->tempRoots.count(hashPart))
-                return false;
-            shared->pending = hashPart;
-        }
-
-        state.dead.insert(*storePath);
-
-        if (state.shouldDelete)
-            invalidatePathChecked(*storePath);
+    if (state.roots.count(path)) {
+        debug("cannot delete '%s' because it's a root", printStorePath(path));
+        state.alive.insert(path);
+        return false;
     }
 
+    if (isValidPath(path)) {
+        StorePathSet incoming;
+
+        /* Don't delete this path if any of its referrers are alive. */
+        queryReferrers(path, incoming);
+
+        /* If keep-derivations is set and this is a derivation, then
+           don't delete the derivation if any of the outputs are
+           alive. */
+        if (state.gcKeepDerivations && path.isDerivation()) {
+            for (auto & [name, maybeOutPath] : queryPartialDerivationOutputMap(path))
+                if (maybeOutPath &&
+                    isValidPath(*maybeOutPath) &&
+                    queryPathInfo(*maybeOutPath)->deriver == path)
+                    incoming.insert(*maybeOutPath);
+        }
+
+        /* If keep-outputs is set, then don't delete this path if
+           there are derivers of this path that are not garbage. */
+        if (state.gcKeepOutputs) {
+            auto derivers = queryValidDerivers(path);
+            for (auto & i : derivers)
+                incoming.insert(i);
+        }
+
+        for (auto & i : incoming)
+            if (i != path
+                && (recursive || state.options.pathsToDelete.count(i))
+                && !tryToDelete(state, visited, i, recursive))
+            {
+                state.alive.insert(path);
+                return false;
+            }
+    }
+
+    {
+        auto hashPart = std::string(path.hashPart());
+        auto shared(state.shared.lock());
+        if (shared->tempRoots.count(hashPart))
+            return false;
+        shared->pending = hashPart;
+    }
+
+    state.dead.insert(path);
+
     if (state.shouldDelete) {
-        Path realPath = realStoreDir + "/" + std::string(baseNameOf(path));
-
-        struct stat st;
-        if (lstat(realPath.c_str(), &st)) {
-            if (errno == ENOENT) return true;
-            throw SysError("getting status of %1%", realPath);
-        }
-
-        printInfo("deleting '%1%'", path);
-
-        state.results.paths.insert(path);
-
-        uint64_t bytesFreed;
-        deletePath(realPath, bytesFreed);
-        state.results.bytesFreed += bytesFreed;
-
-        if (state.results.bytesFreed > state.options.maxFreed) {
-            printInfo("deleted more than %d bytes; stopping", state.options.maxFreed);
-            throw GCLimitReached();
-        }
+        invalidatePathChecked(path);
+        deleteFromStore(state, path.to_string());
     }
 
     return true;
@@ -777,7 +769,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 
         for (auto & i : options.pathsToDelete) {
             StorePathSet visited;
-            if (!tryToDelete(state, visited, printStorePath(i), false))
+            if (!tryToDelete(state, visited, i, false))
                 throw Error(
                     "cannot delete path '%1%' since it is still alive. "
                     "To find out why, use: "
@@ -799,14 +791,20 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
             /* Read the store and delete all paths that are invalid or
                unreachable. We don't use readDirectory() here so that
                GCing can start faster. */
+            auto linksName = baseNameOf(linksDir);
             Paths entries;
             struct dirent * dirent;
             while (errno = 0, dirent = readdir(dir.get())) {
                 checkInterrupt();
                 string name = dirent->d_name;
-                if (name == "." || name == "..") continue;
-                StorePathSet visited;
-                tryToDelete(state, visited, storeDir + "/" + name, true);
+                if (name == "." || name == ".." || name == linksName) continue;
+
+                if (auto storePath = maybeParseStorePath(storeDir + "/" + name)) {
+                    StorePathSet visited;
+                    tryToDelete(state, visited, *storePath, true);
+                } else
+                    deleteFromStore(state, name);
+
             }
         } catch (GCLimitReached & e) {
         }
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 12c057ec3..08bbc1a7d 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -243,9 +243,11 @@ private:
     bool tryToDelete(
         GCState & state,
         StorePathSet & visited,
-        const Path & path,
+        const StorePath & path,
         bool recursive);
 
+    void deleteFromStore(GCState & state, std::string_view baseName);
+
     void findRoots(const Path & path, unsigned char type, Roots & roots);
 
     void findRootsNoTemp(Roots & roots, bool censor);

From e31a48366f19d5fa452df6273e817a4ea5516e50 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 8 Oct 2021 16:57:25 +0200
Subject: [PATCH 108/567] Fix referrers test

This test broke the assumption that the hash parts of store paths are
unique.
---
 tests/referrers.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/referrers.sh b/tests/referrers.sh
index 81323c280..7ede707b8 100644
--- a/tests/referrers.sh
+++ b/tests/referrers.sh
@@ -14,9 +14,9 @@ echo "making registration..."
 
 set +x
 for ((n = 0; n < $max; n++)); do
-    storePath=$NIX_STORE_DIR/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-$n
+    storePath=$NIX_STORE_DIR/$(printf "%05d\n" $n)aaaaaaaaaaaaaaaaaaaaaaaaaaa-$n
     echo -n > $storePath
-    ref2=$NIX_STORE_DIR/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-$((n+1))
+    ref2=$NIX_STORE_DIR/$(printf "%05d\n" $((n+1)))aaaaaaaaaaaaaaaaaaaaaaaaaaa-$((n+1))
     if test $((n+1)) = $max; then
         ref2=$reference
     fi

From 35c98a59c5f09d8ca376ac809e87d14ff2fcbde1 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 8 Oct 2021 16:58:19 +0200
Subject: [PATCH 109/567] Fix GC when there are cycles in the referrers graph

(where "referrers" includes the reverse of derivation outputs and
derivers). Now we do a full traversal to look if we can reach any
root. If not, all paths reached can be deleted.
---
 src/libstore/gc.cc          | 74 +++++++++++++++++++++----------------
 src/libstore/local-store.hh |  5 +--
 2 files changed, 45 insertions(+), 34 deletions(-)

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 969066092..4123a90be 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -499,34 +499,29 @@ void LocalStore::deleteFromStore(GCState & state, std::string_view baseName)
 }
 
 
-bool LocalStore::tryToDelete(
+bool LocalStore::canReachRoot(
     GCState & state,
     StorePathSet & visited,
-    const StorePath & path,
-    bool recursive)
+    const StorePath & path)
 {
     checkInterrupt();
 
     //Activity act(*logger, lvlDebug, format("considering whether to delete '%1%'") % path);
 
-    /* Wake up any client waiting for deletion of this path to
-       finish. */
-    Finally releasePending([&]() {
-        auto shared(state.shared.lock());
-        shared->pending.reset();
-        state.wakeup.notify_all();
-    });
+    if (state.options.action == GCOptions::gcDeleteSpecific
+        && !state.options.pathsToDelete.count(path))
+        return true;
 
-    if (!visited.insert(path).second) return true;
+    if (!visited.insert(path).second) return false;
 
-    if (state.alive.count(path)) return false;
+    if (state.alive.count(path)) return true;
 
-    if (state.dead.count(path)) return true;
+    if (state.dead.count(path)) return false;
 
     if (state.roots.count(path)) {
         debug("cannot delete '%s' because it's a root", printStorePath(path));
         state.alive.insert(path);
-        return false;
+        return true;
     }
 
     if (isValidPath(path)) {
@@ -555,12 +550,9 @@ bool LocalStore::tryToDelete(
         }
 
         for (auto & i : incoming)
-            if (i != path
-                && (recursive || state.options.pathsToDelete.count(i))
-                && !tryToDelete(state, visited, i, recursive))
-            {
+            if (i != path && canReachRoot(state, visited, i)) {
                 state.alive.insert(path);
-                return false;
+                return true;
             }
     }
 
@@ -568,18 +560,11 @@ bool LocalStore::tryToDelete(
         auto hashPart = std::string(path.hashPart());
         auto shared(state.shared.lock());
         if (shared->tempRoots.count(hashPart))
-            return false;
+            return true;
         shared->pending = hashPart;
     }
 
-    state.dead.insert(path);
-
-    if (state.shouldDelete) {
-        invalidatePathChecked(path);
-        deleteFromStore(state, path.to_string());
-    }
-
-    return true;
+    return false;
 }
 
 
@@ -628,7 +613,6 @@ void LocalStore::removeUnusedLinks(const GCState & state)
 }
 
 
-
 void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 {
     GCState state(options, results);
@@ -769,12 +753,21 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 
         for (auto & i : options.pathsToDelete) {
             StorePathSet visited;
-            if (!tryToDelete(state, visited, i, false))
+
+            if (canReachRoot(state, visited, i))
                 throw Error(
                     "cannot delete path '%1%' since it is still alive. "
                     "To find out why, use: "
                     "nix-store --query --roots",
                     printStorePath(i));
+
+            auto sorted = topoSortPaths(visited);
+            for (auto & path : sorted) {
+                if (state.dead.count(path)) continue;
+                invalidatePathChecked(path);
+                deleteFromStore(state, path.to_string());
+                state.dead.insert(path);
+            }
         }
 
     } else if (options.maxFreed > 0) {
@@ -801,7 +794,26 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 
                 if (auto storePath = maybeParseStorePath(storeDir + "/" + name)) {
                     StorePathSet visited;
-                    tryToDelete(state, visited, *storePath, true);
+
+                    /* Wake up any GC client waiting for deletion of
+                       the paths in 'visited' to finish. */
+                    Finally releasePending([&]() {
+                        auto shared(state.shared.lock());
+                        shared->pending.reset();
+                        state.wakeup.notify_all();
+                    });
+
+                    if (!canReachRoot(state, visited, *storePath)) {
+                        auto sorted = topoSortPaths(visited);
+                        for (auto & path : sorted) {
+                            if (state.dead.count(path)) continue;
+                            if (state.shouldDelete) {
+                                invalidatePathChecked(path);
+                                deleteFromStore(state, path.to_string());
+                            }
+                            state.dead.insert(path);
+                        }
+                    }
                 } else
                     deleteFromStore(state, name);
 
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 08bbc1a7d..8629e1528 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -240,11 +240,10 @@ private:
 
     struct GCState;
 
-    bool tryToDelete(
+    bool canReachRoot(
         GCState & state,
         StorePathSet & visited,
-        const StorePath & path,
-        bool recursive);
+        const StorePath & path);
 
     void deleteFromStore(GCState & state, std::string_view baseName);
 

From eae29b0385981a2a1cc792bdb6551d558f4fa6d3 Mon Sep 17 00:00:00 2001
From: kvtb <76634406+kvtb@users.noreply.github.com>
Date: Wed, 13 Oct 2021 18:03:33 +0000
Subject: [PATCH 110/567] fix build with gcc11

---
 src/libutil/ref.hh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libutil/ref.hh b/src/libutil/ref.hh
index d6bf53bb8..347b81f73 100644
--- a/src/libutil/ref.hh
+++ b/src/libutil/ref.hh
@@ -17,7 +17,7 @@ private:
 
 public:
 
-    ref<T>(const ref<T> & r)
+    ref(const ref<T> & r)
         : p(r.p)
     { }
 

From 09b14ea97a7883114baa5878da163d9e403396d6 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 14 Oct 2021 10:04:13 +0200
Subject: [PATCH 111/567] Cleanup

---
 src/libstore/misc.cc | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/libstore/misc.cc b/src/libstore/misc.cc
index f184dd857..32786e963 100644
--- a/src/libstore/misc.cc
+++ b/src/libstore/misc.cc
@@ -239,12 +239,11 @@ StorePaths Store::topoSortPaths(const StorePathSet & paths)
 {
     return topoSort(paths,
         {[&](const StorePath & path) {
-            StorePathSet references;
             try {
-                references = queryPathInfo(path)->references;
+                return queryPathInfo(path)->references;
             } catch (InvalidPath &) {
+                return StorePathSet();
             }
-            return references;
         }},
         {[&](const StorePath & path, const StorePath & parent) {
             return BuildError(

From eab934cb2a23595a7ac7c8a72373cd8096b606a9 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 14 Oct 2021 12:31:21 +0200
Subject: [PATCH 112/567] Make the canReachRoots() traversal non-recursive

---
 src/libstore/gc.cc          | 210 ++++++++++++++++++------------------
 src/libstore/local-store.hh |   5 -
 src/libutil/util.hh         |  11 ++
 3 files changed, 115 insertions(+), 111 deletions(-)

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 4123a90be..8a34f0c9b 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -499,75 +499,6 @@ void LocalStore::deleteFromStore(GCState & state, std::string_view baseName)
 }
 
 
-bool LocalStore::canReachRoot(
-    GCState & state,
-    StorePathSet & visited,
-    const StorePath & path)
-{
-    checkInterrupt();
-
-    //Activity act(*logger, lvlDebug, format("considering whether to delete '%1%'") % path);
-
-    if (state.options.action == GCOptions::gcDeleteSpecific
-        && !state.options.pathsToDelete.count(path))
-        return true;
-
-    if (!visited.insert(path).second) return false;
-
-    if (state.alive.count(path)) return true;
-
-    if (state.dead.count(path)) return false;
-
-    if (state.roots.count(path)) {
-        debug("cannot delete '%s' because it's a root", printStorePath(path));
-        state.alive.insert(path);
-        return true;
-    }
-
-    if (isValidPath(path)) {
-        StorePathSet incoming;
-
-        /* Don't delete this path if any of its referrers are alive. */
-        queryReferrers(path, incoming);
-
-        /* If keep-derivations is set and this is a derivation, then
-           don't delete the derivation if any of the outputs are
-           alive. */
-        if (state.gcKeepDerivations && path.isDerivation()) {
-            for (auto & [name, maybeOutPath] : queryPartialDerivationOutputMap(path))
-                if (maybeOutPath &&
-                    isValidPath(*maybeOutPath) &&
-                    queryPathInfo(*maybeOutPath)->deriver == path)
-                    incoming.insert(*maybeOutPath);
-        }
-
-        /* If keep-outputs is set, then don't delete this path if
-           there are derivers of this path that are not garbage. */
-        if (state.gcKeepOutputs) {
-            auto derivers = queryValidDerivers(path);
-            for (auto & i : derivers)
-                incoming.insert(i);
-        }
-
-        for (auto & i : incoming)
-            if (i != path && canReachRoot(state, visited, i)) {
-                state.alive.insert(path);
-                return true;
-            }
-    }
-
-    {
-        auto hashPart = std::string(path.hashPart());
-        auto shared(state.shared.lock());
-        if (shared->tempRoots.count(hashPart))
-            return true;
-        shared->pending = hashPart;
-    }
-
-    return false;
-}
-
-
 /* Unlink all files in /nix/store/.links that have a link count of 1,
    which indicates that there are no other links and so they can be
    safely deleted.  FIXME: race condition with optimisePath(): we
@@ -746,28 +677,115 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
         state.roots.insert(root.first);
     }
 
-    /* Now either delete all garbage paths, or just the specified
-       paths (for gcDeleteSpecific). */
+    /* Helper function that visits all paths reachable from `start`
+       via the referrers edges and optionally derivers and derivation
+       output edges. If any of those paths is a root, then we cannot
+       delete this path. */
+    auto deleteReferrersClosure = [&](const StorePath & start) {
+        StorePathSet visited;
+        std::queue<StorePath> todo;
 
+        /* Wake up any GC client waiting for deletion of the paths in
+           'visited' to finish. */
+        Finally releasePending([&]() {
+            auto shared(state.shared.lock());
+            shared->pending.reset();
+            state.wakeup.notify_all();
+        });
+
+        auto enqueue = [&](const StorePath & path) {
+            if (visited.insert(path).second)
+                todo.push(path);
+        };
+
+        enqueue(start);
+
+        while (auto path = pop(todo)) {
+            checkInterrupt();
+
+            /* Bail out if we've previously discovered that this path
+               is alive. */
+            if (state.alive.count(*path)) {
+                state.alive.insert(start);
+                return;
+            }
+
+            /* If we've previously deleted this path, we don't have to
+               handle it again. */
+            if (state.dead.count(*path)) continue;
+
+            /* If this is a root, bail out. */
+            if (state.roots.count(*path)) {
+                debug("cannot delete '%s' because it's a root", printStorePath(*path));
+                state.alive.insert(*path);
+                state.alive.insert(start);
+                return;
+            }
+
+            if (state.options.action == GCOptions::gcDeleteSpecific
+                && !state.options.pathsToDelete.count(*path))
+                return;
+
+            {
+                auto hashPart = std::string(path->hashPart());
+                auto shared(state.shared.lock());
+                if (shared->tempRoots.count(hashPart)) {
+                    debug("cannot delete '%s' because it's a temporary root", printStorePath(*path));
+                    state.alive.insert(*path);
+                    state.alive.insert(start);
+                    return;
+                }
+                shared->pending = hashPart;
+            }
+
+            if (isValidPath(*path)) {
+
+                /* Visit the referrers of this path. */
+                StorePathSet referrers;
+                queryReferrers(*path, referrers);
+                for (auto & p : referrers)
+                    enqueue(p);
+
+                /* If keep-derivations is set and this is a
+                   derivation, then visit the derivation outputs. */
+                if (state.gcKeepDerivations && path->isDerivation()) {
+                    for (auto & [name, maybeOutPath] : queryPartialDerivationOutputMap(*path))
+                        if (maybeOutPath &&
+                            isValidPath(*maybeOutPath) &&
+                            queryPathInfo(*maybeOutPath)->deriver == *path)
+                            enqueue(*maybeOutPath);
+                }
+
+                /* If keep-outputs is set, then visit the derivers. */
+                if (state.gcKeepOutputs) {
+                    auto derivers = queryValidDerivers(*path);
+                    for (auto & i : derivers)
+                        enqueue(i);
+                }
+            }
+        }
+
+        for (auto & path : topoSortPaths(visited)) {
+            if (!state.dead.insert(path).second) continue;
+            if (state.shouldDelete) {
+                invalidatePathChecked(path);
+                deleteFromStore(state, path.to_string());
+            }
+        }
+    };
+
+    /* Either delete all garbage paths, or just the specified
+       paths (for gcDeleteSpecific). */
     if (options.action == GCOptions::gcDeleteSpecific) {
 
         for (auto & i : options.pathsToDelete) {
-            StorePathSet visited;
-
-            if (canReachRoot(state, visited, i))
+            deleteReferrersClosure(i);
+            if (!state.dead.count(i))
                 throw Error(
-                    "cannot delete path '%1%' since it is still alive. "
+                    "Cannot delete path '%1%' since it is still alive. "
                     "To find out why, use: "
                     "nix-store --query --roots",
                     printStorePath(i));
-
-            auto sorted = topoSortPaths(visited);
-            for (auto & path : sorted) {
-                if (state.dead.count(path)) continue;
-                invalidatePathChecked(path);
-                deleteFromStore(state, path.to_string());
-                state.dead.insert(path);
-            }
         }
 
     } else if (options.maxFreed > 0) {
@@ -792,29 +810,9 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
                 string name = dirent->d_name;
                 if (name == "." || name == ".." || name == linksName) continue;
 
-                if (auto storePath = maybeParseStorePath(storeDir + "/" + name)) {
-                    StorePathSet visited;
-
-                    /* Wake up any GC client waiting for deletion of
-                       the paths in 'visited' to finish. */
-                    Finally releasePending([&]() {
-                        auto shared(state.shared.lock());
-                        shared->pending.reset();
-                        state.wakeup.notify_all();
-                    });
-
-                    if (!canReachRoot(state, visited, *storePath)) {
-                        auto sorted = topoSortPaths(visited);
-                        for (auto & path : sorted) {
-                            if (state.dead.count(path)) continue;
-                            if (state.shouldDelete) {
-                                invalidatePathChecked(path);
-                                deleteFromStore(state, path.to_string());
-                            }
-                            state.dead.insert(path);
-                        }
-                    }
-                } else
+                if (auto storePath = maybeParseStorePath(storeDir + "/" + name))
+                    deleteReferrersClosure(*storePath);
+                else
                     deleteFromStore(state, name);
 
             }
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 8629e1528..21a4e60cf 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -240,11 +240,6 @@ private:
 
     struct GCState;
 
-    bool canReachRoot(
-        GCState & state,
-        StorePathSet & visited,
-        const StorePath & path);
-
     void deleteFromStore(GCState & state, std::string_view baseName);
 
     void findRoots(const Path & path, unsigned char type, Roots & roots);
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 76f80f7a4..485ff4153 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -523,6 +523,17 @@ std::optional<typename T::value_type> remove_begin(T & c)
 }
 
 
+/* Remove and return the first item from a container. */
+template <class T>
+std::optional<typename T::value_type> pop(T & c)
+{
+    if (c.empty()) return {};
+    auto v = std::move(c.front());
+    c.pop();
+    return v;
+}
+
+
 template<typename T>
 class Callback;
 

From 0be8cc1466f317e33977590510bac4b18471f0ce Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 14 Oct 2021 13:28:22 +0200
Subject: [PATCH 113/567] pathInfoCache: Use the entire base name as the cache
 key

This fixes a bug in the garbage collector where if a path
/nix/store/abcd-foo is valid, but we do a
isValidPath("/nix/store/abcd-foo.lock") first, then a negative entry
for /nix/store/abcd is added to pathInfoCache, so /nix/store/abcd-foo
is subsequently considered invalid and deleted.
---
 src/libstore/binary-cache-store.cc |  8 ++++----
 src/libstore/local-store.cc        |  4 ++--
 src/libstore/store-api.cc          | 26 ++++++++++----------------
 src/libstore/store-api.hh          |  1 -
 tests/gc.sh                        | 11 +++++++++++
 5 files changed, 27 insertions(+), 23 deletions(-)

diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index 8fce94264..943132754 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -111,15 +111,15 @@ void BinaryCacheStore::writeNarInfo(ref<NarInfo> narInfo)
 
     upsertFile(narInfoFile, narInfo->to_string(*this), "text/x-nix-narinfo");
 
-    std::string hashPart(narInfo->path.hashPart());
-
     {
         auto state_(state.lock());
-        state_->pathInfoCache.upsert(hashPart, PathInfoCacheValue { .value = std::shared_ptr<NarInfo>(narInfo) });
+        state_->pathInfoCache.upsert(
+            std::string(narInfo->path.to_string()),
+            PathInfoCacheValue { .value = std::shared_ptr<NarInfo>(narInfo) });
     }
 
     if (diskCache)
-        diskCache->upsertNarInfo(getUri(), hashPart, std::shared_ptr<NarInfo>(narInfo));
+        diskCache->upsertNarInfo(getUri(), std::string(narInfo->path.hashPart()), std::shared_ptr<NarInfo>(narInfo));
 }
 
 AutoCloseFD openFile(const Path & path)
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 0e6556e11..c853e9a9c 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -834,7 +834,7 @@ uint64_t LocalStore::addValidPath(State & state,
 
     {
         auto state_(Store::state.lock());
-        state_->pathInfoCache.upsert(std::string(info.path.hashPart()),
+        state_->pathInfoCache.upsert(std::string(info.path.to_string()),
             PathInfoCacheValue{ .value = std::make_shared<const ValidPathInfo>(info) });
     }
 
@@ -1207,7 +1207,7 @@ void LocalStore::invalidatePath(State & state, const StorePath & path)
 
     {
         auto state_(Store::state.lock());
-        state_->pathInfoCache.erase(std::string(path.hashPart()));
+        state_->pathInfoCache.erase(std::string(path.to_string()));
     }
 }
 
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index b5ff3dccf..10aa1035e 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -414,11 +414,9 @@ StorePathSet Store::queryDerivationOutputs(const StorePath & path)
 
 bool Store::isValidPath(const StorePath & storePath)
 {
-    std::string hashPart(storePath.hashPart());
-
     {
         auto state_(state.lock());
-        auto res = state_->pathInfoCache.get(hashPart);
+        auto res = state_->pathInfoCache.get(std::string(storePath.to_string()));
         if (res && res->isKnownNow()) {
             stats.narInfoReadAverted++;
             return res->didExist();
@@ -426,11 +424,11 @@ bool Store::isValidPath(const StorePath & storePath)
     }
 
     if (diskCache) {
-        auto res = diskCache->lookupNarInfo(getUri(), hashPart);
+        auto res = diskCache->lookupNarInfo(getUri(), std::string(storePath.hashPart()));
         if (res.first != NarInfoDiskCache::oUnknown) {
             stats.narInfoReadAverted++;
             auto state_(state.lock());
-            state_->pathInfoCache.upsert(hashPart,
+            state_->pathInfoCache.upsert(std::string(storePath.to_string()),
                 res.first == NarInfoDiskCache::oInvalid ? PathInfoCacheValue{} : PathInfoCacheValue { .value = res.second });
             return res.first == NarInfoDiskCache::oValid;
         }
@@ -440,7 +438,7 @@ bool Store::isValidPath(const StorePath & storePath)
 
     if (diskCache && !valid)
         // FIXME: handle valid = true case.
-        diskCache->upsertNarInfo(getUri(), hashPart, 0);
+        diskCache->upsertNarInfo(getUri(), std::string(storePath.hashPart()), 0);
 
     return valid;
 }
@@ -487,13 +485,11 @@ static bool goodStorePath(const StorePath & expected, const StorePath & actual)
 void Store::queryPathInfo(const StorePath & storePath,
     Callback<ref<const ValidPathInfo>> callback) noexcept
 {
-    std::string hashPart;
+    auto hashPart = std::string(storePath.hashPart());
 
     try {
-        hashPart = storePath.hashPart();
-
         {
-            auto res = state.lock()->pathInfoCache.get(hashPart);
+            auto res = state.lock()->pathInfoCache.get(std::string(storePath.to_string()));
             if (res && res->isKnownNow()) {
                 stats.narInfoReadAverted++;
                 if (!res->didExist())
@@ -508,7 +504,7 @@ void Store::queryPathInfo(const StorePath & storePath,
                 stats.narInfoReadAverted++;
                 {
                     auto state_(state.lock());
-                    state_->pathInfoCache.upsert(hashPart,
+                    state_->pathInfoCache.upsert(std::string(storePath.to_string()),
                         res.first == NarInfoDiskCache::oInvalid ? PathInfoCacheValue{} : PathInfoCacheValue{ .value = res.second });
                     if (res.first == NarInfoDiskCache::oInvalid ||
                         !goodStorePath(storePath, res.second->path))
@@ -523,7 +519,7 @@ void Store::queryPathInfo(const StorePath & storePath,
     auto callbackPtr = std::make_shared<decltype(callback)>(std::move(callback));
 
     queryPathInfoUncached(storePath,
-        {[this, storePathS{printStorePath(storePath)}, hashPart, callbackPtr](std::future<std::shared_ptr<const ValidPathInfo>> fut) {
+        {[this, storePath, hashPart, callbackPtr](std::future<std::shared_ptr<const ValidPathInfo>> fut) {
 
             try {
                 auto info = fut.get();
@@ -533,14 +529,12 @@ void Store::queryPathInfo(const StorePath & storePath,
 
                 {
                     auto state_(state.lock());
-                    state_->pathInfoCache.upsert(hashPart, PathInfoCacheValue { .value = info });
+                    state_->pathInfoCache.upsert(std::string(storePath.to_string()), PathInfoCacheValue { .value = info });
                 }
 
-                auto storePath = parseStorePath(storePathS);
-
                 if (!info || !goodStorePath(storePath, info->path)) {
                     stats.narInfoMissing++;
-                    throw InvalidPath("path '%s' is not valid", storePathS);
+                    throw InvalidPath("path '%s' is not valid", printStorePath(storePath));
                 }
 
                 (*callbackPtr)(ref<const ValidPathInfo>(info));
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 35461b76d..7d02340df 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -232,7 +232,6 @@ protected:
 
     struct State
     {
-        // FIXME: fix key
         LRUCache<std::string, PathInfoCacheValue> pathInfoCache;
     };
 
diff --git a/tests/gc.sh b/tests/gc.sh
index cf0e2c32d..33d627dae 100644
--- a/tests/gc.sh
+++ b/tests/gc.sh
@@ -1,5 +1,7 @@
 source common.sh
 
+clearStore
+
 drvPath=$(nix-instantiate dependencies.nix)
 outPath=$(nix-store -rvv "$drvPath")
 
@@ -23,6 +25,11 @@ test -e $inUse
 if nix-store --delete $outPath; then false; fi
 test -e $outPath
 
+for i in $NIX_STORE_DIR/*; do
+    touch $i.lock
+    touch $i.chroot
+done
+
 nix-collect-garbage
 
 # Check that the root and its dependencies haven't been deleted.
@@ -38,3 +45,7 @@ nix-collect-garbage
 
 # Check that the output has been GC'd.
 if test -e $outPath/foobar; then false; fi
+
+# Check that the store is empty.
+rmdir $NIX_STORE_DIR/.links
+rmdir $NIX_STORE_DIR

From 0317ffdad3b2137d35e501b38155437e2ec5d0cd Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 14 Oct 2021 13:34:48 +0200
Subject: [PATCH 114/567] Move deleteFromStore()

---
 src/libstore/gc.cc          | 49 +++++++++++++++++++------------------
 src/libstore/local-store.hh |  2 --
 2 files changed, 25 insertions(+), 26 deletions(-)

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 8a34f0c9b..aa0087118 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -479,26 +479,6 @@ struct LocalStore::GCState
 };
 
 
-void LocalStore::deleteFromStore(GCState & state, std::string_view baseName)
-{
-    Path path = storeDir + "/" + std::string(baseName);
-    Path realPath = realStoreDir + "/" + std::string(baseName);
-
-    printInfo("deleting '%1%'", path);
-
-    state.results.paths.insert(path);
-
-    uint64_t bytesFreed;
-    deletePath(realPath, bytesFreed);
-    state.results.bytesFreed += bytesFreed;
-
-    if (state.results.bytesFreed > state.options.maxFreed) {
-        printInfo("deleted more than %d bytes; stopping", state.options.maxFreed);
-        throw GCLimitReached();
-    }
-}
-
-
 /* Unlink all files in /nix/store/.links that have a link count of 1,
    which indicates that there are no other links and so they can be
    safely deleted.  FIXME: race condition with optimisePath(): we
@@ -677,10 +657,31 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
         state.roots.insert(root.first);
     }
 
+    /* Helper function that deletes a path from the store and throws
+       GCLimitReached if we've deleted enough garbage. */
+    auto deleteFromStore = [&](std::string_view baseName)
+    {
+        Path path = storeDir + "/" + std::string(baseName);
+        Path realPath = realStoreDir + "/" + std::string(baseName);
+
+        printInfo("deleting '%1%'", path);
+
+        state.results.paths.insert(path);
+
+        uint64_t bytesFreed;
+        deletePath(realPath, bytesFreed);
+        state.results.bytesFreed += bytesFreed;
+
+        if (state.results.bytesFreed > state.options.maxFreed) {
+            printInfo("deleted more than %d bytes; stopping", state.options.maxFreed);
+            throw GCLimitReached();
+        }
+    };
+
     /* Helper function that visits all paths reachable from `start`
        via the referrers edges and optionally derivers and derivation
-       output edges. If any of those paths is a root, then we cannot
-       delete this path. */
+       output edges. If none of those paths are roots, then all
+       visited paths are garbage and are deleted. */
     auto deleteReferrersClosure = [&](const StorePath & start) {
         StorePathSet visited;
         std::queue<StorePath> todo;
@@ -769,7 +770,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
             if (!state.dead.insert(path).second) continue;
             if (state.shouldDelete) {
                 invalidatePathChecked(path);
-                deleteFromStore(state, path.to_string());
+                deleteFromStore(path.to_string());
             }
         }
     };
@@ -813,7 +814,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
                 if (auto storePath = maybeParseStorePath(storeDir + "/" + name))
                     deleteReferrersClosure(*storePath);
                 else
-                    deleteFromStore(state, name);
+                    deleteFromStore(name);
 
             }
         } catch (GCLimitReached & e) {
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 21a4e60cf..15475f402 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -240,8 +240,6 @@ private:
 
     struct GCState;
 
-    void deleteFromStore(GCState & state, std::string_view baseName);
-
     void findRoots(const Path & path, unsigned char type, Roots & roots);
 
     void findRootsNoTemp(Roots & roots, bool censor);

From 0154fa30cf2a6da63e69f7488cec9e289f57cc15 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 14 Oct 2021 13:52:49 +0200
Subject: [PATCH 115/567] Remove GCState

---
 src/libstore/gc.cc          | 196 ++++++++++++++++--------------------
 src/libstore/local-store.hh |   4 -
 2 files changed, 87 insertions(+), 113 deletions(-)

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index aa0087118..800a3fd19 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -448,16 +448,13 @@ void LocalStore::findRuntimeRoots(Roots & roots, bool censor)
 struct GCLimitReached { };
 
 
-struct LocalStore::GCState
+void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 {
-    const GCOptions & options;
-    GCResults & results;
-    StorePathSet roots;
-    StorePathSet dead;
-    StorePathSet alive;
-    bool gcKeepOutputs;
-    bool gcKeepDerivations;
-    bool shouldDelete;
+    bool shouldDelete = options.action == GCOptions::gcDeleteDead || options.action == GCOptions::gcDeleteSpecific;
+    bool gcKeepOutputs = settings.gcKeepOutputs;
+    bool gcKeepDerivations = settings.gcKeepDerivations;
+
+    StorePathSet roots, dead, alive;
 
     struct Shared
     {
@@ -470,81 +467,23 @@ struct LocalStore::GCState
         std::optional<std::string> pending;
     };
 
-    Sync<Shared> shared;
+    Sync<Shared> _shared;
 
     std::condition_variable wakeup;
 
-    GCState(const GCOptions & options, GCResults & results)
-        : options(options), results(results) { }
-};
-
-
-/* Unlink all files in /nix/store/.links that have a link count of 1,
-   which indicates that there are no other links and so they can be
-   safely deleted.  FIXME: race condition with optimisePath(): we
-   might see a link count of 1 just before optimisePath() increases
-   the link count. */
-void LocalStore::removeUnusedLinks(const GCState & state)
-{
-    AutoCloseDir dir(opendir(linksDir.c_str()));
-    if (!dir) throw SysError("opening directory '%1%'", linksDir);
-
-    int64_t actualSize = 0, unsharedSize = 0;
-
-    struct dirent * dirent;
-    while (errno = 0, dirent = readdir(dir.get())) {
-        checkInterrupt();
-        string name = dirent->d_name;
-        if (name == "." || name == "..") continue;
-        Path path = linksDir + "/" + name;
-
-        auto st = lstat(path);
-
-        if (st.st_nlink != 1) {
-            actualSize += st.st_size;
-            unsharedSize += (st.st_nlink - 1) * st.st_size;
-            continue;
-        }
-
-        printMsg(lvlTalkative, format("deleting unused link '%1%'") % path);
-
-        if (unlink(path.c_str()) == -1)
-            throw SysError("deleting '%1%'", path);
-
-        state.results.bytesFreed += st.st_size;
-    }
-
-    struct stat st;
-    if (stat(linksDir.c_str(), &st) == -1)
-        throw SysError("statting '%1%'", linksDir);
-    int64_t overhead = st.st_blocks * 512ULL;
-
-    printInfo("note: currently hard linking saves %.2f MiB",
-        ((unsharedSize - actualSize - overhead) / (1024.0 * 1024.0)));
-}
-
-
-void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
-{
-    GCState state(options, results);
-    state.gcKeepOutputs = settings.gcKeepOutputs;
-    state.gcKeepDerivations = settings.gcKeepDerivations;
-
     /* Using `--ignore-liveness' with `--delete' can have unintended
        consequences if `keep-outputs' or `keep-derivations' are true
        (the garbage collector will recurse into deleting the outputs
        or derivers, respectively).  So disable them. */
     if (options.action == GCOptions::gcDeleteSpecific && options.ignoreLiveness) {
-        state.gcKeepOutputs = false;
-        state.gcKeepDerivations = false;
+        gcKeepOutputs = false;
+        gcKeepDerivations = false;
     }
 
-    state.shouldDelete = options.action == GCOptions::gcDeleteDead || options.action == GCOptions::gcDeleteSpecific;
-
-    if (state.shouldDelete)
+    if (shouldDelete)
         deletePath(reservedPath);
 
-    /* Acquire the global GC root. Note: we don't use state->fdGCLock
+    /* Acquire the global GC root. Note: we don't use fdGCLock
        here because then in auto-gc mode, another thread could
        downgrade our exclusive lock. */
     auto fdGCLock = openGCLock();
@@ -607,7 +546,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
                             if (storePath) {
                                 debug("got new GC root '%s'", path);
                                 auto hashPart = std::string(storePath->hashPart());
-                                auto shared(state.shared.lock());
+                                auto shared(_shared.lock());
                                 shared->tempRoots.insert(hashPart);
                                 /* If this path is currently being
                                    deleted, then we have to wait until
@@ -619,7 +558,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
                                    poll loop. */
                                 while (shared->pending == hashPart) {
                                     debug("synchronising with deletion of path '%s'", path);
-                                    shared.wait(state.wakeup);
+                                    shared.wait(wakeup);
                                 }
                             } else
                                 printError("received garbage instead of a root from client");
@@ -635,7 +574,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 
     Finally stopServer([&]() {
         writeFull(shutdownPipe.writeSide.get(), "x", false);
-        state.wakeup.notify_all();
+        wakeup.notify_all();
         if (serverThread.joinable()) serverThread.join();
     });
 
@@ -646,15 +585,15 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
     if (!options.ignoreLiveness)
         findRootsNoTemp(rootMap, true);
 
-    for (auto & i : rootMap) state.roots.insert(i.first);
+    for (auto & i : rootMap) roots.insert(i.first);
 
     /* Read the temporary roots created before we acquired the global
        GC root. Any new roots will be sent to our socket. */
     Roots tempRoots;
     findTempRoots(tempRoots, true);
     for (auto & root : tempRoots) {
-        state.shared.lock()->tempRoots.insert(std::string(root.first.hashPart()));
-        state.roots.insert(root.first);
+        _shared.lock()->tempRoots.insert(std::string(root.first.hashPart()));
+        roots.insert(root.first);
     }
 
     /* Helper function that deletes a path from the store and throws
@@ -666,14 +605,14 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 
         printInfo("deleting '%1%'", path);
 
-        state.results.paths.insert(path);
+        results.paths.insert(path);
 
         uint64_t bytesFreed;
         deletePath(realPath, bytesFreed);
-        state.results.bytesFreed += bytesFreed;
+        results.bytesFreed += bytesFreed;
 
-        if (state.results.bytesFreed > state.options.maxFreed) {
-            printInfo("deleted more than %d bytes; stopping", state.options.maxFreed);
+        if (results.bytesFreed > options.maxFreed) {
+            printInfo("deleted more than %d bytes; stopping", options.maxFreed);
             throw GCLimitReached();
         }
     };
@@ -689,9 +628,9 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
         /* Wake up any GC client waiting for deletion of the paths in
            'visited' to finish. */
         Finally releasePending([&]() {
-            auto shared(state.shared.lock());
+            auto shared(_shared.lock());
             shared->pending.reset();
-            state.wakeup.notify_all();
+            wakeup.notify_all();
         });
 
         auto enqueue = [&](const StorePath & path) {
@@ -706,34 +645,34 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 
             /* Bail out if we've previously discovered that this path
                is alive. */
-            if (state.alive.count(*path)) {
-                state.alive.insert(start);
+            if (alive.count(*path)) {
+                alive.insert(start);
                 return;
             }
 
             /* If we've previously deleted this path, we don't have to
                handle it again. */
-            if (state.dead.count(*path)) continue;
+            if (dead.count(*path)) continue;
 
             /* If this is a root, bail out. */
-            if (state.roots.count(*path)) {
+            if (roots.count(*path)) {
                 debug("cannot delete '%s' because it's a root", printStorePath(*path));
-                state.alive.insert(*path);
-                state.alive.insert(start);
+                alive.insert(*path);
+                alive.insert(start);
                 return;
             }
 
-            if (state.options.action == GCOptions::gcDeleteSpecific
-                && !state.options.pathsToDelete.count(*path))
+            if (options.action == GCOptions::gcDeleteSpecific
+                && !options.pathsToDelete.count(*path))
                 return;
 
             {
                 auto hashPart = std::string(path->hashPart());
-                auto shared(state.shared.lock());
+                auto shared(_shared.lock());
                 if (shared->tempRoots.count(hashPart)) {
                     debug("cannot delete '%s' because it's a temporary root", printStorePath(*path));
-                    state.alive.insert(*path);
-                    state.alive.insert(start);
+                    alive.insert(*path);
+                    alive.insert(start);
                     return;
                 }
                 shared->pending = hashPart;
@@ -749,7 +688,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 
                 /* If keep-derivations is set and this is a
                    derivation, then visit the derivation outputs. */
-                if (state.gcKeepDerivations && path->isDerivation()) {
+                if (gcKeepDerivations && path->isDerivation()) {
                     for (auto & [name, maybeOutPath] : queryPartialDerivationOutputMap(*path))
                         if (maybeOutPath &&
                             isValidPath(*maybeOutPath) &&
@@ -758,7 +697,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
                 }
 
                 /* If keep-outputs is set, then visit the derivers. */
-                if (state.gcKeepOutputs) {
+                if (gcKeepOutputs) {
                     auto derivers = queryValidDerivers(*path);
                     for (auto & i : derivers)
                         enqueue(i);
@@ -767,8 +706,8 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
         }
 
         for (auto & path : topoSortPaths(visited)) {
-            if (!state.dead.insert(path).second) continue;
-            if (state.shouldDelete) {
+            if (!dead.insert(path).second) continue;
+            if (shouldDelete) {
                 invalidatePathChecked(path);
                 deleteFromStore(path.to_string());
             }
@@ -781,7 +720,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 
         for (auto & i : options.pathsToDelete) {
             deleteReferrersClosure(i);
-            if (!state.dead.count(i))
+            if (!dead.count(i))
                 throw Error(
                     "Cannot delete path '%1%' since it is still alive. "
                     "To find out why, use: "
@@ -791,7 +730,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 
     } else if (options.maxFreed > 0) {
 
-        if (state.shouldDelete)
+        if (shouldDelete)
             printInfo("deleting garbage...");
         else
             printInfo("determining live/dead paths...");
@@ -821,22 +760,61 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
         }
     }
 
-    if (state.options.action == GCOptions::gcReturnLive) {
-        for (auto & i : state.alive)
-            state.results.paths.insert(printStorePath(i));
+    if (options.action == GCOptions::gcReturnLive) {
+        for (auto & i : alive)
+            results.paths.insert(printStorePath(i));
         return;
     }
 
-    if (state.options.action == GCOptions::gcReturnDead) {
-        for (auto & i : state.dead)
-            state.results.paths.insert(printStorePath(i));
+    if (options.action == GCOptions::gcReturnDead) {
+        for (auto & i : dead)
+            results.paths.insert(printStorePath(i));
         return;
     }
 
-    /* Clean up the links directory. */
+    /* Unlink all files in /nix/store/.links that have a link count of 1,
+       which indicates that there are no other links and so they can be
+       safely deleted.  FIXME: race condition with optimisePath(): we
+       might see a link count of 1 just before optimisePath() increases
+       the link count. */
     if (options.action == GCOptions::gcDeleteDead || options.action == GCOptions::gcDeleteSpecific) {
         printInfo("deleting unused links...");
-        removeUnusedLinks(state);
+
+        AutoCloseDir dir(opendir(linksDir.c_str()));
+        if (!dir) throw SysError("opening directory '%1%'", linksDir);
+
+        int64_t actualSize = 0, unsharedSize = 0;
+
+        struct dirent * dirent;
+        while (errno = 0, dirent = readdir(dir.get())) {
+            checkInterrupt();
+            string name = dirent->d_name;
+            if (name == "." || name == "..") continue;
+            Path path = linksDir + "/" + name;
+
+            auto st = lstat(path);
+
+            if (st.st_nlink != 1) {
+                actualSize += st.st_size;
+                unsharedSize += (st.st_nlink - 1) * st.st_size;
+                continue;
+            }
+
+            printMsg(lvlTalkative, format("deleting unused link '%1%'") % path);
+
+            if (unlink(path.c_str()) == -1)
+                throw SysError("deleting '%1%'", path);
+
+            results.bytesFreed += st.st_size;
+        }
+
+        struct stat st;
+        if (stat(linksDir.c_str(), &st) == -1)
+            throw SysError("statting '%1%'", linksDir);
+        int64_t overhead = st.st_blocks * 512ULL;
+
+        printInfo("note: currently hard linking saves %.2f MiB",
+            ((unsharedSize - actualSize - overhead) / (1024.0 * 1024.0)));
     }
 
     /* While we're at it, vacuum the database. */
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 15475f402..301425eb1 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -238,16 +238,12 @@ private:
     PathSet queryValidPathsOld();
     ValidPathInfo queryPathInfoOld(const Path & path);
 
-    struct GCState;
-
     void findRoots(const Path & path, unsigned char type, Roots & roots);
 
     void findRootsNoTemp(Roots & roots, bool censor);
 
     void findRuntimeRoots(Roots & roots, bool censor);
 
-    void removeUnusedLinks(const GCState & state);
-
     Path createTempDirInStore();
 
     void checkDerivationOutputs(const StorePath & drvPath, const Derivation & drv);

From 17e6ebcc90b6c7d5db8588f1d2b914c98543560b Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 14 Oct 2021 14:13:57 +0200
Subject: [PATCH 116/567] Speed up GC by marking entire closures as live

---
 src/libstore/gc.cc | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 800a3fd19..03d44ebf8 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -654,12 +654,22 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
                handle it again. */
             if (dead.count(*path)) continue;
 
+            auto markAlive = [&]()
+            {
+                alive.insert(*path);
+                alive.insert(start);
+                try {
+                    StorePathSet closure;
+                    computeFSClosure(*path, closure);
+                    for (auto & p : closure)
+                        alive.insert(p);
+                } catch (InvalidPath &) { }
+            };
+
             /* If this is a root, bail out. */
             if (roots.count(*path)) {
                 debug("cannot delete '%s' because it's a root", printStorePath(*path));
-                alive.insert(*path);
-                alive.insert(start);
-                return;
+                return markAlive();
             }
 
             if (options.action == GCOptions::gcDeleteSpecific
@@ -671,9 +681,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
                 auto shared(_shared.lock());
                 if (shared->tempRoots.count(hashPart)) {
                     debug("cannot delete '%s' because it's a temporary root", printStorePath(*path));
-                    alive.insert(*path);
-                    alive.insert(start);
-                    return;
+                    return markAlive();
                 }
                 shared->pending = hashPart;
             }

From 3a2fc9ce1dd3b176bdef257be75439bde33c210a Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Thu, 14 Oct 2021 15:42:54 +0200
Subject: [PATCH 117/567] Fix the `isDaemonNewer` check
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- Don’t hardcode the “newer” version
- Remove an ill-placed `return`
---
 tests/common.sh.in | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/common.sh.in b/tests/common.sh.in
index 7daab2460..08f5e0a77 100644
--- a/tests/common.sh.in
+++ b/tests/common.sh.in
@@ -126,7 +126,7 @@ isDaemonNewer () {
   [[ -n "${NIX_DAEMON_PACKAGE:-}" ]] || return 0
   local requiredVersion="$1"
   local daemonVersion=$($NIX_DAEMON_PACKAGE/bin/nix-daemon --version | cut -d' ' -f3)
-  return [[ $(nix eval --expr "builtins.compareVersions ''$daemonVersion'' ''2.4''") -ge 0 ]]
+  [[ $(nix eval --expr "builtins.compareVersions ''$daemonVersion'' ''$requiredVersion''") -ge 0 ]]
 }
 
 requireDaemonNewerThan () {

From b598e5c47c0e98b45de00b488707f4f92fc093eb Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Thu, 14 Oct 2021 16:00:59 +0200
Subject: [PATCH 118/567] Fix the min bound for the structured-attrs test
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The min bound written corresponds to the date of the commit that
introduced the change, but it only got merged on master some weeks
later. Since the version is essentially the commit date, that means that
there’s a whole range of commits on master (including the current
`nixUnstable`) that have a higher version but don’t contain the required
change.
---
 tests/structured-attrs.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/structured-attrs.sh b/tests/structured-attrs.sh
index e585ce37f..378dbc735 100644
--- a/tests/structured-attrs.sh
+++ b/tests/structured-attrs.sh
@@ -2,7 +2,7 @@ source common.sh
 
 # 27ce722638 required some incompatible changes to the nix file, so skip this
 # tests for the older versions
-requireDaemonNewerThan "2.4pre20210622"
+requireDaemonNewerThan "2.4pre20210712"
 
 clearStore
 

From a9d9e5555118025032eabd9612e03473a97ebff8 Mon Sep 17 00:00:00 2001
From: yvt <i@yvt.jp>
Date: Fri, 15 Oct 2021 09:48:15 +0900
Subject: [PATCH 119/567] Add another path where a Rosetta 2 configuration file
 is possibly located

---
 src/libstore/globals.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/libstore/globals.cc b/src/libstore/globals.cc
index 6934801e3..4903d0922 100644
--- a/src/libstore/globals.cc
+++ b/src/libstore/globals.cc
@@ -148,7 +148,8 @@ StringSet Settings::getDefaultExtraPlatforms()
     // machines. Note that we can’t force processes from executing
     // x86_64 in aarch64 environments or vice versa since they can
     // always exec with their own binary preferences.
-    if (pathExists("/Library/Apple/System/Library/LaunchDaemons/com.apple.oahd.plist")) {
+    if (pathExists("/Library/Apple/System/Library/LaunchDaemons/com.apple.oahd.plist") ||
+        pathExists("/System/Library/LaunchDaemons/com.apple.oahd.plist")) {
         if (std::string{SYSTEM} == "x86_64-darwin")
             extraPlatforms.insert("aarch64-darwin");
         else if (std::string{SYSTEM} == "aarch64-darwin")

From d1da45855c0f7d71bb13928f8028937d3fa062d9 Mon Sep 17 00:00:00 2001
From: Arthur Gautier <baloo@superbaloo.net>
Date: Wed, 13 Oct 2021 17:10:35 +0000
Subject: [PATCH 120/567] preloadNSS: Drop the dns query workaround

We can actually just load nss ourselves and call in nss to configure it
and we don't need to run a dummy query entirely to have nss load nss_dns
as a side-effect.

Signed-off-by: Arthur Gautier <baloo@superbaloo.net>
---
 src/libmain/shared.cc | 23 +++++------------------
 1 file changed, 5 insertions(+), 18 deletions(-)

diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index 85f9f0d58..93775bed1 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -15,9 +15,9 @@
 #include <sys/stat.h>
 #include <unistd.h>
 #include <signal.h>
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <netdb.h>
+#include <gnu/lib-names.h>
+#include <nss.h>
+#include <dlfcn.h>
 
 #include <openssl/crypto.h>
 
@@ -121,21 +121,8 @@ static void preloadNSS() {
        been loaded in the parent. So we force a lookup of an invalid domain to force the NSS machinery to
        load its lookup libraries in the parent before any child gets a chance to. */
     std::call_once(dns_resolve_flag, []() {
-        struct addrinfo *res = NULL;
-
-        /* nss will only force the "local" (not through nscd) dns resolution if its on the LOCALDOMAIN.
-           We need the resolution to be done locally, as nscd socket will not be accessible in the
-           sandbox. */
-        char * previous_env = getenv("LOCALDOMAIN");
-        setenv("LOCALDOMAIN", "invalid", 1);
-        if (getaddrinfo("this.pre-initializes.the.dns.resolvers.invalid.", "http", NULL, &res) == 0) {
-            if (res) freeaddrinfo(res);
-        }
-        if (previous_env) {
-             setenv("LOCALDOMAIN", previous_env, 1);
-        } else {
-             unsetenv("LOCALDOMAIN");
-        }
+        dlopen (LIBNSS_DNS_SO, RTLD_NOW);
+        __nss_configure_lookup ("hosts", "dns");
     });
 }
 

From 85717eff15fadd625014ed57de80f59304fa67db Mon Sep 17 00:00:00 2001
From: Arthur Gautier <baloo@superbaloo.net>
Date: Thu, 14 Oct 2021 21:43:07 +0000
Subject: [PATCH 121/567] preloadNSS: detect glibc

Signed-off-by: Arthur Gautier <baloo@superbaloo.net>
---
 src/libmain/shared.cc | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index 93775bed1..1fb2d62d3 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -15,9 +15,12 @@
 #include <sys/stat.h>
 #include <unistd.h>
 #include <signal.h>
+#include <features.h>
+#ifdef __GLIBC__
 #include <gnu/lib-names.h>
 #include <nss.h>
 #include <dlfcn.h>
+#endif
 
 #include <openssl/crypto.h>
 
@@ -121,8 +124,10 @@ static void preloadNSS() {
        been loaded in the parent. So we force a lookup of an invalid domain to force the NSS machinery to
        load its lookup libraries in the parent before any child gets a chance to. */
     std::call_once(dns_resolve_flag, []() {
+#ifdef __GLIBC__
         dlopen (LIBNSS_DNS_SO, RTLD_NOW);
         __nss_configure_lookup ("hosts", "dns");
+#endif
     });
 }
 

From ca8989daf36629ce47cf35d6e56f92d01f3172ec Mon Sep 17 00:00:00 2001
From: Arthur Gautier <baloo@superbaloo.net>
Date: Thu, 14 Oct 2021 21:54:29 +0000
Subject: [PATCH 122/567] preloadNSS: warn if unable to open nss backend

Signed-off-by: Arthur Gautier <baloo@superbaloo.net>
---
 src/libmain/shared.cc | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index 1fb2d62d3..da3bc3bb5 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -125,7 +125,9 @@ static void preloadNSS() {
        load its lookup libraries in the parent before any child gets a chance to. */
     std::call_once(dns_resolve_flag, []() {
 #ifdef __GLIBC__
-        dlopen (LIBNSS_DNS_SO, RTLD_NOW);
+        if (dlopen (LIBNSS_DNS_SO, RTLD_NOW) == NULL) {
+            printMsg(Verbosity::lvlWarn, fmt("Unable to load nss_dns backend"));
+        }
         __nss_configure_lookup ("hosts", "dns");
 #endif
     });

From 1bdeef83958251e728abe9398b4286cb6b5e9551 Mon Sep 17 00:00:00 2001
From: Kevin Amado <kamadorueda@gmail.com>
Date: Thu, 14 Oct 2021 23:23:04 -0500
Subject: [PATCH 123/567] add pos to EvalState::forceValue

- This way we improve error messages
  on infinite recursion
- Demo:
  ```nix
  let
    x = builtins.fetchMercurial x;
  in
  x
  ```
- Before:
  ```bash
  $ nix-instantiate --show-trace --strict
  error: infinite recursion encountered
  ```
- After:
  ```bash
  nix-instantiate --show-trace --strict
  error: infinite recursion encountered

       at /data/github/kamadorueda/test/default.nix:2:7:

            1| let
            2|   x = builtins.fetchMercurial x;
             |       ^
            3| in
  ```

Mentions: #3505
---
 src/libexpr/primops/fetchMercurial.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libexpr/primops/fetchMercurial.cc b/src/libexpr/primops/fetchMercurial.cc
index 1cd481243..c23480853 100644
--- a/src/libexpr/primops/fetchMercurial.cc
+++ b/src/libexpr/primops/fetchMercurial.cc
@@ -15,7 +15,7 @@ static void prim_fetchMercurial(EvalState & state, const Pos & pos, Value * * ar
     std::string name = "source";
     PathSet context;
 
-    state.forceValue(*args[0]);
+    state.forceValue(*args[0], pos);
 
     if (args[0]->type() == nAttrs) {
 

From c345a4a1e8ad2c5274b06a72337b91a6d11c7f8a Mon Sep 17 00:00:00 2001
From: Arthur Gautier <baloo@superbaloo.net>
Date: Fri, 15 Oct 2021 07:33:49 +0000
Subject: [PATCH 124/567] fixup macos build

Signed-off-by: Arthur Gautier <baloo@superbaloo.net>
---
 src/libmain/shared.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index da3bc3bb5..5eb7871f3 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -15,7 +15,9 @@
 #include <sys/stat.h>
 #include <unistd.h>
 #include <signal.h>
+#ifdef __linux__
 #include <features.h>
+#endif
 #ifdef __GLIBC__
 #include <gnu/lib-names.h>
 #include <nss.h>

From 304180d0ded6bf166b051f2b2ce5c33c18c2bbfe Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 15 Oct 2021 12:20:23 +0200
Subject: [PATCH 125/567] Memoize queryReferrers()

---
 src/libstore/gc.cc | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 03d44ebf8..ed792a777 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -617,6 +617,8 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
         }
     };
 
+    std::map<StorePath, StorePathSet> referrersCache;
+
     /* Helper function that visits all paths reachable from `start`
        via the referrers edges and optionally derivers and derivation
        output edges. If none of those paths are roots, then all
@@ -689,9 +691,14 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
             if (isValidPath(*path)) {
 
                 /* Visit the referrers of this path. */
-                StorePathSet referrers;
-                queryReferrers(*path, referrers);
-                for (auto & p : referrers)
+                auto i = referrersCache.find(*path);
+                if (i == referrersCache.end()) {
+                    StorePathSet referrers;
+                    queryReferrers(*path, referrers);
+                    referrersCache.emplace(*path, std::move(referrers));
+                    i = referrersCache.find(*path);
+                }
+                for (auto & p : i->second)
                     enqueue(p);
 
                 /* If keep-derivations is set and this is a
@@ -718,6 +725,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
             if (shouldDelete) {
                 invalidatePathChecked(path);
                 deleteFromStore(path.to_string());
+                referrersCache.erase(path);
             }
         }
     };

From be35569a6e488563f00caee521eba451d9b63680 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 15 Oct 2021 12:36:29 +0200
Subject: [PATCH 126/567] Run installTests on Hydra

---
 flake.nix | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/flake.nix b/flake.nix
index 2d0c44889..cad6b22f8 100644
--- a/flake.nix
+++ b/flake.nix
@@ -488,12 +488,7 @@
             '';
         */
 
-      };
-
-      checks = forAllSystems (system: {
-        binaryTarball = self.hydraJobs.binaryTarball.${system};
-        perlBindings = self.hydraJobs.perlBindings.${system};
-        installTests =
+        installTests = forAllSystems (system:
           let pkgs = nixpkgsFor.${system}; in
           pkgs.runCommand "install-tests" {
             againstSelf = testNixVersions pkgs pkgs.nix pkgs.pkgs.nix;
@@ -505,7 +500,14 @@
             # Disabled because the latest stable version doesn't handle
             # `NIX_DAEMON_SOCKET_PATH` which is required for the tests to work
             # againstLatestStable = testNixVersions pkgs pkgs.nix pkgs.nixStable;
-          } "touch $out";
+          } "touch $out");
+
+      };
+
+      checks = forAllSystems (system: {
+        binaryTarball = self.hydraJobs.binaryTarball.${system};
+        perlBindings = self.hydraJobs.perlBindings.${system};
+        installTests = self.hydraJobs.installTests.${system};
       });
 
       packages = forAllSystems (system: {

From 4d014221d4aaf9c2e7a323be002f058ebb4d79e2 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 15 Oct 2021 12:41:27 +0200
Subject: [PATCH 127/567] Fix test against old daemon

---
 tests/gc.sh | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/gc.sh b/tests/gc.sh
index 33d627dae..a736b63db 100644
--- a/tests/gc.sh
+++ b/tests/gc.sh
@@ -26,6 +26,7 @@ if nix-store --delete $outPath; then false; fi
 test -e $outPath
 
 for i in $NIX_STORE_DIR/*; do
+    if [[ $i =~ /trash ]]; then continue; fi # compat with old daemon
     touch $i.lock
     touch $i.chroot
 done

From 0b55c8767dfa15540f47579442350ffad51fc047 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Fri, 15 Oct 2021 14:15:43 +0200
Subject: [PATCH 128/567] Disable the eval-store test when using the daemon
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Using the daemon will break most of the assumptions of this test, so
it’s as simple to just disable it
---
 tests/eval-store.sh | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tests/eval-store.sh b/tests/eval-store.sh
index 9ab7a87be..679da5741 100644
--- a/tests/eval-store.sh
+++ b/tests/eval-store.sh
@@ -1,6 +1,8 @@
 source common.sh
 
-requireDaemonNewerThan "2.4pre20210727"
+# Using `--eval-store` with the daemon will eventually copy everything
+# to the build store, invalidating most of the tests here
+needLocalStore
 
 eval_store=$TEST_ROOT/eval-store
 

From e0936ae38f110db68870b1d80d6c628172d12b4c Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 15 Oct 2021 16:12:21 +0200
Subject: [PATCH 129/567] Fix crash when a GC client disconnects

The client thread can't just delete its own thread object from
connections, it has to detach it.
---
 src/libstore/gc.cc | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index ed792a777..220441927 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -536,7 +536,10 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
                 auto fdClient_ = fdClient.get();
                 std::thread clientThread([&, fdClient = std::move(fdClient)]() {
                     Finally cleanup([&]() {
-                        connections.lock()->erase(fdClient.get());
+                        auto conn(connections.lock());
+                        auto i = conn->find(fdClient.get());
+                        i->second.detach();
+                        conn->erase(i);
                     });
 
                     while (true) {

From fcb8af550f5fca37458da0d9042a2b59523eb304 Mon Sep 17 00:00:00 2001
From: Yorick van Pelt <yorick@yorickvanpelt.nl>
Date: Fri, 15 Oct 2021 16:25:49 +0200
Subject: [PATCH 130/567] Restore parent mount namespace in
 restoreProcessContext

This ensures any started processes can't write to /nix/store (except
during builds). This partially reverts 01d07b1e, which happened because
of #2646.

The problem was only happening after nix downloads anything, causing
me to suspect the download thread. The problem turns out to be:
"A  process  can't  join a new mount namespace if it is sharing
filesystem-related attributes with another process", in this case this
process is the curl thread.

Ideally, we might kill it before spawning the shell process, but it's
inside a static variable in the getFileTransfer() function. So
instead, stop it from sharing FS state using unshare(). A strategy
such as the one from #5057 (single-threaded chroot helper binary) is
also very much on the table.

Fixes #4337.
---
 src/libstore/filetransfer.cc |  8 ++++++++
 src/libstore/local-store.cc  |  1 +
 src/libutil/util.cc          | 28 ++++++++++++++++++++++++++--
 src/libutil/util.hh          | 10 +++++++++-
 4 files changed, 44 insertions(+), 3 deletions(-)

diff --git a/src/libstore/filetransfer.cc b/src/libstore/filetransfer.cc
index 37e17b397..4621a8217 100644
--- a/src/libstore/filetransfer.cc
+++ b/src/libstore/filetransfer.cc
@@ -544,6 +544,14 @@ struct curlFileTransfer : public FileTransfer
             stopWorkerThread();
         });
 
+#ifdef __linux__
+        /* Cause this thread to not share any FS attributes with the main thread,
+           because this causes setns() in restoreMountNamespace() to fail.
+           Ideally, this would happen in the std::thread() constructor. */
+        if (unshare(CLONE_FS) != 0)
+            throw SysError("unsharing filesystem state in download thread");
+#endif
+
         std::map<CURL *, std::shared_ptr<TransferItem>> items;
 
         bool quit = false;
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 5b2490472..3440c3150 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -495,6 +495,7 @@ void LocalStore::makeStoreWritable()
         throw SysError("getting info about the Nix store mount point");
 
     if (stat.f_flag & ST_RDONLY) {
+        saveMountNamespace();
         if (unshare(CLONE_NEWNS) == -1)
             throw SysError("setting up a private mount namespace");
 
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 563a72c12..a5e961c1e 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1629,10 +1629,34 @@ void setStackSize(size_t stackSize)
     }
     #endif
 }
+static AutoCloseFD fdSavedMountNamespace;
 
-void restoreProcessContext()
+void saveMountNamespace()
+{
+#if __linux__
+    static std::once_flag done;
+    std::call_once(done, []() {
+        fdSavedMountNamespace = open("/proc/self/ns/mnt", O_RDONLY);
+        if (!fdSavedMountNamespace)
+            throw SysError("saving parent mount namespace");
+    });
+#endif
+}
+
+void restoreMountNamespace()
+{
+#if __linux__
+    if (fdSavedMountNamespace && setns(fdSavedMountNamespace.get(), CLONE_NEWNS) == -1)
+        throw SysError("restoring parent mount namespace");
+#endif
+}
+
+void restoreProcessContext(bool restoreMounts)
 {
     restoreSignals();
+    if (restoreMounts) {
+        restoreMountNamespace();
+    }
 
     restoreAffinity();
 
@@ -1766,7 +1790,7 @@ void commonChildInit(Pipe & logPipe)
     logger = makeSimpleLogger();
 
     const static string pathNullDevice = "/dev/null";
-    restoreProcessContext();
+    restoreProcessContext(false);
 
     /* Put the child in a separate session (and thus a separate
        process group) so that it has no controlling terminal (meaning
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 29232453f..ef3430689 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -300,7 +300,15 @@ void setStackSize(size_t stackSize);
 
 /* Restore the original inherited Unix process context (such as signal
    masks, stack size, CPU affinity). */
-void restoreProcessContext();
+void restoreProcessContext(bool restoreMounts = true);
+
+/* Save the current mount namespace. Ignored if called more than
+   once. */
+void saveMountNamespace();
+
+/* Restore the mount namespace saved by saveMountNamespace(). Ignored
+   if saveMountNamespace() was never called. */
+void restoreMountNamespace();
 
 
 class ExecError : public Error

From ac54c6faa6b73c3da180dec666fadd6e8d7d18e3 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 15 Oct 2021 16:36:48 +0200
Subject: [PATCH 131/567] Fix main GC thread exiting

---
 src/libstore/gc.cc | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 220441927..648295684 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -538,8 +538,10 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
                     Finally cleanup([&]() {
                         auto conn(connections.lock());
                         auto i = conn->find(fdClient.get());
-                        i->second.detach();
-                        conn->erase(i);
+                        if (i != conn->end()) {
+                            i->second.detach();
+                            conn->erase(i);
+                        }
                     });
 
                     while (true) {

From 10f9a8e77d504354deafbcf7351a6d46d4528542 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 15 Oct 2021 16:52:37 +0200
Subject: [PATCH 132/567] Add a test for the non-blocking GC

---
 src/libstore/gc.cc       |  4 ++++
 tests/gc-non-blocking.sh | 33 +++++++++++++++++++++++++++++++++
 tests/local.mk           |  1 +
 3 files changed, 38 insertions(+)
 create mode 100644 tests/gc-non-blocking.sh

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 648295684..5e8cbf8fc 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -735,6 +735,10 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
         }
     };
 
+    /* Synchronisation point for testing, see tests/gc-concurrent.sh. */
+    if (auto p = getEnv("_NIX_TEST_GC_SYNC"))
+        readFile(*p);
+
     /* Either delete all garbage paths, or just the specified
        paths (for gcDeleteSpecific). */
     if (options.action == GCOptions::gcDeleteSpecific) {
diff --git a/tests/gc-non-blocking.sh b/tests/gc-non-blocking.sh
new file mode 100644
index 000000000..8b21c6f1c
--- /dev/null
+++ b/tests/gc-non-blocking.sh
@@ -0,0 +1,33 @@
+# Test whether the collector is non-blocking, i.e. a build can run in
+# parallel with it.
+source common.sh
+
+needLocalStore "the GC test needs a synchronisation point"
+
+clearStore
+
+fifo=$TEST_ROOT/test.fifo
+mkfifo "$fifo"
+
+dummy=$(nix store add-path ./simple.nix)
+
+running=$TEST_ROOT/running
+touch $running
+
+(_NIX_TEST_GC_SYNC=$fifo nix-store --gc -vvvvv; rm $running) &
+pid=$!
+
+sleep 2
+
+outPath=$(nix-build -o "$TEST_ROOT/result" -E "
+  with import ./config.nix;
+  mkDerivation {
+    name = \"non-blocking\";
+    buildCommand = \"set -x; test -e $running; mkdir \$out; echo > $fifo\";
+  }")
+
+wait $pid
+
+(! test -e $running)
+(! test -e $dummy)
+test -e $outPath
diff --git a/tests/local.mk b/tests/local.mk
index d88c3a875..8d454ee19 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -4,6 +4,7 @@ nix_tests = \
   gc.sh \
   ca/gc.sh \
   gc-concurrent.sh \
+  gc-non-blocking.sh \
   gc-auto.sh \
   referrers.sh user-envs.sh logging.sh nix-build.sh misc.sh fixed.sh \
   gc-runtime.sh check-refs.sh filter-source.sh \

From a594d1afd5172abba85561f04fd9976582f1b6c3 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 15 Oct 2021 16:58:21 +0200
Subject: [PATCH 133/567] Revert "Fix referrers test"

This reverts commit e31a48366f19d5fa452df6273e817a4ea5516e50. Unnecessary after 0be8cc1466f317e33977590510bac4b18471f0ce.
---
 tests/referrers.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/referrers.sh b/tests/referrers.sh
index 7ede707b8..81323c280 100644
--- a/tests/referrers.sh
+++ b/tests/referrers.sh
@@ -14,9 +14,9 @@ echo "making registration..."
 
 set +x
 for ((n = 0; n < $max; n++)); do
-    storePath=$NIX_STORE_DIR/$(printf "%05d\n" $n)aaaaaaaaaaaaaaaaaaaaaaaaaaa-$n
+    storePath=$NIX_STORE_DIR/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-$n
     echo -n > $storePath
-    ref2=$NIX_STORE_DIR/$(printf "%05d\n" $((n+1)))aaaaaaaaaaaaaaaaaaaaaaaaaaa-$((n+1))
+    ref2=$NIX_STORE_DIR/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-$((n+1))
     if test $((n+1)) = $max; then
         ref2=$reference
     fi

From 18e3d63341bc03e152659a6836a1b52a1241fe57 Mon Sep 17 00:00:00 2001
From: Kevin Amado <kamadorueda@gmail.com>
Date: Fri, 15 Oct 2021 18:56:17 -0500
Subject: [PATCH 134/567] fetchTree: add pos to EvalState::forceValue

- This way we improve error messages
  on infinite recursion
- Demo:
  ```nix
  let x = builtins.fetchTree x;
  in x
  ```
- Before:
  ```bash
  $ nix-instantiate --extra-experimental-features flakes --strict
  error: infinite recursion encountered
  ```
- After:
  ```bash
  $ nix-instantiate --extra-experimental-features flakes --strict
  error: infinite recursion encountered

       at /data/github/kamadorueda/nix/test.nix:1:9:

            1| let x = builtins.fetchTree x;
             |         ^
            2| in x
  ```

Mentions: #3505
---
 src/libexpr/primops/fetchTree.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index f570f19ae..441edd648 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -97,7 +97,7 @@ static void fetchTree(
     fetchers::Input input;
     PathSet context;
 
-    state.forceValue(*args[0]);
+    state.forceValue(*args[0], pos);
 
     if (args[0]->type() == nAttrs) {
         state.forceAttrs(*args[0], pos);

From e5a27a3b4e5ae6a1b84e439f880613e6fe5faf98 Mon Sep 17 00:00:00 2001
From: Kevin Amado <kamadorueda@gmail.com>
Date: Fri, 15 Oct 2021 19:21:38 -0500
Subject: [PATCH 135/567] fetchTree: add pos to EvalState::forceValue

- This way we improve error messages
  on infinite recursion
- Demo:
  ```nix
  let x = builtins.fetchTree {
    type = "git";
    inherit x;
  };
  in x
  ```
- Before:
  ```bash
  $ nix-instantiate --extra-experimental-features flakes --strict
  error: infinite recursion encountered
  ```
- After:
  ```bash
  $ nix-instantiate --extra-experimental-features flakes --strict
  error: infinite recursion encountered

       at /data/github/kamadorueda/nix/test.nix:3:10:

            2|   type = "git";
            3|   inherit x;
             |          ^
            4| };
  ```

Mentions: #3505
---
 src/libexpr/primops/fetchTree.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index 441edd648..727b661e1 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -121,7 +121,7 @@ static void fetchTree(
 
         for (auto & attr : *args[0]->attrs) {
             if (attr.name == state.sType) continue;
-            state.forceValue(*attr.value);
+            state.forceValue(*attr.value, *attr.pos);
             if (attr.value->type() == nPath || attr.value->type() == nString) {
                 auto s = state.coerceToString(*attr.pos, *attr.value, context, false, false);
                 attrs.emplace(attr.name,

From fa4abe46e2cedfacc90c82177671a3000b229f28 Mon Sep 17 00:00:00 2001
From: Arthur Gautier <baloo@superbaloo.net>
Date: Sat, 16 Oct 2021 01:39:14 +0000
Subject: [PATCH 136/567] preloadNSS: document the preload mechanism

Signed-off-by: Arthur Gautier <baloo@superbaloo.net>
---
 src/libmain/shared.cc | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index 5eb7871f3..b6bfea8cb 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -127,6 +127,24 @@ static void preloadNSS() {
        load its lookup libraries in the parent before any child gets a chance to. */
     std::call_once(dns_resolve_flag, []() {
 #ifdef __GLIBC__
+        /* On linux, glibc will run every lookup through the nss layer.
+         * That means every lookup goes, by default, through nscd, which acts as a local
+         * cache.
+         * Because we run builds in a sandbox, we also remove access to nscd otherwise
+         * lookups would leak into the sandbox.
+         *
+         * But now we have a new problem, we need to make sure the nss_dns backend that
+         * does the dns lookups when nscd is not available is loaded or available.
+         *
+         * We can't make it available without leaking nix's environment, so instead we'll
+         * load the backend, and configure nss so it does not try to run dns lookups
+         * through nscd.
+         *
+         * This is technically only used for builtins:fetch* functions so we only care
+         * about dns.
+         *
+         * All other platforms are unaffected.
+         */
         if (dlopen (LIBNSS_DNS_SO, RTLD_NOW) == NULL) {
             printMsg(Verbosity::lvlWarn, fmt("Unable to load nss_dns backend"));
         }

From ffeec5f283464744fc0ba850622671eb1e91e4c7 Mon Sep 17 00:00:00 2001
From: John Chapman <thestar@fussycoder.id.au>
Date: Sun, 17 Oct 2021 15:24:22 +1100
Subject: [PATCH 137/567] Clarify that not all nix packages will use the
 default build phases

---
 doc/manual/src/command-ref/nix-shell.md | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/doc/manual/src/command-ref/nix-shell.md b/doc/manual/src/command-ref/nix-shell.md
index 8bcad85e1..0bd54b955 100644
--- a/doc/manual/src/command-ref/nix-shell.md
+++ b/doc/manual/src/command-ref/nix-shell.md
@@ -110,18 +110,18 @@ shell in which to build it:
 
 ```console
 $ nix-shell '<nixpkgs>' -A pan
-[nix-shell]$ unpackPhase
+[nix-shell]$ eval ${unpackPhase:-unpackPhase}
 [nix-shell]$ cd pan-*
-[nix-shell]$ configurePhase
-[nix-shell]$ buildPhase
+[nix-shell]$ eval ${configurePhase:-configurePhase}
+[nix-shell]$ eval ${buildPhase:-buildPhase}
 [nix-shell]$ ./pan/gui/pan
 ```
 
-Note: Other packages may override these phases (the unpackPhase,
-configurePhase, buildPhase, etc).
-For those, it may be required to do something like
-`eval "$configurePhase-configurePhase"` or `eval "$configurePhase"`
-depending on how that package's nix files have been written.
+The reason we use form `eval ${configurePhase:-configurePhase}` here is because
+those packages that override these phases do so by exporting the overridden
+values in the environment variable of the same name.
+Here bash is being told to either evaluate the contents of 'configurePhase',
+if it exists as a variable, otherwise evaluate the configurePhase function.
 
 To clear the environment first, and do some additional automatic
 initialisation of the interactive shell:

From 64a3b045c12c3e0fa98f5967ceb38378eaf70e2d Mon Sep 17 00:00:00 2001
From: Alexey Novikov <alexey@novikov.io>
Date: Sun, 17 Oct 2021 11:51:33 +0400
Subject: [PATCH 138/567] Fix error detection in 'base64Decode()'

Fixed a bug in initialization of 'base64DecodeChars' variable.
Currently decoder do not fail on invalid Base64 strings.
Added test-case to verify the fix.

Also have made 'base64DecodeChars' to be computed at compile time.
And added a test case to encode/decode string with non-printable charactes.
---
 src/libutil/tests/tests.cc | 17 +++++++++++++++++
 src/libutil/util.cc        | 18 ++++++++++--------
 2 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/src/libutil/tests/tests.cc b/src/libutil/tests/tests.cc
index 58df9c5ac..92972ed14 100644
--- a/src/libutil/tests/tests.cc
+++ b/src/libutil/tests/tests.cc
@@ -4,6 +4,8 @@
 #include <limits.h>
 #include <gtest/gtest.h>
 
+#include <numeric>
+
 namespace nix {
 
 /* ----------- tests for util.hh ------------------------------------------------*/
@@ -282,6 +284,17 @@ namespace nix {
         ASSERT_EQ(decoded, s);
     }
 
+    TEST(base64Encode, encodeAndDecodeNonPrintable) {
+        char s[256];
+        std::iota(std::rbegin(s), std::rend(s), 0);
+
+        auto encoded = base64Encode(s);
+        auto decoded = base64Decode(encoded);
+
+        EXPECT_EQ(decoded.length(), 255);
+        ASSERT_EQ(decoded, s);
+    }
+
     /* ----------------------------------------------------------------------------
      * base64Decode
      * --------------------------------------------------------------------------*/
@@ -294,6 +307,10 @@ namespace nix {
         ASSERT_EQ(base64Decode("cXVvZCBlcmF0IGRlbW9uc3RyYW5kdW0="), "quod erat demonstrandum");
     }
 
+    TEST(base64Decode, decodeThrowsOnInvalidChar) {
+        ASSERT_THROW(base64Decode("cXVvZCBlcm_0IGRlbW9uc3RyYW5kdW0="), Error);
+    }
+
     /* ----------------------------------------------------------------------------
      * toLower
      * --------------------------------------------------------------------------*/
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 563a72c12..a7b3b879a 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1436,8 +1436,7 @@ std::string filterANSIEscapes(const std::string & s, bool filterAll, unsigned in
 }
 
 
-static char base64Chars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
-static std::array<char, 256> base64DecodeChars;
+constexpr char base64Chars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 
 string base64Encode(std::string_view s)
 {
@@ -1462,12 +1461,15 @@ string base64Encode(std::string_view s)
 
 string base64Decode(std::string_view s)
 {
-    static std::once_flag flag;
-    std::call_once(flag, [](){
-        base64DecodeChars = { (char)-1 };
+    constexpr char npos = -1;
+    constexpr std::array<char, 256> base64DecodeChars = [&]() {
+        std::array<char, 256>  result{};
+        for (auto& c : result)
+            c = npos;
         for (int i = 0; i < 64; i++)
-            base64DecodeChars[(int) base64Chars[i]] = i;
-    });
+            result[base64Chars[i]] = i;
+        return result;
+    }();
 
     string res;
     unsigned int d = 0, bits = 0;
@@ -1477,7 +1479,7 @@ string base64Decode(std::string_view s)
         if (c == '\n') continue;
 
         char digit = base64DecodeChars[(unsigned char) c];
-        if (digit == -1)
+        if (digit == npos)
             throw Error("invalid character in Base64 string: '%c'", c);
 
         bits += 6;

From e989c83b44d7c4d8ffe2e5f4231e4861c5f7732f Mon Sep 17 00:00:00 2001
From: Alexey Novikov <alexey@novikov.io>
Date: Tue, 12 Oct 2021 16:18:44 +0400
Subject: [PATCH 139/567] Add error reporting to machine spec paser

Currently machine specification (`/etc/nix/machine`) parser fails
with a vague exception if the file had incorrect format.
This commit adds verbose exceptions and unit-tests for the parser.
---
 src/libstore/build/entry-points.cc            |   1 -
 src/libstore/machines.cc                      |  78 +++++---
 src/libstore/tests/machines.cc                | 169 ++++++++++++++++++
 .../tests/test-data/machines.bad_format       |   1 +
 src/libstore/tests/test-data/machines.valid   |   3 +
 5 files changed, 227 insertions(+), 25 deletions(-)
 create mode 100644 src/libstore/tests/machines.cc
 create mode 100644 src/libstore/tests/test-data/machines.bad_format
 create mode 100644 src/libstore/tests/test-data/machines.valid

diff --git a/src/libstore/build/entry-points.cc b/src/libstore/build/entry-points.cc
index 2b77e4354..b1e5d8504 100644
--- a/src/libstore/build/entry-points.cc
+++ b/src/libstore/build/entry-points.cc
@@ -1,4 +1,3 @@
-#include "machines.hh"
 #include "worker.hh"
 #include "substitution-goal.hh"
 #include "derivation-goal.hh"
diff --git a/src/libstore/machines.cc b/src/libstore/machines.cc
index 9843ccf04..910e32a76 100644
--- a/src/libstore/machines.cc
+++ b/src/libstore/machines.cc
@@ -83,53 +83,83 @@ ref<Store> Machine::openStore() const {
     return nix::openStore(storeUri, storeParams);
 }
 
-void parseMachines(const std::string & s, Machines & machines)
-{
-    for (auto line : tokenizeString<std::vector<string>>(s, "\n;")) {
+static std::vector<std::string> expandBuilderLines(const std::string& builders) {
+    std::vector<std::string> result;
+    for (auto line : tokenizeString<std::vector<string>>(builders, "\n;")) {
         trim(line);
         line.erase(std::find(line.begin(), line.end(), '#'), line.end());
         if (line.empty()) continue;
 
         if (line[0] == '@') {
-            auto file = trim(std::string(line, 1));
+            const std::string path = trim(std::string(line, 1));
+            std::string text;
             try {
-                parseMachines(readFile(file), machines);
+                text = readFile(path);
             } catch (const SysError & e) {
                 if (e.errNo != ENOENT)
                     throw;
-                debug("cannot find machines file '%s'", file);
+                debug("cannot find machines file '%s'", path);
             }
+
+            const auto lines = expandBuilderLines(text);
+            result.insert(end(result), begin(lines), end(lines));
             continue;
         }
 
-        auto tokens = tokenizeString<std::vector<string>>(line);
-        auto sz = tokens.size();
-        if (sz < 1)
-            throw FormatError("bad machine specification '%s'", line);
+        result.emplace_back(line);
+    }
+    return result;
+}
 
-        auto isSet = [&](size_t n) {
-            return tokens.size() > n && tokens[n] != "" && tokens[n] != "-";
-        };
+static Machine parseBuilderLine(const std::string& line) {
+    const auto tokens = tokenizeString<std::vector<string>>(line);
 
-        machines.emplace_back(tokens[0],
+    auto isSet = [&](size_t fieldIndex) {
+        return tokens.size() > fieldIndex && tokens[fieldIndex] != "" && tokens[fieldIndex] != "-";
+    };
+
+    auto parseUnsignedIntField = [&](size_t fieldIndex) {
+        const auto result = string2Int<unsigned int>(tokens[fieldIndex]);
+        if (!result) {
+            throw FormatError("bad machine specification: failed to convert column #%lu in a row: '%s' to 'unsigned int'", fieldIndex, line);
+        }
+        return result.value();
+    };
+
+    auto ensureBase64 = [&](size_t fieldIndex) {
+        const auto& str = tokens[fieldIndex];
+        try {
+            base64Decode(str);
+        } catch (const Error& e) {
+            throw FormatError("bad machine specification: a column #%lu in a row: '%s' is not valid base64 string: %s", fieldIndex, line, e.what());
+        }
+        return str;
+    };
+
+    if (!isSet(0)) {
+        throw FormatError("bad machine specification: store URI was not found at the first column of a row: '%s'", line);
+    }
+
+    return {tokens[0],
             isSet(1) ? tokenizeString<std::vector<string>>(tokens[1], ",") : std::vector<string>{settings.thisSystem},
             isSet(2) ? tokens[2] : "",
-            isSet(3) ? std::stoull(tokens[3]) : 1LL,
-            isSet(4) ? std::stoull(tokens[4]) : 1LL,
+            isSet(3) ? parseUnsignedIntField(3) : 1U,
+            isSet(4) ? parseUnsignedIntField(4) : 1U,
             isSet(5) ? tokenizeString<std::set<string>>(tokens[5], ",") : std::set<string>{},
             isSet(6) ? tokenizeString<std::set<string>>(tokens[6], ",") : std::set<string>{},
-            isSet(7) ? tokens[7] : "");
-    }
+            isSet(7) ? ensureBase64(7) : ""};
+}
+
+static Machines parseBuilderLines(const std::vector<std::string>& builders) {
+    Machines result;
+    std::transform(builders.begin(), builders.end(), std::back_inserter(result), parseBuilderLine);
+    return result;
 }
 
 Machines getMachines()
 {
-    static auto machines = [&]() {
-        Machines machines;
-        parseMachines(settings.builders, machines);
-        return machines;
-    }();
-    return machines;
+    const auto builderLines = expandBuilderLines(settings.builders);
+    return parseBuilderLines(builderLines);
 }
 
 }
diff --git a/src/libstore/tests/machines.cc b/src/libstore/tests/machines.cc
new file mode 100644
index 000000000..f51052b14
--- /dev/null
+++ b/src/libstore/tests/machines.cc
@@ -0,0 +1,169 @@
+#include "machines.hh"
+#include "globals.hh"
+
+#include <gmock/gmock-matchers.h>
+
+using testing::Contains;
+using testing::ElementsAre;
+using testing::EndsWith;
+using testing::Eq;
+using testing::Field;
+using testing::SizeIs;
+
+using nix::absPath;
+using nix::FormatError;
+using nix::getMachines;
+using nix::Machine;
+using nix::Machines;
+using nix::pathExists;
+using nix::Settings;
+using nix::settings;
+
+class Environment : public ::testing::Environment {
+  public:
+    void SetUp() override { settings.thisSystem = "TEST_ARCH-TEST_OS"; }
+};
+
+testing::Environment* const foo_env =
+    testing::AddGlobalTestEnvironment(new Environment);
+
+TEST(machines, getMachinesWithEmptyBuilders) {
+    settings.builders = "";
+    Machines actual = getMachines();
+    ASSERT_THAT(actual, SizeIs(0));
+}
+
+TEST(machines, getMachinesUriOnly) {
+    settings.builders = "nix@scratchy.labs.cs.uu.nl";
+    Machines actual = getMachines();
+    ASSERT_THAT(actual, SizeIs(1));
+    EXPECT_THAT(actual[0], Field(&Machine::storeUri, Eq("ssh://nix@scratchy.labs.cs.uu.nl")));
+    EXPECT_THAT(actual[0], Field(&Machine::systemTypes, ElementsAre("TEST_ARCH-TEST_OS")));
+    EXPECT_THAT(actual[0], Field(&Machine::sshKey, SizeIs(0)));
+    EXPECT_THAT(actual[0], Field(&Machine::maxJobs, Eq(1)));
+    EXPECT_THAT(actual[0], Field(&Machine::speedFactor, Eq(1)));
+    EXPECT_THAT(actual[0], Field(&Machine::supportedFeatures, SizeIs(0)));
+    EXPECT_THAT(actual[0], Field(&Machine::mandatoryFeatures, SizeIs(0)));
+    EXPECT_THAT(actual[0], Field(&Machine::sshPublicHostKey, SizeIs(0)));
+}
+
+TEST(machines, getMachinesDefaults) {
+    settings.builders = "nix@scratchy.labs.cs.uu.nl - - - - - - -";
+    Machines actual = getMachines();
+    ASSERT_THAT(actual, SizeIs(1));
+    EXPECT_THAT(actual[0], Field(&Machine::storeUri, Eq("ssh://nix@scratchy.labs.cs.uu.nl")));
+    EXPECT_THAT(actual[0], Field(&Machine::systemTypes, ElementsAre("TEST_ARCH-TEST_OS")));
+    EXPECT_THAT(actual[0], Field(&Machine::sshKey, SizeIs(0)));
+    EXPECT_THAT(actual[0], Field(&Machine::maxJobs, Eq(1)));
+    EXPECT_THAT(actual[0], Field(&Machine::speedFactor, Eq(1)));
+    EXPECT_THAT(actual[0], Field(&Machine::supportedFeatures, SizeIs(0)));
+    EXPECT_THAT(actual[0], Field(&Machine::mandatoryFeatures, SizeIs(0)));
+    EXPECT_THAT(actual[0], Field(&Machine::sshPublicHostKey, SizeIs(0)));
+}
+
+TEST(machines, getMachinesWithNewLineSeparator) {
+    settings.builders = "nix@scratchy.labs.cs.uu.nl\nnix@itchy.labs.cs.uu.nl";
+    Machines actual = getMachines();
+    ASSERT_THAT(actual, SizeIs(2));
+    EXPECT_THAT(actual, Contains(Field(&Machine::storeUri, EndsWith("nix@scratchy.labs.cs.uu.nl"))));
+    EXPECT_THAT(actual, Contains(Field(&Machine::storeUri, EndsWith("nix@itchy.labs.cs.uu.nl"))));
+}
+
+TEST(machines, getMachinesWithSemicolonSeparator) {
+    settings.builders = "nix@scratchy.labs.cs.uu.nl ; nix@itchy.labs.cs.uu.nl";
+    Machines actual = getMachines();
+    EXPECT_THAT(actual, SizeIs(2));
+    EXPECT_THAT(actual, Contains(Field(&Machine::storeUri, EndsWith("nix@scratchy.labs.cs.uu.nl"))));
+    EXPECT_THAT(actual, Contains(Field(&Machine::storeUri, EndsWith("nix@itchy.labs.cs.uu.nl"))));
+}
+
+TEST(machines, getMachinesWithCorrectCompleteSingleBuilder) {
+    settings.builders = "nix@scratchy.labs.cs.uu.nl     i686-linux      "
+                        "/home/nix/.ssh/id_scratchy_auto        8 3 kvm "
+                        "benchmark SSH+HOST+PUBLIC+KEY+BASE64+ENCODED==";
+    Machines actual = getMachines();
+    ASSERT_THAT(actual, SizeIs(1));
+    EXPECT_THAT(actual[0], Field(&Machine::storeUri, EndsWith("nix@scratchy.labs.cs.uu.nl")));
+    EXPECT_THAT(actual[0], Field(&Machine::systemTypes, ElementsAre("i686-linux")));
+    EXPECT_THAT(actual[0], Field(&Machine::sshKey, Eq("/home/nix/.ssh/id_scratchy_auto")));
+    EXPECT_THAT(actual[0], Field(&Machine::maxJobs, Eq(8)));
+    EXPECT_THAT(actual[0], Field(&Machine::speedFactor, Eq(3)));
+    EXPECT_THAT(actual[0], Field(&Machine::supportedFeatures, ElementsAre("kvm")));
+    EXPECT_THAT(actual[0], Field(&Machine::mandatoryFeatures, ElementsAre("benchmark")));
+    EXPECT_THAT(actual[0], Field(&Machine::sshPublicHostKey, Eq("SSH+HOST+PUBLIC+KEY+BASE64+ENCODED==")));
+}
+
+TEST(machines,
+     getMachinesWithCorrectCompleteSingleBuilderWithTabColumnDelimiter) {
+    settings.builders =
+        "nix@scratchy.labs.cs.uu.nl\ti686-linux\t/home/nix/.ssh/"
+        "id_scratchy_auto\t8\t3\tkvm\tbenchmark\tSSH+HOST+PUBLIC+"
+        "KEY+BASE64+ENCODED==";
+    Machines actual = getMachines();
+    ASSERT_THAT(actual, SizeIs(1));
+    EXPECT_THAT(actual[0], Field(&Machine::storeUri, EndsWith("nix@scratchy.labs.cs.uu.nl")));
+    EXPECT_THAT(actual[0], Field(&Machine::systemTypes, ElementsAre("i686-linux")));
+    EXPECT_THAT(actual[0], Field(&Machine::sshKey, Eq("/home/nix/.ssh/id_scratchy_auto")));
+    EXPECT_THAT(actual[0], Field(&Machine::maxJobs, Eq(8)));
+    EXPECT_THAT(actual[0], Field(&Machine::speedFactor, Eq(3)));
+    EXPECT_THAT(actual[0], Field(&Machine::supportedFeatures, ElementsAre("kvm")));
+    EXPECT_THAT(actual[0], Field(&Machine::mandatoryFeatures, ElementsAre("benchmark")));
+    EXPECT_THAT(actual[0], Field(&Machine::sshPublicHostKey, Eq("SSH+HOST+PUBLIC+KEY+BASE64+ENCODED==")));
+}
+
+TEST(machines, getMachinesWithMultiOptions) {
+    settings.builders = "nix@scratchy.labs.cs.uu.nl Arch1,Arch2 - - - "
+                        "SupportedFeature1,SupportedFeature2 "
+                        "MandatoryFeature1,MandatoryFeature2";
+    Machines actual = getMachines();
+    ASSERT_THAT(actual, SizeIs(1));
+    EXPECT_THAT(actual[0], Field(&Machine::storeUri, EndsWith("nix@scratchy.labs.cs.uu.nl")));
+    EXPECT_THAT(actual[0], Field(&Machine::systemTypes, ElementsAre("Arch1", "Arch2")));
+    EXPECT_THAT(actual[0], Field(&Machine::supportedFeatures, ElementsAre("SupportedFeature1", "SupportedFeature2")));
+    EXPECT_THAT(actual[0], Field(&Machine::mandatoryFeatures, ElementsAre("MandatoryFeature1", "MandatoryFeature2")));
+}
+
+TEST(machines, getMachinesWithIncorrectFormat) {
+    settings.builders = "nix@scratchy.labs.cs.uu.nl - - eight";
+    EXPECT_THROW(getMachines(), FormatError);
+    settings.builders = "nix@scratchy.labs.cs.uu.nl - - -1";
+    EXPECT_THROW(getMachines(), FormatError);
+    settings.builders = "nix@scratchy.labs.cs.uu.nl - - 8 three";
+    EXPECT_THROW(getMachines(), FormatError);
+    settings.builders = "nix@scratchy.labs.cs.uu.nl - - 8 -3";
+    EXPECT_THROW(getMachines(), FormatError);
+    settings.builders = "nix@scratchy.labs.cs.uu.nl - - 8 3 - - BAD_BASE64";
+    EXPECT_THROW(getMachines(), FormatError);
+}
+
+TEST(machines, getMachinesWithCorrectFileReference) {
+    auto path = absPath("src/libstore/tests/test-data/machines.valid");
+    ASSERT_TRUE(pathExists(path));
+
+    settings.builders = std::string("@") + path;
+    Machines actual = getMachines();
+    ASSERT_THAT(actual, SizeIs(3));
+    EXPECT_THAT(actual, Contains(Field(&Machine::storeUri, EndsWith("nix@scratchy.labs.cs.uu.nl"))));
+    EXPECT_THAT(actual, Contains(Field(&Machine::storeUri, EndsWith("nix@itchy.labs.cs.uu.nl"))));
+    EXPECT_THAT(actual, Contains(Field(&Machine::storeUri, EndsWith("nix@poochie.labs.cs.uu.nl"))));
+}
+
+TEST(machines, getMachinesWithCorrectFileReferenceToEmptyFile) {
+    auto path = "/dev/null";
+    ASSERT_TRUE(pathExists(path));
+
+    settings.builders = std::string("@") + path;
+    Machines actual = getMachines();
+    ASSERT_THAT(actual, SizeIs(0));
+}
+
+TEST(machines, getMachinesWithIncorrectFileReference) {
+    settings.builders = std::string("@") + absPath("/not/a/file");
+    Machines actual = getMachines();
+    ASSERT_THAT(actual, SizeIs(0));
+}
+
+TEST(machines, getMachinesWithCorrectFileReferenceToIncorrectFile) {
+    settings.builders = std::string("@") + absPath("src/libstore/tests/test-data/machines.bad_format");
+    EXPECT_THROW(getMachines(), FormatError);
+}
diff --git a/src/libstore/tests/test-data/machines.bad_format b/src/libstore/tests/test-data/machines.bad_format
new file mode 100644
index 000000000..7255a1216
--- /dev/null
+++ b/src/libstore/tests/test-data/machines.bad_format
@@ -0,0 +1 @@
+nix@scratchy.labs.cs.uu.nl - - eight
diff --git a/src/libstore/tests/test-data/machines.valid b/src/libstore/tests/test-data/machines.valid
new file mode 100644
index 000000000..1a6c8017c
--- /dev/null
+++ b/src/libstore/tests/test-data/machines.valid
@@ -0,0 +1,3 @@
+nix@scratchy.labs.cs.uu.nl  i686-linux      /home/nix/.ssh/id_scratchy_auto        8 1 kvm
+nix@itchy.labs.cs.uu.nl     i686-linux      /home/nix/.ssh/id_scratchy_auto        8 2
+nix@poochie.labs.cs.uu.nl   i686-linux      /home/nix/.ssh/id_scratchy_auto        1 2 kvm benchmark c3NoLXJzYSBBQUFBQjNOemFDMXljMkVBQUFBREFRQUJBQUFDQVFDWWV5R1laNTNzd1VjMUZNSHBWL1BCcXlKaFR5S1JoRkpWWVRpRHlQN2h5c1JGa0w4VDlLOGdhL2Y2L3c3QjN2SjNHSFRIUFkybENiUEdZbGNLd2h6M2ZRbFNNOEViNi95b3ZLajdvM1FsMEx5Y0dzdGJvRmcwWkZKNldncUxsR0ltS0NobUlxOGZ3TW5ZTWUxbnRQeTBUZFZjSU1tOTV3YzF3SjBMd2c3cEVMRmtHazdkeTVvYnM4a3lGZ0pORDVRSmFwQWJjeWp4Z1QzdzdMcktNZ2xzeWhhd01JNVpkMGZsQTVudW5OZ3pid3plYVhLaUsyTW0vdGJXYTU1YTd4QmNYdHpIZGlPSWdSajJlRWxaMGh5bk10YjBmcklsdmxIcEtLaVFaZ3pQdCtIVXQ2bXpRMkRVME52MGYyYnNSU0krOGpJU2pQcmdlcVVHRldMUzVIUTg2N2xSMlpiaWtyclhZNTdqbVFEZk5DRHY1VFBHZU9UekFEd2pjMDc2aFZ3VFJCd3VTZFhtaWNxTS95b3lrWitkV1dnZ25MenE5QU1tdlNZcDhmZkZDcS9CSDBZNUFXWTFHay9vS3hMVTNaOWt3ZDd2UWNFQWFCQ2dxdnVZRGdTaHE1RlhndDM3OVZESWtEL05ZSTg2QXVvajVDRmVNTzlRM2pJSlRadlh6c1VldjVoSnA2djcxSVh5ODVtbTY5R20zcXdicVE1SjVQZDU1Um56SitpaW5BNjZxTEFSc0Y4amNsSnd5ekFXclBoYU9DRVY2bjVMeVhVazhzMW9EVVR4V1pWN25rVkFTbHJ0MllGcjN5dzdjRTRXQVhsemhHcDhocmdLMVVkMUlyeDVnZWRaSnBWcy9uNWVybmJFMUxmb2x5UHUvRUFIWlh6VGd4dHVDUFNobXc9PQo=

From 823dce945a702c9ae51a83098f78e55ed780a223 Mon Sep 17 00:00:00 2001
From: Kevin Amado <kamadorueda@gmail.com>
Date: Fri, 15 Oct 2021 21:03:01 -0500
Subject: [PATCH 140/567] fetch: nicer infinite recursion errors

- This change applies to builtins.fetchurl and builtins.fetchTarball
- PoC: `let x = builtins.fetchurl x; in x`
- Before:
  ```bash
  $ nix-instantiate --extra-experimental-features flakes --strict
  error: infinite recursion encountered
  ```
- After:
  ```bash
  $ nix-instantiate --extra-experimental-features flakes --strict
  error: infinite recursion encountered

       at /data/github/kamadorueda/nix/test.nix:1:9:

            1| let x = builtins.fetchurl x; in x
             |         ^
  ```

Mentions: #3505
---
 src/libexpr/primops/fetchTree.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index 727b661e1..b00a79b7f 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -189,7 +189,7 @@ static void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
     std::optional<std::string> url;
     std::optional<Hash> expectedHash;
 
-    state.forceValue(*args[0]);
+    state.forceValue(*args[0], pos);
 
     if (args[0]->type() == nAttrs) {
 

From 2400819809bed9ab75ea0b6abc4b8564e65aeb7b Mon Sep 17 00:00:00 2001
From: "dependabot[bot]" <49699333+dependabot[bot]@users.noreply.github.com>
Date: Mon, 18 Oct 2021 22:01:24 +0000
Subject: [PATCH 141/567] Bump actions/checkout from 2.3.4 to 2.3.5

Bumps [actions/checkout](https://github.com/actions/checkout) from 2.3.4 to 2.3.5.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v2.3.4...v2.3.5)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
---
 .github/workflows/test.yml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index abaff75ee..9105b5396 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -11,7 +11,7 @@ jobs:
     runs-on: ${{ matrix.os }}
 
     steps:
-    - uses: actions/checkout@v2.3.4
+    - uses: actions/checkout@v2.3.5
       with:
         fetch-depth: 0
     - uses: cachix/install-nix-action@v14
@@ -41,7 +41,7 @@ jobs:
     outputs:
       installerURL: ${{ steps.prepare-installer.outputs.installerURL }}
     steps:
-    - uses: actions/checkout@v2.3.4
+    - uses: actions/checkout@v2.3.5
       with:
         fetch-depth: 0
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
@@ -61,7 +61,7 @@ jobs:
         os: [ubuntu-latest, macos-latest]
     runs-on: ${{ matrix.os }}
     steps:
-    - uses: actions/checkout@v2.3.4
+    - uses: actions/checkout@v2.3.5
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
     - uses: cachix/install-nix-action@v14
       with:

From ec9c1286ad5caf2e77907dc2548085f02cce5237 Mon Sep 17 00:00:00 2001
From: Benoit de Chezelles <benoit.dechezelles@gmail.com>
Date: Sat, 23 Oct 2021 15:32:48 +0200
Subject: [PATCH 142/567] Fix devShell build on non-NixOS with a different
 boost version

---
 flake.nix | 1 +
 1 file changed, 1 insertion(+)

diff --git a/flake.nix b/flake.nix
index 2d0c44889..5c00f744e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -61,6 +61,7 @@
 
         configureFlags =
           lib.optionals stdenv.isLinux [
+            "--with-boost=${boost}/lib"
             "--with-sandbox-shell=${sh}/bin/busybox"
             "LDFLAGS=-fuse-ld=gold"
           ];

From b9234142f5e3c69f3372f15ab2e6df19c7bf6b64 Mon Sep 17 00:00:00 2001
From: Alexander Bantyev <balsoft@balsoft.ru>
Date: Sat, 23 Oct 2021 21:30:51 +0300
Subject: [PATCH 143/567] addToStore, addToStoreFromDump: add references
 argument

Allow to pass a set of references to be added as info to the added paths.
---
 src/libstore/binary-cache-store.cc          | 6 ++++--
 src/libstore/binary-cache-store.hh          | 4 ++--
 src/libstore/build/local-derivation-goal.cc | 8 +++++---
 src/libstore/daemon.cc                      | 6 +++---
 src/libstore/legacy-ssh-store.cc            | 2 +-
 src/libstore/local-store.cc                 | 3 ++-
 src/libstore/local-store.hh                 | 2 +-
 src/libstore/remote-store.cc                | 3 +--
 src/libstore/remote-store.hh                | 2 +-
 src/libstore/store-api.cc                   | 4 ++--
 src/libstore/store-api.hh                   | 5 +++--
 11 files changed, 25 insertions(+), 20 deletions(-)

diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index 8fce94264..280f1d4b5 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -308,7 +308,7 @@ void BinaryCacheStore::addToStore(const ValidPathInfo & info, Source & narSource
 }
 
 StorePath BinaryCacheStore::addToStoreFromDump(Source & dump, const string & name,
-    FileIngestionMethod method, HashType hashAlgo, RepairFlag repair)
+    FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, StorePathSet references)
 {
     if (method != FileIngestionMethod::Recursive || hashAlgo != htSHA256)
         unsupported("addToStoreFromDump");
@@ -318,6 +318,7 @@ StorePath BinaryCacheStore::addToStoreFromDump(Source & dump, const string & nam
             nar.first,
         };
         info.narSize = nar.second;
+        info.references = references;
         return info;
     })->path;
 }
@@ -385,7 +386,7 @@ void BinaryCacheStore::queryPathInfoUncached(const StorePath & storePath,
 }
 
 StorePath BinaryCacheStore::addToStore(const string & name, const Path & srcPath,
-    FileIngestionMethod method, HashType hashAlgo, PathFilter & filter, RepairFlag repair)
+    FileIngestionMethod method, HashType hashAlgo, PathFilter & filter, RepairFlag repair, StorePathSet references)
 {
     /* FIXME: Make BinaryCacheStore::addToStoreCommon support
        non-recursive+sha256 so we can just use the default
@@ -408,6 +409,7 @@ StorePath BinaryCacheStore::addToStore(const string & name, const Path & srcPath
             nar.first,
         };
         info.narSize = nar.second;
+        info.references = references;
         info.ca = FixedOutputHash {
             .method = method,
             .hash = h,
diff --git a/src/libstore/binary-cache-store.hh b/src/libstore/binary-cache-store.hh
index 723f2e805..d8f077db2 100644
--- a/src/libstore/binary-cache-store.hh
+++ b/src/libstore/binary-cache-store.hh
@@ -97,11 +97,11 @@ public:
         RepairFlag repair, CheckSigsFlag checkSigs) override;
 
     StorePath addToStoreFromDump(Source & dump, const string & name,
-        FileIngestionMethod method, HashType hashAlgo, RepairFlag repair) override;
+        FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, StorePathSet references ) override;
 
     StorePath addToStore(const string & name, const Path & srcPath,
         FileIngestionMethod method, HashType hashAlgo,
-        PathFilter & filter, RepairFlag repair) override;
+        PathFilter & filter, RepairFlag repair, StorePathSet references) override;
 
     StorePath addTextToStore(const string & name, const string & s,
         const StorePathSet & references, RepairFlag repair) override;
diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 8d245f84a..694c408f3 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -1179,7 +1179,8 @@ struct RestrictedStore : public virtual RestrictedStoreConfig, public virtual Lo
 
     StorePath addToStore(const string & name, const Path & srcPath,
         FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256,
-        PathFilter & filter = defaultPathFilter, RepairFlag repair = NoRepair) override
+        PathFilter & filter = defaultPathFilter, RepairFlag repair = NoRepair,
+        StorePathSet references = StorePathSet()) override
     { throw Error("addToStore"); }
 
     void addToStore(const ValidPathInfo & info, Source & narSource,
@@ -1198,9 +1199,10 @@ struct RestrictedStore : public virtual RestrictedStoreConfig, public virtual Lo
     }
 
     StorePath addToStoreFromDump(Source & dump, const string & name,
-        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair) override
+        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair,
+        StorePathSet references = StorePathSet()) override
     {
-        auto path = next->addToStoreFromDump(dump, name, method, hashAlgo, repair);
+        auto path = next->addToStoreFromDump(dump, name, method, hashAlgo, repair, references);
         goal.addDependency(path);
         return path;
     }
diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index 164a9b2be..fa6606ba4 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -402,9 +402,9 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
                         return store->queryPathInfo(path);
                     },
                     [&](FixedOutputHashMethod & fohm) {
-                        if (!refs.empty())
-                            throw UnimplementedError("cannot yet have refs with flat or nar-hashed data");
-                        auto path = store->addToStoreFromDump(source, name, fohm.fileIngestionMethod, fohm.hashType, repair);
+                        // if (!refs.empty())
+                            // throw UnimplementedError("cannot yet have refs with flat or nar-hashed data");
+                        auto path = store->addToStoreFromDump(source, name, fohm.fileIngestionMethod, fohm.hashType, repair, refs);
                         return store->queryPathInfo(path);
                     },
                 }, contentAddressMethod);
diff --git a/src/libstore/legacy-ssh-store.cc b/src/libstore/legacy-ssh-store.cc
index 814960bb5..433ddc8e1 100644
--- a/src/libstore/legacy-ssh-store.cc
+++ b/src/libstore/legacy-ssh-store.cc
@@ -227,7 +227,7 @@ struct LegacySSHStore : public virtual LegacySSHStoreConfig, public virtual Stor
 
     StorePath addToStore(const string & name, const Path & srcPath,
         FileIngestionMethod method, HashType hashAlgo,
-        PathFilter & filter, RepairFlag repair) override
+        PathFilter & filter, RepairFlag repair, StorePathSet references) override
     { unsupported("addToStore"); }
 
     StorePath addTextToStore(const string & name, const string & s,
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 5b2490472..85f1de0b0 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -1302,7 +1302,7 @@ void LocalStore::addToStore(const ValidPathInfo & info, Source & source,
 
 
 StorePath LocalStore::addToStoreFromDump(Source & source0, const string & name,
-    FileIngestionMethod method, HashType hashAlgo, RepairFlag repair)
+    FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, StorePathSet references)
 {
     /* For computing the store path. */
     auto hashSink = std::make_unique<HashSink>(hashAlgo);
@@ -1405,6 +1405,7 @@ StorePath LocalStore::addToStoreFromDump(Source & source0, const string & name,
 
             ValidPathInfo info { dstPath, narHash.first };
             info.narSize = narHash.second;
+            info.references = references;
             info.ca = FixedOutputHash { .method = method, .hash = hash };
             registerValidPath(info);
         }
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index a01d48c4b..7a7329dd8 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -140,7 +140,7 @@ public:
         RepairFlag repair, CheckSigsFlag checkSigs) override;
 
     StorePath addToStoreFromDump(Source & dump, const string & name,
-        FileIngestionMethod method, HashType hashAlgo, RepairFlag repair) override;
+        FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, StorePathSet references) override;
 
     StorePath addTextToStore(const string & name, const string & s,
         const StorePathSet & references, RepairFlag repair) override;
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index fa5ea8af7..632dfcf21 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -578,9 +578,8 @@ ref<const ValidPathInfo> RemoteStore::addCAToStore(
 
 
 StorePath RemoteStore::addToStoreFromDump(Source & dump, const string & name,
-        FileIngestionMethod method, HashType hashType, RepairFlag repair)
+      FileIngestionMethod method, HashType hashType, RepairFlag repair, StorePathSet references)
 {
-    StorePathSet references;
     return addCAToStore(dump, name, FixedOutputHashMethod{ .fileIngestionMethod = method, .hashType = hashType }, references, repair)->path;
 }
 
diff --git a/src/libstore/remote-store.hh b/src/libstore/remote-store.hh
index ac1eaa19e..31eb1871a 100644
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@@ -73,7 +73,7 @@ public:
 
     /* Add a content-addressable store path. Does not support references. `dump` will be drained. */
     StorePath addToStoreFromDump(Source & dump, const string & name,
-        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair) override;
+        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair, StorePathSet references = StorePathSet()) override;
 
     void addToStore(const ValidPathInfo & info, Source & nar,
         RepairFlag repair, CheckSigsFlag checkSigs) override;
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index b5ff3dccf..84d6db297 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -237,7 +237,7 @@ StorePath Store::computeStorePathForText(const string & name, const string & s,
 
 
 StorePath Store::addToStore(const string & name, const Path & _srcPath,
-    FileIngestionMethod method, HashType hashAlgo, PathFilter & filter, RepairFlag repair)
+    FileIngestionMethod method, HashType hashAlgo, PathFilter & filter, RepairFlag repair, StorePathSet references)
 {
     Path srcPath(absPath(_srcPath));
     auto source = sinkToSource([&](Sink & sink) {
@@ -246,7 +246,7 @@ StorePath Store::addToStore(const string & name, const Path & _srcPath,
         else
             readFile(srcPath, sink);
     });
-    return addToStoreFromDump(*source, name, method, hashAlgo, repair);
+    return addToStoreFromDump(*source, name, method, hashAlgo, repair, references);
 }
 
 
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 54471bdf2..c4fdb176a 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -453,7 +453,7 @@ public:
        libutil/archive.hh). */
     virtual StorePath addToStore(const string & name, const Path & srcPath,
         FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256,
-        PathFilter & filter = defaultPathFilter, RepairFlag repair = NoRepair);
+        PathFilter & filter = defaultPathFilter, RepairFlag repair = NoRepair, StorePathSet references = StorePathSet());
 
     /* Copy the contents of a path to the store and register the
        validity the resulting path, using a constant amount of
@@ -469,7 +469,8 @@ public:
        `dump` may be drained */
     // FIXME: remove?
     virtual StorePath addToStoreFromDump(Source & dump, const string & name,
-        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair)
+        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair,
+        StorePathSet references = StorePathSet())
     { unsupported("addToStoreFromDump"); }
 
     /* Like addToStore, but the contents written to the output path is

From ba81e871b2b3a034f3e2eaa5242c98e2f253cdd5 Mon Sep 17 00:00:00 2001
From: Shay Bergmann <shaybergmann@gmail.com>
Date: Mon, 25 Oct 2021 21:13:35 +0000
Subject: [PATCH 144/567] toJSON: report error position for fancier output
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Given flake:

```nix
{ description = "nix json error provenance";
  inputs = {};
  outputs = { self }: {
    jsonFunction = _: "function";
    json = builtins.toJSON (_: "function");
  };
}

```
- Before:

```console
❯ nix eval --json .#jsonFunction
error: cannot convert a function to JSON
```

- After:

```console
❯ nix eval --json .#jsonFunction
error: cannot convert a function to JSON

       at /nix/store/b7imf1c2j4jnkg3ys7fsfbj02s5j0i4f-source/testflake/flake.nix:4:5:

            3|   outputs = { self }: {
            4|     jsonFunction = _: "function";
             |     ^
            5|     json = builtins.toJSON (_: "function");
```
---
 src/libexpr/primops.cc                 |  4 ++--
 src/libexpr/value-to-json.cc           | 24 +++++++++++++++---------
 src/libexpr/value-to-json.hh           |  4 ++--
 src/nix-env/nix-env.cc                 |  2 +-
 src/nix-instantiate/nix-instantiate.cc |  2 +-
 src/nix/eval.cc                        |  2 +-
 6 files changed, 22 insertions(+), 16 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 4e0eda7f3..aac741f90 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1008,7 +1008,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
                     if (i->name == state.sStructuredAttrs) continue;
 
                     auto placeholder(jsonObject->placeholder(key));
-                    printValueAsJSON(state, true, *i->value, placeholder, context);
+                    printValueAsJSON(state, true, *i->value, pos, placeholder, context);
 
                     if (i->name == state.sBuilder)
                         drv.builder = state.forceString(*i->value, context, posDrvName);
@@ -1687,7 +1687,7 @@ static void prim_toJSON(EvalState & state, const Pos & pos, Value * * args, Valu
 {
     std::ostringstream out;
     PathSet context;
-    printValueAsJSON(state, true, *args[0], out, context);
+    printValueAsJSON(state, true, *args[0], pos, out, context);
     mkString(v, out.str(), context);
 }
 
diff --git a/src/libexpr/value-to-json.cc b/src/libexpr/value-to-json.cc
index bfea24d40..7c28754f5 100644
--- a/src/libexpr/value-to-json.cc
+++ b/src/libexpr/value-to-json.cc
@@ -10,11 +10,11 @@
 namespace nix {
 
 void printValueAsJSON(EvalState & state, bool strict,
-    Value & v, JSONPlaceholder & out, PathSet & context)
+    Value & v, const Pos & pos, JSONPlaceholder & out, PathSet & context)
 {
     checkInterrupt();
 
-    if (strict) state.forceValue(v);
+    if (strict) state.forceValue(v, pos);
 
     switch (v.type()) {
 
@@ -54,10 +54,10 @@ void printValueAsJSON(EvalState & state, bool strict,
                 for (auto & j : names) {
                     Attr & a(*v.attrs->find(state.symbols.create(j)));
                     auto placeholder(obj.placeholder(j));
-                    printValueAsJSON(state, strict, *a.value, placeholder, context);
+                    printValueAsJSON(state, strict, *a.value, *a.pos, placeholder, context);
                 }
             } else
-                printValueAsJSON(state, strict, *i->value, out, context);
+                printValueAsJSON(state, strict, *i->value, *i->pos, out, context);
             break;
         }
 
@@ -65,7 +65,7 @@ void printValueAsJSON(EvalState & state, bool strict,
             auto list(out.list());
             for (unsigned int n = 0; n < v.listSize(); ++n) {
                 auto placeholder(list.placeholder());
-                printValueAsJSON(state, strict, *v.listElems()[n], placeholder, context);
+                printValueAsJSON(state, strict, *v.listElems()[n], noPos, placeholder, context);
             }
             break;
         }
@@ -79,18 +79,24 @@ void printValueAsJSON(EvalState & state, bool strict,
             break;
 
         case nThunk:
-            throw TypeError("cannot convert %1% to JSON", showType(v));
+            throw TypeError({
+                .msg = hintfmt("cannot convert %1% to JSON", showType(v)),
+                .errPos = pos
+            });
 
         case nFunction:
-            throw TypeError("cannot convert %1% to JSON", showType(v));
+            throw TypeError({
+                .msg = hintfmt("cannot convert %1% to JSON", showType(v)),
+                .errPos = pos
+            });
     }
 }
 
 void printValueAsJSON(EvalState & state, bool strict,
-    Value & v, std::ostream & str, PathSet & context)
+    Value & v, const Pos & pos, std::ostream & str, PathSet & context)
 {
     JSONPlaceholder out(str);
-    printValueAsJSON(state, strict, v, out, context);
+    printValueAsJSON(state, strict, v, pos, out, context);
 }
 
 void ExternalValueBase::printValueAsJSON(EvalState & state, bool strict,
diff --git a/src/libexpr/value-to-json.hh b/src/libexpr/value-to-json.hh
index 67fed6487..c2f797b29 100644
--- a/src/libexpr/value-to-json.hh
+++ b/src/libexpr/value-to-json.hh
@@ -11,9 +11,9 @@ namespace nix {
 class JSONPlaceholder;
 
 void printValueAsJSON(EvalState & state, bool strict,
-    Value & v, JSONPlaceholder & out, PathSet & context);
+    Value & v, const Pos & pos, JSONPlaceholder & out, PathSet & context);
 
 void printValueAsJSON(EvalState & state, bool strict,
-    Value & v, std::ostream & str, PathSet & context);
+    Value & v, const Pos & pos, std::ostream & str, PathSet & context);
 
 }
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index a86f55f84..4056d973d 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -879,7 +879,7 @@ static void queryJSON(Globals & globals, vector<DrvInfo> & elems)
                 placeholder.write(nullptr);
             } else {
                 PathSet context;
-                printValueAsJSON(*globals.state, true, *v, placeholder, context);
+                printValueAsJSON(*globals.state, true, *v, noPos, placeholder, context);
             }
         }
     }
diff --git a/src/nix-instantiate/nix-instantiate.cc b/src/nix-instantiate/nix-instantiate.cc
index 25d0fa3ba..ac48682c7 100644
--- a/src/nix-instantiate/nix-instantiate.cc
+++ b/src/nix-instantiate/nix-instantiate.cc
@@ -52,7 +52,7 @@ void processExpr(EvalState & state, const Strings & attrPaths,
             if (output == okXML)
                 printValueAsXML(state, strict, location, vRes, std::cout, context);
             else if (output == okJSON)
-                printValueAsJSON(state, strict, vRes, std::cout, context);
+                printValueAsJSON(state, strict, vRes, noPos, std::cout, context);
             else {
                 if (strict) state.forceValueDeep(vRes);
                 std::cout << vRes << std::endl;
diff --git a/src/nix/eval.cc b/src/nix/eval.cc
index 65d61e005..c7517cf79 100644
--- a/src/nix/eval.cc
+++ b/src/nix/eval.cc
@@ -112,7 +112,7 @@ struct CmdEval : MixJSON, InstallableCommand
 
         else if (json) {
             JSONPlaceholder jsonOut(std::cout);
-            printValueAsJSON(*state, true, *v, jsonOut, context);
+            printValueAsJSON(*state, true, *v, pos, jsonOut, context);
         }
 
         else {

From af99941279b80c962ec9cae3e5fa32976a3f5744 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Mon, 25 Oct 2021 15:53:01 +0200
Subject: [PATCH 145/567] Make experimental-features a proper type
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Rather than having them plain strings scattered through the whole
codebase, create an enum containing all the known experimental features.

This means that
- Nix can now `warn` when an unkwown experimental feature is passed
  (making it much nicer to spot typos and spot deprecated features)
- It’s now easy to remove a feature altogether (once the feature isn’t
  experimental anymore or is dropped) by just removing the field for the
  enum and letting the compiler point us to all the now invalid usages
  of it.
---
 src/build-remote/build-remote.cc            |  5 +-
 src/libcmd/installables.cc                  |  2 +-
 src/libexpr/eval.cc                         |  2 +-
 src/libexpr/eval.hh                         |  3 +-
 src/libexpr/flake/flake.cc                  |  4 +-
 src/libexpr/parser.y                        |  2 +-
 src/libexpr/primops.cc                      |  2 +-
 src/libexpr/primops/fetchTree.cc            | 10 ++--
 src/libstore/build/derivation-goal.cc       |  6 +--
 src/libstore/build/entry-points.cc          |  2 +-
 src/libstore/build/local-derivation-goal.cc |  6 +--
 src/libstore/daemon.cc                      |  2 +-
 src/libstore/derivations.cc                 |  2 +-
 src/libstore/derived-path.cc                |  2 +-
 src/libstore/globals.cc                     | 15 ++----
 src/libstore/globals.hh                     | 16 ++----
 src/libstore/local-store.cc                 | 10 ++--
 src/libstore/store-api.cc                   |  6 +--
 src/libutil/config.cc                       | 27 ++++++++++
 src/libutil/experimental-features.cc        | 55 ++++++++++++++++++++
 src/libutil/experimental-features.hh        | 56 +++++++++++++++++++++
 src/nix-build/nix-build.cc                  |  2 +-
 src/nix/develop.cc                          |  2 +-
 src/nix/flake.cc                            |  2 +-
 src/nix/main.cc                             |  2 +-
 src/nix/realisation.cc                      |  2 +-
 src/nix/sigs.cc                             |  2 +-
 tests/config.sh                             |  2 +-
 28 files changed, 188 insertions(+), 61 deletions(-)
 create mode 100644 src/libutil/experimental-features.cc
 create mode 100644 src/libutil/experimental-features.hh

diff --git a/src/build-remote/build-remote.cc b/src/build-remote/build-remote.cc
index 0559aeaf4..a6722a1f8 100644
--- a/src/build-remote/build-remote.cc
+++ b/src/build-remote/build-remote.cc
@@ -18,6 +18,7 @@
 #include "derivations.hh"
 #include "local-store.hh"
 #include "legacy.hh"
+#include "experimental-features.hh"
 
 using namespace nix;
 using std::cin;
@@ -295,7 +296,7 @@ connected:
 
         std::set<Realisation> missingRealisations;
         StorePathSet missingPaths;
-        if (settings.isExperimentalFeatureEnabled("ca-derivations") && !derivationHasKnownOutputPaths(drv.type())) {
+        if (settings.isExperimentalFeatureEnabled(Xp::CaDerivations) && !derivationHasKnownOutputPaths(drv.type())) {
             for (auto & outputName : wantedOutputs) {
                 auto thisOutputHash = outputHashes.at(outputName);
                 auto thisOutputId = DrvOutput{ thisOutputHash, outputName };
@@ -327,7 +328,7 @@ connected:
         for (auto & realisation : missingRealisations) {
             // Should hold, because if the feature isn't enabled the set
             // of missing realisations should be empty
-            settings.requireExperimentalFeature("ca-derivations");
+            settings.requireExperimentalFeature(Xp::CaDerivations);
             store->registerDrvOutput(realisation);
         }
 
diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index 0f0fcf39e..5758b52ad 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -714,7 +714,7 @@ BuiltPaths getBuiltPaths(ref<Store> evalStore, ref<Store> store, const DerivedPa
                                 "the derivation '%s' doesn't have an output named '%s'",
                                 store->printStorePath(bfd.drvPath), output);
                         if (settings.isExperimentalFeatureEnabled(
-                                "ca-derivations")) {
+                                Xp::CaDerivations)) {
                             auto outputId =
                                 DrvOutput{outputHashes.at(output), output};
                             auto realisation =
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 3ae05a8d8..db1e7e56d 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -466,7 +466,7 @@ EvalState::~EvalState()
 
 
 void EvalState::requireExperimentalFeatureOnEvaluation(
-    const std::string & feature,
+    const ExperimentalFeature & feature,
     const std::string_view fName,
     const Pos & pos)
 {
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 7cc16ef0a..69119599a 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -5,6 +5,7 @@
 #include "nixexpr.hh"
 #include "symbol-table.hh"
 #include "config.hh"
+#include "experimental-features.hh"
 
 #include <map>
 #include <optional>
@@ -141,7 +142,7 @@ public:
     ~EvalState();
 
     void requireExperimentalFeatureOnEvaluation(
-        const std::string & feature,
+        const ExperimentalFeature &,
         const std::string_view fName,
         const Pos & pos
     );
diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 43bfc3644..c9d848495 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -297,7 +297,7 @@ LockedFlake lockFlake(
     const FlakeRef & topRef,
     const LockFlags & lockFlags)
 {
-    settings.requireExperimentalFeature("flakes");
+    settings.requireExperimentalFeature(Xp::Flakes);
 
     FlakeCache flakeCache;
 
@@ -687,7 +687,7 @@ void callFlake(EvalState & state,
 
 static void prim_getFlake(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    state.requireExperimentalFeatureOnEvaluation("flakes", "builtins.getFlake", pos);
+    state.requireExperimentalFeatureOnEvaluation(Xp::Flakes, "builtins.getFlake", pos);
 
     auto flakeRefS = state.forceStringNoCtx(*args[0], pos);
     auto flakeRef = parseFlakeRef(flakeRefS, {}, true);
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 8a0a79c96..380afa6b7 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -418,7 +418,7 @@ expr_simple
           new ExprString(data->symbols.create(path)));
   }
   | URI {
-      static bool noURLLiterals = settings.isExperimentalFeatureEnabled("no-url-literals");
+      static bool noURLLiterals = settings.isExperimentalFeatureEnabled(Xp::NoUrlLiterals);
       if (noURLLiterals)
           throw ParseError({
               .msg = hintfmt("URL literals are disabled"),
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 4e0eda7f3..6b3cafec8 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -985,7 +985,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
             }
 
             if (i->name == state.sContentAddressed) {
-                settings.requireExperimentalFeature("ca-derivations");
+                settings.requireExperimentalFeature(Xp::CaDerivations);
                 contentAddressed = state.forceBool(*i->value, pos);
             }
 
diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index b00a79b7f..dacd78fd3 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -176,7 +176,7 @@ static void fetchTree(
 
 static void prim_fetchTree(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    settings.requireExperimentalFeature("flakes");
+    settings.requireExperimentalFeature(Xp::Flakes);
     fetchTree(state, pos, args, v, std::nullopt, FetchTreeParams { .allowNameArgument = false });
 }
 
@@ -290,7 +290,7 @@ static RegisterPrimOp primop_fetchTarball({
       The fetched tarball is cached for a certain amount of time (1 hour
       by default) in `~/.cache/nix/tarballs/`. You can change the cache
       timeout either on the command line with `--option tarball-ttl number
-      of seconds` or in the Nix configuration file with this option: ` 
+      of seconds` or in the Nix configuration file with this option: `
       number of seconds to cache `.
 
       Note that when obtaining the hash with ` nix-prefetch-url ` the
@@ -393,7 +393,7 @@ static RegisterPrimOp primop_fetchGit({
           ```
 
           > **Note**
-          > 
+          >
           > It is nice to always specify the branch which a revision
           > belongs to. Without the branch being specified, the fetcher
           > might fail if the default branch changes. Additionally, it can
@@ -430,12 +430,12 @@ static RegisterPrimOp primop_fetchGit({
           ```
 
           > **Note**
-          > 
+          >
           > Nix will refetch the branch in accordance with
           > the option `tarball-ttl`.
 
           > **Note**
-          > 
+          >
           > This behavior is disabled in *Pure evaluation mode*.
     )",
     .fun = prim_fetchGit,
diff --git a/src/libstore/build/derivation-goal.cc b/src/libstore/build/derivation-goal.cc
index 0907120db..67cf8b067 100644
--- a/src/libstore/build/derivation-goal.cc
+++ b/src/libstore/build/derivation-goal.cc
@@ -204,7 +204,7 @@ void DerivationGoal::haveDerivation()
     trace("have derivation");
 
     if (drv->type() == DerivationType::CAFloating)
-        settings.requireExperimentalFeature("ca-derivations");
+        settings.requireExperimentalFeature(Xp::CaDerivations);
 
     retrySubstitution = false;
 
@@ -453,7 +453,7 @@ void DerivationGoal::inputsRealised()
     if (useDerivation) {
         auto & fullDrv = *dynamic_cast<Derivation *>(drv.get());
 
-        if (settings.isExperimentalFeatureEnabled("ca-derivations") &&
+        if (settings.isExperimentalFeatureEnabled(Xp::CaDerivations) &&
             ((!fullDrv.inputDrvs.empty() && derivationIsCA(fullDrv.type()))
             || fullDrv.type() == DerivationType::DeferredInputAddressed)) {
             /* We are be able to resolve this derivation based on the
@@ -1273,7 +1273,7 @@ void DerivationGoal::checkPathValidity()
                     : PathStatus::Corrupt,
             };
         }
-        if (settings.isExperimentalFeatureEnabled("ca-derivations")) {
+        if (settings.isExperimentalFeatureEnabled(Xp::CaDerivations)) {
             auto drvOutput = DrvOutput{initialOutputs.at(i.first).outputHash, i.first};
             if (auto real = worker.store.queryRealisation(drvOutput)) {
                 info.known = {
diff --git a/src/libstore/build/entry-points.cc b/src/libstore/build/entry-points.cc
index 2b77e4354..065efc855 100644
--- a/src/libstore/build/entry-points.cc
+++ b/src/libstore/build/entry-points.cc
@@ -74,7 +74,7 @@ BuildResult Store::buildDerivation(const StorePath & drvPath, const BasicDerivat
                     outputId,
                     Realisation{ outputId, *staticOutput.second}
                     );
-        if (settings.isExperimentalFeatureEnabled("ca-derivations") && !derivationHasKnownOutputPaths(drv.type())) {
+        if (settings.isExperimentalFeatureEnabled(Xp::CaDerivations) && !derivationHasKnownOutputPaths(drv.type())) {
             auto realisation = this->queryRealisation(outputId);
             if (realisation)
                 result.builtOutputs.insert_or_assign(
diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 8d245f84a..fab6c3a08 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -1259,7 +1259,7 @@ struct RestrictedStore : public virtual RestrictedStoreConfig, public virtual Lo
             for (auto & [outputName, outputPath] : outputs)
                 if (wantOutput(outputName, bfd.outputs)) {
                     newPaths.insert(outputPath);
-                    if (settings.isExperimentalFeatureEnabled("ca-derivations")) {
+                    if (settings.isExperimentalFeatureEnabled(Xp::CaDerivations)) {
                         auto thisRealisation = next->queryRealisation(
                             DrvOutput{drvHashes.at(outputName), outputName}
                         );
@@ -1320,7 +1320,7 @@ struct RestrictedStore : public virtual RestrictedStoreConfig, public virtual Lo
 
 void LocalDerivationGoal::startDaemon()
 {
-    settings.requireExperimentalFeature("recursive-nix");
+    settings.requireExperimentalFeature(Xp::RecursiveNix);
 
     Store::Params params;
     params["path-info-cache-size"] = "0";
@@ -2561,7 +2561,7 @@ void LocalDerivationGoal::registerOutputs()
        that for floating CA derivations, which otherwise couldn't be cached,
        but it's fine to do in all cases. */
 
-    if (settings.isExperimentalFeatureEnabled("ca-derivations")) {
+    if (settings.isExperimentalFeatureEnabled(Xp::CaDerivations)) {
         for (auto& [outputName, newInfo] : infos) {
             auto thisRealisation = Realisation{
                 .id = DrvOutput{initialOutputs.at(outputName).outputHash,
diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index 164a9b2be..4e8a3c417 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -230,7 +230,7 @@ struct ClientSettings
                 else if (name == settings.experimentalFeatures.name) {
                     // We don’t want to forward the experimental features to
                     // the daemon, as that could cause some pretty weird stuff
-                    if (tokenizeString<Strings>(value) != settings.experimentalFeatures.get())
+                    if (parseFeatures(tokenizeString<StringSet>(value)) != settings.experimentalFeatures.get())
                         debug("Ignoring the client-specified experimental features");
                 }
                 else if (trusted
diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index ef8765841..b926bb711 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -187,7 +187,7 @@ static DerivationOutput parseDerivationOutput(const Store & store,
                 },
             };
         } else {
-            settings.requireExperimentalFeature("ca-derivations");
+            settings.requireExperimentalFeature(Xp::CaDerivations);
             assert(pathS == "");
             return DerivationOutput {
                 .output = DerivationOutputCAFloating {
diff --git a/src/libstore/derived-path.cc b/src/libstore/derived-path.cc
index e55af21e9..3d188e981 100644
--- a/src/libstore/derived-path.cc
+++ b/src/libstore/derived-path.cc
@@ -100,7 +100,7 @@ RealisedPath::Set BuiltPath::toRealisedPaths(Store & store) const
                     staticOutputHashes(store, store.readDerivation(p.drvPath));
                 for (auto& [outputName, outputPath] : p.outputs) {
                     if (settings.isExperimentalFeatureEnabled(
-                            "ca-derivations")) {
+                                Xp::CaDerivations)) {
                         auto thisRealisation = store.queryRealisation(
                             DrvOutput{drvHashes.at(outputName), outputName});
                         assert(thisRealisation);  // We’ve built it, so we must h
diff --git a/src/libstore/globals.cc b/src/libstore/globals.cc
index 4903d0922..9f1a88130 100644
--- a/src/libstore/globals.cc
+++ b/src/libstore/globals.cc
@@ -160,21 +160,16 @@ StringSet Settings::getDefaultExtraPlatforms()
     return extraPlatforms;
 }
 
-bool Settings::isExperimentalFeatureEnabled(const std::string & name)
+bool Settings::isExperimentalFeatureEnabled(const ExperimentalFeature & feature)
 {
     auto & f = experimentalFeatures.get();
-    return std::find(f.begin(), f.end(), name) != f.end();
+    return std::find(f.begin(), f.end(), feature) != f.end();
 }
 
-MissingExperimentalFeature::MissingExperimentalFeature(std::string feature)
-    : Error("experimental Nix feature '%1%' is disabled; use '--extra-experimental-features %1%' to override", feature)
-    , missingFeature(feature)
-    {}
-
-void Settings::requireExperimentalFeature(const std::string & name)
+void Settings::requireExperimentalFeature(const ExperimentalFeature & feature)
 {
-    if (!isExperimentalFeatureEnabled(name))
-        throw MissingExperimentalFeature(name);
+    if (!isExperimentalFeatureEnabled(feature))
+        throw MissingExperimentalFeature(feature);
 }
 
 bool Settings::isWSL1()
diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index 8784d5faf..165639261 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -3,6 +3,7 @@
 #include "types.hh"
 #include "config.hh"
 #include "util.hh"
+#include "experimental-features.hh"
 
 #include <map>
 #include <limits>
@@ -45,15 +46,6 @@ struct PluginFilesSetting : public BaseSetting<Paths>
     void set(const std::string & str, bool append = false) override;
 };
 
-class MissingExperimentalFeature: public Error
-{
-public:
-    std::string missingFeature;
-
-    MissingExperimentalFeature(std::string feature);
-    virtual const char* sname() const override { return "MissingExperimentalFeature"; }
-};
-
 class Settings : public Config {
 
     unsigned int getDefaultCores();
@@ -925,12 +917,12 @@ public:
           value.
           )"};
 
-    Setting<Strings> experimentalFeatures{this, {}, "experimental-features",
+    Setting<std::set<ExperimentalFeature>> experimentalFeatures{this, {}, "experimental-features",
         "Experimental Nix features to enable."};
 
-    bool isExperimentalFeatureEnabled(const std::string & name);
+    bool isExperimentalFeatureEnabled(const ExperimentalFeature &);
 
-    void requireExperimentalFeature(const std::string & name);
+    void requireExperimentalFeature(const ExperimentalFeature &);
 
     Setting<bool> allowDirty{this, true, "allow-dirty",
         "Whether to allow dirty Git/Mercurial trees."};
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 5b2490472..1e3b5482e 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -309,7 +309,7 @@ LocalStore::LocalStore(const Params & params)
 
     else openDB(*state, false);
 
-    if (settings.isExperimentalFeatureEnabled("ca-derivations")) {
+    if (settings.isExperimentalFeatureEnabled(Xp::CaDerivations)) {
         migrateCASchema(state->db, dbDir + "/ca-schema", globalLock);
     }
 
@@ -339,7 +339,7 @@ LocalStore::LocalStore(const Params & params)
     state->stmts->QueryPathFromHashPart.create(state->db,
         "select path from ValidPaths where path >= ? limit 1;");
     state->stmts->QueryValidPaths.create(state->db, "select path from ValidPaths");
-    if (settings.isExperimentalFeatureEnabled("ca-derivations")) {
+    if (settings.isExperimentalFeatureEnabled(Xp::CaDerivations)) {
         state->stmts->RegisterRealisedOutput.create(state->db,
             R"(
                 insert into Realisations (drvPath, outputName, outputPath, signatures)
@@ -708,7 +708,7 @@ void LocalStore::checkDerivationOutputs(const StorePath & drvPath, const Derivat
 
 void LocalStore::registerDrvOutput(const Realisation & info, CheckSigsFlag checkSigs)
 {
-    settings.requireExperimentalFeature("ca-derivations");
+    settings.requireExperimentalFeature(Xp::CaDerivations);
     if (checkSigs == NoCheckSigs || !realisationIsUntrusted(info))
         registerDrvOutput(info);
     else
@@ -717,7 +717,7 @@ void LocalStore::registerDrvOutput(const Realisation & info, CheckSigsFlag check
 
 void LocalStore::registerDrvOutput(const Realisation & info)
 {
-    settings.requireExperimentalFeature("ca-derivations");
+    settings.requireExperimentalFeature(Xp::CaDerivations);
     retrySQLite<void>([&]() {
         auto state(_state.lock());
         if (auto oldR = queryRealisation_(*state, info.id)) {
@@ -1003,7 +1003,7 @@ LocalStore::queryPartialDerivationOutputMap(const StorePath & path_)
         return outputs;
     });
 
-    if (!settings.isExperimentalFeatureEnabled("ca-derivations"))
+    if (!settings.isExperimentalFeatureEnabled(Xp::CaDerivations))
         return outputs;
 
     auto drv = readInvalidDerivation(path);
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index b5ff3dccf..3338cdc1b 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -355,7 +355,7 @@ ValidPathInfo Store::addToStoreSlow(std::string_view name, const Path & srcPath,
 StringSet StoreConfig::getDefaultSystemFeatures()
 {
     auto res = settings.systemFeatures.get();
-    if (settings.isExperimentalFeatureEnabled("ca-derivations"))
+    if (settings.isExperimentalFeatureEnabled(Xp::CaDerivations))
         res.insert("ca-derivations");
     return res;
 }
@@ -860,7 +860,7 @@ std::map<StorePath, StorePath> copyPaths(
     for (auto & path : paths) {
         storePaths.insert(path.path());
         if (auto realisation = std::get_if<Realisation>(&path.raw)) {
-            settings.requireExperimentalFeature("ca-derivations");
+            settings.requireExperimentalFeature(Xp::CaDerivations);
             toplevelRealisations.insert(*realisation);
         }
     }
@@ -892,7 +892,7 @@ std::map<StorePath, StorePath> copyPaths(
         // Don't fail if the remote doesn't support CA derivations is it might
         // not be within our control to change that, and we might still want
         // to at least copy the output paths.
-        if (e.missingFeature == "ca-derivations")
+        if (e.missingFeature == Xp::CaDerivations)
             ignoreException();
         else
             throw;
diff --git a/src/libutil/config.cc b/src/libutil/config.cc
index c247c7dae..026db6574 100644
--- a/src/libutil/config.cc
+++ b/src/libutil/config.cc
@@ -1,6 +1,7 @@
 #include "config.hh"
 #include "args.hh"
 #include "abstract-setting-to-json.hh"
+#include "experimental-features.hh"
 
 #include <nlohmann/json.hpp>
 
@@ -313,6 +314,31 @@ template<> std::string BaseSetting<StringSet>::to_string() const
     return concatStringsSep(" ", value);
 }
 
+template<> void BaseSetting<std::set<ExperimentalFeature>>::set(const std::string & str, bool append)
+{
+    if (!append) value.clear();
+    for (auto & s : tokenizeString<StringSet>(str)) {
+        auto thisXpFeature = parseExperimentalFeature(s);
+        if (thisXpFeature)
+            value.insert(thisXpFeature.value());
+        else
+            warn("Unknown experimental feature %s", s);
+    }
+}
+
+template<> bool BaseSetting<std::set<ExperimentalFeature>>::isAppendable()
+{
+    return true;
+}
+
+template<> std::string BaseSetting<std::set<ExperimentalFeature>>::to_string() const
+{
+    StringSet stringifiedXpFeatures;
+    for (auto & feature : value)
+        stringifiedXpFeatures.insert(std::string(showExperimentalFeature(feature)));
+    return concatStringsSep(" ", stringifiedXpFeatures);
+}
+
 template<> void BaseSetting<StringMap>::set(const std::string & str, bool append)
 {
     if (!append) value.clear();
@@ -348,6 +374,7 @@ template class BaseSetting<std::string>;
 template class BaseSetting<Strings>;
 template class BaseSetting<StringSet>;
 template class BaseSetting<StringMap>;
+template class BaseSetting<std::set<ExperimentalFeature>>;
 
 void PathSetting::set(const std::string & str, bool append)
 {
diff --git a/src/libutil/experimental-features.cc b/src/libutil/experimental-features.cc
new file mode 100644
index 000000000..d1235d8a4
--- /dev/null
+++ b/src/libutil/experimental-features.cc
@@ -0,0 +1,55 @@
+#include "experimental-features.hh"
+#include "nlohmann/json.hpp"
+
+namespace nix {
+
+std::map<ExperimentalFeature, std::string> stringifiedXpFeatures = {
+    { Xp::CaDerivations, "ca-derivations" },
+    { Xp::Flakes, "flakes" },
+    { Xp::NixCommand, "nix-command" },
+    { Xp::RecursiveNix, "recursive-nix" },
+    { Xp::NoUrlLiterals, "no-url-literals" },
+};
+
+const std::optional<ExperimentalFeature> parseExperimentalFeature(const std::string_view & name)
+{
+    using ReverseXpMap = std::map<std::string_view, ExperimentalFeature>;
+    static ReverseXpMap * reverseXpMap;
+    if (!reverseXpMap) {
+        reverseXpMap = new ReverseXpMap{};
+        for (auto & [feature, name] : stringifiedXpFeatures)
+            (*reverseXpMap)[name] = feature;
+    }
+
+    auto featureIter = reverseXpMap->find(name);
+    if (featureIter == reverseXpMap->end())
+        return std::nullopt;
+    return {featureIter->second};
+}
+
+std::string_view showExperimentalFeature(const ExperimentalFeature feature)
+{
+    return stringifiedXpFeatures.at(feature);
+}
+
+std::set<ExperimentalFeature> parseFeatures(const std::set<std::string> & rawFeatures)
+{
+    std::set<ExperimentalFeature> res;
+    for (auto & rawFeature : rawFeatures) {
+        if (auto feature = parseExperimentalFeature(rawFeature))
+            res.insert(*feature);
+    }
+    return res;
+}
+
+MissingExperimentalFeature::MissingExperimentalFeature(ExperimentalFeature feature)
+    : Error("experimental Nix feature '%1%' is disabled; use '--extra-experimental-features %1%' to override", showExperimentalFeature(feature))
+    , missingFeature(feature)
+    {}
+
+std::ostream & operator <<(std::ostream & str, const ExperimentalFeature & feature)
+{
+    return str << showExperimentalFeature(feature);
+}
+
+}
diff --git a/src/libutil/experimental-features.hh b/src/libutil/experimental-features.hh
new file mode 100644
index 000000000..291a58e32
--- /dev/null
+++ b/src/libutil/experimental-features.hh
@@ -0,0 +1,56 @@
+#pragma once
+
+#include "comparator.hh"
+#include "error.hh"
+#include "nlohmann/json_fwd.hpp"
+#include "types.hh"
+
+namespace nix {
+
+/**
+ * The list of available experimental features.
+ *
+ * If you update this, don’t forget to also change the map defining their
+ * string representation in the corresponding `.cc` file.
+ **/
+enum struct ExperimentalFeature
+{
+    CaDerivations,
+    Flakes,
+    NixCommand,
+    RecursiveNix,
+    NoUrlLiterals
+};
+
+/**
+ * Just because writing `ExperimentalFeature::CaDerivations` is way too long
+ */
+using Xp = ExperimentalFeature;
+
+const std::optional<ExperimentalFeature> parseExperimentalFeature(
+        const std::string_view & name);
+std::string_view showExperimentalFeature(const ExperimentalFeature);
+
+std::ostream & operator<<(
+        std::ostream & str,
+        const ExperimentalFeature & feature);
+
+/**
+ * Parse a set of strings to the corresponding set of experimental features,
+ * ignoring (but warning for) any unkwown feature.
+ */
+std::set<ExperimentalFeature> parseFeatures(const std::set<std::string> &);
+
+class MissingExperimentalFeature : public Error
+{
+public:
+    ExperimentalFeature missingFeature;
+
+    MissingExperimentalFeature(ExperimentalFeature);
+    virtual const char * sname() const override
+    {
+        return "MissingExperimentalFeature";
+    }
+};
+
+}
diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index 77594f046..73d93480e 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -401,7 +401,7 @@ static void main_nix_build(int argc, char * * argv)
 
         if (dryRun) return;
 
-        if (settings.isExperimentalFeatureEnabled("ca-derivations")) {
+        if (settings.isExperimentalFeatureEnabled(Xp::CaDerivations)) {
             auto resolvedDrv = drv.tryResolve(*store);
             assert(resolvedDrv && "Successfully resolved the derivation");
             drv = *resolvedDrv;
diff --git a/src/nix/develop.cc b/src/nix/develop.cc
index f22335023..5aad53919 100644
--- a/src/nix/develop.cc
+++ b/src/nix/develop.cc
@@ -195,7 +195,7 @@ static StorePath getDerivationEnvironment(ref<Store> store, ref<Store> evalStore
        'buildDerivation', but that's privileged. */
     drv.name += "-env";
     drv.inputSrcs.insert(std::move(getEnvShPath));
-    if (settings.isExperimentalFeatureEnabled("ca-derivations")) {
+    if (settings.isExperimentalFeatureEnabled(Xp::CaDerivations)) {
         for (auto & output : drv.outputs) {
             output.second = {
                 .output = DerivationOutputDeferred{},
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 7e4d23f6e..68bb76742 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -1138,7 +1138,7 @@ struct CmdFlake : NixMultiCommand
     {
         if (!command)
             throw UsageError("'nix flake' requires a sub-command.");
-        settings.requireExperimentalFeature("flakes");
+        settings.requireExperimentalFeature(Xp::Flakes);
         command->second->prepare();
         command->second->run();
     }
diff --git a/src/nix/main.cc b/src/nix/main.cc
index 2c3976689..1e033f4f2 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -337,7 +337,7 @@ void mainWrapped(int argc, char * * argv)
     if (args.command->first != "repl"
         && args.command->first != "doctor"
         && args.command->first != "upgrade-nix")
-        settings.requireExperimentalFeature("nix-command");
+        settings.requireExperimentalFeature(Xp::NixCommand);
 
     if (args.useNet && !haveInternet()) {
         warn("you don't have Internet access; disabling some network-dependent features");
diff --git a/src/nix/realisation.cc b/src/nix/realisation.cc
index dfa8ff449..c9a7157cd 100644
--- a/src/nix/realisation.cc
+++ b/src/nix/realisation.cc
@@ -46,7 +46,7 @@ struct CmdRealisationInfo : BuiltPathsCommand, MixJSON
 
     void run(ref<Store> store, BuiltPaths && paths) override
     {
-        settings.requireExperimentalFeature("ca-derivations");
+        settings.requireExperimentalFeature(Xp::CaDerivations);
         RealisedPath::Set realisations;
 
         for (auto & builtPath : paths) {
diff --git a/src/nix/sigs.cc b/src/nix/sigs.cc
index 43e0d9148..6a238efbe 100644
--- a/src/nix/sigs.cc
+++ b/src/nix/sigs.cc
@@ -219,7 +219,7 @@ struct CmdKey : NixMultiCommand
     {
         if (!command)
             throw UsageError("'nix flake' requires a sub-command.");
-        settings.requireExperimentalFeature("flakes");
+        settings.requireExperimentalFeature(Xp::Flakes);
         command->second->prepare();
         command->second->run();
     }
diff --git a/tests/config.sh b/tests/config.sh
index 01c78f2c3..3d0da3cef 100644
--- a/tests/config.sh
+++ b/tests/config.sh
@@ -50,4 +50,4 @@ exp_cores=$(nix show-config | grep '^cores' | cut -d '=' -f 2 | xargs)
 exp_features=$(nix show-config | grep '^experimental-features' | cut -d '=' -f 2 | xargs)
 [[ $prev != $exp_cores ]]
 [[ $exp_cores == "4242" ]]
-[[ $exp_features == "nix-command flakes" ]]
+[[ $exp_features == "flakes nix-command" ]]

From 9ce84c64c5820847a8084f31da5c5e2f549cbbcf Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 26 Oct 2021 14:21:24 +0200
Subject: [PATCH 146/567] Tweak fetchTree docs

---
 src/libexpr/primops/fetchTree.cc | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index dacd78fd3..e6becdafc 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -287,13 +287,13 @@ static RegisterPrimOp primop_fetchTarball({
       stdenv.mkDerivation { … }
       ```
 
-      The fetched tarball is cached for a certain amount of time (1 hour
-      by default) in `~/.cache/nix/tarballs/`. You can change the cache
-      timeout either on the command line with `--option tarball-ttl number
-      of seconds` or in the Nix configuration file with this option: `
-      number of seconds to cache `.
+      The fetched tarball is cached for a certain amount of time (1
+      hour by default) in `~/.cache/nix/tarballs/`. You can change the
+      cache timeout either on the command line with `--tarball-ttl`
+      *number-of-seconds* or in the Nix configuration file by adding
+      the line `tarball-ttl = ` *number-of-seconds*.
 
-      Note that when obtaining the hash with ` nix-prefetch-url ` the
+      Note that when obtaining the hash with `nix-prefetch-url` the
       option `--unpack` is required.
 
       This function can also verify the contents against a hash. In that

From 0d9e050ba719515620a2e320a7b6bba35f1d1df6 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 26 Oct 2021 14:29:48 +0200
Subject: [PATCH 147/567] parseExperimentalFeature(): Initialize atomically

---
 src/libutil/experimental-features.cc | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/src/libutil/experimental-features.cc b/src/libutil/experimental-features.cc
index d1235d8a4..b49f47e1d 100644
--- a/src/libutil/experimental-features.cc
+++ b/src/libutil/experimental-features.cc
@@ -1,4 +1,6 @@
 #include "experimental-features.hh"
+#include "util.hh"
+
 #include "nlohmann/json.hpp"
 
 namespace nix {
@@ -14,17 +16,19 @@ std::map<ExperimentalFeature, std::string> stringifiedXpFeatures = {
 const std::optional<ExperimentalFeature> parseExperimentalFeature(const std::string_view & name)
 {
     using ReverseXpMap = std::map<std::string_view, ExperimentalFeature>;
-    static ReverseXpMap * reverseXpMap;
-    if (!reverseXpMap) {
-        reverseXpMap = new ReverseXpMap{};
+
+    static auto reverseXpMap = []()
+    {
+        auto reverseXpMap = std::make_unique<ReverseXpMap>();
         for (auto & [feature, name] : stringifiedXpFeatures)
             (*reverseXpMap)[name] = feature;
-    }
+        return reverseXpMap;
+    }();
 
-    auto featureIter = reverseXpMap->find(name);
-    if (featureIter == reverseXpMap->end())
+    if (auto feature = get(*reverseXpMap, name))
+        return *feature;
+    else
         return std::nullopt;
-    return {featureIter->second};
 }
 
 std::string_view showExperimentalFeature(const ExperimentalFeature feature)
@@ -45,7 +49,7 @@ std::set<ExperimentalFeature> parseFeatures(const std::set<std::string> & rawFea
 MissingExperimentalFeature::MissingExperimentalFeature(ExperimentalFeature feature)
     : Error("experimental Nix feature '%1%' is disabled; use '--extra-experimental-features %1%' to override", showExperimentalFeature(feature))
     , missingFeature(feature)
-    {}
+{}
 
 std::ostream & operator <<(std::ostream & str, const ExperimentalFeature & feature)
 {

From 8919b81dad58af365919bcf3ded4117e973344d3 Mon Sep 17 00:00:00 2001
From: Timothy <git@timothyklim.com>
Date: Tue, 26 Oct 2021 20:02:37 +0700
Subject: [PATCH 148/567] Support building flakes from a Git repo url with
 submodules query parameter

---
 src/libfetchers/git.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libfetchers/git.cc b/src/libfetchers/git.cc
index 8468d2afc..a3f4e42a3 100644
--- a/src/libfetchers/git.cc
+++ b/src/libfetchers/git.cc
@@ -51,7 +51,7 @@ struct GitInputScheme : InputScheme
         for (auto &[name, value] : url.query) {
             if (name == "rev" || name == "ref")
                 attrs.emplace(name, value);
-            else if (name == "shallow")
+            else if (name == "shallow" || name == "submodules")
                 attrs.emplace(name, Explicit<bool> { value == "1" });
             else
                 url2.query.emplace(name, value);

From 769de259f0060d55ec8317c109cf12aa4003f7fe Mon Sep 17 00:00:00 2001
From: Shay Bergmann <shaybergmann@gmail.com>
Date: Tue, 26 Oct 2021 14:43:15 +0000
Subject: [PATCH 149/567] toJSON: pass pos in case of a list as well

---
 src/libexpr/value-to-json.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libexpr/value-to-json.cc b/src/libexpr/value-to-json.cc
index 7c28754f5..1c3849593 100644
--- a/src/libexpr/value-to-json.cc
+++ b/src/libexpr/value-to-json.cc
@@ -65,7 +65,7 @@ void printValueAsJSON(EvalState & state, bool strict,
             auto list(out.list());
             for (unsigned int n = 0; n < v.listSize(); ++n) {
                 auto placeholder(list.placeholder());
-                printValueAsJSON(state, strict, *v.listElems()[n], noPos, placeholder, context);
+                printValueAsJSON(state, strict, *v.listElems()[n], pos, placeholder, context);
             }
             break;
         }

From 13a7a24ba5213a536911320c0ee69faf26bc3f53 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 27 Oct 2021 13:01:56 +0200
Subject: [PATCH 150/567] Style

---
 src/libutil/config.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libutil/config.cc b/src/libutil/config.cc
index 026db6574..92ab265d3 100644
--- a/src/libutil/config.cc
+++ b/src/libutil/config.cc
@@ -322,7 +322,7 @@ template<> void BaseSetting<std::set<ExperimentalFeature>>::set(const std::strin
         if (thisXpFeature)
             value.insert(thisXpFeature.value());
         else
-            warn("Unknown experimental feature %s", s);
+            warn("unknown experimental feature '%s'", s);
     }
 }
 

From 6e684d1b8747ed0180489eacbdf920a82162e249 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 27 Oct 2021 13:09:13 +0200
Subject: [PATCH 151/567] daemon: Accept 'repeat' setting from untrusted users

Fixes #5352.
---
 src/libstore/daemon.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index 4e8a3c417..4b3465da3 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -235,6 +235,7 @@ struct ClientSettings
                 }
                 else if (trusted
                     || name == settings.buildTimeout.name
+                    || name == settings.buildRepeat.name
                     || name == "connect-timeout"
                     || (name == "builders" && value == ""))
                     settings.set(name, value);

From f2280749b1d58a56f91ad417b487e920ab23b8b6 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 27 Oct 2021 14:21:31 +0200
Subject: [PATCH 152/567] If max-jobs == 0, do preferLocalBuild on remote
 builders

---
 src/libstore/build/derivation-goal.cc | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/libstore/build/derivation-goal.cc b/src/libstore/build/derivation-goal.cc
index 67cf8b067..b924d23b2 100644
--- a/src/libstore/build/derivation-goal.cc
+++ b/src/libstore/build/derivation-goal.cc
@@ -616,7 +616,9 @@ void DerivationGoal::tryToBuild()
     /* Don't do a remote build if the derivation has the attribute
        `preferLocalBuild' set.  Also, check and repair modes are only
        supported for local builds. */
-    bool buildLocally = buildMode != bmNormal || parsedDrv->willBuildLocally(worker.store);
+    bool buildLocally =
+        (buildMode != bmNormal || parsedDrv->willBuildLocally(worker.store))
+        && settings.maxBuildJobs.get() != 0;
 
     if (!buildLocally) {
         switch (tryBuildHook()) {

From 1254e8753c4f07173b0463afad35d9020c6093d7 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 27 Oct 2021 14:25:13 +0200
Subject: [PATCH 153/567] build-remote: Implicitly add the 'builtin' system
 type to all machines

This makes 'nix-env -i --max-jobs 0' work with remote builders.
---
 src/build-remote/build-remote.cc | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/build-remote/build-remote.cc b/src/build-remote/build-remote.cc
index a6722a1f8..9d541b45d 100644
--- a/src/build-remote/build-remote.cc
+++ b/src/build-remote/build-remote.cc
@@ -131,11 +131,14 @@ static int main_build_remote(int argc, char * * argv)
                 for (auto & m : machines) {
                     debug("considering building on remote machine '%s'", m.storeUri);
 
-                    if (m.enabled && std::find(m.systemTypes.begin(),
-                            m.systemTypes.end(),
-                            neededSystem) != m.systemTypes.end() &&
+                    if (m.enabled
+                        && (neededSystem == "builtin"
+                            || std::find(m.systemTypes.begin(),
+                                m.systemTypes.end(),
+                                neededSystem) != m.systemTypes.end()) &&
                         m.allSupported(requiredFeatures) &&
-                        m.mandatoryMet(requiredFeatures)) {
+                        m.mandatoryMet(requiredFeatures))
+                    {
                         rightType = true;
                         AutoCloseFD free;
                         uint64_t load = 0;

From 9c6ac9eb0ee4191dd6ba2a9216e12d68bbc54f8b Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 27 Oct 2021 17:32:44 +0200
Subject: [PATCH 154/567] 2.4 release notes: Add some migration notes

---
 doc/manual/src/release-notes/rl-2.4.md | 33 +++++++++++++++++++++++---
 1 file changed, 30 insertions(+), 3 deletions(-)

diff --git a/doc/manual/src/release-notes/rl-2.4.md b/doc/manual/src/release-notes/rl-2.4.md
index def4a7b66..3c94e6740 100644
--- a/doc/manual/src/release-notes/rl-2.4.md
+++ b/doc/manual/src/release-notes/rl-2.4.md
@@ -1,4 +1,4 @@
-# Release 2.4 (2021-10-XX)
+# Release 2.4 (2021-11-01)
 
 This is the first release in more than two years and is the result of
 more than 2800 commits from 195 contributors since release 2.3.
@@ -286,8 +286,35 @@ more than 2800 commits from 195 contributors since release 2.3.
   to your `nix.conf` if you want to use it, or pass
   `--extra-experimental-features nix-command` on the command line.
 
-* The old `nix run` has been renamed to `nix shell` (and there is a
-  new `nix run` that does something else, as described above).
+* The `nix` command no longer has a syntax for referring to packages
+  in a channel. This means that the following no longer works:
+
+  > nix build nixpkgs.hello # Nix 2.3
+
+  Instead, you can either use the `#` syntax to select a package from
+  a flake, e.g.
+
+  > nix build nixpkgs#hello
+
+  Or, if you want to use the `nixpkgs` channel in the `NIX_PATH`
+  environment variable:
+
+  > nix build -f '<nixpkgs>' hello
+
+* The old `nix run` has been renamed to `nix shell`, while there is a
+  new `nix run` that runs a default command. So instead of
+
+  > nix run nixpkgs.hello -c hello # Nix 2.3
+
+  you should use
+
+  > nix shell nixpkgs#hello -c hello
+
+  or just
+
+  > nix run nixpkgs#hello
+
+  if the command you want to run has the same name as the package.
 
 * It is now an error to modify the `plugin-files` setting via a
   command-line flag that appears after the first non-flag argument to

From 5a160171d05c4bde95a7ae75c133912e08186a12 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 27 Oct 2021 18:14:12 +0200
Subject: [PATCH 155/567] Remove redundant 'warning:'

---
 src/libexpr/parser.y | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 380afa6b7..813ff2fc3 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -752,7 +752,7 @@ std::pair<bool, std::string> EvalState::resolveSearchPathElem(const SearchPathEl
             res = { true, path };
         else {
             logWarning({
-                .msg = hintfmt("warning: Nix search path entry '%1%' does not exist, ignoring", elem.second)
+                .msg = hintfmt("Nix search path entry '%1%' does not exist, ignoring", elem.second)
             });
             res = { false, "" };
         }

From a2473823d748b0249804d393c739622146954d02 Mon Sep 17 00:00:00 2001
From: figsoda <figsoda@pm.me>
Date: Wed, 27 Oct 2021 14:18:30 -0400
Subject: [PATCH 156/567] run: use pname as a fallback for main program

---
 src/nix/app.cc | 3 +++
 src/nix/run.md | 7 ++++---
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/nix/app.cc b/src/nix/app.cc
index 9719a65dd..2fcf4752c 100644
--- a/src/nix/app.cc
+++ b/src/nix/app.cc
@@ -83,11 +83,14 @@ UnresolvedApp Installable::toApp(EvalState & state)
         auto outPath = cursor->getAttr(state.sOutPath)->getString();
         auto outputName = cursor->getAttr(state.sOutputName)->getString();
         auto name = cursor->getAttr(state.sName)->getString();
+        auto aPname = cursor->maybeGetAttr("pname");
         auto aMeta = cursor->maybeGetAttr("meta");
         auto aMainProgram = aMeta ? aMeta->maybeGetAttr("mainProgram") : nullptr;
         auto mainProgram =
             aMainProgram
             ? aMainProgram->getString()
+            : aPname
+            ? aPname->getString()
             : DrvName(name).name;
         auto program = outPath + "/bin/" + mainProgram;
         return UnresolvedApp { App {
diff --git a/src/nix/run.md b/src/nix/run.md
index a76750376..697db9a96 100644
--- a/src/nix/run.md
+++ b/src/nix/run.md
@@ -44,9 +44,10 @@ program specified by the app definition.
 If *installable* evaluates to a derivation, it will try to execute the
 program `<out>/bin/<name>`, where *out* is the primary output store
 path of the derivation and *name* is the `meta.mainProgram` attribute
-of the derivation if it exists, and otherwise the name part of the
-value of the `name` attribute of the derivation (e.g. if `name` is set
-to `hello-1.10`, it will run `$out/bin/hello`).
+of the derivation if it exists, and otherwise the `pname` attribute of
+the derivation or the name part of the value of the `name` attribute of
+the derivation (e.g. if `name` is set to `hello-1.10`, it will run
+`$out/bin/hello`).
 
 # Flake output attributes
 

From 465a167c4347cd208f39670bad349fc61bb42d3d Mon Sep 17 00:00:00 2001
From: Shay Bergmann <shaybergmann@gmail.com>
Date: Wed, 27 Oct 2021 19:01:32 +0000
Subject: [PATCH 157/567] nix-instantiate: pass pos in the `--eval --json` code
 path

---
 src/nix-instantiate/nix-instantiate.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/nix-instantiate/nix-instantiate.cc b/src/nix-instantiate/nix-instantiate.cc
index ac48682c7..fbc697864 100644
--- a/src/nix-instantiate/nix-instantiate.cc
+++ b/src/nix-instantiate/nix-instantiate.cc
@@ -52,7 +52,7 @@ void processExpr(EvalState & state, const Strings & attrPaths,
             if (output == okXML)
                 printValueAsXML(state, strict, location, vRes, std::cout, context);
             else if (output == okJSON)
-                printValueAsJSON(state, strict, vRes, noPos, std::cout, context);
+                printValueAsJSON(state, strict, vRes, v.determinePos(noPos), std::cout, context);
             else {
                 if (strict) state.forceValueDeep(vRes);
                 std::cout << vRes << std::endl;

From a50c027ece2dc853109c7d2c2f10dd6581e2554d Mon Sep 17 00:00:00 2001
From: Shay Bergmann <shaybergmann@gmail.com>
Date: Wed, 27 Oct 2021 19:48:48 +0000
Subject: [PATCH 158/567] toJSON: improve pos accuracy, add trace

---
 src/libexpr/value-to-json.cc | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/src/libexpr/value-to-json.cc b/src/libexpr/value-to-json.cc
index 1c3849593..4d642c720 100644
--- a/src/libexpr/value-to-json.cc
+++ b/src/libexpr/value-to-json.cc
@@ -40,7 +40,7 @@ void printValueAsJSON(EvalState & state, bool strict,
             break;
 
         case nAttrs: {
-            auto maybeString = state.tryAttrsToString(noPos, v, context, false, false);
+            auto maybeString = state.tryAttrsToString(pos, v, context, false, false);
             if (maybeString) {
                 out.write(*maybeString);
                 break;
@@ -79,16 +79,12 @@ void printValueAsJSON(EvalState & state, bool strict,
             break;
 
         case nThunk:
-            throw TypeError({
-                .msg = hintfmt("cannot convert %1% to JSON", showType(v)),
-                .errPos = pos
-            });
-
         case nFunction:
-            throw TypeError({
+            auto e = TypeError({
                 .msg = hintfmt("cannot convert %1% to JSON", showType(v)),
-                .errPos = pos
+                .errPos = v.determinePos(pos)
             });
+            throw e.addTrace(pos, hintfmt("message for the trace"));
     }
 }
 

From bc4b7521f4a72de1d7a9db0b5be76885e0729e7c Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 28 Oct 2021 14:36:47 +0200
Subject: [PATCH 159/567] Rename rl-2.5.md to rl-next.md

Having a generically named file for release notes for the next release
makes things easier for PRs.
---
 doc/manual/src/SUMMARY.md.in                           | 3 ++-
 doc/manual/src/release-notes/{rl-2.5.md => rl-next.md} | 0
 2 files changed, 2 insertions(+), 1 deletion(-)
 rename doc/manual/src/release-notes/{rl-2.5.md => rl-next.md} (100%)

diff --git a/doc/manual/src/SUMMARY.md.in b/doc/manual/src/SUMMARY.md.in
index df9209c7d..3869f4791 100644
--- a/doc/manual/src/SUMMARY.md.in
+++ b/doc/manual/src/SUMMARY.md.in
@@ -70,7 +70,8 @@
   - [Hacking](contributing/hacking.md)
   - [CLI guideline](contributing/cli-guideline.md)
 - [Release Notes](release-notes/release-notes.md)
-  - [Release 2.4 (2021-XX-XX)](release-notes/rl-2.4.md)
+  - [Release X.Y (202?-??-??)](release-notes/rl-next.md)
+  - [Release 2.4 (2021-11-01)](release-notes/rl-2.4.md)
   - [Release 2.3 (2019-09-04)](release-notes/rl-2.3.md)
   - [Release 2.2 (2019-01-11)](release-notes/rl-2.2.md)
   - [Release 2.1 (2018-09-02)](release-notes/rl-2.1.md)
diff --git a/doc/manual/src/release-notes/rl-2.5.md b/doc/manual/src/release-notes/rl-next.md
similarity index 100%
rename from doc/manual/src/release-notes/rl-2.5.md
rename to doc/manual/src/release-notes/rl-next.md

From 22c35ea5b86d4aa450c3517506576ed377437574 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 28 Oct 2021 20:57:36 +0200
Subject: [PATCH 160/567] Remove unused variable

---
 src/libstore/gc.cc | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 5e8cbf8fc..13412e504 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -502,7 +502,6 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 
     std::thread serverThread([&]() {
         Sync<std::map<int, std::thread>> connections;
-        std::atomic_bool quit = false;
 
         Finally cleanup([&]() {
             debug("GC roots server shutting down");

From 33d04e8a8d9ab8f1736b7fe725e8851fbc41e1e7 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 28 Oct 2021 22:14:47 +0200
Subject: [PATCH 161/567] Use nix::connect() to connect to the garbage
 collector

---
 src/libstore/gc.cc | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 13412e504..8030c84f5 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -123,20 +123,10 @@ void LocalStore::addTempRoot(const StorePath & path)
            collector is running. So we have to connect to the garbage
            collector and inform it about our root. */
         if (!state->fdRootsSocket) {
-            state->fdRootsSocket = createUnixDomainSocket();
-
             auto socketPath = stateDir.get() + gcSocketPath;
-
             debug("connecting to '%s'", socketPath);
-
-            struct sockaddr_un addr;
-            addr.sun_family = AF_UNIX;
-            if (socketPath.size() + 1 >= sizeof(addr.sun_path))
-                throw Error("socket path '%s' is too long", socketPath);
-            strcpy(addr.sun_path, socketPath.c_str());
-
-            if (::connect(state->fdRootsSocket.get(), (struct sockaddr *) &addr, sizeof(addr)) == -1)
-                throw SysError("cannot connect to garbage collector at '%s'", socketPath);
+            state->fdRootsSocket = createUnixDomainSocket();
+            nix::connect(state->fdRootsSocket.get(), socketPath);
         }
 
         try {

From e6795c43504b763a03b21dccd6814b8703af357e Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 29 Oct 2021 14:45:13 +0200
Subject: [PATCH 162/567] Style

---
 src/libstore/machines.cc | 42 +++++++++++++++++++++++-----------------
 1 file changed, 24 insertions(+), 18 deletions(-)

diff --git a/src/libstore/machines.cc b/src/libstore/machines.cc
index 910e32a76..b6270a81b 100644
--- a/src/libstore/machines.cc
+++ b/src/libstore/machines.cc
@@ -39,7 +39,8 @@ Machine::Machine(decltype(storeUri) storeUri,
     sshPublicHostKey(sshPublicHostKey)
 {}
 
-bool Machine::allSupported(const std::set<string> & features) const {
+bool Machine::allSupported(const std::set<string> & features) const
+{
     return std::all_of(features.begin(), features.end(),
         [&](const string & feature) {
             return supportedFeatures.count(feature) ||
@@ -47,14 +48,16 @@ bool Machine::allSupported(const std::set<string> & features) const {
         });
 }
 
-bool Machine::mandatoryMet(const std::set<string> & features) const {
+bool Machine::mandatoryMet(const std::set<string> & features) const
+{
     return std::all_of(mandatoryFeatures.begin(), mandatoryFeatures.end(),
         [&](const string & feature) {
             return features.count(feature);
         });
 }
 
-ref<Store> Machine::openStore() const {
+ref<Store> Machine::openStore() const
+{
     Store::Params storeParams;
     if (hasPrefix(storeUri, "ssh://")) {
         storeParams["max-connections"] = "1";
@@ -83,7 +86,8 @@ ref<Store> Machine::openStore() const {
     return nix::openStore(storeUri, storeParams);
 }
 
-static std::vector<std::string> expandBuilderLines(const std::string& builders) {
+static std::vector<std::string> expandBuilderLines(const std::string & builders)
+{
     std::vector<std::string> result;
     for (auto line : tokenizeString<std::vector<string>>(builders, "\n;")) {
         trim(line);
@@ -111,7 +115,8 @@ static std::vector<std::string> expandBuilderLines(const std::string& builders)
     return result;
 }
 
-static Machine parseBuilderLine(const std::string& line) {
+static Machine parseBuilderLine(const std::string & line)
+{
     const auto tokens = tokenizeString<std::vector<string>>(line);
 
     auto isSet = [&](size_t fieldIndex) {
@@ -127,27 +132,28 @@ static Machine parseBuilderLine(const std::string& line) {
     };
 
     auto ensureBase64 = [&](size_t fieldIndex) {
-        const auto& str = tokens[fieldIndex];
+        const auto & str = tokens[fieldIndex];
         try {
             base64Decode(str);
-        } catch (const Error& e) {
+        } catch (const Error & e) {
             throw FormatError("bad machine specification: a column #%lu in a row: '%s' is not valid base64 string: %s", fieldIndex, line, e.what());
         }
         return str;
     };
 
-    if (!isSet(0)) {
-        throw FormatError("bad machine specification: store URI was not found at the first column of a row: '%s'", line);
-    }
+    if (!isSet(0))
+        throw FormatError("bad machine specification: store URL was not found at the first column of a row: '%s'", line);
 
-    return {tokens[0],
-            isSet(1) ? tokenizeString<std::vector<string>>(tokens[1], ",") : std::vector<string>{settings.thisSystem},
-            isSet(2) ? tokens[2] : "",
-            isSet(3) ? parseUnsignedIntField(3) : 1U,
-            isSet(4) ? parseUnsignedIntField(4) : 1U,
-            isSet(5) ? tokenizeString<std::set<string>>(tokens[5], ",") : std::set<string>{},
-            isSet(6) ? tokenizeString<std::set<string>>(tokens[6], ",") : std::set<string>{},
-            isSet(7) ? ensureBase64(7) : ""};
+    return {
+        tokens[0],
+        isSet(1) ? tokenizeString<std::vector<string>>(tokens[1], ",") : std::vector<string>{settings.thisSystem},
+        isSet(2) ? tokens[2] : "",
+        isSet(3) ? parseUnsignedIntField(3) : 1U,
+        isSet(4) ? parseUnsignedIntField(4) : 1U,
+        isSet(5) ? tokenizeString<std::set<string>>(tokens[5], ",") : std::set<string>{},
+        isSet(6) ? tokenizeString<std::set<string>>(tokens[6], ",") : std::set<string>{},
+        isSet(7) ? ensureBase64(7) : ""
+    };
 }
 
 static Machines parseBuilderLines(const std::vector<std::string>& builders) {

From 19148f1940c5f8b0125fc81f244411132031b883 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 29 Oct 2021 14:38:55 +0200
Subject: [PATCH 163/567] Apply a 60-minute timeout to the 'tests' workflow

---
 .github/workflows/test.yml | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 9105b5396..405ccb5ac 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -1,15 +1,18 @@
 name: "Test"
+
 on:
   pull_request:
   push:
+
 jobs:
+
   tests:
     needs: [check_cachix]
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest]
     runs-on: ${{ matrix.os }}
-
+    timeout-minutes: 60
     steps:
     - uses: actions/checkout@v2.3.5
       with:
@@ -23,6 +26,7 @@ jobs:
         signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
         authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
     - run: nix-build -A checks.$(nix-instantiate --eval -E '(builtins.currentSystem)')
+
   check_cachix:
     name: Cachix secret present for installer tests
     runs-on: ubuntu-latest
@@ -34,6 +38,7 @@ jobs:
         env:
           _CACHIX_SECRETS: ${{ secrets.CACHIX_SIGNING_KEY }}${{ secrets.CACHIX_AUTH_TOKEN }}
         run: echo "::set-output name=secret::${{ env._CACHIX_SECRETS != '' }}"
+
   installer:
     needs: [tests, check_cachix]
     if: github.event_name == 'push' && needs.check_cachix.outputs.secret == 'true'
@@ -53,6 +58,7 @@ jobs:
         authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
     - id: prepare-installer
       run: scripts/prepare-installer-for-github-actions
+
   installer_test:
     needs: [installer, check_cachix]
     if: github.event_name == 'push' && needs.check_cachix.outputs.secret == 'true'

From b459a3e85600e1d3a326278a823ce0bdf71fcc21 Mon Sep 17 00:00:00 2001
From: Sebastian Ullrich <sebasti@nullri.ch>
Date: Sat, 30 Oct 2021 12:25:59 +0200
Subject: [PATCH 164/567] git: extend cache dir lock over all mutating
 operations

---
 src/libfetchers/git.cc | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/src/libfetchers/git.cc b/src/libfetchers/git.cc
index 8468d2afc..a96642195 100644
--- a/src/libfetchers/git.cc
+++ b/src/libfetchers/git.cc
@@ -324,17 +324,13 @@ struct GitInputScheme : InputScheme
             Path cacheDir = getCacheDir() + "/nix/gitv3/" + hashString(htSHA256, actualUrl).to_string(Base32, false);
             repoDir = cacheDir;
 
-            Path cacheDirLock = cacheDir + ".lock";
             createDirs(dirOf(cacheDir));
-            AutoCloseFD lock = openLockFile(cacheDirLock, true);
-            lockFile(lock.get(), ltWrite, true);
+            PathLocks cacheDirLock({cacheDir + ".lock"});
 
             if (!pathExists(cacheDir)) {
                 runProgram("git", true, { "-c", "init.defaultBranch=" + gitInitialBranch, "init", "--bare", repoDir });
             }
 
-            deleteLockFile(cacheDirLock, lock.get());
-
             Path localRefFile =
                 input.getRef()->compare(0, 5, "refs/") == 0
                 ? cacheDir + "/" + *input.getRef()
@@ -399,6 +395,8 @@ struct GitInputScheme : InputScheme
 
             if (!input.getRev())
                 input.attrs.insert_or_assign("rev", Hash::parseAny(chomp(readFile(localRefFile)), htSHA1).gitRev());
+
+            // cache dir lock is removed at scope end; we will only use read-only operations on specific revisions in the remainder
         }
 
         bool isShallow = chomp(runProgram("git", true, { "-C", repoDir, "rev-parse", "--is-shallow-repository" })) == "true";

From 6a93e186f4838c13701b4f4551ddaa240ea1cf72 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 1 Nov 2021 22:44:07 +0100
Subject: [PATCH 165/567] Fix 2.4 migration examples

---
 doc/manual/src/release-notes/rl-2.4.md | 28 +++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/doc/manual/src/release-notes/rl-2.4.md b/doc/manual/src/release-notes/rl-2.4.md
index 3c94e6740..70b715053 100644
--- a/doc/manual/src/release-notes/rl-2.4.md
+++ b/doc/manual/src/release-notes/rl-2.4.md
@@ -281,7 +281,9 @@ more than 2800 commits from 195 contributors since release 2.3.
 * The `nix` command is now marked as an experimental feature. This
   means that you need to add
 
-  > experimental-features = nix-command
+  ```
+  experimental-features = nix-command
+  ```
 
   to your `nix.conf` if you want to use it, or pass
   `--extra-experimental-features nix-command` on the command line.
@@ -289,30 +291,42 @@ more than 2800 commits from 195 contributors since release 2.3.
 * The `nix` command no longer has a syntax for referring to packages
   in a channel. This means that the following no longer works:
 
-  > nix build nixpkgs.hello # Nix 2.3
+  ```console
+  nix build nixpkgs.hello # Nix 2.3
+  ```
 
   Instead, you can either use the `#` syntax to select a package from
   a flake, e.g.
 
-  > nix build nixpkgs#hello
+  ```console
+  nix build nixpkgs#hello
+  ```
 
   Or, if you want to use the `nixpkgs` channel in the `NIX_PATH`
   environment variable:
 
-  > nix build -f '<nixpkgs>' hello
+  ```console
+  nix build -f '<nixpkgs>' hello
+  ```
 
 * The old `nix run` has been renamed to `nix shell`, while there is a
   new `nix run` that runs a default command. So instead of
 
-  > nix run nixpkgs.hello -c hello # Nix 2.3
+  ```console
+  nix run nixpkgs.hello -c hello # Nix 2.3
+  ```
 
   you should use
 
-  > nix shell nixpkgs#hello -c hello
+  ```console
+  nix shell nixpkgs#hello -c hello
+  ```
 
   or just
 
-  > nix run nixpkgs#hello
+  ```console
+  nix run nixpkgs#hello
+  ```
 
   if the command you want to run has the same name as the package.
 

From 37b5460ebd1b29fe3c0bf43ff90e34b24045ae90 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 2 Nov 2021 11:53:06 +0100
Subject: [PATCH 166/567] Update release script

---
 maintainers/upload-release.pl | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/maintainers/upload-release.pl b/maintainers/upload-release.pl
index f2d6896db..18ab33424 100755
--- a/maintainers/upload-release.pl
+++ b/maintainers/upload-release.pl
@@ -12,7 +12,6 @@ use LWP::UserAgent;
 use Net::Amazon::S3;
 
 my $evalId = $ARGV[0] or die "Usage: $0 EVAL-ID\n";
-my $nixRev = $ARGV[1] or die; # FIXME
 
 my $releasesBucketName = "nix-releases";
 my $channelsBucketName = "nix-channels";
@@ -36,10 +35,11 @@ sub fetch {
 }
 
 my $evalUrl = "https://hydra.nixos.org/eval/$evalId";
-#my $evalInfo = decode_json(fetch($evalUrl, 'application/json'));
+my $evalInfo = decode_json(fetch($evalUrl, 'application/json'));
 #print Dumper($evalInfo);
-
-#my $nixRev = $evalInfo->{jobsetevalinputs}->{nix}->{revision} or die;
+my $flakeUrl = $evalInfo->{flake} or die;
+my $flakeInfo = decode_json(`nix flake metadata --json "$flakeUrl"` or die);
+my $nixRev = $flakeInfo->{revision} or die;
 
 my $buildInfo = decode_json(fetch("$evalUrl/job/build.x86_64-linux", 'application/json'));
 #print Dumper($buildInfo);
@@ -48,7 +48,7 @@ my $releaseName = $buildInfo->{nixname};
 $releaseName =~ /nix-(.*)$/ or die;
 my $version = $1;
 
-print STDERR "Nix revision is $nixRev, version is $version\n";
+print STDERR "Flake URL is $flakeUrl, Nix revision is $nixRev, version is $version\n";
 
 my $releaseDir = "nix/$releaseName";
 
@@ -143,12 +143,7 @@ if ($isLatest) {
     sub getStorePath {
         my ($jobName) = @_;
         my $buildInfo = decode_json(fetch("$evalUrl/job/$jobName", 'application/json'));
-        for my $product (values %{$buildInfo->{buildproducts}}) {
-            next unless $product->{type} eq "nix-build";
-            next if $product->{path} =~ /[a-z]+$/;
-            return $product->{path};
-        }
-        die;
+        return $buildInfo->{buildoutputs}->{out}->{path} or die "cannot get store path for '$jobName'";
     }
 
     write_file("$nixpkgsDir/nixos/modules/installer/tools/nix-fallback-paths.nix",

From b8532c9ff16582b793d880ddea54e8806bd50238 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Domen=20Ko=C5=BEar?= <domen@dev.si>
Date: Tue, 2 Nov 2021 08:24:17 -0600
Subject: [PATCH 167/567] install-nix-actionv@v14.1

---
 .github/workflows/test.yml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 405ccb5ac..cdf6ddb67 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -17,7 +17,7 @@ jobs:
     - uses: actions/checkout@v2.3.5
       with:
         fetch-depth: 0
-    - uses: cachix/install-nix-action@v14
+    - uses: cachix/install-nix-action@v14.1
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
     - uses: cachix/cachix-action@v10
       if: needs.check_cachix.outputs.secret == 'true'
@@ -50,7 +50,7 @@ jobs:
       with:
         fetch-depth: 0
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
-    - uses: cachix/install-nix-action@v14
+    - uses: cachix/install-nix-action@v14.1
     - uses: cachix/cachix-action@v10
       with:
         name: '${{ env.CACHIX_NAME }}'
@@ -69,7 +69,7 @@ jobs:
     steps:
     - uses: actions/checkout@v2.3.5
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
-    - uses: cachix/install-nix-action@v14
+    - uses: cachix/install-nix-action@v14.1
       with:
         install_url: '${{needs.installer.outputs.installerURL}}'
         install_options: "--tarball-url-prefix https://${{ env.CACHIX_NAME }}.cachix.org/serve"

From b61b307badd30149ddad6cde64d98ac2afb447a5 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 2 Nov 2021 13:52:35 +0100
Subject: [PATCH 168/567] Remove references to building from the source tarball

---
 doc/manual/src/installation/building-source.md    | 11 ++---------
 doc/manual/src/installation/installing-source.md  |  4 ++--
 doc/manual/src/installation/obtaining-source.md   | 15 +++++----------
 .../src/installation/prerequisites-source.md      |  8 +++-----
 4 files changed, 12 insertions(+), 26 deletions(-)

diff --git a/doc/manual/src/installation/building-source.md b/doc/manual/src/installation/building-source.md
index d21a51a82..ed1efffd8 100644
--- a/doc/manual/src/installation/building-source.md
+++ b/doc/manual/src/installation/building-source.md
@@ -1,9 +1,9 @@
 # Building Nix from Source
 
-After unpacking or checking out the Nix sources, issue the following
-commands:
+After cloning Nix's Git repository, issue the following commands:
 
 ```console
+$ ./bootstrap.sh
 $ ./configure options...
 $ make
 $ make install
@@ -11,13 +11,6 @@ $ make install
 
 Nix requires GNU Make so you may need to invoke `gmake` instead.
 
-When building from the Git repository, these should be preceded by the
-command:
-
-```console
-$ ./bootstrap.sh
-```
-
 The installation path can be specified by passing the `--prefix=prefix`
 to `configure`. The default installation directory is `/usr/local`. You
 can change this to any location you like. You must have write permission
diff --git a/doc/manual/src/installation/installing-source.md b/doc/manual/src/installation/installing-source.md
index e52d38a03..09b4e4887 100644
--- a/doc/manual/src/installation/installing-source.md
+++ b/doc/manual/src/installation/installing-source.md
@@ -1,4 +1,4 @@
 # Installing Nix from Source
 
-If no binary package is available, you can download and compile a source
-distribution.
+If no binary package is available or if you want to hack on Nix, you
+can build Nix from its Git repository.
diff --git a/doc/manual/src/installation/obtaining-source.md b/doc/manual/src/installation/obtaining-source.md
index 0a906e390..da05d243d 100644
--- a/doc/manual/src/installation/obtaining-source.md
+++ b/doc/manual/src/installation/obtaining-source.md
@@ -1,14 +1,9 @@
-# Obtaining a Source Distribution
+# Obtaining the Source
 
-The source tarball of the most recent stable release can be downloaded
-from the [Nix homepage](http://nixos.org/nix/download.html). You can
-also grab the [most recent development
-release](http://hydra.nixos.org/job/nix/master/release/latest-finished#tabs-constituents).
-
-Alternatively, the most recent sources of Nix can be obtained from its
-[Git repository](https://github.com/NixOS/nix). For example, the
-following command will check out the latest revision into a directory
-called `nix`:
+The most recent sources of Nix can be obtained from its [Git
+repository](https://github.com/NixOS/nix). For example, the following
+command will check out the latest revision into a directory called
+`nix`:
 
 ```console
 $ git clone https://github.com/NixOS/nix
diff --git a/doc/manual/src/installation/prerequisites-source.md b/doc/manual/src/installation/prerequisites-source.md
index 40cb79627..0323a4f55 100644
--- a/doc/manual/src/installation/prerequisites-source.md
+++ b/doc/manual/src/installation/prerequisites-source.md
@@ -2,9 +2,8 @@
 
   - GNU Autoconf (<https://www.gnu.org/software/autoconf/>) and the
     autoconf-archive macro collection
-    (<https://www.gnu.org/software/autoconf-archive/>). These are only
-    needed to run the bootstrap script, and are not necessary if your
-    source distribution came with a pre-built `./configure` script.
+    (<https://www.gnu.org/software/autoconf-archive/>). These are
+    needed to run the bootstrap script.
 
   - GNU Make.
 
@@ -52,8 +51,7 @@
     you need version 2.5.35, which is available on
     [SourceForge](http://lex.sourceforge.net/). Slightly older versions
     may also work, but ancient versions like the ubiquitous 2.5.4a
-    won't. Note that these are only required if you modify the parser or
-    when you are building from the Git repository.
+    won't.
 
   - The `libseccomp` is used to provide syscall filtering on Linux. This
     is an optional dependency and can be disabled passing a

From 447350fe0ea29d8c45e1d7436d8a148f01bf7a42 Mon Sep 17 00:00:00 2001
From: Anders Kaseorg <andersk@mit.edu>
Date: Mon, 1 Nov 2021 23:26:26 -0700
Subject: [PATCH 169/567] installer: Do not use echo -e in #!/bin/sh script

ShellCheck correctly warns:

In scripts/install-nix-from-closure.sh line 218:
                echo -e "\nif [ -e $p ]; then . $p; fi # added by Nix installer" >> "$fn"
                     ^-- SC3037: In POSIX sh, echo flags are undefined.

In scripts/install-nix-from-closure.sh line 229:
                echo -e "\nif [ -e $p ]; then . $p; fi # added by Nix installer" >> "$fn"
                     ^-- SC3037: In POSIX sh, echo flags are undefined.

Indeed, this actually breaks on Ubuntu where /bin/sh is dash.

Fixes #5458.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>
---
 scripts/install-nix-from-closure.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/scripts/install-nix-from-closure.sh b/scripts/install-nix-from-closure.sh
index 28d884c79..e25978da7 100644
--- a/scripts/install-nix-from-closure.sh
+++ b/scripts/install-nix-from-closure.sh
@@ -215,7 +215,7 @@ if [ -z "$NIX_INSTALLER_NO_MODIFY_PROFILE" ]; then
         if [ -w "$fn" ]; then
             if ! grep -q "$p" "$fn"; then
                 echo "modifying $fn..." >&2
-                echo -e "\nif [ -e $p ]; then . $p; fi # added by Nix installer" >> "$fn"
+                printf '\nif [ -e %s ]; then . %s; fi # added by Nix installer\n' "$p" "$p" >> "$fn"
             fi
             added=1
             break
@@ -226,7 +226,7 @@ if [ -z "$NIX_INSTALLER_NO_MODIFY_PROFILE" ]; then
         if [ -w "$fn" ]; then
             if ! grep -q "$p" "$fn"; then
                 echo "modifying $fn..." >&2
-                echo -e "\nif [ -e $p ]; then . $p; fi # added by Nix installer" >> "$fn"
+                printf '\nif [ -e %s ]; then . %s; fi # added by Nix installer\n' "$p" "$p" >> "$fn"
             fi
             added=1
             break

From 1968760f4aaebc3b80693f86ae9b163b0fa2c00d Mon Sep 17 00:00:00 2001
From: Simon Legner <Simon.Legner@gmail.com>
Date: Tue, 2 Nov 2021 22:00:08 +0100
Subject: [PATCH 170/567] command-ref/nix-shell: fix --pure, --keep

---
 doc/manual/src/command-ref/nix-shell.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/doc/manual/src/command-ref/nix-shell.md b/doc/manual/src/command-ref/nix-shell.md
index 0bd54b955..873311649 100644
--- a/doc/manual/src/command-ref/nix-shell.md
+++ b/doc/manual/src/command-ref/nix-shell.md
@@ -11,8 +11,8 @@
   [`--command` *cmd*]
   [`--run` *cmd*]
   [`--exclude` *regexp*]
-  [--pure]
-  [--keep *name*]
+  [`--pure`]
+  [`--keep` *name*]
   {{`--packages` | `-p`} {*packages* | *expressions*} … | [*path*]}
 
 # Description

From 5b2aa61f1b8fe253c963874ccb4700f6ff99526e Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Tue, 26 Oct 2021 16:55:57 +0200
Subject: [PATCH 171/567] =?UTF-8?q?Don=E2=80=99t=20require=20`ca-derivatio?=
 =?UTF-8?q?ns`=20when=20`=5F=5FcontentAddressed=20=3D=20false`?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

If we explicitely opt-out of it, there’s no need to require the
experimental feature
---
 src/libexpr/primops.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 6b3cafec8..f05cca169 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -985,8 +985,9 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
             }
 
             if (i->name == state.sContentAddressed) {
-                settings.requireExperimentalFeature(Xp::CaDerivations);
                 contentAddressed = state.forceBool(*i->value, pos);
+                if (contentAddressed)
+                    settings.requireExperimentalFeature(Xp::CaDerivations);
             }
 
             /* The `args' attribute is special: it supplies the

From 96670ed2163d3d1a296c9b053833362ec8c06985 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Wed, 27 Oct 2021 11:36:51 +0200
Subject: [PATCH 172/567] Expose an async interface for `queryRealisation`
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Doesn’t change much so far because everything is still using it
synchronously, but should allow the binary cache to fetch stuff in
parallel
---
 src/libstore/binary-cache-store.cc            | 30 ++------
 src/libstore/binary-cache-store.hh            |  3 +-
 .../build/drv-output-substitution-goal.hh     |  2 +-
 src/libstore/build/local-derivation-goal.cc   |  7 +-
 src/libstore/dummy-store.cc                   |  5 +-
 src/libstore/legacy-ssh-store.cc              |  3 +-
 src/libstore/local-store.cc                   | 23 +++++--
 src/libstore/local-store.hh                   |  3 +-
 src/libstore/remote-store.cc                  | 34 ++++++----
 src/libstore/remote-store.hh                  |  3 +-
 src/libstore/store-api.cc                     | 68 +++++++++++++++++++
 src/libstore/store-api.hh                     | 12 +++-
 12 files changed, 138 insertions(+), 55 deletions(-)

diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index 943132754..fb687db42 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -437,39 +437,19 @@ StorePath BinaryCacheStore::addTextToStore(const string & name, const string & s
     })->path;
 }
 
-std::optional<const Realisation> BinaryCacheStore::queryRealisation(const DrvOutput & id)
+void BinaryCacheStore::queryRealisationUncached(const DrvOutput & id,
+    Callback<std::shared_ptr<const Realisation>> callback) noexcept
 {
-    if (diskCache) {
-        auto [cacheOutcome, maybeCachedRealisation] =
-            diskCache->lookupRealisation(getUri(), id);
-        switch (cacheOutcome) {
-            case NarInfoDiskCache::oValid:
-                debug("Returning a cached realisation for %s", id.to_string());
-                return *maybeCachedRealisation;
-            case NarInfoDiskCache::oInvalid:
-                debug("Returning a cached missing realisation for %s", id.to_string());
-                return {};
-            case NarInfoDiskCache::oUnknown:
-                break;
-        }
-    }
-
     auto outputInfoFilePath = realisationsPrefix + "/" + id.to_string() + ".doi";
     auto rawOutputInfo = getFile(outputInfoFilePath);
 
     if (rawOutputInfo) {
         auto realisation = Realisation::fromJSON(
             nlohmann::json::parse(*rawOutputInfo), outputInfoFilePath);
-
-        if (diskCache)
-            diskCache->upsertRealisation(
-                getUri(), realisation);
-
-        return {realisation};
+        callback(std::make_shared<const Realisation>(realisation));
+        return;
     } else {
-        if (diskCache)
-            diskCache->upsertAbsentRealisation(getUri(), id);
-        return std::nullopt;
+        callback(nullptr);
     }
 }
 
diff --git a/src/libstore/binary-cache-store.hh b/src/libstore/binary-cache-store.hh
index 723f2e805..87ce610af 100644
--- a/src/libstore/binary-cache-store.hh
+++ b/src/libstore/binary-cache-store.hh
@@ -108,7 +108,8 @@ public:
 
     void registerDrvOutput(const Realisation & info) override;
 
-    std::optional<const Realisation> queryRealisation(const DrvOutput &) override;
+    void queryRealisationUncached(const DrvOutput &,
+        Callback<std::shared_ptr<const Realisation>> callback) noexcept override;
 
     void narFromPath(const StorePath & path, Sink & sink) override;
 
diff --git a/src/libstore/build/drv-output-substitution-goal.hh b/src/libstore/build/drv-output-substitution-goal.hh
index 63ab53d89..1b11a298e 100644
--- a/src/libstore/build/drv-output-substitution-goal.hh
+++ b/src/libstore/build/drv-output-substitution-goal.hh
@@ -20,7 +20,7 @@ private:
 
     // The realisation corresponding to the given output id.
     // Will be filled once we can get it.
-    std::optional<Realisation> outputInfo;
+    std::shared_ptr<const Realisation> outputInfo;
 
     /* The remaining substituters. */
     std::list<ref<Store>> subs;
diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 2182f0bb4..b076bf998 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -1224,13 +1224,14 @@ struct RestrictedStore : public virtual RestrictedStoreConfig, public virtual Lo
     // corresponds to an allowed derivation
     { throw Error("registerDrvOutput"); }
 
-    std::optional<const Realisation> queryRealisation(const DrvOutput & id) override
+    void queryRealisationUncached(const DrvOutput & id,
+        Callback<std::shared_ptr<const Realisation>> callback) noexcept override
     // XXX: This should probably be allowed if the realisation corresponds to
     // an allowed derivation
     {
         if (!goal.isAllowed(id))
-            throw InvalidPath("cannot query an unknown output id '%s' in recursive Nix", id.to_string());
-        return next->queryRealisation(id);
+            callback(nullptr);
+        next->queryRealisation(id, std::move(callback));
     }
 
     void buildPaths(const std::vector<DerivedPath> & paths, BuildMode buildMode, std::shared_ptr<Store> evalStore) override
diff --git a/src/libstore/dummy-store.cc b/src/libstore/dummy-store.cc
index 36c6e725c..62dc21c59 100644
--- a/src/libstore/dummy-store.cc
+++ b/src/libstore/dummy-store.cc
@@ -50,8 +50,9 @@ struct DummyStore : public virtual DummyStoreConfig, public virtual Store
     void narFromPath(const StorePath & path, Sink & sink) override
     { unsupported("narFromPath"); }
 
-    std::optional<const Realisation> queryRealisation(const DrvOutput&) override
-    { unsupported("queryRealisation"); }
+    void queryRealisationUncached(const DrvOutput &,
+        Callback<std::shared_ptr<const Realisation>> callback) noexcept override
+    { callback(nullptr); }
 };
 
 static RegisterStoreImplementation<DummyStore, DummyStoreConfig> regDummyStore;
diff --git a/src/libstore/legacy-ssh-store.cc b/src/libstore/legacy-ssh-store.cc
index 814960bb5..c9c3be1b0 100644
--- a/src/libstore/legacy-ssh-store.cc
+++ b/src/libstore/legacy-ssh-store.cc
@@ -367,7 +367,8 @@ public:
         return conn->remoteVersion;
     }
 
-    std::optional<const Realisation> queryRealisation(const DrvOutput&) override
+    void queryRealisationUncached(const DrvOutput &,
+        Callback<std::shared_ptr<const Realisation>> callback) noexcept override
     // TODO: Implement
     { unsupported("queryRealisation"); }
 };
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 225a19e1e..92d8c36ac 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -1838,13 +1838,24 @@ std::optional<const Realisation> LocalStore::queryRealisation_(
     return { res };
 }
 
-std::optional<const Realisation>
-LocalStore::queryRealisation(const DrvOutput & id)
+void LocalStore::queryRealisationUncached(const DrvOutput & id,
+        Callback<std::shared_ptr<const Realisation>> callback) noexcept
 {
-    return retrySQLite<std::optional<const Realisation>>([&]() {
-        auto state(_state.lock());
-        return queryRealisation_(*state, id);
-    });
+    try {
+        auto maybeRealisation
+            = retrySQLite<std::optional<const Realisation>>([&]() {
+                  auto state(_state.lock());
+                  return queryRealisation_(*state, id);
+              });
+        if (maybeRealisation)
+            callback(
+                std::make_shared<const Realisation>(maybeRealisation.value()));
+        else
+            callback(nullptr);
+
+    } catch (...) {
+        callback.rethrow();
+    }
 }
 
 FixedOutputHash LocalStore::hashCAPath(
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 301425eb1..b172e897a 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -207,7 +207,8 @@ public:
 
     std::optional<const Realisation> queryRealisation_(State & state, const DrvOutput & id);
     std::optional<std::pair<int64_t, Realisation>> queryRealisationCore_(State & state, const DrvOutput & id);
-    std::optional<const Realisation> queryRealisation(const DrvOutput&) override;
+    void queryRealisationUncached(const DrvOutput&,
+        Callback<std::shared_ptr<const Realisation>> callback) noexcept override;
 
 private:
 
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index 7decc059c..9c00d6212 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -677,23 +677,33 @@ void RemoteStore::registerDrvOutput(const Realisation & info)
     conn.processStderr();
 }
 
-std::optional<const Realisation> RemoteStore::queryRealisation(const DrvOutput & id)
+void RemoteStore::queryRealisationUncached(const DrvOutput & id,
+    Callback<std::shared_ptr<const Realisation>> callback) noexcept
 {
     auto conn(getConnection());
     conn->to << wopQueryRealisation;
     conn->to << id.to_string();
     conn.processStderr();
-    if (GET_PROTOCOL_MINOR(conn->daemonVersion) < 31) {
-        auto outPaths = worker_proto::read(*this, conn->from, Phantom<std::set<StorePath>>{});
-        if (outPaths.empty())
-            return std::nullopt;
-        return {Realisation{.id = id, .outPath = *outPaths.begin()}};
-    } else {
-        auto realisations = worker_proto::read(*this, conn->from, Phantom<std::set<Realisation>>{});
-        if (realisations.empty())
-            return std::nullopt;
-        return *realisations.begin();
-    }
+
+    auto real = [&]() -> std::shared_ptr<const Realisation> {
+        if (GET_PROTOCOL_MINOR(conn->daemonVersion) < 31) {
+            auto outPaths = worker_proto::read(
+                *this, conn->from, Phantom<std::set<StorePath>> {});
+            if (outPaths.empty())
+                return nullptr;
+            return std::make_shared<const Realisation>(Realisation { .id = id, .outPath = *outPaths.begin() });
+        } else {
+            auto realisations = worker_proto::read(
+                *this, conn->from, Phantom<std::set<Realisation>> {});
+            if (realisations.empty())
+                return nullptr;
+            return std::make_shared<const Realisation>(*realisations.begin());
+        }
+    }();
+
+    try {
+        callback(std::shared_ptr<const Realisation>(real));
+    } catch (...) { return callback.rethrow(); }
 }
 
 static void writeDerivedPaths(RemoteStore & store, ConnectionHandle & conn, const std::vector<DerivedPath> & reqs)
diff --git a/src/libstore/remote-store.hh b/src/libstore/remote-store.hh
index a3036e6b0..79d031a24 100644
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@@ -88,7 +88,8 @@ public:
 
     void registerDrvOutput(const Realisation & info) override;
 
-    std::optional<const Realisation> queryRealisation(const DrvOutput &) override;
+    void queryRealisationUncached(const DrvOutput &,
+        Callback<std::shared_ptr<const Realisation>> callback) noexcept override;
 
     void buildPaths(const std::vector<DerivedPath> & paths, BuildMode buildMode, std::shared_ptr<Store> evalStore) override;
 
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index b0d3688ce..b8d702200 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -542,6 +542,74 @@ void Store::queryPathInfo(const StorePath & storePath,
         }});
 }
 
+void Store::queryRealisation(const DrvOutput & id,
+        Callback<std::shared_ptr<const Realisation>> callback) noexcept
+{
+
+    try {
+        if (diskCache) {
+            auto [cacheOutcome, maybeCachedRealisation]
+                = diskCache->lookupRealisation(getUri(), id);
+            switch (cacheOutcome) {
+            case NarInfoDiskCache::oValid:
+                debug("Returning a cached realisation for %s", id.to_string());
+                callback(maybeCachedRealisation);
+                return;
+            case NarInfoDiskCache::oInvalid:
+                debug(
+                    "Returning a cached missing realisation for %s",
+                    id.to_string());
+                callback(nullptr);
+                return;
+            case NarInfoDiskCache::oUnknown:
+                break;
+            }
+        }
+    } catch (...) {
+        return callback.rethrow();
+    }
+
+    auto callbackPtr
+        = std::make_shared<decltype(callback)>(std::move(callback));
+
+    queryRealisationUncached(
+        id,
+        { [this, id, callbackPtr](
+              std::future<std::shared_ptr<const Realisation>> fut) {
+            try {
+                auto info = fut.get();
+
+                if (diskCache) {
+                    if (info)
+                        diskCache->upsertRealisation(getUri(), *info);
+                    else
+                        diskCache->upsertAbsentRealisation(getUri(), id);
+                }
+
+                (*callbackPtr)(std::shared_ptr<const Realisation>(info));
+
+            } catch (...) {
+                callbackPtr->rethrow();
+            }
+        } });
+}
+
+std::shared_ptr<const Realisation> Store::queryRealisation(const DrvOutput & id)
+{
+    using RealPtr = std::shared_ptr<const Realisation>;
+    std::promise<RealPtr> promise;
+
+    queryRealisation(id,
+        {[&](std::future<RealPtr> result) {
+            try {
+                promise.set_value(result.get());
+            } catch (...) {
+                promise.set_exception(std::current_exception());
+            }
+        }});
+
+    return promise.get_future().get();
+}
 
 void Store::substitutePaths(const StorePathSet & paths)
 {
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 7d02340df..8adcf276f 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -369,6 +369,14 @@ public:
     void queryPathInfo(const StorePath & path,
         Callback<ref<const ValidPathInfo>> callback) noexcept;
 
+    /* Query the information about a realisation. */
+    std::shared_ptr<const Realisation> queryRealisation(const DrvOutput &);
+
+    /* Asynchronous version of queryRealisation(). */
+    void queryRealisation(const DrvOutput &,
+        Callback<std::shared_ptr<const Realisation>> callback) noexcept;
+
+
     /* Check whether the given valid path info is sufficiently attested, by
        either being signed by a trusted public key or content-addressed, in
        order to be included in the given store.
@@ -393,11 +401,11 @@ protected:
 
     virtual void queryPathInfoUncached(const StorePath & path,
         Callback<std::shared_ptr<const ValidPathInfo>> callback) noexcept = 0;
+    virtual void queryRealisationUncached(const DrvOutput &,
+        Callback<std::shared_ptr<const Realisation>> callback) noexcept = 0;
 
 public:
 
-    virtual std::optional<const Realisation> queryRealisation(const DrvOutput &) = 0;
-
     /* Queries the set of incoming FS references for a store path.
        The result is not cleared. */
     virtual void queryReferrers(const StorePath & path, StorePathSet & referrers)

From fbc70034b3f5bd82d0cfe24a9a82a6d00237b46e Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Wed, 27 Oct 2021 11:50:57 +0200
Subject: [PATCH 173/567] Make the realisation fetching from binary caches
 async

That way we can fetch several realisations from the same cache in
parallel
---
 src/libstore/binary-cache-store.cc | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index fb687db42..08dde0c54 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -441,16 +441,25 @@ void BinaryCacheStore::queryRealisationUncached(const DrvOutput & id,
     Callback<std::shared_ptr<const Realisation>> callback) noexcept
 {
     auto outputInfoFilePath = realisationsPrefix + "/" + id.to_string() + ".doi";
-    auto rawOutputInfo = getFile(outputInfoFilePath);
 
-    if (rawOutputInfo) {
-        auto realisation = Realisation::fromJSON(
-            nlohmann::json::parse(*rawOutputInfo), outputInfoFilePath);
-        callback(std::make_shared<const Realisation>(realisation));
-        return;
-    } else {
-        callback(nullptr);
-    }
+    auto callbackPtr = std::make_shared<decltype(callback)>(std::move(callback));
+
+    Callback<std::shared_ptr<std::string>> newCallback = {
+        [=](std::future<std::shared_ptr<std::string>> fut) {
+            try {
+                auto data = fut.get();
+                if (!data) return (*callbackPtr)(nullptr);
+
+                auto realisation = Realisation::fromJSON(
+                    nlohmann::json::parse(*data), outputInfoFilePath);
+                return (*callbackPtr)(std::make_shared<const Realisation>(realisation));
+            } catch (...) {
+                callbackPtr->rethrow();
+            }
+        }
+    };
+
+    getFile(outputInfoFilePath, std::move(newCallback));
 }
 
 void BinaryCacheStore::registerDrvOutput(const Realisation& info) {

From f4c869977c391b31eb4f20486f7da03b026e2401 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Thu, 28 Oct 2021 16:43:54 +0200
Subject: [PATCH 174/567] Make the DrvOutputSubstitutionGoal more async

---
 .../build/drv-output-substitution-goal.cc     | 44 +++++++++++++++++--
 .../build/drv-output-substitution-goal.hh     | 12 ++++-
 2 files changed, 51 insertions(+), 5 deletions(-)

diff --git a/src/libstore/build/drv-output-substitution-goal.cc b/src/libstore/build/drv-output-substitution-goal.cc
index be270d079..b9602e696 100644
--- a/src/libstore/build/drv-output-substitution-goal.cc
+++ b/src/libstore/build/drv-output-substitution-goal.cc
@@ -1,6 +1,8 @@
 #include "drv-output-substitution-goal.hh"
+#include "finally.hh"
 #include "worker.hh"
 #include "substitution-goal.hh"
+#include "callback.hh"
 
 namespace nix {
 
@@ -50,14 +52,42 @@ void DrvOutputSubstitutionGoal::tryNext()
         return;
     }
 
-    auto sub = subs.front();
+    sub = subs.front();
     subs.pop_front();
 
     // FIXME: Make async
-    outputInfo = sub->queryRealisation(id);
+    // outputInfo = sub->queryRealisation(id);
+    outPipe.create();
+    promise = decltype(promise)();
+
+    sub->queryRealisation(
+        id, { [&](std::future<std::shared_ptr<const Realisation>> res) {
+            try {
+                Finally updateStats([this]() { outPipe.writeSide.close(); });
+                promise.set_value(res.get());
+            } catch (...) {
+                promise.set_exception(std::current_exception());
+            }
+        } });
+
+    worker.childStarted(shared_from_this(), {outPipe.readSide.get()}, true, false);
+
+    state = &DrvOutputSubstitutionGoal::realisationFetched;
+}
+
+void DrvOutputSubstitutionGoal::realisationFetched()
+{
+    worker.childTerminated(this);
+
+    try {
+        outputInfo = promise.get_future().get();
+    } catch (std::exception & e) {
+        printError(e.what());
+        substituterFailed = true;
+    }
+
     if (!outputInfo) {
-        tryNext();
-        return;
+        return tryNext();
     }
 
     for (const auto & [depId, depPath] : outputInfo->dependentRealisations) {
@@ -119,4 +149,10 @@ void DrvOutputSubstitutionGoal::work()
     (this->*state)();
 }
 
+void DrvOutputSubstitutionGoal::handleEOF(int fd)
+{
+    if (fd == outPipe.readSide.get()) worker.wakeUp(shared_from_this());
+}
+
+
 }
diff --git a/src/libstore/build/drv-output-substitution-goal.hh b/src/libstore/build/drv-output-substitution-goal.hh
index 1b11a298e..67ae2624a 100644
--- a/src/libstore/build/drv-output-substitution-goal.hh
+++ b/src/libstore/build/drv-output-substitution-goal.hh
@@ -3,6 +3,8 @@
 #include "store-api.hh"
 #include "goal.hh"
 #include "realisation.hh"
+#include <thread>
+#include <future>
 
 namespace nix {
 
@@ -25,6 +27,13 @@ private:
     /* The remaining substituters. */
     std::list<ref<Store>> subs;
 
+    /* The current substituter. */
+    std::shared_ptr<Store> sub;
+
+    Pipe outPipe;
+    std::thread thr;
+    std::promise<std::shared_ptr<const Realisation>> promise;
+
     /* Whether a substituter failed. */
     bool substituterFailed = false;
 
@@ -36,6 +45,7 @@ public:
 
     void init();
     void tryNext();
+    void realisationFetched();
     void outPathValid();
     void finished();
 
@@ -44,7 +54,7 @@ public:
     string key() override;
 
     void work() override;
-
+    void handleEOF(int fd) override;
 };
 
 }

From 14fcf1727759f8eaf88a805cbe2251fbe9920edb Mon Sep 17 00:00:00 2001
From: Doron Behar <doron.behar@gmail.com>
Date: Wed, 3 Nov 2021 14:10:16 +0200
Subject: [PATCH 175/567] libstore: Use unix-dotfile vfs if useSQLiteWAL is
 false

---
 src/libstore/sqlite.cc | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/libstore/sqlite.cc b/src/libstore/sqlite.cc
index 447b4179b..1d6baf02d 100644
--- a/src/libstore/sqlite.cc
+++ b/src/libstore/sqlite.cc
@@ -1,4 +1,5 @@
 #include "sqlite.hh"
+#include "globals.hh"
 #include "util.hh"
 
 #include <sqlite3.h>
@@ -27,8 +28,12 @@ namespace nix {
 
 SQLite::SQLite(const Path & path, bool create)
 {
+    // useSQLiteWAL also indicates what virtual file system we need.  Using
+    // `unix-dotfile` is needed on NFS file systems and on Windows' Subsystem
+    // for Linux (WSL) where useSQLiteWAL should be false by default.
+    const char *vfs = settings.useSQLiteWAL ? 0 : "unix-dotfile";
     if (sqlite3_open_v2(path.c_str(), &db,
-            SQLITE_OPEN_READWRITE | (create ? SQLITE_OPEN_CREATE : 0), 0) != SQLITE_OK)
+            SQLITE_OPEN_READWRITE | (create ? SQLITE_OPEN_CREATE : 0), vfs) != SQLITE_OK)
         throw Error("cannot open SQLite database '%s'", path);
 
     if (sqlite3_busy_timeout(db, 60 * 60 * 1000) != SQLITE_OK)

From 3f070cc417ab71cf8b20d5a9db62ff515d209846 Mon Sep 17 00:00:00 2001
From: Christopher League <league@contrapunctus.net>
Date: Wed, 3 Nov 2021 09:25:27 -0400
Subject: [PATCH 176/567] In checkOverlay, accept underscored names for
 final/prev args.

Resolves #4416.
---
 src/nix/flake.cc | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 68bb76742..5855348ac 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -346,10 +346,14 @@ struct CmdFlakeCheck : FlakeCommand
         auto checkOverlay = [&](const std::string & attrPath, Value & v, const Pos & pos) {
             try {
                 state->forceValue(v, pos);
-                if (!v.isLambda() || v.lambda.fun->hasFormals() || std::string(v.lambda.fun->arg) != "final")
+                if (!v.isLambda() || v.lambda.fun->hasFormals() ||
+                    (std::string(v.lambda.fun->arg) != "final" &&
+                        std::string(v.lambda.fun->arg) != "_final"))
                     throw Error("overlay does not take an argument named 'final'");
                 auto body = dynamic_cast<ExprLambda *>(v.lambda.fun->body);
-                if (!body || body->hasFormals() || std::string(body->arg) != "prev")
+                if (!body || body->hasFormals() ||
+                    (std::string(body->arg) != "prev" &&
+                        std::string(body->arg) != "_prev"))
                     throw Error("overlay does not take an argument named 'prev'");
                 // FIXME: if we have a 'nixpkgs' input, use it to
                 // evaluate the overlay.

From c34cc5e488b7baf7dcc1944c72fdceaa6affb55a Mon Sep 17 00:00:00 2001
From: Dimitris Apostolou <dimitris.apostolou@icloud.com>
Date: Wed, 3 Nov 2021 18:11:20 +0200
Subject: [PATCH 177/567] Fix typos

---
 doc/manual/src/command-ref/nix-env.md         |  2 +-
 doc/manual/src/command-ref/nix-store.md       |  2 +-
 doc/manual/src/contributing/cli-guideline.md  | 22 +++++++++----------
 .../src/expressions/advanced-attributes.md    |  2 +-
 .../src/expressions/expression-syntax.md      |  2 +-
 doc/manual/src/expressions/language-values.md |  2 +-
 doc/manual/src/introduction.md                |  2 +-
 7 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/doc/manual/src/command-ref/nix-env.md b/doc/manual/src/command-ref/nix-env.md
index 9138fa05a..5217510d7 100644
--- a/doc/manual/src/command-ref/nix-env.md
+++ b/doc/manual/src/command-ref/nix-env.md
@@ -401,7 +401,7 @@ of a derivation `x` by looking at their respective `name` attributes.
 The names (e.g., `gcc-3.3.1` are split into two parts: the package name
 (`gcc`), and the version (`3.3.1`). The version part starts after the
 first dash not followed by a letter. `x` is considered an upgrade of `y`
-if their package names match, and the version of `y` is higher that that
+if their package names match, and the version of `y` is higher than that
 of `x`.
 
 The versions are compared by splitting them into contiguous components
diff --git a/doc/manual/src/command-ref/nix-store.md b/doc/manual/src/command-ref/nix-store.md
index 7a131dc02..26292f1bb 100644
--- a/doc/manual/src/command-ref/nix-store.md
+++ b/doc/manual/src/command-ref/nix-store.md
@@ -125,7 +125,7 @@ Special exit codes:
 
   - `104`\
     Not deterministic, the build succeeded in check mode but the
-    resulting output is not binary reproducable.
+    resulting output is not binary reproducible.
 
 With the `--keep-going` flag it's possible for multiple failures to
 occur, in this case the 1xx status codes are or combined using binary
diff --git a/doc/manual/src/contributing/cli-guideline.md b/doc/manual/src/contributing/cli-guideline.md
index 0132867c8..69bc45691 100644
--- a/doc/manual/src/contributing/cli-guideline.md
+++ b/doc/manual/src/contributing/cli-guideline.md
@@ -3,7 +3,7 @@
 ## Goals
 
 Purpose of this document is to provide a clear direction to **help design
-delightful command line** experience. This document contain guidelines to
+delightful command line** experience. This document contains guidelines to
 follow to ensure a consistent and approachable user experience.
 
 ## Overview
@@ -115,7 +115,7 @@ The rules are:
 
 - Help is shown by using `--help` or `help` command (eg `nix` `--``help` or
   `nix help`).
-- For non-COMMANDs (eg. `nix` `--``help`  and `nix store` `--``help`) we **show
+- For non-COMMANDs (eg. `nix` `--``help` and `nix store` `--``help`) we **show
   a summary** of most common use cases. Summary is presented on the STDOUT
   without any use of PAGER.
 - For COMMANDs (eg. `nix init` `--``help` or `nix help init`) we display the
@@ -230,8 +230,8 @@ Now **Learn** part of the output is where you educate users. You should only
 show it when you know that a build will take some time and not annoy users of
 the builds that take only few seconds.
 
-Every feature like this should go though a intensive review and testing to
-collect as much a feedback as possible and to fine tune every little detail. If
+Every feature like this should go through an intensive review and testing to
+collect as much feedback as possible and to fine tune every little detail. If
 done right this can be an awesome features beginners and advance users will
 love, but if not done perfectly it will annoy users and leave bad impression.
 
@@ -272,11 +272,11 @@ not know which `ARGUMENTS` and `OPTIONS` are required or which values are
 possible for those options.
 
 In cases, the user might not provide the input or they provide wrong input,
-rather then show the error, prompt a user with an option to find and select
+rather than show the error, prompt a user with an option to find and select
 correct input (see examples).
 
 Prompting is of course not required when TTY is not attached to STDIN. This
-would mean that scripts wont need to handle prompt, but rather handle errors.
+would mean that scripts won't need to handle prompt, but rather handle errors.
 
 A place to use prompt and provide user with interactive select
 
@@ -300,7 +300,7 @@ going to happen.
 ```shell
 $ nix build --option substitutors https://cache.example.org
 ------------------------------------------------------------------------
-  Warning! A security related question need to be answered.
+  Warning! A security related question needs to be answered.
 ------------------------------------------------------------------------
   The following substitutors will be used to in `my-project`: 
     - https://cache.example.org
@@ -311,14 +311,14 @@ $ nix build --option substitutors https://cache.example.org
 
 # Output
 
-Terminal output can be quite limiting in many ways. Which should forces us to
+Terminal output can be quite limiting in many ways. Which should force us to
 think about the experience even more. As with every design the output is a
 compromise between being terse and being verbose, between showing help to
 beginners and annoying advance users. For this it is important that we know
 what are the priorities.
 
 Nix command line should be first and foremost written with beginners in mind.
-But users wont stay beginners for long and what was once useful might quickly
+But users won't stay beginners for long and what was once useful might quickly
 become annoying. There is no golden rule that we can give in this guideline
 that would make it easier how to draw a line and find best compromise.
 
@@ -508,7 +508,7 @@ can, with a few key strokes, be changed into and advance introspection tool.
 
 ### Progress
 
-For longer running commands we should provide and overview of the progress.
+For longer running commands we should provide and overview the progress.
 This is shown best in `nix build` example:
 
 ```shell
@@ -553,7 +553,7 @@ going to happen.
 ```shell
 $ nix build --option substitutors https://cache.example.org
 ------------------------------------------------------------------------
-  Warning! A security related question need to be answered.
+  Warning! A security related question needs to be answered.
 ------------------------------------------------------------------------
   The following substitutors will be used to in `my-project`: 
     - https://cache.example.org
diff --git a/doc/manual/src/expressions/advanced-attributes.md b/doc/manual/src/expressions/advanced-attributes.md
index 5b208df67..000595815 100644
--- a/doc/manual/src/expressions/advanced-attributes.md
+++ b/doc/manual/src/expressions/advanced-attributes.md
@@ -237,7 +237,7 @@ Derivations can declare some infrequently used optional attributes.
   - `preferLocalBuild`\
     If this attribute is set to `true` and [distributed building is
     enabled](../advanced-topics/distributed-builds.md), then, if
-    possible, the derivaton will be built locally instead of forwarded
+    possible, the derivation will be built locally instead of forwarded
     to a remote machine. This is appropriate for trivial builders
     where the cost of doing a download or remote build would exceed
     the cost of building locally.
diff --git a/doc/manual/src/expressions/expression-syntax.md b/doc/manual/src/expressions/expression-syntax.md
index 2a1306e32..6b93e692c 100644
--- a/doc/manual/src/expressions/expression-syntax.md
+++ b/doc/manual/src/expressions/expression-syntax.md
@@ -26,7 +26,7 @@ elements (referenced from the figure by number):
     called with three arguments: `stdenv`, `fetchurl`, and `perl`. They
     are needed to build Hello, but we don't know how to build them here;
     that's why they are function arguments. `stdenv` is a package that
-    is used by almost all Nix Packages packages; it provides a
+    is used by almost all Nix Packages; it provides a
     “standard” environment consisting of the things you would expect
     in a basic Unix environment: a C/C++ compiler (GCC, to be precise),
     the Bash shell, fundamental Unix tools such as `cp`, `grep`, `tar`,
diff --git a/doc/manual/src/expressions/language-values.md b/doc/manual/src/expressions/language-values.md
index 28fa23b58..75ae9f2eb 100644
--- a/doc/manual/src/expressions/language-values.md
+++ b/doc/manual/src/expressions/language-values.md
@@ -64,7 +64,7 @@ Nix has the following basic data types:
     the start of each line. To be precise, it strips from each line a
     number of spaces equal to the minimal indentation of the string as a
     whole (disregarding the indentation of empty lines). For instance,
-    the first and second line are indented two space, while the third
+    the first and second line are indented two spaces, while the third
     line is indented four spaces. Thus, two spaces are stripped from
     each line, so the resulting string is
     
diff --git a/doc/manual/src/introduction.md b/doc/manual/src/introduction.md
index d68445c95..93ec502c1 100644
--- a/doc/manual/src/introduction.md
+++ b/doc/manual/src/introduction.md
@@ -127,7 +127,7 @@ $ nix-env --install firefox
 
 _could_ cause quite a bit of build activity, as not only Firefox but
 also all its dependencies (all the way up to the C library and the
-compiler) would have to built, at least if they are not already in the
+compiler) would have to be built, at least if they are not already in the
 Nix store.  This is a _source deployment model_.  For most users,
 building from source is not very pleasant as it takes far too long.
 However, Nix can automatically skip building from source and instead

From 6f291ed718868a926c6c1aacac12359a78c60da7 Mon Sep 17 00:00:00 2001
From: Moritz Hedtke <Moritz.Hedtke@t-online.de>
Date: Tue, 2 Nov 2021 15:28:01 +0100
Subject: [PATCH 178/567] Fix leaking pthread_attr_t

pthread_attr_destroy was not called.
---
 boehmgc-coroutine-sp-fallback.diff | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/boehmgc-coroutine-sp-fallback.diff b/boehmgc-coroutine-sp-fallback.diff
index fa8dd0325..e659bf470 100644
--- a/boehmgc-coroutine-sp-fallback.diff
+++ b/boehmgc-coroutine-sp-fallback.diff
@@ -1,8 +1,8 @@
 diff --git a/pthread_stop_world.c b/pthread_stop_world.c
-index 1cee6a0b..46c3acd9 100644
+index 4b2c429..1fb4c52 100644
 --- a/pthread_stop_world.c
 +++ b/pthread_stop_world.c
-@@ -674,6 +674,8 @@ GC_INNER void GC_push_all_stacks(void)
+@@ -673,6 +673,8 @@ GC_INNER void GC_push_all_stacks(void)
      struct GC_traced_stack_sect_s *traced_stack_sect;
      pthread_t self = pthread_self();
      word total_size = 0;
@@ -11,7 +11,7 @@ index 1cee6a0b..46c3acd9 100644
  
      if (!EXPECT(GC_thr_initialized, TRUE))
        GC_thr_init();
-@@ -723,6 +725,28 @@ GC_INNER void GC_push_all_stacks(void)
+@@ -722,6 +724,31 @@ GC_INNER void GC_push_all_stacks(void)
            hi = p->altstack + p->altstack_size;
            /* FIXME: Need to scan the normal stack too, but how ? */
            /* FIXME: Assume stack grows down */
@@ -22,6 +22,9 @@ index 1cee6a0b..46c3acd9 100644
 +          if (pthread_attr_getstacksize(&pattr, &stack_limit)) {
 +            ABORT("GC_push_all_stacks: pthread_attr_getstacksize failed!");
 +          }
++          if (pthread_attr_destroy(&pattr)) {
++            ABORT("GC_push_all_stacks: pthread_attr_destroy failed!");
++          }
 +          // When a thread goes into a coroutine, we lose its original sp until
 +          // control flow returns to the thread.
 +          // While in the coroutine, the sp points outside the thread stack,

From 7d56174c1e0f50a06e897f83b3c1b97ac87dbf5a Mon Sep 17 00:00:00 2001
From: Jan Van Bruggen <jancvanbruggen@gmail.com>
Date: Wed, 3 Nov 2021 18:42:32 -0600
Subject: [PATCH 179/567] Reword "we"s to "I"s for consistency

This script uses multiple forms of the first-person POV:
1. "We" to refer to the Nix team (https://github.com/NixOS/nix/blob/1e7c796e66a692cd097b155bd0a60fedf20d554f/scripts/install-multi-user.sh#L72)
2. "We" to refer to the combination of the installation script & the user/executor (https://github.com/NixOS/nix/blob/1e7c796e66a692cd097b155bd0a60fedf20d554f/scripts/install-multi-user.sh#L710)
3. "We" to refer to the installation script alone (https://github.com/NixOS/nix/blob/1e7c796e66a692cd097b155bd0a60fedf20d554f/scripts/install-multi-user.sh#L602)
4. "I" to refer to the installation script alone (https://github.com/NixOS/nix/blob/1e7c796e66a692cd097b155bd0a60fedf20d554f/scripts/install-multi-user.sh#L200)

Since I prefer POV 4 to POV 3, this changes all instances of POV 3 to POV 4.
---
 scripts/install-multi-user.sh | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/scripts/install-multi-user.sh b/scripts/install-multi-user.sh
index 513127a62..7d1cb8c5a 100644
--- a/scripts/install-multi-user.sh
+++ b/scripts/install-multi-user.sh
@@ -599,7 +599,7 @@ manager. This will happen in a few stages:
 1. Make sure your computer doesn't already have Nix. If it does, I
    will show you instructions on how to clean up your old install.
 
-2. Show you what we are going to install and where. Then we will ask
+2. Show you what I am going to install and where. Then I will ask
    if you are ready to continue.
 
 3. Create the system users and groups that the Nix daemon uses to run
@@ -614,14 +614,14 @@ manager. This will happen in a few stages:
 
 EOF
 
-    if ui_confirm "Would you like to see a more detailed list of what we will do?"; then
+    if ui_confirm "Would you like to see a more detailed list of what I will do?"; then
         cat <<EOF
 
-We will:
+I will:
 
  - make sure your computer doesn't already have Nix files
    (if it does, I will tell you how to clean them up.)
- - create local users (see the list above for the users we'll make)
+ - create local users (see the list above for the users I'll make)
  - create a local group ($NIX_BUILD_GROUP_NAME)
  - install Nix in to $NIX_ROOT
  - create a configuration file in /etc/nix
@@ -656,7 +656,7 @@ run in a headless fashion, like this:
 
   $ curl -L https://nixos.org/nix/install | sh
 
-or maybe in a CI pipeline. Because of that, we're going to skip the
+or maybe in a CI pipeline. Because of that, I'm going to skip the
 verbose output in the interest of brevity.
 
 If you would like to
@@ -670,7 +670,7 @@ EOF
     fi
 
     cat <<EOF
-This script is going to call sudo a lot. Every time we do, it'll
+This script is going to call sudo a lot. Every time I do, it'll
 output exactly what it'll do, and why.
 
 Just like this:
@@ -682,15 +682,15 @@ EOF
     cat <<EOF
 
 This might look scary, but everything can be undone by running just a
-few commands. We used to ask you to confirm each time sudo ran, but it
+few commands. I used to ask you to confirm each time sudo ran, but it
 was too many times. Instead, I'll just ask you this one time:
 
 EOF
-    if ui_confirm "Can we use sudo?"; then
+    if ui_confirm "Can I use sudo?"; then
         ok "Yay! Thanks! Let's get going!"
     else
         failure <<EOF
-That is okay, but we can't install.
+That is okay, but I can't install.
 EOF
     fi
 }
@@ -811,8 +811,8 @@ main() {
     # pre-Catalina macOS if run as root user.
     if [ $EUID -eq 0 ]; then
         failure <<EOF
-Please do not run this script with root privileges. We will call sudo
-when we need to.
+Please do not run this script with root privileges. I will call sudo
+when I need to.
 EOF
     fi
 

From e5d4c2235f08ca8bfa4aada4ad51b0ac4f212608 Mon Sep 17 00:00:00 2001
From: Jan Tojnar <jtojnar@gmail.com>
Date: Thu, 4 Nov 2021 11:41:29 +0100
Subject: [PATCH 180/567] docs: Correct fallback user config path

This is in line with XDG Base Directory Specification, where ~/.config is supposed to be used when XDG_CONFIG_HOME is unset.

It also better matches the reality, where ~/.config/nix.conf does not seem to be used.
---
 doc/manual/src/command-ref/conf-file-prefix.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/manual/src/command-ref/conf-file-prefix.md b/doc/manual/src/command-ref/conf-file-prefix.md
index 3140170ab..d660db502 100644
--- a/doc/manual/src/command-ref/conf-file-prefix.md
+++ b/doc/manual/src/command-ref/conf-file-prefix.md
@@ -17,7 +17,7 @@ By default Nix reads settings from the following places:
 
     Otherwise it will look for `nix/nix.conf` files in `XDG_CONFIG_DIRS`
     and `XDG_CONFIG_HOME`. If these are unset, it will look in
-    `$HOME/.config/nix.conf`.
+    `$HOME/.config/nix/nix.conf`.
 
   - If `NIX_CONFIG` is set, its contents is treated as the contents of
     a configuration file.

From c4bd6a15c2171153021691776cc657872c42338c Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 4 Nov 2021 14:52:35 +0100
Subject: [PATCH 181/567] Add helper function to check whether a function arg
 is 'X' or '_X'

Also allow '_'.
---
 src/nix/flake.cc | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 5855348ac..5eeb5498a 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -252,6 +252,14 @@ struct CmdFlakeInfo : CmdFlakeMetadata
     }
 };
 
+static bool argHasName(std::string_view arg, std::string_view expected)
+{
+    return
+        arg == expected
+        || arg == "_"
+        || (hasPrefix(arg, "_") && arg.substr(1) == expected);
+}
+
 struct CmdFlakeCheck : FlakeCommand
 {
     bool build = true;
@@ -346,14 +354,14 @@ struct CmdFlakeCheck : FlakeCommand
         auto checkOverlay = [&](const std::string & attrPath, Value & v, const Pos & pos) {
             try {
                 state->forceValue(v, pos);
-                if (!v.isLambda() || v.lambda.fun->hasFormals() ||
-                    (std::string(v.lambda.fun->arg) != "final" &&
-                        std::string(v.lambda.fun->arg) != "_final"))
+                if (!v.isLambda()
+                    || v.lambda.fun->hasFormals()
+                    || !argHasName(v.lambda.fun->arg, "final"))
                     throw Error("overlay does not take an argument named 'final'");
                 auto body = dynamic_cast<ExprLambda *>(v.lambda.fun->body);
-                if (!body || body->hasFormals() ||
-                    (std::string(body->arg) != "prev" &&
-                        std::string(body->arg) != "_prev"))
+                if (!body
+                    || body->hasFormals()
+                    || !argHasName(body->arg, "prev"))
                     throw Error("overlay does not take an argument named 'prev'");
                 // FIXME: if we have a 'nixpkgs' input, use it to
                 // evaluate the overlay.

From ab35cbd675610a52513f746051e98d0a50815bc1 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 21 Feb 2020 18:31:16 +0100
Subject: [PATCH 182/567] StaticEnv: Use std::vector instead of std::map

---
 src/libexpr/eval.cc    |  6 +++---
 src/libexpr/nixexpr.cc | 25 +++++++++++++++++--------
 src/libexpr/nixexpr.hh | 25 +++++++++++++++++++++----
 src/libexpr/parser.y   |  8 ++++----
 src/libexpr/primops.cc | 10 ++++++++--
 src/nix/repl.cc        |  3 ++-
 6 files changed, 55 insertions(+), 22 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index db1e7e56d..062d190b6 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -583,7 +583,7 @@ Value * EvalState::addConstant(const string & name, Value & v)
 {
     Value * v2 = allocValue();
     *v2 = v;
-    staticBaseEnv.vars[symbols.create(name)] = baseEnvDispl;
+    staticBaseEnv.vars.emplace_back(symbols.create(name), baseEnvDispl);
     baseEnv.values[baseEnvDispl++] = v2;
     string name2 = string(name, 0, 2) == "__" ? string(name, 2) : name;
     baseEnv.values[0]->attrs->push_back(Attr(symbols.create(name2), v2));
@@ -609,7 +609,7 @@ Value * EvalState::addPrimOp(const string & name,
 
     Value * v = allocValue();
     v->mkPrimOp(new PrimOp { .fun = primOp, .arity = arity, .name = sym });
-    staticBaseEnv.vars[symbols.create(name)] = baseEnvDispl;
+    staticBaseEnv.vars.emplace_back(symbols.create(name), baseEnvDispl);
     baseEnv.values[baseEnvDispl++] = v;
     baseEnv.values[0]->attrs->push_back(Attr(sym, v));
     return v;
@@ -635,7 +635,7 @@ Value * EvalState::addPrimOp(PrimOp && primOp)
 
     Value * v = allocValue();
     v->mkPrimOp(new PrimOp(std::move(primOp)));
-    staticBaseEnv.vars[envName] = baseEnvDispl;
+    staticBaseEnv.vars.emplace_back(envName, baseEnvDispl);
     baseEnv.values[baseEnvDispl++] = v;
     baseEnv.values[0]->attrs->push_back(Attr(primOp.name, v));
     return v;
diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc
index 0d0f3e469..95a353a40 100644
--- a/src/libexpr/nixexpr.cc
+++ b/src/libexpr/nixexpr.cc
@@ -269,7 +269,7 @@ void ExprVar::bindVars(const StaticEnv & env)
         if (curEnv->isWith) {
             if (withLevel == -1) withLevel = level;
         } else {
-            StaticEnv::Vars::const_iterator i = curEnv->vars.find(name);
+            auto i = curEnv->find(name);
             if (i != curEnv->vars.end()) {
                 fromWith = false;
                 this->level = level;
@@ -311,14 +311,16 @@ void ExprOpHasAttr::bindVars(const StaticEnv & env)
 void ExprAttrs::bindVars(const StaticEnv & env)
 {
     const StaticEnv * dynamicEnv = &env;
-    StaticEnv newEnv(false, &env);
+    StaticEnv newEnv(false, &env, recursive ? attrs.size() : 0);
 
     if (recursive) {
         dynamicEnv = &newEnv;
 
         unsigned int displ = 0;
         for (auto & i : attrs)
-            newEnv.vars[i.first] = i.second.displ = displ++;
+            newEnv.vars.emplace_back(i.first, i.second.displ = displ++);
+
+        // No need to sort newEnv since attrs is in sorted order.
 
         for (auto & i : attrs)
             i.second.e->bindVars(i.second.inherited ? env : newEnv);
@@ -342,15 +344,20 @@ void ExprList::bindVars(const StaticEnv & env)
 
 void ExprLambda::bindVars(const StaticEnv & env)
 {
-    StaticEnv newEnv(false, &env);
+    StaticEnv newEnv(
+        false, &env,
+        (hasFormals() ? formals->formals.size() : 0) +
+        (arg.empty() ? 0 : 1));
 
     unsigned int displ = 0;
 
-    if (!arg.empty()) newEnv.vars[arg] = displ++;
+    if (!arg.empty()) newEnv.vars.emplace_back(arg, displ++);
 
     if (hasFormals()) {
         for (auto & i : formals->formals)
-            newEnv.vars[i.name] = displ++;
+            newEnv.vars.emplace_back(i.name, displ++);
+
+        newEnv.sort();
 
         for (auto & i : formals->formals)
             if (i.def) i.def->bindVars(newEnv);
@@ -361,11 +368,13 @@ void ExprLambda::bindVars(const StaticEnv & env)
 
 void ExprLet::bindVars(const StaticEnv & env)
 {
-    StaticEnv newEnv(false, &env);
+    StaticEnv newEnv(false, &env, attrs->attrs.size());
 
     unsigned int displ = 0;
     for (auto & i : attrs->attrs)
-        newEnv.vars[i.first] = i.second.displ = displ++;
+        newEnv.vars.emplace_back(i.first, i.second.displ = displ++);
+
+    // No need to sort newEnv since attrs->attrs is in sorted order.
 
     for (auto & i : attrs->attrs)
         i.second.e->bindVars(i.second.inherited ? env : newEnv);
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index 851e875bd..3bfa5e0d3 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -4,8 +4,6 @@
 #include "symbol-table.hh"
 #include "error.hh"
 
-#include <map>
-
 
 namespace nix {
 
@@ -342,9 +340,28 @@ struct StaticEnv
 {
     bool isWith;
     const StaticEnv * up;
-    typedef std::map<Symbol, unsigned int> Vars;
+
+    // Note: these must be in sorted order.
+    typedef std::vector<std::pair<Symbol, unsigned int>> Vars;
     Vars vars;
-    StaticEnv(bool isWith, const StaticEnv * up) : isWith(isWith), up(up) { };
+
+    StaticEnv(bool isWith, const StaticEnv * up, size_t expectedSize = 0) : isWith(isWith), up(up) {
+        vars.reserve(expectedSize);
+    };
+
+    void sort()
+    {
+        std::sort(vars.begin(), vars.end(),
+            [](const Vars::value_type & a, const Vars::value_type & b) { return a.first < b.first; });
+    }
+
+    Vars::const_iterator find(const Symbol & name) const
+    {
+        Vars::value_type key(name, 0);
+        auto i = std::lower_bound(vars.begin(), vars.end(), key);
+        if (i != vars.end() && i->first == name) return i;
+        return vars.end();
+    }
 };
 
 
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 813ff2fc3..5d0f05206 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -126,14 +126,14 @@ static void addAttr(ExprAttrs * attrs, AttrPath & attrPath,
                     auto j2 = jAttrs->attrs.find(ad.first);
                     if (j2 != jAttrs->attrs.end()) // Attr already defined in iAttrs, error.
                         dupAttr(ad.first, j2->second.pos, ad.second.pos);
-                    jAttrs->attrs[ad.first] = ad.second;
+                    jAttrs->attrs.emplace(ad.first, ad.second);
                 }
             } else {
                 dupAttr(attrPath, pos, j->second.pos);
             }
         } else {
             // This attr path is not defined. Let's create it.
-            attrs->attrs[i->symbol] = ExprAttrs::AttrDef(e, pos);
+            attrs->attrs.emplace(i->symbol, ExprAttrs::AttrDef(e, pos));
             e->setName(i->symbol);
         }
     } else {
@@ -483,7 +483,7 @@ binds
           if ($$->attrs.find(i.symbol) != $$->attrs.end())
               dupAttr(i.symbol, makeCurPos(@3, data), $$->attrs[i.symbol].pos);
           Pos pos = makeCurPos(@3, data);
-          $$->attrs[i.symbol] = ExprAttrs::AttrDef(new ExprVar(CUR_POS, i.symbol), pos, true);
+          $$->attrs.emplace(i.symbol, ExprAttrs::AttrDef(new ExprVar(CUR_POS, i.symbol), pos, true));
       }
     }
   | binds INHERIT '(' expr ')' attrs ';'
@@ -492,7 +492,7 @@ binds
       for (auto & i : *$6) {
           if ($$->attrs.find(i.symbol) != $$->attrs.end())
               dupAttr(i.symbol, makeCurPos(@6, data), $$->attrs[i.symbol].pos);
-          $$->attrs[i.symbol] = ExprAttrs::AttrDef(new ExprSelect(CUR_POS, $4, i.symbol), makeCurPos(@6, data));
+          $$->attrs.emplace(i.symbol, ExprAttrs::AttrDef(new ExprSelect(CUR_POS, $4, i.symbol), makeCurPos(@6, data)));
       }
     }
   | { $$ = new ExprAttrs(makeCurPos(@0, data)); }
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 6b3cafec8..8a573f35c 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -184,14 +184,17 @@ static void import(EvalState & state, const Pos & pos, Value & vPath, Value * vS
             Env * env = &state.allocEnv(vScope->attrs->size());
             env->up = &state.baseEnv;
 
-            StaticEnv staticEnv(false, &state.staticBaseEnv);
+            StaticEnv staticEnv(false, &state.staticBaseEnv, vScope->attrs->size());
 
             unsigned int displ = 0;
             for (auto & attr : *vScope->attrs) {
-                staticEnv.vars[attr.name] = displ;
+                staticEnv.vars.emplace_back(attr.name, displ);
                 env->values[displ++] = attr.value;
             }
 
+            // No need to call staticEnv.sort(), because
+            // args[0]->attrs is already sorted.
+
             printTalkative("evaluating file '%1%'", realPath);
             Expr * e = state.parseExprFromFile(resolveExprPath(realPath), staticEnv);
 
@@ -3726,6 +3729,7 @@ void EvalState::createBaseEnv()
 
     /* Add a wrapper around the derivation primop that computes the
        `drvPath' and `outPath' attributes lazily. */
+    staticBaseEnv.sort();
     sDerivationNix = symbols.create("//builtin/derivation.nix");
     eval(parse(
         #include "primops/derivation.nix.gen.hh"
@@ -3735,6 +3739,8 @@ void EvalState::createBaseEnv()
     /* Now that we've added all primops, sort the `builtins' set,
        because attribute lookups expect it to be sorted. */
     baseEnv.values[0]->attrs->sort();
+
+    staticBaseEnv.sort();
 }
 
 
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 9c0d22438..07bf32a0a 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -644,7 +644,8 @@ void NixRepl::addVarToScope(const Symbol & name, Value & v)
 {
     if (displ >= envSize)
         throw Error("environment full; cannot add more variables");
-    staticEnv.vars[name] = displ;
+    staticEnv.vars.emplace_back(name, displ);
+    staticEnv.sort();
     env->values[displ++] = &v;
     varNames.insert((string) name);
 }

From 81e7c40264520b387358917987d101f5f5ae4705 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 24 Feb 2020 01:32:01 +0100
Subject: [PATCH 183/567] Optimize primop calls
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

We now parse function applications as a vector of arguments rather
than as a chain of binary applications, e.g. 'substring 1 2 "foo"' is
parsed as

  ExprCall { .fun = <substring>, .args = [ <1>, <2>, <"foo"> ] }

rather than

  ExprApp (ExprApp (ExprApp <substring> <1>) <2>) <"foo">

This allows primops to be called immediately (if enough arguments are
supplied) without having to allocate intermediate tPrimOpApp values.

On

  $ nix-instantiate --dry-run '<nixpkgs/nixos/release-combined.nix>' -A nixos.tests.simple.x86_64-linux

this gives a substantial performance improvement:

  user CPU time:      median =      0.9209  mean =      0.9218  stddev =      0.0073  min =      0.9086  max =      0.9340  [rejected, p=0.00000, Δ=-0.21433±0.00677]
  elapsed time:       median =      1.0585  mean =      1.0584  stddev =      0.0024  min =      1.0523  max =      1.0623  [rejected, p=0.00000, Δ=-0.20594±0.00236]

because it reduces the number of tPrimOpApp allocations from 551990 to
42534 (i.e. only small minority of primop calls are partially
applied) which in turn reduces time spent in the garbage collector.
---
 src/libexpr/eval.cc    | 272 +++++++++++++++++++++++------------------
 src/libexpr/eval.hh    |  12 +-
 src/libexpr/lexer.l    |   1 +
 src/libexpr/nixexpr.cc |  18 ++-
 src/libexpr/nixexpr.hh |  12 +-
 src/libexpr/parser.y   |  51 +++++---
 6 files changed, 228 insertions(+), 138 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 062d190b6..b4b4f7b5c 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -594,6 +594,8 @@ Value * EvalState::addConstant(const string & name, Value & v)
 Value * EvalState::addPrimOp(const string & name,
     size_t arity, PrimOpFun primOp)
 {
+    assert(arity <= maxPrimOpArity);
+
     auto name2 = string(name, 0, 2) == "__" ? string(name, 2) : name;
     Symbol sym = symbols.create(name2);
 
@@ -1251,144 +1253,182 @@ void ExprLambda::eval(EvalState & state, Env & env, Value & v)
 }
 
 
-void ExprApp::eval(EvalState & state, Env & env, Value & v)
-{
-    /* FIXME: vFun prevents GCC from doing tail call optimisation. */
-    Value vFun;
-    e1->eval(state, env, vFun);
-    state.callFunction(vFun, *(e2->maybeThunk(state, env)), v, pos);
-}
-
-
-void EvalState::callPrimOp(Value & fun, Value & arg, Value & v, const Pos & pos)
-{
-    /* Figure out the number of arguments still needed. */
-    size_t argsDone = 0;
-    Value * primOp = &fun;
-    while (primOp->isPrimOpApp()) {
-        argsDone++;
-        primOp = primOp->primOpApp.left;
-    }
-    assert(primOp->isPrimOp());
-    auto arity = primOp->primOp->arity;
-    auto argsLeft = arity - argsDone;
-
-    if (argsLeft == 1) {
-        /* We have all the arguments, so call the primop. */
-
-        /* Put all the arguments in an array. */
-        Value * vArgs[arity];
-        auto n = arity - 1;
-        vArgs[n--] = &arg;
-        for (Value * arg = &fun; arg->isPrimOpApp(); arg = arg->primOpApp.left)
-            vArgs[n--] = arg->primOpApp.right;
-
-        /* And call the primop. */
-        nrPrimOpCalls++;
-        if (countCalls) primOpCalls[primOp->primOp->name]++;
-        primOp->primOp->fun(*this, pos, vArgs, v);
-    } else {
-        Value * fun2 = allocValue();
-        *fun2 = fun;
-        v.mkPrimOpApp(fun2, &arg);
-    }
-}
-
-void EvalState::callFunction(Value & fun, Value & arg, Value & v, const Pos & pos)
+void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value & vRes, const Pos & pos)
 {
     auto trace = evalSettings.traceFunctionCalls ? std::make_unique<FunctionCallTrace>(pos) : nullptr;
 
     forceValue(fun, pos);
 
-    if (fun.isPrimOp() || fun.isPrimOpApp()) {
-        callPrimOp(fun, arg, v, pos);
-        return;
-    }
+    Value vCur(fun);
 
-    if (fun.type() == nAttrs) {
-      auto found = fun.attrs->find(sFunctor);
-      if (found != fun.attrs->end()) {
-        /* fun may be allocated on the stack of the calling function,
-         * but for functors we may keep a reference, so heap-allocate
-         * a copy and use that instead.
-         */
-        auto & fun2 = *allocValue();
-        fun2 = fun;
-        /* !!! Should we use the attr pos here? */
-        Value v2;
-        callFunction(*found->value, fun2, v2, pos);
-        return callFunction(v2, arg, v, pos);
-      }
-    }
+    auto makeAppChain = [&]()
+    {
+        vRes = vCur;
+        for (size_t i = 0; i < nrArgs; ++i) {
+            auto fun2 = allocValue();
+            *fun2 = vRes;
+            vRes.mkPrimOpApp(fun2, args[i]);
+        }
+    };
 
-    if (!fun.isLambda())
-        throwTypeError(pos, "attempt to call something which is not a function but %1%", fun);
+    while (nrArgs > 0) {
 
-    ExprLambda & lambda(*fun.lambda.fun);
+        if (vCur.isLambda()) {
 
-    auto size =
-        (lambda.arg.empty() ? 0 : 1) +
-        (lambda.hasFormals() ? lambda.formals->formals.size() : 0);
-    Env & env2(allocEnv(size));
-    env2.up = fun.lambda.env;
+            ExprLambda & lambda(*vCur.lambda.fun);
 
-    size_t displ = 0;
+            auto size =
+                (lambda.arg.empty() ? 0 : 1) +
+                (lambda.hasFormals() ? lambda.formals->formals.size() : 0);
+            Env & env2(allocEnv(size));
+            env2.up = vCur.lambda.env;
 
-    if (!lambda.hasFormals())
-        env2.values[displ++] = &arg;
+            size_t displ = 0;
 
-    else {
-        forceAttrs(arg, pos);
+            if (!lambda.hasFormals())
+                env2.values[displ++] = args[0];
 
-        if (!lambda.arg.empty())
-            env2.values[displ++] = &arg;
+            else {
+                forceAttrs(*args[0], pos);
 
-        /* For each formal argument, get the actual argument.  If
-           there is no matching actual argument but the formal
-           argument has a default, use the default. */
-        size_t attrsUsed = 0;
-        for (auto & i : lambda.formals->formals) {
-            Bindings::iterator j = arg.attrs->find(i.name);
-            if (j == arg.attrs->end()) {
-                if (!i.def) throwTypeError(pos, "%1% called without required argument '%2%'",
-                    lambda, i.name);
-                env2.values[displ++] = i.def->maybeThunk(*this, env2);
+                if (!lambda.arg.empty())
+                    env2.values[displ++] = args[0];
+
+                /* For each formal argument, get the actual argument.  If
+                   there is no matching actual argument but the formal
+                   argument has a default, use the default. */
+                size_t attrsUsed = 0;
+                for (auto & i : lambda.formals->formals) {
+                    auto j = args[0]->attrs->get(i.name);
+                    if (!j) {
+                        if (!i.def) throwTypeError(pos, "%1% called without required argument '%2%'",
+                            lambda, i.name);
+                        env2.values[displ++] = i.def->maybeThunk(*this, env2);
+                    } else {
+                        attrsUsed++;
+                        env2.values[displ++] = j->value;
+                    }
+                }
+
+                /* Check that each actual argument is listed as a formal
+                   argument (unless the attribute match specifies a `...'). */
+                if (!lambda.formals->ellipsis && attrsUsed != args[0]->attrs->size()) {
+                    /* Nope, so show the first unexpected argument to the
+                       user. */
+                    for (auto & i : *args[0]->attrs)
+                        if (lambda.formals->argNames.find(i.name) == lambda.formals->argNames.end())
+                            throwTypeError(pos, "%1% called with unexpected argument '%2%'", lambda, i.name);
+                    abort(); // can't happen
+                }
+            }
+
+            nrFunctionCalls++;
+            if (countCalls) incrFunctionCall(&lambda);
+
+            /* Evaluate the body. */
+            try {
+                lambda.body->eval(*this, env2, vCur);
+            } catch (Error & e) {
+                if (loggerSettings.showTrace.get()) {
+                    addErrorTrace(e, lambda.pos, "while evaluating %s",
+                        (lambda.name.set()
+                            ? "'" + (string) lambda.name + "'"
+                            : "anonymous lambda"));
+                    addErrorTrace(e, pos, "from call site%s", "");
+                }
+                throw;
+            }
+
+            nrArgs--;
+            args += 1;
+        }
+
+        else if (vCur.isPrimOp()) {
+
+            size_t argsLeft = vCur.primOp->arity;
+
+            if (nrArgs < argsLeft) {
+                /* We don't have enough arguments, so create a tPrimOpApp chain. */
+                makeAppChain();
+                return;
             } else {
-                attrsUsed++;
-                env2.values[displ++] = j->value;
+                /* We have all the arguments, so call the primop. */
+                nrPrimOpCalls++;
+                if (countCalls) primOpCalls[vCur.primOp->name]++;
+                vCur.primOp->fun(*this, pos, args, vCur);
+
+                nrArgs -= argsLeft;
+                args += argsLeft;
             }
         }
 
-        /* Check that each actual argument is listed as a formal
-           argument (unless the attribute match specifies a `...'). */
-        if (!lambda.formals->ellipsis && attrsUsed != arg.attrs->size()) {
-            /* Nope, so show the first unexpected argument to the
-               user. */
-            for (auto & i : *arg.attrs)
-                if (lambda.formals->argNames.find(i.name) == lambda.formals->argNames.end())
-                    throwTypeError(pos, "%1% called with unexpected argument '%2%'", lambda, i.name);
-            abort(); // can't happen
+        else if (vCur.isPrimOpApp()) {
+            /* Figure out the number of arguments still needed. */
+            size_t argsDone = 0;
+            Value * primOp = &vCur;
+            while (primOp->isPrimOpApp()) {
+                argsDone++;
+                primOp = primOp->primOpApp.left;
+            }
+            assert(primOp->isPrimOp());
+            auto arity = primOp->primOp->arity;
+            auto argsLeft = arity - argsDone;
+
+            if (nrArgs < argsLeft) {
+                /* We still don't have enough arguments, so extend the tPrimOpApp chain. */
+                makeAppChain();
+                return;
+            } else {
+                /* We have all the arguments, so call the primop with
+                   the previous and new arguments. */
+
+                Value * vArgs[arity];
+                auto n = argsDone;
+                for (Value * arg = &vCur; arg->isPrimOpApp(); arg = arg->primOpApp.left)
+                    vArgs[--n] = arg->primOpApp.right;
+
+                for (size_t i = 0; i < argsLeft; ++i)
+                    vArgs[argsDone + i] = args[i];
+
+                nrPrimOpCalls++;
+                if (countCalls) primOpCalls[primOp->primOp->name]++;
+                primOp->primOp->fun(*this, pos, vArgs, vCur);
+
+                nrArgs -= argsLeft;
+                args += argsLeft;
+            }
         }
+
+        else if (vCur.type() == nAttrs) {
+            if (auto functor = vCur.attrs->get(sFunctor)) {
+                /* 'vCur" may be allocated on the stack of the calling
+                   function, but for functors we may keep a reference,
+                   so heap-allocate a copy and use that instead. */
+                Value * args2[] = {allocValue()};
+                *args2[0] = vCur;
+                /* !!! Should we use the attr pos here? */
+                callFunction(*functor->value, 1, args2, vCur, pos);
+            }
+        }
+
+        else
+            throwTypeError(pos, "attempt to call something which is not a function but %1%", vCur);
     }
 
-    nrFunctionCalls++;
-    if (countCalls) incrFunctionCall(&lambda);
+    vRes = vCur;
+}
 
-    /* Evaluate the body.  This is conditional on showTrace, because
-       catching exceptions makes this function not tail-recursive. */
-    if (loggerSettings.showTrace.get())
-        try {
-            lambda.body->eval(*this, env2, v);
-        } catch (Error & e) {
-            addErrorTrace(e, lambda.pos, "while evaluating %s",
-              (lambda.name.set()
-                  ? "'" + (string) lambda.name + "'"
-                  : "anonymous lambda"));
-            addErrorTrace(e, pos, "from call site%s", "");
-            throw;
-        }
-    else
-        fun.lambda.fun->body->eval(*this, env2, v);
+
+void ExprCall::eval(EvalState & state, Env & env, Value & v)
+{
+    Value vFun;
+    fun->eval(state, env, vFun);
+
+    Value * vArgs[args.size()];
+    for (size_t i = 0; i < args.size(); ++i)
+        vArgs[i] = args[i]->maybeThunk(state, env);
+
+    state.callFunction(vFun, args.size(), vArgs, v, pos);
 }
 
 
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 69119599a..f87dcdd8e 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -277,6 +277,8 @@ private:
 
     Value * addConstant(const string & name, Value & v);
 
+    constexpr static size_t maxPrimOpArity = 3;
+
     Value * addPrimOp(const string & name,
         size_t arity, PrimOpFun primOp);
 
@@ -316,8 +318,14 @@ public:
 
     bool isFunctor(Value & fun);
 
-    void callFunction(Value & fun, Value & arg, Value & v, const Pos & pos);
-    void callPrimOp(Value & fun, Value & arg, Value & v, const Pos & pos);
+    // FIXME: use std::span
+    void callFunction(Value & fun, size_t nrArgs, Value * * args, Value & vRes, const Pos & pos);
+
+    void callFunction(Value & fun, Value & arg, Value & vRes, const Pos & pos)
+    {
+        Value * args[] = {&arg};
+        callFunction(fun, 1, args, vRes, pos);
+    }
 
     /* Automatically call a function for which each argument has a
        default value or has a binding in the `args' map. */
diff --git a/src/libexpr/lexer.l b/src/libexpr/lexer.l
index 51593eccd..c18877e29 100644
--- a/src/libexpr/lexer.l
+++ b/src/libexpr/lexer.l
@@ -64,6 +64,7 @@ static void adjustLoc(YYLTYPE * loc, const char * s, size_t len)
 }
 
 
+// FIXME: optimize
 static Expr * unescapeStr(SymbolTable & symbols, const char * s, size_t length)
 {
     string t;
diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc
index 95a353a40..372e323bc 100644
--- a/src/libexpr/nixexpr.cc
+++ b/src/libexpr/nixexpr.cc
@@ -143,6 +143,16 @@ void ExprLambda::show(std::ostream & str) const
     str << ": " << *body << ")";
 }
 
+void ExprCall::show(std::ostream & str) const
+{
+    str << '(' << *fun;
+    for (auto e : args) {
+        str <<  ' ';
+        str << *e;
+    }
+    str << ')';
+}
+
 void ExprLet::show(std::ostream & str) const
 {
     str << "(let ";
@@ -366,6 +376,13 @@ void ExprLambda::bindVars(const StaticEnv & env)
     body->bindVars(newEnv);
 }
 
+void ExprCall::bindVars(const StaticEnv & env)
+{
+    fun->bindVars(env);
+    for (auto e : args)
+        e->bindVars(env);
+}
+
 void ExprLet::bindVars(const StaticEnv & env)
 {
     StaticEnv newEnv(false, &env, attrs->attrs.size());
@@ -461,5 +478,4 @@ size_t SymbolTable::totalSize() const
     return n;
 }
 
-
 }
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index 3bfa5e0d3..fe12890e9 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -248,6 +248,17 @@ struct ExprLambda : Expr
     COMMON_METHODS
 };
 
+struct ExprCall : Expr
+{
+    Expr * fun;
+    std::vector<Expr *> args;
+    Pos pos;
+    ExprCall(const Pos & pos, Expr * fun, std::vector<Expr *> && args)
+        : fun(fun), args(args), pos(pos)
+    { }
+    COMMON_METHODS
+};
+
 struct ExprLet : Expr
 {
     ExprAttrs * attrs;
@@ -306,7 +317,6 @@ struct ExprOpNot : Expr
         void eval(EvalState & state, Env & env, Value & v); \
     };
 
-MakeBinOp(ExprApp, "")
 MakeBinOp(ExprOpEq, "==")
 MakeBinOp(ExprOpNEq, "!=")
 MakeBinOp(ExprOpAnd, "&&")
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 5d0f05206..2e8a04143 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -41,6 +41,12 @@ namespace nix {
             { };
     };
 
+    // Helper to prevent an expensive dynamic_cast call in expr_app.
+    struct App
+    {
+        Expr * e;
+        bool isCall;
+    };
 }
 
 #define YY_DECL int yylex \
@@ -280,10 +286,12 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * err
   char * uri;
   std::vector<nix::AttrName> * attrNames;
   std::vector<nix::Expr *> * string_parts;
+  nix::App app; // bool == whether this is an ExprCall
 }
 
 %type <e> start expr expr_function expr_if expr_op
-%type <e> expr_app expr_select expr_simple
+%type <e> expr_select expr_simple
+%type <app> expr_app
 %type <list> expr_list
 %type <attrs> binds
 %type <formals> formals
@@ -353,13 +361,13 @@ expr_if
 
 expr_op
   : '!' expr_op %prec NOT { $$ = new ExprOpNot($2); }
-  | '-' expr_op %prec NEGATE { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__sub")), new ExprInt(0)), $2); }
+  | '-' expr_op %prec NEGATE { $$ = new ExprCall(CUR_POS, new ExprVar(data->symbols.create("__sub")), {new ExprInt(0), $2}); }
   | expr_op EQ expr_op { $$ = new ExprOpEq($1, $3); }
   | expr_op NEQ expr_op { $$ = new ExprOpNEq($1, $3); }
-  | expr_op '<' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__lessThan")), $1), $3); }
-  | expr_op LEQ expr_op { $$ = new ExprOpNot(new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__lessThan")), $3), $1)); }
-  | expr_op '>' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__lessThan")), $3), $1); }
-  | expr_op GEQ expr_op { $$ = new ExprOpNot(new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__lessThan")), $1), $3)); }
+  | expr_op '<' expr_op { $$ = new ExprCall(CUR_POS, new ExprVar(data->symbols.create("__lessThan")), {$1, $3}); }
+  | expr_op LEQ expr_op { $$ = new ExprOpNot(new ExprCall(CUR_POS, new ExprVar(data->symbols.create("__lessThan")), {$3, $1})); }
+  | expr_op '>' expr_op { $$ = new ExprCall(CUR_POS, new ExprVar(data->symbols.create("__lessThan")), {$3, $1}); }
+  | expr_op GEQ expr_op { $$ = new ExprOpNot(new ExprCall(CUR_POS, new ExprVar(data->symbols.create("__lessThan")), {$1, $3})); }
   | expr_op AND expr_op { $$ = new ExprOpAnd(CUR_POS, $1, $3); }
   | expr_op OR expr_op { $$ = new ExprOpOr(CUR_POS, $1, $3); }
   | expr_op IMPL expr_op { $$ = new ExprOpImpl(CUR_POS, $1, $3); }
@@ -367,17 +375,24 @@ expr_op
   | expr_op '?' attrpath { $$ = new ExprOpHasAttr($1, *$3); }
   | expr_op '+' expr_op
     { $$ = new ExprConcatStrings(CUR_POS, false, new vector<Expr *>({$1, $3})); }
-  | expr_op '-' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__sub")), $1), $3); }
-  | expr_op '*' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__mul")), $1), $3); }
-  | expr_op '/' expr_op { $$ = new ExprApp(CUR_POS, new ExprApp(new ExprVar(data->symbols.create("__div")), $1), $3); }
+  | expr_op '-' expr_op { $$ = new ExprCall(CUR_POS, new ExprVar(data->symbols.create("__sub")), {$1, $3}); }
+  | expr_op '*' expr_op { $$ = new ExprCall(CUR_POS, new ExprVar(data->symbols.create("__mul")), {$1, $3}); }
+  | expr_op '/' expr_op { $$ = new ExprCall(CUR_POS, new ExprVar(data->symbols.create("__div")), {$1, $3}); }
   | expr_op CONCAT expr_op { $$ = new ExprOpConcatLists(CUR_POS, $1, $3); }
-  | expr_app
+  | expr_app { $$ = $1.e; }
   ;
 
 expr_app
-  : expr_app expr_select
-    { $$ = new ExprApp(CUR_POS, $1, $2); }
-  | expr_select { $$ = $1; }
+  : expr_app expr_select {
+      if ($1.isCall) {
+          ((ExprCall *) $1.e)->args.push_back($2);
+          $$ = $1;
+      } else {
+          $$.e = new ExprCall(CUR_POS, $1.e, {$2});
+          $$.isCall = true;
+      }
+  }
+  | expr_select { $$.e = $1; $$.isCall = false; }
   ;
 
 expr_select
@@ -388,7 +403,7 @@ expr_select
   | /* Backwards compatibility: because Nixpkgs has a rarely used
        function named ‘or’, allow stuff like ‘map or [...]’. */
     expr_simple OR_KW
-    { $$ = new ExprApp(CUR_POS, $1, new ExprVar(CUR_POS, data->symbols.create("or"))); }
+    { $$ = new ExprCall(CUR_POS, $1, {new ExprVar(CUR_POS, data->symbols.create("or"))}); }
   | expr_simple { $$ = $1; }
   ;
 
@@ -412,10 +427,10 @@ expr_simple
   }
   | SPATH {
       string path($1 + 1, strlen($1) - 2);
-      $$ = new ExprApp(CUR_POS,
-          new ExprApp(new ExprVar(data->symbols.create("__findFile")),
-              new ExprVar(data->symbols.create("__nixPath"))),
-          new ExprString(data->symbols.create(path)));
+      $$ = new ExprCall(CUR_POS,
+          new ExprVar(data->symbols.create("__findFile")),
+          {new ExprVar(data->symbols.create("__nixPath")),
+           new ExprString(data->symbols.create(path))});
   }
   | URI {
       static bool noURLLiterals = settings.isExperimentalFeatureEnabled(Xp::NoUrlLiterals);

From bcf47800067243b124569da9019077c81bf71cd5 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 24 Feb 2020 14:33:01 +0100
Subject: [PATCH 184/567] Add level / displacement types

---
 src/libexpr/eval.cc    |  8 ++++----
 src/libexpr/nixexpr.cc | 10 +++++-----
 src/libexpr/nixexpr.hh | 11 +++++++----
 3 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index b4b4f7b5c..641687f2a 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -787,7 +787,7 @@ void mkPath(Value & v, const char * s)
 
 inline Value * EvalState::lookupVar(Env * env, const ExprVar & var, bool noEval)
 {
-    for (size_t l = var.level; l; --l, env = env->up) ;
+    for (auto l = var.level; l; --l, env = env->up) ;
 
     if (!var.fromWith) return env->values[var.displ];
 
@@ -1060,7 +1060,7 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
         /* The recursive attributes are evaluated in the new
            environment, while the inherited attributes are evaluated
            in the original environment. */
-        size_t displ = 0;
+        Displacement displ = 0;
         for (auto & i : attrs) {
             Value * vAttr;
             if (hasOverrides && !i.second.inherited) {
@@ -1136,7 +1136,7 @@ void ExprLet::eval(EvalState & state, Env & env, Value & v)
     /* The recursive attributes are evaluated in the new environment,
        while the inherited attributes are evaluated in the original
        environment. */
-    size_t displ = 0;
+    Displacement displ = 0;
     for (auto & i : attrs->attrs)
         env2.values[displ++] = i.second.e->maybeThunk(state, i.second.inherited ? env : env2);
 
@@ -1283,7 +1283,7 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
             Env & env2(allocEnv(size));
             env2.up = vCur.lambda.env;
 
-            size_t displ = 0;
+            Displacement displ = 0;
 
             if (!lambda.hasFormals())
                 env2.values[displ++] = args[0];
diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc
index 372e323bc..57c2f6e44 100644
--- a/src/libexpr/nixexpr.cc
+++ b/src/libexpr/nixexpr.cc
@@ -273,7 +273,7 @@ void ExprVar::bindVars(const StaticEnv & env)
     /* Check whether the variable appears in the environment.  If so,
        set its level and displacement. */
     const StaticEnv * curEnv;
-    unsigned int level;
+    Level level;
     int withLevel = -1;
     for (curEnv = &env, level = 0; curEnv; curEnv = curEnv->up, level++) {
         if (curEnv->isWith) {
@@ -326,7 +326,7 @@ void ExprAttrs::bindVars(const StaticEnv & env)
     if (recursive) {
         dynamicEnv = &newEnv;
 
-        unsigned int displ = 0;
+        Displacement displ = 0;
         for (auto & i : attrs)
             newEnv.vars.emplace_back(i.first, i.second.displ = displ++);
 
@@ -359,7 +359,7 @@ void ExprLambda::bindVars(const StaticEnv & env)
         (hasFormals() ? formals->formals.size() : 0) +
         (arg.empty() ? 0 : 1));
 
-    unsigned int displ = 0;
+    Displacement displ = 0;
 
     if (!arg.empty()) newEnv.vars.emplace_back(arg, displ++);
 
@@ -387,7 +387,7 @@ void ExprLet::bindVars(const StaticEnv & env)
 {
     StaticEnv newEnv(false, &env, attrs->attrs.size());
 
-    unsigned int displ = 0;
+    Displacement displ = 0;
     for (auto & i : attrs->attrs)
         newEnv.vars.emplace_back(i.first, i.second.displ = displ++);
 
@@ -405,7 +405,7 @@ void ExprWith::bindVars(const StaticEnv & env)
        level so that `lookupVar' can look up variables in the previous
        `with' if this one doesn't contain the desired attribute. */
     const StaticEnv * curEnv;
-    unsigned int level;
+    Level level;
     prevWith = 0;
     for (curEnv = &env, level = 1; curEnv; curEnv = curEnv->up, level++)
         if (curEnv->isWith) {
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index fe12890e9..13256272c 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -133,6 +133,9 @@ struct ExprPath : Expr
     Value * maybeThunk(EvalState & state, Env & env);
 };
 
+typedef uint32_t Level;
+typedef uint32_t Displacement;
+
 struct ExprVar : Expr
 {
     Pos pos;
@@ -148,8 +151,8 @@ struct ExprVar : Expr
        value is obtained by getting the attribute named `name' from
        the set stored in the environment that is `level' levels up
        from the current one.*/
-    unsigned int level;
-    unsigned int displ;
+    Level level;
+    Displacement displ;
 
     ExprVar(const Symbol & name) : name(name) { };
     ExprVar(const Pos & pos, const Symbol & name) : pos(pos), name(name) { };
@@ -183,7 +186,7 @@ struct ExprAttrs : Expr
         bool inherited;
         Expr * e;
         Pos pos;
-        unsigned int displ; // displacement
+        Displacement displ; // displacement
         AttrDef(Expr * e, const Pos & pos, bool inherited=false)
             : inherited(inherited), e(e), pos(pos) { };
         AttrDef() { };
@@ -352,7 +355,7 @@ struct StaticEnv
     const StaticEnv * up;
 
     // Note: these must be in sorted order.
-    typedef std::vector<std::pair<Symbol, unsigned int>> Vars;
+    typedef std::vector<std::pair<Symbol, Displacement>> Vars;
     Vars vars;
 
     StaticEnv(bool isWith, const StaticEnv * up, size_t expectedSize = 0) : isWith(isWith), up(up) {

From cbfbf71e0821fd79ae4837e7fe03c051437f43dd Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 2 Mar 2020 17:22:31 +0100
Subject: [PATCH 185/567] Use callFunction() with an array for some calls with
 arity > 1

---
 src/libexpr/primops.cc | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 8a573f35c..9b166d63c 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1883,9 +1883,6 @@ static void addPath(
             Value arg1;
             mkString(arg1, path);
 
-            Value fun2;
-            state.callFunction(*filterFun, arg1, fun2, noPos);
-
             Value arg2;
             mkString(arg2,
                 S_ISREG(st.st_mode) ? "regular" :
@@ -1893,8 +1890,9 @@ static void addPath(
                 S_ISLNK(st.st_mode) ? "symlink" :
                 "unknown" /* not supported, will fail! */);
 
+            Value * args []{&arg1, &arg2};
             Value res;
-            state.callFunction(fun2, arg2, res, noPos);
+            state.callFunction(*filterFun, 2, args, res, pos);
 
             return state.forceBool(res, pos);
         }) : defaultPathFilter;
@@ -2695,10 +2693,9 @@ static void prim_foldlStrict(EvalState & state, const Pos & pos, Value * * args,
         Value * vCur = args[1];
 
         for (unsigned int n = 0; n < args[2]->listSize(); ++n) {
-            Value vTmp;
-            state.callFunction(*args[0], *vCur, vTmp, pos);
+            Value * vs []{vCur, args[2]->listElems()[n]};
             vCur = n == args[2]->listSize() - 1 ? &v : state.allocValue();
-            state.callFunction(vTmp, *args[2]->listElems()[n], *vCur, pos);
+            state.callFunction(*args[0], 2, vs, *vCur, pos);
         }
         state.forceValue(v, pos);
     } else {
@@ -2819,17 +2816,16 @@ static void prim_sort(EvalState & state, const Pos & pos, Value * * args, Value
         v.listElems()[n] = args[1]->listElems()[n];
     }
 
-
     auto comparator = [&](Value * a, Value * b) {
         /* Optimization: if the comparator is lessThan, bypass
            callFunction. */
         if (args[0]->isPrimOp() && args[0]->primOp->fun == prim_lessThan)
             return CompareValues()(a, b);
 
-        Value vTmp1, vTmp2;
-        state.callFunction(*args[0], *a, vTmp1, pos);
-        state.callFunction(vTmp1, *b, vTmp2, pos);
-        return state.forceBool(vTmp2, pos);
+        Value * vs[] = {a, b};
+        Value vBool;
+        state.callFunction(*args[0], 2, vs, vBool, pos);
+        return state.forceBool(vBool, pos);
     };
 
     /* FIXME: std::sort can segfault if the comparator is not a strict

From acd6bddec706e2f180279ca79a0c1a4abac416d6 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 2 Mar 2020 18:15:06 +0100
Subject: [PATCH 186/567] Fix derivation primop

---
 src/libexpr/eval.cc    | 14 ++++++++++----
 src/libexpr/eval.hh    |  2 ++
 src/libexpr/primops.cc | 13 ++++++++-----
 3 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 641687f2a..d371a3fb8 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -583,14 +583,20 @@ Value * EvalState::addConstant(const string & name, Value & v)
 {
     Value * v2 = allocValue();
     *v2 = v;
-    staticBaseEnv.vars.emplace_back(symbols.create(name), baseEnvDispl);
-    baseEnv.values[baseEnvDispl++] = v2;
-    string name2 = string(name, 0, 2) == "__" ? string(name, 2) : name;
-    baseEnv.values[0]->attrs->push_back(Attr(symbols.create(name2), v2));
+    addConstant(name, v2);
     return v2;
 }
 
 
+void EvalState::addConstant(const string & name, Value * v)
+{
+    staticBaseEnv.vars.emplace_back(symbols.create(name), baseEnvDispl);
+    baseEnv.values[baseEnvDispl++] = v;
+    string name2 = string(name, 0, 2) == "__" ? string(name, 2) : name;
+    baseEnv.values[0]->attrs->push_back(Attr(symbols.create(name2), v));
+}
+
+
 Value * EvalState::addPrimOp(const string & name,
     size_t arity, PrimOpFun primOp)
 {
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index f87dcdd8e..65cf04b57 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -277,6 +277,8 @@ private:
 
     Value * addConstant(const string & name, Value & v);
 
+    void addConstant(const string & name, Value * v);
+
     constexpr static size_t maxPrimOpArity = 3;
 
     Value * addPrimOp(const string & name,
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 9b166d63c..e4107dbe1 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -3725,18 +3725,21 @@ void EvalState::createBaseEnv()
 
     /* Add a wrapper around the derivation primop that computes the
        `drvPath' and `outPath' attributes lazily. */
-    staticBaseEnv.sort();
     sDerivationNix = symbols.create("//builtin/derivation.nix");
-    eval(parse(
-        #include "primops/derivation.nix.gen.hh"
-        , foFile, sDerivationNix, "/", staticBaseEnv), v);
-    addConstant("derivation", v);
+    auto vDerivation = allocValue();
+    addConstant("derivation", vDerivation);
 
     /* Now that we've added all primops, sort the `builtins' set,
        because attribute lookups expect it to be sorted. */
     baseEnv.values[0]->attrs->sort();
 
     staticBaseEnv.sort();
+
+    /* Note: we have to initialize the 'derivation' constant *after*
+       building baseEnv/staticBaseEnv because it uses 'builtins'. */
+    eval(parse(
+        #include "primops/derivation.nix.gen.hh"
+        , foFile, sDerivationNix, "/", staticBaseEnv), *vDerivation);
 }
 
 

From 05560f6350f5e330c286e048b8fbbb24dafbf16b Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 2 Mar 2020 18:16:49 +0100
Subject: [PATCH 187/567] Fix function-trace test case

---
 tests/function-trace.sh | 2 --
 1 file changed, 2 deletions(-)

diff --git a/tests/function-trace.sh b/tests/function-trace.sh
index 3b7f364e3..0b7f49d82 100755
--- a/tests/function-trace.sh
+++ b/tests/function-trace.sh
@@ -60,8 +60,6 @@ function-trace exited (string):1:1 at
 expect_trace '(x: x) 1 2' "
 function-trace entered (string):1:1 at
 function-trace exited (string):1:1 at
-function-trace entered (string):1:1 at
-function-trace exited (string):1:1 at
 "
 
 # Not a function

From 40925337a972991468335b90ce4f685f7102d830 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 2 Mar 2020 22:41:56 +0100
Subject: [PATCH 188/567] Remove maxPrimOpArity

---
 src/libexpr/eval.cc | 2 --
 src/libexpr/eval.hh | 2 --
 2 files changed, 4 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index d371a3fb8..402de78ad 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -600,8 +600,6 @@ void EvalState::addConstant(const string & name, Value * v)
 Value * EvalState::addPrimOp(const string & name,
     size_t arity, PrimOpFun primOp)
 {
-    assert(arity <= maxPrimOpArity);
-
     auto name2 = string(name, 0, 2) == "__" ? string(name, 2) : name;
     Symbol sym = symbols.create(name2);
 
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 65cf04b57..1aab8e166 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -279,8 +279,6 @@ private:
 
     void addConstant(const string & name, Value * v);
 
-    constexpr static size_t maxPrimOpArity = 3;
-
     Value * addPrimOp(const string & name,
         size_t arity, PrimOpFun primOp);
 

From abdf9f2a6ecdc364531ed1554b689a6a467b79d1 Mon Sep 17 00:00:00 2001
From: "Travis A. Everett" <travis.a.everett@gmail.com>
Date: Thu, 4 Nov 2021 14:09:40 -0500
Subject: [PATCH 189/567] darwin-install: fix already-mounted store volumes

This adds an explicit unmount of the store volume to avoid cases
where the installer can hang in await_volume when:
- the user already has a store volume
- that volume is already mounted somewhere other than /nix
- they do not take a path through the installer that results in an
  explicit unmount (as both removing and encrypting the volume
  would do)
---
 scripts/create-darwin-volume.sh | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/scripts/create-darwin-volume.sh b/scripts/create-darwin-volume.sh
index b52232dd3..334b75045 100755
--- a/scripts/create-darwin-volume.sh
+++ b/scripts/create-darwin-volume.sh
@@ -742,6 +742,9 @@ setup_volume() {
 
     use_special="${NIX_VOLUME_USE_SPECIAL:-$(create_volume)}"
 
+    _sudo "to ensure the Nix volume is not mounted" \
+        /usr/sbin/diskutil unmount force "$use_special" || true # might not be mounted
+
     use_uuid=${NIX_VOLUME_USE_UUID:-$(volume_uuid_from_special "$use_special")}
 
     setup_fstab "$use_uuid"

From 1a4c9ba50bb36ab5d18f47b0d00052d274ed824f Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Wed, 3 Nov 2021 10:54:17 +0100
Subject: [PATCH 190/567] =?UTF-8?q?Fix=20`nix=20repl`=E2=80=99s=20building?=
 =?UTF-8?q?=20of=20CA=20derivations?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

When running a `:b` command in the repl, after building the derivations
query the store for its outputs rather than just assuming that they are
known in the derivation itself (which isn’t true for CA derivations)

Fix #5328
---
 src/nix/repl.cc  | 4 ++--
 tests/ca/repl.sh | 5 +++++
 tests/local.mk   | 2 +-
 tests/repl.sh    | 4 +++-
 4 files changed, 11 insertions(+), 4 deletions(-)
 create mode 100644 tests/ca/repl.sh

diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 9c0d22438..bc31cf1d4 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -504,8 +504,8 @@ bool NixRepl::processLine(string line)
             state->store->buildPaths({DerivedPath::Built{drvPath}});
             auto drv = state->store->readDerivation(drvPath);
             logger->cout("\nThis derivation produced the following outputs:");
-            for (auto & i : drv.outputsAndOptPaths(*state->store))
-                logger->cout("  %s -> %s", i.first, state->store->printStorePath(*i.second.second));
+            for (auto & [outputName, outputPath] : state->store->queryDerivationOutputMap(drvPath))
+                logger->cout("  %s -> %s", outputName, state->store->printStorePath(outputPath));
         } else if (command == ":i") {
             runNix("nix-env", {"-i", drvPathRaw});
         } else {
diff --git a/tests/ca/repl.sh b/tests/ca/repl.sh
new file mode 100644
index 000000000..3808c7cb2
--- /dev/null
+++ b/tests/ca/repl.sh
@@ -0,0 +1,5 @@
+source common.sh
+
+export NIX_TESTS_CA_BY_DEFAULT=1
+
+cd .. && source repl.sh
diff --git a/tests/local.mk b/tests/local.mk
index 8d454ee19..b63a12d96 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -48,7 +48,7 @@ nix_tests = \
   flakes.sh \
   build.sh \
   compute-levels.sh \
-  repl.sh \
+  repl.sh ca/repl.sh \
   ca/build.sh \
   ca/build-with-garbage-path.sh \
   ca/duplicate-realisation-in-closure.sh \
diff --git a/tests/repl.sh b/tests/repl.sh
index 4e3059517..d360821f2 100644
--- a/tests/repl.sh
+++ b/tests/repl.sh
@@ -7,7 +7,9 @@ simple = import ./simple.nix
 
 testRepl () {
     local nixArgs=("$@")
-    local outPath=$(nix repl "${nixArgs[@]}" <<< "$replCmds" |&
+    local replOutput="$(nix repl "${nixArgs[@]}" <<< "$replCmds")"
+    echo "$replOutput"
+    local outPath=$(echo "$replOutput" |&
         grep -o -E "$NIX_STORE_DIR/\w*-simple")
     nix path-info "${nixArgs[@]}" "$outPath"
 }

From 93eadd5803caa6d28be056c58194be974a87aeb8 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Fri, 5 Nov 2021 11:11:33 +0100
Subject: [PATCH 191/567] Make the post-build-hook use the daemon Nix package
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Having the `post-build-hook` use `nix` from the client package can lead
to a deadlock in case there’s a db migration to do between both, as a
`nix` command running inside the hook will run as root (and as such will
bypass the daemon), so might trigger a db migration, which will get
stuck trying to get a global lock on the DB (as the daemon that ran the
hook already has a lock on it).
---
 tests/common.sh.in | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tests/common.sh.in b/tests/common.sh.in
index 08f5e0a77..3d0d56120 100644
--- a/tests/common.sh.in
+++ b/tests/common.sh.in
@@ -36,8 +36,9 @@ export PATH=@bindir@:$PATH
 if [[ -n "${NIX_CLIENT_PACKAGE:-}" ]]; then
   export PATH="$NIX_CLIENT_PACKAGE/bin":$PATH
 fi
+DAEMON_PATH="$PATH"
 if [[ -n "${NIX_DAEMON_PACKAGE:-}" ]]; then
-  export NIX_DAEMON_COMMAND="$NIX_DAEMON_PACKAGE/bin/nix-daemon"
+  DAEMON_PATH="${NIX_DAEMON_PACKAGE}:$DAEMON_PATH"
 fi
 coreutils=@coreutils@
 
@@ -89,7 +90,7 @@ startDaemon() {
     # Start the daemon, wait for the socket to appear.  !!!
     # ‘nix-daemon’ should have an option to fork into the background.
     rm -f $NIX_DAEMON_SOCKET_PATH
-    ${NIX_DAEMON_COMMAND:-nix daemon} &
+    PATH=$DAEMON_PATH nix daemon &
     for ((i = 0; i < 30; i++)); do
         if [[ -S $NIX_DAEMON_SOCKET_PATH ]]; then break; fi
         sleep 1

From 1f3c3a3785b21fe349480b562d5f97b8cc9caa6d Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Fri, 5 Nov 2021 16:17:49 +0100
Subject: [PATCH 192/567] Make the flake options work when using the daemon
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

When setting flake-local options (with the `nixConfig` field), forward
these options to the daemon in case we’re using one.

This is necessary in particular for options like `binary-caches` or
`post-build-hook` to make sense.

Fix <https://github.com/NixOS/nix/commit/343239fc8a1993f707a990c2cd54a41f1fa3de99#r44356843>
---
 src/libexpr/flake/flake.cc    |  2 +-
 src/libstore/remote-store.cc  |  4 ++++
 src/libstore/remote-store.hh  |  2 ++
 src/libstore/store-api.hh     |  5 +++++
 tests/flake-local-settings.sh | 35 +++++++++++++++++++++++++++++++++++
 tests/local.mk                |  1 +
 6 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 tests/flake-local-settings.sh

diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index c9d848495..07ed3caa2 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -307,7 +307,7 @@ LockedFlake lockFlake(
 
     if (lockFlags.applyNixConfig) {
         flake.config.apply();
-        // FIXME: send new config to the daemon.
+        state.store->setOptions();
     }
 
     try {
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index 7decc059c..274203f8d 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -290,6 +290,10 @@ ConnectionHandle RemoteStore::getConnection()
     return ConnectionHandle(connections->get());
 }
 
+void RemoteStore::setOptions()
+{
+    setOptions(*(getConnection().handle));
+}
 
 bool RemoteStore::isValidPathUncached(const StorePath & path)
 {
diff --git a/src/libstore/remote-store.hh b/src/libstore/remote-store.hh
index a3036e6b0..5f6da9af5 100644
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@@ -147,6 +147,8 @@ protected:
 
     virtual void setOptions(Connection & conn);
 
+    void setOptions() override;
+
     ConnectionHandle getConnection();
 
     friend struct ConnectionHandle;
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 7d02340df..8472e726a 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -724,6 +724,11 @@ public:
     virtual void createUser(const std::string & userName, uid_t userId)
     { }
 
+    /*
+     * Synchronises the options of the client with those of the daemon
+     * (a no-op when there’s no daemon)
+     */
+    virtual void setOptions() { }
 protected:
 
     Stats stats;
diff --git a/tests/flake-local-settings.sh b/tests/flake-local-settings.sh
new file mode 100644
index 000000000..c037431c8
--- /dev/null
+++ b/tests/flake-local-settings.sh
@@ -0,0 +1,35 @@
+source common.sh
+
+clearStore
+rm -rf $TEST_HOME/.cache $TEST_HOME/.config $TEST_HOME/.local
+
+cp ./simple.nix ./simple.builder.sh ./config.nix $TEST_HOME
+
+cd $TEST_HOME
+
+rm -f post-hook-ran
+cat <<EOF > echoing-post-hook.sh
+#!/bin/sh
+
+echo "ThePostHookRan" > $PWD/post-hook-ran
+EOF
+chmod +x echoing-post-hook.sh
+
+cat <<EOF > flake.nix
+{
+    nixConfig.post-build-hook = "$PWD/echoing-post-hook.sh";
+
+    outputs = a: {
+       defaultPackage.$system = import ./simple.nix;
+    };
+}
+EOF
+
+# Ugly hack for testing
+mkdir -p .local/share/nix
+cat <<EOF > .local/share/nix/trusted-settings.json
+{"post-build-hook":{"$PWD/echoing-post-hook.sh":true}}
+EOF
+
+nix build
+test -f post-hook-ran || fail "The post hook should have ran"
diff --git a/tests/local.mk b/tests/local.mk
index 8d454ee19..4c53f09f2 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -46,6 +46,7 @@ nix_tests = \
   recursive.sh \
   describe-stores.sh \
   flakes.sh \
+  flake-local-settings.sh \
   build.sh \
   compute-levels.sh \
   repl.sh \

From 9d4dcff37a14c5bab98761e417a2335a9ac68c96 Mon Sep 17 00:00:00 2001
From: Alexander Bantyev <balsoft@balsoft.ru>
Date: Sat, 23 Oct 2021 21:31:46 +0300
Subject: [PATCH 193/567] addPath: allow paths with references

Since 4806f2f6b0fd2cae401b89fe19d8c528ffd88b5f, we can't have paths with
references passed to builtins.{path,filterSource}. This prevents many cases
of those functions called on IFD outputs from working. Resolve this by
passing the references found in the original path to the added path.
---
 src/libexpr/primops.cc             | 10 +++++-----
 src/libstore/binary-cache-store.cc |  4 ++--
 src/libstore/daemon.cc             |  2 --
 src/libstore/local-store.cc        |  2 +-
 4 files changed, 8 insertions(+), 10 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 4e0eda7f3..4a615c59d 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1859,12 +1859,12 @@ static void addPath(
         // be rewritten to the actual output).
         state.realiseContext(context);
 
+        StorePathSet refs = StorePathSet();
+
         if (state.store->isInStore(path)) {
             auto [storePath, subPath] = state.store->toStorePath(path);
-            auto info = state.store->queryPathInfo(storePath);
-            if (!info->references.empty())
-                throw EvalError("store path '%s' is not allowed to have references",
-                    state.store->printStorePath(storePath));
+            // FIXME: we should scanForReferences on the path before adding it
+            refs = state.store->queryPathInfo(storePath)->references;
             path = state.store->toRealPath(storePath) + subPath;
         }
 
@@ -1904,7 +1904,7 @@ static void addPath(
         if (!expectedHash || !state.store->isValidPath(*expectedStorePath)) {
             dstPath = state.store->printStorePath(settings.readOnlyMode
                 ? state.store->computeStorePathForPath(name, path, method, htSHA256, filter).first
-                : state.store->addToStore(name, path, method, htSHA256, filter, state.repair));
+                : state.store->addToStore(name, path, method, htSHA256, filter, state.repair, refs));
             if (expectedHash && expectedStorePath != state.store->parseStorePath(dstPath))
                 throw Error("store path mismatch in (possibly filtered) path added from '%s'", path);
         } else
diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index 280f1d4b5..a039c57b3 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -314,7 +314,7 @@ StorePath BinaryCacheStore::addToStoreFromDump(Source & dump, const string & nam
         unsupported("addToStoreFromDump");
     return addToStoreCommon(dump, repair, CheckSigs, [&](HashResult nar) {
         ValidPathInfo info {
-            makeFixedOutputPath(method, nar.first, name),
+            makeFixedOutputPath(method, nar.first, name, references),
             nar.first,
         };
         info.narSize = nar.second;
@@ -405,7 +405,7 @@ StorePath BinaryCacheStore::addToStore(const string & name, const Path & srcPath
     });
     return addToStoreCommon(*source, repair, CheckSigs, [&](HashResult nar) {
         ValidPathInfo info {
-            makeFixedOutputPath(method, h, name),
+            makeFixedOutputPath(method, h, name, references),
             nar.first,
         };
         info.narSize = nar.second;
diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index fa6606ba4..b1cc07486 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -402,8 +402,6 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
                         return store->queryPathInfo(path);
                     },
                     [&](FixedOutputHashMethod & fohm) {
-                        // if (!refs.empty())
-                            // throw UnimplementedError("cannot yet have refs with flat or nar-hashed data");
                         auto path = store->addToStoreFromDump(source, name, fohm.fileIngestionMethod, fohm.hashType, repair, refs);
                         return store->queryPathInfo(path);
                     },
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 85f1de0b0..33ac77af5 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -1358,7 +1358,7 @@ StorePath LocalStore::addToStoreFromDump(Source & source0, const string & name,
 
     auto [hash, size] = hashSink->finish();
 
-    auto dstPath = makeFixedOutputPath(method, hash, name);
+    auto dstPath = makeFixedOutputPath(method, hash, name, references);
 
     addTempRoot(dstPath);
 

From 8e7359db6496ee72a84322d46afa322604afd1a9 Mon Sep 17 00:00:00 2001
From: Andreas Rammhold <andreas@rammhold.de>
Date: Sun, 7 Nov 2021 18:21:24 +0100
Subject: [PATCH 194/567] Remove unused "<let-body>" symbol

The requirement for the symbol has been removed since at least 7d47498.
---
 src/libexpr/parser.y | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 2e8a04143..923997bf6 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -33,11 +33,9 @@ namespace nix {
         Symbol file;
         FileOrigin origin;
         std::optional<ErrorInfo> error;
-        Symbol sLetBody;
         ParseData(EvalState & state)
             : state(state)
             , symbols(state.symbols)
-            , sLetBody(symbols.create("<let-body>"))
             { };
     };
 

From d589782fb0b8e73f562792ba9d02339e32cb2d84 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9o=20Zimmermann?= <theo.zimmermann@inria.fr>
Date: Mon, 8 Nov 2021 08:24:15 +0100
Subject: [PATCH 195/567] Fix some typos in CLI guideline.

---
 doc/manual/src/contributing/cli-guideline.md | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/doc/manual/src/contributing/cli-guideline.md b/doc/manual/src/contributing/cli-guideline.md
index 69bc45691..258f090fb 100644
--- a/doc/manual/src/contributing/cli-guideline.md
+++ b/doc/manual/src/contributing/cli-guideline.md
@@ -240,7 +240,7 @@ love, but if not done perfectly it will annoy users and leave bad impression.
 Input to a command is provided via `ARGUMENTS` and `OPTIONS`. 
 
 `ARGUMENTS` represent a required input for a function. When choosing to use
-`ARGUMENT` over function please be aware of the downsides that come with it:
+`ARGUMENTS` over `OPTIONS` please be aware of the downsides that come with it:
 
 - User will need to remember the order of `ARGUMENTS`. This is not a problem if
   there is only one `ARGUMENT`.
@@ -253,7 +253,7 @@ developer consider the downsides and choose wisely.
 
 ## Naming the `OPTIONS`
 
-Then only naming convention - apart from the ones mentioned in Naming the
+The only naming convention - apart from the ones mentioned in Naming the
 `COMMANDS` section is how flags are named.
 
 Flags are a type of `OPTION` that represent an option that can be turned ON of
@@ -271,7 +271,7 @@ to improve the discoverability of possible input. A new user will most likely
 not know which `ARGUMENTS` and `OPTIONS` are required or which values are
 possible for those options.
 
-In cases, the user might not provide the input or they provide wrong input,
+In case the user does not provide the input or they provide wrong input,
 rather than show the error, prompt a user with an option to find and select
 correct input (see examples).
 

From ff2af4d64ee9789c3c50f7e49897e8fa9fda6e16 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 8 Nov 2021 22:00:45 +0100
Subject: [PATCH 196/567] Unshare mount namespace in main()

Doing it as a side-effect of calling LocalStore::makeStoreWritable()
is very ugly.

Also, make sure that stopping the progress bar joins the update
thread, otherwise that thread should be unshared as well.
---
 src/libmain/progress-bar.cc | 16 +++++++++-------
 src/libstore/local-store.cc |  4 ----
 src/nix/main.cc             |  8 ++++++++
 3 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/src/libmain/progress-bar.cc b/src/libmain/progress-bar.cc
index b2a6e2a82..63955eed1 100644
--- a/src/libmain/progress-bar.cc
+++ b/src/libmain/progress-bar.cc
@@ -103,17 +103,19 @@ public:
     ~ProgressBar()
     {
         stop();
-        updateThread.join();
     }
 
     void stop() override
     {
-        auto state(state_.lock());
-        if (!state->active) return;
-        state->active = false;
-        writeToStderr("\r\e[K");
-        updateCV.notify_one();
-        quitCV.notify_one();
+        {
+            auto state(state_.lock());
+            if (!state->active) return;
+            state->active = false;
+            writeToStderr("\r\e[K");
+            updateCV.notify_one();
+            quitCV.notify_one();
+        }
+        updateThread.join();
     }
 
     bool isVerbose() override {
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 1cef50a40..eb3457339 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -504,10 +504,6 @@ void LocalStore::makeStoreWritable()
         throw SysError("getting info about the Nix store mount point");
 
     if (stat.f_flag & ST_RDONLY) {
-        saveMountNamespace();
-        if (unshare(CLONE_NEWNS) == -1)
-            throw SysError("setting up a private mount namespace");
-
         if (mount(0, realStoreDir.get().c_str(), "none", MS_REMOUNT | MS_BIND, 0) == -1)
             throw SysError("remounting %1% writable", realStoreDir);
     }
diff --git a/src/nix/main.cc b/src/nix/main.cc
index 1e033f4f2..01889a71f 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -255,6 +255,14 @@ void mainWrapped(int argc, char * * argv)
     initNix();
     initGC();
 
+    #if __linux__
+    if (getuid() == 0) {
+        saveMountNamespace();
+        if (unshare(CLONE_NEWNS) == -1)
+            throw SysError("setting up a private mount namespace");
+    }
+    #endif
+
     programPath = argv[0];
     auto programName = std::string(baseNameOf(programPath));
 

From 732dd904280c60f64744aed9df51908ce000016b Mon Sep 17 00:00:00 2001
From: "dependabot[bot]" <49699333+dependabot[bot]@users.noreply.github.com>
Date: Mon, 8 Nov 2021 22:00:58 +0000
Subject: [PATCH 197/567] Bump actions/checkout from 2.3.5 to 2.4.0

Bumps [actions/checkout](https://github.com/actions/checkout) from 2.3.5 to 2.4.0.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v2.3.5...v2.4.0)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
---
 .github/workflows/test.yml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index cdf6ddb67..492ee5388 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -14,7 +14,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     timeout-minutes: 60
     steps:
-    - uses: actions/checkout@v2.3.5
+    - uses: actions/checkout@v2.4.0
       with:
         fetch-depth: 0
     - uses: cachix/install-nix-action@v14.1
@@ -46,7 +46,7 @@ jobs:
     outputs:
       installerURL: ${{ steps.prepare-installer.outputs.installerURL }}
     steps:
-    - uses: actions/checkout@v2.3.5
+    - uses: actions/checkout@v2.4.0
       with:
         fetch-depth: 0
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
@@ -67,7 +67,7 @@ jobs:
         os: [ubuntu-latest, macos-latest]
     runs-on: ${{ matrix.os }}
     steps:
-    - uses: actions/checkout@v2.3.5
+    - uses: actions/checkout@v2.4.0
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
     - uses: cachix/install-nix-action@v14.1
       with:

From 69431edbc174c7644f7143ba5c81681b7ece186e Mon Sep 17 00:00:00 2001
From: "Travis A. Everett" <travis.a.everett@gmail.com>
Date: Mon, 8 Nov 2021 17:03:09 -0600
Subject: [PATCH 198/567] installer: clarify starting assumption task

We had a macOS user present in Matrix with some confusion because the
lack of a clear task statement here made them think the error meant
that a problem had occurred during the preceding task in a macOS
install: "Fixing any leftover Nix volume state"
---
 scripts/install-multi-user.sh | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/scripts/install-multi-user.sh b/scripts/install-multi-user.sh
index 7d1cb8c5a..c91dd404a 100644
--- a/scripts/install-multi-user.sh
+++ b/scripts/install-multi-user.sh
@@ -377,6 +377,11 @@ cure_artifacts() {
 }
 
 validate_starting_assumptions() {
+    task "Checking for artifacts of previous installs"
+    cat <<EOF
+Before I try to install, I'll check for signs Nix already is or has
+been installed on this system.
+EOF
     if type nix-env 2> /dev/null >&2; then
         warning <<EOF
 Nix already appears to be installed. This installer may run into issues.
@@ -386,6 +391,11 @@ $(uninstall_directions)
 EOF
     fi
 
+    # TODO: I think it would be good for this step to accumulate more
+    #       knowledge of older obsolete artifacts, if there are any.
+    #       We could issue a "reminder" here that the user might want
+    #       to clean them up?
+
     for profile_target in "${PROFILE_TARGETS[@]}"; do
         if [ -e "$profile_target$PROFILE_BACKUP_SUFFIX" ]; then
             failure <<EOF

From 0b005bc9d67b3f621bc78e5ecb2cd834172d5563 Mon Sep 17 00:00:00 2001
From: Alexander Bantyev <balsoft@balsoft.ru>
Date: Tue, 9 Nov 2021 12:24:49 +0300
Subject: [PATCH 199/567] addToStore, addToStoreFromDump: refactor: pass refs
 by const reference

Co-Authored-By: Eelco Dolstra <edolstra@gmail.com>
---
 src/libexpr/primops.cc                      | 2 +-
 src/libstore/binary-cache-store.cc          | 4 ++--
 src/libstore/binary-cache-store.hh          | 4 ++--
 src/libstore/build/local-derivation-goal.cc | 4 ++--
 src/libstore/legacy-ssh-store.cc            | 2 +-
 src/libstore/local-store.cc                 | 2 +-
 src/libstore/local-store.hh                 | 2 +-
 src/libstore/remote-store.cc                | 2 +-
 src/libstore/remote-store.hh                | 2 +-
 src/libstore/store-api.cc                   | 2 +-
 src/libstore/store-api.hh                   | 4 ++--
 11 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 4a615c59d..047856abc 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1859,7 +1859,7 @@ static void addPath(
         // be rewritten to the actual output).
         state.realiseContext(context);
 
-        StorePathSet refs = StorePathSet();
+        StorePathSet refs;
 
         if (state.store->isInStore(path)) {
             auto [storePath, subPath] = state.store->toStorePath(path);
diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index a039c57b3..065cac8b5 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -308,7 +308,7 @@ void BinaryCacheStore::addToStore(const ValidPathInfo & info, Source & narSource
 }
 
 StorePath BinaryCacheStore::addToStoreFromDump(Source & dump, const string & name,
-    FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, StorePathSet references)
+    FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, const StorePathSet & references)
 {
     if (method != FileIngestionMethod::Recursive || hashAlgo != htSHA256)
         unsupported("addToStoreFromDump");
@@ -386,7 +386,7 @@ void BinaryCacheStore::queryPathInfoUncached(const StorePath & storePath,
 }
 
 StorePath BinaryCacheStore::addToStore(const string & name, const Path & srcPath,
-    FileIngestionMethod method, HashType hashAlgo, PathFilter & filter, RepairFlag repair, StorePathSet references)
+    FileIngestionMethod method, HashType hashAlgo, PathFilter & filter, RepairFlag repair, const StorePathSet & references)
 {
     /* FIXME: Make BinaryCacheStore::addToStoreCommon support
        non-recursive+sha256 so we can just use the default
diff --git a/src/libstore/binary-cache-store.hh b/src/libstore/binary-cache-store.hh
index d8f077db2..a703994d3 100644
--- a/src/libstore/binary-cache-store.hh
+++ b/src/libstore/binary-cache-store.hh
@@ -97,11 +97,11 @@ public:
         RepairFlag repair, CheckSigsFlag checkSigs) override;
 
     StorePath addToStoreFromDump(Source & dump, const string & name,
-        FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, StorePathSet references ) override;
+        FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, const StorePathSet & references ) override;
 
     StorePath addToStore(const string & name, const Path & srcPath,
         FileIngestionMethod method, HashType hashAlgo,
-        PathFilter & filter, RepairFlag repair, StorePathSet references) override;
+        PathFilter & filter, RepairFlag repair, const StorePathSet & references) override;
 
     StorePath addTextToStore(const string & name, const string & s,
         const StorePathSet & references, RepairFlag repair) override;
diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 694c408f3..383c6b990 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -1180,7 +1180,7 @@ struct RestrictedStore : public virtual RestrictedStoreConfig, public virtual Lo
     StorePath addToStore(const string & name, const Path & srcPath,
         FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256,
         PathFilter & filter = defaultPathFilter, RepairFlag repair = NoRepair,
-        StorePathSet references = StorePathSet()) override
+        const StorePathSet & references = StorePathSet()) override
     { throw Error("addToStore"); }
 
     void addToStore(const ValidPathInfo & info, Source & narSource,
@@ -1200,7 +1200,7 @@ struct RestrictedStore : public virtual RestrictedStoreConfig, public virtual Lo
 
     StorePath addToStoreFromDump(Source & dump, const string & name,
         FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair,
-        StorePathSet references = StorePathSet()) override
+        const StorePathSet & references = StorePathSet()) override
     {
         auto path = next->addToStoreFromDump(dump, name, method, hashAlgo, repair, references);
         goal.addDependency(path);
diff --git a/src/libstore/legacy-ssh-store.cc b/src/libstore/legacy-ssh-store.cc
index 433ddc8e1..c4fb91364 100644
--- a/src/libstore/legacy-ssh-store.cc
+++ b/src/libstore/legacy-ssh-store.cc
@@ -227,7 +227,7 @@ struct LegacySSHStore : public virtual LegacySSHStoreConfig, public virtual Stor
 
     StorePath addToStore(const string & name, const Path & srcPath,
         FileIngestionMethod method, HashType hashAlgo,
-        PathFilter & filter, RepairFlag repair, StorePathSet references) override
+        PathFilter & filter, RepairFlag repair, const StorePathSet & references) override
     { unsupported("addToStore"); }
 
     StorePath addTextToStore(const string & name, const string & s,
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 33ac77af5..444308d88 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -1302,7 +1302,7 @@ void LocalStore::addToStore(const ValidPathInfo & info, Source & source,
 
 
 StorePath LocalStore::addToStoreFromDump(Source & source0, const string & name,
-    FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, StorePathSet references)
+    FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, const StorePathSet & references)
 {
     /* For computing the store path. */
     auto hashSink = std::make_unique<HashSink>(hashAlgo);
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 7a7329dd8..c6441ef01 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -140,7 +140,7 @@ public:
         RepairFlag repair, CheckSigsFlag checkSigs) override;
 
     StorePath addToStoreFromDump(Source & dump, const string & name,
-        FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, StorePathSet references) override;
+        FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, const StorePathSet & references) override;
 
     StorePath addTextToStore(const string & name, const string & s,
         const StorePathSet & references, RepairFlag repair) override;
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index 632dfcf21..0db442579 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -578,7 +578,7 @@ ref<const ValidPathInfo> RemoteStore::addCAToStore(
 
 
 StorePath RemoteStore::addToStoreFromDump(Source & dump, const string & name,
-      FileIngestionMethod method, HashType hashType, RepairFlag repair, StorePathSet references)
+      FileIngestionMethod method, HashType hashType, RepairFlag repair, const StorePathSet & references)
 {
     return addCAToStore(dump, name, FixedOutputHashMethod{ .fileIngestionMethod = method, .hashType = hashType }, references, repair)->path;
 }
diff --git a/src/libstore/remote-store.hh b/src/libstore/remote-store.hh
index 31eb1871a..9c3e0bf05 100644
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@@ -73,7 +73,7 @@ public:
 
     /* Add a content-addressable store path. Does not support references. `dump` will be drained. */
     StorePath addToStoreFromDump(Source & dump, const string & name,
-        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair, StorePathSet references = StorePathSet()) override;
+        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair, const StorePathSet & references = StorePathSet()) override;
 
     void addToStore(const ValidPathInfo & info, Source & nar,
         RepairFlag repair, CheckSigsFlag checkSigs) override;
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 84d6db297..329cf679f 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -237,7 +237,7 @@ StorePath Store::computeStorePathForText(const string & name, const string & s,
 
 
 StorePath Store::addToStore(const string & name, const Path & _srcPath,
-    FileIngestionMethod method, HashType hashAlgo, PathFilter & filter, RepairFlag repair, StorePathSet references)
+    FileIngestionMethod method, HashType hashAlgo, PathFilter & filter, RepairFlag repair, const StorePathSet & references)
 {
     Path srcPath(absPath(_srcPath));
     auto source = sinkToSource([&](Sink & sink) {
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index c4fdb176a..34d4dac3c 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -453,7 +453,7 @@ public:
        libutil/archive.hh). */
     virtual StorePath addToStore(const string & name, const Path & srcPath,
         FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256,
-        PathFilter & filter = defaultPathFilter, RepairFlag repair = NoRepair, StorePathSet references = StorePathSet());
+        PathFilter & filter = defaultPathFilter, RepairFlag repair = NoRepair, const StorePathSet & references = StorePathSet());
 
     /* Copy the contents of a path to the store and register the
        validity the resulting path, using a constant amount of
@@ -470,7 +470,7 @@ public:
     // FIXME: remove?
     virtual StorePath addToStoreFromDump(Source & dump, const string & name,
         FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair,
-        StorePathSet references = StorePathSet())
+        const StorePathSet & references = StorePathSet())
     { unsupported("addToStoreFromDump"); }
 
     /* Like addToStore, but the contents written to the output path is

From f7859eef49ea3a3563d821ba17c29deb7757b8a4 Mon Sep 17 00:00:00 2001
From: "Travis A. Everett" <travis.a.everett@gmail.com>
Date: Mon, 8 Nov 2021 20:08:09 -0600
Subject: [PATCH 200/567] installer: improve existing rc backup nag

---
 scripts/install-multi-user.sh | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/scripts/install-multi-user.sh b/scripts/install-multi-user.sh
index 7d1cb8c5a..eb5c48b73 100644
--- a/scripts/install-multi-user.sh
+++ b/scripts/install-multi-user.sh
@@ -387,19 +387,27 @@ EOF
     fi
 
     for profile_target in "${PROFILE_TARGETS[@]}"; do
+        # TODO: I think it would be good to accumulate a list of all
+        #       of the copies so that people don't hit this 2 or 3x in
+        #       a row for different files.
         if [ -e "$profile_target$PROFILE_BACKUP_SUFFIX" ]; then
+            # this backup process first released in Nix 2.1
             failure <<EOF
-When this script runs, it backs up the current $profile_target to
-$profile_target$PROFILE_BACKUP_SUFFIX. This backup file already exists, though.
+I back up shell profile/rc scripts before I add Nix to them.
+I need to back up $profile_target to $profile_target$PROFILE_BACKUP_SUFFIX,
+but the latter already exists.
 
-Please follow these instructions to clean up the old backup file:
+Here's how to clean up the old backup file:
 
-1. Copy $profile_target and $profile_target$PROFILE_BACKUP_SUFFIX to another place, just
-in case.
+1. Back up (copy) $profile_target and $profile_target$PROFILE_BACKUP_SUFFIX
+   to another location, just in case.
 
-2. Take care to make sure that $profile_target$PROFILE_BACKUP_SUFFIX doesn't look like
-it has anything nix-related in it. If it does, something is probably
-quite wrong. Please open an issue or get in touch immediately.
+2. Ensure $profile_target$PROFILE_BACKUP_SUFFIX does not have anything
+   Nix-related in it. If it does, something is probably quite
+   wrong. Please open an issue or get in touch immediately.
+
+3. Once you confirm $profile_target is backed up and doesn't already
+   mention Nix, replace it with $profile_target$PROFILE_BACKUP_SUFFIX.
 EOF
         fi
     done

From ceeecf2f9e62ee9077228f71e714b947b72717a6 Mon Sep 17 00:00:00 2001
From: Matthew Bauer <mjbauer95@gmail.com>
Date: Tue, 9 Nov 2021 11:14:15 -0600
Subject: [PATCH 201/567] Recognize singular "nixosModule" in nix flake show

This makes nixosModule appears as a "NixOS Module" like nixosModules
does.
---
 src/nix/flake.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 5eeb5498a..97f4d911c 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -1052,7 +1052,8 @@ struct CmdFlakeShow : FlakeCommand, MixJSON
                         (attrPath.size() == 1 && attrPath[0] == "overlay")
                         || (attrPath.size() == 2 && attrPath[0] == "overlays") ? std::make_pair("nixpkgs-overlay", "Nixpkgs overlay") :
                         attrPath.size() == 2 && attrPath[0] == "nixosConfigurations" ? std::make_pair("nixos-configuration", "NixOS configuration") :
-                        attrPath.size() == 2 && attrPath[0] == "nixosModules" ? std::make_pair("nixos-module", "NixOS module") :
+                        (attrPath.size() == 1 && attrPath[0] == "nixosModule")
+                        || (attrPath.size() == 2 && attrPath[0] == "nixosModules") ? std::make_pair("nixos-module", "NixOS module") :
                         std::make_pair("unknown", "unknown");
                     if (json) {
                         j.emplace("type", type);

From edfc5b2f127bfbaebbd48fcd7b35034345ce2cfa Mon Sep 17 00:00:00 2001
From: Sergei Trofimovich <slyich@gmail.com>
Date: Sat, 9 Oct 2021 18:47:05 +0100
Subject: [PATCH 202/567] ca-specific-schema.sql: add index on
 RealisationsRefs(referrer) and (outputPath)

For a typical desktop system (~2K packages) we can easily get 100K
entries in RealisationsRefs. Without indices query for RealisationsRefs
requires linear scan.

RealisationsRefs(referrer)
--------------------------

Inefficiency is seen as a 100% CPU load of nix-daemon for the following
scenario:

    $ nix edit -f . bash # add unused environment variable, like FOO="1"
    # populate RealisationsRefs, build fresh system
    $ nix build -f nixos system --arg config '{ contentAddressedByDefault = true; }'
    $ nix edit -f . bash # add unused environment variable, like FOO="2"
    $ time nix build -f nixos system --arg config '{ contentAddressedByDefault = true; }'

In this case `bash `will be rebuilt a few times and then rest of CPU
time is spent on scanning RealisationsRefs table (about 5 CPU-minutes
on my machine).

Before the change:

    $ time nix build -f nixos system ... # step 4 above
    real    34m3,613s
    user    0m5,232s
    sys     0m0,758s

Of all this time about 29.5 minutes are taken by nix-daemon's CPU time.

After the change:

    $ time nix build -f nixos system ... # step 4 above
    real    4m50,061s
    user    0m5,038s
    sys     0m0,677s

Of all this time about 1 minute is taken by nix-daemon's CPU time.
Most of the time is spent polling for non-existent realisations on
cache-nixos.org.

Realisations(outputPath)
------------------------

After running CA system for two weeks I got ~1M entries in Realisations
table. `nix-collect-garbage` became very slow (seemingly 100 path deletions
per second). It happens due to a slow cascading delete from Realisations
triggered by deletion from ValidPaths.

The fix is to add an index on primary key from ValidPaths(id) that
triggers cascading deletions.

Before the change:
    $ time nix-collect-garbage -d --max-freed 100G
    <interrupted before finish, took too long>
    real    23m32.411s
    user    17m49.679s
    sys     4m50.609s

Most of time was spent in re-scanning Realisations table on each path deletion.

After the change:
    $ time nix-collect-garbage -d --max-freed 100G

    real    8m43.226s
    user    6m16.317s
    sys     1m40.188s

Time is spent scanning sqlite indices and in kernel when unlinking directories.
---
 src/libstore/ca-specific-schema.sql |  5 +++++
 src/libstore/local-store.cc         | 13 ++++++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/libstore/ca-specific-schema.sql b/src/libstore/ca-specific-schema.sql
index 08af0cc1f..64cc97fde 100644
--- a/src/libstore/ca-specific-schema.sql
+++ b/src/libstore/ca-specific-schema.sql
@@ -19,3 +19,8 @@ create table if not exists RealisationsRefs (
     foreign key (referrer) references Realisations(id) on delete cascade,
     foreign key (realisationReference) references Realisations(id) on delete restrict
 );
+
+-- used by QueryRealisationReferences
+create index if not exists IndexRealisationsRefs on RealisationsRefs(referrer);
+-- used by cascade deletion when ValidPaths is deleted
+create index if not exists IndexRealisationsRefsOnOutputPath on Realisations(outputPath);
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index eecd407f5..fcddd1f8e 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -79,7 +79,7 @@ int getSchema(Path schemaPath)
 
 void migrateCASchema(SQLite& db, Path schemaPath, AutoCloseFD& lockFd)
 {
-    const int nixCASchemaVersion = 2;
+    const int nixCASchemaVersion = 3;
     int curCASchema = getSchema(schemaPath);
     if (curCASchema != nixCASchemaVersion) {
         if (curCASchema > nixCASchemaVersion) {
@@ -130,6 +130,17 @@ void migrateCASchema(SQLite& db, Path schemaPath, AutoCloseFD& lockFd)
             txn.commit();
         }
 
+        if (curCASchema < 3) {
+            SQLiteTxn txn(db);
+            // Apply new indices added in this schema update.
+            db.exec(R"(
+                -- used by QueryRealisationReferences
+                create index if not exists IndexRealisationsRefs on RealisationsRefs(referrer);
+                -- used by cascade deletion when ValidPaths is deleted
+                create index if not exists IndexRealisationsRefsOnOutputPath on Realisations(outputPath);
+            )");
+            txn.commit();
+        }
         writeFile(schemaPath, fmt("%d", nixCASchemaVersion));
         lockFile(lockFd.get(), ltRead, true);
     }

From cc78901ccbfd1e7b12da7b24ea0866e53db3dac8 Mon Sep 17 00:00:00 2001
From: "Travis A. Everett" <travis.a.everett@gmail.com>
Date: Wed, 10 Nov 2021 14:06:18 -0600
Subject: [PATCH 203/567] installer: make rc replacement instructions explicit

---
 scripts/install-multi-user.sh | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/scripts/install-multi-user.sh b/scripts/install-multi-user.sh
index eb5c48b73..eba894799 100644
--- a/scripts/install-multi-user.sh
+++ b/scripts/install-multi-user.sh
@@ -406,8 +406,9 @@ Here's how to clean up the old backup file:
    Nix-related in it. If it does, something is probably quite
    wrong. Please open an issue or get in touch immediately.
 
-3. Once you confirm $profile_target is backed up and doesn't already
-   mention Nix, replace it with $profile_target$PROFILE_BACKUP_SUFFIX.
+3. Once you confirm $profile_target is backed up and
+   $profile_target$PROFILE_BACKUP_SUFFIX doesn't mention Nix, run:
+   mv $profile_target$PROFILE_BACKUP_SUFFIX $profile_target
 EOF
         fi
     done

From 07bffe799853ef5e2757b9892e4e3dac89bfccbb Mon Sep 17 00:00:00 2001
From: Alexander Bantyev <balsoft@balsoft.ru>
Date: Wed, 10 Nov 2021 14:56:22 +0300
Subject: [PATCH 204/567] Flakes: refetch the input when a follows disappears

When an input follows disappears, we can't just reuse the old lock
file entries since we may be missing some required ones. Refetch the
input when this happens.

Closes https://github.com/NixOS/nix/issues/5289
---
 src/libexpr/flake/flake.cc | 14 ++++++++++++++
 tests/flakes.sh            | 28 +++++++++++++++++++++++++---
 2 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 07ed3caa2..1dc6f5694 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -462,6 +462,8 @@ LockedFlake lockFlake(
                                those. */
                             FlakeInputs fakeInputs;
 
+                            bool refetch = false;
+
                             for (auto & i : oldLock->inputs) {
                                 if (auto lockedNode = std::get_if<0>(&i.second)) {
                                     fakeInputs.emplace(i.first, FlakeInput {
@@ -469,12 +471,24 @@ LockedFlake lockFlake(
                                         .isFlake = (*lockedNode)->isFlake,
                                     });
                                 } else if (auto follows = std::get_if<1>(&i.second)) {
+                                    auto o = input.overrides.find(i.first);
+                                    // If the override disappeared, we have to refetch the flake,
+                                    // since some of the inputs may not be present in the lockfile.
+                                    if (o == input.overrides.end()) {
+                                        refetch = true;
+                                        // There's no point populating the rest of the fake inputs,
+                                        // since we'll refetch the flake anyways.
+                                        break;
+                                    }
                                     fakeInputs.emplace(i.first, FlakeInput {
                                         .follows = *follows,
                                     });
                                 }
                             }
 
+                            if (refetch)
+                                fakeInputs = getFlake(state, oldLock->lockedRef, false, flakeCache).inputs;
+
                             computeLocks(fakeInputs, childNode, inputPath, oldLock, parent, parentPath);
                         }
 
diff --git a/tests/flakes.sh b/tests/flakes.sh
index 57d1b9aad..9e10322b9 100644
--- a/tests/flakes.sh
+++ b/tests/flakes.sh
@@ -707,10 +707,10 @@ cat > $flakeFollowsA/flake.nix <<EOF
         B = {
             url = "path:./flakeB";
             inputs.foobar.follows = "D";
+            inputs.nonFlake.follows = "D";
         };
 
         D.url = "path:./flakeD";
-        foobar.url = "path:./flakeE";
     };
     outputs = { ... }: {};
 }
@@ -720,7 +720,8 @@ cat > $flakeFollowsB/flake.nix <<EOF
 {
     description = "Flake B";
     inputs = {
-        foobar.url = "path:./../flakeE";
+        foobar.url = "path:$flakeFollowsA/flakeE";
+        nonFlake.url = "path:$nonFlakeDir";
         C = {
             url = "path:./flakeC";
             inputs.foobar.follows = "foobar";
@@ -734,7 +735,7 @@ cat > $flakeFollowsC/flake.nix <<EOF
 {
     description = "Flake C";
     inputs = {
-        foobar.url = "path:./../../flakeE";
+        foobar.url = "path:$flakeFollowsA/flakeE";
     };
     outputs = { ... }: {};
 }
@@ -765,6 +766,27 @@ nix flake lock $flakeFollowsA
 [[ $(jq -c .nodes.B.inputs.foobar $flakeFollowsA/flake.lock) = '["D"]' ]]
 [[ $(jq -c .nodes.C.inputs.foobar $flakeFollowsA/flake.lock) = '["B","foobar"]' ]]
 
+# Ensure removing follows from flake.nix removes them from the lockfile
+
+cat > $flakeFollowsA/flake.nix <<EOF
+{
+    description = "Flake A";
+    inputs = {
+        B = {
+            url = "path:./flakeB";
+            inputs.nonFlake.follows = "D";
+        };
+        D.url = "path:./flakeD";
+    };
+    outputs = { ... }: {};
+}
+EOF
+
+nix flake lock $flakeFollowsA
+
+[[ $(jq -c .nodes.B.inputs.foobar $flakeFollowsA/flake.lock) = '"foobar"' ]]
+jq -r -c '.nodes | keys | .[]' $flakeFollowsA/flake.lock | grep "^foobar$"
+
 # Ensure a relative path is not allowed to go outside the store path
 cat > $flakeFollowsA/flake.nix <<EOF
 {

From 3884f7a69a57d8ecfcbcaae476ec2ff53ffbd549 Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Thu, 11 Nov 2021 11:03:21 +0100
Subject: [PATCH 205/567] Install nlohmann_json headers

These headers are included by the libexpr, libfetchers, libstore
and libutil headers.
Considering that these are vendored sources, Nix should expose them,
as it is not a good idea for reverse dependencies to rely on a
potentially different source that can go out of sync.
---
 Makefile              | 1 +
 src/nlohmann/local.mk | 2 ++
 2 files changed, 3 insertions(+)
 create mode 100644 src/nlohmann/local.mk

diff --git a/Makefile b/Makefile
index 5040d2884..e6ce50cbd 100644
--- a/Makefile
+++ b/Makefile
@@ -10,6 +10,7 @@ makefiles = \
   src/libexpr/local.mk \
   src/libcmd/local.mk \
   src/nix/local.mk \
+  src/nlohmann/local.mk \
   src/resolve-system-dependencies/local.mk \
   scripts/local.mk \
   misc/bash/local.mk \
diff --git a/src/nlohmann/local.mk b/src/nlohmann/local.mk
new file mode 100644
index 000000000..63c427e00
--- /dev/null
+++ b/src/nlohmann/local.mk
@@ -0,0 +1,2 @@
+$(foreach i, $(wildcard src/nlohmann/*.hpp), \
+  $(eval $(call install-file-in, $(i), $(includedir)/nlohmann, 0644)))

From 93f7fb6e74605fd533c7267dc349e904d6dd5680 Mon Sep 17 00:00:00 2001
From: Rok Garbas <rok@garbas.si>
Date: Sun, 31 Oct 2021 00:22:35 +0200
Subject: [PATCH 206/567] Docker image with Nix inside

---
 docker.nix | 264 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 flake.nix  |   7 ++
 2 files changed, 271 insertions(+)
 create mode 100644 docker.nix

diff --git a/docker.nix b/docker.nix
new file mode 100644
index 000000000..40af2f38b
--- /dev/null
+++ b/docker.nix
@@ -0,0 +1,264 @@
+{ pkgs ? import <nixpkgs> { }
+, lib ? pkgs.lib
+, name ? "nix"
+, tag ? "latest"
+, crossSystem ? null
+, channelName ? "nixpkgs"
+, channelURL ? "https://nixos.org/channels/nixpkgs-unstable"
+}:
+let
+  buildPkgs = pkgs;
+  targetPkgs =
+    if crossSystem != null && crossSystem != pkgs.system
+    then {
+      aarch64-linux = pkgs.pkgsCross.aarch64-multiplatform;
+      armv7l-linux = pkgs.pkgsCross.armv7l-hf-multiplatform.system;
+      x86_64-linux = pkgs.pkgsCross.gnu64;
+      powerpc64le-linux = pkgs.pkgsCross.musl-power;
+      i686-linux = pkgs.pkgsCross.gnu32;
+    }.${crossSystem}
+    else pkgs;
+
+  defaultPkgs = [
+    targetPkgs.nix
+    targetPkgs.bashInteractive
+    targetPkgs.coreutils-full
+    targetPkgs.gnutar
+    targetPkgs.gzip
+    targetPkgs.gnugrep
+    targetPkgs.which
+    targetPkgs.curl
+    targetPkgs.less
+    targetPkgs.wget
+    targetPkgs.man
+    targetPkgs.cacert.out
+    targetPkgs.findutils
+  ];
+
+  users = {
+
+    root = {
+      uid = 0;
+      shell = "/bin/bash";
+      home = "/root";
+      gid = 0;
+    };
+
+  } // lib.listToAttrs (
+    map
+      (
+        n: {
+          name = "nixbld${toString n}";
+          value = {
+            uid = 30000 + n;
+            gid = 30000;
+            groups = [ "nixbld" ];
+            description = "Nix build user ${toString n}";
+          };
+        }
+      )
+      (lib.lists.range 1 32)
+  );
+
+  groups = {
+    root.gid = 0;
+    nixbld.gid = 30000;
+  };
+
+  userToPasswd = (
+    k:
+    { uid
+    , gid ? 65534
+    , home ? "/var/empty"
+    , description ? ""
+    , shell ? "/bin/false"
+    , groups ? [ ]
+    }: "${k}:x:${toString uid}:${toString gid}:${description}:${home}:${shell}"
+  );
+  passwdContents = (
+    lib.concatStringsSep "\n"
+      (lib.attrValues (lib.mapAttrs userToPasswd users))
+  );
+
+  userToShadow = k: { ... }: "${k}:!:1::::::";
+  shadowContents = (
+    lib.concatStringsSep "\n"
+      (lib.attrValues (lib.mapAttrs userToShadow users))
+  );
+
+  # Map groups to members
+  # {
+  #   group = [ "user1" "user2" ];
+  # }
+  groupMemberMap = (
+    let
+      # Create a flat list of user/group mappings
+      mappings = (
+        builtins.foldl'
+          (
+            acc: user:
+              let
+                groups = users.${user}.groups or [ ];
+              in
+              acc ++ map
+                (group: {
+                  inherit user group;
+                })
+                groups
+          )
+          [ ]
+          (lib.attrNames users)
+      );
+    in
+    (
+      builtins.foldl'
+        (
+          acc: v: acc // {
+            ${v.group} = acc.${v.group} or [ ] ++ [ v.user ];
+          }
+        )
+        { }
+        mappings)
+  );
+
+  groupToGroup = k: { gid }:
+    let
+      members = groupMemberMap.${k} or [ ];
+    in
+    "${k}:x:${toString gid}:${lib.concatStringsSep "," members}";
+  groupContents = (
+    lib.concatStringsSep "\n"
+      (lib.attrValues (lib.mapAttrs groupToGroup groups))
+  );
+
+  nixConf = {
+    sandbox = "false";
+    build-users-group = "nixbld";
+    trusted-public-keys = "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=";
+  };
+  nixConfContents = (lib.concatStringsSep "\n" (lib.mapAttrsFlatten (n: v: "${n} = ${v}") nixConf)) + "\n";
+
+  baseSystem =
+    let
+      nixpkgs = targetPkgs.path;
+      channel = targetPkgs.runCommand "channel-nixos" { } ''
+        mkdir $out
+        ln -s ${nixpkgs} $out/nixpkgs
+        echo "[]" > $out/manifest.nix
+      '';
+      rootEnv = pkgs.buildEnv {
+        name = "root-profile-env";
+        paths = defaultPkgs;
+      };
+      profile = targetPkgs.runCommand "user-environment" { } ''
+        mkdir $out
+        cp -a ${rootEnv}/* $out/
+
+        cat > $out/manifest.nix <<EOF
+        [
+        ${lib.concatStringsSep "\n" (builtins.map (drv: let
+          outputs = drv.outputsToInstall or [ "out" ];
+        in ''
+          {
+            ${lib.concatStringsSep "\n" (builtins.map (output: ''
+              ${output} = { outPath = "${lib.getOutput output drv}"; };
+            '') outputs)}
+            outputs = [ ${lib.concatStringsSep " " (builtins.map (x: "\"${x}\"") outputs)} ];
+            name = "${drv.name}";
+            outPath = "${drv}";
+            system = "${drv.system}";
+            type = "derivation";
+            meta = { };
+          }
+        '') defaultPkgs)}
+        ]
+        EOF
+      '';
+    in
+    targetPkgs.runCommand "base-system"
+      {
+        inherit passwdContents groupContents shadowContents nixConfContents;
+        passAsFile = [
+          "passwdContents"
+          "groupContents"
+          "shadowContents"
+          "nixConfContents"
+        ];
+        allowSubstitutes = false;
+        preferLocalBuild = true;
+      } ''
+      env
+      set -x
+      mkdir -p $out/etc
+
+      cat $passwdContentsPath > $out/etc/passwd
+      echo "" >> $out/etc/passwd
+
+      cat $groupContentsPath > $out/etc/group
+      echo "" >> $out/etc/group
+
+      cat $shadowContentsPath > $out/etc/shadow
+      echo "" >> $out/etc/shadow
+
+      mkdir -p $out/usr
+      ln -s /nix/var/nix/profiles/share $out/usr/
+
+      mkdir -p $out/nix/var/nix/gcroots
+
+      mkdir $out/tmp
+
+      mkdir -p $out/etc/nix
+      cat $nixConfContentsPath > $out/etc/nix/nix.conf
+
+      mkdir -p $out/root
+      mkdir -p $out/nix/var/nix/profiles/per-user/root
+
+      ln -s ${profile} $out/nix/var/nix/profiles/default-1-link
+      ln -s $out/nix/var/nix/profiles/default-1-link $out/nix/var/nix/profiles/default
+      ln -s /nix/var/nix/profiles/default $out/root/.nix-profile
+
+      ln -s ${channel} $out/nix/var/nix/profiles/per-user/root/channels-1-link
+      ln -s $out/nix/var/nix/profiles/per-user/root/channels-1-link $out/nix/var/nix/profiles/per-user/root/channels
+
+      mkdir -p $out/root/.nix-defexpr
+      ln -s $out/nix/var/nix/profiles/per-user/root/channels $out/root/.nix-defexpr/channels
+      echo "${channelURL} ${channelName}" > $out/root/.nix-channels
+
+      mkdir -p $out/bin $out/usr/bin
+      ln -s ${targetPkgs.coreutils}/bin/env $out/usr/bin/env
+      ln -s ${targetPkgs.bashInteractive}/bin/bash $out/bin/sh
+    '';
+
+in
+targetPkgs.dockerTools.buildLayeredImageWithNixDb {
+
+  inherit name tag;
+
+  contents = [ baseSystem ];
+
+  extraCommands = ''
+    rm -rf nix-support
+    ln -s /nix/var/nix/profiles nix/var/nix/gcroots/profiles
+  '';
+
+  config = {
+    Cmd = [ "/root/.nix-profile/bin/bash" ];
+    Env = [
+      "USER=root"
+      "PATH=${lib.concatStringsSep ":" [
+        "/root/.nix-profile/bin"
+        "/nix/var/nix/profiles/default/bin"
+        "/nix/var/nix/profiles/default/sbin"
+      ]}"
+      "MANPATH=${lib.concatStringsSep ":" [
+        "/root/.nix-profile/share/man"
+        "/nix/var/nix/profiles/default/share/man"
+      ]}"
+      "SSL_CERT_FILE=/nix/var/nix/profiles/default/etc/ssl/certs/ca-bundle.crt"
+      "GIT_SSL_CAINFO=/nix/var/nix/profiles/default/etc/ssl/certs/ca-bundle.crt"
+      "NIX_SSL_CERT_FILE=/nix/var/nix/profiles/default/etc/ssl/certs/ca-bundle.crt"
+      "NIX_PATH=/nix/var/nix/profiles/per-user/root/channels:/root/.nix-defexpr/channels"
+    ];
+  };
+
+}
diff --git a/flake.nix b/flake.nix
index ed622ec86..fd5e18429 100644
--- a/flake.nix
+++ b/flake.nix
@@ -405,6 +405,13 @@
         installerScript = installScriptFor [ "x86_64-linux" "i686-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" "armv6l-linux" "armv7l-linux" ];
         installerScriptForGHA = installScriptFor [ "x86_64-linux" "x86_64-darwin" "armv6l-linux" "armv7l-linux"];
 
+        # docker image with Nix inside
+        dockerImage = nixpkgs.lib.genAttrs linux64BitSystems (system:
+          import ./docker.nix {
+            pkgs = nixpkgsFor.${system};
+            tag = version;
+          });
+
         # Line coverage analysis.
         coverage =
           with nixpkgsFor.x86_64-linux;

From c1bf9e39f1138bc43fdfa0c649af33e63f57617a Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 2 Nov 2021 14:03:55 +0100
Subject: [PATCH 207/567] docker.nix: Use 'with'

Co-authored-by: Sandro <sandro.jaeckel@gmail.com>
---
 docker.nix | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/docker.nix b/docker.nix
index 40af2f38b..316d57a36 100644
--- a/docker.nix
+++ b/docker.nix
@@ -19,20 +19,20 @@ let
     }.${crossSystem}
     else pkgs;
 
-  defaultPkgs = [
-    targetPkgs.nix
-    targetPkgs.bashInteractive
-    targetPkgs.coreutils-full
-    targetPkgs.gnutar
-    targetPkgs.gzip
-    targetPkgs.gnugrep
-    targetPkgs.which
-    targetPkgs.curl
-    targetPkgs.less
-    targetPkgs.wget
-    targetPkgs.man
-    targetPkgs.cacert.out
-    targetPkgs.findutils
+  defaultPkgs = with targetPkgs; [
+    nix
+    bashInteractive
+    coreutils-full
+    gnutar
+    gzip
+    gnugrep
+    which
+    curl
+    less
+    wget
+    man
+    cacert.out
+    findutils
   ];
 
   users = {

From a118a70649ca2be9c36e526269ee54bc87ea06d4 Mon Sep 17 00:00:00 2001
From: Rok Garbas <rok@garbas.si>
Date: Thu, 11 Nov 2021 16:03:09 +0100
Subject: [PATCH 208/567] Documenting how to use/build Nix' Docker image

---
 doc/manual/src/SUMMARY.md.in                  |  1 +
 .../src/installation/installing-docker.md     | 59 +++++++++++++++++++
 2 files changed, 60 insertions(+)
 create mode 100644 doc/manual/src/installation/installing-docker.md

diff --git a/doc/manual/src/SUMMARY.md.in b/doc/manual/src/SUMMARY.md.in
index 3869f4791..8d9b061ba 100644
--- a/doc/manual/src/SUMMARY.md.in
+++ b/doc/manual/src/SUMMARY.md.in
@@ -9,6 +9,7 @@
     - [Prerequisites](installation/prerequisites-source.md)
     - [Obtaining a Source Distribution](installation/obtaining-source.md)
     - [Building Nix from Source](installation/building-source.md)
+  - [Using Nix within Docker](installation/installing-docker.md)
   - [Security](installation/nix-security.md)
     - [Single-User Mode](installation/single-user.md)
     - [Multi-User Mode](installation/multi-user.md)
diff --git a/doc/manual/src/installation/installing-docker.md b/doc/manual/src/installation/installing-docker.md
new file mode 100644
index 000000000..3d2255b7a
--- /dev/null
+++ b/doc/manual/src/installation/installing-docker.md
@@ -0,0 +1,59 @@
+# Using Nix within Docker
+
+To run the latest stable release of Nix with Docker run the following command:
+
+```console
+$ docker -ti run nixos/nix
+Unable to find image 'nixos/nix:latest' locally
+latest: Pulling from nixos/nix
+5843afab3874: Pull complete
+b52bf13f109c: Pull complete
+1e2415612aa3: Pull complete
+Digest: sha256:27f6e7f60227e959ee7ece361f75d4844a40e1cc6878b6868fe30140420031ff
+Status: Downloaded newer image for nixos/nix:latest
+35ca4ada6e96:/# nix --version
+nix (Nix) 2.3.12
+35ca4ada6e96:/# exit
+```
+
+# What is included in Nix' Docker image?
+
+The official Docker image is created using `pkgs.dockerTools.buildLayeredImage`
+(and not with `Dockerfile` as it is usual with Docker images). You can still
+base your custom Docker image on it as you would do with any other Docker
+image.
+
+The Docker image is also not based on any other image and includes minimal set
+of runtime dependencies that are required to use Nix:
+
+ - pkgs.nix
+ - pkgs.bashInteractive
+ - pkgs.coreutils-full
+ - pkgs.gnutar
+ - pkgs.gzip
+ - pkgs.gnugrep
+ - pkgs.which
+ - pkgs.curl
+ - pkgs.less
+ - pkgs.wget
+ - pkgs.man
+ - pkgs.cacert.out
+ - pkgs.findutils
+
+# Docker image with the latest development version of Nix
+
+To get the latest image that was built by [Hydra](https://hydra.nixos.org) run
+the following command:
+
+```console
+$ curl -L https://hydra.nixos.org/job/nix/master/dockerImage.x86_64-linux/latest/download/1 | docker load
+$ docker run -ti nix:2.5pre20211105
+```
+
+You can also build a Docker image from source yourself:
+
+```console
+$ nix build ./\#hydraJobs.dockerImage.x86_64-linux
+$ docker load -i ./result
+$ docker run -ti nix:2.5pre20211105
+```

From c1dea92dd6fb5c07127bcf43d8c76d8a59470d7a Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Thu, 11 Nov 2021 21:29:18 -0500
Subject: [PATCH 209/567] nix key: Fix error message and don't require flakes

---
 src/nix/sigs.cc | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/nix/sigs.cc b/src/nix/sigs.cc
index 6a238efbe..3d659d6d2 100644
--- a/src/nix/sigs.cc
+++ b/src/nix/sigs.cc
@@ -218,8 +218,7 @@ struct CmdKey : NixMultiCommand
     void run() override
     {
         if (!command)
-            throw UsageError("'nix flake' requires a sub-command.");
-        settings.requireExperimentalFeature(Xp::Flakes);
+            throw UsageError("'nix key' requires a sub-command.");
         command->second->prepare();
         command->second->run();
     }

From 30e5c5c55fb84a103575fda72fa11c7b1b88d928 Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Fri, 12 Nov 2021 03:18:31 -0500
Subject: [PATCH 210/567] nix registry: Mark experimental

This is part of the flakes feature. Mark it as such.
---
 src/nix/registry.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/nix/registry.cc b/src/nix/registry.cc
index 6a92576c7..c496f94f8 100644
--- a/src/nix/registry.cc
+++ b/src/nix/registry.cc
@@ -226,6 +226,7 @@ struct CmdRegistry : virtual NixMultiCommand
 
     void run() override
     {
+        settings.requireExperimentalFeature(Xp::Flakes);
         if (!command)
             throw UsageError("'nix registry' requires a sub-command.");
         command->second->prepare();

From bceda304982a34c65d5a1dab449cb5bc59f63b83 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 12 Nov 2021 13:41:15 +0100
Subject: [PATCH 211/567] Typo

---
 src/libstore/build/local-derivation-goal.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 2ba79ec46..589b449d0 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -1993,7 +1993,7 @@ void LocalDerivationGoal::runChild()
                 else if (drv->builder == "builtin:unpack-channel")
                     builtinUnpackChannel(drv2);
                 else
-                    throw Error("unsupported builtin function '%1%'", string(drv->builder, 8));
+                    throw Error("unsupported builtin builder '%1%'", string(drv->builder, 8));
                 _exit(0);
             } catch (std::exception & e) {
                 writeFull(STDERR_FILENO, e.what() + std::string("\n"));

From 30496af5980fd03706f587eef014e630e9d9d318 Mon Sep 17 00:00:00 2001
From: Tom Bereknyei <tomberek@gmail.com>
Date: Fri, 12 Nov 2021 09:50:07 -0500
Subject: [PATCH 212/567] Adds an accept-flake-config flag

---
 src/libexpr/flake/config.cc | 23 +++++++++++------------
 src/libstore/globals.hh     |  3 +++
 2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/src/libexpr/flake/config.cc b/src/libexpr/flake/config.cc
index 41b6f78ed..c03f4106c 100644
--- a/src/libexpr/flake/config.cc
+++ b/src/libexpr/flake/config.cc
@@ -1,4 +1,5 @@
 #include "flake.hh"
+#include "globals.hh"
 
 #include <nlohmann/json.hpp>
 
@@ -52,21 +53,19 @@ void ConfigFile::apply()
             auto trustedList = readTrustedList();
 
             bool trusted = false;
-
-            if (auto saved = get(get(trustedList, name).value_or(std::map<std::string, bool>()), valueS)) {
+            if (nix::settings.acceptFlakeConfig){
+                trusted = true;
+            } else if (auto saved = get(get(trustedList, name).value_or(std::map<std::string, bool>()), valueS)) {
                 trusted = *saved;
+                warn("Using saved setting for '%s = %s' from ~/.local/share/nix/trusted-settings.json.", name,valueS);
             } else {
                 // FIXME: filter ANSI escapes, newlines, \r, etc.
-                if (std::tolower(logger->ask(fmt("do you want to allow configuration setting '%s' to be set to '" ANSI_RED "%s" ANSI_NORMAL "' (y/N)?", name, valueS)).value_or('n')) != 'y') {
-                    if (std::tolower(logger->ask("do you want to permanently mark this value as untrusted (y/N)?").value_or('n')) == 'y') {
-                        trustedList[name][valueS] = false;
-                        writeTrustedList(trustedList);
-                    }
-                } else {
-                    if (std::tolower(logger->ask("do you want to permanently mark this value as trusted (y/N)?").value_or('n')) == 'y') {
-                        trustedList[name][valueS] = trusted = true;
-                        writeTrustedList(trustedList);
-                    }
+                if (std::tolower(logger->ask(fmt("do you want to allow configuration setting '%s' to be set to '" ANSI_RED "%s" ANSI_NORMAL "' (y/N)?", name, valueS)).value_or('n')) == 'y') {
+                    trusted = true;
+                }
+                if (std::tolower(logger->ask(fmt("do you want to permanently mark this value as %s (y/N)?",  trusted ? "trusted": "untrusted" )).value_or('n')) == 'y') {
+                    trustedList[name][valueS] = trusted;
+                    writeTrustedList(trustedList);
                 }
             }
 
diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index 165639261..a50eb6803 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -951,6 +951,9 @@ public:
 
     Setting<bool> useRegistries{this, true, "use-registries",
         "Whether to use flake registries to resolve flake references."};
+
+    Setting<bool> acceptFlakeConfig{this, false, "accept-flake-config",
+        "Whether to accept nix configuration from a flake without prompting."};
 };
 
 

From 83af9550a166ece787bbea6014d827d3e3af277b Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Fri, 12 Nov 2021 16:02:32 +0100
Subject: [PATCH 213/567] Add a test for the `--accept-flake-config` option

---
 tests/flake-local-settings.sh | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/tests/flake-local-settings.sh b/tests/flake-local-settings.sh
index c037431c8..6ee6b17d6 100644
--- a/tests/flake-local-settings.sh
+++ b/tests/flake-local-settings.sh
@@ -25,11 +25,5 @@ cat <<EOF > flake.nix
 }
 EOF
 
-# Ugly hack for testing
-mkdir -p .local/share/nix
-cat <<EOF > .local/share/nix/trusted-settings.json
-{"post-build-hook":{"$PWD/echoing-post-hook.sh":true}}
-EOF
-
-nix build
+nix build --accept-flake-config
 test -f post-hook-ran || fail "The post hook should have ran"

From d0e9e184895b62d193a6eff5e332a338d3664e5b Mon Sep 17 00:00:00 2001
From: Kevin Amado <kamadorueda@gmail.com>
Date: Sat, 13 Nov 2021 20:29:31 -0500
Subject: [PATCH 214/567] toXML: display errors position

- This change applies to builtins.toXML and inner workings
- Proof of concept:
  ```nix
  let e = builtins.toXML e; in e
  ```
- Before:
  ```
  $ nix-instantiate --eval poc.nix
  error: infinite recursion encountered
  ```
- After:
  ```
  $ nix-instantiate --eval poc.nix
  error: infinite recursion encountered

       at /data/github/kamadorueda/nix/poc.nix:1:9:

            1| let e = builtins.toXML e; in e
             |
  ```
---
 src/libexpr/primops.cc                 |  2 +-
 src/libexpr/value-to-xml.cc            | 25 ++++++++++++++-----------
 src/libexpr/value-to-xml.hh            |  4 ++--
 src/libexpr/value.hh                   |  3 ++-
 src/nix-instantiate/nix-instantiate.cc |  2 +-
 5 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index aaeafb931..668ad00ec 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1582,7 +1582,7 @@ static void prim_toXML(EvalState & state, const Pos & pos, Value * * args, Value
 {
     std::ostringstream out;
     PathSet context;
-    printValueAsXML(state, true, false, *args[0], out, context);
+    printValueAsXML(state, true, false, *args[0], out, context, pos);
     mkString(v, out.str(), context);
 }
 
diff --git a/src/libexpr/value-to-xml.cc b/src/libexpr/value-to-xml.cc
index b44455f5f..54268ece0 100644
--- a/src/libexpr/value-to-xml.cc
+++ b/src/libexpr/value-to-xml.cc
@@ -18,7 +18,8 @@ static XMLAttrs singletonAttrs(const string & name, const string & value)
 
 
 static void printValueAsXML(EvalState & state, bool strict, bool location,
-    Value & v, XMLWriter & doc, PathSet & context, PathSet & drvsSeen);
+    Value & v, XMLWriter & doc, PathSet & context, PathSet & drvsSeen,
+    const Pos & pos);
 
 
 static void posToXML(XMLAttrs & xmlAttrs, const Pos & pos)
@@ -46,17 +47,18 @@ static void showAttrs(EvalState & state, bool strict, bool location,
 
         XMLOpenElement _(doc, "attr", xmlAttrs);
         printValueAsXML(state, strict, location,
-            *a.value, doc, context, drvsSeen);
+            *a.value, doc, context, drvsSeen, *a.pos);
     }
 }
 
 
 static void printValueAsXML(EvalState & state, bool strict, bool location,
-    Value & v, XMLWriter & doc, PathSet & context, PathSet & drvsSeen)
+    Value & v, XMLWriter & doc, PathSet & context, PathSet & drvsSeen,
+    const Pos & pos)
 {
     checkInterrupt();
 
-    if (strict) state.forceValue(v);
+    if (strict) state.forceValue(v, pos);
 
     switch (v.type()) {
 
@@ -91,14 +93,14 @@ static void printValueAsXML(EvalState & state, bool strict, bool location,
                 Path drvPath;
                 a = v.attrs->find(state.sDrvPath);
                 if (a != v.attrs->end()) {
-                    if (strict) state.forceValue(*a->value);
+                    if (strict) state.forceValue(*a->value, *a->pos);
                     if (a->value->type() == nString)
                         xmlAttrs["drvPath"] = drvPath = a->value->string.s;
                 }
 
                 a = v.attrs->find(state.sOutPath);
                 if (a != v.attrs->end()) {
-                    if (strict) state.forceValue(*a->value);
+                    if (strict) state.forceValue(*a->value, *a->pos);
                     if (a->value->type() == nString)
                         xmlAttrs["outPath"] = a->value->string.s;
                 }
@@ -121,7 +123,7 @@ static void printValueAsXML(EvalState & state, bool strict, bool location,
         case nList: {
             XMLOpenElement _(doc, "list");
             for (unsigned int n = 0; n < v.listSize(); ++n)
-                printValueAsXML(state, strict, location, *v.listElems()[n], doc, context, drvsSeen);
+                printValueAsXML(state, strict, location, *v.listElems()[n], doc, context, drvsSeen, pos);
             break;
         }
 
@@ -149,7 +151,7 @@ static void printValueAsXML(EvalState & state, bool strict, bool location,
         }
 
         case nExternal:
-            v.external->printValueAsXML(state, strict, location, doc, context, drvsSeen);
+            v.external->printValueAsXML(state, strict, location, doc, context, drvsSeen, pos);
             break;
 
         case nFloat:
@@ -163,19 +165,20 @@ static void printValueAsXML(EvalState & state, bool strict, bool location,
 
 
 void ExternalValueBase::printValueAsXML(EvalState & state, bool strict,
-    bool location, XMLWriter & doc, PathSet & context, PathSet & drvsSeen) const
+    bool location, XMLWriter & doc, PathSet & context, PathSet & drvsSeen,
+    const Pos & pos) const
 {
     doc.writeEmptyElement("unevaluated");
 }
 
 
 void printValueAsXML(EvalState & state, bool strict, bool location,
-    Value & v, std::ostream & out, PathSet & context)
+    Value & v, std::ostream & out, PathSet & context, const Pos & pos)
 {
     XMLWriter doc(true, out);
     XMLOpenElement root(doc, "expr");
     PathSet drvsSeen;
-    printValueAsXML(state, strict, location, v, doc, context, drvsSeen);
+    printValueAsXML(state, strict, location, v, doc, context, drvsSeen, pos);
 }
 
 
diff --git a/src/libexpr/value-to-xml.hh b/src/libexpr/value-to-xml.hh
index 97657327e..cc778a2cb 100644
--- a/src/libexpr/value-to-xml.hh
+++ b/src/libexpr/value-to-xml.hh
@@ -9,6 +9,6 @@
 namespace nix {
 
 void printValueAsXML(EvalState & state, bool strict, bool location,
-    Value & v, std::ostream & out, PathSet & context);
-    
+    Value & v, std::ostream & out, PathSet & context, const Pos & pos);
+
 }
diff --git a/src/libexpr/value.hh b/src/libexpr/value.hh
index a1f131f9e..3bb97b3c2 100644
--- a/src/libexpr/value.hh
+++ b/src/libexpr/value.hh
@@ -94,7 +94,8 @@ class ExternalValueBase
 
     /* Print the value as XML. Defaults to unevaluated */
     virtual void printValueAsXML(EvalState & state, bool strict, bool location,
-        XMLWriter & doc, PathSet & context, PathSet & drvsSeen) const;
+        XMLWriter & doc, PathSet & context, PathSet & drvsSeen,
+        const Pos & pos) const;
 
     virtual ~ExternalValueBase()
     {
diff --git a/src/nix-instantiate/nix-instantiate.cc b/src/nix-instantiate/nix-instantiate.cc
index 25d0fa3ba..6ff3d2f19 100644
--- a/src/nix-instantiate/nix-instantiate.cc
+++ b/src/nix-instantiate/nix-instantiate.cc
@@ -50,7 +50,7 @@ void processExpr(EvalState & state, const Strings & attrPaths,
             else
                 state.autoCallFunction(autoArgs, v, vRes);
             if (output == okXML)
-                printValueAsXML(state, strict, location, vRes, std::cout, context);
+                printValueAsXML(state, strict, location, vRes, std::cout, context, noPos);
             else if (output == okJSON)
                 printValueAsJSON(state, strict, vRes, std::cout, context);
             else {

From eae54f2d5208427080c8793d6c88db8550337d77 Mon Sep 17 00:00:00 2001
From: Kevin Amado <kamadorueda@gmail.com>
Date: Sat, 13 Nov 2021 22:28:20 -0500
Subject: [PATCH 215/567] fix many doc typos

---
 doc/manual/src/contributing/cli-guideline.md  | 24 +++++++++----------
 doc/manual/src/expressions/builtins-prefix.md |  2 +-
 .../package-management/garbage-collection.md  |  2 +-
 3 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/doc/manual/src/contributing/cli-guideline.md b/doc/manual/src/contributing/cli-guideline.md
index 258f090fb..01a1b1e73 100644
--- a/doc/manual/src/contributing/cli-guideline.md
+++ b/doc/manual/src/contributing/cli-guideline.md
@@ -103,7 +103,7 @@ impacted the most by bad user experience.
 # Help is essential
 
 Help should be built into your command line so that new users can gradually
-discover new features when they need them. 
+discover new features when they need them.
 
 ## Looking for help
 
@@ -176,7 +176,7 @@ $ nix init --template=template#pyton
 ------------------------------------------------------------------------
 Initializing Nix project at `/path/to/here`.
       Select a template for you new project:
-          |> template#pyton
+          |> template#python
              template#python-pip
              template#python-poetry
 ```
@@ -237,7 +237,7 @@ love, but if not done perfectly it will annoy users and leave bad impression.
 
 # Input
 
-Input to a command is provided via `ARGUMENTS` and `OPTIONS`. 
+Input to a command is provided via `ARGUMENTS` and `OPTIONS`.
 
 `ARGUMENTS` represent a required input for a function. When choosing to use
 `ARGUMENTS` over `OPTIONS` please be aware of the downsides that come with it:
@@ -302,7 +302,7 @@ $ nix build --option substitutors https://cache.example.org
 ------------------------------------------------------------------------
   Warning! A security related question needs to be answered.
 ------------------------------------------------------------------------
-  The following substitutors will be used to in `my-project`: 
+  The following substitutors will be used to in `my-project`:
     - https://cache.example.org
 
   Do you allow `my-project` to use above mentioned substitutors?
@@ -342,7 +342,7 @@ also allowing them to redirect content to a file. For example:
 ```shell
 $ nix build > build.txt
 ------------------------------------------------------------------------
-  Error! Atrribute `bin` missing at (1:94) from string.
+  Error! Attribute `bin` missing at (1:94) from string.
 ------------------------------------------------------------------------
 
   1| with import <nixpkgs> { }; (pkgs.runCommandCC or pkgs.runCommand) "shell" { buildInputs = [ (surge.bin) ]; } ""
@@ -408,7 +408,7 @@ Above command clearly states that command successfully completed. And in case
 of `nix build`, which is a command that might take some time to complete, it is
 equally important to also show that a command started.
 
-## Text alignment 
+## Text alignment
 
 Text alignment is the number one design element that will present all of the
 Nix commands as a family and not as separate tools glued together.
@@ -419,7 +419,7 @@ The format we should follow is:
 $ nix COMMAND
    VERB_1 NOUN and other words
   VERB__1 NOUN and other words
-       |> Some details 
+       |> Some details
 ```
 
 Few rules that we can extract from above example:
@@ -444,13 +444,13 @@ is not even notable, therefore relying on it wouldn’t make much sense.
 
 **The bright text is much better supported** across terminals and color
 schemes. Most of the time the difference is perceived as if the bright text
-would be bold. 
+would be bold.
 
 ## Colors
 
 Humans are already conditioned by society to attach certain meaning to certain
 colors. While the meaning is not universal, a simple collection of colors is
-used to represent basic emotions. 
+used to represent basic emotions.
 
 Colors that can be used in output
 
@@ -555,7 +555,7 @@ $ nix build --option substitutors https://cache.example.org
 ------------------------------------------------------------------------
   Warning! A security related question needs to be answered.
 ------------------------------------------------------------------------
-  The following substitutors will be used to in `my-project`: 
+  The following substitutors will be used to in `my-project`:
     - https://cache.example.org
 
   Do you allow `my-project` to use above mentioned substitutors?
@@ -566,7 +566,7 @@ $ nix build --option substitutors https://cache.example.org
 
 There are many ways that you can control verbosity.
 
-Verbosity levels are: 
+Verbosity levels are:
 
 - `ERROR` (level 0)
 - `WARN` (level 1)
@@ -586,4 +586,4 @@ There are also two shortcuts, `--debug` to run in `DEBUG` verbosity level and
 
 # Appendix 1: Commands naming exceptions
 
-`nix init` and `nix repl` are well established 
+`nix init` and `nix repl` are well established
diff --git a/doc/manual/src/expressions/builtins-prefix.md b/doc/manual/src/expressions/builtins-prefix.md
index 87127de2a..c631a8453 100644
--- a/doc/manual/src/expressions/builtins-prefix.md
+++ b/doc/manual/src/expressions/builtins-prefix.md
@@ -12,5 +12,5 @@ For instance, `derivation` is also available as `builtins.derivation`.
 <dl>
   <dt><code>derivation <var>attrs</var></code>;
       <code>builtins.derivation <var>attrs</var></code></dt>
-  <dd><p><var>derivation</var> in described in
+  <dd><p><var>derivation</var> is described in
          <a href="derivations.md">its own section</a>.</p></dd>
diff --git a/doc/manual/src/package-management/garbage-collection.md b/doc/manual/src/package-management/garbage-collection.md
index fecb30fd6..29a3b3101 100644
--- a/doc/manual/src/package-management/garbage-collection.md
+++ b/doc/manual/src/package-management/garbage-collection.md
@@ -44,7 +44,7 @@ collector as follows:
 $ nix-store --gc
 ```
 
-The behaviour of the gargage collector is affected by the
+The behaviour of the garbage collector is affected by the
 `keep-derivations` (default: true) and `keep-outputs` (default: false)
 options in the Nix configuration file. The defaults will ensure that all
 derivations that are build-time dependencies of garbage collector roots

From 79d07d0980e7b19e613ebbfac420fe2aaaed6469 Mon Sep 17 00:00:00 2001
From: Finn Behrens <me@kloenk.dev>
Date: Sun, 14 Nov 2021 12:23:46 +0100
Subject: [PATCH 216/567] libfetchers: set free gitlab headers

---
 src/libfetchers/github.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libfetchers/github.cc b/src/libfetchers/github.cc
index ffc44e9e2..1c539b80e 100644
--- a/src/libfetchers/github.cc
+++ b/src/libfetchers/github.cc
@@ -300,7 +300,7 @@ struct GitLabInputScheme : GitArchiveInputScheme
         if ("PAT" == token.substr(0, fldsplit))
             return std::make_pair("Private-token", token.substr(fldsplit+1));
         warn("Unrecognized GitLab token type %s",  token.substr(0, fldsplit));
-        return std::nullopt;
+        return std::make_pair(token.substr(0,fldsplit), token.substr(fldsplit+1));
     }
 
     Hash getRevFromRef(nix::ref<Store> store, const Input & input) const override

From 1d0bc96c96aff1b327c46c6aa6a2ff9133a70a62 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Domen=20Ko=C5=BEar?= <domen@dev.si>
Date: Fri, 15 Oct 2021 18:41:50 +0000
Subject: [PATCH 217/567] Add backport action

---
 .github/workflows/backport.yml | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 .github/workflows/backport.yml

diff --git a/.github/workflows/backport.yml b/.github/workflows/backport.yml
new file mode 100644
index 000000000..af12190e2
--- /dev/null
+++ b/.github/workflows/backport.yml
@@ -0,0 +1,26 @@
+name: Backport
+on:
+  pull_request_target:
+    types: [closed, labeled]
+jobs:
+  backport:
+    name: Backport Pull Request
+    if: github.repository_owner == 'NixOS' && github.event.pull_request.merged == true && (github.event_name != 'labeled' || startsWith('backport', github.event.label.name))
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+          # required to find all branches
+          fetch-depth: 0
+      - name: Create backport PRs
+        # should be kept in sync with `version`
+        uses: zeebe-io/backport-action@v0.0.5
+        with:
+          # Config README: https://github.com/zeebe-io/backport-action#backport-action
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          github_workspace: ${{ github.workspace }}
+          pull_description: |-
+            Bot-based backport to `${target_branch}`, triggered by a label in #${pull_number}.
+          # should be kept in sync with `uses`
+          version: v0.0.5

From 671817a858875045b5f99a15ac92addaf9b207f5 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 15 Nov 2021 18:44:27 +0100
Subject: [PATCH 218/567] Simplify lockFlake() a bit

---
 src/libexpr/flake/flake.cc | 27 +++++++++++----------------
 1 file changed, 11 insertions(+), 16 deletions(-)

diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 1dc6f5694..f5be67d67 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -446,24 +446,18 @@ LockedFlake lockFlake(
                            update it. */
                         auto lb = lockFlags.inputUpdates.lower_bound(inputPath);
 
-                        auto hasChildUpdate =
+                        auto mustRefetch =
                             lb != lockFlags.inputUpdates.end()
                             && lb->size() > inputPath.size()
                             && std::equal(inputPath.begin(), inputPath.end(), lb->begin());
 
-                        if (hasChildUpdate) {
-                            auto inputFlake = getFlake(
-                                state, oldLock->lockedRef, false, flakeCache);
-                            computeLocks(inputFlake.inputs, childNode, inputPath, oldLock, parent, parentPath);
-                        } else {
+                        FlakeInputs fakeInputs;
+
+                        if (!mustRefetch) {
                             /* No need to fetch this flake, we can be
                                lazy. However there may be new overrides on the
                                inputs of this flake, so we need to check
                                those. */
-                            FlakeInputs fakeInputs;
-
-                            bool refetch = false;
-
                             for (auto & i : oldLock->inputs) {
                                 if (auto lockedNode = std::get_if<0>(&i.second)) {
                                     fakeInputs.emplace(i.first, FlakeInput {
@@ -475,7 +469,7 @@ LockedFlake lockFlake(
                                     // If the override disappeared, we have to refetch the flake,
                                     // since some of the inputs may not be present in the lockfile.
                                     if (o == input.overrides.end()) {
-                                        refetch = true;
+                                        mustRefetch = true;
                                         // There's no point populating the rest of the fake inputs,
                                         // since we'll refetch the flake anyways.
                                         break;
@@ -485,13 +479,14 @@ LockedFlake lockFlake(
                                     });
                                 }
                             }
-
-                            if (refetch)
-                                fakeInputs = getFlake(state, oldLock->lockedRef, false, flakeCache).inputs;
-
-                            computeLocks(fakeInputs, childNode, inputPath, oldLock, parent, parentPath);
                         }
 
+                        computeLocks(
+                            mustRefetch
+                            ? getFlake(state, oldLock->lockedRef, false, flakeCache).inputs
+                            : fakeInputs,
+                            childNode, inputPath, oldLock, parent, parentPath);
+
                     } else {
                         /* We need to create a new lock file entry. So fetch
                            this input. */

From 4ba355e593e220e5ef6d9d6dfc78990868a724e2 Mon Sep 17 00:00:00 2001
From: "dependabot[bot]" <49699333+dependabot[bot]@users.noreply.github.com>
Date: Mon, 15 Nov 2021 22:01:13 +0000
Subject: [PATCH 219/567] Bump cachix/install-nix-action from 14.1 to 15

Bumps [cachix/install-nix-action](https://github.com/cachix/install-nix-action) from 14.1 to 15.
- [Release notes](https://github.com/cachix/install-nix-action/releases)
- [Commits](https://github.com/cachix/install-nix-action/compare/v14.1...v15)

---
updated-dependencies:
- dependency-name: cachix/install-nix-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
---
 .github/workflows/test.yml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 492ee5388..be4fcd8d1 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -17,7 +17,7 @@ jobs:
     - uses: actions/checkout@v2.4.0
       with:
         fetch-depth: 0
-    - uses: cachix/install-nix-action@v14.1
+    - uses: cachix/install-nix-action@v15
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
     - uses: cachix/cachix-action@v10
       if: needs.check_cachix.outputs.secret == 'true'
@@ -50,7 +50,7 @@ jobs:
       with:
         fetch-depth: 0
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
-    - uses: cachix/install-nix-action@v14.1
+    - uses: cachix/install-nix-action@v15
     - uses: cachix/cachix-action@v10
       with:
         name: '${{ env.CACHIX_NAME }}'
@@ -69,7 +69,7 @@ jobs:
     steps:
     - uses: actions/checkout@v2.4.0
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
-    - uses: cachix/install-nix-action@v14.1
+    - uses: cachix/install-nix-action@v15
       with:
         install_url: '${{needs.installer.outputs.installerURL}}'
         install_options: "--tarball-url-prefix https://${{ env.CACHIX_NAME }}.cachix.org/serve"

From 3771f931bfc5902047755ef810bed299df91400d Mon Sep 17 00:00:00 2001
From: "dependabot[bot]" <49699333+dependabot[bot]@users.noreply.github.com>
Date: Mon, 15 Nov 2021 22:01:17 +0000
Subject: [PATCH 220/567] Bump zeebe-io/backport-action from 0.0.5 to 0.0.7

Bumps [zeebe-io/backport-action](https://github.com/zeebe-io/backport-action) from 0.0.5 to 0.0.7.
- [Release notes](https://github.com/zeebe-io/backport-action/releases)
- [Commits](https://github.com/zeebe-io/backport-action/compare/v0.0.5...v0.0.7)

---
updated-dependencies:
- dependency-name: zeebe-io/backport-action
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
---
 .github/workflows/backport.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/backport.yml b/.github/workflows/backport.yml
index af12190e2..ec7ab4516 100644
--- a/.github/workflows/backport.yml
+++ b/.github/workflows/backport.yml
@@ -15,7 +15,7 @@ jobs:
           fetch-depth: 0
       - name: Create backport PRs
         # should be kept in sync with `version`
-        uses: zeebe-io/backport-action@v0.0.5
+        uses: zeebe-io/backport-action@v0.0.7
         with:
           # Config README: https://github.com/zeebe-io/backport-action#backport-action
           github_token: ${{ secrets.GITHUB_TOKEN }}

From 8c93a481af2ce8fbcdb9e2bbcc9559d52703112f Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 16 Nov 2021 14:23:05 +0100
Subject: [PATCH 221/567] Ignore errors unsharing/restoring the mount namespace

This prevents Nix from barfing when run in a container where it
doesn't have the appropriate privileges.
---
 src/libutil/util.cc | 14 ++++++++++----
 src/nix/main.cc     |  8 +++++---
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index a6552ebca..8ae3445c6 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1631,6 +1631,7 @@ void setStackSize(size_t stackSize)
     }
     #endif
 }
+
 static AutoCloseFD fdSavedMountNamespace;
 
 void saveMountNamespace()
@@ -1638,9 +1639,10 @@ void saveMountNamespace()
 #if __linux__
     static std::once_flag done;
     std::call_once(done, []() {
-        fdSavedMountNamespace = open("/proc/self/ns/mnt", O_RDONLY);
-        if (!fdSavedMountNamespace)
+        AutoCloseFD fd = open("/proc/self/ns/mnt", O_RDONLY);
+        if (!fd)
             throw SysError("saving parent mount namespace");
+        fdSavedMountNamespace = std::move(fd);
     });
 #endif
 }
@@ -1648,8 +1650,12 @@ void saveMountNamespace()
 void restoreMountNamespace()
 {
 #if __linux__
-    if (fdSavedMountNamespace && setns(fdSavedMountNamespace.get(), CLONE_NEWNS) == -1)
-        throw SysError("restoring parent mount namespace");
+    try {
+        if (fdSavedMountNamespace && setns(fdSavedMountNamespace.get(), CLONE_NEWNS) == -1)
+            throw SysError("restoring parent mount namespace");
+    } catch (Error & e) {
+        debug(e.msg());
+    }
 #endif
 }
 
diff --git a/src/nix/main.cc b/src/nix/main.cc
index 01889a71f..60b0aa410 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -257,9 +257,11 @@ void mainWrapped(int argc, char * * argv)
 
     #if __linux__
     if (getuid() == 0) {
-        saveMountNamespace();
-        if (unshare(CLONE_NEWNS) == -1)
-            throw SysError("setting up a private mount namespace");
+        try {
+            saveMountNamespace();
+            if (unshare(CLONE_NEWNS) == -1)
+                throw SysError("setting up a private mount namespace");
+        } catch (Error & e) { }
     }
     #endif
 

From 8368a8aff1b70e98a4997d803e34bfdc2acf10f4 Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Tue, 16 Nov 2021 10:32:26 -0500
Subject: [PATCH 222/567] Make docker.nix match Nixpkgs's idioms

1. `target` is the wrong name, that is just for compilers per out
standard terminology. We just need to worry about "build" and "host".

2. We only need one `pkgs`. `pkgs.buildPackages` is how we get anything
we need at build time.

3. `crossSystem` is the name of a nixpkgs parameter that is actually an
attribute set, not a 2-part "cpu-os" string.

3. `pkgsCross` effectively evaluates Nixpkgs twice, which is
inefficient. It is just there for people poking around the CLI / REPL
(and I am skeptical even that is a good idea), and *not* what written
code should use, especially code that is merely parametric in the package set
it is given.

4. We don't need to memoize Nixpkgs here because we are only doing one
pkg set at a time (no `genAttrs`) so it's better to just delete all this
stuff. `flake.nix` instead would do something like that, with
`genAttrs` (though without `pkgsCross`), if and when we have hydra jobs
for cross builds.
---
 docker.nix | 31 +++++++++----------------------
 1 file changed, 9 insertions(+), 22 deletions(-)

diff --git a/docker.nix b/docker.nix
index 316d57a36..2a13c23fb 100644
--- a/docker.nix
+++ b/docker.nix
@@ -2,24 +2,11 @@
 , lib ? pkgs.lib
 , name ? "nix"
 , tag ? "latest"
-, crossSystem ? null
 , channelName ? "nixpkgs"
 , channelURL ? "https://nixos.org/channels/nixpkgs-unstable"
 }:
 let
-  buildPkgs = pkgs;
-  targetPkgs =
-    if crossSystem != null && crossSystem != pkgs.system
-    then {
-      aarch64-linux = pkgs.pkgsCross.aarch64-multiplatform;
-      armv7l-linux = pkgs.pkgsCross.armv7l-hf-multiplatform.system;
-      x86_64-linux = pkgs.pkgsCross.gnu64;
-      powerpc64le-linux = pkgs.pkgsCross.musl-power;
-      i686-linux = pkgs.pkgsCross.gnu32;
-    }.${crossSystem}
-    else pkgs;
-
-  defaultPkgs = with targetPkgs; [
+  defaultPkgs = with pkgs; [
     nix
     bashInteractive
     coreutils-full
@@ -140,17 +127,17 @@ let
 
   baseSystem =
     let
-      nixpkgs = targetPkgs.path;
-      channel = targetPkgs.runCommand "channel-nixos" { } ''
+      nixpkgs = pkgs.path;
+      channel = pkgs.runCommand "channel-nixos" { } ''
         mkdir $out
         ln -s ${nixpkgs} $out/nixpkgs
         echo "[]" > $out/manifest.nix
       '';
-      rootEnv = pkgs.buildEnv {
+      rootEnv = pkgs.buildPackages.buildEnv {
         name = "root-profile-env";
         paths = defaultPkgs;
       };
-      profile = targetPkgs.runCommand "user-environment" { } ''
+      profile = pkgs.buildPackages.runCommand "user-environment" { } ''
         mkdir $out
         cp -a ${rootEnv}/* $out/
 
@@ -175,7 +162,7 @@ let
         EOF
       '';
     in
-    targetPkgs.runCommand "base-system"
+    pkgs.runCommand "base-system"
       {
         inherit passwdContents groupContents shadowContents nixConfContents;
         passAsFile = [
@@ -225,12 +212,12 @@ let
       echo "${channelURL} ${channelName}" > $out/root/.nix-channels
 
       mkdir -p $out/bin $out/usr/bin
-      ln -s ${targetPkgs.coreutils}/bin/env $out/usr/bin/env
-      ln -s ${targetPkgs.bashInteractive}/bin/bash $out/bin/sh
+      ln -s ${pkgs.coreutils}/bin/env $out/usr/bin/env
+      ln -s ${pkgs.bashInteractive}/bin/bash $out/bin/sh
     '';
 
 in
-targetPkgs.dockerTools.buildLayeredImageWithNixDb {
+pkgs.dockerTools.buildLayeredImageWithNixDb {
 
   inherit name tag;
 

From e41cf8511f68e7e67786d8735d03c961c34cb2ad Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 16 Nov 2021 17:44:19 +0100
Subject: [PATCH 223/567] Don't hang when calling an attrset

Fixes #5565.
---
 src/libexpr/eval.cc | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 402de78ad..615f020e4 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -1275,6 +1275,8 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
         }
     };
 
+    Attr * functor;
+
     while (nrArgs > 0) {
 
         if (vCur.isLambda()) {
@@ -1403,16 +1405,14 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
             }
         }
 
-        else if (vCur.type() == nAttrs) {
-            if (auto functor = vCur.attrs->get(sFunctor)) {
-                /* 'vCur" may be allocated on the stack of the calling
-                   function, but for functors we may keep a reference,
-                   so heap-allocate a copy and use that instead. */
-                Value * args2[] = {allocValue()};
-                *args2[0] = vCur;
-                /* !!! Should we use the attr pos here? */
-                callFunction(*functor->value, 1, args2, vCur, pos);
-            }
+        else if (vCur.type() == nAttrs && (functor = vCur.attrs->get(sFunctor))) {
+            /* 'vCur" may be allocated on the stack of the calling
+               function, but for functors we may keep a reference, so
+               heap-allocate a copy and use that instead. */
+            Value * args2[] = {allocValue()};
+            *args2[0] = vCur;
+            /* !!! Should we use the attr pos here? */
+            callFunction(*functor->value, 1, args2, vCur, pos);
         }
 
         else

From d7bae52b9d418e208593c6641bce54f6a82458f4 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 16 Nov 2021 22:34:17 +0100
Subject: [PATCH 224/567] Call functors with both arguments at once

This is not really useful on its own, but it does recover the
'infinite recursion' error message for '{ __functor = x: x; } 1', and
is more efficient in conjunction with #3718.

Fixes #5515.
---
 src/libexpr/eval.cc | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 615f020e4..f1ff3a6e0 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -1406,13 +1406,15 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
         }
 
         else if (vCur.type() == nAttrs && (functor = vCur.attrs->get(sFunctor))) {
-            /* 'vCur" may be allocated on the stack of the calling
+            /* 'vCur' may be allocated on the stack of the calling
                function, but for functors we may keep a reference, so
                heap-allocate a copy and use that instead. */
-            Value * args2[] = {allocValue()};
+            Value * args2[] = {allocValue(), args[0]};
             *args2[0] = vCur;
             /* !!! Should we use the attr pos here? */
-            callFunction(*functor->value, 1, args2, vCur, pos);
+            callFunction(*functor->value, 2, args2, vCur, pos);
+            nrArgs--;
+            args++;
         }
 
         else

From 6d46b5b609f8f85968e1ca7aaf7c57dd52d0521c Mon Sep 17 00:00:00 2001
From: Kalle Jepsen <git@ksonj.net>
Date: Wed, 17 Nov 2021 08:41:26 +0100
Subject: [PATCH 225/567] Fix detection of scp-style URIs to support
 non-standard SSH ports for git

---
 src/libexpr/primops/fetchTree.cc | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index e6becdafc..b307ac04a 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -74,8 +74,11 @@ std::string fixURI(std::string uri, EvalState & state, const std::string & defau
 
 std::string fixURIForGit(std::string uri, EvalState & state)
 {
+    /* Detects scp-style uris (e.g. git@github.com:NixOS/nix) and fixes
+     * them by removing the `:` and assuming a scheme of `ssh://`
+     * */
     static std::regex scp_uri("([^/].*)@(.*):(.*)");
-    if (uri[0] != '/' && std::regex_match(uri, scp_uri))
+    if (uri[0] != '/' && std::regex_match(uri, scp_uri) && uri.find("://") == std::string::npos)
         return fixURI(std::regex_replace(uri, scp_uri, "$1@$2/$3"), state, "ssh");
     else
         return fixURI(uri, state);

From d03e89e5d19a7082cc1e8e5ff10d7f62a0a6e937 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 3 Mar 2020 15:32:20 +0100
Subject: [PATCH 226/567] Parse '(f x) y' the same as 'f x y'

(cherry picked from commit 5253cb4b68ad248f37b27849c0ebf3614e4f2777)
---
 src/libexpr/parser.y | 24 +++++++-----------------
 1 file changed, 7 insertions(+), 17 deletions(-)

diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 923997bf6..c1f4e72e0 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -39,12 +39,6 @@ namespace nix {
             { };
     };
 
-    // Helper to prevent an expensive dynamic_cast call in expr_app.
-    struct App
-    {
-        Expr * e;
-        bool isCall;
-    };
 }
 
 #define YY_DECL int yylex \
@@ -284,12 +278,10 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * err
   char * uri;
   std::vector<nix::AttrName> * attrNames;
   std::vector<nix::Expr *> * string_parts;
-  nix::App app; // bool == whether this is an ExprCall
 }
 
 %type <e> start expr expr_function expr_if expr_op
-%type <e> expr_select expr_simple
-%type <app> expr_app
+%type <e> expr_select expr_simple expr_app
 %type <list> expr_list
 %type <attrs> binds
 %type <formals> formals
@@ -377,20 +369,18 @@ expr_op
   | expr_op '*' expr_op { $$ = new ExprCall(CUR_POS, new ExprVar(data->symbols.create("__mul")), {$1, $3}); }
   | expr_op '/' expr_op { $$ = new ExprCall(CUR_POS, new ExprVar(data->symbols.create("__div")), {$1, $3}); }
   | expr_op CONCAT expr_op { $$ = new ExprOpConcatLists(CUR_POS, $1, $3); }
-  | expr_app { $$ = $1.e; }
+  | expr_app
   ;
 
 expr_app
   : expr_app expr_select {
-      if ($1.isCall) {
-          ((ExprCall *) $1.e)->args.push_back($2);
+      if (auto e2 = dynamic_cast<ExprCall *>($1)) {
+          e2->args.push_back($2);
           $$ = $1;
-      } else {
-          $$.e = new ExprCall(CUR_POS, $1.e, {$2});
-          $$.isCall = true;
-      }
+      } else
+          $$ = new ExprCall(CUR_POS, $1, {$2});
   }
-  | expr_select { $$.e = $1; $$.isCall = false; }
+  | expr_select
   ;
 
 expr_select

From 46d2a5a10be7e48679a29d487adbb6f1d6fd452a Mon Sep 17 00:00:00 2001
From: Kalle Jepsen <git@ksonj.net>
Date: Wed, 17 Nov 2021 13:49:10 +0100
Subject: [PATCH 227/567] Simplify fix by disallowing / in front of @ to match
 scp style

---
 src/libexpr/primops/fetchTree.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index b307ac04a..079513873 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -77,8 +77,8 @@ std::string fixURIForGit(std::string uri, EvalState & state)
     /* Detects scp-style uris (e.g. git@github.com:NixOS/nix) and fixes
      * them by removing the `:` and assuming a scheme of `ssh://`
      * */
-    static std::regex scp_uri("([^/].*)@(.*):(.*)");
-    if (uri[0] != '/' && std::regex_match(uri, scp_uri) && uri.find("://") == std::string::npos)
+    static std::regex scp_uri("([^/]*)@(.*):(.*)");
+    if (uri[0] != '/' && std::regex_match(uri, scp_uri))
         return fixURI(std::regex_replace(uri, scp_uri, "$1@$2/$3"), state, "ssh");
     else
         return fixURI(uri, state);

From e96faadcd6d0adc223deca746a64f5ae46b517f0 Mon Sep 17 00:00:00 2001
From: Jan Tojnar <jtojnar@gmail.com>
Date: Wed, 17 Nov 2021 14:28:43 +0100
Subject: [PATCH 228/567] Fix XDG_CONFIG_DIRS fallback

According to XDG Base Directory Specification,
it should fall back to /etc/xdg when the env var is not present.
---
 doc/manual/src/command-ref/conf-file-prefix.md | 5 +++--
 src/libutil/util.cc                            | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/doc/manual/src/command-ref/conf-file-prefix.md b/doc/manual/src/command-ref/conf-file-prefix.md
index d660db502..44b7ba86d 100644
--- a/doc/manual/src/command-ref/conf-file-prefix.md
+++ b/doc/manual/src/command-ref/conf-file-prefix.md
@@ -16,8 +16,9 @@ By default Nix reads settings from the following places:
     will be loaded in reverse order.
 
     Otherwise it will look for `nix/nix.conf` files in `XDG_CONFIG_DIRS`
-    and `XDG_CONFIG_HOME`. If these are unset, it will look in
-    `$HOME/.config/nix/nix.conf`.
+    and `XDG_CONFIG_HOME`. If unset, `XDG_CONFIG_DIRS` defaults to
+    `/etc/xdg`, and `XDG_CONFIG_HOME` defaults to `$HOME/.config`
+    as per [XDG Base Directory Specification](https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html).
 
   - If `NIX_CONFIG` is set, its contents is treated as the contents of
     a configuration file.
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 8ae3445c6..5468d1ed1 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -562,7 +562,7 @@ Path getConfigDir()
 std::vector<Path> getConfigDirs()
 {
     Path configHome = getConfigDir();
-    string configDirs = getEnv("XDG_CONFIG_DIRS").value_or("");
+    string configDirs = getEnv("XDG_CONFIG_DIRS").value_or("/etc/xdg");
     std::vector<Path> result = tokenizeString<std::vector<string>>(configDirs, ":");
     result.insert(result.begin(), configHome);
     return result;

From ca4d8ce9e22ef04687b1516c9472a5d3f82e056b Mon Sep 17 00:00:00 2001
From: Jan Tojnar <jtojnar@gmail.com>
Date: Wed, 17 Nov 2021 16:30:39 +0100
Subject: [PATCH 229/567] doc: De-emphasize nix-env without -A

The manual uses `nix-env -i` without `-A` prominently, teaching a bad practice to newcomers.
---
 doc/manual/src/command-ref/nix-env.md         | 42 ++++++++-----
 doc/manual/src/command-ref/opt-common.md      |  4 +-
 .../expressions/simple-building-testing.md    |  2 +-
 doc/manual/src/introduction.md                |  4 +-
 .../package-management/basic-package-mgmt.md  | 63 ++++++++++---------
 .../binary-cache-substituter.md               |  4 +-
 doc/manual/src/package-management/profiles.md |  6 +-
 .../src/package-management/ssh-substituter.md |  2 +-
 doc/manual/src/quick-start.md                 | 14 ++---
 9 files changed, 80 insertions(+), 61 deletions(-)

diff --git a/doc/manual/src/command-ref/nix-env.md b/doc/manual/src/command-ref/nix-env.md
index 5217510d7..8d6abaf52 100644
--- a/doc/manual/src/command-ref/nix-env.md
+++ b/doc/manual/src/command-ref/nix-env.md
@@ -238,7 +238,16 @@ a number of possible ways:
 
 ## Examples
 
-To install a specific version of `gcc` from the active Nix expression:
+To install a package using a specific attribute path from the active Nix expression:
+
+```console
+$ nix-env -iA gcc40mips
+installing `gcc-4.0.2'
+$ nix-env -iA xorg.xorgserver
+installing `xorg-server-1.2.0'
+```
+
+To install a specific version of `gcc` using the derivation name:
 
 ```console
 $ nix-env --install gcc-3.3.2
@@ -246,6 +255,9 @@ installing `gcc-3.3.2'
 uninstalling `gcc-3.1'
 ```
 
+Using attribute path for selecting a package is preferred,
+as it is much faster and there will not be multiple matches.
+
 Note the previously installed version is removed, since
 `--preserve-installed` was not specified.
 
@@ -256,13 +268,6 @@ $ nix-env --install gcc
 installing `gcc-3.3.2'
 ```
 
-To install using a specific attribute:
-
-```console
-$ nix-env -i -A gcc40mips
-$ nix-env -i -A xorg.xorgserver
-```
-
 To install all derivations in the Nix expression `foo.nix`:
 
 ```console
@@ -374,22 +379,29 @@ For the other flags, see `--install`.
 ## Examples
 
 ```console
-$ nix-env --upgrade gcc
+$ nix-env --upgrade -A nixpkgs.gcc
 upgrading `gcc-3.3.1' to `gcc-3.4'
 ```
 
+When there are no updates available, nothing will happen:
+
 ```console
-$ nix-env -u gcc-3.3.2 --always (switch to a specific version)
+$ nix-env --upgrade -A nixpkgs.pan
+```
+
+Using `-A` is preferred when possible, as it is faster and unambiguous but
+it is also possible to upgrade to a specific version by matching the derivation name:
+
+```console
+$ nix-env -u gcc-3.3.2 --always
 upgrading `gcc-3.4' to `gcc-3.3.2'
 ```
 
-```console
-$ nix-env --upgrade pan
-(no upgrades available, so nothing happens)
-```
+To try to upgrade everything
+(matching packages based on the part of the derivation name without version):
 
 ```console
-$ nix-env -u (try to upgrade everything)
+$ nix-env -u
 upgrading `hello-2.1.2' to `hello-2.1.3'
 upgrading `mozilla-1.2' to `mozilla-1.4'
 ```
diff --git a/doc/manual/src/command-ref/opt-common.md b/doc/manual/src/command-ref/opt-common.md
index 47862bc09..7ee1a26bc 100644
--- a/doc/manual/src/command-ref/opt-common.md
+++ b/doc/manual/src/command-ref/opt-common.md
@@ -162,11 +162,11 @@ Most Nix commands accept the following command-line options:
     }: ...
     ```
 
-    So if you call this Nix expression (e.g., when you do `nix-env -i
+    So if you call this Nix expression (e.g., when you do `nix-env -iA
     pkgname`), the function will be called automatically using the
     value [`builtins.currentSystem`](../expressions/builtins.md) for
     the `system` argument. You can override this using `--arg`, e.g.,
-    `nix-env -i pkgname --arg system \"i686-freebsd\"`. (Note that
+    `nix-env -iA pkgname --arg system \"i686-freebsd\"`. (Note that
     since the argument is a Nix string literal, you have to escape the
     quotes.)
 
diff --git a/doc/manual/src/expressions/simple-building-testing.md b/doc/manual/src/expressions/simple-building-testing.md
index 6f730a936..7f0d8f841 100644
--- a/doc/manual/src/expressions/simple-building-testing.md
+++ b/doc/manual/src/expressions/simple-building-testing.md
@@ -1,6 +1,6 @@
 # Building and Testing
 
-You can now try to build Hello. Of course, you could do `nix-env -i
+You can now try to build Hello. Of course, you could do `nix-env -f . -iA
 hello`, but you may not want to install a possibly broken package just
 yet. The best way to test the package is by using the command
 `nix-build`, which builds a Nix expression and creates a symlink named
diff --git a/doc/manual/src/introduction.md b/doc/manual/src/introduction.md
index 93ec502c1..d87487a07 100644
--- a/doc/manual/src/introduction.md
+++ b/doc/manual/src/introduction.md
@@ -76,7 +76,7 @@ there after an upgrade.  This means that you can _roll back_ to the
 old version:
 
 ```console
-$ nix-env --upgrade some-packages
+$ nix-env --upgrade -A nixpkgs.some-package
 $ nix-env --rollback
 ```
 
@@ -122,7 +122,7 @@ Nix expressions generally describe how to build a package from
 source, so an installation action like
 
 ```console
-$ nix-env --install firefox
+$ nix-env --install -A nixpkgs.firefox
 ```
 
 _could_ cause quite a bit of build activity, as not only Firefox but
diff --git a/doc/manual/src/package-management/basic-package-mgmt.md b/doc/manual/src/package-management/basic-package-mgmt.md
index 9702a29eb..50c6d3c2d 100644
--- a/doc/manual/src/package-management/basic-package-mgmt.md
+++ b/doc/manual/src/package-management/basic-package-mgmt.md
@@ -24,7 +24,7 @@ collection; you could write your own Nix expressions based on Nixpkgs,
 or completely new ones.)
 
 You can manually download the latest version of Nixpkgs from
-<http://nixos.org/nixpkgs/download.html>. However, it’s much more
+<https://github.com/NixOS/nixpkgs>. However, it’s much more
 convenient to use the Nixpkgs [*channel*](channels.md), since it makes
 it easy to stay up to date with new versions of Nixpkgs. Nixpkgs is
 automatically added to your list of “subscribed” channels when you
@@ -47,41 +47,45 @@ $ nix-channel --update
 You can view the set of available packages in Nixpkgs:
 
 ```console
-$ nix-env -qa
-aterm-2.2
-bash-3.0
-binutils-2.15
-bison-1.875d
-blackdown-1.4.2
-bzip2-1.0.2
+$ nix-env -qaP
+nixpkgs.aterm                       aterm-2.2
+nixpkgs.bash                        bash-3.0
+nixpkgs.binutils                    binutils-2.15
+nixpkgs.bison                       bison-1.875d
+nixpkgs.blackdown                   blackdown-1.4.2
+nixpkgs.bzip2                       bzip2-1.0.2
 …
 ```
 
-The flag `-q` specifies a query operation, and `-a` means that you want
+The flag `-q` specifies a query operation, `-a` means that you want
 to show the “available” (i.e., installable) packages, as opposed to the
-installed packages. If you downloaded Nixpkgs yourself, or if you
-checked it out from GitHub, then you need to pass the path to your
-Nixpkgs tree using the `-f` flag:
+installed packages, and `-P` prints the attribute paths that can be used
+to unambiguously select a package for installation (listed in the first column).
+If you downloaded Nixpkgs yourself, or if you checked it out from GitHub,
+then you need to pass the path to your Nixpkgs tree using the `-f` flag:
 
 ```console
-$ nix-env -qaf /path/to/nixpkgs
+$ nix-env -qaPf /path/to/nixpkgs
+aterm                               aterm-2.2
+bash                                bash-3.0
+…
 ```
 
 where */path/to/nixpkgs* is where you’ve unpacked or checked out
 Nixpkgs.
 
-You can select specific packages by name:
+You can filter the packages by name:
 
 ```console
-$ nix-env -qa firefox
-firefox-34.0.5
-firefox-with-plugins-34.0.5
+$ nix-env -qaP firefox
+nixpkgs.firefox-esr                 firefox-91.3.0esr
+nixpkgs.firefox                     firefox-94.0.1
 ```
 
 and using regular expressions:
 
 ```console
-$ nix-env -qa 'firefox.*'
+$ nix-env -qaP 'firefox.*'
 ```
 
 It is also possible to see the *status* of available packages, i.e.,
@@ -89,11 +93,11 @@ whether they are installed into the user environment and/or present in
 the system:
 
 ```console
-$ nix-env -qas
+$ nix-env -qaPs
 …
--PS bash-3.0
---S binutils-2.15
-IPS bison-1.875d
+-PS  nixpkgs.bash                bash-3.0
+--S  nixpkgs.binutils            binutils-2.15
+IPS  nixpkgs.bison               bison-1.875d
 …
 ```
 
@@ -106,13 +110,13 @@ which is Nix’s mechanism for doing binary deployment. It just means that
 Nix knows that it can fetch a pre-built package from somewhere
 (typically a network server) instead of building it locally.
 
-You can install a package using `nix-env -i`. For instance,
+You can install a package using `nix-env -iA`. For instance,
 
 ```console
-$ nix-env -i subversion
+$ nix-env -iA nixpkgs.subversion
 ```
 
-will install the package called `subversion` (which is, of course, the
+will install the package called `subversion` from `nixpkgs` channel (which is, of course, the
 [Subversion version management system](http://subversion.tigris.org/)).
 
 > **Note**
@@ -122,7 +126,7 @@ will install the package called `subversion` (which is, of course, the
 > binary cache <https://cache.nixos.org>; it contains binaries for most
 > packages in Nixpkgs. Only if no binary is available in the binary
 > cache, Nix will build the package from source. So if `nix-env
-> -i subversion` results in Nix building stuff from source, then either
+> -iA nixpkgs.subversion` results in Nix building stuff from source, then either
 > the package is not built for your platform by the Nixpkgs build
 > servers, or your version of Nixpkgs is too old or too new. For
 > instance, if you have a very recent checkout of Nixpkgs, then the
@@ -133,7 +137,10 @@ will install the package called `subversion` (which is, of course, the
 > using a Git checkout of the Nixpkgs tree), you will get binaries for
 > most packages.
 
-Naturally, packages can also be uninstalled:
+Naturally, packages can also be uninstalled. Unlike when installing, you will
+need to use the derivation name (though the version part can be omitted),
+instead of the attribute path, as `nix-env` does not record which attribute
+was used for installing:
 
 ```console
 $ nix-env -e subversion
@@ -143,7 +150,7 @@ Upgrading to a new version is just as easy. If you have a new release of
 Nix Packages, you can do:
 
 ```console
-$ nix-env -u subversion
+$ nix-env -uA nixpkgs.subversion
 ```
 
 This will *only* upgrade Subversion if there is a “newer” version in the
diff --git a/doc/manual/src/package-management/binary-cache-substituter.md b/doc/manual/src/package-management/binary-cache-substituter.md
index bdc5038fc..ef738794b 100644
--- a/doc/manual/src/package-management/binary-cache-substituter.md
+++ b/doc/manual/src/package-management/binary-cache-substituter.md
@@ -9,7 +9,7 @@ The daemon that handles binary cache requests via HTTP, `nix-serve`, is
 not part of the Nix distribution, but you can install it from Nixpkgs:
 
 ```console
-$ nix-env -i nix-serve
+$ nix-env -iA nixpkgs.nix-serve
 ```
 
 You can then start the server, listening for HTTP connections on
@@ -35,7 +35,7 @@ On the client side, you can tell Nix to use your binary cache using
 `--option extra-binary-caches`, e.g.:
 
 ```console
-$ nix-env -i firefox --option extra-binary-caches http://avalon:8080/
+$ nix-env -iA nixpkgs.firefox --option extra-binary-caches http://avalon:8080/
 ```
 
 The option `extra-binary-caches` tells Nix to use this binary cache in
diff --git a/doc/manual/src/package-management/profiles.md b/doc/manual/src/package-management/profiles.md
index fbbfb7320..d1a2580d4 100644
--- a/doc/manual/src/package-management/profiles.md
+++ b/doc/manual/src/package-management/profiles.md
@@ -39,7 +39,7 @@ just Subversion 1.1.2 (arrows in the figure indicate symlinks). This
 would be what we would obtain if we had done
 
 ```console
-$ nix-env -i subversion
+$ nix-env -iA nixpkgs.subversion
 ```
 
 on a set of Nix expressions that contained Subversion 1.1.2.
@@ -54,7 +54,7 @@ environment is generated based on the current one. For instance,
 generation 43 was created from generation 42 when we did
 
 ```console
-$ nix-env -i subversion firefox
+$ nix-env -iA nixpkgs.subversion nixpkgs.firefox
 ```
 
 on a set of Nix expressions that contained Firefox and a new version of
@@ -127,7 +127,7 @@ All `nix-env` operations work on the profile pointed to by
 (abbreviation `-p`):
 
 ```console
-$ nix-env -p /nix/var/nix/profiles/other-profile -i subversion
+$ nix-env -p /nix/var/nix/profiles/other-profile -iA nixpkgs.subversion
 ```
 
 This will *not* change the `~/.nix-profile` symlink.
diff --git a/doc/manual/src/package-management/ssh-substituter.md b/doc/manual/src/package-management/ssh-substituter.md
index 6e5e258bc..c59933f61 100644
--- a/doc/manual/src/package-management/ssh-substituter.md
+++ b/doc/manual/src/package-management/ssh-substituter.md
@@ -6,7 +6,7 @@ automatically fetching any store paths in Firefox’s closure if they are
 available on the server `avalon`:
 
 ```console
-$ nix-env -i firefox --substituters ssh://alice@avalon
+$ nix-env -iA nixpkgs.firefox --substituters ssh://alice@avalon
 ```
 
 This works similar to the binary cache substituter that Nix usually
diff --git a/doc/manual/src/quick-start.md b/doc/manual/src/quick-start.md
index 71205923b..b54e73500 100644
--- a/doc/manual/src/quick-start.md
+++ b/doc/manual/src/quick-start.md
@@ -19,19 +19,19 @@ to subsequent chapters.
    channel:
 
    ```console
-   $ nix-env -qa
-   docbook-xml-4.3
-   docbook-xml-4.5
-   firefox-33.0.2
-   hello-2.9
-   libxslt-1.1.28
+   $ nix-env -qaP
+   nixpkgs.docbook_xml_dtd_43                    docbook-xml-4.3
+   nixpkgs.docbook_xml_dtd_45                    docbook-xml-4.5
+   nixpkgs.firefox                               firefox-33.0.2
+   nixpkgs.hello                                 hello-2.9
+   nixpkgs.libxslt                               libxslt-1.1.28
    …
    ```
 
 1. Install some packages from the channel:
 
    ```console
-   $ nix-env -i hello
+   $ nix-env -iA nixpkgs.hello
    ```
 
    This should download pre-built packages; it should not build them

From bc14465e08a286f8bc3b1e47e70372352b64bd2c Mon Sep 17 00:00:00 2001
From: Farid Zakaria <fmzakari@google.com>
Date: Thu, 18 Nov 2021 04:00:19 +0000
Subject: [PATCH 230/567] Fix stack buffer overflow

Fix a stack buffer overflow found by running MemorySanitizer.
---
 src/libstore/references.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libstore/references.cc b/src/libstore/references.cc
index c369b14ac..bb9590acb 100644
--- a/src/libstore/references.cc
+++ b/src/libstore/references.cc
@@ -54,7 +54,7 @@ void RefScanSink::operator () (std::string_view data)
        fragment, so search in the concatenation of the tail of the
        previous fragment and the start of the current fragment. */
     auto s = tail;
-    s.append(data.data(), refLength);
+    s.append(data.data(), std::min(data.size(), refLength));
     search(s, hashes, seen);
 
     search(data, hashes, seen);

From 9653858ce68a04e2c23dbf14e344d4dca4bf7e24 Mon Sep 17 00:00:00 2001
From: Alex Shabalin <alex.shabalin@tweag.io>
Date: Wed, 17 Nov 2021 16:38:03 +0100
Subject: [PATCH 231/567] Fix :e in repl

Closes https://github.com/NixOS/nix/issues/5487

Co-authored-by: Alexander Bantyev balsoft@balsoft.ru
---
 src/nix/repl.cc | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 4f13ee05d..fd86174f2 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -471,7 +471,10 @@ bool NixRepl::processLine(string line)
         auto args = editorFor(pos);
         auto editor = args.front();
         args.pop_front();
-        runProgram(editor, true, args);
+
+        // runProgram redirects stdout to a StringSink,
+        // using runProgram2 to allow editors to display their UI
+        runProgram2(RunOptions { .program = editor, .searchPath = true, .args = args });
 
         // Reload right after exiting the editor
         state->resetFileCache();

From 262a3c7ce332d8f7f52b007178c2d54f063d6c7a Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 18 Nov 2021 12:12:31 +0100
Subject: [PATCH 232/567] Simplify

---
 src/libstore/references.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libstore/references.cc b/src/libstore/references.cc
index bb9590acb..91b3fc142 100644
--- a/src/libstore/references.cc
+++ b/src/libstore/references.cc
@@ -54,12 +54,12 @@ void RefScanSink::operator () (std::string_view data)
        fragment, so search in the concatenation of the tail of the
        previous fragment and the start of the current fragment. */
     auto s = tail;
-    s.append(data.data(), std::min(data.size(), refLength));
+    auto tailLen = std::min(data.size(), refLength);
+    s.append(data.data(), tailLen);
     search(s, hashes, seen);
 
     search(data, hashes, seen);
 
-    auto tailLen = std::min(data.size(), refLength);
     auto rest = refLength - tailLen;
     if (rest < tail.size())
         tail = tail.substr(tail.size() - rest);

From 79f27500a45f9b1eda3d54114cf835f73775af8e Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 18 Nov 2021 13:32:52 +0100
Subject: [PATCH 233/567] Test that untrusted config is ignored without
 --accept-flake-config

---
 tests/flake-local-settings.sh | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tests/flake-local-settings.sh b/tests/flake-local-settings.sh
index 6ee6b17d6..09f6b4ca8 100644
--- a/tests/flake-local-settings.sh
+++ b/tests/flake-local-settings.sh
@@ -25,5 +25,10 @@ cat <<EOF > flake.nix
 }
 EOF
 
+# Without --accept-flake-config, the post hook should not run.
+nix build < /dev/null
+(! [[ -f post-hook-ran ]])
+clearStore
+
 nix build --accept-flake-config
 test -f post-hook-ran || fail "The post hook should have ran"

From e1192116d357fd8346ebeed64de25730e47b4147 Mon Sep 17 00:00:00 2001
From: Lorenz Leutgeb <lorenz@leutgeb.xyz>
Date: Thu, 18 Nov 2021 15:08:01 +0100
Subject: [PATCH 234/567] doc: Fix escape for operator "logical or"

See https://matrix.to/#/!KqkRjyTEzAGRiZFBYT:nixos.org/$hhMb6AdRIXfRkv_LsNsiQJuch7AQ_b6szr4tfawFy-4
---
 doc/manual/src/expressions/language-operators.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/doc/manual/src/expressions/language-operators.md b/doc/manual/src/expressions/language-operators.md
index b7fd6f4c6..6ab319039 100644
--- a/doc/manual/src/expressions/language-operators.md
+++ b/doc/manual/src/expressions/language-operators.md
@@ -24,5 +24,5 @@ order of precedence (from strongest to weakest binding).
 | Equality                 | *e1* `==` *e2*                      | none          | Equality.                                                                                                                                                                                                                     | 11         |
 | Inequality               | *e1* `!=` *e2*                      | none          | Inequality.                                                                                                                                                                                                                   | 11         |
 | Logical AND              | *e1* `&&` *e2*                      | left          | Logical AND.                                                                                                                                                                                                                  | 12         |
-| Logical OR               | *e1* `\|\|` *e2*                    | left          | Logical OR.                                                                                                                                                                                                                   | 13         |
-| Logical Implication      | *e1* `->` *e2*                      | none          | Logical implication (equivalent to `!e1 \|\| e2`).                                                                                                                                                                            | 14         |
+| Logical OR               | *e1* <code>&#124;&#124;</code> *e2* | left          | Logical OR.                                                                                                                                                                                                                   | 13         |
+| Logical Implication      | *e1* `->` *e2*                      | none          | Logical implication (equivalent to <code>!e1 &#124;&#124; e2</code>).                                                                                                                                                                            | 14         |

From 4b28798bfcb659bf83557a33546a03115f8bfed2 Mon Sep 17 00:00:00 2001
From: Alex Shabalin <alex.shabalin@tweag.io>
Date: Thu, 18 Nov 2021 14:32:52 +0100
Subject: [PATCH 235/567] Offer suggestions for nix-env -i

Closes https://github.com/NixOS/nix/issues/972
---
 src/libstore/names.cc  |   2 +-
 src/libstore/names.hh  |   2 +-
 src/nix-env/nix-env.cc | 174 ++++++++++++++++++++++++++---------------
 3 files changed, 113 insertions(+), 65 deletions(-)

diff --git a/src/libstore/names.cc b/src/libstore/names.cc
index ce808accc..54c95055d 100644
--- a/src/libstore/names.cc
+++ b/src/libstore/names.cc
@@ -42,7 +42,7 @@ DrvName::~DrvName()
 { }
 
 
-bool DrvName::matches(DrvName & n)
+bool DrvName::matches(const DrvName & n)
 {
     if (name != "*") {
         if (!regex) {
diff --git a/src/libstore/names.hh b/src/libstore/names.hh
index bc62aac93..3f861bc44 100644
--- a/src/libstore/names.hh
+++ b/src/libstore/names.hh
@@ -19,7 +19,7 @@ struct DrvName
     DrvName(std::string_view s);
     ~DrvName();
 
-    bool matches(DrvName & n);
+    bool matches(const DrvName & n);
 
 private:
     std::unique_ptr<Regex> regex;
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index 4056d973d..1c78b5307 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -224,6 +224,91 @@ static void checkSelectorUse(DrvNames & selectors)
 }
 
 
+namespace {
+
+std::set<std::string> searchByPrefix(const DrvInfos & allElems, std::string_view prefix) {
+    constexpr std::size_t maxResults = 3;
+    std::set<std::string> result;
+    for (const auto & drvInfo : allElems) {
+        const auto drvName = DrvName { drvInfo.queryName() };
+        if (hasPrefix(drvName.name, prefix)) {
+            result.emplace(drvName.name);
+
+            if (result.size() >= maxResults) {
+                break;
+            }
+        }
+    }
+    return result;
+}
+
+struct Match
+{
+    DrvInfo drvInfo;
+    std::size_t index;
+
+    Match(DrvInfo drvInfo_, std::size_t index_)
+    : drvInfo{std::move(drvInfo_)}
+    , index{index_}
+    {}
+};
+
+/* If a selector matches multiple derivations
+   with the same name, pick the one matching the current
+   system.  If there are still multiple derivations, pick the
+   one with the highest priority.  If there are still multiple
+   derivations, pick the one with the highest version.
+   Finally, if there are still multiple derivations,
+   arbitrarily pick the first one. */
+std::vector<Match> pickNewestOnly(EvalState & state, std::vector<Match> matches) {
+    /* Map from package names to derivations. */
+    std::map<std::string, Match> newest;
+    StringSet multiple;
+
+    for (auto & match : matches) {
+        auto & oneDrv = match.drvInfo;
+
+        const auto drvName = DrvName { oneDrv.queryName() };
+        long comparison = 1;
+
+        const auto itOther = newest.find(drvName.name);
+
+        if (itOther != newest.end()) {
+            auto & newestDrv = itOther->second.drvInfo;
+
+            comparison =
+                oneDrv.querySystem() == newestDrv.querySystem() ? 0 :
+                oneDrv.querySystem() == settings.thisSystem ? 1 :
+                newestDrv.querySystem() == settings.thisSystem ? -1 : 0;
+            if (comparison == 0)
+                comparison = comparePriorities(state, oneDrv, newestDrv);
+            if (comparison == 0)
+                comparison = compareVersions(drvName.version, DrvName { newestDrv.queryName() }.version);
+        }
+
+        if (comparison > 0) {
+            newest.erase(drvName.name);
+            newest.emplace(drvName.name, match);
+            multiple.erase(drvName.fullName);
+        } else if (comparison == 0) {
+            multiple.insert(drvName.fullName);
+        }
+    }
+
+    matches.clear();
+    for (auto & [name, match] : newest) {
+        if (multiple.find(name) != multiple.end())
+            printInfo(
+                "warning: there are multiple derivations named '%1%'; using the first one",
+                name);
+        matches.push_back(match);
+    }
+
+    return matches;
+}
+
+} // end namespace
+
 static DrvInfos filterBySelector(EvalState & state, const DrvInfos & allElems,
     const Strings & args, bool newestOnly)
 {
@@ -232,79 +317,42 @@ static DrvInfos filterBySelector(EvalState & state, const DrvInfos & allElems,
         selectors.emplace_back("*");
 
     DrvInfos elems;
-    set<unsigned int> done;
+    std::set<std::size_t> done;
 
-    for (auto & i : selectors) {
-        typedef list<std::pair<DrvInfo, unsigned int> > Matches;
-        Matches matches;
-        unsigned int n = 0;
-        for (DrvInfos::const_iterator j = allElems.begin();
-             j != allElems.end(); ++j, ++n)
-        {
-            DrvName drvName(j->queryName());
-            if (i.matches(drvName)) {
-                i.hits++;
-                matches.push_back(std::pair<DrvInfo, unsigned int>(*j, n));
+    for (auto & selector : selectors) {
+        std::vector<Match> matches;
+        for (const auto & [index, drvInfo] : enumerate(allElems)) {
+            const auto drvName = DrvName { drvInfo.queryName() };
+            if (selector.matches(drvName)) {
+                ++selector.hits;
+                matches.emplace_back(drvInfo, index);
             }
         }
 
-        /* If `newestOnly', if a selector matches multiple derivations
-           with the same name, pick the one matching the current
-           system.  If there are still multiple derivations, pick the
-           one with the highest priority.  If there are still multiple
-           derivations, pick the one with the highest version.
-           Finally, if there are still multiple derivations,
-           arbitrarily pick the first one. */
         if (newestOnly) {
-
-            /* Map from package names to derivations. */
-            typedef map<string, std::pair<DrvInfo, unsigned int> > Newest;
-            Newest newest;
-            StringSet multiple;
-
-            for (auto & j : matches) {
-                DrvName drvName(j.first.queryName());
-                long d = 1;
-
-                Newest::iterator k = newest.find(drvName.name);
-
-                if (k != newest.end()) {
-                    d = j.first.querySystem() == k->second.first.querySystem() ? 0 :
-                        j.first.querySystem() == settings.thisSystem ? 1 :
-                        k->second.first.querySystem() == settings.thisSystem ? -1 : 0;
-                    if (d == 0)
-                        d = comparePriorities(state, j.first, k->second.first);
-                    if (d == 0)
-                        d = compareVersions(drvName.version, DrvName(k->second.first.queryName()).version);
-                }
-
-                if (d > 0) {
-                    newest.erase(drvName.name);
-                    newest.insert(Newest::value_type(drvName.name, j));
-                    multiple.erase(j.first.queryName());
-                } else if (d == 0) {
-                    multiple.insert(j.first.queryName());
-                }
-            }
-
-            matches.clear();
-            for (auto & j : newest) {
-                if (multiple.find(j.second.first.queryName()) != multiple.end())
-                    printInfo(
-                        "warning: there are multiple derivations named '%1%'; using the first one",
-                        j.second.first.queryName());
-                matches.push_back(j.second);
-            }
+            matches = pickNewestOnly(state, std::move(matches));
         }
 
         /* Insert only those elements in the final list that we
            haven't inserted before. */
-        for (auto & j : matches)
-            if (done.insert(j.second).second)
-                elems.push_back(j.first);
-    }
+        for (auto & match : matches)
+            if (done.insert(match.index).second)
+                elems.push_back(match.drvInfo);
 
-    checkSelectorUse(selectors);
+        if (selector.hits == 0 && selector.fullName != "*") {
+            const auto prefixHits = searchByPrefix(allElems, selector.name);
+            
+            if (prefixHits.empty()) {
+                throw Error("selector '%1%' matches no derivations", selector.fullName);    
+            } else {
+                std::string suggestionMessage = ", maybe you meant:";
+                for (const auto & drvName : prefixHits) {
+                    suggestionMessage += fmt("\n%s", drvName);
+                }
+                throw Error("selector '%1%' matches no derivations" + suggestionMessage, selector.fullName);
+            }
+        }
+    }
 
     return elems;
 }

From 9de324f554b884db7c243836b9294b8cca811fc1 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 18 Nov 2021 21:17:57 +0100
Subject: [PATCH 236/567] Remove nix-reduce-build and nix-http-export

These scripts are not installed and haven't been updated in many
years.
---
 .gitignore                     |   2 -
 scripts/local.mk               |   4 +-
 scripts/nix-http-export.cgi.in |  51 ----------
 scripts/nix-reduce-build.in    | 171 ---------------------------------
 4 files changed, 1 insertion(+), 227 deletions(-)
 delete mode 100755 scripts/nix-http-export.cgi.in
 delete mode 100755 scripts/nix-reduce-build.in

diff --git a/.gitignore b/.gitignore
index b6a5f6adc..2889a56eb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -26,8 +26,6 @@ perl/Makefile.config
 
 # /scripts/
 /scripts/nix-profile.sh
-/scripts/nix-reduce-build
-/scripts/nix-http-export.cgi
 /scripts/nix-profile-daemon.sh
 
 # /src/libexpr/
diff --git a/scripts/local.mk b/scripts/local.mk
index 2a0055852..b8477178e 100644
--- a/scripts/local.mk
+++ b/scripts/local.mk
@@ -1,7 +1,5 @@
 nix_noinst_scripts := \
-  $(d)/nix-http-export.cgi \
-  $(d)/nix-profile.sh \
-  $(d)/nix-reduce-build
+  $(d)/nix-profile.sh
 
 noinst-scripts += $(nix_noinst_scripts)
 
diff --git a/scripts/nix-http-export.cgi.in b/scripts/nix-http-export.cgi.in
deleted file mode 100755
index 19a505af1..000000000
--- a/scripts/nix-http-export.cgi.in
+++ /dev/null
@@ -1,51 +0,0 @@
-#! /bin/sh
-
-export HOME=/tmp
-export NIX_REMOTE=daemon
-
-TMP_DIR="${TMP_DIR:-/tmp/nix-export}"
-
-@coreutils@/mkdir -p "$TMP_DIR" || true
-@coreutils@/chmod a+r "$TMP_DIR"
-
-needed_path="?$QUERY_STRING"
-needed_path="${needed_path#*[?&]needed_path=}"
-needed_path="${needed_path%%&*}"
-#needed_path="$(echo $needed_path  | ./unhttp)"
-needed_path="${needed_path//%2B/+}"
-needed_path="${needed_path//%3D/=}"
-
-echo needed_path: "$needed_path" >&2
-
-NIX_STORE="${NIX_STORE_DIR:-/nix/store}"
-
-echo NIX_STORE: "${NIX_STORE}" >&2
-
-full_path="${NIX_STORE}"/"$needed_path"
-
-if [ "$needed_path" != "${needed_path%.drv}" ]; then
-	echo "Status: 403 You should create the derivation file yourself"
-	echo "Content-Type: text/plain"
-	echo
-	echo "Refusing to disclose derivation contents"
-	exit
-fi
-
-if @bindir@/nix-store --check-validity "$full_path"; then
-	if ! [ -e nix-export/"$needed_path".nar.gz ]; then
-		@bindir@/nix-store --export "$full_path" | @gzip@ > "$TMP_DIR"/"$needed_path".nar.gz
-		@coreutils@/ln -fs  "$TMP_DIR"/"$needed_path".nar.gz nix-export/"$needed_path".nar.gz 
-	fi;
-	echo "Status: 301 Moved"
-	echo "Location: nix-export/"$needed_path".nar.gz"
-	echo
-else 
-	echo "Status: 404 No such path found"
-	echo "Content-Type: text/plain"
-	echo
-	echo "Path not found:"
-	echo "$needed_path"
-	echo "checked:"
-	echo "$full_path"
-fi
-
diff --git a/scripts/nix-reduce-build.in b/scripts/nix-reduce-build.in
deleted file mode 100755
index 50beb9d10..000000000
--- a/scripts/nix-reduce-build.in
+++ /dev/null
@@ -1,171 +0,0 @@
-#! @bash@
-
-WORKING_DIRECTORY=$(mktemp -d "${TMPDIR:-/tmp}"/nix-reduce-build-XXXXXX);
-cd "$WORKING_DIRECTORY";
-
-if test -z "$1" || test "a--help" = "a$1" ; then
-	echo 'nix-reduce-build (paths or Nix expressions) -- (package sources)' >&2
-	echo As in: >&2
-	echo nix-reduce-build /etc/nixos/nixos -- ssh://user@somewhere.nowhere.example.org >&2
-	echo nix-reduce-build /etc/nixos/nixos -- \\
-	echo "   " \''http://somewhere.nowhere.example.org/nix/nix-http-export.cgi?needed_path='\' >&2
-	echo "  store path name will be added into the end of the URL" >&2
-	echo nix-reduce-build /etc/nixos/nixos -- file://home/user/nar/ >&2
-	echo "  that should be a directory where gzipped 'nix-store --export' ">&2
-	echo "  files are located (they should have .nar.gz extension)"  >&2
-	echo "        Or all together: " >&2
-	echo -e nix-reduce-build /expr.nix /e2.nix -- \\\\\\\n\
-	"    ssh://a@b.example.com http://n.example.com/get-nar?q= file://nar/" >&2
-	echo "        Also supports best-effort local builds of failing expression set:" >&2
-	echo "nix-reduce-build /e.nix -- nix-daemon:// nix-self://" >&2
-	echo "  nix-daemon:// builds using daemon"
-	echo "  nix-self:// builds directly using nix-store from current installation" >&2
-	echo "  nix-daemon-fixed:// and nix-self-fixed:// do the same, but only for" >&2;
-	echo "derivations with specified output hash (sha256, sha1 or md5)." >&2
-	echo "  nix-daemon-substitute:// and nix-self-substitute:// try to substitute" >&2;
-	echo "maximum amount of paths" >&2;
-	echo "  nix-daemon-build:// and nix-self-build:// try to build (not substitute)" >&2;
-	echo "maximum amount of paths" >&2;
-	echo "        If no package sources are specified, required paths are listed." >&2;
-	exit;
-fi;
-
-while ! test "$1" = "--" || test "$1" = "" ; do 
-	echo "$1" >> initial; >&2
-	shift;
-done
-shift;
-echo Will work on $(cat initial | wc -l) targets. >&2
-
-while read ; do
-	case "$REPLY" in 
-		${NIX_STORE_DIR:-/nix/store}/*)
-			echo "$REPLY" >> paths; >&2
-			;;
-		*)
-			(
-				IFS=: ;
-				nix-instantiate $REPLY >> paths;
-			);
-			;;
-	esac;
-done < initial;
-echo Proceeding $(cat paths | wc -l) paths. >&2
-
-while read; do
-	case "$REPLY" in
-		*.drv)
-			echo "$REPLY" >> derivers; >&2
-			;;
-		*)
-			nix-store --query --deriver "$REPLY" >>derivers;
-			;;
-	esac;
-done < paths;
-echo Found $(cat derivers | wc -l) derivers. >&2
-
-cat derivers | xargs nix-store --query -R > derivers-closure;
-echo Proceeding at most $(cat derivers-closure | wc -l) derivers. >&2
-
-cat derivers-closure | egrep '[.]drv$' | xargs nix-store --query --outputs > wanted-paths;
-cat derivers-closure | egrep -v '[.]drv$' >> wanted-paths;
-echo Prepared $(cat wanted-paths | wc -l) paths to get. >&2
-
-cat wanted-paths | xargs nix-store --check-validity --print-invalid > needed-paths;
-echo We need $(cat needed-paths | wc -l) paths. >&2
-
-egrep '[.]drv$' derivers-closure > critical-derivers;
-
-if test -z "$1" ; then
-	cat needed-paths;	
-fi;
-
-refresh_critical_derivers() {
-    echo "Finding needed derivers..." >&2;
-    cat critical-derivers | while read; do
-        if ! (nix-store --query --outputs "$REPLY" | xargs nix-store --check-validity &> /dev/null;); then
-            echo "$REPLY";
-        fi;
-    done > new-critical-derivers;
-    mv new-critical-derivers critical-derivers;
-    echo The needed paths are realized by $(cat critical-derivers | wc -l) derivers. >&2
-}
-
-build_here() {
-    cat critical-derivers | while read; do 
-        echo "Realising $REPLY using nix-daemon" >&2
-        @bindir@/nix-store -r "${REPLY}"
-    done;
-}
-
-try_to_substitute(){
-    cat needed-paths | while read ; do 
-        echo "Building $REPLY using nix-daemon" >&2
-        @bindir@/nix-store -r "${NIX_STORE_DIR:-/nix/store}/${REPLY##*/}"
-    done;
-}
-
-for i in "$@"; do 
-	sshHost="${i#ssh://}";
-	httpHost="${i#http://}";
-	httpsHost="${i#https://}";
-	filePath="${i#file:/}";
-	if [ "$i" != "$sshHost" ]; then
-		cat needed-paths | while read; do 
-			echo "Getting $REPLY and its closure over ssh" >&2
-			nix-copy-closure --from "$sshHost" --gzip "$REPLY" </dev/null || true; 
-		done;
-	elif [ "$i" != "$httpHost" ] || [ "$i" != "$httpsHost" ]; then
-		cat needed-paths | while read; do
-			echo "Getting $REPLY over http/https" >&2
-			curl ${BAD_CERTIFICATE:+-k} -L "$i${REPLY##*/}" | gunzip | nix-store --import;
-		done;
-	elif [ "$i" != "$filePath" ] ; then
-		cat needed-paths | while read; do 
-			echo "Installing $REPLY from file" >&2
-			gunzip < "$filePath/${REPLY##*/}".nar.gz | nix-store --import;
-		done;
-	elif [ "$i" = "nix-daemon://" ] ; then
-		NIX_REMOTE=daemon try_to_substitute;
-		refresh_critical_derivers;
-		NIX_REMOTE=daemon build_here;
-	elif [ "$i" = "nix-self://" ] ; then
-		NIX_REMOTE= try_to_substitute;
-		refresh_critical_derivers;
-		NIX_REMOTE= build_here;
-	elif [ "$i" = "nix-daemon-fixed://" ] ; then
-		refresh_critical_derivers;
-
-		cat critical-derivers | while read; do 
-			if egrep '"(md5|sha1|sha256)"' "$REPLY" &>/dev/null; then
-				echo "Realising $REPLY using nix-daemon" >&2
-				NIX_REMOTE=daemon @bindir@/nix-store -r "${REPLY}"
-			fi;
-		done;
-	elif [ "$i" = "nix-self-fixed://" ] ; then
-		refresh_critical_derivers;
-
-		cat critical-derivers | while read; do 
-			if egrep '"(md5|sha1|sha256)"' "$REPLY" &>/dev/null; then
-				echo "Realising $REPLY using direct Nix build" >&2
-				NIX_REMOTE= @bindir@/nix-store -r "${REPLY}"
-			fi;
-		done;
-	elif [ "$i" = "nix-daemon-substitute://" ] ; then
-		NIX_REMOTE=daemon try_to_substitute;
-	elif [ "$i" = "nix-self-substitute://" ] ; then
-		NIX_REMOTE= try_to_substitute;
-	elif [ "$i" = "nix-daemon-build://" ] ; then
-		refresh_critical_derivers;
-		NIX_REMOTE=daemon build_here;
-	elif [ "$i" = "nix-self-build://" ] ; then
-		refresh_critical_derivers;
-		NIX_REMOTE= build_here;
-	fi;
-	mv needed-paths wanted-paths;
-	cat wanted-paths | xargs nix-store --check-validity --print-invalid > needed-paths;
-	echo We still need $(cat needed-paths | wc -l) paths. >&2
-done;
-
-cd /
-rm -r "$WORKING_DIRECTORY"

From 06fb6aecea43218e66ccc879471ffebb7dbfee78 Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Thu, 18 Nov 2021 22:22:33 +0000
Subject: [PATCH 237/567] Fix testing the other daemon

The eventual PATH entry needs the `.../bin` or we will not use the right
daemon.
---
 tests/common.sh.in | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/common.sh.in b/tests/common.sh.in
index 3d0d56120..61abab1d7 100644
--- a/tests/common.sh.in
+++ b/tests/common.sh.in
@@ -38,7 +38,7 @@ if [[ -n "${NIX_CLIENT_PACKAGE:-}" ]]; then
 fi
 DAEMON_PATH="$PATH"
 if [[ -n "${NIX_DAEMON_PACKAGE:-}" ]]; then
-  DAEMON_PATH="${NIX_DAEMON_PACKAGE}:$DAEMON_PATH"
+  DAEMON_PATH="${NIX_DAEMON_PACKAGE}/bin:$DAEMON_PATH"
 fi
 coreutils=@coreutils@
 

From d5b36bdb58c5b8182b36ee6869936323a2f2fec7 Mon Sep 17 00:00:00 2001
From: Kristof Molnar-Tatai <kristof.molnar-tatai@oracle.com>
Date: Fri, 19 Nov 2021 13:10:04 +0100
Subject: [PATCH 238/567] switch order of wget and curl

This change makes the script consistent with the installation
instructions while keeping wget as an alternative.
---
 scripts/install.in | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/scripts/install.in b/scripts/install.in
index 5be4f9dda..38d1fb36f 100755
--- a/scripts/install.in
+++ b/scripts/install.in
@@ -81,10 +81,10 @@ if [ "$(uname -s)" != "Darwin" ]; then
     require_util xz "unpack the binary tarball"
 fi
 
-if command -v wget > /dev/null 2>&1; then
-    fetch() { wget "$1" -O "$2"; }
-elif command -v curl > /dev/null 2>&1; then
+if command -v curl > /dev/null 2>&1; then
     fetch() { curl -L "$1" -o "$2"; }
+elif command -v wget > /dev/null 2>&1; then
+    fetch() { wget "$1" -O "$2"; }
 else
     oops "you don't have wget or curl installed, which I need to download the binary tarball"
 fi

From eff48e84d9fde4e98adcdd0ff325b93a8d47947a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sandro=20J=C3=A4ckel?= <sandro.jaeckel@gmail.com>
Date: Thu, 18 Nov 2021 18:33:13 +0100
Subject: [PATCH 239/567] Apply some shellcheck suggestions

---
 scripts/install-multi-user.sh                |  2 +-
 scripts/install-nix-from-closure.sh          | 14 +++++++-------
 scripts/install-systemd-multi-user.sh        |  2 +-
 scripts/nix-profile-daemon.sh.in             |  6 +++---
 scripts/prepare-installer-for-github-actions |  2 +-
 5 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/scripts/install-multi-user.sh b/scripts/install-multi-user.sh
index eba894799..0dba36f51 100644
--- a/scripts/install-multi-user.sh
+++ b/scripts/install-multi-user.sh
@@ -818,7 +818,7 @@ main() {
     # can fail faster in this case. Sourcing install-darwin... now runs
     # `touch /` to detect Read-only root, but it could update times on
     # pre-Catalina macOS if run as root user.
-    if [ $EUID -eq 0 ]; then
+    if [ "$EUID" -eq 0 ]; then
         failure <<EOF
 Please do not run this script with root privileges. I will call sudo
 when I need to.
diff --git a/scripts/install-nix-from-closure.sh b/scripts/install-nix-from-closure.sh
index e25978da7..b5e2fea83 100644
--- a/scripts/install-nix-from-closure.sh
+++ b/scripts/install-nix-from-closure.sh
@@ -134,7 +134,7 @@ fi
 
 echo "performing a single-user installation of Nix..." >&2
 
-if ! [ -e $dest ]; then
+if ! [ -e "$dest" ]; then
     cmd="mkdir -m 0755 $dest && chown $USER $dest"
     echo "directory $dest does not exist; creating it by running '$cmd' using sudo" >&2
     if ! sudo sh -c "$cmd"; then
@@ -143,12 +143,12 @@ if ! [ -e $dest ]; then
     fi
 fi
 
-if ! [ -w $dest ]; then
+if ! [ -w "$dest" ]; then
     echo "$0: directory $dest exists, but is not writable by you. This could indicate that another user has already performed a single-user installation of Nix on this system. If you wish to enable multi-user support see https://nixos.org/nix/manual/#ssec-multi-user. If you wish to continue with a single-user install for $USER please run 'chown -R $USER $dest' as root." >&2
     exit 1
 fi
 
-mkdir -p $dest/store
+mkdir -p "$dest/store"
 
 printf "copying Nix to %s..." "${dest}/store" >&2
 # Insert a newline if no progress is shown.
@@ -189,17 +189,17 @@ fi
 
 # Install an SSL certificate bundle.
 if [ -z "$NIX_SSL_CERT_FILE" ] || ! [ -f "$NIX_SSL_CERT_FILE" ]; then
-    $nix/bin/nix-env -i "$cacert"
+    "$nix/bin/nix-env" -i "$cacert"
     export NIX_SSL_CERT_FILE="$HOME/.nix-profile/etc/ssl/certs/ca-bundle.crt"
 fi
 
 # Subscribe the user to the Nixpkgs channel and fetch it.
 if [ -z "$NIX_INSTALLER_NO_CHANNEL_ADD" ]; then
-    if ! $nix/bin/nix-channel --list | grep -q "^nixpkgs "; then
-        $nix/bin/nix-channel --add https://nixos.org/channels/nixpkgs-unstable
+    if ! "$nix/bin/nix-channel" --list | grep -q "^nixpkgs "; then
+        "$nix/bin/nix-channel" --add https://nixos.org/channels/nixpkgs-unstable
     fi
     if [ -z "$_NIX_INSTALLER_TEST" ]; then
-        if ! $nix/bin/nix-channel --update nixpkgs; then
+        if ! "$nix/bin/nix-channel" --update nixpkgs; then
             echo "Fetching the nixpkgs channel failed. (Are you offline?)"
             echo "To try again later, run \"nix-channel --update nixpkgs\"."
         fi
diff --git a/scripts/install-systemd-multi-user.sh b/scripts/install-systemd-multi-user.sh
index 81c61b2a0..f4a2dfc5d 100755
--- a/scripts/install-systemd-multi-user.sh
+++ b/scripts/install-systemd-multi-user.sh
@@ -15,7 +15,7 @@ readonly SERVICE_OVERRIDE=${SERVICE_DEST}.d/override.conf
 
 create_systemd_override() {
      header "Configuring proxy for the nix-daemon service"
-    _sudo "create directory for systemd unit override" mkdir -p "$(dirname $SERVICE_OVERRIDE)"
+    _sudo "create directory for systemd unit override" mkdir -p "$(dirname "$SERVICE_OVERRIDE")"
     cat <<EOF | _sudo "create systemd unit override" tee "$SERVICE_OVERRIDE"
 [Service]
 $1
diff --git a/scripts/nix-profile-daemon.sh.in b/scripts/nix-profile-daemon.sh.in
index 500a98992..0a47571ac 100644
--- a/scripts/nix-profile-daemon.sh.in
+++ b/scripts/nix-profile-daemon.sh.in
@@ -5,7 +5,7 @@ __ETC_PROFILE_NIX_SOURCED=1
 export NIX_PROFILES="@localstatedir@/nix/profiles/default $HOME/.nix-profile"
 
 # Set $NIX_SSL_CERT_FILE so that Nixpkgs applications like curl work.
-if [ ! -z "${NIX_SSL_CERT_FILE:-}" ]; then
+if [ -n "${NIX_SSL_CERT_FILE:-}" ]; then
     : # Allow users to override the NIX_SSL_CERT_FILE
 elif [ -e /etc/ssl/certs/ca-certificates.crt ]; then # NixOS, Ubuntu, Debian, Gentoo, Arch
     export NIX_SSL_CERT_FILE=/etc/ssl/certs/ca-certificates.crt
@@ -18,14 +18,14 @@ elif [ -e /etc/pki/tls/certs/ca-bundle.crt ]; then # Fedora, CentOS
 else
   # Fall back to what is in the nix profiles, favouring whatever is defined last.
   check_nix_profiles() {
-    if [ "$ZSH_VERSION" ]; then
+    if [ -n "$ZSH_VERSION" ]; then
       # Zsh by default doesn't split words in unquoted parameter expansion.
       # Set local_options for these options to be reverted at the end of the function
       # and shwordsplit to force splitting words in $NIX_PROFILES below.
       setopt local_options shwordsplit
     fi
     for i in $NIX_PROFILES; do
-      if [ -e $i/etc/ssl/certs/ca-bundle.crt ]; then
+      if [ -e "$i/etc/ssl/certs/ca-bundle.crt" ]; then
         export NIX_SSL_CERT_FILE=$i/etc/ssl/certs/ca-bundle.crt
       fi
     done
diff --git a/scripts/prepare-installer-for-github-actions b/scripts/prepare-installer-for-github-actions
index 92d930384..4b994a753 100755
--- a/scripts/prepare-installer-for-github-actions
+++ b/scripts/prepare-installer-for-github-actions
@@ -3,7 +3,7 @@
 set -e
 
 script=$(nix-build -A outputs.hydraJobs.installerScriptForGHA --no-out-link)
-installerHash=$(echo $script | cut -b12-43 -)
+installerHash=$(echo "$script" | cut -b12-43 -)
 
 installerURL=https://$CACHIX_NAME.cachix.org/serve/$installerHash/install
 

From a18d9269a516c5f8149b04ccb01034960f4851d8 Mon Sep 17 00:00:00 2001
From: Alex Shabalin <alex.shabalin@tweag.io>
Date: Fri, 19 Nov 2021 15:22:31 +0100
Subject: [PATCH 240/567] Fix build warnings on MacOS

---
 src/libstore/build/local-derivation-goal.cc | 5 ++++-
 src/libstore/gc.cc                          | 2 ++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 3c7bd695e..c9a4a31e7 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -342,7 +342,7 @@ int childEntry(void * arg)
     return 1;
 }
 
-
+#if __linux__
 static void linkOrCopy(const Path & from, const Path & to)
 {
     if (link(from.c_str(), to.c_str()) == -1) {
@@ -358,6 +358,7 @@ static void linkOrCopy(const Path & from, const Path & to)
         copyPath(from, to);
     }
 }
+#endif
 
 
 void LocalDerivationGoal::startBuilder()
@@ -917,7 +918,9 @@ void LocalDerivationGoal::startBuilder()
     } else
 #endif
     {
+#if __linux__
     fallback:
+#endif
         pid = startProcess([&]() {
             runChild();
         });
diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 8030c84f5..29d45e067 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -324,6 +324,7 @@ static string quoteRegexChars(const string & raw)
     return std::regex_replace(raw, specialRegex, R"(\$&)");
 }
 
+#if defined(__linux__)
 static void readFileRoots(const char * path, UncheckedRoots & roots)
 {
     try {
@@ -333,6 +334,7 @@ static void readFileRoots(const char * path, UncheckedRoots & roots)
             throw;
     }
 }
+#endif
 
 void LocalStore::findRuntimeRoots(Roots & roots, bool censor)
 {

From 86b79628073154b853b2e57360c062654826f5ee Mon Sep 17 00:00:00 2001
From: Alex Shabalin <alex.shabalin@tweag.io>
Date: Fri, 19 Nov 2021 16:29:55 +0100
Subject: [PATCH 241/567] Use warn to print a warning

---
 src/nix-env/nix-env.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index 1c78b5307..490f450df 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -298,8 +298,8 @@ std::vector<Match> pickNewestOnly(EvalState & state, std::vector<Match> matches)
     matches.clear();
     for (auto & [name, match] : newest) {
         if (multiple.find(name) != multiple.end())
-            printInfo(
-                "warning: there are multiple derivations named '%1%'; using the first one",
+            warn(
+                "there are multiple derivations named '%1%'; using the first one",
                 name);
         matches.push_back(match);
     }

From 4318ba2ec568a9fe7d5b4b014df6b7d252ae3481 Mon Sep 17 00:00:00 2001
From: Tom Bereknyei <tomberek@gmail.com>
Date: Fri, 19 Nov 2021 23:52:52 -0500
Subject: [PATCH 242/567] add real path to allowedPaths

---
 src/libexpr/eval.cc    | 4 ++--
 src/libexpr/primops.cc | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index f1ff3a6e0..97fc04711 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -520,7 +520,7 @@ Path EvalState::checkSourcePath(const Path & path_)
     }
 
     if (!found)
-        throw RestrictedPathError("access to path '%1%' is forbidden in restricted mode", abspath);
+        throw RestrictedPathError("access to absolute path '%1%' is forbidden in restricted mode", abspath);
 
     /* Resolve symlinks. */
     debug(format("checking access to '%s'") % abspath);
@@ -533,7 +533,7 @@ Path EvalState::checkSourcePath(const Path & path_)
         }
     }
 
-    throw RestrictedPathError("access to path '%1%' is forbidden in restricted mode", path);
+    throw RestrictedPathError("access to canonical path '%1%' is forbidden in restricted mode", path);
 }
 
 
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 5bd4e5545..8dccf6401 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -70,7 +70,7 @@ void EvalState::realiseContext(const PathSet & context)
                 if (outputPaths.count(outputName) == 0)
                     throw Error("derivation '%s' does not have an output named '%s'",
                             store->printStorePath(drvPath), outputName);
-                allowedPaths->insert(store->printStorePath(outputPaths.at(outputName)));
+                allowPath(outputPaths.at(outputName));
             }
         }
     }

From 664ee49e0d6f1ce0a1608559beeaf82bd039c690 Mon Sep 17 00:00:00 2001
From: Alyssa Ross <hi@alyssa.is>
Date: Sun, 21 Nov 2021 15:52:01 +0000
Subject: [PATCH 243/567] nix-shell --pure: let variables for Wayland through

We let DISPLAY (X11) through, so we should let the Wayland equivalents
through as well.  Similarly, we let HOME through, so it should be okay
to allow XDG_RUNTIME_DIR (which is needed for connecting to Wayland
with WAYLAND_DISPLAY) through as well.  Otherwise graphical
applications will either fall back to X11 (if they support it), or
just not work (if they don't).
---
 src/nix-build/nix-build.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index 73d93480e..75576ef8a 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -105,7 +105,8 @@ static void main_nix_build(int argc, char * * argv)
 
     // List of environment variables kept for --pure
     std::set<string> keepVars{
-        "HOME", "USER", "LOGNAME", "DISPLAY", "PATH", "TERM", "IN_NIX_SHELL",
+        "HOME", "XDG_RUNTIME_DIR", "USER", "LOGNAME", "DISPLAY",
+        "WAYLAND_DISPLAY", "WAYLAND_SOCKET", "PATH", "TERM", "IN_NIX_SHELL",
         "NIX_SHELL_PRESERVE_PROMPT", "TZ", "PAGER", "NIX_BUILD_SHELL", "SHLVL",
         "http_proxy", "https_proxy", "ftp_proxy", "all_proxy", "no_proxy"
     };

From 0768c08d999593fc23675b17c6f0480a35206c47 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Roman=20Fro=C5=82ow?= <rofrol@gmail.com>
Date: Mon, 22 Nov 2021 13:35:35 +0100
Subject: [PATCH 244/567] Typo: change to normal singlequote

---
 src/libexpr/primops.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 5bd4e5545..09007a22c 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -2710,9 +2710,9 @@ static RegisterPrimOp primop_foldlStrict({
     .args = {"op", "nul", "list"},
     .doc = R"(
       Reduce a list by applying a binary operator, from left to right,
-      e.g. `foldl’ op nul [x0 x1 x2 ...] = op (op (op nul x0) x1) x2)
+      e.g. `foldl' op nul [x0 x1 x2 ...] = op (op (op nul x0) x1) x2)
       ...`. The operator is applied strictly, i.e., its arguments are
-      evaluated first. For example, `foldl’ (x: y: x + y) 0 [1 2 3]`
+      evaluated first. For example, `foldl' (x: y: x + y) 0 [1 2 3]`
       evaluates to 6.
     )",
     .fun = prim_foldlStrict,

From db2e4489a54c1c4bf5bd8fd2deb8b3fd02a712f1 Mon Sep 17 00:00:00 2001
From: Alex Shabalin <alex.shabalin@tweag.io>
Date: Mon, 22 Nov 2021 13:57:56 +0100
Subject: [PATCH 245/567] Unify #if linux

---
 src/libstore/gc.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 29d45e067..7a414da6b 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -324,7 +324,7 @@ static string quoteRegexChars(const string & raw)
     return std::regex_replace(raw, specialRegex, R"(\$&)");
 }
 
-#if defined(__linux__)
+#if __linux__
 static void readFileRoots(const char * path, UncheckedRoots & roots)
 {
     try {
@@ -416,7 +416,7 @@ void LocalStore::findRuntimeRoots(Roots & roots, bool censor)
     }
 #endif
 
-#if defined(__linux__)
+#if __linux__
     readFileRoots("/proc/sys/kernel/modprobe", unchecked);
     readFileRoots("/proc/sys/kernel/fbsplash", unchecked);
     readFileRoots("/proc/sys/kernel/poweroff_cmd", unchecked);

From f68699963c51d343e95969397f436af73ba4b1b4 Mon Sep 17 00:00:00 2001
From: Jan Tojnar <jtojnar@gmail.com>
Date: Mon, 22 Nov 2021 17:57:30 +0100
Subject: [PATCH 246/567] flake: Do not use aliases

gmock is not available with `nixpkgs.config.allowAliases = false`.
---
 flake.nix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/flake.nix b/flake.nix
index fd5e18429..01afc23c3 100644
--- a/flake.nix
+++ b/flake.nix
@@ -91,7 +91,7 @@
             libarchive
             boost
             lowdown-nix
-            gmock
+            gtest
           ]
           ++ lib.optionals stdenv.isLinux [libseccomp]
           ++ lib.optional (stdenv.isLinux || stdenv.isDarwin) libsodium

From 08b1ac3e389cda2ba0947e25ea7b09ba2df4813f Mon Sep 17 00:00:00 2001
From: Matthew Bauer <mjbauer95@gmail.com>
Date: Mon, 22 Nov 2021 14:42:31 -0600
Subject: [PATCH 247/567] Set new rosetta 2 path in sandbox

see:

https://github.com/NixOS/nix/pull/5388

and

https://github.com/NixOS/nix/pull/5251
---
 src/libstore/sandbox-defaults.sb | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/libstore/sandbox-defaults.sb b/src/libstore/sandbox-defaults.sb
index 41893e6dd..56b35c3fe 100644
--- a/src/libstore/sandbox-defaults.sb
+++ b/src/libstore/sandbox-defaults.sb
@@ -100,4 +100,5 @@
 
 ; Allow Rosetta 2 to run x86_64 binaries on aarch64-darwin.
 (allow file-read*
-       (subpath "/Library/Apple/usr/libexec/oah"))
+       (subpath "/Library/Apple/usr/libexec/oah")
+       (subpath "/System/Library/Apple/usr/libexec/oah"))

From 5be8fbd7403b0b2df268ca79a3dc93cae8f55758 Mon Sep 17 00:00:00 2001
From: "dependabot[bot]" <49699333+dependabot[bot]@users.noreply.github.com>
Date: Mon, 22 Nov 2021 22:01:42 +0000
Subject: [PATCH 248/567] Bump cachix/install-nix-action from 15 to 16

Bumps [cachix/install-nix-action](https://github.com/cachix/install-nix-action) from 15 to 16.
- [Release notes](https://github.com/cachix/install-nix-action/releases)
- [Commits](https://github.com/cachix/install-nix-action/compare/v15...v16)

---
updated-dependencies:
- dependency-name: cachix/install-nix-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
---
 .github/workflows/test.yml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index be4fcd8d1..1b655e27d 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -17,7 +17,7 @@ jobs:
     - uses: actions/checkout@v2.4.0
       with:
         fetch-depth: 0
-    - uses: cachix/install-nix-action@v15
+    - uses: cachix/install-nix-action@v16
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
     - uses: cachix/cachix-action@v10
       if: needs.check_cachix.outputs.secret == 'true'
@@ -50,7 +50,7 @@ jobs:
       with:
         fetch-depth: 0
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
-    - uses: cachix/install-nix-action@v15
+    - uses: cachix/install-nix-action@v16
     - uses: cachix/cachix-action@v10
       with:
         name: '${{ env.CACHIX_NAME }}'
@@ -69,7 +69,7 @@ jobs:
     steps:
     - uses: actions/checkout@v2.4.0
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
-    - uses: cachix/install-nix-action@v15
+    - uses: cachix/install-nix-action@v16
       with:
         install_url: '${{needs.installer.outputs.installerURL}}'
         install_options: "--tarball-url-prefix https://${{ env.CACHIX_NAME }}.cachix.org/serve"

From cd72a8c346ca752441327cce4a2e94a2b38055bd Mon Sep 17 00:00:00 2001
From: Rok Garbas <rok@garbas.si>
Date: Tue, 23 Nov 2021 11:31:05 +0100
Subject: [PATCH 249/567] Make docker image downloadable in Hydra UI

---
 flake.nix | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/flake.nix b/flake.nix
index 01afc23c3..8a90de5e2 100644
--- a/flake.nix
+++ b/flake.nix
@@ -407,10 +407,18 @@
 
         # docker image with Nix inside
         dockerImage = nixpkgs.lib.genAttrs linux64BitSystems (system:
-          import ./docker.nix {
+          let
             pkgs = nixpkgsFor.${system};
-            tag = version;
-          });
+            image = import ./docker.nix { inherit pkgs; tag = version; };
+          in pkgs.runCommand "docker-image-tarball-${version}"
+            { meta.description = "Docker image with Nix for ${system}";
+            }
+            ''
+              mkdir -p $out/nix-support
+              image=$out/image.tar.gz
+              cp ${image} $image
+              echo "file binary-dist $image" >> $out/nix-support/hydra-build-products
+            '');
 
         # Line coverage analysis.
         coverage =

From 861404a87b2c551ebc189f91ae00d21c1287346a Mon Sep 17 00:00:00 2001
From: Ben Radford <bradford@paxos.com>
Date: Tue, 23 Nov 2021 12:55:49 +0000
Subject: [PATCH 250/567] Add missing Nix::Store import to fix nix-serve
 StoreDir.

---
 perl/lib/Nix/Config.pm.in | 1 +
 1 file changed, 1 insertion(+)

diff --git a/perl/lib/Nix/Config.pm.in b/perl/lib/Nix/Config.pm.in
index f7c6f2484..508a15e15 100644
--- a/perl/lib/Nix/Config.pm.in
+++ b/perl/lib/Nix/Config.pm.in
@@ -1,6 +1,7 @@
 package Nix::Config;
 
 use MIME::Base64;
+use Nix::Store;
 
 $version = "@PACKAGE_VERSION@";
 

From b26cb0c9ac406e03ee54aa07d36350feae8c9bfc Mon Sep 17 00:00:00 2001
From: Alex Shabalin <alex.shabalin@tweag.io>
Date: Tue, 23 Nov 2021 16:15:34 +0100
Subject: [PATCH 251/567] Fix use after free in content-address.cc

Inspired by https://github.com/NixOS/nix/pull/5599
---
 src/libstore/content-address.cc | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/libstore/content-address.cc b/src/libstore/content-address.cc
index 974d1c471..cf32ccdc4 100644
--- a/src/libstore/content-address.cc
+++ b/src/libstore/content-address.cc
@@ -120,8 +120,10 @@ ContentAddress parseContentAddress(std::string_view rawCa) {
 
 ContentAddressMethod parseContentAddressMethod(std::string_view caMethod)
 {
-    std::string_view asPrefix {std::string{caMethod} + ":"};
-    return parseContentAddressMethodPrefix(asPrefix);
+    std::string asPrefix = std::string{caMethod} + ":";
+    // parseContentAddressMethodPrefix takes its argument by reference
+    std::string_view asPrefixView = asPrefix;
+    return parseContentAddressMethodPrefix(asPrefixView);
 }
 
 std::optional<ContentAddress> parseContentAddressOpt(std::string_view rawCaOpt)

From d41af23a6c879fe2b5f88e40e0ad87db099a23cf Mon Sep 17 00:00:00 2001
From: Farid Zakaria <farid.m.zakaria@gmail.com>
Date: Thu, 18 Nov 2021 14:54:50 -0800
Subject: [PATCH 252/567] Fix heap use after free in progress-bar.cc

Fix some heap-use-after-free in progress-bar.cc

These are somewhat tricky failures here due to temporary variable
creation and string_view
---
 src/libmain/progress-bar.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libmain/progress-bar.cc b/src/libmain/progress-bar.cc
index 63955eed1..f4306ab91 100644
--- a/src/libmain/progress-bar.cc
+++ b/src/libmain/progress-bar.cc
@@ -11,7 +11,7 @@
 
 namespace nix {
 
-static std::string getS(const std::vector<Logger::Field> & fields, size_t n)
+static std::string_view getS(const std::vector<Logger::Field> & fields, size_t n)
 {
     assert(n < fields.size());
     assert(fields[n].type == Logger::Field::tString);

From 286eb81143908a49e96fa800e01b302d8f4b7370 Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Fri, 19 Nov 2021 02:28:20 +0000
Subject: [PATCH 253/567] "recursive-nix" system feature only with experimental
 feature

---
 src/libstore/globals.cc   | 2 +-
 src/libstore/store-api.cc | 5 +++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/libstore/globals.cc b/src/libstore/globals.cc
index 9f1a88130..81ca9cc0f 100644
--- a/src/libstore/globals.cc
+++ b/src/libstore/globals.cc
@@ -122,7 +122,7 @@ StringSet Settings::getDefaultSystemFeatures()
     /* For backwards compatibility, accept some "features" that are
        used in Nixpkgs to route builds to certain machines but don't
        actually require anything special on the machines. */
-    StringSet features{"nixos-test", "benchmark", "big-parallel", "recursive-nix"};
+    StringSet features{"nixos-test", "benchmark", "big-parallel"};
 
     #if __linux__
     if (access("/dev/kvm", R_OK | W_OK) == 0)
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index c88dfe179..71350906e 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -355,8 +355,13 @@ ValidPathInfo Store::addToStoreSlow(std::string_view name, const Path & srcPath,
 StringSet StoreConfig::getDefaultSystemFeatures()
 {
     auto res = settings.systemFeatures.get();
+
     if (settings.isExperimentalFeatureEnabled(Xp::CaDerivations))
         res.insert("ca-derivations");
+
+    if (settings.isExperimentalFeatureEnabled(Xp::RecursiveNix))
+        res.insert("recursive-nix");
+
     return res;
 }
 

From 52c84c15e5c8b996bcd0c5e13db656769804d05f Mon Sep 17 00:00:00 2001
From: Rok Garbas <rok@garbas.si>
Date: Wed, 24 Nov 2021 09:18:33 +0100
Subject: [PATCH 254/567] Don't copy, to reduce store size

---
 flake.nix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/flake.nix b/flake.nix
index 8a90de5e2..ba2f2a50c 100644
--- a/flake.nix
+++ b/flake.nix
@@ -416,7 +416,7 @@
             ''
               mkdir -p $out/nix-support
               image=$out/image.tar.gz
-              cp ${image} $image
+              ln -s ${image} $image
               echo "file binary-dist $image" >> $out/nix-support/hydra-build-products
             '');
 

From e7906ffd0e6e6ec1b6c01d77bf8db446abf6cd51 Mon Sep 17 00:00:00 2001
From: Rok Garbas <rok@garbas.si>
Date: Wed, 24 Nov 2021 09:19:29 +0100
Subject: [PATCH 255/567] Add dockerImage to the checks

---
 flake.nix | 1 +
 1 file changed, 1 insertion(+)

diff --git a/flake.nix b/flake.nix
index ba2f2a50c..1b98b526e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -524,6 +524,7 @@
         binaryTarball = self.hydraJobs.binaryTarball.${system};
         perlBindings = self.hydraJobs.perlBindings.${system};
         installTests = self.hydraJobs.installTests.${system};
+        dockerImage = self.hydraJobs.dockerImage.${system};
       });
 
       packages = forAllSystems (system: {

From 09471d2680292af48b2788108de56a8da755d661 Mon Sep 17 00:00:00 2001
From: Silvan Mosberger <contact@infinisil.com>
Date: Mon, 22 Nov 2021 23:56:40 +0100
Subject: [PATCH 256/567] Make lists be comparable

Makes lists comparable using lexicographic comparison.

Increments builtins.langVersion in order for this change to be
detectable
---
 .../src/expressions/language-operators.md     |  8 +++---
 doc/manual/src/release-notes/rl-next.md       |  2 ++
 src/libexpr/primops.cc                        | 26 +++++++++++++++----
 tests/lang/eval-okay-sort.exp                 |  2 +-
 tests/lang/eval-okay-sort.nix                 | 14 +++++++++-
 5 files changed, 41 insertions(+), 11 deletions(-)

diff --git a/doc/manual/src/expressions/language-operators.md b/doc/manual/src/expressions/language-operators.md
index 6ab319039..268b44f4c 100644
--- a/doc/manual/src/expressions/language-operators.md
+++ b/doc/manual/src/expressions/language-operators.md
@@ -17,10 +17,10 @@ order of precedence (from strongest to weakest binding).
 | String Concatenation     | *string1* `+` *string2*             | left          | String concatenation.                                                                                                                                                                                                         | 7          |
 | Not                      | `!` *e*                             | none          | Boolean negation.                                                                                                                                                                                                             | 8          |
 | Update                   | *e1* `//` *e2*                      | right         | Return a set consisting of the attributes in *e1* and *e2* (with the latter taking precedence over the former in case of equally named attributes).                                                                           | 9          |
-| Less Than                | *e1* `<` *e2*,                      | none          | Arithmetic comparison.                                                                                                                                                                                                        | 10         |
-| Less Than or Equal To    | *e1* `<=` *e2*                      | none          | Arithmetic comparison.                                                                                                                                                                                                        | 10         |
-| Greater Than             | *e1* `>` *e2*                       | none          | Arithmetic comparison.                                                                                                                                                                                                        | 10         |
-| Greater Than or Equal To | *e1* `>=` *e2*                      | none          | Arithmetic comparison.                                                                                                                                                                                                        | 10         |
+| Less Than                | *e1* `<` *e2*,                      | none          | Arithmetic/lexicographic comparison.                                                                                                                                                                                                        | 10         |
+| Less Than or Equal To    | *e1* `<=` *e2*                      | none          | Arithmetic/lexicographic comparison.                                                                                                                                                                                                        | 10         |
+| Greater Than             | *e1* `>` *e2*                       | none          | Arithmetic/lexicographic comparison.                                                                                                                                                                                                        | 10         |
+| Greater Than or Equal To | *e1* `>=` *e2*                      | none          | Arithmetic/lexicographic comparison.                                                                                                                                                                                                        | 10         |
 | Equality                 | *e1* `==` *e2*                      | none          | Equality.                                                                                                                                                                                                                     | 11         |
 | Inequality               | *e1* `!=` *e2*                      | none          | Inequality.                                                                                                                                                                                                                   | 11         |
 | Logical AND              | *e1* `&&` *e2*                      | left          | Logical AND.                                                                                                                                                                                                                  | 12         |
diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index 9a29938c2..26c7d2cce 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -3,3 +3,5 @@
 * Binary cache stores now have a setting `compression-level`.
 
 * `nix develop` now has a flag `--unpack` to run `unpackPhase`.
+
+* Lists can now be compared lexicographically using the `<` operator.
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 8dccf6401..69f4737a8 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -517,7 +517,11 @@ static RegisterPrimOp primop_isPath({
 
 struct CompareValues
 {
-    bool operator () (const Value * v1, const Value * v2) const
+    EvalState & state;
+
+    CompareValues(EvalState & state) : state(state) { };
+
+    bool operator () (Value * v1, Value * v2) const
     {
         if (v1->type() == nFloat && v2->type() == nInt)
             return v1->fpoint < v2->integer;
@@ -534,6 +538,17 @@ struct CompareValues
                 return strcmp(v1->string.s, v2->string.s) < 0;
             case nPath:
                 return strcmp(v1->path, v2->path) < 0;
+            case nList:
+                // Lexicographic comparison
+                for (size_t i = 0;; i++) {
+                    if (i == v2->listSize()) {
+                        return false;
+                    } else if (i == v1->listSize()) {
+                        return true;
+                    } else if (!state.eqValues(*v1->listElems()[i], *v2->listElems()[i])) {
+                        return (*this)(v1->listElems()[i], v2->listElems()[i]);
+                    }
+                }
             default:
                 throw EvalError("cannot compare %1% with %2%", showType(*v1), showType(*v2));
         }
@@ -621,7 +636,8 @@ static void prim_genericClosure(EvalState & state, const Pos & pos, Value * * ar
     ValueList res;
     // `doneKeys' doesn't need to be a GC root, because its values are
     // reachable from res.
-    set<Value *, CompareValues> doneKeys;
+    auto cmp = CompareValues(state);
+    set<Value *, decltype(cmp)> doneKeys(cmp);
     while (!workSet.empty()) {
         Value * e = *(workSet.begin());
         workSet.pop_front();
@@ -2821,7 +2837,7 @@ static void prim_sort(EvalState & state, const Pos & pos, Value * * args, Value
         /* Optimization: if the comparator is lessThan, bypass
            callFunction. */
         if (args[0]->isPrimOp() && args[0]->primOp->fun == prim_lessThan)
-            return CompareValues()(a, b);
+            return CompareValues(state)(a, b);
 
         Value * vs[] = {a, b};
         Value vBool;
@@ -3103,7 +3119,7 @@ static void prim_lessThan(EvalState & state, const Pos & pos, Value * * args, Va
 {
     state.forceValue(*args[0], pos);
     state.forceValue(*args[1], pos);
-    CompareValues comp;
+    CompareValues comp{state};
     mkBool(v, comp(args[0], args[1]));
 }
 
@@ -3693,7 +3709,7 @@ void EvalState::createBaseEnv()
        language feature gets added.  It's not necessary to increase it
        when primops get added, because you can just use `builtins ?
        primOp' to check. */
-    mkInt(v, 5);
+    mkInt(v, 6);
     addConstant("__langVersion", v);
 
     // Miscellaneous
diff --git a/tests/lang/eval-okay-sort.exp b/tests/lang/eval-okay-sort.exp
index 148b93516..899119e20 100644
--- a/tests/lang/eval-okay-sort.exp
+++ b/tests/lang/eval-okay-sort.exp
@@ -1 +1 @@
-[ [ 42 77 147 249 483 526 ] [ 526 483 249 147 77 42 ] [ "bar" "fnord" "foo" "xyzzy" ] [ { key = 1; value = "foo"; } { key = 1; value = "fnord"; } { key = 2; value = "bar"; } ] ]
+[ [ 42 77 147 249 483 526 ] [ 526 483 249 147 77 42 ] [ "bar" "fnord" "foo" "xyzzy" ] [ { key = 1; value = "foo"; } { key = 1; value = "fnord"; } { key = 2; value = "bar"; } ] [ [ ] [ ] [ 1 ] [ 1 4 ] [ 1 5 ] [ 1 6 ] [ 2 ] [ 2 3 ] [ 3 ] [ 3 ] ] ]
diff --git a/tests/lang/eval-okay-sort.nix b/tests/lang/eval-okay-sort.nix
index 8299c3a4a..50aa78e40 100644
--- a/tests/lang/eval-okay-sort.nix
+++ b/tests/lang/eval-okay-sort.nix
@@ -4,5 +4,17 @@ with builtins;
   (sort (x: y: y < x) [ 483 249 526 147 42 77 ])
   (sort lessThan [ "foo" "bar" "xyzzy" "fnord" ])
   (sort (x: y: x.key < y.key)
-    [ { key = 1; value = "foo"; } { key = 2; value = "bar"; } { key = 1; value = "fnord"; } ]) 
+    [ { key = 1; value = "foo"; } { key = 2; value = "bar"; } { key = 1; value = "fnord"; } ])
+  (sort lessThan [
+    [ 1 6 ]
+    [ ]
+    [ 2 3 ]
+    [ 3 ]
+    [ 1 5 ]
+    [ 2 ]
+    [ 1 ]
+    [ ]
+    [ 1 4 ]
+    [ 3 ]
+  ])
 ]

From 884674a8e20789250929a4cc6be3ad5445836e63 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 24 Nov 2021 13:49:07 +0100
Subject: [PATCH 257/567] nix flake check: Fix markdown

---
 src/nix/flake-check.md | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/src/nix/flake-check.md b/src/nix/flake-check.md
index d995d6274..07031c909 100644
--- a/src/nix/flake-check.md
+++ b/src/nix/flake-check.md
@@ -31,38 +31,38 @@ at the first error.
 The following flake output attributes must be derivations:
 
 * `checks.`*system*`.`*name*
-* `defaultPackage.`*system*`
-* `devShell.`*system*`
-* `devShells.`*system*`.`*name*`
-* `nixosConfigurations.`*name*`.config.system.build.toplevel
+* `defaultPackage.`*system*
+* `devShell.`*system*
+* `devShells.`*system*`.`*name*
+* `nixosConfigurations.`*name*`.config.system.build.toplevel`
 * `packages.`*system*`.`*name*
 
 The following flake output attributes must be [app
 definitions](./nix3-run.md):
 
 * `apps.`*system*`.`*name*
-* `defaultApp.`*system*`
+* `defaultApp.`*system*
 
 The following flake output attributes must be [template
 definitions](./nix3-flake-init.md):
 
 * `defaultTemplate`
-* `templates`.`*name*
+* `templates.`*name*
 
 The following flake output attributes must be *Nixpkgs overlays*:
 
 * `overlay`
-* `overlays`.`*name*
+* `overlays.`*name*
 
 The following flake output attributes must be *NixOS modules*:
 
 * `nixosModule`
-* `nixosModules`.`*name*
+* `nixosModules.`*name*
 
 The following flake output attributes must be
 [bundlers](./nix3-bundle.md):
 
-* `bundlers`.`*name*
+* `bundlers.`*name*
 * `defaultBundler`
 
 In addition, the `hydraJobs` output is evaluated in the same way as

From 2970ca18bf36c02860396f83f6c9d1c06414eea5 Mon Sep 17 00:00:00 2001
From: Alex Shabalin <alex.shabalin@tweag.io>
Date: Wed, 24 Nov 2021 14:50:08 +0100
Subject: [PATCH 258/567] Fix a minor data race with _isInterrupted

---
 src/libutil/util.cc | 2 +-
 src/libutil/util.hh | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 5468d1ed1..defb77a10 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1205,7 +1205,7 @@ void closeOnExec(int fd)
 //////////////////////////////////////////////////////////////////////
 
 
-bool _isInterrupted = false;
+std::atomic<bool> _isInterrupted = false;
 
 static thread_local bool interruptThrown = false;
 thread_local std::function<bool()> interruptCheck;
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 708e01cf8..0bdb37a79 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -337,7 +337,7 @@ void closeOnExec(int fd);
 
 /* User interruption. */
 
-extern bool _isInterrupted;
+extern std::atomic<bool> _isInterrupted;
 
 extern thread_local std::function<bool()> interruptCheck;
 

From 8388d2c7c662e37470240cfde798956fe8e36a6f Mon Sep 17 00:00:00 2001
From: Las Safin <me@las.rs>
Date: Fri, 8 Oct 2021 22:55:08 +0000
Subject: [PATCH 259/567] Make recursive-nix work even when not privileged

Before this, `setns` would fail when switching to the mount namespace,
since we did not have the privileges to do so when not root.

Closes #5360
---
 src/libstore/build/local-derivation-goal.cc | 11 +++++++++--
 src/libstore/build/local-derivation-goal.hh |  3 ++-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index c9a4a31e7..ebcb561c2 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -260,6 +260,7 @@ void LocalDerivationGoal::cleanupHookFinally()
 void LocalDerivationGoal::cleanupPreChildKill()
 {
     sandboxMountNamespace = -1;
+    sandboxUserNamespace = -1;
 }
 
 
@@ -906,11 +907,14 @@ void LocalDerivationGoal::startBuilder()
                 "nobody:x:65534:65534:Nobody:/:/noshell\n",
                 sandboxUid(), sandboxGid(), settings.sandboxBuildDir));
 
-        /* Save the mount namespace of the child. We have to do this
+        /* Save the mount- and user namespace of the child. We have to do this
            *before* the child does a chroot. */
         sandboxMountNamespace = open(fmt("/proc/%d/ns/mnt", (pid_t) pid).c_str(), O_RDONLY);
         if (sandboxMountNamespace.get() == -1)
             throw SysError("getting sandbox mount namespace");
+        sandboxUserNamespace = open(fmt("/proc/%d/ns/user", (pid_t) pid).c_str(), O_RDONLY);
+        if (sandboxUserNamespace.get() == -1)
+            throw SysError("getting sandbox user namespace");
 
         /* Signal the builder that we've updated its user namespace. */
         writeFull(userNamespaceSync.writeSide.get(), "1");
@@ -1423,7 +1427,7 @@ void LocalDerivationGoal::addDependency(const StorePath & path)
 
             Path source = worker.store.Store::toRealPath(path);
             Path target = chrootRootDir + worker.store.printStorePath(path);
-            debug("bind-mounting %s -> %s", target, source);
+            debug("bind-mounting %s -> %s", source, target);
 
             if (pathExists(target))
                 throw Error("store path '%s' already exists in the sandbox", worker.store.printStorePath(path));
@@ -1438,6 +1442,9 @@ void LocalDerivationGoal::addDependency(const StorePath & path)
                    child process.*/
                 Pid child(startProcess([&]() {
 
+                    if (usingUserNamespace && (setns(sandboxUserNamespace.get(), 0) == -1))
+                        throw SysError("entering sandbox user namespace");
+
                     if (setns(sandboxMountNamespace.get(), 0) == -1)
                         throw SysError("entering sandbox mount namespace");
 
diff --git a/src/libstore/build/local-derivation-goal.hh b/src/libstore/build/local-derivation-goal.hh
index 088a57209..bfdf91d89 100644
--- a/src/libstore/build/local-derivation-goal.hh
+++ b/src/libstore/build/local-derivation-goal.hh
@@ -27,9 +27,10 @@ struct LocalDerivationGoal : public DerivationGoal
     /* Pipe for synchronising updates to the builder namespaces. */
     Pipe userNamespaceSync;
 
-    /* The mount namespace of the builder, used to add additional
+    /* The mount namespace and user namespace of the builder, used to add additional
        paths to the sandbox as a result of recursive Nix calls. */
     AutoCloseFD sandboxMountNamespace;
+    AutoCloseFD sandboxUserNamespace;
 
     /* On Linux, whether we're doing the build in its own user
        namespace. */

From 329b18711e1e9af32bf050f8afcbc72bb527ab3e Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 25 Nov 2021 14:45:47 +0100
Subject: [PATCH 260/567] flake.nix: Only have checks.*.dockerImage on
 supported systems

---
 flake.nix | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/flake.nix b/flake.nix
index 1b98b526e..ff152ebd6 100644
--- a/flake.nix
+++ b/flake.nix
@@ -524,8 +524,9 @@
         binaryTarball = self.hydraJobs.binaryTarball.${system};
         perlBindings = self.hydraJobs.perlBindings.${system};
         installTests = self.hydraJobs.installTests.${system};
+      } // (if system == "x86_64-linux" then {
         dockerImage = self.hydraJobs.dockerImage.${system};
-      });
+      } else {}));
 
       packages = forAllSystems (system: {
         inherit (nixpkgsFor.${system}) nix;

From c47027f3a139669dfb607c22b153564ff53d111c Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Thu, 25 Nov 2021 14:48:01 +0100
Subject: [PATCH 261/567] Fix the error when accessing a forbidden path in pure
 eval
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

If we’re in pure eval mode, then tell that in the error message rather
than (wrongly) speaking about restricted mode.

Fix https://github.com/NixOS/nix/issues/5611
---
 src/libexpr/eval.cc | 8 ++++++--
 tests/pure-eval.sh  | 5 ++++-
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 97fc04711..1fd609bd4 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -519,8 +519,12 @@ Path EvalState::checkSourcePath(const Path & path_)
         }
     }
 
-    if (!found)
-        throw RestrictedPathError("access to absolute path '%1%' is forbidden in restricted mode", abspath);
+    if (!found) {
+        auto modeInformation = evalSettings.pureEval
+            ? "in pure eval mode (use '--impure' to override)"
+            : "in restricted mode";
+        throw RestrictedPathError("access to absolute path '%1%' is forbidden %2%", abspath, modeInformation);
+    }
 
     /* Resolve symlinks. */
     debug(format("checking access to '%s'") % abspath);
diff --git a/tests/pure-eval.sh b/tests/pure-eval.sh
index c994fbb98..cb4b5c5fc 100644
--- a/tests/pure-eval.sh
+++ b/tests/pure-eval.sh
@@ -6,7 +6,10 @@ nix eval --expr 'assert 1 + 2 == 3; true'
 
 [[ $(nix eval --impure --expr 'builtins.readFile ./pure-eval.sh') =~ clearStore ]]
 
-(! nix eval --expr 'builtins.readFile ./pure-eval.sh')
+missingImpureErrorMsg=$(! nix eval --expr 'builtins.readFile ./pure-eval.sh' 2>&1)
+
+echo "$missingImpureErrorMsg" | grep -q -- --impure || \
+    fail "The error message should mention the “--impure” flag to unblock users"
 
 (! nix eval --expr builtins.currentTime)
 (! nix eval --expr builtins.currentSystem)

From b6c8e57056f81fa3c2827a7fdc6f335ec54727bd Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 24 Nov 2021 20:21:34 +0100
Subject: [PATCH 262/567] Support range-based for loop over list values

---
 src/libexpr/eval.cc            | 18 ++++----
 src/libexpr/flake/flake.cc     |  3 +-
 src/libexpr/get-drvs.cc        | 22 ++++-----
 src/libexpr/primops.cc         | 82 ++++++++++++++++------------------
 src/libexpr/primops/context.cc |  7 ++-
 src/libexpr/value-to-json.cc   |  4 +-
 src/libexpr/value-to-xml.cc    |  4 +-
 src/libexpr/value.hh           | 30 +++++++++++++
 src/nix-env/nix-env.cc         |  6 +--
 src/nix/repl.cc                |  6 +--
 10 files changed, 103 insertions(+), 79 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 97fc04711..5adac87cd 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -119,8 +119,8 @@ void printValue(std::ostream & str, std::set<const Value *> & active, const Valu
     case tList2:
     case tListN:
         str << "[ ";
-        for (unsigned int n = 0; n < v.listSize(); ++n) {
-            printValue(str, active, *v.listElems()[n]);
+        for (auto v2 : v.listItems()) {
+            printValue(str, active, *v2);
             str << " ";
         }
         str << "]";
@@ -1151,8 +1151,8 @@ void ExprLet::eval(EvalState & state, Env & env, Value & v)
 void ExprList::eval(EvalState & state, Env & env, Value & v)
 {
     state.mkList(v, elems.size());
-    for (size_t n = 0; n < elems.size(); ++n)
-        v.listElems()[n] = elems[n]->maybeThunk(state, env);
+    for (auto [n, v2] : enumerate(v.listItems()))
+        const_cast<Value * &>(v2) = elems[n]->maybeThunk(state, env);
 }
 
 
@@ -1732,8 +1732,8 @@ void EvalState::forceValueDeep(Value & v)
         }
 
         else if (v.isList()) {
-            for (size_t n = 0; n < v.listSize(); ++n)
-                recurse(*v.listElems()[n]);
+            for (auto v2 : v.listItems())
+                recurse(*v2);
         }
     };
 
@@ -1917,12 +1917,12 @@ string EvalState::coerceToString(const Pos & pos, Value & v, PathSet & context,
 
         if (v.isList()) {
             string result;
-            for (size_t n = 0; n < v.listSize(); ++n) {
-                result += coerceToString(pos, *v.listElems()[n],
+            for (auto [n, v2] : enumerate(v.listItems())) {
+                result += coerceToString(pos, *v2,
                     context, coerceMore, copyToStore);
                 if (n < v.listSize() - 1
                     /* !!! not quite correct */
-                    && (!v.listElems()[n]->isList() || v.listElems()[n]->listSize() != 0))
+                    && (!v2->isList() || v2->listSize() != 0))
                     result += " ";
             }
             return result;
diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index f5be67d67..06136579e 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -257,8 +257,7 @@ static Flake getFlake(
                 flake.config.settings.insert({setting.name, state.forceBool(*setting.value, *setting.pos)});
             else if (setting.value->type() == nList) {
                 std::vector<std::string> ss;
-                for (unsigned int n = 0; n < setting.value->listSize(); ++n) {
-                    auto elem = setting.value->listElems()[n];
+                for (auto elem : setting.value->listItems()) {
                     if (elem->type() != nString)
                         throw TypeError("list element in flake configuration setting '%s' is %s while a string is expected",
                             setting.name, showType(*setting.value));
diff --git a/src/libexpr/get-drvs.cc b/src/libexpr/get-drvs.cc
index f774e6493..ed4c47fbb 100644
--- a/src/libexpr/get-drvs.cc
+++ b/src/libexpr/get-drvs.cc
@@ -102,9 +102,9 @@ DrvInfo::Outputs DrvInfo::queryOutputs(bool onlyOutputsToInstall)
             state->forceList(*i->value, *i->pos);
 
             /* For each output... */
-            for (unsigned int j = 0; j < i->value->listSize(); ++j) {
+            for (auto elem : i->value->listItems()) {
                 /* Evaluate the corresponding set. */
-                string name = state->forceStringNoCtx(*i->value->listElems()[j], *i->pos);
+                string name = state->forceStringNoCtx(*elem, *i->pos);
                 Bindings::iterator out = attrs->find(state->symbols.create(name));
                 if (out == attrs->end()) continue; // FIXME: throw error?
                 state->forceAttrs(*out->value);
@@ -128,9 +128,9 @@ DrvInfo::Outputs DrvInfo::queryOutputs(bool onlyOutputsToInstall)
         /* ^ this shows during `nix-env -i` right under the bad derivation */
     if (!outTI->isList()) throw errMsg;
     Outputs result;
-    for (auto i = outTI->listElems(); i != outTI->listElems() + outTI->listSize(); ++i) {
-        if ((*i)->type() != nString) throw errMsg;
-        auto out = outputs.find((*i)->string.s);
+    for (auto elem : outTI->listItems()) {
+        if (elem->type() != nString) throw errMsg;
+        auto out = outputs.find(elem->string.s);
         if (out == outputs.end()) throw errMsg;
         result.insert(*out);
     }
@@ -174,8 +174,8 @@ bool DrvInfo::checkMeta(Value & v)
 {
     state->forceValue(v);
     if (v.type() == nList) {
-        for (unsigned int n = 0; n < v.listSize(); ++n)
-            if (!checkMeta(*v.listElems()[n])) return false;
+        for (auto elem : v.listItems())
+            if (!checkMeta(*elem)) return false;
         return true;
     }
     else if (v.type() == nAttrs) {
@@ -364,10 +364,10 @@ static void getDerivations(EvalState & state, Value & vIn,
     }
 
     else if (v.type() == nList) {
-        for (unsigned int n = 0; n < v.listSize(); ++n) {
-            string pathPrefix2 = addToPath(pathPrefix, (format("%1%") % n).str());
-            if (getDerivation(state, *v.listElems()[n], pathPrefix2, drvs, done, ignoreAssertionFailures))
-                getDerivations(state, *v.listElems()[n], pathPrefix2, autoArgs, drvs, done, ignoreAssertionFailures);
+        for (auto [n, elem] : enumerate(v.listItems())) {
+            string pathPrefix2 = addToPath(pathPrefix, fmt("%d", n));
+            if (getDerivation(state, *elem, pathPrefix2, drvs, done, ignoreAssertionFailures))
+                getDerivations(state, *elem, pathPrefix2, autoArgs, drvs, done, ignoreAssertionFailures);
         }
     }
 
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 8cbeaa520..c0d59da8c 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -335,9 +335,8 @@ void prim_exec(EvalState & state, const Pos & pos, Value * * args, Value & v)
     PathSet context;
     auto program = state.coerceToString(pos, *elems[0], context, false, false);
     Strings commandArgs;
-    for (unsigned int i = 1; i < args[0]->listSize(); ++i) {
+    for (unsigned int i = 1; i < args[0]->listSize(); ++i)
         commandArgs.emplace_back(state.coerceToString(pos, *elems[i], context, false, false));
-    }
     try {
         state.realiseContext(context);
     } catch (InvalidPathError & e) {
@@ -616,8 +615,8 @@ static void prim_genericClosure(EvalState & state, const Pos & pos, Value * * ar
     state.forceList(*startSet->value, pos);
 
     ValueList workSet;
-    for (unsigned int n = 0; n < startSet->value->listSize(); ++n)
-        workSet.push_back(startSet->value->listElems()[n]);
+    for (auto elem : startSet->value->listItems())
+        workSet.push_back(elem);
 
     /* Get the operator. */
     Bindings::iterator op = getAttr(
@@ -662,9 +661,9 @@ static void prim_genericClosure(EvalState & state, const Pos & pos, Value * * ar
         state.forceList(call, pos);
 
         /* Add the values returned by the operator to the work set. */
-        for (unsigned int n = 0; n < call.listSize(); ++n) {
-            state.forceValue(*call.listElems()[n], pos);
-            workSet.push_back(call.listElems()[n]);
+        for (auto elem : call.listItems()) {
+            state.forceValue(*elem, pos);
+            workSet.push_back(elem);
         }
     }
 
@@ -1013,8 +1012,8 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
                command-line arguments to the builder. */
             else if (i->name == state.sArgs) {
                 state.forceList(*i->value, pos);
-                for (unsigned int n = 0; n < i->value->listSize(); ++n) {
-                    string s = state.coerceToString(posDrvName, *i->value->listElems()[n], context, true);
+                for (auto elem : i->value->listItems()) {
+                    string s = state.coerceToString(posDrvName, *elem, context, true);
                     drv.args.push_back(s);
                 }
             }
@@ -1044,8 +1043,8 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
                         /* Require ‘outputs’ to be a list of strings. */
                         state.forceList(*i->value, posDrvName);
                         Strings ss;
-                        for (unsigned int n = 0; n < i->value->listSize(); ++n)
-                            ss.emplace_back(state.forceStringNoCtx(*i->value->listElems()[n], posDrvName));
+                        for (auto elem : i->value->listItems())
+                            ss.emplace_back(state.forceStringNoCtx(*elem, posDrvName));
                         handleOutputs(ss);
                     }
 
@@ -1460,20 +1459,19 @@ static void prim_findFile(EvalState & state, const Pos & pos, Value * * args, Va
 
     SearchPath searchPath;
 
-    for (unsigned int n = 0; n < args[0]->listSize(); ++n) {
-        Value & v2(*args[0]->listElems()[n]);
-        state.forceAttrs(v2, pos);
+    for (auto v2 : args[0]->listItems()) {
+        state.forceAttrs(*v2, pos);
 
         string prefix;
-        Bindings::iterator i = v2.attrs->find(state.symbols.create("prefix"));
-        if (i != v2.attrs->end())
+        Bindings::iterator i = v2->attrs->find(state.symbols.create("prefix"));
+        if (i != v2->attrs->end())
             prefix = state.forceStringNoCtx(*i->value, pos);
 
         i = getAttr(
             state,
             "findFile",
             "path",
-            v2.attrs,
+            v2->attrs,
             pos
         );
 
@@ -2239,9 +2237,9 @@ static void prim_removeAttrs(EvalState & state, const Pos & pos, Value * * args,
 
     /* Get the attribute names to be removed. */
     std::set<Symbol> names;
-    for (unsigned int i = 0; i < args[1]->listSize(); ++i) {
-        state.forceStringNoCtx(*args[1]->listElems()[i], pos);
-        names.insert(state.symbols.create(args[1]->listElems()[i]->string.s));
+    for (auto elem : args[1]->listItems()) {
+        state.forceStringNoCtx(*elem, pos);
+        names.insert(state.symbols.create(elem->string.s));
     }
 
     /* Copy all attributes not in that set.  Note that we don't need
@@ -2249,7 +2247,7 @@ static void prim_removeAttrs(EvalState & state, const Pos & pos, Value * * args,
        vector. */
     state.mkAttrs(v, args[0]->attrs->size());
     for (auto & i : *args[0]->attrs) {
-        if (names.find(i.name) == names.end())
+        if (!names.count(i.name))
             v.attrs->push_back(i);
     }
 }
@@ -2283,15 +2281,14 @@ static void prim_listToAttrs(EvalState & state, const Pos & pos, Value * * args,
 
     std::set<Symbol> seen;
 
-    for (unsigned int i = 0; i < args[0]->listSize(); ++i) {
-        Value & v2(*args[0]->listElems()[i]);
-        state.forceAttrs(v2, pos);
+    for (auto v2 : args[0]->listItems()) {
+        state.forceAttrs(*v2, pos);
 
         Bindings::iterator j = getAttr(
             state,
             "listToAttrs",
             state.sName,
-            v2.attrs,
+            v2->attrs,
             pos
         );
 
@@ -2303,7 +2300,7 @@ static void prim_listToAttrs(EvalState & state, const Pos & pos, Value * * args,
                 state,
                 "listToAttrs",
                 state.sValue,
-                v2.attrs,
+                v2->attrs,
                 pos
             );
             v.attrs->push_back(Attr(sym, j2->value, j2->pos));
@@ -2370,11 +2367,10 @@ static void prim_catAttrs(EvalState & state, const Pos & pos, Value * * args, Va
     Value * res[args[1]->listSize()];
     unsigned int found = 0;
 
-    for (unsigned int n = 0; n < args[1]->listSize(); ++n) {
-        Value & v2(*args[1]->listElems()[n]);
-        state.forceAttrs(v2, pos);
-        Bindings::iterator i = v2.attrs->find(attrName);
-        if (i != v2.attrs->end())
+    for (auto v2 : args[1]->listItems()) {
+        state.forceAttrs(*v2, pos);
+        Bindings::iterator i = v2->attrs->find(attrName);
+        if (i != v2->attrs->end())
             res[found++] = i->value;
     }
 
@@ -2649,8 +2645,8 @@ static void prim_elem(EvalState & state, const Pos & pos, Value * * args, Value
 {
     bool res = false;
     state.forceList(*args[1], pos);
-    for (unsigned int n = 0; n < args[1]->listSize(); ++n)
-        if (state.eqValues(*args[0], *args[1]->listElems()[n])) {
+    for (auto elem : args[1]->listItems())
+        if (state.eqValues(*args[0], *elem)) {
             res = true;
             break;
         }
@@ -2709,8 +2705,8 @@ static void prim_foldlStrict(EvalState & state, const Pos & pos, Value * * args,
     if (args[2]->listSize()) {
         Value * vCur = args[1];
 
-        for (unsigned int n = 0; n < args[2]->listSize(); ++n) {
-            Value * vs []{vCur, args[2]->listElems()[n]};
+        for (auto [n, elem] : enumerate(args[2]->listItems())) {
+            Value * vs []{vCur, elem};
             vCur = n == args[2]->listSize() - 1 ? &v : state.allocValue();
             state.callFunction(*args[0], 2, vs, *vCur, pos);
         }
@@ -2740,8 +2736,8 @@ static void anyOrAll(bool any, EvalState & state, const Pos & pos, Value * * arg
     state.forceList(*args[1], pos);
 
     Value vTmp;
-    for (unsigned int n = 0; n < args[1]->listSize(); ++n) {
-        state.callFunction(*args[0], *args[1]->listElems()[n], vTmp, pos);
+    for (auto elem : args[1]->listItems()) {
+        state.callFunction(*args[0], *elem, vTmp, pos);
         bool res = state.forceBool(vTmp, pos);
         if (res == any) {
             mkBool(v, any);
@@ -3470,9 +3466,9 @@ static void prim_concatStringsSep(EvalState & state, const Pos & pos, Value * *
     res.reserve((args[1]->listSize() + 32) * sep.size());
     bool first = true;
 
-    for (unsigned int n = 0; n < args[1]->listSize(); ++n) {
+    for (auto elem : args[1]->listItems()) {
         if (first) first = false; else res += sep;
-        res += state.coerceToString(pos, *args[1]->listElems()[n], context);
+        res += state.coerceToString(pos, *elem, context);
     }
 
     mkString(v, res, context);
@@ -3501,14 +3497,14 @@ static void prim_replaceStrings(EvalState & state, const Pos & pos, Value * * ar
 
     vector<string> from;
     from.reserve(args[0]->listSize());
-    for (unsigned int n = 0; n < args[0]->listSize(); ++n)
-        from.push_back(state.forceString(*args[0]->listElems()[n], pos));
+    for (auto elem : args[0]->listItems())
+        from.push_back(state.forceString(*elem, pos));
 
     vector<std::pair<string, PathSet>> to;
     to.reserve(args[1]->listSize());
-    for (unsigned int n = 0; n < args[1]->listSize(); ++n) {
+    for (auto elem : args[1]->listItems()) {
         PathSet ctx;
-        auto s = state.forceString(*args[1]->listElems()[n], ctx, pos);
+        auto s = state.forceString(*elem, ctx, pos);
         to.push_back(std::make_pair(std::move(s), std::move(ctx)));
     }
 
diff --git a/src/libexpr/primops/context.cc b/src/libexpr/primops/context.cc
index 31cf812b4..20545afd0 100644
--- a/src/libexpr/primops/context.cc
+++ b/src/libexpr/primops/context.cc
@@ -118,9 +118,8 @@ static void prim_getContext(EvalState & state, const Pos & pos, Value * * args,
             auto & outputsVal = *state.allocAttr(infoVal, state.sOutputs);
             state.mkList(outputsVal, info.second.outputs.size());
             size_t i = 0;
-            for (const auto & output : info.second.outputs) {
+            for (const auto & output : info.second.outputs)
                 mkString(*(outputsVal.listElems()[i++] = state.allocValue()), output);
-            }
         }
         infoVal.attrs->sort();
     }
@@ -181,8 +180,8 @@ static void prim_appendContext(EvalState & state, const Pos & pos, Value * * arg
                     .errPos = *i.pos
                 });
             }
-            for (unsigned int n = 0; n < iter->value->listSize(); ++n) {
-                auto name = state.forceStringNoCtx(*iter->value->listElems()[n], *iter->pos);
+            for (auto elem : iter->value->listItems()) {
+                auto name = state.forceStringNoCtx(*elem, *iter->pos);
                 context.insert("!" + name + "!" + string(i.name));
             }
         }
diff --git a/src/libexpr/value-to-json.cc b/src/libexpr/value-to-json.cc
index 4d642c720..517da4c01 100644
--- a/src/libexpr/value-to-json.cc
+++ b/src/libexpr/value-to-json.cc
@@ -63,9 +63,9 @@ void printValueAsJSON(EvalState & state, bool strict,
 
         case nList: {
             auto list(out.list());
-            for (unsigned int n = 0; n < v.listSize(); ++n) {
+            for (auto elem : v.listItems()) {
                 auto placeholder(list.placeholder());
-                printValueAsJSON(state, strict, *v.listElems()[n], pos, placeholder, context);
+                printValueAsJSON(state, strict, *elem, pos, placeholder, context);
             }
             break;
         }
diff --git a/src/libexpr/value-to-xml.cc b/src/libexpr/value-to-xml.cc
index 54268ece0..a875f82d7 100644
--- a/src/libexpr/value-to-xml.cc
+++ b/src/libexpr/value-to-xml.cc
@@ -122,8 +122,8 @@ static void printValueAsXML(EvalState & state, bool strict, bool location,
 
         case nList: {
             XMLOpenElement _(doc, "list");
-            for (unsigned int n = 0; n < v.listSize(); ++n)
-                printValueAsXML(state, strict, location, *v.listElems()[n], doc, context, drvsSeen, pos);
+            for (auto v2 : v.listItems())
+                printValueAsXML(state, strict, location, *v2, doc, context, drvsSeen, pos);
             break;
         }
 
diff --git a/src/libexpr/value.hh b/src/libexpr/value.hh
index 3bb97b3c2..4b43e47ae 100644
--- a/src/libexpr/value.hh
+++ b/src/libexpr/value.hh
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <cassert>
+
 #include "symbol-table.hh"
 
 #if HAVE_BOEHMGC
@@ -350,6 +352,34 @@ public:
     bool isTrivial() const;
 
     std::vector<std::pair<Path, std::string>> getContext();
+
+    auto listItems()
+    {
+        struct ListIterable
+        {
+            typedef Value * const * iterator;
+            iterator _begin, _end;
+            iterator begin() const { return _begin; }
+            iterator end() const { return _end; }
+        };
+        assert(isList());
+        auto begin = listElems();
+        return ListIterable { begin, begin + listSize() };
+    }
+
+    auto listItems() const
+    {
+        struct ConstListIterable
+        {
+            typedef const Value * const * iterator;
+            iterator _begin, _end;
+            iterator begin() const { return _begin; }
+            iterator end() const { return _end; }
+        };
+        assert(isList());
+        auto begin = listElems();
+        return ConstListIterable { begin, begin + listSize() };
+    }
 };
 
 
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index 4056d973d..0dd0e34a0 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -1149,10 +1149,10 @@ static void opQuery(Globals & globals, Strings opFlags, Strings opArgs)
                                 } else if (v->type() == nList) {
                                     attrs2["type"] = "strings";
                                     XMLOpenElement m(xml, "meta", attrs2);
-                                    for (unsigned int j = 0; j < v->listSize(); ++j) {
-                                        if (v->listElems()[j]->type() != nString) continue;
+                                    for (auto elem : v->listItems()) {
+                                        if (elem->type() != nString) continue;
                                         XMLAttrs attrs3;
-                                        attrs3["value"] = v->listElems()[j]->string.s;
+                                        attrs3["value"] = elem->string.s;
                                         xml.writeEmptyElement("string", attrs3);
                                     }
                               } else if (v->type() == nAttrs) {
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index fd86174f2..41283c5f2 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -771,12 +771,12 @@ std::ostream & NixRepl::printValue(std::ostream & str, Value & v, unsigned int m
 
         str << "[ ";
         if (maxDepth > 0)
-            for (unsigned int n = 0; n < v.listSize(); ++n) {
-                if (seen.find(v.listElems()[n]) != seen.end())
+            for (auto elem : v.listItems()) {
+                if (seen.count(elem))
                     str << "«repeated»";
                 else
                     try {
-                        printValue(str, *v.listElems()[n], maxDepth - 1, seen);
+                        printValue(str, *elem, maxDepth - 1, seen);
                     } catch (AssertionError & e) {
                         str << ANSI_RED "«error: " << e.msg() << "»" ANSI_NORMAL;
                     }

From 986906e687cc4d3b456592f72a0081c4a9adb1db Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 25 Nov 2021 17:04:31 +0100
Subject: [PATCH 263/567] Update names

---
 doc/manual/src/release-notes/rl-2.4.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/doc/manual/src/release-notes/rl-2.4.md b/doc/manual/src/release-notes/rl-2.4.md
index 70b715053..0f632f100 100644
--- a/doc/manual/src/release-notes/rl-2.4.md
+++ b/doc/manual/src/release-notes/rl-2.4.md
@@ -395,6 +395,7 @@ dramforever,
 Dustin DeWeese,
 edef,
 Eelco Dolstra,
+Ellie Hermaszewska,
 Emilio Karakey,
 Emily,
 Eric Culp,
@@ -405,7 +406,7 @@ Federico Pellegrin,
 Finn Behrens,
 Florian Franzen,
 Félix Baylac-Jacqué,
-Gabriel Gonzalez,
+Gabriella Gonzalez,
 Geoff Reedy,
 Georges Dubus,
 Graham Christensen,
@@ -428,7 +429,6 @@ Jaroslavas Pocepko,
 Jarrett Keifer,
 Jeremy Schlatter,
 Joachim Breitner,
-Joe Hermaszewski,
 Joe Pea,
 John Ericson,
 Jonathan Ringer,

From 05081bedc156c8e6556b66fe2470fec14e074caf Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Fri, 26 Nov 2021 09:56:48 +0100
Subject: [PATCH 264/567] Make `nix-shell` work when nixpkgs is
 content-addressed

Fix #5259
---
 src/nix-build/nix-build.cc |  9 ++++++--
 tests/ca-shell.nix         |  1 +
 tests/nix-shell.sh         | 42 ++++++++++++++++----------------------
 tests/shell.nix            |  4 ++++
 4 files changed, 30 insertions(+), 26 deletions(-)
 create mode 100644 tests/ca-shell.nix

diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index 75576ef8a..e2325c91f 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -359,6 +359,7 @@ static void main_nix_build(int argc, char * * argv)
            is not set, then build bashInteractive from
            <nixpkgs>. */
         auto shell = getEnv("NIX_BUILD_SHELL");
+        std::optional<StorePath> shellDrv;
 
         if (!shell) {
 
@@ -375,8 +376,7 @@ static void main_nix_build(int argc, char * * argv)
                 auto bashDrv = store->parseStorePath(drv->queryDrvPath());
                 pathsToBuild.push_back({bashDrv});
                 pathsToCopy.insert(bashDrv);
-
-                shell = drv->queryOutPath() + "/bin/bash";
+                shellDrv = bashDrv;
 
             } catch (Error & e) {
                 logError(e.info());
@@ -402,6 +402,11 @@ static void main_nix_build(int argc, char * * argv)
 
         if (dryRun) return;
 
+        if (shellDrv) {
+            auto shellDrvOutputs = store->queryPartialDerivationOutputMap(shellDrv.value());
+            shell = store->printStorePath(shellDrvOutputs.at("out").value()) + "/bin/bash";
+        }
+
         if (settings.isExperimentalFeatureEnabled(Xp::CaDerivations)) {
             auto resolvedDrv = drv.tryResolve(*store);
             assert(resolvedDrv && "Successfully resolved the derivation");
diff --git a/tests/ca-shell.nix b/tests/ca-shell.nix
new file mode 100644
index 000000000..ad2ab6aff
--- /dev/null
+++ b/tests/ca-shell.nix
@@ -0,0 +1 @@
+{ ... }@args: import ./shell.nix (args // { contentAddressed = true; })
diff --git a/tests/nix-shell.sh b/tests/nix-shell.sh
index a31d35887..3241d7a0f 100644
--- a/tests/nix-shell.sh
+++ b/tests/nix-shell.sh
@@ -3,59 +3,53 @@ source common.sh
 clearStore
 
 if [[ -n ${CONTENT_ADDRESSED:-} ]]; then
-    nix-shell () {
-        command nix-shell --arg contentAddressed true "$@"
-    }
-
-    nix_develop() {
-        nix develop --arg contentAddressed true "$@"
-    }
+    shellDotNix="$PWD/ca-shell.nix"
 else
-    nix_develop() {
-        nix develop "$@"
-    }
+    shellDotNix="$PWD/shell.nix"
 fi
 
+export NIX_PATH=nixpkgs="$shellDotNix"
+
 # Test nix-shell -A
 export IMPURE_VAR=foo
 export SELECTED_IMPURE_VAR=baz
-export NIX_BUILD_SHELL=$SHELL
-output=$(nix-shell --pure shell.nix -A shellDrv --run \
+
+output=$(nix-shell --pure "$shellDotNix" -A shellDrv --run \
     'echo "$IMPURE_VAR - $VAR_FROM_STDENV_SETUP - $VAR_FROM_NIX - $TEST_inNixShell"')
 
 [ "$output" = " - foo - bar - true" ]
 
 # Test --keep
-output=$(nix-shell --pure --keep SELECTED_IMPURE_VAR shell.nix -A shellDrv --run \
+output=$(nix-shell --pure --keep SELECTED_IMPURE_VAR "$shellDotNix" -A shellDrv --run \
     'echo "$IMPURE_VAR - $VAR_FROM_STDENV_SETUP - $VAR_FROM_NIX - $SELECTED_IMPURE_VAR"')
 
 [ "$output" = " - foo - bar - baz" ]
 
 # Test nix-shell on a .drv
-[[ $(nix-shell --pure $(nix-instantiate shell.nix -A shellDrv) --run \
+[[ $(nix-shell --pure $(nix-instantiate "$shellDotNix" -A shellDrv) --run \
     'echo "$IMPURE_VAR - $VAR_FROM_STDENV_SETUP - $VAR_FROM_NIX - $TEST_inNixShell"') = " - foo - bar - false" ]]
 
-[[ $(nix-shell --pure $(nix-instantiate shell.nix -A shellDrv) --run \
+[[ $(nix-shell --pure $(nix-instantiate "$shellDotNix" -A shellDrv) --run \
     'echo "$IMPURE_VAR - $VAR_FROM_STDENV_SETUP - $VAR_FROM_NIX - $TEST_inNixShell"') = " - foo - bar - false" ]]
 
 # Test nix-shell on a .drv symlink
 
 # Legacy: absolute path and .drv extension required
-nix-instantiate shell.nix -A shellDrv --add-root $TEST_ROOT/shell.drv
+nix-instantiate "$shellDotNix" -A shellDrv --add-root $TEST_ROOT/shell.drv
 [[ $(nix-shell --pure $TEST_ROOT/shell.drv --run \
     'echo "$IMPURE_VAR - $VAR_FROM_STDENV_SETUP - $VAR_FROM_NIX"') = " - foo - bar" ]]
 
 # New behaviour: just needs to resolve to a derivation in the store
-nix-instantiate shell.nix -A shellDrv --add-root $TEST_ROOT/shell
+nix-instantiate "$shellDotNix" -A shellDrv --add-root $TEST_ROOT/shell
 [[ $(nix-shell --pure $TEST_ROOT/shell --run \
     'echo "$IMPURE_VAR - $VAR_FROM_STDENV_SETUP - $VAR_FROM_NIX"') = " - foo - bar" ]]
 
 # Test nix-shell -p
-output=$(NIX_PATH=nixpkgs=shell.nix nix-shell --pure -p foo bar --run 'echo "$(foo) $(bar)"')
+output=$(NIX_PATH=nixpkgs="$shellDotNix" nix-shell --pure -p foo bar --run 'echo "$(foo) $(bar)"')
 [ "$output" = "foo bar" ]
 
 # Test nix-shell -p --arg x y
-output=$(NIX_PATH=nixpkgs=shell.nix nix-shell --pure -p foo --argstr fooContents baz --run 'echo "$(foo)"')
+output=$(NIX_PATH=nixpkgs="$shellDotNix" nix-shell --pure -p foo --argstr fooContents baz --run 'echo "$(foo)"')
 [ "$output" = "baz" ]
 
 # Test nix-shell shebang mode
@@ -91,18 +85,18 @@ output=$($TEST_ROOT/spaced\ \\\'\"shell.shebang.rb abc ruby)
 [ "$output" = '-e load(ARGV.shift) -- '"$TEST_ROOT"'/spaced \'\''"shell.shebang.rb abc ruby' ]
 
 # Test 'nix develop'.
-nix_develop -f shell.nix shellDrv -c bash -c '[[ -n $stdenv ]]'
+nix develop -f "$shellDotNix" shellDrv -c bash -c '[[ -n $stdenv ]]'
 
 # Ensure `nix develop -c` preserves stdin
-echo foo | nix develop -f shell.nix shellDrv -c cat | grep -q foo
+echo foo | nix develop -f "$shellDotNix" shellDrv -c cat | grep -q foo
 
 # Ensure `nix develop -c` actually executes the command if stdout isn't a terminal
-nix_develop -f shell.nix shellDrv -c echo foo |& grep -q foo
+nix develop -f "$shellDotNix" shellDrv -c echo foo |& grep -q foo
 
 # Test 'nix print-dev-env'.
-[[ $(nix print-dev-env -f shell.nix shellDrv --json | jq -r .variables.arr1.value[2]) = '3 4' ]]
+[[ $(nix print-dev-env -f "$shellDotNix" shellDrv --json | jq -r .variables.arr1.value[2]) = '3 4' ]]
 
-source <(nix print-dev-env -f shell.nix shellDrv)
+source <(nix print-dev-env -f "$shellDotNix" shellDrv)
 [[ -n $stdenv ]]
 [[ ${arr1[2]} = "3 4" ]]
 [[ ${arr2[1]} = $'\n' ]]
diff --git a/tests/shell.nix b/tests/shell.nix
index 4912d295a..92d94fbc2 100644
--- a/tests/shell.nix
+++ b/tests/shell.nix
@@ -74,6 +74,10 @@ let pkgs = rec {
   '';
 
   bash = shell;
+  bashInteractive = runCommand "bash" {} ''
+    mkdir -p $out/bin
+    ln -s ${shell} $out/bin/bash
+  '';
 
   # ruby "interpreter" that outputs "$@"
   ruby = runCommand "ruby" {} ''

From e588f4c6558cb486aa065e17a124f272ccc1fcdb Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Thu, 8 Jul 2021 17:01:51 +0200
Subject: [PATCH 265/567] Add a matrix of stdenvs to the flake

For a (currently hardcoded and limited) list of stdenvs,
make `.#$nix-${stdenvName}` correspond to a Nix built with the
corresponding stdenv.

For example, `.#nix-${clang11Stdenv}` is Nix built with clang11.

Likewise, `devShells.x86_64-linux.clang11StdenvPackages` is a development
shell for Nix with clang11, that can be used with

```shell
nix develop .#clang11StdenvPackages
```

Fix #4129

/cc @pamplemousse
---
 flake.nix | 80 ++++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 55 insertions(+), 25 deletions(-)

diff --git a/flake.nix b/flake.nix
index ff152ebd6..9a5d188ae 100644
--- a/flake.nix
+++ b/flake.nix
@@ -22,15 +22,36 @@
 
       crossSystems = [ "armv6l-linux" "armv7l-linux" ];
 
+      stdenvs = [ "gccStdenv" "clangStdenv" "clang11Stdenv" "stdenv" ];
+
       forAllSystems = f: nixpkgs.lib.genAttrs systems (system: f system);
+      forAllSystemsAndStdenvs = f: forAllSystems (system:
+        nixpkgs.lib.listToAttrs
+          (map
+            (n:
+            nixpkgs.lib.nameValuePair "${n}Packages" (
+              f system n
+            )) stdenvs
+          )
+      );
+
+      forAllStdenvs = stdenvs: f: nixpkgs.lib.genAttrs stdenvs (stdenv: f stdenv);
 
       # Memoize nixpkgs for different platforms for efficiency.
-      nixpkgsFor = forAllSystems (system:
-        import nixpkgs {
-          inherit system;
-          overlays = [ self.overlay ];
-        }
-      );
+      nixpkgsFor =
+        let stdenvsPackages = forAllSystemsAndStdenvs
+          (system: stdenv:
+            import nixpkgs {
+              inherit system;
+              overlays = [
+                (overlayFor (p: p.${stdenv}))
+              ];
+            }
+          );
+        in
+        # Add the `stdenvPackages` at toplevel, both because these are the ones
+        # we want most of the time and for backwards compatibility
+        forAllSystems (system: stdenvsPackages.${system} // stdenvsPackages.${system}.stdenvPackages);
 
       commonDeps = pkgs: with pkgs; rec {
         # Use "busybox-sandbox-shell" if present,
@@ -255,18 +276,15 @@
             $(cat ${installerClosureInfo}/store-paths)
         '';
 
-    in {
-
-      # A Nixpkgs overlay that overrides the 'nix' and
-      # 'nix.perl-bindings' packages.
-      overlay = final: prev: {
-
+      overlayFor = getStdenv: final: prev:
+      let currentStdenv = getStdenv final; in
+      {
         nixStable = prev.nix;
 
         # Forward from the previous stage as we don’t want it to pick the lowdown override
         nixUnstable = prev.nixUnstable;
 
-        nix = with final; with commonDeps pkgs; stdenv.mkDerivation {
+        nix = with final; with commonDeps pkgs; currentStdenv.mkDerivation {
           name = "nix-${version}";
           inherit version;
 
@@ -288,9 +306,9 @@
               mkdir -p $out/lib
               cp -pd ${boost}/lib/{libboost_context*,libboost_thread*,libboost_system*} $out/lib
               rm -f $out/lib/*.a
-              ${lib.optionalString stdenv.isLinux ''
+              ${lib.optionalString currentStdenv.isLinux ''
                 chmod u+w $out/lib/*.so.*
-                patchelf --set-rpath $out/lib:${stdenv.cc.cc.lib}/lib $out/lib/libboost_thread.so.*
+                patchelf --set-rpath $out/lib:${currentStdenv.cc.cc.lib}/lib $out/lib/libboost_thread.so.*
               ''}
             '';
 
@@ -317,7 +335,7 @@
 
           strictDeps = true;
 
-          passthru.perl-bindings = with final; stdenv.mkDerivation {
+          passthru.perl-bindings = with final; currentStdenv.mkDerivation {
             name = "nix-perl-${version}";
 
             src = self;
@@ -336,8 +354,8 @@
                 pkgs.perl
                 boost
               ]
-              ++ lib.optional (stdenv.isLinux || stdenv.isDarwin) libsodium
-              ++ lib.optional stdenv.isDarwin darwin.apple_sdk.frameworks.Security;
+              ++ lib.optional (currentStdenv.isLinux || currentStdenv.isDarwin) libsodium
+              ++ lib.optional currentStdenv.isDarwin darwin.apple_sdk.frameworks.Security;
 
             configureFlags = ''
               --with-dbi=${perlPackages.DBI}/${pkgs.perl.libPrefix}
@@ -351,7 +369,7 @@
 
         };
 
-        lowdown-nix = with final; stdenv.mkDerivation rec {
+        lowdown-nix = with final; currentStdenv.mkDerivation rec {
           name = "lowdown-0.9.0";
 
           src = lowdown-src;
@@ -361,15 +379,20 @@
           nativeBuildInputs = [ buildPackages.which ];
 
           configurePhase = ''
-              ${if (stdenv.isDarwin && stdenv.isAarch64) then "echo \"HAVE_SANDBOX_INIT=false\" > configure.local" else ""}
+              ${if (currentStdenv.isDarwin && currentStdenv.isAarch64) then "echo \"HAVE_SANDBOX_INIT=false\" > configure.local" else ""}
               ./configure \
                 PREFIX=${placeholder "dev"} \
                 BINDIR=${placeholder "bin"}/bin
-            '';
+          '';
         };
-
       };
 
+    in {
+
+      # A Nixpkgs overlay that overrides the 'nix' and
+      # 'nix.perl-bindings' packages.
+      overlay = overlayFor (p: p.stdenv);
+
       hydraJobs = {
 
         # Binary package for various platforms.
@@ -610,15 +633,22 @@
           doInstallCheck = true;
           installCheckFlags = "sysconfdir=$(out)/etc";
         };
-      }) crossSystems)));
+      }) crossSystems)) // (builtins.listToAttrs (map (stdenvName:
+      nixpkgsFor.${system}.lib.nameValuePair
+        "nix-${stdenvName}"
+        nixpkgsFor.${system}."${stdenvName}Packages".nix
+      ) stdenvs))
+      );
 
       defaultPackage = forAllSystems (system: self.packages.${system}.nix);
 
-      devShell = forAllSystems (system:
+      devShell = forAllSystems (system: self.devShells.${system}.stdenvPackages);
+
+      devShells = forAllSystemsAndStdenvs (system: stdenv:
         with nixpkgsFor.${system};
         with commonDeps pkgs;
 
-        stdenv.mkDerivation {
+        nixpkgsFor.${system}.${stdenv}.mkDerivation {
           name = "nix";
 
           outputs = [ "out" "dev" "doc" ];

From 288c25257074e70e69a5d51f63dc783695ff4175 Mon Sep 17 00:00:00 2001
From: Pamplemousse <xav.maso@gmail.com>
Date: Thu, 8 Jul 2021 09:13:55 -0700
Subject: [PATCH 266/567] Documentation: alternative `stdenv` for hacking

Signed-off-by: Pamplemousse <xav.maso@gmail.com>
---
 doc/manual/src/contributing/hacking.md | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/doc/manual/src/contributing/hacking.md b/doc/manual/src/contributing/hacking.md
index 2a1e55e5b..90a8f1f94 100644
--- a/doc/manual/src/contributing/hacking.md
+++ b/doc/manual/src/contributing/hacking.md
@@ -35,6 +35,25 @@ variables are set up so that those dependencies can be found:
 $ nix-shell
 ```
 
+or if you have a flake-enabled nix:
+
+```console
+$ nix develop
+```
+
+To get a shell with a different compilation environment (e.g. stdenv,
+gccStdenv, clangStdenv, clang11Stdenv):
+
+```console
+$ nix-shell -A devShells.x86_64-linux.clang11StdenvPackages
+```
+
+or if you have a flake-enabled nix:
+
+```console
+$ nix develop .#clang11StdenvPackages
+```
+
 To build Nix itself in this shell:
 
 ```console

From 6d166d19a6c1ffc8e651b7045ca1a8a7fff42e57 Mon Sep 17 00:00:00 2001
From: Alex Shabalin <alex.shabalin@tweag.io>
Date: Fri, 26 Nov 2021 11:03:48 +0100
Subject: [PATCH 267/567] Catch flake-related exception type in REPL

Closes https://github.com/NixOS/nix/issues/5656
---
 src/nix/repl.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 41283c5f2..22a57de60 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -356,6 +356,8 @@ StringSet NixRepl::completePrefix(string prefix)
             // Quietly ignore evaluation errors.
         } catch (UndefinedVarError & e) {
             // Quietly ignore undefined variable errors.
+        } catch (BadURL & e) {
+            // Quietly ignore BadURL flake-related errors.
         }
     }
 

From 3ef66cd23a81ae809bee8c27c0d65c3699be5c66 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 26 Nov 2021 13:10:28 +0100
Subject: [PATCH 268/567] nix repl: Reset the terminal on exceptional exits

---
 src/nix/repl.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 22a57de60..2649eb0bd 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -279,6 +279,7 @@ bool NixRepl::getLine(string & input, const std::string &prompt)
     };
 
     setupSignals();
+    Finally resetTerminal([&]() { rl_deprep_terminal(); });
     char * s = readline(prompt.c_str());
     Finally doFree([&]() { free(s); });
     restoreSignals();

From 152e3cda0c3e2309b37593b06f9e113ec44f506a Mon Sep 17 00:00:00 2001
From: Tom Bereknyei <tomberek@gmail.com>
Date: Fri, 26 Nov 2021 10:55:43 -0500
Subject: [PATCH 269/567] reproducibility: determinstic man page output for
 cores

---
 doc/manual/local.mk | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/doc/manual/local.mk b/doc/manual/local.mk
index e43d9f2fb..6b232a736 100644
--- a/doc/manual/local.mk
+++ b/doc/manual/local.mk
@@ -12,11 +12,13 @@ man-pages := $(foreach n, \
 clean-files += $(d)/*.1 $(d)/*.5 $(d)/*.8
 
 # Provide a dummy environment for nix, so that it will not access files outside the macOS sandbox.
+# Set cores to 0 because otherwise nix show-config resolves the cores based on the current machine
 dummy-env = env -i \
 	HOME=/dummy \
 	NIX_CONF_DIR=/dummy \
 	NIX_SSL_CERT_FILE=/dummy/no-ca-bundle.crt \
-	NIX_STATE_DIR=/dummy
+	NIX_STATE_DIR=/dummy \
+	NIX_CONFIG='cores = 0'
 
 nix-eval = $(dummy-env) $(bindir)/nix eval --experimental-features nix-command -I nix/corepkgs=corepkgs --store dummy:// --impure --raw
 

From 3a0277305a5d86f29e5bdc1c425c45e4bd7dbe71 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Fri, 26 Nov 2021 16:56:25 +0100
Subject: [PATCH 270/567] =?UTF-8?q?Don=E2=80=99t=20try=20to=20complete=20f?=
 =?UTF-8?q?lakes=20is=20the=20feature=20isn=E2=80=99t=20enabled?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Fix #5661
---
 src/libcmd/installables.cc | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index 5758b52ad..ef200b1d2 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -291,6 +291,9 @@ void completeFlakeRefWithFragment(
 
 void completeFlakeRef(ref<Store> store, std::string_view prefix)
 {
+    if (!settings.isExperimentalFeatureEnabled(Xp::Flakes))
+        return;
+
     if (prefix == "")
         completions->add(".");
 

From 1d5a881da574fc4883e4950c82f520fcf59d583a Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Sat, 27 Nov 2021 23:29:48 +0300
Subject: [PATCH 271/567] Fix typo

---
 src/nix/registry.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/nix/registry.md b/src/nix/registry.md
index a1674bd2e..d5c9ef442 100644
--- a/src/nix/registry.md
+++ b/src/nix/registry.md
@@ -2,7 +2,7 @@ R""(
 
 # Description
 
-`nix flake` provides subcommands for managing *flake
+`nix registry` provides subcommands for managing *flake
 registries*. Flake registries are a convenience feature that allows
 you to refer to flakes using symbolic identifiers such as `nixpkgs`,
 rather than full URLs such as `git://github.com/NixOS/nixpkgs`. You

From 33a227503adfaa570174c48d8c893f968ed8337f Mon Sep 17 00:00:00 2001
From: Alexander Sosedkin <monk@unboiled.info>
Date: Sat, 27 Nov 2021 23:02:04 +0100
Subject: [PATCH 272/567] Document libsodium, which is now mandatory, as a
 dependency

---
 configure.ac                                        | 2 +-
 doc/manual/src/installation/prerequisites-source.md | 5 +++++
 perl/configure.ac                                   | 2 +-
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/configure.ac b/configure.ac
index 65478ecc5..bca650005 100644
--- a/configure.ac
+++ b/configure.ac
@@ -188,7 +188,7 @@ PKG_CHECK_MODULES([EDITLINE], [libeditline], [CXXFLAGS="$EDITLINE_CFLAGS $CXXFLA
     [AC_MSG_ERROR([Nix requires libeditline; it was not found via pkg-config, but via its header, but required functions do not work. Maybe it is too old? >= 1.14 is required.])])
 ])
 
-# Look for libsodium, an optional dependency.
+# Look for libsodium.
 PKG_CHECK_MODULES([SODIUM], [libsodium], [CXXFLAGS="$SODIUM_CFLAGS $CXXFLAGS"])
 
 # Look for libbrotli{enc,dec}.
diff --git a/doc/manual/src/installation/prerequisites-source.md b/doc/manual/src/installation/prerequisites-source.md
index 0323a4f55..b3753b53b 100644
--- a/doc/manual/src/installation/prerequisites-source.md
+++ b/doc/manual/src/installation/prerequisites-source.md
@@ -44,6 +44,11 @@
     obtained from the its repository
     <https://github.com/troglobit/editline>.
 
+  - The `libsodium` library for verifying cryptographic signatures
+    of contents fetched from binary caches.
+    It can be obtained from the official web site
+    <https://libsodium.org>.
+
   - Recent versions of Bison and Flex to build the parser. (This is
     because Nix needs GLR support in Bison and reentrancy support in
     Flex.) For Bison, you need version 2.6, which can be obtained from
diff --git a/perl/configure.ac b/perl/configure.ac
index eb65ac17b..a02cb06c9 100644
--- a/perl/configure.ac
+++ b/perl/configure.ac
@@ -41,7 +41,7 @@ perlarchname=$($perl -e 'use Config; print $Config{archname};')
 AC_SUBST(perllibdir, [${libdir}/perl5/site_perl/$perlversion/$perlarchname])
 AC_MSG_RESULT($perllibdir)
 
-# Look for libsodium, an optional dependency.
+# Look for libsodium.
 PKG_CHECK_MODULES([SODIUM], [libsodium], [CXXFLAGS="$SODIUM_CFLAGS $CXXFLAGS"])
 
 # Check for the required Perl dependencies (DBI and DBD::SQLite).

From b73a1c06386f43b0b0d7ce99448b8c55f4c5156c Mon Sep 17 00:00:00 2001
From: Alexander Sosedkin <monk@unboiled.info>
Date: Sun, 28 Nov 2021 00:47:25 +0100
Subject: [PATCH 273/567] Document libcpuid dependency

---
 doc/manual/src/installation/prerequisites-source.md | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/doc/manual/src/installation/prerequisites-source.md b/doc/manual/src/installation/prerequisites-source.md
index 0323a4f55..37e0b5a10 100644
--- a/doc/manual/src/installation/prerequisites-source.md
+++ b/doc/manual/src/installation/prerequisites-source.md
@@ -58,3 +58,9 @@
     `--disable-seccomp-sandboxing` option to the `configure` script (Not
     recommended unless your system doesn't support `libseccomp`). To get
     the library, visit <https://github.com/seccomp/libseccomp>.
+
+  - On 64-bit x86 machines only, `libcpuid` library
+    is used to determine which microarchitecture levels are supported
+    (e.g., as whether to have `x86_64-v2-linux` among additional system types).
+    The library is available from its homepage
+    <http://libcpuid.sourceforge.net>.

From a9bd06d0ea2c7af9fa33763bdca174db76400ee0 Mon Sep 17 00:00:00 2001
From: Alexander Sosedkin <monk@unboiled.info>
Date: Sun, 28 Nov 2021 00:48:04 +0100
Subject: [PATCH 274/567] Make libcpuid dependency optional with
 --disable-cpuid

---
 configure.ac                                        | 13 ++++++++++---
 doc/manual/src/installation/prerequisites-source.md |  2 ++
 tests/local.mk                                      |  5 ++++-
 3 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/configure.ac b/configure.ac
index 65478ecc5..4108eb0a8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -195,10 +195,17 @@ PKG_CHECK_MODULES([SODIUM], [libsodium], [CXXFLAGS="$SODIUM_CFLAGS $CXXFLAGS"])
 PKG_CHECK_MODULES([LIBBROTLI], [libbrotlienc libbrotlidec], [CXXFLAGS="$LIBBROTLI_CFLAGS $CXXFLAGS"])
 
 # Look for libcpuid.
+have_libcpuid=
 if test "$machine_name" = "x86_64"; then
-  PKG_CHECK_MODULES([LIBCPUID], [libcpuid], [CXXFLAGS="$LIBCPUID_CFLAGS $CXXFLAGS"])
-  have_libcpuid=1
-  AC_DEFINE([HAVE_LIBCPUID], [1], [Use libcpuid])
+    AC_ARG_ENABLE([cpuid],
+                  AS_HELP_STRING([--disable-cpuid], [Do not determine microarchitecture levels with libcpuid (relevant to x86_64 only)]))
+    if test "x$enable_cpuid" != "xno"; then
+      PKG_CHECK_MODULES([LIBCPUID], [libcpuid],
+        [CXXFLAGS="$LIBCPUID_CFLAGS $CXXFLAGS"
+         have_libcpuid=1
+         AC_DEFINE([HAVE_LIBCPUID], [1], [Use libcpuid])]
+      )
+    fi
 fi
 AC_SUBST(HAVE_LIBCPUID, [$have_libcpuid])
 
diff --git a/doc/manual/src/installation/prerequisites-source.md b/doc/manual/src/installation/prerequisites-source.md
index 37e0b5a10..1b03bacd3 100644
--- a/doc/manual/src/installation/prerequisites-source.md
+++ b/doc/manual/src/installation/prerequisites-source.md
@@ -64,3 +64,5 @@
     (e.g., as whether to have `x86_64-v2-linux` among additional system types).
     The library is available from its homepage
     <http://libcpuid.sourceforge.net>.
+    This is an optional dependency and can be disabled
+    by providing a `--disable-cpuid` to the `configure` script.
diff --git a/tests/local.mk b/tests/local.mk
index 6f38853bc..936b72c2a 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -48,7 +48,6 @@ nix_tests = \
   flakes.sh \
   flake-local-settings.sh \
   build.sh \
-  compute-levels.sh \
   repl.sh ca/repl.sh \
   ca/build.sh \
   ca/build-with-garbage-path.sh \
@@ -63,6 +62,10 @@ nix_tests = \
   eval-store.sh
   # parallel.sh
 
+ifeq ($(HAVE_LIBCPUID), 1)
+	nix_tests += compute-levels.sh
+endif
+
 install-tests += $(foreach x, $(nix_tests), tests/$(x))
 
 tests-environment = NIX_REMOTE= $(bash) -e

From 90d8178009381fe7ad6f0380127df2bc5a0d1dc9 Mon Sep 17 00:00:00 2001
From: Andreas Rammhold <andreas@rammhold.de>
Date: Sat, 6 Nov 2021 19:50:27 +0100
Subject: [PATCH 275/567] Don't move the arguments of the primOp

Moving arguments of the primOp into the registration structure makes it
impossible to initialize a second EvalState with the correct primOp
registration. It will end up registering all those "RegisterPrimOp"'s
with an arity of zero on all but the 2nd instance of the EvalState.

Not moving the memory will add a tiny bit of memory overhead during the
eval since we need a copy of all the argument lists of all the primOp's.
The overhead shouldn't be too bad as it is static (based on the amonut
of registered operations) and only occurs once during the interpreter
startup.
---
 src/libexpr/primops.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index c0d59da8c..d1f4d9009 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -3732,7 +3732,7 @@ void EvalState::createBaseEnv()
                 .fun = primOp.fun,
                 .arity = std::max(primOp.args.size(), primOp.arity),
                 .name = symbols.create(primOp.name),
-                .args = std::move(primOp.args),
+                .args = primOp.args,
                 .doc = primOp.doc,
             });
 

From 6e0cbc666b60515b5e201dd28855f5fe1de9a107 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 29 Nov 2021 11:20:50 +0100
Subject: [PATCH 276/567] createTempFile(): Mark file as CLOEEXEC

Fixes #5674.
---
 src/libutil/util.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index defb77a10..1b6467eb2 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -512,6 +512,7 @@ std::pair<AutoCloseFD, Path> createTempFile(const Path & prefix)
     AutoCloseFD fd(mkstemp((char *) tmpl.c_str()));
     if (!fd)
         throw SysError("creating temporary file '%s'", tmpl);
+    closeOnExec(fd.get());
     return {std::move(fd), tmpl};
 }
 

From bd628cf3da14b7d3fe0ba00932eb26d545b4b893 Mon Sep 17 00:00:00 2001
From: Yorick van Pelt <yorick@yorickvanpelt.nl>
Date: Mon, 22 Nov 2021 13:29:49 +0100
Subject: [PATCH 277/567] flakes: fix boolean and int nixConfig values

Some type confusion was causing ints to be pointers, and bools
to be ints. Fixes #5621
---
 src/libexpr/flake/config.cc | 8 ++++----
 src/libexpr/flake/flake.cc  | 2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/libexpr/flake/config.cc b/src/libexpr/flake/config.cc
index c03f4106c..7ecd61816 100644
--- a/src/libexpr/flake/config.cc
+++ b/src/libexpr/flake/config.cc
@@ -38,11 +38,11 @@ void ConfigFile::apply()
 
         // FIXME: Move into libutil/config.cc.
         std::string valueS;
-        if (auto s = std::get_if<std::string>(&value))
+        if (auto* s = std::get_if<std::string>(&value))
             valueS = *s;
-        else if (auto n = std::get_if<int64_t>(&value))
-            valueS = fmt("%d", n);
-        else if (auto b = std::get_if<Explicit<bool>>(&value))
+        else if (auto* n = std::get_if<int64_t>(&value))
+            valueS = fmt("%d", *n);
+        else if (auto* b = std::get_if<Explicit<bool>>(&value))
             valueS = b->t ? "true" : "false";
         else if (auto ss = std::get_if<std::vector<std::string>>(&value))
             valueS = concatStringsSep(" ", *ss); // FIXME: evil
diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index f5be67d67..732198031 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -254,7 +254,7 @@ static Flake getFlake(
             else if (setting.value->type() == nInt)
                 flake.config.settings.insert({setting.name, state.forceInt(*setting.value, *setting.pos)});
             else if (setting.value->type() == nBool)
-                flake.config.settings.insert({setting.name, state.forceBool(*setting.value, *setting.pos)});
+                flake.config.settings.insert({setting.name, Explicit<bool> { state.forceBool(*setting.value, *setting.pos) }});
             else if (setting.value->type() == nList) {
                 std::vector<std::string> ss;
                 for (unsigned int n = 0; n < setting.value->listSize(); ++n) {

From a473e85c808120def9a645235e1e6bfa746753b5 Mon Sep 17 00:00:00 2001
From: Eli Flanagan <eli@typedspace.com>
Date: Tue, 30 Nov 2021 11:13:46 -0500
Subject: [PATCH 278/567] docs: document set theory symbols

These symbols confused me so I wanted to gloss them to help future users. You can see the context here: https://discourse.nixos.org/t/flakes-what-does-mean-big-bundle-of-questions
---
 doc/manual/src/glossary.md | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/doc/manual/src/glossary.md b/doc/manual/src/glossary.md
index bb350d9de..92192e4cb 100644
--- a/doc/manual/src/glossary.md
+++ b/doc/manual/src/glossary.md
@@ -47,7 +47,7 @@
     the store object at `P` contains the path `Q` somewhere. The
     *references* of a store path are the set of store paths to which it
     has a reference.
-    
+
     A derivation can reference other derivations and sources (but not
     output paths), whereas an output path only references other output
     paths.
@@ -66,7 +66,7 @@
     is necessary to deploy whole closures, since otherwise at runtime
     files could be missing. The command `nix-store -qR` prints out
     closures of store paths.
-    
+
     As an example, if the store object at path `P` contains a reference
     to path `Q`, then `Q` is in the closure of `P`. Further, if `Q`
     references `R` then `R` is also in the closure of `P`.
@@ -98,3 +98,7 @@
     store. It can contain regular files, directories and symbolic
     links.  NARs are generated and unpacked using `nix-store --dump`
     and `nix-store --restore`.
+  - `∅` \
+    The empty set symbol. In the context of package history, this denotes a package was not present prior to installation.
+  - `ε` \
+    The epsilon symbol. In the context of a package, this means the version is empty. More precisely, the derivation does not have a version attribute.

From 5f64b69d23bfee70d222671a7d10f2efe22b99c6 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Tue, 30 Nov 2021 17:32:40 +0100
Subject: [PATCH 279/567] Add a github cron to check the hydra status
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Add a regular github action that will check the status of the latest
hydra evaluation.

Things aren’t ideal right now because this job will only notify “the
user who last modified the cron syntax in the workflow file” (so myself
atm). But at least that’ll give a notification for failing hydra jobs
---
 .github/workflows/hydra_status.yml | 16 ++++++++++++++++
 scripts/check-hydra-status.sh      | 28 ++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)
 create mode 100644 .github/workflows/hydra_status.yml
 create mode 100644 scripts/check-hydra-status.sh

diff --git a/.github/workflows/hydra_status.yml b/.github/workflows/hydra_status.yml
new file mode 100644
index 000000000..b97076bd7
--- /dev/null
+++ b/.github/workflows/hydra_status.yml
@@ -0,0 +1,16 @@
+name: Hydra status
+on:
+  schedule:
+    - cron: "12,42 * * * *"
+  workflow_dispatch:
+jobs:
+  check_hydra_status:
+    name: Check Hydra status
+    if: github.repository_owner == 'NixOS'
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2.4.0
+      with:
+        fetch-depth: 0
+    - run: bash scripts/check-hydra-status.sh
+
diff --git a/scripts/check-hydra-status.sh b/scripts/check-hydra-status.sh
new file mode 100644
index 000000000..c1d2d7c40
--- /dev/null
+++ b/scripts/check-hydra-status.sh
@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+# set -x
+
+
+# mapfile BUILDS_FOR_LATEST_EVAL < <(
+# curl -H 'Accept: application/json' https://hydra.nixos.org/jobset/nix/master/evals | \
+#   jq -r '.evals[0].builds[] | @sh')
+BUILDS_FOR_LATEST_EVAL=$(
+curl -sS -H 'Accept: application/json' https://hydra.nixos.org/jobset/nix/master/evals | \
+  jq -r '.evals[0].builds[]')
+
+someBuildFailed=0
+
+for buildId in $BUILDS_FOR_LATEST_EVAL; do
+  buildInfo=$(curl -sS -H 'Accept: application/json' "https://hydra.nixos.org/build/$buildId")
+
+  buildStatus=$(echo "$buildInfo" | \
+    jq -r '.buildstatus')
+
+  if [[ "$buildStatus" -ne 0 ]]; then
+    someBuildFailed=1
+    echo "Job “$(echo "$buildInfo" | jq -r '.job')” failed on hydra"
+  fi
+done
+
+exit "$someBuildFailed"

From 092c375cda9efc24f9a3d6b56d818792406b232b Mon Sep 17 00:00:00 2001
From: Eli Flanagan <eli@typedspace.com>
Date: Tue, 30 Nov 2021 13:19:42 -0500
Subject: [PATCH 280/567] Update doc/manual/src/glossary.md

Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
---
 doc/manual/src/glossary.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/manual/src/glossary.md b/doc/manual/src/glossary.md
index 92192e4cb..71ff13275 100644
--- a/doc/manual/src/glossary.md
+++ b/doc/manual/src/glossary.md
@@ -99,6 +99,6 @@
     links.  NARs are generated and unpacked using `nix-store --dump`
     and `nix-store --restore`.
   - `∅` \
-    The empty set symbol. In the context of package history, this denotes a package was not present prior to installation.
+    The empty set symbol. In the context of profile history, this denotes a package is not present in a particular version of the profile.
   - `ε` \
     The epsilon symbol. In the context of a package, this means the version is empty. More precisely, the derivation does not have a version attribute.

From 1f15441103caab1b41317a6107fc2560eb109a4a Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Tue, 30 Nov 2021 20:23:13 +0000
Subject: [PATCH 281/567] Tidy up the logging

Use the macros more, so we properly skip work when the log level
excludes. Also log the daemon operation number on the daemon side.
---
 src/libstore/daemon.cc    | 4 +++-
 src/libstore/store-api.cc | 2 +-
 src/libutil/logging.hh    | 5 +++--
 3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index 2eb566080..58c567b05 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -951,7 +951,7 @@ void processConnection(
 
     Finally finally([&]() {
         _isInterrupted = false;
-        prevLogger->log(lvlDebug, fmt("%d operations", opCount));
+        printMsgUsing(prevLogger, lvlDebug, "%d operations", opCount);
     });
 
     if (GET_PROTOCOL_MINOR(clientVersion) >= 14 && readInt(from)) {
@@ -984,6 +984,8 @@ void processConnection(
                 break;
             }
 
+            printMsgUsing(prevLogger, lvlDebug, "received daemon op %d", op);
+
             opCount++;
 
             try {
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 71350906e..aab4ce94c 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -1079,7 +1079,7 @@ std::map<StorePath, StorePath> copyPaths(
                     nrFailed++;
                     if (!settings.keepGoing)
                         throw e;
-                    logger->log(lvlError, fmt("could not copy %s: %s", dstStore.printStorePath(storePath), e.what()));
+                    printMsg(lvlError, "could not copy %s: %s", dstStore.printStorePath(storePath), e.what());
                     showProgress();
                     return;
                 }
diff --git a/src/libutil/logging.hh b/src/libutil/logging.hh
index 96ad69790..ce9c3dfed 100644
--- a/src/libutil/logging.hh
+++ b/src/libutil/logging.hh
@@ -189,13 +189,14 @@ extern Verbosity verbosity; /* suppress msgs > this */
 /* Print a string message if the current log level is at least the specified
    level. Note that this has to be implemented as a macro to ensure that the
    arguments are evaluated lazily. */
-#define printMsg(level, args...) \
+#define printMsgUsing(loggerParam, level, args...) \
     do { \
         auto __lvl = level; \
         if (__lvl <= nix::verbosity) { \
-            logger->log(__lvl, fmt(args)); \
+            loggerParam->log(__lvl, fmt(args)); \
         } \
     } while (0)
+#define printMsg(level, args...) printMsgUsing(logger, level, args)
 
 #define printError(args...) printMsg(lvlError, args)
 #define notice(args...) printMsg(lvlNotice, args)

From 70a717f7a8feb15d9daf1215e305162b999b6175 Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Tue, 30 Nov 2021 20:53:10 +0000
Subject: [PATCH 282/567] Nix daemon stream old wopAddToStore

No more buffering in string.
---
 src/libstore/daemon.cc | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index 2eb566080..773794ffc 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -431,25 +431,23 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
                 hashAlgo = parseHashType(hashAlgoRaw);
             }
 
-            StringSink saved;
-            TeeSource savedNARSource(from, saved);
-            RetrieveRegularNARSink savedRegular { saved };
+            auto dumpSource = sinkToSource([&](Sink & saved) {
+                TeeSource savedNARSource(from, saved);
+                RetrieveRegularNARSink savedRegular { saved };
 
-            if (method == FileIngestionMethod::Recursive) {
-                /* Get the entire NAR dump from the client and save it to
-                  a string so that we can pass it to
-                  addToStoreFromDump(). */
-                ParseSink sink; /* null sink; just parse the NAR */
-                parseDump(sink, savedNARSource);
-            } else
-                parseDump(savedRegular, from);
+                if (method == FileIngestionMethod::Recursive) {
+                    /* Get the entire NAR dump from the client and save it to
+                      a string so that we can pass it to
+                      addToStoreFromDump(). */
+                    ParseSink sink; /* null sink; just parse the NAR */
+                    parseDump(sink, savedNARSource);
+                } else
+                    parseDump(savedRegular, from);
 
+                if (!savedRegular.regular) throw Error("regular file expected");
+            });
             logger->startWork();
-            if (!savedRegular.regular) throw Error("regular file expected");
-
-            // FIXME: try to stream directly from `from`.
-            StringSource dumpSource { *saved.s };
-            auto path = store->addToStoreFromDump(dumpSource, baseName, method, hashAlgo);
+            auto path = store->addToStoreFromDump(*dumpSource, baseName, method, hashAlgo);
             logger->stopWork();
 
             to << store->printStorePath(path);

From 95157b4e664dc6f4dece15beac6fa1143086323e Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Tue, 30 Nov 2021 21:02:45 +0000
Subject: [PATCH 283/567] Push wopAddToStore old style stream adapters into
 smaller scopes

This doesn't fix the bug, but makes the code less difficult to read.
Also improve the comments, now that it is clear what part is needed in
each code path.
---
 src/libstore/daemon.cc | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index 773794ffc..dc4889dfd 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -432,19 +432,26 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
             }
 
             auto dumpSource = sinkToSource([&](Sink & saved) {
-                TeeSource savedNARSource(from, saved);
-                RetrieveRegularNARSink savedRegular { saved };
-
                 if (method == FileIngestionMethod::Recursive) {
-                    /* Get the entire NAR dump from the client and save it to
-                      a string so that we can pass it to
-                      addToStoreFromDump(). */
+                    /* We parse the NAR dump through into `saved` unmodified,
+                       so why all this extra work? We still parse the NAR so
+                       that we aren't sending arbitrary data to `saved`
+                       unwittingly`, and we know when the NAR ends so we don't
+                       consume the rest of `from` and can't parse another
+                       command. (We don't trust `addToStoreFromDump` to not
+                       eagerly consume the entire stream it's given, past the
+                       length of the Nar. */
+                    TeeSource savedNARSource(from, saved);
                     ParseSink sink; /* null sink; just parse the NAR */
                     parseDump(sink, savedNARSource);
-                } else
+                } else {
+                    /* Incrementally parse the NAR file, stripping the
+                       metadata, and streaming the sole file we expect into
+                       `saved`. */
+                    RetrieveRegularNARSink savedRegular { saved };
                     parseDump(savedRegular, from);
-
-                if (!savedRegular.regular) throw Error("regular file expected");
+                    if (!savedRegular.regular) throw Error("regular file expected");
+                }
             });
             logger->startWork();
             auto path = store->addToStoreFromDump(*dumpSource, baseName, method, hashAlgo);

From 2f5c913d4a21c60799290d6efe769d188c57b906 Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Tue, 30 Nov 2021 21:48:43 +0000
Subject: [PATCH 284/567] Fix #5299

No matter what, we need to resize the buffer to not have any scratch
space after we do the `read`. In the end of file case, `got` will be 0
from it's initial value.

Before, we forgot to resize in the EOF case with the break. Yes, we know
we didn't recieve any data in that case, but we still have the scatch
space to undo.

Co-Authored-By: Will Fancher <Will.Fancher@Obsidian.Systems>
---
 src/libstore/local-store.cc | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 64019314f..3a1688272 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -8,6 +8,7 @@
 #include "references.hh"
 #include "callback.hh"
 #include "topo-sort.hh"
+#include "finally.hh"
 
 #include <iostream>
 #include <algorithm>
@@ -1333,13 +1334,15 @@ StorePath LocalStore::addToStoreFromDump(Source & source0, const string & name,
         auto want = std::min(chunkSize, settings.narBufferSize - oldSize);
         dump.resize(oldSize + want);
         auto got = 0;
+        Finally cleanup([&]() {
+            dump.resize(oldSize + got);
+        });
         try {
             got = source.read(dump.data() + oldSize, want);
         } catch (EndOfFile &) {
             inMemory = true;
             break;
         }
-        dump.resize(oldSize + got);
     }
 
     std::unique_ptr<AutoDelete> delTempDir;

From 21520297dad8a198004e4551808a4818a8de7ddd Mon Sep 17 00:00:00 2001
From: Arthur Gautier <arthur.gautier@arista.com>
Date: Wed, 1 Dec 2021 16:08:23 +0100
Subject: [PATCH 285/567] reproducibility: hide non-reproducible settings from
 manual

Because the manual is generated from default values which are themselves
generated from various sources (cpuid, bios settings (kvm), number of
cores). This commit hides non-reproducible settings from the manual
output.
---
 doc/manual/generate-options.nix         | 24 +++++++++++++-----------
 src/libstore/globals.hh                 | 17 ++++++++++-------
 src/libutil/abstract-setting-to-json.hh |  1 +
 src/libutil/config.hh                   | 10 +++++++---
 src/libutil/tests/config.cc             |  2 +-
 5 files changed, 32 insertions(+), 22 deletions(-)

diff --git a/doc/manual/generate-options.nix b/doc/manual/generate-options.nix
index 3c31a4eec..9a77f4d36 100644
--- a/doc/manual/generate-options.nix
+++ b/doc/manual/generate-options.nix
@@ -8,17 +8,19 @@ concatStrings (map
     let option = options.${name}; in
     "  - `${name}`  \n\n"
     + concatStrings (map (s: "    ${s}\n") (splitLines option.description)) + "\n\n"
-    + "    **Default:** " + (
-      if option.value == "" || option.value == []
-      then "*empty*"
-      else if isBool option.value
-      then (if option.value then "`true`" else "`false`")
-      else
-        # n.b. a StringMap value type is specified as a string, but
-        # this shows the value type.  The empty stringmap is "null" in
-        # JSON, but that converts to "{ }" here.
-        (if isAttrs option.value then "`\"\"`"
-         else "`" + toString option.value + "`")) + "\n\n"
+    + (if option.documentDefault
+       then "    **Default:** " + (
+       if option.value == "" || option.value == []
+       then "*empty*"
+       else if isBool option.value
+       then (if option.value then "`true`" else "`false`")
+       else
+         # n.b. a StringMap value type is specified as a string, but
+         # this shows the value type.  The empty stringmap is "null" in
+         # JSON, but that converts to "{ }" here.
+         (if isAttrs option.value then "`\"\"`"
+          else "`" + toString option.value + "`")) + "\n\n"
+       else "    **Default:** *machine-specific*")
     + (if option.aliases != []
        then "    **Deprecated alias:** " + (concatStringsSep ", " (map (s: "`${s}`") option.aliases)) + "\n\n"
        else "")
diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index a50eb6803..e9eeffe8c 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -21,7 +21,7 @@ struct MaxBuildJobsSetting : public BaseSetting<unsigned int>
         const std::string & name,
         const std::string & description,
         const std::set<std::string> & aliases = {})
-        : BaseSetting<unsigned int>(def, name, description, aliases)
+        : BaseSetting<unsigned int>(def, true, name, description, aliases)
     {
         options->addSetting(this);
     }
@@ -38,7 +38,7 @@ struct PluginFilesSetting : public BaseSetting<Paths>
         const std::string & name,
         const std::string & description,
         const std::set<std::string> & aliases = {})
-        : BaseSetting<Paths>(def, name, description, aliases)
+        : BaseSetting<Paths>(def, true, name, description, aliases)
     {
         options->addSetting(this);
     }
@@ -130,7 +130,9 @@ public:
         {"build-max-jobs"}};
 
     Setting<unsigned int> buildCores{
-        this, getDefaultCores(), "cores",
+        this,
+        getDefaultCores(),
+        "cores",
         R"(
           Sets the value of the `NIX_BUILD_CORES` environment variable in the
           invocation of builders. Builders can use this variable at their
@@ -141,7 +143,7 @@ public:
           command line switch and defaults to `1`. The value `0` means that
           the builder should use all available CPU cores in the system.
         )",
-        {"build-cores"}};
+        {"build-cores"}, false};
 
     /* Read-only mode.  Don't copy stuff to the store, don't change
        the database. */
@@ -583,10 +585,11 @@ public:
           platform and generate incompatible code, so you may wish to
           cross-check the results of using this option against proper
           natively-built versions of your derivations.
-        )"};
+        )", {}, false};
 
     Setting<StringSet> systemFeatures{
-        this, getDefaultSystemFeatures(),
+        this,
+        getDefaultSystemFeatures(),
         "system-features",
         R"(
           A set of system “features” supported by this machine, e.g. `kvm`.
@@ -602,7 +605,7 @@ public:
           This setting by default includes `kvm` if `/dev/kvm` is accessible,
           and the pseudo-features `nixos-test`, `benchmark` and `big-parallel`
           that are used in Nixpkgs to route builds to specific machines.
-        )"};
+        )", {}, false};
 
     Setting<Strings> substituters{
         this,
diff --git a/src/libutil/abstract-setting-to-json.hh b/src/libutil/abstract-setting-to-json.hh
index b3fbc84f7..2d82b54e7 100644
--- a/src/libutil/abstract-setting-to-json.hh
+++ b/src/libutil/abstract-setting-to-json.hh
@@ -10,6 +10,7 @@ std::map<std::string, nlohmann::json> BaseSetting<T>::toJSONObject()
     auto obj = AbstractSetting::toJSONObject();
     obj.emplace("value", value);
     obj.emplace("defaultValue", defaultValue);
+    obj.emplace("documentDefault", documentDefault);
     return obj;
 }
 }
diff --git a/src/libutil/config.hh b/src/libutil/config.hh
index 736810bf3..79ec0f9cf 100644
--- a/src/libutil/config.hh
+++ b/src/libutil/config.hh
@@ -232,16 +232,19 @@ protected:
 
     T value;
     const T defaultValue;
+    const bool documentDefault;
 
 public:
 
     BaseSetting(const T & def,
+        const bool documentDefault,
         const std::string & name,
         const std::string & description,
         const std::set<std::string> & aliases = {})
         : AbstractSetting(name, description, aliases)
         , value(def)
         , defaultValue(def)
+        , documentDefault(documentDefault)
     { }
 
     operator const T &() const { return value; }
@@ -288,8 +291,9 @@ public:
         const T & def,
         const std::string & name,
         const std::string & description,
-        const std::set<std::string> & aliases = {})
-        : BaseSetting<T>(def, name, description, aliases)
+        const std::set<std::string> & aliases = {},
+        const bool documentDefault = true)
+        : BaseSetting<T>(def, documentDefault, name, description, aliases)
     {
         options->addSetting(this);
     }
@@ -311,7 +315,7 @@ public:
         const std::string & name,
         const std::string & description,
         const std::set<std::string> & aliases = {})
-        : BaseSetting<Path>(def, name, description, aliases)
+        : BaseSetting<Path>(def, true, name, description, aliases)
         , allowEmpty(allowEmpty)
     {
         options->addSetting(this);
diff --git a/src/libutil/tests/config.cc b/src/libutil/tests/config.cc
index 0ebdaf3db..8be6730dd 100644
--- a/src/libutil/tests/config.cc
+++ b/src/libutil/tests/config.cc
@@ -161,7 +161,7 @@ namespace nix {
         Setting<std::string> setting{&config, "", "name-of-the-setting", "description"};
         setting.assign("value");
 
-        ASSERT_EQ(config.toJSON().dump(), R"#({"name-of-the-setting":{"aliases":[],"defaultValue":"","description":"description\n","value":"value"}})#");
+        ASSERT_EQ(config.toJSON().dump(), R"#({"name-of-the-setting":{"aliases":[],"defaultValue":"","description":"description\n","documentDefault":true,"value":"value"}})#");
     }
 
     TEST(Config, setSettingAlias) {

From c32a5f4d380daafc33d129a097a494e1af8d9600 Mon Sep 17 00:00:00 2001
From: Sergei Trofimovich <slyich@gmail.com>
Date: Wed, 1 Dec 2021 22:06:15 +0000
Subject: [PATCH 286/567] src/libutil/util.hh: fix build on gcc-11

Due to missing <atomic> declaration the build fails as:

    src/libutil/util.hh:350:24: error: no match for 'operator||' (operand types are 'std::atomic<bool>' and 'bool')
      350 |     if (_isInterrupted || (interruptCheck && interruptCheck()))
          |         ~~~~~~~~~~~~~~ ^~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          |         |                                 |
          |         std::atomic<bool>                 bool
---
 src/libutil/util.hh | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 0bdb37a79..bc96bfed1 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -11,6 +11,7 @@
 #include <unistd.h>
 #include <signal.h>
 
+#include <atomic>
 #include <functional>
 #include <map>
 #include <sstream>

From 74898117360733bfc7ee57d1180a13f354c2ebbf Mon Sep 17 00:00:00 2001
From: David Arnold <david.arnold@iohk.io>
Date: Wed, 1 Dec 2021 18:36:19 -0500
Subject: [PATCH 287/567] Fix parent path check boundary

- Previous to this commit the boundary was exclusive of the
  top level flake.
- This is wrong since the top level flake is still a valid
  relative reference.
- Now, the check boundary is inclusive of the top level flake.

Signed-off-by: Timothy DeHerrera <tim.deh@pm.me>
---
 src/libfetchers/path.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libfetchers/path.cc b/src/libfetchers/path.cc
index fb5702c4c..07e543c53 100644
--- a/src/libfetchers/path.cc
+++ b/src/libfetchers/path.cc
@@ -97,7 +97,7 @@ struct PathInputScheme : InputScheme
             // for security, ensure that if the parent is a store path, it's inside it
             if (store->isInStore(parent)) {
                 auto storePath = store->printStorePath(store->toStorePath(parent).first);
-                if (!isInDir(absPath, storePath))
+                if (!isDirOrInDir(absPath, storePath))
                     throw BadStorePath("relative path '%s' points outside of its parent's store path '%s'", path, storePath);
             }
         } else

From 3bf7a868eefa5388400a63efd5c5b92b9177ff56 Mon Sep 17 00:00:00 2001
From: "Travis A. Everett" <travis.a.everett@gmail.com>
Date: Wed, 1 Dec 2021 18:38:32 -0600
Subject: [PATCH 288/567] darwin-install: nail down diskutil

Same purpose as de9efa3b79af7886fcf2a67b6ce97d4f96a57421

For some unclear reason, we get occasional reports from people who do
not have /usr/sbin on their PATH that the installer fails. It's a
standard part of the PATH, so I have no clue what they're doing to
remove it--but it's also fairly cheap to avoid.
---
 scripts/install-darwin-multi-user.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/scripts/install-darwin-multi-user.sh b/scripts/install-darwin-multi-user.sh
index 96eba8310..afaa6783b 100644
--- a/scripts/install-darwin-multi-user.sh
+++ b/scripts/install-darwin-multi-user.sh
@@ -218,7 +218,7 @@ EOF
         setup_darwin_volume
     fi
 
-    if [ "$(diskutil info -plist /nix | xmllint --xpath "(/plist/dict/key[text()='GlobalPermissionsEnabled'])/following-sibling::*[1]" -)" = "<false/>" ]; then
-        failure "This script needs a /nix volume with global permissions! This may require running sudo diskutil enableOwnership /nix."
+    if [ "$(/usr/sbin/diskutil info -plist /nix | xmllint --xpath "(/plist/dict/key[text()='GlobalPermissionsEnabled'])/following-sibling::*[1]" -)" = "<false/>" ]; then
+        failure "This script needs a /nix volume with global permissions! This may require running sudo /usr/sbin/diskutil enableOwnership /nix."
     fi
 }

From 8cbf862e6f6e8250d59491fdb88dfc11a805a970 Mon Sep 17 00:00:00 2001
From: Alexander Bantyev <balsoft@balsoft.ru>
Date: Thu, 2 Dec 2021 11:35:50 +0300
Subject: [PATCH 289/567] Flakes: computeLocks: pass correct LockParent when
 reusing oldLock

Previously, when we were attempting to reuse the old lockfile
information in the computeLocks function, we have passed the parent of
the current input to the next computeLocks call. This was incorrect,
since the follows are resolved relative to the parent. This caused
issues when we tried to reuse oldLock but couldn't for some
reason (read: mustRefetch is true), in that case the follows were
resolved incorrectly.

Fix this by passing the correct parent, and adding some tests to
prevent this particular regression from happening again.

Closes https://github.com/NixOS/nix/issues/5697
---
 src/libexpr/flake/flake.cc |  7 ++++++-
 tests/flakes.sh            | 12 ++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 06136579e..33d253eee 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -480,11 +480,16 @@ LockedFlake lockFlake(
                             }
                         }
 
+                        LockParent newParent {
+                            .path = inputPath,
+                            .absolute = false
+                        };
+
                         computeLocks(
                             mustRefetch
                             ? getFlake(state, oldLock->lockedRef, false, flakeCache).inputs
                             : fakeInputs,
-                            childNode, inputPath, oldLock, parent, parentPath);
+                            childNode, inputPath, oldLock, newParent, parentPath);
 
                     } else {
                         /* We need to create a new lock file entry. So fetch
diff --git a/tests/flakes.sh b/tests/flakes.sh
index 9e10322b9..20966ab2a 100644
--- a/tests/flakes.sh
+++ b/tests/flakes.sh
@@ -722,6 +722,7 @@ cat > $flakeFollowsB/flake.nix <<EOF
     inputs = {
         foobar.url = "path:$flakeFollowsA/flakeE";
         nonFlake.url = "path:$nonFlakeDir";
+        goodoo.follows = "C/goodoo";
         C = {
             url = "path:./flakeC";
             inputs.foobar.follows = "foobar";
@@ -736,6 +737,7 @@ cat > $flakeFollowsC/flake.nix <<EOF
     description = "Flake C";
     inputs = {
         foobar.url = "path:$flakeFollowsA/flakeE";
+        goodoo.follows = "foobar";
     };
     outputs = { ... }: {};
 }
@@ -760,8 +762,18 @@ EOF
 git -C $flakeFollowsA add flake.nix flakeB/flake.nix \
   flakeB/flakeC/flake.nix flakeD/flake.nix flakeE/flake.nix
 
+nix flake update $flakeFollowsA
+
+oldLock="$(cat "$flakeFollowsA/flake.lock")"
+
+# Ensure that locking twice doesn't change anything
+
 nix flake lock $flakeFollowsA
 
+newLock="$(cat "$flakeFollowsA/flake.lock")"
+
+diff <(echo "$newLock") <(echo "$oldLock")
+
 [[ $(jq -c .nodes.B.inputs.C $flakeFollowsA/flake.lock) = '"C"' ]]
 [[ $(jq -c .nodes.B.inputs.foobar $flakeFollowsA/flake.lock) = '["D"]' ]]
 [[ $(jq -c .nodes.C.inputs.foobar $flakeFollowsA/flake.lock) = '["B","foobar"]' ]]

From 90700736c7744b97ab69a4fadcd56fa242ec617f Mon Sep 17 00:00:00 2001
From: Silvan Mosberger <contact@infinisil.com>
Date: Thu, 2 Dec 2021 17:46:44 +0100
Subject: [PATCH 290/567] Introduce builtins.groupBy primop

This function is very useful in nixpkgs, but its implementation in Nix
itself is rather slow due to it requiring a lot of attribute set and
list appends.
---
 doc/manual/src/release-notes/rl-next.md |  3 ++
 src/libexpr/primops.cc                  | 50 +++++++++++++++++++++++++
 src/libexpr/value.hh                    |  2 +
 3 files changed, 55 insertions(+)

diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index 26c7d2cce..a6b22dfa7 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -5,3 +5,6 @@
 * `nix develop` now has a flag `--unpack` to run `unpackPhase`.
 
 * Lists can now be compared lexicographically using the `<` operator.
+
+* New built-in function: `builtins.groupBy`, with the same functionality as
+  Nixpkgs' `lib.groupBy`, but faster.
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index d1f4d9009..66af373d7 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -2928,6 +2928,56 @@ static RegisterPrimOp primop_partition({
     .fun = prim_partition,
 });
 
+static void prim_groupBy(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    state.forceFunction(*args[0], pos);
+    state.forceList(*args[1], pos);
+
+    ValueVectorMap attrs;
+
+    for (auto vElem : args[1]->listItems()) {
+        Value res;
+        state.callFunction(*args[0], *vElem, res, pos);
+        string name = state.forceStringNoCtx(res, pos);
+        Symbol sym = state.symbols.create(name);
+        auto vector = attrs.try_emplace(sym, ValueVector()).first;
+        vector->second.push_back(vElem);
+    }
+
+    state.mkAttrs(v, attrs.size());
+
+    for (auto & i : attrs) {
+        Value * list = state.allocAttr(v, i.first);
+        auto size = i.second.size();
+        state.mkList(*list, size);
+        memcpy(list->listElems(), i.second.data(), sizeof(Value *) * size);
+    }
+}
+
+static RegisterPrimOp primop_groupBy({
+    .name = "__groupBy",
+    .args = {"f", "list"},
+    .doc = R"(
+      Groups elements of *list* together by the string returned from the
+      function *f* called on each element. It returns an attribute set
+      where each attribute value contains the elements of *list* that are
+      mapped to the same corresponding attribute name returned by *f*.
+
+      For example,
+
+      ```nix
+      builtins.groupBy (builtins.substring 0 1) ["foo" "bar" "baz"]
+      ```
+
+      evaluates to
+
+      ```nix
+      { b = [ "bar" "baz" ]; f = [ "foo" ]; }
+      ```
+    )",
+    .fun = prim_groupBy,
+});
+
 static void prim_concatMap(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     state.forceFunction(*args[0], pos);
diff --git a/src/libexpr/value.hh b/src/libexpr/value.hh
index 4b43e47ae..6b4f3c0ae 100644
--- a/src/libexpr/value.hh
+++ b/src/libexpr/value.hh
@@ -425,9 +425,11 @@ void mkPath(Value & v, const char * s);
 #if HAVE_BOEHMGC
 typedef std::vector<Value *, traceable_allocator<Value *> > ValueVector;
 typedef std::map<Symbol, Value *, std::less<Symbol>, traceable_allocator<std::pair<const Symbol, Value *> > > ValueMap;
+typedef std::map<Symbol, ValueVector, std::less<Symbol>, traceable_allocator<std::pair<const Symbol, ValueVector> > > ValueVectorMap;
 #else
 typedef std::vector<Value *> ValueVector;
 typedef std::map<Symbol, Value *> ValueMap;
+typedef std::map<Symbol, ValueVector> ValueVectorMap;
 #endif
 
 

From 69b919887550483925b5a30388c13a63dabcca1a Mon Sep 17 00:00:00 2001
From: David Purdum <davepurdum@protonmail.com>
Date: Thu, 2 Dec 2021 23:38:33 -0500
Subject: [PATCH 291/567] Fix docker command

`docker -ti run nixos` does not run on docker version 20.10.7 (my machine).  This fixes it to read `docker run -ti nixos`.
---
 doc/manual/src/installation/installing-docker.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/manual/src/installation/installing-docker.md b/doc/manual/src/installation/installing-docker.md
index 3d2255b7a..ee7614bdb 100644
--- a/doc/manual/src/installation/installing-docker.md
+++ b/doc/manual/src/installation/installing-docker.md
@@ -3,7 +3,7 @@
 To run the latest stable release of Nix with Docker run the following command:
 
 ```console
-$ docker -ti run nixos/nix
+$ docker run -ti nixos/nix
 Unable to find image 'nixos/nix:latest' locally
 latest: Pulling from nixos/nix
 5843afab3874: Pull complete

From b6cc0a704d8c1432e230ff65d4b74ea7114a730b Mon Sep 17 00:00:00 2001
From: Tom Bereknyei <tomberek@gmail.com>
Date: Fri, 3 Dec 2021 10:53:41 -0500
Subject: [PATCH 292/567] flakes: search up to git or filesystem boundary

While parsing a flakeref, upon not finding a flake.nix, search upwards
until git or filesystem boundary.
---
 doc/manual/src/release-notes/rl-next.md |  2 ++
 src/libexpr/flake/flakeref.cc           | 23 +++++++++++++++++++++--
 tests/flake-searching.sh                | 24 ++++++++++++++++++++++++
 tests/local.mk                          |  1 +
 4 files changed, 48 insertions(+), 2 deletions(-)
 create mode 100644 tests/flake-searching.sh

diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index a6b22dfa7..2826fc8be 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -8,3 +8,5 @@
 
 * New built-in function: `builtins.groupBy`, with the same functionality as
   Nixpkgs' `lib.groupBy`, but faster.
+
+* Nix now searches for a flake.nix up until git or filesystem boundary.
diff --git a/src/libexpr/flake/flakeref.cc b/src/libexpr/flake/flakeref.cc
index 29128d789..074727f06 100644
--- a/src/libexpr/flake/flakeref.cc
+++ b/src/libexpr/flake/flakeref.cc
@@ -117,8 +117,27 @@ std::pair<FlakeRef, std::string> parseFlakeRefWithFragment(
             if (!S_ISDIR(lstat(path).st_mode))
                 throw BadURL("path '%s' is not a flake (because it's not a directory)", path);
 
-            if (!allowMissing && !pathExists(path + "/flake.nix"))
-                throw BadURL("path '%s' is not a flake (because it doesn't contain a 'flake.nix' file)", path);
+            if (!allowMissing && !pathExists(path + "/flake.nix")){
+                notice("path '%s' does not contain a 'flake.nix', searching up",path);
+
+                // Save device to detect filesystem boundary
+                dev_t device = lstat(path).st_dev;
+                bool found = false;
+                while (path != "/") {
+                    if (pathExists(path + "/flake.nix")) {
+                        found = true;
+                        break;
+                    } else if (pathExists(path + "/.git"))
+                        throw Error("unable to find a flake before encountering git boundary at '%s'", path);
+                    else {
+                        if (lstat(path).st_dev != device)
+                            throw Error("unable to find a flake before encountering filesystem boundary at '%s'", path);
+                    }
+                    path = dirOf(path);
+                }
+                if (!found)
+                    throw BadURL("could not find a flake.nix file");
+            }
 
             auto flakeRoot = path;
             std::string subdir;
diff --git a/tests/flake-searching.sh b/tests/flake-searching.sh
new file mode 100644
index 000000000..82ae66894
--- /dev/null
+++ b/tests/flake-searching.sh
@@ -0,0 +1,24 @@
+source common.sh
+
+clearStore
+
+cp ./simple.nix ./simple.builder.sh ./config.nix $TEST_HOME
+cd $TEST_HOME
+cat <<EOF > flake.nix
+{
+    outputs = a: {
+       defaultPackage.$system = import ./simple.nix;
+       packages.$system.test = import ./simple.nix;
+    };
+}
+EOF
+mkdir subdir
+cd subdir
+
+for i in "" . "$PWD" .# .#test; do
+    nix build $i || fail "flake should be found by searching up directories"
+done
+
+for i in "path:$PWD"; do
+    ! nix build $i || fail "flake should not search up directories when using 'path:'"
+done
diff --git a/tests/local.mk b/tests/local.mk
index 936b72c2a..9277c0b1b 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -47,6 +47,7 @@ nix_tests = \
   describe-stores.sh \
   flakes.sh \
   flake-local-settings.sh \
+  flake-searching.sh \
   build.sh \
   repl.sh ca/repl.sh \
   ca/build.sh \

From ad9322a48fce955fb30b111b0fb5c3b8007a6e2e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rg=20Thalheim?= <joerg@thalheim.io>
Date: Fri, 3 Dec 2021 18:36:33 +0100
Subject: [PATCH 293/567] update flake.nix to 21.11

---
 flake.lock | 8 ++++----
 flake.nix  | 2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/flake.lock b/flake.lock
index 861af1c54..5fb200248 100644
--- a/flake.lock
+++ b/flake.lock
@@ -18,16 +18,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1632864508,
-        "narHash": "sha256-d127FIvGR41XbVRDPVvozUPQ/uRHbHwvfyKHwEt5xFM=",
+        "lastModified": 1638501222,
+        "narHash": "sha256-tgOZW/rLcB4P7iffx88K3iF70YH+44PtV6kVg5YGIg0=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "82891b5e2c2359d7e58d08849e4c89511ab94234",
+        "rev": "45c527ae2de6f2f36d5790273343f06cd14bc0d1",
         "type": "github"
       },
       "original": {
         "id": "nixpkgs",
-        "ref": "nixos-21.05-small",
+        "ref": "nixos-21.11-small",
         "type": "indirect"
       }
     },
diff --git a/flake.nix b/flake.nix
index 9a5d188ae..942388ab4 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,7 +1,7 @@
 {
   description = "The purely functional package manager";
 
-  inputs.nixpkgs.url = "nixpkgs/nixos-21.05-small";
+  inputs.nixpkgs.url = "nixpkgs/nixos-21.11-small";
   inputs.lowdown-src = { url = "github:kristapsdz/lowdown"; flake = false; };
 
   outputs = { self, nixpkgs, lowdown-src }:

From 52f5fa948a4784b6a9b707770f4beee6a8674dee Mon Sep 17 00:00:00 2001
From: Connor Baker <connorbaker01@gmail.com>
Date: Fri, 3 Dec 2021 22:16:02 -0500
Subject: [PATCH 294/567] Add support for .tar.gz shorthand (.tgz) to
 TarballInputScheme

---
 src/libfetchers/tarball.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/libfetchers/tarball.cc b/src/libfetchers/tarball.cc
index 031ccc5f7..69d020748 100644
--- a/src/libfetchers/tarball.cc
+++ b/src/libfetchers/tarball.cc
@@ -176,6 +176,7 @@ struct TarballInputScheme : InputScheme
 
         if (!hasSuffix(url.path, ".zip")
             && !hasSuffix(url.path, ".tar")
+            && !hasSuffix(url.path, ".tgz")
             && !hasSuffix(url.path, ".tar.gz")
             && !hasSuffix(url.path, ".tar.xz")
             && !hasSuffix(url.path, ".tar.bz2")

From d9b3adca756bdc10c298439f4502626bbcefcc2a Mon Sep 17 00:00:00 2001
From: Zhong Jianxin <azuwis@gmail.com>
Date: Sat, 4 Dec 2021 20:46:29 +0800
Subject: [PATCH 295/567] launchd: Set NumberOfFiles to 4096

The default maxfiles on macOS 11 and macOS 12 is 256, which is too low
for nix to work:

```
$ launchctl limit maxfiles
	maxfiles    256            unlimited
```

Set NumberOfFiles of nix-daemon to 4096 to avoid `Too many open files`
error.
---
 misc/launchd/org.nixos.nix-daemon.plist.in | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/misc/launchd/org.nixos.nix-daemon.plist.in b/misc/launchd/org.nixos.nix-daemon.plist.in
index f1b439840..da1970f69 100644
--- a/misc/launchd/org.nixos.nix-daemon.plist.in
+++ b/misc/launchd/org.nixos.nix-daemon.plist.in
@@ -25,5 +25,10 @@
     <string>/var/log/nix-daemon.log</string>
     <key>StandardOutPath</key>
     <string>/dev/null</string>
+    <key>SoftResourceLimits</key>
+    <dict>
+      <key>NumberOfFiles</key>
+      <integer>4096</integer>
+    </dict>
   </dict>
 </plist>

From 80934561114df14137ef07b6c07e17dff3a95544 Mon Sep 17 00:00:00 2001
From: "Travis A. Everett" <travis.a.everett@gmail.com>
Date: Sat, 4 Dec 2021 23:07:17 -0600
Subject: [PATCH 296/567] document some darwin mount settings

---
 .../src/installation/installing-binary.md     | 24 +++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/doc/manual/src/installation/installing-binary.md b/doc/manual/src/installation/installing-binary.md
index 96fa34635..4367654a2 100644
--- a/doc/manual/src/installation/installing-binary.md
+++ b/doc/manual/src/installation/installing-binary.md
@@ -119,6 +119,30 @@ this to run the installer, but it may help if you run into trouble:
 - update `/etc/synthetic.conf` to direct macOS to create a "synthetic"
   empty root directory to mount your volume
 - specify mount options for the volume in `/etc/fstab`
+  - `rw`: read-write
+  - `noauto`: prevent the system from auto-mounting the volume (so the
+    LaunchDaemon mentioned below can control mounting it, and to avoid
+    masking problems with that mounting service).
+  - `nobrowse`: prevent the Nix Store volume from showing up on your
+    desktop; also keeps Spotlight from spending resources to index
+    this volume
+  <!-- TODO:
+  - `suid`: honor setuid? surely not? ...
+  - `owners`: honor file ownership on the volume
+
+    For now I'll avoid pretending to understand suid/owners more
+    than I do. There've been some vague reports of file-ownership
+    and permission issues, particularly in cloud/VM/headless setups.
+    My pet theory is that this has something to do with these setups
+    not having a token that gets delegated to initial/admin accounts
+    on macOS. See scripts/create-darwin-volume.sh for a little more.
+
+    In any case, by Dec 4 2021, it _seems_ like some combination of
+    suid, owners, and calling diskutil enableOwnership have stopped
+    new reports from coming in. But I hesitate to celebrate because we
+    haven't really named and catalogued the behavior, understood what
+    we're fixing, and validated that all 3 components are essential.
+  -->
 - if you have FileVault enabled
     - generate an encryption password
     - put it in your system Keychain

From fa58bff1ab9aacffd50f8200d72843af7abd827f Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Mon, 6 Dec 2021 11:45:18 +0100
Subject: [PATCH 297/567] Fallback when the daemon is too old for CA
 derivations

Fix #5712
---
 src/libstore/remote-store.cc | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index a627e9cf1..c3d23affb 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -684,6 +684,14 @@ void RemoteStore::queryRealisationUncached(const DrvOutput & id,
     Callback<std::shared_ptr<const Realisation>> callback) noexcept
 {
     auto conn(getConnection());
+
+    if (GET_PROTOCOL_MINOR(conn->daemonVersion) < 27) {
+        warn("The daemon is too old for content-addressed derivations. I’ll do what I can");
+        try {
+            callback(nullptr);
+        } catch (...) { return callback.rethrow(); }
+    }
+
     conn->to << wopQueryRealisation;
     conn->to << id.to_string();
     conn.processStderr();

From d1aaa7ef71713b6693ad3ddf8704ce62bab82095 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 6 Dec 2021 13:33:39 +0100
Subject: [PATCH 298/567] Change version to X.Y.Z

Fixes #5732.
---
 .version | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.version b/.version
index 68151b2e1..fad066f80 100644
--- a/.version
+++ b/.version
@@ -1 +1 @@
-2.5
\ No newline at end of file
+2.5.0
\ No newline at end of file

From 0a2fa2d68460eca946c91b72cd264725e5cda7db Mon Sep 17 00:00:00 2001
From: Alexander Bantyev <balsoft@balsoft.ru>
Date: Fri, 26 Nov 2021 17:38:46 +0300
Subject: [PATCH 299/567] RunPager: restore stdout upon pager exit

Before this change, stdout was closed after the pager exits. This is
fine for non-interactive commands where we want to exit right after
the pager exits anyways, but for interactive things (e.g. nix repl)
this breaks the output after we quit the pager.

Keep the initial stdout fd as part of RunPager, and restore it in
RunPager::~RunPager using dup2.
---
 src/libmain/shared.cc | 4 ++--
 src/libmain/shared.hh | 1 +
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index b6bfea8cb..4404e0195 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -427,7 +427,7 @@ RunPager::RunPager()
     });
 
     pid.setKillSignal(SIGINT);
-
+    stdout = fcntl(STDOUT_FILENO, F_DUPFD_CLOEXEC, 0);
     if (dup2(toPager.writeSide.get(), STDOUT_FILENO) == -1)
         throw SysError("dupping stdout");
 }
@@ -438,7 +438,7 @@ RunPager::~RunPager()
     try {
         if (pid != -1) {
             std::cout.flush();
-            close(STDOUT_FILENO);
+            dup2(stdout, STDOUT_FILENO);
             pid.wait();
         }
     } catch (...) {
diff --git a/src/libmain/shared.hh b/src/libmain/shared.hh
index 05277d90a..ed012959b 100644
--- a/src/libmain/shared.hh
+++ b/src/libmain/shared.hh
@@ -88,6 +88,7 @@ public:
 
 private:
     Pid pid;
+    int stdout;
 };
 
 extern volatile ::sig_atomic_t blockInt;

From 33926ed1e75c06cbf70a920e462841cc9daa0520 Mon Sep 17 00:00:00 2001
From: Alexander Bantyev <balsoft@balsoft.ru>
Date: Fri, 26 Nov 2021 18:03:07 +0300
Subject: [PATCH 300/567] nix repl: add :log

Add a :log command that shows logs for a derivation.

Closes https://github.com/NixOS/nix/issues/3504

Co-authored-by: Taeer Bar-Yam <taeer@bar-yam.me>
---
 doc/manual/src/release-notes/rl-next.md |  2 ++
 src/nix/repl.cc                         | 26 +++++++++++++++++++++++--
 src/nix/repl.md                         |  7 +++++--
 tests/repl.sh                           | 13 +++++++++++++
 tests/simple-failing.builder.sh         |  2 ++
 tests/simple-failing.nix                |  8 ++++++++
 6 files changed, 54 insertions(+), 4 deletions(-)
 create mode 100644 tests/simple-failing.builder.sh
 create mode 100644 tests/simple-failing.nix

diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index a6b22dfa7..cf2da9aa8 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -8,3 +8,5 @@
 
 * New built-in function: `builtins.groupBy`, with the same functionality as
   Nixpkgs' `lib.groupBy`, but faster.
+
+* `nix repl` now has a `:log` command.
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 2649eb0bd..42143871f 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -430,7 +430,8 @@ bool NixRepl::processLine(string line)
              << "  :s <expr>     Build dependencies of derivation, then start nix-shell\n"
              << "  :t <expr>     Describe result of evaluation\n"
              << "  :u <expr>     Build derivation, then start nix-shell\n"
-             << "  :doc <expr>   Show documentation of a builtin function\n";
+             << "  :doc <expr>   Show documentation of a builtin function\n"
+             << "  :log <expr>   Show logs for a derivation\n";
     }
 
     else if (command == ":a" || command == ":add") {
@@ -500,7 +501,7 @@ bool NixRepl::processLine(string line)
         runNix("nix-shell", {state->store->printStorePath(drvPath)});
     }
 
-    else if (command == ":b" || command == ":i" || command == ":s") {
+    else if (command == ":b" || command == ":i" || command == ":s" || command == ":log") {
         Value v;
         evalString(arg, v);
         StorePath drvPath = getDerivationPath(v);
@@ -514,6 +515,27 @@ bool NixRepl::processLine(string line)
                 logger->cout("  %s -> %s", outputName, state->store->printStorePath(outputPath));
         } else if (command == ":i") {
             runNix("nix-env", {"-i", drvPathRaw});
+        } else if (command == ":log") {
+            settings.readOnlyMode = true;
+            Finally roModeReset([&]() {
+                settings.readOnlyMode = false;
+            });
+            auto subs = getDefaultSubstituters();
+
+            subs.push_front(state->store);
+
+            bool foundLog = false;
+            RunPager pager;
+            for (auto & sub : subs) {
+                auto log = sub->getBuildLog(drvPath);
+                if (log) {
+                    printInfo("got build log for '%s' from '%s'", drvPathRaw, sub->getUri());
+                    logger->writeToStdout(*log);
+                    foundLog = true;
+                    break;
+                }
+            }
+            if (!foundLog) throw Error("build log of '%s' is not available", drvPathRaw);
         } else {
             runNix("nix-shell", {drvPathRaw});
         }
diff --git a/src/nix/repl.md b/src/nix/repl.md
index bba60f871..9b6f2bee3 100644
--- a/src/nix/repl.md
+++ b/src/nix/repl.md
@@ -35,14 +35,17 @@ R""(
   nix-repl> emacs.drvPath
   "/nix/store/lp0sjrhgg03y2n0l10n70rg0k7hhyz0l-emacs-27.1.drv"
 
-  nix-repl> drv = runCommand "hello" { buildInputs = [ hello ]; } "hello > $out"
+  nix-repl> drv = runCommand "hello" { buildInputs = [ hello ]; } "hello; hello > $out"
 
-  nix-repl> :b x
+  nix-repl> :b drv
   this derivation produced the following outputs:
     out -> /nix/store/0njwbgwmkwls0w5dv9mpc1pq5fj39q0l-hello
 
   nix-repl> builtins.readFile drv
   "Hello, world!\n"
+
+  nix-repl> :log drv
+  Hello, world!
   ```
 
 # Description
diff --git a/tests/repl.sh b/tests/repl.sh
index d360821f2..f592822bc 100644
--- a/tests/repl.sh
+++ b/tests/repl.sh
@@ -3,6 +3,13 @@ source common.sh
 replCmds="
 simple = import ./simple.nix
 :b simple
+:log simple
+"
+
+replFailingCmds="
+failing = import ./simple-failing.nix
+:b failing
+:log failing
 "
 
 testRepl () {
@@ -12,6 +19,12 @@ testRepl () {
     local outPath=$(echo "$replOutput" |&
         grep -o -E "$NIX_STORE_DIR/\w*-simple")
     nix path-info "${nixArgs[@]}" "$outPath"
+    # simple.nix prints a PATH during build
+    echo "$replOutput" | grep -qs 'PATH=' || fail "nix repl :log doesn't output logs"
+    local replOutput="$(nix repl "${nixArgs[@]}" <<< "$replFailingCmds")"
+    echo "$replOutput"
+    echo "$replOutput" | grep -qs 'This should fail' \
+      || fail "nix repl :log doesn't output logs for a failed derivation"
 }
 
 # Simple test, try building a drv
diff --git a/tests/simple-failing.builder.sh b/tests/simple-failing.builder.sh
new file mode 100644
index 000000000..6285488ca
--- /dev/null
+++ b/tests/simple-failing.builder.sh
@@ -0,0 +1,2 @@
+echo "This should fail"
+exit 1
diff --git a/tests/simple-failing.nix b/tests/simple-failing.nix
new file mode 100644
index 000000000..1e3a080ed
--- /dev/null
+++ b/tests/simple-failing.nix
@@ -0,0 +1,8 @@
+with import ./config.nix;
+
+mkDerivation {
+  name = "simple-failing";
+  builder = ./simple-failing.builder.sh;
+  PATH = "";
+  goodPath = path;
+}

From ae21aab456f4e07fa621d87487c40381e45947dc Mon Sep 17 00:00:00 2001
From: Jan Tojnar <jtojnar@gmail.com>
Date: Mon, 6 Dec 2021 16:42:57 +0100
Subject: [PATCH 301/567] Update manual links

Fixes: https://github.com/NixOS/nixos-homepage/issues/762
---
 scripts/install-nix-from-closure.sh   | 6 +++---
 src/libstore/build/derivation-goal.cc | 2 +-
 src/libstore/build/worker.cc          | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/scripts/install-nix-from-closure.sh b/scripts/install-nix-from-closure.sh
index b5e2fea83..d543b4463 100644
--- a/scripts/install-nix-from-closure.sh
+++ b/scripts/install-nix-from-closure.sh
@@ -38,7 +38,7 @@ fi
 
 # Determine if we could use the multi-user installer or not
 if [ "$(uname -s)" = "Linux" ]; then
-    echo "Note: a multi-user installation is possible. See https://nixos.org/nix/manual/#sect-multi-user-installation" >&2
+    echo "Note: a multi-user installation is possible. See https://nixos.org/manual/nix/stable/installation/installing-binary.html#multi-user-installation" >&2
 fi
 
 case "$(uname -s)" in
@@ -98,7 +98,7 @@ while [ $# -gt 0 ]; do
                 echo "              providing multi-user support and better isolation for local builds."
                 echo "              Both for security and reproducibility, this method is recommended if"
                 echo "              supported on your platform."
-                echo "              See https://nixos.org/nix/manual/#sect-multi-user-installation"
+                echo "              See https://nixos.org/manual/nix/stable/installation/installing-binary.html#multi-user-installation"
                 echo ""
                 echo " --no-daemon: Simple, single-user installation that does not require root and is"
                 echo "              trivial to uninstall."
@@ -144,7 +144,7 @@ if ! [ -e "$dest" ]; then
 fi
 
 if ! [ -w "$dest" ]; then
-    echo "$0: directory $dest exists, but is not writable by you. This could indicate that another user has already performed a single-user installation of Nix on this system. If you wish to enable multi-user support see https://nixos.org/nix/manual/#ssec-multi-user. If you wish to continue with a single-user install for $USER please run 'chown -R $USER $dest' as root." >&2
+    echo "$0: directory $dest exists, but is not writable by you. This could indicate that another user has already performed a single-user installation of Nix on this system. If you wish to enable multi-user support see https://nixos.org/manual/nix/stable/installation/multi-user.html. If you wish to continue with a single-user install for $USER please run 'chown -R $USER $dest' as root." >&2
     exit 1
 fi
 
diff --git a/src/libstore/build/derivation-goal.cc b/src/libstore/build/derivation-goal.cc
index b924d23b2..60945403e 100644
--- a/src/libstore/build/derivation-goal.cc
+++ b/src/libstore/build/derivation-goal.cc
@@ -655,7 +655,7 @@ void DerivationGoal::tryLocalBuild() {
     throw Error(
         "unable to build with a primary store that isn't a local store; "
         "either pass a different '--store' or enable remote builds."
-        "\nhttps://nixos.org/nix/manual/#chap-distributed-builds");
+        "\nhttps://nixos.org/manual/nix/stable/advanced-topics/distributed-builds.html");
 }
 
 
diff --git a/src/libstore/build/worker.cc b/src/libstore/build/worker.cc
index 55afb5cca..f11c5ce68 100644
--- a/src/libstore/build/worker.cc
+++ b/src/libstore/build/worker.cc
@@ -281,11 +281,11 @@ void Worker::run(const Goals & _topGoals)
                 if (getMachines().empty())
                    throw Error("unable to start any build; either increase '--max-jobs' "
                             "or enable remote builds."
-                            "\nhttps://nixos.org/nix/manual/#chap-distributed-builds");
+                            "\nhttps://nixos.org/manual/nix/stable/advanced-topics/distributed-builds.html");
                 else
                    throw Error("unable to start any build; remote machines may not have "
                             "all required system features."
-                            "\nhttps://nixos.org/nix/manual/#chap-distributed-builds");
+                            "\nhttps://nixos.org/manual/nix/stable/advanced-topics/distributed-builds.html");
 
             }
             assert(!awake.empty());

From 853ef1304c379f03ef33f40bc68225d528cc6105 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 7 Dec 2021 21:45:09 +0100
Subject: [PATCH 302/567] Inline file

---
 tests/simple-failing.builder.sh | 2 --
 tests/simple-failing.nix        | 6 +++++-
 2 files changed, 5 insertions(+), 3 deletions(-)
 delete mode 100644 tests/simple-failing.builder.sh

diff --git a/tests/simple-failing.builder.sh b/tests/simple-failing.builder.sh
deleted file mode 100644
index 6285488ca..000000000
--- a/tests/simple-failing.builder.sh
+++ /dev/null
@@ -1,2 +0,0 @@
-echo "This should fail"
-exit 1
diff --git a/tests/simple-failing.nix b/tests/simple-failing.nix
index 1e3a080ed..d176c9c51 100644
--- a/tests/simple-failing.nix
+++ b/tests/simple-failing.nix
@@ -2,7 +2,11 @@ with import ./config.nix;
 
 mkDerivation {
   name = "simple-failing";
-  builder = ./simple-failing.builder.sh;
+  builder = builtins.toFile "builder.sh"
+    ''
+      echo "This should fail"
+      exit 1
+    '';
   PATH = "";
   goodPath = path;
 }

From 92ff5b4254b1a38a9dba4529d3dd4e9b11ea9333 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 7 Dec 2021 22:22:02 +0100
Subject: [PATCH 303/567] Tweak warning

---
 src/libstore/remote-store.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index c3d23affb..7f7e973e9 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -686,7 +686,7 @@ void RemoteStore::queryRealisationUncached(const DrvOutput & id,
     auto conn(getConnection());
 
     if (GET_PROTOCOL_MINOR(conn->daemonVersion) < 27) {
-        warn("The daemon is too old for content-addressed derivations. I’ll do what I can");
+        warn("the daemon is too old to support content-addressed derivations, please upgrade it to 2.4");
         try {
             callback(nullptr);
         } catch (...) { return callback.rethrow(); }

From b6d08a9e3ff76a38636377abe383b179b38e37b5 Mon Sep 17 00:00:00 2001
From: "Travis A. Everett" <travis.a.everett@gmail.com>
Date: Wed, 3 Nov 2021 23:17:48 -0500
Subject: [PATCH 304/567] darwin-install: fix break from bad vim plugins

---
 scripts/create-darwin-volume.sh | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/scripts/create-darwin-volume.sh b/scripts/create-darwin-volume.sh
index b52232dd3..7e1a38cbd 100755
--- a/scripts/create-darwin-volume.sh
+++ b/scripts/create-darwin-volume.sh
@@ -440,7 +440,22 @@ add_nix_vol_fstab_line() {
     # shellcheck disable=SC1003,SC2026
     local escaped_mountpoint="${NIX_ROOT/ /'\\\'040}"
     shift
-    EDITOR="/usr/bin/ex" _sudo "to add nix to fstab" "$@" <<EOF
+
+    # wrap `ex` to work around a problem with vim plugins breaking exit codes;
+    # (see https://github.com/NixOS/nix/issues/5468)
+    # we'd prefer EDITOR="/usr/bin/ex --noplugin" but vifs doesn't word-split
+    # the EDITOR env.
+    #
+    # TODO: at some point we should switch to `--clean`, but it wasn't added
+    # until https://github.com/vim/vim/releases/tag/v8.0.1554 while the macOS
+    # minver 10.12.6 seems to have released with vim 7.4
+    cat > "$SCRATCH/ex_cleanroom_wrapper" <<EOF
+#!/bin/sh
+/usr/bin/ex --noplugin "\$@"
+EOF
+    chmod 755 "$SCRATCH/ex_cleanroom_wrapper"
+
+    EDITOR="$SCRATCH/ex_cleanroom_wrapper" _sudo "to add nix to fstab" "$@" <<EOF
 :a
 UUID=$uuid $escaped_mountpoint apfs rw,noauto,nobrowse,suid,owners
 .
@@ -631,7 +646,7 @@ EOF
         # technically /etc/synthetic.d/nix is supported in Big Sur+
         # but handling both takes even more code...
         _sudo "to add Nix to /etc/synthetic.conf" \
-            /usr/bin/ex /etc/synthetic.conf <<EOF
+            /usr/bin/ex --noplugin /etc/synthetic.conf <<EOF
 :a
 ${NIX_ROOT:1}
 .
@@ -791,7 +806,7 @@ setup_volume_daemon() {
     local volume_uuid="$2"
     if ! test_voldaemon; then
         task "Configuring LaunchDaemon to mount '$NIX_VOLUME_LABEL'" >&2
-        _sudo "to install the Nix volume mounter" /usr/bin/ex "$NIX_VOLUME_MOUNTD_DEST" <<EOF
+        _sudo "to install the Nix volume mounter" /usr/bin/ex --noplugin "$NIX_VOLUME_MOUNTD_DEST" <<EOF
 :a
 $(generate_mount_daemon "$cmd_type" "$volume_uuid")
 .

From 971382cab0c8ee057706e3dd4a124252d6b3547d Mon Sep 17 00:00:00 2001
From: Gavin Ray <ray.gavin97@gmail.com>
Date: Wed, 8 Dec 2021 19:55:34 -0500
Subject: [PATCH 305/567] Better diagnostics if no valid signature found

I downloaded Nix tonight, and immediately broke it by accidentally removing the default binary caching.
After figuring this out, I also failed to fix it properly, due to using the wrong key for Nix's default binary cache

If the diagnostic message would have been clearer about what/where a "signature" for a "substituter" is + comes from, it probably would have saved me a few hours.
Maybe we can save other noobs the same pain?
---
 src/libstore/build/substitution-goal.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/libstore/build/substitution-goal.cc b/src/libstore/build/substitution-goal.cc
index 29a8cfb87..4c3701b27 100644
--- a/src/libstore/build/substitution-goal.cc
+++ b/src/libstore/build/substitution-goal.cc
@@ -140,6 +140,8 @@ void PathSubstitutionGoal::tryNext()
     {
         warn("substituter '%s' does not have a valid signature for path '%s'",
             sub->getUri(), worker.store.printStorePath(storePath));
+        warn("verify that your nix.conf contains a correct signature in 'trusted-public-keys' for %s",
+            sub->getUri());
         tryNext();
         return;
     }

From 55e3a1108cb41801c92d3697620408d9d272c2d2 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Thu, 9 Dec 2021 16:35:27 +0100
Subject: [PATCH 306/567] Properly take the last assignment in the REPL

When a variable is assigned in the REPL, make sure to remove any possible reference to the old one so that we correctly pick the new one afterwards

Fix #5706
---
 src/nix/repl.cc | 2 ++
 tests/repl.sh   | 1 +
 2 files changed, 3 insertions(+)

diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 42143871f..f453343f3 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -672,6 +672,8 @@ void NixRepl::addVarToScope(const Symbol & name, Value & v)
 {
     if (displ >= envSize)
         throw Error("environment full; cannot add more variables");
+    if (auto oldVar = staticEnv.find(name); oldVar != staticEnv.vars.end())
+        staticEnv.vars.erase(oldVar);
     staticEnv.vars.emplace_back(name, displ);
     staticEnv.sort();
     env->values[displ++] = &v;
diff --git a/tests/repl.sh b/tests/repl.sh
index f592822bc..995db869c 100644
--- a/tests/repl.sh
+++ b/tests/repl.sh
@@ -1,6 +1,7 @@
 source common.sh
 
 replCmds="
+simple = 1
 simple = import ./simple.nix
 :b simple
 :log simple

From 0bd93ed7478a827ea81e71dbce113cd7e073d8cb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Amon=20Stopin=C5=A1ek?= <am-on@users.noreply.github.com>
Date: Thu, 9 Dec 2021 16:44:24 +0000
Subject: [PATCH 307/567] Fix link to nixos channel

The old link returned 404 errror.
---
 doc/manual/src/package-management/basic-package-mgmt.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/manual/src/package-management/basic-package-mgmt.md b/doc/manual/src/package-management/basic-package-mgmt.md
index 50c6d3c2d..5f1d7a89c 100644
--- a/doc/manual/src/package-management/basic-package-mgmt.md
+++ b/doc/manual/src/package-management/basic-package-mgmt.md
@@ -40,7 +40,7 @@ $ nix-channel --update
 > 
 > On NixOS, you’re automatically subscribed to a NixOS channel
 > corresponding to your NixOS major release (e.g.
-> <http://nixos.org/channels/nixos-14.12>). A NixOS channel is identical
+> <http://nixos.org/channels/nixos-21.11>). A NixOS channel is identical
 > to the Nixpkgs channel, except that it contains only Linux binaries
 > and is updated only if a set of regression tests succeed.
 

From 5d64c33fa534773cbebfec3eee59d7b0ac74e59c Mon Sep 17 00:00:00 2001
From: Tom Bereknyei <tomberek@gmail.com>
Date: Thu, 9 Dec 2021 14:27:05 -0500
Subject: [PATCH 308/567] add pull_request_template.md

---
 .github/PULL_REQUEST_TEMPLATE/pull_request_template.md | 7 +++++++
 1 file changed, 7 insertions(+)
 create mode 100644 .github/PULL_REQUEST_TEMPLATE/pull_request_template.md

diff --git a/.github/PULL_REQUEST_TEMPLATE/pull_request_template.md b/.github/PULL_REQUEST_TEMPLATE/pull_request_template.md
new file mode 100644
index 000000000..537aa0909
--- /dev/null
+++ b/.github/PULL_REQUEST_TEMPLATE/pull_request_template.md
@@ -0,0 +1,7 @@
+**Release Notes**
+Please include relevant [release notes](https://github.com/NixOS/nix/blob/master/doc/manual/src/release-notes/rl-next.md) as needed.
+
+
+**Testing**
+
+If this issue is a regression or something that should block release, please consider including a test either in the [testsuite](https://github.com/NixOS/nix/tree/master/tests) or as a [hydraJob]( https://github.com/NixOS/nix/blob/master/flake.nix#L396) so that it can be part of the [automatic checks](https://hydra.nixos.org/jobset/nix/master).

From 4194b682500ee1e40b575e9729a8ddcbb6ac1518 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Janne=20He=C3=9F?= <janne@hess.ooo>
Date: Fri, 10 Dec 2021 12:58:12 +0100
Subject: [PATCH 309/567] doc: Fix command for distributed builds

We also need to build impurely or the <nixpkgs> lookup will not work.
---
 doc/manual/src/advanced-topics/distributed-builds.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/doc/manual/src/advanced-topics/distributed-builds.md b/doc/manual/src/advanced-topics/distributed-builds.md
index 580b36736..c4c60db15 100644
--- a/doc/manual/src/advanced-topics/distributed-builds.md
+++ b/doc/manual/src/advanced-topics/distributed-builds.md
@@ -53,8 +53,8 @@ example, the following command allows you to build a derivation for
 $ uname
 Linux
 
-$ nix build \
-  '(with import <nixpkgs> { system = "x86_64-darwin"; }; runCommand "foo" {} "uname > $out")' \
+$ nix build --impure \
+  --expr '(with import <nixpkgs> { system = "x86_64-darwin"; }; runCommand "foo" {} "uname > $out")' \
   --builders 'ssh://mac x86_64-darwin'
 [1/0/1 built, 0.0 MiB DL] building foo on ssh://mac
 

From 20b1290103f23e40614518291b8d4847e37fea05 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 10 Dec 2021 15:12:55 +0100
Subject: [PATCH 310/567] Ignore system.nfs4_acl

Closes #1584.
---
 src/libstore/globals.hh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index 2f9e8c6e8..433deaf0f 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -799,7 +799,7 @@ public:
         )"};
 
     Setting<StringSet> ignoredAcls{
-        this, {"security.selinux"}, "ignored-acls",
+        this, {"security.selinux", "system.nfs4_acl"}, "ignored-acls",
         R"(
           A list of ACLs that should be ignored, normally Nix attempts to
           remove all ACLs from files and directories in the Nix store, but

From be1055f2cc8841954521bf30a6f886cf3c807a28 Mon Sep 17 00:00:00 2001
From: Yorick van Pelt <yorick@yorickvanpelt.nl>
Date: Fri, 10 Dec 2021 17:00:32 +0100
Subject: [PATCH 311/567] extract_archive: use copy_pathname instead of
 set_pathname.

Libarchive documentation mentions that archive_entry_set_pathname
expects us to keep the passed string alive, which we don't.
---
 src/libutil/tarfile.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libutil/tarfile.cc b/src/libutil/tarfile.cc
index 50e691a3d..934b70162 100644
--- a/src/libutil/tarfile.cc
+++ b/src/libutil/tarfile.cc
@@ -93,7 +93,7 @@ static void extract_archive(TarArchive & archive, const Path & destDir)
         else
             archive.check(r);
 
-        archive_entry_set_pathname(entry,
+        archive_entry_copy_pathname(entry,
             (destDir + "/" + name).c_str());
 
         archive.check(archive_read_extract(archive.archive, entry, flags));

From 0e0de90b35b61edcfae3030c150b9d7e42bf39fe Mon Sep 17 00:00:00 2001
From: Yorick van Pelt <yorick@yorickvanpelt.nl>
Date: Fri, 10 Dec 2021 17:03:51 +0100
Subject: [PATCH 312/567] extract_archive: fix "Hard-link target '...'" error

Fixes #5741
---
 src/libutil/tarfile.cc | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/libutil/tarfile.cc b/src/libutil/tarfile.cc
index 934b70162..790bc943a 100644
--- a/src/libutil/tarfile.cc
+++ b/src/libutil/tarfile.cc
@@ -96,6 +96,13 @@ static void extract_archive(TarArchive & archive, const Path & destDir)
         archive_entry_copy_pathname(entry,
             (destDir + "/" + name).c_str());
 
+        // Patch hardlink path
+        const char *original_hardlink = archive_entry_hardlink(entry);
+        if (original_hardlink) {
+            archive_entry_copy_hardlink(entry,
+                (destDir + "/" + original_hardlink).c_str());
+        }
+
         archive.check(archive_read_extract(archive.archive, entry, flags));
     }
 

From 3542d4fe16822bcd94433bf9393fbe17a5297948 Mon Sep 17 00:00:00 2001
From: Gavin Ray <ray.gavin97@gmail.com>
Date: Fri, 10 Dec 2021 19:02:22 -0500
Subject: [PATCH 313/567] Incorporate suggestions from @edolstra

---
 src/libstore/build/substitution-goal.cc | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/src/libstore/build/substitution-goal.cc b/src/libstore/build/substitution-goal.cc
index 4c3701b27..5ecf1da7e 100644
--- a/src/libstore/build/substitution-goal.cc
+++ b/src/libstore/build/substitution-goal.cc
@@ -138,10 +138,8 @@ void PathSubstitutionGoal::tryNext()
        only after we've downloaded the path. */
     if (!sub->isTrusted && worker.store.pathInfoIsUntrusted(*info))
     {
-        warn("substituter '%s' does not have a valid signature for path '%s'",
-            sub->getUri(), worker.store.printStorePath(storePath));
-        warn("verify that your nix.conf contains a correct signature in 'trusted-public-keys' for %s",
-            sub->getUri());
+        warn("the substitute for '%s' from '%s' is not signed by any of the keys in 'trusted-public-keys'",
+            worker.store.printStorePath(storePath), sub->getUri());
         tryNext();
         return;
     }

From 33e96820d52dcfea387214f84ff2271959b3467b Mon Sep 17 00:00:00 2001
From: Yorick van Pelt <yorick@yorickvanpelt.nl>
Date: Sat, 11 Dec 2021 16:02:08 +0100
Subject: [PATCH 314/567] EvalCommand::getEvalState: use gc tracable allocator
 for EvalState

---
 src/libcmd/command.cc | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/libcmd/command.cc b/src/libcmd/command.cc
index fd3edfc46..429cd32cc 100644
--- a/src/libcmd/command.cc
+++ b/src/libcmd/command.cc
@@ -73,8 +73,13 @@ ref<Store> EvalCommand::getEvalStore()
 
 ref<EvalState> EvalCommand::getEvalState()
 {
-    if (!evalState)
-        evalState = std::make_shared<EvalState>(searchPath, getEvalStore(), getStore());
+    if (!evalState) evalState =
+#if HAVE_BOEHMGC
+        std::allocate_shared<EvalState>(traceable_allocator<EvalState>(),
+#else
+        std::make_shared<EvalState>(
+#endif
+            searchPath, getEvalStore(), getStore());
     return ref<EvalState>(evalState);
 }
 

From 3f417c8d1c3fc05af16766f21f13f2ecc15192a0 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 29 Nov 2021 12:42:01 +0100
Subject: [PATCH 315/567] Add release notes entry for #5149

---
 doc/manual/src/release-notes/rl-next.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index cf2da9aa8..61c189d22 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -1,5 +1,9 @@
 # Release 2.5 (2021-XX-XX)
 
+* The garbage collector no longer blocks new builds, so the message
+  `waiting for the big garbage collector lock...` is a thing of the
+  past.
+
 * Binary cache stores now have a setting `compression-level`.
 
 * `nix develop` now has a flag `--unpack` to run `unpackPhase`.

From f133001dc8c849053b8af9933902d11f274426bd Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 13 Dec 2021 16:48:44 +0100
Subject: [PATCH 316/567] Move rl-next.md to rl-2.5.md

---
 doc/manual/src/SUMMARY.md.in            |  1 +
 doc/manual/src/release-notes/rl-2.5.md  | 16 ++++++++++++++++
 doc/manual/src/release-notes/rl-next.md | 17 +----------------
 3 files changed, 18 insertions(+), 16 deletions(-)
 create mode 100644 doc/manual/src/release-notes/rl-2.5.md

diff --git a/doc/manual/src/SUMMARY.md.in b/doc/manual/src/SUMMARY.md.in
index 8d9b061ba..2876be52a 100644
--- a/doc/manual/src/SUMMARY.md.in
+++ b/doc/manual/src/SUMMARY.md.in
@@ -72,6 +72,7 @@
   - [CLI guideline](contributing/cli-guideline.md)
 - [Release Notes](release-notes/release-notes.md)
   - [Release X.Y (202?-??-??)](release-notes/rl-next.md)
+  - [Release 2.5 (2021-12-13)](release-notes/rl-2.5.md)
   - [Release 2.4 (2021-11-01)](release-notes/rl-2.4.md)
   - [Release 2.3 (2019-09-04)](release-notes/rl-2.3.md)
   - [Release 2.2 (2019-01-11)](release-notes/rl-2.2.md)
diff --git a/doc/manual/src/release-notes/rl-2.5.md b/doc/manual/src/release-notes/rl-2.5.md
new file mode 100644
index 000000000..61c189d22
--- /dev/null
+++ b/doc/manual/src/release-notes/rl-2.5.md
@@ -0,0 +1,16 @@
+# Release 2.5 (2021-XX-XX)
+
+* The garbage collector no longer blocks new builds, so the message
+  `waiting for the big garbage collector lock...` is a thing of the
+  past.
+
+* Binary cache stores now have a setting `compression-level`.
+
+* `nix develop` now has a flag `--unpack` to run `unpackPhase`.
+
+* Lists can now be compared lexicographically using the `<` operator.
+
+* New built-in function: `builtins.groupBy`, with the same functionality as
+  Nixpkgs' `lib.groupBy`, but faster.
+
+* `nix repl` now has a `:log` command.
diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index 61c189d22..c869b5e2f 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -1,16 +1 @@
-# Release 2.5 (2021-XX-XX)
-
-* The garbage collector no longer blocks new builds, so the message
-  `waiting for the big garbage collector lock...` is a thing of the
-  past.
-
-* Binary cache stores now have a setting `compression-level`.
-
-* `nix develop` now has a flag `--unpack` to run `unpackPhase`.
-
-* Lists can now be compared lexicographically using the `<` operator.
-
-* New built-in function: `builtins.groupBy`, with the same functionality as
-  Nixpkgs' `lib.groupBy`, but faster.
-
-* `nix repl` now has a `:log` command.
+# Release X.Y (202?-??-??)

From 55dbb7f1ccc0e991df6b09af0a16ce9246ac3f19 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Mon, 13 Dec 2021 16:56:44 +0100
Subject: [PATCH 317/567] More properly track the status of CA builds
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Make the build of unresolved derivations return the same status as the
resolved one, except in the case of an `AlreadyValid` in which case it
will return `ResolvesToAlreadyValid` to mean that the outputs of the unresolved
derivation weren’t known, but the resolved one is.
---
 src/libstore/build/derivation-goal.cc | 26 +++++++++++++++++---------
 src/libstore/build/derivation-goal.hh |  4 ++--
 src/libstore/store-api.hh             |  3 ++-
 3 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/src/libstore/build/derivation-goal.cc b/src/libstore/build/derivation-goal.cc
index 60945403e..a713d7222 100644
--- a/src/libstore/build/derivation-goal.cc
+++ b/src/libstore/build/derivation-goal.cc
@@ -464,7 +464,6 @@ void DerivationGoal::inputsRealised()
             Derivation drvResolved { *std::move(attempt) };
 
             auto pathResolved = writeDerivation(worker.store, drvResolved);
-            resolvedDrv = drvResolved;
 
             auto msg = fmt("Resolved derivation: '%s' -> '%s'",
                 worker.store.printStorePath(drvPath),
@@ -475,9 +474,9 @@ void DerivationGoal::inputsRealised()
                        worker.store.printStorePath(pathResolved),
                    });
 
-            auto resolvedGoal = worker.makeDerivationGoal(
+            resolvedDrvGoal = worker.makeDerivationGoal(
                 pathResolved, wantedOutputs, buildMode);
-            addWaitee(resolvedGoal);
+            addWaitee(resolvedDrvGoal);
 
             state = &DerivationGoal::resolvedFinished;
             return;
@@ -938,16 +937,17 @@ void DerivationGoal::buildDone()
 }
 
 void DerivationGoal::resolvedFinished() {
-    assert(resolvedDrv);
+    assert(resolvedDrvGoal);
+    auto resolvedDrv = *resolvedDrvGoal->drv;
 
-    auto resolvedHashes = staticOutputHashes(worker.store, *resolvedDrv);
+    auto resolvedHashes = staticOutputHashes(worker.store, resolvedDrv);
 
     StorePathSet outputPaths;
 
     // `wantedOutputs` might be empty, which means “all the outputs”
     auto realWantedOutputs = wantedOutputs;
     if (realWantedOutputs.empty())
-        realWantedOutputs = resolvedDrv->outputNames();
+        realWantedOutputs = resolvedDrv.outputNames();
 
     for (auto & wantedOutput : realWantedOutputs) {
         assert(initialOutputs.count(wantedOutput) != 0);
@@ -979,9 +979,17 @@ void DerivationGoal::resolvedFinished() {
         outputPaths
     );
 
-    // This is potentially a bit fishy in terms of error reporting. Not sure
-    // how to do it in a cleaner way
-    amDone(nrFailed == 0 ? ecSuccess : ecFailed, ex);
+    auto status = [&]() {
+        auto resolvedResult = resolvedDrvGoal->getResult();
+        switch (resolvedResult.status) {
+            case BuildResult::AlreadyValid:
+                return BuildResult::ResolvesToAlreadyValid;
+            default:
+                return resolvedResult.status;
+        }
+    }();
+
+    done(status);
 }
 
 HookReply DerivationGoal::tryBuildHook()
diff --git a/src/libstore/build/derivation-goal.hh b/src/libstore/build/derivation-goal.hh
index 704b77caf..e112542c7 100644
--- a/src/libstore/build/derivation-goal.hh
+++ b/src/libstore/build/derivation-goal.hh
@@ -50,8 +50,8 @@ struct DerivationGoal : public Goal
     /* The path of the derivation. */
     StorePath drvPath;
 
-    /* The path of the corresponding resolved derivation */
-    std::optional<BasicDerivation> resolvedDrv;
+    /* The goal for the corresponding resolved derivation */
+    std::shared_ptr<DerivationGoal> resolvedDrvGoal;
 
     /* The specific outputs that we need to build.  Empty means all of
        them. */
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index aa44651d4..3a385b293 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -151,6 +151,7 @@ struct BuildResult
         DependencyFailed,
         LogLimitExceeded,
         NotDeterministic,
+        ResolvesToAlreadyValid,
     } status = MiscFailure;
     std::string errorMsg;
 
@@ -170,7 +171,7 @@ struct BuildResult
     time_t startTime = 0, stopTime = 0;
 
     bool success() {
-        return status == Built || status == Substituted || status == AlreadyValid;
+        return status == Built || status == Substituted || status == AlreadyValid || status == ResolvesToAlreadyValid;
     }
 };
 

From 2eec2f765a86b8954f3a74ff148bc70a2d32be27 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Mon, 13 Dec 2021 16:58:43 +0100
Subject: [PATCH 318/567] Add a crude tracing mechansim for the build results
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Add a `_NIX_TRACE_BUILT_OUTPUTS` environment variable that can be set to
a filename in which the result of each build will be logged.

This is intentionally crude and undocumented as it’s only meant to be a
temporary thing to assess the usefulness of CA derivations.
Any other use would need a cleaner re-implementation first.
---
 src/libstore/build/derivation-goal.cc |  8 ++++++++
 src/libstore/store-api.hh             | 23 +++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/src/libstore/build/derivation-goal.cc b/src/libstore/build/derivation-goal.cc
index a713d7222..c6ab5c3d1 100644
--- a/src/libstore/build/derivation-goal.cc
+++ b/src/libstore/build/derivation-goal.cc
@@ -17,6 +17,7 @@
 #include <regex>
 #include <queue>
 
+#include <fstream>
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/un.h>
@@ -1337,6 +1338,13 @@ void DerivationGoal::done(BuildResult::Status status, std::optional<Error> ex)
     }
 
     worker.updateProgress();
+
+    auto traceBuiltOutputsFile = getEnv("_NIX_TRACE_BUILT_OUTPUTS").value_or("");
+    if (traceBuiltOutputsFile != "") {
+        std::fstream fs;
+        fs.open(traceBuiltOutputsFile, std::fstream::out);
+        fs << worker.store.printStorePath(drvPath) << "\t" << result.toString() << std::endl;
+    }
 }
 
 
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 3a385b293..3dd446f23 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -155,6 +155,29 @@ struct BuildResult
     } status = MiscFailure;
     std::string errorMsg;
 
+    std::string toString() const {
+        auto strStatus = [&]() {
+            switch (status) {
+                case Built: return "Built";
+                case Substituted: return "Substituted";
+                case AlreadyValid: return "AlreadyValid";
+                case PermanentFailure: return "PermanentFailure";
+                case InputRejected: return "InputRejected";
+                case OutputRejected: return "OutputRejected";
+                case TransientFailure: return "TransientFailure";
+                case CachedFailure: return "CachedFailure";
+                case TimedOut: return "TimedOut";
+                case MiscFailure: return "MiscFailure";
+                case DependencyFailed: return "DependencyFailed";
+                case LogLimitExceeded: return "LogLimitExceeded";
+                case NotDeterministic: return "NotDeterministic";
+                case ResolvesToAlreadyValid: return "ResolvesToAlreadyValid";
+                default: return "Unknown";
+            };
+        }();
+        return strStatus + ((errorMsg == "") ? "" : " : " + errorMsg);
+    }
+
     /* How many times this build was performed. */
     unsigned int timesBuilt = 0;
 

From 6d30f9e6fea7d451033653f8f167aef58f7f5347 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 13 Dec 2021 17:16:46 +0100
Subject: [PATCH 319/567] Explicitly make GC roots client sockets blocking

On macOS / BSD, these sockets inherit the non-blocking flag of the
server soocket, which is not what we want.

https://github.com/dotnet/runtime/issues/25069
https://bugs.python.org/issue7995

https://hydra.nixos.org/build/161439304
---
 src/libstore/gc.cc | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 7a414da6b..ee123d84e 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -535,6 +535,12 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
                         }
                     });
 
+                    /* On macOS, accepted sockets inherit the
+                       non-blocking flag from the server socket, so
+                       explicitly make it blocking. */
+                    if (fcntl(fdServer.get(), F_SETFL, fcntl(fdServer.get(), F_GETFL) & ~O_NONBLOCK) == -1)
+                        abort();
+
                     while (true) {
                         try {
                             auto path = readLine(fdClient.get());

From 05fcc681ac07c4ea04b365e6b03a76f3e6c54c94 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 13 Dec 2021 16:14:57 +0100
Subject: [PATCH 320/567] Retry on ECONNREFUSED

https://hydra.nixos.org/build/161439235
---
 src/libstore/gc.cc | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index ee123d84e..fa68cd8f3 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -126,7 +126,17 @@ void LocalStore::addTempRoot(const StorePath & path)
             auto socketPath = stateDir.get() + gcSocketPath;
             debug("connecting to '%s'", socketPath);
             state->fdRootsSocket = createUnixDomainSocket();
-            nix::connect(state->fdRootsSocket.get(), socketPath);
+            try {
+                nix::connect(state->fdRootsSocket.get(), socketPath);
+            } catch (SysError & e) {
+                /* The garbage collector may have exited, so we need to
+                   restart. */
+                if (e.errNo == ECONNREFUSED) {
+                    debug("GC socket connection refused");
+                    state->fdRootsSocket.close();
+                    goto restart;
+                }
+            }
         }
 
         try {

From df1edd143fcb2532e32bbcb28f774ced1402cda4 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 13 Dec 2021 16:24:25 +0100
Subject: [PATCH 321/567] gc-non-blocking.sh: Don't hang indefinitely if the GC
 roots server crashes

---
 tests/gc-non-blocking.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/gc-non-blocking.sh b/tests/gc-non-blocking.sh
index 8b21c6f1c..0d781485d 100644
--- a/tests/gc-non-blocking.sh
+++ b/tests/gc-non-blocking.sh
@@ -19,7 +19,7 @@ pid=$!
 
 sleep 2
 
-outPath=$(nix-build -o "$TEST_ROOT/result" -E "
+outPath=$(nix-build --max-silent-time 60 -o "$TEST_ROOT/result" -E "
   with import ./config.nix;
   mkDerivation {
     name = \"non-blocking\";

From d17d46cfc2e38efb63565270a1fba7b03b37de16 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 13 Dec 2021 17:12:32 +0100
Subject: [PATCH 322/567] More debug info

---
 src/libstore/gc.cc | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index fa68cd8f3..e35199b3d 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -533,6 +533,8 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
                 AutoCloseFD fdClient = accept(fdServer.get(), nullptr, nullptr);
                 if (!fdClient) continue;
 
+                debug("GC roots server accepted new client");
+
                 /* Process the connection in a separate thread. */
                 auto fdClient_ = fdClient.get();
                 std::thread clientThread([&, fdClient = std::move(fdClient)]() {
@@ -575,7 +577,10 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
                             } else
                                 printError("received garbage instead of a root from client");
                             writeFull(fdClient.get(), "1", false);
-                        } catch (Error &) { break; }
+                        } catch (Error & e) {
+                            debug("reading GC root from client: %s", e.msg());
+                            break;
+                        }
                     }
                 });
 

From 2567b74c66ed52f752578373d4ec81ac2f09d6f0 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 13 Dec 2021 19:14:32 +0100
Subject: [PATCH 323/567] nix run: Tweak docs

---
 src/nix/run.md | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/nix/run.md b/src/nix/run.md
index 697db9a96..cd3b978c0 100644
--- a/src/nix/run.md
+++ b/src/nix/run.md
@@ -43,11 +43,15 @@ program specified by the app definition.
 
 If *installable* evaluates to a derivation, it will try to execute the
 program `<out>/bin/<name>`, where *out* is the primary output store
-path of the derivation and *name* is the `meta.mainProgram` attribute
-of the derivation if it exists, and otherwise the `pname` attribute of
-the derivation or the name part of the value of the `name` attribute of
-the derivation (e.g. if `name` is set to `hello-1.10`, it will run
-`$out/bin/hello`).
+path of the derivation, and *name* is the first of the following that
+exists:
+
+* The `meta.mainProgram` attribute of the derivation.
+* The `pname` attribute of the derivation.
+* The name part of the value of the `name` attribute of the derivation.
+
+For instance, if `name` is set to `hello-1.10`, `nix run` will run
+`$out/bin/hello`.
 
 # Flake output attributes
 

From e2e5f3a78f31e4e72170ebfe48cbbb082860cc24 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 13 Dec 2021 19:37:30 +0100
Subject: [PATCH 324/567] Respect /etc/hosts

https://hydra.nixos.org/build/161439329
---
 src/libmain/shared.cc | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index 4404e0195..f605184bb 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -145,10 +145,10 @@ static void preloadNSS() {
          *
          * All other platforms are unaffected.
          */
-        if (dlopen (LIBNSS_DNS_SO, RTLD_NOW) == NULL) {
-            printMsg(Verbosity::lvlWarn, fmt("Unable to load nss_dns backend"));
-        }
-        __nss_configure_lookup ("hosts", "dns");
+        if (!dlopen(LIBNSS_DNS_SO, RTLD_NOW))
+            warn("unable to load nss_dns backend");
+        // FIXME: get hosts entry from nsswitch.conf.
+        __nss_configure_lookup("hosts", "files dns");
 #endif
     });
 }

From 18cb094aab2e50c9b90e484592212bfce026b640 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 13 Dec 2021 19:57:06 +0100
Subject: [PATCH 325/567] rl-2.5.md: Set date

---
 doc/manual/src/release-notes/rl-2.5.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/manual/src/release-notes/rl-2.5.md b/doc/manual/src/release-notes/rl-2.5.md
index 61c189d22..dd6fd3b0f 100644
--- a/doc/manual/src/release-notes/rl-2.5.md
+++ b/doc/manual/src/release-notes/rl-2.5.md
@@ -1,4 +1,4 @@
-# Release 2.5 (2021-XX-XX)
+# Release 2.5 (2021-12-13)
 
 * The garbage collector no longer blocks new builds, so the message
   `waiting for the big garbage collector lock...` is a thing of the

From 46d86e06ba54dc708fa8fd7d0109845fa2ac402e Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 13 Dec 2021 20:28:53 +0100
Subject: [PATCH 326/567] Simplify

---
 src/libstore/build/local-derivation-goal.cc | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index edfa46052..66d950b42 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -1779,15 +1779,14 @@ void LocalDerivationGoal::runChild()
            i686-linux build on an x86_64-linux machine. */
         struct utsname utsbuf;
         uname(&utsbuf);
-        if (drv->platform == "i686-linux" &&
-            (settings.thisSystem == "x86_64-linux" ||
-             (!strcmp(utsbuf.sysname, "Linux") && !strcmp(utsbuf.machine, "x86_64")))) {
+        if ((drv->platform == "i686-linux"
+                && (settings.thisSystem == "x86_64-linux"
+                    || (!strcmp(utsbuf.sysname, "Linux") && !strcmp(utsbuf.machine, "x86_64"))))
+            || drv->platform == "armv7l-linux"
+            || drv->platform == "armv6l-linux")
+        {
             if (personality(PER_LINUX32) == -1)
-                throw SysError("cannot set i686-linux personality");
-        }
-        if (drv->platform == "armv7l-linux" || drv->platform == "armv6l-linux") {
-          if (personality(PER_LINUX32) == -1)
-            throw SysError("cannot set 32bit linux personality");
+                throw SysError("cannot set 32-bit personality");
         }
 
         /* Impersonate a Linux 2.6 machine to get some determinism in

From 32a62b0d25116ffe0d66ecaf6a479fbc915d196e Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 13 Dec 2021 20:54:43 +0100
Subject: [PATCH 327/567] Re-allow inputs.x.url = "/path/to/file"

---
 src/libexpr/flake/flake.cc    |  8 ++--
 src/libexpr/flake/flakeref.cc | 77 +++++++++++++++++++----------------
 src/libexpr/flake/flakeref.hh | 10 ++++-
 tests/flakes.sh               | 10 +++++
 4 files changed, 65 insertions(+), 40 deletions(-)

diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 33d253eee..f598400fc 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -155,7 +155,7 @@ static FlakeInput parseFlakeInput(EvalState & state,
         if (!attrs.empty())
             throw Error("unexpected flake input attribute '%s', at %s", attrs.begin()->first, pos);
         if (url)
-            input.ref = parseFlakeRef(*url, baseDir, true);
+            input.ref = parseFlakeRef(*url, baseDir, true, input.isFlake);
     }
 
     if (!input.follows && !input.ref)
@@ -194,8 +194,8 @@ static Flake getFlake(
         state, originalRef, allowLookup, flakeCache);
 
     // Guard against symlink attacks.
-    auto flakeDir = canonPath(sourceInfo.actualPath + "/" + lockedRef.subdir);
-    auto flakeFile = canonPath(flakeDir + "/flake.nix");
+    auto flakeDir = canonPath(sourceInfo.actualPath + "/" + lockedRef.subdir, true);
+    auto flakeFile = canonPath(flakeDir + "/flake.nix", true);
     if (!isInDir(flakeFile, sourceInfo.actualPath))
         throw Error("'flake.nix' file of flake '%s' escapes from '%s'",
             lockedRef, state.store->printStorePath(sourceInfo.storePath));
@@ -570,7 +570,7 @@ LockedFlake lockFlake(
         };
 
         // Bring in the current ref for relative path resolution if we have it
-        auto parentPath = canonPath(flake.sourceInfo->actualPath + "/" + flake.lockedRef.subdir);
+        auto parentPath = canonPath(flake.sourceInfo->actualPath + "/" + flake.lockedRef.subdir, true);
 
         computeLocks(
             flake.inputs, newLockFile.root, {},
diff --git a/src/libexpr/flake/flakeref.cc b/src/libexpr/flake/flakeref.cc
index 29128d789..c3b74e0fe 100644
--- a/src/libexpr/flake/flakeref.cc
+++ b/src/libexpr/flake/flakeref.cc
@@ -48,9 +48,12 @@ FlakeRef FlakeRef::resolve(ref<Store> store) const
 }
 
 FlakeRef parseFlakeRef(
-    const std::string & url, const std::optional<Path> & baseDir, bool allowMissing)
+    const std::string & url,
+    const std::optional<Path> & baseDir,
+    bool allowMissing,
+    bool isFlake)
 {
-    auto [flakeRef, fragment] = parseFlakeRefWithFragment(url, baseDir, allowMissing);
+    auto [flakeRef, fragment] = parseFlakeRefWithFragment(url, baseDir, allowMissing, isFlake);
     if (fragment != "")
         throw Error("unexpected fragment '%s' in flake reference '%s'", fragment, url);
     return flakeRef;
@@ -67,7 +70,10 @@ std::optional<FlakeRef> maybeParseFlakeRef(
 }
 
 std::pair<FlakeRef, std::string> parseFlakeRefWithFragment(
-    const std::string & url, const std::optional<Path> & baseDir, bool allowMissing)
+    const std::string & url,
+    const std::optional<Path> & baseDir,
+    bool allowMissing,
+    bool isFlake)
 {
     using namespace fetchers;
 
@@ -112,46 +118,49 @@ std::pair<FlakeRef, std::string> parseFlakeRefWithFragment(
                to 'baseDir'). If so, search upward to the root of the
                repo (i.e. the directory containing .git). */
 
-            path = absPath(path, baseDir, true);
+            path = absPath(path, baseDir);
 
-            if (!S_ISDIR(lstat(path).st_mode))
-                throw BadURL("path '%s' is not a flake (because it's not a directory)", path);
+            if (isFlake) {
 
-            if (!allowMissing && !pathExists(path + "/flake.nix"))
-                throw BadURL("path '%s' is not a flake (because it doesn't contain a 'flake.nix' file)", path);
+                if (!S_ISDIR(lstat(path).st_mode))
+                    throw BadURL("path '%s' is not a flake (because it's not a directory)", path);
 
-            auto flakeRoot = path;
-            std::string subdir;
+                if (!allowMissing && !pathExists(path + "/flake.nix"))
+                    throw BadURL("path '%s' is not a flake (because it doesn't contain a 'flake.nix' file)", path);
 
-            while (flakeRoot != "/") {
-                if (pathExists(flakeRoot + "/.git")) {
-                    auto base = std::string("git+file://") + flakeRoot;
+                auto flakeRoot = path;
+                std::string subdir;
 
-                    auto parsedURL = ParsedURL{
-                        .url = base, // FIXME
-                        .base = base,
-                        .scheme = "git+file",
-                        .authority = "",
-                        .path = flakeRoot,
-                        .query = decodeQuery(match[2]),
-                    };
+                while (flakeRoot != "/") {
+                    if (pathExists(flakeRoot + "/.git")) {
+                        auto base = std::string("git+file://") + flakeRoot;
 
-                    if (subdir != "") {
-                        if (parsedURL.query.count("dir"))
-                            throw Error("flake URL '%s' has an inconsistent 'dir' parameter", url);
-                        parsedURL.query.insert_or_assign("dir", subdir);
+                        auto parsedURL = ParsedURL{
+                            .url = base, // FIXME
+                            .base = base,
+                            .scheme = "git+file",
+                            .authority = "",
+                            .path = flakeRoot,
+                            .query = decodeQuery(match[2]),
+                        };
+
+                        if (subdir != "") {
+                            if (parsedURL.query.count("dir"))
+                                throw Error("flake URL '%s' has an inconsistent 'dir' parameter", url);
+                            parsedURL.query.insert_or_assign("dir", subdir);
+                        }
+
+                        if (pathExists(flakeRoot + "/.git/shallow"))
+                            parsedURL.query.insert_or_assign("shallow", "1");
+
+                        return std::make_pair(
+                            FlakeRef(Input::fromURL(parsedURL), get(parsedURL.query, "dir").value_or("")),
+                            fragment);
                     }
 
-                    if (pathExists(flakeRoot + "/.git/shallow"))
-                        parsedURL.query.insert_or_assign("shallow", "1");
-
-                    return std::make_pair(
-                        FlakeRef(Input::fromURL(parsedURL), get(parsedURL.query, "dir").value_or("")),
-                        fragment);
+                    subdir = std::string(baseNameOf(flakeRoot)) + (subdir.empty() ? "" : "/" + subdir);
+                    flakeRoot = dirOf(flakeRoot);
                 }
-
-                subdir = std::string(baseNameOf(flakeRoot)) + (subdir.empty() ? "" : "/" + subdir);
-                flakeRoot = dirOf(flakeRoot);
             }
 
         } else {
diff --git a/src/libexpr/flake/flakeref.hh b/src/libexpr/flake/flakeref.hh
index 0292eb210..1fddfd9a0 100644
--- a/src/libexpr/flake/flakeref.hh
+++ b/src/libexpr/flake/flakeref.hh
@@ -62,13 +62,19 @@ struct FlakeRef
 std::ostream & operator << (std::ostream & str, const FlakeRef & flakeRef);
 
 FlakeRef parseFlakeRef(
-    const std::string & url, const std::optional<Path> & baseDir = {}, bool allowMissing = false);
+    const std::string & url,
+    const std::optional<Path> & baseDir = {},
+    bool allowMissing = false,
+    bool isFlake = true);
 
 std::optional<FlakeRef> maybeParseFlake(
     const std::string & url, const std::optional<Path> & baseDir = {});
 
 std::pair<FlakeRef, std::string> parseFlakeRefWithFragment(
-    const std::string & url, const std::optional<Path> & baseDir = {}, bool allowMissing = false);
+    const std::string & url,
+    const std::optional<Path> & baseDir = {},
+    bool allowMissing = false,
+    bool isFlake = true);
 
 std::optional<std::pair<FlakeRef, std::string>> maybeParseFlakeRefWithFragment(
     const std::string & url, const std::optional<Path> & baseDir = {});
diff --git a/tests/flakes.sh b/tests/flakes.sh
index 20966ab2a..942d07010 100644
--- a/tests/flakes.sh
+++ b/tests/flakes.sh
@@ -249,6 +249,14 @@ cat > $flake3Dir/flake.nix <<EOF
       url = git+file://$nonFlakeDir;
       flake = false;
     };
+    nonFlakeFile = {
+      url = path://$nonFlakeDir/README.md;
+      flake = false;
+    };
+    nonFlakeFile2 = {
+      url = "$nonFlakeDir/README.md";
+      flake = false;
+    };
   };
 
   description = "Fnord";
@@ -265,6 +273,8 @@ cat > $flake3Dir/flake.nix <<EOF
         dummy2 = builtins.readFile (builtins.path { name = "source"; path = inputs.flake1; filter = path: type: baseNameOf path == "simple.nix"; } + "/simple.nix");
         buildCommand = ''
           cat \${inputs.nonFlake}/README.md > \$out
+          [[ \$(cat \${inputs.nonFlake}/README.md) = \$(cat \${inputs.nonFlakeFile}) ]]
+          [[ \${inputs.nonFlakeFile} = \${inputs.nonFlakeFile2} ]]
         '';
       };
   };

From 95bd5da341aec4b99f4719d1b1ab2343ee14fad7 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 13 Dec 2021 21:08:42 +0100
Subject: [PATCH 328/567] queryMissing(): Use a bigger thread pool

This is a temporary hack until we make queryMissing() async.

Closes #5324.
---
 src/libstore/misc.cc | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/libstore/misc.cc b/src/libstore/misc.cc
index 32786e963..6409874ff 100644
--- a/src/libstore/misc.cc
+++ b/src/libstore/misc.cc
@@ -7,6 +7,7 @@
 #include "topo-sort.hh"
 #include "callback.hh"
 #include "closure.hh"
+#include "filetransfer.hh"
 
 namespace nix {
 
@@ -100,7 +101,8 @@ void Store::queryMissing(const std::vector<DerivedPath> & targets,
 
     downloadSize_ = narSize_ = 0;
 
-    ThreadPool pool;
+    // FIXME: make async.
+    ThreadPool pool(fileTransferSettings.httpConnections);
 
     struct State
     {

From bcd4d2e4c6c8ec03ec8cf5d3558975c9152314d5 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 14 Dec 2021 00:01:42 +0100
Subject: [PATCH 329/567] Bump version

---
 .version | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.version b/.version
index fad066f80..914ec9671 100644
--- a/.version
+++ b/.version
@@ -1 +1 @@
-2.5.0
\ No newline at end of file
+2.6.0
\ No newline at end of file

From bb8a53ab08c43425c6073aff5fe34bd5bc93dd13 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Tue, 14 Dec 2021 09:15:24 +0100
Subject: [PATCH 330/567] Add a test for boolean config options in flakes

---
 tests/flake-local-settings.sh | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/flake-local-settings.sh b/tests/flake-local-settings.sh
index 09f6b4ca8..98ad60174 100644
--- a/tests/flake-local-settings.sh
+++ b/tests/flake-local-settings.sh
@@ -18,6 +18,7 @@ chmod +x echoing-post-hook.sh
 cat <<EOF > flake.nix
 {
     nixConfig.post-build-hook = "$PWD/echoing-post-hook.sh";
+    nixConfig.allow-dirty = false; # See #5621
 
     outputs = a: {
        defaultPackage.$system = import ./simple.nix;

From 1b6adfe18f17c90a56ab172e031d040815b3e1f3 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 15 Dec 2021 13:49:05 +0100
Subject: [PATCH 331/567] Revert "update flake.nix to 21.11"

This reverts commit ad9322a48fce955fb30b111b0fb5c3b8007a6e2e because
it breaks hydraJobs.buildStatic.* and the evaluation of some tests.
---
 flake.lock | 8 ++++----
 flake.nix  | 2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/flake.lock b/flake.lock
index 5fb200248..861af1c54 100644
--- a/flake.lock
+++ b/flake.lock
@@ -18,16 +18,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1638501222,
-        "narHash": "sha256-tgOZW/rLcB4P7iffx88K3iF70YH+44PtV6kVg5YGIg0=",
+        "lastModified": 1632864508,
+        "narHash": "sha256-d127FIvGR41XbVRDPVvozUPQ/uRHbHwvfyKHwEt5xFM=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "45c527ae2de6f2f36d5790273343f06cd14bc0d1",
+        "rev": "82891b5e2c2359d7e58d08849e4c89511ab94234",
         "type": "github"
       },
       "original": {
         "id": "nixpkgs",
-        "ref": "nixos-21.11-small",
+        "ref": "nixos-21.05-small",
         "type": "indirect"
       }
     },
diff --git a/flake.nix b/flake.nix
index 942388ab4..9a5d188ae 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,7 +1,7 @@
 {
   description = "The purely functional package manager";
 
-  inputs.nixpkgs.url = "nixpkgs/nixos-21.11-small";
+  inputs.nixpkgs.url = "nixpkgs/nixos-21.05-small";
   inputs.lowdown-src = { url = "github:kristapsdz/lowdown"; flake = false; };
 
   outputs = { self, nixpkgs, lowdown-src }:

From f66923efdefa5160222b6d6ef0dd9fa822242116 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 15 Dec 2021 19:13:06 +0100
Subject: [PATCH 332/567] pkgconfig -> pkg-config

---
 flake.nix | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/flake.nix b/flake.nix
index 9a5d188ae..806ed45de 100644
--- a/flake.nix
+++ b/flake.nix
@@ -96,7 +96,7 @@
             buildPackages.mdbook
             buildPackages.autoconf-archive
             buildPackages.autoreconfHook
-            buildPackages.pkgconfig
+            buildPackages.pkg-config
 
             # Tests
             buildPackages.git
@@ -343,7 +343,7 @@
             nativeBuildInputs =
               [ buildPackages.autoconf-archive
                 buildPackages.autoreconfHook
-                buildPackages.pkgconfig
+                buildPackages.pkg-config
               ];
 
             buildInputs =

From 11ee875a6deaba021e7ea4e3f6c3563e3fab1425 Mon Sep 17 00:00:00 2001
From: jesse <brennan@ucsc.edu>
Date: Wed, 15 Dec 2021 10:53:03 -0800
Subject: [PATCH 333/567] List aarch64 as supported macOS hardware

Resolves #5767
---
 doc/manual/src/installation/supported-platforms.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/manual/src/installation/supported-platforms.md b/doc/manual/src/installation/supported-platforms.md
index 8ef1f0e78..8ca3ce8d4 100644
--- a/doc/manual/src/installation/supported-platforms.md
+++ b/doc/manual/src/installation/supported-platforms.md
@@ -4,4 +4,4 @@ Nix is currently supported on the following platforms:
 
   - Linux (i686, x86\_64, aarch64).
 
-  - macOS (x86\_64).
+  - macOS (x86\_64, aarch64).

From c3f9344cae1921e4ddf1568469d063c2bba787dc Mon Sep 17 00:00:00 2001
From: Noah Snelson <noah.snelson@protonmail.com>
Date: Wed, 15 Dec 2021 23:40:37 -0800
Subject: [PATCH 334/567] Fix typo in `src/nix/shell.md`

Changed `If not command` to `If no command`, also specified that the
default shell launched in `nix shell` can be specified with `$SHELL`.
---
 src/nix/shell.md | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/nix/shell.md b/src/nix/shell.md
index 2a379e03f..90b81fb2f 100644
--- a/src/nix/shell.md
+++ b/src/nix/shell.md
@@ -41,8 +41,8 @@ R""(
 
 # Description
 
-`nix shell` runs a command in an environment in which the `$PATH`
-variable provides the specified *installables*. If not command is
-specified, it starts the default shell of your user account.
+`nix shell` runs a command in an environment in which the `$PATH` variable
+provides the specified *installables*. If no command is specified, it starts the
+default shell of your user account specified by `$SHELL`.
 
 )""

From 6942ee8a84f695332149f9a14046b51f2cb6462c Mon Sep 17 00:00:00 2001
From: John Axel Eriksson <john@insane.se>
Date: Thu, 16 Dec 2021 11:29:05 +0100
Subject: [PATCH 335/567] docker: fix image so that nix profile works

nix profile will otherwise throw this error:

error: path '/nix/var/nix/profiles/default/manifest.nix' is not in the Nix store

That's not entirely true since manifest.nix is within a directory in
the nix store but nix profile seems to require the manifest.nix itself
to be a store path.
---
 docker.nix | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/docker.nix b/docker.nix
index 2a13c23fb..ffb553f78 100644
--- a/docker.nix
+++ b/docker.nix
@@ -137,11 +137,8 @@ let
         name = "root-profile-env";
         paths = defaultPkgs;
       };
-      profile = pkgs.buildPackages.runCommand "user-environment" { } ''
-        mkdir $out
-        cp -a ${rootEnv}/* $out/
-
-        cat > $out/manifest.nix <<EOF
+      manifest = pkgs.buildPackages.runCommand "manifest.nix" { } ''
+        cat > $out <<EOF
         [
         ${lib.concatStringsSep "\n" (builtins.map (drv: let
           outputs = drv.outputsToInstall or [ "out" ];
@@ -161,6 +158,11 @@ let
         ]
         EOF
       '';
+      profile = pkgs.buildPackages.runCommand "user-environment" { } ''
+        mkdir $out
+        cp -a ${rootEnv}/* $out/
+        ln -s ${manifest} $out/manifest.nix
+      '';
     in
     pkgs.runCommand "base-system"
       {

From d9fbe3e20860be305c9d42945b4d0ef73067007e Mon Sep 17 00:00:00 2001
From: Silvan Mosberger <contact@infinisil.com>
Date: Thu, 16 Dec 2021 19:59:13 +0100
Subject: [PATCH 336/567] Add a test case for builtins.groupBy

---
 tests/lang/eval-okay-groupBy.exp | 1 +
 tests/lang/eval-okay-groupBy.nix | 5 +++++
 2 files changed, 6 insertions(+)
 create mode 100644 tests/lang/eval-okay-groupBy.exp
 create mode 100644 tests/lang/eval-okay-groupBy.nix

diff --git a/tests/lang/eval-okay-groupBy.exp b/tests/lang/eval-okay-groupBy.exp
new file mode 100644
index 000000000..bfca5652a
--- /dev/null
+++ b/tests/lang/eval-okay-groupBy.exp
@@ -0,0 +1 @@
+{ "1" = [ 9 ]; "2" = [ 8 ]; "3" = [ 13 29 ]; "4" = [ 3 4 10 11 17 18 ]; "5" = [ 0 23 26 28 ]; "6" = [ 1 12 21 27 30 ]; "7" = [ 7 22 ]; "8" = [ 14 ]; "9" = [ 19 ]; b = [ 16 25 ]; c = [ 24 ]; d = [ 2 ]; e = [ 5 6 15 31 ]; f = [ 20 ]; }
diff --git a/tests/lang/eval-okay-groupBy.nix b/tests/lang/eval-okay-groupBy.nix
new file mode 100644
index 000000000..862d89dbd
--- /dev/null
+++ b/tests/lang/eval-okay-groupBy.nix
@@ -0,0 +1,5 @@
+with import ./lib.nix;
+
+builtins.groupBy (n:
+  builtins.substring 0 1 (builtins.hashString "sha256" (toString n))
+) (range 0 31)

From c260640dec6e35c714b666a1e7adede5aab6972a Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 16 Dec 2021 21:48:38 +0100
Subject: [PATCH 337/567] Fix docker instructions

---
 doc/manual/src/installation/installing-docker.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/doc/manual/src/installation/installing-docker.md b/doc/manual/src/installation/installing-docker.md
index ee7614bdb..9d6d8f2d9 100644
--- a/doc/manual/src/installation/installing-docker.md
+++ b/doc/manual/src/installation/installing-docker.md
@@ -16,7 +16,7 @@ nix (Nix) 2.3.12
 35ca4ada6e96:/# exit
 ```
 
-# What is included in Nix' Docker image?
+# What is included in Nix's Docker image?
 
 The official Docker image is created using `pkgs.dockerTools.buildLayeredImage`
 (and not with `Dockerfile` as it is usual with Docker images). You can still
@@ -54,6 +54,6 @@ You can also build a Docker image from source yourself:
 
 ```console
 $ nix build ./\#hydraJobs.dockerImage.x86_64-linux
-$ docker load -i ./result
+$ docker load -i ./result/image.tar.gz
 $ docker run -ti nix:2.5pre20211105
 ```

From ec8f24ed3a3115cba85f908515c423112e5b13e0 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 16 Dec 2021 21:26:22 +0100
Subject: [PATCH 338/567] Ignore EPERM when unsharing FS state

On Docker (but not podman), unshare(CLONE_FS) fails with EPERM. So
let's ignore it and hope nothing bad happens.

Attempted fix for #5777.
---
 src/libstore/filetransfer.cc | 8 +-------
 src/libutil/util.cc          | 8 ++++++++
 src/libutil/util.hh          | 5 +++++
 3 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/src/libstore/filetransfer.cc b/src/libstore/filetransfer.cc
index 4621a8217..17980ab22 100644
--- a/src/libstore/filetransfer.cc
+++ b/src/libstore/filetransfer.cc
@@ -544,13 +544,7 @@ struct curlFileTransfer : public FileTransfer
             stopWorkerThread();
         });
 
-#ifdef __linux__
-        /* Cause this thread to not share any FS attributes with the main thread,
-           because this causes setns() in restoreMountNamespace() to fail.
-           Ideally, this would happen in the std::thread() constructor. */
-        if (unshare(CLONE_FS) != 0)
-            throw SysError("unsharing filesystem state in download thread");
-#endif
+        unshareFilesystem();
 
         std::map<CURL *, std::shared_ptr<TransferItem>> items;
 
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 1b6467eb2..43fea1b1e 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1660,6 +1660,14 @@ void restoreMountNamespace()
 #endif
 }
 
+void unshareFilesystem()
+{
+#ifdef __linux__
+    if (unshare(CLONE_FS) != 0 && errno != EPERM)
+        throw SysError("unsharing filesystem state in download thread");
+#endif
+}
+
 void restoreProcessContext(bool restoreMounts)
 {
     restoreSignals();
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index bc96bfed1..4cc043a84 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -311,6 +311,11 @@ void saveMountNamespace();
    if saveMountNamespace() was never called. */
 void restoreMountNamespace();
 
+/* Cause this thread to not share any FS attributes with the main
+   thread, because this causes setns() in restoreMountNamespace() to
+   fail. */
+void unshareFilesystem();
+
 
 class ExecError : public Error
 {

From 6f1b3d711e6174286ae8ecb83c5d8a348e9fa2c3 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Fri, 17 Dec 2021 09:14:28 +0100
Subject: [PATCH 339/567] Test the update of multiple channels
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Make sure that `nix-channel --update` won’t accidentaly remove one
---
 tests/nix-channel.sh | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/tests/nix-channel.sh b/tests/nix-channel.sh
index 63c0f97ba..54b8f5979 100644
--- a/tests/nix-channel.sh
+++ b/tests/nix-channel.sh
@@ -35,16 +35,14 @@ grep -q 'item.*attrPath="foo".*name="dependencies-top"' $TEST_ROOT/meta.xml
 nix-env -i dependencies-top
 [ -e $TEST_HOME/.nix-profile/foobar ]
 
-clearProfiles
-rm -f $TEST_HOME/.nix-channels
-
 # Test updating from a tarball
-nix-channel --add file://$TEST_ROOT/foo/nixexprs.tar.bz2 foo
+nix-channel --add file://$TEST_ROOT/foo/nixexprs.tar.bz2 bar
 nix-channel --update
 
 # Do a query.
 nix-env -qa \* --meta --xml --out-path > $TEST_ROOT/meta.xml
 grep -q 'meta.*description.*Random test package' $TEST_ROOT/meta.xml
+grep -q 'item.*attrPath="bar".*name="dependencies-top"' $TEST_ROOT/meta.xml
 grep -q 'item.*attrPath="foo".*name="dependencies-top"' $TEST_ROOT/meta.xml
 
 # Do an install.

From ab902521b131c6a642d8cdcfe28d61b5dfe764a2 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Fri, 12 Nov 2021 16:28:39 +0100
Subject: [PATCH 340/567] Allow paths in flake local settings

Fix #5505
---
 src/libexpr/flake/flake.cc    |  4 ++++
 tests/flake-local-settings.sh | 14 ++++++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index b15878d5c..ed753c7e4 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -251,6 +251,10 @@ static Flake getFlake(
             forceTrivialValue(state, *setting.value, *setting.pos);
             if (setting.value->type() == nString)
                 flake.config.settings.insert({setting.name, state.forceStringNoCtx(*setting.value, *setting.pos)});
+            else if (setting.value->type() == nPath) {
+                PathSet emptyContext = {};
+                flake.config.settings.insert({setting.name, state.coerceToString(*setting.pos, *setting.value, emptyContext, false, true, true)});
+            }
             else if (setting.value->type() == nInt)
                 flake.config.settings.insert({setting.name, state.forceInt(*setting.value, *setting.pos)});
             else if (setting.value->type() == nBool)
diff --git a/tests/flake-local-settings.sh b/tests/flake-local-settings.sh
index 98ad60174..7765fe379 100644
--- a/tests/flake-local-settings.sh
+++ b/tests/flake-local-settings.sh
@@ -11,13 +11,13 @@ rm -f post-hook-ran
 cat <<EOF > echoing-post-hook.sh
 #!/bin/sh
 
-echo "ThePostHookRan" > $PWD/post-hook-ran
+echo "ThePostHookRan as \$0" > $PWD/post-hook-ran
 EOF
 chmod +x echoing-post-hook.sh
 
 cat <<EOF > flake.nix
 {
-    nixConfig.post-build-hook = "$PWD/echoing-post-hook.sh";
+    nixConfig.post-build-hook = ./echoing-post-hook.sh;
     nixConfig.allow-dirty = false; # See #5621
 
     outputs = a: {
@@ -33,3 +33,13 @@ clearStore
 
 nix build --accept-flake-config
 test -f post-hook-ran || fail "The post hook should have ran"
+
+# Make sure that the path to the post hook doesn’t change if we change
+# something in the flake.
+# Otherwise the user would have to re-validate the setting each time.
+mv post-hook-ran previous-post-hook-run
+echo "# Dummy comment" >> flake.nix
+clearStore
+nix build --accept-flake-config
+diff -q post-hook-ran previous-post-hook-run || \
+    fail "Both post hook runs should report the same filename"

From c3f68b5db7b9d4b963102a2abc20e20445a8bec5 Mon Sep 17 00:00:00 2001
From: Nicolas Mattia <nicolas@nmattia.com>
Date: Fri, 17 Dec 2021 22:03:33 +0100
Subject: [PATCH 341/567] Replace cpptoml with toml11

---
 src/cpptoml/LICENSE                 |   18 -
 src/cpptoml/cpptoml.h               | 3668 ---------------------------
 src/toml11/LICENSE                  |   21 +
 src/toml11/README.md                | 1966 ++++++++++++++
 src/toml11/toml.hpp                 |   46 +
 src/toml11/toml/color.hpp           |   64 +
 src/toml11/toml/combinator.hpp      |  306 +++
 src/toml11/toml/comments.hpp        |  472 ++++
 src/toml11/toml/datetime.hpp        |  631 +++++
 src/toml11/toml/exception.hpp       |   65 +
 src/toml11/toml/from.hpp            |   19 +
 src/toml11/toml/get.hpp             | 1117 ++++++++
 src/toml11/toml/into.hpp            |   19 +
 src/toml11/toml/lexer.hpp           |  293 +++
 src/toml11/toml/literal.hpp         |  113 +
 src/toml11/toml/macros.hpp          |  121 +
 src/toml11/toml/parser.hpp          | 2364 +++++++++++++++++
 src/toml11/toml/region.hpp          |  417 +++
 src/toml11/toml/result.hpp          |  717 ++++++
 src/toml11/toml/serializer.hpp      |  922 +++++++
 src/toml11/toml/source_location.hpp |  233 ++
 src/toml11/toml/storage.hpp         |   43 +
 src/toml11/toml/string.hpp          |  225 ++
 src/toml11/toml/traits.hpp          |  327 +++
 src/toml11/toml/types.hpp           |  173 ++
 src/toml11/toml/utility.hpp         |  149 ++
 src/toml11/toml/value.hpp           | 2035 +++++++++++++++
 27 files changed, 12858 insertions(+), 3686 deletions(-)
 delete mode 100644 src/cpptoml/LICENSE
 delete mode 100644 src/cpptoml/cpptoml.h
 create mode 100644 src/toml11/LICENSE
 create mode 100644 src/toml11/README.md
 create mode 100644 src/toml11/toml.hpp
 create mode 100644 src/toml11/toml/color.hpp
 create mode 100644 src/toml11/toml/combinator.hpp
 create mode 100644 src/toml11/toml/comments.hpp
 create mode 100644 src/toml11/toml/datetime.hpp
 create mode 100644 src/toml11/toml/exception.hpp
 create mode 100644 src/toml11/toml/from.hpp
 create mode 100644 src/toml11/toml/get.hpp
 create mode 100644 src/toml11/toml/into.hpp
 create mode 100644 src/toml11/toml/lexer.hpp
 create mode 100644 src/toml11/toml/literal.hpp
 create mode 100644 src/toml11/toml/macros.hpp
 create mode 100644 src/toml11/toml/parser.hpp
 create mode 100644 src/toml11/toml/region.hpp
 create mode 100644 src/toml11/toml/result.hpp
 create mode 100644 src/toml11/toml/serializer.hpp
 create mode 100644 src/toml11/toml/source_location.hpp
 create mode 100644 src/toml11/toml/storage.hpp
 create mode 100644 src/toml11/toml/string.hpp
 create mode 100644 src/toml11/toml/traits.hpp
 create mode 100644 src/toml11/toml/types.hpp
 create mode 100644 src/toml11/toml/utility.hpp
 create mode 100644 src/toml11/toml/value.hpp

diff --git a/src/cpptoml/LICENSE b/src/cpptoml/LICENSE
deleted file mode 100644
index 8802c4fa5..000000000
--- a/src/cpptoml/LICENSE
+++ /dev/null
@@ -1,18 +0,0 @@
-Copyright (c) 2014 Chase Geigle
-
-Permission is hereby granted, free of charge, to any person obtaining a copy of
-this software and associated documentation files (the "Software"), to deal in
-the Software without restriction, including without limitation the rights to
-use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
-the Software, and to permit persons to whom the Software is furnished to do so,
-subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
-FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
-COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
-IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
-CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/src/cpptoml/cpptoml.h b/src/cpptoml/cpptoml.h
deleted file mode 100644
index 5a00da3b4..000000000
--- a/src/cpptoml/cpptoml.h
+++ /dev/null
@@ -1,3668 +0,0 @@
-/**
- * @file cpptoml.h
- * @author Chase Geigle
- * @date May 2013
- */
-
-#ifndef CPPTOML_H
-#define CPPTOML_H
-
-#include <algorithm>
-#include <cassert>
-#include <clocale>
-#include <cstdint>
-#include <cstring>
-#include <fstream>
-#include <iomanip>
-#include <map>
-#include <memory>
-#include <sstream>
-#include <stdexcept>
-#include <string>
-#include <unordered_map>
-#include <vector>
-
-#if __cplusplus > 201103L
-#define CPPTOML_DEPRECATED(reason) [[deprecated(reason)]]
-#elif defined(__clang__)
-#define CPPTOML_DEPRECATED(reason) __attribute__((deprecated(reason)))
-#elif defined(__GNUG__)
-#define CPPTOML_DEPRECATED(reason) __attribute__((deprecated))
-#elif defined(_MSC_VER)
-#if _MSC_VER < 1910
-#define CPPTOML_DEPRECATED(reason) __declspec(deprecated)
-#else
-#define CPPTOML_DEPRECATED(reason) [[deprecated(reason)]]
-#endif
-#endif
-
-namespace cpptoml
-{
-class writer; // forward declaration
-class base;   // forward declaration
-#if defined(CPPTOML_USE_MAP)
-// a std::map will ensure that entries a sorted, albeit at a slight
-// performance penalty relative to the (default) unordered_map
-using string_to_base_map = std::map<std::string, std::shared_ptr<base>>;
-#else
-// by default an unordered_map is used for best performance as the
-// toml specification does not require entries to be sorted
-using string_to_base_map
-    = std::unordered_map<std::string, std::shared_ptr<base>>;
-#endif
-
-// if defined, `base` will retain type information in form of an enum class
-// such that static_cast can be used instead of dynamic_cast
-// #define CPPTOML_NO_RTTI
-
-template <class T>
-class option
-{
-  public:
-    option() : empty_{true}
-    {
-        // nothing
-    }
-
-    option(T value) : empty_{false}, value_(std::move(value))
-    {
-        // nothing
-    }
-
-    explicit operator bool() const
-    {
-        return !empty_;
-    }
-
-    const T& operator*() const
-    {
-        return value_;
-    }
-
-    const T* operator->() const
-    {
-        return &value_;
-    }
-
-    template <class U>
-    T value_or(U&& alternative) const
-    {
-        if (!empty_)
-            return value_;
-        return static_cast<T>(std::forward<U>(alternative));
-    }
-
-  private:
-    bool empty_;
-    T value_;
-};
-
-struct local_date
-{
-    int year = 0;
-    int month = 0;
-    int day = 0;
-};
-
-struct local_time
-{
-    int hour = 0;
-    int minute = 0;
-    int second = 0;
-    int microsecond = 0;
-};
-
-struct zone_offset
-{
-    int hour_offset = 0;
-    int minute_offset = 0;
-};
-
-struct local_datetime : local_date, local_time
-{
-};
-
-struct offset_datetime : local_datetime, zone_offset
-{
-    static inline struct offset_datetime from_zoned(const struct tm& t)
-    {
-        offset_datetime dt;
-        dt.year = t.tm_year + 1900;
-        dt.month = t.tm_mon + 1;
-        dt.day = t.tm_mday;
-        dt.hour = t.tm_hour;
-        dt.minute = t.tm_min;
-        dt.second = t.tm_sec;
-
-        char buf[16];
-        strftime(buf, 16, "%z", &t);
-
-        int offset = std::stoi(buf);
-        dt.hour_offset = offset / 100;
-        dt.minute_offset = offset % 100;
-        return dt;
-    }
-
-    CPPTOML_DEPRECATED("from_local has been renamed to from_zoned")
-    static inline struct offset_datetime from_local(const struct tm& t)
-    {
-        return from_zoned(t);
-    }
-
-    static inline struct offset_datetime from_utc(const struct tm& t)
-    {
-        offset_datetime dt;
-        dt.year = t.tm_year + 1900;
-        dt.month = t.tm_mon + 1;
-        dt.day = t.tm_mday;
-        dt.hour = t.tm_hour;
-        dt.minute = t.tm_min;
-        dt.second = t.tm_sec;
-        return dt;
-    }
-};
-
-CPPTOML_DEPRECATED("datetime has been renamed to offset_datetime")
-typedef offset_datetime datetime;
-
-class fill_guard
-{
-  public:
-    fill_guard(std::ostream& os) : os_(os), fill_{os.fill()}
-    {
-        // nothing
-    }
-
-    ~fill_guard()
-    {
-        os_.fill(fill_);
-    }
-
-  private:
-    std::ostream& os_;
-    std::ostream::char_type fill_;
-};
-
-inline std::ostream& operator<<(std::ostream& os, const local_date& dt)
-{
-    fill_guard g{os};
-    os.fill('0');
-
-    using std::setw;
-    os << setw(4) << dt.year << "-" << setw(2) << dt.month << "-" << setw(2)
-       << dt.day;
-
-    return os;
-}
-
-inline std::ostream& operator<<(std::ostream& os, const local_time& ltime)
-{
-    fill_guard g{os};
-    os.fill('0');
-
-    using std::setw;
-    os << setw(2) << ltime.hour << ":" << setw(2) << ltime.minute << ":"
-       << setw(2) << ltime.second;
-
-    if (ltime.microsecond > 0)
-    {
-        os << ".";
-        int power = 100000;
-        for (int curr_us = ltime.microsecond; curr_us; power /= 10)
-        {
-            auto num = curr_us / power;
-            os << num;
-            curr_us -= num * power;
-        }
-    }
-
-    return os;
-}
-
-inline std::ostream& operator<<(std::ostream& os, const zone_offset& zo)
-{
-    fill_guard g{os};
-    os.fill('0');
-
-    using std::setw;
-
-    if (zo.hour_offset != 0 || zo.minute_offset != 0)
-    {
-        if (zo.hour_offset > 0)
-        {
-            os << "+";
-        }
-        else
-        {
-            os << "-";
-        }
-        os << setw(2) << std::abs(zo.hour_offset) << ":" << setw(2)
-           << std::abs(zo.minute_offset);
-    }
-    else
-    {
-        os << "Z";
-    }
-
-    return os;
-}
-
-inline std::ostream& operator<<(std::ostream& os, const local_datetime& dt)
-{
-    return os << static_cast<const local_date&>(dt) << "T"
-              << static_cast<const local_time&>(dt);
-}
-
-inline std::ostream& operator<<(std::ostream& os, const offset_datetime& dt)
-{
-    return os << static_cast<const local_datetime&>(dt)
-              << static_cast<const zone_offset&>(dt);
-}
-
-template <class T, class... Ts>
-struct is_one_of;
-
-template <class T, class V>
-struct is_one_of<T, V> : std::is_same<T, V>
-{
-};
-
-template <class T, class V, class... Ts>
-struct is_one_of<T, V, Ts...>
-{
-    const static bool value
-        = std::is_same<T, V>::value || is_one_of<T, Ts...>::value;
-};
-
-template <class T>
-class value;
-
-template <class T>
-struct valid_value
-    : is_one_of<T, std::string, int64_t, double, bool, local_date, local_time,
-                local_datetime, offset_datetime>
-{
-};
-
-template <class T, class Enable = void>
-struct value_traits;
-
-template <class T>
-struct valid_value_or_string_convertible
-{
-
-    const static bool value = valid_value<typename std::decay<T>::type>::value
-                              || std::is_convertible<T, std::string>::value;
-};
-
-template <class T>
-struct value_traits<T, typename std::enable_if<
-                           valid_value_or_string_convertible<T>::value>::type>
-{
-    using value_type = typename std::conditional<
-        valid_value<typename std::decay<T>::type>::value,
-        typename std::decay<T>::type, std::string>::type;
-
-    using type = value<value_type>;
-
-    static value_type construct(T&& val)
-    {
-        return value_type(val);
-    }
-};
-
-template <class T>
-struct value_traits<
-    T,
-    typename std::enable_if<
-        !valid_value_or_string_convertible<T>::value
-        && std::is_floating_point<typename std::decay<T>::type>::value>::type>
-{
-    using value_type = typename std::decay<T>::type;
-
-    using type = value<double>;
-
-    static value_type construct(T&& val)
-    {
-        return value_type(val);
-    }
-};
-
-template <class T>
-struct value_traits<
-    T, typename std::enable_if<
-           !valid_value_or_string_convertible<T>::value
-           && !std::is_floating_point<typename std::decay<T>::type>::value
-           && std::is_signed<typename std::decay<T>::type>::value>::type>
-{
-    using value_type = int64_t;
-
-    using type = value<int64_t>;
-
-    static value_type construct(T&& val)
-    {
-        if (val < (std::numeric_limits<int64_t>::min)())
-            throw std::underflow_error{"constructed value cannot be "
-                                       "represented by a 64-bit signed "
-                                       "integer"};
-
-        if (val > (std::numeric_limits<int64_t>::max)())
-            throw std::overflow_error{"constructed value cannot be represented "
-                                      "by a 64-bit signed integer"};
-
-        return static_cast<int64_t>(val);
-    }
-};
-
-template <class T>
-struct value_traits<
-    T, typename std::enable_if<
-           !valid_value_or_string_convertible<T>::value
-           && std::is_unsigned<typename std::decay<T>::type>::value>::type>
-{
-    using value_type = int64_t;
-
-    using type = value<int64_t>;
-
-    static value_type construct(T&& val)
-    {
-        if (val > static_cast<uint64_t>((std::numeric_limits<int64_t>::max)()))
-            throw std::overflow_error{"constructed value cannot be represented "
-                                      "by a 64-bit signed integer"};
-
-        return static_cast<int64_t>(val);
-    }
-};
-
-class array;
-class table;
-class table_array;
-
-template <class T>
-struct array_of_trait
-{
-    using return_type = option<std::vector<T>>;
-};
-
-template <>
-struct array_of_trait<array>
-{
-    using return_type = option<std::vector<std::shared_ptr<array>>>;
-};
-
-template <class T>
-inline std::shared_ptr<typename value_traits<T>::type> make_value(T&& val);
-inline std::shared_ptr<array> make_array();
-
-namespace detail
-{
-template <class T>
-inline std::shared_ptr<T> make_element();
-}
-
-inline std::shared_ptr<table> make_table();
-inline std::shared_ptr<table_array> make_table_array(bool is_inline = false);
-
-#if defined(CPPTOML_NO_RTTI)
-/// Base type used to store underlying data type explicitly if RTTI is disabled
-enum class base_type
-{
-    NONE,
-    STRING,
-    LOCAL_TIME,
-    LOCAL_DATE,
-    LOCAL_DATETIME,
-    OFFSET_DATETIME,
-    INT,
-    FLOAT,
-    BOOL,
-    TABLE,
-    ARRAY,
-    TABLE_ARRAY
-};
-
-/// Type traits class to convert C++ types to enum member
-template <class T>
-struct base_type_traits;
-
-template <>
-struct base_type_traits<std::string>
-{
-    static const base_type type = base_type::STRING;
-};
-
-template <>
-struct base_type_traits<local_time>
-{
-    static const base_type type = base_type::LOCAL_TIME;
-};
-
-template <>
-struct base_type_traits<local_date>
-{
-    static const base_type type = base_type::LOCAL_DATE;
-};
-
-template <>
-struct base_type_traits<local_datetime>
-{
-    static const base_type type = base_type::LOCAL_DATETIME;
-};
-
-template <>
-struct base_type_traits<offset_datetime>
-{
-    static const base_type type = base_type::OFFSET_DATETIME;
-};
-
-template <>
-struct base_type_traits<int64_t>
-{
-    static const base_type type = base_type::INT;
-};
-
-template <>
-struct base_type_traits<double>
-{
-    static const base_type type = base_type::FLOAT;
-};
-
-template <>
-struct base_type_traits<bool>
-{
-    static const base_type type = base_type::BOOL;
-};
-
-template <>
-struct base_type_traits<table>
-{
-    static const base_type type = base_type::TABLE;
-};
-
-template <>
-struct base_type_traits<array>
-{
-    static const base_type type = base_type::ARRAY;
-};
-
-template <>
-struct base_type_traits<table_array>
-{
-    static const base_type type = base_type::TABLE_ARRAY;
-};
-#endif
-
-/**
- * A generic base TOML value used for type erasure.
- */
-class base : public std::enable_shared_from_this<base>
-{
-  public:
-    virtual ~base() = default;
-
-    virtual std::shared_ptr<base> clone() const = 0;
-
-    /**
-     * Determines if the given TOML element is a value.
-     */
-    virtual bool is_value() const
-    {
-        return false;
-    }
-
-    /**
-     * Determines if the given TOML element is a table.
-     */
-    virtual bool is_table() const
-    {
-        return false;
-    }
-
-    /**
-     * Converts the TOML element into a table.
-     */
-    std::shared_ptr<table> as_table()
-    {
-        if (is_table())
-            return std::static_pointer_cast<table>(shared_from_this());
-        return nullptr;
-    }
-    /**
-     * Determines if the TOML element is an array of "leaf" elements.
-     */
-    virtual bool is_array() const
-    {
-        return false;
-    }
-
-    /**
-     * Converts the TOML element to an array.
-     */
-    std::shared_ptr<array> as_array()
-    {
-        if (is_array())
-            return std::static_pointer_cast<array>(shared_from_this());
-        return nullptr;
-    }
-
-    /**
-     * Determines if the given TOML element is an array of tables.
-     */
-    virtual bool is_table_array() const
-    {
-        return false;
-    }
-
-    /**
-     * Converts the TOML element into a table array.
-     */
-    std::shared_ptr<table_array> as_table_array()
-    {
-        if (is_table_array())
-            return std::static_pointer_cast<table_array>(shared_from_this());
-        return nullptr;
-    }
-
-    /**
-     * Attempts to coerce the TOML element into a concrete TOML value
-     * of type T.
-     */
-    template <class T>
-    std::shared_ptr<value<T>> as();
-
-    template <class T>
-    std::shared_ptr<const value<T>> as() const;
-
-    template <class Visitor, class... Args>
-    void accept(Visitor&& visitor, Args&&... args) const;
-
-#if defined(CPPTOML_NO_RTTI)
-    base_type type() const
-    {
-        return type_;
-    }
-
-  protected:
-    base(const base_type t) : type_(t)
-    {
-        // nothing
-    }
-
-  private:
-    const base_type type_ = base_type::NONE;
-
-#else
-  protected:
-    base()
-    {
-        // nothing
-    }
-#endif
-};
-
-/**
- * A concrete TOML value representing the "leaves" of the "tree".
- */
-template <class T>
-class value : public base
-{
-    struct make_shared_enabler
-    {
-        // nothing; this is a private key accessible only to friends
-    };
-
-    template <class U>
-    friend std::shared_ptr<typename value_traits<U>::type>
-    cpptoml::make_value(U&& val);
-
-  public:
-    static_assert(valid_value<T>::value, "invalid value type");
-
-    std::shared_ptr<base> clone() const override;
-
-    value(const make_shared_enabler&, const T& val) : value(val)
-    {
-        // nothing; note that users cannot actually invoke this function
-        // because they lack access to the make_shared_enabler.
-    }
-
-    bool is_value() const override
-    {
-        return true;
-    }
-
-    /**
-     * Gets the data associated with this value.
-     */
-    T& get()
-    {
-        return data_;
-    }
-
-    /**
-     * Gets the data associated with this value. Const version.
-     */
-    const T& get() const
-    {
-        return data_;
-    }
-
-  private:
-    T data_;
-
-    /**
-     * Constructs a value from the given data.
-     */
-#if defined(CPPTOML_NO_RTTI)
-    value(const T& val) : base(base_type_traits<T>::type), data_(val)
-    {
-    }
-#else
-    value(const T& val) : data_(val)
-    {
-    }
-#endif
-
-    value(const value& val) = delete;
-    value& operator=(const value& val) = delete;
-};
-
-template <class T>
-std::shared_ptr<typename value_traits<T>::type> make_value(T&& val)
-{
-    using value_type = typename value_traits<T>::type;
-    using enabler = typename value_type::make_shared_enabler;
-    return std::make_shared<value_type>(
-        enabler{}, value_traits<T>::construct(std::forward<T>(val)));
-}
-
-template <class T>
-inline std::shared_ptr<value<T>> base::as()
-{
-#if defined(CPPTOML_NO_RTTI)
-    if (type() == base_type_traits<T>::type)
-        return std::static_pointer_cast<value<T>>(shared_from_this());
-    else
-        return nullptr;
-#else
-    return std::dynamic_pointer_cast<value<T>>(shared_from_this());
-#endif
-}
-
-// special case value<double> to allow getting an integer parameter as a
-// double value
-template <>
-inline std::shared_ptr<value<double>> base::as()
-{
-#if defined(CPPTOML_NO_RTTI)
-    if (type() == base_type::FLOAT)
-        return std::static_pointer_cast<value<double>>(shared_from_this());
-
-    if (type() == base_type::INT)
-    {
-        auto v = std::static_pointer_cast<value<int64_t>>(shared_from_this());
-        return make_value<double>(static_cast<double>(v->get()));
-    }
-#else
-    if (auto v = std::dynamic_pointer_cast<value<double>>(shared_from_this()))
-        return v;
-
-    if (auto v = std::dynamic_pointer_cast<value<int64_t>>(shared_from_this()))
-        return make_value<double>(static_cast<double>(v->get()));
-#endif
-
-    return nullptr;
-}
-
-template <class T>
-inline std::shared_ptr<const value<T>> base::as() const
-{
-#if defined(CPPTOML_NO_RTTI)
-    if (type() == base_type_traits<T>::type)
-        return std::static_pointer_cast<const value<T>>(shared_from_this());
-    else
-        return nullptr;
-#else
-    return std::dynamic_pointer_cast<const value<T>>(shared_from_this());
-#endif
-}
-
-// special case value<double> to allow getting an integer parameter as a
-// double value
-template <>
-inline std::shared_ptr<const value<double>> base::as() const
-{
-#if defined(CPPTOML_NO_RTTI)
-    if (type() == base_type::FLOAT)
-        return std::static_pointer_cast<const value<double>>(
-            shared_from_this());
-
-    if (type() == base_type::INT)
-    {
-        auto v = as<int64_t>();
-        // the below has to be a non-const value<double> due to a bug in
-        // libc++: https://llvm.org/bugs/show_bug.cgi?id=18843
-        return make_value<double>(static_cast<double>(v->get()));
-    }
-#else
-    if (auto v
-        = std::dynamic_pointer_cast<const value<double>>(shared_from_this()))
-        return v;
-
-    if (auto v = as<int64_t>())
-    {
-        // the below has to be a non-const value<double> due to a bug in
-        // libc++: https://llvm.org/bugs/show_bug.cgi?id=18843
-        return make_value<double>(static_cast<double>(v->get()));
-    }
-#endif
-
-    return nullptr;
-}
-
-/**
- * Exception class for array insertion errors.
- */
-class array_exception : public std::runtime_error
-{
-  public:
-    array_exception(const std::string& err) : std::runtime_error{err}
-    {
-    }
-};
-
-class array : public base
-{
-  public:
-    friend std::shared_ptr<array> make_array();
-
-    std::shared_ptr<base> clone() const override;
-
-    virtual bool is_array() const override
-    {
-        return true;
-    }
-
-    using size_type = std::size_t;
-
-    /**
-     * arrays can be iterated over
-     */
-    using iterator = std::vector<std::shared_ptr<base>>::iterator;
-
-    /**
-     * arrays can be iterated over.  Const version.
-     */
-    using const_iterator = std::vector<std::shared_ptr<base>>::const_iterator;
-
-    iterator begin()
-    {
-        return values_.begin();
-    }
-
-    const_iterator begin() const
-    {
-        return values_.begin();
-    }
-
-    iterator end()
-    {
-        return values_.end();
-    }
-
-    const_iterator end() const
-    {
-        return values_.end();
-    }
-
-    /**
-     * Obtains the array (vector) of base values.
-     */
-    std::vector<std::shared_ptr<base>>& get()
-    {
-        return values_;
-    }
-
-    /**
-     * Obtains the array (vector) of base values. Const version.
-     */
-    const std::vector<std::shared_ptr<base>>& get() const
-    {
-        return values_;
-    }
-
-    std::shared_ptr<base> at(size_t idx) const
-    {
-        return values_.at(idx);
-    }
-
-    /**
-     * Obtains an array of value<T>s. Note that elements may be
-     * nullptr if they cannot be converted to a value<T>.
-     */
-    template <class T>
-    std::vector<std::shared_ptr<value<T>>> array_of() const
-    {
-        std::vector<std::shared_ptr<value<T>>> result(values_.size());
-
-        std::transform(values_.begin(), values_.end(), result.begin(),
-                       [&](std::shared_ptr<base> v) { return v->as<T>(); });
-
-        return result;
-    }
-
-    /**
-     * Obtains a option<vector<T>>. The option will be empty if the array
-     * contains values that are not of type T.
-     */
-    template <class T>
-    inline typename array_of_trait<T>::return_type get_array_of() const
-    {
-        std::vector<T> result;
-        result.reserve(values_.size());
-
-        for (const auto& val : values_)
-        {
-            if (auto v = val->as<T>())
-                result.push_back(v->get());
-            else
-                return {};
-        }
-
-        return {std::move(result)};
-    }
-
-    /**
-     * Obtains an array of arrays. Note that elements may be nullptr
-     * if they cannot be converted to a array.
-     */
-    std::vector<std::shared_ptr<array>> nested_array() const
-    {
-        std::vector<std::shared_ptr<array>> result(values_.size());
-
-        std::transform(values_.begin(), values_.end(), result.begin(),
-                       [&](std::shared_ptr<base> v) -> std::shared_ptr<array> {
-                           if (v->is_array())
-                               return std::static_pointer_cast<array>(v);
-                           return std::shared_ptr<array>{};
-                       });
-
-        return result;
-    }
-
-    /**
-     * Add a value to the end of the array
-     */
-    template <class T>
-    void push_back(const std::shared_ptr<value<T>>& val)
-    {
-        if (values_.empty() || values_[0]->as<T>())
-        {
-            values_.push_back(val);
-        }
-        else
-        {
-            throw array_exception{"Arrays must be homogenous."};
-        }
-    }
-
-    /**
-     * Add an array to the end of the array
-     */
-    void push_back(const std::shared_ptr<array>& val)
-    {
-        if (values_.empty() || values_[0]->is_array())
-        {
-            values_.push_back(val);
-        }
-        else
-        {
-            throw array_exception{"Arrays must be homogenous."};
-        }
-    }
-
-    /**
-     * Convenience function for adding a simple element to the end
-     * of the array.
-     */
-    template <class T>
-    void push_back(T&& val, typename value_traits<T>::type* = 0)
-    {
-        push_back(make_value(std::forward<T>(val)));
-    }
-
-    /**
-     * Insert a value into the array
-     */
-    template <class T>
-    iterator insert(iterator position, const std::shared_ptr<value<T>>& value)
-    {
-        if (values_.empty() || values_[0]->as<T>())
-        {
-            return values_.insert(position, value);
-        }
-        else
-        {
-            throw array_exception{"Arrays must be homogenous."};
-        }
-    }
-
-    /**
-     * Insert an array into the array
-     */
-    iterator insert(iterator position, const std::shared_ptr<array>& value)
-    {
-        if (values_.empty() || values_[0]->is_array())
-        {
-            return values_.insert(position, value);
-        }
-        else
-        {
-            throw array_exception{"Arrays must be homogenous."};
-        }
-    }
-
-    /**
-     * Convenience function for inserting a simple element in the array
-     */
-    template <class T>
-    iterator insert(iterator position, T&& val,
-                    typename value_traits<T>::type* = 0)
-    {
-        return insert(position, make_value(std::forward<T>(val)));
-    }
-
-    /**
-     * Erase an element from the array
-     */
-    iterator erase(iterator position)
-    {
-        return values_.erase(position);
-    }
-
-    /**
-     * Clear the array
-     */
-    void clear()
-    {
-        values_.clear();
-    }
-
-    /**
-     * Reserve space for n values.
-     */
-    void reserve(size_type n)
-    {
-        values_.reserve(n);
-    }
-
-  private:
-#if defined(CPPTOML_NO_RTTI)
-    array() : base(base_type::ARRAY)
-    {
-        // empty
-    }
-#else
-    array() = default;
-#endif
-
-    template <class InputIterator>
-    array(InputIterator begin, InputIterator end) : values_{begin, end}
-    {
-        // nothing
-    }
-
-    array(const array& obj) = delete;
-    array& operator=(const array& obj) = delete;
-
-    std::vector<std::shared_ptr<base>> values_;
-};
-
-inline std::shared_ptr<array> make_array()
-{
-    struct make_shared_enabler : public array
-    {
-        make_shared_enabler()
-        {
-            // nothing
-        }
-    };
-
-    return std::make_shared<make_shared_enabler>();
-}
-
-namespace detail
-{
-template <>
-inline std::shared_ptr<array> make_element<array>()
-{
-    return make_array();
-}
-} // namespace detail
-
-/**
- * Obtains a option<vector<T>>. The option will be empty if the array
- * contains values that are not of type T.
- */
-template <>
-inline typename array_of_trait<array>::return_type
-array::get_array_of<array>() const
-{
-    std::vector<std::shared_ptr<array>> result;
-    result.reserve(values_.size());
-
-    for (const auto& val : values_)
-    {
-        if (auto v = val->as_array())
-            result.push_back(v);
-        else
-            return {};
-    }
-
-    return {std::move(result)};
-}
-
-class table;
-
-class table_array : public base
-{
-    friend class table;
-    friend std::shared_ptr<table_array> make_table_array(bool);
-
-  public:
-    std::shared_ptr<base> clone() const override;
-
-    using size_type = std::size_t;
-
-    /**
-     * arrays can be iterated over
-     */
-    using iterator = std::vector<std::shared_ptr<table>>::iterator;
-
-    /**
-     * arrays can be iterated over.  Const version.
-     */
-    using const_iterator = std::vector<std::shared_ptr<table>>::const_iterator;
-
-    iterator begin()
-    {
-        return array_.begin();
-    }
-
-    const_iterator begin() const
-    {
-        return array_.begin();
-    }
-
-    iterator end()
-    {
-        return array_.end();
-    }
-
-    const_iterator end() const
-    {
-        return array_.end();
-    }
-
-    virtual bool is_table_array() const override
-    {
-        return true;
-    }
-
-    std::vector<std::shared_ptr<table>>& get()
-    {
-        return array_;
-    }
-
-    const std::vector<std::shared_ptr<table>>& get() const
-    {
-        return array_;
-    }
-
-    /**
-     * Add a table to the end of the array
-     */
-    void push_back(const std::shared_ptr<table>& val)
-    {
-        array_.push_back(val);
-    }
-
-    /**
-     * Insert a table into the array
-     */
-    iterator insert(iterator position, const std::shared_ptr<table>& value)
-    {
-        return array_.insert(position, value);
-    }
-
-    /**
-     * Erase an element from the array
-     */
-    iterator erase(iterator position)
-    {
-        return array_.erase(position);
-    }
-
-    /**
-     * Clear the array
-     */
-    void clear()
-    {
-        array_.clear();
-    }
-
-    /**
-     * Reserve space for n tables.
-     */
-    void reserve(size_type n)
-    {
-        array_.reserve(n);
-    }
-
-    /**
-     * Whether or not the table array is declared inline. This mostly
-     * matters for parsing, where statically defined arrays cannot be
-     * appended to using the array-of-table syntax.
-     */
-    bool is_inline() const
-    {
-        return is_inline_;
-    }
-
-  private:
-#if defined(CPPTOML_NO_RTTI)
-    table_array(bool is_inline = false)
-        : base(base_type::TABLE_ARRAY), is_inline_(is_inline)
-    {
-        // nothing
-    }
-#else
-    table_array(bool is_inline = false) : is_inline_(is_inline)
-    {
-        // nothing
-    }
-#endif
-
-    table_array(const table_array& obj) = delete;
-    table_array& operator=(const table_array& rhs) = delete;
-
-    std::vector<std::shared_ptr<table>> array_;
-    const bool is_inline_ = false;
-};
-
-inline std::shared_ptr<table_array> make_table_array(bool is_inline)
-{
-    struct make_shared_enabler : public table_array
-    {
-        make_shared_enabler(bool mse_is_inline) : table_array(mse_is_inline)
-        {
-            // nothing
-        }
-    };
-
-    return std::make_shared<make_shared_enabler>(is_inline);
-}
-
-namespace detail
-{
-template <>
-inline std::shared_ptr<table_array> make_element<table_array>()
-{
-    return make_table_array(true);
-}
-} // namespace detail
-
-// The below are overloads for fetching specific value types out of a value
-// where special casting behavior (like bounds checking) is desired
-
-template <class T>
-typename std::enable_if<!std::is_floating_point<T>::value
-                            && std::is_signed<T>::value,
-                        option<T>>::type
-get_impl(const std::shared_ptr<base>& elem)
-{
-    if (auto v = elem->as<int64_t>())
-    {
-        if (v->get() < (std::numeric_limits<T>::min)())
-            throw std::underflow_error{
-                "T cannot represent the value requested in get"};
-
-        if (v->get() > (std::numeric_limits<T>::max)())
-            throw std::overflow_error{
-                "T cannot represent the value requested in get"};
-
-        return {static_cast<T>(v->get())};
-    }
-    else
-    {
-        return {};
-    }
-}
-
-template <class T>
-typename std::enable_if<!std::is_same<T, bool>::value
-                            && std::is_unsigned<T>::value,
-                        option<T>>::type
-get_impl(const std::shared_ptr<base>& elem)
-{
-    if (auto v = elem->as<int64_t>())
-    {
-        if (v->get() < 0)
-            throw std::underflow_error{"T cannot store negative value in get"};
-
-        if (static_cast<uint64_t>(v->get()) > (std::numeric_limits<T>::max)())
-            throw std::overflow_error{
-                "T cannot represent the value requested in get"};
-
-        return {static_cast<T>(v->get())};
-    }
-    else
-    {
-        return {};
-    }
-}
-
-template <class T>
-typename std::enable_if<!std::is_integral<T>::value
-                            || std::is_same<T, bool>::value,
-                        option<T>>::type
-get_impl(const std::shared_ptr<base>& elem)
-{
-    if (auto v = elem->as<T>())
-    {
-        return {v->get()};
-    }
-    else
-    {
-        return {};
-    }
-}
-
-/**
- * Represents a TOML keytable.
- */
-class table : public base
-{
-  public:
-    friend class table_array;
-    friend std::shared_ptr<table> make_table();
-
-    std::shared_ptr<base> clone() const override;
-
-    /**
-     * tables can be iterated over.
-     */
-    using iterator = string_to_base_map::iterator;
-
-    /**
-     * tables can be iterated over. Const version.
-     */
-    using const_iterator = string_to_base_map::const_iterator;
-
-    iterator begin()
-    {
-        return map_.begin();
-    }
-
-    const_iterator begin() const
-    {
-        return map_.begin();
-    }
-
-    iterator end()
-    {
-        return map_.end();
-    }
-
-    const_iterator end() const
-    {
-        return map_.end();
-    }
-
-    bool is_table() const override
-    {
-        return true;
-    }
-
-    bool empty() const
-    {
-        return map_.empty();
-    }
-
-    /**
-     * Determines if this key table contains the given key.
-     */
-    bool contains(const std::string& key) const
-    {
-        return map_.find(key) != map_.end();
-    }
-
-    /**
-     * Determines if this key table contains the given key. Will
-     * resolve "qualified keys". Qualified keys are the full access
-     * path separated with dots like "grandparent.parent.child".
-     */
-    bool contains_qualified(const std::string& key) const
-    {
-        return resolve_qualified(key);
-    }
-
-    /**
-     * Obtains the base for a given key.
-     * @throw std::out_of_range if the key does not exist
-     */
-    std::shared_ptr<base> get(const std::string& key) const
-    {
-        return map_.at(key);
-    }
-
-    /**
-     * Obtains the base for a given key. Will resolve "qualified
-     * keys". Qualified keys are the full access path separated with
-     * dots like "grandparent.parent.child".
-     *
-     * @throw std::out_of_range if the key does not exist
-     */
-    std::shared_ptr<base> get_qualified(const std::string& key) const
-    {
-        std::shared_ptr<base> p;
-        resolve_qualified(key, &p);
-        return p;
-    }
-
-    /**
-     * Obtains a table for a given key, if possible.
-     */
-    std::shared_ptr<table> get_table(const std::string& key) const
-    {
-        if (contains(key) && get(key)->is_table())
-            return std::static_pointer_cast<table>(get(key));
-        return nullptr;
-    }
-
-    /**
-     * Obtains a table for a given key, if possible. Will resolve
-     * "qualified keys".
-     */
-    std::shared_ptr<table> get_table_qualified(const std::string& key) const
-    {
-        if (contains_qualified(key) && get_qualified(key)->is_table())
-            return std::static_pointer_cast<table>(get_qualified(key));
-        return nullptr;
-    }
-
-    /**
-     * Obtains an array for a given key.
-     */
-    std::shared_ptr<array> get_array(const std::string& key) const
-    {
-        if (!contains(key))
-            return nullptr;
-        return get(key)->as_array();
-    }
-
-    /**
-     * Obtains an array for a given key. Will resolve "qualified keys".
-     */
-    std::shared_ptr<array> get_array_qualified(const std::string& key) const
-    {
-        if (!contains_qualified(key))
-            return nullptr;
-        return get_qualified(key)->as_array();
-    }
-
-    /**
-     * Obtains a table_array for a given key, if possible.
-     */
-    std::shared_ptr<table_array> get_table_array(const std::string& key) const
-    {
-        if (!contains(key))
-            return nullptr;
-        return get(key)->as_table_array();
-    }
-
-    /**
-     * Obtains a table_array for a given key, if possible. Will resolve
-     * "qualified keys".
-     */
-    std::shared_ptr<table_array>
-    get_table_array_qualified(const std::string& key) const
-    {
-        if (!contains_qualified(key))
-            return nullptr;
-        return get_qualified(key)->as_table_array();
-    }
-
-    /**
-     * Helper function that attempts to get a value corresponding
-     * to the template parameter from a given key.
-     */
-    template <class T>
-    option<T> get_as(const std::string& key) const
-    {
-        try
-        {
-            return get_impl<T>(get(key));
-        }
-        catch (const std::out_of_range&)
-        {
-            return {};
-        }
-    }
-
-    /**
-     * Helper function that attempts to get a value corresponding
-     * to the template parameter from a given key. Will resolve "qualified
-     * keys".
-     */
-    template <class T>
-    option<T> get_qualified_as(const std::string& key) const
-    {
-        try
-        {
-            return get_impl<T>(get_qualified(key));
-        }
-        catch (const std::out_of_range&)
-        {
-            return {};
-        }
-    }
-
-    /**
-     * Helper function that attempts to get an array of values of a given
-     * type corresponding to the template parameter for a given key.
-     *
-     * If the key doesn't exist, doesn't exist as an array type, or one or
-     * more keys inside the array type are not of type T, an empty option
-     * is returned. Otherwise, an option containing a vector of the values
-     * is returned.
-     */
-    template <class T>
-    inline typename array_of_trait<T>::return_type
-    get_array_of(const std::string& key) const
-    {
-        if (auto v = get_array(key))
-        {
-            std::vector<T> result;
-            result.reserve(v->get().size());
-
-            for (const auto& b : v->get())
-            {
-                if (auto val = b->as<T>())
-                    result.push_back(val->get());
-                else
-                    return {};
-            }
-            return {std::move(result)};
-        }
-
-        return {};
-    }
-
-    /**
-     * Helper function that attempts to get an array of values of a given
-     * type corresponding to the template parameter for a given key. Will
-     * resolve "qualified keys".
-     *
-     * If the key doesn't exist, doesn't exist as an array type, or one or
-     * more keys inside the array type are not of type T, an empty option
-     * is returned. Otherwise, an option containing a vector of the values
-     * is returned.
-     */
-    template <class T>
-    inline typename array_of_trait<T>::return_type
-    get_qualified_array_of(const std::string& key) const
-    {
-        if (auto v = get_array_qualified(key))
-        {
-            std::vector<T> result;
-            result.reserve(v->get().size());
-
-            for (const auto& b : v->get())
-            {
-                if (auto val = b->as<T>())
-                    result.push_back(val->get());
-                else
-                    return {};
-            }
-            return {std::move(result)};
-        }
-
-        return {};
-    }
-
-    /**
-     * Adds an element to the keytable.
-     */
-    void insert(const std::string& key, const std::shared_ptr<base>& value)
-    {
-        map_[key] = value;
-    }
-
-    /**
-     * Convenience shorthand for adding a simple element to the
-     * keytable.
-     */
-    template <class T>
-    void insert(const std::string& key, T&& val,
-                typename value_traits<T>::type* = 0)
-    {
-        insert(key, make_value(std::forward<T>(val)));
-    }
-
-    /**
-     * Removes an element from the table.
-     */
-    void erase(const std::string& key)
-    {
-        map_.erase(key);
-    }
-
-  private:
-#if defined(CPPTOML_NO_RTTI)
-    table() : base(base_type::TABLE)
-    {
-        // nothing
-    }
-#else
-    table()
-    {
-        // nothing
-    }
-#endif
-
-    table(const table& obj) = delete;
-    table& operator=(const table& rhs) = delete;
-
-    std::vector<std::string> split(const std::string& value,
-                                   char separator) const
-    {
-        std::vector<std::string> result;
-        std::string::size_type p = 0;
-        std::string::size_type q;
-        while ((q = value.find(separator, p)) != std::string::npos)
-        {
-            result.emplace_back(value, p, q - p);
-            p = q + 1;
-        }
-        result.emplace_back(value, p);
-        return result;
-    }
-
-    // If output parameter p is specified, fill it with the pointer to the
-    // specified entry and throw std::out_of_range if it couldn't be found.
-    //
-    // Otherwise, just return true if the entry could be found or false
-    // otherwise and do not throw.
-    bool resolve_qualified(const std::string& key,
-                           std::shared_ptr<base>* p = nullptr) const
-    {
-        auto parts = split(key, '.');
-        auto last_key = parts.back();
-        parts.pop_back();
-
-        auto cur_table = this;
-        for (const auto& part : parts)
-        {
-            cur_table = cur_table->get_table(part).get();
-            if (!cur_table)
-            {
-                if (!p)
-                    return false;
-
-                throw std::out_of_range{key + " is not a valid key"};
-            }
-        }
-
-        if (!p)
-            return cur_table->map_.count(last_key) != 0;
-
-        *p = cur_table->map_.at(last_key);
-        return true;
-    }
-
-    string_to_base_map map_;
-};
-
-/**
- * Helper function that attempts to get an array of arrays for a given
- * key.
- *
- * If the key doesn't exist, doesn't exist as an array type, or one or
- * more keys inside the array type are not of type T, an empty option
- * is returned. Otherwise, an option containing a vector of the values
- * is returned.
- */
-template <>
-inline typename array_of_trait<array>::return_type
-table::get_array_of<array>(const std::string& key) const
-{
-    if (auto v = get_array(key))
-    {
-        std::vector<std::shared_ptr<array>> result;
-        result.reserve(v->get().size());
-
-        for (const auto& b : v->get())
-        {
-            if (auto val = b->as_array())
-                result.push_back(val);
-            else
-                return {};
-        }
-
-        return {std::move(result)};
-    }
-
-    return {};
-}
-
-/**
- * Helper function that attempts to get an array of arrays for a given
- * key. Will resolve "qualified keys".
- *
- * If the key doesn't exist, doesn't exist as an array type, or one or
- * more keys inside the array type are not of type T, an empty option
- * is returned. Otherwise, an option containing a vector of the values
- * is returned.
- */
-template <>
-inline typename array_of_trait<array>::return_type
-table::get_qualified_array_of<array>(const std::string& key) const
-{
-    if (auto v = get_array_qualified(key))
-    {
-        std::vector<std::shared_ptr<array>> result;
-        result.reserve(v->get().size());
-
-        for (const auto& b : v->get())
-        {
-            if (auto val = b->as_array())
-                result.push_back(val);
-            else
-                return {};
-        }
-
-        return {std::move(result)};
-    }
-
-    return {};
-}
-
-std::shared_ptr<table> make_table()
-{
-    struct make_shared_enabler : public table
-    {
-        make_shared_enabler()
-        {
-            // nothing
-        }
-    };
-
-    return std::make_shared<make_shared_enabler>();
-}
-
-namespace detail
-{
-template <>
-inline std::shared_ptr<table> make_element<table>()
-{
-    return make_table();
-}
-} // namespace detail
-
-template <class T>
-std::shared_ptr<base> value<T>::clone() const
-{
-    return make_value(data_);
-}
-
-inline std::shared_ptr<base> array::clone() const
-{
-    auto result = make_array();
-    result->reserve(values_.size());
-    for (const auto& ptr : values_)
-        result->values_.push_back(ptr->clone());
-    return result;
-}
-
-inline std::shared_ptr<base> table_array::clone() const
-{
-    auto result = make_table_array(is_inline());
-    result->reserve(array_.size());
-    for (const auto& ptr : array_)
-        result->array_.push_back(ptr->clone()->as_table());
-    return result;
-}
-
-inline std::shared_ptr<base> table::clone() const
-{
-    auto result = make_table();
-    for (const auto& pr : map_)
-        result->insert(pr.first, pr.second->clone());
-    return result;
-}
-
-/**
- * Exception class for all TOML parsing errors.
- */
-class parse_exception : public std::runtime_error
-{
-  public:
-    parse_exception(const std::string& err) : std::runtime_error{err}
-    {
-    }
-
-    parse_exception(const std::string& err, std::size_t line_number)
-        : std::runtime_error{err + " at line " + std::to_string(line_number)}
-    {
-    }
-};
-
-inline bool is_number(char c)
-{
-    return c >= '0' && c <= '9';
-}
-
-inline bool is_hex(char c)
-{
-    return is_number(c) || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F');
-}
-
-/**
- * Helper object for consuming expected characters.
- */
-template <class OnError>
-class consumer
-{
-  public:
-    consumer(std::string::iterator& it, const std::string::iterator& end,
-             OnError&& on_error)
-        : it_(it), end_(end), on_error_(std::forward<OnError>(on_error))
-    {
-        // nothing
-    }
-
-    void operator()(char c)
-    {
-        if (it_ == end_ || *it_ != c)
-            on_error_();
-        ++it_;
-    }
-
-    template <std::size_t N>
-    void operator()(const char (&str)[N])
-    {
-        std::for_each(std::begin(str), std::end(str) - 1,
-                      [&](char c) { (*this)(c); });
-    }
-
-    void eat_or(char a, char b)
-    {
-        if (it_ == end_ || (*it_ != a && *it_ != b))
-            on_error_();
-        ++it_;
-    }
-
-    int eat_digits(int len)
-    {
-        int val = 0;
-        for (int i = 0; i < len; ++i)
-        {
-            if (!is_number(*it_) || it_ == end_)
-                on_error_();
-            val = 10 * val + (*it_++ - '0');
-        }
-        return val;
-    }
-
-    void error()
-    {
-        on_error_();
-    }
-
-  private:
-    std::string::iterator& it_;
-    const std::string::iterator& end_;
-    OnError on_error_;
-};
-
-template <class OnError>
-consumer<OnError> make_consumer(std::string::iterator& it,
-                                const std::string::iterator& end,
-                                OnError&& on_error)
-{
-    return consumer<OnError>(it, end, std::forward<OnError>(on_error));
-}
-
-// replacement for std::getline to handle incorrectly line-ended files
-// https://stackoverflow.com/questions/6089231/getting-std-ifstream-to-handle-lf-cr-and-crlf
-namespace detail
-{
-inline std::istream& getline(std::istream& input, std::string& line)
-{
-    line.clear();
-
-    std::istream::sentry sentry{input, true};
-    auto sb = input.rdbuf();
-
-    while (true)
-    {
-        auto c = sb->sbumpc();
-        if (c == '\r')
-        {
-            if (sb->sgetc() == '\n')
-                c = sb->sbumpc();
-        }
-
-        if (c == '\n')
-            return input;
-
-        if (c == std::istream::traits_type::eof())
-        {
-            if (line.empty())
-                input.setstate(std::ios::eofbit);
-            return input;
-        }
-
-        line.push_back(static_cast<char>(c));
-    }
-}
-} // namespace detail
-
-/**
- * The parser class.
- */
-class parser
-{
-  public:
-    /**
-     * Parsers are constructed from streams.
-     */
-    parser(std::istream& stream) : input_(stream)
-    {
-        // nothing
-    }
-
-    parser& operator=(const parser& parser) = delete;
-
-    /**
-     * Parses the stream this parser was created on until EOF.
-     * @throw parse_exception if there are errors in parsing
-     */
-    std::shared_ptr<table> parse()
-    {
-        std::shared_ptr<table> root = make_table();
-
-        table* curr_table = root.get();
-
-        while (detail::getline(input_, line_))
-        {
-            line_number_++;
-            auto it = line_.begin();
-            auto end = line_.end();
-            consume_whitespace(it, end);
-            if (it == end || *it == '#')
-                continue;
-            if (*it == '[')
-            {
-                curr_table = root.get();
-                parse_table(it, end, curr_table);
-            }
-            else
-            {
-                parse_key_value(it, end, curr_table);
-                consume_whitespace(it, end);
-                eol_or_comment(it, end);
-            }
-        }
-        return root;
-    }
-
-  private:
-#if defined _MSC_VER
-    __declspec(noreturn)
-#elif defined __GNUC__
-    __attribute__((noreturn))
-#endif
-        void throw_parse_exception(const std::string& err)
-    {
-        throw parse_exception{err, line_number_};
-    }
-
-    void parse_table(std::string::iterator& it,
-                     const std::string::iterator& end, table*& curr_table)
-    {
-        // remove the beginning keytable marker
-        ++it;
-        if (it == end)
-            throw_parse_exception("Unexpected end of table");
-        if (*it == '[')
-            parse_table_array(it, end, curr_table);
-        else
-            parse_single_table(it, end, curr_table);
-    }
-
-    void parse_single_table(std::string::iterator& it,
-                            const std::string::iterator& end,
-                            table*& curr_table)
-    {
-        if (it == end || *it == ']')
-            throw_parse_exception("Table name cannot be empty");
-
-        std::string full_table_name;
-        bool inserted = false;
-
-        auto key_end = [](char c) { return c == ']'; };
-
-        auto key_part_handler = [&](const std::string& part) {
-            if (part.empty())
-                throw_parse_exception("Empty component of table name");
-
-            if (!full_table_name.empty())
-                full_table_name += '.';
-            full_table_name += part;
-
-            if (curr_table->contains(part))
-            {
-#if !defined(__PGI)
-                auto b = curr_table->get(part);
-#else
-                // Workaround for PGI compiler
-                std::shared_ptr<base> b = curr_table->get(part);
-#endif
-                if (b->is_table())
-                    curr_table = static_cast<table*>(b.get());
-                else if (b->is_table_array())
-                    curr_table = std::static_pointer_cast<table_array>(b)
-                                     ->get()
-                                     .back()
-                                     .get();
-                else
-                    throw_parse_exception("Key " + full_table_name
-                                          + "already exists as a value");
-            }
-            else
-            {
-                inserted = true;
-                curr_table->insert(part, make_table());
-                curr_table = static_cast<table*>(curr_table->get(part).get());
-            }
-        };
-
-        key_part_handler(parse_key(it, end, key_end, key_part_handler));
-
-        if (it == end)
-            throw_parse_exception(
-                "Unterminated table declaration; did you forget a ']'?");
-
-        if (*it != ']')
-        {
-            std::string errmsg{"Unexpected character in table definition: "};
-            errmsg += '"';
-            errmsg += *it;
-            errmsg += '"';
-            throw_parse_exception(errmsg);
-        }
-
-        // table already existed
-        if (!inserted)
-        {
-            auto is_value
-                = [](const std::pair<const std::string&,
-                                     const std::shared_ptr<base>&>& p) {
-                      return p.second->is_value();
-                  };
-
-            // if there are any values, we can't add values to this table
-            // since it has already been defined. If there aren't any
-            // values, then it was implicitly created by something like
-            // [a.b]
-            if (curr_table->empty()
-                || std::any_of(curr_table->begin(), curr_table->end(),
-                               is_value))
-            {
-                throw_parse_exception("Redefinition of table "
-                                      + full_table_name);
-            }
-        }
-
-        ++it;
-        consume_whitespace(it, end);
-        eol_or_comment(it, end);
-    }
-
-    void parse_table_array(std::string::iterator& it,
-                           const std::string::iterator& end, table*& curr_table)
-    {
-        ++it;
-        if (it == end || *it == ']')
-            throw_parse_exception("Table array name cannot be empty");
-
-        auto key_end = [](char c) { return c == ']'; };
-
-        std::string full_ta_name;
-        auto key_part_handler = [&](const std::string& part) {
-            if (part.empty())
-                throw_parse_exception("Empty component of table array name");
-
-            if (!full_ta_name.empty())
-                full_ta_name += '.';
-            full_ta_name += part;
-
-            if (curr_table->contains(part))
-            {
-#if !defined(__PGI)
-                auto b = curr_table->get(part);
-#else
-                // Workaround for PGI compiler
-                std::shared_ptr<base> b = curr_table->get(part);
-#endif
-
-                // if this is the end of the table array name, add an
-                // element to the table array that we just looked up,
-                // provided it was not declared inline
-                if (it != end && *it == ']')
-                {
-                    if (!b->is_table_array())
-                    {
-                        throw_parse_exception("Key " + full_ta_name
-                                              + " is not a table array");
-                    }
-
-                    auto v = b->as_table_array();
-
-                    if (v->is_inline())
-                    {
-                        throw_parse_exception("Static array " + full_ta_name
-                                              + " cannot be appended to");
-                    }
-
-                    v->get().push_back(make_table());
-                    curr_table = v->get().back().get();
-                }
-                // otherwise, just keep traversing down the key name
-                else
-                {
-                    if (b->is_table())
-                        curr_table = static_cast<table*>(b.get());
-                    else if (b->is_table_array())
-                        curr_table = std::static_pointer_cast<table_array>(b)
-                                         ->get()
-                                         .back()
-                                         .get();
-                    else
-                        throw_parse_exception("Key " + full_ta_name
-                                              + " already exists as a value");
-                }
-            }
-            else
-            {
-                // if this is the end of the table array name, add a new
-                // table array and a new table inside that array for us to
-                // add keys to next
-                if (it != end && *it == ']')
-                {
-                    curr_table->insert(part, make_table_array());
-                    auto arr = std::static_pointer_cast<table_array>(
-                        curr_table->get(part));
-                    arr->get().push_back(make_table());
-                    curr_table = arr->get().back().get();
-                }
-                // otherwise, create the implicitly defined table and move
-                // down to it
-                else
-                {
-                    curr_table->insert(part, make_table());
-                    curr_table
-                        = static_cast<table*>(curr_table->get(part).get());
-                }
-            }
-        };
-
-        key_part_handler(parse_key(it, end, key_end, key_part_handler));
-
-        // consume the last "]]"
-        auto eat = make_consumer(it, end, [this]() {
-            throw_parse_exception("Unterminated table array name");
-        });
-        eat(']');
-        eat(']');
-
-        consume_whitespace(it, end);
-        eol_or_comment(it, end);
-    }
-
-    void parse_key_value(std::string::iterator& it, std::string::iterator& end,
-                         table* curr_table)
-    {
-        auto key_end = [](char c) { return c == '='; };
-
-        auto key_part_handler = [&](const std::string& part) {
-            // two cases: this key part exists already, in which case it must
-            // be a table, or it doesn't exist in which case we must create
-            // an implicitly defined table
-            if (curr_table->contains(part))
-            {
-                auto val = curr_table->get(part);
-                if (val->is_table())
-                {
-                    curr_table = static_cast<table*>(val.get());
-                }
-                else
-                {
-                    throw_parse_exception("Key " + part
-                                          + " already exists as a value");
-                }
-            }
-            else
-            {
-                auto newtable = make_table();
-                curr_table->insert(part, newtable);
-                curr_table = newtable.get();
-            }
-        };
-
-        auto key = parse_key(it, end, key_end, key_part_handler);
-
-        if (curr_table->contains(key))
-            throw_parse_exception("Key " + key + " already present");
-        if (it == end || *it != '=')
-            throw_parse_exception("Value must follow after a '='");
-        ++it;
-        consume_whitespace(it, end);
-        curr_table->insert(key, parse_value(it, end));
-        consume_whitespace(it, end);
-    }
-
-    template <class KeyEndFinder, class KeyPartHandler>
-    std::string
-    parse_key(std::string::iterator& it, const std::string::iterator& end,
-              KeyEndFinder&& key_end, KeyPartHandler&& key_part_handler)
-    {
-        // parse the key as a series of one or more simple-keys joined with '.'
-        while (it != end && !key_end(*it))
-        {
-            auto part = parse_simple_key(it, end);
-            consume_whitespace(it, end);
-
-            if (it == end || key_end(*it))
-            {
-                return part;
-            }
-
-            if (*it != '.')
-            {
-                std::string errmsg{"Unexpected character in key: "};
-                errmsg += '"';
-                errmsg += *it;
-                errmsg += '"';
-                throw_parse_exception(errmsg);
-            }
-
-            key_part_handler(part);
-
-            // consume the dot
-            ++it;
-        }
-
-        throw_parse_exception("Unexpected end of key");
-    }
-
-    std::string parse_simple_key(std::string::iterator& it,
-                                 const std::string::iterator& end)
-    {
-        consume_whitespace(it, end);
-
-        if (it == end)
-            throw_parse_exception("Unexpected end of key (blank key?)");
-
-        if (*it == '"' || *it == '\'')
-        {
-            return string_literal(it, end, *it);
-        }
-        else
-        {
-            auto bke = std::find_if(it, end, [](char c) {
-                return c == '.' || c == '=' || c == ']';
-            });
-            return parse_bare_key(it, bke);
-        }
-    }
-
-    std::string parse_bare_key(std::string::iterator& it,
-                               const std::string::iterator& end)
-    {
-        if (it == end)
-        {
-            throw_parse_exception("Bare key missing name");
-        }
-
-        auto key_end = end;
-        --key_end;
-        consume_backwards_whitespace(key_end, it);
-        ++key_end;
-        std::string key{it, key_end};
-
-        if (std::find(it, key_end, '#') != key_end)
-        {
-            throw_parse_exception("Bare key " + key + " cannot contain #");
-        }
-
-        if (std::find_if(it, key_end,
-                         [](char c) { return c == ' ' || c == '\t'; })
-            != key_end)
-        {
-            throw_parse_exception("Bare key " + key
-                                  + " cannot contain whitespace");
-        }
-
-        if (std::find_if(it, key_end,
-                         [](char c) { return c == '[' || c == ']'; })
-            != key_end)
-        {
-            throw_parse_exception("Bare key " + key
-                                  + " cannot contain '[' or ']'");
-        }
-
-        it = end;
-        return key;
-    }
-
-    enum class parse_type
-    {
-        STRING = 1,
-        LOCAL_TIME,
-        LOCAL_DATE,
-        LOCAL_DATETIME,
-        OFFSET_DATETIME,
-        INT,
-        FLOAT,
-        BOOL,
-        ARRAY,
-        INLINE_TABLE
-    };
-
-    std::shared_ptr<base> parse_value(std::string::iterator& it,
-                                      std::string::iterator& end)
-    {
-        parse_type type = determine_value_type(it, end);
-        switch (type)
-        {
-            case parse_type::STRING:
-                return parse_string(it, end);
-            case parse_type::LOCAL_TIME:
-                return parse_time(it, end);
-            case parse_type::LOCAL_DATE:
-            case parse_type::LOCAL_DATETIME:
-            case parse_type::OFFSET_DATETIME:
-                return parse_date(it, end);
-            case parse_type::INT:
-            case parse_type::FLOAT:
-                return parse_number(it, end);
-            case parse_type::BOOL:
-                return parse_bool(it, end);
-            case parse_type::ARRAY:
-                return parse_array(it, end);
-            case parse_type::INLINE_TABLE:
-                return parse_inline_table(it, end);
-            default:
-                throw_parse_exception("Failed to parse value");
-        }
-    }
-
-    parse_type determine_value_type(const std::string::iterator& it,
-                                    const std::string::iterator& end)
-    {
-        if (it == end)
-        {
-            throw_parse_exception("Failed to parse value type");
-        }
-        if (*it == '"' || *it == '\'')
-        {
-            return parse_type::STRING;
-        }
-        else if (is_time(it, end))
-        {
-            return parse_type::LOCAL_TIME;
-        }
-        else if (auto dtype = date_type(it, end))
-        {
-            return *dtype;
-        }
-        else if (is_number(*it) || *it == '-' || *it == '+'
-                 || (*it == 'i' && it + 1 != end && it[1] == 'n'
-                     && it + 2 != end && it[2] == 'f')
-                 || (*it == 'n' && it + 1 != end && it[1] == 'a'
-                     && it + 2 != end && it[2] == 'n'))
-        {
-            return determine_number_type(it, end);
-        }
-        else if (*it == 't' || *it == 'f')
-        {
-            return parse_type::BOOL;
-        }
-        else if (*it == '[')
-        {
-            return parse_type::ARRAY;
-        }
-        else if (*it == '{')
-        {
-            return parse_type::INLINE_TABLE;
-        }
-        throw_parse_exception("Failed to parse value type");
-    }
-
-    parse_type determine_number_type(const std::string::iterator& it,
-                                     const std::string::iterator& end)
-    {
-        // determine if we are an integer or a float
-        auto check_it = it;
-        if (*check_it == '-' || *check_it == '+')
-            ++check_it;
-
-        if (check_it == end)
-            throw_parse_exception("Malformed number");
-
-        if (*check_it == 'i' || *check_it == 'n')
-            return parse_type::FLOAT;
-
-        while (check_it != end && is_number(*check_it))
-            ++check_it;
-        if (check_it != end && *check_it == '.')
-        {
-            ++check_it;
-            while (check_it != end && is_number(*check_it))
-                ++check_it;
-            return parse_type::FLOAT;
-        }
-        else
-        {
-            return parse_type::INT;
-        }
-    }
-
-    std::shared_ptr<value<std::string>> parse_string(std::string::iterator& it,
-                                                     std::string::iterator& end)
-    {
-        auto delim = *it;
-        assert(delim == '"' || delim == '\'');
-
-        // end is non-const here because we have to be able to potentially
-        // parse multiple lines in a string, not just one
-        auto check_it = it;
-        ++check_it;
-        if (check_it != end && *check_it == delim)
-        {
-            ++check_it;
-            if (check_it != end && *check_it == delim)
-            {
-                it = ++check_it;
-                return parse_multiline_string(it, end, delim);
-            }
-        }
-        return make_value<std::string>(string_literal(it, end, delim));
-    }
-
-    std::shared_ptr<value<std::string>>
-    parse_multiline_string(std::string::iterator& it,
-                           std::string::iterator& end, char delim)
-    {
-        std::stringstream ss;
-
-        auto is_ws = [](char c) { return c == ' ' || c == '\t'; };
-
-        bool consuming = false;
-        std::shared_ptr<value<std::string>> ret;
-
-        auto handle_line = [&](std::string::iterator& local_it,
-                               std::string::iterator& local_end) {
-            if (consuming)
-            {
-                local_it = std::find_if_not(local_it, local_end, is_ws);
-
-                // whole line is whitespace
-                if (local_it == local_end)
-                    return;
-            }
-
-            consuming = false;
-
-            while (local_it != local_end)
-            {
-                // handle escaped characters
-                if (delim == '"' && *local_it == '\\')
-                {
-                    auto check = local_it;
-                    // check if this is an actual escape sequence or a
-                    // whitespace escaping backslash
-                    ++check;
-                    consume_whitespace(check, local_end);
-                    if (check == local_end)
-                    {
-                        consuming = true;
-                        break;
-                    }
-
-                    ss << parse_escape_code(local_it, local_end);
-                    continue;
-                }
-
-                // if we can end the string
-                if (std::distance(local_it, local_end) >= 3)
-                {
-                    auto check = local_it;
-                    // check for """
-                    if (*check++ == delim && *check++ == delim
-                        && *check++ == delim)
-                    {
-                        local_it = check;
-                        ret = make_value<std::string>(ss.str());
-                        break;
-                    }
-                }
-
-                ss << *local_it++;
-            }
-        };
-
-        // handle the remainder of the current line
-        handle_line(it, end);
-        if (ret)
-            return ret;
-
-        // start eating lines
-        while (detail::getline(input_, line_))
-        {
-            ++line_number_;
-
-            it = line_.begin();
-            end = line_.end();
-
-            handle_line(it, end);
-
-            if (ret)
-                return ret;
-
-            if (!consuming)
-                ss << std::endl;
-        }
-
-        throw_parse_exception("Unterminated multi-line basic string");
-    }
-
-    std::string string_literal(std::string::iterator& it,
-                               const std::string::iterator& end, char delim)
-    {
-        ++it;
-        std::string val;
-        while (it != end)
-        {
-            // handle escaped characters
-            if (delim == '"' && *it == '\\')
-            {
-                val += parse_escape_code(it, end);
-            }
-            else if (*it == delim)
-            {
-                ++it;
-                consume_whitespace(it, end);
-                return val;
-            }
-            else
-            {
-                val += *it++;
-            }
-        }
-        throw_parse_exception("Unterminated string literal");
-    }
-
-    std::string parse_escape_code(std::string::iterator& it,
-                                  const std::string::iterator& end)
-    {
-        ++it;
-        if (it == end)
-            throw_parse_exception("Invalid escape sequence");
-        char value;
-        if (*it == 'b')
-        {
-            value = '\b';
-        }
-        else if (*it == 't')
-        {
-            value = '\t';
-        }
-        else if (*it == 'n')
-        {
-            value = '\n';
-        }
-        else if (*it == 'f')
-        {
-            value = '\f';
-        }
-        else if (*it == 'r')
-        {
-            value = '\r';
-        }
-        else if (*it == '"')
-        {
-            value = '"';
-        }
-        else if (*it == '\\')
-        {
-            value = '\\';
-        }
-        else if (*it == 'u' || *it == 'U')
-        {
-            return parse_unicode(it, end);
-        }
-        else
-        {
-            throw_parse_exception("Invalid escape sequence");
-        }
-        ++it;
-        return std::string(1, value);
-    }
-
-    std::string parse_unicode(std::string::iterator& it,
-                              const std::string::iterator& end)
-    {
-        bool large = *it++ == 'U';
-        auto codepoint = parse_hex(it, end, large ? 0x10000000 : 0x1000);
-
-        if ((codepoint > 0xd7ff && codepoint < 0xe000) || codepoint > 0x10ffff)
-        {
-            throw_parse_exception(
-                "Unicode escape sequence is not a Unicode scalar value");
-        }
-
-        std::string result;
-        // See Table 3-6 of the Unicode standard
-        if (codepoint <= 0x7f)
-        {
-            // 1-byte codepoints: 00000000 0xxxxxxx
-            // repr: 0xxxxxxx
-            result += static_cast<char>(codepoint & 0x7f);
-        }
-        else if (codepoint <= 0x7ff)
-        {
-            // 2-byte codepoints: 00000yyy yyxxxxxx
-            // repr: 110yyyyy 10xxxxxx
-            //
-            // 0x1f = 00011111
-            // 0xc0 = 11000000
-            //
-            result += static_cast<char>(0xc0 | ((codepoint >> 6) & 0x1f));
-            //
-            // 0x80 = 10000000
-            // 0x3f = 00111111
-            //
-            result += static_cast<char>(0x80 | (codepoint & 0x3f));
-        }
-        else if (codepoint <= 0xffff)
-        {
-            // 3-byte codepoints: zzzzyyyy yyxxxxxx
-            // repr: 1110zzzz 10yyyyyy 10xxxxxx
-            //
-            // 0xe0 = 11100000
-            // 0x0f = 00001111
-            //
-            result += static_cast<char>(0xe0 | ((codepoint >> 12) & 0x0f));
-            result += static_cast<char>(0x80 | ((codepoint >> 6) & 0x1f));
-            result += static_cast<char>(0x80 | (codepoint & 0x3f));
-        }
-        else
-        {
-            // 4-byte codepoints: 000uuuuu zzzzyyyy yyxxxxxx
-            // repr: 11110uuu 10uuzzzz 10yyyyyy 10xxxxxx
-            //
-            // 0xf0 = 11110000
-            // 0x07 = 00000111
-            //
-            result += static_cast<char>(0xf0 | ((codepoint >> 18) & 0x07));
-            result += static_cast<char>(0x80 | ((codepoint >> 12) & 0x3f));
-            result += static_cast<char>(0x80 | ((codepoint >> 6) & 0x3f));
-            result += static_cast<char>(0x80 | (codepoint & 0x3f));
-        }
-        return result;
-    }
-
-    uint32_t parse_hex(std::string::iterator& it,
-                       const std::string::iterator& end, uint32_t place)
-    {
-        uint32_t value = 0;
-        while (place > 0)
-        {
-            if (it == end)
-                throw_parse_exception("Unexpected end of unicode sequence");
-
-            if (!is_hex(*it))
-                throw_parse_exception("Invalid unicode escape sequence");
-
-            value += place * hex_to_digit(*it++);
-            place /= 16;
-        }
-        return value;
-    }
-
-    uint32_t hex_to_digit(char c)
-    {
-        if (is_number(c))
-            return static_cast<uint32_t>(c - '0');
-        return 10
-               + static_cast<uint32_t>(c
-                                       - ((c >= 'a' && c <= 'f') ? 'a' : 'A'));
-    }
-
-    std::shared_ptr<base> parse_number(std::string::iterator& it,
-                                       const std::string::iterator& end)
-    {
-        auto check_it = it;
-        auto check_end = find_end_of_number(it, end);
-
-        auto eat_sign = [&]() {
-            if (check_it != end && (*check_it == '-' || *check_it == '+'))
-                ++check_it;
-        };
-
-        auto check_no_leading_zero = [&]() {
-            if (check_it != end && *check_it == '0' && check_it + 1 != check_end
-                && check_it[1] != '.')
-            {
-                throw_parse_exception("Numbers may not have leading zeros");
-            }
-        };
-
-        auto eat_digits = [&](bool (*check_char)(char)) {
-            auto beg = check_it;
-            while (check_it != end && check_char(*check_it))
-            {
-                ++check_it;
-                if (check_it != end && *check_it == '_')
-                {
-                    ++check_it;
-                    if (check_it == end || !check_char(*check_it))
-                        throw_parse_exception("Malformed number");
-                }
-            }
-
-            if (check_it == beg)
-                throw_parse_exception("Malformed number");
-        };
-
-        auto eat_hex = [&]() { eat_digits(&is_hex); };
-
-        auto eat_numbers = [&]() { eat_digits(&is_number); };
-
-        if (check_it != end && *check_it == '0' && check_it + 1 != check_end
-            && (check_it[1] == 'x' || check_it[1] == 'o' || check_it[1] == 'b'))
-        {
-            ++check_it;
-            char base = *check_it;
-            ++check_it;
-            if (base == 'x')
-            {
-                eat_hex();
-                return parse_int(it, check_it, 16);
-            }
-            else if (base == 'o')
-            {
-                auto start = check_it;
-                eat_numbers();
-                auto val = parse_int(start, check_it, 8, "0");
-                it = start;
-                return val;
-            }
-            else // if (base == 'b')
-            {
-                auto start = check_it;
-                eat_numbers();
-                auto val = parse_int(start, check_it, 2);
-                it = start;
-                return val;
-            }
-        }
-
-        eat_sign();
-        check_no_leading_zero();
-
-        if (check_it != end && check_it + 1 != end && check_it + 2 != end)
-        {
-            if (check_it[0] == 'i' && check_it[1] == 'n' && check_it[2] == 'f')
-            {
-                auto val = std::numeric_limits<double>::infinity();
-                if (*it == '-')
-                    val = -val;
-                it = check_it + 3;
-                return make_value(val);
-            }
-            else if (check_it[0] == 'n' && check_it[1] == 'a'
-                     && check_it[2] == 'n')
-            {
-                auto val = std::numeric_limits<double>::quiet_NaN();
-                if (*it == '-')
-                    val = -val;
-                it = check_it + 3;
-                return make_value(val);
-            }
-        }
-
-        eat_numbers();
-
-        if (check_it != end
-            && (*check_it == '.' || *check_it == 'e' || *check_it == 'E'))
-        {
-            bool is_exp = *check_it == 'e' || *check_it == 'E';
-
-            ++check_it;
-            if (check_it == end)
-                throw_parse_exception("Floats must have trailing digits");
-
-            auto eat_exp = [&]() {
-                eat_sign();
-                check_no_leading_zero();
-                eat_numbers();
-            };
-
-            if (is_exp)
-                eat_exp();
-            else
-                eat_numbers();
-
-            if (!is_exp && check_it != end
-                && (*check_it == 'e' || *check_it == 'E'))
-            {
-                ++check_it;
-                eat_exp();
-            }
-
-            return parse_float(it, check_it);
-        }
-        else
-        {
-            return parse_int(it, check_it);
-        }
-    }
-
-    std::shared_ptr<value<int64_t>> parse_int(std::string::iterator& it,
-                                              const std::string::iterator& end,
-                                              int base = 10,
-                                              const char* prefix = "")
-    {
-        std::string v{it, end};
-        v = prefix + v;
-        v.erase(std::remove(v.begin(), v.end(), '_'), v.end());
-        it = end;
-        try
-        {
-            return make_value<int64_t>(std::stoll(v, nullptr, base));
-        }
-        catch (const std::invalid_argument& ex)
-        {
-            throw_parse_exception("Malformed number (invalid argument: "
-                                  + std::string{ex.what()} + ")");
-        }
-        catch (const std::out_of_range& ex)
-        {
-            throw_parse_exception("Malformed number (out of range: "
-                                  + std::string{ex.what()} + ")");
-        }
-    }
-
-    std::shared_ptr<value<double>> parse_float(std::string::iterator& it,
-                                               const std::string::iterator& end)
-    {
-        std::string v{it, end};
-        v.erase(std::remove(v.begin(), v.end(), '_'), v.end());
-        it = end;
-        char decimal_point = std::localeconv()->decimal_point[0];
-        std::replace(v.begin(), v.end(), '.', decimal_point);
-        try
-        {
-            return make_value<double>(std::stod(v));
-        }
-        catch (const std::invalid_argument& ex)
-        {
-            throw_parse_exception("Malformed number (invalid argument: "
-                                  + std::string{ex.what()} + ")");
-        }
-        catch (const std::out_of_range& ex)
-        {
-            throw_parse_exception("Malformed number (out of range: "
-                                  + std::string{ex.what()} + ")");
-        }
-    }
-
-    std::shared_ptr<value<bool>> parse_bool(std::string::iterator& it,
-                                            const std::string::iterator& end)
-    {
-        auto eat = make_consumer(it, end, [this]() {
-            throw_parse_exception("Attempted to parse invalid boolean value");
-        });
-
-        if (*it == 't')
-        {
-            eat("true");
-            return make_value<bool>(true);
-        }
-        else if (*it == 'f')
-        {
-            eat("false");
-            return make_value<bool>(false);
-        }
-
-        eat.error();
-        return nullptr;
-    }
-
-    std::string::iterator find_end_of_number(std::string::iterator it,
-                                             std::string::iterator end)
-    {
-        auto ret = std::find_if(it, end, [](char c) {
-            return !is_number(c) && c != '_' && c != '.' && c != 'e' && c != 'E'
-                   && c != '-' && c != '+' && c != 'x' && c != 'o' && c != 'b';
-        });
-        if (ret != end && ret + 1 != end && ret + 2 != end)
-        {
-            if ((ret[0] == 'i' && ret[1] == 'n' && ret[2] == 'f')
-                || (ret[0] == 'n' && ret[1] == 'a' && ret[2] == 'n'))
-            {
-                ret = ret + 3;
-            }
-        }
-        return ret;
-    }
-
-    std::string::iterator find_end_of_date(std::string::iterator it,
-                                           std::string::iterator end)
-    {
-        auto end_of_date = std::find_if(it, end, [](char c) {
-            return !is_number(c) && c != '-';
-        });
-        if (end_of_date != end && *end_of_date == ' ' && end_of_date + 1 != end
-            && is_number(end_of_date[1]))
-            end_of_date++;
-        return std::find_if(end_of_date, end, [](char c) {
-            return !is_number(c) && c != 'T' && c != 'Z' && c != ':'
-                   && c != '-' && c != '+' && c != '.';
-        });
-    }
-
-    std::string::iterator find_end_of_time(std::string::iterator it,
-                                           std::string::iterator end)
-    {
-        return std::find_if(it, end, [](char c) {
-            return !is_number(c) && c != ':' && c != '.';
-        });
-    }
-
-    local_time read_time(std::string::iterator& it,
-                         const std::string::iterator& end)
-    {
-        auto time_end = find_end_of_time(it, end);
-
-        auto eat = make_consumer(
-            it, time_end, [&]() { throw_parse_exception("Malformed time"); });
-
-        local_time ltime;
-
-        ltime.hour = eat.eat_digits(2);
-        eat(':');
-        ltime.minute = eat.eat_digits(2);
-        eat(':');
-        ltime.second = eat.eat_digits(2);
-
-        int power = 100000;
-        if (it != time_end && *it == '.')
-        {
-            ++it;
-            while (it != time_end && is_number(*it))
-            {
-                ltime.microsecond += power * (*it++ - '0');
-                power /= 10;
-            }
-        }
-
-        if (it != time_end)
-            throw_parse_exception("Malformed time");
-
-        return ltime;
-    }
-
-    std::shared_ptr<value<local_time>>
-    parse_time(std::string::iterator& it, const std::string::iterator& end)
-    {
-        return make_value(read_time(it, end));
-    }
-
-    std::shared_ptr<base> parse_date(std::string::iterator& it,
-                                     const std::string::iterator& end)
-    {
-        auto date_end = find_end_of_date(it, end);
-
-        auto eat = make_consumer(
-            it, date_end, [&]() { throw_parse_exception("Malformed date"); });
-
-        local_date ldate;
-        ldate.year = eat.eat_digits(4);
-        eat('-');
-        ldate.month = eat.eat_digits(2);
-        eat('-');
-        ldate.day = eat.eat_digits(2);
-
-        if (it == date_end)
-            return make_value(ldate);
-
-        eat.eat_or('T', ' ');
-
-        local_datetime ldt;
-        static_cast<local_date&>(ldt) = ldate;
-        static_cast<local_time&>(ldt) = read_time(it, date_end);
-
-        if (it == date_end)
-            return make_value(ldt);
-
-        offset_datetime dt;
-        static_cast<local_datetime&>(dt) = ldt;
-
-        int hoff = 0;
-        int moff = 0;
-        if (*it == '+' || *it == '-')
-        {
-            auto plus = *it == '+';
-            ++it;
-
-            hoff = eat.eat_digits(2);
-            dt.hour_offset = (plus) ? hoff : -hoff;
-            eat(':');
-            moff = eat.eat_digits(2);
-            dt.minute_offset = (plus) ? moff : -moff;
-        }
-        else if (*it == 'Z')
-        {
-            ++it;
-        }
-
-        if (it != date_end)
-            throw_parse_exception("Malformed date");
-
-        return make_value(dt);
-    }
-
-    std::shared_ptr<base> parse_array(std::string::iterator& it,
-                                      std::string::iterator& end)
-    {
-        // this gets ugly because of the "homogeneity" restriction:
-        // arrays can either be of only one type, or contain arrays
-        // (each of those arrays could be of different types, though)
-        //
-        // because of the latter portion, we don't really have a choice
-        // but to represent them as arrays of base values...
-        ++it;
-
-        // ugh---have to read the first value to determine array type...
-        skip_whitespace_and_comments(it, end);
-
-        // edge case---empty array
-        if (*it == ']')
-        {
-            ++it;
-            return make_array();
-        }
-
-        auto val_end = std::find_if(
-            it, end, [](char c) { return c == ',' || c == ']' || c == '#'; });
-        parse_type type = determine_value_type(it, val_end);
-        switch (type)
-        {
-            case parse_type::STRING:
-                return parse_value_array<std::string>(it, end);
-            case parse_type::LOCAL_TIME:
-                return parse_value_array<local_time>(it, end);
-            case parse_type::LOCAL_DATE:
-                return parse_value_array<local_date>(it, end);
-            case parse_type::LOCAL_DATETIME:
-                return parse_value_array<local_datetime>(it, end);
-            case parse_type::OFFSET_DATETIME:
-                return parse_value_array<offset_datetime>(it, end);
-            case parse_type::INT:
-                return parse_value_array<int64_t>(it, end);
-            case parse_type::FLOAT:
-                return parse_value_array<double>(it, end);
-            case parse_type::BOOL:
-                return parse_value_array<bool>(it, end);
-            case parse_type::ARRAY:
-                return parse_object_array<array>(&parser::parse_array, '[', it,
-                                                 end);
-            case parse_type::INLINE_TABLE:
-                return parse_object_array<table_array>(
-                    &parser::parse_inline_table, '{', it, end);
-            default:
-                throw_parse_exception("Unable to parse array");
-        }
-    }
-
-    template <class Value>
-    std::shared_ptr<array> parse_value_array(std::string::iterator& it,
-                                             std::string::iterator& end)
-    {
-        auto arr = make_array();
-        while (it != end && *it != ']')
-        {
-            auto val = parse_value(it, end);
-            if (auto v = val->as<Value>())
-                arr->get().push_back(val);
-            else
-                throw_parse_exception("Arrays must be homogeneous");
-            skip_whitespace_and_comments(it, end);
-            if (*it != ',')
-                break;
-            ++it;
-            skip_whitespace_and_comments(it, end);
-        }
-        if (it != end)
-            ++it;
-        return arr;
-    }
-
-    template <class Object, class Function>
-    std::shared_ptr<Object> parse_object_array(Function&& fun, char delim,
-                                               std::string::iterator& it,
-                                               std::string::iterator& end)
-    {
-        auto arr = detail::make_element<Object>();
-
-        while (it != end && *it != ']')
-        {
-            if (*it != delim)
-                throw_parse_exception("Unexpected character in array");
-
-            arr->get().push_back(((*this).*fun)(it, end));
-            skip_whitespace_and_comments(it, end);
-
-            if (it == end || *it != ',')
-                break;
-
-            ++it;
-            skip_whitespace_and_comments(it, end);
-        }
-
-        if (it == end || *it != ']')
-            throw_parse_exception("Unterminated array");
-
-        ++it;
-        return arr;
-    }
-
-    std::shared_ptr<table> parse_inline_table(std::string::iterator& it,
-                                              std::string::iterator& end)
-    {
-        auto tbl = make_table();
-        do
-        {
-            ++it;
-            if (it == end)
-                throw_parse_exception("Unterminated inline table");
-
-            consume_whitespace(it, end);
-            if (it != end && *it != '}')
-            {
-                parse_key_value(it, end, tbl.get());
-                consume_whitespace(it, end);
-            }
-        } while (*it == ',');
-
-        if (it == end || *it != '}')
-            throw_parse_exception("Unterminated inline table");
-
-        ++it;
-        consume_whitespace(it, end);
-
-        return tbl;
-    }
-
-    void skip_whitespace_and_comments(std::string::iterator& start,
-                                      std::string::iterator& end)
-    {
-        consume_whitespace(start, end);
-        while (start == end || *start == '#')
-        {
-            if (!detail::getline(input_, line_))
-                throw_parse_exception("Unclosed array");
-            line_number_++;
-            start = line_.begin();
-            end = line_.end();
-            consume_whitespace(start, end);
-        }
-    }
-
-    void consume_whitespace(std::string::iterator& it,
-                            const std::string::iterator& end)
-    {
-        while (it != end && (*it == ' ' || *it == '\t'))
-            ++it;
-    }
-
-    void consume_backwards_whitespace(std::string::iterator& back,
-                                      const std::string::iterator& front)
-    {
-        while (back != front && (*back == ' ' || *back == '\t'))
-            --back;
-    }
-
-    void eol_or_comment(const std::string::iterator& it,
-                        const std::string::iterator& end)
-    {
-        if (it != end && *it != '#')
-            throw_parse_exception("Unidentified trailing character '"
-                                  + std::string{*it}
-                                  + "'---did you forget a '#'?");
-    }
-
-    bool is_time(const std::string::iterator& it,
-                 const std::string::iterator& end)
-    {
-        auto time_end = find_end_of_time(it, end);
-        auto len = std::distance(it, time_end);
-
-        if (len < 8)
-            return false;
-
-        if (it[2] != ':' || it[5] != ':')
-            return false;
-
-        if (len > 8)
-            return it[8] == '.' && len > 9;
-
-        return true;
-    }
-
-    option<parse_type> date_type(const std::string::iterator& it,
-                                 const std::string::iterator& end)
-    {
-        auto date_end = find_end_of_date(it, end);
-        auto len = std::distance(it, date_end);
-
-        if (len < 10)
-            return {};
-
-        if (it[4] != '-' || it[7] != '-')
-            return {};
-
-        if (len >= 19 && (it[10] == 'T' || it[10] == ' ')
-            && is_time(it + 11, date_end))
-        {
-            // datetime type
-            auto time_end = find_end_of_time(it + 11, date_end);
-            if (time_end == date_end)
-                return {parse_type::LOCAL_DATETIME};
-            else
-                return {parse_type::OFFSET_DATETIME};
-        }
-        else if (len == 10)
-        {
-            // just a regular date
-            return {parse_type::LOCAL_DATE};
-        }
-
-        return {};
-    }
-
-    std::istream& input_;
-    std::string line_;
-    std::size_t line_number_ = 0;
-};
-
-/**
- * Utility function to parse a file as a TOML file. Returns the root table.
- * Throws a parse_exception if the file cannot be opened.
- */
-inline std::shared_ptr<table> parse_file(const std::string& filename)
-{
-#if defined(BOOST_NOWIDE_FSTREAM_INCLUDED_HPP)
-    boost::nowide::ifstream file{filename.c_str()};
-#elif defined(NOWIDE_FSTREAM_INCLUDED_HPP)
-    nowide::ifstream file{filename.c_str()};
-#else
-    std::ifstream file{filename};
-#endif
-    if (!file.is_open())
-        throw parse_exception{filename + " could not be opened for parsing"};
-    parser p{file};
-    return p.parse();
-}
-
-template <class... Ts>
-struct value_accept;
-
-template <>
-struct value_accept<>
-{
-    template <class Visitor, class... Args>
-    static void accept(const base&, Visitor&&, Args&&...)
-    {
-        // nothing
-    }
-};
-
-template <class T, class... Ts>
-struct value_accept<T, Ts...>
-{
-    template <class Visitor, class... Args>
-    static void accept(const base& b, Visitor&& visitor, Args&&... args)
-    {
-        if (auto v = b.as<T>())
-        {
-            visitor.visit(*v, std::forward<Args>(args)...);
-        }
-        else
-        {
-            value_accept<Ts...>::accept(b, std::forward<Visitor>(visitor),
-                                        std::forward<Args>(args)...);
-        }
-    }
-};
-
-/**
- * base implementation of accept() that calls visitor.visit() on the concrete
- * class.
- */
-template <class Visitor, class... Args>
-void base::accept(Visitor&& visitor, Args&&... args) const
-{
-    if (is_value())
-    {
-        using value_acceptor
-            = value_accept<std::string, int64_t, double, bool, local_date,
-                           local_time, local_datetime, offset_datetime>;
-        value_acceptor::accept(*this, std::forward<Visitor>(visitor),
-                               std::forward<Args>(args)...);
-    }
-    else if (is_table())
-    {
-        visitor.visit(static_cast<const table&>(*this),
-                      std::forward<Args>(args)...);
-    }
-    else if (is_array())
-    {
-        visitor.visit(static_cast<const array&>(*this),
-                      std::forward<Args>(args)...);
-    }
-    else if (is_table_array())
-    {
-        visitor.visit(static_cast<const table_array&>(*this),
-                      std::forward<Args>(args)...);
-    }
-}
-
-/**
- * Writer that can be passed to accept() functions of cpptoml objects and
- * will output valid TOML to a stream.
- */
-class toml_writer
-{
-  public:
-    /**
-     * Construct a toml_writer that will write to the given stream
-     */
-    toml_writer(std::ostream& s, const std::string& indent_space = "\t")
-        : stream_(s), indent_(indent_space), has_naked_endline_(false)
-    {
-        // nothing
-    }
-
-  public:
-    /**
-     * Output a base value of the TOML tree.
-     */
-    template <class T>
-    void visit(const value<T>& v, bool = false)
-    {
-        write(v);
-    }
-
-    /**
-     * Output a table element of the TOML tree
-     */
-    void visit(const table& t, bool in_array = false)
-    {
-        write_table_header(in_array);
-        std::vector<std::string> values;
-        std::vector<std::string> tables;
-
-        for (const auto& i : t)
-        {
-            if (i.second->is_table() || i.second->is_table_array())
-            {
-                tables.push_back(i.first);
-            }
-            else
-            {
-                values.push_back(i.first);
-            }
-        }
-
-        for (unsigned int i = 0; i < values.size(); ++i)
-        {
-            path_.push_back(values[i]);
-
-            if (i > 0)
-                endline();
-
-            write_table_item_header(*t.get(values[i]));
-            t.get(values[i])->accept(*this, false);
-            path_.pop_back();
-        }
-
-        for (unsigned int i = 0; i < tables.size(); ++i)
-        {
-            path_.push_back(tables[i]);
-
-            if (values.size() > 0 || i > 0)
-                endline();
-
-            write_table_item_header(*t.get(tables[i]));
-            t.get(tables[i])->accept(*this, false);
-            path_.pop_back();
-        }
-
-        endline();
-    }
-
-    /**
-     * Output an array element of the TOML tree
-     */
-    void visit(const array& a, bool = false)
-    {
-        write("[");
-
-        for (unsigned int i = 0; i < a.get().size(); ++i)
-        {
-            if (i > 0)
-                write(", ");
-
-            if (a.get()[i]->is_array())
-            {
-                a.get()[i]->as_array()->accept(*this, true);
-            }
-            else
-            {
-                a.get()[i]->accept(*this, true);
-            }
-        }
-
-        write("]");
-    }
-
-    /**
-     * Output a table_array element of the TOML tree
-     */
-    void visit(const table_array& t, bool = false)
-    {
-        for (unsigned int j = 0; j < t.get().size(); ++j)
-        {
-            if (j > 0)
-                endline();
-
-            t.get()[j]->accept(*this, true);
-        }
-
-        endline();
-    }
-
-    /**
-     * Escape a string for output.
-     */
-    static std::string escape_string(const std::string& str)
-    {
-        std::string res;
-        for (auto it = str.begin(); it != str.end(); ++it)
-        {
-            if (*it == '\b')
-            {
-                res += "\\b";
-            }
-            else if (*it == '\t')
-            {
-                res += "\\t";
-            }
-            else if (*it == '\n')
-            {
-                res += "\\n";
-            }
-            else if (*it == '\f')
-            {
-                res += "\\f";
-            }
-            else if (*it == '\r')
-            {
-                res += "\\r";
-            }
-            else if (*it == '"')
-            {
-                res += "\\\"";
-            }
-            else if (*it == '\\')
-            {
-                res += "\\\\";
-            }
-            else if (static_cast<uint32_t>(*it) <= UINT32_C(0x001f))
-            {
-                res += "\\u";
-                std::stringstream ss;
-                ss << std::hex << static_cast<uint32_t>(*it);
-                res += ss.str();
-            }
-            else
-            {
-                res += *it;
-            }
-        }
-        return res;
-    }
-
-  protected:
-    /**
-     * Write out a string.
-     */
-    void write(const value<std::string>& v)
-    {
-        write("\"");
-        write(escape_string(v.get()));
-        write("\"");
-    }
-
-    /**
-     * Write out a double.
-     */
-    void write(const value<double>& v)
-    {
-        std::stringstream ss;
-        ss << std::showpoint
-           << std::setprecision(std::numeric_limits<double>::max_digits10)
-           << v.get();
-
-        auto double_str = ss.str();
-        auto pos = double_str.find("e0");
-        if (pos != std::string::npos)
-            double_str.replace(pos, 2, "e");
-        pos = double_str.find("e-0");
-        if (pos != std::string::npos)
-            double_str.replace(pos, 3, "e-");
-
-        stream_ << double_str;
-        has_naked_endline_ = false;
-    }
-
-    /**
-     * Write out an integer, local_date, local_time, local_datetime, or
-     * offset_datetime.
-     */
-    template <class T>
-    typename std::enable_if<
-        is_one_of<T, int64_t, local_date, local_time, local_datetime,
-                  offset_datetime>::value>::type
-    write(const value<T>& v)
-    {
-        write(v.get());
-    }
-
-    /**
-     * Write out a boolean.
-     */
-    void write(const value<bool>& v)
-    {
-        write((v.get() ? "true" : "false"));
-    }
-
-    /**
-     * Write out the header of a table.
-     */
-    void write_table_header(bool in_array = false)
-    {
-        if (!path_.empty())
-        {
-            indent();
-
-            write("[");
-
-            if (in_array)
-            {
-                write("[");
-            }
-
-            for (unsigned int i = 0; i < path_.size(); ++i)
-            {
-                if (i > 0)
-                {
-                    write(".");
-                }
-
-                if (path_[i].find_first_not_of("ABCDEFGHIJKLMNOPQRSTUVWXYZabcde"
-                                               "fghijklmnopqrstuvwxyz0123456789"
-                                               "_-")
-                    == std::string::npos)
-                {
-                    write(path_[i]);
-                }
-                else
-                {
-                    write("\"");
-                    write(escape_string(path_[i]));
-                    write("\"");
-                }
-            }
-
-            if (in_array)
-            {
-                write("]");
-            }
-
-            write("]");
-            endline();
-        }
-    }
-
-    /**
-     * Write out the identifier for an item in a table.
-     */
-    void write_table_item_header(const base& b)
-    {
-        if (!b.is_table() && !b.is_table_array())
-        {
-            indent();
-
-            if (path_.back().find_first_not_of("ABCDEFGHIJKLMNOPQRSTUVWXYZabcde"
-                                               "fghijklmnopqrstuvwxyz0123456789"
-                                               "_-")
-                == std::string::npos)
-            {
-                write(path_.back());
-            }
-            else
-            {
-                write("\"");
-                write(escape_string(path_.back()));
-                write("\"");
-            }
-
-            write(" = ");
-        }
-    }
-
-  private:
-    /**
-     * Indent the proper number of tabs given the size of
-     * the path.
-     */
-    void indent()
-    {
-        for (std::size_t i = 1; i < path_.size(); ++i)
-            write(indent_);
-    }
-
-    /**
-     * Write a value out to the stream.
-     */
-    template <class T>
-    void write(const T& v)
-    {
-        stream_ << v;
-        has_naked_endline_ = false;
-    }
-
-    /**
-     * Write an endline out to the stream
-     */
-    void endline()
-    {
-        if (!has_naked_endline_)
-        {
-            stream_ << "\n";
-            has_naked_endline_ = true;
-        }
-    }
-
-  private:
-    std::ostream& stream_;
-    const std::string indent_;
-    std::vector<std::string> path_;
-    bool has_naked_endline_;
-};
-
-inline std::ostream& operator<<(std::ostream& stream, const base& b)
-{
-    toml_writer writer{stream};
-    b.accept(writer);
-    return stream;
-}
-
-template <class T>
-std::ostream& operator<<(std::ostream& stream, const value<T>& v)
-{
-    toml_writer writer{stream};
-    v.accept(writer);
-    return stream;
-}
-
-inline std::ostream& operator<<(std::ostream& stream, const table& t)
-{
-    toml_writer writer{stream};
-    t.accept(writer);
-    return stream;
-}
-
-inline std::ostream& operator<<(std::ostream& stream, const table_array& t)
-{
-    toml_writer writer{stream};
-    t.accept(writer);
-    return stream;
-}
-
-inline std::ostream& operator<<(std::ostream& stream, const array& a)
-{
-    toml_writer writer{stream};
-    a.accept(writer);
-    return stream;
-}
-} // namespace cpptoml
-#endif // CPPTOML_H
diff --git a/src/toml11/LICENSE b/src/toml11/LICENSE
new file mode 100644
index 000000000..f55c511d6
--- /dev/null
+++ b/src/toml11/LICENSE
@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2017 Toru Niina
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/src/toml11/README.md b/src/toml11/README.md
new file mode 100644
index 000000000..62b586305
--- /dev/null
+++ b/src/toml11/README.md
@@ -0,0 +1,1966 @@
+toml11
+======
+
+[![Build Status on GitHub Actions](https://github.com/ToruNiina/toml11/workflows/build/badge.svg)](https://github.com/ToruNiina/toml11/actions)
+[![Build Status on TravisCI](https://travis-ci.org/ToruNiina/toml11.svg?branch=master)](https://travis-ci.org/ToruNiina/toml11)
+[![Build status on Appveyor](https://ci.appveyor.com/api/projects/status/m2n08a926asvg5mg/branch/master?svg=true)](https://ci.appveyor.com/project/ToruNiina/toml11/branch/master)
+[![Build status on CircleCI](https://circleci.com/gh/ToruNiina/toml11/tree/master.svg?style=svg)](https://circleci.com/gh/ToruNiina/toml11/tree/master)
+[![Version](https://img.shields.io/github/release/ToruNiina/toml11.svg?style=flat)](https://github.com/ToruNiina/toml11/releases)
+[![License](https://img.shields.io/github/license/ToruNiina/toml11.svg?style=flat)](LICENSE)
+[![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.1209136.svg)](https://doi.org/10.5281/zenodo.1209136)
+
+toml11 is a C++11 (or later) header-only toml parser/encoder depending only on C++ standard library.
+
+- It is compatible to the latest version of [TOML v1.0.0](https://toml.io/en/v1.0.0).
+- It is one of the most TOML standard compliant libraries, tested with [the language agnostic test suite for TOML parsers by BurntSushi](https://github.com/BurntSushi/toml-test).
+- It shows highly informative error messages. You can see the error messages about invalid files at [CircleCI](https://circleci.com/gh/ToruNiina/toml11).
+- It has configurable container. You can use any random-access containers and key-value maps as backend containers.
+- It optionally preserves comments without any overhead.
+- It has configurable serializer that supports comments, inline tables, literal strings and multiline strings.
+- It supports user-defined type conversion from/into toml values.
+- It correctly handles UTF-8 sequences, with or without BOM, both on posix and Windows.
+
+## Example
+
+```cpp
+#include <toml.hpp>
+#include <iostream>
+
+int main()
+{
+    // ```toml
+    // title = "an example toml file"
+    // nums  = [3, 1, 4, 1, 5]
+    // ```
+    auto data = toml::parse("example.toml");
+
+    // find a value with the specified type from a table
+    std::string title = toml::find<std::string>(data, "title");
+
+    // convert the whole array into any container automatically
+    std::vector<int> nums = toml::find<std::vector<int>>(data, "nums");
+
+    // access with STL-like manner
+    if(!data.contains("foo"))
+    {
+        data["foo"] = "bar";
+    }
+
+    // pass a fallback
+    std::string name = toml::find_or<std::string>(data, "name", "not found");
+
+    // width-dependent formatting
+    std::cout << std::setw(80) << data << std::endl;
+
+    return 0;
+}
+```
+
+## Table of Contents
+
+- [Integration](#integration)
+- [Decoding a toml file](#decoding-a-toml-file)
+  - [In the case of syntax error](#in-the-case-of-syntax-error)
+  - [Invalid UTF-8 Codepoints](#invalid-utf-8-codepoints)
+- [Finding a toml value](#finding-a-toml-value)
+  - [Finding a value in a table](#finding-a-value-in-a-table)
+  - [In case of error](#in-case-of-error)
+  - [Dotted keys](#dotted-keys)
+- [Casting a toml value](#casting-a-toml-value)
+- [Checking value type](#checking-value-type)
+- [More about conversion](#more-about-conversion)
+  - [Converting an array](#converting-an-array)
+  - [Converting a table](#converting-a-table)
+  - [Getting an array of tables](#getting-an-array-of-tables)
+  - [Cost of conversion](#cost-of-conversion)
+  - [Converting datetime and its variants](#converting-datetime-and-its-variants)
+- [Getting with a fallback](#getting-with-a-fallback)
+- [Expecting conversion](#expecting-conversion)
+- [Visiting a toml::value](#visiting-a-tomlvalue)
+- [Constructing a toml::value](#constructing-a-tomlvalue)
+- [Preserving Comments](#preserving-comments)
+- [Customizing containers](#customizing-containers)
+- [TOML literal](#toml-literal)
+- [Conversion between toml value and arbitrary types](#conversion-between-toml-value-and-arbitrary-types)
+- [Formatting user-defined error messages](#formatting-user-defined-error-messages)
+- [Obtaining location information](#obtaining-location-information)
+- [Exceptions](#exceptions)
+- [Colorize Error Messages](#colorize-error-messages)
+- [Serializing TOML data](#serializing-toml-data)
+- [Underlying types](#underlying-types)
+- [Unreleased TOML features](#unreleased-toml-features)
+- [Breaking Changes from v2](#breaking-changes-from-v2)
+- [Running Tests](#running-tests)
+- [Contributors](#contributors)
+- [Licensing Terms](#licensing-terms)
+
+## Integration
+
+Just include the file after adding it to the include path.
+
+```cpp
+#include <toml.hpp> // that's all! now you can use it.
+#include <iostream>
+
+int main()
+{
+    const auto data  = toml::parse("example.toml");
+    const auto title = toml::find<std::string>(data, "title");
+    std::cout << "the title is " << title << std::endl;
+    return 0;
+}
+```
+
+The convenient way is to add this repository as a git-submodule or to install
+it in your system by CMake.
+
+Note for MSVC: We recommend to set `/Zc:__cplusplus` to detect C++ version correctly.
+
+## Decoding a toml file
+
+To parse a toml file, the only thing you have to do is
+to pass a filename to the `toml::parse` function.
+
+```cpp
+const std::string fname("sample.toml");
+const toml::value data = toml::parse(fname);
+```
+
+As required by the TOML specification, the top-level value is always a table.
+You can find a value inside it, cast it into a table explicitly, and insert it as a value into other `toml::value`.
+
+If it encounters an error while opening a file, it will throw `std::runtime_error`.
+
+You can also pass a `std::istream` to the  `toml::parse` function.
+To show a filename in an error message, however, it is recommended to pass the
+filename with the stream.
+
+```cpp
+std::ifstream ifs("sample.toml", std::ios_base::binary);
+assert(ifs.good());
+const auto data = toml::parse(ifs, /*optional -> */ "sample.toml");
+```
+
+**Note**: When you are **on Windows, open a file in binary mode**.
+If a file is opened in text-mode, CRLF ("\r\n") will automatically be
+converted to LF ("\n") and this causes inconsistency between file size
+and the contents that would be read. This causes weird error.
+
+### In the case of syntax error
+
+If there is a syntax error in a toml file, `toml::parse` will throw
+`toml::syntax_error` that inherits `std::exception`.
+
+toml11 has clean and informative error messages inspired by Rust and
+it looks like the following.
+
+```console
+terminate called after throwing an instance of 'toml::syntax_error'
+  what():  [error] toml::parse_table: invalid line format # error description
+ --> example.toml                                         # file name
+ 3 | a = 42 = true                                        # line num and content
+   |        ^------ expected newline, but got '='.        # error reason
+```
+
+If you (mistakenly) duplicate tables and got an error, it is helpful to see
+where they are. toml11 shows both at the same time like the following.
+
+```console
+terminate called after throwing an instance of 'toml::syntax_error'
+  what():  [error] toml::insert_value: table ("table") already exists.
+ --> duplicate-table.toml
+ 1 | [table]
+   | ~~~~~~~ table already exists here
+ ...
+ 3 | [table]
+   | ~~~~~~~ table defined twice
+```
+
+When toml11 encounters a malformed value, it tries to detect what type it is.
+Then it shows hints to fix the format. An error message while reading one of
+the malformed files in [the language agnostic test suite](https://github.com/BurntSushi/toml-test).
+is shown below.
+
+```console
+what(): [error] bad time: should be HH:MM:SS.subsec
+ --> ./datetime-malformed-no-secs.toml
+ 1 | no-secs = 1987-07-05T17:45Z
+   |                     ^------- HH:MM:SS.subsec
+   |
+Hint: pass: 1979-05-27T07:32:00, 1979-05-27 07:32:00.999999
+Hint: fail: 1979-05-27T7:32:00, 1979-05-27 17:32
+```
+
+You can find other examples in a job named `output_result` on
+[CircleCI](https://circleci.com/gh/ToruNiina/toml11).
+
+Since the error message generation is generally a difficult task, the current
+status is not ideal. If you encounter a weird error message, please let us know
+and contribute to improve the quality!
+
+### Invalid UTF-8 codepoints
+
+It throws `syntax_error` if a value of an escape sequence
+representing unicode character is not a valid UTF-8 codepoint.
+
+```console
+  what():  [error] toml::read_utf8_codepoint: input codepoint is too large.
+ --> utf8.toml
+ 1 | exceeds_unicode = "\U0011FFFF example"
+   |                              ^--------- should be in [0x00..0x10FFFF]
+```
+
+## Finding a toml value
+
+After parsing successfully, you can obtain the values from the result of
+`toml::parse` using `toml::find` function.
+
+```toml
+# sample.toml
+answer  = 42
+pi      = 3.14
+numbers = [1,2,3]
+time    = 1979-05-27T07:32:00Z
+```
+
+``` cpp
+const auto data      = toml::parse("sample.toml");
+const auto answer    = toml::find<std::int64_t    >(data, "answer");
+const auto pi        = toml::find<double          >(data, "pi");
+const auto numbers   = toml::find<std::vector<int>>(data, "numbers");
+const auto timepoint = toml::find<std::chrono::system_clock::time_point>(data, "time");
+```
+
+By default, `toml::find` returns a `toml::value`.
+
+```cpp
+const toml::value& answer = toml::find(data, "answer");
+```
+
+When you pass an exact TOML type that does not require type conversion,
+`toml::find` returns a reference without copying the value.
+
+```cpp
+const auto  data   = toml::parse("sample.toml");
+const auto& answer = toml::find<toml::integer>(data, "answer");
+```
+
+If the specified type requires conversion, you can't take a reference to the value.
+See also [underlying types](#underlying-types).
+
+**NOTE**: For some technical reason, automatic conversion between `integer` and
+`floating` is not supported. If you want to get a floating value even if a value
+has integer value, you need to convert it manually after obtaining a value,
+like the following.
+
+```cpp
+const auto vx = toml::find(data, "x");
+double x = vx.is_floating() ? vx.as_floating(std::nothrow) :
+           static_cast<double>(vx.as_integer()); // it throws if vx is neither
+                                                 // floating nor integer.
+```
+
+### Finding a value in a table
+
+There are several way to get a value defined in a table.
+First, you can get a table as a normal value and find a value from the table.
+
+```toml
+[fruit]
+name = "apple"
+[fruit.physical]
+color = "red"
+shape = "round"
+```
+
+``` cpp
+const auto  data  = toml::parse("fruit.toml");
+const auto& fruit = toml::find(data, "fruit");
+const auto  name  = toml::find<std::string>(fruit, "name");
+
+const auto& physical = toml::find(fruit, "physical");
+const auto  color    = toml::find<std::string>(physical, "color");
+const auto  shape    = toml::find<std::string>(physical, "shape");
+```
+
+Here, variable `fruit` is a `toml::value` and can be used as the first argument
+of `toml::find`.
+
+Second, you can pass as many arguments as the number of subtables to `toml::find`.
+
+```cpp
+const auto data  = toml::parse("fruit.toml");
+const auto color = toml::find<std::string>(data, "fruit", "physical", "color");
+const auto shape = toml::find<std::string>(data, "fruit", "physical", "shape");
+```
+
+### Finding a value in an array
+
+You can find n-th value in an array by `toml::find`.
+
+```toml
+values = ["foo", "bar", "baz"]
+```
+
+``` cpp
+const auto data   = toml::parse("sample.toml");
+const auto values = toml::find(data, "values");
+const auto bar    = toml::find<std::string>(values, 1);
+```
+
+`toml::find` can also search array recursively.
+
+```cpp
+const auto data = toml::parse("fruit.toml");
+const auto bar  = toml::find<std::string>(data, "values", 1);
+```
+
+Before calling `toml::find`, you can check if a value corresponding to a key
+exists. You can use both `bool toml::value::contains(const key&) const` and
+`std::size_t toml::value::count(const key&) const`. Those behaves like the
+`std::map::contains` and `std::map::count`.
+
+```cpp
+const auto data = toml::parse("fruit.toml");
+if(data.contains("fruit") && data.at("fruit").count("physical") != 0)
+{
+    // ...
+}
+```
+
+### In case of error
+
+If the value does not exist, `toml::find` throws `std::out_of_range` with the
+location of the table.
+
+```console
+terminate called after throwing an instance of 'std::out_of_range'
+  what():  [error] key "answer" not found
+ --> example.toml
+ 6 | [tab]
+   | ~~~~~ in this table
+```
+
+----
+
+If the specified type differs from the actual value contained, it throws
+`toml::type_error` that inherits `std::exception`.
+
+Similar to the case of syntax error, toml11 also displays clean error messages.
+The error message when you choose `int` to get `string` value would be like this.
+
+```console
+terminate called after throwing an instance of 'toml::type_error'
+  what():  [error] toml::value bad_cast to integer
+ --> example.toml
+ 3 | title = "TOML Example"
+   |         ~~~~~~~~~~~~~~ the actual type is string
+```
+
+**NOTE**: In order to show this kind of error message, all the toml values have
+a pointer to represent its range in a file. The entire contents of a file is
+shared by `toml::value`s and remains on the heap memory. It is recommended to
+destruct all the `toml::value` classes after configuring your application
+if you have a large TOML file compared to the memory resource.
+
+### Dotted keys
+
+TOML v0.5.0 has a new feature named "dotted keys".
+You can chain keys to represent the structure of the data.
+
+```toml
+physical.color = "orange"
+physical.shape = "round"
+```
+
+This is equivalent to the following.
+
+```toml
+[physical]
+color = "orange"
+shape = "round"
+```
+
+You can get both of the above tables with the same c++ code.
+
+```cpp
+const auto physical = toml::find(data, "physical");
+const auto color    = toml::find<std::string>(physical, "color");
+```
+
+The following code does not work for the above toml file.
+
+```cpp
+// XXX this does not work!
+const auto color = toml::find<std::string>(data, "physical.color");
+```
+
+The above code works with the following toml file.
+
+```toml
+"physical.color" = "orange"
+# equivalent to {"physical.color": "orange"},
+# NOT {"physical": {"color": "orange"}}.
+```
+
+
+## Casting a toml value
+
+### `toml::get`
+
+`toml::parse` returns `toml::value`. `toml::value` is a union type that can
+contain one of the following types.
+
+- `toml::boolean` (`bool`)
+- `toml::integer` (`std::int64_t`)
+- `toml::floating` (`double`)
+- `toml::string` (a type convertible to std::string)
+- `toml::local_date`
+- `toml::local_time`
+- `toml::local_datetime`
+- `toml::offset_datetime`
+- `toml::array` (by default, `std::vector<toml::value>`)
+  - It depends. See [customizing containers](#customizing-containers) for detail.
+- `toml::table` (by default, `std::unordered_map<toml::key, toml::value>`)
+  - It depends. See [customizing containers](#customizing-containers) for detail.
+
+To get a value inside, you can use `toml::get<T>()`. The usage is the same as
+`toml::find<T>` (actually, `toml::find` internally uses `toml::get` after casting
+a value to `toml::table`).
+
+``` cpp
+const toml::value  data    = toml::parse("sample.toml");
+const toml::value  answer_ = toml::get<toml::table >(data).at("answer");
+const std::int64_t answer  = toml::get<std::int64_t>(answer_);
+```
+
+When you pass an exact TOML type that does not require type conversion,
+`toml::get` returns a reference through which you can modify the content
+(if the `toml::value` is `const`, it returns `const` reference).
+
+```cpp
+toml::value   data    = toml::parse("sample.toml");
+toml::value   answer_ = toml::get<toml::table >(data).at("answer");
+toml::integer& answer = toml::get<toml::integer>(answer_);
+answer = 6 * 9; // write to data.answer. now `answer_` contains 54.
+```
+
+If the specified type requires conversion, you can't take a reference to the value.
+See also [underlying types](#underlying-types).
+
+It also throws a `toml::type_error` if the type differs.
+
+### `as_xxx`
+
+You can also use a member function to cast a value.
+
+```cpp
+const std::int64_t answer = data.as_table().at("answer").as_integer();
+```
+
+It also throws a `toml::type_error` if the type differs. If you are sure that
+the value `v` contains a value of the specified type, you can suppress checking
+by passing `std::nothrow`.
+
+```cpp
+const auto& answer = data.as_table().at("answer");
+if(answer.is_integer() && answer.as_integer(std::nothrow) == 42)
+{
+    std::cout << "value is 42" << std::endl;
+}
+```
+
+If `std::nothrow` is passed, the functions are marked as noexcept.
+
+By casting a `toml::value` into an array or a table, you can iterate over the
+elements.
+
+```cpp
+const auto data = toml::parse("example.toml");
+std::cout << "keys in the top-level table are the following: \n";
+for(const auto& [k, v] : data.as_table())
+{
+    std::cout << k << '\n';
+}
+
+const auto& fruits = toml::find(data, "fruits");
+for(const auto& v : fruits.as_array())
+{
+    std::cout << toml::find<std::string>(v, "name") << '\n';
+}
+```
+
+The full list of the functions is below.
+
+```cpp
+namespace toml {
+class value {
+    // ...
+    const boolean&         as_boolean()         const&;
+    const integer&         as_integer()         const&;
+    const floating&        as_floating()        const&;
+    const string&          as_string()          const&;
+    const offset_datetime& as_offset_datetime() const&;
+    const local_datetime&  as_local_datetime()  const&;
+    const local_date&      as_local_date()      const&;
+    const local_time&      as_local_time()      const&;
+    const array&           as_array()           const&;
+    const table&           as_table()           const&;
+    // --------------------------------------------------------
+    // non-const version
+    boolean&               as_boolean()         &;
+    // ditto...
+    // --------------------------------------------------------
+    // rvalue version
+    boolean&&              as_boolean()         &&;
+    // ditto...
+
+    // --------------------------------------------------------
+    // noexcept versions ...
+    const boolean&         as_boolean(const std::nothrow_t&) const& noexcept;
+    boolean&               as_boolean(const std::nothrow_t&) &      noexcept;
+    boolean&&              as_boolean(const std::nothrow_t&) &&     noexcept;
+    // ditto...
+};
+} // toml
+```
+
+### `at()`
+
+You can access to the element of a table and an array by `toml::basic_value::at`.
+
+```cpp
+const toml::value v{1,2,3,4,5};
+std::cout << v.at(2).as_integer() << std::endl; // 3
+
+const toml::value v{{"foo", 42}, {"bar", 3.14}};
+std::cout << v.at("foo").as_integer() << std::endl; // 42
+```
+
+If an invalid key (integer for a table, string for an array), it throws
+`toml::type_error` for the conversion. If the provided key is out-of-range,
+it throws `std::out_of_range`.
+
+Note that, although `std::string` has `at()` member function, `toml::value::at`
+throws if the contained type is a string. Because `std::string` does not
+contain `toml::value`.
+
+### `operator[]`
+
+You can also access to the element of a table and an array by
+`toml::basic_value::operator[]`.
+
+```cpp
+const toml::value v{1,2,3,4,5};
+std::cout << v[2].as_integer() << std::endl; // 3
+
+const toml::value v{{"foo", 42}, {"bar", 3.14}};
+std::cout << v["foo"].as_integer() << std::endl; // 42
+```
+
+When you access to a `toml::value` that is not initialized yet via
+`operator[](const std::string&)`, the `toml::value` will be a table,
+just like the `std::map`.
+
+```cpp
+toml::value v; // not initialized as a table.
+v["foo"] = 42; // OK. `v` will be a table.
+```
+
+Contrary, if you access to a `toml::value` that contains an array via `operator[]`,
+it does not check anything. It converts `toml::value` without type check and then
+access to the n-th element without boundary check, just like the `std::vector::operator[]`.
+
+```cpp
+toml::value v; // not initialized as an array
+v[2] = 42;     // error! UB
+```
+
+Please make sure that the `toml::value` has an array inside when you access to
+its element via `operator[]`.
+
+## Checking value type
+
+You can check the type of a value by `is_xxx` function.
+
+```cpp
+const toml::value v = /* ... */;
+if(v.is_integer())
+{
+    std::cout << "value is an integer" << std::endl;
+}
+```
+
+The complete list of the functions is below.
+
+```cpp
+namespace toml {
+class value {
+    // ...
+    bool is_boolean()         const noexcept;
+    bool is_integer()         const noexcept;
+    bool is_floating()        const noexcept;
+    bool is_string()          const noexcept;
+    bool is_offset_datetime() const noexcept;
+    bool is_local_datetime()  const noexcept;
+    bool is_local_date()      const noexcept;
+    bool is_local_time()      const noexcept;
+    bool is_array()           const noexcept;
+    bool is_table()           const noexcept;
+    bool is_uninitialized()   const noexcept;
+    // ...
+};
+} // toml
+```
+
+Also, you can get `enum class value_t` from `toml::value::type()`.
+
+```cpp
+switch(data.at("something").type())
+{
+    case toml::value_t::integer:  /*do some stuff*/ ; break;
+    case toml::value_t::floating: /*do some stuff*/ ; break;
+    case toml::value_t::string :  /*do some stuff*/ ; break;
+    default : throw std::runtime_error(
+        "unexpected type : " + toml::stringize(data.at("something").type()));
+}
+```
+
+The complete list of the `enum`s can be found in the section
+[underlying types](#underlying-types).
+
+The `enum`s can be used as a parameter of `toml::value::is` function like the following.
+
+```cpp
+toml::value v = /* ... */;
+if(v.is(toml::value_t::boolean)) // ...
+```
+
+## More about conversion
+
+Since `toml::find` internally uses `toml::get`, all the following examples work
+with both `toml::get` and `toml::find`.
+
+### Converting an array
+
+You can get any kind of `container` class from a `toml::array`
+except for `map`-like classes.
+
+``` cpp
+// # sample.toml
+// numbers = [1,2,3]
+
+const auto numbers = toml::find(data, "numbers");
+
+const auto vc  = toml::get<std::vector<int>  >(numbers);
+const auto ls  = toml::get<std::list<int>    >(numbers);
+const auto dq  = toml::get<std::deque<int>   >(numbers);
+const auto ar  = toml::get<std::array<int, 3>>(numbers);
+// if the size of data.at("numbers") is larger than that of std::array,
+// it will throw toml::type_error because std::array is not resizable.
+```
+
+Surprisingly, you can convert `toml::array` into `std::pair` and `std::tuple`.
+
+```cpp
+// numbers = [1,2,3]
+const auto tp = toml::get<std::tuple<short, int, unsigned int>>(numbers);
+```
+
+This functionality is helpful when you have a toml file like the following.
+
+```toml
+array_of_arrays = [[1, 2, 3], ["foo", "bar", "baz"]] # toml allows this
+```
+
+What is the corresponding C++ type?
+Obviously, it is a `std::pair` of `std::vector`s.
+
+```cpp
+const auto array_of_arrays = toml::find(data, "array_of_arrays");
+const auto aofa = toml::get<
+    std::pair<std::vector<int>, std::vector<std::string>>
+    >(array_of_arrays);
+```
+
+If you don't know the type of the elements, you can use `toml::array`,
+which is a `std::vector` of `toml::value`, instead.
+
+```cpp
+const auto a_of_a = toml::get<toml::array>(array_of_arrays);
+const auto first  = toml::get<std::vector<int>>(a_of_a.at(0));
+```
+
+You can change the implementation of `toml::array` with `std::deque` or some
+other array-like container. See [Customizing containers](#customizing-containers)
+for detail.
+
+### Converting a table
+
+When all the values of the table have the same type, toml11 allows you to
+convert a `toml::table` to a `map` that contains the convertible type.
+
+```toml
+[tab]
+key1 = "foo" # all the values are
+key2 = "bar" # toml String
+```
+
+```cpp
+const auto data = toml::parse("sample.toml");
+const auto tab = toml::find<std::map<std::string, std::string>>(data, "tab");
+std::cout << tab["key1"] << std::endl; // foo
+std::cout << tab["key2"] << std::endl; // bar
+```
+
+But since `toml::table` is just an alias of `std::unordered_map<toml::key, toml::value>`,
+normally you don't need to convert it because it has all the functionalities that
+`std::unordered_map` has (e.g. `operator[]`, `count`, and `find`). In most cases
+`toml::table` is sufficient.
+
+```cpp
+toml::table tab = toml::get<toml::table>(data);
+if(data.count("title") != 0)
+{
+    data["title"] = std::string("TOML example");
+}
+```
+
+You can change the implementation of `toml::table` with `std::map` or some
+other map-like container. See [Customizing containers](#customizing-containers)
+for detail.
+
+### Getting an array of tables
+
+An array of tables is just an array of tables.
+You can get it in completely the same way as the other arrays and tables.
+
+```toml
+# sample.toml
+array_of_inline_tables = [{key = "value1"}, {key = "value2"}, {key = "value3"}]
+
+[[array_of_tables]]
+key = "value4"
+[[array_of_tables]]
+key = "value5"
+[[array_of_tables]]
+key = "value6"
+```
+
+```cpp
+const auto data = toml::parse("sample.toml");
+const auto aot1 = toml::find<std::vector<toml::table>>(data, "array_of_inline_tables");
+const auto aot2 = toml::find<std::vector<toml::table>>(data, "array_of_tables");
+```
+
+### Cost of conversion
+
+Although conversion through `toml::(get|find)` is convenient, it has additional
+copy-cost because it copies data contained in `toml::value` to the
+user-specified type. Of course in some cases this overhead is not ignorable.
+
+```cpp
+// the following code constructs a std::vector.
+// it requires heap allocation for vector and element conversion.
+const auto array = toml::find<std::vector<int>>(data, "foo");
+```
+
+By passing the exact types, `toml::get` returns reference that has no overhead.
+
+``` cpp
+const auto& tab     = toml::find<toml::table>(data, "tab");
+const auto& numbers = toml::find<toml::array>(data, "numbers");
+```
+
+Also, `as_xxx` are zero-overhead because they always return a reference.
+
+``` cpp
+const auto& tab     = toml::find(data, "tab"    ).as_table();
+const auto& numbers = toml::find(data, "numbers").as_array();
+```
+
+In this case you need to call `toml::get` each time you access to
+the element of `toml::array` because `toml::array` is an array of `toml::value`.
+
+```cpp
+const auto& num0 = toml::get<toml::integer>(numbers.at(0));
+const auto& num1 = toml::get<toml::integer>(numbers.at(1));
+const auto& num2 = toml::get<toml::integer>(numbers.at(2));
+```
+
+### Converting datetime and its variants
+
+TOML v0.5.0 has 4 different datetime objects, `local_date`, `local_time`,
+`local_datetime`, and `offset_datetime`.
+
+Since `local_date`, `local_datetime`, and `offset_datetime` represent a time
+point, you can convert them to `std::chrono::system_clock::time_point`.
+
+Contrary, `local_time` does not represents a time point because they lack a
+date information, but it can be converted to `std::chrono::duration` that
+represents a duration from the beginning of the day, `00:00:00.000`.
+
+```toml
+# sample.toml
+date = 2018-12-23
+time = 12:30:00
+l_dt = 2018-12-23T12:30:00
+o_dt = 2018-12-23T12:30:00+09:30
+```
+
+```cpp
+const auto data = toml::parse("sample.toml");
+
+const auto date = toml::get<std::chrono::system_clock::time_point>(data.at("date"));
+const auto l_dt = toml::get<std::chrono::system_clock::time_point>(data.at("l_dt"));
+const auto o_dt = toml::get<std::chrono::system_clock::time_point>(data.at("o_dt"));
+
+const auto time = toml::get<std::chrono::minutes>(data.at("time")); // 12 * 60 + 30 min
+```
+
+`local_date` and `local_datetime` are assumed to be in the local timezone when
+they are converted into `time_point`. On the other hand, `offset_datetime` only
+uses the offset part of the data and it does not take local timezone into account.
+
+To contain datetime data, toml11 defines its own datetime types.
+For more detail, you can see the definitions in [toml/datetime.hpp](toml/datetime.hpp).
+
+## Getting with a fallback
+
+`toml::find_or` returns a default value if the value is not found or has a
+different type.
+
+```cpp
+const auto data = toml::parse("example.toml");
+const auto num  = toml::find_or(data, "num", 42);
+```
+
+It works recursively if you pass several keys for subtables.
+In that case, the last argument is considered to be the optional value.
+All other arguments between `toml::value` and the optinoal value are considered as keys.
+
+```cpp
+// [fruit.physical]
+// color = "red"
+auto data  = toml::parse("fruit.toml");
+auto color = toml::find_or(data, "fruit", "physical", "color", "red");
+//                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^  ^^^^^
+//                               arguments                     optional value
+```
+
+Also, `toml::get_or` returns a default value if `toml::get<T>` failed.
+
+```cpp
+toml::value v("foo"); // v contains String
+const int value = toml::get_or(v, 42); // conversion fails. it returns 42.
+```
+
+These functions automatically deduce what type you want to get
+from the default value you passed.
+
+To get a reference through this function, take care about the default value.
+
+```cpp
+toml::value v("foo"); // v contains String
+toml::integer& i = toml::get_or(v, 42); // does not work because binding `42`
+                                        // to `integer&` is invalid
+toml::integer opt = 42;
+toml::integer& i = toml::get_or(v, opt); // this works.
+```
+
+## Expecting conversion
+
+By using `toml::expect`, you will get your expected value or an error message
+without throwing `toml::type_error`.
+
+```cpp
+const auto value = toml::expect<std::string>(data.at("title"));
+if(value.is_ok()) {
+    std::cout << value.unwrap() << std::endl;
+} else {
+    std::cout << value.unwrap_err() << std::endl;
+}
+```
+
+Also, you can pass a function object to modify the expected value.
+
+```cpp
+const auto value = toml::expect<int>(data.at("number"))
+    .map(// function that receives expected type (here, int)
+    [](const int number) -> double {
+        return number * 1.5 + 1.0;
+    }).unwrap_or(/*default value =*/ 3.14);
+```
+
+## Visiting a toml::value
+
+toml11 provides `toml::visit` to apply a function to `toml::value` in the
+same way as `std::variant`.
+
+```cpp
+const toml::value v(3.14);
+toml::visit([](const auto& val) -> void {
+        std::cout << val << std::endl;
+    }, v);
+```
+
+The function object that would be passed to `toml::visit` must be able to
+receive all the possible TOML types. Also, the result types should be the same
+each other.
+
+## Constructing a toml::value
+
+`toml::value` can be constructed in various ways.
+
+```cpp
+toml::value v(true);     // boolean
+toml::value v(42);       // integer
+toml::value v(3.14);     // floating
+toml::value v("foobar"); // string
+toml::value v(toml::local_date(2019, toml::month_t::Apr, 1)); // date
+toml::value v{1, 2, 3, 4, 5};                                 // array
+toml::value v{{"foo", 42}, {"bar", 3.14}, {"baz", "qux"}};    // table
+```
+
+When constructing a string, you can choose to use either literal or basic string.
+By default, it will be a basic string.
+
+```cpp
+toml::value v("foobar", toml::string_t::basic  );
+toml::value v("foobar", toml::string_t::literal);
+```
+
+Datetime objects can be constructed from `std::tm` and
+`std::chrono::system_clock::time_point`. But you need to specify what type
+you use to avoid ambiguity.
+
+```cpp
+const auto now = std::chrono::system_clock::now();
+toml::value v(toml::local_date(now));
+toml::value v(toml::local_datetime(now));
+toml::value v(toml::offset_datetime(now));
+```
+
+Since local time is not equivalent to a time point, because it lacks date
+information, it will be constructed from `std::chrono::duration`.
+
+```cpp
+toml::value v(toml::local_time(std::chrono::hours(10)));
+```
+
+You can construct an array object not only from `initializer_list`, but also
+from STL containers. In that case, the element type must be convertible to
+`toml::value`.
+
+```cpp
+std::vector<int> vec{1,2,3,4,5};
+toml::value v(vec);
+```
+
+When you construct an array value, all the elements of `initializer_list`
+must be convertible into `toml::value`.
+
+If a `toml::value` has an array, you can `push_back` an element in it.
+
+```cpp
+toml::value v{1,2,3,4,5};
+v.push_back(6);
+```
+
+`emplace_back` also works.
+
+## Preserving comments
+
+toml11 v3 or later allows you yo choose whether comments are preserved or not via template parameter
+
+```cpp
+const auto data1 = toml::parse<toml::discard_comments >("example.toml");
+const auto data2 = toml::parse<toml::preserve_comments>("example.toml");
+```
+
+or macro definition.
+
+```cpp
+#define TOML11_PRESERVE_COMMENTS_BY_DEFAULT
+#include <toml11/toml.hpp>
+```
+
+This feature is controlled by template parameter in `toml::basic_value<...>`.
+`toml::value` is an alias of `toml::basic_value<...>`.
+
+If template parameter is explicitly specified, the return value of `toml::parse`
+will be `toml::basic_value<toml::preserve_comments>`.
+If the macro is defined, the alias `toml::value` will be
+`toml::basic_value<toml::preserve_comments>`.
+
+Comments related to a value can be obtained by `toml::value::comments()`.
+The return value has the same interface as `std::vector<std::string>`.
+
+```cpp
+const auto& com = v.comments();
+for(const auto& c : com)
+{
+    std::cout << c << std::endl;
+}
+```
+
+Comments just before and just after (within the same line) a value are kept in a value.
+
+```toml
+# this is a comment for v1.
+v1 = "foo"
+
+v2 = "bar" # this is a comment for v2.
+# Note that this comment is NOT a comment for v2.
+
+# this comment is not related to any value
+# because there are empty lines between v3.
+# this comment will be ignored even if you set `preserve_comments`.
+
+# this is a comment for v3
+# this is also a comment for v3.
+v3 = "baz" # ditto.
+```
+
+Each comment line becomes one element of a `std::vector`.
+
+Hash signs will be removed, but spaces after hash sign will not be removed.
+
+```cpp
+v1.comments().at(0) == " this is a comment for v1."s;
+
+v2.comments().at(1) == " this is a comment for v1."s;
+
+v3.comments().at(0) == " this is a comment for v3."s;
+v3.comments().at(1) == " this is also a comment for v3."s;
+v3.comments().at(2) == " ditto."s;
+```
+
+Note that a comment just after an opening brace of an array will not be a
+comment for the array.
+
+```toml
+# this is a comment for a.
+a = [ # this is not a comment for a. this will be ignored.
+  1, 2, 3,
+  # this is a comment for `42`.
+  42, # this is also a comment for `42`.
+  5
+] # this is a comment for a.
+```
+
+You can also append and modify comments.
+The interfaces are the same as `std::vector<std::string>`.
+
+```cpp
+toml::basic_value<toml::preserve_comments> v(42);
+v.comments().push_back(" add this comment.");
+// # add this comment.
+// i = 42
+```
+
+Also, you can pass a `std::vector<std::string>` when constructing a
+`toml::basic_value<toml::preserve_comments>`.
+
+```cpp
+std::vector<std::string> comments{"comment 1", "comment 2"};
+const toml::basic_value<toml::preserve_comments> v1(42, std::move(comments));
+const toml::basic_value<toml::preserve_comments> v2(42, {"comment 1", "comment 2"});
+```
+
+When `toml::discard_comments` is chosen, comments will not be contained in a value.
+`value::comments()` will always be kept empty.
+All the modification on comments would be ignored.
+All the element access in a `discard_comments` causes the same error as accessing
+an element of an empty `std::vector`.
+
+The comments will also be serialized. If comments exist, those comments will be
+added just before the values.
+
+__NOTE__: Result types from `toml::parse(...)` and
+`toml::parse<toml::preserve_comments>(...)` are different.
+
+## Customizing containers
+
+Actually, `toml::basic_value` has 3 template arguments.
+
+```cpp
+template<typename Comment, // discard/preserve_comment
+         template<typename ...> class Table = std::unordered_map,
+         template<typename ...> class Array = std::vector>
+class basic_value;
+```
+
+This enables you to change the containers used inside. E.g. you can use
+`std::map` to contain a table object instead of `std::unordered_map`.
+And also can use `std::deque` as a array object instead of `std::vector`.
+
+You can set these parameters while calling `toml::parse` function.
+
+```cpp
+const auto data = toml::parse<
+    toml::preserve_comments, std::map, std::deque
+    >("example.toml");
+```
+
+Needless to say, the result types from `toml::parse(...)` and
+`toml::parse<Com, Map, Cont>(...)` are different (unless you specify the same
+types as default).
+
+Note that, since `toml::table` and `toml::array` is an alias for a table and an
+array of a default `toml::value`, so it is different from the types actually
+contained in a `toml::basic_value` when you customize containers.
+To get the actual type in a generic way, use
+`typename toml::basic_type<C, T, A>::table_type` and
+`typename toml::basic_type<C, T, A>::array_type`.
+
+## TOML literal
+
+toml11 supports `"..."_toml` literal.
+It accept both a bare value and a file content.
+
+```cpp
+using namespace toml::literals::toml_literals;
+
+// `_toml` can convert a bare value without key
+const toml::value v = u8"0xDEADBEEF"_toml;
+// v is an Integer value containing 0xDEADBEEF.
+
+// raw string literal (`R"(...)"` is useful for this purpose)
+const toml::value t = u8R"(
+    title = "this is TOML literal"
+    [table]
+    key = "value"
+)"_toml;
+// the literal will be parsed and the result will be contained in t
+```
+
+The literal function is defined in the same way as the standard library literals
+such as `std::literals::string_literals::operator""s`.
+
+```cpp
+namespace toml
+{
+inline namespace literals
+{
+inline namespace toml_literals
+{
+toml::value operator"" _toml(const char* str, std::size_t len);
+} // toml_literals
+} // literals
+} // toml
+```
+
+Access to the operator can be gained with `using namespace toml::literals;`,
+`using namespace toml::toml_literals`, and `using namespace toml::literals::toml_literals`.
+
+Note that a key that is composed only of digits is allowed in TOML.
+And, unlike the file parser, toml-literal allows a bare value without a key.
+Thus it is difficult to distinguish arrays having integers and definitions of
+tables that are named as digits.
+Currently, literal `[1]` becomes a table named "1".
+To ensure a literal to be considered as an array with one element, you need to
+add a comma after the first element (like `[1,]`).
+
+```cpp
+"[1,2,3]"_toml;   // This is an array
+"[table]"_toml;   // This is a table that has an empty table named "table" inside.
+"[[1,2,3]]"_toml; // This is an array of arrays
+"[[table]]"_toml; // This is a table that has an array of tables inside.
+
+"[[1]]"_toml;     // This literal is ambiguous.
+                  // Currently, it becomes a table that has array of table "1".
+"1 = [{}]"_toml;  // This is a table that has an array of table named 1.
+"[[1,]]"_toml;    // This is an array of arrays.
+"[[1],]"_toml;    // ditto.
+```
+
+NOTE: `_toml` literal returns a `toml::value`  that does not have comments.
+
+## Conversion between toml value and arbitrary types
+
+You can also use `toml::get` and other related functions with the types
+you defined after you implement a way to convert it.
+
+```cpp
+namespace ext
+{
+struct foo
+{
+    int         a;
+    double      b;
+    std::string c;
+};
+} // ext
+
+const auto data = toml::parse("example.toml");
+
+// to do this
+const foo f = toml::find<ext::foo>(data, "foo");
+```
+
+There are 3 ways to use `toml::get` with the types that you defined.
+
+The first one is to implement `from_toml(const toml::value&)` member function.
+
+```cpp
+namespace ext
+{
+struct foo
+{
+    int         a;
+    double      b;
+    std::string c;
+
+    void from_toml(const toml::value& v)
+    {
+        this->a = toml::find<int        >(v, "a");
+        this->b = toml::find<double     >(v, "b");
+        this->c = toml::find<std::string>(v, "c");
+        return;
+    }
+};
+} // ext
+```
+
+In this way, because `toml::get` first constructs `foo` without arguments,
+the type should be default-constructible.
+
+The second is to implement `constructor(const toml::value&)`.
+
+```cpp
+namespace ext
+{
+struct foo
+{
+    explicit foo(const toml::value& v)
+        : a(toml::find<int>(v, "a")), b(toml::find<double>(v, "b")),
+          c(toml::find<std::string>(v, "c"))
+    {}
+
+    int         a;
+    double      b;
+    std::string c;
+};
+} // ext
+```
+
+Note that implicit default constructor declaration will be suppressed
+when a constructor is defined. If you want to use the struct (here, `foo`)
+in a container (e.g. `std::vector<foo>`), you may need to define default
+constructor explicitly.
+
+The third is to implement specialization of `toml::from` for your type.
+
+```cpp
+namespace ext
+{
+struct foo
+{
+    int         a;
+    double      b;
+    std::string c;
+};
+} // ext
+
+namespace toml
+{
+template<>
+struct from<ext::foo>
+{
+    static ext::foo from_toml(const value& v)
+    {
+        ext::foo f;
+        f.a = find<int        >(v, "a");
+        f.b = find<double     >(v, "b");
+        f.c = find<std::string>(v, "c");
+        return f;
+    }
+};
+} // toml
+```
+
+In this way, since the conversion function is defined outside of the class,
+you can add conversion between `toml::value` and classes defined in another library.
+
+In some cases, a class has a templatized constructor that takes a template, `T`.
+It confuses `toml::get/find<T>` because it makes the class "constructible" from
+`toml::value`. To avoid this problem, `toml::from` and `from_toml` always
+precede constructor. It makes easier to implement conversion between
+`toml::value` and types defined in other libraries because it skips constructor.
+
+But, importantly, you cannot define `toml::from<T>` and `T.from_toml` at the same
+time because it causes ambiguity in the overload resolution of `toml::get<T>` and `toml::find<T>`.
+
+So the precedence is `toml::from<T>` == `T.from_toml()` > `T(toml::value)`.
+
+If you want to convert any versions of `toml::basic_value`,
+you need to templatize the conversion function as follows.
+
+```cpp
+struct foo
+{
+    template<typename C, template<typename ...> class M, template<typename ...> class A>
+    void from_toml(const toml::basic_value<C, M, A>& v)
+    {
+        this->a = toml::find<int        >(v, "a");
+        this->b = toml::find<double     >(v, "b");
+        this->c = toml::find<std::string>(v, "c");
+        return;
+    }
+};
+// or
+namespace toml
+{
+template<>
+struct from<ext::foo>
+{
+    template<typename C, template<typename ...> class M, template<typename ...> class A>
+    static ext::foo from_toml(const basic_value<C, M, A>& v)
+    {
+        ext::foo f;
+        f.a = find<int        >(v, "a");
+        f.b = find<double     >(v, "b");
+        f.c = find<std::string>(v, "c");
+        return f;
+    }
+};
+} // toml
+```
+
+----
+
+The opposite direction is also supported in a similar way. You can directly
+pass your type to `toml::value`'s constructor by introducing `into_toml` or
+`toml::into<T>`.
+
+```cpp
+namespace ext
+{
+struct foo
+{
+    int         a;
+    double      b;
+    std::string c;
+
+    toml::value into_toml() const // you need to mark it const.
+    {
+        return toml::value{{"a", this->a}, {"b", this->b}, {"c", this->c}};
+    }
+};
+} // ext
+
+ext::foo    f{42, 3.14, "foobar"};
+toml::value v(f);
+```
+
+The definition of `toml::into<T>` is similar to `toml::from<T>`.
+
+```cpp
+namespace ext
+{
+struct foo
+{
+    int         a;
+    double      b;
+    std::string c;
+};
+} // ext
+
+namespace toml
+{
+template<>
+struct into<ext::foo>
+{
+    static toml::value into_toml(const ext::foo& f)
+    {
+        return toml::value{{"a", f.a}, {"b", f.b}, {"c", f.c}};
+    }
+};
+} // toml
+
+ext::foo    f{42, 3.14, "foobar"};
+toml::value v(f);
+```
+
+Any type that can be converted to `toml::value`, e.g. `int`, `toml::table` and
+`toml::array` are okay to return from `into_toml`.
+
+You can also return a custom `toml::basic_value` from `toml::into`.
+
+```cpp
+namespace toml
+{
+template<>
+struct into<ext::foo>
+{
+    static toml::basic_value<toml::preserve_comments> into_toml(const ext::foo& f)
+    {
+        toml::basic_value<toml::preserve_comments> v{{"a", f.a}, {"b", f.b}, {"c", f.c}};
+        v.comments().push_back(" comment");
+        return v;
+    }
+};
+} // toml
+```
+
+But note that, if this `basic_value` would be assigned into other `toml::value`
+that discards `comments`, the comments would be dropped.
+
+### Macro to automatically define conversion functions
+
+There is a helper macro that automatically generates conversion functions `from` and `into` for a simple struct.
+
+```cpp
+namespace foo
+{
+struct Foo
+{
+    std::string s;
+    double      d;
+    int         i;
+};
+} // foo
+
+TOML11_DEFINE_CONVERSION_NON_INTRUSIVE(foo::Foo, s, d, i)
+
+int main()
+{
+    const auto file = toml::parse("example.toml");
+    auto f = toml::find<foo::Foo>(file, "foo");
+}
+```
+
+And then you can use `toml::find<foo::Foo>(file, "foo");`
+
+**Note** that, because of a slight difference in implementation of preprocessor between gcc/clang and MSVC, [you need to define `/Zc:preprocessor`](https://github.com/ToruNiina/toml11/issues/139#issuecomment-803683682) to use it in MSVC (Thank you @glebm !).
+
+## Formatting user-defined error messages
+
+When you encounter an error after you read the toml value, you may want to
+show the error with the value.
+
+toml11 provides you a function that formats user-defined error message with
+related values. With a code like the following,
+
+```cpp
+const auto value = toml::find<int>(data, "num");
+if(value < 0)
+{
+    std::cerr << toml::format_error("[error] value should be positive",
+                                    data.at("num"), "positive number required")
+              << std::endl;
+}
+```
+
+you will get an error message like this.
+
+```console
+[error] value should be positive
+ --> example.toml
+ 3 | num = -42
+   |       ~~~ positive number required
+```
+
+When you pass two values to `toml::format_error`,
+
+```cpp
+const auto min = toml::find<int>(range, "min");
+const auto max = toml::find<int>(range, "max");
+if(max < min)
+{
+    std::cerr << toml::format_error("[error] max should be larger than min",
+                                    data.at("min"), "minimum number here",
+                                    data.at("max"), "maximum number here");
+              << std::endl;
+}
+```
+
+you will get an error message like this.
+
+```console
+[error] max should be larger than min
+ --> example.toml
+ 3 | min = 54
+   |       ~~ minimum number here
+ ...
+ 4 | max = 42
+   |       ~~ maximum number here
+```
+
+You can print hints at the end of the message.
+
+```cpp
+std::vector<std::string> hints;
+hints.push_back("positive number means n >= 0.");
+hints.push_back("negative number is not positive.");
+std::cerr << toml::format_error("[error] value should be positive",
+                                data.at("num"), "positive number required", hints)
+          << std::endl;
+```
+
+```console
+[error] value should be positive
+ --> example.toml
+ 2 | num = 42
+   |       ~~ positive number required
+   |
+Hint: positive number means n >= 0.
+Hint: negative number is not positive.
+```
+
+## Obtaining location information
+
+You can also format error messages in your own way by using `source_location`.
+
+```cpp
+struct source_location
+{
+    std::uint_least32_t line()      const noexcept;
+    std::uint_least32_t column()    const noexcept;
+    std::uint_least32_t region()    const noexcept;
+    std::string const&  file_name() const noexcept;
+    std::string const&  line_str()  const noexcept;
+};
+// +-- line()       +--- length of the region (here, region() == 9)
+// v            .---+---.
+// 12 | value = "foo bar" <- line_str() returns the line itself.
+//              ^-------- column() points here
+```
+
+You can get this by
+```cpp
+const toml::value           v   = /*...*/;
+const toml::source_location loc = v.location();
+```
+
+## Exceptions
+
+The following `exception` classes inherits `toml::exception` that inherits
+`std::exception`.
+
+```cpp
+namespace toml {
+struct exception      : public std::exception  {/**/};
+struct syntax_error   : public toml::exception {/**/};
+struct type_error     : public toml::exception {/**/};
+struct internal_error : public toml::exception {/**/};
+} // toml
+```
+
+`toml::exception` has `toml::exception::location()` member function that returns
+`toml::source_location`, in addition to `what()`.
+
+```cpp
+namespace toml {
+struct exception : public std::exception
+{
+    // ...
+    source_location const& location() const noexcept;
+};
+} // toml
+```
+
+It represents where the error occurs.
+
+`syntax_error` will be thrown from `toml::parse` and `_toml` literal.
+`type_error` will be thrown from `toml::get/find`, `toml::value::as_xxx()`, and
+other functions that takes a content inside of `toml::value`.
+
+Note that, currently, from `toml::value::at()` and `toml::find(value, key)`
+may throw an `std::out_of_range` that does not inherits `toml::exception`.
+
+Also, in some cases, most likely in the file open error, it will throw an
+`std::runtime_error`.
+
+## Colorize Error Messages
+
+By defining `TOML11_COLORIZE_ERROR_MESSAGE`, the error messages from
+`toml::parse` and `toml::find|get` will be colorized. By default, this feature
+is turned off.
+
+With the following toml file taken from `toml-lang/toml/tests/hard_example.toml`,
+
+```toml
+[error]
+array = [
+         "This might most likely happen in multiline arrays",
+         Like here,
+         "or here,
+         and here"
+        ]     End of array comment, forgot the #
+```
+
+the error message would be like this.
+
+![error-message-1](https://github.com/ToruNiina/toml11/blob/misc/misc/toml11-err-msg-1.png)
+
+With the following,
+
+```toml
+[error]
+# array = [
+#          "This might most likely happen in multiline arrays",
+#          Like here,
+#          "or here,
+#          and here"
+#         ]     End of array comment, forgot the #
+number = 3.14  pi <--again forgot the #
+```
+
+the error message would be like this.
+
+![error-message-2](https://github.com/ToruNiina/toml11/blob/misc/misc/toml11-err-msg-2.png)
+
+The message would be messy when it is written to a file, not a terminal because
+it uses [ANSI escape code](https://en.wikipedia.org/wiki/ANSI_escape_code).
+
+Without `TOML11_COLORIZE_ERROR_MESSAGE`, you can still colorize user-defined
+error message by passing `true` to the `toml::format_error` function.
+If you define `TOML11_COLORIZE_ERROR_MESSAGE`, the value is `true` by default.
+If not, the default value would be `false`.
+
+```cpp
+std::cerr << toml::format_error("[error] value should be positive",
+                                data.at("num"), "positive number required",
+                                hints, /*colorize = */ true) << std::endl;
+```
+
+Note: It colorize `[error]` in red. That means that it detects `[error]` prefix
+at the front of the error message. If there is no `[error]` prefix,
+`format_error` adds it to the error message.
+
+## Serializing TOML data
+
+toml11 enables you to serialize data into toml format.
+
+```cpp
+const toml::value data{{"foo", 42}, {"bar", "baz"}};
+std::cout << data << std::endl;
+// bar = "baz"
+// foo = 42
+```
+
+toml11 automatically makes a small table and small array inline.
+You can specify the width to make them inline by `std::setw` for streams.
+
+```cpp
+const toml::value data{
+    {"qux",    {{"foo", 42}, {"bar", "baz"}}},
+    {"quux",   {"small", "array", "of", "strings"}},
+    {"foobar", {"this", "array", "of", "strings", "is", "too", "long",
+                "to", "print", "into", "single", "line", "isn't", "it?"}},
+};
+
+// the threshold becomes 80.
+std::cout << std::setw(80) << data << std::endl;
+// foobar = [
+// "this","array","of","strings","is","too","long","to","print","into",
+// "single","line","isn't","it?",
+// ]
+// quux = ["small","array","of","strings"]
+// qux = {bar="baz",foo=42}
+
+
+// the width is 0. nothing become inline.
+std::cout << std::setw(0) << data << std::endl;
+// foobar = [
+// "this",
+// ... (snip)
+// "it?",
+// ]
+// quux = [
+// "small",
+// "array",
+// "of",
+// "strings",
+// ]
+// [qux]
+// bar = "baz"
+// foo = 42
+```
+
+It is recommended to set width before printing data. Some I/O functions changes
+width to 0, and it makes all the stuff (including `toml::array`) multiline.
+The resulting files becomes too long.
+
+To control the precision of floating point numbers, you need to pass
+`std::setprecision` to stream.
+
+```cpp
+const toml::value data{
+    {"pi", 3.141592653589793},
+    {"e",  2.718281828459045}
+};
+std::cout << std::setprecision(17) << data << std::endl;
+// e = 2.7182818284590451
+// pi = 3.1415926535897931
+std::cout << std::setprecision( 7) << data << std::endl;
+// e = 2.718282
+// pi = 3.141593
+```
+
+There is another way to format toml values, `toml::format()`.
+It returns `std::string` that represents a value.
+
+```cpp
+const toml::value v{{"a", 42}};
+const std::string fmt = toml::format(v);
+// a = 42
+```
+
+Note that since `toml::format` formats a value, the resulting string may lack
+the key value.
+
+```cpp
+const toml::value v{3.14};
+const std::string fmt = toml::format(v);
+// 3.14
+```
+
+To control the width and precision, `toml::format` receives optional second and
+third arguments to set them. By default, the width is 80 and the precision is
+`std::numeric_limits<double>::max_digit10`.
+
+```cpp
+const auto serial = toml::format(data, /*width = */ 0, /*prec = */ 17);
+```
+
+When you pass a comment-preserving-value, the comment will also be serialized.
+An array or a table containing a value that has a comment would not be inlined.
+
+## Underlying types
+
+The toml types (can be used as `toml::*` in this library) and corresponding `enum` names are listed in the table below.
+
+| TOML type      | underlying c++ type                | enum class                       |
+| -------------- | ---------------------------------- | -------------------------------- |
+| Boolean        | `bool`                             | `toml::value_t::boolean`         |
+| Integer        | `std::int64_t`                     | `toml::value_t::integer`         |
+| Float          | `double`                           | `toml::value_t::floating`        |
+| String         | `toml::string`                     | `toml::value_t::string`          |
+| LocalDate      | `toml::local_date`                 | `toml::value_t::local_date`      |
+| LocalTime      | `toml::local_time`                 | `toml::value_t::local_time`      |
+| LocalDatetime  | `toml::local_datetime`             | `toml::value_t::local_datetime`  |
+| OffsetDatetime | `toml::offset_datetime`            | `toml::value_t::offset_datetime` |
+| Array          | `array-like<toml::value>`          | `toml::value_t::array`           |
+| Table          | `map-like<toml::key, toml::value>` | `toml::value_t::table`           |
+
+`array-like` and `map-like` are the STL containers that works like a `std::vector` and
+`std::unordered_map`, respectively. By default, `std::vector` and `std::unordered_map`
+are used. See [Customizing containers](#customizing-containers) for detail.
+
+`toml::string` is effectively the same as `std::string` but has an additional
+flag that represents a kind of a string, `string_t::basic` and `string_t::literal`.
+Although `std::string` is not an exact toml type, still you can get a reference
+that points to internal `std::string` by using `toml::get<std::string>()` for convenience.
+The most important difference between `std::string` and `toml::string` is that
+`toml::string` will be formatted as a TOML string when outputted with `ostream`.
+This feature is introduced to make it easy to write a custom serializer.
+
+`Datetime` variants are `struct` that are defined in this library.
+Because `std::chrono::system_clock::time_point` is a __time point__,
+not capable of representing a Local Time independent from a specific day.
+
+## Unreleased TOML features
+
+Since TOML v1.0.0-rc.1 has been released, those features are now activated by
+default. We no longer need to define `TOML11_USE_UNRELEASED_FEATURES`.
+
+- Leading zeroes in exponent parts of floats are permitted.
+  - e.g. `1.0e+01`, `5e+05`
+  - [toml-lang/toml/PR/656](https://github.com/toml-lang/toml/pull/656)
+- Allow raw tab characters in basic strings and multi-line basic strings.
+  - [toml-lang/toml/PR/627](https://github.com/toml-lang/toml/pull/627)
+- Allow heterogeneous arrays
+  - [toml-lang/toml/PR/676](https://github.com/toml-lang/toml/pull/676)
+
+## Note about heterogeneous arrays
+
+Although `toml::parse` allows heterogeneous arrays, constructor of `toml::value`
+does not. Here the reason is explained.
+
+```cpp
+// this won't be compiled
+toml::value v{
+    "foo", 3.14, 42, {1,2,3,4,5}, {{"key", "value"}}
+}
+```
+
+There is a workaround for this. By explicitly converting values into
+`toml::value`, you can initialize `toml::value` with a heterogeneous array.
+Also, you can first initialize a `toml::value` with an array and then
+`push_back` into it.
+
+```cpp
+// OK!
+toml::value v{
+    toml::value("foo"), toml::value(3.14), toml::value(42),
+    toml::value{1,2,3,4,5}, toml::value{{"key", "value"}}
+}
+
+// OK!
+toml::value v(toml::array{});
+v.push_back("foo");
+v.push_back(3.14);
+
+// OK!
+toml::array a;
+a.push_back("foo");
+a.push_back(3.14);
+toml::value v(std::move(a));
+```
+
+The reason why the first example is not allowed is the following.
+Let's assume that you are initializing a `toml::value` with a table.
+
+```cpp
+                    // # expecting TOML table.
+toml::value v{      // [v]
+    {"answer", 42}, // answer = 42
+    {"pi",   3.14}, // pi = 3.14
+    {"foo", "bar"}  // foo = "bar"
+};
+```
+
+This is indistinguishable from a (heterogeneous) TOML array definition.
+
+```toml
+v = [
+    ["answer", 42],
+    ["pi",   3.14],
+    ["foo", "bar"],
+]
+```
+
+This means that the above C++ code makes constructor's overload resolution
+ambiguous. So a constructor that allows both "table as an initializer-list" and
+"heterogeneous array as an initializer-list" cannot be implemented.
+
+Thus, although it is painful, we need to explicitly cast values into
+`toml::value` when you initialize heterogeneous array in a C++ code.
+
+```cpp
+toml::value v{
+    toml::value("foo"), toml::value(3.14), toml::value(42),
+    toml::value{1,2,3,4,5}, toml::value{{"key", "value"}}
+};
+```
+
+## Breaking Changes from v2
+
+Although toml11 is relatively new library (it's three years old now), it had
+some confusing and inconvenient user-interfaces because of historical reasons.
+
+Between v2 and v3, those interfaces are rearranged.
+
+- `toml::parse` now returns a `toml::value`, not `toml::table`.
+- `toml::value` is now an alias of `toml::basic_value<discard_comment, std::vector, std::unordered_map>`.
+  - See [Customizing containers](#customizing-containers) for detail.
+- The elements of `toml::value_t` are renamed as `snake_case`.
+  - See [Underlying types](#underlying-types) for detail.
+- Supports for the CamelCaseNames are dropped.
+  - See [Underlying types](#underlying-types) for detail.
+- `(is|as)_float` has been removed to make the function names consistent with others.
+  - Since `float` is a keyword, toml11 named a float type as `toml::floating`.
+  - Also a `value_t` corresponds to `toml::floating` is named `value_t::floating`.
+  - So `(is|as)_floating` is introduced and `is_float` has been removed.
+  - See [Casting a toml::value](#casting-a-tomlvalue) and [Checking value type](#checking-value-type) for detail.
+- An overload of `toml::find` for `toml::table` has been dropped. Use `toml::value` version instead.
+  - Because type conversion between a table and a value causes ambiguity while overload resolution
+  - Since `toml::parse` now returns a `toml::value`, this feature becomes less important.
+  - Also because `toml::table` is a normal STL container, implementing utility function is easy.
+  - See [Finding a toml::value](#finding-a-toml-value) for detail.
+- An overload of `operator<<` and `toml::format` for `toml::table`s are dropped.
+  - Use `toml::value` instead.
+  - See [Serializing TOML data](#serializing-toml-data) for detail.
+- Interface around comments.
+  - See [Preserving Comments](#preserving-comments) for detail.
+- An ancient `from_toml/into_toml` has been removed. Use arbitrary type conversion support.
+  - See [Conversion between toml value and arbitrary types](#conversion-between-toml-value-and-arbitrary-types) for detail.
+
+Such a big change will not happen in the coming years.
+
+## Running Tests
+
+After cloning this repository, run the following command (thank you @jwillikers
+for automating test set fetching!).
+
+```sh
+$ mkdir build
+$ cd build
+$ cmake .. -Dtoml11_BUILD_TEST=ON
+$ make
+$ make test
+```
+
+To run the language agnostic test suite, you need to compile
+`tests/check_toml_test.cpp` and pass it to the tester.
+
+## Contributors
+
+I appreciate the help of the contributors who introduced the great feature to this library.
+
+- Guillaume Fraux (@Luthaf)
+  - Windows support and CI on Appvayor
+  - Intel Compiler support
+- Quentin Khan (@xaxousis)
+  - Found & Fixed a bug around ODR
+  - Improved error messages for invalid keys to show the location where the parser fails
+- Petr Beneš (@wbenny)
+  - Fixed warnings on MSVC
+- Ivan Shynkarenka (@chronoxor)
+  - Fixed Visual Studio 2019 warnings
+- @khoitd1997
+  - Fixed warnings while type conversion
+- @KerstinKeller
+  - Added installation script to CMake
+- J.C. Moyer (@jcmoyer)
+  - Fixed an example code in the documentation
+- Jt Freeman (@blockparty-sh)
+  - Fixed feature test macro around `localtime_s`
+  - Suppress warnings in Debug mode
+- OGAWA Kenichi (@kenichiice)
+  - Suppress warnings on intel compiler
+- Jordan Williams (@jwillikers)
+  - Fixed clang range-loop-analysis warnings
+  - Fixed feature test macro to suppress -Wundef
+  - Use cache variables in CMakeLists.txt
+  - Automate test set fetching, update and refactor CMakeLists.txt
+- Scott McCaskill
+  - Parse 9 digits (nanoseconds) of fractional seconds in a `local_time`
+- Shu Wang (@halfelf)
+  - fix "Finding a value in an array" example in README
+- @maass-tv and @SeverinLeonhardt
+  - Fix MSVC warning C4866
+- OGAWA KenIchi (@kenichiice)
+  - Fix include path in README
+- Mohammed Alyousef (@MoAlyousef)
+  - Made testing optional in CMake
+- Ivan Shynkarenka (@chronoxor)
+  - Fix compilation error in `<filesystem>` with MinGW
+- Alex Merry (@amerry)
+  - Add missing include files
+- sneakypete81 (@sneakypete81)
+  - Fix typo in error message
+- Oliver Kahrmann (@founderio)
+  - Fix missing filename in error message if parsed file is empty
+- Karl Nilsson (@karl-nilsson)
+  - Fix many spelling errors
+- ohdarling88 (@ohdarling)
+  - Fix a bug in a constructor of serializer
+- estshorter (@estshorter)
+  - Fix MSVC warning C26478
+- Philip Top (@phlptp)
+  - Improve checking standard library feature availability check
+- Louis Marascio (@marascio)
+  - Fix free-nonheap-object warning
+
+
+## Licensing terms
+
+This product is licensed under the terms of the [MIT License](LICENSE).
+
+- Copyright (c) 2017-2021 Toru Niina
+
+All rights reserved.
diff --git a/src/toml11/toml.hpp b/src/toml11/toml.hpp
new file mode 100644
index 000000000..f34cfccca
--- /dev/null
+++ b/src/toml11/toml.hpp
@@ -0,0 +1,46 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Toru Niina
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef TOML_FOR_MODERN_CPP
+#define TOML_FOR_MODERN_CPP
+
+#ifndef __cplusplus
+#    error "__cplusplus is not defined"
+#endif
+
+#if __cplusplus < 201103L && _MSC_VER < 1900
+#    error "toml11 requires C++11 or later."
+#endif
+
+#define TOML11_VERSION_MAJOR 3
+#define TOML11_VERSION_MINOR 7
+#define TOML11_VERSION_PATCH 0
+
+#include "toml/parser.hpp"
+#include "toml/literal.hpp"
+#include "toml/serializer.hpp"
+#include "toml/get.hpp"
+#include "toml/macros.hpp"
+
+#endif// TOML_FOR_MODERN_CPP
diff --git a/src/toml11/toml/color.hpp b/src/toml11/toml/color.hpp
new file mode 100644
index 000000000..4cb572cb0
--- /dev/null
+++ b/src/toml11/toml/color.hpp
@@ -0,0 +1,64 @@
+#ifndef TOML11_COLOR_HPP
+#define TOML11_COLOR_HPP
+#include <cstdint>
+#include <ostream>
+
+#ifdef TOML11_COLORIZE_ERROR_MESSAGE
+#define TOML11_ERROR_MESSAGE_COLORIZED true
+#else
+#define TOML11_ERROR_MESSAGE_COLORIZED false
+#endif
+
+namespace toml
+{
+
+// put ANSI escape sequence to ostream
+namespace color_ansi
+{
+namespace detail
+{
+inline int colorize_index()
+{
+    static const int index = std::ios_base::xalloc();
+    return index;
+}
+} // detail
+
+inline std::ostream& colorize(std::ostream& os)
+{
+    // by default, it is zero.
+    os.iword(detail::colorize_index()) = 1;
+    return os;
+}
+inline std::ostream& nocolorize(std::ostream& os)
+{
+    os.iword(detail::colorize_index()) = 0;
+    return os;
+}
+inline std::ostream& reset  (std::ostream& os)
+{if(os.iword(detail::colorize_index()) == 1) {os << "\033[00m";} return os;}
+inline std::ostream& bold   (std::ostream& os)
+{if(os.iword(detail::colorize_index()) == 1) {os << "\033[01m";} return os;}
+inline std::ostream& grey   (std::ostream& os)
+{if(os.iword(detail::colorize_index()) == 1) {os << "\033[30m";} return os;}
+inline std::ostream& red    (std::ostream& os)
+{if(os.iword(detail::colorize_index()) == 1) {os << "\033[31m";} return os;}
+inline std::ostream& green  (std::ostream& os)
+{if(os.iword(detail::colorize_index()) == 1) {os << "\033[32m";} return os;}
+inline std::ostream& yellow (std::ostream& os)
+{if(os.iword(detail::colorize_index()) == 1) {os << "\033[33m";} return os;}
+inline std::ostream& blue   (std::ostream& os)
+{if(os.iword(detail::colorize_index()) == 1) {os << "\033[34m";} return os;}
+inline std::ostream& magenta(std::ostream& os)
+{if(os.iword(detail::colorize_index()) == 1) {os << "\033[35m";} return os;}
+inline std::ostream& cyan   (std::ostream& os)
+{if(os.iword(detail::colorize_index()) == 1) {os << "\033[36m";} return os;}
+inline std::ostream& white  (std::ostream& os)
+{if(os.iword(detail::colorize_index()) == 1) {os << "\033[37m";} return os;}
+} // color_ansi
+
+// ANSI escape sequence is the only and default colorization method currently
+namespace color = color_ansi;
+
+} // toml
+#endif// TOML11_COLOR_HPP
diff --git a/src/toml11/toml/combinator.hpp b/src/toml11/toml/combinator.hpp
new file mode 100644
index 000000000..33ecca1eb
--- /dev/null
+++ b/src/toml11/toml/combinator.hpp
@@ -0,0 +1,306 @@
+//     Copyright Toru Niina 2017.
+// Distributed under the MIT License.
+#ifndef TOML11_COMBINATOR_HPP
+#define TOML11_COMBINATOR_HPP
+#include <cassert>
+#include <cctype>
+#include <cstdio>
+
+#include <array>
+#include <iomanip>
+#include <iterator>
+#include <limits>
+#include <type_traits>
+
+#include "region.hpp"
+#include "result.hpp"
+#include "traits.hpp"
+#include "utility.hpp"
+
+// they scans characters and returns region if it matches to the condition.
+// when they fail, it does not change the location.
+// in lexer.hpp, these are used.
+
+namespace toml
+{
+namespace detail
+{
+
+// to output character as an error message.
+inline std::string show_char(const char c)
+{
+    // It suppresses an error that occurs only in Debug mode of MSVC++ on Windows.
+    // I'm not completely sure but they check the value of char to be in the
+    // range [0, 256) and some of the COMPLETELY VALID utf-8 character sometimes
+    // has negative value (if char has sign). So here it re-interprets c as
+    // unsigned char through pointer. In general, converting pointer to a
+    // pointer that has different type cause UB, but `(signed|unsigned)?char`
+    // are one of the exceptions. Converting pointer only to char and std::byte
+    // (c++17) are valid.
+    if(std::isgraph(*reinterpret_cast<unsigned char const*>(std::addressof(c))))
+    {
+        return std::string(1, c);
+    }
+    else
+    {
+        std::array<char, 5> buf;
+        buf.fill('\0');
+        const auto r = std::snprintf(
+                buf.data(), buf.size(), "0x%02x", static_cast<int>(c) & 0xFF);
+        (void) r; // Unused variable warning
+        assert(r == static_cast<int>(buf.size()) - 1);
+        return std::string(buf.data());
+    }
+}
+
+template<char C>
+struct character
+{
+    static constexpr char target = C;
+
+    static result<region, none_t>
+    invoke(location& loc)
+    {
+        if(loc.iter() == loc.end()) {return none();}
+        const auto first = loc.iter();
+
+        const char c = *(loc.iter());
+        if(c != target)
+        {
+            return none();
+        }
+        loc.advance(); // update location
+
+        return ok(region(loc, first, loc.iter()));
+    }
+};
+template<char C>
+constexpr char character<C>::target;
+
+// closed interval [Low, Up]. both Low and Up are included.
+template<char Low, char Up>
+struct in_range
+{
+    // assuming ascii part of UTF-8...
+    static_assert(Low <= Up, "lower bound should be less than upper bound.");
+
+    static constexpr char upper = Up;
+    static constexpr char lower = Low;
+
+    static result<region, none_t>
+    invoke(location& loc)
+    {
+        if(loc.iter() == loc.end()) {return none();}
+        const auto first = loc.iter();
+
+        const char c = *(loc.iter());
+        if(c < lower || upper < c)
+        {
+            return none();
+        }
+
+        loc.advance();
+        return ok(region(loc, first, loc.iter()));
+    }
+};
+template<char L, char U> constexpr char in_range<L, U>::upper;
+template<char L, char U> constexpr char in_range<L, U>::lower;
+
+// keep iterator if `Combinator` matches. otherwise, increment `iter` by 1 char.
+// for detecting invalid characters, like control sequences in toml string.
+template<typename Combinator>
+struct exclude
+{
+    static result<region, none_t>
+    invoke(location& loc)
+    {
+        if(loc.iter() == loc.end()) {return none();}
+        auto first = loc.iter();
+
+        auto rslt = Combinator::invoke(loc);
+        if(rslt.is_ok())
+        {
+            loc.reset(first);
+            return none();
+        }
+        loc.reset(std::next(first)); // XXX maybe loc.advance() is okay but...
+        return ok(region(loc, first, loc.iter()));
+    }
+};
+
+// increment `iter`, if matches. otherwise, just return empty string.
+template<typename Combinator>
+struct maybe
+{
+    static result<region, none_t>
+    invoke(location& loc)
+    {
+        const auto rslt = Combinator::invoke(loc);
+        if(rslt.is_ok())
+        {
+            return rslt;
+        }
+        return ok(region(loc));
+    }
+};
+
+template<typename ... Ts>
+struct sequence;
+
+template<typename Head, typename ... Tail>
+struct sequence<Head, Tail...>
+{
+    static result<region, none_t>
+    invoke(location& loc)
+    {
+        const auto first = loc.iter();
+        auto rslt = Head::invoke(loc);
+        if(rslt.is_err())
+        {
+            loc.reset(first);
+            return none();
+        }
+        return sequence<Tail...>::invoke(loc, std::move(rslt.unwrap()), first);
+    }
+
+    // called from the above function only, recursively.
+    template<typename Iterator>
+    static result<region, none_t>
+    invoke(location& loc, region reg, Iterator first)
+    {
+        const auto rslt = Head::invoke(loc);
+        if(rslt.is_err())
+        {
+            loc.reset(first);
+            return none();
+        }
+        reg += rslt.unwrap(); // concat regions
+        return sequence<Tail...>::invoke(loc, std::move(reg), first);
+    }
+};
+
+template<typename Head>
+struct sequence<Head>
+{
+    // would be called from sequence<T ...>::invoke only.
+    template<typename Iterator>
+    static result<region, none_t>
+    invoke(location& loc, region reg, Iterator first)
+    {
+        const auto rslt = Head::invoke(loc);
+        if(rslt.is_err())
+        {
+            loc.reset(first);
+            return none();
+        }
+        reg += rslt.unwrap(); // concat regions
+        return ok(reg);
+    }
+};
+
+template<typename ... Ts>
+struct either;
+
+template<typename Head, typename ... Tail>
+struct either<Head, Tail...>
+{
+    static result<region, none_t>
+    invoke(location& loc)
+    {
+        const auto rslt = Head::invoke(loc);
+        if(rslt.is_ok()) {return rslt;}
+        return either<Tail...>::invoke(loc);
+    }
+};
+template<typename Head>
+struct either<Head>
+{
+    static result<region, none_t>
+    invoke(location& loc)
+    {
+        return Head::invoke(loc);
+    }
+};
+
+template<typename T, typename N>
+struct repeat;
+
+template<std::size_t N> struct exactly{};
+template<std::size_t N> struct at_least{};
+struct unlimited{};
+
+template<typename T, std::size_t N>
+struct repeat<T, exactly<N>>
+{
+    static result<region, none_t>
+    invoke(location& loc)
+    {
+        region retval(loc);
+        const auto first = loc.iter();
+        for(std::size_t i=0; i<N; ++i)
+        {
+            auto rslt = T::invoke(loc);
+            if(rslt.is_err())
+            {
+                loc.reset(first);
+                return none();
+            }
+            retval += rslt.unwrap();
+        }
+        return ok(std::move(retval));
+    }
+};
+
+template<typename T, std::size_t N>
+struct repeat<T, at_least<N>>
+{
+    static result<region, none_t>
+    invoke(location& loc)
+    {
+        region retval(loc);
+
+        const auto first = loc.iter();
+        for(std::size_t i=0; i<N; ++i)
+        {
+            auto rslt = T::invoke(loc);
+            if(rslt.is_err())
+            {
+                loc.reset(first);
+                return none();
+            }
+            retval += rslt.unwrap();
+        }
+        while(true)
+        {
+            auto rslt = T::invoke(loc);
+            if(rslt.is_err())
+            {
+                return ok(std::move(retval));
+            }
+            retval += rslt.unwrap();
+        }
+    }
+};
+
+template<typename T>
+struct repeat<T, unlimited>
+{
+    static result<region, none_t>
+    invoke(location& loc)
+    {
+        region retval(loc);
+        while(true)
+        {
+            auto rslt = T::invoke(loc);
+            if(rslt.is_err())
+            {
+                return ok(std::move(retval));
+            }
+            retval += rslt.unwrap();
+        }
+    }
+};
+
+} // detail
+} // toml
+#endif// TOML11_COMBINATOR_HPP
diff --git a/src/toml11/toml/comments.hpp b/src/toml11/toml/comments.hpp
new file mode 100644
index 000000000..ec2504117
--- /dev/null
+++ b/src/toml11/toml/comments.hpp
@@ -0,0 +1,472 @@
+//     Copyright Toru Niina 2019.
+// Distributed under the MIT License.
+#ifndef TOML11_COMMENTS_HPP
+#define TOML11_COMMENTS_HPP
+#include <initializer_list>
+#include <iterator>
+#include <stdexcept>
+#include <string>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+#ifdef TOML11_PRESERVE_COMMENTS_BY_DEFAULT
+#  define TOML11_DEFAULT_COMMENT_STRATEGY ::toml::preserve_comments
+#else
+#  define TOML11_DEFAULT_COMMENT_STRATEGY ::toml::discard_comments
+#endif
+
+// This file provides mainly two classes, `preserve_comments` and `discard_comments`.
+// Those two are a container that have the same interface as `std::vector<std::string>`
+// but bahaves in the opposite way. `preserve_comments` is just the same as
+// `std::vector<std::string>` and each `std::string` corresponds to a comment line.
+// Conversely, `discard_comments` discards all the strings and ignores everything
+// assigned in it. `discard_comments` is always empty and you will encounter an
+// error whenever you access to the element.
+namespace toml
+{
+struct discard_comments; // forward decl
+
+// use it in the following way
+//
+// const toml::basic_value<toml::preserve_comments> data =
+//     toml::parse<toml::preserve_comments>("example.toml");
+//
+// the interface is almost the same as std::vector<std::string>.
+struct preserve_comments
+{
+    // `container_type` is not provided in discard_comments.
+    // do not use this inner-type in a generic code.
+    using container_type         = std::vector<std::string>;
+
+    using size_type              = container_type::size_type;
+    using difference_type        = container_type::difference_type;
+    using value_type             = container_type::value_type;
+    using reference              = container_type::reference;
+    using const_reference        = container_type::const_reference;
+    using pointer                = container_type::pointer;
+    using const_pointer          = container_type::const_pointer;
+    using iterator               = container_type::iterator;
+    using const_iterator         = container_type::const_iterator;
+    using reverse_iterator       = container_type::reverse_iterator;
+    using const_reverse_iterator = container_type::const_reverse_iterator;
+
+    preserve_comments()  = default;
+    ~preserve_comments() = default;
+    preserve_comments(preserve_comments const&) = default;
+    preserve_comments(preserve_comments &&)     = default;
+    preserve_comments& operator=(preserve_comments const&) = default;
+    preserve_comments& operator=(preserve_comments &&)     = default;
+
+    explicit preserve_comments(const std::vector<std::string>& c): comments(c){}
+    explicit preserve_comments(std::vector<std::string>&& c)
+        : comments(std::move(c))
+    {}
+    preserve_comments& operator=(const std::vector<std::string>& c)
+    {
+        comments = c;
+        return *this;
+    }
+    preserve_comments& operator=(std::vector<std::string>&& c)
+    {
+        comments = std::move(c);
+        return *this;
+    }
+
+    explicit preserve_comments(const discard_comments&) {}
+
+    explicit preserve_comments(size_type n): comments(n) {}
+    preserve_comments(size_type n, const std::string& x): comments(n, x) {}
+    preserve_comments(std::initializer_list<std::string> x): comments(x) {}
+    template<typename InputIterator>
+    preserve_comments(InputIterator first, InputIterator last)
+        : comments(first, last)
+    {}
+
+    template<typename InputIterator>
+    void assign(InputIterator first, InputIterator last) {comments.assign(first, last);}
+    void assign(std::initializer_list<std::string> ini)  {comments.assign(ini);}
+    void assign(size_type n, const std::string& val)     {comments.assign(n, val);}
+
+    // Related to the issue #97.
+    //
+    // It is known that `std::vector::insert` and `std::vector::erase` in
+    // the standard library implementation included in GCC 4.8.5 takes
+    // `std::vector::iterator` instead of `std::vector::const_iterator`.
+    // Because of the const-correctness, we cannot convert a `const_iterator` to
+    // an `iterator`. It causes compilation error in GCC 4.8.5.
+#if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__) && !defined(__clang__)
+#  if (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) <= 40805
+#    define TOML11_WORKAROUND_GCC_4_8_X_STANDARD_LIBRARY_IMPLEMENTATION
+#  endif
+#endif
+
+#ifdef TOML11_WORKAROUND_GCC_4_8_X_STANDARD_LIBRARY_IMPLEMENTATION
+    iterator insert(iterator p, const std::string& x)
+    {
+        return comments.insert(p, x);
+    }
+    iterator insert(iterator p, std::string&&      x)
+    {
+        return comments.insert(p, std::move(x));
+    }
+    void insert(iterator p, size_type n, const std::string& x)
+    {
+        return comments.insert(p, n, x);
+    }
+    template<typename InputIterator>
+    void insert(iterator p, InputIterator first, InputIterator last)
+    {
+        return comments.insert(p, first, last);
+    }
+    void insert(iterator p, std::initializer_list<std::string> ini)
+    {
+        return comments.insert(p, ini);
+    }
+
+    template<typename ... Ts>
+    iterator emplace(iterator p, Ts&& ... args)
+    {
+        return comments.emplace(p, std::forward<Ts>(args)...);
+    }
+
+    iterator erase(iterator pos) {return comments.erase(pos);}
+    iterator erase(iterator first, iterator last)
+    {
+        return comments.erase(first, last);
+    }
+#else
+    iterator insert(const_iterator p, const std::string& x)
+    {
+        return comments.insert(p, x);
+    }
+    iterator insert(const_iterator p, std::string&&      x)
+    {
+        return comments.insert(p, std::move(x));
+    }
+    iterator insert(const_iterator p, size_type n, const std::string& x)
+    {
+        return comments.insert(p, n, x);
+    }
+    template<typename InputIterator>
+    iterator insert(const_iterator p, InputIterator first, InputIterator last)
+    {
+        return comments.insert(p, first, last);
+    }
+    iterator insert(const_iterator p, std::initializer_list<std::string> ini)
+    {
+        return comments.insert(p, ini);
+    }
+
+    template<typename ... Ts>
+    iterator emplace(const_iterator p, Ts&& ... args)
+    {
+        return comments.emplace(p, std::forward<Ts>(args)...);
+    }
+
+    iterator erase(const_iterator pos) {return comments.erase(pos);}
+    iterator erase(const_iterator first, const_iterator last)
+    {
+        return comments.erase(first, last);
+    }
+#endif
+
+    void swap(preserve_comments& other) {comments.swap(other.comments);}
+
+    void push_back(const std::string& v) {comments.push_back(v);}
+    void push_back(std::string&&      v) {comments.push_back(std::move(v));}
+    void pop_back()                      {comments.pop_back();}
+
+    template<typename ... Ts>
+    void emplace_back(Ts&& ... args) {comments.emplace_back(std::forward<Ts>(args)...);}
+
+    void clear() {comments.clear();}
+
+    size_type size()     const noexcept {return comments.size();}
+    size_type max_size() const noexcept {return comments.max_size();}
+    size_type capacity() const noexcept {return comments.capacity();}
+    bool      empty()    const noexcept {return comments.empty();}
+
+    void reserve(size_type n)                      {comments.reserve(n);}
+    void resize(size_type n)                       {comments.resize(n);}
+    void resize(size_type n, const std::string& c) {comments.resize(n, c);}
+    void shrink_to_fit()                           {comments.shrink_to_fit();}
+
+    reference       operator[](const size_type n)       noexcept {return comments[n];}
+    const_reference operator[](const size_type n) const noexcept {return comments[n];}
+    reference       at(const size_type n)       {return comments.at(n);}
+    const_reference at(const size_type n) const {return comments.at(n);}
+    reference       front()       noexcept {return comments.front();}
+    const_reference front() const noexcept {return comments.front();}
+    reference       back()        noexcept {return comments.back();}
+    const_reference back()  const noexcept {return comments.back();}
+
+    pointer         data()        noexcept {return comments.data();}
+    const_pointer   data()  const noexcept {return comments.data();}
+
+    iterator       begin()        noexcept {return comments.begin();}
+    iterator       end()          noexcept {return comments.end();}
+    const_iterator begin()  const noexcept {return comments.begin();}
+    const_iterator end()    const noexcept {return comments.end();}
+    const_iterator cbegin() const noexcept {return comments.cbegin();}
+    const_iterator cend()   const noexcept {return comments.cend();}
+
+    reverse_iterator       rbegin()        noexcept {return comments.rbegin();}
+    reverse_iterator       rend()          noexcept {return comments.rend();}
+    const_reverse_iterator rbegin()  const noexcept {return comments.rbegin();}
+    const_reverse_iterator rend()    const noexcept {return comments.rend();}
+    const_reverse_iterator crbegin() const noexcept {return comments.crbegin();}
+    const_reverse_iterator crend()   const noexcept {return comments.crend();}
+
+    friend bool operator==(const preserve_comments&, const preserve_comments&);
+    friend bool operator!=(const preserve_comments&, const preserve_comments&);
+    friend bool operator< (const preserve_comments&, const preserve_comments&);
+    friend bool operator<=(const preserve_comments&, const preserve_comments&);
+    friend bool operator> (const preserve_comments&, const preserve_comments&);
+    friend bool operator>=(const preserve_comments&, const preserve_comments&);
+
+    friend void swap(preserve_comments&, std::vector<std::string>&);
+    friend void swap(std::vector<std::string>&, preserve_comments&);
+
+  private:
+
+    container_type comments;
+};
+
+inline bool operator==(const preserve_comments& lhs, const preserve_comments& rhs) {return lhs.comments == rhs.comments;}
+inline bool operator!=(const preserve_comments& lhs, const preserve_comments& rhs) {return lhs.comments != rhs.comments;}
+inline bool operator< (const preserve_comments& lhs, const preserve_comments& rhs) {return lhs.comments <  rhs.comments;}
+inline bool operator<=(const preserve_comments& lhs, const preserve_comments& rhs) {return lhs.comments <= rhs.comments;}
+inline bool operator> (const preserve_comments& lhs, const preserve_comments& rhs) {return lhs.comments >  rhs.comments;}
+inline bool operator>=(const preserve_comments& lhs, const preserve_comments& rhs) {return lhs.comments >= rhs.comments;}
+
+inline void swap(preserve_comments& lhs, preserve_comments& rhs)
+{
+    lhs.swap(rhs);
+    return;
+}
+inline void swap(preserve_comments& lhs, std::vector<std::string>& rhs)
+{
+    lhs.comments.swap(rhs);
+    return;
+}
+inline void swap(std::vector<std::string>& lhs, preserve_comments& rhs)
+{
+    lhs.swap(rhs.comments);
+    return;
+}
+
+template<typename charT, typename traits>
+std::basic_ostream<charT, traits>&
+operator<<(std::basic_ostream<charT, traits>& os, const preserve_comments& com)
+{
+    for(const auto& c : com)
+    {
+        os << '#' << c << '\n';
+    }
+    return os;
+}
+
+namespace detail
+{
+
+// To provide the same interface with `preserve_comments`, `discard_comments`
+// should have an iterator. But it does not contain anything, so we need to
+// add an iterator that points nothing.
+//
+// It always points null, so DO NOT unwrap this iterator. It always crashes
+// your program.
+template<typename T, bool is_const>
+struct empty_iterator
+{
+    using value_type        = T;
+    using reference_type    = typename std::conditional<is_const, T const&, T&>::type;
+    using pointer_type      = typename std::conditional<is_const, T const*, T*>::type;
+    using difference_type   = std::ptrdiff_t;
+    using iterator_category = std::random_access_iterator_tag;
+
+    empty_iterator()  = default;
+    ~empty_iterator() = default;
+    empty_iterator(empty_iterator const&) = default;
+    empty_iterator(empty_iterator &&)     = default;
+    empty_iterator& operator=(empty_iterator const&) = default;
+    empty_iterator& operator=(empty_iterator &&)     = default;
+
+    // DO NOT call these operators.
+    reference_type operator*()  const noexcept {std::terminate();}
+    pointer_type   operator->() const noexcept {return nullptr;}
+    reference_type operator[](difference_type) const noexcept {return this->operator*();}
+
+    // These operators do nothing.
+    empty_iterator& operator++()    noexcept {return *this;}
+    empty_iterator  operator++(int) noexcept {return *this;}
+    empty_iterator& operator--()    noexcept {return *this;}
+    empty_iterator  operator--(int) noexcept {return *this;}
+
+    empty_iterator& operator+=(difference_type) noexcept {return *this;}
+    empty_iterator& operator-=(difference_type) noexcept {return *this;}
+
+    empty_iterator  operator+(difference_type) const noexcept {return *this;}
+    empty_iterator  operator-(difference_type) const noexcept {return *this;}
+};
+
+template<typename T, bool C>
+bool operator==(const empty_iterator<T, C>&, const empty_iterator<T, C>&) noexcept {return true;}
+template<typename T, bool C>
+bool operator!=(const empty_iterator<T, C>&, const empty_iterator<T, C>&) noexcept {return false;}
+template<typename T, bool C>
+bool operator< (const empty_iterator<T, C>&, const empty_iterator<T, C>&) noexcept {return false;}
+template<typename T, bool C>
+bool operator<=(const empty_iterator<T, C>&, const empty_iterator<T, C>&) noexcept {return true;}
+template<typename T, bool C>
+bool operator> (const empty_iterator<T, C>&, const empty_iterator<T, C>&) noexcept {return false;}
+template<typename T, bool C>
+bool operator>=(const empty_iterator<T, C>&, const empty_iterator<T, C>&) noexcept {return true;}
+
+template<typename T, bool C>
+typename empty_iterator<T, C>::difference_type
+operator-(const empty_iterator<T, C>&, const empty_iterator<T, C>&) noexcept {return 0;}
+
+template<typename T, bool C>
+empty_iterator<T, C>
+operator+(typename empty_iterator<T, C>::difference_type, const empty_iterator<T, C>& rhs) noexcept {return rhs;}
+template<typename T, bool C>
+empty_iterator<T, C>
+operator+(const empty_iterator<T, C>& lhs, typename empty_iterator<T, C>::difference_type) noexcept {return lhs;}
+
+} // detail
+
+// The default comment type. It discards all the comments. It requires only one
+// byte to contain, so the memory footprint is smaller than preserve_comments.
+//
+// It just ignores `push_back`, `insert`, `erase`, and any other modifications.
+// IT always returns size() == 0, the iterator taken by `begin()` is always the
+// same as that of `end()`, and accessing through `operator[]` or iterators
+// always causes a segmentation fault. DO NOT access to the element of this.
+//
+// Why this is chose as the default type is because the last version (2.x.y)
+// does not contain any comments in a value. To minimize the impact on the
+// efficiency, this is chosen as a default.
+//
+// To reduce the memory footprint, later we can try empty base optimization (EBO).
+struct discard_comments
+{
+    using size_type              = std::size_t;
+    using difference_type        = std::ptrdiff_t;
+    using value_type             = std::string;
+    using reference              = std::string&;
+    using const_reference        = std::string const&;
+    using pointer                = std::string*;
+    using const_pointer          = std::string const*;
+    using iterator               = detail::empty_iterator<std::string, false>;
+    using const_iterator         = detail::empty_iterator<std::string, true>;
+    using reverse_iterator       = detail::empty_iterator<std::string, false>;
+    using const_reverse_iterator = detail::empty_iterator<std::string, true>;
+
+    discard_comments() = default;
+    ~discard_comments() = default;
+    discard_comments(discard_comments const&) = default;
+    discard_comments(discard_comments &&)     = default;
+    discard_comments& operator=(discard_comments const&) = default;
+    discard_comments& operator=(discard_comments &&)     = default;
+
+    explicit discard_comments(const std::vector<std::string>&) noexcept {}
+    explicit discard_comments(std::vector<std::string>&&)      noexcept {}
+    discard_comments& operator=(const std::vector<std::string>&) noexcept {return *this;}
+    discard_comments& operator=(std::vector<std::string>&&)      noexcept {return *this;}
+
+    explicit discard_comments(const preserve_comments&)        noexcept {}
+
+    explicit discard_comments(size_type) noexcept {}
+    discard_comments(size_type, const std::string&) noexcept {}
+    discard_comments(std::initializer_list<std::string>) noexcept {}
+    template<typename InputIterator>
+    discard_comments(InputIterator, InputIterator) noexcept {}
+
+    template<typename InputIterator>
+    void assign(InputIterator, InputIterator)       noexcept {}
+    void assign(std::initializer_list<std::string>) noexcept {}
+    void assign(size_type, const std::string&)      noexcept {}
+
+    iterator insert(const_iterator, const std::string&)                 {return iterator{};}
+    iterator insert(const_iterator, std::string&&)                      {return iterator{};}
+    iterator insert(const_iterator, size_type, const std::string&)      {return iterator{};}
+    template<typename InputIterator>
+    iterator insert(const_iterator, InputIterator, InputIterator)       {return iterator{};}
+    iterator insert(const_iterator, std::initializer_list<std::string>) {return iterator{};}
+
+    template<typename ... Ts>
+    iterator emplace(const_iterator, Ts&& ...)     {return iterator{};}
+    iterator erase(const_iterator)                 {return iterator{};}
+    iterator erase(const_iterator, const_iterator) {return iterator{};}
+
+    void swap(discard_comments&) {return;}
+
+    void push_back(const std::string&) {return;}
+    void push_back(std::string&&     ) {return;}
+    void pop_back()                    {return;}
+
+    template<typename ... Ts>
+    void emplace_back(Ts&& ...) {return;}
+
+    void clear() {return;}
+
+    size_type size()     const noexcept {return 0;}
+    size_type max_size() const noexcept {return 0;}
+    size_type capacity() const noexcept {return 0;}
+    bool      empty()    const noexcept {return true;}
+
+    void reserve(size_type)                    {return;}
+    void resize(size_type)                     {return;}
+    void resize(size_type, const std::string&) {return;}
+    void shrink_to_fit()                       {return;}
+
+    // DO NOT access to the element of this container. This container is always
+    // empty, so accessing through operator[], front/back, data causes address
+    // error.
+
+    reference       operator[](const size_type)       noexcept {return *data();}
+    const_reference operator[](const size_type) const noexcept {return *data();}
+    reference       at(const size_type)       {throw std::out_of_range("toml::discard_comment is always empty.");}
+    const_reference at(const size_type) const {throw std::out_of_range("toml::discard_comment is always empty.");}
+    reference       front()       noexcept {return *data();}
+    const_reference front() const noexcept {return *data();}
+    reference       back()        noexcept {return *data();}
+    const_reference back()  const noexcept {return *data();}
+
+    pointer         data()        noexcept {return nullptr;}
+    const_pointer   data()  const noexcept {return nullptr;}
+
+    iterator       begin()        noexcept {return iterator{};}
+    iterator       end()          noexcept {return iterator{};}
+    const_iterator begin()  const noexcept {return const_iterator{};}
+    const_iterator end()    const noexcept {return const_iterator{};}
+    const_iterator cbegin() const noexcept {return const_iterator{};}
+    const_iterator cend()   const noexcept {return const_iterator{};}
+
+    reverse_iterator       rbegin()        noexcept {return iterator{};}
+    reverse_iterator       rend()          noexcept {return iterator{};}
+    const_reverse_iterator rbegin()  const noexcept {return const_iterator{};}
+    const_reverse_iterator rend()    const noexcept {return const_iterator{};}
+    const_reverse_iterator crbegin() const noexcept {return const_iterator{};}
+    const_reverse_iterator crend()   const noexcept {return const_iterator{};}
+};
+
+inline bool operator==(const discard_comments&, const discard_comments&) noexcept {return true;}
+inline bool operator!=(const discard_comments&, const discard_comments&) noexcept {return false;}
+inline bool operator< (const discard_comments&, const discard_comments&) noexcept {return false;}
+inline bool operator<=(const discard_comments&, const discard_comments&) noexcept {return true;}
+inline bool operator> (const discard_comments&, const discard_comments&) noexcept {return false;}
+inline bool operator>=(const discard_comments&, const discard_comments&) noexcept {return true;}
+
+inline void swap(const discard_comments&, const discard_comments&) noexcept {return;}
+
+template<typename charT, typename traits>
+std::basic_ostream<charT, traits>&
+operator<<(std::basic_ostream<charT, traits>& os, const discard_comments&)
+{
+    return os;
+}
+
+} // toml11
+#endif// TOML11_COMMENTS_HPP
diff --git a/src/toml11/toml/datetime.hpp b/src/toml11/toml/datetime.hpp
new file mode 100644
index 000000000..d8127c150
--- /dev/null
+++ b/src/toml11/toml/datetime.hpp
@@ -0,0 +1,631 @@
+//     Copyright Toru Niina 2017.
+// Distributed under the MIT License.
+#ifndef TOML11_DATETIME_HPP
+#define TOML11_DATETIME_HPP
+#include <cstdint>
+#include <cstdlib>
+#include <ctime>
+
+#include <array>
+#include <chrono>
+#include <iomanip>
+#include <ostream>
+#include <tuple>
+
+namespace toml
+{
+
+// To avoid non-threadsafe std::localtime. In C11 (not C++11!), localtime_s is
+// provided in the absolutely same purpose, but C++11 is actually not compatible
+// with C11. We need to dispatch the function depending on the OS.
+namespace detail
+{
+// TODO: find more sophisticated way to handle this
+#if (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 1) || defined(_XOPEN_SOURCE) || defined(_BSD_SOURCE) || defined(_SVID_SOURCE) || defined(_POSIX_SOURCE)
+inline std::tm localtime_s(const std::time_t* src)
+{
+    std::tm dst;
+    const auto result = ::localtime_r(src, &dst);
+    if (!result) { throw std::runtime_error("localtime_r failed."); }
+    return dst;
+}
+inline std::tm gmtime_s(const std::time_t* src)
+{
+    std::tm dst;
+    const auto result = ::gmtime_r(src, &dst);
+    if (!result) { throw std::runtime_error("gmtime_r failed."); }
+    return dst;
+}
+#elif defined(_MSC_VER)
+inline std::tm localtime_s(const std::time_t* src)
+{
+    std::tm dst;
+    const auto result = ::localtime_s(&dst, src);
+    if (result) { throw std::runtime_error("localtime_s failed."); }
+    return dst;
+}
+inline std::tm gmtime_s(const std::time_t* src)
+{
+    std::tm dst;
+    const auto result = ::gmtime_s(&dst, src);
+    if (result) { throw std::runtime_error("gmtime_s failed."); }
+    return dst;
+}
+#else // fallback. not threadsafe
+inline std::tm localtime_s(const std::time_t* src)
+{
+    const auto result = std::localtime(src);
+    if (!result) { throw std::runtime_error("localtime failed."); }
+    return *result;
+}
+inline std::tm gmtime_s(const std::time_t* src)
+{
+    const auto result = std::gmtime(src);
+    if (!result) { throw std::runtime_error("gmtime failed."); }
+    return *result;
+}
+#endif
+} // detail
+
+enum class month_t : std::uint8_t
+{
+    Jan =  0,
+    Feb =  1,
+    Mar =  2,
+    Apr =  3,
+    May =  4,
+    Jun =  5,
+    Jul =  6,
+    Aug =  7,
+    Sep =  8,
+    Oct =  9,
+    Nov = 10,
+    Dec = 11
+};
+
+struct local_date
+{
+    std::int16_t year;   // A.D. (like, 2018)
+    std::uint8_t month;  // [0, 11]
+    std::uint8_t day;    // [1, 31]
+
+    local_date(int y, month_t m, int d)
+        : year (static_cast<std::int16_t>(y)),
+          month(static_cast<std::uint8_t>(m)),
+          day  (static_cast<std::uint8_t>(d))
+    {}
+
+    explicit local_date(const std::tm& t)
+        : year (static_cast<std::int16_t>(t.tm_year + 1900)),
+          month(static_cast<std::uint8_t>(t.tm_mon)),
+          day  (static_cast<std::uint8_t>(t.tm_mday))
+    {}
+
+    explicit local_date(const std::chrono::system_clock::time_point& tp)
+    {
+        const auto t    = std::chrono::system_clock::to_time_t(tp);
+        const auto time = detail::localtime_s(&t);
+        *this = local_date(time);
+    }
+
+    explicit local_date(const std::time_t t)
+        : local_date(std::chrono::system_clock::from_time_t(t))
+    {}
+
+    operator std::chrono::system_clock::time_point() const
+    {
+        // std::mktime returns date as local time zone. no conversion needed
+        std::tm t;
+        t.tm_sec   = 0;
+        t.tm_min   = 0;
+        t.tm_hour  = 0;
+        t.tm_mday  = static_cast<int>(this->day);
+        t.tm_mon   = static_cast<int>(this->month);
+        t.tm_year  = static_cast<int>(this->year) - 1900;
+        t.tm_wday  = 0; // the value will be ignored
+        t.tm_yday  = 0; // the value will be ignored
+        t.tm_isdst = -1;
+        return std::chrono::system_clock::from_time_t(std::mktime(&t));
+    }
+
+    operator std::time_t() const
+    {
+        return std::chrono::system_clock::to_time_t(
+                std::chrono::system_clock::time_point(*this));
+    }
+
+    local_date() = default;
+    ~local_date() = default;
+    local_date(local_date const&) = default;
+    local_date(local_date&&)      = default;
+    local_date& operator=(local_date const&) = default;
+    local_date& operator=(local_date&&)      = default;
+};
+
+inline bool operator==(const local_date& lhs, const local_date& rhs)
+{
+    return std::make_tuple(lhs.year, lhs.month, lhs.day) ==
+           std::make_tuple(rhs.year, rhs.month, rhs.day);
+}
+inline bool operator!=(const local_date& lhs, const local_date& rhs)
+{
+    return !(lhs == rhs);
+}
+inline bool operator< (const local_date& lhs, const local_date& rhs)
+{
+    return std::make_tuple(lhs.year, lhs.month, lhs.day) <
+           std::make_tuple(rhs.year, rhs.month, rhs.day);
+}
+inline bool operator<=(const local_date& lhs, const local_date& rhs)
+{
+    return (lhs < rhs) || (lhs == rhs);
+}
+inline bool operator> (const local_date& lhs, const local_date& rhs)
+{
+    return !(lhs <= rhs);
+}
+inline bool operator>=(const local_date& lhs, const local_date& rhs)
+{
+    return !(lhs < rhs);
+}
+
+template<typename charT, typename traits>
+std::basic_ostream<charT, traits>&
+operator<<(std::basic_ostream<charT, traits>& os, const local_date& date)
+{
+    os << std::setfill('0') << std::setw(4) << static_cast<int>(date.year )     << '-';
+    os << std::setfill('0') << std::setw(2) << static_cast<int>(date.month) + 1 << '-';
+    os << std::setfill('0') << std::setw(2) << static_cast<int>(date.day  )    ;
+    return os;
+}
+
+struct local_time
+{
+    std::uint8_t  hour;        // [0, 23]
+    std::uint8_t  minute;      // [0, 59]
+    std::uint8_t  second;      // [0, 60]
+    std::uint16_t millisecond; // [0, 999]
+    std::uint16_t microsecond; // [0, 999]
+    std::uint16_t nanosecond;  // [0, 999]
+
+    local_time(int h, int m, int s,
+               int ms = 0, int us = 0, int ns = 0)
+        : hour  (static_cast<std::uint8_t>(h)),
+          minute(static_cast<std::uint8_t>(m)),
+          second(static_cast<std::uint8_t>(s)),
+          millisecond(static_cast<std::uint16_t>(ms)),
+          microsecond(static_cast<std::uint16_t>(us)),
+          nanosecond (static_cast<std::uint16_t>(ns))
+    {}
+
+    explicit local_time(const std::tm& t)
+        : hour  (static_cast<std::uint8_t>(t.tm_hour)),
+          minute(static_cast<std::uint8_t>(t.tm_min)),
+          second(static_cast<std::uint8_t>(t.tm_sec)),
+          millisecond(0), microsecond(0), nanosecond(0)
+    {}
+
+    template<typename Rep, typename Period>
+    explicit local_time(const std::chrono::duration<Rep, Period>& t)
+    {
+        const auto h = std::chrono::duration_cast<std::chrono::hours>(t);
+        this->hour = static_cast<std::uint8_t>(h.count());
+        const auto t2 = t - h;
+        const auto m = std::chrono::duration_cast<std::chrono::minutes>(t2);
+        this->minute = static_cast<std::uint8_t>(m.count());
+        const auto t3 = t2 - m;
+        const auto s = std::chrono::duration_cast<std::chrono::seconds>(t3);
+        this->second = static_cast<std::uint8_t>(s.count());
+        const auto t4 = t3 - s;
+        const auto ms = std::chrono::duration_cast<std::chrono::milliseconds>(t4);
+        this->millisecond = static_cast<std::uint16_t>(ms.count());
+        const auto t5 = t4 - ms;
+        const auto us = std::chrono::duration_cast<std::chrono::microseconds>(t5);
+        this->microsecond = static_cast<std::uint16_t>(us.count());
+        const auto t6 = t5 - us;
+        const auto ns = std::chrono::duration_cast<std::chrono::nanoseconds>(t6);
+        this->nanosecond = static_cast<std::uint16_t>(ns.count());
+    }
+
+    operator std::chrono::nanoseconds() const
+    {
+        return std::chrono::nanoseconds (this->nanosecond)  +
+               std::chrono::microseconds(this->microsecond) +
+               std::chrono::milliseconds(this->millisecond) +
+               std::chrono::seconds(this->second) +
+               std::chrono::minutes(this->minute) +
+               std::chrono::hours(this->hour);
+    }
+
+    local_time() = default;
+    ~local_time() = default;
+    local_time(local_time const&) = default;
+    local_time(local_time&&)      = default;
+    local_time& operator=(local_time const&) = default;
+    local_time& operator=(local_time&&)      = default;
+};
+
+inline bool operator==(const local_time& lhs, const local_time& rhs)
+{
+    return std::make_tuple(lhs.hour, lhs.minute, lhs.second, lhs.millisecond, lhs.microsecond, lhs.nanosecond) ==
+           std::make_tuple(rhs.hour, rhs.minute, rhs.second, rhs.millisecond, rhs.microsecond, rhs.nanosecond);
+}
+inline bool operator!=(const local_time& lhs, const local_time& rhs)
+{
+    return !(lhs == rhs);
+}
+inline bool operator< (const local_time& lhs, const local_time& rhs)
+{
+    return std::make_tuple(lhs.hour, lhs.minute, lhs.second, lhs.millisecond, lhs.microsecond, lhs.nanosecond) <
+           std::make_tuple(rhs.hour, rhs.minute, rhs.second, rhs.millisecond, rhs.microsecond, rhs.nanosecond);
+}
+inline bool operator<=(const local_time& lhs, const local_time& rhs)
+{
+    return (lhs < rhs) || (lhs == rhs);
+}
+inline bool operator> (const local_time& lhs, const local_time& rhs)
+{
+    return !(lhs <= rhs);
+}
+inline bool operator>=(const local_time& lhs, const local_time& rhs)
+{
+    return !(lhs < rhs);
+}
+
+template<typename charT, typename traits>
+std::basic_ostream<charT, traits>&
+operator<<(std::basic_ostream<charT, traits>& os, const local_time& time)
+{
+    os << std::setfill('0') << std::setw(2) << static_cast<int>(time.hour  ) << ':';
+    os << std::setfill('0') << std::setw(2) << static_cast<int>(time.minute) << ':';
+    os << std::setfill('0') << std::setw(2) << static_cast<int>(time.second);
+    if(time.millisecond != 0 || time.microsecond != 0 || time.nanosecond != 0)
+    {
+        os << '.';
+        os << std::setfill('0') << std::setw(3) << static_cast<int>(time.millisecond);
+        if(time.microsecond != 0 || time.nanosecond != 0)
+        {
+            os << std::setfill('0') << std::setw(3) << static_cast<int>(time.microsecond);
+            if(time.nanosecond != 0)
+            {
+                os << std::setfill('0') << std::setw(3) << static_cast<int>(time.nanosecond);
+            }
+        }
+    }
+    return os;
+}
+
+struct time_offset
+{
+    std::int8_t hour;   // [-12, 12]
+    std::int8_t minute; // [-59, 59]
+
+    time_offset(int h, int m)
+        : hour  (static_cast<std::int8_t>(h)),
+          minute(static_cast<std::int8_t>(m))
+    {}
+
+    operator std::chrono::minutes() const
+    {
+        return std::chrono::minutes(this->minute) +
+               std::chrono::hours(this->hour);
+    }
+
+    time_offset() = default;
+    ~time_offset() = default;
+    time_offset(time_offset const&) = default;
+    time_offset(time_offset&&)      = default;
+    time_offset& operator=(time_offset const&) = default;
+    time_offset& operator=(time_offset&&)      = default;
+};
+
+inline bool operator==(const time_offset& lhs, const time_offset& rhs)
+{
+    return std::make_tuple(lhs.hour, lhs.minute) ==
+           std::make_tuple(rhs.hour, rhs.minute);
+}
+inline bool operator!=(const time_offset& lhs, const time_offset& rhs)
+{
+    return !(lhs == rhs);
+}
+inline bool operator< (const time_offset& lhs, const time_offset& rhs)
+{
+    return std::make_tuple(lhs.hour, lhs.minute) <
+           std::make_tuple(rhs.hour, rhs.minute);
+}
+inline bool operator<=(const time_offset& lhs, const time_offset& rhs)
+{
+    return (lhs < rhs) || (lhs == rhs);
+}
+inline bool operator> (const time_offset& lhs, const time_offset& rhs)
+{
+    return !(lhs <= rhs);
+}
+inline bool operator>=(const time_offset& lhs, const time_offset& rhs)
+{
+    return !(lhs < rhs);
+}
+
+template<typename charT, typename traits>
+std::basic_ostream<charT, traits>&
+operator<<(std::basic_ostream<charT, traits>& os, const time_offset& offset)
+{
+    if(offset.hour == 0 && offset.minute == 0)
+    {
+        os << 'Z';
+        return os;
+    }
+    int minute = static_cast<int>(offset.hour) * 60 + offset.minute;
+    if(minute < 0){os << '-'; minute = std::abs(minute);} else {os << '+';}
+    os << std::setfill('0') << std::setw(2) << minute / 60 << ':';
+    os << std::setfill('0') << std::setw(2) << minute % 60;
+    return os;
+}
+
+struct local_datetime
+{
+    local_date date;
+    local_time time;
+
+    local_datetime(local_date d, local_time t): date(d), time(t) {}
+
+    explicit local_datetime(const std::tm& t): date(t), time(t){}
+
+    explicit local_datetime(const std::chrono::system_clock::time_point& tp)
+    {
+        const auto t = std::chrono::system_clock::to_time_t(tp);
+        std::tm ltime = detail::localtime_s(&t);
+
+        this->date = local_date(ltime);
+        this->time = local_time(ltime);
+
+        // std::tm lacks subsecond information, so diff between tp and tm
+        // can be used to get millisecond & microsecond information.
+        const auto t_diff = tp -
+            std::chrono::system_clock::from_time_t(std::mktime(&ltime));
+        this->time.millisecond = static_cast<std::uint16_t>(
+          std::chrono::duration_cast<std::chrono::milliseconds>(t_diff).count());
+        this->time.microsecond = static_cast<std::uint16_t>(
+          std::chrono::duration_cast<std::chrono::microseconds>(t_diff).count());
+        this->time.nanosecond = static_cast<std::uint16_t>(
+          std::chrono::duration_cast<std::chrono::nanoseconds >(t_diff).count());
+    }
+
+    explicit local_datetime(const std::time_t t)
+        : local_datetime(std::chrono::system_clock::from_time_t(t))
+    {}
+
+    operator std::chrono::system_clock::time_point() const
+    {
+        using internal_duration =
+            typename std::chrono::system_clock::time_point::duration;
+
+        // Normally DST begins at A.M. 3 or 4. If we re-use conversion operator
+        // of local_date and local_time independently, the conversion fails if
+        // it is the day when DST begins or ends. Since local_date considers the
+        // time is 00:00 A.M. and local_time does not consider DST because it
+        // does not have any date information. We need to consider both date and
+        // time information at the same time to convert it correctly.
+
+        std::tm t;
+        t.tm_sec   = static_cast<int>(this->time.second);
+        t.tm_min   = static_cast<int>(this->time.minute);
+        t.tm_hour  = static_cast<int>(this->time.hour);
+        t.tm_mday  = static_cast<int>(this->date.day);
+        t.tm_mon   = static_cast<int>(this->date.month);
+        t.tm_year  = static_cast<int>(this->date.year) - 1900;
+        t.tm_wday  = 0; // the value will be ignored
+        t.tm_yday  = 0; // the value will be ignored
+        t.tm_isdst = -1;
+
+        // std::mktime returns date as local time zone. no conversion needed
+        auto dt = std::chrono::system_clock::from_time_t(std::mktime(&t));
+        dt += std::chrono::duration_cast<internal_duration>(
+                std::chrono::milliseconds(this->time.millisecond) +
+                std::chrono::microseconds(this->time.microsecond) +
+                std::chrono::nanoseconds (this->time.nanosecond));
+        return dt;
+    }
+
+    operator std::time_t() const
+    {
+        return std::chrono::system_clock::to_time_t(
+                std::chrono::system_clock::time_point(*this));
+    }
+
+    local_datetime() = default;
+    ~local_datetime() = default;
+    local_datetime(local_datetime const&) = default;
+    local_datetime(local_datetime&&)      = default;
+    local_datetime& operator=(local_datetime const&) = default;
+    local_datetime& operator=(local_datetime&&)      = default;
+};
+
+inline bool operator==(const local_datetime& lhs, const local_datetime& rhs)
+{
+    return std::make_tuple(lhs.date, lhs.time) ==
+           std::make_tuple(rhs.date, rhs.time);
+}
+inline bool operator!=(const local_datetime& lhs, const local_datetime& rhs)
+{
+    return !(lhs == rhs);
+}
+inline bool operator< (const local_datetime& lhs, const local_datetime& rhs)
+{
+    return std::make_tuple(lhs.date, lhs.time) <
+           std::make_tuple(rhs.date, rhs.time);
+}
+inline bool operator<=(const local_datetime& lhs, const local_datetime& rhs)
+{
+    return (lhs < rhs) || (lhs == rhs);
+}
+inline bool operator> (const local_datetime& lhs, const local_datetime& rhs)
+{
+    return !(lhs <= rhs);
+}
+inline bool operator>=(const local_datetime& lhs, const local_datetime& rhs)
+{
+    return !(lhs < rhs);
+}
+
+template<typename charT, typename traits>
+std::basic_ostream<charT, traits>&
+operator<<(std::basic_ostream<charT, traits>& os, const local_datetime& dt)
+{
+    os << dt.date << 'T' << dt.time;
+    return os;
+}
+
+struct offset_datetime
+{
+    local_date  date;
+    local_time  time;
+    time_offset offset;
+
+    offset_datetime(local_date d, local_time t, time_offset o)
+        : date(d), time(t), offset(o)
+    {}
+    offset_datetime(const local_datetime& dt, time_offset o)
+        : date(dt.date), time(dt.time), offset(o)
+    {}
+    explicit offset_datetime(const local_datetime& ld)
+        : date(ld.date), time(ld.time), offset(get_local_offset(nullptr))
+          // use the current local timezone offset
+    {}
+    explicit offset_datetime(const std::chrono::system_clock::time_point& tp)
+        : offset(0, 0) // use gmtime
+    {
+        const auto timet = std::chrono::system_clock::to_time_t(tp);
+        const auto tm    = detail::gmtime_s(&timet);
+        this->date = local_date(tm);
+        this->time = local_time(tm);
+    }
+    explicit offset_datetime(const std::time_t& t)
+        : offset(0, 0) // use gmtime
+    {
+        const auto tm    = detail::gmtime_s(&t);
+        this->date = local_date(tm);
+        this->time = local_time(tm);
+    }
+    explicit offset_datetime(const std::tm& t)
+        : offset(0, 0) // assume gmtime
+    {
+        this->date = local_date(t);
+        this->time = local_time(t);
+    }
+
+    operator std::chrono::system_clock::time_point() const
+    {
+        // get date-time
+        using internal_duration =
+            typename std::chrono::system_clock::time_point::duration;
+
+        // first, convert it to local date-time information in the same way as
+        // local_datetime does. later we will use time_t to adjust time offset.
+        std::tm t;
+        t.tm_sec   = static_cast<int>(this->time.second);
+        t.tm_min   = static_cast<int>(this->time.minute);
+        t.tm_hour  = static_cast<int>(this->time.hour);
+        t.tm_mday  = static_cast<int>(this->date.day);
+        t.tm_mon   = static_cast<int>(this->date.month);
+        t.tm_year  = static_cast<int>(this->date.year) - 1900;
+        t.tm_wday  = 0; // the value will be ignored
+        t.tm_yday  = 0; // the value will be ignored
+        t.tm_isdst = -1;
+        const std::time_t tp_loc = std::mktime(std::addressof(t));
+
+        auto tp = std::chrono::system_clock::from_time_t(tp_loc);
+        tp += std::chrono::duration_cast<internal_duration>(
+                std::chrono::milliseconds(this->time.millisecond) +
+                std::chrono::microseconds(this->time.microsecond) +
+                std::chrono::nanoseconds (this->time.nanosecond));
+
+        // Since mktime uses local time zone, it should be corrected.
+        // `12:00:00+09:00` means `03:00:00Z`. So mktime returns `03:00:00Z` if
+        // we are in `+09:00` timezone. To represent `12:00:00Z` there, we need
+        // to add `+09:00` to `03:00:00Z`.
+        //    Here, it uses the time_t converted from date-time info to handle
+        // daylight saving time.
+        const auto ofs = get_local_offset(std::addressof(tp_loc));
+        tp += std::chrono::hours  (ofs.hour);
+        tp += std::chrono::minutes(ofs.minute);
+
+        // We got `12:00:00Z` by correcting local timezone applied by mktime.
+        // Then we will apply the offset. Let's say `12:00:00-08:00` is given.
+        // And now, we have `12:00:00Z`. `12:00:00-08:00` means `20:00:00Z`.
+        // So we need to subtract the offset.
+        tp -= std::chrono::minutes(this->offset);
+        return tp;
+    }
+
+    operator std::time_t() const
+    {
+        return std::chrono::system_clock::to_time_t(
+                std::chrono::system_clock::time_point(*this));
+    }
+
+    offset_datetime() = default;
+    ~offset_datetime() = default;
+    offset_datetime(offset_datetime const&) = default;
+    offset_datetime(offset_datetime&&)      = default;
+    offset_datetime& operator=(offset_datetime const&) = default;
+    offset_datetime& operator=(offset_datetime&&)      = default;
+
+  private:
+
+    static time_offset get_local_offset(const std::time_t* tp)
+    {
+        // get local timezone with the same date-time information as mktime
+        const auto t = detail::localtime_s(tp);
+
+        std::array<char, 6> buf;
+        const auto result = std::strftime(buf.data(), 6, "%z", &t); // +hhmm\0
+        if(result != 5)
+        {
+            throw std::runtime_error("toml::offset_datetime: cannot obtain "
+                                     "timezone information of current env");
+        }
+        const int ofs = std::atoi(buf.data());
+        const int ofs_h = ofs / 100;
+        const int ofs_m = ofs - (ofs_h * 100);
+        return time_offset(ofs_h, ofs_m);
+    }
+};
+
+inline bool operator==(const offset_datetime& lhs, const offset_datetime& rhs)
+{
+    return std::make_tuple(lhs.date, lhs.time, lhs.offset) ==
+           std::make_tuple(rhs.date, rhs.time, rhs.offset);
+}
+inline bool operator!=(const offset_datetime& lhs, const offset_datetime& rhs)
+{
+    return !(lhs == rhs);
+}
+inline bool operator< (const offset_datetime& lhs, const offset_datetime& rhs)
+{
+    return std::make_tuple(lhs.date, lhs.time, lhs.offset) <
+           std::make_tuple(rhs.date, rhs.time, rhs.offset);
+}
+inline bool operator<=(const offset_datetime& lhs, const offset_datetime& rhs)
+{
+    return (lhs < rhs) || (lhs == rhs);
+}
+inline bool operator> (const offset_datetime& lhs, const offset_datetime& rhs)
+{
+    return !(lhs <= rhs);
+}
+inline bool operator>=(const offset_datetime& lhs, const offset_datetime& rhs)
+{
+    return !(lhs < rhs);
+}
+
+template<typename charT, typename traits>
+std::basic_ostream<charT, traits>&
+operator<<(std::basic_ostream<charT, traits>& os, const offset_datetime& dt)
+{
+    os << dt.date << 'T' << dt.time << dt.offset;
+    return os;
+}
+
+}//toml
+#endif// TOML11_DATETIME
diff --git a/src/toml11/toml/exception.hpp b/src/toml11/toml/exception.hpp
new file mode 100644
index 000000000..c64651d0a
--- /dev/null
+++ b/src/toml11/toml/exception.hpp
@@ -0,0 +1,65 @@
+//     Copyright Toru Niina 2017.
+// Distributed under the MIT License.
+#ifndef TOML11_EXCEPTION_HPP
+#define TOML11_EXCEPTION_HPP
+#include <stdexcept>
+#include <string>
+
+#include "source_location.hpp"
+
+namespace toml
+{
+
+struct exception : public std::exception
+{
+  public:
+    explicit exception(const source_location& loc): loc_(loc) {}
+    virtual ~exception() noexcept override = default;
+    virtual const char* what() const noexcept override {return "";}
+    virtual source_location const& location() const noexcept {return loc_;}
+
+  protected:
+    source_location loc_;
+};
+
+struct syntax_error : public toml::exception
+{
+  public:
+    explicit syntax_error(const std::string& what_arg, const source_location& loc)
+        : exception(loc), what_(what_arg)
+    {}
+    virtual ~syntax_error() noexcept override = default;
+    virtual const char* what() const noexcept override {return what_.c_str();}
+
+  protected:
+    std::string what_;
+};
+
+struct type_error : public toml::exception
+{
+  public:
+    explicit type_error(const std::string& what_arg, const source_location& loc)
+        : exception(loc), what_(what_arg)
+    {}
+    virtual ~type_error() noexcept override = default;
+    virtual const char* what() const noexcept override {return what_.c_str();}
+
+  protected:
+    std::string what_;
+};
+
+struct internal_error : public toml::exception
+{
+  public:
+    explicit internal_error(const std::string& what_arg, const source_location& loc)
+        : exception(loc), what_(what_arg)
+    {}
+    virtual ~internal_error() noexcept override = default;
+    virtual const char* what() const noexcept override {return what_.c_str();}
+
+  protected:
+    std::string what_;
+};
+
+} // toml
+#endif // TOML_EXCEPTION
diff --git a/src/toml11/toml/from.hpp b/src/toml11/toml/from.hpp
new file mode 100644
index 000000000..10815caf5
--- /dev/null
+++ b/src/toml11/toml/from.hpp
@@ -0,0 +1,19 @@
+//     Copyright Toru Niina 2019.
+// Distributed under the MIT License.
+#ifndef TOML11_FROM_HPP
+#define TOML11_FROM_HPP
+
+namespace toml
+{
+
+template<typename T>
+struct from;
+// {
+//     static T from_toml(const toml::value& v)
+//     {
+//         // User-defined conversions ...
+//     }
+// };
+
+} // toml
+#endif // TOML11_FROM_HPP
diff --git a/src/toml11/toml/get.hpp b/src/toml11/toml/get.hpp
new file mode 100644
index 000000000..d7fdf553b
--- /dev/null
+++ b/src/toml11/toml/get.hpp
@@ -0,0 +1,1117 @@
+//     Copyright Toru Niina 2017.
+// Distributed under the MIT License.
+#ifndef TOML11_GET_HPP
+#define TOML11_GET_HPP
+#include <algorithm>
+
+#include "from.hpp"
+#include "result.hpp"
+#include "value.hpp"
+
+namespace toml
+{
+
+// ============================================================================
+// exact toml::* type
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::is_exact_toml_type<T, basic_value<C, M, V>>::value, T> &
+get(basic_value<C, M, V>& v)
+{
+    return v.template cast<detail::type_to_enum<T, basic_value<C, M, V>>::value>();
+}
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::is_exact_toml_type<T, basic_value<C, M, V>>::value, T> const&
+get(const basic_value<C, M, V>& v)
+{
+    return v.template cast<detail::type_to_enum<T, basic_value<C, M, V>>::value>();
+}
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::is_exact_toml_type<T, basic_value<C, M, V>>::value, T>
+get(basic_value<C, M, V>&& v)
+{
+    return T(std::move(v).template cast<detail::type_to_enum<T, basic_value<C, M, V>>::value>());
+}
+
+// ============================================================================
+// T == toml::value; identity transformation.
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+inline detail::enable_if_t<std::is_same<T, basic_value<C, M, V>>::value, T>&
+get(basic_value<C, M, V>& v)
+{
+    return v;
+}
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+inline detail::enable_if_t<std::is_same<T, basic_value<C, M, V>>::value, T> const&
+get(const basic_value<C, M, V>& v)
+{
+    return v;
+}
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+inline detail::enable_if_t<std::is_same<T, basic_value<C, M, V>>::value, T>
+get(basic_value<C, M, V>&& v)
+{
+    return basic_value<C, M, V>(std::move(v));
+}
+
+// ============================================================================
+// T == toml::basic_value<C2, M2, V2>; basic_value -> basic_value
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+inline detail::enable_if_t<detail::conjunction<detail::is_basic_value<T>,
+    detail::negation<std::is_same<T, basic_value<C, M, V>>>
+    >::value, T>
+get(const basic_value<C, M, V>& v)
+{
+    return T(v);
+}
+
+// ============================================================================
+// integer convertible from toml::Integer
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+inline detail::enable_if_t<detail::conjunction<
+    std::is_integral<T>,                            // T is integral
+    detail::negation<std::is_same<T, bool>>,        // but not bool
+    detail::negation<                               // but not toml::integer
+        detail::is_exact_toml_type<T, basic_value<C, M, V>>>
+    >::value, T>
+get(const basic_value<C, M, V>& v)
+{
+    return static_cast<T>(v.as_integer());
+}
+
+// ============================================================================
+// floating point convertible from toml::Float
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+inline detail::enable_if_t<detail::conjunction<
+    std::is_floating_point<T>,                      // T is floating_point
+    detail::negation<                               // but not toml::floating
+        detail::is_exact_toml_type<T, basic_value<C, M, V>>>
+    >::value, T>
+get(const basic_value<C, M, V>& v)
+{
+    return static_cast<T>(v.as_floating());
+}
+
+// ============================================================================
+// std::string; toml uses its own toml::string, but it should be convertible to
+// std::string seamlessly
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+inline detail::enable_if_t<std::is_same<T, std::string>::value, std::string>&
+get(basic_value<C, M, V>& v)
+{
+    return v.as_string().str;
+}
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+inline detail::enable_if_t<std::is_same<T, std::string>::value, std::string> const&
+get(const basic_value<C, M, V>& v)
+{
+    return v.as_string().str;
+}
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+inline detail::enable_if_t<std::is_same<T, std::string>::value, std::string>
+get(basic_value<C, M, V>&& v)
+{
+    return std::string(std::move(v.as_string().str));
+}
+
+// ============================================================================
+// std::string_view
+
+#if defined(TOML11_USING_STRING_VIEW) && TOML11_USING_STRING_VIEW>0
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+inline detail::enable_if_t<std::is_same<T, std::string_view>::value, std::string_view>
+get(const basic_value<C, M, V>& v)
+{
+    return std::string_view(v.as_string().str);
+}
+#endif
+
+// ============================================================================
+// std::chrono::duration from toml::local_time.
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+inline detail::enable_if_t<detail::is_chrono_duration<T>::value, T>
+get(const basic_value<C, M, V>& v)
+{
+    return std::chrono::duration_cast<T>(
+            std::chrono::nanoseconds(v.as_local_time()));
+}
+
+// ============================================================================
+// std::chrono::system_clock::time_point from toml::datetime variants
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+inline detail::enable_if_t<
+    std::is_same<std::chrono::system_clock::time_point, T>::value, T>
+get(const basic_value<C, M, V>& v)
+{
+    switch(v.type())
+    {
+        case value_t::local_date:
+        {
+            return std::chrono::system_clock::time_point(v.as_local_date());
+        }
+        case value_t::local_datetime:
+        {
+            return std::chrono::system_clock::time_point(v.as_local_datetime());
+        }
+        case value_t::offset_datetime:
+        {
+            return std::chrono::system_clock::time_point(v.as_offset_datetime());
+        }
+        default:
+        {
+            throw type_error(detail::format_underline("toml::value: "
+                "bad_cast to std::chrono::system_clock::time_point", {
+                    {v.location(), concat_to_string("the actual type is ", v.type())}
+                }), v.location());
+        }
+    }
+}
+
+// ============================================================================
+// forward declaration to use this recursively. ignore this and go ahead.
+
+// array-like type with push_back(value) method
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::conjunction<
+    detail::is_container<T>,         // T is a container
+    detail::has_push_back_method<T>, // T::push_back(value) works
+    detail::negation<                // but not toml::array
+        detail::is_exact_toml_type<T, basic_value<C, M, V>>>
+    >::value, T>
+get(const basic_value<C, M, V>&);
+
+// array-like type without push_back(value) method
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::conjunction<
+    detail::is_container<T>,                           // T is a container
+    detail::negation<detail::has_push_back_method<T>>, // w/o push_back(...)
+    detail::negation<                                  // not toml::array
+        detail::is_exact_toml_type<T, basic_value<C, M, V>>>
+    >::value, T>
+get(const basic_value<C, M, V>&);
+
+// std::pair<T1, T2>
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::is_std_pair<T>::value, T>
+get(const basic_value<C, M, V>&);
+
+// std::tuple<T1, T2, ...>
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::is_std_tuple<T>::value, T>
+get(const basic_value<C, M, V>&);
+
+// map-like classes
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::conjunction<
+    detail::is_map<T>, // T is map
+    detail::negation<  // but not toml::table
+        detail::is_exact_toml_type<T, basic_value<C, M, V>>>
+    >::value, T>
+get(const basic_value<C, M, V>&);
+
+// T.from_toml(v)
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::conjunction<
+    detail::negation<                         // not a toml::* type
+        detail::is_exact_toml_type<T, basic_value<C, M, V>>>,
+    detail::has_from_toml_method<T, C, M, V>, // but has from_toml(toml::value)
+    std::is_default_constructible<T>          // and default constructible
+    >::value, T>
+get(const basic_value<C, M, V>&);
+
+// toml::from<T>::from_toml(v)
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::has_specialized_from<T>::value, T>
+get(const basic_value<C, M, V>&);
+
+// T(const toml::value&) and T is not toml::basic_value,
+// and it does not have `from<T>` nor `from_toml`.
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::conjunction<
+    detail::negation<detail::is_basic_value<T>>,
+    std::is_constructible<T, const basic_value<C, M, V>&>,
+    detail::negation<detail::has_from_toml_method<T, C, M, V>>,
+    detail::negation<detail::has_specialized_from<T>>
+    >::value, T>
+get(const basic_value<C, M, V>&);
+
+// ============================================================================
+// array-like types; most likely STL container, like std::vector, etc.
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::conjunction<
+    detail::is_container<T>,         // T is a container
+    detail::has_push_back_method<T>, // container.push_back(elem) works
+    detail::negation<                // but not toml::array
+        detail::is_exact_toml_type<T, basic_value<C, M, V>>>
+    >::value, T>
+get(const basic_value<C, M, V>& v)
+{
+    using value_type = typename T::value_type;
+    const auto& ary = v.as_array();
+
+    T container;
+    try_reserve(container, ary.size());
+
+    for(const auto& elem : ary)
+    {
+        container.push_back(get<value_type>(elem));
+    }
+    return container;
+}
+
+// ============================================================================
+// std::forward_list does not have push_back, insert, or emplace.
+// It has insert_after, emplace_after, push_front.
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::is_std_forward_list<T>::value, T>
+get(const basic_value<C, M, V>& v)
+{
+    using value_type = typename T::value_type;
+    T container;
+    for(const auto& elem : v.as_array())
+    {
+        container.push_front(get<value_type>(elem));
+    }
+    container.reverse();
+    return container;
+}
+
+// ============================================================================
+// array-like types, without push_back(). most likely [std|boost]::array.
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::conjunction<
+    detail::is_container<T>,                           // T is a container
+    detail::negation<detail::has_push_back_method<T>>, // w/o push_back
+    detail::negation<                                  // T is not toml::array
+        detail::is_exact_toml_type<T, basic_value<C, M, V>>>
+    >::value, T>
+get(const basic_value<C, M, V>& v)
+{
+    using value_type = typename T::value_type;
+    const auto& ar = v.as_array();
+
+    T container;
+    if(ar.size() != container.size())
+    {
+        throw std::out_of_range(detail::format_underline(concat_to_string(
+            "toml::get: specified container size is ", container.size(),
+            " but there are ", ar.size(), " elements in toml array."), {
+                {v.location(), "here"}
+            }));
+    }
+    for(std::size_t i=0; i<ar.size(); ++i)
+    {
+        container[i] = ::toml::get<value_type>(ar[i]);
+    }
+    return container;
+}
+
+// ============================================================================
+// std::pair.
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::is_std_pair<T>::value, T>
+get(const basic_value<C, M, V>& v)
+{
+    using first_type  = typename T::first_type;
+    using second_type = typename T::second_type;
+
+    const auto& ar = v.as_array();
+    if(ar.size() != 2)
+    {
+        throw std::out_of_range(detail::format_underline(concat_to_string(
+            "toml::get: specified std::pair but there are ", ar.size(),
+            " elements in toml array."), {{v.location(), "here"}}));
+    }
+    return std::make_pair(::toml::get<first_type >(ar.at(0)),
+                          ::toml::get<second_type>(ar.at(1)));
+}
+
+// ============================================================================
+// std::tuple.
+
+namespace detail
+{
+template<typename T, typename Array, std::size_t ... I>
+T get_tuple_impl(const Array& a, index_sequence<I...>)
+{
+    return std::make_tuple(
+        ::toml::get<typename std::tuple_element<I, T>::type>(a.at(I))...);
+}
+} // detail
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::is_std_tuple<T>::value, T>
+get(const basic_value<C, M, V>& v)
+{
+    const auto& ar = v.as_array();
+    if(ar.size() != std::tuple_size<T>::value)
+    {
+        throw std::out_of_range(detail::format_underline(concat_to_string(
+            "toml::get: specified std::tuple with ",
+            std::tuple_size<T>::value, " elements, but there are ", ar.size(),
+            " elements in toml array."), {{v.location(), "here"}}));
+    }
+    return detail::get_tuple_impl<T>(ar,
+            detail::make_index_sequence<std::tuple_size<T>::value>{});
+}
+
+// ============================================================================
+// map-like types; most likely STL map, like std::map or std::unordered_map.
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::conjunction<
+    detail::is_map<T>, // T is map
+    detail::negation<  // but not toml::array
+        detail::is_exact_toml_type<T, basic_value<C, M, V>>>
+    >::value, T>
+get(const basic_value<C, M, V>& v)
+{
+    using key_type    = typename T::key_type;
+    using mapped_type = typename T::mapped_type;
+    static_assert(std::is_convertible<std::string, key_type>::value,
+                  "toml::get only supports map type of which key_type is "
+                  "convertible from std::string.");
+    T map;
+    for(const auto& kv : v.as_table())
+    {
+        map.emplace(key_type(kv.first), get<mapped_type>(kv.second));
+    }
+    return map;
+}
+
+// ============================================================================
+// user-defined, but compatible types.
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::conjunction<
+    detail::negation<                         // not a toml::* type
+        detail::is_exact_toml_type<T, basic_value<C, M, V>>>,
+    detail::has_from_toml_method<T, C, M, V>, // but has from_toml(toml::value) memfn
+    std::is_default_constructible<T>          // and default constructible
+    >::value, T>
+get(const basic_value<C, M, V>& v)
+{
+    T ud;
+    ud.from_toml(v);
+    return ud;
+}
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::has_specialized_from<T>::value, T>
+get(const basic_value<C, M, V>& v)
+{
+    return ::toml::from<T>::from_toml(v);
+}
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::conjunction<
+    detail::negation<detail::is_basic_value<T>>,                // T is not a toml::value
+    std::is_constructible<T, const basic_value<C, M, V>&>,      // T is constructible from toml::value
+    detail::negation<detail::has_from_toml_method<T, C, M, V>>, // and T does not have T.from_toml(v);
+    detail::negation<detail::has_specialized_from<T>>           // and T does not have toml::from<T>{};
+    >::value, T>
+get(const basic_value<C, M, V>& v)
+{
+    return T(v);
+}
+
+// ============================================================================
+// find
+
+// ----------------------------------------------------------------------------
+// these overloads do not require to set T. and returns value itself.
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V>
+basic_value<C, M, V> const& find(const basic_value<C, M, V>& v, const key& ky)
+{
+    const auto& tab = v.as_table();
+    if(tab.count(ky) == 0)
+    {
+        detail::throw_key_not_found_error(v, ky);
+    }
+    return tab.at(ky);
+}
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V>
+basic_value<C, M, V>& find(basic_value<C, M, V>& v, const key& ky)
+{
+    auto& tab = v.as_table();
+    if(tab.count(ky) == 0)
+    {
+        detail::throw_key_not_found_error(v, ky);
+    }
+    return tab.at(ky);
+}
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V>
+basic_value<C, M, V> find(basic_value<C, M, V>&& v, const key& ky)
+{
+    typename basic_value<C, M, V>::table_type tab = std::move(v).as_table();
+    if(tab.count(ky) == 0)
+    {
+        detail::throw_key_not_found_error(v, ky);
+    }
+    return basic_value<C, M, V>(std::move(tab.at(ky)));
+}
+
+// ----------------------------------------------------------------------------
+// find(value, idx)
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V>
+basic_value<C, M, V> const&
+find(const basic_value<C, M, V>& v, const std::size_t idx)
+{
+    const auto& ary = v.as_array();
+    if(ary.size() <= idx)
+    {
+        throw std::out_of_range(detail::format_underline(concat_to_string(
+            "index ", idx, " is out of range"), {{v.location(), "in this array"}}));
+    }
+    return ary.at(idx);
+}
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V>
+basic_value<C, M, V>& find(basic_value<C, M, V>& v, const std::size_t idx)
+{
+    auto& ary = v.as_array();
+    if(ary.size() <= idx)
+    {
+        throw std::out_of_range(detail::format_underline(concat_to_string(
+            "index ", idx, " is out of range"), {{v.location(), "in this array"}}));
+    }
+    return ary.at(idx);
+}
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V>
+basic_value<C, M, V> find(basic_value<C, M, V>&& v, const std::size_t idx)
+{
+    auto& ary = v.as_array();
+    if(ary.size() <= idx)
+    {
+        throw std::out_of_range(detail::format_underline(concat_to_string(
+            "index ", idx, " is out of range"), {{v.location(), "in this array"}}));
+    }
+    return basic_value<C, M, V>(std::move(ary.at(idx)));
+}
+
+// ----------------------------------------------------------------------------
+// find<T>(value, key);
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+decltype(::toml::get<T>(std::declval<basic_value<C, M, V> const&>()))
+find(const basic_value<C, M, V>& v, const key& ky)
+{
+    const auto& tab = v.as_table();
+    if(tab.count(ky) == 0)
+    {
+        detail::throw_key_not_found_error(v, ky);
+    }
+    return ::toml::get<T>(tab.at(ky));
+}
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+decltype(::toml::get<T>(std::declval<basic_value<C, M, V>&>()))
+find(basic_value<C, M, V>& v, const key& ky)
+{
+    auto& tab = v.as_table();
+    if(tab.count(ky) == 0)
+    {
+        detail::throw_key_not_found_error(v, ky);
+    }
+    return ::toml::get<T>(tab.at(ky));
+}
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+decltype(::toml::get<T>(std::declval<basic_value<C, M, V>&&>()))
+find(basic_value<C, M, V>&& v, const key& ky)
+{
+    typename basic_value<C, M, V>::table_type tab = std::move(v).as_table();
+    if(tab.count(ky) == 0)
+    {
+        detail::throw_key_not_found_error(v, ky);
+    }
+    return ::toml::get<T>(std::move(tab.at(ky)));
+}
+
+// ----------------------------------------------------------------------------
+// find<T>(value, idx)
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+decltype(::toml::get<T>(std::declval<basic_value<C, M, V> const&>()))
+find(const basic_value<C, M, V>& v, const std::size_t idx)
+{
+    const auto& ary = v.as_array();
+    if(ary.size() <= idx)
+    {
+        throw std::out_of_range(detail::format_underline(concat_to_string(
+            "index ", idx, " is out of range"), {{v.location(), "in this array"}}));
+    }
+    return ::toml::get<T>(ary.at(idx));
+}
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+decltype(::toml::get<T>(std::declval<basic_value<C, M, V>&>()))
+find(basic_value<C, M, V>& v, const std::size_t idx)
+{
+    auto& ary = v.as_array();
+    if(ary.size() <= idx)
+    {
+        throw std::out_of_range(detail::format_underline(concat_to_string(
+            "index ", idx, " is out of range"), {{v.location(), "in this array"}}));
+    }
+    return ::toml::get<T>(ary.at(idx));
+}
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+decltype(::toml::get<T>(std::declval<basic_value<C, M, V>&&>()))
+find(basic_value<C, M, V>&& v, const std::size_t idx)
+{
+    typename basic_value<C, M, V>::array_type ary = std::move(v).as_array();
+    if(ary.size() <= idx)
+    {
+        throw std::out_of_range(detail::format_underline(concat_to_string(
+            "index ", idx, " is out of range"), {{v.location(), "in this array"}}));
+    }
+    return ::toml::get<T>(std::move(ary.at(idx)));
+}
+
+// --------------------------------------------------------------------------
+// toml::find(toml::value, toml::key, Ts&& ... keys)
+
+namespace detail
+{
+// It suppresses warnings by -Wsign-conversion. Let's say we have the following
+// code.
+// ```cpp
+// const auto x = toml::find<std::string>(data, "array", 0);
+// ```
+// Here, the type of literal number `0` is `int`. `int` is a signed integer.
+// `toml::find` takes `std::size_t` as an index. So it causes implicit sign
+// conversion and `-Wsign-conversion` warns about it. Using `0u` instead of `0`
+// suppresses the warning, but it makes user code messy.
+//     To suppress this warning, we need to be aware of type conversion caused
+// by `toml::find(v, key1, key2, ... keys)`. But the thing is that the types of
+// keys can be any combination of {string-like, size_t-like}. Of course we can't
+// write down all the combinations. Thus we need to use some function that
+// recognize the type of argument and cast it into `std::string` or
+// `std::size_t` depending on the context.
+//     `key_cast` does the job. It has 2 overloads. One is invoked when the
+// argument type is an integer and cast the argument into `std::size_t`. The
+// other is invoked when the argument type is not an integer, possibly one of
+// std::string, const char[N] or const char*, and construct std::string from
+// the argument.
+//     `toml::find(v, k1, k2, ... ks)` uses `key_cast` before passing `ks` to
+// `toml::find(v, k)` to suppress -Wsign-conversion.
+
+template<typename T>
+enable_if_t<conjunction<std::is_integral<remove_cvref_t<T>>,
+            negation<std::is_same<remove_cvref_t<T>, bool>>>::value, std::size_t>
+key_cast(T&& v) noexcept
+{
+    return std::size_t(v);
+}
+template<typename T>
+enable_if_t<negation<conjunction<std::is_integral<remove_cvref_t<T>>,
+            negation<std::is_same<remove_cvref_t<T>, bool>>>>::value, std::string>
+key_cast(T&& v) noexcept
+{
+    return std::string(std::forward<T>(v));
+}
+} // detail
+
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V,
+         typename Key1, typename Key2, typename ... Keys>
+const basic_value<C, M, V>&
+find(const basic_value<C, M, V>& v, Key1&& k1, Key2&& k2, Keys&& ... keys)
+{
+    return ::toml::find(::toml::find(v, detail::key_cast(k1)),
+            detail::key_cast(k2), std::forward<Keys>(keys)...);
+}
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V,
+         typename Key1, typename Key2, typename ... Keys>
+basic_value<C, M, V>&
+find(basic_value<C, M, V>& v, Key1&& k1, Key2&& k2, Keys&& ... keys)
+{
+    return ::toml::find(::toml::find(v, detail::key_cast(k1)),
+            detail::key_cast(k2), std::forward<Keys>(keys)...);
+}
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V,
+         typename Key1, typename Key2, typename ... Keys>
+basic_value<C, M, V>
+find(basic_value<C, M, V>&& v, Key1&& k1, Key2&& k2, Keys&& ... keys)
+{
+    return ::toml::find(::toml::find(std::move(v), std::forward<Key1>(k1)),
+            detail::key_cast(k2), std::forward<Keys>(keys)...);
+}
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V,
+         typename Key1, typename Key2, typename ... Keys>
+decltype(::toml::get<T>(std::declval<const basic_value<C, M, V>&>()))
+find(const basic_value<C, M, V>& v, Key1&& k1, Key2&& k2, Keys&& ... keys)
+{
+    return ::toml::find<T>(::toml::find(v, detail::key_cast(k1)),
+            detail::key_cast(k2), std::forward<Keys>(keys)...);
+}
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V,
+         typename Key1, typename Key2, typename ... Keys>
+decltype(::toml::get<T>(std::declval<basic_value<C, M, V>&>()))
+find(basic_value<C, M, V>& v, Key1&& k1, Key2&& k2, Keys&& ... keys)
+{
+    return ::toml::find<T>(::toml::find(v, detail::key_cast(k1)),
+            detail::key_cast(k2), std::forward<Keys>(keys)...);
+}
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V,
+         typename Key1, typename Key2, typename ... Keys>
+decltype(::toml::get<T>(std::declval<basic_value<C, M, V>&&>()))
+find(basic_value<C, M, V>&& v, Key1&& k1, Key2&& k2, Keys&& ... keys)
+{
+    return ::toml::find<T>(::toml::find(std::move(v), detail::key_cast(k1)),
+            detail::key_cast(k2), std::forward<Keys>(keys)...);
+}
+
+// ============================================================================
+// get_or(value, fallback)
+
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V>
+basic_value<C, M, V> const&
+get_or(const basic_value<C, M, V>& v, const basic_value<C, M, V>&)
+{
+    return v;
+}
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V>
+basic_value<C, M, V>&
+get_or(basic_value<C, M, V>& v, basic_value<C, M, V>&)
+{
+    return v;
+}
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V>
+basic_value<C, M, V>
+get_or(basic_value<C, M, V>&& v, basic_value<C, M, V>&&)
+{
+    return v;
+}
+
+// ----------------------------------------------------------------------------
+// specialization for the exact toml types (return type becomes lvalue ref)
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<
+    detail::is_exact_toml_type<T, basic_value<C, M, V>>::value, T> const&
+get_or(const basic_value<C, M, V>& v, const T& opt)
+{
+    try
+    {
+        return get<detail::remove_cvref_t<T>>(v);
+    }
+    catch(...)
+    {
+        return opt;
+    }
+}
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<
+    detail::is_exact_toml_type<T, basic_value<C, M, V>>::value, T>&
+get_or(basic_value<C, M, V>& v, T& opt)
+{
+    try
+    {
+        return get<detail::remove_cvref_t<T>>(v);
+    }
+    catch(...)
+    {
+        return opt;
+    }
+}
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::is_exact_toml_type<detail::remove_cvref_t<T>,
+    basic_value<C, M, V>>::value, detail::remove_cvref_t<T>>
+get_or(basic_value<C, M, V>&& v, T&& opt)
+{
+    try
+    {
+        return get<detail::remove_cvref_t<T>>(std::move(v));
+    }
+    catch(...)
+    {
+        return detail::remove_cvref_t<T>(std::forward<T>(opt));
+    }
+}
+
+// ----------------------------------------------------------------------------
+// specialization for std::string (return type becomes lvalue ref)
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<std::is_same<detail::remove_cvref_t<T>, std::string>::value,
+    std::string> const&
+get_or(const basic_value<C, M, V>& v, const T& opt)
+{
+    try
+    {
+        return v.as_string().str;
+    }
+    catch(...)
+    {
+        return opt;
+    }
+}
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<std::is_same<T, std::string>::value, std::string>&
+get_or(basic_value<C, M, V>& v, T& opt)
+{
+    try
+    {
+        return v.as_string().str;
+    }
+    catch(...)
+    {
+        return opt;
+    }
+}
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<
+    std::is_same<detail::remove_cvref_t<T>, std::string>::value, std::string>
+get_or(basic_value<C, M, V>&& v, T&& opt)
+{
+    try
+    {
+        return std::move(v.as_string().str);
+    }
+    catch(...)
+    {
+        return std::string(std::forward<T>(opt));
+    }
+}
+
+// ----------------------------------------------------------------------------
+// specialization for string literal
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::is_string_literal<
+    typename std::remove_reference<T>::type>::value, std::string>
+get_or(const basic_value<C, M, V>& v, T&& opt)
+{
+    try
+    {
+        return std::move(v.as_string().str);
+    }
+    catch(...)
+    {
+        return std::string(std::forward<T>(opt));
+    }
+}
+
+// ----------------------------------------------------------------------------
+// others (require type conversion and return type cannot be lvalue reference)
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::conjunction<
+    detail::negation<detail::is_exact_toml_type<detail::remove_cvref_t<T>,
+        basic_value<C, M, V>>>,
+    detail::negation<std::is_same<std::string, detail::remove_cvref_t<T>>>,
+    detail::negation<detail::is_string_literal<
+        typename std::remove_reference<T>::type>>
+    >::value, detail::remove_cvref_t<T>>
+get_or(const basic_value<C, M, V>& v, T&& opt)
+{
+    try
+    {
+        return get<detail::remove_cvref_t<T>>(v);
+    }
+    catch(...)
+    {
+        return detail::remove_cvref_t<T>(std::forward<T>(opt));
+    }
+}
+
+// ===========================================================================
+// find_or(value, key, fallback)
+
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V>
+basic_value<C, M, V> const&
+find_or(const basic_value<C, M, V>& v, const key& ky,
+        const basic_value<C, M, V>& opt)
+{
+    if(!v.is_table()) {return opt;}
+    const auto& tab = v.as_table();
+    if(tab.count(ky) == 0) {return opt;}
+    return tab.at(ky);
+}
+
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V>
+basic_value<C, M, V>&
+find_or(basic_value<C, M, V>& v, const toml::key& ky, basic_value<C, M, V>& opt)
+{
+    if(!v.is_table()) {return opt;}
+    auto& tab = v.as_table();
+    if(tab.count(ky) == 0) {return opt;}
+    return tab.at(ky);
+}
+
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V>
+basic_value<C, M, V>
+find_or(basic_value<C, M, V>&& v, const toml::key& ky, basic_value<C, M, V>&& opt)
+{
+    if(!v.is_table()) {return opt;}
+    auto tab = std::move(v).as_table();
+    if(tab.count(ky) == 0) {return opt;}
+    return basic_value<C, M, V>(std::move(tab.at(ky)));
+}
+
+// ---------------------------------------------------------------------------
+// exact types (return type can be a reference)
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<
+    detail::is_exact_toml_type<T, basic_value<C, M, V>>::value, T> const&
+find_or(const basic_value<C, M, V>& v, const key& ky, const T& opt)
+{
+    if(!v.is_table()) {return opt;}
+    const auto& tab = v.as_table();
+    if(tab.count(ky) == 0) {return opt;}
+    return get_or(tab.at(ky), opt);
+}
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<
+    detail::is_exact_toml_type<T, basic_value<C, M, V>>::value, T>&
+find_or(basic_value<C, M, V>& v, const toml::key& ky, T& opt)
+{
+    if(!v.is_table()) {return opt;}
+    auto& tab = v.as_table();
+    if(tab.count(ky) == 0) {return opt;}
+    return get_or(tab.at(ky), opt);
+}
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<
+    detail::is_exact_toml_type<T, basic_value<C, M, V>>::value,
+    detail::remove_cvref_t<T>>
+find_or(basic_value<C, M, V>&& v, const toml::key& ky, T&& opt)
+{
+    if(!v.is_table()) {return std::forward<T>(opt);}
+    auto tab = std::move(v).as_table();
+    if(tab.count(ky) == 0) {return std::forward<T>(opt);}
+    return get_or(std::move(tab.at(ky)), std::forward<T>(opt));
+}
+
+// ---------------------------------------------------------------------------
+// std::string (return type can be a reference)
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<std::is_same<T, std::string>::value, std::string> const&
+find_or(const basic_value<C, M, V>& v, const key& ky, const T& opt)
+{
+    if(!v.is_table()) {return opt;}
+    const auto& tab = v.as_table();
+    if(tab.count(ky) == 0) {return opt;}
+    return get_or(tab.at(ky), opt);
+}
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<std::is_same<T, std::string>::value, std::string>&
+find_or(basic_value<C, M, V>& v, const toml::key& ky, T& opt)
+{
+    if(!v.is_table()) {return opt;}
+    auto& tab = v.as_table();
+    if(tab.count(ky) == 0) {return opt;}
+    return get_or(tab.at(ky), opt);
+}
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<std::is_same<T, std::string>::value, std::string>
+find_or(basic_value<C, M, V>&& v, const toml::key& ky, T&& opt)
+{
+    if(!v.is_table()) {return std::forward<T>(opt);}
+    auto tab = std::move(v).as_table();
+    if(tab.count(ky) == 0) {return std::forward<T>(opt);}
+    return get_or(std::move(tab.at(ky)), std::forward<T>(opt));
+}
+
+// ---------------------------------------------------------------------------
+// string literal (deduced as std::string)
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<
+    detail::is_string_literal<typename std::remove_reference<T>::type>::value,
+    std::string>
+find_or(const basic_value<C, M, V>& v, const toml::key& ky, T&& opt)
+{
+    if(!v.is_table()) {return std::string(opt);}
+    const auto& tab = v.as_table();
+    if(tab.count(ky) == 0) {return std::string(opt);}
+    return get_or(tab.at(ky), std::forward<T>(opt));
+}
+
+// ---------------------------------------------------------------------------
+// others (require type conversion and return type cannot be lvalue reference)
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::conjunction<
+    // T is not an exact toml type
+    detail::negation<detail::is_exact_toml_type<
+        detail::remove_cvref_t<T>, basic_value<C, M, V>>>,
+    // T is not std::string
+    detail::negation<std::is_same<std::string, detail::remove_cvref_t<T>>>,
+    // T is not a string literal
+    detail::negation<detail::is_string_literal<
+        typename std::remove_reference<T>::type>>
+    >::value, detail::remove_cvref_t<T>>
+find_or(const basic_value<C, M, V>& v, const toml::key& ky, T&& opt)
+{
+    if(!v.is_table()) {return std::forward<T>(opt);}
+    const auto& tab = v.as_table();
+    if(tab.count(ky) == 0) {return std::forward<T>(opt);}
+    return get_or(tab.at(ky), std::forward<T>(opt));
+}
+
+// ---------------------------------------------------------------------------
+// recursive find-or with type deduction (find_or(value, keys, opt))
+
+template<typename Value, typename ... Ks,
+         typename detail::enable_if_t<(sizeof...(Ks) > 1), std::nullptr_t> = nullptr>
+         // here we need to add SFINAE in the template parameter to avoid
+         // infinite recursion in type deduction on gcc
+auto find_or(Value&& v, const toml::key& ky, Ks&& ... keys)
+    -> decltype(find_or(std::forward<Value>(v), ky, detail::last_one(std::forward<Ks>(keys)...)))
+{
+    if(!v.is_table())
+    {
+        return detail::last_one(std::forward<Ks>(keys)...);
+    }
+    auto&& tab = std::forward<Value>(v).as_table();
+    if(tab.count(ky) == 0)
+    {
+        return detail::last_one(std::forward<Ks>(keys)...);
+    }
+    return find_or(std::forward<decltype(tab)>(tab).at(ky), std::forward<Ks>(keys)...);
+}
+
+// ---------------------------------------------------------------------------
+// recursive find_or with explicit type specialization, find_or<int>(value, keys...)
+
+template<typename T, typename Value, typename ... Ks,
+         typename detail::enable_if_t<(sizeof...(Ks) > 1), std::nullptr_t> = nullptr>
+         // here we need to add SFINAE in the template parameter to avoid
+         // infinite recursion in type deduction on gcc
+auto find_or(Value&& v, const toml::key& ky, Ks&& ... keys)
+    -> decltype(find_or<T>(std::forward<Value>(v), ky, detail::last_one(std::forward<Ks>(keys)...)))
+{
+    if(!v.is_table())
+    {
+        return detail::last_one(std::forward<Ks>(keys)...);
+    }
+    auto&& tab = std::forward<Value>(v).as_table();
+    if(tab.count(ky) == 0)
+    {
+        return detail::last_one(std::forward<Ks>(keys)...);
+    }
+    return find_or(std::forward<decltype(tab)>(tab).at(ky), std::forward<Ks>(keys)...);
+}
+
+// ============================================================================
+// expect
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+result<T, std::string> expect(const basic_value<C, M, V>& v) noexcept
+{
+    try
+    {
+        return ok(get<T>(v));
+    }
+    catch(const std::exception& e)
+    {
+        return err(e.what());
+    }
+}
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+result<T, std::string>
+expect(const basic_value<C, M, V>& v, const toml::key& k) noexcept
+{
+    try
+    {
+        return ok(find<T>(v, k));
+    }
+    catch(const std::exception& e)
+    {
+        return err(e.what());
+    }
+}
+
+} // toml
+#endif// TOML11_GET
diff --git a/src/toml11/toml/into.hpp b/src/toml11/toml/into.hpp
new file mode 100644
index 000000000..74495560e
--- /dev/null
+++ b/src/toml11/toml/into.hpp
@@ -0,0 +1,19 @@
+//     Copyright Toru Niina 2019.
+// Distributed under the MIT License.
+#ifndef TOML11_INTO_HPP
+#define TOML11_INTO_HPP
+
+namespace toml
+{
+
+template<typename T>
+struct into;
+// {
+//     static toml::value into_toml(const T& user_defined_type)
+//     {
+//         // User-defined conversions ...
+//     }
+// };
+
+} // toml
+#endif // TOML11_INTO_HPP
diff --git a/src/toml11/toml/lexer.hpp b/src/toml11/toml/lexer.hpp
new file mode 100644
index 000000000..ea5050b8d
--- /dev/null
+++ b/src/toml11/toml/lexer.hpp
@@ -0,0 +1,293 @@
+//     Copyright Toru Niina 2017.
+// Distributed under the MIT License.
+#ifndef TOML11_LEXER_HPP
+#define TOML11_LEXER_HPP
+#include <istream>
+#include <sstream>
+#include <stdexcept>
+#include <fstream>
+
+#include "combinator.hpp"
+
+namespace toml
+{
+namespace detail
+{
+
+// these scans contents from current location in a container of char
+// and extract a region that matches their own pattern.
+// to see the implementation of each component, see combinator.hpp.
+
+using lex_wschar  = either<character<' '>, character<'\t'>>;
+using lex_ws      = repeat<lex_wschar, at_least<1>>;
+using lex_newline = either<character<'\n'>,
+                           sequence<character<'\r'>, character<'\n'>>>;
+using lex_lower   = in_range<'a', 'z'>;
+using lex_upper   = in_range<'A', 'Z'>;
+using lex_alpha   = either<lex_lower, lex_upper>;
+using lex_digit   = in_range<'0', '9'>;
+using lex_nonzero = in_range<'1', '9'>;
+using lex_oct_dig = in_range<'0', '7'>;
+using lex_bin_dig = in_range<'0', '1'>;
+using lex_hex_dig = either<lex_digit, in_range<'A', 'F'>, in_range<'a', 'f'>>;
+
+using lex_hex_prefix = sequence<character<'0'>, character<'x'>>;
+using lex_oct_prefix = sequence<character<'0'>, character<'o'>>;
+using lex_bin_prefix = sequence<character<'0'>, character<'b'>>;
+using lex_underscore = character<'_'>;
+using lex_plus       = character<'+'>;
+using lex_minus      = character<'-'>;
+using lex_sign       = either<lex_plus, lex_minus>;
+
+// digit | nonzero 1*(digit | _ digit)
+using lex_unsigned_dec_int = either<sequence<lex_nonzero, repeat<
+    either<lex_digit, sequence<lex_underscore, lex_digit>>, at_least<1>>>,
+    lex_digit>;
+// (+|-)? unsigned_dec_int
+using lex_dec_int = sequence<maybe<lex_sign>, lex_unsigned_dec_int>;
+
+// hex_prefix hex_dig *(hex_dig | _ hex_dig)
+using lex_hex_int = sequence<lex_hex_prefix, sequence<lex_hex_dig, repeat<
+    either<lex_hex_dig, sequence<lex_underscore, lex_hex_dig>>, unlimited>>>;
+// oct_prefix oct_dig *(oct_dig | _ oct_dig)
+using lex_oct_int = sequence<lex_oct_prefix, sequence<lex_oct_dig, repeat<
+    either<lex_oct_dig, sequence<lex_underscore, lex_oct_dig>>, unlimited>>>;
+// bin_prefix bin_dig *(bin_dig | _ bin_dig)
+using lex_bin_int = sequence<lex_bin_prefix, sequence<lex_bin_dig, repeat<
+    either<lex_bin_dig, sequence<lex_underscore, lex_bin_dig>>, unlimited>>>;
+
+// (dec_int | hex_int | oct_int | bin_int)
+using lex_integer = either<lex_bin_int, lex_oct_int, lex_hex_int, lex_dec_int>;
+
+// ===========================================================================
+
+using lex_inf = sequence<character<'i'>, character<'n'>, character<'f'>>;
+using lex_nan = sequence<character<'n'>, character<'a'>, character<'n'>>;
+using lex_special_float = sequence<maybe<lex_sign>, either<lex_inf, lex_nan>>;
+
+using lex_zero_prefixable_int = sequence<lex_digit, repeat<either<lex_digit,
+    sequence<lex_underscore, lex_digit>>, unlimited>>;
+
+using lex_fractional_part = sequence<character<'.'>, lex_zero_prefixable_int>;
+
+using lex_exponent_part   = sequence<either<character<'e'>, character<'E'>>,
+        maybe<lex_sign>, lex_zero_prefixable_int>;
+
+using lex_float = either<lex_special_float,
+      sequence<lex_dec_int, either<lex_exponent_part,
+      sequence<lex_fractional_part, maybe<lex_exponent_part>>>>>;
+
+// ===========================================================================
+
+using lex_true = sequence<character<'t'>, character<'r'>,
+                          character<'u'>, character<'e'>>;
+using lex_false = sequence<character<'f'>, character<'a'>, character<'l'>,
+                           character<'s'>, character<'e'>>;
+using lex_boolean = either<lex_true, lex_false>;
+
+// ===========================================================================
+
+using lex_date_fullyear = repeat<lex_digit, exactly<4>>;
+using lex_date_month    = repeat<lex_digit, exactly<2>>;
+using lex_date_mday     = repeat<lex_digit, exactly<2>>;
+using lex_time_delim    = either<character<'T'>, character<'t'>, character<' '>>;
+using lex_time_hour     = repeat<lex_digit, exactly<2>>;
+using lex_time_minute   = repeat<lex_digit, exactly<2>>;
+using lex_time_second   = repeat<lex_digit, exactly<2>>;
+using lex_time_secfrac  = sequence<character<'.'>,
+                                   repeat<lex_digit, at_least<1>>>;
+
+using lex_time_numoffset = sequence<either<character<'+'>, character<'-'>>,
+                                    sequence<lex_time_hour, character<':'>,
+                                             lex_time_minute>>;
+using lex_time_offset = either<character<'Z'>, character<'z'>,
+                               lex_time_numoffset>;
+
+using lex_partial_time = sequence<lex_time_hour,   character<':'>,
+                                  lex_time_minute, character<':'>,
+                                  lex_time_second, maybe<lex_time_secfrac>>;
+using lex_full_date    = sequence<lex_date_fullyear, character<'-'>,
+                                  lex_date_month,    character<'-'>,
+                                  lex_date_mday>;
+using lex_full_time    = sequence<lex_partial_time, lex_time_offset>;
+
+using lex_offset_date_time = sequence<lex_full_date, lex_time_delim, lex_full_time>;
+using lex_local_date_time  = sequence<lex_full_date, lex_time_delim, lex_partial_time>;
+using lex_local_date       = lex_full_date;
+using lex_local_time       = lex_partial_time;
+
+// ===========================================================================
+
+using lex_quotation_mark  = character<'"'>;
+using lex_basic_unescaped = exclude<either<in_range<0x00, 0x08>, // 0x09 (tab) is allowed
+                                           in_range<0x0A, 0x1F>,
+                                           character<0x22>, character<0x5C>,
+                                           character<0x7F>>>;
+
+using lex_escape          = character<'\\'>;
+using lex_escape_unicode_short = sequence<character<'u'>,
+                                          repeat<lex_hex_dig, exactly<4>>>;
+using lex_escape_unicode_long  = sequence<character<'U'>,
+                                          repeat<lex_hex_dig, exactly<8>>>;
+using lex_escape_seq_char = either<character<'"'>, character<'\\'>,
+                                   character<'b'>, character<'f'>,
+                                   character<'n'>, character<'r'>,
+                                   character<'t'>,
+                                   lex_escape_unicode_short,
+                                   lex_escape_unicode_long
+                                   >;
+using lex_escaped      = sequence<lex_escape, lex_escape_seq_char>;
+using lex_basic_char   = either<lex_basic_unescaped, lex_escaped>;
+using lex_basic_string = sequence<lex_quotation_mark,
+                                  repeat<lex_basic_char, unlimited>,
+                                  lex_quotation_mark>;
+
+// After toml post-v0.5.0, it is explicitly clarified how quotes in ml-strings
+// are allowed to be used.
+// After this, the following strings are *explicitly* allowed.
+// - One or two `"`s in a multi-line basic string is allowed wherever it is.
+// - Three consecutive `"`s in a multi-line basic string is considered as a delimiter.
+// - One or two `"`s can appear just before or after the delimiter.
+// ```toml
+// str4 = """Here are two quotation marks: "". Simple enough."""
+// str5 = """Here are three quotation marks: ""\"."""
+// str6 = """Here are fifteen quotation marks: ""\"""\"""\"""\"""\"."""
+// str7 = """"This," she said, "is just a pointless statement.""""
+// ```
+// In the current implementation (v3.3.0), it is difficult to parse `str7` in
+// the above example. It is difficult to recognize `"` at the end of string body
+// collectly. It will be misunderstood as a `"""` delimiter and an additional,
+// invalid `"`. Like this:
+// ```console
+//   what():  [error] toml::parse_table: invalid line format
+//  --> hoge.toml
+//     |
+//  13 | str7 = """"This," she said, "is just a pointless statement.""""
+//     |                                                               ^- expected newline, but got '"'.
+// ```
+// As a quick workaround for this problem, `lex_ml_basic_string_delim` was
+// split into two, `lex_ml_basic_string_open` and `lex_ml_basic_string_close`.
+// `lex_ml_basic_string_open` allows only `"""`. `_close` allows 3-5 `"`s.
+// In parse_ml_basic_string() function, the trailing `"`s will be attached to
+// the string body.
+//
+using lex_ml_basic_string_delim = repeat<lex_quotation_mark, exactly<3>>;
+using lex_ml_basic_string_open  = lex_ml_basic_string_delim;
+using lex_ml_basic_string_close = sequence<
+        repeat<lex_quotation_mark, exactly<3>>,
+        maybe<lex_quotation_mark>, maybe<lex_quotation_mark>
+    >;
+
+using lex_ml_basic_unescaped    = exclude<either<in_range<0x00, 0x08>, // 0x09 is tab
+                                                 in_range<0x0A, 0x1F>,
+                                                 character<0x5C>, // backslash
+                                                 character<0x7F>, // DEL
+                                                 lex_ml_basic_string_delim>>;
+
+using lex_ml_basic_escaped_newline = sequence<
+        lex_escape, maybe<lex_ws>, lex_newline,
+        repeat<either<lex_ws, lex_newline>, unlimited>>;
+
+using lex_ml_basic_char = either<lex_ml_basic_unescaped, lex_escaped>;
+using lex_ml_basic_body = repeat<either<lex_ml_basic_char, lex_newline,
+                                        lex_ml_basic_escaped_newline>,
+                                 unlimited>;
+using lex_ml_basic_string = sequence<lex_ml_basic_string_open,
+                                     lex_ml_basic_body,
+                                     lex_ml_basic_string_close>;
+
+using lex_literal_char = exclude<either<in_range<0x00, 0x08>, in_range<0x0A, 0x1F>,
+                                        character<0x7F>, character<0x27>>>;
+using lex_apostrophe = character<'\''>;
+using lex_literal_string = sequence<lex_apostrophe,
+                                    repeat<lex_literal_char, unlimited>,
+                                    lex_apostrophe>;
+
+// the same reason as above.
+using lex_ml_literal_string_delim = repeat<lex_apostrophe, exactly<3>>;
+using lex_ml_literal_string_open  = lex_ml_literal_string_delim;
+using lex_ml_literal_string_close = sequence<
+        repeat<lex_apostrophe, exactly<3>>,
+        maybe<lex_apostrophe>, maybe<lex_apostrophe>
+    >;
+
+using lex_ml_literal_char = exclude<either<in_range<0x00, 0x08>,
+                                           in_range<0x0A, 0x1F>,
+                                           character<0x7F>,
+                                           lex_ml_literal_string_delim>>;
+using lex_ml_literal_body = repeat<either<lex_ml_literal_char, lex_newline>,
+                                   unlimited>;
+using lex_ml_literal_string = sequence<lex_ml_literal_string_open,
+                                       lex_ml_literal_body,
+                                       lex_ml_literal_string_close>;
+
+using lex_string = either<lex_ml_basic_string,   lex_basic_string,
+                          lex_ml_literal_string, lex_literal_string>;
+
+// ===========================================================================
+using lex_dot_sep = sequence<maybe<lex_ws>, character<'.'>, maybe<lex_ws>>;
+
+using lex_unquoted_key = repeat<either<lex_alpha, lex_digit,
+                                       character<'-'>, character<'_'>>,
+                                at_least<1>>;
+using lex_quoted_key = either<lex_basic_string, lex_literal_string>;
+using lex_simple_key = either<lex_unquoted_key, lex_quoted_key>;
+using lex_dotted_key = sequence<lex_simple_key,
+                                repeat<sequence<lex_dot_sep, lex_simple_key>,
+                                       at_least<1>
+                                       >
+                                >;
+using lex_key = either<lex_dotted_key, lex_simple_key>;
+
+using lex_keyval_sep = sequence<maybe<lex_ws>,
+                                character<'='>,
+                                maybe<lex_ws>>;
+
+using lex_std_table_open  = character<'['>;
+using lex_std_table_close = character<']'>;
+using lex_std_table       = sequence<lex_std_table_open,
+                                     maybe<lex_ws>,
+                                     lex_key,
+                                     maybe<lex_ws>,
+                                     lex_std_table_close>;
+
+using lex_array_table_open  = sequence<lex_std_table_open,  lex_std_table_open>;
+using lex_array_table_close = sequence<lex_std_table_close, lex_std_table_close>;
+using lex_array_table       = sequence<lex_array_table_open,
+                                       maybe<lex_ws>,
+                                       lex_key,
+                                       maybe<lex_ws>,
+                                       lex_array_table_close>;
+
+using lex_utf8_1byte = in_range<0x00, 0x7F>;
+using lex_utf8_2byte = sequence<
+        in_range<static_cast<char>(0xC2), static_cast<char>(0xDF)>,
+        in_range<static_cast<char>(0x80), static_cast<char>(0xBF)>
+    >;
+using lex_utf8_3byte = sequence<either<
+        sequence<character<static_cast<char>(0xE0)>,                          in_range<static_cast<char>(0xA0), static_cast<char>(0xBF)>>,
+        sequence<in_range <static_cast<char>(0xE1), static_cast<char>(0xEC)>, in_range<static_cast<char>(0x80), static_cast<char>(0xBF)>>,
+        sequence<character<static_cast<char>(0xED)>,                          in_range<static_cast<char>(0x80), static_cast<char>(0x9F)>>,
+        sequence<in_range <static_cast<char>(0xEE), static_cast<char>(0xEF)>, in_range<static_cast<char>(0x80), static_cast<char>(0xBF)>>
+    >, in_range<static_cast<char>(0x80), static_cast<char>(0xBF)>>;
+using lex_utf8_4byte = sequence<either<
+        sequence<character<static_cast<char>(0xF0)>,                          in_range<static_cast<char>(0x90), static_cast<char>(0xBF)>>,
+        sequence<in_range <static_cast<char>(0xF1), static_cast<char>(0xF3)>, in_range<static_cast<char>(0x80), static_cast<char>(0xBF)>>,
+        sequence<character<static_cast<char>(0xF4)>,                          in_range<static_cast<char>(0x80), static_cast<char>(0x8F)>>
+    >, in_range<static_cast<char>(0x80), static_cast<char>(0xBF)>,
+       in_range<static_cast<char>(0x80), static_cast<char>(0xBF)>>;
+using lex_utf8_code = either<
+        lex_utf8_1byte,
+        lex_utf8_2byte,
+        lex_utf8_3byte,
+        lex_utf8_4byte
+    >;
+
+using lex_comment_start_symbol = character<'#'>;
+using lex_non_eol_ascii = either<character<0x09>, in_range<0x20, 0x7E>>;
+using lex_comment = sequence<lex_comment_start_symbol, repeat<either<
+    lex_non_eol_ascii, lex_utf8_2byte, lex_utf8_3byte, lex_utf8_4byte>, unlimited>>;
+
+} // detail
+} // toml
+#endif // TOML_LEXER_HPP
diff --git a/src/toml11/toml/literal.hpp b/src/toml11/toml/literal.hpp
new file mode 100644
index 000000000..04fbbc13e
--- /dev/null
+++ b/src/toml11/toml/literal.hpp
@@ -0,0 +1,113 @@
+//     Copyright Toru Niina 2019.
+// Distributed under the MIT License.
+#ifndef TOML11_LITERAL_HPP
+#define TOML11_LITERAL_HPP
+#include "parser.hpp"
+
+namespace toml
+{
+inline namespace literals
+{
+inline namespace toml_literals
+{
+
+// implementation
+inline ::toml::basic_value<TOML11_DEFAULT_COMMENT_STRATEGY, std::unordered_map, std::vector>
+literal_internal_impl(::toml::detail::location loc)
+{
+    using value_type = ::toml::basic_value<
+        TOML11_DEFAULT_COMMENT_STRATEGY, std::unordered_map, std::vector>;
+    // if there are some comments or empty lines, skip them.
+    using skip_line = ::toml::detail::repeat<toml::detail::sequence<
+            ::toml::detail::maybe<::toml::detail::lex_ws>,
+            ::toml::detail::maybe<::toml::detail::lex_comment>,
+            ::toml::detail::lex_newline
+        >, ::toml::detail::at_least<1>>;
+    skip_line::invoke(loc);
+
+    // if there are some whitespaces before a value, skip them.
+    using skip_ws = ::toml::detail::repeat<
+        ::toml::detail::lex_ws, ::toml::detail::at_least<1>>;
+    skip_ws::invoke(loc);
+
+    // to distinguish arrays and tables, first check it is a table or not.
+    //
+    // "[1,2,3]"_toml;   // this is an array
+    // "[table]"_toml;   // a table that has an empty table named "table" inside.
+    // "[[1,2,3]]"_toml; // this is an array of arrays
+    // "[[table]]"_toml; // this is a table that has an array of tables inside.
+    //
+    // "[[1]]"_toml;     // this can be both... (currently it becomes a table)
+    // "1 = [{}]"_toml;  // this is a table that has an array of table named 1.
+    // "[[1,]]"_toml;    // this is an array of arrays.
+    // "[[1],]"_toml;    // this also.
+
+    const auto the_front = loc.iter();
+
+    const bool is_table_key = ::toml::detail::lex_std_table::invoke(loc);
+    loc.reset(the_front);
+
+    const bool is_aots_key  = ::toml::detail::lex_array_table::invoke(loc);
+    loc.reset(the_front);
+
+    // If it is neither a table-key or a array-of-table-key, it may be a value.
+    if(!is_table_key && !is_aots_key)
+    {
+        if(auto data = ::toml::detail::parse_value<value_type>(loc))
+        {
+            return data.unwrap();
+        }
+    }
+
+    // Note that still it can be a table, because the literal might be something
+    // like the following.
+    // ```cpp
+    // R"( // c++11 raw string literals
+    //   key = "value"
+    //   int = 42
+    // )"_toml;
+    // ```
+    // It is a valid toml file.
+    // It should be parsed as if we parse a file with this content.
+
+    if(auto data = ::toml::detail::parse_toml_file<value_type>(loc))
+    {
+        return data.unwrap();
+    }
+    else // none of them.
+    {
+        throw ::toml::syntax_error(data.unwrap_err(), source_location(loc));
+    }
+
+}
+
+inline ::toml::basic_value<TOML11_DEFAULT_COMMENT_STRATEGY, std::unordered_map, std::vector>
+operator"" _toml(const char* str, std::size_t len)
+{
+    ::toml::detail::location loc(
+            std::string("TOML literal encoded in a C++ code"),
+            std::vector<char>(str, str + len));
+    // literal length does not include the null character at the end.
+    return literal_internal_impl(std::move(loc));
+}
+
+// value of __cplusplus in C++2a/20 mode is not fixed yet along compilers.
+// So here we use the feature test macro for `char8_t` itself.
+#if defined(__cpp_char8_t) && __cpp_char8_t >= 201811L
+// value of u8"" literal has been changed from char to char8_t and char8_t is
+// NOT compatible to char
+inline ::toml::basic_value<TOML11_DEFAULT_COMMENT_STRATEGY, std::unordered_map, std::vector>
+operator"" _toml(const char8_t* str, std::size_t len)
+{
+    ::toml::detail::location loc(
+            std::string("TOML literal encoded in a C++ code"),
+            std::vector<char>(reinterpret_cast<const char*>(str),
+                              reinterpret_cast<const char*>(str) + len));
+    return literal_internal_impl(std::move(loc));
+}
+#endif
+
+} // toml_literals
+} // literals
+} // toml
+#endif//TOML11_LITERAL_HPP
diff --git a/src/toml11/toml/macros.hpp b/src/toml11/toml/macros.hpp
new file mode 100644
index 000000000..e8f91aecd
--- /dev/null
+++ b/src/toml11/toml/macros.hpp
@@ -0,0 +1,121 @@
+#ifndef TOML11_MACROS_HPP
+#define TOML11_MACROS_HPP
+
+#define TOML11_STRINGIZE_AUX(x) #x
+#define TOML11_STRINGIZE(x)     TOML11_STRINGIZE_AUX(x)
+
+#define TOML11_CONCATENATE_AUX(x, y) x##y
+#define TOML11_CONCATENATE(x, y)     TOML11_CONCATENATE_AUX(x, y)
+
+// ============================================================================
+// TOML11_DEFINE_CONVERSION_NON_INTRUSIVE
+
+#ifndef TOML11_WITHOUT_DEFINE_NON_INTRUSIVE
+
+// ----------------------------------------------------------------------------
+// TOML11_ARGS_SIZE
+
+#define TOML11_INDEX_RSEQ() \
+    32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, \
+    16, 15, 14, 13, 12, 11, 10,  9,  8,  7,  6,  5,  4,  3,  2,  1, 0
+#define TOML11_ARGS_SIZE_IMPL(\
+    ARG1,  ARG2,  ARG3,  ARG4,  ARG5,  ARG6,  ARG7,  ARG8,  ARG9,  ARG10, \
+    ARG11, ARG12, ARG13, ARG14, ARG15, ARG16, ARG17, ARG18, ARG19, ARG20, \
+    ARG21, ARG22, ARG23, ARG24, ARG25, ARG26, ARG27, ARG28, ARG29, ARG30, \
+    ARG31, ARG32, N, ...) N
+#define TOML11_ARGS_SIZE_AUX(...) TOML11_ARGS_SIZE_IMPL(__VA_ARGS__)
+#define TOML11_ARGS_SIZE(...) TOML11_ARGS_SIZE_AUX(__VA_ARGS__, TOML11_INDEX_RSEQ())
+
+// ----------------------------------------------------------------------------
+// TOML11_FOR_EACH_VA_ARGS
+
+#define TOML11_FOR_EACH_VA_ARGS_AUX_1( FUNCTOR, ARG1     ) FUNCTOR(ARG1)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_2( FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_1( FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_3( FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_2( FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_4( FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_3( FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_5( FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_4( FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_6( FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_5( FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_7( FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_6( FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_8( FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_7( FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_9( FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_8( FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_10(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_9( FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_11(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_10(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_12(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_11(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_13(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_12(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_14(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_13(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_15(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_14(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_16(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_15(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_17(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_16(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_18(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_17(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_19(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_18(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_20(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_19(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_21(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_20(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_22(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_21(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_23(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_22(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_24(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_23(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_25(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_24(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_26(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_25(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_27(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_26(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_28(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_27(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_29(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_28(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_30(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_29(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_31(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_30(FUNCTOR, __VA_ARGS__)
+#define TOML11_FOR_EACH_VA_ARGS_AUX_32(FUNCTOR, ARG1, ...) FUNCTOR(ARG1) TOML11_FOR_EACH_VA_ARGS_AUX_31(FUNCTOR, __VA_ARGS__)
+
+#define TOML11_FOR_EACH_VA_ARGS(FUNCTOR, ...)\
+    TOML11_CONCATENATE(TOML11_FOR_EACH_VA_ARGS_AUX_, TOML11_ARGS_SIZE(__VA_ARGS__))(FUNCTOR, __VA_ARGS__)
+
+// ----------------------------------------------------------------------------
+// TOML11_DEFINE_CONVERSION_NON_INTRUSIVE
+
+// use it in the following way.
+// ```cpp
+// namespace foo
+// {
+// struct Foo
+// {
+//     std::string s;
+//     double      d;
+//     int         i;
+// };
+// } // foo
+//
+// TOML11_DEFINE_CONVERSION_NON_INTRUSIVE(foo::Foo, s, d, i)
+// ```
+// And then you can use `toml::find<foo::Foo>(file, "foo");`
+//
+#define TOML11_FIND_MEMBER_VARIABLE_FROM_VALUE(VAR_NAME)\
+    obj.VAR_NAME = toml::find<decltype(obj.VAR_NAME)>(v, TOML11_STRINGIZE(VAR_NAME));
+
+#define TOML11_ASSIGN_MEMBER_VARIABLE_TO_VALUE(VAR_NAME)\
+    v[TOML11_STRINGIZE(VAR_NAME)] = obj.VAR_NAME;
+
+#define TOML11_DEFINE_CONVERSION_NON_INTRUSIVE(NAME, ...)\
+    namespace toml {                                                                     \
+    template<>                                                                           \
+    struct from<NAME>                                                                    \
+    {                                                                                    \
+        template<typename C, template<typename ...> class T,                             \
+                 template<typename ...> class A>                                         \
+        static NAME from_toml(const basic_value<C, T, A>& v)                             \
+        {                                                                                \
+            NAME obj;                                                                    \
+            TOML11_FOR_EACH_VA_ARGS(TOML11_FIND_MEMBER_VARIABLE_FROM_VALUE, __VA_ARGS__) \
+            return obj;                                                                  \
+        }                                                                                \
+    };                                                                                   \
+    template<>                                                                           \
+    struct into<NAME>                                                                    \
+    {                                                                                    \
+        static value into_toml(const NAME& obj)                                          \
+        {                                                                                \
+            ::toml::value v = ::toml::table{};                                           \
+            TOML11_FOR_EACH_VA_ARGS(TOML11_ASSIGN_MEMBER_VARIABLE_TO_VALUE, __VA_ARGS__) \
+            return v;                                                                    \
+        }                                                                                \
+    };                                                                                   \
+    } /* toml */
+
+#endif// TOML11_WITHOUT_DEFINE_NON_INTRUSIVE
+
+#endif// TOML11_MACROS_HPP
diff --git a/src/toml11/toml/parser.hpp b/src/toml11/toml/parser.hpp
new file mode 100644
index 000000000..e31179918
--- /dev/null
+++ b/src/toml11/toml/parser.hpp
@@ -0,0 +1,2364 @@
+//     Copyright Toru Niina 2017.
+// Distributed under the MIT License.
+#ifndef TOML11_PARSER_HPP
+#define TOML11_PARSER_HPP
+#include <cstring>
+#include <fstream>
+#include <sstream>
+
+#include "combinator.hpp"
+#include "lexer.hpp"
+#include "region.hpp"
+#include "result.hpp"
+#include "types.hpp"
+#include "value.hpp"
+
+#ifndef TOML11_DISABLE_STD_FILESYSTEM
+#ifdef __cpp_lib_filesystem
+#if __has_include(<filesystem>)
+#define TOML11_HAS_STD_FILESYSTEM
+#include <filesystem>
+#endif // has_include(<string_view>)
+#endif // __cpp_lib_filesystem
+#endif // TOML11_DISABLE_STD_FILESYSTEM
+
+namespace toml
+{
+namespace detail
+{
+
+inline result<std::pair<boolean, region>, std::string>
+parse_boolean(location& loc)
+{
+    const auto first = loc.iter();
+    if(const auto token = lex_boolean::invoke(loc))
+    {
+        const auto reg = token.unwrap();
+        if     (reg.str() == "true")  {return ok(std::make_pair(true,  reg));}
+        else if(reg.str() == "false") {return ok(std::make_pair(false, reg));}
+        else // internal error.
+        {
+            throw internal_error(format_underline(
+                "toml::parse_boolean: internal error",
+                {{source_location(reg), "invalid token"}}),
+                source_location(reg));
+        }
+    }
+    loc.reset(first); //rollback
+    return err(format_underline("toml::parse_boolean: ",
+               {{source_location(loc), "the next token is not a boolean"}}));
+}
+
+inline result<std::pair<integer, region>, std::string>
+parse_binary_integer(location& loc)
+{
+    const auto first = loc.iter();
+    if(const auto token = lex_bin_int::invoke(loc))
+    {
+        auto str = token.unwrap().str();
+        assert(str.size() > 2); // minimum -> 0b1
+        integer retval(0), base(1);
+        for(auto i(str.rbegin()), e(str.rend() - 2); i!=e; ++i)
+        {
+            if     (*i == '1'){retval += base; base *= 2;}
+            else if(*i == '0'){base *= 2;}
+            else if(*i == '_'){/* do nothing. */}
+            else // internal error.
+            {
+                throw internal_error(format_underline(
+                    "toml::parse_integer: internal error",
+                    {{source_location(token.unwrap()), "invalid token"}}),
+                    source_location(loc));
+            }
+        }
+        return ok(std::make_pair(retval, token.unwrap()));
+    }
+    loc.reset(first);
+    return err(format_underline("toml::parse_binary_integer:",
+               {{source_location(loc), "the next token is not an integer"}}));
+}
+
+inline result<std::pair<integer, region>, std::string>
+parse_octal_integer(location& loc)
+{
+    const auto first = loc.iter();
+    if(const auto token = lex_oct_int::invoke(loc))
+    {
+        auto str = token.unwrap().str();
+        str.erase(std::remove(str.begin(), str.end(), '_'), str.end());
+        str.erase(str.begin()); str.erase(str.begin()); // remove `0o` prefix
+
+        std::istringstream iss(str);
+        integer retval(0);
+        iss >> std::oct >> retval;
+        return ok(std::make_pair(retval, token.unwrap()));
+    }
+    loc.reset(first);
+    return err(format_underline("toml::parse_octal_integer:",
+               {{source_location(loc), "the next token is not an integer"}}));
+}
+
+inline result<std::pair<integer, region>, std::string>
+parse_hexadecimal_integer(location& loc)
+{
+    const auto first = loc.iter();
+    if(const auto token = lex_hex_int::invoke(loc))
+    {
+        auto str = token.unwrap().str();
+        str.erase(std::remove(str.begin(), str.end(), '_'), str.end());
+        str.erase(str.begin()); str.erase(str.begin()); // remove `0x` prefix
+
+        std::istringstream iss(str);
+        integer retval(0);
+        iss >> std::hex >> retval;
+        return ok(std::make_pair(retval, token.unwrap()));
+    }
+    loc.reset(first);
+    return err(format_underline("toml::parse_hexadecimal_integer",
+               {{source_location(loc), "the next token is not an integer"}}));
+}
+
+inline result<std::pair<integer, region>, std::string>
+parse_integer(location& loc)
+{
+    const auto first = loc.iter();
+    if(first != loc.end() && *first == '0')
+    {
+        const auto second = std::next(first);
+        if(second == loc.end()) // the token is just zero.
+        {
+            loc.advance();
+            return ok(std::make_pair(0, region(loc, first, second)));
+        }
+
+        if(*second == 'b') {return parse_binary_integer     (loc);} // 0b1100
+        if(*second == 'o') {return parse_octal_integer      (loc);} // 0o775
+        if(*second == 'x') {return parse_hexadecimal_integer(loc);} // 0xC0FFEE
+
+        if(std::isdigit(*second))
+        {
+            return err(format_underline("toml::parse_integer: "
+                "leading zero in an Integer is not allowed.",
+                {{source_location(loc), "leading zero"}}));
+        }
+        else if(std::isalpha(*second))
+        {
+             return err(format_underline("toml::parse_integer: "
+                "unknown integer prefix appeared.",
+                {{source_location(loc), "none of 0x, 0o, 0b"}}));
+        }
+    }
+
+    if(const auto token = lex_dec_int::invoke(loc))
+    {
+        auto str = token.unwrap().str();
+        str.erase(std::remove(str.begin(), str.end(), '_'), str.end());
+
+        std::istringstream iss(str);
+        integer retval(0);
+        iss >> retval;
+        return ok(std::make_pair(retval, token.unwrap()));
+    }
+    loc.reset(first);
+    return err(format_underline("toml::parse_integer: ",
+               {{source_location(loc), "the next token is not an integer"}}));
+}
+
+inline result<std::pair<floating, region>, std::string>
+parse_floating(location& loc)
+{
+    const auto first = loc.iter();
+    if(const auto token = lex_float::invoke(loc))
+    {
+        auto str = token.unwrap().str();
+        if(str == "inf" || str == "+inf")
+        {
+            if(std::numeric_limits<floating>::has_infinity)
+            {
+                return ok(std::make_pair(
+                    std::numeric_limits<floating>::infinity(), token.unwrap()));
+            }
+            else
+            {
+                throw std::domain_error("toml::parse_floating: inf value found"
+                    " but the current environment does not support inf. Please"
+                    " make sure that the floating-point implementation conforms"
+                    " IEEE 754/ISO 60559 international standard.");
+            }
+        }
+        else if(str == "-inf")
+        {
+            if(std::numeric_limits<floating>::has_infinity)
+            {
+                return ok(std::make_pair(
+                    -std::numeric_limits<floating>::infinity(), token.unwrap()));
+            }
+            else
+            {
+                throw std::domain_error("toml::parse_floating: inf value found"
+                    " but the current environment does not support inf. Please"
+                    " make sure that the floating-point implementation conforms"
+                    " IEEE 754/ISO 60559 international standard.");
+            }
+        }
+        else if(str == "nan" || str == "+nan")
+        {
+            if(std::numeric_limits<floating>::has_quiet_NaN)
+            {
+                return ok(std::make_pair(
+                    std::numeric_limits<floating>::quiet_NaN(), token.unwrap()));
+            }
+            else if(std::numeric_limits<floating>::has_signaling_NaN)
+            {
+                return ok(std::make_pair(
+                    std::numeric_limits<floating>::signaling_NaN(), token.unwrap()));
+            }
+            else
+            {
+                throw std::domain_error("toml::parse_floating: NaN value found"
+                    " but the current environment does not support NaN. Please"
+                    " make sure that the floating-point implementation conforms"
+                    " IEEE 754/ISO 60559 international standard.");
+            }
+        }
+        else if(str == "-nan")
+        {
+            if(std::numeric_limits<floating>::has_quiet_NaN)
+            {
+                return ok(std::make_pair(
+                    -std::numeric_limits<floating>::quiet_NaN(), token.unwrap()));
+            }
+            else if(std::numeric_limits<floating>::has_signaling_NaN)
+            {
+                return ok(std::make_pair(
+                    -std::numeric_limits<floating>::signaling_NaN(), token.unwrap()));
+            }
+            else
+            {
+                throw std::domain_error("toml::parse_floating: NaN value found"
+                    " but the current environment does not support NaN. Please"
+                    " make sure that the floating-point implementation conforms"
+                    " IEEE 754/ISO 60559 international standard.");
+            }
+        }
+        str.erase(std::remove(str.begin(), str.end(), '_'), str.end());
+        std::istringstream iss(str);
+        floating v(0.0);
+        iss >> v;
+        return ok(std::make_pair(v, token.unwrap()));
+    }
+    loc.reset(first);
+    return err(format_underline("toml::parse_floating: ",
+               {{source_location(loc), "the next token is not a float"}}));
+}
+
+inline std::string read_utf8_codepoint(const region& reg, const location& loc)
+{
+    const auto str = reg.str().substr(1);
+    std::uint_least32_t codepoint;
+    std::istringstream iss(str);
+    iss >> std::hex >> codepoint;
+
+    const auto to_char = [](const std::uint_least32_t i) noexcept -> char {
+        const auto uc = static_cast<unsigned char>(i);
+        return *reinterpret_cast<const char*>(std::addressof(uc));
+    };
+
+    std::string character;
+    if(codepoint < 0x80) // U+0000 ... U+0079 ; just an ASCII.
+    {
+        character += static_cast<char>(codepoint);
+    }
+    else if(codepoint < 0x800) //U+0080 ... U+07FF
+    {
+        // 110yyyyx 10xxxxxx; 0x3f == 0b0011'1111
+        character += to_char(0xC0| codepoint >> 6);
+        character += to_char(0x80|(codepoint & 0x3F));
+    }
+    else if(codepoint < 0x10000) // U+0800...U+FFFF
+    {
+        if(0xD800 <= codepoint && codepoint <= 0xDFFF)
+        {
+            throw syntax_error(format_underline(
+                "toml::read_utf8_codepoint: codepoints in the range "
+                "[0xD800, 0xDFFF] are not valid UTF-8.", {{
+                    source_location(loc), "not a valid UTF-8 codepoint"
+                }}), source_location(loc));
+        }
+        assert(codepoint < 0xD800 || 0xDFFF < codepoint);
+        // 1110yyyy 10yxxxxx 10xxxxxx
+        character += to_char(0xE0| codepoint >> 12);
+        character += to_char(0x80|(codepoint >> 6 & 0x3F));
+        character += to_char(0x80|(codepoint      & 0x3F));
+    }
+    else if(codepoint < 0x110000) // U+010000 ... U+10FFFF
+    {
+        // 11110yyy 10yyxxxx 10xxxxxx 10xxxxxx
+        character += to_char(0xF0| codepoint >> 18);
+        character += to_char(0x80|(codepoint >> 12 & 0x3F));
+        character += to_char(0x80|(codepoint >> 6  & 0x3F));
+        character += to_char(0x80|(codepoint       & 0x3F));
+    }
+    else // out of UTF-8 region
+    {
+        throw syntax_error(format_underline("toml::read_utf8_codepoint:"
+            " input codepoint is too large.",
+            {{source_location(loc), "should be in [0x00..0x10FFFF]"}}),
+            source_location(loc));
+    }
+    return character;
+}
+
+inline result<std::string, std::string> parse_escape_sequence(location& loc)
+{
+    const auto first = loc.iter();
+    if(first == loc.end() || *first != '\\')
+    {
+        return err(format_underline("toml::parse_escape_sequence: ", {{
+            source_location(loc), "the next token is not a backslash \"\\\""}}));
+    }
+    loc.advance();
+    switch(*loc.iter())
+    {
+        case '\\':{loc.advance(); return ok(std::string("\\"));}
+        case '"' :{loc.advance(); return ok(std::string("\""));}
+        case 'b' :{loc.advance(); return ok(std::string("\b"));}
+        case 't' :{loc.advance(); return ok(std::string("\t"));}
+        case 'n' :{loc.advance(); return ok(std::string("\n"));}
+        case 'f' :{loc.advance(); return ok(std::string("\f"));}
+        case 'r' :{loc.advance(); return ok(std::string("\r"));}
+        case 'u' :
+        {
+            if(const auto token = lex_escape_unicode_short::invoke(loc))
+            {
+                return ok(read_utf8_codepoint(token.unwrap(), loc));
+            }
+            else
+            {
+                return err(format_underline("parse_escape_sequence: "
+                           "invalid token found in UTF-8 codepoint uXXXX.",
+                           {{source_location(loc), "here"}}));
+            }
+        }
+        case 'U':
+        {
+            if(const auto token = lex_escape_unicode_long::invoke(loc))
+            {
+                return ok(read_utf8_codepoint(token.unwrap(), loc));
+            }
+            else
+            {
+                return err(format_underline("parse_escape_sequence: "
+                           "invalid token found in UTF-8 codepoint Uxxxxxxxx",
+                           {{source_location(loc), "here"}}));
+            }
+        }
+    }
+
+    const auto msg = format_underline("parse_escape_sequence: "
+           "unknown escape sequence appeared.", {{source_location(loc),
+           "escape sequence is one of \\, \", b, t, n, f, r, uxxxx, Uxxxxxxxx"}},
+           /* Hints = */{"if you want to write backslash as just one backslash, "
+           "use literal string like: regex    = '<\\i\\c*\\s*>'"});
+    loc.reset(first);
+    return err(msg);
+}
+
+inline std::ptrdiff_t check_utf8_validity(const std::string& reg)
+{
+    location loc("tmp", reg);
+    const auto u8 = repeat<lex_utf8_code, unlimited>::invoke(loc);
+    if(!u8 || loc.iter() != loc.end())
+    {
+        const auto error_location = std::distance(loc.begin(), loc.iter());
+        assert(0 <= error_location);
+        return error_location;
+    }
+    return -1;
+}
+
+inline result<std::pair<toml::string, region>, std::string>
+parse_ml_basic_string(location& loc)
+{
+    const auto first = loc.iter();
+    if(const auto token = lex_ml_basic_string::invoke(loc))
+    {
+        auto inner_loc = loc;
+        inner_loc.reset(first);
+
+        std::string retval;
+        retval.reserve(token.unwrap().size());
+
+        auto delim = lex_ml_basic_string_open::invoke(inner_loc);
+        if(!delim)
+        {
+            throw internal_error(format_underline(
+                "parse_ml_basic_string: invalid token",
+                {{source_location(inner_loc), "should be \"\"\""}}),
+                source_location(inner_loc));
+        }
+        // immediate newline is ignored (if exists)
+        /* discard return value */ lex_newline::invoke(inner_loc);
+
+        delim = none();
+        while(!delim)
+        {
+            using lex_unescaped_seq = repeat<
+                either<lex_ml_basic_unescaped, lex_newline>, unlimited>;
+            if(auto unescaped = lex_unescaped_seq::invoke(inner_loc))
+            {
+                retval += unescaped.unwrap().str();
+            }
+            if(auto escaped = parse_escape_sequence(inner_loc))
+            {
+                retval += escaped.unwrap();
+            }
+            if(auto esc_nl = lex_ml_basic_escaped_newline::invoke(inner_loc))
+            {
+                // ignore newline after escape until next non-ws char
+            }
+            if(inner_loc.iter() == inner_loc.end())
+            {
+                throw internal_error(format_underline(
+                    "parse_ml_basic_string: unexpected end of region",
+                    {{source_location(inner_loc), "not sufficient token"}}),
+                    source_location(inner_loc));
+            }
+            delim = lex_ml_basic_string_close::invoke(inner_loc);
+        }
+        // `lex_ml_basic_string_close` allows 3 to 5 `"`s to allow 1 or 2 `"`s
+        // at just before the delimiter. Here, we need to attach `"`s at the
+        // end of the string body, if it exists.
+        // For detail, see the definition of `lex_ml_basic_string_close`.
+        assert(std::all_of(delim.unwrap().first(), delim.unwrap().last(),
+                           [](const char c) noexcept {return c == '\"';}));
+        switch(delim.unwrap().size())
+        {
+            case 3: {break;}
+            case 4: {retval += "\"";  break;}
+            case 5: {retval += "\"\""; break;}
+            default:
+            {
+                throw internal_error(format_underline(
+                    "parse_ml_basic_string: closing delimiter has invalid length",
+                    {{source_location(inner_loc), "end of this"}}),
+                    source_location(inner_loc));
+            }
+        }
+
+        const auto err_loc = check_utf8_validity(token.unwrap().str());
+        if(err_loc == -1)
+        {
+            return ok(std::make_pair(toml::string(retval), token.unwrap()));
+        }
+        else
+        {
+            inner_loc.reset(first);
+            inner_loc.advance(err_loc);
+            throw syntax_error(format_underline(
+                "parse_ml_basic_string: invalid utf8 sequence found",
+                {{source_location(inner_loc), "here"}}),
+                source_location(inner_loc));
+        }
+    }
+    else
+    {
+        loc.reset(first);
+        return err(format_underline("toml::parse_ml_basic_string: "
+                   "the next token is not a valid multiline string",
+                   {{source_location(loc), "here"}}));
+    }
+}
+
+inline result<std::pair<toml::string, region>, std::string>
+parse_basic_string(location& loc)
+{
+    const auto first = loc.iter();
+    if(const auto token = lex_basic_string::invoke(loc))
+    {
+        auto inner_loc = loc;
+        inner_loc.reset(first);
+
+        auto quot = lex_quotation_mark::invoke(inner_loc);
+        if(!quot)
+        {
+            throw internal_error(format_underline("parse_basic_string: "
+                "invalid token", {{source_location(inner_loc), "should be \""}}),
+                source_location(inner_loc));
+        }
+
+        std::string retval;
+        retval.reserve(token.unwrap().size());
+
+        quot = none();
+        while(!quot)
+        {
+            using lex_unescaped_seq = repeat<lex_basic_unescaped, unlimited>;
+            if(auto unescaped = lex_unescaped_seq::invoke(inner_loc))
+            {
+                retval += unescaped.unwrap().str();
+            }
+            if(auto escaped = parse_escape_sequence(inner_loc))
+            {
+                retval += escaped.unwrap();
+            }
+            if(inner_loc.iter() == inner_loc.end())
+            {
+                throw internal_error(format_underline(
+                    "parse_basic_string: unexpected end of region",
+                    {{source_location(inner_loc), "not sufficient token"}}),
+                    source_location(inner_loc));
+            }
+            quot = lex_quotation_mark::invoke(inner_loc);
+        }
+
+        const auto err_loc = check_utf8_validity(token.unwrap().str());
+        if(err_loc == -1)
+        {
+            return ok(std::make_pair(toml::string(retval), token.unwrap()));
+        }
+        else
+        {
+            inner_loc.reset(first);
+            inner_loc.advance(err_loc);
+            throw syntax_error(format_underline(
+                "parse_ml_basic_string: invalid utf8 sequence found",
+                {{source_location(inner_loc), "here"}}),
+                source_location(inner_loc));
+        }
+    }
+    else
+    {
+        loc.reset(first); // rollback
+        return err(format_underline("toml::parse_basic_string: "
+                   "the next token is not a valid string",
+                   {{source_location(loc), "here"}}));
+    }
+}
+
+inline result<std::pair<toml::string, region>, std::string>
+parse_ml_literal_string(location& loc)
+{
+    const auto first = loc.iter();
+    if(const auto token = lex_ml_literal_string::invoke(loc))
+    {
+        location inner_loc(loc.name(), token.unwrap().str());
+
+        const auto open = lex_ml_literal_string_open::invoke(inner_loc);
+        if(!open)
+        {
+            throw internal_error(format_underline(
+                "parse_ml_literal_string: invalid token",
+                {{source_location(inner_loc), "should be '''"}}),
+                source_location(inner_loc));
+        }
+        // immediate newline is ignored (if exists)
+        /* discard return value */ lex_newline::invoke(inner_loc);
+
+        const auto body = lex_ml_literal_body::invoke(inner_loc);
+
+        const auto close = lex_ml_literal_string_close::invoke(inner_loc);
+        if(!close)
+        {
+            throw internal_error(format_underline(
+                "parse_ml_literal_string: invalid token",
+                {{source_location(inner_loc), "should be '''"}}),
+                source_location(inner_loc));
+        }
+        // `lex_ml_literal_string_close` allows 3 to 5 `'`s to allow 1 or 2 `'`s
+        // at just before the delimiter. Here, we need to attach `'`s at the
+        // end of the string body, if it exists.
+        // For detail, see the definition of `lex_ml_basic_string_close`.
+
+        std::string retval = body.unwrap().str();
+        assert(std::all_of(close.unwrap().first(), close.unwrap().last(),
+                           [](const char c) noexcept {return c == '\'';}));
+        switch(close.unwrap().size())
+        {
+            case 3: {break;}
+            case 4: {retval += "'";  break;}
+            case 5: {retval += "''"; break;}
+            default:
+            {
+                throw internal_error(format_underline(
+                    "parse_ml_literal_string: closing delimiter has invalid length",
+                    {{source_location(inner_loc), "end of this"}}),
+                    source_location(inner_loc));
+            }
+        }
+
+        const auto err_loc = check_utf8_validity(token.unwrap().str());
+        if(err_loc == -1)
+        {
+            return ok(std::make_pair(toml::string(retval, toml::string_t::literal),
+                                     token.unwrap()));
+        }
+        else
+        {
+            inner_loc.reset(first);
+            inner_loc.advance(err_loc);
+            throw syntax_error(format_underline(
+                "parse_ml_basic_string: invalid utf8 sequence found",
+                {{source_location(inner_loc), "here"}}),
+                source_location(inner_loc));
+        }
+    }
+    else
+    {
+        loc.reset(first); // rollback
+        return err(format_underline("toml::parse_ml_literal_string: "
+                   "the next token is not a valid multiline literal string",
+                   {{source_location(loc), "here"}}));
+    }
+}
+
+inline result<std::pair<toml::string, region>, std::string>
+parse_literal_string(location& loc)
+{
+    const auto first = loc.iter();
+    if(const auto token = lex_literal_string::invoke(loc))
+    {
+        location inner_loc(loc.name(), token.unwrap().str());
+
+        const auto open = lex_apostrophe::invoke(inner_loc);
+        if(!open)
+        {
+            throw internal_error(format_underline(
+                "parse_literal_string: invalid token",
+                {{source_location(inner_loc), "should be '"}}),
+                source_location(inner_loc));
+        }
+
+        const auto body = repeat<lex_literal_char, unlimited>::invoke(inner_loc);
+
+        const auto close = lex_apostrophe::invoke(inner_loc);
+        if(!close)
+        {
+            throw internal_error(format_underline(
+                "parse_literal_string: invalid token",
+                {{source_location(inner_loc), "should be '"}}),
+                source_location(inner_loc));
+        }
+
+        const auto err_loc = check_utf8_validity(token.unwrap().str());
+        if(err_loc == -1)
+        {
+            return ok(std::make_pair(
+                      toml::string(body.unwrap().str(), toml::string_t::literal),
+                      token.unwrap()));
+        }
+        else
+        {
+            inner_loc.reset(first);
+            inner_loc.advance(err_loc);
+            throw syntax_error(format_underline(
+                "parse_ml_basic_string: invalid utf8 sequence found",
+                {{source_location(inner_loc), "here"}}),
+                source_location(inner_loc));
+        }
+    }
+    else
+    {
+        loc.reset(first); // rollback
+        return err(format_underline("toml::parse_literal_string: "
+                   "the next token is not a valid literal string",
+                   {{source_location(loc), "here"}}));
+    }
+}
+
+inline result<std::pair<toml::string, region>, std::string>
+parse_string(location& loc)
+{
+    if(loc.iter() != loc.end() && *(loc.iter()) == '"')
+    {
+        if(loc.iter() + 1 != loc.end() && *(loc.iter() + 1) == '"' &&
+           loc.iter() + 2 != loc.end() && *(loc.iter() + 2) == '"')
+        {
+            return parse_ml_basic_string(loc);
+        }
+        else
+        {
+            return parse_basic_string(loc);
+        }
+    }
+    else if(loc.iter() != loc.end() && *(loc.iter()) == '\'')
+    {
+        if(loc.iter() + 1 != loc.end() && *(loc.iter() + 1) == '\'' &&
+           loc.iter() + 2 != loc.end() && *(loc.iter() + 2) == '\'')
+        {
+            return parse_ml_literal_string(loc);
+        }
+        else
+        {
+            return parse_literal_string(loc);
+        }
+    }
+    return err(format_underline("toml::parse_string: ",
+                {{source_location(loc), "the next token is not a string"}}));
+}
+
+inline result<std::pair<local_date, region>, std::string>
+parse_local_date(location& loc)
+{
+    const auto first = loc.iter();
+    if(const auto token = lex_local_date::invoke(loc))
+    {
+        location inner_loc(loc.name(), token.unwrap().str());
+
+        const auto y = lex_date_fullyear::invoke(inner_loc);
+        if(!y || inner_loc.iter() == inner_loc.end() || *inner_loc.iter() != '-')
+        {
+            throw internal_error(format_underline(
+                "toml::parse_inner_local_date: invalid year format",
+                {{source_location(inner_loc), "should be `-`"}}),
+                source_location(inner_loc));
+        }
+        inner_loc.advance();
+        const auto m = lex_date_month::invoke(inner_loc);
+        if(!m || inner_loc.iter() == inner_loc.end() || *inner_loc.iter() != '-')
+        {
+            throw internal_error(format_underline(
+                "toml::parse_local_date: invalid month format",
+                {{source_location(inner_loc), "should be `-`"}}),
+                source_location(inner_loc));
+        }
+        inner_loc.advance();
+        const auto d = lex_date_mday::invoke(inner_loc);
+        if(!d)
+        {
+            throw internal_error(format_underline(
+                "toml::parse_local_date: invalid day format",
+                {{source_location(inner_loc), "here"}}),
+                source_location(inner_loc));
+        }
+
+        const auto year  = static_cast<std::int16_t>(from_string<int>(y.unwrap().str(), 0));
+        const auto month = static_cast<std::int8_t >(from_string<int>(m.unwrap().str(), 0));
+        const auto day   = static_cast<std::int8_t >(from_string<int>(d.unwrap().str(), 0));
+
+        // We briefly check whether the input date is valid or not. But here, we
+        // only check if the RFC3339 compliance.
+        //     Actually there are several special date that does not exist,
+        // because of historical reasons, such as 1582/10/5-1582/10/14 (only in
+        // several countries). But here, we do not care about such a complicated
+        // rule. It makes the code complicated and there is only low probability
+        // that such a specific date is needed in practice. If someone need to
+        // validate date accurately, that means that the one need a specialized
+        // library for their purpose in a different layer.
+        {
+            const bool is_leap = (year % 4 == 0) && ((year % 100 != 0) || (year % 400 == 0));
+            const auto max_day = (month == 2) ? (is_leap ? 29 : 28) :
+                ((month == 4 || month == 6 || month == 9 || month == 11) ? 30 : 31);
+
+            if((month < 1 || 12 < month) || (day < 1 || max_day < day))
+            {
+                throw syntax_error(format_underline("toml::parse_date: "
+                    "invalid date: it does not conform RFC3339.", {{
+                    source_location(loc), "month should be 01-12, day should be"
+                    " 01-28,29,30,31, depending on month/year."
+                    }}), source_location(inner_loc));
+            }
+        }
+        return ok(std::make_pair(local_date(year, static_cast<month_t>(month - 1), day),
+                                 token.unwrap()));
+    }
+    else
+    {
+        loc.reset(first);
+        return err(format_underline("toml::parse_local_date: ",
+            {{source_location(loc), "the next token is not a local_date"}}));
+    }
+}
+
+inline result<std::pair<local_time, region>, std::string>
+parse_local_time(location& loc)
+{
+    const auto first = loc.iter();
+    if(const auto token = lex_local_time::invoke(loc))
+    {
+        location inner_loc(loc.name(), token.unwrap().str());
+
+        const auto h = lex_time_hour::invoke(inner_loc);
+        if(!h || inner_loc.iter() == inner_loc.end() || *inner_loc.iter() != ':')
+        {
+            throw internal_error(format_underline(
+                "toml::parse_local_time: invalid year format",
+                {{source_location(inner_loc), "should be `:`"}}),
+                source_location(inner_loc));
+        }
+        inner_loc.advance();
+        const auto m = lex_time_minute::invoke(inner_loc);
+        if(!m || inner_loc.iter() == inner_loc.end() || *inner_loc.iter() != ':')
+        {
+            throw internal_error(format_underline(
+                "toml::parse_local_time: invalid month format",
+                {{source_location(inner_loc), "should be `:`"}}),
+                source_location(inner_loc));
+        }
+        inner_loc.advance();
+        const auto s = lex_time_second::invoke(inner_loc);
+        if(!s)
+        {
+            throw internal_error(format_underline(
+                "toml::parse_local_time: invalid second format",
+                {{source_location(inner_loc), "here"}}),
+                source_location(inner_loc));
+        }
+
+        const int hour   = from_string<int>(h.unwrap().str(), 0);
+        const int minute = from_string<int>(m.unwrap().str(), 0);
+        const int second = from_string<int>(s.unwrap().str(), 0);
+
+        if((hour   < 0 || 23 < hour) || (minute < 0 || 59 < minute) ||
+           (second < 0 || 60 < second)) // it may be leap second
+        {
+            throw syntax_error(format_underline("toml::parse_time: "
+                "invalid time: it does not conform RFC3339.", {{
+                source_location(loc), "hour should be 00-23, minute should be"
+                " 00-59, second should be 00-60 (depending on the leap"
+                " second rules.)"}}), source_location(inner_loc));
+        }
+
+        local_time time(hour, minute, second, 0, 0);
+
+        const auto before_secfrac = inner_loc.iter();
+        if(const auto secfrac = lex_time_secfrac::invoke(inner_loc))
+        {
+            auto sf = secfrac.unwrap().str();
+            sf.erase(sf.begin()); // sf.front() == '.'
+            switch(sf.size() % 3)
+            {
+                case 2:  sf += '0';  break;
+                case 1:  sf += "00"; break;
+                case 0:  break;
+                default: break;
+            }
+            if(sf.size() >= 9)
+            {
+                time.millisecond = from_string<std::uint16_t>(sf.substr(0, 3), 0u);
+                time.microsecond = from_string<std::uint16_t>(sf.substr(3, 3), 0u);
+                time.nanosecond  = from_string<std::uint16_t>(sf.substr(6, 3), 0u);
+            }
+            else if(sf.size() >= 6)
+            {
+                time.millisecond = from_string<std::uint16_t>(sf.substr(0, 3), 0u);
+                time.microsecond = from_string<std::uint16_t>(sf.substr(3, 3), 0u);
+            }
+            else if(sf.size() >= 3)
+            {
+                time.millisecond = from_string<std::uint16_t>(sf, 0u);
+                time.microsecond = 0u;
+            }
+        }
+        else
+        {
+            if(before_secfrac != inner_loc.iter())
+            {
+                throw internal_error(format_underline(
+                    "toml::parse_local_time: invalid subsecond format",
+                    {{source_location(inner_loc), "here"}}),
+                source_location(inner_loc));
+            }
+        }
+        return ok(std::make_pair(time, token.unwrap()));
+    }
+    else
+    {
+        loc.reset(first);
+        return err(format_underline("toml::parse_local_time: ",
+            {{source_location(loc), "the next token is not a local_time"}}));
+    }
+}
+
+inline result<std::pair<local_datetime, region>, std::string>
+parse_local_datetime(location& loc)
+{
+    const auto first = loc.iter();
+    if(const auto token = lex_local_date_time::invoke(loc))
+    {
+        location inner_loc(loc.name(), token.unwrap().str());
+        const auto date = parse_local_date(inner_loc);
+        if(!date || inner_loc.iter() == inner_loc.end())
+        {
+            throw internal_error(format_underline(
+                "toml::parse_local_datetime: invalid datetime format",
+                {{source_location(inner_loc), "date, not datetime"}}),
+                source_location(inner_loc));
+        }
+        const char delim = *(inner_loc.iter());
+        if(delim != 'T' && delim != 't' && delim != ' ')
+        {
+            throw internal_error(format_underline(
+                "toml::parse_local_datetime: invalid datetime format",
+                {{source_location(inner_loc), "should be `T` or ` ` (space)"}}),
+                source_location(inner_loc));
+        }
+        inner_loc.advance();
+        const auto time = parse_local_time(inner_loc);
+        if(!time)
+        {
+            throw internal_error(format_underline(
+                "toml::parse_local_datetime: invalid datetime format",
+                {{source_location(inner_loc), "invalid time format"}}),
+                source_location(inner_loc));
+        }
+        return ok(std::make_pair(
+            local_datetime(date.unwrap().first, time.unwrap().first),
+            token.unwrap()));
+    }
+    else
+    {
+        loc.reset(first);
+        return err(format_underline("toml::parse_local_datetime: ",
+            {{source_location(loc), "the next token is not a local_datetime"}}));
+    }
+}
+
+inline result<std::pair<offset_datetime, region>, std::string>
+parse_offset_datetime(location& loc)
+{
+    const auto first = loc.iter();
+    if(const auto token = lex_offset_date_time::invoke(loc))
+    {
+        location inner_loc(loc.name(), token.unwrap().str());
+        const auto datetime = parse_local_datetime(inner_loc);
+        if(!datetime || inner_loc.iter() == inner_loc.end())
+        {
+            throw internal_error(format_underline(
+                "toml::parse_offset_datetime: invalid datetime format",
+                {{source_location(inner_loc), "date, not datetime"}}),
+                source_location(inner_loc));
+        }
+        time_offset offset(0, 0);
+        if(const auto ofs = lex_time_numoffset::invoke(inner_loc))
+        {
+            const auto str = ofs.unwrap().str();
+
+            const auto hour   = from_string<int>(str.substr(1,2), 0);
+            const auto minute = from_string<int>(str.substr(4,2), 0);
+
+            if((hour < 0 || 23 < hour) || (minute < 0 || 59 < minute))
+            {
+                throw syntax_error(format_underline("toml::parse_offset_datetime: "
+                    "invalid offset: it does not conform RFC3339.", {{
+                    source_location(loc), "month should be 01-12, day should be"
+                    " 01-28,29,30,31, depending on month/year."
+                    }}), source_location(inner_loc));
+            }
+
+            if(str.front() == '+')
+            {
+                offset = time_offset(hour, minute);
+            }
+            else
+            {
+                offset = time_offset(-hour, -minute);
+            }
+        }
+        else if(*inner_loc.iter() != 'Z' && *inner_loc.iter() != 'z')
+        {
+            throw internal_error(format_underline(
+                "toml::parse_offset_datetime: invalid datetime format",
+                {{source_location(inner_loc), "should be `Z` or `+HH:MM`"}}),
+                source_location(inner_loc));
+        }
+        return ok(std::make_pair(offset_datetime(datetime.unwrap().first, offset),
+                                 token.unwrap()));
+    }
+    else
+    {
+        loc.reset(first);
+        return err(format_underline("toml::parse_offset_datetime: ",
+            {{source_location(loc), "the next token is not a offset_datetime"}}));
+    }
+}
+
+inline result<std::pair<key, region>, std::string>
+parse_simple_key(location& loc)
+{
+    if(const auto bstr = parse_basic_string(loc))
+    {
+        return ok(std::make_pair(bstr.unwrap().first.str, bstr.unwrap().second));
+    }
+    if(const auto lstr = parse_literal_string(loc))
+    {
+        return ok(std::make_pair(lstr.unwrap().first.str, lstr.unwrap().second));
+    }
+    if(const auto bare = lex_unquoted_key::invoke(loc))
+    {
+        const auto reg = bare.unwrap();
+        return ok(std::make_pair(reg.str(), reg));
+    }
+    return err(format_underline("toml::parse_simple_key: ",
+            {{source_location(loc), "the next token is not a simple key"}}));
+}
+
+// dotted key become vector of keys
+inline result<std::pair<std::vector<key>, region>, std::string>
+parse_key(location& loc)
+{
+    const auto first = loc.iter();
+    // dotted key -> `foo.bar.baz` where several single keys are chained by
+    // dots. Whitespaces between keys and dots are allowed.
+    if(const auto token = lex_dotted_key::invoke(loc))
+    {
+        const auto reg = token.unwrap();
+        location inner_loc(loc.name(), reg.str());
+        std::vector<key> keys;
+
+        while(inner_loc.iter() != inner_loc.end())
+        {
+            lex_ws::invoke(inner_loc);
+            if(const auto k = parse_simple_key(inner_loc))
+            {
+                keys.push_back(k.unwrap().first);
+            }
+            else
+            {
+                throw internal_error(format_underline(
+                    "toml::detail::parse_key: dotted key contains invalid key",
+                    {{source_location(inner_loc), k.unwrap_err()}}),
+                    source_location(inner_loc));
+            }
+
+            lex_ws::invoke(inner_loc);
+            if(inner_loc.iter() == inner_loc.end())
+            {
+                break;
+            }
+            else if(*inner_loc.iter() == '.')
+            {
+                inner_loc.advance(); // to skip `.`
+            }
+            else
+            {
+                throw internal_error(format_underline("toml::parse_key: "
+                    "dotted key contains invalid key ",
+                    {{source_location(inner_loc), "should be `.`"}}),
+                    source_location(inner_loc));
+            }
+        }
+        return ok(std::make_pair(keys, reg));
+    }
+    loc.reset(first);
+
+    // simple_key: a single (basic_string|literal_string|bare key)
+    if(const auto smpl = parse_simple_key(loc))
+    {
+        return ok(std::make_pair(std::vector<key>(1, smpl.unwrap().first),
+                                 smpl.unwrap().second));
+    }
+    return err(format_underline("toml::parse_key: an invalid key appeared.",
+                {{source_location(loc), "is not a valid key"}}, {
+                "bare keys  : non-empty strings composed only of [A-Za-z0-9_-].",
+                "quoted keys: same as \"basic strings\" or 'literal strings'.",
+                "dotted keys: sequence of bare or quoted keys joined with a dot."
+                }));
+}
+
+// forward-decl to implement parse_array and parse_table
+template<typename Value>
+result<Value, std::string> parse_value(location&);
+
+template<typename Value>
+result<std::pair<typename Value::array_type, region>, std::string>
+parse_array(location& loc)
+{
+    using value_type = Value;
+    using array_type = typename value_type::array_type;
+
+    const auto first = loc.iter();
+    if(loc.iter() == loc.end())
+    {
+        return err("toml::parse_array: input is empty");
+    }
+    if(*loc.iter() != '[')
+    {
+        return err("toml::parse_array: token is not an array");
+    }
+    loc.advance();
+
+    using lex_ws_comment_newline = repeat<
+        either<lex_wschar, lex_newline, lex_comment>, unlimited>;
+
+    array_type retval;
+    while(loc.iter() != loc.end())
+    {
+        lex_ws_comment_newline::invoke(loc); // skip
+
+        if(loc.iter() != loc.end() && *loc.iter() == ']')
+        {
+            loc.advance(); // skip ']'
+            return ok(std::make_pair(retval,
+                      region(loc, first, loc.iter())));
+        }
+
+        if(auto val = parse_value<value_type>(loc))
+        {
+            // After TOML v1.0.0-rc.1, array becomes to be able to have values
+            // with different types. So here we will omit this by default.
+            //
+            // But some of the test-suite checks if the parser accepts a hetero-
+            // geneous arrays, so we keep this for a while.
+#ifdef TOML11_DISALLOW_HETEROGENEOUS_ARRAYS
+            if(!retval.empty() && retval.front().type() != val.as_ok().type())
+            {
+                auto array_start_loc = loc;
+                array_start_loc.reset(first);
+
+                throw syntax_error(format_underline("toml::parse_array: "
+                    "type of elements should be the same each other.", {
+                        {source_location(array_start_loc), "array starts here"},
+                        {
+                            retval.front().location(),
+                            "value has type " + stringize(retval.front().type())
+                        },
+                        {
+                            val.unwrap().location(),
+                            "value has different type, " + stringize(val.unwrap().type())
+                        }
+                    }), source_location(loc));
+            }
+#endif
+            retval.push_back(std::move(val.unwrap()));
+        }
+        else
+        {
+            auto array_start_loc = loc;
+            array_start_loc.reset(first);
+
+            throw syntax_error(format_underline("toml::parse_array: "
+                "value having invalid format appeared in an array", {
+                    {source_location(array_start_loc), "array starts here"},
+                    {source_location(loc), "it is not a valid value."}
+                }), source_location(loc));
+        }
+
+        using lex_array_separator = sequence<maybe<lex_ws_comment_newline>, character<','>>;
+        const auto sp = lex_array_separator::invoke(loc);
+        if(!sp)
+        {
+            lex_ws_comment_newline::invoke(loc);
+            if(loc.iter() != loc.end() && *loc.iter() == ']')
+            {
+                loc.advance(); // skip ']'
+                return ok(std::make_pair(retval,
+                          region(loc, first, loc.iter())));
+            }
+            else
+            {
+                auto array_start_loc = loc;
+                array_start_loc.reset(first);
+
+                throw syntax_error(format_underline("toml::parse_array:"
+                    " missing array separator `,` after a value", {
+                        {source_location(array_start_loc), "array starts here"},
+                        {source_location(loc),             "should be `,`"}
+                    }), source_location(loc));
+            }
+        }
+    }
+    loc.reset(first);
+    throw syntax_error(format_underline("toml::parse_array: "
+            "array did not closed by `]`",
+            {{source_location(loc), "should be closed"}}),
+            source_location(loc));
+}
+
+template<typename Value>
+result<std::pair<std::pair<std::vector<key>, region>, Value>, std::string>
+parse_key_value_pair(location& loc)
+{
+    using value_type = Value;
+
+    const auto first = loc.iter();
+    auto key_reg = parse_key(loc);
+    if(!key_reg)
+    {
+        std::string msg = std::move(key_reg.unwrap_err());
+        // if the next token is keyvalue-separator, it means that there are no
+        // key. then we need to show error as "empty key is not allowed".
+        if(const auto keyval_sep = lex_keyval_sep::invoke(loc))
+        {
+            loc.reset(first);
+            msg = format_underline("toml::parse_key_value_pair: "
+                "empty key is not allowed.",
+                {{source_location(loc), "key expected before '='"}});
+        }
+        return err(std::move(msg));
+    }
+
+    const auto kvsp = lex_keyval_sep::invoke(loc);
+    if(!kvsp)
+    {
+        std::string msg;
+        // if the line contains '=' after the invalid sequence, possibly the
+        // error is in the key (like, invalid character in bare key).
+        const auto line_end = std::find(loc.iter(), loc.end(), '\n');
+        if(std::find(loc.iter(), line_end, '=') != line_end)
+        {
+            msg = format_underline("toml::parse_key_value_pair: "
+                "invalid format for key",
+                {{source_location(loc), "invalid character in key"}},
+                {"Did you forget '.' to separate dotted-key?",
+                "Allowed characters for bare key are [0-9a-zA-Z_-]."});
+        }
+        else // if not, the error is lack of key-value separator.
+        {
+            msg = format_underline("toml::parse_key_value_pair: "
+                "missing key-value separator `=`",
+                {{source_location(loc), "should be `=`"}});
+        }
+        loc.reset(first);
+        return err(std::move(msg));
+    }
+
+    const auto after_kvsp = loc.iter(); // err msg
+    auto val = parse_value<value_type>(loc);
+    if(!val)
+    {
+        std::string msg;
+        loc.reset(after_kvsp);
+        // check there is something not a comment/whitespace after `=`
+        if(sequence<maybe<lex_ws>, maybe<lex_comment>, lex_newline>::invoke(loc))
+        {
+            loc.reset(after_kvsp);
+            msg = format_underline("toml::parse_key_value_pair: "
+                    "missing value after key-value separator '='",
+                    {{source_location(loc), "expected value, but got nothing"}});
+        }
+        else // there is something not a comment/whitespace, so invalid format.
+        {
+            msg = std::move(val.unwrap_err());
+        }
+        loc.reset(first);
+        return err(msg);
+    }
+    return ok(std::make_pair(std::move(key_reg.unwrap()),
+                             std::move(val.unwrap())));
+}
+
+// for error messages.
+template<typename InputIterator>
+std::string format_dotted_keys(InputIterator first, const InputIterator last)
+{
+    static_assert(std::is_same<key,
+        typename std::iterator_traits<InputIterator>::value_type>::value,"");
+
+    std::string retval(*first++);
+    for(; first != last; ++first)
+    {
+        retval += '.';
+        retval += *first;
+    }
+    return retval;
+}
+
+// forward decl for is_valid_forward_table_definition
+result<std::pair<std::vector<key>, region>, std::string>
+parse_table_key(location& loc);
+template<typename Value>
+result<std::pair<typename Value::table_type, region>, std::string>
+parse_inline_table(location& loc);
+
+// The following toml file is allowed.
+// ```toml
+// [a.b.c]     # here, table `a` has element `b`.
+// foo = "bar"
+// [a]         # merge a = {baz = "qux"} to a = {b = {...}}
+// baz = "qux"
+// ```
+// But the following is not allowed.
+// ```toml
+// [a]
+// b.c.foo = "bar"
+// [a]             # error! the same table [a] defined!
+// baz = "qux"
+// ```
+// The following is neither allowed.
+// ```toml
+// a = { b.c.foo = "bar"}
+// [a]             # error! the same table [a] defined!
+// baz = "qux"
+// ```
+// Here, it parses region of `tab->at(k)` as a table key and check the depth
+// of the key. If the key region points deeper node, it would be allowed.
+// Otherwise, the key points the same node. It would be rejected.
+template<typename Value, typename Iterator>
+bool is_valid_forward_table_definition(const Value& fwd, const Value& inserting,
+        Iterator key_first, Iterator key_curr, Iterator key_last)
+{
+    // ------------------------------------------------------------------------
+    // check type of the value to be inserted/merged
+
+    std::string inserting_reg = "";
+    if(const auto ptr = detail::get_region(inserting))
+    {
+        inserting_reg = ptr->str();
+    }
+    location inserting_def("internal", std::move(inserting_reg));
+    if(const auto inlinetable = parse_inline_table<Value>(inserting_def))
+    {
+        // check if we are overwriting existing table.
+        // ```toml
+        // # NG
+        // a.b = 42
+        // a = {d = 3.14}
+        // ```
+        // Inserting an inline table to a existing super-table is not allowed in
+        // any case. If we found it, we can reject it without further checking.
+        return false;
+    }
+
+    // ------------------------------------------------------------------------
+    // check table defined before
+
+    std::string internal = "";
+    if(const auto ptr = detail::get_region(fwd))
+    {
+        internal = ptr->str();
+    }
+    location def("internal", std::move(internal));
+    if(const auto tabkeys = parse_table_key(def)) // [table.key]
+    {
+        // table keys always contains all the nodes from the root.
+        const auto& tks = tabkeys.unwrap().first;
+        if(std::size_t(std::distance(key_first, key_last)) == tks.size() &&
+           std::equal(tks.begin(), tks.end(), key_first))
+        {
+            // the keys are equivalent. it is not allowed.
+            return false;
+        }
+        // the keys are not equivalent. it is allowed.
+        return true;
+    }
+    if(const auto dotkeys = parse_key(def))
+    {
+        // consider the following case.
+        // [a]
+        // b.c = {d = 42}
+        // [a.b.c]
+        // e = 2.71
+        // this defines the table [a.b.c] twice. no?
+
+        // a dotted key starts from the node representing a table in which the
+        // dotted key belongs to.
+        const auto& dks = dotkeys.unwrap().first;
+        if(std::size_t(std::distance(key_curr, key_last)) == dks.size() &&
+           std::equal(dks.begin(), dks.end(), key_curr))
+        {
+            // the keys are equivalent. it is not allowed.
+            return false;
+        }
+        // the keys are not equivalent. it is allowed.
+        return true;
+    }
+    return false;
+}
+
+template<typename Value, typename InputIterator>
+result<bool, std::string>
+insert_nested_key(typename Value::table_type& root, const Value& v,
+                  InputIterator iter, const InputIterator last,
+                  region key_reg,
+                  const bool is_array_of_table = false)
+{
+    static_assert(std::is_same<key,
+        typename std::iterator_traits<InputIterator>::value_type>::value,"");
+
+    using value_type = Value;
+    using table_type = typename value_type::table_type;
+    using array_type = typename value_type::array_type;
+
+    const auto first = iter;
+    assert(iter != last);
+
+    table_type* tab = std::addressof(root);
+    for(; iter != last; ++iter) // search recursively
+    {
+        const key& k = *iter;
+        if(std::next(iter) == last) // k is the last key
+        {
+            // XXX if the value is array-of-tables, there can be several
+            //     tables that are in the same array. in that case, we need to
+            //     find the last element and insert it to there.
+            if(is_array_of_table)
+            {
+                if(tab->count(k) == 1) // there is already an array of table
+                {
+                    if(tab->at(k).is_table())
+                    {
+                        // show special err msg for conflicting table
+                        throw syntax_error(format_underline(concat_to_string(
+                            "toml::insert_value: array of table (\"",
+                            format_dotted_keys(first, last),
+                            "\") cannot be defined"), {
+                                {tab->at(k).location(), "table already defined"},
+                                {v.location(), "this conflicts with the previous table"}
+                            }), v.location());
+                    }
+                    else if(!(tab->at(k).is_array()))
+                    {
+                        throw syntax_error(format_underline(concat_to_string(
+                            "toml::insert_value: array of table (\"",
+                            format_dotted_keys(first, last), "\") collides with"
+                            " existing value"), {
+                                {tab->at(k).location(),
+                                 concat_to_string("this ", tab->at(k).type(),
+                                                  " value already exists")},
+                                {v.location(),
+                                 "while inserting this array-of-tables"}
+                            }), v.location());
+                    }
+                    // the above if-else-if checks tab->at(k) is an array
+                    auto& a = tab->at(k).as_array();
+                    // If table element is defined as [[array_of_tables]], it
+                    // cannot be an empty array. If an array of tables is
+                    // defined as `aot = []`, it cannot be appended.
+                    if(a.empty() || !(a.front().is_table()))
+                    {
+                        throw syntax_error(format_underline(concat_to_string(
+                            "toml::insert_value: array of table (\"",
+                            format_dotted_keys(first, last), "\") collides with"
+                            " existing value"), {
+                                {tab->at(k).location(),
+                                 concat_to_string("this ", tab->at(k).type(),
+                                                  " value already exists")},
+                                {v.location(),
+                                 "while inserting this array-of-tables"}
+                            }), v.location());
+                    }
+                    // avoid conflicting array of table like the following.
+                    // ```toml
+                    // a = [{b = 42}] # define a as an array of *inline* tables
+                    // [[a]]          # a is an array of *multi-line* tables
+                    // b = 54
+                    // ```
+                    // Here, from the type information, these cannot be detected
+                    // because inline table is also a table.
+                    // But toml v0.5.0 explicitly says it is invalid. The above
+                    // array-of-tables has a static size and appending to the
+                    // array is invalid.
+                    // In this library, multi-line table value has a region
+                    // that points to the key of the table (e.g. [[a]]). By
+                    // comparing the first two letters in key, we can detect
+                    // the array-of-table is inline or multiline.
+                    if(const auto ptr = detail::get_region(a.front()))
+                    {
+                        if(ptr->str().substr(0,2) != "[[")
+                        {
+                            throw syntax_error(format_underline(concat_to_string(
+                                "toml::insert_value: array of table (\"",
+                                format_dotted_keys(first, last), "\") collides "
+                                "with existing array-of-tables"), {
+                                    {tab->at(k).location(),
+                                     concat_to_string("this ", tab->at(k).type(),
+                                                      " value has static size")},
+                                    {v.location(),
+                                     "appending it to the statically sized array"}
+                                }), v.location());
+                        }
+                    }
+                    a.push_back(v);
+                    return ok(true);
+                }
+                else // if not, we need to create the array of table
+                {
+                    // XXX: Consider the following array of tables.
+                    // ```toml
+                    // # This is a comment.
+                    // [[aot]]
+                    // foo = "bar"
+                    // ```
+                    // Here, the comment is for `aot`. But here, actually two
+                    // values are defined. An array that contains tables, named
+                    // `aot`, and the 0th element of the `aot`, `{foo = "bar"}`.
+                    // Those two are different from each other. But both of them
+                    // points to the same portion of the TOML file, `[[aot]]`,
+                    // so `key_reg.comments()` returns `# This is a comment`.
+                    // If it is assigned as a comment of `aot` defined here, the
+                    // comment will be duplicated. Both the `aot` itself and
+                    // the 0-th element will have the same comment. This causes
+                    // "duplication of the same comments" bug when the data is
+                    // serialized.
+                    //     Next, consider the following.
+                    // ```toml
+                    // # comment 1
+                    // aot = [
+                    //     # comment 2
+                    //     {foo = "bar"},
+                    // ]
+                    // ```
+                    // In this case, we can distinguish those two comments. So
+                    // here we need to add "comment 1" to the `aot` and
+                    // "comment 2" to the 0th element of that.
+                    //     To distinguish those two, we check the key region.
+                    std::vector<std::string> comments{/* empty by default */};
+                    if(key_reg.str().substr(0, 2) != "[[")
+                    {
+                        comments = key_reg.comments();
+                    }
+                    value_type aot(array_type(1, v), key_reg, std::move(comments));
+                    tab->insert(std::make_pair(k, aot));
+                    return ok(true);
+                }
+            } // end if(array of table)
+
+            if(tab->count(k) == 1)
+            {
+                if(tab->at(k).is_table() && v.is_table())
+                {
+                    if(!is_valid_forward_table_definition(
+                                tab->at(k), v, first, iter, last))
+                    {
+                        throw syntax_error(format_underline(concat_to_string(
+                            "toml::insert_value: table (\"",
+                            format_dotted_keys(first, last),
+                            "\") already exists."), {
+                                {tab->at(k).location(), "table already exists here"},
+                                {v.location(), "table defined twice"}
+                            }), v.location());
+                    }
+                    // to allow the following toml file.
+                    // [a.b.c]
+                    // d = 42
+                    // [a]
+                    // e = 2.71
+                    auto& t = tab->at(k).as_table();
+                    for(const auto& kv : v.as_table())
+                    {
+                        if(tab->at(k).contains(kv.first))
+                        {
+                            throw syntax_error(format_underline(concat_to_string(
+                                "toml::insert_value: value (\"",
+                                format_dotted_keys(first, last),
+                                "\") already exists."), {
+                                    {t.at(kv.first).location(), "already exists here"},
+                                    {v.location(), "this defined twice"}
+                                }), v.location());
+                        }
+                        t[kv.first] = kv.second;
+                    }
+                    detail::change_region(tab->at(k), key_reg);
+                    return ok(true);
+                }
+                else if(v.is_table()                     &&
+                        tab->at(k).is_array()            &&
+                        tab->at(k).as_array().size() > 0 &&
+                        tab->at(k).as_array().front().is_table())
+                {
+                    throw syntax_error(format_underline(concat_to_string(
+                        "toml::insert_value: array of tables (\"",
+                        format_dotted_keys(first, last), "\") already exists."), {
+                            {tab->at(k).location(), "array of tables defined here"},
+                            {v.location(), "table conflicts with the previous array of table"}
+                        }), v.location());
+                }
+                else
+                {
+                    throw syntax_error(format_underline(concat_to_string(
+                        "toml::insert_value: value (\"",
+                        format_dotted_keys(first, last), "\") already exists."), {
+                            {tab->at(k).location(), "value already exists here"},
+                            {v.location(), "value defined twice"}
+                        }), v.location());
+                }
+            }
+            tab->insert(std::make_pair(k, v));
+            return ok(true);
+        }
+        else // k is not the last one, we should insert recursively
+        {
+            // if there is no corresponding value, insert it first.
+            // related: you don't need to write
+            // # [x]
+            // # [x.y]
+            // to write
+            // [x.y.z]
+            if(tab->count(k) == 0)
+            {
+                // a table that is defined implicitly doesn't have any comments.
+                (*tab)[k] = value_type(table_type{}, key_reg, {/*no comment*/});
+            }
+
+            // type checking...
+            if(tab->at(k).is_table())
+            {
+                // According to toml-lang/toml:36d3091b3 "Clarify that inline
+                // tables are immutable", check if it adds key-value pair to an
+                // inline table.
+                if(const auto* ptr = get_region(tab->at(k)))
+                {
+                    // here, if the value is a (multi-line) table, the region
+                    // should be something like `[table-name]`.
+                    if(ptr->front() == '{')
+                    {
+                        throw syntax_error(format_underline(concat_to_string(
+                            "toml::insert_value: inserting to an inline table (",
+                            format_dotted_keys(first, std::next(iter)),
+                            ") but inline tables are immutable"), {
+                                {tab->at(k).location(), "inline tables are immutable"},
+                                {v.location(), "inserting this"}
+                            }), v.location());
+                    }
+                }
+                tab = std::addressof((*tab)[k].as_table());
+            }
+            else if(tab->at(k).is_array()) // inserting to array-of-tables?
+            {
+                auto& a = (*tab)[k].as_array();
+                if(!a.back().is_table())
+                {
+                    throw syntax_error(format_underline(concat_to_string(
+                        "toml::insert_value: target (",
+                        format_dotted_keys(first, std::next(iter)),
+                        ") is neither table nor an array of tables"), {
+                            {a.back().location(), concat_to_string(
+                                    "actual type is ", a.back().type())},
+                            {v.location(), "inserting this"}
+                        }), v.location());
+                }
+                tab = std::addressof(a.back().as_table());
+            }
+            else
+            {
+                throw syntax_error(format_underline(concat_to_string(
+                    "toml::insert_value: target (",
+                    format_dotted_keys(first, std::next(iter)),
+                    ") is neither table nor an array of tables"), {
+                        {tab->at(k).location(), concat_to_string(
+                                "actual type is ", tab->at(k).type())},
+                        {v.location(), "inserting this"}
+                    }), v.location());
+            }
+        }
+    }
+    return err(std::string("toml::detail::insert_nested_key: never reach here"));
+}
+
+template<typename Value>
+result<std::pair<typename Value::table_type, region>, std::string>
+parse_inline_table(location& loc)
+{
+    using value_type = Value;
+    using table_type = typename value_type::table_type;
+
+    const auto first = loc.iter();
+    table_type retval;
+    if(!(loc.iter() != loc.end() && *loc.iter() == '{'))
+    {
+        return err(format_underline("toml::parse_inline_table: ",
+            {{source_location(loc), "the next token is not an inline table"}}));
+    }
+    loc.advance();
+
+    // check if the inline table is an empty table = { }
+    maybe<lex_ws>::invoke(loc);
+    if(loc.iter() != loc.end() && *loc.iter() == '}')
+    {
+        loc.advance(); // skip `}`
+        return ok(std::make_pair(retval, region(loc, first, loc.iter())));
+    }
+
+    // it starts from "{". it should be formatted as inline-table
+    while(loc.iter() != loc.end())
+    {
+        const auto kv_r = parse_key_value_pair<value_type>(loc);
+        if(!kv_r)
+        {
+            return err(kv_r.unwrap_err());
+        }
+
+        const auto&              kvpair  = kv_r.unwrap();
+        const std::vector<key>&  keys    = kvpair.first.first;
+        const auto&              key_reg = kvpair.first.second;
+        const value_type&        val     = kvpair.second;
+
+        const auto inserted =
+            insert_nested_key(retval, val, keys.begin(), keys.end(), key_reg);
+        if(!inserted)
+        {
+            throw internal_error("toml::parse_inline_table: "
+                "failed to insert value into table: " + inserted.unwrap_err(),
+                source_location(loc));
+        }
+
+        using lex_table_separator = sequence<maybe<lex_ws>, character<','>>;
+        const auto sp = lex_table_separator::invoke(loc);
+
+        if(!sp)
+        {
+            maybe<lex_ws>::invoke(loc);
+
+            if(loc.iter() == loc.end())
+            {
+                throw syntax_error(format_underline(
+                    "toml::parse_inline_table: missing table separator `}` ",
+                    {{source_location(loc), "should be `}`"}}),
+                    source_location(loc));
+            }
+            else if(*loc.iter() == '}')
+            {
+                loc.advance(); // skip `}`
+                return ok(std::make_pair(
+                            retval, region(loc, first, loc.iter())));
+            }
+            else if(*loc.iter() == '#' || *loc.iter() == '\r' || *loc.iter() == '\n')
+            {
+                throw syntax_error(format_underline(
+                    "toml::parse_inline_table: missing curly brace `}`",
+                    {{source_location(loc), "should be `}`"}}),
+                    source_location(loc));
+            }
+            else
+            {
+                throw syntax_error(format_underline(
+                    "toml::parse_inline_table: missing table separator `,` ",
+                    {{source_location(loc), "should be `,`"}}),
+                    source_location(loc));
+            }
+        }
+        else // `,` is found
+        {
+            maybe<lex_ws>::invoke(loc);
+            if(loc.iter() != loc.end() && *loc.iter() == '}')
+            {
+                throw syntax_error(format_underline(
+                    "toml::parse_inline_table: trailing comma is not allowed in"
+                    " an inline table",
+                    {{source_location(loc), "should be `}`"}}),
+                    source_location(loc));
+            }
+        }
+    }
+    loc.reset(first);
+    throw syntax_error(format_underline("toml::parse_inline_table: "
+            "inline table did not closed by `}`",
+            {{source_location(loc), "should be closed"}}),
+            source_location(loc));
+}
+
+inline result<value_t, std::string> guess_number_type(const location& l)
+{
+    // This function tries to find some (common) mistakes by checking characters
+    // that follows the last character of a value. But it is often difficult
+    // because some non-newline characters can appear after a value. E.g.
+    // spaces, tabs, commas (in an array or inline table), closing brackets
+    // (of an array or inline table), comment-sign (#). Since this function
+    // does not parse further, those characters are always allowed to be there.
+    location loc = l;
+
+    if(lex_offset_date_time::invoke(loc)) {return ok(value_t::offset_datetime);}
+    loc.reset(l.iter());
+
+    if(lex_local_date_time::invoke(loc))
+    {
+        // bad offset may appear after this.
+        if(loc.iter() != loc.end() && (*loc.iter() == '+' || *loc.iter() == '-'
+                    || *loc.iter() == 'Z' || *loc.iter() == 'z'))
+        {
+            return err(format_underline("bad offset: should be [+-]HH:MM or Z",
+                        {{source_location(loc), "[+-]HH:MM or Z"}},
+                        {"pass: +09:00, -05:30", "fail: +9:00, -5:30"}));
+        }
+        return ok(value_t::local_datetime);
+    }
+    loc.reset(l.iter());
+
+    if(lex_local_date::invoke(loc))
+    {
+        // bad time may appear after this.
+        // A space is allowed as a delimiter between local time. But there are
+        // both cases in which a space becomes valid or invalid.
+        // - invalid: 2019-06-16 7:00:00
+        // - valid  : 2019-06-16 07:00:00
+        if(loc.iter() != loc.end())
+        {
+            const auto c = *loc.iter();
+            if(c == 'T' || c == 't')
+            {
+                return err(format_underline("bad time: should be HH:MM:SS.subsec",
+                        {{source_location(loc), "HH:MM:SS.subsec"}},
+                        {"pass: 1979-05-27T07:32:00, 1979-05-27 07:32:00.999999",
+                         "fail: 1979-05-27T7:32:00, 1979-05-27 17:32"}));
+            }
+            if('0' <= c && c <= '9')
+            {
+                return err(format_underline("bad time: missing T",
+                        {{source_location(loc), "T or space required here"}},
+                        {"pass: 1979-05-27T07:32:00, 1979-05-27 07:32:00.999999",
+                         "fail: 1979-05-27T7:32:00, 1979-05-27 7:32"}));
+            }
+            if(c == ' ' && std::next(loc.iter()) != loc.end() &&
+                ('0' <= *std::next(loc.iter()) && *std::next(loc.iter())<= '9'))
+            {
+                loc.advance();
+                return err(format_underline("bad time: should be HH:MM:SS.subsec",
+                        {{source_location(loc), "HH:MM:SS.subsec"}},
+                        {"pass: 1979-05-27T07:32:00, 1979-05-27 07:32:00.999999",
+                         "fail: 1979-05-27T7:32:00, 1979-05-27 7:32"}));
+            }
+        }
+        return ok(value_t::local_date);
+    }
+    loc.reset(l.iter());
+
+    if(lex_local_time::invoke(loc)) {return ok(value_t::local_time);}
+    loc.reset(l.iter());
+
+    if(lex_float::invoke(loc))
+    {
+        if(loc.iter() != loc.end() && *loc.iter() == '_')
+        {
+            return err(format_underline("bad float: `_` should be surrounded by digits",
+                        {{source_location(loc), "here"}},
+                        {"pass: +1.0, -2e-2, 3.141_592_653_589, inf, nan",
+                         "fail: .0, 1., _1.0, 1.0_, 1_.0, 1.0__0"}));
+        }
+        return ok(value_t::floating);
+    }
+    loc.reset(l.iter());
+
+    if(lex_integer::invoke(loc))
+    {
+        if(loc.iter() != loc.end())
+        {
+            const auto c = *loc.iter();
+            if(c == '_')
+            {
+                return err(format_underline("bad integer: `_` should be surrounded by digits",
+                            {{source_location(loc), "here"}},
+                            {"pass: -42, 1_000, 1_2_3_4_5, 0xC0FFEE, 0b0010, 0o755",
+                             "fail: 1__000, 0123"}));
+            }
+            if('0' <= c && c <= '9')
+            {
+                // leading zero. point '0'
+                loc.retrace();
+                return err(format_underline("bad integer: leading zero",
+                            {{source_location(loc), "here"}},
+                            {"pass: -42, 1_000, 1_2_3_4_5, 0xC0FFEE, 0b0010, 0o755",
+                             "fail: 1__000, 0123"}));
+            }
+            if(c == ':' || c == '-')
+            {
+                return err(format_underline("bad datetime: invalid format",
+                            {{source_location(loc), "here"}},
+                            {"pass: 1979-05-27T07:32:00-07:00, 1979-05-27 07:32:00.999999Z",
+                             "fail: 1979-05-27T7:32:00-7:00, 1979-05-27 7:32-00:30"}));
+            }
+            if(c == '.' || c == 'e' || c == 'E')
+            {
+                return err(format_underline("bad float: invalid format",
+                            {{source_location(loc), "here"}},
+                            {"pass: +1.0, -2e-2, 3.141_592_653_589, inf, nan",
+                             "fail: .0, 1., _1.0, 1.0_, 1_.0, 1.0__0"}));
+            }
+        }
+        return ok(value_t::integer);
+    }
+    if(loc.iter() != loc.end() && *loc.iter() == '.')
+    {
+        return err(format_underline("bad float: invalid format",
+                {{source_location(loc), "integer part required before this"}},
+                {"pass: +1.0, -2e-2, 3.141_592_653_589, inf, nan",
+                 "fail: .0, 1., _1.0, 1.0_, 1_.0, 1.0__0"}));
+    }
+    if(loc.iter() != loc.end() && *loc.iter() == '_')
+    {
+        return err(format_underline("bad number: `_` should be surrounded by digits",
+                {{source_location(loc), "`_` is not surrounded by digits"}},
+                {"pass: -42, 1_000, 1_2_3_4_5, 0xC0FFEE, 0b0010, 0o755",
+                 "fail: 1__000, 0123"}));
+    }
+    return err(format_underline("bad format: unknown value appeared",
+                {{source_location(loc), "here"}}));
+}
+
+inline result<value_t, std::string> guess_value_type(const location& loc)
+{
+    switch(*loc.iter())
+    {
+        case '"' : {return ok(value_t::string);  }
+        case '\'': {return ok(value_t::string);  }
+        case 't' : {return ok(value_t::boolean); }
+        case 'f' : {return ok(value_t::boolean); }
+        case '[' : {return ok(value_t::array);   }
+        case '{' : {return ok(value_t::table);   }
+        case 'i' : {return ok(value_t::floating);} // inf.
+        case 'n' : {return ok(value_t::floating);} // nan.
+        default  : {return guess_number_type(loc);}
+    }
+}
+
+template<typename Value, typename T>
+result<Value, std::string>
+parse_value_helper(result<std::pair<T, region>, std::string> rslt)
+{
+    if(rslt.is_ok())
+    {
+        auto comments = rslt.as_ok().second.comments();
+        return ok(Value(std::move(rslt.as_ok()), std::move(comments)));
+    }
+    else
+    {
+        return err(std::move(rslt.as_err()));
+    }
+}
+
+template<typename Value>
+result<Value, std::string> parse_value(location& loc)
+{
+    const auto first = loc.iter();
+    if(first == loc.end())
+    {
+        return err(format_underline("toml::parse_value: input is empty",
+                   {{source_location(loc), ""}}));
+    }
+
+    const auto type = guess_value_type(loc);
+    if(!type)
+    {
+        return err(type.unwrap_err());
+    }
+
+    switch(type.unwrap())
+    {
+        case value_t::boolean        : {return parse_value_helper<Value>(parse_boolean(loc)            );}
+        case value_t::integer        : {return parse_value_helper<Value>(parse_integer(loc)            );}
+        case value_t::floating       : {return parse_value_helper<Value>(parse_floating(loc)           );}
+        case value_t::string         : {return parse_value_helper<Value>(parse_string(loc)             );}
+        case value_t::offset_datetime: {return parse_value_helper<Value>(parse_offset_datetime(loc)    );}
+        case value_t::local_datetime : {return parse_value_helper<Value>(parse_local_datetime(loc)     );}
+        case value_t::local_date     : {return parse_value_helper<Value>(parse_local_date(loc)         );}
+        case value_t::local_time     : {return parse_value_helper<Value>(parse_local_time(loc)         );}
+        case value_t::array          : {return parse_value_helper<Value>(parse_array<Value>(loc)       );}
+        case value_t::table          : {return parse_value_helper<Value>(parse_inline_table<Value>(loc));}
+        default:
+        {
+            const auto msg = format_underline("toml::parse_value: "
+                    "unknown token appeared", {{source_location(loc), "unknown"}});
+            loc.reset(first);
+            return err(msg);
+        }
+    }
+}
+
+inline result<std::pair<std::vector<key>, region>, std::string>
+parse_table_key(location& loc)
+{
+    if(auto token = lex_std_table::invoke(loc))
+    {
+        location inner_loc(loc.name(), token.unwrap().str());
+
+        const auto open = lex_std_table_open::invoke(inner_loc);
+        if(!open || inner_loc.iter() == inner_loc.end())
+        {
+            throw internal_error(format_underline(
+                "toml::parse_table_key: no `[`",
+                {{source_location(inner_loc), "should be `[`"}}),
+                source_location(inner_loc));
+        }
+        // to skip [ a . b . c ]
+        //          ^----------- this whitespace
+        lex_ws::invoke(inner_loc);
+        const auto keys = parse_key(inner_loc);
+        if(!keys)
+        {
+            throw internal_error(format_underline(
+                "toml::parse_table_key: invalid key",
+                {{source_location(inner_loc), "not key"}}),
+                source_location(inner_loc));
+        }
+        // to skip [ a . b . c ]
+        //                    ^-- this whitespace
+        lex_ws::invoke(inner_loc);
+        const auto close = lex_std_table_close::invoke(inner_loc);
+        if(!close)
+        {
+            throw internal_error(format_underline(
+                "toml::parse_table_key: no `]`",
+                {{source_location(inner_loc), "should be `]`"}}),
+                source_location(inner_loc));
+        }
+
+        // after [table.key], newline or EOF(empty table) required.
+        if(loc.iter() != loc.end())
+        {
+            using lex_newline_after_table_key =
+                sequence<maybe<lex_ws>, maybe<lex_comment>, lex_newline>;
+            const auto nl = lex_newline_after_table_key::invoke(loc);
+            if(!nl)
+            {
+                throw syntax_error(format_underline(
+                    "toml::parse_table_key: newline required after [table.key]",
+                    {{source_location(loc), "expected newline"}}),
+                    source_location(loc));
+            }
+        }
+        return ok(std::make_pair(keys.unwrap().first, token.unwrap()));
+    }
+    else
+    {
+        return err(format_underline("toml::parse_table_key: "
+            "not a valid table key", {{source_location(loc), "here"}}));
+    }
+}
+
+inline result<std::pair<std::vector<key>, region>, std::string>
+parse_array_table_key(location& loc)
+{
+    if(auto token = lex_array_table::invoke(loc))
+    {
+        location inner_loc(loc.name(), token.unwrap().str());
+
+        const auto open = lex_array_table_open::invoke(inner_loc);
+        if(!open || inner_loc.iter() == inner_loc.end())
+        {
+            throw internal_error(format_underline(
+                "toml::parse_array_table_key: no `[[`",
+                {{source_location(inner_loc), "should be `[[`"}}),
+                source_location(inner_loc));
+        }
+        lex_ws::invoke(inner_loc);
+        const auto keys = parse_key(inner_loc);
+        if(!keys)
+        {
+            throw internal_error(format_underline(
+                "toml::parse_array_table_key: invalid key",
+                {{source_location(inner_loc), "not a key"}}),
+                source_location(inner_loc));
+        }
+        lex_ws::invoke(inner_loc);
+        const auto close = lex_array_table_close::invoke(inner_loc);
+        if(!close)
+        {
+            throw internal_error(format_underline(
+                "toml::parse_table_key: no `]]`",
+                {{source_location(inner_loc), "should be `]]`"}}),
+                source_location(inner_loc));
+        }
+
+        // after [[table.key]], newline or EOF(empty table) required.
+        if(loc.iter() != loc.end())
+        {
+            using lex_newline_after_table_key =
+                sequence<maybe<lex_ws>, maybe<lex_comment>, lex_newline>;
+            const auto nl = lex_newline_after_table_key::invoke(loc);
+            if(!nl)
+            {
+                throw syntax_error(format_underline("toml::"
+                    "parse_array_table_key: newline required after [[table.key]]",
+                    {{source_location(loc), "expected newline"}}),
+                    source_location(loc));
+            }
+        }
+        return ok(std::make_pair(keys.unwrap().first, token.unwrap()));
+    }
+    else
+    {
+        return err(format_underline("toml::parse_array_table_key: "
+            "not a valid table key", {{source_location(loc), "here"}}));
+    }
+}
+
+// parse table body (key-value pairs until the iter hits the next [tablekey])
+template<typename Value>
+result<typename Value::table_type, std::string>
+parse_ml_table(location& loc)
+{
+    using value_type = Value;
+    using table_type = typename value_type::table_type;
+
+    const auto first = loc.iter();
+    if(first == loc.end())
+    {
+        return ok(table_type{});
+    }
+
+    // XXX at lest one newline is needed.
+    using skip_line = repeat<
+        sequence<maybe<lex_ws>, maybe<lex_comment>, lex_newline>, at_least<1>>;
+    skip_line::invoke(loc);
+    lex_ws::invoke(loc);
+
+    table_type tab;
+    while(loc.iter() != loc.end())
+    {
+        lex_ws::invoke(loc);
+        const auto before = loc.iter();
+        if(const auto tmp = parse_array_table_key(loc)) // next table found
+        {
+            loc.reset(before);
+            return ok(tab);
+        }
+        if(const auto tmp = parse_table_key(loc)) // next table found
+        {
+            loc.reset(before);
+            return ok(tab);
+        }
+
+        if(const auto kv = parse_key_value_pair<value_type>(loc))
+        {
+            const auto&              kvpair  = kv.unwrap();
+            const std::vector<key>&  keys    = kvpair.first.first;
+            const auto&              key_reg = kvpair.first.second;
+            const value_type&        val     = kvpair.second;
+            const auto inserted =
+                insert_nested_key(tab, val, keys.begin(), keys.end(), key_reg);
+            if(!inserted)
+            {
+                return err(inserted.unwrap_err());
+            }
+        }
+        else
+        {
+            return err(kv.unwrap_err());
+        }
+
+        // comment lines are skipped by the above function call.
+        // However, since the `skip_line` requires at least 1 newline, it fails
+        // if the file ends with ws and/or comment without newline.
+        // `skip_line` matches `ws? + comment? + newline`, not `ws` or `comment`
+        // itself. To skip the last ws and/or comment, call lexers.
+        // It does not matter if these fails, so the return value is discarded.
+        lex_ws::invoke(loc);
+        lex_comment::invoke(loc);
+
+        // skip_line is (whitespace? comment? newline)_{1,}. multiple empty lines
+        // and comments after the last key-value pairs are allowed.
+        const auto newline = skip_line::invoke(loc);
+        if(!newline && loc.iter() != loc.end())
+        {
+            const auto before2 = loc.iter();
+            lex_ws::invoke(loc); // skip whitespace
+            const auto msg = format_underline("toml::parse_table: "
+                "invalid line format", {{source_location(loc), concat_to_string(
+                "expected newline, but got '", show_char(*loc.iter()), "'.")}});
+            loc.reset(before2);
+            return err(msg);
+        }
+
+        // the skip_lines only matches with lines that includes newline.
+        // to skip the last line that includes comment and/or whitespace
+        // but no newline, call them one more time.
+        lex_ws::invoke(loc);
+        lex_comment::invoke(loc);
+    }
+    return ok(tab);
+}
+
+template<typename Value>
+result<Value, std::string> parse_toml_file(location& loc)
+{
+    using value_type = Value;
+    using table_type = typename value_type::table_type;
+
+    const auto first = loc.iter();
+    if(first == loc.end())
+    {
+        // For empty files, return an empty table with an empty region (zero-length).
+        // Without the region, error messages would miss the filename.
+        return ok(value_type(table_type{}, region(loc, first, first), {}));
+    }
+
+    // put the first line as a region of a file
+    // Here first != loc.end(), so taking std::next is okay
+    const region file(loc, first, std::next(loc.iter()));
+
+    // The first successive comments that are separated from the first value
+    // by an empty line are for a file itself.
+    // ```toml
+    // # this is a comment for a file.
+    //
+    // key = "the first value"
+    // ```
+    // ```toml
+    // # this is a comment for "the first value".
+    // key = "the first value"
+    // ```
+    std::vector<std::string> comments;
+    using lex_first_comments = sequence<
+        repeat<sequence<maybe<lex_ws>, lex_comment, lex_newline>, at_least<1>>,
+        sequence<maybe<lex_ws>, lex_newline>
+        >;
+    if(const auto token = lex_first_comments::invoke(loc))
+    {
+        location inner_loc(loc.name(), token.unwrap().str());
+        while(inner_loc.iter() != inner_loc.end())
+        {
+            maybe<lex_ws>::invoke(inner_loc); // remove ws if exists
+            if(lex_newline::invoke(inner_loc))
+            {
+                assert(inner_loc.iter() == inner_loc.end());
+                break; // empty line found.
+            }
+            auto com = lex_comment::invoke(inner_loc).unwrap().str();
+            com.erase(com.begin()); // remove # sign
+            comments.push_back(std::move(com));
+            lex_newline::invoke(inner_loc);
+        }
+    }
+
+    table_type data;
+    // root object is also a table, but without [tablename]
+    if(const auto tab = parse_ml_table<value_type>(loc))
+    {
+        data = std::move(tab.unwrap());
+    }
+    else // failed (empty table is regarded as success in parse_ml_table)
+    {
+        return err(tab.unwrap_err());
+    }
+    while(loc.iter() != loc.end())
+    {
+        // here, the region of [table] is regarded as the table-key because
+        // the table body is normally too big and it is not so informative
+        // if the first key-value pair of the table is shown in the error
+        // message.
+        if(const auto tabkey = parse_array_table_key(loc))
+        {
+            const auto tab = parse_ml_table<value_type>(loc);
+            if(!tab){return err(tab.unwrap_err());}
+
+            const auto& tk   = tabkey.unwrap();
+            const auto& keys = tk.first;
+            const auto& reg  = tk.second;
+
+            const auto inserted = insert_nested_key(data,
+                    value_type(tab.unwrap(), reg, reg.comments()),
+                    keys.begin(), keys.end(), reg,
+                    /*is_array_of_table=*/ true);
+            if(!inserted) {return err(inserted.unwrap_err());}
+
+            continue;
+        }
+        if(const auto tabkey = parse_table_key(loc))
+        {
+            const auto tab = parse_ml_table<value_type>(loc);
+            if(!tab){return err(tab.unwrap_err());}
+
+            const auto& tk   = tabkey.unwrap();
+            const auto& keys = tk.first;
+            const auto& reg  = tk.second;
+
+            const auto inserted = insert_nested_key(data,
+                value_type(tab.unwrap(), reg, reg.comments()),
+                keys.begin(), keys.end(), reg);
+            if(!inserted) {return err(inserted.unwrap_err());}
+
+            continue;
+        }
+        return err(format_underline("toml::parse_toml_file: "
+            "unknown line appeared", {{source_location(loc), "unknown format"}}));
+    }
+
+    return ok(Value(std::move(data), file, comments));
+}
+
+} // detail
+
+template<typename                     Comment = TOML11_DEFAULT_COMMENT_STRATEGY,
+         template<typename ...> class Table   = std::unordered_map,
+         template<typename ...> class Array   = std::vector>
+basic_value<Comment, Table, Array>
+parse(std::istream& is, const std::string& fname = "unknown file")
+{
+    using value_type = basic_value<Comment, Table, Array>;
+
+    const auto beg = is.tellg();
+    is.seekg(0, std::ios::end);
+    const auto end = is.tellg();
+    const auto fsize = end - beg;
+    is.seekg(beg);
+
+    // read whole file as a sequence of char
+    assert(fsize >= 0);
+    std::vector<char> letters(static_cast<std::size_t>(fsize));
+    is.read(letters.data(), fsize);
+
+    // append LF.
+    // Although TOML does not require LF at the EOF, to make parsing logic
+    // simpler, we "normalize" the content by adding LF if it does not exist.
+    // It also checks if the last char is CR, to avoid changing the meaning.
+    // This is not the *best* way to deal with the last character, but is a
+    // simple and quick fix.
+    if(!letters.empty() && letters.back() != '\n' && letters.back() != '\r')
+    {
+        letters.push_back('\n');
+    }
+
+    detail::location loc(std::move(fname), std::move(letters));
+
+    // skip BOM if exists.
+    // XXX component of BOM (like 0xEF) exceeds the representable range of
+    // signed char, so on some (actually, most) of the environment, these cannot
+    // be compared to char. However, since we are always out of luck, we need to
+    // check our chars are equivalent to BOM. To do this, first we need to
+    // convert char to unsigned char to guarantee the comparability.
+    if(loc.source()->size() >= 3)
+    {
+        std::array<unsigned char, 3> BOM;
+        std::memcpy(BOM.data(), loc.source()->data(), 3);
+        if(BOM[0] == 0xEF && BOM[1] == 0xBB && BOM[2] == 0xBF)
+        {
+            loc.advance(3); // BOM found. skip.
+        }
+    }
+
+    const auto data = detail::parse_toml_file<value_type>(loc);
+    if(!data)
+    {
+        throw syntax_error(data.unwrap_err(), source_location(loc));
+    }
+    return data.unwrap();
+}
+
+template<typename                     Comment = TOML11_DEFAULT_COMMENT_STRATEGY,
+         template<typename ...> class Table   = std::unordered_map,
+         template<typename ...> class Array   = std::vector>
+basic_value<Comment, Table, Array> parse(const std::string& fname)
+{
+    std::ifstream ifs(fname.c_str(), std::ios_base::binary);
+    if(!ifs.good())
+    {
+        throw std::runtime_error("toml::parse: file open error -> " + fname);
+    }
+    return parse<Comment, Table, Array>(ifs, fname);
+}
+
+#ifdef TOML11_HAS_STD_FILESYSTEM
+// This function just forwards `parse("filename.toml")` to std::string version
+// to avoid the ambiguity in overload resolution.
+//
+// Both std::string and std::filesystem::path are convertible from const char*.
+// Without this, both parse(std::string) and parse(std::filesystem::path)
+// matches to parse("filename.toml"). This breaks the existing code.
+//
+// This function exactly matches to the invocation with c-string.
+// So this function is preferred than others and the ambiguity disappears.
+template<typename                     Comment = TOML11_DEFAULT_COMMENT_STRATEGY,
+         template<typename ...> class Table   = std::unordered_map,
+         template<typename ...> class Array   = std::vector>
+basic_value<Comment, Table, Array> parse(const char* fname)
+{
+    return parse<Comment, Table, Array>(std::string(fname));
+}
+
+template<typename                     Comment = TOML11_DEFAULT_COMMENT_STRATEGY,
+         template<typename ...> class Table   = std::unordered_map,
+         template<typename ...> class Array   = std::vector>
+basic_value<Comment, Table, Array> parse(const std::filesystem::path& fpath)
+{
+    std::ifstream ifs(fpath, std::ios_base::binary);
+    if(!ifs.good())
+    {
+        throw std::runtime_error("toml::parse: file open error -> " +
+                                 fpath.string());
+    }
+    return parse<Comment, Table, Array>(ifs, fpath.string());
+}
+#endif // TOML11_HAS_STD_FILESYSTEM
+
+} // toml
+#endif// TOML11_PARSER_HPP
diff --git a/src/toml11/toml/region.hpp b/src/toml11/toml/region.hpp
new file mode 100644
index 000000000..2e01e51d0
--- /dev/null
+++ b/src/toml11/toml/region.hpp
@@ -0,0 +1,417 @@
+//     Copyright Toru Niina 2017.
+// Distributed under the MIT License.
+#ifndef TOML11_REGION_HPP
+#define TOML11_REGION_HPP
+#include <memory>
+#include <vector>
+#include <algorithm>
+#include <initializer_list>
+#include <iterator>
+#include <iomanip>
+#include <cassert>
+#include "color.hpp"
+
+namespace toml
+{
+namespace detail
+{
+
+// helper function to avoid std::string(0, 'c') or std::string(iter, iter)
+template<typename Iterator>
+std::string make_string(Iterator first, Iterator last)
+{
+    if(first == last) {return "";}
+    return std::string(first, last);
+}
+inline std::string make_string(std::size_t len, char c)
+{
+    if(len == 0) {return "";}
+    return std::string(len, c);
+}
+
+// region_base is a base class of location and region that are defined below.
+// it will be used to generate better error messages.
+struct region_base
+{
+    region_base() = default;
+    virtual ~region_base() = default;
+    region_base(const region_base&) = default;
+    region_base(region_base&&     ) = default;
+    region_base& operator=(const region_base&) = default;
+    region_base& operator=(region_base&&     ) = default;
+
+    virtual bool is_ok()           const noexcept {return false;}
+    virtual char front()           const noexcept {return '\0';}
+
+    virtual std::string str()      const {return std::string("unknown region");}
+    virtual std::string name()     const {return std::string("unknown file");}
+    virtual std::string line()     const {return std::string("unknown line");}
+    virtual std::string line_num() const {return std::string("?");}
+
+    // length of the region
+    virtual std::size_t size()     const noexcept {return 0;}
+    // number of characters in the line before the region
+    virtual std::size_t before()   const noexcept {return 0;}
+    // number of characters in the line after the region
+    virtual std::size_t after()    const noexcept {return 0;}
+
+    virtual std::vector<std::string> comments() const {return {};}
+    // ```toml
+    // # comment_before
+    // key = "value" # comment_inline
+    // ```
+};
+
+// location represents a position in a container, which contains a file content.
+// it can be considered as a region that contains only one character.
+//
+// it contains pointer to the file content and iterator that points the current
+// location.
+struct location final : public region_base
+{
+    using const_iterator  = typename std::vector<char>::const_iterator;
+    using difference_type = typename const_iterator::difference_type;
+    using source_ptr      = std::shared_ptr<const std::vector<char>>;
+
+    location(std::string source_name, std::vector<char> cont)
+      : source_(std::make_shared<std::vector<char>>(std::move(cont))),
+        line_number_(1), source_name_(std::move(source_name)), iter_(source_->cbegin())
+    {}
+    location(std::string source_name, const std::string& cont)
+      : source_(std::make_shared<std::vector<char>>(cont.begin(), cont.end())),
+        line_number_(1), source_name_(std::move(source_name)), iter_(source_->cbegin())
+    {}
+
+    location(const location&) = default;
+    location(location&&)      = default;
+    location& operator=(const location&) = default;
+    location& operator=(location&&)      = default;
+    ~location() = default;
+
+    bool is_ok() const noexcept override {return static_cast<bool>(source_);}
+    char front() const noexcept override {return *iter_;}
+
+    // this const prohibits codes like `++(loc.iter())`.
+    const const_iterator iter()  const noexcept {return iter_;}
+
+    const_iterator begin() const noexcept {return source_->cbegin();}
+    const_iterator end()   const noexcept {return source_->cend();}
+
+    // XXX `location::line_num()` used to be implemented using `std::count` to
+    // count a number of '\n'. But with a long toml file (typically, 10k lines),
+    // it becomes intolerably slow because each time it generates error messages,
+    // it counts '\n' from thousands of characters. To workaround it, I decided
+    // to introduce `location::line_number_` member variable and synchronize it
+    // to the location changes the point to look. So an overload of `iter()`
+    // which returns mutable reference is removed and `advance()`, `retrace()`
+    // and `reset()` is added.
+    void advance(difference_type n = 1) noexcept
+    {
+        this->line_number_ += static_cast<std::size_t>(
+                std::count(this->iter_, std::next(this->iter_, n), '\n'));
+        this->iter_ += n;
+        return;
+    }
+    void retrace(difference_type n = 1) noexcept
+    {
+        this->line_number_ -= static_cast<std::size_t>(
+                std::count(std::prev(this->iter_, n), this->iter_, '\n'));
+        this->iter_ -= n;
+        return;
+    }
+    void reset(const_iterator rollback) noexcept
+    {
+        // since c++11, std::distance works in both ways for random-access
+        // iterators and returns a negative value if `first > last`.
+        if(0 <= std::distance(rollback, this->iter_)) // rollback < iter
+        {
+            this->line_number_ -= static_cast<std::size_t>(
+                    std::count(rollback, this->iter_, '\n'));
+        }
+        else // iter < rollback [[unlikely]]
+        {
+            this->line_number_ += static_cast<std::size_t>(
+                    std::count(this->iter_, rollback, '\n'));
+        }
+        this->iter_ = rollback;
+        return;
+    }
+
+    std::string str()  const override {return make_string(1, *this->iter());}
+    std::string name() const override {return source_name_;}
+
+    std::string line_num() const override
+    {
+        return std::to_string(this->line_number_);
+    }
+
+    std::string line() const override
+    {
+        return make_string(this->line_begin(), this->line_end());
+    }
+
+    const_iterator line_begin() const noexcept
+    {
+        using reverse_iterator = std::reverse_iterator<const_iterator>;
+        return std::find(reverse_iterator(this->iter()),
+                         reverse_iterator(this->begin()), '\n').base();
+    }
+    const_iterator line_end() const noexcept
+    {
+        return std::find(this->iter(), this->end(), '\n');
+    }
+
+    // location is always points a character. so the size is 1.
+    std::size_t size() const noexcept override
+    {
+        return 1u;
+    }
+    std::size_t before() const noexcept override
+    {
+        const auto sz = std::distance(this->line_begin(), this->iter());
+        assert(sz >= 0);
+        return static_cast<std::size_t>(sz);
+    }
+    std::size_t after() const noexcept override
+    {
+        const auto sz = std::distance(this->iter(), this->line_end());
+        assert(sz >= 0);
+        return static_cast<std::size_t>(sz);
+    }
+
+    source_ptr const& source() const& noexcept {return source_;}
+    source_ptr&&      source() &&     noexcept {return std::move(source_);}
+
+  private:
+
+    source_ptr     source_;
+    std::size_t    line_number_;
+    std::string    source_name_;
+    const_iterator iter_;
+};
+
+// region represents a range in a container, which contains a file content.
+//
+// it contains pointer to the file content and iterator that points the first
+// and last location.
+struct region final : public region_base
+{
+    using const_iterator = typename std::vector<char>::const_iterator;
+    using source_ptr     = std::shared_ptr<const std::vector<char>>;
+
+    // delete default constructor. source_ never be null.
+    region() = delete;
+
+    explicit region(const location& loc)
+      : source_(loc.source()), source_name_(loc.name()),
+        first_(loc.iter()), last_(loc.iter())
+    {}
+    explicit region(location&& loc)
+      : source_(loc.source()), source_name_(loc.name()),
+        first_(loc.iter()), last_(loc.iter())
+    {}
+
+    region(const location& loc, const_iterator f, const_iterator l)
+      : source_(loc.source()), source_name_(loc.name()), first_(f), last_(l)
+    {}
+    region(location&& loc, const_iterator f, const_iterator l)
+      : source_(loc.source()), source_name_(loc.name()), first_(f), last_(l)
+    {}
+
+    region(const region&) = default;
+    region(region&&)      = default;
+    region& operator=(const region&) = default;
+    region& operator=(region&&)      = default;
+    ~region() = default;
+
+    region& operator+=(const region& other)
+    {
+        // different regions cannot be concatenated
+        assert(this->begin() == other.begin() && this->end() == other.end() &&
+               this->last_   == other.first_);
+
+        this->last_ = other.last_;
+        return *this;
+    }
+
+    bool is_ok() const noexcept override {return static_cast<bool>(source_);}
+    char front() const noexcept override {return *first_;}
+
+    std::string str()  const override {return make_string(first_, last_);}
+    std::string line() const override
+    {
+        if(this->contain_newline())
+        {
+            return make_string(this->line_begin(),
+                    std::find(this->line_begin(), this->last(), '\n'));
+        }
+        return make_string(this->line_begin(), this->line_end());
+    }
+    std::string line_num() const override
+    {
+        return std::to_string(1 + std::count(this->begin(), this->first(), '\n'));
+    }
+
+    std::size_t size() const noexcept override
+    {
+        const auto sz = std::distance(first_, last_);
+        assert(sz >= 0);
+        return static_cast<std::size_t>(sz);
+    }
+    std::size_t before() const noexcept override
+    {
+        const auto sz = std::distance(this->line_begin(), this->first());
+        assert(sz >= 0);
+        return static_cast<std::size_t>(sz);
+    }
+    std::size_t after() const noexcept override
+    {
+        const auto sz = std::distance(this->last(), this->line_end());
+        assert(sz >= 0);
+        return static_cast<std::size_t>(sz);
+    }
+
+    bool contain_newline() const noexcept
+    {
+        return std::find(this->first(), this->last(), '\n') != this->last();
+    }
+
+    const_iterator line_begin() const noexcept
+    {
+        using reverse_iterator = std::reverse_iterator<const_iterator>;
+        return std::find(reverse_iterator(this->first()),
+                         reverse_iterator(this->begin()), '\n').base();
+    }
+    const_iterator line_end() const noexcept
+    {
+        return std::find(this->last(), this->end(), '\n');
+    }
+
+    const_iterator begin() const noexcept {return source_->cbegin();}
+    const_iterator end()   const noexcept {return source_->cend();}
+    const_iterator first() const noexcept {return first_;}
+    const_iterator last()  const noexcept {return last_;}
+
+    source_ptr const& source() const& noexcept {return source_;}
+    source_ptr&&      source() &&     noexcept {return std::move(source_);}
+
+    std::string name() const override {return source_name_;}
+
+    std::vector<std::string> comments() const override
+    {
+        // assuming the current region (`*this`) points a value.
+        // ```toml
+        // a = "value"
+        //     ^^^^^^^- this region
+        // ```
+        using rev_iter = std::reverse_iterator<const_iterator>;
+
+        std::vector<std::string> com{};
+        {
+            // find comments just before the current region.
+            // ```toml
+            // # this should be collected.
+            // # this also.
+            // a = value # not this.
+            // ```
+
+            // # this is a comment for `a`, not array elements.
+            // a = [1, 2, 3, 4, 5]
+            if(this->first() == std::find_if(this->line_begin(), this->first(),
+                [](const char c) noexcept -> bool {return c == '[' || c == '{';}))
+            {
+                auto iter = this->line_begin(); // points the first character
+                while(iter != this->begin())
+                {
+                    iter = std::prev(iter);
+
+                    // range [line_start, iter) represents the previous line
+                    const auto line_start   = std::find(
+                            rev_iter(iter), rev_iter(this->begin()), '\n').base();
+                    const auto comment_found = std::find(line_start, iter, '#');
+                    if(comment_found == iter)
+                    {
+                        break; // comment not found.
+                    }
+
+                    // exclude the following case.
+                    // > a = "foo" # comment // <-- this is not a comment for b but a.
+                    // > b = "current value"
+                    if(std::all_of(line_start, comment_found,
+                            [](const char c) noexcept -> bool {
+                                return c == ' ' || c == '\t';
+                            }))
+                    {
+                        // unwrap the first '#' by std::next.
+                        auto s = make_string(std::next(comment_found), iter);
+                        if(!s.empty() && s.back() == '\r') {s.pop_back();}
+                        com.push_back(std::move(s));
+                    }
+                    else
+                    {
+                        break;
+                    }
+                    iter = line_start;
+                }
+            }
+        }
+
+        if(com.size() > 1)
+        {
+            std::reverse(com.begin(), com.end());
+        }
+
+        {
+            // find comments just after the current region.
+            // ```toml
+            // # not this.
+            // a = value # this one.
+            // a = [ # not this (technically difficult)
+            //
+            // ] # and this.
+            // ```
+            // The reason why it's difficult is that it requires parsing in the
+            // following case.
+            // ```toml
+            // a = [ 10 # this comment is for `10`. not for `a` but `a[0]`.
+            // # ...
+            // ] # this is apparently a comment for a.
+            //
+            // b = [
+            // 3.14 ] # there is no way to add a comment to `3.14` currently.
+            //
+            // c = [
+            //   3.14 # do this if you need a comment here.
+            // ]
+            // ```
+            const auto comment_found =
+                std::find(this->last(), this->line_end(), '#');
+            if(comment_found != this->line_end()) // '#' found
+            {
+                // table = {key = "value"} # what is this for?
+                // the above comment is not for "value", but {key="value"}.
+                if(comment_found == std::find_if(this->last(), comment_found,
+                    [](const char c) noexcept -> bool {
+                        return !(c == ' ' || c == '\t' || c == ',');
+                    }))
+                {
+                    // unwrap the first '#' by std::next.
+                    auto s = make_string(std::next(comment_found), this->line_end());
+                    if(!s.empty() && s.back() == '\r') {s.pop_back();}
+                    com.push_back(std::move(s));
+                }
+            }
+        }
+        return com;
+    }
+
+  private:
+
+    source_ptr     source_;
+    std::string    source_name_;
+    const_iterator first_, last_;
+};
+
+} // detail
+} // toml
+#endif// TOML11_REGION_H
diff --git a/src/toml11/toml/result.hpp b/src/toml11/toml/result.hpp
new file mode 100644
index 000000000..77cd46c64
--- /dev/null
+++ b/src/toml11/toml/result.hpp
@@ -0,0 +1,717 @@
+//     Copyright Toru Niina 2017.
+// Distributed under the MIT License.
+#ifndef TOML11_RESULT_HPP
+#define TOML11_RESULT_HPP
+#include "traits.hpp"
+#include <type_traits>
+#include <stdexcept>
+#include <utility>
+#include <new>
+#include <string>
+#include <sstream>
+#include <cassert>
+
+namespace toml
+{
+
+template<typename T>
+struct success
+{
+    using value_type = T;
+    value_type value;
+
+    explicit success(const value_type& v)
+        noexcept(std::is_nothrow_copy_constructible<value_type>::value)
+        : value(v)
+    {}
+    explicit success(value_type&& v)
+        noexcept(std::is_nothrow_move_constructible<value_type>::value)
+        : value(std::move(v))
+    {}
+
+    template<typename U>
+    explicit success(U&& v): value(std::forward<U>(v)) {}
+
+    template<typename U>
+    explicit success(const success<U>& v): value(v.value) {}
+    template<typename U>
+    explicit success(success<U>&& v): value(std::move(v.value)) {}
+
+    ~success() = default;
+    success(const success&) = default;
+    success(success&&)      = default;
+    success& operator=(const success&) = default;
+    success& operator=(success&&)      = default;
+};
+
+template<typename T>
+struct failure
+{
+    using value_type = T;
+    value_type value;
+
+    explicit failure(const value_type& v)
+        noexcept(std::is_nothrow_copy_constructible<value_type>::value)
+        : value(v)
+    {}
+    explicit failure(value_type&& v)
+        noexcept(std::is_nothrow_move_constructible<value_type>::value)
+        : value(std::move(v))
+    {}
+
+    template<typename U>
+    explicit failure(U&& v): value(std::forward<U>(v)) {}
+
+    template<typename U>
+    explicit failure(const failure<U>& v): value(v.value) {}
+    template<typename U>
+    explicit failure(failure<U>&& v): value(std::move(v.value)) {}
+
+    ~failure() = default;
+    failure(const failure&) = default;
+    failure(failure&&)      = default;
+    failure& operator=(const failure&) = default;
+    failure& operator=(failure&&)      = default;
+};
+
+template<typename T>
+success<typename std::remove_cv<typename std::remove_reference<T>::type>::type>
+ok(T&& v)
+{
+    return success<
+        typename std::remove_cv<typename std::remove_reference<T>::type>::type
+        >(std::forward<T>(v));
+}
+template<typename T>
+failure<typename std::remove_cv<typename std::remove_reference<T>::type>::type>
+err(T&& v)
+{
+    return failure<
+        typename std::remove_cv<typename std::remove_reference<T>::type>::type
+        >(std::forward<T>(v));
+}
+
+inline success<std::string> ok(const char* literal)
+{
+    return success<std::string>(std::string(literal));
+}
+inline failure<std::string> err(const char* literal)
+{
+    return failure<std::string>(std::string(literal));
+}
+
+
+template<typename T, typename E>
+struct result
+{
+    using value_type = T;
+    using error_type = E;
+    using success_type = success<value_type>;
+    using failure_type = failure<error_type>;
+
+    result(const success_type& s): is_ok_(true)
+    {
+        auto tmp = ::new(std::addressof(this->succ)) success_type(s);
+        assert(tmp == std::addressof(this->succ));
+        (void)tmp;
+    }
+    result(const failure_type& f): is_ok_(false)
+    {
+        auto tmp = ::new(std::addressof(this->fail)) failure_type(f);
+        assert(tmp == std::addressof(this->fail));
+        (void)tmp;
+    }
+    result(success_type&& s): is_ok_(true)
+    {
+        auto tmp = ::new(std::addressof(this->succ)) success_type(std::move(s));
+        assert(tmp == std::addressof(this->succ));
+        (void)tmp;
+    }
+    result(failure_type&& f): is_ok_(false)
+    {
+        auto tmp = ::new(std::addressof(this->fail)) failure_type(std::move(f));
+        assert(tmp == std::addressof(this->fail));
+        (void)tmp;
+    }
+
+    template<typename U>
+    result(const success<U>& s): is_ok_(true)
+    {
+        auto tmp = ::new(std::addressof(this->succ)) success_type(s.value);
+        assert(tmp == std::addressof(this->succ));
+        (void)tmp;
+    }
+    template<typename U>
+    result(const failure<U>& f): is_ok_(false)
+    {
+        auto tmp = ::new(std::addressof(this->fail)) failure_type(f.value);
+        assert(tmp == std::addressof(this->fail));
+        (void)tmp;
+    }
+    template<typename U>
+    result(success<U>&& s): is_ok_(true)
+    {
+        auto tmp = ::new(std::addressof(this->succ)) success_type(std::move(s.value));
+        assert(tmp == std::addressof(this->succ));
+        (void)tmp;
+    }
+    template<typename U>
+    result(failure<U>&& f): is_ok_(false)
+    {
+        auto tmp = ::new(std::addressof(this->fail)) failure_type(std::move(f.value));
+        assert(tmp == std::addressof(this->fail));
+        (void)tmp;
+    }
+
+    result& operator=(const success_type& s)
+    {
+        this->cleanup();
+        this->is_ok_ = true;
+        auto tmp = ::new(std::addressof(this->succ)) success_type(s);
+        assert(tmp == std::addressof(this->succ));
+        (void)tmp;
+        return *this;
+    }
+    result& operator=(const failure_type& f)
+    {
+        this->cleanup();
+        this->is_ok_ = false;
+        auto tmp = ::new(std::addressof(this->fail)) failure_type(f);
+        assert(tmp == std::addressof(this->fail));
+        (void)tmp;
+        return *this;
+    }
+    result& operator=(success_type&& s)
+    {
+        this->cleanup();
+        this->is_ok_ = true;
+        auto tmp = ::new(std::addressof(this->succ)) success_type(std::move(s));
+        assert(tmp == std::addressof(this->succ));
+        (void)tmp;
+        return *this;
+    }
+    result& operator=(failure_type&& f)
+    {
+        this->cleanup();
+        this->is_ok_ = false;
+        auto tmp = ::new(std::addressof(this->fail)) failure_type(std::move(f));
+        assert(tmp == std::addressof(this->fail));
+        (void)tmp;
+        return *this;
+    }
+
+    template<typename U>
+    result& operator=(const success<U>& s)
+    {
+        this->cleanup();
+        this->is_ok_ = true;
+        auto tmp = ::new(std::addressof(this->succ)) success_type(s.value);
+        assert(tmp == std::addressof(this->succ));
+        (void)tmp;
+        return *this;
+    }
+    template<typename U>
+    result& operator=(const failure<U>& f)
+    {
+        this->cleanup();
+        this->is_ok_ = false;
+        auto tmp = ::new(std::addressof(this->fail)) failure_type(f.value);
+        assert(tmp == std::addressof(this->fail));
+        (void)tmp;
+        return *this;
+    }
+    template<typename U>
+    result& operator=(success<U>&& s)
+    {
+        this->cleanup();
+        this->is_ok_ = true;
+        auto tmp = ::new(std::addressof(this->succ)) success_type(std::move(s.value));
+        assert(tmp == std::addressof(this->succ));
+        (void)tmp;
+        return *this;
+    }
+    template<typename U>
+    result& operator=(failure<U>&& f)
+    {
+        this->cleanup();
+        this->is_ok_ = false;
+        auto tmp = ::new(std::addressof(this->fail)) failure_type(std::move(f.value));
+        assert(tmp == std::addressof(this->fail));
+        (void)tmp;
+        return *this;
+    }
+
+    ~result() noexcept {this->cleanup();}
+
+    result(const result& other): is_ok_(other.is_ok())
+    {
+        if(other.is_ok())
+        {
+            auto tmp = ::new(std::addressof(this->succ)) success_type(other.as_ok());
+            assert(tmp == std::addressof(this->succ));
+            (void)tmp;
+        }
+        else
+        {
+            auto tmp = ::new(std::addressof(this->fail)) failure_type(other.as_err());
+            assert(tmp == std::addressof(this->fail));
+            (void)tmp;
+        }
+    }
+    result(result&& other): is_ok_(other.is_ok())
+    {
+        if(other.is_ok())
+        {
+            auto tmp = ::new(std::addressof(this->succ)) success_type(std::move(other.as_ok()));
+            assert(tmp == std::addressof(this->succ));
+            (void)tmp;
+        }
+        else
+        {
+            auto tmp = ::new(std::addressof(this->fail)) failure_type(std::move(other.as_err()));
+            assert(tmp == std::addressof(this->fail));
+            (void)tmp;
+        }
+    }
+
+    template<typename U, typename F>
+    result(const result<U, F>& other): is_ok_(other.is_ok())
+    {
+        if(other.is_ok())
+        {
+            auto tmp = ::new(std::addressof(this->succ)) success_type(other.as_ok());
+            assert(tmp == std::addressof(this->succ));
+            (void)tmp;
+        }
+        else
+        {
+            auto tmp = ::new(std::addressof(this->fail)) failure_type(other.as_err());
+            assert(tmp == std::addressof(this->fail));
+            (void)tmp;
+        }
+    }
+    template<typename U, typename F>
+    result(result<U, F>&& other): is_ok_(other.is_ok())
+    {
+        if(other.is_ok())
+        {
+            auto tmp = ::new(std::addressof(this->succ)) success_type(std::move(other.as_ok()));
+            assert(tmp == std::addressof(this->succ));
+            (void)tmp;
+        }
+        else
+        {
+            auto tmp = ::new(std::addressof(this->fail)) failure_type(std::move(other.as_err()));
+            assert(tmp == std::addressof(this->fail));
+            (void)tmp;
+        }
+    }
+
+    result& operator=(const result& other)
+    {
+        this->cleanup();
+        if(other.is_ok())
+        {
+            auto tmp = ::new(std::addressof(this->succ)) success_type(other.as_ok());
+            assert(tmp == std::addressof(this->succ));
+            (void)tmp;
+        }
+        else
+        {
+            auto tmp = ::new(std::addressof(this->fail)) failure_type(other.as_err());
+            assert(tmp == std::addressof(this->fail));
+            (void)tmp;
+        }
+        is_ok_ = other.is_ok();
+        return *this;
+    }
+    result& operator=(result&& other)
+    {
+        this->cleanup();
+        if(other.is_ok())
+        {
+            auto tmp = ::new(std::addressof(this->succ)) success_type(std::move(other.as_ok()));
+            assert(tmp == std::addressof(this->succ));
+            (void)tmp;
+        }
+        else
+        {
+            auto tmp = ::new(std::addressof(this->fail)) failure_type(std::move(other.as_err()));
+            assert(tmp == std::addressof(this->fail));
+            (void)tmp;
+        }
+        is_ok_ = other.is_ok();
+        return *this;
+    }
+
+    template<typename U, typename F>
+    result& operator=(const result<U, F>& other)
+    {
+        this->cleanup();
+        if(other.is_ok())
+        {
+            auto tmp = ::new(std::addressof(this->succ)) success_type(other.as_ok());
+            assert(tmp == std::addressof(this->succ));
+            (void)tmp;
+        }
+        else
+        {
+            auto tmp = ::new(std::addressof(this->fail)) failure_type(other.as_err());
+            assert(tmp == std::addressof(this->fail));
+            (void)tmp;
+        }
+        is_ok_ = other.is_ok();
+        return *this;
+    }
+    template<typename U, typename F>
+    result& operator=(result<U, F>&& other)
+    {
+        this->cleanup();
+        if(other.is_ok())
+        {
+            auto tmp = ::new(std::addressof(this->succ)) success_type(std::move(other.as_ok()));
+            assert(tmp == std::addressof(this->succ));
+            (void)tmp;
+        }
+        else
+        {
+            auto tmp = ::new(std::addressof(this->fail)) failure_type(std::move(other.as_err()));
+            assert(tmp == std::addressof(this->fail));
+            (void)tmp;
+        }
+        is_ok_ = other.is_ok();
+        return *this;
+    }
+
+    bool is_ok()  const noexcept {return is_ok_;}
+    bool is_err() const noexcept {return !is_ok_;}
+
+    operator bool() const noexcept {return is_ok_;}
+
+    value_type&       unwrap() &
+    {
+        if(is_err())
+        {
+            throw std::runtime_error("toml::result: bad unwrap: " +
+                                     format_error(this->as_err()));
+        }
+        return this->succ.value;
+    }
+    value_type const& unwrap() const&
+    {
+        if(is_err())
+        {
+            throw std::runtime_error("toml::result: bad unwrap: " +
+                                     format_error(this->as_err()));
+        }
+        return this->succ.value;
+    }
+    value_type&&      unwrap() &&
+    {
+        if(is_err())
+        {
+            throw std::runtime_error("toml::result: bad unwrap: " +
+                                     format_error(this->as_err()));
+        }
+        return std::move(this->succ.value);
+    }
+
+    value_type&       unwrap_or(value_type& opt) &
+    {
+        if(is_err()) {return opt;}
+        return this->succ.value;
+    }
+    value_type const& unwrap_or(value_type const& opt) const&
+    {
+        if(is_err()) {return opt;}
+        return this->succ.value;
+    }
+    value_type        unwrap_or(value_type opt) &&
+    {
+        if(is_err()) {return opt;}
+        return this->succ.value;
+    }
+
+    error_type&       unwrap_err() &
+    {
+        if(is_ok()) {throw std::runtime_error("toml::result: bad unwrap_err");}
+        return this->fail.value;
+    }
+    error_type const& unwrap_err() const&
+    {
+        if(is_ok()) {throw std::runtime_error("toml::result: bad unwrap_err");}
+        return this->fail.value;
+    }
+    error_type&&      unwrap_err() &&
+    {
+        if(is_ok()) {throw std::runtime_error("toml::result: bad unwrap_err");}
+        return std::move(this->fail.value);
+    }
+
+    value_type&       as_ok() &      noexcept {return this->succ.value;}
+    value_type const& as_ok() const& noexcept {return this->succ.value;}
+    value_type&&      as_ok() &&     noexcept {return std::move(this->succ.value);}
+
+    error_type&       as_err() &      noexcept {return this->fail.value;}
+    error_type const& as_err() const& noexcept {return this->fail.value;}
+    error_type&&      as_err() &&     noexcept {return std::move(this->fail.value);}
+
+
+    // prerequisities
+    // F: T -> U
+    // retval: result<U, E>
+    template<typename F>
+    result<detail::return_type_of_t<F, value_type&>, error_type>
+    map(F&& f) &
+    {
+        if(this->is_ok()){return ok(f(this->as_ok()));}
+        return err(this->as_err());
+    }
+    template<typename F>
+    result<detail::return_type_of_t<F, value_type const&>, error_type>
+    map(F&& f) const&
+    {
+        if(this->is_ok()){return ok(f(this->as_ok()));}
+        return err(this->as_err());
+    }
+    template<typename F>
+    result<detail::return_type_of_t<F, value_type &&>, error_type>
+    map(F&& f) &&
+    {
+        if(this->is_ok()){return ok(f(std::move(this->as_ok())));}
+        return err(std::move(this->as_err()));
+    }
+
+    // prerequisities
+    // F: E -> F
+    // retval: result<T, F>
+    template<typename F>
+    result<value_type, detail::return_type_of_t<F, error_type&>>
+    map_err(F&& f) &
+    {
+        if(this->is_err()){return err(f(this->as_err()));}
+        return ok(this->as_ok());
+    }
+    template<typename F>
+    result<value_type, detail::return_type_of_t<F, error_type const&>>
+    map_err(F&& f) const&
+    {
+        if(this->is_err()){return err(f(this->as_err()));}
+        return ok(this->as_ok());
+    }
+    template<typename F>
+    result<value_type, detail::return_type_of_t<F, error_type&&>>
+    map_err(F&& f) &&
+    {
+        if(this->is_err()){return err(f(std::move(this->as_err())));}
+        return ok(std::move(this->as_ok()));
+    }
+
+    // prerequisities
+    // F: T -> U
+    // retval: U
+    template<typename F, typename U>
+    detail::return_type_of_t<F, value_type&>
+    map_or_else(F&& f, U&& opt) &
+    {
+        if(this->is_err()){return std::forward<U>(opt);}
+        return f(this->as_ok());
+    }
+    template<typename F, typename U>
+    detail::return_type_of_t<F, value_type const&>
+    map_or_else(F&& f, U&& opt) const&
+    {
+        if(this->is_err()){return std::forward<U>(opt);}
+        return f(this->as_ok());
+    }
+    template<typename F, typename U>
+    detail::return_type_of_t<F, value_type&&>
+    map_or_else(F&& f, U&& opt) &&
+    {
+        if(this->is_err()){return std::forward<U>(opt);}
+        return f(std::move(this->as_ok()));
+    }
+
+    // prerequisities
+    // F: E -> U
+    // retval: U
+    template<typename F, typename U>
+    detail::return_type_of_t<F, error_type&>
+    map_err_or_else(F&& f, U&& opt) &
+    {
+        if(this->is_ok()){return std::forward<U>(opt);}
+        return f(this->as_err());
+    }
+    template<typename F, typename U>
+    detail::return_type_of_t<F, error_type const&>
+    map_err_or_else(F&& f, U&& opt) const&
+    {
+        if(this->is_ok()){return std::forward<U>(opt);}
+        return f(this->as_err());
+    }
+    template<typename F, typename U>
+    detail::return_type_of_t<F, error_type&&>
+    map_err_or_else(F&& f, U&& opt) &&
+    {
+        if(this->is_ok()){return std::forward<U>(opt);}
+        return f(std::move(this->as_err()));
+    }
+
+    // prerequisities:
+    // F: func T -> U
+    // toml::err(error_type) should be convertible to U.
+    // normally, type U is another result<S, F> and E is convertible to F
+    template<typename F>
+    detail::return_type_of_t<F, value_type&>
+    and_then(F&& f) &
+    {
+        if(this->is_ok()){return f(this->as_ok());}
+        return err(this->as_err());
+    }
+    template<typename F>
+    detail::return_type_of_t<F, value_type const&>
+    and_then(F&& f) const&
+    {
+        if(this->is_ok()){return f(this->as_ok());}
+        return err(this->as_err());
+    }
+    template<typename F>
+    detail::return_type_of_t<F, value_type&&>
+    and_then(F&& f) &&
+    {
+        if(this->is_ok()){return f(std::move(this->as_ok()));}
+        return err(std::move(this->as_err()));
+    }
+
+    // prerequisities:
+    // F: func E -> U
+    // toml::ok(value_type) should be convertible to U.
+    // normally, type U is another result<S, F> and T is convertible to S
+    template<typename F>
+    detail::return_type_of_t<F, error_type&>
+    or_else(F&& f) &
+    {
+        if(this->is_err()){return f(this->as_err());}
+        return ok(this->as_ok());
+    }
+    template<typename F>
+    detail::return_type_of_t<F, error_type const&>
+    or_else(F&& f) const&
+    {
+        if(this->is_err()){return f(this->as_err());}
+        return ok(this->as_ok());
+    }
+    template<typename F>
+    detail::return_type_of_t<F, error_type&&>
+    or_else(F&& f) &&
+    {
+        if(this->is_err()){return f(std::move(this->as_err()));}
+        return ok(std::move(this->as_ok()));
+    }
+
+    // if *this is error, returns *this. otherwise, returns other.
+    result and_other(const result& other) const&
+    {
+        return this->is_err() ? *this : other;
+    }
+    result and_other(result&& other) &&
+    {
+        return this->is_err() ? std::move(*this) : std::move(other);
+    }
+
+    // if *this is okay, returns *this. otherwise, returns other.
+    result or_other(const result& other) const&
+    {
+        return this->is_ok() ? *this : other;
+    }
+    result or_other(result&& other) &&
+    {
+        return this->is_ok() ? std::move(*this) : std::move(other);
+    }
+
+    void swap(result<T, E>& other)
+    {
+        result<T, E> tmp(std::move(*this));
+        *this = std::move(other);
+        other = std::move(tmp);
+        return ;
+    }
+
+  private:
+
+    static std::string format_error(std::exception const& excpt)
+    {
+        return std::string(excpt.what());
+    }
+    template<typename U, typename std::enable_if<!std::is_base_of<
+        std::exception, U>::value, std::nullptr_t>::type = nullptr>
+    static std::string format_error(U const& others)
+    {
+        std::ostringstream oss; oss << others;
+        return oss.str();
+    }
+
+    void cleanup() noexcept
+    {
+        if(this->is_ok_) {this->succ.~success_type();}
+        else             {this->fail.~failure_type();}
+        return;
+    }
+
+  private:
+
+    bool      is_ok_;
+    union
+    {
+        success_type succ;
+        failure_type fail;
+    };
+};
+
+template<typename T, typename E>
+void swap(result<T, E>& lhs, result<T, E>& rhs)
+{
+    lhs.swap(rhs);
+    return;
+}
+
+// this might be confusing because it eagerly evaluated, while in the other
+// cases operator && and || are short-circuited.
+//
+// template<typename T, typename E>
+// inline result<T, E>
+// operator&&(const result<T, E>& lhs, const result<T, E>& rhs) noexcept
+// {
+//     return lhs.is_ok() ? rhs : lhs;
+// }
+//
+// template<typename T, typename E>
+// inline result<T, E>
+// operator||(const result<T, E>& lhs, const result<T, E>& rhs) noexcept
+// {
+//     return lhs.is_ok() ? lhs : rhs;
+// }
+
+// ----------------------------------------------------------------------------
+// re-use result<T, E> as a optional<T> with none_t
+
+namespace detail
+{
+struct none_t {};
+inline bool operator==(const none_t&, const none_t&) noexcept {return true;}
+inline bool operator!=(const none_t&, const none_t&) noexcept {return false;}
+inline bool operator< (const none_t&, const none_t&) noexcept {return false;}
+inline bool operator<=(const none_t&, const none_t&) noexcept {return true;}
+inline bool operator> (const none_t&, const none_t&) noexcept {return false;}
+inline bool operator>=(const none_t&, const none_t&) noexcept {return true;}
+template<typename charT, typename traitsT>
+std::basic_ostream<charT, traitsT>&
+operator<<(std::basic_ostream<charT, traitsT>& os, const none_t&)
+{
+    os << "none";
+    return os;
+}
+inline failure<none_t> none() noexcept {return failure<none_t>{none_t{}};}
+} // detail
+} // toml11
+#endif// TOML11_RESULT_H
diff --git a/src/toml11/toml/serializer.hpp b/src/toml11/toml/serializer.hpp
new file mode 100644
index 000000000..88ae775a8
--- /dev/null
+++ b/src/toml11/toml/serializer.hpp
@@ -0,0 +1,922 @@
+//     Copyright Toru Niina 2019.
+// Distributed under the MIT License.
+#ifndef TOML11_SERIALIZER_HPP
+#define TOML11_SERIALIZER_HPP
+#include <cmath>
+#include <cstdio>
+
+#include <limits>
+
+#include "lexer.hpp"
+#include "value.hpp"
+
+namespace toml
+{
+
+// This function serialize a key. It checks a string is a bare key and
+// escapes special characters if the string is not compatible to a bare key.
+// ```cpp
+// std::string k("non.bare.key"); // the key itself includes `.`s.
+// std::string formatted = toml::format_key(k);
+// assert(formatted == "\"non.bare.key\"");
+// ```
+//
+// This function is exposed to make it easy to write a user-defined serializer.
+// Since toml restricts characters available in a bare key, generally a string
+// should be escaped. But checking whether a string needs to be surrounded by
+// a `"` and escaping some special character is boring.
+template<typename charT, typename traits, typename Alloc>
+std::basic_string<charT, traits, Alloc>
+format_key(const std::basic_string<charT, traits, Alloc>& k)
+{
+    if(k.empty())
+    {
+        return std::string("\"\"");
+    }
+
+    // check the key can be a bare (unquoted) key
+    detail::location loc(k, std::vector<char>(k.begin(), k.end()));
+    detail::lex_unquoted_key::invoke(loc);
+    if(loc.iter() == loc.end())
+    {
+        return k; // all the tokens are consumed. the key is unquoted-key.
+    }
+
+    //if it includes special characters, then format it in a "quoted" key.
+    std::basic_string<charT, traits, Alloc> serialized("\"");
+    for(const char c : k)
+    {
+        switch(c)
+        {
+            case '\\': {serialized += "\\\\"; break;}
+            case '\"': {serialized += "\\\""; break;}
+            case '\b': {serialized += "\\b";  break;}
+            case '\t': {serialized += "\\t";  break;}
+            case '\f': {serialized += "\\f";  break;}
+            case '\n': {serialized += "\\n";  break;}
+            case '\r': {serialized += "\\r";  break;}
+            default  : {serialized += c;      break;}
+        }
+    }
+    serialized += "\"";
+    return serialized;
+}
+
+template<typename charT, typename traits, typename Alloc>
+std::basic_string<charT, traits, Alloc>
+format_keys(const std::vector<std::basic_string<charT, traits, Alloc>>& keys)
+{
+    if(keys.empty())
+    {
+        return std::string("\"\"");
+    }
+
+    std::basic_string<charT, traits, Alloc> serialized;
+    for(const auto& ky : keys)
+    {
+        serialized += format_key(ky);
+        serialized += charT('.');
+    }
+    serialized.pop_back(); // remove the last dot '.'
+    return serialized;
+}
+
+template<typename Value>
+struct serializer
+{
+    static_assert(detail::is_basic_value<Value>::value,
+                  "toml::serializer is for toml::value and its variants, "
+                  "toml::basic_value<...>.");
+
+    using value_type           = Value;
+    using key_type             = typename value_type::key_type            ;
+    using comment_type         = typename value_type::comment_type        ;
+    using boolean_type         = typename value_type::boolean_type        ;
+    using integer_type         = typename value_type::integer_type        ;
+    using floating_type        = typename value_type::floating_type       ;
+    using string_type          = typename value_type::string_type         ;
+    using local_time_type      = typename value_type::local_time_type     ;
+    using local_date_type      = typename value_type::local_date_type     ;
+    using local_datetime_type  = typename value_type::local_datetime_type ;
+    using offset_datetime_type = typename value_type::offset_datetime_type;
+    using array_type           = typename value_type::array_type          ;
+    using table_type           = typename value_type::table_type          ;
+
+    serializer(const std::size_t w              = 80u,
+               const int         float_prec     = std::numeric_limits<toml::floating>::max_digits10,
+               const bool        can_be_inlined = false,
+               const bool        no_comment     = false,
+               std::vector<toml::key> ks        = {},
+               const bool     value_has_comment = false)
+        : can_be_inlined_(can_be_inlined), no_comment_(no_comment),
+          value_has_comment_(value_has_comment && !no_comment),
+          float_prec_(float_prec), width_(w), keys_(std::move(ks))
+    {}
+    ~serializer() = default;
+
+    std::string operator()(const boolean_type& b) const
+    {
+        return b ? "true" : "false";
+    }
+    std::string operator()(const integer_type i) const
+    {
+        return std::to_string(i);
+    }
+    std::string operator()(const floating_type f) const
+    {
+        if(std::isnan(f))
+        {
+            if(std::signbit(f))
+            {
+                return std::string("-nan");
+            }
+            else
+            {
+                return std::string("nan");
+            }
+        }
+        else if(!std::isfinite(f))
+        {
+            if(std::signbit(f))
+            {
+                return std::string("-inf");
+            }
+            else
+            {
+                return std::string("inf");
+            }
+        }
+
+        const auto fmt = "%.*g";
+        const auto bsz = std::snprintf(nullptr, 0, fmt, this->float_prec_, f);
+        // +1 for null character(\0)
+        std::vector<char> buf(static_cast<std::size_t>(bsz + 1), '\0');
+        std::snprintf(buf.data(), buf.size(), fmt, this->float_prec_, f);
+
+        std::string token(buf.begin(), std::prev(buf.end()));
+        if(!token.empty() && token.back() == '.') // 1. => 1.0
+        {
+            token += '0';
+        }
+
+        const auto e = std::find_if(
+            token.cbegin(), token.cend(), [](const char c) noexcept -> bool {
+                return c == 'e' || c == 'E';
+            });
+        const auto has_exponent = (token.cend() != e);
+        const auto has_fraction = (token.cend() != std::find(
+            token.cbegin(), token.cend(), '.'));
+
+        if(!has_exponent && !has_fraction)
+        {
+            // the resulting value does not have any float specific part!
+            token += ".0";
+        }
+        return token;
+    }
+    std::string operator()(const string_type& s) const
+    {
+        if(s.kind == string_t::basic)
+        {
+            if((std::find(s.str.cbegin(), s.str.cend(), '\n') != s.str.cend() ||
+                std::find(s.str.cbegin(), s.str.cend(), '\"') != s.str.cend()) &&
+               this->width_ != (std::numeric_limits<std::size_t>::max)())
+            {
+                // if linefeed or double-quote is contained,
+                // make it multiline basic string.
+                const auto escaped = this->escape_ml_basic_string(s.str);
+                std::string open("\"\"\"");
+                std::string close("\"\"\"");
+                if(escaped.find('\n') != std::string::npos ||
+                   this->width_ < escaped.size() + 6)
+                {
+                    // if the string body contains newline or is enough long,
+                    // add newlines after and before delimiters.
+                    open += "\n";
+                    close = std::string("\\\n") + close;
+                }
+                return open + escaped + close;
+            }
+
+            // no linefeed. try to make it oneline-string.
+            std::string oneline = this->escape_basic_string(s.str);
+            if(oneline.size() + 2 < width_ || width_ < 2)
+            {
+                const std::string quote("\"");
+                return quote + oneline + quote;
+            }
+
+            // the line is too long compared to the specified width.
+            // split it into multiple lines.
+            std::string token("\"\"\"\n");
+            while(!oneline.empty())
+            {
+                if(oneline.size() < width_)
+                {
+                    token += oneline;
+                    oneline.clear();
+                }
+                else if(oneline.at(width_-2) == '\\')
+                {
+                    token += oneline.substr(0, width_-2);
+                    token += "\\\n";
+                    oneline.erase(0, width_-2);
+                }
+                else
+                {
+                    token += oneline.substr(0, width_-1);
+                    token += "\\\n";
+                    oneline.erase(0, width_-1);
+                }
+            }
+            return token + std::string("\\\n\"\"\"");
+        }
+        else // the string `s` is literal-string.
+        {
+            if(std::find(s.str.cbegin(), s.str.cend(), '\n') != s.str.cend() ||
+               std::find(s.str.cbegin(), s.str.cend(), '\'') != s.str.cend() )
+            {
+                std::string open("'''");
+                if(this->width_ + 6 < s.str.size())
+                {
+                    open += '\n'; // the first newline is ignored by TOML spec
+                }
+                const std::string close("'''");
+                return open + s.str + close;
+            }
+            else
+            {
+                const std::string quote("'");
+                return quote + s.str + quote;
+            }
+        }
+    }
+
+    std::string operator()(const local_date_type& d) const
+    {
+        std::ostringstream oss;
+        oss << d;
+        return oss.str();
+    }
+    std::string operator()(const local_time_type& t) const
+    {
+        std::ostringstream oss;
+        oss << t;
+        return oss.str();
+    }
+    std::string operator()(const local_datetime_type& dt) const
+    {
+        std::ostringstream oss;
+        oss << dt;
+        return oss.str();
+    }
+    std::string operator()(const offset_datetime_type& odt) const
+    {
+        std::ostringstream oss;
+        oss << odt;
+        return oss.str();
+    }
+
+    std::string operator()(const array_type& v) const
+    {
+        if(v.empty())
+        {
+            return std::string("[]");
+        }
+        if(this->is_array_of_tables(v))
+        {
+            return make_array_of_tables(v);
+        }
+
+        // not an array of tables. normal array.
+        // first, try to make it inline if none of the elements have a comment.
+        if( ! this->has_comment_inside(v))
+        {
+            const auto inl = this->make_inline_array(v);
+            if(inl.size() < this->width_ &&
+               std::find(inl.cbegin(), inl.cend(), '\n') == inl.cend())
+            {
+                return inl;
+            }
+        }
+
+        // if the length exceeds this->width_, print multiline array.
+        // key = [
+        //   # ...
+        //   42,
+        //   ...
+        // ]
+        std::string token;
+        std::string current_line;
+        token += "[\n";
+        for(const auto& item : v)
+        {
+            if( ! item.comments().empty() && !no_comment_)
+            {
+                // if comment exists, the element must be the only element in the line.
+                // e.g. the following is not allowed.
+                // ```toml
+                // array = [
+                // # comment for what?
+                // 1, 2, 3, 4, 5
+                // ]
+                // ```
+                if(!current_line.empty())
+                {
+                    if(current_line.back() != '\n')
+                    {
+                        current_line += '\n';
+                    }
+                    token += current_line;
+                    current_line.clear();
+                }
+                for(const auto& c : item.comments())
+                {
+                    token += '#';
+                    token += c;
+                    token += '\n';
+                }
+                token += toml::visit(*this, item);
+                if(!token.empty() && token.back() == '\n') {token.pop_back();}
+                token += ",\n";
+                continue;
+            }
+            std::string next_elem;
+            if(item.is_table())
+            {
+                serializer ser(*this);
+                ser.can_be_inlined_ = true;
+                ser.width_ = (std::numeric_limits<std::size_t>::max)();
+                next_elem += toml::visit(ser, item);
+            }
+            else
+            {
+                next_elem += toml::visit(*this, item);
+            }
+
+            // comma before newline.
+            if(!next_elem.empty() && next_elem.back() == '\n') {next_elem.pop_back();}
+
+            // if current line does not exceeds the width limit, continue.
+            if(current_line.size() + next_elem.size() + 1 < this->width_)
+            {
+                current_line += next_elem;
+                current_line += ',';
+            }
+            else if(current_line.empty())
+            {
+                // if current line was empty, force put the next_elem because
+                // next_elem is not splittable
+                token += next_elem;
+                token += ",\n";
+                // current_line is kept empty
+            }
+            else // reset current_line
+            {
+                assert(current_line.back() == ',');
+                token += current_line;
+                token += '\n';
+                current_line = next_elem;
+                current_line += ',';
+            }
+        }
+        if(!current_line.empty())
+        {
+            if(!current_line.empty() && current_line.back() != '\n')
+            {
+                current_line += '\n';
+            }
+            token += current_line;
+        }
+        token += "]\n";
+        return token;
+    }
+
+    // templatize for any table-like container
+    std::string operator()(const table_type& v) const
+    {
+        // if an element has a comment, then it can't be inlined.
+        // table = {# how can we write a comment for this? key = "value"}
+        if(this->can_be_inlined_ && !(this->has_comment_inside(v)))
+        {
+            std::string token;
+            if(!this->keys_.empty())
+            {
+                token += format_key(this->keys_.back());
+                token += " = ";
+            }
+            token += this->make_inline_table(v);
+            if(token.size() < this->width_ &&
+               token.end() == std::find(token.begin(), token.end(), '\n'))
+            {
+                return token;
+            }
+        }
+
+        std::string token;
+        if(!keys_.empty())
+        {
+            token += '[';
+            token += format_keys(keys_);
+            token += "]\n";
+        }
+        token += this->make_multiline_table(v);
+        return token;
+    }
+
+  private:
+
+    std::string escape_basic_string(const std::string& s) const
+    {
+        //XXX assuming `s` is a valid utf-8 sequence.
+        std::string retval;
+        for(const char c : s)
+        {
+            switch(c)
+            {
+                case '\\': {retval += "\\\\"; break;}
+                case '\"': {retval += "\\\""; break;}
+                case '\b': {retval += "\\b";  break;}
+                case '\t': {retval += "\\t";  break;}
+                case '\f': {retval += "\\f";  break;}
+                case '\n': {retval += "\\n";  break;}
+                case '\r': {retval += "\\r";  break;}
+                default  :
+                {
+                    if((0x00 <= c && c <= 0x08) || (0x0A <= c && c <= 0x1F) || c == 0x7F)
+                    {
+                        retval += "\\u00";
+                        retval += char(48 + (c / 16));
+                        retval += char((c % 16 < 10 ? 48 : 55) + (c % 16));
+                    }
+                    else
+                    {
+                        retval += c;
+                    }
+                }
+            }
+        }
+        return retval;
+    }
+
+    std::string escape_ml_basic_string(const std::string& s) const
+    {
+        std::string retval;
+        for(auto i=s.cbegin(), e=s.cend(); i!=e; ++i)
+        {
+            switch(*i)
+            {
+                case '\\': {retval += "\\\\"; break;}
+                // One or two consecutive "s are allowed.
+                // Later we will check there are no three consecutive "s.
+                //   case '\"': {retval += "\\\""; break;}
+                case '\b': {retval += "\\b";  break;}
+                case '\t': {retval += "\\t";  break;}
+                case '\f': {retval += "\\f";  break;}
+                case '\n': {retval += "\n";   break;}
+                case '\r':
+                {
+                    if(std::next(i) != e && *std::next(i) == '\n')
+                    {
+                        retval += "\r\n";
+                        ++i;
+                    }
+                    else
+                    {
+                        retval += "\\r";
+                    }
+                    break;
+                }
+                default  :
+                {
+                    const auto c = *i;
+                    if((0x00 <= c && c <= 0x08) || (0x0A <= c && c <= 0x1F) || c == 0x7F)
+                    {
+                        retval += "\\u00";
+                        retval += char(48 + (c / 16));
+                        retval += char((c % 16 < 10 ? 48 : 55) + (c % 16));
+                    }
+                    else
+                    {
+                        retval += c;
+                    }
+                }
+
+            }
+        }
+        // Only 1 or 2 consecutive `"`s are allowed in multiline basic string.
+        // 3 consecutive `"`s are considered as a closing delimiter.
+        // We need to check if there are 3 or more consecutive `"`s and insert
+        // backslash to break them down into several short `"`s like the `str6`
+        // in the following example.
+        // ```toml
+        // str4 = """Here are two quotation marks: "". Simple enough."""
+        // # str5 = """Here are three quotation marks: """."""  # INVALID
+        // str5 = """Here are three quotation marks: ""\"."""
+        // str6 = """Here are fifteen quotation marks: ""\"""\"""\"""\"""\"."""
+        // ```
+        auto found_3_quotes = retval.find("\"\"\"");
+        while(found_3_quotes != std::string::npos)
+        {
+            retval.replace(found_3_quotes, 3, "\"\"\\\"");
+            found_3_quotes = retval.find("\"\"\"");
+        }
+        return retval;
+    }
+
+    // if an element of a table or an array has a comment, it cannot be inlined.
+    bool has_comment_inside(const array_type& a) const noexcept
+    {
+        // if no_comment is set, comments would not be written.
+        if(this->no_comment_) {return false;}
+
+        for(const auto& v : a)
+        {
+            if(!v.comments().empty()) {return true;}
+        }
+        return false;
+    }
+    bool has_comment_inside(const table_type& t) const noexcept
+    {
+        // if no_comment is set, comments would not be written.
+        if(this->no_comment_) {return false;}
+
+        for(const auto& kv : t)
+        {
+            if(!kv.second.comments().empty()) {return true;}
+        }
+        return false;
+    }
+
+    std::string make_inline_array(const array_type& v) const
+    {
+        assert(!has_comment_inside(v));
+        std::string token;
+        token += '[';
+        bool is_first = true;
+        for(const auto& item : v)
+        {
+            if(is_first) {is_first = false;} else {token += ',';}
+            token += visit(serializer(
+                (std::numeric_limits<std::size_t>::max)(), this->float_prec_,
+                /* inlined */ true, /*no comment*/ false, /*keys*/ {},
+                /*has_comment*/ !item.comments().empty()), item);
+        }
+        token += ']';
+        return token;
+    }
+
+    std::string make_inline_table(const table_type& v) const
+    {
+        assert(!has_comment_inside(v));
+        assert(this->can_be_inlined_);
+        std::string token;
+        token += '{';
+        bool is_first = true;
+        for(const auto& kv : v)
+        {
+            // in inline tables, trailing comma is not allowed (toml-lang #569).
+            if(is_first) {is_first = false;} else {token += ',';}
+            token += format_key(kv.first);
+            token += '=';
+            token += visit(serializer(
+                (std::numeric_limits<std::size_t>::max)(), this->float_prec_,
+                /* inlined */ true, /*no comment*/ false, /*keys*/ {},
+                /*has_comment*/ !kv.second.comments().empty()), kv.second);
+        }
+        token += '}';
+        return token;
+    }
+
+    std::string make_multiline_table(const table_type& v) const
+    {
+        std::string token;
+
+        // print non-table elements first.
+        // ```toml
+        // [foo]         # a table we're writing now here
+        // key = "value" # <- non-table element, "key"
+        // # ...
+        // [foo.bar] # <- table element, "bar"
+        // ```
+        // because after printing [foo.bar], the remaining non-table values will
+        // be assigned into [foo.bar], not [foo]. Those values should be printed
+        // earlier.
+        for(const auto& kv : v)
+        {
+            if(kv.second.is_table() || is_array_of_tables(kv.second))
+            {
+                continue;
+            }
+
+            token += write_comments(kv.second);
+
+            const auto key_and_sep    = format_key(kv.first) + " = ";
+            const auto residual_width = (this->width_ > key_and_sep.size()) ?
+                                        this->width_ - key_and_sep.size() : 0;
+            token += key_and_sep;
+            token += visit(serializer(residual_width, this->float_prec_,
+                /*can be inlined*/ true, /*no comment*/ false, /*keys*/ {},
+                /*has_comment*/ !kv.second.comments().empty()), kv.second);
+
+            if(token.back() != '\n')
+            {
+                token += '\n';
+            }
+        }
+
+        // normal tables / array of tables
+
+        // after multiline table appeared, the other tables cannot be inline
+        // because the table would be assigned into the table.
+        // [foo]
+        // ...
+        // bar = {...} # <- bar will be a member of [foo].
+        bool multiline_table_printed = false;
+        for(const auto& kv : v)
+        {
+            if(!kv.second.is_table() && !is_array_of_tables(kv.second))
+            {
+                continue; // other stuff are already serialized. skip them.
+            }
+
+            std::vector<toml::key> ks(this->keys_);
+            ks.push_back(kv.first);
+
+            auto tmp = visit(serializer(this->width_, this->float_prec_,
+                !multiline_table_printed, this->no_comment_, ks,
+                /*has_comment*/ !kv.second.comments().empty()), kv.second);
+
+            // If it is the first time to print a multi-line table, it would be
+            // helpful to separate normal key-value pair and subtables by a
+            // newline.
+            // (this checks if the current key-value pair contains newlines.
+            //  but it is not perfect because multi-line string can also contain
+            //  a newline. in such a case, an empty line will be written) TODO
+            if((!multiline_table_printed) &&
+               std::find(tmp.cbegin(), tmp.cend(), '\n') != tmp.cend())
+            {
+                multiline_table_printed = true;
+                token += '\n'; // separate key-value pairs and subtables
+
+                token += write_comments(kv.second);
+                token += tmp;
+
+                // care about recursive tables (all tables in each level prints
+                // newline and there will be a full of newlines)
+                if(tmp.substr(tmp.size() - 2, 2) != "\n\n" &&
+                   tmp.substr(tmp.size() - 4, 4) != "\r\n\r\n" )
+                {
+                    token += '\n';
+                }
+            }
+            else
+            {
+                token += write_comments(kv.second);
+                token += tmp;
+                token += '\n';
+            }
+        }
+        return token;
+    }
+
+    std::string make_array_of_tables(const array_type& v) const
+    {
+        // if it's not inlined, we need to add `[[table.key]]`.
+        // but if it can be inlined, we can format it as the following.
+        // ```
+        // table.key = [
+        //   {...},
+        //   # comment
+        //   {...},
+        // ]
+        // ```
+        // This function checks if inlinization is possible or not, and then
+        // format the array-of-tables in a proper way.
+        //
+        // Note about comments:
+        //
+        // If the array itself has a comment (value_has_comment_ == true), we
+        // should try to make it inline.
+        // ```toml
+        // # comment about array
+        // array = [
+        //   # comment about table element
+        //   {of = "table"}
+        // ]
+        // ```
+        // If it is formatted as a multiline table, the two comments becomes
+        // indistinguishable.
+        // ```toml
+        // # comment about array
+        // # comment about table element
+        // [[array]]
+        // of = "table"
+        // ```
+        // So we need to try to make it inline, and it force-inlines regardless
+        // of the line width limit.
+        //     It may fail if the element of a table has comment. In that case,
+        // the array-of-tables will be formatted as a multiline table.
+        if(this->can_be_inlined_ || this->value_has_comment_)
+        {
+            std::string token;
+            if(!keys_.empty())
+            {
+                token += format_key(keys_.back());
+                token += " = ";
+            }
+
+            bool failed = false;
+            token += "[\n";
+            for(const auto& item : v)
+            {
+                // if an element of the table has a comment, the table
+                // cannot be inlined.
+                if(this->has_comment_inside(item.as_table()))
+                {
+                    failed = true;
+                    break;
+                }
+                // write comments for the table itself
+                token += write_comments(item);
+
+                const auto t = this->make_inline_table(item.as_table());
+
+                if(t.size() + 1 > width_ || // +1 for the last comma {...},
+                   std::find(t.cbegin(), t.cend(), '\n') != t.cend())
+                {
+                    // if the value itself has a comment, ignore the line width limit
+                    if( ! this->value_has_comment_)
+                    {
+                        failed = true;
+                        break;
+                    }
+                }
+                token += t;
+                token += ",\n";
+            }
+
+            if( ! failed)
+            {
+                token += "]\n";
+                return token;
+            }
+            // if failed, serialize them as [[array.of.tables]].
+        }
+
+        std::string token;
+        for(const auto& item : v)
+        {
+            token += write_comments(item);
+            token += "[[";
+            token += format_keys(keys_);
+            token += "]]\n";
+            token += this->make_multiline_table(item.as_table());
+        }
+        return token;
+    }
+
+    std::string write_comments(const value_type& v) const
+    {
+        std::string retval;
+        if(this->no_comment_) {return retval;}
+
+        for(const auto& c : v.comments())
+        {
+            retval += '#';
+            retval += c;
+            retval += '\n';
+        }
+        return retval;
+    }
+
+    bool is_array_of_tables(const value_type& v) const
+    {
+        if(!v.is_array() || v.as_array().empty()) {return false;}
+        return is_array_of_tables(v.as_array());
+    }
+    bool is_array_of_tables(const array_type& v) const
+    {
+        // Since TOML v0.5.0, heterogeneous arrays are allowed. So we need to
+        // check all the element in an array to check if the array is an array
+        // of tables.
+        return std::all_of(v.begin(), v.end(), [](const value_type& elem) {
+                return elem.is_table();
+            });
+    }
+
+  private:
+
+    bool        can_be_inlined_;
+    bool        no_comment_;
+    bool        value_has_comment_;
+    int         float_prec_;
+    std::size_t width_;
+    std::vector<toml::key> keys_;
+};
+
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V>
+std::string
+format(const basic_value<C, M, V>& v, std::size_t w = 80u,
+       int fprec = std::numeric_limits<toml::floating>::max_digits10,
+       bool no_comment = false, bool force_inline = false)
+{
+    using value_type = basic_value<C, M, V>;
+    // if value is a table, it is considered to be a root object.
+    // the root object can't be an inline table.
+    if(v.is_table())
+    {
+        std::ostringstream oss;
+        if(!v.comments().empty())
+        {
+            oss << v.comments();
+            oss << '\n'; // to split the file comment from the first element
+        }
+        const auto serialized = visit(serializer<value_type>(w, fprec, false, no_comment), v);
+        oss << serialized;
+        return oss.str();
+    }
+    return visit(serializer<value_type>(w, fprec, force_inline), v);
+}
+
+namespace detail
+{
+template<typename charT, typename traits>
+int comment_index(std::basic_ostream<charT, traits>&)
+{
+    static const int index = std::ios_base::xalloc();
+    return index;
+}
+} // detail
+
+template<typename charT, typename traits>
+std::basic_ostream<charT, traits>&
+nocomment(std::basic_ostream<charT, traits>& os)
+{
+    // by default, it is zero. and by default, it shows comments.
+    os.iword(detail::comment_index(os)) = 1;
+    return os;
+}
+
+template<typename charT, typename traits>
+std::basic_ostream<charT, traits>&
+showcomment(std::basic_ostream<charT, traits>& os)
+{
+    // by default, it is zero. and by default, it shows comments.
+    os.iword(detail::comment_index(os)) = 0;
+    return os;
+}
+
+template<typename charT, typename traits, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+std::basic_ostream<charT, traits>&
+operator<<(std::basic_ostream<charT, traits>& os, const basic_value<C, M, V>& v)
+{
+    using value_type = basic_value<C, M, V>;
+
+    // get status of std::setw().
+    const auto w     = static_cast<std::size_t>(os.width());
+    const int  fprec = static_cast<int>(os.precision());
+    os.width(0);
+
+    // by default, iword is initialized by 0. And by default, toml11 outputs
+    // comments. So `0` means showcomment. 1 means nocommnet.
+    const bool no_comment = (1 == os.iword(detail::comment_index(os)));
+
+    if(!no_comment && v.is_table() && !v.comments().empty())
+    {
+        os << v.comments();
+        os << '\n'; // to split the file comment from the first element
+    }
+    // the root object can't be an inline table. so pass `false`.
+    const auto serialized = visit(serializer<value_type>(w, fprec, no_comment, false), v);
+    os << serialized;
+
+    // if v is a non-table value, and has only one comment, then
+    // put a comment just after a value. in the following way.
+    //
+    // ```toml
+    // key = "value" # comment.
+    // ```
+    //
+    // Since the top-level toml object is a table, one who want to put a
+    // non-table toml value must use this in a following way.
+    //
+    // ```cpp
+    // toml::value v;
+    // std::cout << "user-defined-key = " << v << std::endl;
+    // ```
+    //
+    // In this case, it is impossible to put comments before key-value pair.
+    // The only way to preserve comments is to put all of them after a value.
+    if(!no_comment && !v.is_table() && !v.comments().empty())
+    {
+        os << " #";
+        for(const auto& c : v.comments()) {os << c;}
+    }
+    return os;
+}
+
+} // toml
+#endif// TOML11_SERIALIZER_HPP
diff --git a/src/toml11/toml/source_location.hpp b/src/toml11/toml/source_location.hpp
new file mode 100644
index 000000000..fa175b5b4
--- /dev/null
+++ b/src/toml11/toml/source_location.hpp
@@ -0,0 +1,233 @@
+//     Copyright Toru Niina 2019.
+// Distributed under the MIT License.
+#ifndef TOML11_SOURCE_LOCATION_HPP
+#define TOML11_SOURCE_LOCATION_HPP
+#include <cstdint>
+#include <sstream>
+
+#include "region.hpp"
+
+namespace toml
+{
+
+// A struct to contain location in a toml file.
+// The interface imitates std::experimental::source_location,
+// but not completely the same.
+//
+// It would be constructed by toml::value. It can be used to generate
+// user-defined error messages.
+//
+// - std::uint_least32_t line() const noexcept
+//   - returns the line number where the region is on.
+// - std::uint_least32_t column() const noexcept
+//   - returns the column number where the region starts.
+// - std::uint_least32_t region() const noexcept
+//   - returns the size of the region.
+//
+// +-- line()       +-- region of interest (region() == 9)
+// v            .---+---.
+// 12 | value = "foo bar"
+//              ^
+//              +-- column()
+//
+// - std::string const& file_name() const noexcept;
+//   - name of the file.
+// - std::string const& line_str() const noexcept;
+//   - the whole line that contains the region of interest.
+//
+struct source_location
+{
+  public:
+
+    source_location()
+        : line_num_(1), column_num_(1), region_size_(1),
+          file_name_("unknown file"), line_str_("")
+    {}
+
+    explicit source_location(const detail::region_base* reg)
+        : line_num_(1), column_num_(1), region_size_(1),
+          file_name_("unknown file"), line_str_("")
+    {
+        if(reg)
+        {
+            if(reg->line_num() != detail::region_base().line_num())
+            {
+                line_num_ = static_cast<std::uint_least32_t>(
+                        std::stoul(reg->line_num()));
+            }
+            column_num_  = static_cast<std::uint_least32_t>(reg->before() + 1);
+            region_size_ = static_cast<std::uint_least32_t>(reg->size());
+            file_name_   = reg->name();
+            line_str_    = reg->line();
+        }
+    }
+
+    explicit source_location(const detail::region& reg)
+        : line_num_(static_cast<std::uint_least32_t>(std::stoul(reg.line_num()))),
+          column_num_(static_cast<std::uint_least32_t>(reg.before() + 1)),
+          region_size_(static_cast<std::uint_least32_t>(reg.size())),
+          file_name_(reg.name()),
+          line_str_ (reg.line())
+    {}
+    explicit source_location(const detail::location& loc)
+        : line_num_(static_cast<std::uint_least32_t>(std::stoul(loc.line_num()))),
+          column_num_(static_cast<std::uint_least32_t>(loc.before() + 1)),
+          region_size_(static_cast<std::uint_least32_t>(loc.size())),
+          file_name_(loc.name()),
+          line_str_ (loc.line())
+    {}
+
+    ~source_location() = default;
+    source_location(source_location const&) = default;
+    source_location(source_location &&)     = default;
+    source_location& operator=(source_location const&) = default;
+    source_location& operator=(source_location &&)     = default;
+
+    std::uint_least32_t line()      const noexcept {return line_num_;}
+    std::uint_least32_t column()    const noexcept {return column_num_;}
+    std::uint_least32_t region()    const noexcept {return region_size_;}
+
+    std::string const&  file_name() const noexcept {return file_name_;}
+    std::string const&  line_str()  const noexcept {return line_str_;}
+
+  private:
+
+    std::uint_least32_t line_num_;
+    std::uint_least32_t column_num_;
+    std::uint_least32_t region_size_;
+    std::string         file_name_;
+    std::string         line_str_;
+};
+
+namespace detail
+{
+
+// internal error message generation.
+inline std::string format_underline(const std::string& message,
+        const std::vector<std::pair<source_location, std::string>>& loc_com,
+        const std::vector<std::string>& helps = {},
+        const bool colorize = TOML11_ERROR_MESSAGE_COLORIZED)
+{
+    std::size_t line_num_width = 0;
+    for(const auto& lc : loc_com)
+    {
+        std::uint_least32_t line = lc.first.line();
+        std::size_t        digit = 0;
+        while(line != 0)
+        {
+            line  /= 10;
+            digit +=  1;
+        }
+        line_num_width = (std::max)(line_num_width, digit);
+    }
+    // 1 is the minimum width
+    line_num_width = std::max<std::size_t>(line_num_width, 1);
+
+    std::ostringstream retval;
+
+    if(colorize)
+    {
+        retval << color::colorize; // turn on ANSI color
+    }
+
+    // XXX
+    // Here, before `colorize` support, it does not output `[error]` prefix
+    // automatically. So some user may output it manually and this change may
+    // duplicate the prefix. To avoid it, check the first 7 characters and
+    // if it is "[error]", it removes that part from the message shown.
+    if(message.size() > 7 && message.substr(0, 7) == "[error]")
+    {
+        retval << color::bold << color::red << "[error]" << color::reset
+               << color::bold << message.substr(7) << color::reset << '\n';
+    }
+    else
+    {
+        retval << color::bold << color::red << "[error] " << color::reset
+               << color::bold << message << color::reset << '\n';
+    }
+
+    const auto format_one_location = [line_num_width]
+        (std::ostringstream& oss,
+         const source_location& loc, const std::string& comment) -> void
+        {
+            oss << ' ' << color::bold << color::blue
+                << std::setw(static_cast<int>(line_num_width))
+                << std::right << loc.line() << " | "  << color::reset
+                << loc.line_str() << '\n';
+
+            oss << make_string(line_num_width + 1, ' ')
+                << color::bold << color::blue << " | " << color::reset
+                << make_string(loc.column()-1 /*1-origin*/, ' ');
+
+            if(loc.region() == 1)
+            {
+                // invalid
+                // ^------
+                oss << color::bold << color::red << "^---" << color::reset;
+            }
+            else
+            {
+                // invalid
+                // ~~~~~~~
+                const auto underline_len = (std::min)(
+                    static_cast<std::size_t>(loc.region()), loc.line_str().size());
+                oss << color::bold << color::red
+                    << make_string(underline_len, '~') << color::reset;
+            }
+            oss << ' ';
+            oss << comment;
+            return;
+        };
+
+    assert(!loc_com.empty());
+
+    // --> example.toml
+    //   |
+    retval << color::bold << color::blue << " --> " << color::reset
+           << loc_com.front().first.file_name() << '\n';
+    retval << make_string(line_num_width + 1, ' ')
+           << color::bold << color::blue << " |\n"  << color::reset;
+    // 1 | key value
+    //   |    ^--- missing =
+    format_one_location(retval, loc_com.front().first, loc_com.front().second);
+
+    // process the rest of the locations
+    for(std::size_t i=1; i<loc_com.size(); ++i)
+    {
+        const auto& prev = loc_com.at(i-1);
+        const auto& curr = loc_com.at(i);
+
+        retval << '\n';
+        // if the filenames are the same, print "..."
+        if(prev.first.file_name() == curr.first.file_name())
+        {
+            retval << color::bold << color::blue << " ...\n" << color::reset;
+        }
+        else // if filename differs, print " --> filename.toml" again
+        {
+            retval << color::bold << color::blue << " --> " << color::reset
+                   << curr.first.file_name() << '\n';
+            retval << make_string(line_num_width + 1, ' ')
+                   << color::bold << color::blue << " |\n"  << color::reset;
+        }
+
+        format_one_location(retval, curr.first, curr.second);
+    }
+
+    if(!helps.empty())
+    {
+        retval << '\n';
+        retval << make_string(line_num_width + 1, ' ');
+        retval << color::bold << color::blue << " |" << color::reset;
+        for(const auto& help : helps)
+        {
+            retval << color::bold << "\nHint: " << color::reset;
+            retval << help;
+        }
+    }
+    return retval.str();
+}
+
+} // detail
+} // toml
+#endif// TOML11_SOURCE_LOCATION_HPP
diff --git a/src/toml11/toml/storage.hpp b/src/toml11/toml/storage.hpp
new file mode 100644
index 000000000..202f9035f
--- /dev/null
+++ b/src/toml11/toml/storage.hpp
@@ -0,0 +1,43 @@
+//     Copyright Toru Niina 2017.
+// Distributed under the MIT License.
+#ifndef TOML11_STORAGE_HPP
+#define TOML11_STORAGE_HPP
+#include "utility.hpp"
+
+namespace toml
+{
+namespace detail
+{
+
+// this contains pointer and deep-copy the content if copied.
+// to avoid recursive pointer.
+template<typename T>
+struct storage
+{
+    using value_type = T;
+
+    explicit storage(value_type const& v): ptr(toml::make_unique<T>(v)) {}
+    explicit storage(value_type&&      v): ptr(toml::make_unique<T>(std::move(v))) {}
+    ~storage() = default;
+    storage(const storage& rhs): ptr(toml::make_unique<T>(*rhs.ptr)) {}
+    storage& operator=(const storage& rhs)
+    {
+        this->ptr = toml::make_unique<T>(*rhs.ptr);
+        return *this;
+    }
+    storage(storage&&) = default;
+    storage& operator=(storage&&) = default;
+
+    bool is_ok() const noexcept {return static_cast<bool>(ptr);}
+
+    value_type&       value() &      noexcept {return *ptr;}
+    value_type const& value() const& noexcept {return *ptr;}
+    value_type&&      value() &&     noexcept {return std::move(*ptr);}
+
+  private:
+    std::unique_ptr<value_type> ptr;
+};
+
+} // detail
+} // toml
+#endif// TOML11_STORAGE_HPP
diff --git a/src/toml11/toml/string.hpp b/src/toml11/toml/string.hpp
new file mode 100644
index 000000000..5136d8c56
--- /dev/null
+++ b/src/toml11/toml/string.hpp
@@ -0,0 +1,225 @@
+//     Copyright Toru Niina 2017.
+// Distributed under the MIT License.
+#ifndef TOML11_STRING_HPP
+#define TOML11_STRING_HPP
+#include <cstdint>
+
+#include <algorithm>
+#include <string>
+
+#if __cplusplus >= 201703L
+#if __has_include(<string_view>)
+#define TOML11_USING_STRING_VIEW 1
+#include <string_view>
+#endif
+#endif
+
+namespace toml
+{
+
+enum class string_t : std::uint8_t
+{
+    basic   = 0,
+    literal = 1,
+};
+
+struct string
+{
+    string()  = default;
+    ~string() = default;
+    string(const string& s) = default;
+    string(string&& s)      = default;
+    string& operator=(const string& s) = default;
+    string& operator=(string&& s)      = default;
+
+    string(const std::string& s): kind(string_t::basic), str(s){}
+    string(const std::string& s, string_t k):   kind(k), str(s){}
+    string(const char* s):        kind(string_t::basic), str(s){}
+    string(const char* s,        string_t k):   kind(k), str(s){}
+
+    string(std::string&& s): kind(string_t::basic), str(std::move(s)){}
+    string(std::string&& s, string_t k):   kind(k), str(std::move(s)){}
+
+    string& operator=(const std::string& s)
+    {kind = string_t::basic; str = s; return *this;}
+    string& operator=(std::string&& s)
+    {kind = string_t::basic; str = std::move(s); return *this;}
+
+    operator std::string&       () &      noexcept {return str;}
+    operator std::string const& () const& noexcept {return str;}
+    operator std::string&&      () &&     noexcept {return std::move(str);}
+
+    string& operator+=(const char*        rhs) {str += rhs; return *this;}
+    string& operator+=(const char         rhs) {str += rhs; return *this;}
+    string& operator+=(const std::string& rhs) {str += rhs; return *this;}
+    string& operator+=(const string&      rhs) {str += rhs.str; return *this;}
+
+#if defined(TOML11_USING_STRING_VIEW) && TOML11_USING_STRING_VIEW>0
+    explicit string(std::string_view s): kind(string_t::basic), str(s){}
+    string(std::string_view s, string_t k): kind(k), str(s){}
+
+    string& operator=(std::string_view s)
+    {kind = string_t::basic; str = s; return *this;}
+
+    explicit operator std::string_view() const noexcept
+    {return std::string_view(str);}
+
+    string& operator+=(const std::string_view& rhs) {str += rhs; return *this;}
+#endif
+
+    string_t    kind;
+    std::string str;
+};
+
+inline bool operator==(const string& lhs, const string& rhs)
+{
+    return lhs.kind == rhs.kind && lhs.str == rhs.str;
+}
+inline bool operator!=(const string& lhs, const string& rhs)
+{
+    return !(lhs == rhs);
+}
+inline bool operator<(const string& lhs, const string& rhs)
+{
+    return (lhs.kind == rhs.kind) ? (lhs.str < rhs.str) : (lhs.kind < rhs.kind);
+}
+inline bool operator>(const string& lhs, const string& rhs)
+{
+    return rhs < lhs;
+}
+inline bool operator<=(const string& lhs, const string& rhs)
+{
+    return !(rhs < lhs);
+}
+inline bool operator>=(const string& lhs, const string& rhs)
+{
+    return !(lhs < rhs);
+}
+
+inline bool
+operator==(const string& lhs, const std::string& rhs) {return lhs.str == rhs;}
+inline bool
+operator!=(const string& lhs, const std::string& rhs) {return lhs.str != rhs;}
+inline bool
+operator< (const string& lhs, const std::string& rhs) {return lhs.str <  rhs;}
+inline bool
+operator> (const string& lhs, const std::string& rhs) {return lhs.str >  rhs;}
+inline bool
+operator<=(const string& lhs, const std::string& rhs) {return lhs.str <= rhs;}
+inline bool
+operator>=(const string& lhs, const std::string& rhs) {return lhs.str >= rhs;}
+
+inline bool
+operator==(const std::string& lhs, const string& rhs) {return lhs == rhs.str;}
+inline bool
+operator!=(const std::string& lhs, const string& rhs) {return lhs != rhs.str;}
+inline bool
+operator< (const std::string& lhs, const string& rhs) {return lhs <  rhs.str;}
+inline bool
+operator> (const std::string& lhs, const string& rhs) {return lhs >  rhs.str;}
+inline bool
+operator<=(const std::string& lhs, const string& rhs) {return lhs <= rhs.str;}
+inline bool
+operator>=(const std::string& lhs, const string& rhs) {return lhs >= rhs.str;}
+
+inline bool
+operator==(const string& lhs, const char* rhs) {return lhs.str == std::string(rhs);}
+inline bool
+operator!=(const string& lhs, const char* rhs) {return lhs.str != std::string(rhs);}
+inline bool
+operator< (const string& lhs, const char* rhs) {return lhs.str <  std::string(rhs);}
+inline bool
+operator> (const string& lhs, const char* rhs) {return lhs.str >  std::string(rhs);}
+inline bool
+operator<=(const string& lhs, const char* rhs) {return lhs.str <= std::string(rhs);}
+inline bool
+operator>=(const string& lhs, const char* rhs) {return lhs.str >= std::string(rhs);}
+
+inline bool
+operator==(const char* lhs, const string& rhs) {return std::string(lhs) == rhs.str;}
+inline bool
+operator!=(const char* lhs, const string& rhs) {return std::string(lhs) != rhs.str;}
+inline bool
+operator< (const char* lhs, const string& rhs) {return std::string(lhs) <  rhs.str;}
+inline bool
+operator> (const char* lhs, const string& rhs) {return std::string(lhs) >  rhs.str;}
+inline bool
+operator<=(const char* lhs, const string& rhs) {return std::string(lhs) <= rhs.str;}
+inline bool
+operator>=(const char* lhs, const string& rhs) {return std::string(lhs) >= rhs.str;}
+
+template<typename charT, typename traits>
+std::basic_ostream<charT, traits>&
+operator<<(std::basic_ostream<charT, traits>& os, const string& s)
+{
+    if(s.kind == string_t::basic)
+    {
+        if(std::find(s.str.cbegin(), s.str.cend(), '\n') != s.str.cend())
+        {
+            // it contains newline. make it multiline string.
+            os << "\"\"\"\n";
+            for(auto i=s.str.cbegin(), e=s.str.cend(); i!=e; ++i)
+            {
+                switch(*i)
+                {
+                    case '\\': {os << "\\\\"; break;}
+                    case '\"': {os << "\\\""; break;}
+                    case '\b': {os << "\\b";  break;}
+                    case '\t': {os << "\\t";  break;}
+                    case '\f': {os << "\\f";  break;}
+                    case '\n': {os << '\n';   break;}
+                    case '\r':
+                    {
+                        // since it is a multiline string,
+                        // CRLF is not needed to be escaped.
+                        if(std::next(i) != e && *std::next(i) == '\n')
+                        {
+                            os << "\r\n";
+                            ++i;
+                        }
+                        else
+                        {
+                            os << "\\r";
+                        }
+                        break;
+                    }
+                    default: {os << *i; break;}
+                }
+            }
+            os << "\\\n\"\"\"";
+            return os;
+        }
+        // no newline. make it inline.
+        os << "\"";
+        for(const auto c : s.str)
+        {
+            switch(c)
+            {
+                case '\\': {os << "\\\\"; break;}
+                case '\"': {os << "\\\""; break;}
+                case '\b': {os << "\\b";  break;}
+                case '\t': {os << "\\t";  break;}
+                case '\f': {os << "\\f";  break;}
+                case '\n': {os << "\\n";  break;}
+                case '\r': {os << "\\r";  break;}
+                default  : {os << c;      break;}
+            }
+        }
+        os << "\"";
+        return os;
+    }
+    // the string `s` is literal-string.
+    if(std::find(s.str.cbegin(), s.str.cend(), '\n') != s.str.cend() ||
+       std::find(s.str.cbegin(), s.str.cend(), '\'') != s.str.cend() )
+    {
+        // contains newline or single quote. make it multiline.
+        os << "'''\n" << s.str << "'''";
+        return os;
+    }
+    // normal literal string
+    os << '\'' << s.str << '\'';
+    return os;
+}
+
+} // toml
+#endif// TOML11_STRING_H
diff --git a/src/toml11/toml/traits.hpp b/src/toml11/toml/traits.hpp
new file mode 100644
index 000000000..5495c93b2
--- /dev/null
+++ b/src/toml11/toml/traits.hpp
@@ -0,0 +1,327 @@
+//     Copyright Toru Niina 2017.
+// Distributed under the MIT License.
+#ifndef TOML11_TRAITS_HPP
+#define TOML11_TRAITS_HPP
+
+#include "from.hpp"
+#include "into.hpp"
+
+#include <chrono>
+#include <forward_list>
+#include <string>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+
+#if __cplusplus >= 201703L
+#if __has_include(<string_view>)
+#include <string_view>
+#endif // has_include(<string_view>)
+#endif // cplusplus   >= C++17
+
+namespace toml
+{
+template<typename C, template<typename ...> class T, template<typename ...> class A>
+class basic_value;
+
+namespace detail
+{
+// ---------------------------------------------------------------------------
+// check whether type T is a kind of container/map class
+
+struct has_iterator_impl
+{
+    template<typename T> static std::true_type  check(typename T::iterator*);
+    template<typename T> static std::false_type check(...);
+};
+struct has_value_type_impl
+{
+    template<typename T> static std::true_type  check(typename T::value_type*);
+    template<typename T> static std::false_type check(...);
+};
+struct has_key_type_impl
+{
+    template<typename T> static std::true_type  check(typename T::key_type*);
+    template<typename T> static std::false_type check(...);
+};
+struct has_mapped_type_impl
+{
+    template<typename T> static std::true_type  check(typename T::mapped_type*);
+    template<typename T> static std::false_type check(...);
+};
+struct has_reserve_method_impl
+{
+    template<typename T> static std::false_type check(...);
+    template<typename T> static std::true_type  check(
+        decltype(std::declval<T>().reserve(std::declval<std::size_t>()))*);
+};
+struct has_push_back_method_impl
+{
+    template<typename T> static std::false_type check(...);
+    template<typename T> static std::true_type  check(
+        decltype(std::declval<T>().push_back(std::declval<typename T::value_type>()))*);
+};
+struct is_comparable_impl
+{
+    template<typename T> static std::false_type check(...);
+    template<typename T> static std::true_type  check(
+        decltype(std::declval<T>() < std::declval<T>())*);
+};
+
+struct has_from_toml_method_impl
+{
+    template<typename T, typename C,
+             template<typename ...> class Tb, template<typename ...> class A>
+    static std::true_type  check(
+        decltype(std::declval<T>().from_toml(
+                std::declval<::toml::basic_value<C, Tb, A>>()))*);
+
+    template<typename T, typename C,
+             template<typename ...> class Tb, template<typename ...> class A>
+    static std::false_type check(...);
+};
+struct has_into_toml_method_impl
+{
+    template<typename T>
+    static std::true_type  check(decltype(std::declval<T>().into_toml())*);
+    template<typename T>
+    static std::false_type check(...);
+};
+
+struct has_specialized_from_impl
+{
+    template<typename T>
+    static std::false_type check(...);
+    template<typename T, std::size_t S = sizeof(::toml::from<T>)>
+    static std::true_type check(::toml::from<T>*);
+};
+struct has_specialized_into_impl
+{
+    template<typename T>
+    static std::false_type check(...);
+    template<typename T, std::size_t S = sizeof(::toml::into<T>)>
+    static std::true_type check(::toml::from<T>*);
+};
+
+
+/// Intel C++ compiler can not use decltype in parent class declaration, here
+/// is a hack to work around it. https://stackoverflow.com/a/23953090/4692076
+#ifdef __INTEL_COMPILER
+#define decltype(...) std::enable_if<true, decltype(__VA_ARGS__)>::type
+#endif
+
+template<typename T>
+struct has_iterator    : decltype(has_iterator_impl::check<T>(nullptr)){};
+template<typename T>
+struct has_value_type  : decltype(has_value_type_impl::check<T>(nullptr)){};
+template<typename T>
+struct has_key_type    : decltype(has_key_type_impl::check<T>(nullptr)){};
+template<typename T>
+struct has_mapped_type : decltype(has_mapped_type_impl::check<T>(nullptr)){};
+template<typename T>
+struct has_reserve_method : decltype(has_reserve_method_impl::check<T>(nullptr)){};
+template<typename T>
+struct has_push_back_method : decltype(has_push_back_method_impl::check<T>(nullptr)){};
+template<typename T>
+struct is_comparable : decltype(is_comparable_impl::check<T>(nullptr)){};
+
+template<typename T, typename C,
+         template<typename ...> class Tb, template<typename ...> class A>
+struct has_from_toml_method
+: decltype(has_from_toml_method_impl::check<T, C, Tb, A>(nullptr)){};
+
+template<typename T>
+struct has_into_toml_method
+: decltype(has_into_toml_method_impl::check<T>(nullptr)){};
+
+template<typename T>
+struct has_specialized_from : decltype(has_specialized_from_impl::check<T>(nullptr)){};
+template<typename T>
+struct has_specialized_into : decltype(has_specialized_into_impl::check<T>(nullptr)){};
+
+#ifdef __INTEL_COMPILER
+#undef decltype
+#endif
+
+// ---------------------------------------------------------------------------
+// C++17 and/or/not
+
+#if __cplusplus >= 201703L
+
+using std::conjunction;
+using std::disjunction;
+using std::negation;
+
+#else
+
+template<typename ...> struct conjunction : std::true_type{};
+template<typename T>   struct conjunction<T> : T{};
+template<typename T, typename ... Ts>
+struct conjunction<T, Ts...> :
+    std::conditional<static_cast<bool>(T::value), conjunction<Ts...>, T>::type
+{};
+
+template<typename ...> struct disjunction : std::false_type{};
+template<typename T>   struct disjunction<T> : T {};
+template<typename T, typename ... Ts>
+struct disjunction<T, Ts...> :
+    std::conditional<static_cast<bool>(T::value), T, disjunction<Ts...>>::type
+{};
+
+template<typename T>
+struct negation : std::integral_constant<bool, !static_cast<bool>(T::value)>{};
+
+#endif
+
+// ---------------------------------------------------------------------------
+// type checkers
+
+template<typename T> struct is_std_pair : std::false_type{};
+template<typename T1, typename T2>
+struct is_std_pair<std::pair<T1, T2>> : std::true_type{};
+
+template<typename T> struct is_std_tuple : std::false_type{};
+template<typename ... Ts>
+struct is_std_tuple<std::tuple<Ts...>> : std::true_type{};
+
+template<typename T> struct is_std_forward_list : std::false_type{};
+template<typename T>
+struct is_std_forward_list<std::forward_list<T>> : std::true_type{};
+
+template<typename T> struct is_chrono_duration: std::false_type{};
+template<typename Rep, typename Period>
+struct is_chrono_duration<std::chrono::duration<Rep, Period>>: std::true_type{};
+
+template<typename T>
+struct is_map : conjunction< // map satisfies all the following conditions
+    has_iterator<T>,         // has T::iterator
+    has_value_type<T>,       // has T::value_type
+    has_key_type<T>,         // has T::key_type
+    has_mapped_type<T>       // has T::mapped_type
+    >{};
+template<typename T> struct is_map<T&>                : is_map<T>{};
+template<typename T> struct is_map<T const&>          : is_map<T>{};
+template<typename T> struct is_map<T volatile&>       : is_map<T>{};
+template<typename T> struct is_map<T const volatile&> : is_map<T>{};
+
+template<typename T>
+struct is_container : conjunction<
+    negation<is_map<T>>,                         // not a map
+    negation<std::is_same<T, std::string>>,      // not a std::string
+#if __cplusplus >= 201703L
+#if __has_include(<string_view>)
+    negation<std::is_same<T, std::string_view>>, // not a std::string_view
+#endif // has_include(<string_view>)
+#endif
+    has_iterator<T>,                             // has T::iterator
+    has_value_type<T>                            // has T::value_type
+    >{};
+template<typename T> struct is_container<T&>                : is_container<T>{};
+template<typename T> struct is_container<T const&>          : is_container<T>{};
+template<typename T> struct is_container<T volatile&>       : is_container<T>{};
+template<typename T> struct is_container<T const volatile&> : is_container<T>{};
+
+template<typename T>
+struct is_basic_value: std::false_type{};
+template<typename T> struct is_basic_value<T&>                : is_basic_value<T>{};
+template<typename T> struct is_basic_value<T const&>          : is_basic_value<T>{};
+template<typename T> struct is_basic_value<T volatile&>       : is_basic_value<T>{};
+template<typename T> struct is_basic_value<T const volatile&> : is_basic_value<T>{};
+template<typename C, template<typename ...> class M, template<typename ...> class V>
+struct is_basic_value<::toml::basic_value<C, M, V>>: std::true_type{};
+
+// ---------------------------------------------------------------------------
+// C++14 index_sequence
+
+#if __cplusplus >= 201402L
+
+using std::index_sequence;
+using std::make_index_sequence;
+
+#else
+
+template<std::size_t ... Ns> struct index_sequence{};
+
+template<typename IS, std::size_t N> struct push_back_index_sequence{};
+template<std::size_t N, std::size_t ... Ns>
+struct push_back_index_sequence<index_sequence<Ns...>, N>
+{
+    typedef index_sequence<Ns..., N> type;
+};
+
+template<std::size_t N>
+struct index_sequence_maker
+{
+    typedef typename push_back_index_sequence<
+        typename index_sequence_maker<N-1>::type, N>::type type;
+};
+template<>
+struct index_sequence_maker<0>
+{
+    typedef index_sequence<0> type;
+};
+template<std::size_t N>
+using make_index_sequence = typename index_sequence_maker<N-1>::type;
+
+#endif // __cplusplus >= 2014
+
+// ---------------------------------------------------------------------------
+// C++14 enable_if_t
+
+#if __cplusplus >= 201402L
+
+using std::enable_if_t;
+
+#else
+
+template<bool B, typename T>
+using enable_if_t = typename std::enable_if<B, T>::type;
+
+#endif // __cplusplus >= 2014
+
+// ---------------------------------------------------------------------------
+// return_type_of_t
+
+#if __cplusplus >= 201703L && defined(__cpp_lib_is_invocable) && __cpp_lib_is_invocable>=201703
+
+template<typename F, typename ... Args>
+using return_type_of_t = std::invoke_result_t<F, Args...>;
+
+#else
+// result_of is deprecated after C++17
+template<typename F, typename ... Args>
+using return_type_of_t = typename std::result_of<F(Args...)>::type;
+
+#endif
+
+// ---------------------------------------------------------------------------
+// is_string_literal
+//
+// to use this, pass `typename remove_reference<T>::type` to T.
+
+template<typename T>
+struct is_string_literal:
+disjunction<
+    std::is_same<const char*, T>,
+    conjunction<
+        std::is_array<T>,
+        std::is_same<const char, typename std::remove_extent<T>::type>
+        >
+    >{};
+
+// ---------------------------------------------------------------------------
+// C++20 remove_cvref_t
+
+template<typename T>
+struct remove_cvref
+{
+    using type = typename std::remove_cv<
+        typename std::remove_reference<T>::type>::type;
+};
+
+template<typename T>
+using remove_cvref_t = typename remove_cvref<T>::type;
+
+}// detail
+}//toml
+#endif // TOML_TRAITS
diff --git a/src/toml11/toml/types.hpp b/src/toml11/toml/types.hpp
new file mode 100644
index 000000000..1e420e7fd
--- /dev/null
+++ b/src/toml11/toml/types.hpp
@@ -0,0 +1,173 @@
+//     Copyright Toru Niina 2017.
+// Distributed under the MIT License.
+#ifndef TOML11_TYPES_HPP
+#define TOML11_TYPES_HPP
+#include <unordered_map>
+#include <vector>
+
+#include "comments.hpp"
+#include "datetime.hpp"
+#include "string.hpp"
+#include "traits.hpp"
+
+namespace toml
+{
+
+template<typename Comment, // discard/preserve_comment
+         template<typename ...> class Table, // map-like class
+         template<typename ...> class Array> // vector-like class
+class basic_value;
+
+using character = char;
+using key = std::string;
+
+#if !defined(__clang__) && defined(__GNUC__) && __GNUC__ <= 4
+#  pragma GCC diagnostic push
+#  pragma GCC diagnostic ignored "-Wshadow"
+#endif
+
+using boolean        = bool;
+using integer        = std::int64_t;
+using floating       = double; // "float" is a keyword, cannot use it here.
+// the following stuffs are structs defined here, so aliases are not needed.
+// - string
+// - offset_datetime
+// - offset_datetime
+// - local_datetime
+// - local_date
+// - local_time
+
+#if defined(__GNUC__) && !defined(__clang__)
+#  pragma GCC diagnostic pop
+#endif
+
+// default toml::value and default array/table. these are defined after defining
+// basic_value itself.
+// using value = basic_value<discard_comments, std::unordered_map, std::vector>;
+// using array = typename value::array_type;
+// using table = typename value::table_type;
+
+// to avoid warnings about `value_t::integer` is "shadowing" toml::integer in
+// GCC -Wshadow=global.
+#if defined(__GNUC__) && !defined(__clang__)
+#  pragma GCC diagnostic push
+#  if 7 <= __GNUC__
+#    pragma GCC diagnostic ignored "-Wshadow=global"
+#  else // gcc-6 or older
+#    pragma GCC diagnostic ignored "-Wshadow"
+#  endif
+#endif
+enum class value_t : std::uint8_t
+{
+    empty           =  0,
+    boolean         =  1,
+    integer         =  2,
+    floating        =  3,
+    string          =  4,
+    offset_datetime =  5,
+    local_datetime  =  6,
+    local_date      =  7,
+    local_time      =  8,
+    array           =  9,
+    table           = 10,
+};
+#if defined(__GNUC__) && !defined(__clang__)
+#  pragma GCC diagnostic pop
+#endif
+
+template<typename charT, typename traits>
+inline std::basic_ostream<charT, traits>&
+operator<<(std::basic_ostream<charT, traits>& os, value_t t)
+{
+    switch(t)
+    {
+        case value_t::boolean         : os << "boolean";         return os;
+        case value_t::integer         : os << "integer";         return os;
+        case value_t::floating        : os << "floating";        return os;
+        case value_t::string          : os << "string";          return os;
+        case value_t::offset_datetime : os << "offset_datetime"; return os;
+        case value_t::local_datetime  : os << "local_datetime";  return os;
+        case value_t::local_date      : os << "local_date";      return os;
+        case value_t::local_time      : os << "local_time";      return os;
+        case value_t::array           : os << "array";           return os;
+        case value_t::table           : os << "table";           return os;
+        case value_t::empty           : os << "empty";           return os;
+        default                       : os << "unknown";         return os;
+    }
+}
+
+template<typename charT = char,
+         typename traits = std::char_traits<charT>,
+         typename alloc = std::allocator<charT>>
+inline std::basic_string<charT, traits, alloc> stringize(value_t t)
+{
+    std::basic_ostringstream<charT, traits, alloc> oss;
+    oss << t;
+    return oss.str();
+}
+
+namespace detail
+{
+
+// helper to define a type that represents a value_t value.
+template<value_t V>
+using value_t_constant = std::integral_constant<value_t, V>;
+
+// meta-function that convertes from value_t to the exact toml type that corresponds to.
+// It takes toml::basic_value type because array and table types depend on it.
+template<value_t t, typename Value> struct enum_to_type                      {using type = void                      ;};
+template<typename Value> struct enum_to_type<value_t::empty          , Value>{using type = void                      ;};
+template<typename Value> struct enum_to_type<value_t::boolean        , Value>{using type = boolean                   ;};
+template<typename Value> struct enum_to_type<value_t::integer        , Value>{using type = integer                   ;};
+template<typename Value> struct enum_to_type<value_t::floating       , Value>{using type = floating                  ;};
+template<typename Value> struct enum_to_type<value_t::string         , Value>{using type = string                    ;};
+template<typename Value> struct enum_to_type<value_t::offset_datetime, Value>{using type = offset_datetime           ;};
+template<typename Value> struct enum_to_type<value_t::local_datetime , Value>{using type = local_datetime            ;};
+template<typename Value> struct enum_to_type<value_t::local_date     , Value>{using type = local_date                ;};
+template<typename Value> struct enum_to_type<value_t::local_time     , Value>{using type = local_time                ;};
+template<typename Value> struct enum_to_type<value_t::array          , Value>{using type = typename Value::array_type;};
+template<typename Value> struct enum_to_type<value_t::table          , Value>{using type = typename Value::table_type;};
+
+// meta-function that converts from an exact toml type to the enum that corresponds to.
+template<typename T, typename Value>
+struct type_to_enum : std::conditional<
+    std::is_same<T, typename Value::array_type>::value, // if T == array_type,
+    value_t_constant<value_t::array>,                   // then value_t::array
+    typename std::conditional<                          // else...
+        std::is_same<T, typename Value::table_type>::value, // if T == table_type
+        value_t_constant<value_t::table>,               // then value_t::table
+        value_t_constant<value_t::empty>                // else value_t::empty
+        >::type
+    >::type {};
+template<typename Value> struct type_to_enum<boolean        , Value>: value_t_constant<value_t::boolean        > {};
+template<typename Value> struct type_to_enum<integer        , Value>: value_t_constant<value_t::integer        > {};
+template<typename Value> struct type_to_enum<floating       , Value>: value_t_constant<value_t::floating       > {};
+template<typename Value> struct type_to_enum<string         , Value>: value_t_constant<value_t::string         > {};
+template<typename Value> struct type_to_enum<offset_datetime, Value>: value_t_constant<value_t::offset_datetime> {};
+template<typename Value> struct type_to_enum<local_datetime , Value>: value_t_constant<value_t::local_datetime > {};
+template<typename Value> struct type_to_enum<local_date     , Value>: value_t_constant<value_t::local_date     > {};
+template<typename Value> struct type_to_enum<local_time     , Value>: value_t_constant<value_t::local_time     > {};
+
+// meta-function that checks the type T is the same as one of the toml::* types.
+template<typename T, typename Value>
+struct is_exact_toml_type : disjunction<
+    std::is_same<T, boolean        >,
+    std::is_same<T, integer        >,
+    std::is_same<T, floating       >,
+    std::is_same<T, string         >,
+    std::is_same<T, offset_datetime>,
+    std::is_same<T, local_datetime >,
+    std::is_same<T, local_date     >,
+    std::is_same<T, local_time     >,
+    std::is_same<T, typename Value::array_type>,
+    std::is_same<T, typename Value::table_type>
+    >{};
+template<typename T, typename V> struct is_exact_toml_type<T&, V>               : is_exact_toml_type<T, V>{};
+template<typename T, typename V> struct is_exact_toml_type<T const&, V>         : is_exact_toml_type<T, V>{};
+template<typename T, typename V> struct is_exact_toml_type<T volatile&, V>      : is_exact_toml_type<T, V>{};
+template<typename T, typename V> struct is_exact_toml_type<T const volatile&, V>: is_exact_toml_type<T, V>{};
+
+} // detail
+} // toml
+
+#endif// TOML11_TYPES_H
diff --git a/src/toml11/toml/utility.hpp b/src/toml11/toml/utility.hpp
new file mode 100644
index 000000000..4a6b4309d
--- /dev/null
+++ b/src/toml11/toml/utility.hpp
@@ -0,0 +1,149 @@
+//     Copyright Toru Niina 2017.
+// Distributed under the MIT License.
+#ifndef TOML11_UTILITY_HPP
+#define TOML11_UTILITY_HPP
+#include <memory>
+#include <sstream>
+#include <utility>
+
+#include "traits.hpp"
+
+#if __cplusplus >= 201402L
+#  define TOML11_MARK_AS_DEPRECATED(msg) [[deprecated(msg)]]
+#elif defined(__GNUC__)
+#  define TOML11_MARK_AS_DEPRECATED(msg) __attribute__((deprecated(msg)))
+#elif defined(_MSC_VER)
+#  define TOML11_MARK_AS_DEPRECATED(msg) __declspec(deprecated(msg))
+#else
+#  define TOML11_MARK_AS_DEPRECATED
+#endif
+
+namespace toml
+{
+
+#if __cplusplus >= 201402L
+
+using std::make_unique;
+
+#else
+
+template<typename T, typename ... Ts>
+inline std::unique_ptr<T> make_unique(Ts&& ... args)
+{
+    return std::unique_ptr<T>(new T(std::forward<Ts>(args)...));
+}
+
+#endif // __cplusplus >= 2014
+
+namespace detail
+{
+template<typename Container>
+void try_reserve_impl(Container& container, std::size_t N, std::true_type)
+{
+    container.reserve(N);
+    return;
+}
+template<typename Container>
+void try_reserve_impl(Container&, std::size_t, std::false_type) noexcept
+{
+    return;
+}
+} // detail
+
+template<typename Container>
+void try_reserve(Container& container, std::size_t N)
+{
+    if(N <= container.size()) {return;}
+    detail::try_reserve_impl(container, N, detail::has_reserve_method<Container>{});
+    return;
+}
+
+namespace detail
+{
+inline std::string concat_to_string_impl(std::ostringstream& oss)
+{
+    return oss.str();
+}
+template<typename T, typename ... Ts>
+std::string concat_to_string_impl(std::ostringstream& oss, T&& head, Ts&& ... tail)
+{
+    oss << std::forward<T>(head);
+    return concat_to_string_impl(oss, std::forward<Ts>(tail) ... );
+}
+} // detail
+
+template<typename ... Ts>
+std::string concat_to_string(Ts&& ... args)
+{
+    std::ostringstream oss;
+    oss << std::boolalpha << std::fixed;
+    return detail::concat_to_string_impl(oss, std::forward<Ts>(args) ...);
+}
+
+template<typename T>
+T from_string(const std::string& str, T opt)
+{
+    T v(opt);
+    std::istringstream iss(str);
+    iss >> v;
+    return v;
+}
+
+namespace detail
+{
+#if __cplusplus >= 201402L
+template<typename T>
+decltype(auto) last_one(T&& tail) noexcept
+{
+    return std::forward<T>(tail);
+}
+
+template<typename T, typename ... Ts>
+decltype(auto) last_one(T&& /*head*/, Ts&& ... tail) noexcept
+{
+    return last_one(std::forward<Ts>(tail)...);
+}
+#else // C++11
+// The following code
+// ```cpp
+//  1 | template<typename T, typename ... Ts>
+//  2 | auto last_one(T&& /*head*/, Ts&& ... tail)
+//  3 |  -> decltype(last_one(std::forward<Ts>(tail)...))
+//  4 | {
+//  5 |     return last_one(std::forward<Ts>(tail)...);
+//  6 | }
+// ```
+// does not work because the function `last_one(...)` is not yet defined at
+// line #3, so `decltype()` cannot deduce the type returned from `last_one`.
+// So we need to determine return type in a different way, like a meta func.
+
+template<typename T, typename ... Ts>
+struct last_one_in_pack
+{
+    using type = typename last_one_in_pack<Ts...>::type;
+};
+template<typename T>
+struct last_one_in_pack<T>
+{
+    using type = T;
+};
+template<typename ... Ts>
+using last_one_in_pack_t = typename last_one_in_pack<Ts...>::type;
+
+template<typename T>
+T&& last_one(T&& tail) noexcept
+{
+    return std::forward<T>(tail);
+}
+template<typename T, typename ... Ts>
+enable_if_t<(sizeof...(Ts) > 0), last_one_in_pack_t<Ts&& ...>>
+last_one(T&& /*head*/, Ts&& ... tail)
+{
+    return last_one(std::forward<Ts>(tail)...);
+}
+
+#endif
+} // detail
+
+}// toml
+#endif // TOML11_UTILITY
diff --git a/src/toml11/toml/value.hpp b/src/toml11/toml/value.hpp
new file mode 100644
index 000000000..1b43db8d4
--- /dev/null
+++ b/src/toml11/toml/value.hpp
@@ -0,0 +1,2035 @@
+//     Copyright Toru Niina 2017.
+// Distributed under the MIT License.
+#ifndef TOML11_VALUE_HPP
+#define TOML11_VALUE_HPP
+#include <cassert>
+
+#include "comments.hpp"
+#include "exception.hpp"
+#include "into.hpp"
+#include "region.hpp"
+#include "source_location.hpp"
+#include "storage.hpp"
+#include "traits.hpp"
+#include "types.hpp"
+#include "utility.hpp"
+
+namespace toml
+{
+
+namespace detail
+{
+
+// to show error messages. not recommended for users.
+template<typename Value>
+inline region_base const* get_region(const Value& v)
+{
+    return v.region_info_.get();
+}
+
+template<typename Value>
+void change_region(Value& v, region reg)
+{
+    v.region_info_ = std::make_shared<region>(std::move(reg));
+    return;
+}
+
+template<value_t Expected, typename Value>
+[[noreturn]] inline void
+throw_bad_cast(const std::string& funcname, value_t actual, const Value& v)
+{
+    throw type_error(detail::format_underline(
+        concat_to_string(funcname, "bad_cast to ", Expected), {
+            {v.location(), concat_to_string("the actual type is ", actual)}
+        }), v.location());
+}
+
+// Throw `out_of_range` from `toml::value::at()` and `toml::find()`
+// after generating an error message.
+//
+// The implementation is a bit complicated and there are many edge-cases.
+// If you are not interested in the error message generation, just skip this.
+template<typename Value>
+[[noreturn]] void
+throw_key_not_found_error(const Value& v, const key& ky)
+{
+    // The top-level table has its region at the first character of the file.
+    // That means that, in the case when a key is not found in the top-level
+    // table, the error message points to the first character. If the file has
+    // its first table at the first line, the error message would be like this.
+    // ```console
+    // [error] key "a" not found
+    //  --> example.toml
+    //    |
+    //  1 | [table]
+    //    | ^------ in this table
+    // ```
+    // It actually points to the top-level table at the first character,
+    // not `[table]`. But it is too confusing. To avoid the confusion, the error
+    // message should explicitly say "key not found in the top-level table",
+    // or "the parsed file is empty" if there is no content at all (0 bytes in file).
+    const auto loc = v.location();
+    if(loc.line() == 1 && loc.region() == 0)
+    {
+        // First line with a zero-length region means "empty file".
+        // The region will be generated at `parse_toml_file` function
+        // if the file contains no bytes.
+        throw std::out_of_range(format_underline(concat_to_string(
+            "key \"", ky, "\" not found in the top-level table"), {
+                {loc, "the parsed file is empty"}
+            }));
+    }
+    else if(loc.line() == 1 && loc.region() == 1)
+    {
+        // Here it assumes that top-level table starts at the first character.
+        // The region corresponds to the top-level table will be generated at
+        // `parse_toml_file` function.
+        //     It also assumes that the top-level table size is just one and
+        // the line number is `1`. It is always satisfied. And those conditions
+        // are satisfied only if the table is the top-level table.
+        //
+        // 1. one-character dot-key at the first line
+        // ```toml
+        // a.b = "c"
+        // ```
+        // toml11 counts whole key as the table key. Here, `a.b` is the region
+        // of the table "a". It could be counter intuitive, but it works.
+        // The size of the region is 3, not 1. The above example is the shortest
+        // dot-key example. The size cannot be 1.
+        //
+        // 2. one-character inline-table at the first line
+        // ```toml
+        // a = {b = "c"}
+        // ```
+        // toml11 considers the inline table body as the table region. Here,
+        // `{b = "c"}` is the region of the table "a". The size of the region
+        // is 9, not 1. The shotest inline table still has two characters, `{`
+        // and `}`. The size cannot be 1.
+        //
+        // 3. one-character table declaration at the first line
+        // ```toml
+        // [a]
+        // ```
+        // toml11 considers the whole table key as the table region. Here,
+        // `[a]` is the table region. The size is 3, not 1.
+        //
+        throw std::out_of_range(format_underline(concat_to_string(
+            "key \"", ky, "\" not found in the top-level table"), {
+                {loc, "the top-level table starts here"}
+            }));
+    }
+    else
+    {
+        // normal table.
+        throw std::out_of_range(format_underline(concat_to_string(
+            "key \"", ky, "\" not found"), { {loc, "in this table"} }));
+    }
+}
+
+// switch by `value_t` at the compile time.
+template<value_t T>
+struct switch_cast {};
+#define TOML11_GENERATE_SWITCH_CASTER(TYPE) \
+    template<>                                                           \
+    struct switch_cast<value_t::TYPE>                                    \
+    {                                                                    \
+        template<typename Value>                                         \
+        static typename Value::TYPE##_type& invoke(Value& v)             \
+        {                                                                \
+            return v.as_##TYPE();                                        \
+        }                                                                \
+        template<typename Value>                                         \
+        static typename Value::TYPE##_type const& invoke(const Value& v) \
+        {                                                                \
+            return v.as_##TYPE();                                        \
+        }                                                                \
+        template<typename Value>                                         \
+        static typename Value::TYPE##_type&& invoke(Value&& v)           \
+        {                                                                \
+            return std::move(v).as_##TYPE();                             \
+        }                                                                \
+    };                                                                   \
+    /**/
+TOML11_GENERATE_SWITCH_CASTER(boolean)
+TOML11_GENERATE_SWITCH_CASTER(integer)
+TOML11_GENERATE_SWITCH_CASTER(floating)
+TOML11_GENERATE_SWITCH_CASTER(string)
+TOML11_GENERATE_SWITCH_CASTER(offset_datetime)
+TOML11_GENERATE_SWITCH_CASTER(local_datetime)
+TOML11_GENERATE_SWITCH_CASTER(local_date)
+TOML11_GENERATE_SWITCH_CASTER(local_time)
+TOML11_GENERATE_SWITCH_CASTER(array)
+TOML11_GENERATE_SWITCH_CASTER(table)
+
+#undef TOML11_GENERATE_SWITCH_CASTER
+
+}// detail
+
+template<typename Comment, // discard/preserve_comment
+         template<typename ...> class Table = std::unordered_map,
+         template<typename ...> class Array = std::vector>
+class basic_value
+{
+    template<typename T, typename U>
+    static void assigner(T& dst, U&& v)
+    {
+        const auto tmp = ::new(std::addressof(dst)) T(std::forward<U>(v));
+        assert(tmp == std::addressof(dst));
+        (void)tmp;
+    }
+
+    using region_base = detail::region_base;
+
+    template<typename C, template<typename ...> class T,
+             template<typename ...> class A>
+    friend class basic_value;
+
+  public:
+
+    using comment_type         = Comment;
+    using key_type             = ::toml::key;
+    using value_type           = basic_value<comment_type, Table, Array>;
+    using boolean_type         = ::toml::boolean;
+    using integer_type         = ::toml::integer;
+    using floating_type        = ::toml::floating;
+    using string_type          = ::toml::string;
+    using local_time_type      = ::toml::local_time;
+    using local_date_type      = ::toml::local_date;
+    using local_datetime_type  = ::toml::local_datetime;
+    using offset_datetime_type = ::toml::offset_datetime;
+    using array_type           = Array<value_type>;
+    using table_type           = Table<key_type, value_type>;
+
+  public:
+
+    basic_value() noexcept
+        : type_(value_t::empty),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {}
+    ~basic_value() noexcept {this->cleanup();}
+
+    basic_value(const basic_value& v)
+        : type_(v.type()), region_info_(v.region_info_), comments_(v.comments_)
+    {
+        switch(v.type())
+        {
+            case value_t::boolean        : assigner(boolean_        , v.boolean_        ); break;
+            case value_t::integer        : assigner(integer_        , v.integer_        ); break;
+            case value_t::floating       : assigner(floating_       , v.floating_       ); break;
+            case value_t::string         : assigner(string_         , v.string_         ); break;
+            case value_t::offset_datetime: assigner(offset_datetime_, v.offset_datetime_); break;
+            case value_t::local_datetime : assigner(local_datetime_ , v.local_datetime_ ); break;
+            case value_t::local_date     : assigner(local_date_     , v.local_date_     ); break;
+            case value_t::local_time     : assigner(local_time_     , v.local_time_     ); break;
+            case value_t::array          : assigner(array_          , v.array_          ); break;
+            case value_t::table          : assigner(table_          , v.table_          ); break;
+            default: break;
+        }
+    }
+    basic_value(basic_value&& v)
+        : type_(v.type()), region_info_(std::move(v.region_info_)),
+          comments_(std::move(v.comments_))
+    {
+        switch(this->type_) // here this->type_ is already initialized
+        {
+            case value_t::boolean        : assigner(boolean_        , std::move(v.boolean_        )); break;
+            case value_t::integer        : assigner(integer_        , std::move(v.integer_        )); break;
+            case value_t::floating       : assigner(floating_       , std::move(v.floating_       )); break;
+            case value_t::string         : assigner(string_         , std::move(v.string_         )); break;
+            case value_t::offset_datetime: assigner(offset_datetime_, std::move(v.offset_datetime_)); break;
+            case value_t::local_datetime : assigner(local_datetime_ , std::move(v.local_datetime_ )); break;
+            case value_t::local_date     : assigner(local_date_     , std::move(v.local_date_     )); break;
+            case value_t::local_time     : assigner(local_time_     , std::move(v.local_time_     )); break;
+            case value_t::array          : assigner(array_          , std::move(v.array_          )); break;
+            case value_t::table          : assigner(table_          , std::move(v.table_          )); break;
+            default: break;
+        }
+    }
+    basic_value& operator=(const basic_value& v)
+    {
+        this->cleanup();
+        this->region_info_ = v.region_info_;
+        this->comments_ = v.comments_;
+        this->type_ = v.type();
+        switch(this->type_)
+        {
+            case value_t::boolean        : assigner(boolean_        , v.boolean_        ); break;
+            case value_t::integer        : assigner(integer_        , v.integer_        ); break;
+            case value_t::floating       : assigner(floating_       , v.floating_       ); break;
+            case value_t::string         : assigner(string_         , v.string_         ); break;
+            case value_t::offset_datetime: assigner(offset_datetime_, v.offset_datetime_); break;
+            case value_t::local_datetime : assigner(local_datetime_ , v.local_datetime_ ); break;
+            case value_t::local_date     : assigner(local_date_     , v.local_date_     ); break;
+            case value_t::local_time     : assigner(local_time_     , v.local_time_     ); break;
+            case value_t::array          : assigner(array_          , v.array_          ); break;
+            case value_t::table          : assigner(table_          , v.table_          ); break;
+            default: break;
+        }
+        return *this;
+    }
+    basic_value& operator=(basic_value&& v)
+    {
+        this->cleanup();
+        this->region_info_ = std::move(v.region_info_);
+        this->comments_ = std::move(v.comments_);
+        this->type_ = v.type();
+        switch(this->type_)
+        {
+            case value_t::boolean        : assigner(boolean_        , std::move(v.boolean_        )); break;
+            case value_t::integer        : assigner(integer_        , std::move(v.integer_        )); break;
+            case value_t::floating       : assigner(floating_       , std::move(v.floating_       )); break;
+            case value_t::string         : assigner(string_         , std::move(v.string_         )); break;
+            case value_t::offset_datetime: assigner(offset_datetime_, std::move(v.offset_datetime_)); break;
+            case value_t::local_datetime : assigner(local_datetime_ , std::move(v.local_datetime_ )); break;
+            case value_t::local_date     : assigner(local_date_     , std::move(v.local_date_     )); break;
+            case value_t::local_time     : assigner(local_time_     , std::move(v.local_time_     )); break;
+            case value_t::array          : assigner(array_          , std::move(v.array_          )); break;
+            case value_t::table          : assigner(table_          , std::move(v.table_          )); break;
+            default: break;
+        }
+        return *this;
+    }
+
+    // overwrite comments ----------------------------------------------------
+
+    basic_value(const basic_value& v, std::vector<std::string> com)
+        : type_(v.type()), region_info_(v.region_info_),
+          comments_(std::move(com))
+    {
+        switch(v.type())
+        {
+            case value_t::boolean        : assigner(boolean_        , v.boolean_        ); break;
+            case value_t::integer        : assigner(integer_        , v.integer_        ); break;
+            case value_t::floating       : assigner(floating_       , v.floating_       ); break;
+            case value_t::string         : assigner(string_         , v.string_         ); break;
+            case value_t::offset_datetime: assigner(offset_datetime_, v.offset_datetime_); break;
+            case value_t::local_datetime : assigner(local_datetime_ , v.local_datetime_ ); break;
+            case value_t::local_date     : assigner(local_date_     , v.local_date_     ); break;
+            case value_t::local_time     : assigner(local_time_     , v.local_time_     ); break;
+            case value_t::array          : assigner(array_          , v.array_          ); break;
+            case value_t::table          : assigner(table_          , v.table_          ); break;
+            default: break;
+        }
+    }
+
+    basic_value(basic_value&& v, std::vector<std::string> com)
+        : type_(v.type()), region_info_(std::move(v.region_info_)),
+          comments_(std::move(com))
+    {
+        switch(this->type_) // here this->type_ is already initialized
+        {
+            case value_t::boolean        : assigner(boolean_        , std::move(v.boolean_        )); break;
+            case value_t::integer        : assigner(integer_        , std::move(v.integer_        )); break;
+            case value_t::floating       : assigner(floating_       , std::move(v.floating_       )); break;
+            case value_t::string         : assigner(string_         , std::move(v.string_         )); break;
+            case value_t::offset_datetime: assigner(offset_datetime_, std::move(v.offset_datetime_)); break;
+            case value_t::local_datetime : assigner(local_datetime_ , std::move(v.local_datetime_ )); break;
+            case value_t::local_date     : assigner(local_date_     , std::move(v.local_date_     )); break;
+            case value_t::local_time     : assigner(local_time_     , std::move(v.local_time_     )); break;
+            case value_t::array          : assigner(array_          , std::move(v.array_          )); break;
+            case value_t::table          : assigner(table_          , std::move(v.table_          )); break;
+            default: break;
+        }
+    }
+
+    // -----------------------------------------------------------------------
+    // conversion between different basic_values.
+    template<typename C,
+             template<typename ...> class T,
+             template<typename ...> class A>
+    basic_value(const basic_value<C, T, A>& v)
+        : type_(v.type()), region_info_(v.region_info_), comments_(v.comments())
+    {
+        switch(v.type())
+        {
+            case value_t::boolean        : assigner(boolean_        , v.boolean_        ); break;
+            case value_t::integer        : assigner(integer_        , v.integer_        ); break;
+            case value_t::floating       : assigner(floating_       , v.floating_       ); break;
+            case value_t::string         : assigner(string_         , v.string_         ); break;
+            case value_t::offset_datetime: assigner(offset_datetime_, v.offset_datetime_); break;
+            case value_t::local_datetime : assigner(local_datetime_ , v.local_datetime_ ); break;
+            case value_t::local_date     : assigner(local_date_     , v.local_date_     ); break;
+            case value_t::local_time     : assigner(local_time_     , v.local_time_     ); break;
+            case value_t::array          :
+            {
+                array_type tmp(v.as_array(std::nothrow).begin(),
+                               v.as_array(std::nothrow).end());
+                assigner(array_, std::move(tmp));
+                break;
+            }
+            case value_t::table          :
+            {
+                table_type tmp(v.as_table(std::nothrow).begin(),
+                               v.as_table(std::nothrow).end());
+                assigner(table_, std::move(tmp));
+                break;
+            }
+            default: break;
+        }
+    }
+    template<typename C,
+             template<typename ...> class T,
+             template<typename ...> class A>
+    basic_value(const basic_value<C, T, A>& v, std::vector<std::string> com)
+        : type_(v.type()), region_info_(v.region_info_),
+          comments_(std::move(com))
+    {
+        switch(v.type())
+        {
+            case value_t::boolean        : assigner(boolean_        , v.boolean_        ); break;
+            case value_t::integer        : assigner(integer_        , v.integer_        ); break;
+            case value_t::floating       : assigner(floating_       , v.floating_       ); break;
+            case value_t::string         : assigner(string_         , v.string_         ); break;
+            case value_t::offset_datetime: assigner(offset_datetime_, v.offset_datetime_); break;
+            case value_t::local_datetime : assigner(local_datetime_ , v.local_datetime_ ); break;
+            case value_t::local_date     : assigner(local_date_     , v.local_date_     ); break;
+            case value_t::local_time     : assigner(local_time_     , v.local_time_     ); break;
+            case value_t::array          :
+            {
+                array_type tmp(v.as_array(std::nothrow).begin(),
+                               v.as_array(std::nothrow).end());
+                assigner(array_, std::move(tmp));
+                break;
+            }
+            case value_t::table          :
+            {
+                table_type tmp(v.as_table(std::nothrow).begin(),
+                               v.as_table(std::nothrow).end());
+                assigner(table_, std::move(tmp));
+                break;
+            }
+            default: break;
+        }
+    }
+    template<typename C,
+             template<typename ...> class T,
+             template<typename ...> class A>
+    basic_value& operator=(const basic_value<C, T, A>& v)
+    {
+        this->region_info_ = v.region_info_;
+        this->comments_    = comment_type(v.comments());
+        this->type_        = v.type();
+        switch(v.type())
+        {
+            case value_t::boolean        : assigner(boolean_        , v.boolean_        ); break;
+            case value_t::integer        : assigner(integer_        , v.integer_        ); break;
+            case value_t::floating       : assigner(floating_       , v.floating_       ); break;
+            case value_t::string         : assigner(string_         , v.string_         ); break;
+            case value_t::offset_datetime: assigner(offset_datetime_, v.offset_datetime_); break;
+            case value_t::local_datetime : assigner(local_datetime_ , v.local_datetime_ ); break;
+            case value_t::local_date     : assigner(local_date_     , v.local_date_     ); break;
+            case value_t::local_time     : assigner(local_time_     , v.local_time_     ); break;
+            case value_t::array          :
+            {
+                array_type tmp(v.as_array(std::nothrow).begin(),
+                               v.as_array(std::nothrow).end());
+                assigner(array_, std::move(tmp));
+                break;
+            }
+            case value_t::table          :
+            {
+                table_type tmp(v.as_table(std::nothrow).begin(),
+                               v.as_table(std::nothrow).end());
+                assigner(table_, std::move(tmp));
+                break;
+            }
+            default: break;
+        }
+        return *this;
+    }
+
+    // boolean ==============================================================
+
+    basic_value(boolean b)
+        : type_(value_t::boolean),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        assigner(this->boolean_, b);
+    }
+    basic_value& operator=(boolean b)
+    {
+        this->cleanup();
+        this->type_ = value_t::boolean;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+        assigner(this->boolean_, b);
+        return *this;
+    }
+    basic_value(boolean b, std::vector<std::string> com)
+        : type_(value_t::boolean),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        assigner(this->boolean_, b);
+    }
+
+    // integer ==============================================================
+
+    template<typename T, typename std::enable_if<detail::conjunction<
+        std::is_integral<T>, detail::negation<std::is_same<T, boolean>>>::value,
+        std::nullptr_t>::type = nullptr>
+    basic_value(T i)
+        : type_(value_t::integer),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        assigner(this->integer_, static_cast<integer>(i));
+    }
+
+    template<typename T, typename std::enable_if<detail::conjunction<
+        std::is_integral<T>, detail::negation<std::is_same<T, boolean>>>::value,
+        std::nullptr_t>::type = nullptr>
+    basic_value& operator=(T i)
+    {
+        this->cleanup();
+        this->type_ = value_t::integer;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+        assigner(this->integer_, static_cast<integer>(i));
+        return *this;
+    }
+
+    template<typename T, typename std::enable_if<detail::conjunction<
+        std::is_integral<T>, detail::negation<std::is_same<T, boolean>>>::value,
+        std::nullptr_t>::type = nullptr>
+    basic_value(T i, std::vector<std::string> com)
+        : type_(value_t::integer),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        assigner(this->integer_, static_cast<integer>(i));
+    }
+
+    // floating =============================================================
+
+    template<typename T, typename std::enable_if<
+        std::is_floating_point<T>::value, std::nullptr_t>::type = nullptr>
+    basic_value(T f)
+        : type_(value_t::floating),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        assigner(this->floating_, static_cast<floating>(f));
+    }
+
+
+    template<typename T, typename std::enable_if<
+        std::is_floating_point<T>::value, std::nullptr_t>::type = nullptr>
+    basic_value& operator=(T f)
+    {
+        this->cleanup();
+        this->type_ = value_t::floating;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+        assigner(this->floating_, static_cast<floating>(f));
+        return *this;
+    }
+
+    template<typename T, typename std::enable_if<
+        std::is_floating_point<T>::value, std::nullptr_t>::type = nullptr>
+    basic_value(T f, std::vector<std::string> com)
+        : type_(value_t::floating),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        assigner(this->floating_, f);
+    }
+
+    // string ===============================================================
+
+    basic_value(toml::string s)
+        : type_(value_t::string),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        assigner(this->string_, std::move(s));
+    }
+    basic_value& operator=(toml::string s)
+    {
+        this->cleanup();
+        this->type_ = value_t::string ;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+        assigner(this->string_, s);
+        return *this;
+    }
+    basic_value(toml::string s, std::vector<std::string> com)
+        : type_(value_t::string),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        assigner(this->string_, std::move(s));
+    }
+
+    basic_value(std::string s)
+        : type_(value_t::string),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        assigner(this->string_, toml::string(std::move(s)));
+    }
+    basic_value& operator=(std::string s)
+    {
+        this->cleanup();
+        this->type_ = value_t::string ;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+        assigner(this->string_, toml::string(std::move(s)));
+        return *this;
+    }
+    basic_value(std::string s, string_t kind)
+        : type_(value_t::string),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        assigner(this->string_, toml::string(std::move(s), kind));
+    }
+    basic_value(std::string s, std::vector<std::string> com)
+        : type_(value_t::string),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        assigner(this->string_, toml::string(std::move(s)));
+    }
+    basic_value(std::string s, string_t kind, std::vector<std::string> com)
+        : type_(value_t::string),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        assigner(this->string_, toml::string(std::move(s), kind));
+    }
+
+    basic_value(const char* s)
+        : type_(value_t::string),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        assigner(this->string_, toml::string(std::string(s)));
+    }
+    basic_value& operator=(const char* s)
+    {
+        this->cleanup();
+        this->type_ = value_t::string ;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+        assigner(this->string_, toml::string(std::string(s)));
+        return *this;
+    }
+    basic_value(const char* s, string_t kind)
+        : type_(value_t::string),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        assigner(this->string_, toml::string(std::string(s), kind));
+    }
+    basic_value(const char* s, std::vector<std::string> com)
+        : type_(value_t::string),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        assigner(this->string_, toml::string(std::string(s)));
+    }
+    basic_value(const char* s, string_t kind, std::vector<std::string> com)
+        : type_(value_t::string),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        assigner(this->string_, toml::string(std::string(s), kind));
+    }
+
+#if defined(TOML11_USING_STRING_VIEW) && TOML11_USING_STRING_VIEW>0
+    basic_value(std::string_view s)
+        : type_(value_t::string),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        assigner(this->string_, toml::string(s));
+    }
+    basic_value& operator=(std::string_view s)
+    {
+        this->cleanup();
+        this->type_ = value_t::string ;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+        assigner(this->string_, toml::string(s));
+        return *this;
+    }
+    basic_value(std::string_view s, std::vector<std::string> com)
+        : type_(value_t::string),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        assigner(this->string_, toml::string(s));
+    }
+    basic_value(std::string_view s, string_t kind)
+        : type_(value_t::string),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        assigner(this->string_, toml::string(s, kind));
+    }
+    basic_value(std::string_view s, string_t kind, std::vector<std::string> com)
+        : type_(value_t::string),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        assigner(this->string_, toml::string(s, kind));
+    }
+#endif
+
+    // local date ===========================================================
+
+    basic_value(const local_date& ld)
+        : type_(value_t::local_date),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        assigner(this->local_date_, ld);
+    }
+    basic_value& operator=(const local_date& ld)
+    {
+        this->cleanup();
+        this->type_ = value_t::local_date;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+        assigner(this->local_date_, ld);
+        return *this;
+    }
+    basic_value(const local_date& ld, std::vector<std::string> com)
+        : type_(value_t::local_date),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        assigner(this->local_date_, ld);
+    }
+
+    // local time ===========================================================
+
+    basic_value(const local_time& lt)
+        : type_(value_t::local_time),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        assigner(this->local_time_, lt);
+    }
+    basic_value(const local_time& lt, std::vector<std::string> com)
+        : type_(value_t::local_time),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        assigner(this->local_time_, lt);
+    }
+    basic_value& operator=(const local_time& lt)
+    {
+        this->cleanup();
+        this->type_ = value_t::local_time;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+        assigner(this->local_time_, lt);
+        return *this;
+    }
+
+    template<typename Rep, typename Period>
+    basic_value(const std::chrono::duration<Rep, Period>& dur)
+        : type_(value_t::local_time),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        assigner(this->local_time_, local_time(dur));
+    }
+    template<typename Rep, typename Period>
+    basic_value(const std::chrono::duration<Rep, Period>& dur,
+                std::vector<std::string> com)
+        : type_(value_t::local_time),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        assigner(this->local_time_, local_time(dur));
+    }
+    template<typename Rep, typename Period>
+    basic_value& operator=(const std::chrono::duration<Rep, Period>& dur)
+    {
+        this->cleanup();
+        this->type_ = value_t::local_time;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+        assigner(this->local_time_, local_time(dur));
+        return *this;
+    }
+
+    // local datetime =======================================================
+
+    basic_value(const local_datetime& ldt)
+        : type_(value_t::local_datetime),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        assigner(this->local_datetime_, ldt);
+    }
+    basic_value(const local_datetime& ldt, std::vector<std::string> com)
+        : type_(value_t::local_datetime),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        assigner(this->local_datetime_, ldt);
+    }
+    basic_value& operator=(const local_datetime& ldt)
+    {
+        this->cleanup();
+        this->type_ = value_t::local_datetime;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+        assigner(this->local_datetime_, ldt);
+        return *this;
+    }
+
+    // offset datetime ======================================================
+
+    basic_value(const offset_datetime& odt)
+        : type_(value_t::offset_datetime),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        assigner(this->offset_datetime_, odt);
+    }
+    basic_value(const offset_datetime& odt, std::vector<std::string> com)
+        : type_(value_t::offset_datetime),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        assigner(this->offset_datetime_, odt);
+    }
+    basic_value& operator=(const offset_datetime& odt)
+    {
+        this->cleanup();
+        this->type_ = value_t::offset_datetime;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+        assigner(this->offset_datetime_, odt);
+        return *this;
+    }
+    basic_value(const std::chrono::system_clock::time_point& tp)
+        : type_(value_t::offset_datetime),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        assigner(this->offset_datetime_, offset_datetime(tp));
+    }
+    basic_value(const std::chrono::system_clock::time_point& tp,
+                std::vector<std::string> com)
+        : type_(value_t::offset_datetime),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        assigner(this->offset_datetime_, offset_datetime(tp));
+    }
+    basic_value& operator=(const std::chrono::system_clock::time_point& tp)
+    {
+        this->cleanup();
+        this->type_ = value_t::offset_datetime;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+        assigner(this->offset_datetime_, offset_datetime(tp));
+        return *this;
+    }
+
+    // array ================================================================
+
+    basic_value(const array_type& ary)
+        : type_(value_t::array),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        assigner(this->array_, ary);
+    }
+    basic_value(const array_type& ary, std::vector<std::string> com)
+        : type_(value_t::array),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        assigner(this->array_, ary);
+    }
+    basic_value& operator=(const array_type& ary)
+    {
+        this->cleanup();
+        this->type_ = value_t::array ;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+        assigner(this->array_, ary);
+        return *this;
+    }
+
+    // array (initializer_list) ----------------------------------------------
+
+    template<typename T, typename std::enable_if<
+            std::is_convertible<T, value_type>::value,
+        std::nullptr_t>::type = nullptr>
+    basic_value(std::initializer_list<T> list)
+        : type_(value_t::array),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        array_type ary(list.begin(), list.end());
+        assigner(this->array_, std::move(ary));
+    }
+    template<typename T, typename std::enable_if<
+            std::is_convertible<T, value_type>::value,
+        std::nullptr_t>::type = nullptr>
+    basic_value(std::initializer_list<T> list, std::vector<std::string> com)
+        : type_(value_t::array),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        array_type ary(list.begin(), list.end());
+        assigner(this->array_, std::move(ary));
+    }
+    template<typename T, typename std::enable_if<
+            std::is_convertible<T, value_type>::value,
+        std::nullptr_t>::type = nullptr>
+    basic_value& operator=(std::initializer_list<T> list)
+    {
+        this->cleanup();
+        this->type_ = value_t::array;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+
+        array_type ary(list.begin(), list.end());
+        assigner(this->array_, std::move(ary));
+        return *this;
+    }
+
+    // array (STL Containers) ------------------------------------------------
+
+    template<typename T, typename std::enable_if<detail::conjunction<
+            detail::negation<std::is_same<T, array_type>>,
+            detail::is_container<T>
+        >::value, std::nullptr_t>::type = nullptr>
+    basic_value(const T& list)
+        : type_(value_t::array),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        static_assert(std::is_convertible<typename T::value_type, value_type>::value,
+            "elements of a container should be convertible to toml::value");
+
+        array_type ary(list.size());
+        std::copy(list.begin(), list.end(), ary.begin());
+        assigner(this->array_, std::move(ary));
+    }
+    template<typename T, typename std::enable_if<detail::conjunction<
+            detail::negation<std::is_same<T, array_type>>,
+            detail::is_container<T>
+        >::value, std::nullptr_t>::type = nullptr>
+    basic_value(const T& list, std::vector<std::string> com)
+        : type_(value_t::array),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        static_assert(std::is_convertible<typename T::value_type, value_type>::value,
+            "elements of a container should be convertible to toml::value");
+
+        array_type ary(list.size());
+        std::copy(list.begin(), list.end(), ary.begin());
+        assigner(this->array_, std::move(ary));
+    }
+    template<typename T, typename std::enable_if<detail::conjunction<
+            detail::negation<std::is_same<T, array_type>>,
+            detail::is_container<T>
+        >::value, std::nullptr_t>::type = nullptr>
+    basic_value& operator=(const T& list)
+    {
+        static_assert(std::is_convertible<typename T::value_type, value_type>::value,
+            "elements of a container should be convertible to toml::value");
+
+        this->cleanup();
+        this->type_ = value_t::array;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+
+        array_type ary(list.size());
+        std::copy(list.begin(), list.end(), ary.begin());
+        assigner(this->array_, std::move(ary));
+        return *this;
+    }
+
+    // table ================================================================
+
+    basic_value(const table_type& tab)
+        : type_(value_t::table),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        assigner(this->table_, tab);
+    }
+    basic_value(const table_type& tab, std::vector<std::string> com)
+        : type_(value_t::table),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        assigner(this->table_, tab);
+    }
+    basic_value& operator=(const table_type& tab)
+    {
+        this->cleanup();
+        this->type_ = value_t::table;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+        assigner(this->table_, tab);
+        return *this;
+    }
+
+    // initializer-list ------------------------------------------------------
+
+    basic_value(std::initializer_list<std::pair<key, basic_value>> list)
+        : type_(value_t::table),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        table_type tab;
+        for(const auto& elem : list) {tab[elem.first] = elem.second;}
+        assigner(this->table_, std::move(tab));
+    }
+
+    basic_value(std::initializer_list<std::pair<key, basic_value>> list,
+                std::vector<std::string> com)
+        : type_(value_t::table),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        table_type tab;
+        for(const auto& elem : list) {tab[elem.first] = elem.second;}
+        assigner(this->table_, std::move(tab));
+    }
+    basic_value& operator=(std::initializer_list<std::pair<key, basic_value>> list)
+    {
+        this->cleanup();
+        this->type_ = value_t::table;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+
+        table_type tab;
+        for(const auto& elem : list) {tab[elem.first] = elem.second;}
+        assigner(this->table_, std::move(tab));
+        return *this;
+    }
+
+    // other table-like -----------------------------------------------------
+
+    template<typename Map, typename std::enable_if<detail::conjunction<
+            detail::negation<std::is_same<Map, table_type>>,
+            detail::is_map<Map>
+        >::value, std::nullptr_t>::type = nullptr>
+    basic_value(const Map& mp)
+        : type_(value_t::table),
+          region_info_(std::make_shared<region_base>(region_base{}))
+    {
+        table_type tab;
+        for(const auto& elem : mp) {tab[elem.first] = elem.second;}
+        assigner(this->table_, std::move(tab));
+    }
+    template<typename Map, typename std::enable_if<detail::conjunction<
+            detail::negation<std::is_same<Map, table_type>>,
+            detail::is_map<Map>
+        >::value, std::nullptr_t>::type = nullptr>
+    basic_value(const Map& mp, std::vector<std::string> com)
+        : type_(value_t::table),
+          region_info_(std::make_shared<region_base>(region_base{})),
+          comments_(std::move(com))
+    {
+        table_type tab;
+        for(const auto& elem : mp) {tab[elem.first] = elem.second;}
+        assigner(this->table_, std::move(tab));
+    }
+    template<typename Map, typename std::enable_if<detail::conjunction<
+            detail::negation<std::is_same<Map, table_type>>,
+            detail::is_map<Map>
+        >::value, std::nullptr_t>::type = nullptr>
+    basic_value& operator=(const Map& mp)
+    {
+        this->cleanup();
+        this->type_ = value_t::table;
+        this->region_info_ = std::make_shared<region_base>(region_base{});
+
+        table_type tab;
+        for(const auto& elem : mp) {tab[elem.first] = elem.second;}
+        assigner(this->table_, std::move(tab));
+        return *this;
+    }
+
+    // user-defined =========================================================
+
+    // convert using into_toml() method -------------------------------------
+
+    template<typename T, typename std::enable_if<
+        detail::has_into_toml_method<T>::value, std::nullptr_t>::type = nullptr>
+    basic_value(const T& ud): basic_value(ud.into_toml()) {}
+
+    template<typename T, typename std::enable_if<
+        detail::has_into_toml_method<T>::value, std::nullptr_t>::type = nullptr>
+    basic_value(const T& ud, std::vector<std::string> com)
+        : basic_value(ud.into_toml(), std::move(com))
+    {}
+    template<typename T, typename std::enable_if<
+        detail::has_into_toml_method<T>::value, std::nullptr_t>::type = nullptr>
+    basic_value& operator=(const T& ud)
+    {
+        *this = ud.into_toml();
+        return *this;
+    }
+
+    // convert using into<T> struct -----------------------------------------
+
+    template<typename T, std::size_t S = sizeof(::toml::into<T>)>
+    basic_value(const T& ud): basic_value(::toml::into<T>::into_toml(ud)) {}
+    template<typename T, std::size_t S = sizeof(::toml::into<T>)>
+    basic_value(const T& ud, std::vector<std::string> com)
+        : basic_value(::toml::into<T>::into_toml(ud), std::move(com))
+    {}
+    template<typename T, std::size_t S = sizeof(::toml::into<T>)>
+    basic_value& operator=(const T& ud)
+    {
+        *this = ::toml::into<T>::into_toml(ud);
+        return *this;
+    }
+
+    // for internal use ------------------------------------------------------
+    //
+    // Those constructors take detail::region that contains parse result.
+
+    basic_value(boolean b, detail::region reg, std::vector<std::string> cm)
+        : type_(value_t::boolean),
+          region_info_(std::make_shared<detail::region>(std::move(reg))),
+          comments_(std::move(cm))
+    {
+        assigner(this->boolean_, b);
+    }
+    template<typename T, typename std::enable_if<
+        detail::conjunction<
+            std::is_integral<T>, detail::negation<std::is_same<T, boolean>>
+        >::value, std::nullptr_t>::type = nullptr>
+    basic_value(T i, detail::region reg, std::vector<std::string> cm)
+        : type_(value_t::integer),
+          region_info_(std::make_shared<detail::region>(std::move(reg))),
+          comments_(std::move(cm))
+    {
+        assigner(this->integer_, static_cast<integer>(i));
+    }
+    template<typename T, typename std::enable_if<
+        std::is_floating_point<T>::value, std::nullptr_t>::type = nullptr>
+    basic_value(T f, detail::region reg, std::vector<std::string> cm)
+        : type_(value_t::floating),
+          region_info_(std::make_shared<detail::region>(std::move(reg))),
+          comments_(std::move(cm))
+    {
+        assigner(this->floating_, static_cast<floating>(f));
+    }
+    basic_value(toml::string s, detail::region reg,
+                std::vector<std::string> cm)
+        : type_(value_t::string),
+          region_info_(std::make_shared<detail::region>(std::move(reg))),
+          comments_(std::move(cm))
+    {
+        assigner(this->string_, std::move(s));
+    }
+    basic_value(const local_date& ld, detail::region reg,
+                std::vector<std::string> cm)
+        : type_(value_t::local_date),
+          region_info_(std::make_shared<detail::region>(std::move(reg))),
+          comments_(std::move(cm))
+    {
+        assigner(this->local_date_, ld);
+    }
+    basic_value(const local_time& lt, detail::region reg,
+                std::vector<std::string> cm)
+        : type_(value_t::local_time),
+          region_info_(std::make_shared<detail::region>(std::move(reg))),
+          comments_(std::move(cm))
+    {
+        assigner(this->local_time_, lt);
+    }
+    basic_value(const local_datetime& ldt, detail::region reg,
+                std::vector<std::string> cm)
+        : type_(value_t::local_datetime),
+          region_info_(std::make_shared<detail::region>(std::move(reg))),
+          comments_(std::move(cm))
+    {
+        assigner(this->local_datetime_, ldt);
+    }
+    basic_value(const offset_datetime& odt, detail::region reg,
+                std::vector<std::string> cm)
+        : type_(value_t::offset_datetime),
+          region_info_(std::make_shared<detail::region>(std::move(reg))),
+          comments_(std::move(cm))
+    {
+        assigner(this->offset_datetime_, odt);
+    }
+    basic_value(const array_type& ary, detail::region reg,
+                std::vector<std::string> cm)
+        : type_(value_t::array),
+          region_info_(std::make_shared<detail::region>(std::move(reg))),
+          comments_(std::move(cm))
+    {
+        assigner(this->array_, ary);
+    }
+    basic_value(const table_type& tab, detail::region reg,
+                std::vector<std::string> cm)
+        : type_(value_t::table),
+          region_info_(std::make_shared<detail::region>(std::move(reg))),
+          comments_(std::move(cm))
+    {
+        assigner(this->table_, tab);
+    }
+
+    template<typename T, typename std::enable_if<
+        detail::is_exact_toml_type<T, value_type>::value,
+        std::nullptr_t>::type = nullptr>
+    basic_value(std::pair<T, detail::region> parse_result, std::vector<std::string> com)
+        : basic_value(std::move(parse_result.first),
+                      std::move(parse_result.second),
+                      std::move(com))
+    {}
+
+    // type checking and casting ============================================
+
+    template<typename T, typename std::enable_if<
+        detail::is_exact_toml_type<T, value_type>::value,
+        std::nullptr_t>::type = nullptr>
+    bool is() const noexcept
+    {
+        return detail::type_to_enum<T, value_type>::value == this->type_;
+    }
+    bool is(value_t t) const noexcept {return t == this->type_;}
+
+    bool is_uninitialized()   const noexcept {return this->is(value_t::empty          );}
+    bool is_boolean()         const noexcept {return this->is(value_t::boolean        );}
+    bool is_integer()         const noexcept {return this->is(value_t::integer        );}
+    bool is_floating()        const noexcept {return this->is(value_t::floating       );}
+    bool is_string()          const noexcept {return this->is(value_t::string         );}
+    bool is_offset_datetime() const noexcept {return this->is(value_t::offset_datetime);}
+    bool is_local_datetime()  const noexcept {return this->is(value_t::local_datetime );}
+    bool is_local_date()      const noexcept {return this->is(value_t::local_date     );}
+    bool is_local_time()      const noexcept {return this->is(value_t::local_time     );}
+    bool is_array()           const noexcept {return this->is(value_t::array          );}
+    bool is_table()           const noexcept {return this->is(value_t::table          );}
+
+    value_t type() const noexcept {return type_;}
+
+    template<value_t T>
+    typename detail::enum_to_type<T, value_type>::type&       cast() &
+    {
+        if(this->type_ != T)
+        {
+            detail::throw_bad_cast<T>("toml::value::cast: ", this->type_, *this);
+        }
+        return detail::switch_cast<T>::invoke(*this);
+    }
+    template<value_t T>
+    typename detail::enum_to_type<T, value_type>::type const& cast() const&
+    {
+        if(this->type_ != T)
+        {
+            detail::throw_bad_cast<T>("toml::value::cast: ", this->type_, *this);
+        }
+        return detail::switch_cast<T>::invoke(*this);
+    }
+    template<value_t T>
+    typename detail::enum_to_type<T, value_type>::type&&      cast() &&
+    {
+        if(this->type_ != T)
+        {
+            detail::throw_bad_cast<T>("toml::value::cast: ", this->type_, *this);
+        }
+        return detail::switch_cast<T>::invoke(std::move(*this));
+    }
+
+    // ------------------------------------------------------------------------
+    // nothrow version
+
+    boolean         const& as_boolean        (const std::nothrow_t&) const& noexcept {return this->boolean_;}
+    integer         const& as_integer        (const std::nothrow_t&) const& noexcept {return this->integer_;}
+    floating        const& as_floating       (const std::nothrow_t&) const& noexcept {return this->floating_;}
+    string          const& as_string         (const std::nothrow_t&) const& noexcept {return this->string_;}
+    offset_datetime const& as_offset_datetime(const std::nothrow_t&) const& noexcept {return this->offset_datetime_;}
+    local_datetime  const& as_local_datetime (const std::nothrow_t&) const& noexcept {return this->local_datetime_;}
+    local_date      const& as_local_date     (const std::nothrow_t&) const& noexcept {return this->local_date_;}
+    local_time      const& as_local_time     (const std::nothrow_t&) const& noexcept {return this->local_time_;}
+    array_type      const& as_array          (const std::nothrow_t&) const& noexcept {return this->array_.value();}
+    table_type      const& as_table          (const std::nothrow_t&) const& noexcept {return this->table_.value();}
+
+    boolean        & as_boolean        (const std::nothrow_t&) & noexcept {return this->boolean_;}
+    integer        & as_integer        (const std::nothrow_t&) & noexcept {return this->integer_;}
+    floating       & as_floating       (const std::nothrow_t&) & noexcept {return this->floating_;}
+    string         & as_string         (const std::nothrow_t&) & noexcept {return this->string_;}
+    offset_datetime& as_offset_datetime(const std::nothrow_t&) & noexcept {return this->offset_datetime_;}
+    local_datetime & as_local_datetime (const std::nothrow_t&) & noexcept {return this->local_datetime_;}
+    local_date     & as_local_date     (const std::nothrow_t&) & noexcept {return this->local_date_;}
+    local_time     & as_local_time     (const std::nothrow_t&) & noexcept {return this->local_time_;}
+    array_type     & as_array          (const std::nothrow_t&) & noexcept {return this->array_.value();}
+    table_type     & as_table          (const std::nothrow_t&) & noexcept {return this->table_.value();}
+
+    boolean        && as_boolean        (const std::nothrow_t&) && noexcept {return std::move(this->boolean_);}
+    integer        && as_integer        (const std::nothrow_t&) && noexcept {return std::move(this->integer_);}
+    floating       && as_floating       (const std::nothrow_t&) && noexcept {return std::move(this->floating_);}
+    string         && as_string         (const std::nothrow_t&) && noexcept {return std::move(this->string_);}
+    offset_datetime&& as_offset_datetime(const std::nothrow_t&) && noexcept {return std::move(this->offset_datetime_);}
+    local_datetime && as_local_datetime (const std::nothrow_t&) && noexcept {return std::move(this->local_datetime_);}
+    local_date     && as_local_date     (const std::nothrow_t&) && noexcept {return std::move(this->local_date_);}
+    local_time     && as_local_time     (const std::nothrow_t&) && noexcept {return std::move(this->local_time_);}
+    array_type     && as_array          (const std::nothrow_t&) && noexcept {return std::move(this->array_.value());}
+    table_type     && as_table          (const std::nothrow_t&) && noexcept {return std::move(this->table_.value());}
+
+    // ========================================================================
+    // throw version
+    // ------------------------------------------------------------------------
+    // const reference {{{
+
+    boolean const& as_boolean() const&
+    {
+        if(this->type_ != value_t::boolean)
+        {
+            detail::throw_bad_cast<value_t::boolean>(
+                    "toml::value::as_boolean(): ", this->type_, *this);
+        }
+        return this->boolean_;
+    }
+    integer const& as_integer() const&
+    {
+        if(this->type_ != value_t::integer)
+        {
+            detail::throw_bad_cast<value_t::integer>(
+                    "toml::value::as_integer(): ", this->type_, *this);
+        }
+        return this->integer_;
+    }
+    floating const& as_floating() const&
+    {
+        if(this->type_ != value_t::floating)
+        {
+            detail::throw_bad_cast<value_t::floating>(
+                    "toml::value::as_floating(): ", this->type_, *this);
+        }
+        return this->floating_;
+    }
+    string const& as_string() const&
+    {
+        if(this->type_ != value_t::string)
+        {
+            detail::throw_bad_cast<value_t::string>(
+                    "toml::value::as_string(): ", this->type_, *this);
+        }
+        return this->string_;
+    }
+    offset_datetime const& as_offset_datetime() const&
+    {
+        if(this->type_ != value_t::offset_datetime)
+        {
+            detail::throw_bad_cast<value_t::offset_datetime>(
+                    "toml::value::as_offset_datetime(): ", this->type_, *this);
+        }
+        return this->offset_datetime_;
+    }
+    local_datetime const& as_local_datetime() const&
+    {
+        if(this->type_ != value_t::local_datetime)
+        {
+            detail::throw_bad_cast<value_t::local_datetime>(
+                    "toml::value::as_local_datetime(): ", this->type_, *this);
+        }
+        return this->local_datetime_;
+    }
+    local_date const& as_local_date() const&
+    {
+        if(this->type_ != value_t::local_date)
+        {
+            detail::throw_bad_cast<value_t::local_date>(
+                    "toml::value::as_local_date(): ", this->type_, *this);
+        }
+        return this->local_date_;
+    }
+    local_time const& as_local_time() const&
+    {
+        if(this->type_ != value_t::local_time)
+        {
+            detail::throw_bad_cast<value_t::local_time>(
+                    "toml::value::as_local_time(): ", this->type_, *this);
+        }
+        return this->local_time_;
+    }
+    array_type const& as_array() const&
+    {
+        if(this->type_ != value_t::array)
+        {
+            detail::throw_bad_cast<value_t::array>(
+                    "toml::value::as_array(): ", this->type_, *this);
+        }
+        return this->array_.value();
+    }
+    table_type const& as_table() const&
+    {
+        if(this->type_ != value_t::table)
+        {
+            detail::throw_bad_cast<value_t::table>(
+                    "toml::value::as_table(): ", this->type_, *this);
+        }
+        return this->table_.value();
+    }
+    // }}}
+    // ------------------------------------------------------------------------
+    // nonconst reference {{{
+
+    boolean & as_boolean() &
+    {
+        if(this->type_ != value_t::boolean)
+        {
+            detail::throw_bad_cast<value_t::boolean>(
+                    "toml::value::as_boolean(): ", this->type_, *this);
+        }
+        return this->boolean_;
+    }
+    integer & as_integer() &
+    {
+        if(this->type_ != value_t::integer)
+        {
+            detail::throw_bad_cast<value_t::integer>(
+                    "toml::value::as_integer(): ", this->type_, *this);
+        }
+        return this->integer_;
+    }
+    floating & as_floating() &
+    {
+        if(this->type_ != value_t::floating)
+        {
+            detail::throw_bad_cast<value_t::floating>(
+                    "toml::value::as_floating(): ", this->type_, *this);
+        }
+        return this->floating_;
+    }
+    string & as_string() &
+    {
+        if(this->type_ != value_t::string)
+        {
+            detail::throw_bad_cast<value_t::string>(
+                    "toml::value::as_string(): ", this->type_, *this);
+        }
+        return this->string_;
+    }
+    offset_datetime & as_offset_datetime() &
+    {
+        if(this->type_ != value_t::offset_datetime)
+        {
+            detail::throw_bad_cast<value_t::offset_datetime>(
+                    "toml::value::as_offset_datetime(): ", this->type_, *this);
+        }
+        return this->offset_datetime_;
+    }
+    local_datetime & as_local_datetime() &
+    {
+        if(this->type_ != value_t::local_datetime)
+        {
+            detail::throw_bad_cast<value_t::local_datetime>(
+                    "toml::value::as_local_datetime(): ", this->type_, *this);
+        }
+        return this->local_datetime_;
+    }
+    local_date & as_local_date() &
+    {
+        if(this->type_ != value_t::local_date)
+        {
+            detail::throw_bad_cast<value_t::local_date>(
+                    "toml::value::as_local_date(): ", this->type_, *this);
+        }
+        return this->local_date_;
+    }
+    local_time & as_local_time() &
+    {
+        if(this->type_ != value_t::local_time)
+        {
+            detail::throw_bad_cast<value_t::local_time>(
+                    "toml::value::as_local_time(): ", this->type_, *this);
+        }
+        return this->local_time_;
+    }
+    array_type & as_array() &
+    {
+        if(this->type_ != value_t::array)
+        {
+            detail::throw_bad_cast<value_t::array>(
+                    "toml::value::as_array(): ", this->type_, *this);
+        }
+        return this->array_.value();
+    }
+    table_type & as_table() &
+    {
+        if(this->type_ != value_t::table)
+        {
+            detail::throw_bad_cast<value_t::table>(
+                    "toml::value::as_table(): ", this->type_, *this);
+        }
+        return this->table_.value();
+    }
+
+    // }}}
+    // ------------------------------------------------------------------------
+    // rvalue reference {{{
+
+    boolean && as_boolean() &&
+    {
+        if(this->type_ != value_t::boolean)
+        {
+            detail::throw_bad_cast<value_t::boolean>(
+                    "toml::value::as_boolean(): ", this->type_, *this);
+        }
+        return std::move(this->boolean_);
+    }
+    integer && as_integer() &&
+    {
+        if(this->type_ != value_t::integer)
+        {
+            detail::throw_bad_cast<value_t::integer>(
+                    "toml::value::as_integer(): ", this->type_, *this);
+        }
+        return std::move(this->integer_);
+    }
+    floating && as_floating() &&
+    {
+        if(this->type_ != value_t::floating)
+        {
+            detail::throw_bad_cast<value_t::floating>(
+                    "toml::value::as_floating(): ", this->type_, *this);
+        }
+        return std::move(this->floating_);
+    }
+    string && as_string() &&
+    {
+        if(this->type_ != value_t::string)
+        {
+            detail::throw_bad_cast<value_t::string>(
+                    "toml::value::as_string(): ", this->type_, *this);
+        }
+        return std::move(this->string_);
+    }
+    offset_datetime && as_offset_datetime() &&
+    {
+        if(this->type_ != value_t::offset_datetime)
+        {
+            detail::throw_bad_cast<value_t::offset_datetime>(
+                    "toml::value::as_offset_datetime(): ", this->type_, *this);
+        }
+        return std::move(this->offset_datetime_);
+    }
+    local_datetime && as_local_datetime() &&
+    {
+        if(this->type_ != value_t::local_datetime)
+        {
+            detail::throw_bad_cast<value_t::local_datetime>(
+                    "toml::value::as_local_datetime(): ", this->type_, *this);
+        }
+        return std::move(this->local_datetime_);
+    }
+    local_date && as_local_date() &&
+    {
+        if(this->type_ != value_t::local_date)
+        {
+            detail::throw_bad_cast<value_t::local_date>(
+                    "toml::value::as_local_date(): ", this->type_, *this);
+        }
+        return std::move(this->local_date_);
+    }
+    local_time && as_local_time() &&
+    {
+        if(this->type_ != value_t::local_time)
+        {
+            detail::throw_bad_cast<value_t::local_time>(
+                    "toml::value::as_local_time(): ", this->type_, *this);
+        }
+        return std::move(this->local_time_);
+    }
+    array_type && as_array() &&
+    {
+        if(this->type_ != value_t::array)
+        {
+            detail::throw_bad_cast<value_t::array>(
+                    "toml::value::as_array(): ", this->type_, *this);
+        }
+        return std::move(this->array_.value());
+    }
+    table_type && as_table() &&
+    {
+        if(this->type_ != value_t::table)
+        {
+            detail::throw_bad_cast<value_t::table>(
+                    "toml::value::as_table(): ", this->type_, *this);
+        }
+        return std::move(this->table_.value());
+    }
+    // }}}
+
+    // accessors =============================================================
+    //
+    // may throw type_error or out_of_range
+    //
+    value_type&       at(const key& k)
+    {
+        if(!this->is_table())
+        {
+            detail::throw_bad_cast<value_t::table>(
+                "toml::value::at(key): ", this->type_, *this);
+        }
+        if(this->as_table(std::nothrow).count(k) == 0)
+        {
+            detail::throw_key_not_found_error(*this, k);
+        }
+        return this->as_table(std::nothrow).at(k);
+    }
+    value_type const& at(const key& k) const
+    {
+        if(!this->is_table())
+        {
+            detail::throw_bad_cast<value_t::table>(
+                "toml::value::at(key): ", this->type_, *this);
+        }
+        if(this->as_table(std::nothrow).count(k) == 0)
+        {
+            detail::throw_key_not_found_error(*this, k);
+        }
+        return this->as_table(std::nothrow).at(k);
+    }
+    value_type&       operator[](const key& k)
+    {
+        if(this->is_uninitialized())
+        {
+            *this = table_type{};
+        }
+        else if(!this->is_table()) // initialized, but not a table
+        {
+            detail::throw_bad_cast<value_t::table>(
+                "toml::value::operator[](key): ", this->type_, *this);
+        }
+        return this->as_table(std::nothrow)[k];
+    }
+
+    value_type&       at(const std::size_t idx)
+    {
+        if(!this->is_array())
+        {
+            detail::throw_bad_cast<value_t::array>(
+                "toml::value::at(idx): ", this->type_, *this);
+        }
+        if(this->as_array(std::nothrow).size() <= idx)
+        {
+            throw std::out_of_range(detail::format_underline(
+                "toml::value::at(idx): no element corresponding to the index", {
+                    {this->location(), concat_to_string("the length is ",
+                        this->as_array(std::nothrow).size(),
+                        ", and the specified index is ", idx)}
+                }));
+        }
+        return this->as_array().at(idx);
+    }
+    value_type const& at(const std::size_t idx) const
+    {
+        if(!this->is_array())
+        {
+            detail::throw_bad_cast<value_t::array>(
+                "toml::value::at(idx): ", this->type_, *this);
+        }
+        if(this->as_array(std::nothrow).size() <= idx)
+        {
+            throw std::out_of_range(detail::format_underline(
+                "toml::value::at(idx): no element corresponding to the index", {
+                    {this->location(), concat_to_string("the length is ",
+                        this->as_array(std::nothrow).size(),
+                        ", and the specified index is ", idx)}
+                }));
+        }
+        return this->as_array(std::nothrow).at(idx);
+    }
+
+    value_type&       operator[](const std::size_t idx) noexcept
+    {
+        // no check...
+        return this->as_array(std::nothrow)[idx];
+    }
+    value_type const& operator[](const std::size_t idx) const noexcept
+    {
+        // no check...
+        return this->as_array(std::nothrow)[idx];
+    }
+
+    void push_back(const value_type& x)
+    {
+        if(!this->is_array())
+        {
+            detail::throw_bad_cast<value_t::array>(
+                "toml::value::push_back(value): ", this->type_, *this);
+        }
+        this->as_array(std::nothrow).push_back(x);
+        return;
+    }
+    void push_back(value_type&& x)
+    {
+        if(!this->is_array())
+        {
+            detail::throw_bad_cast<value_t::array>(
+                "toml::value::push_back(value): ", this->type_, *this);
+        }
+        this->as_array(std::nothrow).push_back(std::move(x));
+        return;
+    }
+
+    template<typename ... Ts>
+    value_type& emplace_back(Ts&& ... args)
+    {
+        if(!this->is_array())
+        {
+            detail::throw_bad_cast<value_t::array>(
+                "toml::value::emplace_back(...): ", this->type_, *this);
+        }
+        this->as_array(std::nothrow).emplace_back(std::forward<Ts>(args) ...);
+        return this->as_array(std::nothrow).back();
+    }
+
+    std::size_t size() const
+    {
+        switch(this->type_)
+        {
+            case value_t::array:
+            {
+                return this->as_array(std::nothrow).size();
+            }
+            case value_t::table:
+            {
+                return this->as_table(std::nothrow).size();
+            }
+            case value_t::string:
+            {
+                return this->as_string(std::nothrow).str.size();
+            }
+            default:
+            {
+                throw type_error(detail::format_underline(
+                    "toml::value::size(): bad_cast to container types", {
+                        {this->location(),
+                         concat_to_string("the actual type is ", this->type_)}
+                    }), this->location());
+            }
+        }
+    }
+
+    std::size_t count(const key_type& k) const
+    {
+        if(!this->is_table())
+        {
+            detail::throw_bad_cast<value_t::table>(
+                "toml::value::count(key): ", this->type_, *this);
+        }
+        return this->as_table(std::nothrow).count(k);
+    }
+
+    bool contains(const key_type& k) const
+    {
+        if(!this->is_table())
+        {
+            detail::throw_bad_cast<value_t::table>(
+                "toml::value::contains(key): ", this->type_, *this);
+        }
+        return (this->as_table(std::nothrow).count(k) != 0);
+    }
+
+    source_location location() const
+    {
+        return source_location(this->region_info_.get());
+    }
+
+    comment_type const& comments() const noexcept {return this->comments_;}
+    comment_type&       comments()       noexcept {return this->comments_;}
+
+  private:
+
+    void cleanup() noexcept
+    {
+        switch(this->type_)
+        {
+            case value_t::string  : {string_.~string();       return;}
+            case value_t::array   : {array_.~array_storage(); return;}
+            case value_t::table   : {table_.~table_storage(); return;}
+            default              : return;
+        }
+    }
+
+    // for error messages
+    template<typename Value>
+    friend region_base const* detail::get_region(const Value& v);
+
+    template<typename Value>
+    friend void detail::change_region(Value& v, detail::region reg);
+
+  private:
+
+    using array_storage = detail::storage<array_type>;
+    using table_storage = detail::storage<table_type>;
+
+    value_t type_;
+    union
+    {
+        boolean         boolean_;
+        integer         integer_;
+        floating        floating_;
+        string          string_;
+        offset_datetime offset_datetime_;
+        local_datetime  local_datetime_;
+        local_date      local_date_;
+        local_time      local_time_;
+        array_storage   array_;
+        table_storage   table_;
+    };
+    std::shared_ptr<region_base> region_info_;
+    comment_type                 comments_;
+};
+
+// default toml::value and default array/table.
+// TOML11_DEFAULT_COMMENT_STRATEGY is defined in comments.hpp
+using value = basic_value<TOML11_DEFAULT_COMMENT_STRATEGY, std::unordered_map, std::vector>;
+using array = typename value::array_type;
+using table = typename value::table_type;
+
+template<typename C, template<typename ...> class T, template<typename ...> class A>
+inline bool
+operator==(const basic_value<C, T, A>& lhs, const basic_value<C, T, A>& rhs)
+{
+    if(lhs.type()     != rhs.type())     {return false;}
+    if(lhs.comments() != rhs.comments()) {return false;}
+
+    switch(lhs.type())
+    {
+        case value_t::boolean  :
+        {
+            return lhs.as_boolean() == rhs.as_boolean();
+        }
+        case value_t::integer  :
+        {
+            return lhs.as_integer() == rhs.as_integer();
+        }
+        case value_t::floating :
+        {
+            return lhs.as_floating() == rhs.as_floating();
+        }
+        case value_t::string   :
+        {
+            return lhs.as_string() == rhs.as_string();
+        }
+        case value_t::offset_datetime:
+        {
+            return lhs.as_offset_datetime() == rhs.as_offset_datetime();
+        }
+        case value_t::local_datetime:
+        {
+            return lhs.as_local_datetime() == rhs.as_local_datetime();
+        }
+        case value_t::local_date:
+        {
+            return lhs.as_local_date() == rhs.as_local_date();
+        }
+        case value_t::local_time:
+        {
+            return lhs.as_local_time() == rhs.as_local_time();
+        }
+        case value_t::array    :
+        {
+            return lhs.as_array() == rhs.as_array();
+        }
+        case value_t::table    :
+        {
+            return lhs.as_table() == rhs.as_table();
+        }
+        case value_t::empty    : {return true; }
+        default:                 {return false;}
+    }
+}
+
+template<typename C, template<typename ...> class T, template<typename ...> class A>
+inline bool operator!=(const basic_value<C, T, A>& lhs, const basic_value<C, T, A>& rhs)
+{
+    return !(lhs == rhs);
+}
+
+template<typename C, template<typename ...> class T, template<typename ...> class A>
+typename std::enable_if<detail::conjunction<
+    detail::is_comparable<typename basic_value<C, T, A>::array_type>,
+    detail::is_comparable<typename basic_value<C, T, A>::table_type>
+    >::value, bool>::type
+operator<(const basic_value<C, T, A>& lhs, const basic_value<C, T, A>& rhs)
+{
+    if(lhs.type() != rhs.type()){return (lhs.type() < rhs.type());}
+    switch(lhs.type())
+    {
+        case value_t::boolean  :
+        {
+            return lhs.as_boolean() <  rhs.as_boolean() ||
+                  (lhs.as_boolean() == rhs.as_boolean() &&
+                   lhs.comments() < rhs.comments());
+        }
+        case value_t::integer  :
+        {
+            return lhs.as_integer() <  rhs.as_integer() ||
+                  (lhs.as_integer() == rhs.as_integer() &&
+                   lhs.comments() < rhs.comments());
+        }
+        case value_t::floating :
+        {
+            return lhs.as_floating() <  rhs.as_floating() ||
+                  (lhs.as_floating() == rhs.as_floating() &&
+                   lhs.comments() < rhs.comments());
+        }
+        case value_t::string   :
+        {
+            return lhs.as_string() <  rhs.as_string() ||
+                  (lhs.as_string() == rhs.as_string() &&
+                   lhs.comments() < rhs.comments());
+        }
+        case value_t::offset_datetime:
+        {
+            return lhs.as_offset_datetime() <  rhs.as_offset_datetime() ||
+                  (lhs.as_offset_datetime() == rhs.as_offset_datetime() &&
+                   lhs.comments() < rhs.comments());
+        }
+        case value_t::local_datetime:
+        {
+            return lhs.as_local_datetime() <  rhs.as_local_datetime() ||
+                  (lhs.as_local_datetime() == rhs.as_local_datetime() &&
+                   lhs.comments() < rhs.comments());
+        }
+        case value_t::local_date:
+        {
+            return lhs.as_local_date() <  rhs.as_local_date() ||
+                  (lhs.as_local_date() == rhs.as_local_date() &&
+                   lhs.comments() < rhs.comments());
+        }
+        case value_t::local_time:
+        {
+            return lhs.as_local_time() <  rhs.as_local_time() ||
+                  (lhs.as_local_time() == rhs.as_local_time() &&
+                   lhs.comments() < rhs.comments());
+        }
+        case value_t::array    :
+        {
+            return lhs.as_array() <  rhs.as_array() ||
+                  (lhs.as_array() == rhs.as_array() &&
+                   lhs.comments() < rhs.comments());
+        }
+        case value_t::table    :
+        {
+            return lhs.as_table() <  rhs.as_table() ||
+                  (lhs.as_table() == rhs.as_table() &&
+                   lhs.comments() < rhs.comments());
+        }
+        case value_t::empty    :
+        {
+            return lhs.comments() < rhs.comments();
+        }
+        default:
+        {
+            return lhs.comments() < rhs.comments();
+        }
+    }
+}
+
+template<typename C, template<typename ...> class T, template<typename ...> class A>
+typename std::enable_if<detail::conjunction<
+    detail::is_comparable<typename basic_value<C, T, A>::array_type>,
+    detail::is_comparable<typename basic_value<C, T, A>::table_type>
+    >::value, bool>::type
+operator<=(const basic_value<C, T, A>& lhs, const basic_value<C, T, A>& rhs)
+{
+    return (lhs < rhs) || (lhs == rhs);
+}
+template<typename C, template<typename ...> class T, template<typename ...> class A>
+typename std::enable_if<detail::conjunction<
+    detail::is_comparable<typename basic_value<C, T, A>::array_type>,
+    detail::is_comparable<typename basic_value<C, T, A>::table_type>
+    >::value, bool>::type
+operator>(const basic_value<C, T, A>& lhs, const basic_value<C, T, A>& rhs)
+{
+    return !(lhs <= rhs);
+}
+template<typename C, template<typename ...> class T, template<typename ...> class A>
+typename std::enable_if<detail::conjunction<
+    detail::is_comparable<typename basic_value<C, T, A>::array_type>,
+    detail::is_comparable<typename basic_value<C, T, A>::table_type>
+    >::value, bool>::type
+operator>=(const basic_value<C, T, A>& lhs, const basic_value<C, T, A>& rhs)
+{
+    return !(lhs < rhs);
+}
+
+template<typename C, template<typename ...> class T, template<typename ...> class A>
+inline std::string format_error(const std::string& err_msg,
+        const basic_value<C, T, A>& v, const std::string& comment,
+        std::vector<std::string> hints = {},
+        const bool colorize = TOML11_ERROR_MESSAGE_COLORIZED)
+{
+    return detail::format_underline(err_msg, {{v.location(), comment}},
+                                    std::move(hints), colorize);
+}
+
+template<typename C, template<typename ...> class T, template<typename ...> class A>
+inline std::string format_error(const std::string& err_msg,
+        const toml::basic_value<C, T, A>& v1, const std::string& comment1,
+        const toml::basic_value<C, T, A>& v2, const std::string& comment2,
+        std::vector<std::string> hints = {},
+        const bool colorize = TOML11_ERROR_MESSAGE_COLORIZED)
+{
+    return detail::format_underline(err_msg, {
+            {v1.location(), comment1}, {v2.location(), comment2}
+        }, std::move(hints), colorize);
+}
+
+template<typename C, template<typename ...> class T, template<typename ...> class A>
+inline std::string format_error(const std::string& err_msg,
+        const toml::basic_value<C, T, A>& v1, const std::string& comment1,
+        const toml::basic_value<C, T, A>& v2, const std::string& comment2,
+        const toml::basic_value<C, T, A>& v3, const std::string& comment3,
+        std::vector<std::string> hints = {},
+        const bool colorize = TOML11_ERROR_MESSAGE_COLORIZED)
+{
+    return detail::format_underline(err_msg, {{v1.location(), comment1},
+            {v2.location(), comment2}, {v3.location(), comment3}
+        }, std::move(hints), colorize);
+}
+
+template<typename Visitor, typename C,
+         template<typename ...> class T, template<typename ...> class A>
+detail::return_type_of_t<Visitor, const toml::boolean&>
+visit(Visitor&& visitor, const toml::basic_value<C, T, A>& v)
+{
+    switch(v.type())
+    {
+        case value_t::boolean        : {return visitor(v.as_boolean        ());}
+        case value_t::integer        : {return visitor(v.as_integer        ());}
+        case value_t::floating       : {return visitor(v.as_floating       ());}
+        case value_t::string         : {return visitor(v.as_string         ());}
+        case value_t::offset_datetime: {return visitor(v.as_offset_datetime());}
+        case value_t::local_datetime : {return visitor(v.as_local_datetime ());}
+        case value_t::local_date     : {return visitor(v.as_local_date     ());}
+        case value_t::local_time     : {return visitor(v.as_local_time     ());}
+        case value_t::array          : {return visitor(v.as_array          ());}
+        case value_t::table          : {return visitor(v.as_table          ());}
+        case value_t::empty          : break;
+        default: break;
+    }
+    throw std::runtime_error(format_error("[error] toml::visit: toml::basic_value "
+            "does not have any valid basic_value.", v, "here"));
+}
+
+template<typename Visitor, typename C,
+         template<typename ...> class T, template<typename ...> class A>
+detail::return_type_of_t<Visitor, toml::boolean&>
+visit(Visitor&& visitor, toml::basic_value<C, T, A>& v)
+{
+    switch(v.type())
+    {
+        case value_t::boolean        : {return visitor(v.as_boolean        ());}
+        case value_t::integer        : {return visitor(v.as_integer        ());}
+        case value_t::floating       : {return visitor(v.as_floating       ());}
+        case value_t::string         : {return visitor(v.as_string         ());}
+        case value_t::offset_datetime: {return visitor(v.as_offset_datetime());}
+        case value_t::local_datetime : {return visitor(v.as_local_datetime ());}
+        case value_t::local_date     : {return visitor(v.as_local_date     ());}
+        case value_t::local_time     : {return visitor(v.as_local_time     ());}
+        case value_t::array          : {return visitor(v.as_array          ());}
+        case value_t::table          : {return visitor(v.as_table          ());}
+        case value_t::empty          : break;
+        default: break;
+    }
+    throw std::runtime_error(format_error("[error] toml::visit: toml::basic_value "
+            "does not have any valid basic_value.", v, "here"));
+}
+
+template<typename Visitor, typename C,
+         template<typename ...> class T, template<typename ...> class A>
+detail::return_type_of_t<Visitor, toml::boolean&&>
+visit(Visitor&& visitor, toml::basic_value<C, T, A>&& v)
+{
+    switch(v.type())
+    {
+        case value_t::boolean        : {return visitor(std::move(v.as_boolean        ()));}
+        case value_t::integer        : {return visitor(std::move(v.as_integer        ()));}
+        case value_t::floating       : {return visitor(std::move(v.as_floating       ()));}
+        case value_t::string         : {return visitor(std::move(v.as_string         ()));}
+        case value_t::offset_datetime: {return visitor(std::move(v.as_offset_datetime()));}
+        case value_t::local_datetime : {return visitor(std::move(v.as_local_datetime ()));}
+        case value_t::local_date     : {return visitor(std::move(v.as_local_date     ()));}
+        case value_t::local_time     : {return visitor(std::move(v.as_local_time     ()));}
+        case value_t::array          : {return visitor(std::move(v.as_array          ()));}
+        case value_t::table          : {return visitor(std::move(v.as_table          ()));}
+        case value_t::empty          : break;
+        default: break;
+    }
+    throw std::runtime_error(format_error("[error] toml::visit: toml::basic_value "
+            "does not have any valid basic_value.", v, "here"));
+}
+
+}// toml
+#endif// TOML11_VALUE

From 10a8b5d3ae65cbf842faa83a91e7805276cb799e Mon Sep 17 00:00:00 2001
From: Nicolas Mattia <nicolas@nmattia.com>
Date: Fri, 17 Dec 2021 22:03:48 +0100
Subject: [PATCH 342/567] Update primops/fromTOML.cc to use toml11

---
 src/libexpr/primops/fromTOML.cc | 113 +++++++++++++++-----------------
 1 file changed, 53 insertions(+), 60 deletions(-)

diff --git a/src/libexpr/primops/fromTOML.cc b/src/libexpr/primops/fromTOML.cc
index 4c6682dfd..8fba0bf04 100644
--- a/src/libexpr/primops/fromTOML.cc
+++ b/src/libexpr/primops/fromTOML.cc
@@ -1,86 +1,79 @@
 #include "primops.hh"
 #include "eval-inline.hh"
 
-#include "../../cpptoml/cpptoml.h"
+#include "../../toml11/toml.hpp"
 
 namespace nix {
 
-static void prim_fromTOML(EvalState & state, const Pos & pos, Value * * args, Value & v)
+static void prim_fromTOML(EvalState & state, const Pos & pos, Value * * args, Value & val)
 {
-    using namespace cpptoml;
-
     auto toml = state.forceStringNoCtx(*args[0], pos);
 
     std::istringstream tomlStream(toml);
 
-    std::function<void(Value &, std::shared_ptr<base>)> visit;
+    std::function<void(Value &, toml::value)> visit;
 
-    visit = [&](Value & v, std::shared_ptr<base> t) {
+    visit = [&](Value & v, toml::value t) {
 
-        if (auto t2 = t->as_table()) {
+        switch(t.type())
+        {
+            case toml::value_t::table:
+                {
+                    auto table = toml::get<toml::table>(t);
 
-            size_t size = 0;
-            for (auto & i : *t2) { (void) i; size++; }
+                    size_t size = 0;
+                    for (auto & i : table) { (void) i; size++; }
 
-            state.mkAttrs(v, size);
+                    state.mkAttrs(v, size);
 
-            for (auto & i : *t2) {
-                auto & v2 = *state.allocAttr(v, state.symbols.create(i.first));
+                    for(auto & elem: table) {
 
-                if (auto i2 = i.second->as_table_array()) {
-                    size_t size2 = i2->get().size();
-                    state.mkList(v2, size2);
-                    for (size_t j = 0; j < size2; ++j)
-                        visit(*(v2.listElems()[j] = state.allocValue()), i2->get()[j]);
+                        auto & v2 = *state.allocAttr(v, state.symbols.create(elem.first));
+
+                        // TODO: note about creating children here in old code
+                        visit(v2, elem.second);
+                    }
                 }
-                else
-                    visit(v2, i.second);
-            }
+                break;;
+            case toml::value_t::array:
+                {
+                    auto array = toml::get<std::vector<toml::value>>(t);
+
+                    size_t size = array.size();
+                    state.mkList(v, size);
+                    for (size_t i = 0; i < size; ++i)
+                        visit(*(v.listElems()[i] = state.allocValue()), array[i]);
+                }
+                break;;
+            case toml::value_t::boolean:
+                mkBool(v, toml::get<bool>(t));
+                break;;
+            case toml::value_t::integer:
+                mkInt(v, toml::get<int>(t));
+                break;;
+            case toml::value_t::floating:
+                mkFloat(v, toml::get<double>(t));
+                break;;
+            case toml::value_t::string:
+                mkString(v, toml::get<std::string>(t));
+                break;;
+            case toml::value_t::local_datetime:
+            case toml::value_t::offset_datetime:
+            case toml::value_t::local_date:
+            case toml::value_t::local_time:
+                // TODO: convert to string?
+                throw std::runtime_error("Dates and times are not supported");
+                break;;
+            case toml::value_t::empty:
+                mkNull(v);
+                break;;
 
-            v.attrs->sort();
         }
-
-        else if (auto t2 = t->as_array()) {
-            size_t size = t2->get().size();
-
-            state.mkList(v, size);
-
-            for (size_t i = 0; i < size; ++i)
-                visit(*(v.listElems()[i] = state.allocValue()), t2->get()[i]);
-        }
-
-        // Handle cases like 'a = [[{ a = true }]]', which IMHO should be
-        // parsed as a array containing an array containing a table,
-        // but instead are parsed as an array containing a table array
-        // containing a table.
-        else if (auto t2 = t->as_table_array()) {
-            size_t size = t2->get().size();
-
-            state.mkList(v, size);
-
-            for (size_t j = 0; j < size; ++j)
-                visit(*(v.listElems()[j] = state.allocValue()), t2->get()[j]);
-        }
-
-        else if (t->is_value()) {
-            if (auto val = t->as<int64_t>())
-                mkInt(v, val->get());
-            else if (auto val = t->as<NixFloat>())
-                mkFloat(v, val->get());
-            else if (auto val = t->as<bool>())
-                mkBool(v, val->get());
-            else if (auto val = t->as<std::string>())
-                mkString(v, val->get());
-            else
-                throw EvalError("unsupported value type in TOML");
-        }
-
-        else abort();
     };
 
     try {
-        visit(v, parser(tomlStream).parse());
-    } catch (std::runtime_error & e) {
+        visit(val, toml::parse(tomlStream)); // TODO give filename
+    } catch (std::exception & e) { // TODO: toml::syntax_error
         throw EvalError({
             .msg = hintfmt("while parsing a TOML string: %s", e.what()),
             .errPos = pos

From 5d06836b9f8b675bdbaa1ce2497d704cfe5e2456 Mon Sep 17 00:00:00 2001
From: Nicolas Mattia <nicolas@nmattia.com>
Date: Fri, 17 Dec 2021 23:15:26 +0100
Subject: [PATCH 343/567] Use long in fromTOML

---
 src/libexpr/primops/fromTOML.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libexpr/primops/fromTOML.cc b/src/libexpr/primops/fromTOML.cc
index 8fba0bf04..4ec64daf2 100644
--- a/src/libexpr/primops/fromTOML.cc
+++ b/src/libexpr/primops/fromTOML.cc
@@ -49,7 +49,7 @@ static void prim_fromTOML(EvalState & state, const Pos & pos, Value * * args, Va
                 mkBool(v, toml::get<bool>(t));
                 break;;
             case toml::value_t::integer:
-                mkInt(v, toml::get<int>(t));
+                mkInt(v, toml::get<long>(t));
                 break;;
             case toml::value_t::floating:
                 mkFloat(v, toml::get<double>(t));

From 1827cf5a9b8fa0f8f1dff1ee775f67f7f326606c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Na=C3=AFm=20Favier?= <n@monade.li>
Date: Mon, 20 Dec 2021 19:57:48 +0100
Subject: [PATCH 344/567] Add shell completion for why-depends

Fixes #5806
---
 src/nix/why-depends.cc | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/nix/why-depends.cc b/src/nix/why-depends.cc
index 2f6b361bb..e27f56ef5 100644
--- a/src/nix/why-depends.cc
+++ b/src/nix/why-depends.cc
@@ -34,8 +34,21 @@ struct CmdWhyDepends : SourceExprCommand
 
     CmdWhyDepends()
     {
-        expectArg("package", &_package);
-        expectArg("dependency", &_dependency);
+        expectArgs({
+            .label = "package",
+            .handler = {&_package},
+            .completer = {[&](size_t, std::string_view prefix) {
+                completeInstallable(prefix);
+            }}
+        });
+
+        expectArgs({
+            .label = "dependency",
+            .handler = {&_dependency},
+            .completer = {[&](size_t, std::string_view prefix) {
+                completeInstallable(prefix);
+            }}
+        });
 
         addFlag({
             .longName = "all",

From 9dea5768ef0e3d11725926a96eeadac81c0e2543 Mon Sep 17 00:00:00 2001
From: Nicolas Mattia <nicolas@nmattia.com>
Date: Mon, 20 Dec 2021 21:39:37 +0100
Subject: [PATCH 345/567] Clean up toml parsing code

---
 src/libexpr/primops/fromTOML.cc | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/src/libexpr/primops/fromTOML.cc b/src/libexpr/primops/fromTOML.cc
index 4ec64daf2..bfea1ce34 100644
--- a/src/libexpr/primops/fromTOML.cc
+++ b/src/libexpr/primops/fromTOML.cc
@@ -29,8 +29,6 @@ static void prim_fromTOML(EvalState & state, const Pos & pos, Value * * args, Va
                     for(auto & elem: table) {
 
                         auto & v2 = *state.allocAttr(v, state.symbols.create(elem.first));
-
-                        // TODO: note about creating children here in old code
                         visit(v2, elem.second);
                     }
                 }
@@ -61,7 +59,7 @@ static void prim_fromTOML(EvalState & state, const Pos & pos, Value * * args, Va
             case toml::value_t::offset_datetime:
             case toml::value_t::local_date:
             case toml::value_t::local_time:
-                // TODO: convert to string?
+                // We fail since Nix doesn't have date and time types
                 throw std::runtime_error("Dates and times are not supported");
                 break;;
             case toml::value_t::empty:
@@ -72,7 +70,7 @@ static void prim_fromTOML(EvalState & state, const Pos & pos, Value * * args, Va
     };
 
     try {
-        visit(val, toml::parse(tomlStream)); // TODO give filename
+        visit(val, toml::parse(tomlStream, "fromTOML" /* the "filename" */));
     } catch (std::exception & e) { // TODO: toml::syntax_error
         throw EvalError({
             .msg = hintfmt("while parsing a TOML string: %s", e.what()),

From 09b245690a9ab40847e3faa96646e4bd6ce033e0 Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Mon, 20 Dec 2021 13:28:54 +0100
Subject: [PATCH 346/567] bulk-allocate Value instances in the evaluator
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

calling GC_malloc for each value is significantly more expensive than
allocating a bunch of values at once with GC_malloc_many. "a bunch" here
is a GC block size, ie 16KiB or less.

this gives a 1.5% performance boost when evaluating our nixos system.

tested with

nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'

 # on master

  Time (mean ± σ):      3.335 s ±  0.007 s    [User: 2.774 s, System: 0.293 s]
  Range (min … max):    3.315 s …  3.347 s    50 runs

 # with this change

  Time (mean ± σ):      3.288 s ±  0.006 s    [User: 2.728 s, System: 0.292 s]
  Range (min … max):    3.274 s …  3.307 s    50 runs
---
 src/libexpr/eval.cc | 17 ++++++++++++++++-
 src/libexpr/eval.hh |  3 +++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 8cf4d9549..a95726f5f 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -821,8 +821,23 @@ inline Value * EvalState::lookupVar(Env * env, const ExprVar & var, bool noEval)
 
 Value * EvalState::allocValue()
 {
+    /* We use the boehm batch allocator to speed up allocations of Values (of which there are many).
+       GC_malloc_many returns a linked list of objects of the given size, where the first word
+       of each object is also the pointer to the next object in the list. This also means that we
+       have to explicitly clear the first word of every object we take. */
+    if (!valueAllocCache) {
+        valueAllocCache = GC_malloc_many(sizeof(Value));
+        if (!valueAllocCache) throw std::bad_alloc();
+    }
+
+    /* GC_NEXT is a convenience macro for accessing the first word of an object.
+       Take the first list item, advance the list to the next item, and clear the next pointer. */
+    void * p = valueAllocCache;
+    GC_PTR_STORE_AND_DIRTY(&valueAllocCache, GC_NEXT(p));
+    GC_NEXT(p) = nullptr;
+
     nrValues++;
-    auto v = (Value *) allocBytes(sizeof(Value));
+    auto v = (Value *) p;
     return v;
 }
 
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 1aab8e166..cc63294c6 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -133,6 +133,9 @@ private:
     /* Cache used by prim_match(). */
     std::shared_ptr<RegexCache> regexCache;
 
+    /* Allocation cache for GC'd Value objects. */
+    void * valueAllocCache = nullptr;
+
 public:
 
     EvalState(

From cbbd21ec073781f68029daff153dac2516dafc23 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Tue, 21 Dec 2021 08:42:19 +0100
Subject: [PATCH 347/567] Factor out the path realisation bit of IFD

---
 src/libexpr/primops.cc | 75 +++++++++++++++++++++---------------------
 1 file changed, 38 insertions(+), 37 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 66af373d7..5f00fad1c 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -76,6 +76,19 @@ void EvalState::realiseContext(const PathSet & context)
     }
 }
 
+static Path realisePath(EvalState & state, const Pos & pos, Value & v, bool requireAbsolutePath = true)
+{
+    PathSet context;
+
+    Path path = requireAbsolutePath
+        ? state.coerceToPath(pos, v, context)
+        : state.coerceToString(pos, v, context, false, false);
+
+    state.realiseContext(context);
+
+    return state.checkSourcePath(state.toRealPath(path, context));
+}
+
 /* Add and attribute to the given attribute map from the output name to
    the output path, or a placeholder.
 
@@ -109,11 +122,9 @@ static void mkOutputString(EvalState & state, Value & v,
    argument. */
 static void import(EvalState & state, const Pos & pos, Value & vPath, Value * vScope, Value & v)
 {
-    PathSet context;
-    Path path = state.coerceToPath(pos, vPath, context);
-
+    Path path;
     try {
-        state.realiseContext(context);
+        path = realisePath(state, pos, vPath);
     } catch (InvalidPathError & e) {
         throw EvalError({
             .msg = hintfmt("cannot import '%1%', since path '%2%' is not valid", path, e.path),
@@ -124,8 +135,6 @@ static void import(EvalState & state, const Pos & pos, Value & vPath, Value * vS
         throw;
     }
 
-    Path realPath = state.checkSourcePath(state.toRealPath(path, context));
-
     // FIXME
     auto isValidDerivationInStore = [&]() -> std::optional<StorePath> {
         if (!state.store->isStorePath(path))
@@ -177,7 +186,7 @@ static void import(EvalState & state, const Pos & pos, Value & vPath, Value * vS
 
     else {
         if (!vScope)
-            state.evalFile(realPath, v);
+            state.evalFile(path, v);
         else {
             state.forceAttrs(*vScope);
 
@@ -195,8 +204,8 @@ static void import(EvalState & state, const Pos & pos, Value & vPath, Value * vS
             // No need to call staticEnv.sort(), because
             // args[0]->attrs is already sorted.
 
-            printTalkative("evaluating file '%1%'", realPath);
-            Expr * e = state.parseExprFromFile(resolveExprPath(realPath), staticEnv);
+            printTalkative("evaluating file '%1%'", path);
+            Expr * e = state.parseExprFromFile(resolveExprPath(path), staticEnv);
 
             e->eval(state, *env, v);
         }
@@ -281,22 +290,19 @@ extern "C" typedef void (*ValueInitializer)(EvalState & state, Value & v);
 /* Load a ValueInitializer from a DSO and return whatever it initializes */
 void prim_importNative(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    PathSet context;
-    Path path = state.coerceToPath(pos, *args[0], context);
-
+    Path path;
     try {
-        state.realiseContext(context);
+        path = realisePath(state, pos, *args[0]);
     } catch (InvalidPathError & e) {
         throw EvalError({
-            .msg = hintfmt(
-                "cannot import '%1%', since path '%2%' is not valid",
-                path, e.path),
+            .msg = hintfmt("cannot import '%1%', since path '%2%' is not valid", path, e.path),
             .errPos = pos
         });
+    } catch (Error & e) {
+        e.addTrace(pos, "while importing '%s'", path);
+        throw;
     }
 
-    path = state.checkSourcePath(path);
-
     string sym = state.forceStringNoCtx(*args[1], pos);
 
     void *handle = dlopen(path.c_str(), RTLD_LAZY | RTLD_LOCAL);
@@ -1349,10 +1355,9 @@ static RegisterPrimOp primop_storePath({
 
 static void prim_pathExists(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    PathSet context;
-    Path path = state.coerceToPath(pos, *args[0], context);
+    Path path;
     try {
-        state.realiseContext(context);
+        path = realisePath(state, pos, *args[0]);
     } catch (InvalidPathError & e) {
         throw EvalError({
             .msg = hintfmt(
@@ -1363,7 +1368,7 @@ static void prim_pathExists(EvalState & state, const Pos & pos, Value * * args,
     }
 
     try {
-        mkBool(v, pathExists(state.checkSourcePath(path)));
+        mkBool(v, pathExists(path));
     } catch (SysError & e) {
         /* Don't give away info from errors while canonicalising
            ‘path’ in restricted mode. */
@@ -1426,17 +1431,16 @@ static RegisterPrimOp primop_dirOf({
 /* Return the contents of a file as a string. */
 static void prim_readFile(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    PathSet context;
-    Path path = state.coerceToPath(pos, *args[0], context);
+    Path path;
     try {
-        state.realiseContext(context);
+        path = realisePath(state, pos, *args[0]);
     } catch (InvalidPathError & e) {
         throw EvalError({
             .msg = hintfmt("cannot read '%1%', since path '%2%' is not valid", path, e.path),
             .errPos = pos
         });
     }
-    string s = readFile(state.checkSourcePath(state.toRealPath(path, context)));
+    string s = readFile(path);
     if (s.find((char) 0) != string::npos)
         throw Error("the contents of the file '%1%' cannot be represented as a Nix string", path);
     mkString(v, s.c_str());
@@ -1475,11 +1479,10 @@ static void prim_findFile(EvalState & state, const Pos & pos, Value * * args, Va
             pos
         );
 
-        PathSet context;
-        string path = state.coerceToString(pos, *i->value, context, false, false);
+        Path path;
 
         try {
-            state.realiseContext(context);
+            path = realisePath(state, pos, *i->value, false);
         } catch (InvalidPathError & e) {
             throw EvalError({
                 .msg = hintfmt("cannot find '%1%', since path '%2%' is not valid", path, e.path),
@@ -1512,15 +1515,14 @@ static void prim_hashFile(EvalState & state, const Pos & pos, Value * * args, Va
             .errPos = pos
         });
 
-    PathSet context;
-    Path path = state.coerceToPath(pos, *args[1], context);
+    Path path;
     try {
-        state.realiseContext(context);
+        path = realisePath(state, pos, *args[1]);
     } catch (InvalidPathError & e) {
         throw EvalError("cannot read '%s' since path '%s' is not valid, at %s", path, e.path, pos);
     }
 
-    mkString(v, hashFile(*ht, state.checkSourcePath(state.toRealPath(path, context))).to_string(Base16, false));
+    mkString(v, hashFile(*ht, path).to_string(Base16, false));
 }
 
 static RegisterPrimOp primop_hashFile({
@@ -1537,10 +1539,9 @@ static RegisterPrimOp primop_hashFile({
 /* Read a directory (without . or ..) */
 static void prim_readDir(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    PathSet ctx;
-    Path path = state.coerceToPath(pos, *args[0], ctx);
+    Path path;
     try {
-        state.realiseContext(ctx);
+        path = realisePath(state, pos, *args[0]);
     } catch (InvalidPathError & e) {
         throw EvalError({
             .msg = hintfmt("cannot read '%1%', since path '%2%' is not valid", path, e.path),
@@ -1548,7 +1549,7 @@ static void prim_readDir(EvalState & state, const Pos & pos, Value * * args, Val
         });
     }
 
-    DirEntries entries = readDirectory(state.checkSourcePath(path));
+    DirEntries entries = readDirectory(path);
     state.mkAttrs(v, entries.size());
 
     for (auto & ent : entries) {

From d90f9d4b9994dc1f15b9d664ae313f06261d6058 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Mon, 20 Dec 2021 19:46:55 +0100
Subject: [PATCH 348/567] Fix IFD with CA derivations

Rewrite the string taken by the IFD-like primops to contain the actual
output paths of the derivations rather than the placeholders

Fix #5805
---
 src/libexpr/eval.hh           |  5 +++-
 src/libexpr/primops.cc        | 43 +++++++++++++++++++++++------------
 tests/ca/import-derivation.sh |  6 +++++
 tests/local.mk                |  2 +-
 4 files changed, 40 insertions(+), 16 deletions(-)
 create mode 100644 tests/ca/import-derivation.sh

diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 1aab8e166..0ba570434 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -350,7 +350,10 @@ public:
     /* Print statistics. */
     void printStats();
 
-    void realiseContext(const PathSet & context);
+    /* Realise the given context, and return a mapping from the placeholders
+     * used to construct the associated value to their final store path
+     */
+    [[nodiscard]] StringMap realiseContext(const PathSet & context);
 
 private:
 
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 5f00fad1c..aff8f951e 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -35,9 +35,10 @@ namespace nix {
 InvalidPathError::InvalidPathError(const Path & path) :
     EvalError("path '%s' is not valid", path), path(path) {}
 
-void EvalState::realiseContext(const PathSet & context)
+StringMap EvalState::realiseContext(const PathSet & context)
 {
     std::vector<DerivedPath::Built> drvs;
+    StringMap res;
 
     for (auto & i : context) {
         auto [ctxS, outputName] = decodeContext(i);
@@ -46,10 +47,12 @@ void EvalState::realiseContext(const PathSet & context)
             throw InvalidPathError(store->printStorePath(ctx));
         if (!outputName.empty() && ctx.isDerivation()) {
             drvs.push_back({ctx, {outputName}});
+        } else {
+            res.insert_or_assign(ctxS, ctxS);
         }
     }
 
-    if (drvs.empty()) return;
+    if (drvs.empty()) return {};
 
     if (!evalSettings.enableImportFromDerivation)
         throw Error(
@@ -61,19 +64,29 @@ void EvalState::realiseContext(const PathSet & context)
     for (auto & d : drvs) buildReqs.emplace_back(DerivedPath { d });
     store->buildPaths(buildReqs);
 
+    /* Get all the output paths corresponding to the placeholders we had */
+    for (auto & [drvPath, outputs] : drvs) {
+        auto outputPaths = store->queryDerivationOutputMap(drvPath);
+        for (auto & outputName : outputs) {
+            if (outputPaths.count(outputName) == 0)
+                throw Error("derivation '%s' does not have an output named '%s'",
+                        store->printStorePath(drvPath), outputName);
+            res.insert_or_assign(
+                downstreamPlaceholder(*store, drvPath, outputName),
+                store->printStorePath(outputPaths.at(outputName))
+            );
+        }
+    }
+
     /* Add the output of this derivations to the allowed
        paths. */
     if (allowedPaths) {
-        for (auto & [drvPath, outputs] : drvs) {
-            auto outputPaths = store->queryDerivationOutputMap(drvPath);
-            for (auto & outputName : outputs) {
-                if (outputPaths.count(outputName) == 0)
-                    throw Error("derivation '%s' does not have an output named '%s'",
-                            store->printStorePath(drvPath), outputName);
-                allowPath(outputPaths.at(outputName));
-            }
+        for (auto & [_placeholder, outputPath] : res) {
+            allowPath(outputPath);
         }
     }
+
+    return res;
 }
 
 static Path realisePath(EvalState & state, const Pos & pos, Value & v, bool requireAbsolutePath = true)
@@ -84,9 +97,10 @@ static Path realisePath(EvalState & state, const Pos & pos, Value & v, bool requ
         ? state.coerceToPath(pos, v, context)
         : state.coerceToString(pos, v, context, false, false);
 
-    state.realiseContext(context);
+    StringMap rewrites = state.realiseContext(context);
 
-    return state.checkSourcePath(state.toRealPath(path, context));
+    return state.checkSourcePath(
+            state.toRealPath(rewriteStrings(path, rewrites), context));
 }
 
 /* Add and attribute to the given attribute map from the output name to
@@ -344,7 +358,7 @@ void prim_exec(EvalState & state, const Pos & pos, Value * * args, Value & v)
     for (unsigned int i = 1; i < args[0]->listSize(); ++i)
         commandArgs.emplace_back(state.coerceToString(pos, *elems[i], context, false, false));
     try {
-        state.realiseContext(context);
+        auto _ = state.realiseContext(context); // FIXME: Handle CA derivations
     } catch (InvalidPathError & e) {
         throw EvalError({
             .msg = hintfmt("cannot execute '%1%', since path '%2%' is not valid",
@@ -1876,7 +1890,8 @@ static void addPath(
     try {
         // FIXME: handle CA derivation outputs (where path needs to
         // be rewritten to the actual output).
-        state.realiseContext(context);
+        auto rewrites = state.realiseContext(context);
+        path = state.toRealPath(rewriteStrings(path, rewrites), context);
 
         StorePathSet refs;
 
diff --git a/tests/ca/import-derivation.sh b/tests/ca/import-derivation.sh
new file mode 100644
index 000000000..e98e0fbd0
--- /dev/null
+++ b/tests/ca/import-derivation.sh
@@ -0,0 +1,6 @@
+source common.sh
+
+export NIX_TESTS_CA_BY_DEFAULT=1
+
+cd .. && source import-derivation.sh
+
diff --git a/tests/local.mk b/tests/local.mk
index 936b72c2a..c22e779a6 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -11,7 +11,7 @@ nix_tests = \
   local-store.sh remote-store.sh export.sh export-graph.sh \
   db-migration.sh \
   timeout.sh secure-drv-outputs.sh nix-channel.sh \
-  multiple-outputs.sh import-derivation.sh fetchurl.sh optimise-store.sh \
+  multiple-outputs.sh import-derivation.sh ca/import-derivation.sh fetchurl.sh optimise-store.sh \
   binary-cache.sh \
   substitute-with-invalid-ca.sh \
   binary-cache-build-remote.sh \

From 881b610266f553dd45d398cc7c5cd0d3d1491ee5 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 21 Dec 2021 14:19:21 +0100
Subject: [PATCH 349/567] Update release notes

---
 doc/manual/src/release-notes/rl-next.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index c869b5e2f..ac662c132 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -1 +1,4 @@
 # Release X.Y (202?-??-??)
+
+* The TOML parser used by `builtins.fromTOML` has been replaced by [a
+  more compliant one](https://github.com/ToruNiina/toml11).

From 534bc5a3d1fba33f25f9921e8cea7ac8e98288c5 Mon Sep 17 00:00:00 2001
From: Rok Garbas <rok@garbas.si>
Date: Tue, 21 Dec 2021 21:17:29 +0100
Subject: [PATCH 350/567] Add cacert to /etc/ssl/certs in the docker image

Fixes #5797
---
 docker.nix | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/docker.nix b/docker.nix
index ffb553f78..25930bb87 100644
--- a/docker.nix
+++ b/docker.nix
@@ -180,6 +180,9 @@ let
       set -x
       mkdir -p $out/etc
 
+      mkdir -p $out/etc/ssl/certs
+      ln -s /nix/var/nix/profiles/default/etc/ssl/certs/ca-bundle.crt $out/etc/ssl/certs
+
       cat $passwdContentsPath > $out/etc/passwd
       echo "" >> $out/etc/passwd
 

From 0a7c1da9f3182e685a08eadd6185803a83a16b59 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 22 Dec 2021 13:21:45 +0100
Subject: [PATCH 351/567] Make bash completion for 'nix' work in a devshell

---
 flake.nix | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/flake.nix b/flake.nix
index 806ed45de..f4fae2a00 100644
--- a/flake.nix
+++ b/flake.nix
@@ -667,6 +667,9 @@
               PATH=$prefix/bin:$PATH
               unset PYTHONPATH
               export MANPATH=$out/share/man:$MANPATH
+
+              # Make bash completion work.
+              XDG_DATA_DIRS+=:$out/share
             '';
         });
 

From 5b5f68f1dd4395f0ef7231218295d1c633d4288b Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 22 Dec 2021 13:26:35 +0100
Subject: [PATCH 352/567] Make bash completion work when nix is invoked as
 ~/.../nix

---
 misc/bash/completion.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/misc/bash/completion.sh b/misc/bash/completion.sh
index bea2a40bc..0af90d8c1 100644
--- a/misc/bash/completion.sh
+++ b/misc/bash/completion.sh
@@ -13,7 +13,7 @@ function _complete_nix {
         else
             COMPREPLY+=("$completion")
         fi
-    done < <(NIX_GET_COMPLETIONS=$cword "${words[@]}")
+    done < <(NIX_GET_COMPLETIONS=$cword "${words[@]/#\~/$HOME}")
     __ltrim_colon_completions "$cur"
 }
 

From 9747ea84b43c75f719d719673b9d0a7cb50d34e5 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 22 Dec 2021 15:49:51 +0100
Subject: [PATCH 353/567] Remove CPU locking
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This was already accidentally disabled in ba87b08. It also no longer
appears to be beneficial, and in fact slow things down, e.g. when
evaluating a NixOS system configuration:

  elapsed time:       median =      3.8170  mean =      3.8202  stddev =      0.0195  min =      3.7894  max =      3.8600  [rejected, p=0.00000, Δ=0.36929±0.02513]
---
 src/libstore/daemon.cc       |  5 ++-
 src/libstore/remote-store.cc |  8 ++---
 src/libutil/affinity.cc      | 70 ------------------------------------
 src/libutil/affinity.hh      |  9 -----
 src/libutil/thread-pool.cc   |  3 --
 src/libutil/util.cc          |  4 ---
 src/libutil/util.hh          |  2 +-
 src/nix-build/nix-build.cc   |  1 -
 src/nix/develop.cc           |  1 -
 src/nix/repl.cc              |  1 -
 src/nix/run.cc               |  1 -
 11 files changed, 5 insertions(+), 100 deletions(-)
 delete mode 100644 src/libutil/affinity.cc
 delete mode 100644 src/libutil/affinity.hh

diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index bafab6fd5..59325da79 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -4,7 +4,6 @@
 #include "store-api.hh"
 #include "path-with-outputs.hh"
 #include "finally.hh"
-#include "affinity.hh"
 #include "archive.hh"
 #include "derivations.hh"
 #include "args.hh"
@@ -960,8 +959,8 @@ void processConnection(
     });
 
     if (GET_PROTOCOL_MINOR(clientVersion) >= 14 && readInt(from)) {
-        auto affinity = readInt(from);
-        setAffinityTo(affinity);
+        // Obsolete CPU affinity.
+        readInt(from);
     }
 
     readInt(from); // obsolete reserveSpace
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index 7f7e973e9..57cc260b0 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -5,7 +5,6 @@
 #include "remote-store.hh"
 #include "worker-protocol.hh"
 #include "archive.hh"
-#include "affinity.hh"
 #include "globals.hh"
 #include "derivations.hh"
 #include "pool.hh"
@@ -184,11 +183,8 @@ void RemoteStore::initConnection(Connection & conn)
         conn.to << PROTOCOL_VERSION;
 
         if (GET_PROTOCOL_MINOR(conn.daemonVersion) >= 14) {
-            int cpu = sameMachine() && settings.lockCPU ? lockToCurrentCPU() : -1;
-            if (cpu != -1)
-                conn.to << 1 << cpu;
-            else
-                conn.to << 0;
+            // Obsolete CPU affinity.
+            conn.to << 0;
         }
 
         if (GET_PROTOCOL_MINOR(conn.daemonVersion) >= 11)
diff --git a/src/libutil/affinity.cc b/src/libutil/affinity.cc
deleted file mode 100644
index ac2295e4a..000000000
--- a/src/libutil/affinity.cc
+++ /dev/null
@@ -1,70 +0,0 @@
-#include "types.hh"
-#include "util.hh"
-#include "affinity.hh"
-
-#if __linux__
-#include <sched.h>
-#endif
-
-namespace nix {
-
-
-#if __linux__
-static bool didSaveAffinity = false;
-static cpu_set_t savedAffinity;
-
-std::ostream& operator<<(std::ostream &os, const cpu_set_t &cset)
-{
-    auto count = CPU_COUNT(&cset);
-    for (int i=0; i < count; ++i)
-    {
-        os << (CPU_ISSET(i,&cset) ? "1" : "0");
-    }
-
-    return os;
-}
-#endif
-
-
-void setAffinityTo(int cpu)
-{
-#if __linux__
-    if (sched_getaffinity(0, sizeof(cpu_set_t), &savedAffinity) == -1) return;
-    didSaveAffinity = true;
-    debug(format("locking this thread to CPU %1%") % cpu);
-    cpu_set_t newAffinity;
-    CPU_ZERO(&newAffinity);
-    CPU_SET(cpu, &newAffinity);
-    if (sched_setaffinity(0, sizeof(cpu_set_t), &newAffinity) == -1)
-        printError("failed to lock thread to CPU %1%", cpu);
-#endif
-}
-
-
-int lockToCurrentCPU()
-{
-#if __linux__
-    int cpu = sched_getcpu();
-    if (cpu != -1) setAffinityTo(cpu);
-    return cpu;
-#else
-    return -1;
-#endif
-}
-
-
-void restoreAffinity()
-{
-#if __linux__
-    if (!didSaveAffinity) return;
-    if (sched_setaffinity(0, sizeof(cpu_set_t), &savedAffinity) == -1)
-    {
-        std::ostringstream oss;
-        oss << savedAffinity;
-        printError("failed to restore CPU affinity %1%", oss.str());
-    }
-#endif
-}
-
-
-}
diff --git a/src/libutil/affinity.hh b/src/libutil/affinity.hh
deleted file mode 100644
index c1bd28e13..000000000
--- a/src/libutil/affinity.hh
+++ /dev/null
@@ -1,9 +0,0 @@
-#pragma once
-
-namespace nix {
-
-void setAffinityTo(int cpu);
-int lockToCurrentCPU();
-void restoreAffinity();
-
-}
diff --git a/src/libutil/thread-pool.cc b/src/libutil/thread-pool.cc
index 857ee91f8..dc4067f1b 100644
--- a/src/libutil/thread-pool.cc
+++ b/src/libutil/thread-pool.cc
@@ -1,13 +1,10 @@
 #include "thread-pool.hh"
-#include "affinity.hh"
 
 namespace nix {
 
 ThreadPool::ThreadPool(size_t _maxThreads)
     : maxThreads(_maxThreads)
 {
-    restoreAffinity(); // FIXME
-
     if (!maxThreads) {
         maxThreads = std::thread::hardware_concurrency();
         if (!maxThreads) maxThreads = 1;
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 43fea1b1e..e18648557 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1,5 +1,4 @@
 #include "util.hh"
-#include "affinity.hh"
 #include "sync.hh"
 #include "finally.hh"
 #include "serialise.hh"
@@ -1004,7 +1003,6 @@ pid_t startProcess(std::function<void()> fun, const ProcessOptions & options)
             if (options.dieWithParent && prctl(PR_SET_PDEATHSIG, SIGKILL) == -1)
                 throw SysError("setting death signal");
 #endif
-            restoreAffinity();
             fun();
         } catch (std::exception & e) {
             try {
@@ -1675,8 +1673,6 @@ void restoreProcessContext(bool restoreMounts)
         restoreMountNamespace();
     }
 
-    restoreAffinity();
-
     #if __linux__
     if (savedStackSize) {
         struct rlimit limit;
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 4cc043a84..d08f42826 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -300,7 +300,7 @@ void setStackSize(size_t stackSize);
 
 
 /* Restore the original inherited Unix process context (such as signal
-   masks, stack size, CPU affinity). */
+   masks, stack size). */
 void restoreProcessContext(bool restoreMounts = true);
 
 /* Save the current mount namespace. Ignored if called more than
diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index e2325c91f..d3d6ce1ce 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -14,7 +14,6 @@
 #include "local-fs-store.hh"
 #include "globals.hh"
 #include "derivations.hh"
-#include "affinity.hh"
 #include "util.hh"
 #include "shared.hh"
 #include "path-with-outputs.hh"
diff --git a/src/nix/develop.cc b/src/nix/develop.cc
index 5aad53919..a8ca1cac2 100644
--- a/src/nix/develop.cc
+++ b/src/nix/develop.cc
@@ -5,7 +5,6 @@
 #include "store-api.hh"
 #include "path-with-outputs.hh"
 #include "derivations.hh"
-#include "affinity.hh"
 #include "progress-bar.hh"
 #include "run.hh"
 
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index f453343f3..63ccbfda3 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -28,7 +28,6 @@ extern "C" {
 #include "common-eval-args.hh"
 #include "get-drvs.hh"
 #include "derivations.hh"
-#include "affinity.hh"
 #include "globals.hh"
 #include "command.hh"
 #include "finally.hh"
diff --git a/src/nix/run.cc b/src/nix/run.cc
index b01fdebaa..bae64ed39 100644
--- a/src/nix/run.cc
+++ b/src/nix/run.cc
@@ -8,7 +8,6 @@
 #include "finally.hh"
 #include "fs-accessor.hh"
 #include "progress-bar.hh"
-#include "affinity.hh"
 #include "eval.hh"
 
 #if __linux__

From 1da1b2b345ccf32220a2628622ee8b170d9d521a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Na=C3=AFm=20Favier?= <n@monade.li>
Date: Wed, 22 Dec 2021 12:37:59 +0100
Subject: [PATCH 354/567] Don't insert spaces when completing attribute paths

---
 misc/bash/completion.sh    |  4 +++-
 misc/fish/completion.fish  |  1 -
 src/libcmd/installables.cc | 10 +++++++---
 src/libutil/args.cc        |  4 ++--
 src/libutil/args.hh        |  8 +++++++-
 src/nix/main.cc            |  9 ++++++++-
 6 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/misc/bash/completion.sh b/misc/bash/completion.sh
index bea2a40bc..3eb44dfa6 100644
--- a/misc/bash/completion.sh
+++ b/misc/bash/completion.sh
@@ -7,8 +7,10 @@ function _complete_nix {
         local completion=${line%%	*}
         if [[ -z $have_type ]]; then
             have_type=1
-            if [[ $completion = filenames ]]; then
+            if [[ $completion == filenames ]]; then
                 compopt -o filenames
+            elif [[ $completion == attrs ]]; then
+                compopt -o nospace
             fi
         else
             COMPREPLY+=("$completion")
diff --git a/misc/fish/completion.fish b/misc/fish/completion.fish
index bedbefaf8..c6b8ef16a 100644
--- a/misc/fish/completion.fish
+++ b/misc/fish/completion.fish
@@ -19,7 +19,6 @@ end
 
 function _nix_accepts_files
   set -l response (_nix_complete)
-  # First line is either filenames or no-filenames.
   test $response[1] = 'filenames'
 end
 
diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index ef200b1d2..5f118b8d0 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -203,6 +203,8 @@ void SourceExprCommand::completeInstallable(std::string_view prefix)
         Value v2;
         state->autoCallFunction(*autoArgs, v1, v2);
 
+        completionType = ctAttrs;
+
         if (v2.type() == nAttrs) {
             for (auto & i : *v2.attrs) {
                 std::string name = i.name;
@@ -232,7 +234,9 @@ void completeFlakeRefWithFragment(
        prefix. */
     try {
         auto hash = prefix.find('#');
-        if (hash != std::string::npos) {
+        if (hash == std::string::npos) {
+            completeFlakeRef(evalState->store, prefix);
+        } else {
             auto fragment = prefix.substr(hash + 1);
             auto flakeRefS = std::string(prefix.substr(0, hash));
             // FIXME: do tilde expansion.
@@ -248,6 +252,8 @@ void completeFlakeRefWithFragment(
                flake. */
             attrPathPrefixes.push_back("");
 
+            completionType = ctAttrs;
+
             for (auto & attrPathPrefixS : attrPathPrefixes) {
                 auto attrPathPrefix = parseAttrPath(*evalState, attrPathPrefixS);
                 auto attrPathS = attrPathPrefixS + std::string(fragment);
@@ -285,8 +291,6 @@ void completeFlakeRefWithFragment(
     } catch (Error & e) {
         warn(e.msg());
     }
-
-    completeFlakeRef(evalState->store, prefix);
 }
 
 void completeFlakeRef(ref<Store> store, std::string_view prefix)
diff --git a/src/libutil/args.cc b/src/libutil/args.cc
index 9df279faf..a739d6b4e 100644
--- a/src/libutil/args.cc
+++ b/src/libutil/args.cc
@@ -39,7 +39,7 @@ void Completions::add(std::string completion, std::string description)
 bool Completion::operator<(const Completion & other) const
 { return completion < other.completion || (completion == other.completion && description < other.description); }
 
-bool pathCompletions = false;
+CompletionType completionType = ctNormal;
 std::shared_ptr<Completions> completions;
 
 std::string completionMarker = "___COMPLETE___";
@@ -277,7 +277,7 @@ Args::Flag Args::Flag::mkHashTypeOptFlag(std::string && longName, std::optional<
 
 static void _completePath(std::string_view prefix, bool onlyDirs)
 {
-    pathCompletions = true;
+    completionType = ctFilenames;
     glob_t globbuf;
     int flags = GLOB_NOESCAPE | GLOB_TILDE;
     #ifdef GLOB_ONLYDIR
diff --git a/src/libutil/args.hh b/src/libutil/args.hh
index 7521b3065..76b1cfe92 100644
--- a/src/libutil/args.hh
+++ b/src/libutil/args.hh
@@ -237,7 +237,13 @@ public:
     void add(std::string completion, std::string description = "");
 };
 extern std::shared_ptr<Completions> completions;
-extern bool pathCompletions;
+
+enum CompletionType {
+    ctNormal,
+    ctFilenames,
+    ctAttrs
+};
+extern CompletionType completionType;
 
 std::optional<std::string> needsCompletion(std::string_view s);
 
diff --git a/src/nix/main.cc b/src/nix/main.cc
index 60b0aa410..759118fd5 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -310,7 +310,14 @@ void mainWrapped(int argc, char * * argv)
     Finally printCompletions([&]()
     {
         if (completions) {
-            std::cout << (pathCompletions ? "filenames\n" : "no-filenames\n");
+            switch (completionType) {
+            case ctNormal:
+                std::cout << "normal\n"; break;
+            case ctFilenames:
+                std::cout << "filenames\n"; break;
+            case ctAttrs:
+                std::cout << "attrs\n"; break;
+            }
             for (auto & s : *completions)
                 std::cout << s.completion << "\t" << s.description << "\n";
         }

From c4a03bc4ae7ac89dfca3ada27d1a7946d568d4d3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Na=C3=AFm=20Favier?= <n@monade.li>
Date: Wed, 22 Dec 2021 16:37:58 +0100
Subject: [PATCH 355/567] Fix attr path completion after a dot

---
 src/libcmd/installables.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index 5f118b8d0..6c20bb7b1 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -191,7 +191,7 @@ void SourceExprCommand::completeInstallable(std::string_view prefix)
         auto sep = prefix_.rfind('.');
         std::string searchWord;
         if (sep != std::string::npos) {
-            searchWord = prefix_.substr(sep, std::string::npos);
+            searchWord = prefix_.substr(sep + 1, std::string::npos);
             prefix_ = prefix_.substr(0, sep);
         } else {
             searchWord = prefix_;

From dc89dfa7b3f8fa7368cd4c5e20891e60e418722b Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Thu, 23 Dec 2021 10:35:09 +0100
Subject: [PATCH 356/567] Properly return false on `builtins.pathExists
 /someNonAllowedPath`

Follow-up from https://github.com/NixOS/nix/pull/5807 to fix https://github.com/NixOS/nix/pull/5807#issuecomment-1000135394
---
 src/libexpr/primops.cc | 29 ++++++++++++++++++++++-------
 tests/pure-eval.sh     |  3 +++
 2 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index aff8f951e..62c21c7c5 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -89,18 +89,28 @@ StringMap EvalState::realiseContext(const PathSet & context)
     return res;
 }
 
-static Path realisePath(EvalState & state, const Pos & pos, Value & v, bool requireAbsolutePath = true)
+struct RealisePathFlags {
+    // Whether to check whether the path is a valid absolute path
+    bool requireAbsolutePath = true;
+    // Whether to check that the path is allowed in pure eval mode
+    bool checkForPureEval = true;
+};
+
+static Path realisePath(EvalState & state, const Pos & pos, Value & v, const RealisePathFlags flags = {})
 {
     PathSet context;
 
-    Path path = requireAbsolutePath
+    Path path = flags.requireAbsolutePath
         ? state.coerceToPath(pos, v, context)
         : state.coerceToString(pos, v, context, false, false);
 
     StringMap rewrites = state.realiseContext(context);
 
-    return state.checkSourcePath(
-            state.toRealPath(rewriteStrings(path, rewrites), context));
+    auto realPath = state.toRealPath(rewriteStrings(path, rewrites), context);
+
+    return flags.checkForPureEval
+        ? state.checkSourcePath(realPath)
+        : realPath;
 }
 
 /* Add and attribute to the given attribute map from the output name to
@@ -1371,7 +1381,12 @@ static void prim_pathExists(EvalState & state, const Pos & pos, Value * * args,
 {
     Path path;
     try {
-        path = realisePath(state, pos, *args[0]);
+        // We don’t check the path right now, because we don’t want to throw if
+        // the path isn’t allowed, but just return false
+        // (and we can’t just catch the exception here because we still want to
+        // throw if something in the evaluation of `*args[0]` tries to access an
+        // unauthorized path)
+        path = realisePath(state, pos, *args[0], { .checkForPureEval = false });
     } catch (InvalidPathError & e) {
         throw EvalError({
             .msg = hintfmt(
@@ -1382,7 +1397,7 @@ static void prim_pathExists(EvalState & state, const Pos & pos, Value * * args,
     }
 
     try {
-        mkBool(v, pathExists(path));
+        mkBool(v, pathExists(state.checkSourcePath(path)));
     } catch (SysError & e) {
         /* Don't give away info from errors while canonicalising
            ‘path’ in restricted mode. */
@@ -1496,7 +1511,7 @@ static void prim_findFile(EvalState & state, const Pos & pos, Value * * args, Va
         Path path;
 
         try {
-            path = realisePath(state, pos, *i->value, false);
+            path = realisePath(state, pos, *i->value, { .requireAbsolutePath = false });
         } catch (InvalidPathError & e) {
             throw EvalError({
                 .msg = hintfmt("cannot find '%1%', since path '%2%' is not valid", path, e.path),
diff --git a/tests/pure-eval.sh b/tests/pure-eval.sh
index cb4b5c5fc..1a4568ea6 100644
--- a/tests/pure-eval.sh
+++ b/tests/pure-eval.sh
@@ -11,6 +11,9 @@ missingImpureErrorMsg=$(! nix eval --expr 'builtins.readFile ./pure-eval.sh' 2>&
 echo "$missingImpureErrorMsg" | grep -q -- --impure || \
     fail "The error message should mention the “--impure” flag to unblock users"
 
+[[ $(nix eval --expr 'builtins.pathExists ./pure-eval.sh') == false ]] || \
+    fail "Calling 'pathExists' on a non-authorised path should return false"
+
 (! nix eval --expr builtins.currentTime)
 (! nix eval --expr builtins.currentSystem)
 

From b16643b6fc9abb5c243a1d83cfe0da93c441bb2c Mon Sep 17 00:00:00 2001
From: Nicolas Mattia <nicolas@nmattia.com>
Date: Thu, 23 Dec 2021 14:12:48 +0100
Subject: [PATCH 357/567] Use int64_t and NixFloat in fromTOML types

This makes sure that values parsed from TOML have a proper size. Using
e.g. `double` caused issues on i686 where the size of `double` (32bit)
was too small to accommodate some values.
---
 src/libexpr/primops/fromTOML.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libexpr/primops/fromTOML.cc b/src/libexpr/primops/fromTOML.cc
index bfea1ce34..221c40db9 100644
--- a/src/libexpr/primops/fromTOML.cc
+++ b/src/libexpr/primops/fromTOML.cc
@@ -47,10 +47,10 @@ static void prim_fromTOML(EvalState & state, const Pos & pos, Value * * args, Va
                 mkBool(v, toml::get<bool>(t));
                 break;;
             case toml::value_t::integer:
-                mkInt(v, toml::get<long>(t));
+                mkInt(v, toml::get<int64_t>(t));
                 break;;
             case toml::value_t::floating:
-                mkFloat(v, toml::get<double>(t));
+                mkFloat(v, toml::get<NixFloat>(t));
                 break;;
             case toml::value_t::string:
                 mkString(v, toml::get<std::string>(t));

From a4ab0a74d97c7c31df69f04870fa56cde89701a3 Mon Sep 17 00:00:00 2001
From: Yorick van Pelt <yorick@yorickvanpelt.nl>
Date: Mon, 27 Dec 2021 13:18:55 +0100
Subject: [PATCH 358/567] Fix accidental O(n^2 * log n) performance in
 NixRepl::addAttrsToScope

Only sort once, after adding all of the attrs first. This reduces my
`nix repl '<nixpkgs>'` loading time from 1.07s to 103ms.

Fixes #5823
---
 src/libexpr/nixexpr.hh |  7 +++++++
 src/nix/repl.cc        | 12 ++++++++++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index c013f5deb..b328b3941 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -368,6 +368,13 @@ struct StaticEnv
             [](const Vars::value_type & a, const Vars::value_type & b) { return a.first < b.first; });
     }
 
+    void deduplicate()
+    {
+        const auto last = std::unique(vars.begin(), vars.end(),
+            [] (const Vars::value_type & a, const Vars::value_type & b) { return a.first == b.first; });
+        vars.erase(last, vars.end());
+    }
+
     Vars::const_iterator find(const Symbol & name) const
     {
         Vars::value_type key(name, 0);
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 63ccbfda3..39a5a31de 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -661,8 +661,16 @@ void NixRepl::reloadFiles()
 void NixRepl::addAttrsToScope(Value & attrs)
 {
     state->forceAttrs(attrs);
-    for (auto & i : *attrs.attrs)
-        addVarToScope(i.name, *i.value);
+    if (displ + attrs.attrs->size() >= envSize)
+        throw Error("environment full; cannot add more variables");
+
+    for (auto & i : *attrs.attrs) {
+        staticEnv.vars.emplace_back(i.name, displ);
+        env->values[displ++] = i.value;
+        varNames.insert((string) i.name);
+    }
+    staticEnv.sort();
+    staticEnv.deduplicate();
     notice("Added %1% variables.", attrs.attrs->size());
 }
 

From 2664a216e57169ec57d7f51be1b8383c1be83fd5 Mon Sep 17 00:00:00 2001
From: Alexander Bantyev <balsoft@balsoft.ru>
Date: Tue, 28 Dec 2021 15:30:06 +0300
Subject: [PATCH 359/567] flake.cc: computeLocks: Only verify overrides when
 they could change

When we check for disappeared overrides, we can get "false positives"
for follows and overrides which are defined in the dependencies of the
flake we are locking, since they are not parsed by
parseFlakeInputs. However, at that point we already know that the
overrides couldn't have possible been changed if the input itself
hasn't changed (since we check that oldLock->originalRef == *input.ref
for the input's parent). So, to prevent this, only perform this check
when it was possible that the flake changed (e.g. the flake we're
locking, or a new input, or the input has changed and mustRefetch ==
true).
---
 src/libexpr/flake/flake.cc | 36 ++++++++++++++++++++++--------------
 tests/flakes.sh            | 10 +++-------
 2 files changed, 25 insertions(+), 21 deletions(-)

diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index b15878d5c..c549c5971 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -344,7 +344,8 @@ LockedFlake lockFlake(
             const InputPath & inputPathPrefix,
             std::shared_ptr<const Node> oldNode,
             const LockParent & parent,
-            const Path & parentPath)>
+            const Path & parentPath,
+            bool trustLock)>
             computeLocks;
 
         computeLocks = [&](
@@ -353,7 +354,8 @@ LockedFlake lockFlake(
             const InputPath & inputPathPrefix,
             std::shared_ptr<const Node> oldNode,
             const LockParent & parent,
-            const Path & parentPath)
+            const Path & parentPath,
+            bool trustLock)
         {
             debug("computing lock file node '%s'", printInputPath(inputPathPrefix));
 
@@ -464,14 +466,20 @@ LockedFlake lockFlake(
                                         .isFlake = (*lockedNode)->isFlake,
                                     });
                                 } else if (auto follows = std::get_if<1>(&i.second)) {
-                                    auto o = input.overrides.find(i.first);
-                                    // If the override disappeared, we have to refetch the flake,
-                                    // since some of the inputs may not be present in the lockfile.
-                                    if (o == input.overrides.end()) {
-                                        mustRefetch = true;
-                                        // There's no point populating the rest of the fake inputs,
-                                        // since we'll refetch the flake anyways.
-                                        break;
+                                    if (! trustLock) {
+                                        // It is possible that the flake has changed,
+                                        // so we must confirm all the follows that are in the lockfile are also in the flake.
+                                        auto overridePath(inputPath);
+                                        overridePath.push_back(i.first);
+                                        auto o = overrides.find(overridePath);
+                                        // If the override disappeared, we have to refetch the flake,
+                                        // since some of the inputs may not be present in the lockfile.
+                                        if (o == overrides.end()) {
+                                            mustRefetch = true;
+                                            // There's no point populating the rest of the fake inputs,
+                                            // since we'll refetch the flake anyways.
+                                            break;
+                                        }
                                     }
                                     fakeInputs.emplace(i.first, FlakeInput {
                                         .follows = *follows,
@@ -482,14 +490,14 @@ LockedFlake lockFlake(
 
                         LockParent newParent {
                             .path = inputPath,
-                            .absolute = false
+                            .absolute = true
                         };
 
                         computeLocks(
                             mustRefetch
                             ? getFlake(state, oldLock->lockedRef, false, flakeCache).inputs
                             : fakeInputs,
-                            childNode, inputPath, oldLock, newParent, parentPath);
+                            childNode, inputPath, oldLock, newParent, parentPath, !mustRefetch);
 
                     } else {
                         /* We need to create a new lock file entry. So fetch
@@ -546,7 +554,7 @@ LockedFlake lockFlake(
                                 ? std::dynamic_pointer_cast<const Node>(oldLock)
                                 : LockFile::read(
                                     inputFlake.sourceInfo->actualPath + "/" + inputFlake.lockedRef.subdir + "/flake.lock").root,
-                                newParent, localPath);
+                                newParent, localPath, false);
                         }
 
                         else {
@@ -574,7 +582,7 @@ LockedFlake lockFlake(
 
         computeLocks(
             flake.inputs, newLockFile.root, {},
-            lockFlags.recreateLockFile ? nullptr : oldLockFile.root, parent, parentPath);
+            lockFlags.recreateLockFile ? nullptr : oldLockFile.root, parent, parentPath, false);
 
         for (auto & i : lockFlags.inputOverrides)
             if (!overridesUsed.count(i.first))
diff --git a/tests/flakes.sh b/tests/flakes.sh
index 942d07010..20e6d09c1 100644
--- a/tests/flakes.sh
+++ b/tests/flakes.sh
@@ -716,11 +716,10 @@ cat > $flakeFollowsA/flake.nix <<EOF
     inputs = {
         B = {
             url = "path:./flakeB";
-            inputs.foobar.follows = "D";
-            inputs.nonFlake.follows = "D";
+            inputs.foobar.follows = "foobar";
         };
 
-        D.url = "path:./flakeD";
+        foobar.url = "path:$flakeFollowsA/flakeE";
     };
     outputs = { ... }: {};
 }
@@ -731,8 +730,6 @@ cat > $flakeFollowsB/flake.nix <<EOF
     description = "Flake B";
     inputs = {
         foobar.url = "path:$flakeFollowsA/flakeE";
-        nonFlake.url = "path:$nonFlakeDir";
-        goodoo.follows = "C/goodoo";
         C = {
             url = "path:./flakeC";
             inputs.foobar.follows = "foobar";
@@ -747,7 +744,6 @@ cat > $flakeFollowsC/flake.nix <<EOF
     description = "Flake C";
     inputs = {
         foobar.url = "path:$flakeFollowsA/flakeE";
-        goodoo.follows = "foobar";
     };
     outputs = { ... }: {};
 }
@@ -785,7 +781,7 @@ newLock="$(cat "$flakeFollowsA/flake.lock")"
 diff <(echo "$newLock") <(echo "$oldLock")
 
 [[ $(jq -c .nodes.B.inputs.C $flakeFollowsA/flake.lock) = '"C"' ]]
-[[ $(jq -c .nodes.B.inputs.foobar $flakeFollowsA/flake.lock) = '["D"]' ]]
+[[ $(jq -c .nodes.B.inputs.foobar $flakeFollowsA/flake.lock) = '["foobar"]' ]]
 [[ $(jq -c .nodes.C.inputs.foobar $flakeFollowsA/flake.lock) = '["B","foobar"]' ]]
 
 # Ensure removing follows from flake.nix removes them from the lockfile

From 581f774284fa1b833255218165f4c958fe741500 Mon Sep 17 00:00:00 2001
From: Alexander Bantyev <balsoft@balsoft.ru>
Date: Tue, 28 Dec 2021 15:53:21 +0300
Subject: [PATCH 360/567] BaseError::calcWhat: take loggerSettings.showTrace
 into account

Text representation for errors should include the trace if
--show-trace is passed.
---
 src/libutil/error.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libutil/error.cc b/src/libutil/error.cc
index 203d79087..dd9678ee7 100644
--- a/src/libutil/error.cc
+++ b/src/libutil/error.cc
@@ -25,7 +25,7 @@ const string & BaseError::calcWhat() const
         err.name = sname();
 
         std::ostringstream oss;
-        showErrorInfo(oss, err, false);
+        showErrorInfo(oss, err, loggerSettings.showTrace);
         what_ = oss.str();
 
         return *what_;

From 2dc29e0d932822baa50dbc3e81ae108382c39062 Mon Sep 17 00:00:00 2001
From: Alexander Bantyev <balsoft@balsoft.ru>
Date: Tue, 28 Dec 2021 15:54:46 +0300
Subject: [PATCH 361/567] Add a test that nix repl --show-trace actually shows
 the trace

---
 tests/repl.sh                | 10 +++++++++-
 tests/undefined-variable.nix |  1 +
 2 files changed, 10 insertions(+), 1 deletion(-)
 create mode 100644 tests/undefined-variable.nix

diff --git a/tests/repl.sh b/tests/repl.sh
index 995db869c..0e23a98db 100644
--- a/tests/repl.sh
+++ b/tests/repl.sh
@@ -13,6 +13,10 @@ failing = import ./simple-failing.nix
 :log failing
 "
 
+replUndefinedVariable="
+import ./undefined-variable.nix
+"
+
 testRepl () {
     local nixArgs=("$@")
     local replOutput="$(nix repl "${nixArgs[@]}" <<< "$replCmds")"
@@ -22,10 +26,14 @@ testRepl () {
     nix path-info "${nixArgs[@]}" "$outPath"
     # simple.nix prints a PATH during build
     echo "$replOutput" | grep -qs 'PATH=' || fail "nix repl :log doesn't output logs"
-    local replOutput="$(nix repl "${nixArgs[@]}" <<< "$replFailingCmds")"
+    local replOutput="$(nix repl "${nixArgs[@]}" <<< "$replFailingCmds" 2>&1)"
     echo "$replOutput"
     echo "$replOutput" | grep -qs 'This should fail' \
       || fail "nix repl :log doesn't output logs for a failed derivation"
+    local replOutput="$(nix repl --show-trace "${nixArgs[@]}" <<< "$replUndefinedVariable" 2>&1)"
+    echo "$replOutput"
+    echo "$replOutput" | grep -qs "while evaluating the file" \
+      || fail "nix repl --show-trace doesn't show the trace"
 }
 
 # Simple test, try building a drv
diff --git a/tests/undefined-variable.nix b/tests/undefined-variable.nix
new file mode 100644
index 000000000..579985497
--- /dev/null
+++ b/tests/undefined-variable.nix
@@ -0,0 +1 @@
+let f = builtins.toFile "test-file.nix" "asd"; in import f

From 92c7d33ee32b9597fedee5f7371de54c0a10a5a5 Mon Sep 17 00:00:00 2001
From: Lily Foster <lily@lily.flowers>
Date: Tue, 28 Dec 2021 10:10:58 -0500
Subject: [PATCH 362/567] Sort attrs from tables in fromTOML

This was dropped in 10a8b5d for the migration from cpptoml to toml11 but
seems to be necessary for the attrsets to work correctly.

Fixes #5833
---
 src/libexpr/primops/fromTOML.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/libexpr/primops/fromTOML.cc b/src/libexpr/primops/fromTOML.cc
index 221c40db9..30466fc5b 100644
--- a/src/libexpr/primops/fromTOML.cc
+++ b/src/libexpr/primops/fromTOML.cc
@@ -31,6 +31,8 @@ static void prim_fromTOML(EvalState & state, const Pos & pos, Value * * args, Va
                         auto & v2 = *state.allocAttr(v, state.symbols.create(elem.first));
                         visit(v2, elem.second);
                     }
+
+                    v.attrs->sort();
                 }
                 break;;
             case toml::value_t::array:

From a26351da02689d1e3ee562a6d89d93c12816e476 Mon Sep 17 00:00:00 2001
From: Alexander Bantyev <balsoft@balsoft.ru>
Date: Tue, 28 Dec 2021 16:13:07 +0300
Subject: [PATCH 363/567] Add ability to toggle show-trace from within the repl

---
 doc/manual/src/release-notes/rl-next.md |  2 ++
 src/nix/repl.cc                         | 15 ++++++++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index ac662c132..2a67a39b1 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -2,3 +2,5 @@
 
 * The TOML parser used by `builtins.fromTOML` has been replaced by [a
   more compliant one](https://github.com/ToruNiina/toml11).
+* Added `:st`/`:show-trace` commands to nix repl, which are used to
+  set or toggle display of error traces.
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 39a5a31de..a62ad66c2 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -430,7 +430,8 @@ bool NixRepl::processLine(string line)
              << "  :t <expr>     Describe result of evaluation\n"
              << "  :u <expr>     Build derivation, then start nix-shell\n"
              << "  :doc <expr>   Show documentation of a builtin function\n"
-             << "  :log <expr>   Show logs for a derivation\n";
+             << "  :log <expr>   Show logs for a derivation\n"
+             << "  :st [bool]    Enable, disable or toggle showing traces for errors\n";
     }
 
     else if (command == ":a" || command == ":add") {
@@ -572,6 +573,18 @@ bool NixRepl::processLine(string line)
             throw Error("value does not have documentation");
     }
 
+    else if (command == ":st" || command == ":show-trace") {
+        if (arg == "false" || (arg == "" && loggerSettings.showTrace)) {
+            std::cout << "not showing error traces\n";
+            loggerSettings.showTrace = false;
+        } else if (arg == "true" || (arg == "" && !loggerSettings.showTrace)) {
+            std::cout << "showing error traces\n";
+            loggerSettings.showTrace = true;
+        } else {
+            throw Error("unexpected argument '%s' to %s", arg, command);
+        };
+    }
+
     else if (command != "")
         throw Error("unknown command '%1%'", command);
 

From d0c8e9254e8a8271a3f044ee69774096e57a74bb Mon Sep 17 00:00:00 2001
From: Sebastian Ullrich <sebasti@nullri.ch>
Date: Wed, 29 Dec 2021 18:42:02 +0100
Subject: [PATCH 364/567] Fix IFD with chroot store

---
 src/libexpr/primops.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 62c21c7c5..7c964bd0d 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -82,7 +82,7 @@ StringMap EvalState::realiseContext(const PathSet & context)
        paths. */
     if (allowedPaths) {
         for (auto & [_placeholder, outputPath] : res) {
-            allowPath(outputPath);
+            allowPath(store->toRealPath(outputPath));
         }
     }
 

From d9aabb7acb4d697d4ba9527326602cf3abe77590 Mon Sep 17 00:00:00 2001
From: Wolfgang Thaller <wolfgang.thaller@gmx.net>
Date: Sat, 1 Jan 2022 16:47:05 +0100
Subject: [PATCH 365/567] docker.nix: set correct permissions on /tmp

---
 docker.nix | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/docker.nix b/docker.nix
index 25930bb87..bfccdb8f5 100644
--- a/docker.nix
+++ b/docker.nix
@@ -232,6 +232,9 @@ pkgs.dockerTools.buildLayeredImageWithNixDb {
     rm -rf nix-support
     ln -s /nix/var/nix/profiles nix/var/nix/gcroots/profiles
   '';
+  fakeRootCommands = ''
+    chmod 1777 tmp
+  '';
 
   config = {
     Cmd = [ "/root/.nix-profile/bin/bash" ];

From 00c993f48b1c752656d8cdd2c25e38f9ba572128 Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Sat, 25 Dec 2021 15:29:49 +0100
Subject: [PATCH 366/567] add zipAttrsWith primop

nixpkgs can save a good bit of eval memory with this primop. zipAttrsWith is
used quite a bit around nixpkgs (eg in the form of recursiveUpdate), but the
most costly application for this primop is in the module system. it improves
the implementation of zipAttrsWith from nixpkgs by not checking an attribute
multiple times if it occurs more than once in the input list, allocates less
values and set elements, and just avoids many a temporary object in general.

nixpkgs has a more generic version of this operation, zipAttrsWithNames, but
this version is only used once so isn't suitable for being the base of a new
primop. if it were to be used more we should add a second primop instead.
---
 doc/manual/src/release-notes/rl-next.md |  2 +
 src/libexpr/primops.cc                  | 84 +++++++++++++++++++++++++
 tests/lang/eval-okay-zipAttrsWith.exp   |  1 +
 tests/lang/eval-okay-zipAttrsWith.nix   |  9 +++
 4 files changed, 96 insertions(+)
 create mode 100644 tests/lang/eval-okay-zipAttrsWith.exp
 create mode 100644 tests/lang/eval-okay-zipAttrsWith.nix

diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index 2a67a39b1..a516887b1 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -4,3 +4,5 @@
   more compliant one](https://github.com/ToruNiina/toml11).
 * Added `:st`/`:show-trace` commands to nix repl, which are used to
   set or toggle display of error traces.
+* New builtin function `builtins.zipAttrsWith` with same functionality
+  as `lib.zipAttrsWith` from nixpkgs, but much more efficient.
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 7c964bd0d..ab99962f7 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -2503,6 +2503,90 @@ static RegisterPrimOp primop_mapAttrs({
     .fun = prim_mapAttrs,
 });
 
+static void prim_zipAttrsWith(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    // we will first count how many values are present for each given key.
+    // we then allocate a single attrset and pre-populate it with lists of
+    // appropriate sizes, stash the pointers to the list elements of each,
+    // and populate the lists. after that we replace the list in the every
+    // attribute with the merge function application. this way we need not
+    // use (slightly slower) temporary storage the GC does not know about.
+
+    std::map<Symbol, std::pair<size_t, Value * *>> attrsSeen;
+
+    state.forceFunction(*args[0], pos);
+    state.forceList(*args[1], pos);
+    const auto listSize = args[1]->listSize();
+    const auto listElems = args[1]->listElems();
+
+    for (unsigned int n = 0; n < listSize; ++n) {
+        Value * vElem = listElems[n];
+        try {
+            state.forceAttrs(*vElem);
+            for (auto & attr : *vElem->attrs)
+                attrsSeen[attr.name].first++;
+        } catch (TypeError & e) {
+            e.addTrace(pos, hintfmt("while invoking '%s'", "zipAttrsWith"));
+            throw;
+        }
+    }
+
+    state.mkAttrs(v, attrsSeen.size());
+    for (auto & [sym, elem] : attrsSeen) {
+        Value * list = state.allocAttr(v, sym);
+        state.mkList(*list, elem.first);
+        elem.second = list->listElems();
+    }
+
+    for (unsigned int n = 0; n < listSize; ++n) {
+        Value * vElem = listElems[n];
+        for (auto & attr : *vElem->attrs)
+            *attrsSeen[attr.name].second++ = attr.value;
+    }
+
+    for (auto & attr : *v.attrs) {
+        Value * name = state.allocValue();
+        mkString(*name, attr.name);
+        Value * call1 = state.allocValue();
+        mkApp(*call1, *args[0], *name);
+        Value * call2 = state.allocValue();
+        mkApp(*call2, *call1, *attr.value);
+        attr.value = call2;
+    }
+}
+
+static RegisterPrimOp primop_zipAttrsWith({
+    .name = "__zipAttrsWith",
+    .args = {"f", "list"},
+    .doc = R"(
+      Transpose a list of attribute sets into an attribute set of lists,
+      then apply `mapAttrs`.
+
+      `f` receives two arguments: the attribute name and a non-empty
+      list of all values encountered for that attribute name.
+
+      The result is an attribute set where the attribute names are the
+      union of the attribute names in each element of `list`. The attribute
+      values are the return values of `f`.
+
+      ```nix
+      builtins.zipAttrsWith
+        (name: values: { inherit name values; })
+        [ { a = "x"; } { a = "y"; b = "z"; } ]
+      ```
+
+      evaluates to
+
+      ```
+      {
+        a = { name = "a"; values = [ "x" "y" ]; };
+        b = { name = "b"; values = [ "z" ]; };
+      }
+      ```
+    )",
+    .fun = prim_zipAttrsWith,
+});
+
 
 /*************************************************************
  * Lists
diff --git a/tests/lang/eval-okay-zipAttrsWith.exp b/tests/lang/eval-okay-zipAttrsWith.exp
new file mode 100644
index 000000000..9c0b15d22
--- /dev/null
+++ b/tests/lang/eval-okay-zipAttrsWith.exp
@@ -0,0 +1 @@
+{ "0" = { n = "0"; v = [ 5 23 29 ]; }; "1" = { n = "1"; v = [ 7 30 ]; }; "2" = { n = "2"; v = [ 18 ]; }; "4" = { n = "4"; v = [ 10 ]; }; "5" = { n = "5"; v = [ 15 25 26 31 ]; }; "6" = { n = "6"; v = [ 3 14 ]; }; "7" = { n = "7"; v = [ 12 ]; }; "8" = { n = "8"; v = [ 2 6 8 9 ]; }; "9" = { n = "9"; v = [ 0 16 ]; }; a = { n = "a"; v = [ 17 21 22 27 ]; }; c = { n = "c"; v = [ 11 24 ]; }; d = { n = "d"; v = [ 4 13 28 ]; }; e = { n = "e"; v = [ 20 ]; }; f = { n = "f"; v = [ 1 19 ]; }; }
diff --git a/tests/lang/eval-okay-zipAttrsWith.nix b/tests/lang/eval-okay-zipAttrsWith.nix
new file mode 100644
index 000000000..877d4e5fa
--- /dev/null
+++ b/tests/lang/eval-okay-zipAttrsWith.nix
@@ -0,0 +1,9 @@
+with import ./lib.nix;
+
+let
+  str = builtins.hashString "sha256" "test";
+in
+builtins.zipAttrsWith
+  (n: v: { inherit n v; })
+  (map (n: { ${builtins.substring n 1 str} = n; })
+    (range 0 31))

From 9dd45dfc3d9ff3f9bb73dd890d7d7e02eb7c3d36 Mon Sep 17 00:00:00 2001
From: Sandro <sandro.jaeckel@gmail.com>
Date: Tue, 4 Jan 2022 12:49:02 +0100
Subject: [PATCH 367/567] Add iana-etc for /etc/protocols to default packages

---
 docker.nix | 1 +
 1 file changed, 1 insertion(+)

diff --git a/docker.nix b/docker.nix
index bfccdb8f5..28745fc5d 100644
--- a/docker.nix
+++ b/docker.nix
@@ -20,6 +20,7 @@ let
     man
     cacert.out
     findutils
+    iana-etc
   ];
 
   users = {

From 6d9a6d2cc3a20c9047436d174c9f91a2223da220 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 4 Jan 2022 17:39:16 +0100
Subject: [PATCH 368/567] Ensure that attrsets are sorted

Previously you had to remember to call value->attrs->sort() after
populating value->attrs. Now there is a BindingsBuilder helper that
wraps Bindings and ensures that sort() is called before you can use
it.
---
 src/libexpr/attr-set.cc               |  25 +++++-
 src/libexpr/attr-set.hh               |  34 ++++++++
 src/libexpr/common-eval-args.cc       |   9 +-
 src/libexpr/eval.cc                   |  50 ++++++-----
 src/libexpr/eval.hh                   |   7 +-
 src/libexpr/get-drvs.cc               |  13 ++-
 src/libexpr/primops.cc                | 120 ++++++++++++--------------
 src/libexpr/primops/context.cc        |  21 +++--
 src/libexpr/primops/fetchMercurial.cc |  14 +--
 src/libexpr/primops/fetchTree.cc      |  27 +++---
 src/libexpr/primops/fromTOML.cc       |  11 +--
 src/libexpr/value.hh                  |   8 ++
 src/nix-build/nix-build.cc            |  11 +--
 src/nix-env/nix-env.cc                |  28 +++---
 src/nix-env/user-env.cc               |  57 ++++++------
 src/nix/bundle.cc                     |  14 +--
 src/nix/main.cc                       |   9 +-
 17 files changed, 260 insertions(+), 198 deletions(-)

diff --git a/src/libexpr/attr-set.cc b/src/libexpr/attr-set.cc
index b6091c955..d74243f45 100644
--- a/src/libexpr/attr-set.cc
+++ b/src/libexpr/attr-set.cc
@@ -41,16 +41,39 @@ Value * EvalState::allocAttr(Value & vAttrs, const Symbol & name)
 }
 
 
-Value * EvalState::allocAttr(Value & vAttrs, const std::string & name)
+Value * EvalState::allocAttr(Value & vAttrs, std::string_view name)
 {
     return allocAttr(vAttrs, symbols.create(name));
 }
 
 
+Value & BindingsBuilder::alloc(const Symbol & name, ptr<Pos> pos)
+{
+    auto value = state.allocValue();
+    bindings->push_back(Attr(name, value, pos));
+    return *value;
+}
+
+
+Value & BindingsBuilder::alloc(std::string_view name, ptr<Pos> pos)
+{
+    return alloc(state.symbols.create(name), pos);
+}
+
+
 void Bindings::sort()
 {
     std::sort(begin(), end());
 }
 
 
+Value & Value::mkAttrs(BindingsBuilder & bindings)
+{
+    clearValue();
+    internalType = tAttrs;
+    attrs = bindings.finish();
+    return *this;
+}
+
+
 }
diff --git a/src/libexpr/attr-set.hh b/src/libexpr/attr-set.hh
index 7d6ffc9f3..903289b69 100644
--- a/src/libexpr/attr-set.hh
+++ b/src/libexpr/attr-set.hh
@@ -113,5 +113,39 @@ public:
     friend class EvalState;
 };
 
+/* A wrapper around Bindings that ensures that its always in sorted
+   order at the end. The only way to consume a BindingsBuilder is to
+   call finish(), which sorts the bindings. */
+class BindingsBuilder
+{
+    EvalState & state;
+    Bindings * bindings;
+
+public:
+
+    BindingsBuilder(EvalState & state, Bindings * bindings)
+        : state(state), bindings(bindings)
+    { }
+
+    void insert(Symbol name, Value * value, ptr<Pos> pos = ptr(&noPos))
+    {
+        insert(Attr(name, value, pos));
+    }
+
+    void insert(const Attr & attr)
+    {
+        bindings->push_back(attr);
+    }
+
+    Value & alloc(const Symbol & name, ptr<Pos> pos = ptr(&noPos));
+
+    Value & alloc(std::string_view name, ptr<Pos> pos = ptr(&noPos));
+
+    Bindings * finish()
+    {
+        bindings->sort();
+        return bindings;
+    }
+};
 
 }
diff --git a/src/libexpr/common-eval-args.cc b/src/libexpr/common-eval-args.cc
index fb0932c00..ecae2ca1f 100644
--- a/src/libexpr/common-eval-args.cc
+++ b/src/libexpr/common-eval-args.cc
@@ -73,17 +73,16 @@ MixEvalArgs::MixEvalArgs()
 
 Bindings * MixEvalArgs::getAutoArgs(EvalState & state)
 {
-    Bindings * res = state.allocBindings(autoArgs.size());
+    auto res = state.buildBindings(autoArgs.size());
     for (auto & i : autoArgs) {
-        Value * v = state.allocValue();
+        auto v = state.allocValue();
         if (i.second[0] == 'E')
             state.mkThunk_(*v, state.parseExprFromString(string(i.second, 1), absPath(".")));
         else
             mkString(*v, string(i.second, 1));
-        res->push_back(Attr(state.symbols.create(i.first), v));
+        res.insert(state.symbols.create(i.first), v);
     }
-    res->sort();
-    return res;
+    return res.finish();
 }
 
 Path lookupFileArg(EvalState & state, string s)
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index a95726f5f..0710ce270 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -772,18 +772,30 @@ void mkString(Value & v, const char * s)
 }
 
 
+void Value::mkString(std::string_view s)
+{
+    mkString(dupStringWithLen(s.data(), s.size()));
+}
+
+
 Value & mkString(Value & v, std::string_view s, const PathSet & context)
 {
-    v.mkString(dupStringWithLen(s.data(), s.size()));
+    v.mkString(s, context);
+    return v;
+}
+
+
+void Value::mkString(std::string_view s, const PathSet & context)
+{
+    mkString(s);
     if (!context.empty()) {
         size_t n = 0;
-        v.string.context = (const char * *)
+        string.context = (const char * *)
             allocBytes((context.size() + 1) * sizeof(char *));
         for (auto & i : context)
-            v.string.context[n++] = dupString(i.c_str());
-        v.string.context[n] = 0;
+            string.context[n++] = dupString(i.c_str());
+        string.context[n] = 0;
     }
-    return v;
 }
 
 
@@ -882,11 +894,11 @@ void EvalState::mkThunk_(Value & v, Expr * expr)
 void EvalState::mkPos(Value & v, ptr<Pos> pos)
 {
     if (pos->file.set()) {
-        mkAttrs(v, 3);
-        mkString(*allocAttr(v, sFile), pos->file);
-        mkInt(*allocAttr(v, sLine), pos->line);
-        mkInt(*allocAttr(v, sColumn), pos->column);
-        v.attrs->sort();
+        auto attrs = buildBindings(3);
+        attrs.alloc(sFile).mkString(pos->file);
+        attrs.alloc(sLine).mkInt(pos->line);
+        attrs.alloc(sColumn).mkInt(pos->column);
+        v.mkAttrs(attrs);
     } else
         mkNull(v);
 }
@@ -1341,7 +1353,7 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
                     /* Nope, so show the first unexpected argument to the
                        user. */
                     for (auto & i : *args[0]->attrs)
-                        if (lambda.formals->argNames.find(i.name) == lambda.formals->argNames.end())
+                        if (!lambda.formals->argNames.count(i.name))
                             throwTypeError(pos, "%1% called with unexpected argument '%2%'", lambda, i.name);
                     abort(); // can't happen
                 }
@@ -1484,22 +1496,20 @@ void EvalState::autoCallFunction(Bindings & args, Value & fun, Value & res)
         return;
     }
 
-    Value * actualArgs = allocValue();
-    mkAttrs(*actualArgs, std::max(static_cast<uint32_t>(fun.lambda.fun->formals->formals.size()), args.size()));
+    auto attrs = buildBindings(std::max(static_cast<uint32_t>(fun.lambda.fun->formals->formals.size()), args.size()));
 
     if (fun.lambda.fun->formals->ellipsis) {
         // If the formals have an ellipsis (eg the function accepts extra args) pass
         // all available automatic arguments (which includes arguments specified on
         // the command line via --arg/--argstr)
-        for (auto& v : args) {
-            actualArgs->attrs->push_back(v);
-        }
+        for (auto & v : args)
+            attrs.insert(v);
     } else {
         // Otherwise, only pass the arguments that the function accepts
         for (auto & i : fun.lambda.fun->formals->formals) {
             Bindings::iterator j = args.find(i.name);
             if (j != args.end()) {
-                actualArgs->attrs->push_back(*j);
+                attrs.insert(*j);
             } else if (!i.def) {
                 throwMissingArgumentError(i.pos, R"(cannot evaluate a function that has an argument without a value ('%1%')
 
@@ -1512,9 +1522,7 @@ https://nixos.org/manual/nix/stable/#ss-functions.)", i.name);
         }
     }
 
-    actualArgs->attrs->sort();
-
-    callFunction(fun, *actualArgs, res, noPos);
+    callFunction(fun, allocValue()->mkAttrs(attrs), res, noPos);
 }
 
 
@@ -1719,7 +1727,7 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
         auto path = canonPath(s.str());
         mkPath(v, path.c_str());
     } else
-        mkString(v, s.str(), context);
+        v.mkString(s.str(), context);
 }
 
 
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index d7ef7b88a..44ccc6593 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -339,10 +339,15 @@ public:
     Env & allocEnv(size_t size);
 
     Value * allocAttr(Value & vAttrs, const Symbol & name);
-    Value * allocAttr(Value & vAttrs, const std::string & name);
+    Value * allocAttr(Value & vAttrs, std::string_view name);
 
     Bindings * allocBindings(size_t capacity);
 
+    BindingsBuilder buildBindings(size_t capacity)
+    {
+        return BindingsBuilder(*this, allocBindings(capacity));
+    }
+
     void mkList(Value & v, size_t length);
     void mkAttrs(Value & v, size_t capacity);
     void mkThunk_(Value & v, Expr * expr);
diff --git a/src/libexpr/get-drvs.cc b/src/libexpr/get-drvs.cc
index ed4c47fbb..25fd9b949 100644
--- a/src/libexpr/get-drvs.cc
+++ b/src/libexpr/get-drvs.cc
@@ -254,15 +254,14 @@ bool DrvInfo::queryMetaBool(const string & name, bool def)
 void DrvInfo::setMeta(const string & name, Value * v)
 {
     getMeta();
-    Bindings * old = meta;
-    meta = state->allocBindings(1 + (old ? old->size() : 0));
+    auto attrs = state->buildBindings(1 + (meta ? meta->size() : 0));
     Symbol sym = state->symbols.create(name);
-    if (old)
-        for (auto i : *old)
+    if (meta)
+        for (auto i : *meta)
             if (i.name != sym)
-                meta->push_back(i);
-    if (v) meta->push_back(Attr(sym, v));
-    meta->sort();
+                attrs.insert(i);
+    if (v) attrs.insert(sym, v);
+    meta = attrs.finish();
 }
 
 
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index ab99962f7..daf5fc927 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -125,13 +125,15 @@ static Path realisePath(EvalState & state, const Pos & pos, Value & v, const Rea
    the actual path.
 
    The 'drv' and 'drvPath' outputs must correspond. */
-static void mkOutputString(EvalState & state, Value & v,
-    const StorePath & drvPath, const BasicDerivation & drv,
-    std::pair<string, DerivationOutput> o)
+static void mkOutputString(
+    EvalState & state,
+    BindingsBuilder & attrs,
+    const StorePath & drvPath,
+    const BasicDerivation & drv,
+    const std::pair<string, DerivationOutput> & o)
 {
     auto optOutputPath = o.second.path(*state.store, drv.name, o.first);
-    mkString(
-        *state.allocAttr(v, state.symbols.create(o.first)),
+    attrs.alloc(o.first).mkString(
         optOutputPath
             ? state.store->printStorePath(*optOutputPath)
             /* Downstream we would substitute this for an actual path once
@@ -172,23 +174,19 @@ static void import(EvalState & state, const Pos & pos, Value & vPath, Value * vS
     if (auto optStorePath = isValidDerivationInStore()) {
         auto storePath = *optStorePath;
         Derivation drv = state.store->readDerivation(storePath);
-        Value & w = *state.allocValue();
-        state.mkAttrs(w, 3 + drv.outputs.size());
-        Value * v2 = state.allocAttr(w, state.sDrvPath);
-        mkString(*v2, path, {"=" + path});
-        v2 = state.allocAttr(w, state.sName);
-        mkString(*v2, drv.env["name"]);
-        Value * outputsVal =
-            state.allocAttr(w, state.symbols.create("outputs"));
-        state.mkList(*outputsVal, drv.outputs.size());
-        unsigned int outputs_index = 0;
+        auto attrs = state.buildBindings(3 + drv.outputs.size());
+        attrs.alloc(state.sDrvPath).mkString(path, {"=" + path});
+        attrs.alloc(state.sName).mkString(drv.env["name"]);
+        auto & outputsVal = attrs.alloc(state.sOutputs);
+        state.mkList(outputsVal, drv.outputs.size());
 
-        for (const auto & o : drv.outputs) {
-            mkOutputString(state, w, storePath, drv, o);
-            outputsVal->listElems()[outputs_index] = state.allocValue();
-            mkString(*(outputsVal->listElems()[outputs_index++]), o.first);
+        for (const auto & [i, o] : enumerate(drv.outputs)) {
+            mkOutputString(state, attrs, storePath, drv, o);
+            (outputsVal.listElems()[i] = state.allocValue())->mkString(o.first);
         }
-        w.attrs->sort();
+
+        auto w = state.allocValue();
+        w->mkAttrs(attrs);
 
         if (!state.vImportedDrvToDerivation) {
             state.vImportedDrvToDerivation = allocRootValue(state.allocValue());
@@ -198,7 +196,7 @@ static void import(EvalState & state, const Pos & pos, Value & vPath, Value * vS
         }
 
         state.forceFunction(**state.vImportedDrvToDerivation, pos);
-        mkApp(v, **state.vImportedDrvToDerivation, w);
+        mkApp(v, **state.vImportedDrvToDerivation, *w);
         state.forceAttrs(v, pos);
     }
 
@@ -802,16 +800,16 @@ static RegisterPrimOp primop_floor({
  * else => {success=false; value=false;} */
 static void prim_tryEval(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    state.mkAttrs(v, 2);
+    auto attrs = state.buildBindings(2);
     try {
         state.forceValue(*args[0], pos);
-        v.attrs->push_back(Attr(state.sValue, args[0]));
-        mkBool(*state.allocAttr(v, state.symbols.create("success")), true);
+        attrs.insert(state.sValue, args[0]);
+        mkBool(attrs.alloc("success"), true);
     } catch (AssertionError & e) {
-        mkBool(*state.allocAttr(v, state.sValue), false);
-        mkBool(*state.allocAttr(v, state.symbols.create("success")), false);
+        mkBool(attrs.alloc(state.sValue), false);
+        mkBool(attrs.alloc("success"), false);
     }
-    v.attrs->sort();
+    v.mkAttrs(attrs);
 }
 
 static RegisterPrimOp primop_tryEval({
@@ -839,7 +837,7 @@ static RegisterPrimOp primop_tryEval({
 static void prim_getEnv(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     string name = state.forceStringNoCtx(*args[0], pos);
-    mkString(v, evalSettings.restrictEval || evalSettings.pureEval ? "" : getEnv(name).value_or(""));
+    v.mkString(evalSettings.restrictEval || evalSettings.pureEval ? "" : getEnv(name).value_or(""));
 }
 
 static RegisterPrimOp primop_getEnv({
@@ -1265,11 +1263,11 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
         drvHashes.lock()->insert_or_assign(drvPath, h);
     }
 
-    state.mkAttrs(v, 1 + drv.outputs.size());
-    mkString(*state.allocAttr(v, state.sDrvPath), drvPathS, {"=" + drvPathS});
+    auto attrs = state.buildBindings(1 + drv.outputs.size());
+    attrs.alloc(state.sDrvPath).mkString(drvPathS, {"=" + drvPathS});
     for (auto & i : drv.outputs)
-        mkOutputString(state, v, drvPath, drv, i);
-    v.attrs->sort();
+        mkOutputString(state, attrs, drvPath, drv, i);
+    v.mkAttrs(attrs);
 }
 
 static RegisterPrimOp primop_derivationStrict(RegisterPrimOp::Info {
@@ -1579,20 +1577,20 @@ static void prim_readDir(EvalState & state, const Pos & pos, Value * * args, Val
     }
 
     DirEntries entries = readDirectory(path);
-    state.mkAttrs(v, entries.size());
+
+    auto attrs = state.buildBindings(entries.size());
 
     for (auto & ent : entries) {
-        Value * ent_val = state.allocAttr(v, state.symbols.create(ent.name));
         if (ent.type == DT_UNKNOWN)
             ent.type = getFileType(path + "/" + ent.name);
-        ent_val->mkString(
+        attrs.alloc(ent.name).mkString(
             ent.type == DT_REG ? "regular" :
             ent.type == DT_DIR ? "directory" :
             ent.type == DT_LNK ? "symlink" :
             "unknown");
     }
 
-    v.attrs->sort();
+    v.mkAttrs(attrs);
 }
 
 static RegisterPrimOp primop_readDir({
@@ -2308,7 +2306,7 @@ static void prim_listToAttrs(EvalState & state, const Pos & pos, Value * * args,
 {
     state.forceList(*args[0], pos);
 
-    state.mkAttrs(v, args[0]->listSize());
+    auto attrs = state.buildBindings(args[0]->listSize());
 
     std::set<Symbol> seen;
 
@@ -2334,11 +2332,11 @@ static void prim_listToAttrs(EvalState & state, const Pos & pos, Value * * args,
                 v2->attrs,
                 pos
             );
-            v.attrs->push_back(Attr(sym, j2->value, j2->pos));
+            attrs.insert(sym, j2->value, j2->pos);
         }
     }
 
-    v.attrs->sort();
+    v.mkAttrs(attrs);
 }
 
 static RegisterPrimOp primop_listToAttrs({
@@ -2445,14 +2443,11 @@ static void prim_functionArgs(EvalState & state, const Pos & pos, Value * * args
         return;
     }
 
-    state.mkAttrs(v, args[0]->lambda.fun->formals->formals.size());
-    for (auto & i : args[0]->lambda.fun->formals->formals) {
+    auto attrs = state.buildBindings(args[0]->lambda.fun->formals->formals.size());
+    for (auto & i : args[0]->lambda.fun->formals->formals)
         // !!! should optimise booleans (allocate only once)
-        Value * value = state.allocValue();
-        v.attrs->push_back(Attr(i.name, value, ptr(&i.pos)));
-        mkBool(*value, i.def);
-    }
-    v.attrs->sort();
+        mkBool(attrs.alloc(i.name, ptr(&i.pos)), i.def);
+    v.mkAttrs(attrs);
 }
 
 static RegisterPrimOp primop_functionArgs({
@@ -3003,21 +2998,21 @@ static void prim_partition(EvalState & state, const Pos & pos, Value * * args, V
             wrong.push_back(vElem);
     }
 
-    state.mkAttrs(v, 2);
+    auto attrs = state.buildBindings(2);
 
-    Value * vRight = state.allocAttr(v, state.sRight);
+    auto & vRight = attrs.alloc(state.sRight);
     auto rsize = right.size();
-    state.mkList(*vRight, rsize);
+    state.mkList(vRight, rsize);
     if (rsize)
-        memcpy(vRight->listElems(), right.data(), sizeof(Value *) * rsize);
+        memcpy(vRight.listElems(), right.data(), sizeof(Value *) * rsize);
 
-    Value * vWrong = state.allocAttr(v, state.sWrong);
+    auto & vWrong = attrs.alloc(state.sWrong);
     auto wsize = wrong.size();
-    state.mkList(*vWrong, wsize);
+    state.mkList(vWrong, wsize);
     if (wsize)
-        memcpy(vWrong->listElems(), wrong.data(), sizeof(Value *) * wsize);
+        memcpy(vWrong.listElems(), wrong.data(), sizeof(Value *) * wsize);
 
-    v.attrs->sort();
+    v.mkAttrs(attrs);
 }
 
 static RegisterPrimOp primop_partition({
@@ -3734,10 +3729,10 @@ static void prim_parseDrvName(EvalState & state, const Pos & pos, Value * * args
 {
     string name = state.forceStringNoCtx(*args[0], pos);
     DrvName parsed(name);
-    state.mkAttrs(v, 2);
-    mkString(*state.allocAttr(v, state.sName), parsed.name);
-    mkString(*state.allocAttr(v, state.symbols.create("version")), parsed.version);
-    v.attrs->sort();
+    auto attrs = state.buildBindings(2);
+    attrs.alloc(state.sName).mkString(parsed.name);
+    attrs.alloc("version").mkString(parsed.version);
+    v.mkAttrs(attrs);
 }
 
 static RegisterPrimOp primop_parseDrvName({
@@ -3883,11 +3878,10 @@ void EvalState::createBaseEnv()
     mkList(v, searchPath.size());
     int n = 0;
     for (auto & i : searchPath) {
-        auto v2 = v.listElems()[n++] = allocValue();
-        mkAttrs(*v2, 2);
-        mkString(*allocAttr(*v2, symbols.create("path")), i.second);
-        mkString(*allocAttr(*v2, symbols.create("prefix")), i.first);
-        v2->attrs->sort();
+        auto attrs = buildBindings(2);
+        attrs.alloc("path").mkString(i.second);
+        attrs.alloc("prefix").mkString(i.first);
+        (v.listElems()[n++] = allocValue())->mkAttrs(attrs);
     }
     addConstant("__nixPath", v);
 
diff --git a/src/libexpr/primops/context.cc b/src/libexpr/primops/context.cc
index 20545afd0..ab08303d8 100644
--- a/src/libexpr/primops/context.cc
+++ b/src/libexpr/primops/context.cc
@@ -103,27 +103,26 @@ static void prim_getContext(EvalState & state, const Pos & pos, Value * * args,
         }
     }
 
-    state.mkAttrs(v, contextInfos.size());
+    auto attrs = state.buildBindings(contextInfos.size());
 
     auto sPath = state.symbols.create("path");
     auto sAllOutputs = state.symbols.create("allOutputs");
     for (const auto & info : contextInfos) {
-        auto & infoVal = *state.allocAttr(v, state.symbols.create(info.first));
-        state.mkAttrs(infoVal, 3);
+        auto infoAttrs = state.buildBindings(3);
         if (info.second.path)
-            mkBool(*state.allocAttr(infoVal, sPath), true);
+            mkBool(infoAttrs.alloc(sPath), true);
         if (info.second.allOutputs)
-            mkBool(*state.allocAttr(infoVal, sAllOutputs), true);
+            mkBool(infoAttrs.alloc(sAllOutputs), true);
         if (!info.second.outputs.empty()) {
-            auto & outputsVal = *state.allocAttr(infoVal, state.sOutputs);
+            auto & outputsVal = infoAttrs.alloc(state.sOutputs);
             state.mkList(outputsVal, info.second.outputs.size());
-            size_t i = 0;
-            for (const auto & output : info.second.outputs)
-                mkString(*(outputsVal.listElems()[i++] = state.allocValue()), output);
+            for (const auto & [i, output] : enumerate(info.second.outputs))
+                (outputsVal.listElems()[i] = state.allocValue())->mkString(output);
         }
-        infoVal.attrs->sort();
+        attrs.alloc(info.first).mkAttrs(infoAttrs);
     }
-    v.attrs->sort();
+
+    v.mkAttrs(attrs);
 }
 
 static RegisterPrimOp primop_getContext("__getContext", 1, prim_getContext);
diff --git a/src/libexpr/primops/fetchMercurial.cc b/src/libexpr/primops/fetchMercurial.cc
index c23480853..42214c207 100644
--- a/src/libexpr/primops/fetchMercurial.cc
+++ b/src/libexpr/primops/fetchMercurial.cc
@@ -70,19 +70,19 @@ static void prim_fetchMercurial(EvalState & state, const Pos & pos, Value * * ar
     // FIXME: use name
     auto [tree, input2] = input.fetch(state.store);
 
-    state.mkAttrs(v, 8);
+    auto attrs2 = state.buildBindings(8);
     auto storePath = state.store->printStorePath(tree.storePath);
-    mkString(*state.allocAttr(v, state.sOutPath), storePath, PathSet({storePath}));
+    attrs2.alloc(state.sOutPath).mkString(storePath, {storePath});
     if (input2.getRef())
-        mkString(*state.allocAttr(v, state.symbols.create("branch")), *input2.getRef());
+        attrs2.alloc("branch").mkString(*input2.getRef());
     // Backward compatibility: set 'rev' to
     // 0000000000000000000000000000000000000000 for a dirty tree.
     auto rev2 = input2.getRev().value_or(Hash(htSHA1));
-    mkString(*state.allocAttr(v, state.symbols.create("rev")), rev2.gitRev());
-    mkString(*state.allocAttr(v, state.symbols.create("shortRev")), std::string(rev2.gitRev(), 0, 12));
+    attrs2.alloc("rev").mkString(rev2.gitRev());
+    attrs2.alloc("shortRev").mkString(rev2.gitRev().substr(0, 12));
     if (auto revCount = input2.getRevCount())
-        mkInt(*state.allocAttr(v, state.symbols.create("revCount")), *revCount);
-    v.attrs->sort();
+        attrs2.alloc("revCount").mkInt(*revCount);
+    v.mkAttrs(attrs2);
 
     state.allowPath(tree.storePath);
 }
diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index 079513873..a97bfcae7 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -21,49 +21,48 @@ void emitTreeAttrs(
 {
     assert(input.isImmutable());
 
-    state.mkAttrs(v, 8);
+    auto attrs = state.buildBindings(8);
 
     auto storePath = state.store->printStorePath(tree.storePath);
 
-    mkString(*state.allocAttr(v, state.sOutPath), storePath, PathSet({storePath}));
+    attrs.alloc(state.sOutPath).mkString(storePath, {storePath});
 
     // FIXME: support arbitrary input attributes.
 
     auto narHash = input.getNarHash();
     assert(narHash);
-    mkString(*state.allocAttr(v, state.symbols.create("narHash")),
-        narHash->to_string(SRI, true));
+    attrs.alloc("narHash").mkString(narHash->to_string(SRI, true));
 
     if (input.getType() == "git")
-        mkBool(*state.allocAttr(v, state.symbols.create("submodules")),
+        attrs.alloc("submodules").mkBool(
             fetchers::maybeGetBoolAttr(input.attrs, "submodules").value_or(false));
 
     if (!forceDirty) {
 
         if (auto rev = input.getRev()) {
-            mkString(*state.allocAttr(v, state.symbols.create("rev")), rev->gitRev());
-            mkString(*state.allocAttr(v, state.symbols.create("shortRev")), rev->gitShortRev());
+            attrs.alloc("rev").mkString(rev->gitRev());
+            attrs.alloc("shortRev").mkString(rev->gitShortRev());
         } else if (emptyRevFallback) {
             // Backwards compat for `builtins.fetchGit`: dirty repos return an empty sha1 as rev
             auto emptyHash = Hash(htSHA1);
-            mkString(*state.allocAttr(v, state.symbols.create("rev")), emptyHash.gitRev());
-            mkString(*state.allocAttr(v, state.symbols.create("shortRev")), emptyHash.gitShortRev());
+            attrs.alloc("rev").mkString(emptyHash.gitRev());
+            attrs.alloc("shortRev").mkString(emptyHash.gitShortRev());
         }
 
         if (auto revCount = input.getRevCount())
-            mkInt(*state.allocAttr(v, state.symbols.create("revCount")), *revCount);
+            attrs.alloc("revCount").mkInt(*revCount);
         else if (emptyRevFallback)
-            mkInt(*state.allocAttr(v, state.symbols.create("revCount")), 0);
+            attrs.alloc("revCount").mkInt(0);
 
     }
 
     if (auto lastModified = input.getLastModified()) {
-        mkInt(*state.allocAttr(v, state.symbols.create("lastModified")), *lastModified);
-        mkString(*state.allocAttr(v, state.symbols.create("lastModifiedDate")),
+        attrs.alloc("lastModified").mkInt(*lastModified);
+        attrs.alloc("lastModifiedDate").mkString(
             fmt("%s", std::put_time(std::gmtime(&*lastModified), "%Y%m%d%H%M%S")));
     }
 
-    v.attrs->sort();
+    v.mkAttrs(attrs);
 }
 
 std::string fixURI(std::string uri, EvalState & state, const std::string & defaultScheme = "file")
diff --git a/src/libexpr/primops/fromTOML.cc b/src/libexpr/primops/fromTOML.cc
index 30466fc5b..a328b6736 100644
--- a/src/libexpr/primops/fromTOML.cc
+++ b/src/libexpr/primops/fromTOML.cc
@@ -24,15 +24,12 @@ static void prim_fromTOML(EvalState & state, const Pos & pos, Value * * args, Va
                     size_t size = 0;
                     for (auto & i : table) { (void) i; size++; }
 
-                    state.mkAttrs(v, size);
+                    auto attrs = state.buildBindings(size);
 
-                    for(auto & elem: table) {
+                    for(auto & elem : table)
+                        visit(attrs.alloc(elem.first), elem.second);
 
-                        auto & v2 = *state.allocAttr(v, state.symbols.create(elem.first));
-                        visit(v2, elem.second);
-                    }
-
-                    v.attrs->sort();
+                    v.mkAttrs(attrs);
                 }
                 break;;
             case toml::value_t::array:
diff --git a/src/libexpr/value.hh b/src/libexpr/value.hh
index 6b4f3c0ae..a8fea02dc 100644
--- a/src/libexpr/value.hh
+++ b/src/libexpr/value.hh
@@ -10,6 +10,8 @@
 
 namespace nix {
 
+class BindingsBuilder;
+
 
 typedef enum {
     tInt = 1,
@@ -235,6 +237,10 @@ public:
         string.context = context;
     }
 
+    void mkString(std::string_view s);
+
+    void mkString(std::string_view s, const PathSet & context);
+
     inline void mkPath(const char * s)
     {
         clearValue();
@@ -255,6 +261,8 @@ public:
         attrs = a;
     }
 
+    Value & mkAttrs(BindingsBuilder & bindings);
+
     inline void mkList(size_t size)
     {
         clearValue();
diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index d3d6ce1ce..b73eb0795 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -258,13 +258,10 @@ static void main_nix_build(int argc, char * * argv)
     auto autoArgs = myArgs.getAutoArgs(*state);
 
     if (runEnv) {
-        auto newArgs = state->allocBindings(autoArgs->size() + 1);
-        auto tru = state->allocValue();
-        mkBool(*tru, true);
-        newArgs->push_back(Attr(state->symbols.create("inNixShell"), tru));
-        for (auto & i : *autoArgs) newArgs->push_back(i);
-        newArgs->sort();
-        autoArgs = newArgs;
+        auto newArgs = state->buildBindings(autoArgs->size() + 1);
+        newArgs.alloc("inNixShell").mkBool(true);
+        for (auto & i : *autoArgs) newArgs.insert(i);
+        autoArgs = newArgs.finish();
     }
 
     if (packages) {
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index b9e7be1c6..171f1c440 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -98,8 +98,11 @@ static bool isNixExpr(const Path & path, struct stat & st)
 }
 
 
+static constexpr size_t maxAttrs = 1024;
+
+
 static void getAllExprs(EvalState & state,
-    const Path & path, StringSet & attrs, Value & v)
+    const Path & path, StringSet & seen, BindingsBuilder & attrs)
 {
     StringSet namesSorted;
     for (auto & i : readDirectory(path)) namesSorted.insert(i.name);
@@ -124,22 +127,21 @@ static void getAllExprs(EvalState & state,
             string attrName = i;
             if (hasSuffix(attrName, ".nix"))
                 attrName = string(attrName, 0, attrName.size() - 4);
-            if (!attrs.insert(attrName).second) {
+            if (!seen.insert(attrName).second) {
                 printError("warning: name collision in input Nix expressions, skipping '%1%'", path2);
                 continue;
             }
             /* Load the expression on demand. */
-            Value & vFun = state.getBuiltin("import");
-            Value & vArg(*state.allocValue());
-            mkString(vArg, path2);
-            if (v.attrs->size() == v.attrs->capacity())
+            auto vArg = state.allocValue();
+            vArg->mkString(path2);
+            if (seen.size() == maxAttrs)
                 throw Error("too many Nix expressions in directory '%1%'", path);
-            mkApp(*state.allocAttr(v, state.symbols.create(attrName)), vFun, vArg);
+            attrs.alloc(attrName).mkApp(&state.getBuiltin("import"), vArg);
         }
         else if (S_ISDIR(st.st_mode))
             /* `path2' is a directory (with no default.nix in it);
                recurse into it. */
-            getAllExprs(state, path2, attrs, v);
+            getAllExprs(state, path2, seen, attrs);
     }
 }
 
@@ -161,11 +163,11 @@ static void loadSourceExpr(EvalState & state, const Path & path, Value & v)
        ~/.nix-defexpr directory that includes some system-wide
        directory). */
     else if (S_ISDIR(st.st_mode)) {
-        state.mkAttrs(v, 1024);
-        state.mkList(*state.allocAttr(v, state.symbols.create("_combineChannels")), 0);
-        StringSet attrs;
-        getAllExprs(state, path, attrs, v);
-        v.attrs->sort();
+        auto attrs = state.buildBindings(maxAttrs);
+        attrs.alloc("_combineChannels").mkList(0);
+        StringSet seen;
+        getAllExprs(state, path, seen, attrs);
+        v.mkAttrs(attrs);
     }
 
     else throw Error("path '%s' is not a directory or a Nix expression", path);
diff --git a/src/nix-env/user-env.cc b/src/nix-env/user-env.cc
index 1fd4bcbd3..68c1c16b2 100644
--- a/src/nix-env/user-env.cc
+++ b/src/nix-env/user-env.cc
@@ -50,7 +50,7 @@ bool createUserEnv(EvalState & state, DrvInfos & elems,
     StorePathSet references;
     Value manifest;
     state.mkList(manifest, elems.size());
-    unsigned int n = 0;
+    size_t n = 0;
     for (auto & i : elems) {
         /* Create a pseudo-derivation containing the name, system,
            output paths, and optionally the derivation path, as well
@@ -59,28 +59,25 @@ bool createUserEnv(EvalState & state, DrvInfos & elems,
         DrvInfo::Outputs outputs = i.queryOutputs(true);
         StringSet metaNames = i.queryMetaNames();
 
-        Value & v(*state.allocValue());
-        manifest.listElems()[n++] = &v;
-        state.mkAttrs(v, 7 + outputs.size());
+        auto attrs = state.buildBindings(7 + outputs.size());
 
-        mkString(*state.allocAttr(v, state.sType), "derivation");
-        mkString(*state.allocAttr(v, state.sName), i.queryName());
+        attrs.alloc(state.sType).mkString("derivation");
+        attrs.alloc(state.sName).mkString(i.queryName());
         auto system = i.querySystem();
         if (!system.empty())
-            mkString(*state.allocAttr(v, state.sSystem), system);
-        mkString(*state.allocAttr(v, state.sOutPath), i.queryOutPath());
+            attrs.alloc(state.sSystem).mkString(system);
+        attrs.alloc(state.sOutPath).mkString(i.queryOutPath());
         if (drvPath != "")
-            mkString(*state.allocAttr(v, state.sDrvPath), i.queryDrvPath());
+            attrs.alloc(state.sDrvPath).mkString(i.queryDrvPath());
 
         // Copy each output meant for installation.
-        Value & vOutputs = *state.allocAttr(v, state.sOutputs);
+        auto & vOutputs = attrs.alloc(state.sOutputs);
         state.mkList(vOutputs, outputs.size());
-        unsigned int m = 0;
-        for (auto & j : outputs) {
-            mkString(*(vOutputs.listElems()[m++] = state.allocValue()), j.first);
-            Value & vOutputs = *state.allocAttr(v, state.symbols.create(j.first));
-            state.mkAttrs(vOutputs, 2);
-            mkString(*state.allocAttr(vOutputs, state.sOutPath), j.second);
+        for (const auto & [m, j] : enumerate(outputs)) {
+            (vOutputs.listElems()[m] = state.allocValue())->mkString(j.first);
+            auto outputAttrs = state.buildBindings(2);
+            outputAttrs.alloc(state.sOutPath).mkString(j.second);
+            attrs.alloc(j.first).mkAttrs(outputAttrs);
 
             /* This is only necessary when installing store paths, e.g.,
                `nix-env -i /nix/store/abcd...-foo'. */
@@ -91,15 +88,16 @@ bool createUserEnv(EvalState & state, DrvInfos & elems,
         }
 
         // Copy the meta attributes.
-        Value & vMeta = *state.allocAttr(v, state.sMeta);
-        state.mkAttrs(vMeta, metaNames.size());
+        auto meta = state.buildBindings(metaNames.size());
         for (auto & j : metaNames) {
             Value * v = i.queryMeta(j);
             if (!v) continue;
-            vMeta.attrs->push_back(Attr(state.symbols.create(j), v));
+            meta.insert(state.symbols.create(j), v);
         }
-        vMeta.attrs->sort();
-        v.attrs->sort();
+
+        attrs.alloc(state.sMeta).mkAttrs(meta);
+
+        (manifest.listElems()[n++] = state.allocValue())->mkAttrs(attrs);
 
         if (drvPath != "") references.insert(state.store->parseStorePath(drvPath));
     }
@@ -118,13 +116,16 @@ bool createUserEnv(EvalState & state, DrvInfos & elems,
 
     /* Construct a Nix expression that calls the user environment
        builder with the manifest as argument. */
-    Value args, topLevel;
-    state.mkAttrs(args, 3);
-    mkString(*state.allocAttr(args, state.symbols.create("manifest")),
-        state.store->printStorePath(manifestFile), {state.store->printStorePath(manifestFile)});
-    args.attrs->push_back(Attr(state.symbols.create("derivations"), &manifest));
-    args.attrs->sort();
-    mkApp(topLevel, envBuilder, args);
+    auto attrs = state.buildBindings(3);
+    attrs.alloc("manifest").mkString(
+        state.store->printStorePath(manifestFile),
+        {state.store->printStorePath(manifestFile)});
+    attrs.insert(state.symbols.create("derivations"), &manifest);
+    Value args;
+    args.mkAttrs(attrs);
+
+    Value topLevel;
+    topLevel.mkApp(&envBuilder, &args);
 
     /* Evaluate it. */
     debug("evaluating user environment builder");
diff --git a/src/nix/bundle.cc b/src/nix/bundle.cc
index aca024bca..adb5b3e73 100644
--- a/src/nix/bundle.cc
+++ b/src/nix/bundle.cc
@@ -78,20 +78,20 @@ struct CmdBundle : InstallableCommand
             Strings{bundlerName == "" ? "defaultBundler" : bundlerName},
             Strings({"bundlers."}), lockFlags);
 
-        Value * arg = evalState->allocValue();
-        evalState->mkAttrs(*arg, 2);
+        auto attrs = evalState->buildBindings(2);
 
         PathSet context;
         for (auto & i : app.context)
             context.insert("=" + store->printStorePath(i.path));
-        mkString(*evalState->allocAttr(*arg, evalState->symbols.create("program")), app.program, context);
+        attrs.alloc("program").mkString(app.program, context);
 
-        mkString(*evalState->allocAttr(*arg, evalState->symbols.create("system")), settings.thisSystem.get());
-
-        arg->attrs->sort();
+        attrs.alloc("system").mkString(settings.thisSystem.get());
 
         auto vRes = evalState->allocValue();
-        evalState->callFunction(*bundler.toValue(*evalState).first, *arg, *vRes, noPos);
+        evalState->callFunction(
+            *bundler.toValue(*evalState).first,
+            evalState->allocValue()->mkAttrs(attrs),
+            *vRes, noPos);
 
         if (!evalState->isDerivation(*vRes))
             throw Error("the bundler '%s' does not produce a derivation", bundler.what());
diff --git a/src/nix/main.cc b/src/nix/main.cc
index 759118fd5..fe7469be4 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -187,14 +187,11 @@ static void showHelp(std::vector<std::string> subcommand, MultiCommand & topleve
             , "/"),
         *vUtils);
 
-    auto vArgs = state.allocValue();
-    state.mkAttrs(*vArgs, 16);
-    auto vJson = state.allocAttr(*vArgs, state.symbols.create("command"));
-    mkString(*vJson, toplevel.toJSON().dump());
-    vArgs->attrs->sort();
+    auto attrs = state.buildBindings(16);
+    attrs.alloc("command").mkString(toplevel.toJSON().dump());
 
     auto vRes = state.allocValue();
-    state.callFunction(*vGenerateManpage, *vArgs, *vRes, noPos);
+    state.callFunction(*vGenerateManpage, state.allocValue()->mkAttrs(attrs), *vRes, noPos);
 
     auto attr = vRes->attrs->get(state.symbols.create(mdName + ".md"));
     if (!attr)

From cc08364315437bfd870363220373c48f64862e83 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 4 Jan 2022 18:24:42 +0100
Subject: [PATCH 369/567] Remove non-method mkString()

---
 src/libexpr/common-eval-args.cc  |  2 +-
 src/libexpr/eval.cc              | 13 -------
 src/libexpr/eval.hh              |  2 -
 src/libexpr/flake/flake.cc       |  4 +-
 src/libexpr/json-to-value.cc     |  5 ++-
 src/libexpr/primops.cc           | 66 +++++++++++++++-----------------
 src/libexpr/primops/context.cc   |  7 ++--
 src/libexpr/primops/fetchTree.cc |  2 +-
 src/libexpr/primops/fromTOML.cc  |  2 +-
 src/libexpr/value.hh             |  3 --
 src/nix-env/nix-env.cc           |  4 +-
 11 files changed, 44 insertions(+), 66 deletions(-)

diff --git a/src/libexpr/common-eval-args.cc b/src/libexpr/common-eval-args.cc
index ecae2ca1f..fffca4ac5 100644
--- a/src/libexpr/common-eval-args.cc
+++ b/src/libexpr/common-eval-args.cc
@@ -79,7 +79,7 @@ Bindings * MixEvalArgs::getAutoArgs(EvalState & state)
         if (i.second[0] == 'E')
             state.mkThunk_(*v, state.parseExprFromString(string(i.second, 1), absPath(".")));
         else
-            mkString(*v, string(i.second, 1));
+            v->mkString(((std::string_view) i.second).substr(1));
         res.insert(state.symbols.create(i.first), v);
     }
     return res.finish();
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 0710ce270..2ac872745 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -766,25 +766,12 @@ LocalNoInline(void addErrorTrace(Error & e, const Pos & pos, const char * s, con
 }
 
 
-void mkString(Value & v, const char * s)
-{
-    v.mkString(dupString(s));
-}
-
-
 void Value::mkString(std::string_view s)
 {
     mkString(dupStringWithLen(s.data(), s.size()));
 }
 
 
-Value & mkString(Value & v, std::string_view s, const PathSet & context)
-{
-    v.mkString(s, context);
-    return v;
-}
-
-
 void Value::mkString(std::string_view s, const PathSet & context)
 {
     mkString(s);
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 44ccc6593..c7f74d7b7 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -44,8 +44,6 @@ struct Env
 };
 
 
-Value & mkString(Value & v, std::string_view s, const PathSet & context = PathSet());
-
 void copyContext(const Value & v, PathSet & context);
 
 
diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index c549c5971..15e8d4b06 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -682,7 +682,7 @@ void callFlake(EvalState & state,
     auto vTmp1 = state.allocValue();
     auto vTmp2 = state.allocValue();
 
-    mkString(*vLocks, lockedFlake.lockFile.to_string());
+    vLocks->mkString(lockedFlake.lockFile.to_string());
 
     emitTreeAttrs(
         state,
@@ -692,7 +692,7 @@ void callFlake(EvalState & state,
         false,
         lockedFlake.flake.forceDirty);
 
-    mkString(*vRootSubdir, lockedFlake.flake.lockedRef.subdir);
+    vRootSubdir->mkString(lockedFlake.flake.lockedRef.subdir);
 
     if (!state.vCallFlake) {
         state.vCallFlake = allocRootValue(state.allocValue());
diff --git a/src/libexpr/json-to-value.cc b/src/libexpr/json-to-value.cc
index 9ca5ac86d..3825ca9a9 100644
--- a/src/libexpr/json-to-value.cc
+++ b/src/libexpr/json-to-value.cc
@@ -113,8 +113,11 @@ public:
 
     bool string(string_t & val)
     {
-        return handle_value<void(Value&, const char*)>(mkString, val.c_str());
+        rs->value(state).mkString(val);
+        rs->add();
+        return true;
     }
+
 #if NLOHMANN_JSON_VERSION_MAJOR >= 3 && NLOHMANN_JSON_VERSION_MINOR >= 8
     bool binary(binary_t&)
     {
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index daf5fc927..cb18fe494 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1285,7 +1285,7 @@ static RegisterPrimOp primop_derivationStrict(RegisterPrimOp::Info {
    ‘out’. */
 static void prim_placeholder(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    mkString(v, hashPlaceholder(state.forceStringNoCtx(*args[0], pos)));
+    v.mkString(hashPlaceholder(state.forceStringNoCtx(*args[0], pos)));
 }
 
 static RegisterPrimOp primop_placeholder({
@@ -1310,7 +1310,7 @@ static void prim_toPath(EvalState & state, const Pos & pos, Value * * args, Valu
 {
     PathSet context;
     Path path = state.coerceToPath(pos, *args[0], context);
-    mkString(v, canonPath(path), context);
+    v.mkString(canonPath(path), context);
 }
 
 static RegisterPrimOp primop_toPath({
@@ -1354,7 +1354,7 @@ static void prim_storePath(EvalState & state, const Pos & pos, Value * * args, V
     if (!settings.readOnlyMode)
         state.store->ensurePath(path2);
     context.insert(state.store->printStorePath(path2));
-    mkString(v, path, context);
+    v.mkString(path, context);
 }
 
 static RegisterPrimOp primop_storePath({
@@ -1420,7 +1420,7 @@ static RegisterPrimOp primop_pathExists({
 static void prim_baseNameOf(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     PathSet context;
-    mkString(v, baseNameOf(state.coerceToString(pos, *args[0], context, false, false)), context);
+    v.mkString(baseNameOf(state.coerceToString(pos, *args[0], context, false, false)), context);
 }
 
 static RegisterPrimOp primop_baseNameOf({
@@ -1441,7 +1441,7 @@ static void prim_dirOf(EvalState & state, const Pos & pos, Value * * args, Value
 {
     PathSet context;
     Path dir = dirOf(state.coerceToString(pos, *args[0], context, false, false));
-    if (args[0]->type() == nPath) mkPath(v, dir.c_str()); else mkString(v, dir, context);
+    if (args[0]->type() == nPath) mkPath(v, dir.c_str()); else v.mkString(dir, context);
 }
 
 static RegisterPrimOp primop_dirOf({
@@ -1470,7 +1470,7 @@ static void prim_readFile(EvalState & state, const Pos & pos, Value * * args, Va
     string s = readFile(path);
     if (s.find((char) 0) != string::npos)
         throw Error("the contents of the file '%1%' cannot be represented as a Nix string", path);
-    mkString(v, s.c_str());
+    v.mkString(s);
 }
 
 static RegisterPrimOp primop_readFile({
@@ -1549,7 +1549,7 @@ static void prim_hashFile(EvalState & state, const Pos & pos, Value * * args, Va
         throw EvalError("cannot read '%s' since path '%s' is not valid, at %s", path, e.path, pos);
     }
 
-    mkString(v, hashFile(*ht, path).to_string(Base16, false));
+    v.mkString(hashFile(*ht, path).to_string(Base16, false));
 }
 
 static RegisterPrimOp primop_hashFile({
@@ -1626,7 +1626,7 @@ static void prim_toXML(EvalState & state, const Pos & pos, Value * * args, Value
     std::ostringstream out;
     PathSet context;
     printValueAsXML(state, true, false, *args[0], out, context, pos);
-    mkString(v, out.str(), context);
+    v.mkString(out.str(), context);
 }
 
 static RegisterPrimOp primop_toXML({
@@ -1734,7 +1734,7 @@ static void prim_toJSON(EvalState & state, const Pos & pos, Value * * args, Valu
     std::ostringstream out;
     PathSet context;
     printValueAsJSON(state, true, *args[0], pos, out, context);
-    mkString(v, out.str(), context);
+    v.mkString(out.str(), context);
 }
 
 static RegisterPrimOp primop_toJSON({
@@ -1808,7 +1808,7 @@ static void prim_toFile(EvalState & state, const Pos & pos, Value * * args, Valu
        result, since `storePath' itself has references to the paths
        used in args[1]. */
 
-    mkString(v, storePath, {storePath});
+    v.mkString(storePath, {storePath});
 }
 
 static RegisterPrimOp primop_toFile({
@@ -1925,10 +1925,10 @@ static void addPath(
             /* Call the filter function.  The first argument is the path,
                the second is a string indicating the type of the file. */
             Value arg1;
-            mkString(arg1, path);
+            arg1.mkString(path);
 
             Value arg2;
-            mkString(arg2,
+            arg2.mkString(
                 S_ISREG(st.st_mode) ? "regular" :
                 S_ISDIR(st.st_mode) ? "directory" :
                 S_ISLNK(st.st_mode) ? "symlink" :
@@ -1955,7 +1955,7 @@ static void addPath(
         } else
             dstPath = state.store->printStorePath(*expectedStorePath);
 
-        mkString(v, dstPath, {dstPath});
+        v.mkString(dstPath, {dstPath});
 
         state.allowPath(dstPath);
 
@@ -3303,7 +3303,7 @@ static void prim_toString(EvalState & state, const Pos & pos, Value * * args, Va
 {
     PathSet context;
     string s = state.coerceToString(pos, *args[0], context, true, false);
-    mkString(v, s, context);
+    v.mkString(s, context);
 }
 
 static RegisterPrimOp primop_toString({
@@ -3347,7 +3347,7 @@ static void prim_substring(EvalState & state, const Pos & pos, Value * * args, V
             .errPos = pos
         });
 
-    mkString(v, (unsigned int) start >= s.size() ? "" : string(s, start, len), context);
+    v.mkString((unsigned int) start >= s.size() ? "" : string(s, start, len), context);
 }
 
 static RegisterPrimOp primop_substring({
@@ -3401,7 +3401,7 @@ static void prim_hashString(EvalState & state, const Pos & pos, Value * * args,
     PathSet context; // discarded
     string s = state.forceString(*args[1], context, pos);
 
-    mkString(v, hashString(*ht, s).to_string(Base16, false));
+    v.mkString(hashString(*ht, s).to_string(Base16, false));
 }
 
 static RegisterPrimOp primop_hashString({
@@ -3451,7 +3451,7 @@ void prim_match(EvalState & state, const Pos & pos, Value * * args, Value & v)
             if (!match[i+1].matched)
                 mkNull(*(v.listElems()[i] = state.allocValue()));
             else
-                mkString(*(v.listElems()[i] = state.allocValue()), match[i + 1].str().c_str());
+                (v.listElems()[i] = state.allocValue())->mkString(match[i + 1].str());
         }
 
     } catch (std::regex_error &e) {
@@ -3526,7 +3526,6 @@ static void prim_split(EvalState & state, const Pos & pos, Value * * args, Value
         const size_t len = std::distance(begin, end);
         state.mkList(v, 2 * len + 1);
         size_t idx = 0;
-        Value * elem;
 
         if (len == 0) {
             v.listElems()[idx++] = args[1];
@@ -3538,12 +3537,11 @@ static void prim_split(EvalState & state, const Pos & pos, Value * * args, Value
             std::smatch match = *i;
 
             // Add a string for non-matched characters.
-            elem = v.listElems()[idx++] = state.allocValue();
-            mkString(*elem, match.prefix().str().c_str());
+            (v.listElems()[idx++] = state.allocValue())->mkString(match.prefix().str());
 
             // Add a list for matched substrings.
             const size_t slen = match.size() - 1;
-            elem = v.listElems()[idx++] = state.allocValue();
+            auto elem = v.listElems()[idx++] = state.allocValue();
 
             // Start at 1, beacause the first match is the whole string.
             state.mkList(*elem, slen);
@@ -3551,15 +3549,14 @@ static void prim_split(EvalState & state, const Pos & pos, Value * * args, Value
                 if (!match[si + 1].matched)
                     mkNull(*(elem->listElems()[si] = state.allocValue()));
                 else
-                    mkString(*(elem->listElems()[si] = state.allocValue()), match[si + 1].str().c_str());
+                    (elem->listElems()[si] = state.allocValue())->mkString(match[si + 1].str());
             }
 
             // Add a string for non-matched suffix characters.
-            if (idx == 2 * len) {
-                elem = v.listElems()[idx++] = state.allocValue();
-                mkString(*elem, match.suffix().str().c_str());
-            }
+            if (idx == 2 * len)
+                (v.listElems()[idx++] = state.allocValue())->mkString(match.suffix().str());
         }
+
         assert(idx == 2 * len + 1);
 
     } catch (std::regex_error &e) {
@@ -3631,7 +3628,7 @@ static void prim_concatStringsSep(EvalState & state, const Pos & pos, Value * *
         res += state.coerceToString(pos, *elem, context);
     }
 
-    mkString(v, res, context);
+    v.mkString(res, context);
 }
 
 static RegisterPrimOp primop_concatStringsSep({
@@ -3700,7 +3697,7 @@ static void prim_replaceStrings(EvalState & state, const Pos & pos, Value * * ar
         }
     }
 
-    mkString(v, res, context);
+    v.mkString(res, context);
 }
 
 static RegisterPrimOp primop_replaceStrings({
@@ -3781,11 +3778,8 @@ static void prim_splitVersion(EvalState & state, const Pos & pos, Value * * args
         components.emplace_back(std::move(component));
     }
     state.mkList(v, components.size());
-    unsigned int n = 0;
-    for (auto & component : components) {
-        auto listElem = v.listElems()[n++] = state.allocValue();
-        mkString(*listElem, std::move(component));
-    }
+    for (const auto & [n, component] : enumerate(components))
+        (v.listElems()[n] = state.allocValue())->mkString(std::move(component));
 }
 
 static RegisterPrimOp primop_splitVersion({
@@ -3851,14 +3845,14 @@ void EvalState::createBaseEnv()
         mkInt(v, time(0));
         addConstant("__currentTime", v);
 
-        mkString(v, settings.thisSystem.get());
+        v.mkString(settings.thisSystem.get());
         addConstant("__currentSystem", v);
     }
 
-    mkString(v, nixVersion);
+    v.mkString(nixVersion);
     addConstant("__nixVersion", v);
 
-    mkString(v, store->storeDir);
+    v.mkString(store->storeDir);
     addConstant("__storeDir", v);
 
     /* Language version.  This should be increased every time a new
diff --git a/src/libexpr/primops/context.cc b/src/libexpr/primops/context.cc
index ab08303d8..321c3c301 100644
--- a/src/libexpr/primops/context.cc
+++ b/src/libexpr/primops/context.cc
@@ -7,8 +7,7 @@ namespace nix {
 static void prim_unsafeDiscardStringContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     PathSet context;
-    string s = state.coerceToString(pos, *args[0], context);
-    mkString(v, s, PathSet());
+    v.mkString(state.coerceToString(pos, *args[0], context));
 }
 
 static RegisterPrimOp primop_unsafeDiscardStringContext("__unsafeDiscardStringContext", 1, prim_unsafeDiscardStringContext);
@@ -39,7 +38,7 @@ static void prim_unsafeDiscardOutputDependency(EvalState & state, const Pos & po
     for (auto & p : context)
         context2.insert(p.at(0) == '=' ? string(p, 1) : p);
 
-    mkString(v, s, context2);
+    v.mkString(s, context2);
 }
 
 static RegisterPrimOp primop_unsafeDiscardOutputDependency("__unsafeDiscardOutputDependency", 1, prim_unsafeDiscardOutputDependency);
@@ -186,7 +185,7 @@ static void prim_appendContext(EvalState & state, const Pos & pos, Value * * arg
         }
     }
 
-    mkString(v, orig, context);
+    v.mkString(orig, context);
 }
 
 static RegisterPrimOp primop_appendContext("__appendContext", 2, prim_appendContext);
diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index a97bfcae7..6647bd35c 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -247,7 +247,7 @@ static void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
     state.allowPath(storePath);
 
     auto path = state.store->printStorePath(storePath);
-    mkString(v, path, PathSet({path}));
+    v.mkString(path, PathSet({path}));
 }
 
 static void prim_fetchurl(EvalState & state, const Pos & pos, Value * * args, Value & v)
diff --git a/src/libexpr/primops/fromTOML.cc b/src/libexpr/primops/fromTOML.cc
index a328b6736..bae0189ab 100644
--- a/src/libexpr/primops/fromTOML.cc
+++ b/src/libexpr/primops/fromTOML.cc
@@ -52,7 +52,7 @@ static void prim_fromTOML(EvalState & state, const Pos & pos, Value * * args, Va
                 mkFloat(v, toml::get<NixFloat>(t));
                 break;;
             case toml::value_t::string:
-                mkString(v, toml::get<std::string>(t));
+                v.mkString(toml::get<std::string>(t));
                 break;;
             case toml::value_t::local_datetime:
             case toml::value_t::offset_datetime:
diff --git a/src/libexpr/value.hh b/src/libexpr/value.hh
index a8fea02dc..94a17136f 100644
--- a/src/libexpr/value.hh
+++ b/src/libexpr/value.hh
@@ -424,9 +424,6 @@ static inline void mkString(Value & v, const Symbol & s)
 }
 
 
-void mkString(Value & v, const char * s);
-
-
 void mkPath(Value & v, const char * s);
 
 
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index 171f1c440..7393d91f9 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -678,8 +678,8 @@ static void opUpgrade(Globals & globals, Strings opFlags, Strings opArgs)
 static void setMetaFlag(EvalState & state, DrvInfo & drv,
     const string & name, const string & value)
 {
-    Value * v = state.allocValue();
-    mkString(*v, value.c_str());
+    auto v = state.allocValue();
+    v->mkString(value);
     drv.setMeta(name, v);
 }
 

From 263a8d293c67488065296737cdadee3d0e122bf5 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 4 Jan 2022 18:40:39 +0100
Subject: [PATCH 370/567] Remove non-method mk<X> functions

---
 src/libexpr/eval.cc             |  26 +++----
 src/libexpr/json-to-value.cc    |  27 ++++----
 src/libexpr/nixexpr.hh          |   4 +-
 src/libexpr/primops.cc          | 118 ++++++++++++++++----------------
 src/libexpr/primops/context.cc  |   6 +-
 src/libexpr/primops/fromTOML.cc |   8 +--
 src/libexpr/value.hh            |  25 -------
 src/nix-env/nix-env.cc          |   2 +-
 tests/plugins/plugintest.cc     |   4 +-
 9 files changed, 99 insertions(+), 121 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 2ac872745..591aa6583 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -613,7 +613,7 @@ Value * EvalState::addPrimOp(const string & name,
         auto vPrimOp = allocValue();
         vPrimOp->mkPrimOp(new PrimOp { .fun = primOp, .arity = 1, .name = sym });
         Value v;
-        mkApp(v, *vPrimOp, *vPrimOp);
+        v.mkApp(vPrimOp, vPrimOp);
         return addConstant(name, v);
     }
 
@@ -635,7 +635,7 @@ Value * EvalState::addPrimOp(PrimOp && primOp)
         auto vPrimOp = allocValue();
         vPrimOp->mkPrimOp(new PrimOp(std::move(primOp)));
         Value v;
-        mkApp(v, *vPrimOp, *vPrimOp);
+        v.mkApp(vPrimOp, vPrimOp);
         return addConstant(primOp.name, v);
     }
 
@@ -887,7 +887,7 @@ void EvalState::mkPos(Value & v, ptr<Pos> pos)
         attrs.alloc(sColumn).mkInt(pos->column);
         v.mkAttrs(attrs);
     } else
-        mkNull(v);
+        v.mkNull();
 }
 
 
@@ -1258,14 +1258,14 @@ void ExprOpHasAttr::eval(EvalState & state, Env & env, Value & v)
         if (vAttrs->type() != nAttrs ||
             (j = vAttrs->attrs->find(name)) == vAttrs->attrs->end())
         {
-            mkBool(v, false);
+            v.mkBool(false);
             return;
         } else {
             vAttrs = j->value;
         }
     }
 
-    mkBool(v, true);
+    v.mkBool(true);
 }
 
 
@@ -1544,7 +1544,7 @@ void ExprAssert::eval(EvalState & state, Env & env, Value & v)
 
 void ExprOpNot::eval(EvalState & state, Env & env, Value & v)
 {
-    mkBool(v, !state.evalBool(env, e));
+    v.mkBool(!state.evalBool(env, e));
 }
 
 
@@ -1552,7 +1552,7 @@ void ExprOpEq::eval(EvalState & state, Env & env, Value & v)
 {
     Value v1; e1->eval(state, env, v1);
     Value v2; e2->eval(state, env, v2);
-    mkBool(v, state.eqValues(v1, v2));
+    v.mkBool(state.eqValues(v1, v2));
 }
 
 
@@ -1560,25 +1560,25 @@ void ExprOpNEq::eval(EvalState & state, Env & env, Value & v)
 {
     Value v1; e1->eval(state, env, v1);
     Value v2; e2->eval(state, env, v2);
-    mkBool(v, !state.eqValues(v1, v2));
+    v.mkBool(!state.eqValues(v1, v2));
 }
 
 
 void ExprOpAnd::eval(EvalState & state, Env & env, Value & v)
 {
-    mkBool(v, state.evalBool(env, e1, pos) && state.evalBool(env, e2, pos));
+    v.mkBool(state.evalBool(env, e1, pos) && state.evalBool(env, e2, pos));
 }
 
 
 void ExprOpOr::eval(EvalState & state, Env & env, Value & v)
 {
-    mkBool(v, state.evalBool(env, e1, pos) || state.evalBool(env, e2, pos));
+    v.mkBool(state.evalBool(env, e1, pos) || state.evalBool(env, e2, pos));
 }
 
 
 void ExprOpImpl::eval(EvalState & state, Env & env, Value & v)
 {
-    mkBool(v, !state.evalBool(env, e1, pos) || state.evalBool(env, e2, pos));
+    v.mkBool(!state.evalBool(env, e1, pos) || state.evalBool(env, e2, pos));
 }
 
 
@@ -1705,9 +1705,9 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
     }
 
     if (firstType == nInt)
-        mkInt(v, n);
+        v.mkInt(n);
     else if (firstType == nFloat)
-        mkFloat(v, nf);
+        v.mkFloat(nf);
     else if (firstType == nPath) {
         if (!context.empty())
             throwEvalError(pos, "a string that refers to a store path cannot be appended to a path");
diff --git a/src/libexpr/json-to-value.cc b/src/libexpr/json-to-value.cc
index 3825ca9a9..4dc41729a 100644
--- a/src/libexpr/json-to-value.cc
+++ b/src/libexpr/json-to-value.cc
@@ -76,39 +76,42 @@ class JSONSax : nlohmann::json_sax<json> {
     EvalState & state;
     std::unique_ptr<JSONState> rs;
 
-    template<typename T, typename... Args> inline bool handle_value(T f, Args... args)
-    {
-        f(rs->value(state), args...);
-        rs->add();
-        return true;
-    }
-
 public:
     JSONSax(EvalState & state, Value & v) : state(state), rs(new JSONState(&v)) {};
 
     bool null()
     {
-        return handle_value(mkNull);
+        rs->value(state).mkNull();
+        rs->add();
+        return true;
     }
 
     bool boolean(bool val)
     {
-        return handle_value(mkBool, val);
+        rs->value(state).mkBool(val);
+        rs->add();
+        return true;
     }
 
     bool number_integer(number_integer_t val)
     {
-        return handle_value(mkInt, val);
+        rs->value(state).mkInt(val);
+        rs->add();
+        return true;
     }
 
     bool number_unsigned(number_unsigned_t val)
     {
-        return handle_value(mkInt, val);
+        rs->value(state).mkInt(val);
+        rs->add();
+        return true;
     }
 
     bool number_float(number_float_t val, const string_t & s)
     {
-        return handle_value(mkFloat, val);
+        rs->value(state).mkFloat(val);
+        rs->add();
+        return true;
     }
 
     bool string(string_t & val)
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index b328b3941..aa5a3f332 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -94,7 +94,7 @@ struct ExprInt : Expr
 {
     NixInt n;
     Value v;
-    ExprInt(NixInt n) : n(n) { mkInt(v, n); };
+    ExprInt(NixInt n) : n(n) { v.mkInt(n); };
     COMMON_METHODS
     Value * maybeThunk(EvalState & state, Env & env);
 };
@@ -103,7 +103,7 @@ struct ExprFloat : Expr
 {
     NixFloat nf;
     Value v;
-    ExprFloat(NixFloat nf) : nf(nf) { mkFloat(v, nf); };
+    ExprFloat(NixFloat nf) : nf(nf) { v.mkFloat(nf); };
     COMMON_METHODS
     Value * maybeThunk(EvalState & state, Env & env);
 };
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index cb18fe494..57be5ac23 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -196,7 +196,7 @@ static void import(EvalState & state, const Pos & pos, Value & vPath, Value * vS
         }
 
         state.forceFunction(**state.vImportedDrvToDerivation, pos);
-        mkApp(v, **state.vImportedDrvToDerivation, *w);
+        v.mkApp(*state.vImportedDrvToDerivation, w);
         state.forceAttrs(v, pos);
     }
 
@@ -430,7 +430,7 @@ static RegisterPrimOp primop_typeOf({
 static void prim_isNull(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     state.forceValue(*args[0], pos);
-    mkBool(v, args[0]->type() == nNull);
+    v.mkBool(args[0]->type() == nNull);
 }
 
 static RegisterPrimOp primop_isNull({
@@ -450,7 +450,7 @@ static RegisterPrimOp primop_isNull({
 static void prim_isFunction(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     state.forceValue(*args[0], pos);
-    mkBool(v, args[0]->type() == nFunction);
+    v.mkBool(args[0]->type() == nFunction);
 }
 
 static RegisterPrimOp primop_isFunction({
@@ -466,7 +466,7 @@ static RegisterPrimOp primop_isFunction({
 static void prim_isInt(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     state.forceValue(*args[0], pos);
-    mkBool(v, args[0]->type() == nInt);
+    v.mkBool(args[0]->type() == nInt);
 }
 
 static RegisterPrimOp primop_isInt({
@@ -482,7 +482,7 @@ static RegisterPrimOp primop_isInt({
 static void prim_isFloat(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     state.forceValue(*args[0], pos);
-    mkBool(v, args[0]->type() == nFloat);
+    v.mkBool(args[0]->type() == nFloat);
 }
 
 static RegisterPrimOp primop_isFloat({
@@ -498,7 +498,7 @@ static RegisterPrimOp primop_isFloat({
 static void prim_isString(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     state.forceValue(*args[0], pos);
-    mkBool(v, args[0]->type() == nString);
+    v.mkBool(args[0]->type() == nString);
 }
 
 static RegisterPrimOp primop_isString({
@@ -514,7 +514,7 @@ static RegisterPrimOp primop_isString({
 static void prim_isBool(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     state.forceValue(*args[0], pos);
-    mkBool(v, args[0]->type() == nBool);
+    v.mkBool(args[0]->type() == nBool);
 }
 
 static RegisterPrimOp primop_isBool({
@@ -530,7 +530,7 @@ static RegisterPrimOp primop_isBool({
 static void prim_isPath(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     state.forceValue(*args[0], pos);
-    mkBool(v, args[0]->type() == nPath);
+    v.mkBool(args[0]->type() == nPath);
 }
 
 static RegisterPrimOp primop_isPath({
@@ -685,7 +685,7 @@ static void prim_genericClosure(EvalState & state, const Pos & pos, Value * * ar
 
         /* Call the `operator' function with `e' as argument. */
         Value call;
-        mkApp(call, *op->value, *e);
+        call.mkApp(op->value, e);
         state.forceList(call, pos);
 
         /* Add the values returned by the operator to the work set. */
@@ -761,7 +761,7 @@ static RegisterPrimOp primop_addErrorContext(RegisterPrimOp::Info {
 static void prim_ceil(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     auto value = state.forceFloat(*args[0], args[0]->determinePos(pos));
-    mkInt(v, ceil(value));
+    v.mkInt(ceil(value));
 }
 
 static RegisterPrimOp primop_ceil({
@@ -780,7 +780,7 @@ static RegisterPrimOp primop_ceil({
 static void prim_floor(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     auto value = state.forceFloat(*args[0], args[0]->determinePos(pos));
-    mkInt(v, floor(value));
+    v.mkInt(floor(value));
 }
 
 static RegisterPrimOp primop_floor({
@@ -804,10 +804,10 @@ static void prim_tryEval(EvalState & state, const Pos & pos, Value * * args, Val
     try {
         state.forceValue(*args[0], pos);
         attrs.insert(state.sValue, args[0]);
-        mkBool(attrs.alloc("success"), true);
+        attrs.alloc("success").mkBool(true);
     } catch (AssertionError & e) {
-        mkBool(attrs.alloc(state.sValue), false);
-        mkBool(attrs.alloc("success"), false);
+        attrs.alloc(state.sValue).mkBool(false);
+        attrs.alloc("success").mkBool(false);
     }
     v.mkAttrs(attrs);
 }
@@ -1395,13 +1395,13 @@ static void prim_pathExists(EvalState & state, const Pos & pos, Value * * args,
     }
 
     try {
-        mkBool(v, pathExists(state.checkSourcePath(path)));
+        v.mkBool(pathExists(state.checkSourcePath(path)));
     } catch (SysError & e) {
         /* Don't give away info from errors while canonicalising
            ‘path’ in restricted mode. */
-        mkBool(v, false);
+        v.mkBool(false);
     } catch (RestrictedPathError & e) {
-        mkBool(v, false);
+        v.mkBool(false);
     }
 }
 
@@ -2213,7 +2213,7 @@ static void prim_unsafeGetAttrPos(EvalState & state, const Pos & pos, Value * *
     state.forceAttrs(*args[1], pos);
     Bindings::iterator i = args[1]->attrs->find(state.symbols.create(attr));
     if (i == args[1]->attrs->end())
-        mkNull(v);
+        v.mkNull();
     else
         state.mkPos(v, i->pos);
 }
@@ -2229,7 +2229,7 @@ static void prim_hasAttr(EvalState & state, const Pos & pos, Value * * args, Val
 {
     string attr = state.forceStringNoCtx(*args[0], pos);
     state.forceAttrs(*args[1], pos);
-    mkBool(v, args[1]->attrs->find(state.symbols.create(attr)) != args[1]->attrs->end());
+    v.mkBool(args[1]->attrs->find(state.symbols.create(attr)) != args[1]->attrs->end());
 }
 
 static RegisterPrimOp primop_hasAttr({
@@ -2247,7 +2247,7 @@ static RegisterPrimOp primop_hasAttr({
 static void prim_isAttrs(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     state.forceValue(*args[0], pos);
-    mkBool(v, args[0]->type() == nAttrs);
+    v.mkBool(args[0]->type() == nAttrs);
 }
 
 static RegisterPrimOp primop_isAttrs({
@@ -2446,7 +2446,7 @@ static void prim_functionArgs(EvalState & state, const Pos & pos, Value * * args
     auto attrs = state.buildBindings(args[0]->lambda.fun->formals->formals.size());
     for (auto & i : args[0]->lambda.fun->formals->formals)
         // !!! should optimise booleans (allocate only once)
-        mkBool(attrs.alloc(i.name, ptr(&i.pos)), i.def);
+        attrs.alloc(i.name, ptr(&i.pos)).mkBool(i.def);
     v.mkAttrs(attrs);
 }
 
@@ -2478,8 +2478,8 @@ static void prim_mapAttrs(EvalState & state, const Pos & pos, Value * * args, Va
         Value * vName = state.allocValue();
         Value * vFun2 = state.allocValue();
         mkString(*vName, i.name);
-        mkApp(*vFun2, *args[0], *vName);
-        mkApp(*state.allocAttr(v, i.name), *vFun2, *i.value);
+        vFun2->mkApp(args[0], vName);
+        state.allocAttr(v, i.name)->mkApp(vFun2, i.value);
     }
 }
 
@@ -2542,10 +2542,10 @@ static void prim_zipAttrsWith(EvalState & state, const Pos & pos, Value * * args
     for (auto & attr : *v.attrs) {
         Value * name = state.allocValue();
         mkString(*name, attr.name);
-        Value * call1 = state.allocValue();
-        mkApp(*call1, *args[0], *name);
-        Value * call2 = state.allocValue();
-        mkApp(*call2, *call1, *attr.value);
+        auto call1 = state.allocValue();
+        call1->mkApp(args[0], name);
+        auto call2 = state.allocValue();
+        call2->mkApp(call1, attr.value);
         attr.value = call2;
     }
 }
@@ -2592,7 +2592,7 @@ static RegisterPrimOp primop_zipAttrsWith({
 static void prim_isList(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     state.forceValue(*args[0], pos);
-    mkBool(v, args[0]->type() == nList);
+    v.mkBool(args[0]->type() == nList);
 }
 
 static RegisterPrimOp primop_isList({
@@ -2690,8 +2690,8 @@ static void prim_map(EvalState & state, const Pos & pos, Value * * args, Value &
     state.mkList(v, args[1]->listSize());
 
     for (unsigned int n = 0; n < v.listSize(); ++n)
-        mkApp(*(v.listElems()[n] = state.allocValue()),
-            *args[0], *args[1]->listElems()[n]);
+        (v.listElems()[n] = state.allocValue())->mkApp(
+            args[0], args[1]->listElems()[n]);
 }
 
 static RegisterPrimOp primop_map({
@@ -2760,7 +2760,7 @@ static void prim_elem(EvalState & state, const Pos & pos, Value * * args, Value
             res = true;
             break;
         }
-    mkBool(v, res);
+    v.mkBool(res);
 }
 
 static RegisterPrimOp primop_elem({
@@ -2793,7 +2793,7 @@ static RegisterPrimOp primop_concatLists({
 static void prim_length(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     state.forceList(*args[0], pos);
-    mkInt(v, args[0]->listSize());
+    v.mkInt(args[0]->listSize());
 }
 
 static RegisterPrimOp primop_length({
@@ -2850,12 +2850,12 @@ static void anyOrAll(bool any, EvalState & state, const Pos & pos, Value * * arg
         state.callFunction(*args[0], *elem, vTmp, pos);
         bool res = state.forceBool(vTmp, pos);
         if (res == any) {
-            mkBool(v, any);
+            v.mkBool(any);
             return;
         }
     }
 
-    mkBool(v, !any);
+    v.mkBool(!any);
 }
 
 
@@ -2902,9 +2902,9 @@ static void prim_genList(EvalState & state, const Pos & pos, Value * * args, Val
     state.mkList(v, len);
 
     for (unsigned int n = 0; n < (unsigned int) len; ++n) {
-        Value * arg = state.allocValue();
-        mkInt(*arg, n);
-        mkApp(*(v.listElems()[n] = state.allocValue()), *args[0], *arg);
+        auto arg = state.allocValue();
+        arg->mkInt(n);
+        (v.listElems()[n] = state.allocValue())->mkApp(args[0], arg);
     }
 }
 
@@ -3140,9 +3140,9 @@ static void prim_add(EvalState & state, const Pos & pos, Value * * args, Value &
     state.forceValue(*args[0], pos);
     state.forceValue(*args[1], pos);
     if (args[0]->type() == nFloat || args[1]->type() == nFloat)
-        mkFloat(v, state.forceFloat(*args[0], pos) + state.forceFloat(*args[1], pos));
+        v.mkFloat(state.forceFloat(*args[0], pos) + state.forceFloat(*args[1], pos));
     else
-        mkInt(v, state.forceInt(*args[0], pos) + state.forceInt(*args[1], pos));
+        v.mkInt(state.forceInt(*args[0], pos) + state.forceInt(*args[1], pos));
 }
 
 static RegisterPrimOp primop_add({
@@ -3159,9 +3159,9 @@ static void prim_sub(EvalState & state, const Pos & pos, Value * * args, Value &
     state.forceValue(*args[0], pos);
     state.forceValue(*args[1], pos);
     if (args[0]->type() == nFloat || args[1]->type() == nFloat)
-        mkFloat(v, state.forceFloat(*args[0], pos) - state.forceFloat(*args[1], pos));
+        v.mkFloat(state.forceFloat(*args[0], pos) - state.forceFloat(*args[1], pos));
     else
-        mkInt(v, state.forceInt(*args[0], pos) - state.forceInt(*args[1], pos));
+        v.mkInt(state.forceInt(*args[0], pos) - state.forceInt(*args[1], pos));
 }
 
 static RegisterPrimOp primop_sub({
@@ -3178,9 +3178,9 @@ static void prim_mul(EvalState & state, const Pos & pos, Value * * args, Value &
     state.forceValue(*args[0], pos);
     state.forceValue(*args[1], pos);
     if (args[0]->type() == nFloat || args[1]->type() == nFloat)
-        mkFloat(v, state.forceFloat(*args[0], pos) * state.forceFloat(*args[1], pos));
+        v.mkFloat(state.forceFloat(*args[0], pos) * state.forceFloat(*args[1], pos));
     else
-        mkInt(v, state.forceInt(*args[0], pos) * state.forceInt(*args[1], pos));
+        v.mkInt(state.forceInt(*args[0], pos) * state.forceInt(*args[1], pos));
 }
 
 static RegisterPrimOp primop_mul({
@@ -3205,7 +3205,7 @@ static void prim_div(EvalState & state, const Pos & pos, Value * * args, Value &
         });
 
     if (args[0]->type() == nFloat || args[1]->type() == nFloat) {
-        mkFloat(v, state.forceFloat(*args[0], pos) / state.forceFloat(*args[1], pos));
+        v.mkFloat(state.forceFloat(*args[0], pos) / state.forceFloat(*args[1], pos));
     } else {
         NixInt i1 = state.forceInt(*args[0], pos);
         NixInt i2 = state.forceInt(*args[1], pos);
@@ -3216,7 +3216,7 @@ static void prim_div(EvalState & state, const Pos & pos, Value * * args, Value &
                 .errPos = pos
             });
 
-        mkInt(v, i1 / i2);
+        v.mkInt(i1 / i2);
     }
 }
 
@@ -3231,7 +3231,7 @@ static RegisterPrimOp primop_div({
 
 static void prim_bitAnd(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    mkInt(v, state.forceInt(*args[0], pos) & state.forceInt(*args[1], pos));
+    v.mkInt(state.forceInt(*args[0], pos) & state.forceInt(*args[1], pos));
 }
 
 static RegisterPrimOp primop_bitAnd({
@@ -3245,7 +3245,7 @@ static RegisterPrimOp primop_bitAnd({
 
 static void prim_bitOr(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    mkInt(v, state.forceInt(*args[0], pos) | state.forceInt(*args[1], pos));
+    v.mkInt(state.forceInt(*args[0], pos) | state.forceInt(*args[1], pos));
 }
 
 static RegisterPrimOp primop_bitOr({
@@ -3259,7 +3259,7 @@ static RegisterPrimOp primop_bitOr({
 
 static void prim_bitXor(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    mkInt(v, state.forceInt(*args[0], pos) ^ state.forceInt(*args[1], pos));
+    v.mkInt(state.forceInt(*args[0], pos) ^ state.forceInt(*args[1], pos));
 }
 
 static RegisterPrimOp primop_bitXor({
@@ -3276,7 +3276,7 @@ static void prim_lessThan(EvalState & state, const Pos & pos, Value * * args, Va
     state.forceValue(*args[0], pos);
     state.forceValue(*args[1], pos);
     CompareValues comp{state};
-    mkBool(v, comp(args[0], args[1]));
+    v.mkBool(comp(args[0], args[1]));
 }
 
 static RegisterPrimOp primop_lessThan({
@@ -3374,7 +3374,7 @@ static void prim_stringLength(EvalState & state, const Pos & pos, Value * * args
 {
     PathSet context;
     string s = state.coerceToString(pos, *args[0], context);
-    mkInt(v, s.size());
+    v.mkInt(s.size());
 }
 
 static RegisterPrimOp primop_stringLength({
@@ -3440,7 +3440,7 @@ void prim_match(EvalState & state, const Pos & pos, Value * * args, Value & v)
 
         std::smatch match;
         if (!std::regex_match(str, match, regex->second)) {
-            mkNull(v);
+            v.mkNull();
             return;
         }
 
@@ -3449,7 +3449,7 @@ void prim_match(EvalState & state, const Pos & pos, Value * * args, Value & v)
         state.mkList(v, len);
         for (size_t i = 0; i < len; ++i) {
             if (!match[i+1].matched)
-                mkNull(*(v.listElems()[i] = state.allocValue()));
+                (v.listElems()[i] = state.allocValue())->mkNull();
             else
                 (v.listElems()[i] = state.allocValue())->mkString(match[i + 1].str());
         }
@@ -3547,7 +3547,7 @@ static void prim_split(EvalState & state, const Pos & pos, Value * * args, Value
             state.mkList(*elem, slen);
             for (size_t si = 0; si < slen; ++si) {
                 if (!match[si + 1].matched)
-                    mkNull(*(elem->listElems()[si] = state.allocValue()));
+                    (elem->listElems()[si] = state.allocValue())->mkNull();
                 else
                     (elem->listElems()[si] = state.allocValue())->mkString(match[si + 1].str());
             }
@@ -3750,7 +3750,7 @@ static void prim_compareVersions(EvalState & state, const Pos & pos, Value * * a
 {
     string version1 = state.forceStringNoCtx(*args[0], pos);
     string version2 = state.forceStringNoCtx(*args[1], pos);
-    mkInt(v, compareVersions(version1, version2));
+    v.mkInt(compareVersions(version1, version2));
 }
 
 static RegisterPrimOp primop_compareVersions({
@@ -3832,17 +3832,17 @@ void EvalState::createBaseEnv()
     mkAttrs(v, 128);
     addConstant("builtins", v);
 
-    mkBool(v, true);
+    v.mkBool(true);
     addConstant("true", v);
 
-    mkBool(v, false);
+    v.mkBool(false);
     addConstant("false", v);
 
-    mkNull(v);
+    v.mkNull();
     addConstant("null", v);
 
     if (!evalSettings.pureEval) {
-        mkInt(v, time(0));
+        v.mkInt(time(0));
         addConstant("__currentTime", v);
 
         v.mkString(settings.thisSystem.get());
@@ -3859,7 +3859,7 @@ void EvalState::createBaseEnv()
        language feature gets added.  It's not necessary to increase it
        when primops get added, because you can just use `builtins ?
        primOp' to check. */
-    mkInt(v, 6);
+    v.mkInt(6);
     addConstant("__langVersion", v);
 
     // Miscellaneous
diff --git a/src/libexpr/primops/context.cc b/src/libexpr/primops/context.cc
index 321c3c301..a239c06da 100644
--- a/src/libexpr/primops/context.cc
+++ b/src/libexpr/primops/context.cc
@@ -17,7 +17,7 @@ static void prim_hasContext(EvalState & state, const Pos & pos, Value * * args,
 {
     PathSet context;
     state.forceString(*args[0], context, pos);
-    mkBool(v, !context.empty());
+    v.mkBool(!context.empty());
 }
 
 static RegisterPrimOp primop_hasContext("__hasContext", 1, prim_hasContext);
@@ -109,9 +109,9 @@ static void prim_getContext(EvalState & state, const Pos & pos, Value * * args,
     for (const auto & info : contextInfos) {
         auto infoAttrs = state.buildBindings(3);
         if (info.second.path)
-            mkBool(infoAttrs.alloc(sPath), true);
+            infoAttrs.alloc(sPath).mkBool(true);
         if (info.second.allOutputs)
-            mkBool(infoAttrs.alloc(sAllOutputs), true);
+            infoAttrs.alloc(sAllOutputs).mkBool(true);
         if (!info.second.outputs.empty()) {
             auto & outputsVal = infoAttrs.alloc(state.sOutputs);
             state.mkList(outputsVal, info.second.outputs.size());
diff --git a/src/libexpr/primops/fromTOML.cc b/src/libexpr/primops/fromTOML.cc
index bae0189ab..80c7e0b82 100644
--- a/src/libexpr/primops/fromTOML.cc
+++ b/src/libexpr/primops/fromTOML.cc
@@ -43,13 +43,13 @@ static void prim_fromTOML(EvalState & state, const Pos & pos, Value * * args, Va
                 }
                 break;;
             case toml::value_t::boolean:
-                mkBool(v, toml::get<bool>(t));
+                v.mkBool(toml::get<bool>(t));
                 break;;
             case toml::value_t::integer:
-                mkInt(v, toml::get<int64_t>(t));
+                v.mkInt(toml::get<int64_t>(t));
                 break;;
             case toml::value_t::floating:
-                mkFloat(v, toml::get<NixFloat>(t));
+                v.mkFloat(toml::get<NixFloat>(t));
                 break;;
             case toml::value_t::string:
                 v.mkString(toml::get<std::string>(t));
@@ -62,7 +62,7 @@ static void prim_fromTOML(EvalState & state, const Pos & pos, Value * * args, Va
                 throw std::runtime_error("Dates and times are not supported");
                 break;;
             case toml::value_t::empty:
-                mkNull(v);
+                v.mkNull();
                 break;;
 
         }
diff --git a/src/libexpr/value.hh b/src/libexpr/value.hh
index 94a17136f..3f9b65197 100644
--- a/src/libexpr/value.hh
+++ b/src/libexpr/value.hh
@@ -393,31 +393,6 @@ public:
 
 
 // TODO: Remove these static functions, replace call sites with v.mk* instead
-static inline void mkInt(Value & v, NixInt n)
-{
-    v.mkInt(n);
-}
-
-static inline void mkFloat(Value & v, NixFloat n)
-{
-    v.mkFloat(n);
-}
-
-static inline void mkBool(Value & v, bool b)
-{
-    v.mkBool(b);
-}
-
-static inline void mkNull(Value & v)
-{
-    v.mkNull();
-}
-
-static inline void mkApp(Value & v, Value & left, Value & right)
-{
-    v.mkApp(&left, &right);
-}
-
 static inline void mkString(Value & v, const Symbol & s)
 {
     v.mkString(((const string &) s).c_str());
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index 7393d91f9..f64075567 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -408,7 +408,7 @@ static void queryInstSources(EvalState & state,
                 Expr * eFun = state.parseExprFromString(i, absPath("."));
                 Value vFun, vTmp;
                 state.eval(eFun, vFun);
-                mkApp(vTmp, vFun, vArg);
+                vTmp.mkApp(&vFun, &vArg);
                 getDerivations(state, vTmp, "", *instSource.autoArgs, elems, true);
             }
 
diff --git a/tests/plugins/plugintest.cc b/tests/plugins/plugintest.cc
index c085d3329..cd7c9f8b1 100644
--- a/tests/plugins/plugintest.cc
+++ b/tests/plugins/plugintest.cc
@@ -16,9 +16,9 @@ static GlobalConfig::Register rs(&mySettings);
 static void prim_anotherNull (EvalState & state, const Pos & pos, Value ** args, Value & v)
 {
     if (mySettings.settingSet)
-        mkNull(v);
+        v.mkNull();
     else
-        mkBool(v, false);
+        v.mkBool(false);
 }
 
 static RegisterPrimOp rp("anotherNull", 0, prim_anotherNull);

From ed93aec3c317e5dc3748b28e451c8eb6df377060 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 4 Jan 2022 18:45:16 +0100
Subject: [PATCH 371/567] Remove non-method mkPath()

---
 src/libexpr/eval.cc    | 7 +++----
 src/libexpr/primops.cc | 4 ++--
 src/libexpr/value.hh   | 5 ++---
 3 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 591aa6583..cd7d19747 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -786,9 +786,9 @@ void Value::mkString(std::string_view s, const PathSet & context)
 }
 
 
-void mkPath(Value & v, const char * s)
+void Value::mkPath(std::string_view s)
 {
-    v.mkPath(dupString(s));
+    mkPath(dupStringWithLen(s.data(), s.size()));
 }
 
 
@@ -1711,8 +1711,7 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
     else if (firstType == nPath) {
         if (!context.empty())
             throwEvalError(pos, "a string that refers to a store path cannot be appended to a path");
-        auto path = canonPath(s.str());
-        mkPath(v, path.c_str());
+        v.mkPath(canonPath(s.str()));
     } else
         v.mkString(s.str(), context);
 }
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 57be5ac23..650200ae4 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1441,7 +1441,7 @@ static void prim_dirOf(EvalState & state, const Pos & pos, Value * * args, Value
 {
     PathSet context;
     Path dir = dirOf(state.coerceToString(pos, *args[0], context, false, false));
-    if (args[0]->type() == nPath) mkPath(v, dir.c_str()); else v.mkString(dir, context);
+    if (args[0]->type() == nPath) v.mkPath(dir); else v.mkString(dir, context);
 }
 
 static RegisterPrimOp primop_dirOf({
@@ -1522,7 +1522,7 @@ static void prim_findFile(EvalState & state, const Pos & pos, Value * * args, Va
 
     string path = state.forceStringNoCtx(*args[1], pos);
 
-    mkPath(v, state.checkSourcePath(state.findFile(searchPath, path, pos)).c_str());
+    v.mkPath(state.checkSourcePath(state.findFile(searchPath, path, pos)));
 }
 
 static RegisterPrimOp primop_findFile(RegisterPrimOp::Info {
diff --git a/src/libexpr/value.hh b/src/libexpr/value.hh
index 3f9b65197..ba647a10d 100644
--- a/src/libexpr/value.hh
+++ b/src/libexpr/value.hh
@@ -248,6 +248,8 @@ public:
         path = s;
     }
 
+    void mkPath(std::string_view s);
+
     inline void mkNull()
     {
         clearValue();
@@ -399,9 +401,6 @@ static inline void mkString(Value & v, const Symbol & s)
 }
 
 
-void mkPath(Value & v, const char * s);
-
-
 #if HAVE_BOEHMGC
 typedef std::vector<Value *, traceable_allocator<Value *> > ValueVector;
 typedef std::map<Symbol, Value *, std::less<Symbol>, traceable_allocator<std::pair<const Symbol, Value *> > > ValueMap;

From ca5baf239277daecef489a415fe157094bd7e799 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 4 Jan 2022 19:09:40 +0100
Subject: [PATCH 372/567] Turn mkString(Symbol) into a method

---
 src/libexpr/nixexpr.hh |  2 +-
 src/libexpr/primops.cc | 10 +++++-----
 src/libexpr/value.hh   | 13 +++++--------
 3 files changed, 11 insertions(+), 14 deletions(-)

diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index aa5a3f332..0a60057e5 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -112,7 +112,7 @@ struct ExprString : Expr
 {
     Symbol s;
     Value v;
-    ExprString(const Symbol & s) : s(s) { mkString(v, s); };
+    ExprString(const Symbol & s) : s(s) { v.mkString(s); };
     COMMON_METHODS
     Value * maybeThunk(EvalState & state, Env & env);
 };
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 650200ae4..879dfa0a3 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -412,7 +412,7 @@ static void prim_typeOf(EvalState & state, const Pos & pos, Value * * args, Valu
         case nFloat: t = "float"; break;
         case nThunk: abort();
     }
-    mkString(v, state.symbols.create(t));
+    v.mkString(state.symbols.create(t));
 }
 
 static RegisterPrimOp primop_typeOf({
@@ -2129,7 +2129,7 @@ static void prim_attrNames(EvalState & state, const Pos & pos, Value * * args, V
 
     size_t n = 0;
     for (auto & i : *args[0]->attrs)
-        mkString(*(v.listElems()[n++] = state.allocValue()), i.name);
+        (v.listElems()[n++] = state.allocValue())->mkString(i.name);
 
     std::sort(v.listElems(), v.listElems() + n,
               [](Value * v1, Value * v2) { return strcmp(v1->string.s, v2->string.s) < 0; });
@@ -2477,7 +2477,7 @@ static void prim_mapAttrs(EvalState & state, const Pos & pos, Value * * args, Va
     for (auto & i : *args[1]->attrs) {
         Value * vName = state.allocValue();
         Value * vFun2 = state.allocValue();
-        mkString(*vName, i.name);
+        vName->mkString(i.name);
         vFun2->mkApp(args[0], vName);
         state.allocAttr(v, i.name)->mkApp(vFun2, i.value);
     }
@@ -2540,8 +2540,8 @@ static void prim_zipAttrsWith(EvalState & state, const Pos & pos, Value * * args
     }
 
     for (auto & attr : *v.attrs) {
-        Value * name = state.allocValue();
-        mkString(*name, attr.name);
+        auto name = state.allocValue();
+        name->mkString(attr.name);
         auto call1 = state.allocValue();
         call1->mkApp(args[0], name);
         auto call2 = state.allocValue();
diff --git a/src/libexpr/value.hh b/src/libexpr/value.hh
index ba647a10d..7d007ebdc 100644
--- a/src/libexpr/value.hh
+++ b/src/libexpr/value.hh
@@ -241,6 +241,11 @@ public:
 
     void mkString(std::string_view s, const PathSet & context);
 
+    inline void mkString(const Symbol & s)
+    {
+        mkString(((const std::string &) s).c_str());
+    }
+
     inline void mkPath(const char * s)
     {
         clearValue();
@@ -393,14 +398,6 @@ public:
 };
 
 
-
-// TODO: Remove these static functions, replace call sites with v.mk* instead
-static inline void mkString(Value & v, const Symbol & s)
-{
-    v.mkString(((const string &) s).c_str());
-}
-
-
 #if HAVE_BOEHMGC
 typedef std::vector<Value *, traceable_allocator<Value *> > ValueVector;
 typedef std::map<Symbol, Value *, std::less<Symbol>, traceable_allocator<std::pair<const Symbol, Value *> > > ValueMap;

From 17daec0b832205df781f6443292667c9aa617047 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 4 Jan 2022 19:23:11 +0100
Subject: [PATCH 373/567] Move empty attrset optimisation

---
 src/libexpr/attr-set.cc | 8 +++-----
 src/libexpr/eval.cc     | 3 +--
 src/libexpr/eval.hh     | 2 +-
 3 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/src/libexpr/attr-set.cc b/src/libexpr/attr-set.cc
index d74243f45..fc971957d 100644
--- a/src/libexpr/attr-set.cc
+++ b/src/libexpr/attr-set.cc
@@ -12,6 +12,8 @@ namespace nix {
    structure. */
 Bindings * EvalState::allocBindings(size_t capacity)
 {
+    if (capacity == 0)
+        return &emptyBindings;
     if (capacity > std::numeric_limits<Bindings::size_t>::max())
         throw Error("attribute set of size %d is too big", capacity);
     return new (allocBytes(sizeof(Bindings) + sizeof(Attr) * capacity)) Bindings((Bindings::size_t) capacity);
@@ -20,10 +22,6 @@ Bindings * EvalState::allocBindings(size_t capacity)
 
 void EvalState::mkAttrs(Value & v, size_t capacity)
 {
-    if (capacity == 0) {
-        v = vEmptySet;
-        return;
-    }
     v.mkAttrs(allocBindings(capacity));
     nrAttrsets++;
     nrAttrsInAttrsets += capacity;
@@ -63,7 +61,7 @@ Value & BindingsBuilder::alloc(std::string_view name, ptr<Pos> pos)
 
 void Bindings::sort()
 {
-    std::sort(begin(), end());
+    if (size_) std::sort(begin(), end());
 }
 
 
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index cd7d19747..112690189 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -413,6 +413,7 @@ EvalState::EvalState(
     , sSelf(symbols.create("self"))
     , sEpsilon(symbols.create(""))
     , repair(NoRepair)
+    , emptyBindings(0)
     , store(store)
     , buildStore(buildStore ? buildStore : store)
     , regexCache(makeRegexCache())
@@ -454,8 +455,6 @@ EvalState::EvalState(
         }
     }
 
-    vEmptySet.mkAttrs(allocBindings(0));
-
     createBaseEnv();
 }
 
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index c7f74d7b7..c0d88201a 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -91,7 +91,7 @@ public:
        mode. */
     std::optional<PathSet> allowedPaths;
 
-    Value vEmptySet;
+    Bindings emptyBindings;
 
     /* Store used to materialise .drv files. */
     const ref<Store> store;

From 2b4c94482364c236b03f7f8b61aca7076ab4079d Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 4 Jan 2022 20:29:17 +0100
Subject: [PATCH 374/567] Remove EvalState::mkAttrs()

---
 src/libexpr/attr-set.cc      | 13 +++--------
 src/libexpr/attr-set.hh      | 10 +++++++--
 src/libexpr/eval.cc          | 20 +++++++++--------
 src/libexpr/eval.hh          |  3 ++-
 src/libexpr/json-to-value.cc |  6 +++---
 src/libexpr/primops.cc       | 42 +++++++++++++++++++++---------------
 6 files changed, 52 insertions(+), 42 deletions(-)

diff --git a/src/libexpr/attr-set.cc b/src/libexpr/attr-set.cc
index fc971957d..52ac47e9b 100644
--- a/src/libexpr/attr-set.cc
+++ b/src/libexpr/attr-set.cc
@@ -7,6 +7,7 @@
 namespace nix {
 
 
+
 /* Allocate a new array of attributes for an attribute set with a specific
    capacity. The space is implicitly reserved after the Bindings
    structure. */
@@ -16,15 +17,9 @@ Bindings * EvalState::allocBindings(size_t capacity)
         return &emptyBindings;
     if (capacity > std::numeric_limits<Bindings::size_t>::max())
         throw Error("attribute set of size %d is too big", capacity);
-    return new (allocBytes(sizeof(Bindings) + sizeof(Attr) * capacity)) Bindings((Bindings::size_t) capacity);
-}
-
-
-void EvalState::mkAttrs(Value & v, size_t capacity)
-{
-    v.mkAttrs(allocBindings(capacity));
     nrAttrsets++;
     nrAttrsInAttrsets += capacity;
+    return new (allocBytes(sizeof(Bindings) + sizeof(Attr) * capacity)) Bindings((Bindings::size_t) capacity);
 }
 
 
@@ -67,9 +62,7 @@ void Bindings::sort()
 
 Value & Value::mkAttrs(BindingsBuilder & bindings)
 {
-    clearValue();
-    internalType = tAttrs;
-    attrs = bindings.finish();
+    mkAttrs(bindings.finish());
     return *this;
 }
 
diff --git a/src/libexpr/attr-set.hh b/src/libexpr/attr-set.hh
index 903289b69..82c348287 100644
--- a/src/libexpr/attr-set.hh
+++ b/src/libexpr/attr-set.hh
@@ -118,13 +118,14 @@ public:
    call finish(), which sorts the bindings. */
 class BindingsBuilder
 {
-    EvalState & state;
     Bindings * bindings;
 
 public:
 
+    EvalState & state;
+
     BindingsBuilder(EvalState & state, Bindings * bindings)
-        : state(state), bindings(bindings)
+        : bindings(bindings), state(state)
     { }
 
     void insert(Symbol name, Value * value, ptr<Pos> pos = ptr(&noPos))
@@ -146,6 +147,11 @@ public:
         bindings->sort();
         return bindings;
     }
+
+    Bindings * alreadySorted()
+    {
+        return bindings;
+    }
 };
 
 }
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 112690189..81aa86641 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -145,7 +145,7 @@ void printValue(std::ostream & str, std::set<const Value *> & active, const Valu
         str << v.fpoint;
         break;
     default:
-        throw Error("invalid value");
+        abort();
     }
 
     active.erase(&v);
@@ -1065,8 +1065,8 @@ void ExprPath::eval(EvalState & state, Env & env, Value & v)
 
 void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
 {
-    state.mkAttrs(v, attrs.size() + dynamicAttrs.size());
-    Env *dynamicEnv = &env;
+    v.mkAttrs(state.buildBindings(attrs.size() + dynamicAttrs.size()).finish());
+    auto dynamicEnv = &env;
 
     if (recursive) {
         /* Create a new environment that contains the attributes in
@@ -1592,7 +1592,7 @@ void ExprOpUpdate::eval(EvalState & state, Env & env, Value & v)
     if (v1.attrs->size() == 0) { v = v2; return; }
     if (v2.attrs->size() == 0) { v = v1; return; }
 
-    state.mkAttrs(v, v1.attrs->size() + v2.attrs->size());
+    auto attrs = state.buildBindings(v1.attrs->size() + v2.attrs->size());
 
     /* Merge the sets, preferring values from the second set.  Make
        sure to keep the resulting vector in sorted order. */
@@ -1601,17 +1601,19 @@ void ExprOpUpdate::eval(EvalState & state, Env & env, Value & v)
 
     while (i != v1.attrs->end() && j != v2.attrs->end()) {
         if (i->name == j->name) {
-            v.attrs->push_back(*j);
+            attrs.insert(*j);
             ++i; ++j;
         }
         else if (i->name < j->name)
-            v.attrs->push_back(*i++);
+            attrs.insert(*i++);
         else
-            v.attrs->push_back(*j++);
+            attrs.insert(*j++);
     }
 
-    while (i != v1.attrs->end()) v.attrs->push_back(*i++);
-    while (j != v2.attrs->end()) v.attrs->push_back(*j++);
+    while (i != v1.attrs->end()) attrs.insert(*i++);
+    while (j != v2.attrs->end()) attrs.insert(*j++);
+
+    v.mkAttrs(attrs.alreadySorted());
 
     state.nrOpUpdateValuesCopied += v.attrs->size();
 }
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index c0d88201a..89814785e 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -347,7 +347,6 @@ public:
     }
 
     void mkList(Value & v, size_t length);
-    void mkAttrs(Value & v, size_t capacity);
     void mkThunk_(Value & v, Expr * expr);
     void mkPos(Value & v, ptr<Pos> pos);
 
@@ -400,6 +399,8 @@ private:
     friend struct ExprSelect;
     friend void prim_getAttr(EvalState & state, const Pos & pos, Value * * args, Value & v);
     friend void prim_match(EvalState & state, const Pos & pos, Value * * args, Value & v);
+
+    friend struct Value;
 };
 
 
diff --git a/src/libexpr/json-to-value.cc b/src/libexpr/json-to-value.cc
index 4dc41729a..88716250c 100644
--- a/src/libexpr/json-to-value.cc
+++ b/src/libexpr/json-to-value.cc
@@ -37,10 +37,10 @@ class JSONSax : nlohmann::json_sax<json> {
         ValueMap attrs;
         std::unique_ptr<JSONState> resolve(EvalState & state) override
         {
-            Value & v = parent->value(state);
-            state.mkAttrs(v, attrs.size());
+            auto attrs2 = state.buildBindings(attrs.size());
             for (auto & i : attrs)
-                v.attrs->push_back(Attr(i.first, i.second));
+                attrs2.insert(i.first, i.second);
+            parent->value(state).mkAttrs(attrs2.alreadySorted());
             return std::move(parent);
         }
         void add() override { v = nullptr; }
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 879dfa0a3..d7382af6b 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -2274,11 +2274,12 @@ static void prim_removeAttrs(EvalState & state, const Pos & pos, Value * * args,
     /* Copy all attributes not in that set.  Note that we don't need
        to sort v.attrs because it's a subset of an already sorted
        vector. */
-    state.mkAttrs(v, args[0]->attrs->size());
+    auto attrs = state.buildBindings(args[0]->attrs->size());
     for (auto & i : *args[0]->attrs) {
         if (!names.count(i.name))
-            v.attrs->push_back(i);
+            attrs.insert(i);
     }
+    v.mkAttrs(attrs.alreadySorted());
 }
 
 static RegisterPrimOp primop_removeAttrs({
@@ -2369,13 +2370,15 @@ static void prim_intersectAttrs(EvalState & state, const Pos & pos, Value * * ar
     state.forceAttrs(*args[0], pos);
     state.forceAttrs(*args[1], pos);
 
-    state.mkAttrs(v, std::min(args[0]->attrs->size(), args[1]->attrs->size()));
+    auto attrs = state.buildBindings(std::min(args[0]->attrs->size(), args[1]->attrs->size()));
 
     for (auto & i : *args[0]->attrs) {
         Bindings::iterator j = args[1]->attrs->find(i.name);
         if (j != args[1]->attrs->end())
-            v.attrs->push_back(*j);
+            attrs.insert(*j);
     }
+
+    v.mkAttrs(attrs.alreadySorted());
 }
 
 static RegisterPrimOp primop_intersectAttrs({
@@ -2429,7 +2432,7 @@ static void prim_functionArgs(EvalState & state, const Pos & pos, Value * * args
 {
     state.forceValue(*args[0], pos);
     if (args[0]->isPrimOpApp() || args[0]->isPrimOp()) {
-        state.mkAttrs(v, 0);
+        v.mkAttrs(&state.emptyBindings);
         return;
     }
     if (!args[0]->isLambda())
@@ -2439,7 +2442,7 @@ static void prim_functionArgs(EvalState & state, const Pos & pos, Value * * args
         });
 
     if (!args[0]->lambda.fun->hasFormals()) {
-        state.mkAttrs(v, 0);
+        v.mkAttrs(&state.emptyBindings);
         return;
     }
 
@@ -2472,15 +2475,17 @@ static void prim_mapAttrs(EvalState & state, const Pos & pos, Value * * args, Va
 {
     state.forceAttrs(*args[1], pos);
 
-    state.mkAttrs(v, args[1]->attrs->size());
+    auto attrs = state.buildBindings(args[1]->attrs->size());
 
     for (auto & i : *args[1]->attrs) {
         Value * vName = state.allocValue();
         Value * vFun2 = state.allocValue();
         vName->mkString(i.name);
         vFun2->mkApp(args[0], vName);
-        state.allocAttr(v, i.name)->mkApp(vFun2, i.value);
+        attrs.alloc(i.name).mkApp(vFun2, i.value);
     }
+
+    v.mkAttrs(attrs.alreadySorted());
 }
 
 static RegisterPrimOp primop_mapAttrs({
@@ -2526,12 +2531,13 @@ static void prim_zipAttrsWith(EvalState & state, const Pos & pos, Value * * args
         }
     }
 
-    state.mkAttrs(v, attrsSeen.size());
+    auto attrs = state.buildBindings(attrsSeen.size());
     for (auto & [sym, elem] : attrsSeen) {
-        Value * list = state.allocAttr(v, sym);
-        state.mkList(*list, elem.first);
-        elem.second = list->listElems();
+        auto & list = attrs.alloc(sym);
+        state.mkList(list, elem.first);
+        elem.second = list.listElems();
     }
+    v.mkAttrs(attrs.alreadySorted());
 
     for (unsigned int n = 0; n < listSize; ++n) {
         Value * vElem = listElems[n];
@@ -3054,14 +3060,16 @@ static void prim_groupBy(EvalState & state, const Pos & pos, Value * * args, Val
         vector->second.push_back(vElem);
     }
 
-    state.mkAttrs(v, attrs.size());
+    auto attrs2 = state.buildBindings(attrs.size());
 
     for (auto & i : attrs) {
-        Value * list = state.allocAttr(v, i.first);
+        auto & list = attrs2.alloc(i.first);
         auto size = i.second.size();
-        state.mkList(*list, size);
-        memcpy(list->listElems(), i.second.data(), sizeof(Value *) * size);
+        state.mkList(list, size);
+        memcpy(list.listElems(), i.second.data(), sizeof(Value *) * size);
     }
+
+    v.mkAttrs(attrs2.alreadySorted());
 }
 
 static RegisterPrimOp primop_groupBy({
@@ -3829,7 +3837,7 @@ void EvalState::createBaseEnv()
     Value v;
 
     /* `builtins' must be first! */
-    mkAttrs(v, 128);
+    v.mkAttrs(buildBindings(128).finish());
     addConstant("builtins", v);
 
     v.mkBool(true);

From 65257614ea77437a75447c3b5936f240e581ede9 Mon Sep 17 00:00:00 2001
From: Farid Zakaria <fmzakari@google.com>
Date: Thu, 6 Jan 2022 09:13:18 -0800
Subject: [PATCH 375/567] Add outputs to JSON query

Emit output information when printing JSON information
and `--out-paths` is requested.

fixes #5877
---
 src/nix-env/nix-env.cc | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index f64075567..b2d789324 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -907,7 +907,7 @@ static VersionDiff compareVersionAgainstSet(
 }
 
 
-static void queryJSON(Globals & globals, vector<DrvInfo> & elems)
+static void queryJSON(Globals & globals, vector<DrvInfo> & elems, bool printOutPath)
 {
     JSONObject topObj(cout, true);
     for (auto & i : elems) {
@@ -919,6 +919,14 @@ static void queryJSON(Globals & globals, vector<DrvInfo> & elems)
         pkgObj.attr("version", drvName.version);
         pkgObj.attr("system", i.querySystem());
 
+        if (printOutPath) {
+            DrvInfo::Outputs outputs = i.queryOutputs();
+            JSONObject outputObj = pkgObj.object("outputs");
+            for (auto & j : outputs) {
+                outputObj.attr(j.first, j.second);
+            }
+        }
+
         JSONObject metaObj = pkgObj.object("meta");
         StringSet metaNames = i.queryMetaNames();
         for (auto & j : metaNames) {
@@ -1035,7 +1043,7 @@ static void opQuery(Globals & globals, Strings opFlags, Strings opArgs)
 
     /* Print the desired columns, or XML output. */
     if (jsonOutput) {
-        queryJSON(globals, elems);
+        queryJSON(globals, elems, printOutPath);
         return;
     }
 

From e36fdbbfd9812a9d0a3aadf5f7898c9092d72963 Mon Sep 17 00:00:00 2001
From: Farid Zakaria <fmzakari@google.com>
Date: Thu, 6 Jan 2022 14:40:02 -0800
Subject: [PATCH 376/567] Check for `--meta` before emitting it for `--json`

Check that the meta flag is present when emitting JSON query information
for `nix-env`.

fixes #5882
---
 src/nix-env/nix-env.cc | 28 +++++++++++++++-------------
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index b2d789324..f4647f43d 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -907,7 +907,7 @@ static VersionDiff compareVersionAgainstSet(
 }
 
 
-static void queryJSON(Globals & globals, vector<DrvInfo> & elems, bool printOutPath)
+static void queryJSON(Globals & globals, vector<DrvInfo> & elems, bool printOutPath, bool printMeta)
 {
     JSONObject topObj(cout, true);
     for (auto & i : elems) {
@@ -927,17 +927,19 @@ static void queryJSON(Globals & globals, vector<DrvInfo> & elems, bool printOutP
             }
         }
 
-        JSONObject metaObj = pkgObj.object("meta");
-        StringSet metaNames = i.queryMetaNames();
-        for (auto & j : metaNames) {
-            auto placeholder = metaObj.placeholder(j);
-            Value * v = i.queryMeta(j);
-            if (!v) {
-                printError("derivation '%s' has invalid meta attribute '%s'", i.queryName(), j);
-                placeholder.write(nullptr);
-            } else {
-                PathSet context;
-                printValueAsJSON(*globals.state, true, *v, noPos, placeholder, context);
+        if (printMeta) {
+            JSONObject metaObj = pkgObj.object("meta");
+            StringSet metaNames = i.queryMetaNames();
+            for (auto & j : metaNames) {
+                auto placeholder = metaObj.placeholder(j);
+                Value * v = i.queryMeta(j);
+                if (!v) {
+                    printError("derivation '%s' has invalid meta attribute '%s'", i.queryName(), j);
+                    placeholder.write(nullptr);
+                } else {
+                    PathSet context;
+                    printValueAsJSON(*globals.state, true, *v, noPos, placeholder, context);
+                }
             }
         }
     }
@@ -1043,7 +1045,7 @@ static void opQuery(Globals & globals, Strings opFlags, Strings opArgs)
 
     /* Print the desired columns, or XML output. */
     if (jsonOutput) {
-        queryJSON(globals, elems, printOutPath);
+        queryJSON(globals, elems, printOutPath, printMeta);
         return;
     }
 

From 26a8b220eb7470e132b9bcedb94b58492cdd786f Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Tue, 28 Dec 2021 22:26:59 +0100
Subject: [PATCH 377/567] avoid ostream sentries per json string character
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

we don't have to create an ostream sentry object for every character of a JSON
string we write. format a bunch of characters and flush them to the stream all
at once instead.

this doesn't affect small numbers of string characters, but larger numbers of
total JSON string characters written gain a lot. at 1MB of total string written
we gain almost 30%, at 16MB it's almost a factor of 3x. large numbers of JSON
string characters do occur naturally in a nixos system evaluation to generate
documentation (though this is now somewhat mitigated by caching the largest part
of nixos option docs).

benchmarked with

  hyperfine 'nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) {e})"' --warmup 1 -L e 1,4,256,4096,65536

before:

  Benchmark 1: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 1)"
    Time (mean ± σ):      12.5 ms ±   0.2 ms    [User: 9.2 ms, System: 4.0 ms]
    Range (min … max):    11.9 ms …  13.1 ms    223 runs

  Benchmark 2: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 4)"
    Time (mean ± σ):      12.5 ms ±   0.2 ms    [User: 9.3 ms, System: 3.8 ms]
    Range (min … max):    11.9 ms …  13.2 ms    220 runs

  Benchmark 3: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 256)"
    Time (mean ± σ):      13.2 ms ±   0.3 ms    [User: 9.8 ms, System: 4.0 ms]
    Range (min … max):    12.6 ms …  14.3 ms    205 runs

  Benchmark 4: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 4096)"
    Time (mean ± σ):      24.0 ms ±   0.4 ms    [User: 19.4 ms, System: 5.2 ms]
    Range (min … max):    22.7 ms …  25.8 ms    119 runs

  Benchmark 5: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 65536)"
    Time (mean ± σ):     196.0 ms ±   3.7 ms    [User: 171.2 ms, System: 25.8 ms]
    Range (min … max):   190.6 ms … 201.5 ms    14 runs

after:

  Benchmark 1: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 1)"
    Time (mean ± σ):      12.4 ms ±   0.3 ms    [User: 9.1 ms, System: 4.0 ms]
    Range (min … max):    11.7 ms …  13.3 ms    204 runs

  Benchmark 2: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 4)"
    Time (mean ± σ):      12.4 ms ±   0.2 ms    [User: 9.2 ms, System: 3.9 ms]
    Range (min … max):    11.8 ms …  13.0 ms    214 runs

  Benchmark 3: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 256)"
    Time (mean ± σ):      12.6 ms ±   0.2 ms    [User: 9.5 ms, System: 3.8 ms]
    Range (min … max):    12.1 ms …  13.3 ms    209 runs

  Benchmark 4: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 4096)"
    Time (mean ± σ):      15.9 ms ±   0.2 ms    [User: 11.4 ms, System: 5.1 ms]
    Range (min … max):    15.2 ms …  16.4 ms    171 runs

  Benchmark 5: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 65536)"
    Time (mean ± σ):      69.0 ms ±   0.9 ms    [User: 44.3 ms, System: 25.3 ms]
    Range (min … max):    67.2 ms …  70.9 ms    42 runs
---
 src/libutil/json.cc | 42 ++++++++++++++++++++++++++++++++----------
 1 file changed, 32 insertions(+), 10 deletions(-)

diff --git a/src/libutil/json.cc b/src/libutil/json.cc
index 01331947e..3a981376f 100644
--- a/src/libutil/json.cc
+++ b/src/libutil/json.cc
@@ -7,16 +7,38 @@ namespace nix {
 
 void toJSON(std::ostream & str, const char * start, const char * end)
 {
-    str << '"';
-    for (auto i = start; i != end; i++)
-        if (*i == '\"' || *i == '\\') str << '\\' << *i;
-        else if (*i == '\n') str << "\\n";
-        else if (*i == '\r') str << "\\r";
-        else if (*i == '\t') str << "\\t";
-        else if (*i >= 0 && *i < 32)
-            str << "\\u" << std::setfill('0') << std::setw(4) << std::hex << (uint16_t) *i << std::dec;
-        else str << *i;
-    str << '"';
+    constexpr size_t BUF_SIZE = 4096;
+    char buf[BUF_SIZE + 7]; // BUF_SIZE + largest single sequence of puts
+    size_t bufPos = 0;
+
+    const auto flush = [&] {
+        str.write(buf, bufPos);
+        bufPos = 0;
+    };
+    const auto put = [&] (char c) {
+        buf[bufPos++] = c;
+    };
+
+    put('"');
+    for (auto i = start; i != end; i++) {
+        if (bufPos >= BUF_SIZE) flush();
+        if (*i == '\"' || *i == '\\') { put('\\'); put(*i); }
+        else if (*i == '\n') { put('\\'); put('n'); }
+        else if (*i == '\r') { put('\\'); put('r'); }
+        else if (*i == '\t') { put('\\'); put('t'); }
+        else if (*i >= 0 && *i < 32) {
+            const char hex[17] = "0123456789abcdef";
+            put('\\');
+            put('u');
+            put(hex[(uint16_t(*i) >> 12) & 0xf]);
+            put(hex[(uint16_t(*i) >>  8) & 0xf]);
+            put(hex[(uint16_t(*i) >>  4) & 0xf]);
+            put(hex[(uint16_t(*i) >>  0) & 0xf]);
+        }
+        else put(*i);
+    }
+    put('"');
+    flush();
 }
 
 void toJSON(std::ostream & str, const char * s)

From be64fb9b5160f50d5b127598c84ffb77b980799b Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 8 Dec 2021 14:03:44 +0100
Subject: [PATCH 378/567] DerivationGoal::loadDerivation(): Don't use
 derivationFromPath()

This causes a recursive call to ensurePath(), which is not a good
idea.
---
 src/libstore/build/derivation-goal.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libstore/build/derivation-goal.cc b/src/libstore/build/derivation-goal.cc
index c6ab5c3d1..d34e53fe8 100644
--- a/src/libstore/build/derivation-goal.cc
+++ b/src/libstore/build/derivation-goal.cc
@@ -194,7 +194,7 @@ void DerivationGoal::loadDerivation()
     assert(worker.evalStore.isValidPath(drvPath));
 
     /* Get the derivation. */
-    drv = std::make_unique<Derivation>(worker.evalStore.derivationFromPath(drvPath));
+    drv = std::make_unique<Derivation>(worker.evalStore.readDerivation(drvPath));
 
     haveDerivation();
 }

From e1a0359b599d0beeb93f11d9948ec2cb1a1008c4 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 2 Dec 2021 14:16:05 +0100
Subject: [PATCH 379/567] isInDir() / isDirOrInDir(): Use std::string_view

---
 src/libutil/util.cc |  8 ++++----
 src/libutil/util.hh | 10 ++++++----
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index e18648557..9edd69c64 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -196,16 +196,16 @@ std::string_view baseNameOf(std::string_view path)
 }
 
 
-bool isInDir(const Path & path, const Path & dir)
+bool isInDir(std::string_view path, std::string_view dir)
 {
-    return path[0] == '/'
-        && string(path, 0, dir.size()) == dir
+    return path.substr(0, 1) == "/"
+        && path.substr(0, dir.size()) == dir
         && path.size() >= dir.size() + 2
         && path[dir.size()] == '/';
 }
 
 
-bool isDirOrInDir(const Path & path, const Path & dir)
+bool isDirOrInDir(std::string_view path, std::string_view dir)
 {
     return path == dir || isInDir(path, dir);
 }
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index d08f42826..dfad33ed2 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -66,11 +66,13 @@ Path dirOf(const Path & path);
    following the final `/' (trailing slashes are removed). */
 std::string_view baseNameOf(std::string_view path);
 
-/* Check whether 'path' is a descendant of 'dir'. */
-bool isInDir(const Path & path, const Path & dir);
+/* Check whether 'path' is a descendant of 'dir'. Both paths must be
+   canonicalized. */
+bool isInDir(std::string_view path, std::string_view dir);
 
-/* Check whether 'path' is equal to 'dir' or a descendant of 'dir'. */
-bool isDirOrInDir(const Path & path, const Path & dir);
+/* Check whether 'path' is equal to 'dir' or a descendant of
+   'dir'. Both paths must be canonicalized. */
+bool isDirOrInDir(std::string_view path, std::string_view dir);
 
 /* Get status of `path'. */
 struct stat lstat(const Path & path);

From fcddaa4b9b22a910a24a513bc05579a12eb1db41 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 2 Dec 2021 20:56:26 +0100
Subject: [PATCH 380/567] dump(): Use emplace()

---
 src/libutil/archive.cc | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/libutil/archive.cc b/src/libutil/archive.cc
index d78ec2b93..fdee643b1 100644
--- a/src/libutil/archive.cc
+++ b/src/libutil/archive.cc
@@ -93,13 +93,12 @@ static void dump(const Path & path, Sink & sink, PathFilter & filter)
                     debug(format("removing case hack suffix from '%1%'") % (path + "/" + i.name));
                     name.erase(pos);
                 }
-                if (unhacked.find(name) != unhacked.end())
+                if (!unhacked.emplace(name, i.name).second)
                     throw Error("file name collision in between '%1%' and '%2%'",
                        (path + "/" + unhacked[name]),
                        (path + "/" + i.name));
-                unhacked[name] = i.name;
             } else
-                unhacked[i.name] = i.name;
+                unhacked.emplace(i.name, i.name);
 
         for (auto & i : unhacked)
             if (filter(path + "/" + i.first)) {

From c66865dff1747ecd55915ef8c549dc1a088ff168 Mon Sep 17 00:00:00 2001
From: Nikolay Amiantov <ab@fmap.me>
Date: Fri, 4 Mar 2016 13:47:19 +0300
Subject: [PATCH 381/567] builtins.readFile: Propagate path context

Co-authored-by: Shea Levy <shea@shealevy.com>
---
 src/libexpr/primops.cc | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index d7382af6b..1d2a7d5d2 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1470,7 +1470,11 @@ static void prim_readFile(EvalState & state, const Pos & pos, Value * * args, Va
     string s = readFile(path);
     if (s.find((char) 0) != string::npos)
         throw Error("the contents of the file '%1%' cannot be represented as a Nix string", path);
-    v.mkString(s);
+    auto refs = state.store->isInStore(path) ?
+        state.store->queryPathInfo(state.store->toStorePath(path).first)->references :
+        StorePathSet{};
+    auto context = state.store->printStorePathSet(refs);
+    v.mkString(s, context);
 }
 
 static RegisterPrimOp primop_readFile({

From 120ca245d13708743a59e83da12ec90902636236 Mon Sep 17 00:00:00 2001
From: Nikolay Amiantov <ab@fmap.me>
Date: Sat, 11 Nov 2017 01:51:34 +0300
Subject: [PATCH 382/567] Add test for readFile keeping context

---
 tests/local.mk                    |  3 ++-
 tests/readfile-context.builder.sh |  1 +
 tests/readfile-context.nix        | 19 +++++++++++++++++++
 tests/readfile-context.sh         | 16 ++++++++++++++++
 4 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 tests/readfile-context.builder.sh
 create mode 100644 tests/readfile-context.nix
 create mode 100644 tests/readfile-context.sh

diff --git a/tests/local.mk b/tests/local.mk
index c22e779a6..d2a46f22b 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -59,7 +59,8 @@ nix_tests = \
   ca/recursive.sh \
   ca/concurrent-builds.sh \
   ca/nix-copy.sh \
-  eval-store.sh
+  eval-store.sh \
+  readfile-context.sh
   # parallel.sh
 
 ifeq ($(HAVE_LIBCPUID), 1)
diff --git a/tests/readfile-context.builder.sh b/tests/readfile-context.builder.sh
new file mode 100644
index 000000000..7084a08cb
--- /dev/null
+++ b/tests/readfile-context.builder.sh
@@ -0,0 +1 @@
+echo "$input" > $out
diff --git a/tests/readfile-context.nix b/tests/readfile-context.nix
new file mode 100644
index 000000000..600036a94
--- /dev/null
+++ b/tests/readfile-context.nix
@@ -0,0 +1,19 @@
+with import ./config.nix;
+
+let
+
+  input = import ./simple.nix;
+
+  dependent = mkDerivation {
+    name = "dependent";
+    builder = ./readfile-context.builder.sh;
+    input = "${input}/hello";
+  };
+
+  readDependent = mkDerivation {
+    name = "read-dependent";
+    builder = ./readfile-context.builder.sh;
+    input = builtins.readFile dependent;
+  };
+
+in readDependent
diff --git a/tests/readfile-context.sh b/tests/readfile-context.sh
new file mode 100644
index 000000000..31e70ddb1
--- /dev/null
+++ b/tests/readfile-context.sh
@@ -0,0 +1,16 @@
+source common.sh
+
+clearStore
+
+outPath=$(nix-build --no-out-link readfile-context.nix)
+
+# Set a GC root.
+ln -s $outPath "$NIX_STATE_DIR"/gcroots/foo
+
+# Check that file exists.
+[ "$(cat $(cat $outPath))" = "Hello World!" ]
+
+nix-collect-garbage
+
+# Check that file still exists.
+[ "$(cat $(cat $outPath))" = "Hello World!" ]

From 19fd6e585d8f4cad3e358361b6f983b0d7d3b8a9 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 10 Jan 2022 16:52:25 +0100
Subject: [PATCH 383/567] 'target' points to 'source'

---
 src/libstore/build/local-derivation-goal.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index d3434d63e..8dd1965e1 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -1427,7 +1427,7 @@ void LocalDerivationGoal::addDependency(const StorePath & path)
 
             Path source = worker.store.Store::toRealPath(path);
             Path target = chrootRootDir + worker.store.printStorePath(path);
-            debug("bind-mounting %s -> %s", source, target);
+            debug("bind-mounting %s -> %s", target, source);
 
             if (pathExists(target))
                 throw Error("store path '%s' already exists in the sandbox", worker.store.printStorePath(path));

From e9a4abdb5d6fe8e128372a77d879b0187b1bacfe Mon Sep 17 00:00:00 2001
From: Guillaume Maudoux <guillaume.maudoux@tweag.io>
Date: Tue, 11 Jan 2022 11:57:45 +0100
Subject: [PATCH 384/567] Make --repair-path also repair corrupt optimised
 links

There already existed a smoke test for the link content length,
but it appears that there exists some corruptions pernicious enough
to replace the file content with zeros, and keeping the same length.

--repair-path now goes as far as checking the content of the link,
making it true to its name and actually repairing the path for such
coruption cases.
---
 src/libstore/build/local-derivation-goal.cc |  2 +-
 src/libstore/local-store.cc                 |  6 +--
 src/libstore/local-store.hh                 |  7 +--
 src/libstore/optimise-store.cc              | 31 ++++++++------
 src/libutil/logging.hh                      |  2 +-
 tests/repair.sh                             | 47 +++++++++++++++++++++
 6 files changed, 75 insertions(+), 20 deletions(-)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 66d950b42..9ad28c6a9 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -2460,7 +2460,7 @@ void LocalDerivationGoal::registerOutputs()
         }
 
         if (curRound == nrRounds) {
-            localStore.optimisePath(actualPath); // FIXME: combine with scanForReferences()
+            localStore.optimisePath(actualPath, false); // FIXME: combine with scanForReferences()
             worker.markContentsGood(newInfo.path);
         }
 
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 1b8e77ead..9ebdfd6ed 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -1307,7 +1307,7 @@ void LocalStore::addToStore(const ValidPathInfo & info, Source & source,
 
             canonicalisePathMetaData(realPath, -1);
 
-            optimisePath(realPath); // FIXME: combine with hashPath()
+            optimisePath(realPath, repair); // FIXME: combine with hashPath()
 
             registerValidPath(info);
         }
@@ -1419,7 +1419,7 @@ StorePath LocalStore::addToStoreFromDump(Source & source0, const string & name,
 
             canonicalisePathMetaData(realPath, -1); // FIXME: merge into restorePath
 
-            optimisePath(realPath);
+            optimisePath(realPath, repair);
 
             ValidPathInfo info { dstPath, narHash.first };
             info.narSize = narHash.second;
@@ -1463,7 +1463,7 @@ StorePath LocalStore::addTextToStore(const string & name, const string & s,
             dumpString(s, sink);
             auto narHash = hashString(htSHA256, *sink.s);
 
-            optimisePath(realPath);
+            optimisePath(realPath, repair);
 
             ValidPathInfo info { dstPath, narHash };
             info.narSize = sink.s->size();
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 115ea046a..04698ba07 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -172,8 +172,9 @@ public:
 
     void optimiseStore() override;
 
-    /* Optimise a single store path. */
-    void optimisePath(const Path & path);
+    /* Optimise a single store path. Optionally, test the encountered
+       symlinks for corruption. */
+    void optimisePath(const Path & path, bool repair);
 
     bool verifyStore(bool checkContents, RepairFlag repair) override;
 
@@ -253,7 +254,7 @@ private:
 
     InodeHash loadInodeHash();
     Strings readDirectoryIgnoringInodes(const Path & path, const InodeHash & inodeHash);
-    void optimisePath_(Activity * act, OptimiseStats & stats, const Path & path, InodeHash & inodeHash);
+    void optimisePath_(Activity * act, OptimiseStats & stats, const Path & path, InodeHash & inodeHash, bool repair);
 
     // Internal versions that are not wrapped in retry_sqlite.
     bool isValidPath_(State & state, const StorePath & path);
diff --git a/src/libstore/optimise-store.cc b/src/libstore/optimise-store.cc
index d95e54af1..c93d0706d 100644
--- a/src/libstore/optimise-store.cc
+++ b/src/libstore/optimise-store.cc
@@ -88,7 +88,7 @@ Strings LocalStore::readDirectoryIgnoringInodes(const Path & path, const InodeHa
 
 
 void LocalStore::optimisePath_(Activity * act, OptimiseStats & stats,
-    const Path & path, InodeHash & inodeHash)
+    const Path & path, InodeHash & inodeHash, bool repair)
 {
     checkInterrupt();
 
@@ -110,7 +110,7 @@ void LocalStore::optimisePath_(Activity * act, OptimiseStats & stats,
     if (S_ISDIR(st.st_mode)) {
         Strings names = readDirectoryIgnoringInodes(path, inodeHash);
         for (auto & i : names)
-            optimisePath_(act, stats, path + "/" + i, inodeHash);
+            optimisePath_(act, stats, path + "/" + i, inodeHash, repair);
         return;
     }
 
@@ -151,7 +151,20 @@ void LocalStore::optimisePath_(Activity * act, OptimiseStats & stats,
     /* Check if this is a known hash. */
     Path linkPath = linksDir + "/" + hash.to_string(Base32, false);
 
- retry:
+    /* Maybe delete the link, if it has been corrupted. */
+    if (pathExists(linkPath)) {
+        auto stLink = lstat(linkPath);
+        if (st.st_size != stLink.st_size
+            || (repair && hash != hashPath(htSHA256, linkPath).first))
+        {
+            // XXX: Consider overwriting linkPath with our valid version.
+            warn("removing corrupted link '%s'", linkPath);
+            warn("There may be more corrupted paths."
+                 "\nYou should run `nix-store --verify --check-contents --repair` to fix them all");
+            unlink(linkPath.c_str());
+        }
+    }
+
     if (!pathExists(linkPath)) {
         /* Nope, create a hard link in the links directory. */
         if (link(path.c_str(), linkPath.c_str()) == 0) {
@@ -187,12 +200,6 @@ void LocalStore::optimisePath_(Activity * act, OptimiseStats & stats,
         return;
     }
 
-    if (st.st_size != stLink.st_size) {
-        warn("removing corrupted link '%s'", linkPath);
-        unlink(linkPath.c_str());
-        goto retry;
-    }
-
     printMsg(lvlTalkative, format("linking '%1%' to '%2%'") % path % linkPath);
 
     /* Make the containing directory writable, but only if it's not
@@ -260,7 +267,7 @@ void LocalStore::optimiseStore(OptimiseStats & stats)
         if (!isValidPath(i)) continue; /* path was GC'ed, probably */
         {
             Activity act(*logger, lvlTalkative, actUnknown, fmt("optimising path '%s'", printStorePath(i)));
-            optimisePath_(&act, stats, realStoreDir + "/" + std::string(i.to_string()), inodeHash);
+            optimisePath_(&act, stats, realStoreDir + "/" + std::string(i.to_string()), inodeHash, false);
         }
         done++;
         act.progress(done, paths.size());
@@ -278,12 +285,12 @@ void LocalStore::optimiseStore()
         stats.filesLinked);
 }
 
-void LocalStore::optimisePath(const Path & path)
+void LocalStore::optimisePath(const Path & path, bool repair)
 {
     OptimiseStats stats;
     InodeHash inodeHash;
 
-    if (settings.autoOptimiseStore) optimisePath_(nullptr, stats, path, inodeHash);
+    if (settings.autoOptimiseStore) optimisePath_(nullptr, stats, path, inodeHash, repair);
 }
 
 
diff --git a/src/libutil/logging.hh b/src/libutil/logging.hh
index ce9c3dfed..5560d2bed 100644
--- a/src/libutil/logging.hh
+++ b/src/libutil/logging.hh
@@ -40,7 +40,7 @@ struct LoggerSettings : Config
     Setting<bool> showTrace{
         this, false, "show-trace",
         R"(
-          Where Nix should print out a stack trace in case of Nix
+          Whether Nix should print out a stack trace in case of Nix
           expression evaluation errors.
         )"};
 };
diff --git a/tests/repair.sh b/tests/repair.sh
index 1105b446b..c8f07b1c6 100644
--- a/tests/repair.sh
+++ b/tests/repair.sh
@@ -74,3 +74,50 @@ if [ "$(nix-hash $path2)" != "$hash" -o -e $path2/bad ]; then
     echo "path not repaired properly" >&2
     exit 1
 fi
+
+# Check that --repair-path also checks content of optimised symlinks (1/2)
+nix-store --verify-path $path2
+
+if (! nix-store --optimize); then
+    echo "nix-store --optimize failed to optimize the store" >&2
+    exit 1
+fi
+chmod u+w $path2/bar
+echo 'rabrab' > $path2/bar # different length
+
+if nix-store --verify-path $path2; then
+    echo "nix-store --verify-path did not detect .links file corruption" >&2
+    exit 1
+fi
+
+nix-store --repair-path $path2 --option auto-optimise-store true
+
+if [ "$(nix-hash $path2)" != "$hash" -o "BAR" != "$(< $path2/bar)" ]; then
+    echo "path not repaired properly" >&2
+    exit 1
+fi
+
+# Check that --repair-path also checks content of optimised symlinks (2/2)
+nix-store --verify-path $path2
+
+if (! nix-store --optimize); then
+    echo "nix-store --optimize failed to optimize the store" >&2
+    exit 1
+fi
+chmod u+w $path2
+chmod u+w $path2/bar
+sed -e 's/./X/g' < $path2/bar > $path2/tmp # same length, different content.
+cp $path2/tmp $path2/bar
+rm $path2/tmp
+
+if nix-store --verify-path $path2; then
+    echo "nix-store --verify-path did not detect .links file corruption" >&2
+    exit 1
+fi
+
+nix-store --repair-path $path2 --substituters "file://$cacheDir" --no-require-sigs --option auto-optimise-store true
+
+if [ "$(nix-hash $path2)" != "$hash" -o "BAR" != "$(< $path2/bar)" ]; then
+    echo "path not repaired properly" >&2
+    exit 1
+fi

From 9f9f39a24b515d5d3ddd2bbd4cdadb0b1924bc3b Mon Sep 17 00:00:00 2001
From: Guillaume Maudoux <guillaume.maudoux@tweag.io>
Date: Tue, 11 Jan 2022 13:34:57 +0100
Subject: [PATCH 385/567] Prefer RepairFlag over bool when applicable

---
 src/libstore/build/local-derivation-goal.cc | 2 +-
 src/libstore/local-store.hh                 | 4 ++--
 src/libstore/optimise-store.cc              | 6 +++---
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 9ad28c6a9..61991a7e5 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -2460,7 +2460,7 @@ void LocalDerivationGoal::registerOutputs()
         }
 
         if (curRound == nrRounds) {
-            localStore.optimisePath(actualPath, false); // FIXME: combine with scanForReferences()
+            localStore.optimisePath(actualPath, NoRepair); // FIXME: combine with scanForReferences()
             worker.markContentsGood(newInfo.path);
         }
 
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 04698ba07..c4d7b80bd 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -174,7 +174,7 @@ public:
 
     /* Optimise a single store path. Optionally, test the encountered
        symlinks for corruption. */
-    void optimisePath(const Path & path, bool repair);
+    void optimisePath(const Path & path, RepairFlag repair);
 
     bool verifyStore(bool checkContents, RepairFlag repair) override;
 
@@ -254,7 +254,7 @@ private:
 
     InodeHash loadInodeHash();
     Strings readDirectoryIgnoringInodes(const Path & path, const InodeHash & inodeHash);
-    void optimisePath_(Activity * act, OptimiseStats & stats, const Path & path, InodeHash & inodeHash, bool repair);
+    void optimisePath_(Activity * act, OptimiseStats & stats, const Path & path, InodeHash & inodeHash, RepairFlag repair);
 
     // Internal versions that are not wrapped in retry_sqlite.
     bool isValidPath_(State & state, const StorePath & path);
diff --git a/src/libstore/optimise-store.cc b/src/libstore/optimise-store.cc
index c93d0706d..1833c954e 100644
--- a/src/libstore/optimise-store.cc
+++ b/src/libstore/optimise-store.cc
@@ -88,7 +88,7 @@ Strings LocalStore::readDirectoryIgnoringInodes(const Path & path, const InodeHa
 
 
 void LocalStore::optimisePath_(Activity * act, OptimiseStats & stats,
-    const Path & path, InodeHash & inodeHash, bool repair)
+    const Path & path, InodeHash & inodeHash, RepairFlag repair)
 {
     checkInterrupt();
 
@@ -267,7 +267,7 @@ void LocalStore::optimiseStore(OptimiseStats & stats)
         if (!isValidPath(i)) continue; /* path was GC'ed, probably */
         {
             Activity act(*logger, lvlTalkative, actUnknown, fmt("optimising path '%s'", printStorePath(i)));
-            optimisePath_(&act, stats, realStoreDir + "/" + std::string(i.to_string()), inodeHash, false);
+            optimisePath_(&act, stats, realStoreDir + "/" + std::string(i.to_string()), inodeHash, NoRepair);
         }
         done++;
         act.progress(done, paths.size());
@@ -285,7 +285,7 @@ void LocalStore::optimiseStore()
         stats.filesLinked);
 }
 
-void LocalStore::optimisePath(const Path & path, bool repair)
+void LocalStore::optimisePath(const Path & path, RepairFlag repair)
 {
     OptimiseStats stats;
     InodeHash inodeHash;

From 89b4df8d9271303416ac7ce6d86f9be58f40540d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Theodor=20Ren=C3=A9=20Carlsen?=
 <36312737+TheodorRene@users.noreply.github.com>
Date: Tue, 11 Jan 2022 17:01:43 +0100
Subject: [PATCH 386/567] Add link to explanation when introducing a new
 operator

The logical implication operator is included in this section but never explained. It might stump new readers with a pretty uncommon operator, and it's never referenced explicitly.
---
 doc/manual/src/expressions/language-constructs.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/doc/manual/src/expressions/language-constructs.md b/doc/manual/src/expressions/language-constructs.md
index cb0169239..c406b6910 100644
--- a/doc/manual/src/expressions/language-constructs.md
+++ b/doc/manual/src/expressions/language-constructs.md
@@ -276,6 +276,7 @@ stdenv.mkDerivation {
   ...
 }
 ```
+("->" is a boolean operation known as [logical implication](https://en.wikipedia.org/wiki/Truth_table#Logical_implication))
 
 The points of interest are:
 

From 9aa486c4be2801a25847b9c75012054d04e792d0 Mon Sep 17 00:00:00 2001
From: Rok Garbas <rok@garbas.si>
Date: Tue, 21 Dec 2021 21:26:52 +0100
Subject: [PATCH 387/567] Rename github workflow from Tests to CI

---
 .github/workflows/{test.yml => ci.yml} | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
 rename .github/workflows/{test.yml => ci.yml} (99%)

diff --git a/.github/workflows/test.yml b/.github/workflows/ci.yml
similarity index 99%
rename from .github/workflows/test.yml
rename to .github/workflows/ci.yml
index 1b655e27d..cc34579dd 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/ci.yml
@@ -1,4 +1,4 @@
-name: "Test"
+name: "CI"
 
 on:
   pull_request:

From 2267c773f0b36861c13915b518f62376a23b6f46 Mon Sep 17 00:00:00 2001
From: Rok Garbas <rok@garbas.si>
Date: Tue, 21 Dec 2021 22:42:47 +0100
Subject: [PATCH 388/567] Push docker image (only x86_64-linux right now) to
 hub.docker.com

---
 .github/workflows/ci.yml | 30 ++++++++++++++++++++++++++++++
 flake.nix                |  4 ++--
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index cc34579dd..4ae182cf1 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -74,3 +74,33 @@ jobs:
         install_url: '${{needs.installer.outputs.installerURL}}'
         install_options: "--tarball-url-prefix https://${{ env.CACHIX_NAME }}.cachix.org/serve"
     - run: nix-instantiate -E 'builtins.currentTime' --eval
+
+  docker_push_image:
+    needs: [check_cachix, tests]
+    if: >-
+      github.event_name == 'push' &&
+      github.ref_name == 'master' &&
+      needs.check_cachix.outputs.secret == 'true'
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2.4.0
+      with:
+        fetch-depth: 0
+    - uses: cachix/install-nix-action@v16
+    - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
+    - run: echo NIX_VERSION="$(nix-instantiate --eval -E '(import ./default.nix).defaultPackage.${builtins.currentSystem}.version' | tr -d \")" >> $GITHUB_ENV
+    - uses: cachix/cachix-action@v10
+      if: needs.check_cachix.outputs.secret == 'true'
+      with:
+        name: '${{ env.CACHIX_NAME }}'
+        signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
+        authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
+    - run: nix-build -A checks.$(nix-instantiate --eval -E 'builtins.currentSystem' --json).dockerImage
+    - run: docker load -i ./result/image.tar.gz
+    - run: docker tag nix:$NIX_VERSION nixos/nix:$NIX_VERSION
+    - name: Login to Docker Hub
+      uses: docker/login-action@v1
+      with:
+        username: ${{ secrets.DOCKERHUB_USERNAME }}
+        password: ${{ secrets.DOCKERHUB_TOKEN }}
+    - run: docker push nixos/nix:$NIX_VERSION
diff --git a/flake.nix b/flake.nix
index f4fae2a00..a96aed490 100644
--- a/flake.nix
+++ b/flake.nix
@@ -547,9 +547,9 @@
         binaryTarball = self.hydraJobs.binaryTarball.${system};
         perlBindings = self.hydraJobs.perlBindings.${system};
         installTests = self.hydraJobs.installTests.${system};
-      } // (if system == "x86_64-linux" then {
+      } // (nixpkgs.lib.optionalAttrs (builtins.elem system linux64BitSystems)) {
         dockerImage = self.hydraJobs.dockerImage.${system};
-      } else {}));
+      });
 
       packages = forAllSystems (system: {
         inherit (nixpkgsFor.${system}) nix;

From 5838354d342f1cdd09da7099e86123b36ecec409 Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Mon, 27 Dec 2021 02:04:49 +0100
Subject: [PATCH 389/567] optimize ExprConcatStrings::eval
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

constructing an ostringstream for non-string concats (like integer addition) is
a small constant cost that we can avoid. for string concats we can keep all the
string temporaries we get from coerceToString and concatenate them in one go,
which saves a lot of intermediate temporaries and copies in ostringstream. we
can also avoid copying the concatenated string again by directly allocating it
in GC memory and moving ownership of the concatenated string into the target
value.

saves about 2% on system eval.

before:

  Benchmark 1: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
    Time (mean ± σ):      2.837 s ±  0.031 s    [User: 2.562 s, System: 0.191 s]
    Range (min … max):    2.796 s …  2.892 s    20 runs

after:

  Benchmark 1: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
    Time (mean ± σ):      2.790 s ±  0.035 s    [User: 2.532 s, System: 0.187 s]
    Range (min … max):    2.722 s …  2.836 s    20 runs
---
 src/libexpr/eval.cc  | 75 ++++++++++++++++++++++++++++++++++++--------
 src/libexpr/value.hh |  2 ++
 2 files changed, 64 insertions(+), 13 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 81aa86641..61bccd6e2 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -36,6 +36,19 @@
 namespace nix {
 
 
+static char * allocString(size_t size)
+{
+    char * t;
+#if HAVE_BOEHMGC
+    t = (char *) GC_MALLOC_ATOMIC(size);
+#else
+    t = malloc(size);
+#endif
+    if (!t) throw std::bad_alloc();
+    return t;
+}
+
+
 static char * dupString(const char * s)
 {
     char * t;
@@ -771,17 +784,28 @@ void Value::mkString(std::string_view s)
 }
 
 
+static void copyContextToValue(Value & v, const PathSet & context)
+{
+    if (!context.empty()) {
+        size_t n = 0;
+        v.string.context = (const char * *)
+            allocBytes((context.size() + 1) * sizeof(char *));
+        for (auto & i : context)
+            v.string.context[n++] = dupString(i.c_str());
+        v.string.context[n] = 0;
+    }
+}
+
 void Value::mkString(std::string_view s, const PathSet & context)
 {
     mkString(s);
-    if (!context.empty()) {
-        size_t n = 0;
-        string.context = (const char * *)
-            allocBytes((context.size() + 1) * sizeof(char *));
-        for (auto & i : context)
-            string.context[n++] = dupString(i.c_str());
-        string.context[n] = 0;
-    }
+    copyContextToValue(*this, context);
+}
+
+void Value::mkStringMove(const char * s, const PathSet & context)
+{
+    mkString(s);
+    copyContextToValue(*this, context);
 }
 
 
@@ -1660,13 +1684,34 @@ void EvalState::concatLists(Value & v, size_t nrLists, Value * * lists, const Po
 void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
 {
     PathSet context;
-    std::ostringstream s;
+    std::vector<std::string> s;
+    size_t sSize = 0;
     NixInt n = 0;
     NixFloat nf = 0;
 
     bool first = !forceString;
     ValueType firstType = nString;
 
+    const auto str = [&] {
+        std::string result;
+        result.reserve(sSize);
+        for (const auto & part : s) result += part;
+        return result;
+    };
+    /* c_str() is not str().c_str() because we want to create a string
+       Value. allocating a GC'd string directly and moving it into a
+       Value lets us avoid an allocation and copy. */
+    const auto c_str = [&] {
+        char * result = allocString(sSize + 1);
+        char * tmp = result;
+        for (const auto & part : s) {
+            memcpy(tmp, part.c_str(), part.size());
+            tmp += part.size();
+        }
+        *tmp = 0;
+        return result;
+    };
+
     for (auto & [i_pos, i] : *es) {
         Value vTmp;
         i->eval(state, env, vTmp);
@@ -1696,11 +1741,15 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
                 nf += vTmp.fpoint;
             } else
                 throwEvalError(i_pos, "cannot add %1% to a float", showType(vTmp));
-        } else
+        } else {
+            if (s.empty()) s.reserve(es->size());
             /* skip canonization of first path, which would only be not
             canonized in the first place if it's coming from a ./${foo} type
             path */
-            s << state.coerceToString(i_pos, vTmp, context, false, firstType == nString, !first);
+            s.emplace_back(
+                state.coerceToString(i_pos, vTmp, context, false, firstType == nString, !first));
+            sSize += s.back().size();
+        }
 
         first = false;
     }
@@ -1712,9 +1761,9 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
     else if (firstType == nPath) {
         if (!context.empty())
             throwEvalError(pos, "a string that refers to a store path cannot be appended to a path");
-        v.mkPath(canonPath(s.str()));
+        v.mkPath(canonPath(str()));
     } else
-        v.mkString(s.str(), context);
+        v.mkStringMove(c_str(), context);
 }
 
 
diff --git a/src/libexpr/value.hh b/src/libexpr/value.hh
index 7d007ebdc..1896c7563 100644
--- a/src/libexpr/value.hh
+++ b/src/libexpr/value.hh
@@ -241,6 +241,8 @@ public:
 
     void mkString(std::string_view s, const PathSet & context);
 
+    void mkStringMove(const char * s, const PathSet & context);
+
     inline void mkString(const Symbol & s)
     {
         mkString(((const std::string &) s).c_str());

From 73fcc40fa4382e2325be601bd85ebe258420e1ce Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Fri, 31 Dec 2021 03:16:59 +0100
Subject: [PATCH 390/567] use boost::lexical_cast for string2*

this avoids one copy from `s` into `str`, and possibly another copy needed to
construct `s` at the call site. lexical_cast is also more efficient in general.
---
 src/libutil/util.hh | 30 ++++++++++++++++--------------
 1 file changed, 16 insertions(+), 14 deletions(-)

diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index d08f42826..7da60b310 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -11,6 +11,8 @@
 #include <unistd.h>
 #include <signal.h>
 
+#include <boost/lexical_cast.hpp>
+
 #include <atomic>
 #include <functional>
 #include <map>
@@ -417,21 +419,21 @@ bool statusOk(int status);
 
 /* Parse a string into an integer. */
 template<class N>
-std::optional<N> string2Int(const std::string & s)
+std::optional<N> string2Int(const std::string_view s)
 {
     if (s.substr(0, 1) == "-" && !std::numeric_limits<N>::is_signed)
         return std::nullopt;
-    std::istringstream str(s);
-    N n;
-    str >> n;
-    if (str && str.get() == EOF) return n;
-    return std::nullopt;
+    try {
+        return boost::lexical_cast<N>(s.data(), s.size());
+    } catch (const boost::bad_lexical_cast &) {
+        return std::nullopt;
+    }
 }
 
 /* Like string2Int(), but support an optional suffix 'K', 'M', 'G' or
    'T' denoting a binary unit prefix. */
 template<class N>
-N string2IntWithUnitPrefix(std::string s)
+N string2IntWithUnitPrefix(std::string_view s)
 {
     N multiplier = 1;
     if (!s.empty()) {
@@ -442,7 +444,7 @@ N string2IntWithUnitPrefix(std::string s)
             else if (u == 'G') multiplier = 1ULL << 30;
             else if (u == 'T') multiplier = 1ULL << 40;
             else throw UsageError("invalid unit specifier '%1%'", u);
-            s.resize(s.size() - 1);
+            s.remove_suffix(1);
         }
     }
     if (auto n = string2Int<N>(s))
@@ -452,13 +454,13 @@ N string2IntWithUnitPrefix(std::string s)
 
 /* Parse a string into a float. */
 template<class N>
-std::optional<N> string2Float(const string & s)
+std::optional<N> string2Float(const std::string_view s)
 {
-    std::istringstream str(s);
-    N n;
-    str >> n;
-    if (str && str.get() == EOF) return n;
-    return std::nullopt;
+    try {
+        return boost::lexical_cast<N>(s.data(), s.size());
+    } catch (const boost::bad_lexical_cast &) {
+        return std::nullopt;
+    }
 }
 
 

From a51c45720471c55090b45962c59e117d547cc935 Mon Sep 17 00:00:00 2001
From: Profpatsch <mail@profpatsch.de>
Date: Wed, 12 Jan 2022 12:19:47 +0100
Subject: [PATCH 391/567] Release Notes 2.4: add `--indirect` no-op change

Since
https://github.com/NixOS/nix/commit/00d25e84577659ccf0bc360c61c47b6cd25d1c26
which was first included in nix 2.4.

It is a backwards-compatible change since the flag will just be
ignored.
---
 doc/manual/src/release-notes/rl-2.4.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/doc/manual/src/release-notes/rl-2.4.md b/doc/manual/src/release-notes/rl-2.4.md
index 0f632f100..8b566fc7b 100644
--- a/doc/manual/src/release-notes/rl-2.4.md
+++ b/doc/manual/src/release-notes/rl-2.4.md
@@ -276,6 +276,9 @@ more than 2800 commits from 195 contributors since release 2.3.
 
 * Plugins can now register `nix` subcommands.
 
+* The `--indirect` flag to `nix-store --add-root` has become a no-op.
+  `--add-root` will always generate indirect GC roots from now on.
+
 ## Incompatible changes
 
 * The `nix` command is now marked as an experimental feature. This

From 44c92a1667ce829518178a77a9de0a53609d284f Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Wed, 12 Jan 2022 16:02:29 +0100
Subject: [PATCH 392/567] use more string_view in utils
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

there's a couple places that can be easily converted from using strings to using
string_views instead. gives a slight (~1%) boost to system eval.

 # before

  nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
    Time (mean ± σ):      2.946 s ±  0.026 s    [User: 2.655 s, System: 0.209 s]
    Range (min … max):    2.905 s …  2.995 s    20 runs

 # after

    Time (mean ± σ):      2.928 s ±  0.024 s    [User: 2.638 s, System: 0.211 s]
    Range (min … max):    2.893 s …  2.970 s    20 runs
---
 src/libutil/types.hh |  1 +
 src/libutil/util.cc  | 43 +++++++++++++++++++++++--------------------
 src/libutil/util.hh  | 18 +++++++++++++++---
 3 files changed, 39 insertions(+), 23 deletions(-)

diff --git a/src/libutil/types.hh b/src/libutil/types.hh
index 9c85fef62..8f72c926f 100644
--- a/src/libutil/types.hh
+++ b/src/libutil/types.hh
@@ -22,6 +22,7 @@ typedef std::map<string, string> StringMap;
 /* Paths are just strings. */
 
 typedef string Path;
+typedef std::string_view PathView;
 typedef list<Path> Paths;
 typedef set<Path> PathSet;
 
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 9edd69c64..47876709e 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -106,16 +106,16 @@ Path absPath(Path path, std::optional<Path> dir, bool resolveSymlinks)
 }
 
 
-Path canonPath(const Path & path, bool resolveSymlinks)
+Path canonPath(PathView path, bool resolveSymlinks)
 {
     assert(path != "");
 
     string s;
+    s.reserve(256);
 
     if (path[0] != '/')
         throw Error("not an absolute path: '%1%'", path);
 
-    string::const_iterator i = path.begin(), end = path.end();
     string temp;
 
     /* Count the number of times we follow a symlink and stop at some
@@ -125,33 +125,37 @@ Path canonPath(const Path & path, bool resolveSymlinks)
     while (1) {
 
         /* Skip slashes. */
-        while (i != end && *i == '/') i++;
-        if (i == end) break;
+        while (!path.empty() && path[0] == '/') path.remove_prefix(1);
+        if (path.empty()) break;
 
         /* Ignore `.'. */
-        if (*i == '.' && (i + 1 == end || i[1] == '/'))
-            i++;
+        if (path == "." || path.substr(0, 2) == "./")
+            path.remove_prefix(1);
 
         /* If `..', delete the last component. */
-        else if (*i == '.' && i + 1 < end && i[1] == '.' &&
-            (i + 2 == end || i[2] == '/'))
+        else if (path == ".." || path.substr(0, 3) == "../")
         {
             if (!s.empty()) s.erase(s.rfind('/'));
-            i += 2;
+            path.remove_prefix(2);
         }
 
         /* Normal component; copy it. */
         else {
             s += '/';
-            while (i != end && *i != '/') s += *i++;
+            if (const auto slash = path.find('/'); slash == string::npos) {
+                s += path;
+                path = {};
+            } else {
+                s += path.substr(0, slash);
+                path = path.substr(slash + 1);
+            }
 
             /* If s points to a symlink, resolve it and continue from there */
             if (resolveSymlinks && isLink(s)) {
                 if (++followCount >= maxFollow)
                     throw Error("infinite symlink recursion in path '%1%'", path);
-                temp = readLink(s) + string(i, end);
-                i = temp.begin();
-                end = temp.end();
+                temp = concatStrings(readLink(s), path);
+                path = temp;
                 if (!temp.empty() && temp[0] == '/') {
                     s.clear();  /* restart for symlinks pointing to absolute path */
                 } else {
@@ -164,7 +168,7 @@ Path canonPath(const Path & path, bool resolveSymlinks)
         }
     }
 
-    return s.empty() ? "/" : s;
+    return s.empty() ? "/" : std::move(s);
 }
 
 
@@ -1229,23 +1233,22 @@ void _interrupted()
 //////////////////////////////////////////////////////////////////////
 
 
-template<class C> C tokenizeString(std::string_view s, const string & separators)
+template<class C> C tokenizeString(std::string_view s, std::string_view separators)
 {
     C result;
     string::size_type pos = s.find_first_not_of(separators, 0);
     while (pos != string::npos) {
         string::size_type end = s.find_first_of(separators, pos + 1);
         if (end == string::npos) end = s.size();
-        string token(s, pos, end - pos);
-        result.insert(result.end(), token);
+        result.insert(result.end(), string(s, pos, end - pos));
         pos = s.find_first_not_of(separators, end);
     }
     return result;
 }
 
-template Strings tokenizeString(std::string_view s, const string & separators);
-template StringSet tokenizeString(std::string_view s, const string & separators);
-template vector<string> tokenizeString(std::string_view s, const string & separators);
+template Strings tokenizeString(std::string_view s, std::string_view separators);
+template StringSet tokenizeString(std::string_view s, std::string_view separators);
+template vector<string> tokenizeString(std::string_view s, std::string_view separators);
 
 
 string chomp(std::string_view s)
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index c900033f8..369c44f78 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -56,7 +56,7 @@ Path absPath(Path path,
    double or trailing slashes.  Optionally resolves all symlink
    components such that each component of the resulting path is *not*
    a symbolic link. */
-Path canonPath(const Path & path, bool resolveSymlinks = false);
+Path canonPath(PathView path, bool resolveSymlinks = false);
 
 /* Return the directory part of the given canonical path, i.e.,
    everything before the final `/'.  If the path is the root or an
@@ -368,15 +368,19 @@ MakeError(FormatError, Error);
 
 
 /* String tokenizer. */
-template<class C> C tokenizeString(std::string_view s, const string & separators = " \t\n\r");
+template<class C> C tokenizeString(std::string_view s, std::string_view separators = " \t\n\r");
 
 
 /* Concatenate the given strings with a separator between the
    elements. */
 template<class C>
-string concatStringsSep(const string & sep, const C & ss)
+string concatStringsSep(const std::string_view sep, const C & ss)
 {
+    size_t size = 0;
+    // need a cast to string_view since this is also called with Symbols
+    for (const auto & s : ss) size += sep.size() + std::string_view(s).size();
     string s;
+    s.reserve(size);
     for (auto & i : ss) {
         if (s.size() != 0) s += sep;
         s += i;
@@ -384,6 +388,14 @@ string concatStringsSep(const string & sep, const C & ss)
     return s;
 }
 
+template<class ... Parts>
+auto concatStrings(Parts && ... parts)
+    -> std::enable_if_t<(... && std::is_convertible_v<Parts, std::string_view>), string>
+{
+    std::string_view views[sizeof...(parts)] = { parts... };
+    return concatStringsSep({}, views);
+}
+
 
 /* Add quotes around a collection of strings. */
 template<class C> Strings quoteStrings(const C & c)

From 1bebb1095a122d4741c4ed9cd9cb19f08753872b Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Wed, 12 Jan 2022 18:08:48 +0100
Subject: [PATCH 393/567] cache more often-used symbols for primops

there's a few symbols in primops we can create once and pick them out of
EvalState afterwards instead of creating them every time we need them. this
gives almost 1% speedup to an uncached nix search.
---
 src/libexpr/eval.cc    |  5 +++++
 src/libexpr/eval.hh    |  3 ++-
 src/libexpr/primops.cc | 21 ++++++++++-----------
 3 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 61bccd6e2..94ffab175 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -425,6 +425,11 @@ EvalState::EvalState(
     , sDescription(symbols.create("description"))
     , sSelf(symbols.create("self"))
     , sEpsilon(symbols.create(""))
+    , sStartSet(symbols.create("startSet"))
+    , sOperator(symbols.create("operator"))
+    , sKey(symbols.create("key"))
+    , sPath(symbols.create("path"))
+    , sPrefix(symbols.create("prefix"))
     , repair(NoRepair)
     , emptyBindings(0)
     , store(store)
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 89814785e..348a1b291 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -80,7 +80,8 @@ public:
         sContentAddressed,
         sOutputHash, sOutputHashAlgo, sOutputHashMode,
         sRecurseForDerivations,
-        sDescription, sSelf, sEpsilon;
+        sDescription, sSelf, sEpsilon, sStartSet, sOperator, sKey, sPath,
+        sPrefix;
     Symbol sDerivationNix;
 
     /* If set, force copying files to the Nix store even if they
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 1d2a7d5d2..7b0e6e7df 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -592,16 +592,16 @@ typedef list<Value *> ValueList;
 
 static Bindings::iterator getAttr(
     EvalState & state,
-    string funcName,
-    string attrName,
+    std::string_view funcName,
+    Symbol attrSym,
     Bindings * attrSet,
     const Pos & pos)
 {
-    Bindings::iterator value = attrSet->find(state.symbols.create(attrName));
+    Bindings::iterator value = attrSet->find(attrSym);
     if (value == attrSet->end()) {
         hintformat errorMsg = hintfmt(
             "attribute '%s' missing for call to '%s'",
-            attrName,
+            attrSym,
             funcName
         );
 
@@ -635,7 +635,7 @@ static void prim_genericClosure(EvalState & state, const Pos & pos, Value * * ar
     Bindings::iterator startSet = getAttr(
         state,
         "genericClosure",
-        "startSet",
+        state.sStartSet,
         args[0]->attrs,
         pos
     );
@@ -650,7 +650,7 @@ static void prim_genericClosure(EvalState & state, const Pos & pos, Value * * ar
     Bindings::iterator op = getAttr(
         state,
         "genericClosure",
-        "operator",
+        state.sOperator,
         args[0]->attrs,
         pos
     );
@@ -672,7 +672,7 @@ static void prim_genericClosure(EvalState & state, const Pos & pos, Value * * ar
         state.forceAttrs(*e, pos);
 
         Bindings::iterator key =
-            e->attrs->find(state.symbols.create("key"));
+            e->attrs->find(state.sKey);
         if (key == e->attrs->end())
             throw EvalError({
                 .msg = hintfmt("attribute 'key' required"),
@@ -1498,14 +1498,14 @@ static void prim_findFile(EvalState & state, const Pos & pos, Value * * args, Va
         state.forceAttrs(*v2, pos);
 
         string prefix;
-        Bindings::iterator i = v2->attrs->find(state.symbols.create("prefix"));
+        Bindings::iterator i = v2->attrs->find(state.sPrefix);
         if (i != v2->attrs->end())
             prefix = state.forceStringNoCtx(*i->value, pos);
 
         i = getAttr(
             state,
             "findFile",
-            "path",
+            state.sPath,
             v2->attrs,
             pos
         );
@@ -2184,11 +2184,10 @@ void prim_getAttr(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     string attr = state.forceStringNoCtx(*args[0], pos);
     state.forceAttrs(*args[1], pos);
-    // !!! Should we create a symbol here or just do a lookup?
     Bindings::iterator i = getAttr(
         state,
         "getAttr",
-        attr,
+        state.symbols.create(attr),
         args[1]->attrs,
         pos
     );

From ef45787aae1c91dffce1e95db3d46740b0165319 Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Wed, 12 Jan 2022 18:17:59 +0100
Subject: [PATCH 394/567] avoid string copies in attrNames sort comparison

symbols can also be cast to string_view, which compares the same but doesn't
require a copy of both symbol names on every comparison.
---
 src/libexpr/primops.cc | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 7b0e6e7df..365595c92 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -2163,7 +2163,10 @@ static void prim_attrValues(EvalState & state, const Pos & pos, Value * * args,
         v.listElems()[n++] = (Value *) &i;
 
     std::sort(v.listElems(), v.listElems() + n,
-        [](Value * v1, Value * v2) { return (string) ((Attr *) v1)->name < (string) ((Attr *) v2)->name; });
+        [](Value * v1, Value * v2) {
+            std::string_view s1 = ((Attr *) v1)->name, s2 = ((Attr *) v2)->name;
+            return s1 < s2;
+        });
 
     for (unsigned int i = 0; i < n; ++i)
         v.listElems()[i] = ((Attr *) v.listElems()[i])->value;

From 6401e443a441f58f48e2cbab5286b89ec162835a Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Sun, 2 Jan 2022 00:30:57 +0100
Subject: [PATCH 395/567] move strings in derivationStrict

the temporary will be discarded anyway, so we can move out of it and save many
small allocations and copies.
---
 src/libexpr/primops.cc | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 365595c92..003e588a4 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1079,10 +1079,10 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
                 } else {
                     auto s = state.coerceToString(*i->pos, *i->value, context, true);
                     drv.env.emplace(key, s);
-                    if (i->name == state.sBuilder) drv.builder = s;
-                    else if (i->name == state.sSystem) drv.platform = s;
-                    else if (i->name == state.sOutputHash) outputHash = s;
-                    else if (i->name == state.sOutputHashAlgo) outputHashAlgo = s;
+                    if (i->name == state.sBuilder) drv.builder = std::move(s);
+                    else if (i->name == state.sSystem) drv.platform = std::move(s);
+                    else if (i->name == state.sOutputHash) outputHash = std::move(s);
+                    else if (i->name == state.sOutputHashAlgo) outputHashAlgo = std::move(s);
                     else if (i->name == state.sOutputHashMode) handleHashMode(s);
                     else if (i->name == state.sOutputs)
                         handleOutputs(tokenizeString<Strings>(s));

From 5e9653c3701eddf86312b534d7e8340c0857e84b Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 13 Jan 2022 14:33:09 +0100
Subject: [PATCH 396/567] Tweak

---
 doc/manual/src/expressions/language-constructs.md | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/doc/manual/src/expressions/language-constructs.md b/doc/manual/src/expressions/language-constructs.md
index c406b6910..1c01f2cc7 100644
--- a/doc/manual/src/expressions/language-constructs.md
+++ b/doc/manual/src/expressions/language-constructs.md
@@ -276,7 +276,6 @@ stdenv.mkDerivation {
   ...
 }
 ```
-("->" is a boolean operation known as [logical implication](https://en.wikipedia.org/wiki/Truth_table#Logical_implication))
 
 The points of interest are:
 
@@ -285,6 +284,10 @@ The points of interest are:
     function is called with the `localServer` argument set to `true` but
     the `db4` argument set to `null`, then the evaluation fails.
 
+    Note that `->` is the [logical
+    implication](https://en.wikipedia.org/wiki/Truth_table#Logical_implication)
+    Boolean operation.
+
 2.  This is a more subtle condition: if Subversion is built with Apache
     (`httpServer`) support, then the Expat library (an XML library) used
     by Subversion should be same as the one used by Apache. This is

From 61a9d16d5c1d4088981f7d0ca08655f9155cc015 Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Tue, 21 Dec 2021 09:17:31 +0100
Subject: [PATCH 397/567] don't strdup tokens in the lexer
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

every stringy token the lexer returns is turned into a Symbol and not
used further, so we don't have to strdup. using a string_view is
sufficient, but due to limitations of the current parser we have to use
a POD type that holds the same information.

gives ~2% on system build, 6% on search, 8% on parsing alone

 # before

Benchmark 1: nix search --offline nixpkgs hello
  Time (mean ± σ):     610.6 ms ±   2.4 ms    [User: 602.5 ms, System: 7.8 ms]
  Range (min … max):   606.6 ms … 617.3 ms    50 runs

Benchmark 2: nix eval -f hackage-packages.nix
  Time (mean ± σ):     430.1 ms ±   1.4 ms    [User: 393.1 ms, System: 36.7 ms]
  Range (min … max):   428.2 ms … 434.2 ms    50 runs

Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
  Time (mean ± σ):      3.032 s ±  0.005 s    [User: 2.808 s, System: 0.223 s]
  Range (min … max):    3.023 s …  3.041 s    50 runs

 # after

Benchmark 1: nix search --offline nixpkgs hello
  Time (mean ± σ):     574.7 ms ±   2.8 ms    [User: 566.3 ms, System: 8.0 ms]
  Range (min … max):   569.2 ms … 580.7 ms    50 runs

Benchmark 2: nix eval -f hackage-packages.nix
  Time (mean ± σ):     394.4 ms ±   0.8 ms    [User: 361.8 ms, System: 32.3 ms]
  Range (min … max):   392.7 ms … 395.7 ms    50 runs

Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
  Time (mean ± σ):      2.976 s ±  0.005 s    [User: 2.757 s, System: 0.218 s]
  Range (min … max):    2.966 s …  2.990 s    50 runs
---
 src/libexpr/lexer.l  | 14 +++++++-------
 src/libexpr/parser.y | 25 ++++++++++++++++---------
 2 files changed, 23 insertions(+), 16 deletions(-)

diff --git a/src/libexpr/lexer.l b/src/libexpr/lexer.l
index c18877e29..70e99d2d2 100644
--- a/src/libexpr/lexer.l
+++ b/src/libexpr/lexer.l
@@ -139,7 +139,7 @@ or          { return OR_KW; }
 \/\/        { return UPDATE; }
 \+\+        { return CONCAT; }
 
-{ID}        { yylval->id = strdup(yytext); return ID; }
+{ID}        { yylval->id = {yytext, (size_t) yyleng}; return ID; }
 {INT}       { errno = 0;
               try {
                   yylval->n = boost::lexical_cast<int64_t>(yytext);
@@ -221,14 +221,14 @@ or          { return OR_KW; }
 <PATH_START>{PATH_SEG} {
   POP_STATE();
   PUSH_STATE(INPATH_SLASH);
-  yylval->path = strdup(yytext);
+  yylval->path = {yytext, (size_t) yyleng};
   return PATH;
 }
 
 <PATH_START>{HPATH_START} {
   POP_STATE();
   PUSH_STATE(INPATH_SLASH);
-  yylval->path = strdup(yytext);
+  yylval->path = {yytext, (size_t) yyleng};
   return HPATH;
 }
 
@@ -237,7 +237,7 @@ or          { return OR_KW; }
     PUSH_STATE(INPATH_SLASH);
   else
     PUSH_STATE(INPATH);
-  yylval->path = strdup(yytext);
+  yylval->path = {yytext, (size_t) yyleng};
   return PATH;
 }
 {HPATH} {
@@ -245,7 +245,7 @@ or          { return OR_KW; }
     PUSH_STATE(INPATH_SLASH);
   else
     PUSH_STATE(INPATH);
-  yylval->path = strdup(yytext);
+  yylval->path = {yytext, (size_t) yyleng};
   return HPATH;
 }
 
@@ -280,8 +280,8 @@ or          { return OR_KW; }
   throw ParseError("path has a trailing slash");
 }
 
-{SPATH}     { yylval->path = strdup(yytext); return SPATH; }
-{URI}       { yylval->uri = strdup(yytext); return URI; }
+{SPATH}     { yylval->path = {yytext, (size_t) yyleng}; return SPATH; }
+{URI}       { yylval->uri = {yytext, (size_t) yyleng}; return URI; }
 
 [ \t\r\n]+    /* eat up whitespace */
 \#[^\r\n]*    /* single-line comments */
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index f8aaea582..049a149cc 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -273,9 +273,16 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * err
   nix::Formal * formal;
   nix::NixInt n;
   nix::NixFloat nf;
-  const char * id; // !!! -> Symbol
-  char * path;
-  char * uri;
+  // using C a struct allows us to avoid having to define the special
+  // members that using string_view here would implicitly delete.
+  struct StringToken {
+    const char * p;
+    size_t l;
+    operator std::string_view() const { return {p, l}; }
+  };
+  StringToken id; // !!! -> Symbol
+  StringToken path;
+  StringToken uri;
   std::vector<nix::AttrName> * attrNames;
   std::vector<std::pair<nix::Pos, nix::Expr *> > * string_parts;
 }
@@ -397,7 +404,7 @@ expr_select
 
 expr_simple
   : ID {
-      if (strcmp($1, "__curPos") == 0)
+      if (strncmp($1.p, "__curPos", $1.l) == 0)
           $$ = new ExprPos(CUR_POS);
       else
           $$ = new ExprVar(CUR_POS, data->symbols.create($1));
@@ -414,7 +421,7 @@ expr_simple
       $$ = new ExprConcatStrings(CUR_POS, false, $2);
   }
   | SPATH {
-      string path($1 + 1, strlen($1) - 2);
+      string path($1.p + 1, $1.l - 2);
       $$ = new ExprCall(CUR_POS,
           new ExprVar(data->symbols.create("__findFile")),
           {new ExprVar(data->symbols.create("__nixPath")),
@@ -460,14 +467,14 @@ string_parts_interpolated
 
 path_start
   : PATH {
-    Path path(absPath($1, data->basePath));
+    Path path(absPath({$1.p, $1.l}, data->basePath));
     /* add back in the trailing '/' to the first segment */
-    if ($1[strlen($1)-1] == '/' && strlen($1) > 1)
+    if ($1.p[$1.l-1] == '/' && $1.l > 1)
       path += "/";
     $$ = new ExprPath(path);
   }
   | HPATH {
-    Path path(getHome() + string($1 + 1));
+    Path path(getHome() + string($1.p + 1, $1.l - 1));
     $$ = new ExprPath(path);
   }
   ;
@@ -543,7 +550,7 @@ attrpath
 
 attr
   : ID { $$ = $1; }
-  | OR_KW { $$ = "or"; }
+  | OR_KW { $$ = {"or", 2}; }
   ;
 
 string_attr

From eee0bcee227f6a1b46116efc8915545feb5a2e86 Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Mon, 20 Dec 2021 11:29:14 +0100
Subject: [PATCH 398/567] avoid allocations in SymbolTable::create
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

speeds up parsing by ~3%, system builds by a bit more than 1%

 # before

Benchmark 1: nix search --offline nixpkgs hello
  Time (mean ± σ):     574.7 ms ±   2.8 ms    [User: 566.3 ms, System: 8.0 ms]
  Range (min … max):   569.2 ms … 580.7 ms    50 runs

Benchmark 2: nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
  Time (mean ± σ):     394.4 ms ±   0.8 ms    [User: 361.8 ms, System: 32.3 ms]
  Range (min … max):   392.7 ms … 395.7 ms    50 runs

Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
  Time (mean ± σ):      2.976 s ±  0.005 s    [User: 2.757 s, System: 0.218 s]
  Range (min … max):    2.966 s …  2.990 s    50 runs

 # after

Benchmark 1: nix search --offline nixpkgs hello
  Time (mean ± σ):     572.4 ms ±   2.3 ms    [User: 563.4 ms, System: 8.6 ms]
  Range (min … max):   566.9 ms … 579.1 ms    50 runs

Benchmark 2: nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
  Time (mean ± σ):     381.7 ms ±   1.0 ms    [User: 348.3 ms, System: 33.1 ms]
  Range (min … max):   380.2 ms … 387.7 ms    50 runs

Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
  Time (mean ± σ):      2.936 s ±  0.005 s    [User: 2.715 s, System: 0.221 s]
  Range (min … max):    2.923 s …  2.946 s    50 runs
---
 src/libexpr/nixexpr.cc      |  2 +-
 src/libexpr/symbol-table.hh | 21 ++++++++++++++-------
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc
index a75357871..640c44c01 100644
--- a/src/libexpr/nixexpr.cc
+++ b/src/libexpr/nixexpr.cc
@@ -473,7 +473,7 @@ string ExprLambda::showNamePos() const
 size_t SymbolTable::totalSize() const
 {
     size_t n = 0;
-    for (auto & i : symbols)
+    for (auto & i : store)
         n += i.size();
     return n;
 }
diff --git a/src/libexpr/symbol-table.hh b/src/libexpr/symbol-table.hh
index 4eb6dac81..a090ebae5 100644
--- a/src/libexpr/symbol-table.hh
+++ b/src/libexpr/symbol-table.hh
@@ -1,7 +1,8 @@
 #pragma once
 
+#include <list>
 #include <map>
-#include <unordered_set>
+#include <unordered_map>
 
 #include "types.hh"
 
@@ -70,15 +71,21 @@ public:
 class SymbolTable
 {
 private:
-    typedef std::unordered_set<string> Symbols;
-    Symbols symbols;
+    std::unordered_map<std::string_view, Symbol> symbols;
+    std::list<string> store;
 
 public:
     Symbol create(std::string_view s)
     {
-        // FIXME: avoid allocation if 's' already exists in the symbol table.
-        std::pair<Symbols::iterator, bool> res = symbols.emplace(std::string(s));
-        return Symbol(&*res.first);
+        // Most symbols are looked up more than once, so we trade off insertion performance
+        // for lookup performance.
+        // TODO: could probably be done more efficiently with transparent Hash and Equals
+        // on the original implementation using unordered_set
+        auto it = symbols.find(s);
+        if (it != symbols.end()) return it->second;
+
+        const string & rawSym = store.emplace_back(s);
+        return symbols.emplace(rawSym, Symbol(&rawSym)).first->second;
     }
 
     size_t size() const
@@ -91,7 +98,7 @@ public:
     template<typename T>
     void dump(T callback)
     {
-        for (auto & s : symbols)
+        for (auto & s : store)
             callback(s);
     }
 };

From 34e3bd10e3891afc965a7fb8fdcaacbdc900b2d5 Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Tue, 21 Dec 2021 13:56:57 +0100
Subject: [PATCH 399/567] avoid copies of parser input data
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

when given a string yacc will copy the entire input to a newly allocated
location so that it can add a second terminating NUL byte. since the
parser is a very internal thing to EvalState we can ensure that having
two terminating NUL bytes is always possible without copying, and have
the parser itself merely check that the expected NULs are present.

 # before

Benchmark 1: nix search --offline nixpkgs hello
  Time (mean ± σ):     572.4 ms ±   2.3 ms    [User: 563.4 ms, System: 8.6 ms]
  Range (min … max):   566.9 ms … 579.1 ms    50 runs

Benchmark 2: nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
  Time (mean ± σ):     381.7 ms ±   1.0 ms    [User: 348.3 ms, System: 33.1 ms]
  Range (min … max):   380.2 ms … 387.7 ms    50 runs

Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
  Time (mean ± σ):      2.936 s ±  0.005 s    [User: 2.715 s, System: 0.221 s]
  Range (min … max):    2.923 s …  2.946 s    50 runs

 # after

Benchmark 1: nix search --offline nixpkgs hello
  Time (mean ± σ):     571.7 ms ±   2.4 ms    [User: 563.3 ms, System: 8.0 ms]
  Range (min … max):   566.7 ms … 579.7 ms    50 runs

Benchmark 2: nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
  Time (mean ± σ):     376.6 ms ±   1.0 ms    [User: 345.8 ms, System: 30.5 ms]
  Range (min … max):   374.5 ms … 379.1 ms    50 runs

Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
  Time (mean ± σ):      2.922 s ±  0.006 s    [User: 2.707 s, System: 0.215 s]
  Range (min … max):    2.906 s …  2.934 s    50 runs
---
 src/libexpr/eval.hh        |  6 +++---
 src/libexpr/parser.y       | 23 +++++++++++++++--------
 src/libexpr/primops.cc     |  9 ++++++---
 src/libutil/util.cc        |  4 +++-
 src/nix-build/nix-build.cc |  2 +-
 src/nix/repl.cc            |  2 +-
 6 files changed, 29 insertions(+), 17 deletions(-)

diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index cc63294c6..15925a6b4 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -181,8 +181,8 @@ public:
     Expr * parseExprFromFile(const Path & path, StaticEnv & staticEnv);
 
     /* Parse a Nix expression from the specified string. */
-    Expr * parseExprFromString(std::string_view s, const Path & basePath, StaticEnv & staticEnv);
-    Expr * parseExprFromString(std::string_view s, const Path & basePath);
+    Expr * parseExprFromString(std::string s, const Path & basePath, StaticEnv & staticEnv);
+    Expr * parseExprFromString(std::string s, const Path & basePath);
 
     Expr * parseStdin();
 
@@ -310,7 +310,7 @@ private:
     friend struct ExprAttrs;
     friend struct ExprLet;
 
-    Expr * parse(const char * text, FileOrigin origin, const Path & path,
+    Expr * parse(char * text, size_t length, FileOrigin origin, const Path & path,
         const Path & basePath, StaticEnv & staticEnv);
 
 public:
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 049a149cc..a3e713937 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -596,7 +596,7 @@ formal
 namespace nix {
 
 
-Expr * EvalState::parse(const char * text, FileOrigin origin,
+Expr * EvalState::parse(char * text, size_t length, FileOrigin origin,
     const Path & path, const Path & basePath, StaticEnv & staticEnv)
 {
     yyscan_t scanner;
@@ -616,7 +616,7 @@ Expr * EvalState::parse(const char * text, FileOrigin origin,
     data.basePath = basePath;
 
     yylex_init(&scanner);
-    yy_scan_string(text, scanner);
+    yy_scan_buffer(text, length, scanner);
     int res = yyparse(scanner, &data);
     yylex_destroy(scanner);
 
@@ -662,26 +662,33 @@ Expr * EvalState::parseExprFromFile(const Path & path)
 
 Expr * EvalState::parseExprFromFile(const Path & path, StaticEnv & staticEnv)
 {
-    return parse(readFile(path).c_str(), foFile, path, dirOf(path), staticEnv);
+    auto buffer = readFile(path);
+    // readFile should have left some extra space for terminators
+    buffer.append("\0\0", 2);
+    return parse(buffer.data(), buffer.size(), foFile, path, dirOf(path), staticEnv);
 }
 
 
-Expr * EvalState::parseExprFromString(std::string_view s, const Path & basePath, StaticEnv & staticEnv)
+Expr * EvalState::parseExprFromString(std::string s, const Path & basePath, StaticEnv & staticEnv)
 {
-    return parse(s.data(), foString, "", basePath, staticEnv);
+    s.append("\0\0", 2);
+    return parse(s.data(), s.size(), foString, "", basePath, staticEnv);
 }
 
 
-Expr * EvalState::parseExprFromString(std::string_view s, const Path & basePath)
+Expr * EvalState::parseExprFromString(std::string s, const Path & basePath)
 {
-    return parseExprFromString(s, basePath, staticBaseEnv);
+    return parseExprFromString(std::move(s), basePath, staticBaseEnv);
 }
 
 
 Expr * EvalState::parseStdin()
 {
     //Activity act(*logger, lvlTalkative, format("parsing standard input"));
-    return parse(drainFD(0).data(), foStdin, "", absPath("."), staticBaseEnv);
+    auto buffer = drainFD(0);
+    // drainFD should have left some extra space for terminators
+    buffer.append("\0\0", 2);
+    return parse(buffer.data(), buffer.size(), foStdin, "", absPath("."), staticBaseEnv);
 }
 
 
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 66af373d7..852317aa3 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -350,7 +350,7 @@ void prim_exec(EvalState & state, const Pos & pos, Value * * args, Value & v)
     auto output = runProgram(program, true, commandArgs);
     Expr * parsed;
     try {
-        parsed = state.parseExprFromString(output, pos.file);
+        parsed = state.parseExprFromString(std::move(output), pos.file);
     } catch (Error & e) {
         e.addTrace(pos, "While parsing the output from '%1%'", program);
         throw;
@@ -3800,9 +3800,12 @@ void EvalState::createBaseEnv()
 
     /* Note: we have to initialize the 'derivation' constant *after*
        building baseEnv/staticBaseEnv because it uses 'builtins'. */
-    eval(parse(
+    char code[] =
         #include "primops/derivation.nix.gen.hh"
-        , foFile, sDerivationNix, "/", staticBaseEnv), *vDerivation);
+        // the parser needs two NUL bytes as terminators; one of them
+        // is implied by being a C string.
+        "\0";
+    eval(parse(code, sizeof(code), foFile, sDerivationNix, "/", staticBaseEnv), *vDerivation);
 }
 
 
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 43fea1b1e..f15a617b0 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -669,7 +669,9 @@ void writeFull(int fd, std::string_view s, bool allowInterrupts)
 
 string drainFD(int fd, bool block, const size_t reserveSize)
 {
-    StringSink sink(reserveSize);
+    // the parser needs two extra bytes to append terminating characters, other users will
+    // not care very much about the extra memory.
+    StringSink sink(reserveSize + 2);
     drainFD(fd, sink, block);
     return std::move(*sink.s);
 }
diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index e2325c91f..b5d0f4813 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -296,7 +296,7 @@ static void main_nix_build(int argc, char * * argv)
     else
         for (auto i : left) {
             if (fromArgs)
-                exprs.push_back(state->parseExprFromString(i, absPath(".")));
+                exprs.push_back(state->parseExprFromString(std::move(i), absPath(".")));
             else {
                 auto absolute = i;
                 try {
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index f453343f3..c8bb5a90f 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -683,7 +683,7 @@ void NixRepl::addVarToScope(const Symbol & name, Value & v)
 
 Expr * NixRepl::parseString(string s)
 {
-    Expr * e = state->parseExprFromString(s, curDir, staticEnv);
+    Expr * e = state->parseExprFromString(std::move(s), curDir, staticEnv);
     return e;
 }
 

From 72f42093e711db1ab43c920688bb5e59df33935d Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Tue, 21 Dec 2021 10:28:05 +0100
Subject: [PATCH 400/567] optimize unescapeStr
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

mainly to avoid an allocation and a copy of a string that can be
modified in place (ever since EvalState holds on to the buffer, not the
generated parser itself).

 # before

Benchmark 1: nix search --offline nixpkgs hello
  Time (mean ± σ):     571.7 ms ±   2.4 ms    [User: 563.3 ms, System: 8.0 ms]
  Range (min … max):   566.7 ms … 579.7 ms    50 runs

Benchmark 2: nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
  Time (mean ± σ):     376.6 ms ±   1.0 ms    [User: 345.8 ms, System: 30.5 ms]
  Range (min … max):   374.5 ms … 379.1 ms    50 runs

Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
  Time (mean ± σ):      2.922 s ±  0.006 s    [User: 2.707 s, System: 0.215 s]
  Range (min … max):    2.906 s …  2.934 s    50 runs

 # after

Benchmark 1: nix search --offline nixpkgs hello
  Time (mean ± σ):     570.4 ms ±   2.8 ms    [User: 561.3 ms, System: 8.6 ms]
  Range (min … max):   564.6 ms … 578.1 ms    50 runs

Benchmark 2: nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
  Time (mean ± σ):     375.4 ms ±   1.3 ms    [User: 343.2 ms, System: 31.7 ms]
  Range (min … max):   373.4 ms … 378.2 ms    50 runs

Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
  Time (mean ± σ):      2.925 s ±  0.006 s    [User: 2.704 s, System: 0.219 s]
  Range (min … max):    2.910 s …  2.942 s    50 runs
---
 src/libexpr/lexer.l | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/src/libexpr/lexer.l b/src/libexpr/lexer.l
index 70e99d2d2..a0e7a1877 100644
--- a/src/libexpr/lexer.l
+++ b/src/libexpr/lexer.l
@@ -64,29 +64,32 @@ static void adjustLoc(YYLTYPE * loc, const char * s, size_t len)
 }
 
 
-// FIXME: optimize
-static Expr * unescapeStr(SymbolTable & symbols, const char * s, size_t length)
+// we make use of the fact that the parser receives a private copy of the input
+// string and can munge around in it.
+static Expr * unescapeStr(SymbolTable & symbols, char * s, size_t length)
 {
-    string t;
-    t.reserve(length);
+    char * result = s;
+    char * t = s;
     char c;
+    // the input string is terminated with *two* NULs, so we can safely take
+    // *one* character after the one being checked against.
     while ((c = *s++)) {
         if (c == '\\') {
-            assert(*s);
             c = *s++;
-            if (c == 'n') t += '\n';
-            else if (c == 'r') t += '\r';
-            else if (c == 't') t += '\t';
-            else t += c;
+            if (c == 'n') *t = '\n';
+            else if (c == 'r') *t = '\r';
+            else if (c == 't') *t = '\t';
+            else *t = c;
         }
         else if (c == '\r') {
             /* Normalise CR and CR/LF into LF. */
-            t += '\n';
+            *t = '\n';
             if (*s == '\n') s++; /* cr/lf */
         }
-        else t += c;
+        else *t = c;
+        t++;
     }
-    return new ExprString(symbols.create(t));
+    return new ExprString(symbols.create({result, size_t(t - result)}));
 }
 
 

From 81cd0a113b8da1485c2f892c9dd9edb541f139ad Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Fri, 14 Jan 2022 13:41:45 +0100
Subject: [PATCH 401/567] Start the pager early-enough in `nix why-depends`
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

`nix why-depends` is piping its output into a pager by default.
However the pager was only started after the first path is printed,
causing it to be excluded from the pager output.

(Actually the pager was started *inside* the recursive function that was
printing the dependency chain, so a new instance was started at each
level. It’s a little miracle that it worked at all).

Fix #5911
---
 src/nix/why-depends.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/nix/why-depends.cc b/src/nix/why-depends.cc
index e27f56ef5..dd43bd1c3 100644
--- a/src/nix/why-depends.cc
+++ b/src/nix/why-depends.cc
@@ -239,7 +239,6 @@ struct CmdWhyDepends : SourceExprCommand
 
             visitPath(pathS);
 
-            RunPager pager;
             for (auto & ref : refs) {
                 std::string hash(ref.second->path.hashPart());
 
@@ -259,6 +258,7 @@ struct CmdWhyDepends : SourceExprCommand
             }
         };
 
+        RunPager pager;
         try {
             printNode(graph.at(packagePath), "", "");
         } catch (BailOut & ) { }

From c9fc975259e27220caeb4291f3dff453e65f1965 Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Sun, 2 Jan 2022 00:41:21 +0100
Subject: [PATCH 402/567] optimize removeAttrs builtin

use a sorted array of symbols to be removed instead of a set. this saves a lot
of memory allocations and slightly speeds up removal.
---
 src/libexpr/attr-set.hh |  7 +++++++
 src/libexpr/primops.cc  | 20 +++++++++++++-------
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/src/libexpr/attr-set.hh b/src/libexpr/attr-set.hh
index 82c348287..3e4899efc 100644
--- a/src/libexpr/attr-set.hh
+++ b/src/libexpr/attr-set.hh
@@ -121,6 +121,8 @@ class BindingsBuilder
     Bindings * bindings;
 
 public:
+    // needed by std::back_inserter
+    using value_type = Attr;
 
     EvalState & state;
 
@@ -134,6 +136,11 @@ public:
     }
 
     void insert(const Attr & attr)
+    {
+        push_back(attr);
+    }
+
+    void push_back(const Attr & attr)
     {
         bindings->push_back(attr);
     }
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 003e588a4..839fbb95c 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -12,6 +12,8 @@
 #include "value-to-xml.hh"
 #include "primops.hh"
 
+#include <boost/container/small_vector.hpp>
+
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
@@ -2270,21 +2272,25 @@ static void prim_removeAttrs(EvalState & state, const Pos & pos, Value * * args,
     state.forceAttrs(*args[0], pos);
     state.forceList(*args[1], pos);
 
-    /* Get the attribute names to be removed. */
-    std::set<Symbol> names;
+    /* Get the attribute names to be removed.
+       We keep them as Attrs instead of Symbols so std::set_difference
+       can be used to remove them from attrs[0]. */
+    boost::container::small_vector<Attr, 64> names;
+    names.reserve(args[1]->listSize());
     for (auto elem : args[1]->listItems()) {
         state.forceStringNoCtx(*elem, pos);
-        names.insert(state.symbols.create(elem->string.s));
+        names.emplace_back(state.symbols.create(elem->string.s), nullptr);
     }
+    std::sort(names.begin(), names.end());
 
     /* Copy all attributes not in that set.  Note that we don't need
        to sort v.attrs because it's a subset of an already sorted
        vector. */
     auto attrs = state.buildBindings(args[0]->attrs->size());
-    for (auto & i : *args[0]->attrs) {
-        if (!names.count(i.name))
-            attrs.insert(i);
-    }
+    std::set_difference(
+        args[0]->attrs->begin(), args[0]->attrs->end(),
+        names.begin(), names.end(),
+        std::back_inserter(attrs));
     v.mkAttrs(attrs.alreadySorted());
 }
 

From ad60dfde2af6bcdb77e50562a2f2b28107e28588 Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Sun, 2 Jan 2022 00:46:43 +0100
Subject: [PATCH 403/567] also cache split regexes, not just match regexes
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

gives about 1% improvement on system eval, a bit less on nix search.

 # before

  nix search --no-eval-cache --offline ../nixpkgs hello
    Time (mean ± σ):      7.419 s ±  0.045 s    [User: 6.362 s, System: 0.794 s]
    Range (min … max):    7.335 s …  7.517 s    20 runs

  nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
    Time (mean ± σ):      2.921 s ±  0.023 s    [User: 2.626 s, System: 0.210 s]
    Range (min … max):    2.883 s …  2.957 s    20 runs

 # after

  nix search --no-eval-cache --offline ../nixpkgs hello
    Time (mean ± σ):      7.370 s ±  0.059 s    [User: 6.333 s, System: 0.791 s]
    Range (min … max):    7.286 s …  7.541 s    20 runs

  nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
    Time (mean ± σ):      2.891 s ±  0.033 s    [User: 2.606 s, System: 0.210 s]
    Range (min … max):    2.823 s …  2.958 s    20 runs
---
 src/libexpr/eval.hh    | 1 +
 src/libexpr/primops.cc | 8 +++++---
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 348a1b291..63d16bd2b 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -400,6 +400,7 @@ private:
     friend struct ExprSelect;
     friend void prim_getAttr(EvalState & state, const Pos & pos, Value * * args, Value & v);
     friend void prim_match(EvalState & state, const Pos & pos, Value * * args, Value & v);
+    friend void prim_split(EvalState & state, const Pos & pos, Value * * args, Value & v);
 
     friend struct Value;
 };
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 839fbb95c..3004e9a0a 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -3528,18 +3528,20 @@ static RegisterPrimOp primop_match({
 
 /* Split a string with a regular expression, and return a list of the
    non-matching parts interleaved by the lists of the matching groups. */
-static void prim_split(EvalState & state, const Pos & pos, Value * * args, Value & v)
+void prim_split(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     auto re = state.forceStringNoCtx(*args[0], pos);
 
     try {
 
-        std::regex regex(re, std::regex::extended);
+        auto regex = state.regexCache->cache.find(re);
+        if (regex == state.regexCache->cache.end())
+            regex = state.regexCache->cache.emplace(re, std::regex(re, std::regex::extended)).first;
 
         PathSet context;
         const std::string str = state.forceString(*args[1], context, pos);
 
-        auto begin = std::sregex_iterator(str.begin(), str.end(), regex);
+        auto begin = std::sregex_iterator(str.begin(), str.end(), regex->second);
         auto end = std::sregex_iterator();
 
         // Any matches results are surrounded by non-matching results.

From 2dead2092470f7b0440d34035e19b9d8c80db91e Mon Sep 17 00:00:00 2001
From: tomberek <tomberek@users.noreply.github.com>
Date: Fri, 14 Jan 2022 09:16:34 -0500
Subject: [PATCH 404/567] Apply suggestions from code review
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
---
 doc/manual/src/release-notes/rl-next.md | 13 +------------
 src/libexpr/flake/flakeref.cc           |  2 +-
 2 files changed, 2 insertions(+), 13 deletions(-)

diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index 44c6e2c09..49be90f90 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -1,16 +1,5 @@
 # Release X.Y (202?-??-??)
 
-
-* Binary cache stores now have a setting `compression-level`.
-
-* `nix develop` now has a flag `--unpack` to run `unpackPhase`.
-
-* Lists can now be compared lexicographically using the `<` operator.
-
-* New built-in function: `builtins.groupBy`, with the same functionality as
-  Nixpkgs' `lib.groupBy`, but faster.
-
-* Nix now searches for a flake.nix up until git or filesystem boundary.
-
+* The Nix cli now searches for a flake.nix up until the root of the current git repository or a filesystem boundary rather than just in the current directory
 * The TOML parser used by `builtins.fromTOML` has been replaced by [a
   more compliant one](https://github.com/ToruNiina/toml11).
diff --git a/src/libexpr/flake/flakeref.cc b/src/libexpr/flake/flakeref.cc
index b3f01746e..06f8511b6 100644
--- a/src/libexpr/flake/flakeref.cc
+++ b/src/libexpr/flake/flakeref.cc
@@ -136,7 +136,7 @@ std::pair<FlakeRef, std::string> parseFlakeRefWithFragment(
                         throw Error("unable to find a flake before encountering git boundary at '%s'", path);
                     else {
                         if (lstat(path).st_dev != device)
-                            throw Error("unable to find a flake before encountering filesystem boundary at '%s'", path);
+                        throw Error("path '%s' is not part of a flake (neither it nor its parent directories contain a 'flake.nix' file)", origPath);
                     }
                     path = dirOf(path);
                 }

From e3690ab39382498eaabbd07e696335e17c9f209c Mon Sep 17 00:00:00 2001
From: Alexander Bantyev <balsoft@balsoft.ru>
Date: Fri, 14 Jan 2022 17:15:45 +0300
Subject: [PATCH 405/567] Add more tests for flake upward searching

---
 src/libexpr/flake/flakeref.cc | 37 ++++++++++++++++++-----------------
 tests/flake-searching.sh      | 14 +++++++++++--
 2 files changed, 31 insertions(+), 20 deletions(-)

diff --git a/src/libexpr/flake/flakeref.cc b/src/libexpr/flake/flakeref.cc
index 06f8511b6..930ed9ccd 100644
--- a/src/libexpr/flake/flakeref.cc
+++ b/src/libexpr/flake/flakeref.cc
@@ -122,27 +122,28 @@ std::pair<FlakeRef, std::string> parseFlakeRefWithFragment(
 
             if (isFlake) {
 
-            if (!allowMissing && !pathExists(path + "/flake.nix")){
-                notice("path '%s' does not contain a 'flake.nix', searching up",path);
+                if (!allowMissing && !pathExists(path + "/flake.nix")){
+                    notice("path '%s' does not contain a 'flake.nix', searching up",path);
 
-                // Save device to detect filesystem boundary
-                dev_t device = lstat(path).st_dev;
-                bool found = false;
-                while (path != "/") {
-                    if (pathExists(path + "/flake.nix")) {
-                        found = true;
-                        break;
-                    } else if (pathExists(path + "/.git"))
-                        throw Error("unable to find a flake before encountering git boundary at '%s'", path);
-                    else {
-                        if (lstat(path).st_dev != device)
-                        throw Error("path '%s' is not part of a flake (neither it nor its parent directories contain a 'flake.nix' file)", origPath);
+                    // Save device to detect filesystem boundary
+                    dev_t device = lstat(path).st_dev;
+                    bool found = false;
+                    while (path != "/") {
+                        if (pathExists(path + "/flake.nix")) {
+                            found = true;
+                            break;
+                        } else if (pathExists(path + "/.git"))
+                            throw Error("path '%s' is not part of a flake (neither it nor its parent directories contain a 'flake.nix' file)", path);
+                        else {
+                            if (lstat(path).st_dev != device)
+                                throw Error("unable to find a flake before encountering filesystem boundary at '%s'", path);
+                        }
+                        path = dirOf(path);
                     }
-                    path = dirOf(path);
+                    if (!found)
+                        throw BadURL("could not find a flake.nix file");
                 }
-                if (!found)
-                    throw BadURL("could not find a flake.nix file");
-            }
+
                 if (!S_ISDIR(lstat(path).st_mode))
                     throw BadURL("path '%s' is not a flake (because it's not a directory)", path);
 
diff --git a/tests/flake-searching.sh b/tests/flake-searching.sh
index 82ae66894..7c2041ce1 100644
--- a/tests/flake-searching.sh
+++ b/tests/flake-searching.sh
@@ -4,8 +4,11 @@ clearStore
 
 cp ./simple.nix ./simple.builder.sh ./config.nix $TEST_HOME
 cd $TEST_HOME
+mkdir -p foo/subdir
+echo '{ outputs = _: {}; }' > foo/flake.nix
 cat <<EOF > flake.nix
 {
+    inputs.foo.url = "$PWD/foo";
     outputs = a: {
        defaultPackage.$system = import ./simple.nix;
        packages.$system.test = import ./simple.nix;
@@ -13,12 +16,19 @@ cat <<EOF > flake.nix
 }
 EOF
 mkdir subdir
-cd subdir
+pushd subdir
 
-for i in "" . "$PWD" .# .#test; do
+for i in "" . .# .#test ../subdir ../subdir#test "$PWD"; do
     nix build $i || fail "flake should be found by searching up directories"
 done
 
 for i in "path:$PWD"; do
     ! nix build $i || fail "flake should not search up directories when using 'path:'"
 done
+
+popd
+
+nix build --override-input foo . || fail "flake should search up directories when not an installable"
+
+sed "s,$PWD/foo,$PWD/foo/subdir,g" -i flake.nix
+! nix build || fail "flake should not search upwards when part of inputs"

From de4489a672a635a350bae6094422a5917794f77a Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Fri, 14 Jan 2022 15:41:14 +0100
Subject: [PATCH 406/567] Forbid runtime references to boost

We explicitly hack around to remove them, so might as well check that
the hack is useful.

(Introduced because I feared that the changes of
https://github.com/NixOS/nix/pull/5906#discussion_r784810238 would bring
back some runtime references)
---
 flake.nix | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/flake.nix b/flake.nix
index f4fae2a00..026433c52 100644
--- a/flake.nix
+++ b/flake.nix
@@ -299,6 +299,8 @@
 
           propagatedBuildInputs = propagatedDeps;
 
+          disallowedReferences = [ boost ];
+
           preConfigure =
             ''
               # Copy libboost_context so we don't get all of Boost in our closure.

From 1dace028666f5547a4088071bad52846240eea05 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Fri, 14 Jan 2022 15:55:36 +0100
Subject: [PATCH 407/567] Add git to the docker image

Fix #5896

See https://github.com/NixOS/docker/issues/33
---
 docker.nix | 1 +
 1 file changed, 1 insertion(+)

diff --git a/docker.nix b/docker.nix
index 28745fc5d..ca5d90635 100644
--- a/docker.nix
+++ b/docker.nix
@@ -21,6 +21,7 @@ let
     cacert.out
     findutils
     iana-etc
+    git
   ];
 
   users = {

From f055cc5a0bfc0871d36cc141e14777acd0e214ca Mon Sep 17 00:00:00 2001
From: Alexander Bantyev <balsoft@balsoft.ru>
Date: Fri, 14 Jan 2022 17:53:07 +0300
Subject: [PATCH 408/567] Document searching upwards and fix documentation for
 installables

---
 src/nix/flake.md |  9 ---------
 src/nix/nix.md   | 30 +++++++++++++++++++++++++++---
 2 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/src/nix/flake.md b/src/nix/flake.md
index 3b5812a0a..a8436bcaa 100644
--- a/src/nix/flake.md
+++ b/src/nix/flake.md
@@ -137,15 +137,6 @@ Currently the `type` attribute can be one of the following:
   *path* must be a directory in the file system containing a file
   named `flake.nix`.
 
-  If the directory or any of its parents is a Git repository, then
-  this is essentially equivalent to `git+file://<path>` (see below),
-  except that the `dir` parameter is derived automatically. For
-  example, if `/foo/bar` is a Git repository, then the flake reference
-  `/foo/bar/flake` is equivalent to `/foo/bar?dir=flake`.
-
-  If the directory is not inside a Git repository, then the flake
-  contents is the entire contents of *path*.
-
   *path* generally must be an absolute path. However, on the command
   line, it can be a relative path (e.g. `.` or `./foo`) which is
   interpreted as relative to the current directory. In this case, it
diff --git a/src/nix/nix.md b/src/nix/nix.md
index d10de7c01..0756ef0ac 100644
--- a/src/nix/nix.md
+++ b/src/nix/nix.md
@@ -57,9 +57,33 @@ the Nix store. Here are the recognised types of installables:
   These have the form *flakeref*[`#`*attrpath*], where *flakeref* is a
   flake reference and *attrpath* is an optional attribute path. For
   more information on flakes, see [the `nix flake` manual
-  page](./nix3-flake.md). Flake references are most commonly a flake
-  identifier in the flake registry (e.g. `nixpkgs`) or a path
-  (e.g. `/path/to/my-flake` or `.`).
+  page](./nix3-flake.md).  Flake references are most commonly a flake
+  identifier in the flake registry (e.g. `nixpkgs`), or a raw path
+  (e.g. `/path/to/my-flake` or `.` or `../foo`), or a full URL
+  (e.g. `github:nixos/nixpkgs` or `path:.`)
+
+  When the flake reference is a raw path (a path without any URL
+  scheme), it is interpreted in the following way:
+
+  - If the supplied path does not contain `flake.nix`, then Nix
+    searches for a directory containing `flake.nix` upwards of the
+    supplied path (until a filesystem boundary or a git repository
+    root). For example, if `/foo/bar/flake.nix` exists, then supplying
+    `/foo/bar/baz/` will find the directory `/foo/bar/`;
+  - If `flake.nix` is in a Git repository, then this is essentially
+    equivalent to `git+file://<directory>` (see [the `nix flake`
+    manual page](./nix3-flake.md)), except that the `dir` parameter is
+    derived automatically. For example, if `/foo/bar` is a Git
+    repository and `/foo/bar/baz` contains `flake.nix`, then the flake
+    reference `/foo/bar/baz` is equivalent to
+    `git+file:///foo/bar?dir=baz`. Note that it will only include
+    files indexed by git. In particular, files which are matched by
+    `.gitignore` will not be available in the flake. If this is
+    undesireable, specify `path:<directory>` explicitly;
+  - If the directory is not inside a Git repository, then it is
+    equivalent to `path:<directory>` (see [the `nix flake` manual
+    page](./nix3-flake.md)), which includes the entire contents of the
+    path.
 
   If *attrpath* is omitted, Nix tries some default values; for most
   subcommands, the default is `defaultPackage.`*system*

From b9f5dccdbeb14a229fd14a3211490d83e53f70b8 Mon Sep 17 00:00:00 2001
From: Alexander Bantyev <balsoft@balsoft.ru>
Date: Fri, 14 Jan 2022 18:03:47 +0300
Subject: [PATCH 409/567] Check that we don't search past a git repo

---
 tests/flake-searching.sh | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/tests/flake-searching.sh b/tests/flake-searching.sh
index 7c2041ce1..6558aff9a 100644
--- a/tests/flake-searching.sh
+++ b/tests/flake-searching.sh
@@ -18,11 +18,14 @@ EOF
 mkdir subdir
 pushd subdir
 
-for i in "" . .# .#test ../subdir ../subdir#test "$PWD"; do
+success=("" . .# .#test ../subdir ../subdir#test "$PWD")
+failure=("path:$PWD")
+
+for i in "${success[@]}"; do
     nix build $i || fail "flake should be found by searching up directories"
 done
 
-for i in "path:$PWD"; do
+for i in "${failure[@]}"; do
     ! nix build $i || fail "flake should not search up directories when using 'path:'"
 done
 
@@ -32,3 +35,11 @@ nix build --override-input foo . || fail "flake should search up directories whe
 
 sed "s,$PWD/foo,$PWD/foo/subdir,g" -i flake.nix
 ! nix build || fail "flake should not search upwards when part of inputs"
+
+pushd subdir
+git init
+for i in "${success[@]}" "${failure[@]}"; do
+    ! nix build $i || fail "flake should not search past a git repository"
+done
+rm -rf .git
+popd

From 3fff0196cdf0859ee16c719fdc51084a414c8a4d Mon Sep 17 00:00:00 2001
From: John Axel Eriksson <john@insane.se>
Date: Sat, 15 Jan 2022 10:20:18 +0100
Subject: [PATCH 410/567] docker: also create var/tmp as some tools rely on it

---
 docker.nix | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/docker.nix b/docker.nix
index ca5d90635..0e29d0e0b 100644
--- a/docker.nix
+++ b/docker.nix
@@ -201,6 +201,8 @@ let
 
       mkdir $out/tmp
 
+      mkdir $out/var/tmp
+
       mkdir -p $out/etc/nix
       cat $nixConfContentsPath > $out/etc/nix/nix.conf
 
@@ -236,6 +238,7 @@ pkgs.dockerTools.buildLayeredImageWithNixDb {
   '';
   fakeRootCommands = ''
     chmod 1777 tmp
+    chmod 1777 var/tmp
   '';
 
   config = {

From dd3aa1e5158f5692326f282985ec03300ed452b2 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Sat, 15 Jan 2022 11:32:57 +0100
Subject: [PATCH 411/567] Remove the references to boost on darwin

---
 flake.nix | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/flake.nix b/flake.nix
index 026433c52..86601fcd9 100644
--- a/flake.nix
+++ b/flake.nix
@@ -312,6 +312,13 @@
                 chmod u+w $out/lib/*.so.*
                 patchelf --set-rpath $out/lib:${currentStdenv.cc.cc.lib}/lib $out/lib/libboost_thread.so.*
               ''}
+              ${lib.optionalString currentStdenv.isDarwin ''
+                for LIB in $out/lib/*.dylib; do
+                  chmod u+w $LIB
+                  install_name_tool -id $LIB $LIB
+                done
+                install_name_tool -change ${boost}/lib/libboost_system.dylib $out/lib/libboost_system.dylib $out/lib/libboost_thread.dylib
+              ''}
             '';
 
           configureFlags = configureFlags ++
@@ -328,6 +335,12 @@
           postInstall = ''
             mkdir -p $doc/nix-support
             echo "doc manual $doc/share/doc/nix/manual" >> $doc/nix-support/hydra-build-products
+            ${lib.optionalString currentStdenv.isDarwin ''
+            install_name_tool \
+              -change ${boost}/lib/libboost_context.dylib \
+              $out/lib/libboost_context.dylib \
+              $out/lib/libnixutil.dylib
+            ''}
           '';
 
           doInstallCheck = true;

From 84507daaaa476e9ee4fbf87d1728a07ad6520ca0 Mon Sep 17 00:00:00 2001
From: John Axel Eriksson <john@insane.se>
Date: Sat, 15 Jan 2022 14:11:37 +0100
Subject: [PATCH 412/567] docker: var/tmp make add -p option to mkdir to also
 create parent dirs

---
 docker.nix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docker.nix b/docker.nix
index 0e29d0e0b..251bd2f46 100644
--- a/docker.nix
+++ b/docker.nix
@@ -201,7 +201,7 @@ let
 
       mkdir $out/tmp
 
-      mkdir $out/var/tmp
+      mkdir -p $out/var/tmp
 
       mkdir -p $out/etc/nix
       cat $nixConfContentsPath > $out/etc/nix/nix.conf

From 6ff2ce8caf6f5fa0134ab7c6fa9547226dad8bde Mon Sep 17 00:00:00 2001
From: Farid Zakaria <farid.m.zakaria@gmail.com>
Date: Sat, 15 Jan 2022 19:17:40 -0800
Subject: [PATCH 413/567] Added result and .vscode to gitignore

---
 .gitignore | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/.gitignore b/.gitignore
index 2889a56eb..4b290425a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -120,3 +120,7 @@ GTAGS
 compile_commands.json
 
 nix-rust/target
+
+result
+
+.vscode/

From 61f02f7f2082a1a012b6ae0e3d5c2edc3567c5b7 Mon Sep 17 00:00:00 2001
From: Farid Zakaria <farid.m.zakaria@gmail.com>
Date: Sat, 15 Jan 2022 19:36:07 -0800
Subject: [PATCH 414/567] Make queryJSON not bail immediately on an assertion
 or error

---
 src/nix-env/nix-env.cc | 58 ++++++++++++++++++++++++------------------
 1 file changed, 33 insertions(+), 25 deletions(-)

diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index f4647f43d..f95754599 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -911,36 +911,44 @@ static void queryJSON(Globals & globals, vector<DrvInfo> & elems, bool printOutP
 {
     JSONObject topObj(cout, true);
     for (auto & i : elems) {
-        JSONObject pkgObj = topObj.object(i.attrPath);
+        try {
+            if (i.hasFailed()) continue;
 
-        auto drvName = DrvName(i.queryName());
-        pkgObj.attr("name", drvName.fullName);
-        pkgObj.attr("pname", drvName.name);
-        pkgObj.attr("version", drvName.version);
-        pkgObj.attr("system", i.querySystem());
+            JSONObject pkgObj = topObj.object(i.attrPath);
 
-        if (printOutPath) {
-            DrvInfo::Outputs outputs = i.queryOutputs();
-            JSONObject outputObj = pkgObj.object("outputs");
-            for (auto & j : outputs) {
-                outputObj.attr(j.first, j.second);
-            }
-        }
+            auto drvName = DrvName(i.queryName());
+            pkgObj.attr("name", drvName.fullName);
+            pkgObj.attr("pname", drvName.name);
+            pkgObj.attr("version", drvName.version);
+            pkgObj.attr("system", i.querySystem());
 
-        if (printMeta) {
-            JSONObject metaObj = pkgObj.object("meta");
-            StringSet metaNames = i.queryMetaNames();
-            for (auto & j : metaNames) {
-                auto placeholder = metaObj.placeholder(j);
-                Value * v = i.queryMeta(j);
-                if (!v) {
-                    printError("derivation '%s' has invalid meta attribute '%s'", i.queryName(), j);
-                    placeholder.write(nullptr);
-                } else {
-                    PathSet context;
-                    printValueAsJSON(*globals.state, true, *v, noPos, placeholder, context);
+            if (printOutPath) {
+                DrvInfo::Outputs outputs = i.queryOutputs();
+                JSONObject outputObj = pkgObj.object("outputs");
+                for (auto & j : outputs) {
+                    outputObj.attr(j.first, j.second);
                 }
             }
+
+            if (printMeta) {
+                JSONObject metaObj = pkgObj.object("meta");
+                StringSet metaNames = i.queryMetaNames();
+                for (auto & j : metaNames) {
+                    auto placeholder = metaObj.placeholder(j);
+                    Value * v = i.queryMeta(j);
+                    if (!v) {
+                        printError("derivation '%s' has invalid meta attribute '%s'", i.queryName(), j);
+                        placeholder.write(nullptr);
+                    } else {
+                        PathSet context;
+                        printValueAsJSON(*globals.state, true, *v, noPos, placeholder, context);
+                    }
+                }
+            }
+        } catch (AssertionError & e) {
+            printMsg(lvlTalkative, "skipping derivation named '%1%' which gives an assertion failure", i.queryName());
+        } catch (Error & e) {
+            printMsg(lvlError, "skipping derivation named '%1%' which gives an error '%2%'", i.queryName(), e.msg());
         }
     }
 }

From 8cf54f754dcdd11ffb6ed4c7aa6794d113c849b3 Mon Sep 17 00:00:00 2001
From: Alexander Bantyev <balsoft@balsoft.ru>
Date: Fri, 14 Jan 2022 20:07:47 +0300
Subject: [PATCH 415/567] Show build and substitution information when not
 connected to a TTY
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

When stderr is not connected to a tty, show "building" and
"substituting" messages, a-la nix-build et al.

Closes https://github.com/NixOS/nix/issues/4402

Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
---
 src/nix/main.cc | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/nix/main.cc b/src/nix/main.cc
index fe7469be4..5158c3902 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -270,11 +270,15 @@ void mainWrapped(int argc, char * * argv)
         if (legacy) return legacy(argc, argv);
     }
 
-    verbosity = lvlNotice;
-    settings.verboseBuild = false;
     evalSettings.pureEval = true;
 
     setLogFormat("bar");
+    settings.verboseBuild = false;
+    if (isatty(STDERR_FILENO)) {
+        verbosity = lvlNotice;
+    } else {
+        verbosity = lvlInfo;
+    }
 
     Finally f([] { logger->stop(); });
 

From 34b66aab009428d3fab05b7530d6d13f1df3b2c9 Mon Sep 17 00:00:00 2001
From: Alexander Bantyev <balsoft@balsoft.ru>
Date: Mon, 17 Jan 2022 20:00:04 +0300
Subject: [PATCH 416/567] Update documentation for paths on command line
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
---
 src/nix/nix.md | 54 +++++++++++++++++++++++++++++++-------------------
 1 file changed, 34 insertions(+), 20 deletions(-)

diff --git a/src/nix/nix.md b/src/nix/nix.md
index 0756ef0ac..33942a5ad 100644
--- a/src/nix/nix.md
+++ b/src/nix/nix.md
@@ -63,27 +63,41 @@ the Nix store. Here are the recognised types of installables:
   (e.g. `github:nixos/nixpkgs` or `path:.`)
 
   When the flake reference is a raw path (a path without any URL
-  scheme), it is interpreted in the following way:
+  scheme), it is interpreted as a `path:` or `git+file:` url in the following
+  way:
+  
+  - If the path is within a Git repository, then the url will be of the form
+    `git+file://[GIT_REPO_ROOT]?dir=[RELATIVE_FLAKE_DIR_PATH]`
+    where `GIT_REPO_ROOT` is the path to the root of the git repository,
+    and `RELATIVE_FLAKE_DIR_PATH` is the path (relative to the directory
+    root) of the closest parent of the given path that contains a `flake.nix` within
+    the git repository.
+    If no such directory exists, then Nix will error-out.
+    
+    Note that the search will only include files indexed by git. In particular, files
+    which are matched by `.gitignore` or have never been `git add`-ed will not be
+    available in the flake. If this is undesireable, specify `path:<directory>` explicitly;
+    
+    For example, if `/foo/bar` is a git repository with the following structure:
+    ```
+   .
+   └── baz
+       ├── blah
+       │   └── file.txt
+       └── flake.nix
+    ```
+
+  Then `/foo/bar/baz/blah` will resolve to `git+file:///foo/bar?dir=baz`
+
+  - If the supplied path is not a git repository, then the url will have the form
+    `path:FLAKE_DIR_PATH` where `FLAKE_DIR_PATH` is the closest parent
+    of the supplied path that contains a `flake.nix` file (within the same file-system).
+    If no such directory exists, then Nix will error-out.
+    
+    For example, if `/foo/bar/flake.nix` exists, then `/foo/bar/baz/` will resolve to
+   `path:/foo/bar`
+
 
-  - If the supplied path does not contain `flake.nix`, then Nix
-    searches for a directory containing `flake.nix` upwards of the
-    supplied path (until a filesystem boundary or a git repository
-    root). For example, if `/foo/bar/flake.nix` exists, then supplying
-    `/foo/bar/baz/` will find the directory `/foo/bar/`;
-  - If `flake.nix` is in a Git repository, then this is essentially
-    equivalent to `git+file://<directory>` (see [the `nix flake`
-    manual page](./nix3-flake.md)), except that the `dir` parameter is
-    derived automatically. For example, if `/foo/bar` is a Git
-    repository and `/foo/bar/baz` contains `flake.nix`, then the flake
-    reference `/foo/bar/baz` is equivalent to
-    `git+file:///foo/bar?dir=baz`. Note that it will only include
-    files indexed by git. In particular, files which are matched by
-    `.gitignore` will not be available in the flake. If this is
-    undesireable, specify `path:<directory>` explicitly;
-  - If the directory is not inside a Git repository, then it is
-    equivalent to `path:<directory>` (see [the `nix flake` manual
-    page](./nix3-flake.md)), which includes the entire contents of the
-    path.
 
   If *attrpath* is omitted, Nix tries some default values; for most
   subcommands, the default is `defaultPackage.`*system*

From 776eb97a4328ccfacbd4e795b4659b7367838db0 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 17 Jan 2022 19:28:42 +0100
Subject: [PATCH 417/567] serialise.hh: Use std::string_view

---
 src/libstore/build/derivation-goal.cc | 2 +-
 src/libutil/error.hh                  | 2 +-
 src/libutil/serialise.cc              | 2 +-
 src/libutil/serialise.hh              | 4 ++--
 4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/libstore/build/derivation-goal.cc b/src/libstore/build/derivation-goal.cc
index d34e53fe8..151217b8b 100644
--- a/src/libstore/build/derivation-goal.cc
+++ b/src/libstore/build/derivation-goal.cc
@@ -278,7 +278,7 @@ void DerivationGoal::outputsSubstitutionTried()
 
     if (nrFailed > 0 && nrFailed > nrNoSubstituters + nrIncompleteClosure && !settings.tryFallback) {
         done(BuildResult::TransientFailure,
-            fmt("some substitutes for the outputs of derivation '%s' failed (usually happens due to networking issues); try '--fallback' to build derivation from source ",
+            Error("some substitutes for the outputs of derivation '%s' failed (usually happens due to networking issues); try '--fallback' to build derivation from source ",
                 worker.store.printStorePath(drvPath)));
         return;
     }
diff --git a/src/libutil/error.hh b/src/libutil/error.hh
index ff58d3e00..6fe5e4857 100644
--- a/src/libutil/error.hh
+++ b/src/libutil/error.hh
@@ -137,7 +137,7 @@ public:
     { }
 
     template<typename... Args>
-    BaseError(const std::string & fs, const Args & ... args)
+    explicit BaseError(const std::string & fs, const Args & ... args)
         : err { .level = lvlError, .msg = hintfmt(fs, args...) }
     { }
 
diff --git a/src/libutil/serialise.cc b/src/libutil/serialise.cc
index 16f3476c2..704359b4a 100644
--- a/src/libutil/serialise.cc
+++ b/src/libutil/serialise.cc
@@ -325,7 +325,7 @@ void writeString(std::string_view data, Sink & sink)
 }
 
 
-Sink & operator << (Sink & sink, const string & s)
+Sink & operator << (Sink & sink, std::string_view s)
 {
     writeString(s, sink);
     return sink;
diff --git a/src/libutil/serialise.hh b/src/libutil/serialise.hh
index 0fe6e8332..b3cfb06a2 100644
--- a/src/libutil/serialise.hh
+++ b/src/libutil/serialise.hh
@@ -317,10 +317,10 @@ inline Sink & operator << (Sink & sink, uint64_t n)
     return sink;
 }
 
-Sink & operator << (Sink & sink, const string & s);
+Sink & operator << (Sink & in, const Error & ex);
+Sink & operator << (Sink & sink, std::string_view s);
 Sink & operator << (Sink & sink, const Strings & s);
 Sink & operator << (Sink & sink, const StringSet & s);
-Sink & operator << (Sink & in, const Error & ex);
 
 
 MakeError(SerialisationError, Error);

From 52ee7ec0028263f04e15c05256ca90fa62a0da66 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 17 Jan 2022 19:38:17 +0100
Subject: [PATCH 418/567] StringSource: Use std::string_view

---
 src/libutil/serialise.hh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libutil/serialise.hh b/src/libutil/serialise.hh
index b3cfb06a2..e80fb9ecf 100644
--- a/src/libutil/serialise.hh
+++ b/src/libutil/serialise.hh
@@ -167,9 +167,9 @@ struct StringSink : Sink
 /* A source that reads data from a string. */
 struct StringSource : Source
 {
-    const string & s;
+    std::string_view s;
     size_t pos;
-    StringSource(const string & _s) : s(_s), pos(0) { }
+    StringSource(std::string_view s) : s(s), pos(0) { }
     size_t read(char * data, size_t len) override;
 };
 

From 5753f6efbb46ea172913d03d0b0988546ff4971f Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Tue, 18 Jan 2022 10:55:00 +0100
Subject: [PATCH 419/567] Fix the rendering of the example directory tree

---
 src/nix/nix.md | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/nix/nix.md b/src/nix/nix.md
index 33942a5ad..2f54c5e2c 100644
--- a/src/nix/nix.md
+++ b/src/nix/nix.md
@@ -80,11 +80,11 @@ the Nix store. Here are the recognised types of installables:
     
     For example, if `/foo/bar` is a git repository with the following structure:
     ```
-   .
-   └── baz
-       ├── blah
-       │   └── file.txt
-       └── flake.nix
+    .
+    └── baz
+        ├── blah
+        │   └── file.txt
+        └── flake.nix
     ```
 
   Then `/foo/bar/baz/blah` will resolve to `git+file:///foo/bar?dir=baz`

From d62a9390fcdc0f9e4971e5fab2f667567237b252 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 17 Jan 2022 22:20:05 +0100
Subject: [PATCH 420/567] Get rid of std::shared_ptr<std::string> and
 ref<std::string>

These were needed back in the pre-C++11 era because we didn't have
move semantics. But now we do.
---
 src/libfetchers/tarball.cc                  | 10 +++----
 src/libstore/binary-cache-store.cc          | 24 ++++++++---------
 src/libstore/binary-cache-store.hh          |  9 ++++---
 src/libstore/build/local-derivation-goal.cc |  6 ++---
 src/libstore/daemon.cc                      | 14 +++++-----
 src/libstore/export-import.cc               |  6 ++---
 src/libstore/filetransfer.cc                | 20 +++++++-------
 src/libstore/filetransfer.hh                |  8 +++---
 src/libstore/http-binary-cache-store.cc     |  8 +++---
 src/libstore/legacy-ssh-store.cc            |  2 +-
 src/libstore/local-fs-store.cc              | 16 +++++------
 src/libstore/local-fs-store.hh              |  3 ++-
 src/libstore/local-store.cc                 |  4 +--
 src/libstore/nar-accessor.cc                |  8 +++---
 src/libstore/nar-accessor.hh                |  2 +-
 src/libstore/remote-fs-accessor.cc          | 30 +++++++++++----------
 src/libstore/remote-fs-accessor.hh          |  3 +--
 src/libstore/remote-store.cc                |  2 +-
 src/libstore/s3-binary-cache-store.cc       |  2 +-
 src/libstore/s3.hh                          |  4 ++-
 src/libstore/store-api.hh                   |  4 +--
 src/libutil/compression.cc                  |  8 +++---
 src/libutil/compression.hh                  |  4 +--
 src/libutil/serialise.cc                    |  6 ++---
 src/libutil/serialise.hh                    | 11 ++++----
 src/libutil/tests/compression.cc            | 28 +++++++++----------
 src/libutil/util.cc                         |  4 +--
 src/nix/add-to-store.cc                     |  6 ++---
 src/nix/cat.cc                              |  2 +-
 src/nix/ls.cc                               |  2 +-
 src/nix/make-content-addressable.cc         |  8 +++---
 src/nix/profile.cc                          |  6 ++---
 src/nix/upgrade-nix.cc                      |  2 +-
 33 files changed, 138 insertions(+), 134 deletions(-)

diff --git a/src/libfetchers/tarball.cc b/src/libfetchers/tarball.cc
index 69d020748..c933475ca 100644
--- a/src/libfetchers/tarball.cc
+++ b/src/libfetchers/tarball.cc
@@ -67,18 +67,18 @@ DownloadFileResult downloadFile(
         storePath = std::move(cached->storePath);
     } else {
         StringSink sink;
-        dumpString(*res.data, sink);
-        auto hash = hashString(htSHA256, *res.data);
+        dumpString(res.data, sink);
+        auto hash = hashString(htSHA256, res.data);
         ValidPathInfo info {
             store->makeFixedOutputPath(FileIngestionMethod::Flat, hash, name),
-            hashString(htSHA256, *sink.s),
+            hashString(htSHA256, sink.s),
         };
-        info.narSize = sink.s->size();
+        info.narSize = sink.s.size();
         info.ca = FixedOutputHash {
             .method = FileIngestionMethod::Flat,
             .hash = hash,
         };
-        auto source = StringSource { *sink.s };
+        auto source = StringSource(sink.s);
         store->addToStore(info, source, NoRepair, NoCheckSigs);
         storePath = std::move(info.path);
     }
diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index 13c086a46..8aec632e8 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -31,7 +31,7 @@ BinaryCacheStore::BinaryCacheStore(const Params & params)
 
     StringSink sink;
     sink << narVersionMagic1;
-    narMagic = *sink.s;
+    narMagic = sink.s;
 }
 
 void BinaryCacheStore::init()
@@ -68,7 +68,7 @@ void BinaryCacheStore::upsertFile(const std::string & path,
 }
 
 void BinaryCacheStore::getFile(const std::string & path,
-    Callback<std::shared_ptr<std::string>> callback) noexcept
+    Callback<std::optional<std::string>> callback) noexcept
 {
     try {
         callback(getFile(path));
@@ -77,9 +77,9 @@ void BinaryCacheStore::getFile(const std::string & path,
 
 void BinaryCacheStore::getFile(const std::string & path, Sink & sink)
 {
-    std::promise<std::shared_ptr<std::string>> promise;
+    std::promise<std::optional<std::string>> promise;
     getFile(path,
-        {[&](std::future<std::shared_ptr<std::string>> result) {
+        {[&](std::future<std::optional<std::string>> result) {
             try {
                 promise.set_value(result.get());
             } catch (...) {
@@ -89,15 +89,15 @@ void BinaryCacheStore::getFile(const std::string & path, Sink & sink)
     sink(*promise.get_future().get());
 }
 
-std::shared_ptr<std::string> BinaryCacheStore::getFile(const std::string & path)
+std::optional<std::string> BinaryCacheStore::getFile(const std::string & path)
 {
     StringSink sink;
     try {
         getFile(path, sink);
     } catch (NoSuchBinaryCacheFile &) {
-        return nullptr;
+        return std::nullopt;
     }
-    return sink.s;
+    return std::move(sink.s);
 }
 
 std::string BinaryCacheStore::narInfoFileFor(const StorePath & storePath)
@@ -367,7 +367,7 @@ void BinaryCacheStore::queryPathInfoUncached(const StorePath & storePath,
     auto callbackPtr = std::make_shared<decltype(callback)>(std::move(callback));
 
     getFile(narInfoFile,
-        {[=](std::future<std::shared_ptr<std::string>> fut) {
+        {[=](std::future<std::optional<std::string>> fut) {
             try {
                 auto data = fut.get();
 
@@ -429,7 +429,7 @@ StorePath BinaryCacheStore::addTextToStore(const string & name, const string & s
 
     StringSink sink;
     dumpString(s, sink);
-    auto source = StringSource { *sink.s };
+    StringSource source(sink.s);
     return addToStoreCommon(source, repair, CheckSigs, [&](HashResult nar) {
         ValidPathInfo info { path, nar.first };
         info.narSize = nar.second;
@@ -446,8 +446,8 @@ void BinaryCacheStore::queryRealisationUncached(const DrvOutput & id,
 
     auto callbackPtr = std::make_shared<decltype(callback)>(std::move(callback));
 
-    Callback<std::shared_ptr<std::string>> newCallback = {
-        [=](std::future<std::shared_ptr<std::string>> fut) {
+    Callback<std::optional<std::string>> newCallback = {
+        [=](std::future<std::optional<std::string>> fut) {
             try {
                 auto data = fut.get();
                 if (!data) return (*callbackPtr)(nullptr);
@@ -490,7 +490,7 @@ void BinaryCacheStore::addSignatures(const StorePath & storePath, const StringSe
     writeNarInfo(narInfo);
 }
 
-std::shared_ptr<std::string> BinaryCacheStore::getBuildLog(const StorePath & path)
+std::optional<std::string> BinaryCacheStore::getBuildLog(const StorePath & path)
 {
     auto drvPath = path;
 
diff --git a/src/libstore/binary-cache-store.hh b/src/libstore/binary-cache-store.hh
index 9815af591..46ff67c77 100644
--- a/src/libstore/binary-cache-store.hh
+++ b/src/libstore/binary-cache-store.hh
@@ -62,10 +62,11 @@ public:
 
     /* Fetch the specified file and call the specified callback with
        the result. A subclass may implement this asynchronously. */
-    virtual void getFile(const std::string & path,
-        Callback<std::shared_ptr<std::string>> callback) noexcept;
+    virtual void getFile(
+        const std::string & path,
+        Callback<std::optional<std::string>> callback) noexcept;
 
-    std::shared_ptr<std::string> getFile(const std::string & path);
+    std::optional<std::string> getFile(const std::string & path);
 
 public:
 
@@ -117,7 +118,7 @@ public:
 
     void addSignatures(const StorePath & storePath, const StringSet & sigs) override;
 
-    std::shared_ptr<std::string> getBuildLog(const StorePath & path) override;
+    std::optional<std::string> getBuildLog(const StorePath & path) override;
 
 };
 
diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index e4d2add73..0d0afea2d 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -2226,8 +2226,8 @@ void LocalDerivationGoal::registerOutputs()
                 StringSink sink;
                 dumpPath(actualPath, sink);
                 deletePath(actualPath);
-                sink.s = make_ref<std::string>(rewriteStrings(*sink.s, outputRewrites));
-                StringSource source(*sink.s);
+                sink.s = rewriteStrings(sink.s, outputRewrites);
+                StringSource source(sink.s);
                 restorePath(actualPath, source);
             }
         };
@@ -2295,7 +2295,7 @@ void LocalDerivationGoal::registerOutputs()
                     StringSink sink;
                     dumpPath(actualPath, sink);
                     RewritingSink rsink2(oldHashPart, std::string(finalPath.hashPart()), nextSink);
-                    rsink2(*sink.s);
+                    rsink2(sink.s);
                     rsink2.flush();
                 });
                 Path tmpPath = actualPath + ".tmp";
diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index 59325da79..5b817c587 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -69,7 +69,7 @@ struct TunnelLogger : public Logger
 
         StringSink buf;
         buf << STDERR_NEXT << (fs.s + "\n");
-        enqueueMsg(*buf.s);
+        enqueueMsg(buf.s);
     }
 
     void logEI(const ErrorInfo & ei) override
@@ -81,7 +81,7 @@ struct TunnelLogger : public Logger
 
         StringSink buf;
         buf << STDERR_NEXT << oss.str();
-        enqueueMsg(*buf.s);
+        enqueueMsg(buf.s);
     }
 
     /* startWork() means that we're starting an operation for which we
@@ -129,7 +129,7 @@ struct TunnelLogger : public Logger
 
         StringSink buf;
         buf << STDERR_START_ACTIVITY << act << lvl << type << s << fields << parent;
-        enqueueMsg(*buf.s);
+        enqueueMsg(buf.s);
     }
 
     void stopActivity(ActivityId act) override
@@ -137,7 +137,7 @@ struct TunnelLogger : public Logger
         if (GET_PROTOCOL_MINOR(clientVersion) < 20) return;
         StringSink buf;
         buf << STDERR_STOP_ACTIVITY << act;
-        enqueueMsg(*buf.s);
+        enqueueMsg(buf.s);
     }
 
     void result(ActivityId act, ResultType type, const Fields & fields) override
@@ -145,7 +145,7 @@ struct TunnelLogger : public Logger
         if (GET_PROTOCOL_MINOR(clientVersion) < 20) return;
         StringSink buf;
         buf << STDERR_RESULT << act << type << fields;
-        enqueueMsg(*buf.s);
+        enqueueMsg(buf.s);
     }
 };
 
@@ -852,14 +852,14 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
 
         else {
             std::unique_ptr<Source> source;
+            StringSink saved;
             if (GET_PROTOCOL_MINOR(clientVersion) >= 21)
                 source = std::make_unique<TunnelSource>(from, to);
             else {
-                StringSink saved;
                 TeeSource tee { from, saved };
                 ParseSink ether;
                 parseDump(ether, tee);
-                source = std::make_unique<StringSource>(std::move(*saved.s));
+                source = std::make_unique<StringSource>(saved.s);
             }
 
             logger->startWork();
diff --git a/src/libstore/export-import.cc b/src/libstore/export-import.cc
index 02c839520..9875da909 100644
--- a/src/libstore/export-import.cc
+++ b/src/libstore/export-import.cc
@@ -75,20 +75,20 @@ StorePaths Store::importPaths(Source & source, CheckSigsFlag checkSigs)
 
         auto references = worker_proto::read(*this, source, Phantom<StorePathSet> {});
         auto deriver = readString(source);
-        auto narHash = hashString(htSHA256, *saved.s);
+        auto narHash = hashString(htSHA256, saved.s);
 
         ValidPathInfo info { path, narHash };
         if (deriver != "")
             info.deriver = parseStorePath(deriver);
         info.references = references;
-        info.narSize = saved.s->size();
+        info.narSize = saved.s.size();
 
         // Ignore optional legacy signature.
         if (readInt(source) == 1)
             readString(source);
 
         // Can't use underlying source, which would have been exhausted
-        auto source = StringSource { *saved.s };
+        auto source = StringSource(saved.s);
         addToStore(info, source, NoRepair, checkSigs);
 
         res.push_back(info.path);
diff --git a/src/libstore/filetransfer.cc b/src/libstore/filetransfer.cc
index 17980ab22..6b62311cf 100644
--- a/src/libstore/filetransfer.cc
+++ b/src/libstore/filetransfer.cc
@@ -106,7 +106,7 @@ struct curlFileTransfer : public FileTransfer
                         this->request.dataCallback(data);
                     }
                 } else
-                    this->result.data->append(data);
+                    this->result.data.append(data);
               })
         {
             if (!request.expectedETag.empty())
@@ -195,7 +195,7 @@ struct curlFileTransfer : public FileTransfer
             std::smatch match;
             if (std::regex_match(line, match, statusLine)) {
                 result.etag = "";
-                result.data = std::make_shared<std::string>();
+                result.data.clear();
                 result.bodySize = 0;
                 statusMsg = trim(match[1]);
                 acceptRanges = false;
@@ -340,7 +340,7 @@ struct curlFileTransfer : public FileTransfer
             if (writtenToSink)
                 curl_easy_setopt(req, CURLOPT_RESUME_FROM_LARGE, writtenToSink);
 
-            result.data = std::make_shared<std::string>();
+            result.data.clear();
             result.bodySize = 0;
         }
 
@@ -434,21 +434,21 @@ struct curlFileTransfer : public FileTransfer
 
                 attempt++;
 
-                std::shared_ptr<std::string> response;
+                std::optional<std::string> response;
                 if (errorSink)
-                    response = errorSink->s;
+                    response = std::move(errorSink->s);
                 auto exc =
                     code == CURLE_ABORTED_BY_CALLBACK && _isInterrupted
-                    ? FileTransferError(Interrupted, response, "%s of '%s' was interrupted", request.verb(), request.uri)
+                    ? FileTransferError(Interrupted, std::move(response), "%s of '%s' was interrupted", request.verb(), request.uri)
                     : httpStatus != 0
                     ? FileTransferError(err,
-                        response,
+                        std::move(response),
                         fmt("unable to %s '%s': HTTP error %d ('%s')",
                             request.verb(), request.uri, httpStatus, statusMsg)
                         + (code == CURLE_OK ? "" : fmt(" (curl error: %s)", curl_easy_strerror(code)))
                         )
                     : FileTransferError(err,
-                        response,
+                        std::move(response),
                         fmt("unable to %s '%s': %s (%d)",
                             request.verb(), request.uri, curl_easy_strerror(code), code));
 
@@ -705,7 +705,7 @@ struct curlFileTransfer : public FileTransfer
                 FileTransferResult res;
                 if (!s3Res.data)
                     throw FileTransferError(NotFound, nullptr, "S3 object '%s' does not exist", request.uri);
-                res.data = s3Res.data;
+                res.data = std::move(*s3Res.data);
                 callback(std::move(res));
 #else
                 throw nix::Error("cannot download '%s' because Nix is not built with S3 support", request.uri);
@@ -859,7 +859,7 @@ void FileTransfer::download(FileTransferRequest && request, Sink & sink)
 }
 
 template<typename... Args>
-FileTransferError::FileTransferError(FileTransfer::Error error, std::shared_ptr<string> response, const Args & ... args)
+FileTransferError::FileTransferError(FileTransfer::Error error, std::optional<std::string> response, const Args & ... args)
     : Error(args...), error(error), response(response)
 {
     const auto hf = hintfmt(args...);
diff --git a/src/libstore/filetransfer.hh b/src/libstore/filetransfer.hh
index 45d9ccf89..3e61b23b1 100644
--- a/src/libstore/filetransfer.hh
+++ b/src/libstore/filetransfer.hh
@@ -59,7 +59,7 @@ struct FileTransferRequest
     unsigned int baseRetryTimeMs = 250;
     ActivityId parentAct;
     bool decompress = true;
-    std::shared_ptr<std::string> data;
+    std::optional<std::string> data;
     std::string mimeType;
     std::function<void(std::string_view data)> dataCallback;
 
@@ -77,7 +77,7 @@ struct FileTransferResult
     bool cached = false;
     std::string etag;
     std::string effectiveUri;
-    std::shared_ptr<std::string> data;
+    std::string data;
     uint64_t bodySize = 0;
 };
 
@@ -119,10 +119,10 @@ class FileTransferError : public Error
 {
 public:
     FileTransfer::Error error;
-    std::shared_ptr<string> response; // intentionally optional
+    std::optional<string> response; // intentionally optional
 
     template<typename... Args>
-    FileTransferError(FileTransfer::Error error, std::shared_ptr<string> response, const Args & ... args);
+    FileTransferError(FileTransfer::Error error, std::optional<string> response, const Args & ... args);
 
     virtual const char* sname() const override { return "FileTransferError"; }
 };
diff --git a/src/libstore/http-binary-cache-store.cc b/src/libstore/http-binary-cache-store.cc
index 605ec4b28..3cb5efdbf 100644
--- a/src/libstore/http-binary-cache-store.cc
+++ b/src/libstore/http-binary-cache-store.cc
@@ -126,7 +126,7 @@ protected:
         const std::string & mimeType) override
     {
         auto req = makeRequest(path);
-        req.data = std::make_shared<string>(StreamToSourceAdapter(istream).drain());
+        req.data = StreamToSourceAdapter(istream).drain();
         req.mimeType = mimeType;
         try {
             getFileTransfer()->upload(req);
@@ -159,7 +159,7 @@ protected:
     }
 
     void getFile(const std::string & path,
-        Callback<std::shared_ptr<std::string>> callback) noexcept override
+        Callback<std::optional<std::string>> callback) noexcept override
     {
         checkEnabled();
 
@@ -170,10 +170,10 @@ protected:
         getFileTransfer()->enqueueFileTransfer(request,
             {[callbackPtr, this](std::future<FileTransferResult> result) {
                 try {
-                    (*callbackPtr)(result.get().data);
+                    (*callbackPtr)(std::move(result.get().data));
                 } catch (FileTransferError & e) {
                     if (e.error == FileTransfer::NotFound || e.error == FileTransfer::Forbidden)
-                        return (*callbackPtr)(std::shared_ptr<std::string>());
+                        return (*callbackPtr)({});
                     maybeDisable();
                     callbackPtr->rethrow();
                 } catch (...) {
diff --git a/src/libstore/legacy-ssh-store.cc b/src/libstore/legacy-ssh-store.cc
index 4861d185e..f8b2662af 100644
--- a/src/libstore/legacy-ssh-store.cc
+++ b/src/libstore/legacy-ssh-store.cc
@@ -94,7 +94,7 @@ struct LegacySSHStore : public virtual LegacySSHStoreConfig, public virtual Stor
                 conn->sshConn->in.close();
                 auto msg = conn->from.drain();
                 throw Error("'nix-store --serve' protocol mismatch from '%s', got '%s'",
-                    host, chomp(*saved.s + msg));
+                    host, chomp(saved.s + msg));
             }
             conn->remoteVersion = readInt(conn->from);
             if (GET_PROTOCOL_MAJOR(conn->remoteVersion) != 0x200)
diff --git a/src/libstore/local-fs-store.cc b/src/libstore/local-fs-store.cc
index 6de13c73a..c933251db 100644
--- a/src/libstore/local-fs-store.cc
+++ b/src/libstore/local-fs-store.cc
@@ -87,34 +87,32 @@ void LocalFSStore::narFromPath(const StorePath & path, Sink & sink)
 
 const string LocalFSStore::drvsLogDir = "drvs";
 
-
-
-std::shared_ptr<std::string> LocalFSStore::getBuildLog(const StorePath & path_)
+std::optional<std::string> LocalFSStore::getBuildLog(const StorePath & path_)
 {
     auto path = path_;
 
     if (!path.isDerivation()) {
         try {
             auto info = queryPathInfo(path);
-            if (!info->deriver) return nullptr;
+            if (!info->deriver) return std::nullopt;
             path = *info->deriver;
         } catch (InvalidPath &) {
-            return nullptr;
+            return std::nullopt;
         }
     }
 
-    auto baseName = std::string(baseNameOf(printStorePath(path)));
+    auto baseName = path.to_string();
 
     for (int j = 0; j < 2; j++) {
 
         Path logPath =
             j == 0
-            ? fmt("%s/%s/%s/%s", logDir, drvsLogDir, string(baseName, 0, 2), string(baseName, 2))
+            ? fmt("%s/%s/%s/%s", logDir, drvsLogDir, baseName.substr(0, 2), baseName.substr(2))
             : fmt("%s/%s/%s", logDir, drvsLogDir, baseName);
         Path logBz2Path = logPath + ".bz2";
 
         if (pathExists(logPath))
-            return std::make_shared<std::string>(readFile(logPath));
+            return readFile(logPath);
 
         else if (pathExists(logBz2Path)) {
             try {
@@ -124,7 +122,7 @@ std::shared_ptr<std::string> LocalFSStore::getBuildLog(const StorePath & path_)
 
     }
 
-    return nullptr;
+    return std::nullopt;
 }
 
 }
diff --git a/src/libstore/local-fs-store.hh b/src/libstore/local-fs-store.hh
index f8b19d00d..e44b27cc2 100644
--- a/src/libstore/local-fs-store.hh
+++ b/src/libstore/local-fs-store.hh
@@ -45,7 +45,8 @@ public:
         return getRealStoreDir() + "/" + std::string(storePath, storeDir.size() + 1);
     }
 
-    std::shared_ptr<std::string> getBuildLog(const StorePath & path) override;
+    std::optional<std::string> getBuildLog(const StorePath & path) override;
+
 };
 
 }
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 9ebdfd6ed..d3cebe720 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -1461,12 +1461,12 @@ StorePath LocalStore::addTextToStore(const string & name, const string & s,
 
             StringSink sink;
             dumpString(s, sink);
-            auto narHash = hashString(htSHA256, *sink.s);
+            auto narHash = hashString(htSHA256, sink.s);
 
             optimisePath(realPath, repair);
 
             ValidPathInfo info { dstPath, narHash };
-            info.narSize = sink.s->size();
+            info.narSize = sink.s.size();
             info.references = references;
             info.ca = TextHash { .hash = hash };
             registerValidPath(info);
diff --git a/src/libstore/nar-accessor.cc b/src/libstore/nar-accessor.cc
index 784ebb719..7d27d7667 100644
--- a/src/libstore/nar-accessor.cc
+++ b/src/libstore/nar-accessor.cc
@@ -28,7 +28,7 @@ struct NarMember
 
 struct NarAccessor : public FSAccessor
 {
-    std::shared_ptr<const std::string> nar;
+    std::optional<const std::string> nar;
 
     GetNarBytes getNarBytes;
 
@@ -104,7 +104,7 @@ struct NarAccessor : public FSAccessor
         }
     };
 
-    NarAccessor(ref<const std::string> nar) : nar(nar)
+    NarAccessor(std::string && _nar) : nar(_nar)
     {
         StringSource source(*nar);
         NarIndexer indexer(*this, source);
@@ -224,9 +224,9 @@ struct NarAccessor : public FSAccessor
     }
 };
 
-ref<FSAccessor> makeNarAccessor(ref<const std::string> nar)
+ref<FSAccessor> makeNarAccessor(std::string && nar)
 {
-    return make_ref<NarAccessor>(nar);
+    return make_ref<NarAccessor>(std::move(nar));
 }
 
 ref<FSAccessor> makeNarAccessor(Source & source)
diff --git a/src/libstore/nar-accessor.hh b/src/libstore/nar-accessor.hh
index 8af1272f6..c2241a04c 100644
--- a/src/libstore/nar-accessor.hh
+++ b/src/libstore/nar-accessor.hh
@@ -10,7 +10,7 @@ struct Source;
 
 /* Return an object that provides access to the contents of a NAR
    file. */
-ref<FSAccessor> makeNarAccessor(ref<const std::string> nar);
+ref<FSAccessor> makeNarAccessor(std::string && nar);
 
 ref<FSAccessor> makeNarAccessor(Source & source);
 
diff --git a/src/libstore/remote-fs-accessor.cc b/src/libstore/remote-fs-accessor.cc
index f43456f0b..0ce335646 100644
--- a/src/libstore/remote-fs-accessor.cc
+++ b/src/libstore/remote-fs-accessor.cc
@@ -22,9 +22,18 @@ Path RemoteFSAccessor::makeCacheFile(std::string_view hashPart, const std::strin
     return fmt("%s/%s.%s", cacheDir, hashPart, ext);
 }
 
-void RemoteFSAccessor::addToCache(std::string_view hashPart, const std::string & nar,
-    ref<FSAccessor> narAccessor)
+ref<FSAccessor> RemoteFSAccessor::addToCache(std::string_view hashPart, std::string && nar)
 {
+    if (cacheDir != "") {
+        try {
+            /* FIXME: do this asynchronously. */
+            writeFile(makeCacheFile(hashPart, "nar"), nar);
+        } catch (...) {
+            ignoreException();
+        }
+    }
+
+    auto narAccessor = makeNarAccessor(std::move(nar));
     nars.emplace(hashPart, narAccessor);
 
     if (cacheDir != "") {
@@ -33,14 +42,12 @@ void RemoteFSAccessor::addToCache(std::string_view hashPart, const std::string &
             JSONPlaceholder jsonRoot(str);
             listNar(jsonRoot, narAccessor, "", true);
             writeFile(makeCacheFile(hashPart, "ls"), str.str());
-
-            /* FIXME: do this asynchronously. */
-            writeFile(makeCacheFile(hashPart, "nar"), nar);
-
         } catch (...) {
             ignoreException();
         }
     }
+
+    return narAccessor;
 }
 
 std::pair<ref<FSAccessor>, Path> RemoteFSAccessor::fetch(const Path & path_, bool requireValidPath)
@@ -55,7 +62,6 @@ std::pair<ref<FSAccessor>, Path> RemoteFSAccessor::fetch(const Path & path_, boo
     auto i = nars.find(std::string(storePath.hashPart()));
     if (i != nars.end()) return {i->second, restPath};
 
-    StringSink sink;
     std::string listing;
     Path cacheFile;
 
@@ -86,19 +92,15 @@ std::pair<ref<FSAccessor>, Path> RemoteFSAccessor::fetch(const Path & path_, boo
         } catch (SysError &) { }
 
         try {
-            *sink.s = nix::readFile(cacheFile);
-
-            auto narAccessor = makeNarAccessor(sink.s);
+            auto narAccessor = makeNarAccessor(nix::readFile(cacheFile));
             nars.emplace(storePath.hashPart(), narAccessor);
             return {narAccessor, restPath};
-
         } catch (SysError &) { }
     }
 
+    StringSink sink;
     store->narFromPath(storePath, sink);
-    auto narAccessor = makeNarAccessor(sink.s);
-    addToCache(storePath.hashPart(), *sink.s, narAccessor);
-    return {narAccessor, restPath};
+    return {addToCache(storePath.hashPart(), std::move(sink.s)), restPath};
 }
 
 FSAccessor::Stat RemoteFSAccessor::stat(const Path & path)
diff --git a/src/libstore/remote-fs-accessor.hh b/src/libstore/remote-fs-accessor.hh
index 594852d0e..99f5544ef 100644
--- a/src/libstore/remote-fs-accessor.hh
+++ b/src/libstore/remote-fs-accessor.hh
@@ -20,8 +20,7 @@ class RemoteFSAccessor : public FSAccessor
 
     Path makeCacheFile(std::string_view hashPart, const std::string & ext);
 
-    void addToCache(std::string_view hashPart, const std::string & nar,
-        ref<FSAccessor> narAccessor);
+    ref<FSAccessor> addToCache(std::string_view hashPart, std::string && nar);
 
 public:
 
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index 57cc260b0..6886103e1 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -172,7 +172,7 @@ void RemoteStore::initConnection(Connection & conn)
                it. */
             conn.closeWrite();
             auto msg = conn.from.drain();
-            throw Error("protocol mismatch, got '%s'", chomp(*saved.s + msg));
+            throw Error("protocol mismatch, got '%s'", chomp(saved.s + msg));
         }
 
         conn.from >> conn.daemonVersion;
diff --git a/src/libstore/s3-binary-cache-store.cc b/src/libstore/s3-binary-cache-store.cc
index 7accad7f4..a024e971d 100644
--- a/src/libstore/s3-binary-cache-store.cc
+++ b/src/libstore/s3-binary-cache-store.cc
@@ -385,7 +385,7 @@ struct S3BinaryCacheStoreImpl : virtual S3BinaryCacheStoreConfig, public virtual
         auto compress = [&](std::string compression)
         {
             auto compressed = nix::compress(compression, StreamToSourceAdapter(istream).drain());
-            return std::make_shared<std::stringstream>(std::move(*compressed));
+            return std::make_shared<std::stringstream>(std::move(compressed));
         };
 
         if (narinfoCompression != "" && hasSuffix(path, ".narinfo"))
diff --git a/src/libstore/s3.hh b/src/libstore/s3.hh
index 2042bffcf..3f55c74db 100644
--- a/src/libstore/s3.hh
+++ b/src/libstore/s3.hh
@@ -4,6 +4,8 @@
 
 #include "ref.hh"
 
+#include <optional>
+
 namespace Aws { namespace Client { class ClientConfiguration; } }
 namespace Aws { namespace S3 { class S3Client; } }
 
@@ -20,7 +22,7 @@ struct S3Helper
 
     struct FileTransferResult
     {
-        std::shared_ptr<std::string> data;
+        std::optional<std::string> data;
         unsigned int durationMs;
     };
 
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 3dd446f23..3567dcd1c 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -724,8 +724,8 @@ public:
 
     /* Return the build log of the specified store path, if available,
        or null otherwise. */
-    virtual std::shared_ptr<std::string> getBuildLog(const StorePath & path)
-    { return nullptr; }
+    virtual std::optional<std::string> getBuildLog(const StorePath & path)
+    { return std::nullopt; }
 
     /* Hack to allow long-running processes like hydra-queue-runner to
        occasionally flush their path info cache. */
diff --git a/src/libutil/compression.cc b/src/libutil/compression.cc
index f80ca664c..89180e7a7 100644
--- a/src/libutil/compression.cc
+++ b/src/libutil/compression.cc
@@ -190,13 +190,13 @@ struct BrotliDecompressionSink : ChunkedCompressionSink
     }
 };
 
-ref<std::string> decompress(const std::string & method, const std::string & in)
+std::string decompress(const std::string & method, std::string_view in)
 {
     StringSink ssink;
     auto sink = makeDecompressionSink(method, ssink);
     (*sink)(in);
     sink->finish();
-    return ssink.s;
+    return std::move(ssink.s);
 }
 
 std::unique_ptr<FinishSink> makeDecompressionSink(const std::string & method, Sink & nextSink)
@@ -281,13 +281,13 @@ ref<CompressionSink> makeCompressionSink(const std::string & method, Sink & next
         throw UnknownCompressionMethod("unknown compression method '%s'", method);
 }
 
-ref<std::string> compress(const std::string & method, const std::string & in, const bool parallel, int level)
+std::string compress(const std::string & method, std::string_view in, const bool parallel, int level)
 {
     StringSink ssink;
     auto sink = makeCompressionSink(method, ssink, parallel, level);
     (*sink)(in);
     sink->finish();
-    return ssink.s;
+    return std::move(ssink.s);
 }
 
 }
diff --git a/src/libutil/compression.hh b/src/libutil/compression.hh
index 9b1e4a9d4..c470b82a5 100644
--- a/src/libutil/compression.hh
+++ b/src/libutil/compression.hh
@@ -15,11 +15,11 @@ struct CompressionSink : BufferedSink, FinishSink
     using FinishSink::finish;
 };
 
-ref<std::string> decompress(const std::string & method, const std::string & in);
+std::string decompress(const std::string & method, std::string_view in);
 
 std::unique_ptr<FinishSink> makeDecompressionSink(const std::string & method, Sink & nextSink);
 
-ref<std::string> compress(const std::string & method, const std::string & in, const bool parallel = false, int level = -1);
+std::string compress(const std::string & method, std::string_view in, const bool parallel = false, int level = -1);
 
 ref<CompressionSink> makeCompressionSink(const std::string & method, Sink & nextSink, const bool parallel = false, int level = -1);
 
diff --git a/src/libutil/serialise.cc b/src/libutil/serialise.cc
index 704359b4a..fe703de06 100644
--- a/src/libutil/serialise.cc
+++ b/src/libutil/serialise.cc
@@ -110,7 +110,7 @@ std::string Source::drain()
 {
     StringSink s;
     drainInto(s);
-    return *s.s;
+    return std::move(s.s);
 }
 
 
@@ -450,11 +450,11 @@ Error readError(Source & source)
 void StringSink::operator () (std::string_view data)
 {
     static bool warned = false;
-    if (!warned && s->size() > threshold) {
+    if (!warned && s.size() > threshold) {
         warnLargeDump();
         warned = true;
     }
-    s->append(data);
+    s.append(data);
 }
 
 size_t ChainSource::read(char * data, size_t len)
diff --git a/src/libutil/serialise.hh b/src/libutil/serialise.hh
index e80fb9ecf..fdd35aa00 100644
--- a/src/libutil/serialise.hh
+++ b/src/libutil/serialise.hh
@@ -154,12 +154,13 @@ private:
 /* A sink that writes data to a string. */
 struct StringSink : Sink
 {
-    ref<std::string> s;
-    StringSink() : s(make_ref<std::string>()) { };
-    explicit StringSink(const size_t reservedSize) : s(make_ref<std::string>()) {
-      s->reserve(reservedSize);
+    std::string s;
+    StringSink() { }
+    explicit StringSink(const size_t reservedSize)
+    {
+      s.reserve(reservedSize);
     };
-    StringSink(ref<std::string> s) : s(s) { };
+    StringSink(std::string && s) : s(std::move(s)) { };
     void operator () (std::string_view data) override;
 };
 
diff --git a/src/libutil/tests/compression.cc b/src/libutil/tests/compression.cc
index 2efa3266b..bbbf3500f 100644
--- a/src/libutil/tests/compression.cc
+++ b/src/libutil/tests/compression.cc
@@ -12,17 +12,17 @@ namespace nix {
     }
 
     TEST(compress, noneMethodDoesNothingToTheInput) {
-        ref<std::string> o = compress("none", "this-is-a-test");
+        auto o = compress("none", "this-is-a-test");
 
-        ASSERT_EQ(*o, "this-is-a-test");
+        ASSERT_EQ(o, "this-is-a-test");
     }
 
     TEST(decompress, decompressNoneCompressed) {
         auto method = "none";
         auto str = "slfja;sljfklsa;jfklsjfkl;sdjfkl;sadjfkl;sdjf;lsdfjsadlf";
-        ref<std::string> o = decompress(method, str);
+        auto o = decompress(method, str);
 
-        ASSERT_EQ(*o, str);
+        ASSERT_EQ(o, str);
     }
 
     TEST(decompress, decompressEmptyCompressed) {
@@ -30,33 +30,33 @@ namespace nix {
         // (Content-Encoding == "").
         auto method = "";
         auto str = "slfja;sljfklsa;jfklsjfkl;sdjfkl;sadjfkl;sdjf;lsdfjsadlf";
-        ref<std::string> o = decompress(method, str);
+        auto o = decompress(method, str);
 
-        ASSERT_EQ(*o, str);
+        ASSERT_EQ(o, str);
     }
 
     TEST(decompress, decompressXzCompressed) {
         auto method = "xz";
         auto str = "slfja;sljfklsa;jfklsjfkl;sdjfkl;sadjfkl;sdjf;lsdfjsadlf";
-        ref<std::string> o = decompress(method, *compress(method, str));
+        auto o = decompress(method, compress(method, str));
 
-        ASSERT_EQ(*o, str);
+        ASSERT_EQ(o, str);
     }
 
     TEST(decompress, decompressBzip2Compressed) {
         auto method = "bzip2";
         auto str = "slfja;sljfklsa;jfklsjfkl;sdjfkl;sadjfkl;sdjf;lsdfjsadlf";
-        ref<std::string> o = decompress(method, *compress(method, str));
+        auto o = decompress(method, compress(method, str));
 
-        ASSERT_EQ(*o, str);
+        ASSERT_EQ(o, str);
     }
 
     TEST(decompress, decompressBrCompressed) {
         auto method = "br";
         auto str = "slfja;sljfklsa;jfklsjfkl;sdjfkl;sadjfkl;sdjf;lsdfjsadlf";
-        ref<std::string> o = decompress(method, *compress(method, str));
+        auto o = decompress(method, compress(method, str));
 
-        ASSERT_EQ(*o, str);
+        ASSERT_EQ(o, str);
     }
 
     TEST(decompress, decompressInvalidInputThrowsCompressionError) {
@@ -77,7 +77,7 @@ namespace nix {
         (*sink)(inputString);
         sink->finish();
 
-        ASSERT_STREQ((*strSink.s).c_str(), inputString);
+        ASSERT_STREQ(strSink.s.c_str(), inputString);
     }
 
     TEST(makeCompressionSink, compressAndDecompress) {
@@ -90,7 +90,7 @@ namespace nix {
         sink->finish();
         decompressionSink->finish();
 
-        ASSERT_STREQ((*strSink.s).c_str(), inputString);
+        ASSERT_STREQ(strSink.s.c_str(), inputString);
     }
 
 }
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 9edd69c64..f43161e33 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -670,7 +670,7 @@ string drainFD(int fd, bool block, const size_t reserveSize)
 {
     StringSink sink(reserveSize);
     drainFD(fd, sink, block);
-    return std::move(*sink.s);
+    return std::move(sink.s);
 }
 
 
@@ -1055,7 +1055,7 @@ std::pair<int, std::string> runProgram(RunOptions && options)
         status = e.status;
     }
 
-    return {status, std::move(*sink.s)};
+    return {status, std::move(sink.s)};
 }
 
 void runProgram2(const RunOptions & options)
diff --git a/src/nix/add-to-store.cc b/src/nix/add-to-store.cc
index 2ae042789..5168413d2 100644
--- a/src/nix/add-to-store.cc
+++ b/src/nix/add-to-store.cc
@@ -32,7 +32,7 @@ struct CmdAddToStore : MixDryRun, StoreCommand
         StringSink sink;
         dumpPath(path, sink);
 
-        auto narHash = hashString(htSHA256, *sink.s);
+        auto narHash = hashString(htSHA256, sink.s);
 
         Hash hash = narHash;
         if (ingestionMethod == FileIngestionMethod::Flat) {
@@ -45,14 +45,14 @@ struct CmdAddToStore : MixDryRun, StoreCommand
             store->makeFixedOutputPath(ingestionMethod, hash, *namePart),
             narHash,
         };
-        info.narSize = sink.s->size();
+        info.narSize = sink.s.size();
         info.ca = std::optional { FixedOutputHash {
             .method = ingestionMethod,
             .hash = hash,
         } };
 
         if (!dryRun) {
-            auto source = StringSource { *sink.s };
+            auto source = StringSource(sink.s);
             store->addToStore(info, source);
         }
 
diff --git a/src/nix/cat.cc b/src/nix/cat.cc
index e28ee3c50..6420a0f79 100644
--- a/src/nix/cat.cc
+++ b/src/nix/cat.cc
@@ -78,7 +78,7 @@ struct CmdCatNar : StoreCommand, MixCat
 
     void run(ref<Store> store) override
     {
-        cat(makeNarAccessor(make_ref<std::string>(readFile(narPath))));
+        cat(makeNarAccessor(readFile(narPath)));
     }
 };
 
diff --git a/src/nix/ls.cc b/src/nix/ls.cc
index c1dc9a95b..07554994b 100644
--- a/src/nix/ls.cc
+++ b/src/nix/ls.cc
@@ -157,7 +157,7 @@ struct CmdLsNar : Command, MixLs
 
     void run() override
     {
-        list(makeNarAccessor(make_ref<std::string>(readFile(narPath))));
+        list(makeNarAccessor(readFile(narPath)));
     }
 };
 
diff --git a/src/nix/make-content-addressable.cc b/src/nix/make-content-addressable.cc
index 12f303a10..2e75a3b61 100644
--- a/src/nix/make-content-addressable.cc
+++ b/src/nix/make-content-addressable.cc
@@ -61,10 +61,10 @@ struct CmdMakeContentAddressable : StorePathsCommand, MixJSON
                 }
             }
 
-            *sink.s = rewriteStrings(*sink.s, rewrites);
+            sink.s = rewriteStrings(sink.s, rewrites);
 
             HashModuloSink hashModuloSink(htSHA256, oldHashPart);
-            hashModuloSink(*sink.s);
+            hashModuloSink(sink.s);
 
             auto narHash = hashModuloSink.finish().first;
 
@@ -74,7 +74,7 @@ struct CmdMakeContentAddressable : StorePathsCommand, MixJSON
             };
             info.references = std::move(references);
             if (hasSelfReference) info.references.insert(info.path);
-            info.narSize = sink.s->size();
+            info.narSize = sink.s.size();
             info.ca = FixedOutputHash {
                 .method = FileIngestionMethod::Recursive,
                 .hash = info.narHash,
@@ -85,7 +85,7 @@ struct CmdMakeContentAddressable : StorePathsCommand, MixJSON
 
             auto source = sinkToSource([&](Sink & nextSink) {
                 RewritingSink rsink2(oldHashPart, std::string(info.path.hashPart()), nextSink);
-                rsink2(*sink.s);
+                rsink2(sink.s);
                 rsink2.flush();
             });
 
diff --git a/src/nix/profile.cc b/src/nix/profile.cc
index 96a20f673..9b7c999af 100644
--- a/src/nix/profile.cc
+++ b/src/nix/profile.cc
@@ -157,17 +157,17 @@ struct ProfileManifest
         StringSink sink;
         dumpPath(tempDir, sink);
 
-        auto narHash = hashString(htSHA256, *sink.s);
+        auto narHash = hashString(htSHA256, sink.s);
 
         ValidPathInfo info {
             store->makeFixedOutputPath(FileIngestionMethod::Recursive, narHash, "profile", references),
             narHash,
         };
         info.references = std::move(references);
-        info.narSize = sink.s->size();
+        info.narSize = sink.s.size();
         info.ca = FixedOutputHash { .method = FileIngestionMethod::Recursive, .hash = info.narHash };
 
-        auto source = StringSource { *sink.s };
+        StringSource source(sink.s);
         store->addToStore(info, source);
 
         return std::move(info.path);
diff --git a/src/nix/upgrade-nix.cc b/src/nix/upgrade-nix.cc
index 9cd567896..17a5a77ee 100644
--- a/src/nix/upgrade-nix.cc
+++ b/src/nix/upgrade-nix.cc
@@ -140,7 +140,7 @@ struct CmdUpgradeNix : MixDryRun, StoreCommand
 
         auto state = std::make_unique<EvalState>(Strings(), store);
         auto v = state->allocValue();
-        state->eval(state->parseExprFromString(*res.data, "/no-such-path"), *v);
+        state->eval(state->parseExprFromString(res.data, "/no-such-path"), *v);
         Bindings & bindings(*state->allocBindings(0));
         auto v2 = findAlongAttrPath(*state, settings.thisSystem, bindings, *v).first;
 

From 50be51d9a8792ea6ebbaca42ac9c4b233c58da2b Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 18 Jan 2022 13:50:25 +0100
Subject: [PATCH 421/567] Doh

---
 src/libstore/binary-cache-store.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index 8aec632e8..62869031b 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -498,10 +498,10 @@ std::optional<std::string> BinaryCacheStore::getBuildLog(const StorePath & path)
         try {
             auto info = queryPathInfo(path);
             // FIXME: add a "Log" field to .narinfo
-            if (!info->deriver) return nullptr;
+            if (!info->deriver) return std::nullopt;
             drvPath = *info->deriver;
         } catch (InvalidPath &) {
-            return nullptr;
+            return std::nullopt;
         }
     }
 

From f6f0bcf11ff79213f5ffa58d0e490901b2d3ce58 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 18 Jan 2022 14:06:51 +0100
Subject: [PATCH 422/567] Doh

---
 src/libstore/binary-cache-store.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index 62869031b..7d25e2160 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -371,7 +371,7 @@ void BinaryCacheStore::queryPathInfoUncached(const StorePath & storePath,
             try {
                 auto data = fut.get();
 
-                if (!data) return (*callbackPtr)(nullptr);
+                if (!data) return (*callbackPtr)({});
 
                 stats.narInfoRead++;
 
@@ -450,7 +450,7 @@ void BinaryCacheStore::queryRealisationUncached(const DrvOutput & id,
         [=](std::future<std::optional<std::string>> fut) {
             try {
                 auto data = fut.get();
-                if (!data) return (*callbackPtr)(nullptr);
+                if (!data) return (*callbackPtr)({});
 
                 auto realisation = Realisation::fromJSON(
                     nlohmann::json::parse(*data), outputInfoFilePath);

From 6448ea84ab537600d3f350867063bc305b3bb910 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 17 Jan 2022 13:58:26 +0100
Subject: [PATCH 423/567] Factor out --from / --to logic

---
 src/libcmd/command.cc | 54 +++++++++++++++++++++++++++++++++++++------
 src/libcmd/command.hh | 17 ++++++++++++++
 src/nix/copy.cc       | 39 ++-----------------------------
 3 files changed, 66 insertions(+), 44 deletions(-)

diff --git a/src/libcmd/command.cc b/src/libcmd/command.cc
index 429cd32cc..5e6d4a857 100644
--- a/src/libcmd/command.cc
+++ b/src/libcmd/command.cc
@@ -73,13 +73,16 @@ ref<Store> EvalCommand::getEvalStore()
 
 ref<EvalState> EvalCommand::getEvalState()
 {
-    if (!evalState) evalState =
-#if HAVE_BOEHMGC
-        std::allocate_shared<EvalState>(traceable_allocator<EvalState>(),
-#else
-        std::make_shared<EvalState>(
-#endif
-            searchPath, getEvalStore(), getStore());
+    if (!evalState)
+        evalState =
+            #if HAVE_BOEHMGC
+            std::allocate_shared<EvalState>(traceable_allocator<EvalState>(),
+                searchPath, getEvalStore(), getStore())
+            #else
+            std::make_shared<EvalState>(
+                searchPath, getEvalStore(), getStore())
+            #endif
+            ;
     return ref<EvalState>(evalState);
 }
 
@@ -156,6 +159,43 @@ void StorePathsCommand::run(ref<Store> store, BuiltPaths && paths)
     run(store, std::move(sorted));
 }
 
+CopyCommand::CopyCommand()
+    : BuiltPathsCommand(true)
+{
+    addFlag({
+        .longName = "from",
+        .description = "URL of the source Nix store.",
+        .labels = {"store-uri"},
+        .handler = {&srcUri},
+    });
+
+    addFlag({
+        .longName = "to",
+        .description = "URL of the destination Nix store.",
+        .labels = {"store-uri"},
+        .handler = {&dstUri},
+    });
+}
+
+ref<Store> CopyCommand::createStore()
+{
+    return srcUri.empty() ? StoreCommand::createStore() : openStore(srcUri);
+}
+
+void CopyCommand::run(ref<Store> store)
+{
+    if (srcUri.empty() && dstUri.empty())
+        throw UsageError("you must pass '--from' and/or '--to'");
+
+    BuiltPathsCommand::run(store);
+}
+
+void CopyCommand::run(ref<Store> srcStore, BuiltPaths && paths)
+{
+    ref<Store> dstStore = dstUri.empty() ? openStore() : openStore(dstUri);
+    run(srcStore, dstStore, std::move(paths));
+}
+
 void StorePathCommand::run(ref<Store> store, std::vector<StorePath> && storePaths)
 {
     if (storePaths.size() != 1)
diff --git a/src/libcmd/command.hh b/src/libcmd/command.hh
index 07f398468..0c3e29e25 100644
--- a/src/libcmd/command.hh
+++ b/src/libcmd/command.hh
@@ -176,6 +176,23 @@ public:
     bool useDefaultInstallables() override { return !all; }
 };
 
+/* A command that copies something between `--from` and `--to`
+   stores. */
+struct CopyCommand : virtual BuiltPathsCommand
+{
+    std::string srcUri, dstUri;
+
+    CopyCommand();
+
+    ref<Store> createStore() override;
+
+    void run(ref<Store> store) override;
+
+    void run(ref<Store> srcStore, BuiltPaths && paths) override;
+
+    virtual void run(ref<Store> srcStore, ref<Store> dstStore, BuiltPaths && paths) = 0;
+};
+
 struct StorePathsCommand : public BuiltPathsCommand
 {
     StorePathsCommand(bool recursive = false);
diff --git a/src/nix/copy.cc b/src/nix/copy.cc
index 197c85316..9f7cef304 100644
--- a/src/nix/copy.cc
+++ b/src/nix/copy.cc
@@ -1,17 +1,11 @@
 #include "command.hh"
 #include "shared.hh"
 #include "store-api.hh"
-#include "sync.hh"
-#include "thread-pool.hh"
-
-#include <atomic>
 
 using namespace nix;
 
-struct CmdCopy : BuiltPathsCommand
+struct CmdCopy : CopyCommand
 {
-    std::string srcUri, dstUri;
-
     CheckSigsFlag checkSigs = CheckSigs;
 
     SubstituteFlag substitute = NoSubstitute;
@@ -21,20 +15,6 @@ struct CmdCopy : BuiltPathsCommand
     CmdCopy()
         : BuiltPathsCommand(true)
     {
-        addFlag({
-            .longName = "from",
-            .description = "URL of the source Nix store.",
-            .labels = {"store-uri"},
-            .handler = {&srcUri},
-        });
-
-        addFlag({
-            .longName = "to",
-            .description = "URL of the destination Nix store.",
-            .labels = {"store-uri"},
-            .handler = {&dstUri},
-        });
-
         addFlag({
             .longName = "no-check-sigs",
             .description = "Do not require that paths are signed by trusted keys.",
@@ -65,23 +45,8 @@ struct CmdCopy : BuiltPathsCommand
 
     Category category() override { return catSecondary; }
 
-    ref<Store> createStore() override
+    void run(ref<Store> srcStore, ref<Store> dstStore, BuiltPaths && paths) override
     {
-        return srcUri.empty() ? StoreCommand::createStore() : openStore(srcUri);
-    }
-
-    void run(ref<Store> store) override
-    {
-        if (srcUri.empty() && dstUri.empty())
-            throw UsageError("you must pass '--from' and/or '--to'");
-
-        BuiltPathsCommand::run(store);
-    }
-
-    void run(ref<Store> srcStore, BuiltPaths && paths) override
-    {
-        ref<Store> dstStore = dstUri.empty() ? openStore() : openStore(dstUri);
-
         RealisedPath::Set stuffToCopy;
 
         for (auto & builtPath : paths) {

From 4dda1f92aae05dd9d633152458d65a3815bcd03c Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 17 Jan 2022 19:45:21 +0100
Subject: [PATCH 424/567] Add command 'nix store copy-log'

Fixes #5222.
---
 doc/manual/src/release-notes/rl-next.md |  2 +
 src/libcmd/command.cc                   | 67 +++++++++++--------------
 src/libcmd/command.hh                   | 30 +++++------
 src/libstore/daemon.cc                  | 26 ++++++++--
 src/libstore/local-store.cc             | 21 ++++++++
 src/libstore/local-store.hh             |  2 +
 src/libstore/remote-store.cc            | 12 +++++
 src/libstore/remote-store.hh            |  2 +
 src/libstore/store-api.hh               |  3 ++
 src/libstore/worker-protocol.hh         |  1 +
 src/nix/copy.cc                         |  6 ++-
 src/nix/store-copy-log.cc               | 40 +++++++++++++++
 src/nix/store-copy-log.md               | 13 +++++
 13 files changed, 165 insertions(+), 60 deletions(-)
 create mode 100644 src/nix/store-copy-log.cc
 create mode 100644 src/nix/store-copy-log.md

diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index f51969ced..adf3010c0 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -7,3 +7,5 @@
   set or toggle display of error traces.
 * New builtin function `builtins.zipAttrsWith` with same functionality
   as `lib.zipAttrsWith` from nixpkgs, but much more efficient.
+* New command `nix store copy-log` to copy build logs from one store
+  to another.
diff --git a/src/libcmd/command.cc b/src/libcmd/command.cc
index 5e6d4a857..6d183dfad 100644
--- a/src/libcmd/command.cc
+++ b/src/libcmd/command.cc
@@ -54,6 +54,36 @@ void StoreCommand::run()
     run(getStore());
 }
 
+CopyCommand::CopyCommand()
+{
+    addFlag({
+        .longName = "from",
+        .description = "URL of the source Nix store.",
+        .labels = {"store-uri"},
+        .handler = {&srcUri},
+    });
+
+    addFlag({
+        .longName = "to",
+        .description = "URL of the destination Nix store.",
+        .labels = {"store-uri"},
+        .handler = {&dstUri},
+    });
+}
+
+ref<Store> CopyCommand::createStore()
+{
+    return srcUri.empty() ? StoreCommand::createStore() : openStore(srcUri);
+}
+
+ref<Store> CopyCommand::getDstStore()
+{
+    if (srcUri.empty() && dstUri.empty())
+        throw UsageError("you must pass '--from' and/or '--to'");
+
+    return dstUri.empty() ? openStore() : openStore(dstUri);
+}
+
 EvalCommand::EvalCommand()
 {
 }
@@ -159,43 +189,6 @@ void StorePathsCommand::run(ref<Store> store, BuiltPaths && paths)
     run(store, std::move(sorted));
 }
 
-CopyCommand::CopyCommand()
-    : BuiltPathsCommand(true)
-{
-    addFlag({
-        .longName = "from",
-        .description = "URL of the source Nix store.",
-        .labels = {"store-uri"},
-        .handler = {&srcUri},
-    });
-
-    addFlag({
-        .longName = "to",
-        .description = "URL of the destination Nix store.",
-        .labels = {"store-uri"},
-        .handler = {&dstUri},
-    });
-}
-
-ref<Store> CopyCommand::createStore()
-{
-    return srcUri.empty() ? StoreCommand::createStore() : openStore(srcUri);
-}
-
-void CopyCommand::run(ref<Store> store)
-{
-    if (srcUri.empty() && dstUri.empty())
-        throw UsageError("you must pass '--from' and/or '--to'");
-
-    BuiltPathsCommand::run(store);
-}
-
-void CopyCommand::run(ref<Store> srcStore, BuiltPaths && paths)
-{
-    ref<Store> dstStore = dstUri.empty() ? openStore() : openStore(dstUri);
-    run(srcStore, dstStore, std::move(paths));
-}
-
 void StorePathCommand::run(ref<Store> store, std::vector<StorePath> && storePaths)
 {
     if (storePaths.size() != 1)
diff --git a/src/libcmd/command.hh b/src/libcmd/command.hh
index 0c3e29e25..bd2a0a7ee 100644
--- a/src/libcmd/command.hh
+++ b/src/libcmd/command.hh
@@ -43,6 +43,19 @@ private:
     std::shared_ptr<Store> _store;
 };
 
+/* A command that copies something between `--from` and `--to`
+   stores. */
+struct CopyCommand : virtual StoreCommand
+{
+    std::string srcUri, dstUri;
+
+    CopyCommand();
+
+    ref<Store> createStore() override;
+
+    ref<Store> getDstStore();
+};
+
 struct EvalCommand : virtual StoreCommand, MixEvalArgs
 {
     EvalCommand();
@@ -176,23 +189,6 @@ public:
     bool useDefaultInstallables() override { return !all; }
 };
 
-/* A command that copies something between `--from` and `--to`
-   stores. */
-struct CopyCommand : virtual BuiltPathsCommand
-{
-    std::string srcUri, dstUri;
-
-    CopyCommand();
-
-    ref<Store> createStore() override;
-
-    void run(ref<Store> store) override;
-
-    void run(ref<Store> srcStore, BuiltPaths && paths) override;
-
-    virtual void run(ref<Store> srcStore, ref<Store> dstStore, BuiltPaths && paths) = 0;
-};
-
 struct StorePathsCommand : public BuiltPathsCommand
 {
     StorePathsCommand(bool recursive = false);
diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index 5b817c587..101aa13a5 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -468,10 +468,12 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
             dontCheckSigs = false;
 
         logger->startWork();
-        FramedSource source(from);
-        store->addMultipleToStore(source,
-            RepairFlag{repair},
-            dontCheckSigs ? NoCheckSigs : CheckSigs);
+        {
+            FramedSource source(from);
+            store->addMultipleToStore(source,
+                RepairFlag{repair},
+                dontCheckSigs ? NoCheckSigs : CheckSigs);
+        }
         logger->stopWork();
         break;
     }
@@ -920,6 +922,22 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         break;
     }
 
+    case wopAddBuildLog: {
+        StorePath path{readString(from)};
+        logger->startWork();
+        if (!trusted)
+            throw Error("you are not privileged to add logs");
+        {
+            FramedSource source(from);
+            StringSink sink;
+            source.drainInto(sink);
+            store->addBuildLog(path, sink.s);
+        }
+        logger->stopWork();
+        to << 1;
+        break;
+    }
+
     default:
         throw Error("invalid operation %1%", op);
     }
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index d3cebe720..1807940d8 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -9,6 +9,7 @@
 #include "callback.hh"
 #include "topo-sort.hh"
 #include "finally.hh"
+#include "compression.hh"
 
 #include <iostream>
 #include <algorithm>
@@ -1898,4 +1899,24 @@ FixedOutputHash LocalStore::hashCAPath(
     };
 }
 
+void LocalStore::addBuildLog(const StorePath & drvPath, std::string_view log)
+{
+    assert(drvPath.isDerivation());
+
+    auto baseName = drvPath.to_string();
+
+    auto logPath = fmt("%s/%s/%s/%s.bz2", logDir, drvsLogDir, baseName.substr(0, 2), baseName.substr(2));
+
+    if (pathExists(logPath)) return;
+
+    createDirs(dirOf(logPath));
+
+    auto tmpFile = fmt("%s.tmp.%d", logPath, getpid());
+
+    writeFile(tmpFile, compress("bzip2", log));
+
+    if (rename(tmpFile.c_str(), logPath.c_str()) != 0)
+        throw SysError("renaming '%1%' to '%2%'", tmpFile, logPath);
+}
+
 }  // namespace nix
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index c4d7b80bd..6d867d778 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -280,6 +280,8 @@ private:
         const std::string_view pathHash
     );
 
+    void addBuildLog(const StorePath & drvPath, std::string_view log) override;
+
     friend struct LocalDerivationGoal;
     friend struct PathSubstitutionGoal;
     friend struct SubstitutionGoal;
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index 6886103e1..aac2965e0 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -908,6 +908,18 @@ void RemoteStore::queryMissing(const std::vector<DerivedPath> & targets,
 }
 
 
+void RemoteStore::addBuildLog(const StorePath & drvPath, std::string_view log)
+{
+    auto conn(getConnection());
+    conn->to << wopAddBuildLog << drvPath.to_string();
+    StringSource source(log);
+    conn.withFramedSink([&](Sink & sink) {
+        source.drainInto(sink);
+    });
+    readInt(conn->from);
+}
+
+
 void RemoteStore::connect()
 {
     auto conn(getConnection());
diff --git a/src/libstore/remote-store.hh b/src/libstore/remote-store.hh
index 0fd67f371..4754ff45a 100644
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@@ -116,6 +116,8 @@ public:
         StorePathSet & willBuild, StorePathSet & willSubstitute, StorePathSet & unknown,
         uint64_t & downloadSize, uint64_t & narSize) override;
 
+    void addBuildLog(const StorePath & drvPath, std::string_view log) override;
+
     void connect() override;
 
     unsigned int getProtocol() override;
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 3567dcd1c..07f45d1e9 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -727,6 +727,9 @@ public:
     virtual std::optional<std::string> getBuildLog(const StorePath & path)
     { return std::nullopt; }
 
+    virtual void addBuildLog(const StorePath & path, std::string_view log)
+    { unsupported("addBuildLog"); }
+
     /* Hack to allow long-running processes like hydra-queue-runner to
        occasionally flush their path info cache. */
     void clearPathInfoCache()
diff --git a/src/libstore/worker-protocol.hh b/src/libstore/worker-protocol.hh
index 93cf546d2..ecf42a5d0 100644
--- a/src/libstore/worker-protocol.hh
+++ b/src/libstore/worker-protocol.hh
@@ -56,6 +56,7 @@ typedef enum {
     wopRegisterDrvOutput = 42,
     wopQueryRealisation = 43,
     wopAddMultipleToStore = 44,
+    wopAddBuildLog = 45,
 } WorkerOp;
 
 
diff --git a/src/nix/copy.cc b/src/nix/copy.cc
index 9f7cef304..8730a9a5c 100644
--- a/src/nix/copy.cc
+++ b/src/nix/copy.cc
@@ -4,7 +4,7 @@
 
 using namespace nix;
 
-struct CmdCopy : CopyCommand
+struct CmdCopy : virtual CopyCommand, virtual BuiltPathsCommand
 {
     CheckSigsFlag checkSigs = CheckSigs;
 
@@ -45,8 +45,10 @@ struct CmdCopy : CopyCommand
 
     Category category() override { return catSecondary; }
 
-    void run(ref<Store> srcStore, ref<Store> dstStore, BuiltPaths && paths) override
+    void run(ref<Store> srcStore, BuiltPaths && paths) override
     {
+        auto dstStore = getDstStore();
+
         RealisedPath::Set stuffToCopy;
 
         for (auto & builtPath : paths) {
diff --git a/src/nix/store-copy-log.cc b/src/nix/store-copy-log.cc
new file mode 100644
index 000000000..fa6436cd0
--- /dev/null
+++ b/src/nix/store-copy-log.cc
@@ -0,0 +1,40 @@
+#include "command.hh"
+#include "shared.hh"
+#include "store-api.hh"
+#include "sync.hh"
+#include "thread-pool.hh"
+
+#include <atomic>
+
+using namespace nix;
+
+struct CmdCopyLog : virtual CopyCommand, virtual InstallablesCommand
+{
+    std::string description() override
+    {
+        return "copy build logs between Nix stores";
+    }
+
+    std::string doc() override
+    {
+        return
+          #include "store-copy-log.md"
+          ;
+    }
+
+    Category category() override { return catUtility; }
+
+    void run(ref<Store> srcStore) override
+    {
+        auto dstStore = getDstStore();
+
+        for (auto & path : toDerivations(srcStore, installables, true)) {
+            if (auto log = srcStore->getBuildLog(path))
+                dstStore->addBuildLog(path, *log);
+            else
+                throw Error("build log for '%s' is not available", srcStore->printStorePath(path));
+        }
+    }
+};
+
+static auto rCmdCopyLog = registerCommand2<CmdCopyLog>({"store", "copy-log"});
diff --git a/src/nix/store-copy-log.md b/src/nix/store-copy-log.md
new file mode 100644
index 000000000..f0cb66e57
--- /dev/null
+++ b/src/nix/store-copy-log.md
@@ -0,0 +1,13 @@
+R""(
+
+# Examples
+
+TODO
+
+# Description
+
+`nix store copy-log` copies build logs between two Nix stores. The
+source store is specified using `--from` and the destination using
+`--to`. If one of these is omitted, it defaults to the local store.
+
+)""

From 5b243a2b4bf88f41c87569773af84671ba83e890 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 18 Jan 2022 16:14:01 +0100
Subject: [PATCH 425/567] BinaryCacheStore: Implement addBuildLog()

---
 src/libstore/binary-cache-store.cc       | 10 ++++++++++
 src/libstore/binary-cache-store.hh       |  3 +++
 src/libstore/local-binary-cache-store.cc |  1 +
 3 files changed, 14 insertions(+)

diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index 7d25e2160..6e4458f7a 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -512,4 +512,14 @@ std::optional<std::string> BinaryCacheStore::getBuildLog(const StorePath & path)
     return getFile(logPath);
 }
 
+void BinaryCacheStore::addBuildLog(const StorePath & drvPath, std::string_view log)
+{
+    assert(drvPath.isDerivation());
+
+    upsertFile(
+        "log/" + std::string(drvPath.to_string()),
+        (std::string) log, // FIXME: don't copy
+        "text/plain; charset=utf-8");
+}
+
 }
diff --git a/src/libstore/binary-cache-store.hh b/src/libstore/binary-cache-store.hh
index 46ff67c77..7599230d9 100644
--- a/src/libstore/binary-cache-store.hh
+++ b/src/libstore/binary-cache-store.hh
@@ -51,6 +51,7 @@ public:
         const std::string & mimeType) = 0;
 
     void upsertFile(const std::string & path,
+        // FIXME: use std::string_view
         std::string && data,
         const std::string & mimeType);
 
@@ -120,6 +121,8 @@ public:
 
     std::optional<std::string> getBuildLog(const StorePath & path) override;
 
+    void addBuildLog(const StorePath & drvPath, std::string_view log) override;
+
 };
 
 MakeError(NoSuchBinaryCacheFile, Error);
diff --git a/src/libstore/local-binary-cache-store.cc b/src/libstore/local-binary-cache-store.cc
index f93111fce..f754770f9 100644
--- a/src/libstore/local-binary-cache-store.cc
+++ b/src/libstore/local-binary-cache-store.cc
@@ -96,6 +96,7 @@ void LocalBinaryCacheStore::init()
     createDirs(binaryCacheDir + "/" + realisationsPrefix);
     if (writeDebugInfo)
         createDirs(binaryCacheDir + "/debuginfo");
+    createDirs(binaryCacheDir + "/log");
     BinaryCacheStore::init();
 }
 

From 2ad2678c0baaa755becdbb7be82e2bb2e8ba1ada Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Tue, 18 Jan 2022 16:54:53 +0100
Subject: [PATCH 426/567] Add a simple test for `nix why-depends`

---
 tests/dependencies.nix |  2 ++
 tests/local.mk         |  3 ++-
 tests/why-depends.sh   | 13 +++++++++++++
 3 files changed, 17 insertions(+), 1 deletion(-)
 create mode 100644 tests/why-depends.sh

diff --git a/tests/dependencies.nix b/tests/dependencies.nix
index e320d81c9..45aca1793 100644
--- a/tests/dependencies.nix
+++ b/tests/dependencies.nix
@@ -27,6 +27,8 @@ let {
     input1 = input1 + "/.";
     input2 = "${input2}/.";
     input1_drv = input1;
+    input2_drv = input2;
+    input0_drv = input0;
     meta.description = "Random test package";
   };
 
diff --git a/tests/local.mk b/tests/local.mk
index 8580ecac9..93cf20d43 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -61,7 +61,8 @@ nix_tests = \
   ca/concurrent-builds.sh \
   ca/nix-copy.sh \
   eval-store.sh \
-  readfile-context.sh
+  readfile-context.sh \
+  why-depends.sh
   # parallel.sh
 
 ifeq ($(HAVE_LIBCPUID), 1)
diff --git a/tests/why-depends.sh b/tests/why-depends.sh
new file mode 100644
index 000000000..11b54b5b6
--- /dev/null
+++ b/tests/why-depends.sh
@@ -0,0 +1,13 @@
+source common.sh
+
+clearStore
+
+cp ./dependencies.nix ./dependencies.builder0.sh ./config.nix $TEST_HOME
+
+cd $TEST_HOME
+
+nix-build ./dependencies.nix -A input0_drv -o dep
+nix-build ./dependencies.nix -o toplevel
+
+nix why-depends ./toplevel ./dep |
+    grep input-2

From 3876238546c82e4cda4f257b9b1e3e6d53d07658 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 18 Jan 2022 17:28:18 +0100
Subject: [PATCH 427/567] Add Installable::toDrvPaths()

This is needed to get the path of a derivation that might not exist
(e.g. for 'nix store copy-log').

InstallableStorePath::toDerivedPaths() cannot be used for this because
it calls readDerivation(), so it fails if the store doesn't have the
derivation.
---
 src/libcmd/installables.cc | 39 +++++++++++++++++++++++++++++++-------
 src/libcmd/installables.hh | 11 +++++++++--
 src/nix/app.cc             |  2 +-
 src/nix/store-copy-log.cc  | 14 ++++++++++----
 4 files changed, 52 insertions(+), 14 deletions(-)

diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index 6c20bb7b1..0c2db0399 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -345,6 +345,18 @@ Installable::getCursor(EvalState & state)
     return cursors[0];
 }
 
+static StorePath getDeriver(
+    ref<Store> store,
+    const Installable & i,
+    const StorePath & drvPath)
+{
+    auto derivers = store->queryValidDerivers(drvPath);
+    if (derivers.empty())
+        throw Error("'%s' does not have a known deriver", i.what());
+    // FIXME: use all derivers?
+    return *derivers.begin();
+}
+
 struct InstallableStorePath : Installable
 {
     ref<Store> store;
@@ -353,7 +365,7 @@ struct InstallableStorePath : Installable
     InstallableStorePath(ref<Store> store, StorePath && storePath)
         : store(store), storePath(std::move(storePath)) { }
 
-    std::string what() override { return store->printStorePath(storePath); }
+    std::string what() const override { return store->printStorePath(storePath); }
 
     DerivedPaths toDerivedPaths() override
     {
@@ -374,6 +386,15 @@ struct InstallableStorePath : Installable
         }
     }
 
+    StorePathSet toDrvPaths(ref<Store> store) override
+    {
+        if (storePath.isDerivation()) {
+            return {storePath};
+        } else {
+            return {getDeriver(store, *this, storePath)};
+        }
+    }
+
     std::optional<StorePath> getStorePath() override
     {
         return storePath;
@@ -402,6 +423,14 @@ DerivedPaths InstallableValue::toDerivedPaths()
     return res;
 }
 
+StorePathSet InstallableValue::toDrvPaths(ref<Store> store)
+{
+    StorePathSet res;
+    for (auto & drv : toDerivations())
+        res.insert(drv.drvPath);
+    return res;
+}
+
 struct InstallableAttrPath : InstallableValue
 {
     SourceExprCommand & cmd;
@@ -412,7 +441,7 @@ struct InstallableAttrPath : InstallableValue
         : InstallableValue(state), cmd(cmd), v(allocRootValue(v)), attrPath(attrPath)
     { }
 
-    std::string what() override { return attrPath; }
+    std::string what() const override { return attrPath; }
 
     std::pair<Value *, Pos> toValue(EvalState & state) override
     {
@@ -836,11 +865,7 @@ StorePathSet toDerivations(
                 [&](const DerivedPath::Opaque & bo) {
                     if (!useDeriver)
                         throw Error("argument '%s' did not evaluate to a derivation", i->what());
-                    auto derivers = store->queryValidDerivers(bo.path);
-                    if (derivers.empty())
-                        throw Error("'%s' does not have a known deriver", i->what());
-                    // FIXME: use all derivers?
-                    drvPaths.insert(*derivers.begin());
+                    drvPaths.insert(getDeriver(store, *i, bo.path));
                 },
                 [&](const DerivedPath::Built & bfd) {
                     drvPaths.insert(bfd.drvPath);
diff --git a/src/libcmd/installables.hh b/src/libcmd/installables.hh
index 79931ad3e..ced6b3f10 100644
--- a/src/libcmd/installables.hh
+++ b/src/libcmd/installables.hh
@@ -33,10 +33,15 @@ struct Installable
 {
     virtual ~Installable() { }
 
-    virtual std::string what() = 0;
+    virtual std::string what() const = 0;
 
     virtual DerivedPaths toDerivedPaths() = 0;
 
+    virtual StorePathSet toDrvPaths(ref<Store> store)
+    {
+        throw Error("'%s' cannot be converted to a derivation path", what());
+    }
+
     DerivedPath toDerivedPath();
 
     UnresolvedApp toApp(EvalState & state);
@@ -81,6 +86,8 @@ struct InstallableValue : Installable
     virtual std::vector<DerivationInfo> toDerivations() = 0;
 
     DerivedPaths toDerivedPaths() override;
+
+    StorePathSet toDrvPaths(ref<Store> store) override;
 };
 
 struct InstallableFlake : InstallableValue
@@ -99,7 +106,7 @@ struct InstallableFlake : InstallableValue
         Strings && prefixes,
         const flake::LockFlags & lockFlags);
 
-    std::string what() override { return flakeRef.to_string() + "#" + *attrPaths.begin(); }
+    std::string what() const override { return flakeRef.to_string() + "#" + *attrPaths.begin(); }
 
     std::vector<std::string> getActualAttrPaths();
 
diff --git a/src/nix/app.cc b/src/nix/app.cc
index 2fcf4752c..e104cc9c1 100644
--- a/src/nix/app.cc
+++ b/src/nix/app.cc
@@ -19,7 +19,7 @@ struct InstallableDerivedPath : Installable
     }
 
 
-    std::string what() override { return derivedPath.to_string(*store); }
+    std::string what() const override { return derivedPath.to_string(*store); }
 
     DerivedPaths toDerivedPaths() override
     {
diff --git a/src/nix/store-copy-log.cc b/src/nix/store-copy-log.cc
index fa6436cd0..079cd6b3e 100644
--- a/src/nix/store-copy-log.cc
+++ b/src/nix/store-copy-log.cc
@@ -28,11 +28,17 @@ struct CmdCopyLog : virtual CopyCommand, virtual InstallablesCommand
     {
         auto dstStore = getDstStore();
 
-        for (auto & path : toDerivations(srcStore, installables, true)) {
-            if (auto log = srcStore->getBuildLog(path))
-                dstStore->addBuildLog(path, *log);
+        StorePathSet drvPaths;
+
+        for (auto & i : installables)
+            for (auto & drvPath : i->toDrvPaths(getEvalStore()))
+                drvPaths.insert(drvPath);
+
+        for (auto & drvPath : drvPaths) {
+            if (auto log = srcStore->getBuildLog(drvPath))
+                dstStore->addBuildLog(drvPath, *log);
             else
-                throw Error("build log for '%s' is not available", srcStore->printStorePath(path));
+                throw Error("build log for '%s' is not available", srcStore->printStorePath(drvPath));
         }
     }
 };

From 5fe1ec8a05f0074329dfe8ba13b55d583504e4ef Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 18 Jan 2022 17:30:50 +0100
Subject: [PATCH 428/567] Add a test for 'nix store copy-log' and 'nix log'

---
 tests/binary-cache.sh | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tests/binary-cache.sh b/tests/binary-cache.sh
index d7bc1507b..2368884f7 100644
--- a/tests/binary-cache.sh
+++ b/tests/binary-cache.sh
@@ -14,6 +14,17 @@ outPath=$(nix-build dependencies.nix --no-out-link)
 
 nix copy --to file://$cacheDir $outPath
 
+# Test copying build logs to the binary cache.
+nix log --store file://$cacheDir $outPath 2>&1 | grep 'is not available'
+nix store copy-log --to file://$cacheDir $outPath
+nix log --store file://$cacheDir $outPath | grep FOO
+rm -rf $TEST_ROOT/var/log/nix
+nix log $outPath 2>&1 | grep 'is not available'
+nix log --substituters file://$cacheDir $outPath | grep FOO
+
+# Test copying build logs from the binary cache.
+nix store copy-log --from file://$cacheDir $(nix-store -qd $outPath)
+nix log $outPath | grep FOO
 
 basicDownloadTests() {
     # No uploading tests bcause upload with force HTTP doesn't work.

From 04432f25101f0da74d8ba3bb0cbb6a9ea9501b7c Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 18 Jan 2022 17:35:41 +0100
Subject: [PATCH 429/567] Add examples

---
 src/nix/store-copy-log.md | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/nix/store-copy-log.md b/src/nix/store-copy-log.md
index f0cb66e57..19ae57079 100644
--- a/src/nix/store-copy-log.md
+++ b/src/nix/store-copy-log.md
@@ -2,7 +2,27 @@ R""(
 
 # Examples
 
-TODO
+* To copy the build log of the `hello` package from
+  https://cache.nixos.org to the local store:
+
+  ```console
+  # nix store copy-log --from https://cache.nixos.org --eval-store auto nixpkgs#hello
+  ```
+
+  You can verify that the log is available locally:
+
+  ```console
+  # nix log --substituters '' nixpkgs#hello
+  ```
+
+  (The flag `--substituters ''` avoids querying
+  `https://cache.nixos.org` for the log.)
+
+* To copy the log for a specific store derivation via SSH:
+
+  ```console
+  # nix store copy-log --to ssh-ng://machine /nix/store/ilgm50plpmcgjhcp33z6n4qbnpqfhxym-glibc-2.33-59.drv
+  ```
 
 # Description
 

From 3e5a9ad7ff15e5263d8b31288095ebd2e489b8e1 Mon Sep 17 00:00:00 2001
From: "lincoln auster [they/them]" <lincolnauster@gmail.com>
Date: Thu, 13 Jan 2022 13:01:04 -0700
Subject: [PATCH 430/567] allow modifying lockfile commit msg with nix config
 option

This allows setting the commit-lockfile-summary option to a non-empty
string to override the commit summary while leaving the body unchanged.
---
 src/libexpr/flake/flake.cc | 20 ++++++++++++++++----
 src/libstore/globals.hh    |  7 +++++++
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 190a128d7..0fbe9b960 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -633,12 +633,24 @@ LockedFlake lockFlake(
 
                         newLockFile.write(path);
 
+                        std::optional<std::string> commitMessage = std::nullopt;
+                        if (lockFlags.commitLockFile) {
+                            std::string cm;
+
+                            cm = settings.commitLockFileSummary.get();
+
+                            if (cm == "") {
+                                cm = fmt("%s: %s", relPath, lockFileExists ? "Update" : "Add");
+                            }
+
+                            cm += "\n\nFlake lock file updates:\n\n";
+                            cm += filterANSIEscapes(diff, true);
+                            commitMessage = cm;
+                        }
+
                         topRef.input.markChangedFile(
                             (topRef.subdir == "" ? "" : topRef.subdir + "/") + "flake.lock",
-                            lockFlags.commitLockFile
-                            ? std::optional<std::string>(fmt("%s: %s\n\nFlake lock file changes:\n\n%s",
-                                    relPath, lockFileExists ? "Update" : "Add", filterANSIEscapes(diff, true)))
-                            : std::nullopt);
+                            commitMessage);
 
                         /* Rewriting the lockfile changed the top-level
                            repo, so we should re-read it. FIXME: we could
diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index 1911ec855..f65893b10 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -966,6 +966,13 @@ public:
 
     Setting<bool> acceptFlakeConfig{this, false, "accept-flake-config",
         "Whether to accept nix configuration from a flake without prompting."};
+
+    Setting<std::string> commitLockFileSummary{
+        this, "", "commit-lockfile-summary",
+        R"(
+          The commit summary to use when commiting changed flake lock files. If
+          empty, the summary is generated based on the action performed.
+        )"};
 };
 
 

From 7d4f86f0321b70180fe7ad7686cd902c35567124 Mon Sep 17 00:00:00 2001
From: "lincoln auster [they/them]" <lincolnauster@gmail.com>
Date: Wed, 12 Jan 2022 10:05:28 -0700
Subject: [PATCH 431/567] release-notes: document commit-lockfile-summary
 option

This documents 3023c7700.
---
 doc/manual/src/release-notes/rl-next.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index adf3010c0..f20acbd3f 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -9,3 +9,7 @@
   as `lib.zipAttrsWith` from nixpkgs, but much more efficient.
 * New command `nix store copy-log` to copy build logs from one store
   to another.
+* The `commit-lockfile-summary` option can be set to a non-empty string
+  to override the commit summary used when commiting an updated lockfile.
+  This may be used in conjunction with the nixConfig attribute in
+  `flake.nix` to better conform to repository conventions.

From 0a7746603eda58c4b368e977e87d0aa4db397f5b Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Wed, 19 Jan 2022 13:39:42 +0100
Subject: [PATCH 432/567] remove ExprIndStr
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

it can be replaced with StringToken if we add another bit if information to
StringToken, namely whether this string should take part in indentation scanning
or not. since all escaping terminates indentation scanning we need to set this
bit only for the non-escaped IND_STRING rule.

this improves performance by about 1%.

 before

  nix search --no-eval-cache --offline ../nixpkgs hello
    Time (mean ± σ):      8.880 s ±  0.048 s    [User: 6.809 s, System: 1.643 s]
    Range (min … max):    8.781 s …  8.993 s    20 runs

  nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
    Time (mean ± σ):     375.0 ms ±   2.2 ms    [User: 339.8 ms, System: 35.2 ms]
    Range (min … max):   371.5 ms … 379.3 ms    20 runs

  nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
    Time (mean ± σ):      2.831 s ±  0.040 s    [User: 2.536 s, System: 0.225 s]
    Range (min … max):    2.769 s …  2.912 s    20 runs

 after

  nix search --no-eval-cache --offline ../nixpkgs hello
    Time (mean ± σ):      8.832 s ±  0.048 s    [User: 6.757 s, System: 1.657 s]
    Range (min … max):    8.743 s …  8.921 s    20 runs

  nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
    Time (mean ± σ):     367.4 ms ±   3.2 ms    [User: 332.7 ms, System: 34.7 ms]
    Range (min … max):   364.6 ms … 374.6 ms    20 runs

  nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
    Time (mean ± σ):      2.810 s ±  0.030 s    [User: 2.517 s, System: 0.225 s]
    Range (min … max):    2.742 s …  2.854 s    20 runs
---
 src/libexpr/lexer.l    | 18 ++++-----
 src/libexpr/nixexpr.hh |  7 ----
 src/libexpr/parser.y   | 86 +++++++++++++++++++++++-------------------
 3 files changed, 57 insertions(+), 54 deletions(-)

diff --git a/src/libexpr/lexer.l b/src/libexpr/lexer.l
index a0e7a1877..e276b0467 100644
--- a/src/libexpr/lexer.l
+++ b/src/libexpr/lexer.l
@@ -66,7 +66,7 @@ static void adjustLoc(YYLTYPE * loc, const char * s, size_t len)
 
 // we make use of the fact that the parser receives a private copy of the input
 // string and can munge around in it.
-static Expr * unescapeStr(SymbolTable & symbols, char * s, size_t length)
+static StringToken unescapeStr(SymbolTable & symbols, char * s, size_t length)
 {
     char * result = s;
     char * t = s;
@@ -89,7 +89,7 @@ static Expr * unescapeStr(SymbolTable & symbols, char * s, size_t length)
         else *t = c;
         t++;
     }
-    return new ExprString(symbols.create({result, size_t(t - result)}));
+    return {result, size_t(t - result)};
 }
 
 
@@ -176,7 +176,7 @@ or          { return OR_KW; }
                 /* It is impossible to match strings ending with '$' with one
                    regex because trailing contexts are only valid at the end
                    of a rule. (A sane but undocumented limitation.) */
-                yylval->e = unescapeStr(data->symbols, yytext, yyleng);
+                yylval->str = unescapeStr(data->symbols, yytext, yyleng);
                 return STR;
               }
 <STRING>\$\{  { PUSH_STATE(DEFAULT); return DOLLAR_CURLY; }
@@ -191,26 +191,26 @@ or          { return OR_KW; }
 
 \'\'(\ *\n)?     { PUSH_STATE(IND_STRING); return IND_STRING_OPEN; }
 <IND_STRING>([^\$\']|\$[^\{\']|\'[^\'\$])+ {
-                   yylval->e = new ExprIndStr(yytext);
+                   yylval->str = {yytext, (size_t) yyleng, true};
                    return IND_STR;
                  }
 <IND_STRING>\'\'\$ |
 <IND_STRING>\$   {
-                   yylval->e = new ExprIndStr("$");
+                   yylval->str = {"$", 1};
                    return IND_STR;
                  }
 <IND_STRING>\'\'\' {
-                   yylval->e = new ExprIndStr("''");
+                   yylval->str = {"''", 2};
                    return IND_STR;
                  }
 <IND_STRING>\'\'\\{ANY} {
-                   yylval->e = unescapeStr(data->symbols, yytext + 2, yyleng - 2);
+                   yylval->str = unescapeStr(data->symbols, yytext + 2, yyleng - 2);
                    return IND_STR;
                  }
 <IND_STRING>\$\{ { PUSH_STATE(DEFAULT); return DOLLAR_CURLY; }
 <IND_STRING>\'\' { POP_STATE(); return IND_STRING_CLOSE; }
 <IND_STRING>\'   {
-                   yylval->e = new ExprIndStr("'");
+                   yylval->str = {"'", 1};
                    return IND_STR;
                  }
 
@@ -264,7 +264,7 @@ or          { return OR_KW; }
       PUSH_STATE(INPATH_SLASH);
   else
       PUSH_STATE(INPATH);
-  yylval->e = new ExprString(data->symbols.create(string(yytext)));
+  yylval->str = {yytext, (size_t) yyleng};
   return STR;
 }
 <INPATH>{ANY} |
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index 0a60057e5..ae11560ea 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -117,13 +117,6 @@ struct ExprString : Expr
     Value * maybeThunk(EvalState & state, Env & env);
 };
 
-/* Temporary class used during parsing of indented strings. */
-struct ExprIndStr : Expr
-{
-    string s;
-    ExprIndStr(const string & s) : s(s) { };
-};
-
 struct ExprPath : Expr
 {
     string s;
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index a3e713937..38b218156 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -16,6 +16,8 @@
 #ifndef BISON_HEADER
 #define BISON_HEADER
 
+#include <variant>
+
 #include "util.hh"
 
 #include "nixexpr.hh"
@@ -41,6 +43,15 @@ namespace nix {
 
 }
 
+// using C a struct allows us to avoid having to define the special
+// members that using string_view here would implicitly delete.
+struct StringToken {
+  const char * p;
+  size_t l;
+  bool hasIndentation;
+  operator std::string_view() const { return {p, l}; }
+};
+
 #define YY_DECL int yylex \
     (YYSTYPE * yylval_param, YYLTYPE * yylloc_param, yyscan_t yyscanner, nix::ParseData * data)
 
@@ -152,7 +163,8 @@ static void addFormal(const Pos & pos, Formals * formals, const Formal & formal)
 }
 
 
-static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols, vector<std::pair<Pos, Expr *> > & es)
+static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols,
+    vector<std::pair<Pos, std::variant<Expr *, StringToken> > > & es)
 {
     if (es.empty()) return new ExprString(symbols.create(""));
 
@@ -163,20 +175,20 @@ static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols, vector<st
     size_t minIndent = 1000000;
     size_t curIndent = 0;
     for (auto & [i_pos, i] : es) {
-        ExprIndStr * e = dynamic_cast<ExprIndStr *>(i);
-        if (!e) {
-            /* Anti-quotations end the current start-of-line whitespace. */
+        auto * str = std::get_if<StringToken>(&i);
+        if (!str || !str->hasIndentation) {
+            /* Anti-quotations and escaped characters end the current start-of-line whitespace. */
             if (atStartOfLine) {
                 atStartOfLine = false;
                 if (curIndent < minIndent) minIndent = curIndent;
             }
             continue;
         }
-        for (size_t j = 0; j < e->s.size(); ++j) {
+        for (size_t j = 0; j < str->l; ++j) {
             if (atStartOfLine) {
-                if (e->s[j] == ' ')
+                if (str->p[j] == ' ')
                     curIndent++;
-                else if (e->s[j] == '\n') {
+                else if (str->p[j] == '\n') {
                     /* Empty line, doesn't influence minimum
                        indentation. */
                     curIndent = 0;
@@ -184,7 +196,7 @@ static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols, vector<st
                     atStartOfLine = false;
                     if (curIndent < minIndent) minIndent = curIndent;
                 }
-            } else if (e->s[j] == '\n') {
+            } else if (str->p[j] == '\n') {
                 atStartOfLine = true;
                 curIndent = 0;
             }
@@ -196,33 +208,31 @@ static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols, vector<st
     atStartOfLine = true;
     size_t curDropped = 0;
     size_t n = es.size();
-    for (vector<std::pair<Pos, Expr *> >::iterator i = es.begin(); i != es.end(); ++i, --n) {
-        ExprIndStr * e = dynamic_cast<ExprIndStr *>(i->second);
-        if (!e) {
-            atStartOfLine = false;
-            curDropped = 0;
-            es2->push_back(*i);
-            continue;
-        }
-
+    auto i = es.begin();
+    const auto trimExpr = [&] (Expr * e) {
+        atStartOfLine = false;
+        curDropped = 0;
+        es2->emplace_back(i->first, e);
+    };
+    const auto trimString = [&] (const StringToken & t) {
         string s2;
-        for (size_t j = 0; j < e->s.size(); ++j) {
+        for (size_t j = 0; j < t.l; ++j) {
             if (atStartOfLine) {
-                if (e->s[j] == ' ') {
+                if (t.p[j] == ' ') {
                     if (curDropped++ >= minIndent)
-                        s2 += e->s[j];
+                        s2 += t.p[j];
                 }
-                else if (e->s[j] == '\n') {
+                else if (t.p[j] == '\n') {
                     curDropped = 0;
-                    s2 += e->s[j];
+                    s2 += t.p[j];
                 } else {
                     atStartOfLine = false;
                     curDropped = 0;
-                    s2 += e->s[j];
+                    s2 += t.p[j];
                 }
             } else {
-                s2 += e->s[j];
-                if (e->s[j] == '\n') atStartOfLine = true;
+                s2 += t.p[j];
+                if (t.p[j] == '\n') atStartOfLine = true;
             }
         }
 
@@ -235,6 +245,9 @@ static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols, vector<st
         }
 
         es2->emplace_back(i->first, new ExprString(symbols.create(s2)));
+    };
+    for (; i != es.end(); ++i, --n) {
+        std::visit(overloaded { trimExpr, trimString }, i->second);
     }
 
     /* If this is a single string, then don't do a concatenation. */
@@ -273,18 +286,13 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * err
   nix::Formal * formal;
   nix::NixInt n;
   nix::NixFloat nf;
-  // using C a struct allows us to avoid having to define the special
-  // members that using string_view here would implicitly delete.
-  struct StringToken {
-    const char * p;
-    size_t l;
-    operator std::string_view() const { return {p, l}; }
-  };
   StringToken id; // !!! -> Symbol
   StringToken path;
   StringToken uri;
+  StringToken str;
   std::vector<nix::AttrName> * attrNames;
   std::vector<std::pair<nix::Pos, nix::Expr *> > * string_parts;
+  std::vector<std::pair<nix::Pos, std::variant<nix::Expr *, StringToken> > > * ind_string_parts;
 }
 
 %type <e> start expr expr_function expr_if expr_op
@@ -294,11 +302,12 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * err
 %type <formals> formals
 %type <formal> formal
 %type <attrNames> attrs attrpath
-%type <string_parts> string_parts_interpolated ind_string_parts
+%type <string_parts> string_parts_interpolated
+%type <ind_string_parts> ind_string_parts
 %type <e> path_start string_parts string_attr
 %type <id> attr
 %token <id> ID ATTRPATH
-%token <e> STR IND_STR
+%token <str> STR IND_STR
 %token <n> INT
 %token <nf> FLOAT
 %token <path> PATH HPATH SPATH PATH_END
@@ -449,18 +458,19 @@ expr_simple
   ;
 
 string_parts
-  : STR
+  : STR { $$ = new ExprString(data->symbols.create($1)); }
   | string_parts_interpolated { $$ = new ExprConcatStrings(CUR_POS, true, $1); }
   | { $$ = new ExprString(data->symbols.create("")); }
   ;
 
 string_parts_interpolated
-  : string_parts_interpolated STR { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $2); }
+  : string_parts_interpolated STR
+  { $$ = $1; $1->emplace_back(makeCurPos(@2, data), new ExprString(data->symbols.create($2))); }
   | string_parts_interpolated DOLLAR_CURLY expr '}' { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $3); }
   | DOLLAR_CURLY expr '}' { $$ = new vector<std::pair<Pos, Expr *> >; $$->emplace_back(makeCurPos(@1, data), $2); }
   | STR DOLLAR_CURLY expr '}' {
       $$ = new vector<std::pair<Pos, Expr *> >;
-      $$->emplace_back(makeCurPos(@1, data), $1);
+      $$->emplace_back(makeCurPos(@1, data), new ExprString(data->symbols.create($1)));
       $$->emplace_back(makeCurPos(@2, data), $3);
     }
   ;
@@ -482,7 +492,7 @@ path_start
 ind_string_parts
   : ind_string_parts IND_STR { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $2); }
   | ind_string_parts DOLLAR_CURLY expr '}' { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $3); }
-  | { $$ = new vector<std::pair<Pos, Expr *> >; }
+  | { $$ = new vector<std::pair<Pos, std::variant<Expr *, StringToken> > >; }
   ;
 
 binds

From dd7c2e0695b02639d8fe6c7bc050da14373b9513 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Wed, 19 Jan 2022 14:15:45 +0100
Subject: [PATCH 433/567] Make `nix why-depends` quieter by default

Unless `--precise` is passed, make `nix why-depends` only show the
dependencies between the store paths, without introspecting them to
find the actual references.

This also makes it ~3x faster
---
 src/nix/why-depends.cc         | 27 +++++++++++++++++++++------
 tests/dependencies.builder0.sh |  2 +-
 tests/gc.sh                    |  4 ++--
 tests/why-depends.sh           | 12 ++++++++++--
 4 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/src/nix/why-depends.cc b/src/nix/why-depends.cc
index dd43bd1c3..74377c912 100644
--- a/src/nix/why-depends.cc
+++ b/src/nix/why-depends.cc
@@ -31,6 +31,7 @@ struct CmdWhyDepends : SourceExprCommand
 {
     std::string _package, _dependency;
     bool all = false;
+    bool precise = false;
 
     CmdWhyDepends()
     {
@@ -56,6 +57,12 @@ struct CmdWhyDepends : SourceExprCommand
             .description = "Show all edges in the dependency graph leading from *package* to *dependency*, rather than just a shortest path.",
             .handler = {&all, true},
         });
+
+        addFlag({
+            .longName = "precise",
+            .description = "For each edge of the graph, inspect the parent node to display the exact location in the path that causes the dependency",
+            .handler = {&precise, true},
+        });
     }
 
     std::string description() override
@@ -158,11 +165,19 @@ struct CmdWhyDepends : SourceExprCommand
             auto pathS = store->printStorePath(node.path);
 
             assert(node.dist != inf);
-            logger->cout("%s%s%s%s" ANSI_NORMAL,
-                firstPad,
-                node.visited ? "\e[38;5;244m" : "",
-                firstPad != "" ? "→ " : "",
-                pathS);
+            if (precise) {
+                logger->cout("%s%s%s%s" ANSI_NORMAL,
+                    firstPad,
+                    node.visited ? "\e[38;5;244m" : "",
+                    firstPad != "" ? "→ " : "",
+                    pathS);
+            } else {
+                logger->cout("%s%s%s%s" ANSI_NORMAL,
+                    firstPad,
+                    node.visited ? "\e[38;5;244m" : "",
+                    firstPad != "" ? treeLast : "",
+                    pathS);
+            }
 
             if (node.path == dependencyPath && !all
                 && packagePath != dependencyPath)
@@ -237,7 +252,7 @@ struct CmdWhyDepends : SourceExprCommand
 
             // FIXME: should use scanForReferences().
 
-            visitPath(pathS);
+            if (precise) visitPath(pathS);
 
             for (auto & ref : refs) {
                 std::string hash(ref.second->path.hashPart());
diff --git a/tests/dependencies.builder0.sh b/tests/dependencies.builder0.sh
index c37bf909a..9b11576e0 100644
--- a/tests/dependencies.builder0.sh
+++ b/tests/dependencies.builder0.sh
@@ -4,7 +4,7 @@
 mkdir $out
 echo $(cat $input1/foo)$(cat $input2/bar) > $out/foobar
 
-ln -s $input2 $out/input-2
+ln -s $input2 $out/reference-to-input-2
 
 # Self-reference.
 ln -s $out $out/self
diff --git a/tests/gc.sh b/tests/gc.sh
index a736b63db..ad09a8b39 100644
--- a/tests/gc.sh
+++ b/tests/gc.sh
@@ -18,7 +18,7 @@ if nix-store --gc --print-dead | grep -E $outPath$; then false; fi
 
 nix-store --gc --print-dead
 
-inUse=$(readLink $outPath/input-2)
+inUse=$(readLink $outPath/reference-to-input-2)
 if nix-store --delete $inUse; then false; fi
 test -e $inUse
 
@@ -35,7 +35,7 @@ nix-collect-garbage
 
 # Check that the root and its dependencies haven't been deleted.
 cat $outPath/foobar
-cat $outPath/input-2/bar
+cat $outPath/reference-to-input-2/bar
 
 # Check that the derivation has been GC'd.
 if test -e $drvPath; then false; fi
diff --git a/tests/why-depends.sh b/tests/why-depends.sh
index 11b54b5b6..c12941e76 100644
--- a/tests/why-depends.sh
+++ b/tests/why-depends.sh
@@ -9,5 +9,13 @@ cd $TEST_HOME
 nix-build ./dependencies.nix -A input0_drv -o dep
 nix-build ./dependencies.nix -o toplevel
 
-nix why-depends ./toplevel ./dep |
-    grep input-2
+FAST_WHY_DEPENDS_OUTPUT=$(nix why-depends ./toplevel ./dep)
+PRECISE_WHY_DEPENDS_OUTPUT=$(nix why-depends ./toplevel ./dep --precise)
+
+# Both outputs should show that `input-2` is in the dependency chain
+echo "$FAST_WHY_DEPENDS_OUTPUT" | grep -q input-2
+echo "$PRECISE_WHY_DEPENDS_OUTPUT" | grep -q input-2
+
+# But only the “precise” one should refere to `reference-to-input-2`
+echo "$FAST_WHY_DEPENDS_OUTPUT" | (! grep -q reference-to-input-2)
+echo "$PRECISE_WHY_DEPENDS_OUTPUT" | grep -q reference-to-input-2

From e36add56cf094388dc450fa31723d05dad1a4947 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Wed, 19 Jan 2022 14:37:54 +0100
Subject: [PATCH 434/567] Fix the build with nlohmann/json 3.10.4+

---
 src/libstore/realisation.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libstore/realisation.cc b/src/libstore/realisation.cc
index f871e6437..d63ec5ea2 100644
--- a/src/libstore/realisation.cc
+++ b/src/libstore/realisation.cc
@@ -78,7 +78,7 @@ Realisation Realisation::fromJSON(
         auto fieldIterator = json.find(fieldName);
         if (fieldIterator == json.end())
             return std::nullopt;
-        return *fieldIterator;
+        return {*fieldIterator};
     };
     auto getField = [&](std::string fieldName) -> std::string {
         if (auto field = getOptionalField(fieldName))

From 9ac836d1d6d7e3480ad3bc4dbe23286d9052052b Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Wed, 19 Jan 2022 14:31:30 +0100
Subject: [PATCH 435/567] don't use Symbols for strings
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

string expressions by and large do not need the benefits a Symbol gives us,
instead they pollute the symbol table and cause unnecessary overhead for almost
all strings. the one place we can think of that benefits from them (attrpaths
with expressions) extracts the benefit in the parser, which we'll have to touch
anyway when changing ExprString to hold strings.

this gives a sizeable improvement on of 3-5% on all benchmarks we've run.

 before

  nix search --no-eval-cache --offline ../nixpkgs hello
    Time (mean ± σ):      8.844 s ±  0.045 s    [User: 6.750 s, System: 1.663 s]
    Range (min … max):    8.758 s …  8.922 s    20 runs

  nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
    Time (mean ± σ):     367.4 ms ±   3.3 ms    [User: 332.3 ms, System: 35.2 ms]
    Range (min … max):   364.0 ms … 375.2 ms    20 runs

  nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
    Time (mean ± σ):      2.810 s ±  0.030 s    [User: 2.517 s, System: 0.225 s]
    Range (min … max):    2.742 s …  2.854 s    20 runs

 after

  nix search --no-eval-cache --offline ../nixpkgs hello
    Time (mean ± σ):      8.533 s ±  0.068 s    [User: 6.485 s, System: 1.642 s]
    Range (min … max):    8.404 s …  8.657 s    20 runs

  nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
    Time (mean ± σ):     347.6 ms ±   3.1 ms    [User: 313.1 ms, System: 34.5 ms]
    Range (min … max):   343.3 ms … 354.6 ms    20 runs

  nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
    Time (mean ± σ):      2.709 s ±  0.032 s    [User: 2.414 s, System: 0.232 s]
    Range (min … max):    2.655 s …  2.788 s    20 runs
---
 src/libexpr/nixexpr.hh |  4 ++--
 src/libexpr/parser.y   | 22 +++++++++++-----------
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index ae11560ea..a2070ff69 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -110,9 +110,9 @@ struct ExprFloat : Expr
 
 struct ExprString : Expr
 {
-    Symbol s;
+    string s;
     Value v;
-    ExprString(const Symbol & s) : s(s) { v.mkString(s); };
+    ExprString(std::string s) : s(std::move(s)) { v.mkString(this->s.data()); };
     COMMON_METHODS
     Value * maybeThunk(EvalState & state, Env & env);
 };
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 38b218156..88bdebcd6 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -166,7 +166,7 @@ static void addFormal(const Pos & pos, Formals * formals, const Formal & formal)
 static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols,
     vector<std::pair<Pos, std::variant<Expr *, StringToken> > > & es)
 {
-    if (es.empty()) return new ExprString(symbols.create(""));
+    if (es.empty()) return new ExprString("");
 
     /* Figure out the minimum indentation.  Note that by design
        whitespace-only final lines are not taken into account.  (So
@@ -244,7 +244,7 @@ static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols,
                 s2 = string(s2, 0, p + 1);
         }
 
-        es2->emplace_back(i->first, new ExprString(symbols.create(s2)));
+        es2->emplace_back(i->first, new ExprString(s2));
     };
     for (; i != es.end(); ++i, --n) {
         std::visit(overloaded { trimExpr, trimString }, i->second);
@@ -434,7 +434,7 @@ expr_simple
       $$ = new ExprCall(CUR_POS,
           new ExprVar(data->symbols.create("__findFile")),
           {new ExprVar(data->symbols.create("__nixPath")),
-           new ExprString(data->symbols.create(path))});
+           new ExprString(path)});
   }
   | URI {
       static bool noURLLiterals = settings.isExperimentalFeatureEnabled(Xp::NoUrlLiterals);
@@ -443,7 +443,7 @@ expr_simple
               .msg = hintfmt("URL literals are disabled"),
               .errPos = CUR_POS
           });
-      $$ = new ExprString(data->symbols.create($1));
+      $$ = new ExprString(string($1));
   }
   | '(' expr ')' { $$ = $2; }
   /* Let expressions `let {..., body = ...}' are just desugared
@@ -458,19 +458,19 @@ expr_simple
   ;
 
 string_parts
-  : STR { $$ = new ExprString(data->symbols.create($1)); }
+  : STR { $$ = new ExprString(string($1)); }
   | string_parts_interpolated { $$ = new ExprConcatStrings(CUR_POS, true, $1); }
-  | { $$ = new ExprString(data->symbols.create("")); }
+  | { $$ = new ExprString(""); }
   ;
 
 string_parts_interpolated
   : string_parts_interpolated STR
-  { $$ = $1; $1->emplace_back(makeCurPos(@2, data), new ExprString(data->symbols.create($2))); }
+  { $$ = $1; $1->emplace_back(makeCurPos(@2, data), new ExprString(string($2))); }
   | string_parts_interpolated DOLLAR_CURLY expr '}' { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $3); }
   | DOLLAR_CURLY expr '}' { $$ = new vector<std::pair<Pos, Expr *> >; $$->emplace_back(makeCurPos(@1, data), $2); }
   | STR DOLLAR_CURLY expr '}' {
       $$ = new vector<std::pair<Pos, Expr *> >;
-      $$->emplace_back(makeCurPos(@1, data), new ExprString(data->symbols.create($1)));
+      $$->emplace_back(makeCurPos(@1, data), new ExprString(string($1)));
       $$->emplace_back(makeCurPos(@2, data), $3);
     }
   ;
@@ -524,7 +524,7 @@ attrs
     { $$ = $1;
       ExprString * str = dynamic_cast<ExprString *>($2);
       if (str) {
-          $$->push_back(AttrName(str->s));
+          $$->push_back(AttrName(data->symbols.create(str->s)));
           delete str;
       } else
           throw ParseError({
@@ -541,7 +541,7 @@ attrpath
     { $$ = $1;
       ExprString * str = dynamic_cast<ExprString *>($3);
       if (str) {
-          $$->push_back(AttrName(str->s));
+          $$->push_back(AttrName(data->symbols.create(str->s)));
           delete str;
       } else
           $$->push_back(AttrName($3));
@@ -551,7 +551,7 @@ attrpath
     { $$ = new vector<AttrName>;
       ExprString *str = dynamic_cast<ExprString *>($1);
       if (str) {
-          $$->push_back(AttrName(str->s));
+          $$->push_back(AttrName(data->symbols.create(str->s)));
           delete str;
       } else
           $$->push_back(AttrName($1));

From d038a67bd3c6ed0d6452d595cf0af3115e14c48f Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Thu, 6 Jan 2022 01:20:12 +0100
Subject: [PATCH 436/567] Fix segfault or stack overflow caused by large
 derivation fields

This removes a dynamic stack allocation, making the derivation
unparsing logic robust against overflows when large strings are
added to a derivation.
Overflow behavior depends on the platform and stack configuration.

For instance, x86_64-linux/glibc behaves as (somewhat) expected:

$ (ulimit -s 20000; nix-instantiate tests/lang/eval-okay-big-derivation-attr.nix)
error: stack overflow (possible infinite recursion)

$ (ulimit -s 40000; nix-instantiate tests/lang/eval-okay-big-derivation-attr.nix)
error: expression does not evaluate to a derivation (or a set or list of those)

However, on aarch64-darwin:

$ nix-instantiate big-attr.nix                                                                                                                                                                                                                                                       ~
zsh: segmentation fault  nix-instantiate big-attr.nix

This indicates a slight flaw in the single stack protection page
approach that is not encountered with normal stack frames.
---
 src/libstore/derivations.cc   | 10 +++++++++-
 tests/big-derivation-attr.nix | 13 +++++++++++++
 tests/simple.sh               |  6 ++++++
 3 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 tests/big-derivation-attr.nix

diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index b926bb711..616e78076 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -272,7 +272,15 @@ Derivation parseDerivation(const Store & store, std::string && s, std::string_vi
 
 static void printString(string & res, std::string_view s)
 {
-    char buf[s.size() * 2 + 2];
+    char * buf;
+    size_t bufSize = s.size() * 2 + 2;
+    std::unique_ptr<char[]> dynBuf;
+    if (bufSize < 0x10000) {
+        buf = (char *)alloca(bufSize);
+    } else {
+        dynBuf = decltype(dynBuf)(new char[bufSize]);
+        buf = dynBuf.get();
+    }
     char * p = buf;
     *p++ = '"';
     for (auto c : s)
diff --git a/tests/big-derivation-attr.nix b/tests/big-derivation-attr.nix
new file mode 100644
index 000000000..35c1187f6
--- /dev/null
+++ b/tests/big-derivation-attr.nix
@@ -0,0 +1,13 @@
+let
+  sixteenBytes = "0123456789abcdef";
+  times16 = s: builtins.concatStringsSep "" [s s s s s s s s s s s s s s s s];
+  exp = n: x: if n == 1 then x else times16 (exp (n - 1) x);
+  sixteenMegabyte = exp 6 sixteenBytes;
+in
+assert builtins.stringLength sixteenMegabyte == 16777216;
+derivation {
+  name = "big-derivation-attr";
+  builder = "/x";
+  system = "y";
+  bigAttr = sixteenMegabyte;
+}
diff --git a/tests/simple.sh b/tests/simple.sh
index 15bd2bd16..50d44f93f 100644
--- a/tests/simple.sh
+++ b/tests/simple.sh
@@ -25,3 +25,9 @@ if test "$outPath" != "/foo/lfy1s6ca46rm5r6w4gg9hc0axiakjcnm-dependencies.drv";
     echo "hashDerivationModulo appears broken, got $outPath"
     exit 1
 fi
+
+outPath="$(NIX_REMOTE=local?store=/foo\&real=$TEST_ROOT/real-store nix-instantiate --readonly-mode big-derivation-attr.nix)"
+if test "$outPath" != "/foo/xxiwa5zlaajv6xdjynf9yym9g319d6mn-big-derivation-attr.drv"; then
+    echo "big-derivation-attr.nix hash appears broken, got $outPath. Memory corruption in large drv attr?"
+    exit 1
+fi

From 55c58580be89e0f7ec6519bd7a7f2cded4fab382 Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Thu, 6 Jan 2022 14:31:23 +0100
Subject: [PATCH 437/567] Add withBuffer

... to avoid non-standard, unidiomatic alloca.
---
 src/libstore/derivations.cc | 30 ++++++++++++------------------
 src/libutil/util.hh         |  9 +++++++++
 2 files changed, 21 insertions(+), 18 deletions(-)

diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index 616e78076..21ea84dbf 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -272,25 +272,19 @@ Derivation parseDerivation(const Store & store, std::string && s, std::string_vi
 
 static void printString(string & res, std::string_view s)
 {
-    char * buf;
     size_t bufSize = s.size() * 2 + 2;
-    std::unique_ptr<char[]> dynBuf;
-    if (bufSize < 0x10000) {
-        buf = (char *)alloca(bufSize);
-    } else {
-        dynBuf = decltype(dynBuf)(new char[bufSize]);
-        buf = dynBuf.get();
-    }
-    char * p = buf;
-    *p++ = '"';
-    for (auto c : s)
-        if (c == '\"' || c == '\\') { *p++ = '\\'; *p++ = c; }
-        else if (c == '\n') { *p++ = '\\'; *p++ = 'n'; }
-        else if (c == '\r') { *p++ = '\\'; *p++ = 'r'; }
-        else if (c == '\t') { *p++ = '\\'; *p++ = 't'; }
-        else *p++ = c;
-    *p++ = '"';
-    res.append(buf, p - buf);
+    withBuffer<void, char>(bufSize, [&](char buf[]) {
+        char * p = buf;
+        *p++ = '"';
+        for (auto c : s)
+            if (c == '\"' || c == '\\') { *p++ = '\\'; *p++ = c; }
+            else if (c == '\n') { *p++ = '\\'; *p++ = 'n'; }
+            else if (c == '\r') { *p++ = '\\'; *p++ = 'r'; }
+            else if (c == '\t') { *p++ = '\\'; *p++ = 't'; }
+            else *p++ = c;
+        *p++ = '"';
+        res.append(buf, p - buf);
+    });
 }
 
 
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 369c44f78..840acd67b 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -671,5 +671,14 @@ template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
 
 std::string showBytes(uint64_t bytes);
 
+template<typename R = void, typename T = char> inline R withBuffer(size_t size, std::function<R (T[])> fun) {
+    if (size < 0x10000) {
+        T buf[size];
+        return fun(buf);
+    } else {
+        auto buf = std::unique_ptr<T[]>(new T[size]);
+        return fun(buf.get());
+    }
+}
 
 }

From 6dd271b7b4a679ce3c2a8d84a39909bb9b60bf9f Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Thu, 6 Jan 2022 15:11:37 +0100
Subject: [PATCH 438/567] withBuffer: avoid allocating a std::function

---
 src/libstore/derivations.cc | 2 +-
 src/libutil/util.hh         | 5 ++++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index 21ea84dbf..f8fe6a59c 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -273,7 +273,7 @@ Derivation parseDerivation(const Store & store, std::string && s, std::string_vi
 static void printString(string & res, std::string_view s)
 {
     size_t bufSize = s.size() * 2 + 2;
-    withBuffer<void, char>(bufSize, [&](char buf[]) {
+    withBuffer(bufSize, [&](char *buf) {
         char * p = buf;
         *p++ = '"';
         for (auto c : s)
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 840acd67b..407505be9 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -671,7 +671,10 @@ template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
 
 std::string showBytes(uint64_t bytes);
 
-template<typename R = void, typename T = char> inline R withBuffer(size_t size, std::function<R (T[])> fun) {
+template<typename T = char, typename Fn>
+inline auto withBuffer(size_t size, Fn fun)
+  -> std::invoke_result_t<Fn, T *>
+{
     if (size < 0x10000) {
         T buf[size];
         return fun(buf);

From 624f18ad90e3784878e6d303858f59651af68f61 Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Mon, 10 Jan 2022 21:17:17 +0100
Subject: [PATCH 439/567] withBuffer: Make sure to hit the stack protector

---
 src/libutil/util.hh | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 407505be9..e2192987c 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -671,15 +671,28 @@ template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
 
 std::string showBytes(uint64_t bytes);
 
+/**
+  `withBuffer(size, fun)` applies `fun` to a temporary `char` array of size `size`.
+  The array will be allocated either on the stack or on the heap depending on its size
+*/
 template<typename T = char, typename Fn>
-inline auto withBuffer(size_t size, Fn fun)
+inline auto withBuffer(size_t n, Fn fun)
   -> std::invoke_result_t<Fn, T *>
 {
-    if (size < 0x10000) {
-        T buf[size];
+    // Large stack allocations can skip past the stack protection page.
+    const size_t stack_protection_size = 4096;
+    // We reduce the max stack allocated buffer by an extra amount to increase
+    // the chance of hitting it, even when `fun`'s first access is some distance
+    // into its *further* stack frame, particularly if the call was inlined and
+    // therefore not writing a frame pointer.
+    const size_t play = 64 * sizeof(char *); // 512B on 64b archs
+    size_t size_bytes = n * sizeof(T);
+
+    if (size_bytes < stack_protection_size - play) {
+        T buf[n];
         return fun(buf);
     } else {
-        auto buf = std::unique_ptr<T[]>(new T[size]);
+        auto buf = std::unique_ptr<T[]>(new T[n]);
         return fun(buf.get());
     }
 }

From dec774811922d7ee220bb8e2488bc2f7abf61844 Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Wed, 19 Jan 2022 15:20:46 +0100
Subject: [PATCH 440/567] Replace withBuffer by boost small_vector

Although this will leave gaps in the stack, the performance impact
of those should be insignificant and we get a simpler solution
this way.
---
 src/libstore/derivations.cc | 35 ++++++++++++++++++++++-------------
 src/libutil/util.hh         | 25 -------------------------
 2 files changed, 22 insertions(+), 38 deletions(-)

diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index f8fe6a59c..5233cfe67 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -4,6 +4,7 @@
 #include "util.hh"
 #include "worker-protocol.hh"
 #include "fs-accessor.hh"
+#include <boost/container/small_vector.hpp>
 
 namespace nix {
 
@@ -272,19 +273,27 @@ Derivation parseDerivation(const Store & store, std::string && s, std::string_vi
 
 static void printString(string & res, std::string_view s)
 {
-    size_t bufSize = s.size() * 2 + 2;
-    withBuffer(bufSize, [&](char *buf) {
-        char * p = buf;
-        *p++ = '"';
-        for (auto c : s)
-            if (c == '\"' || c == '\\') { *p++ = '\\'; *p++ = c; }
-            else if (c == '\n') { *p++ = '\\'; *p++ = 'n'; }
-            else if (c == '\r') { *p++ = '\\'; *p++ = 'r'; }
-            else if (c == '\t') { *p++ = '\\'; *p++ = 't'; }
-            else *p++ = c;
-        *p++ = '"';
-        res.append(buf, p - buf);
-    });
+    // Large stack allocations can skip past the stack protection page.
+    const size_t stack_protection_size = 4096;
+    // We reduce the max stack allocated buffer by an extra amount to increase
+    // the chance of hitting it, even when `fun`'s first access is some distance
+    // into its *further* stack frame, particularly if the call was inlined and
+    // therefore not writing a frame pointer.
+    const size_t play = 64 * sizeof(char *); // 512B on 64b archs
+
+    boost::container::small_vector<char, stack_protection_size - play> buffer;
+    buffer.reserve(s.size() * 2 + 2);
+    char * buf = buffer.data();
+    char * p = buf;
+    *p++ = '"';
+    for (auto c : s)
+        if (c == '\"' || c == '\\') { *p++ = '\\'; *p++ = c; }
+        else if (c == '\n') { *p++ = '\\'; *p++ = 'n'; }
+        else if (c == '\r') { *p++ = '\\'; *p++ = 'r'; }
+        else if (c == '\t') { *p++ = '\\'; *p++ = 't'; }
+        else *p++ = c;
+    *p++ = '"';
+    res.append(buf, p - buf);
 }
 
 
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index e2192987c..369c44f78 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -671,30 +671,5 @@ template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
 
 std::string showBytes(uint64_t bytes);
 
-/**
-  `withBuffer(size, fun)` applies `fun` to a temporary `char` array of size `size`.
-  The array will be allocated either on the stack or on the heap depending on its size
-*/
-template<typename T = char, typename Fn>
-inline auto withBuffer(size_t n, Fn fun)
-  -> std::invoke_result_t<Fn, T *>
-{
-    // Large stack allocations can skip past the stack protection page.
-    const size_t stack_protection_size = 4096;
-    // We reduce the max stack allocated buffer by an extra amount to increase
-    // the chance of hitting it, even when `fun`'s first access is some distance
-    // into its *further* stack frame, particularly if the call was inlined and
-    // therefore not writing a frame pointer.
-    const size_t play = 64 * sizeof(char *); // 512B on 64b archs
-    size_t size_bytes = n * sizeof(T);
-
-    if (size_bytes < stack_protection_size - play) {
-        T buf[n];
-        return fun(buf);
-    } else {
-        auto buf = std::unique_ptr<T[]>(new T[n]);
-        return fun(buf.get());
-    }
-}
 
 }

From 7d4cc5515ce5e4972fd5b474ae18cf95f6ea257e Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Wed, 19 Jan 2022 16:49:02 +0100
Subject: [PATCH 441/567] defer formals duplicate check for incresed efficiency
 all round
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

if we defer the duplicate argument check for lambda formals we can use more
efficient data structures for the formals set, and we can get rid of the
duplication of formals names to boot. instead of a list of formals we've seen
and a set of names we'll keep a vector instead and run a sort+dupcheck step
before moving the parsed formals into a newly created lambda. this improves
performance on search and rebuild by ~1%, pure parsing gains more (about 4%).

this does reorder lambda arguments in the xml output, but the output is still
stable. this shouldn't be a problem since argument order is not semantically
important anyway.

 before

  nix search --no-eval-cache --offline ../nixpkgs hello
    Time (mean ± σ):      8.550 s ±  0.060 s    [User: 6.470 s, System: 1.664 s]
    Range (min … max):    8.435 s …  8.666 s    20 runs

  nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
    Time (mean ± σ):     346.7 ms ±   2.1 ms    [User: 312.4 ms, System: 34.2 ms]
    Range (min … max):   343.8 ms … 353.4 ms    20 runs

  nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
    Time (mean ± σ):      2.720 s ±  0.031 s    [User: 2.415 s, System: 0.231 s]
    Range (min … max):    2.662 s …  2.780 s    20 runs

 after

  nix search --no-eval-cache --offline ../nixpkgs hello
    Time (mean ± σ):      8.462 s ±  0.063 s    [User: 6.398 s, System: 1.661 s]
    Range (min … max):    8.339 s …  8.542 s    20 runs

  nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
    Time (mean ± σ):     329.1 ms ±   1.4 ms    [User: 296.8 ms, System: 32.3 ms]
    Range (min … max):   326.1 ms … 330.8 ms    20 runs

  nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
    Time (mean ± σ):      2.687 s ±  0.035 s    [User: 2.392 s, System: 0.228 s]
    Range (min … max):    2.626 s …  2.754 s    20 runs
---
 src/libexpr/eval.cc              |  2 +-
 src/libexpr/nixexpr.hh           | 24 +++++++++----
 src/libexpr/parser.y             | 61 +++++++++++++++++++++++++-------
 src/libexpr/value-to-xml.cc      |  2 +-
 src/nix/flake.cc                 |  4 +--
 tests/check.nix                  |  2 +-
 tests/lang/eval-okay-xml.exp.xml |  2 +-
 7 files changed, 71 insertions(+), 26 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 94ffab175..73ed3a8a1 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -1368,7 +1368,7 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
                     /* Nope, so show the first unexpected argument to the
                        user. */
                     for (auto & i : *args[0]->attrs)
-                        if (!lambda.formals->argNames.count(i.name))
+                        if (!lambda.formals->has(i.name))
                             throwTypeError(pos, "%1% called with unexpected argument '%2%'", lambda, i.name);
                     abort(); // can't happen
                 }
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index a2070ff69..4e923ac89 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -216,10 +216,25 @@ struct Formal
 
 struct Formals
 {
-    typedef std::list<Formal> Formals_;
+    typedef std::vector<Formal> Formals_;
     Formals_ formals;
-    std::set<Symbol> argNames; // used during parsing
     bool ellipsis;
+
+    bool has(Symbol arg) const {
+        auto it = std::lower_bound(formals.begin(), formals.end(), arg,
+            [] (const Formal & f, const Symbol & sym) { return f.name < sym; });
+        return it != formals.end() && it->name == arg;
+    }
+
+    std::vector<Formal> lexicographicOrder() const
+    {
+        std::vector<Formal> result(formals.begin(), formals.end());
+        std::sort(result.begin(), result.end(),
+            [] (const Formal & a, const Formal & b) {
+                return std::string_view(a.name) < std::string_view(b.name);
+            });
+        return result;
+    }
 };
 
 struct ExprLambda : Expr
@@ -232,11 +247,6 @@ struct ExprLambda : Expr
     ExprLambda(const Pos & pos, const Symbol & arg, Formals * formals, Expr * body)
         : pos(pos), arg(arg), formals(formals), body(body)
     {
-        if (!arg.empty() && formals && formals->argNames.find(arg) != formals->argNames.end())
-            throw ParseError({
-                .msg = hintfmt("duplicate formal function argument '%1%'", arg),
-                .errPos = pos
-            });
     };
     void setName(Symbol & name);
     string showNamePos() const;
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 88bdebcd6..1b0177e4a 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -41,6 +41,11 @@ namespace nix {
             { };
     };
 
+    struct ParserFormals {
+        std::vector<Formal> formals;
+        bool ellipsis = false;
+    };
+
 }
 
 // using C a struct allows us to avoid having to define the special
@@ -151,15 +156,39 @@ static void addAttr(ExprAttrs * attrs, AttrPath & attrPath,
 }
 
 
-static void addFormal(const Pos & pos, Formals * formals, const Formal & formal)
+static Formals * toFormals(ParseData & data, ParserFormals * formals,
+    Pos pos = noPos, Symbol arg = {})
 {
-    if (!formals->argNames.insert(formal.name).second)
+    std::sort(formals->formals.begin(), formals->formals.end(),
+        [] (const auto & a, const auto & b) {
+            return std::tie(a.name, a.pos) < std::tie(b.name, b.pos);
+        });
+
+    std::optional<std::pair<Symbol, Pos>> duplicate;
+    for (size_t i = 0; i + 1 < formals->formals.size(); i++) {
+        if (formals->formals[i].name != formals->formals[i + 1].name)
+            continue;
+        std::pair thisDup{formals->formals[i].name, formals->formals[i + 1].pos};
+        duplicate = std::min(thisDup, duplicate.value_or(thisDup));
+    }
+    if (duplicate)
         throw ParseError({
-            .msg = hintfmt("duplicate formal function argument '%1%'",
-                formal.name),
+            .msg = hintfmt("duplicate formal function argument '%1%'", duplicate->first),
+            .errPos = duplicate->second
+        });
+
+    Formals result;
+    result.ellipsis = formals->ellipsis;
+    result.formals = std::move(formals->formals);
+
+    if (arg.set() && result.has(arg))
+        throw ParseError({
+            .msg = hintfmt("duplicate formal function argument '%1%'", arg),
             .errPos = pos
         });
-    formals->formals.push_front(formal);
+
+    delete formals;
+    return new Formals(std::move(result));
 }
 
 
@@ -282,7 +311,7 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * err
   nix::Expr * e;
   nix::ExprList * list;
   nix::ExprAttrs * attrs;
-  nix::Formals * formals;
+  nix::ParserFormals * formals;
   nix::Formal * formal;
   nix::NixInt n;
   nix::NixFloat nf;
@@ -340,11 +369,17 @@ expr_function
   : ID ':' expr_function
     { $$ = new ExprLambda(CUR_POS, data->symbols.create($1), 0, $3); }
   | '{' formals '}' ':' expr_function
-    { $$ = new ExprLambda(CUR_POS, data->symbols.create(""), $2, $5); }
+    { $$ = new ExprLambda(CUR_POS, data->symbols.create(""), toFormals(*data, $2), $5); }
   | '{' formals '}' '@' ID ':' expr_function
-    { $$ = new ExprLambda(CUR_POS, data->symbols.create($5), $2, $7); }
+    {
+      Symbol arg = data->symbols.create($5);
+      $$ = new ExprLambda(CUR_POS, arg, toFormals(*data, $2, CUR_POS, arg), $7);
+    }
   | ID '@' '{' formals '}' ':' expr_function
-    { $$ = new ExprLambda(CUR_POS, data->symbols.create($1), $4, $7); }
+    {
+      Symbol arg = data->symbols.create($1);
+      $$ = new ExprLambda(CUR_POS, arg, toFormals(*data, $4, CUR_POS, arg), $7);
+    }
   | ASSERT expr ';' expr_function
     { $$ = new ExprAssert(CUR_POS, $2, $4); }
   | WITH expr ';' expr_function
@@ -575,13 +610,13 @@ expr_list
 
 formals
   : formal ',' formals
-    { $$ = $3; addFormal(CUR_POS, $$, *$1); }
+    { $$ = $3; $$->formals.push_back(*$1); }
   | formal
-    { $$ = new Formals; addFormal(CUR_POS, $$, *$1); $$->ellipsis = false; }
+    { $$ = new ParserFormals; $$->formals.push_back(*$1); $$->ellipsis = false; }
   |
-    { $$ = new Formals; $$->ellipsis = false; }
+    { $$ = new ParserFormals; $$->ellipsis = false; }
   | ELLIPSIS
-    { $$ = new Formals; $$->ellipsis = true; }
+    { $$ = new ParserFormals; $$->ellipsis = true; }
   ;
 
 formal
diff --git a/src/libexpr/value-to-xml.cc b/src/libexpr/value-to-xml.cc
index a875f82d7..a9fb60b0e 100644
--- a/src/libexpr/value-to-xml.cc
+++ b/src/libexpr/value-to-xml.cc
@@ -142,7 +142,7 @@ static void printValueAsXML(EvalState & state, bool strict, bool location,
                 if (!v.lambda.fun->arg.empty()) attrs["name"] = v.lambda.fun->arg;
                 if (v.lambda.fun->formals->ellipsis) attrs["ellipsis"] = "1";
                 XMLOpenElement _(doc, "attrspat", attrs);
-                for (auto & i : v.lambda.fun->formals->formals)
+                for (auto & i : v.lambda.fun->formals->lexicographicOrder())
                     doc.writeEmptyElement("attr", singletonAttrs("name", i.name));
             } else
                 doc.writeEmptyElement("varpat", singletonAttrs("name", v.lambda.fun->arg));
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 97f4d911c..101d38c6c 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -476,8 +476,8 @@ struct CmdFlakeCheck : FlakeCommand
                 if (!v.isLambda())
                     throw Error("bundler must be a function");
                 if (!v.lambda.fun->formals ||
-                    !v.lambda.fun->formals->argNames.count(state->symbols.create("program")) ||
-                    !v.lambda.fun->formals->argNames.count(state->symbols.create("system")))
+                    !v.lambda.fun->formals->has(state->symbols.create("program")) ||
+                    !v.lambda.fun->formals->has(state->symbols.create("system")))
                     throw Error("bundler must take formal arguments 'program' and 'system'");
             } catch (Error & e) {
                 e.addTrace(pos, hintfmt("while checking the template '%s'", attrPath));
diff --git a/tests/check.nix b/tests/check.nix
index ec455ae2d..ed91ff845 100644
--- a/tests/check.nix
+++ b/tests/check.nix
@@ -50,6 +50,6 @@ with import ./config.nix;
 
   fetchurl = import <nix/fetchurl.nix> {
     url = "file://" + toString ./lang/eval-okay-xml.exp.xml;
-    sha256 = "0kg4sla7ihm8ijr8cb3117fhl99zrc2bwy1jrngsfmkh8bav4m0v";
+    sha256 = "sha256-behBlX+DQK/Pjvkuc8Tx68Jwi4E5v86wDq+ZLaHyhQE=";
   };
 }
diff --git a/tests/lang/eval-okay-xml.exp.xml b/tests/lang/eval-okay-xml.exp.xml
index 92b75e0b8..20099326c 100644
--- a/tests/lang/eval-okay-xml.exp.xml
+++ b/tests/lang/eval-okay-xml.exp.xml
@@ -31,9 +31,9 @@
     <attr name="f">
       <function>
         <attrspat>
-          <attr name="z" />
           <attr name="x" />
           <attr name="y" />
+          <attr name="z" />
         </attrspat>
       </function>
     </attr>

From 92e8230215db50bfbd63729c18072d2ed76c267b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hubert=20G=C5=82uchowski?= <hubert.gluchowski19@gmail.com>
Date: Wed, 19 Jan 2022 17:46:29 +0100
Subject: [PATCH 442/567] Make `nix search` highlight all regexes

---
 src/nix/search.cc | 81 +++++++++++++++++++++++++++++++++++++----------
 1 file changed, 64 insertions(+), 17 deletions(-)

diff --git a/src/nix/search.cc b/src/nix/search.cc
index 0d8fdd5c2..3a62251d4 100644
--- a/src/nix/search.cc
+++ b/src/nix/search.cc
@@ -20,16 +20,52 @@ std::string wrap(std::string prefix, std::string s)
     return prefix + s + ANSI_NORMAL;
 }
 
+#define HILITE_COLOR ANSI_GREEN
+
 std::string hilite(const std::string & s, const std::smatch & m, std::string postfix)
 {
     return
         m.empty()
         ? s
         : std::string(m.prefix())
-          + ANSI_GREEN + std::string(m.str()) + postfix
+          + HILITE_COLOR + std::string(m.str()) + postfix
           + std::string(m.suffix());
 }
 
+std::string hilite_all(const std::string &s, std::vector<std::smatch> matches, std::string postfix) {
+    // Don't waste time on trivial highlights
+    if (matches.size() == 0)
+        return s;
+    else if (matches.size() == 1)
+        return hilite(s, matches[0], postfix);
+
+    std::sort(matches.begin(), matches.end(), [](const auto &a, const auto &b) {
+        return a.position() < b.position();
+    });
+
+    std::string out;
+    ssize_t last_end = 0;
+    for (size_t i = 0; i < matches.size(); i++) {
+        auto m = matches[i];
+        size_t start = m.position();
+        out.append(m.prefix().str().substr(last_end));
+        // Merge continous matches
+        ssize_t end = start + m.length();
+        while(i + 1 < matches.size() && matches[i+1].position() <= end) {
+            auto n = matches[++i];
+            ssize_t nend = start + (n.position() - start + n.length());
+            if(nend > end)
+                end = nend;
+        }
+        out.append(HILITE_COLOR);
+        out.append(s.substr(start, end - start));
+        out.append(postfix);
+        last_end = end;
+    }
+    out.append(s.substr(last_end));
+    return out;
+}
+
 struct CmdSearch : InstallableCommand, MixJSON
 {
     std::vector<std::string> res;
@@ -100,8 +136,6 @@ struct CmdSearch : InstallableCommand, MixJSON
                 };
 
                 if (cursor.isDerivation()) {
-                    size_t found = 0;
-
                     DrvName name(cursor.getAttr("name")->getString());
 
                     auto aMeta = cursor.maybeGetAttr("meta");
@@ -110,21 +144,34 @@ struct CmdSearch : InstallableCommand, MixJSON
                     std::replace(description.begin(), description.end(), '\n', ' ');
                     auto attrPath2 = concatStringsSep(".", attrPath);
 
-                    std::smatch attrPathMatch;
-                    std::smatch descriptionMatch;
-                    std::smatch nameMatch;
+                    std::vector<std::smatch> attrPathMatches;
+                    std::vector<std::smatch> descriptionMatches;
+                    std::vector<std::smatch> nameMatches;
+                    bool found = false;
 
                     for (auto & regex : regexes) {
-                        std::regex_search(attrPath2, attrPathMatch, regex);
-                        std::regex_search(name.name, nameMatch, regex);
-                        std::regex_search(description, descriptionMatch, regex);
-                        if (!attrPathMatch.empty()
-                            || !nameMatch.empty()
-                            || !descriptionMatch.empty())
-                            found++;
+                        std::smatch tmp;
+                        found = false;
+
+                        if(std::regex_search(attrPath2, tmp, regex)) {
+                            attrPathMatches.push_back(tmp);
+                            found = true;
+                        }
+                        if(std::regex_search(name.name, tmp, regex)) {
+                            nameMatches.push_back(tmp);
+                            found = true;
+                        }
+                        if(std::regex_search(description, tmp, regex)) {
+                            descriptionMatches.push_back(tmp);
+                            found = true;
+                        }
+
+                        if(!found)
+                            break;
                     }
 
-                    if (found == res.size()) {
+                    if (found)
+                    {
                         results++;
                         if (json) {
                             auto jsonElem = jsonOut->object(attrPath2);
@@ -132,15 +179,15 @@ struct CmdSearch : InstallableCommand, MixJSON
                             jsonElem.attr("version", name.version);
                             jsonElem.attr("description", description);
                         } else {
-                            auto name2 = hilite(name.name, nameMatch, "\e[0;2m");
+                            auto name2 = hilite_all(name.name, nameMatches, "\e[0;2m");
                             if (results > 1) logger->cout("");
                             logger->cout(
                                 "* %s%s",
-                                wrap("\e[0;1m", hilite(attrPath2, attrPathMatch, "\e[0;1m")),
+                                wrap("\e[0;1m", hilite_all(attrPath2, attrPathMatches, "\e[0;1m")),
                                 name.version != "" ? " (" + name.version + ")" : "");
                             if (description != "")
                                 logger->cout(
-                                    "  %s", hilite(description, descriptionMatch, ANSI_NORMAL));
+                                    "  %s", hilite_all(description, descriptionMatches, ANSI_NORMAL));
                         }
                     }
                 }

From 87fdd230251b871f60f2a148ae2ee00b00854017 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hubert=20G=C5=82uchowski?= <hubert.gluchowski19@gmail.com>
Date: Wed, 19 Jan 2022 19:59:02 +0100
Subject: [PATCH 443/567] Make `nix search` highlight all matches of a regex

---
 src/nix/search.cc | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/src/nix/search.cc b/src/nix/search.cc
index 3a62251d4..d23ce0f53 100644
--- a/src/nix/search.cc
+++ b/src/nix/search.cc
@@ -10,6 +10,7 @@
 #include "eval-cache.hh"
 #include "attr-path.hh"
 
+#include <iterator>
 #include <regex>
 #include <fstream>
 
@@ -48,7 +49,7 @@ std::string hilite_all(const std::string &s, std::vector<std::smatch> matches, s
     for (size_t i = 0; i < matches.size(); i++) {
         auto m = matches[i];
         size_t start = m.position();
-        out.append(m.prefix().str().substr(last_end));
+        out.append(s.substr(last_end, m.position() - last_end));
         // Merge continous matches
         ssize_t end = start + m.length();
         while(i + 1 < matches.size() && matches[i+1].position() <= end) {
@@ -150,21 +151,18 @@ struct CmdSearch : InstallableCommand, MixJSON
                     bool found = false;
 
                     for (auto & regex : regexes) {
-                        std::smatch tmp;
                         found = false;
+                        auto add_all = [&found](std::sregex_iterator it, std::vector<std::smatch>& vec){
+                            const auto end = std::sregex_iterator();
+                            while(it != end) {
+                                vec.push_back(*it++);
+                                found = true;
+                            }
+                        };
 
-                        if(std::regex_search(attrPath2, tmp, regex)) {
-                            attrPathMatches.push_back(tmp);
-                            found = true;
-                        }
-                        if(std::regex_search(name.name, tmp, regex)) {
-                            nameMatches.push_back(tmp);
-                            found = true;
-                        }
-                        if(std::regex_search(description, tmp, regex)) {
-                            descriptionMatches.push_back(tmp);
-                            found = true;
-                        }
+                        add_all(std::sregex_iterator(attrPath2.begin(), attrPath2.end(), regex), attrPathMatches);
+                        add_all(std::sregex_iterator(name.name.begin(), name.name.end(), regex), nameMatches);
+                        add_all(std::sregex_iterator(description.begin(), description.end(), regex), descriptionMatches);
 
                         if(!found)
                             break;

From 89f8917a323b8825dd0926ec543285b42bcb0a81 Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Wed, 19 Jan 2022 20:16:24 +0000
Subject: [PATCH 444/567] Remove dead field in NixArgs

This has been unused since 170e86dff5724264e0d3d25b9af1bd42df6aec74

CC @thufschmitt
---
 src/nix/main.cc | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/nix/main.cc b/src/nix/main.cc
index 5158c3902..b923f2535 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -59,7 +59,6 @@ struct HelpRequested { };
 
 struct NixArgs : virtual MultiCommand, virtual MixCommonArgs
 {
-    bool printBuildLogs = false;
     bool useNet = true;
     bool refresh = false;
     bool showVersion = false;

From 9510ad10c54d906ec2597d3baa81d0f0f97b1f77 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hubert=20G=C5=82uchowski?= <hubert.gluchowski19@gmail.com>
Date: Thu, 20 Jan 2022 17:12:15 +0100
Subject: [PATCH 445/567] Make `hilite_all` take an iterator of matches instead
 of a vector.

---
 src/nix/search.cc | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/src/nix/search.cc b/src/nix/search.cc
index d23ce0f53..01211bae3 100644
--- a/src/nix/search.cc
+++ b/src/nix/search.cc
@@ -33,27 +33,27 @@ std::string hilite(const std::string & s, const std::smatch & m, std::string pos
           + std::string(m.suffix());
 }
 
-std::string hilite_all(const std::string &s, std::vector<std::smatch> matches, std::string postfix) {
-    // Don't waste time on trivial highlights
-    if (matches.size() == 0)
+template<class Iter>
+std::string hilite_all(const std::string &s, Iter matches_first, Iter matches_last, std::string postfix) {
+    // Avoid copy on zero matches
+    if (matches_first == matches_last)
         return s;
-    else if (matches.size() == 1)
-        return hilite(s, matches[0], postfix);
 
-    std::sort(matches.begin(), matches.end(), [](const auto &a, const auto &b) {
+    std::sort(matches_first, matches_last, [](const auto &a, const auto &b) {
         return a.position() < b.position();
     });
 
     std::string out;
     ssize_t last_end = 0;
-    for (size_t i = 0; i < matches.size(); i++) {
-        auto m = matches[i];
+
+    for (Iter it = matches_first; it != matches_last; ++it) {
+        auto m = *it;
         size_t start = m.position();
         out.append(s.substr(last_end, m.position() - last_end));
         // Merge continous matches
         ssize_t end = start + m.length();
-        while(i + 1 < matches.size() && matches[i+1].position() <= end) {
-            auto n = matches[++i];
+        while(it + 1 != matches_last && (*(it + 1)).position() <= end) {
+            auto n = *++it;
             ssize_t nend = start + (n.position() - start + n.length());
             if(nend > end)
                 end = nend;
@@ -177,15 +177,15 @@ struct CmdSearch : InstallableCommand, MixJSON
                             jsonElem.attr("version", name.version);
                             jsonElem.attr("description", description);
                         } else {
-                            auto name2 = hilite_all(name.name, nameMatches, "\e[0;2m");
+                            auto name2 = hilite_all(name.name, nameMatches.begin(), nameMatches.end(), "\e[0;2m");
                             if (results > 1) logger->cout("");
                             logger->cout(
                                 "* %s%s",
-                                wrap("\e[0;1m", hilite_all(attrPath2, attrPathMatches, "\e[0;1m")),
+                                wrap("\e[0;1m", hilite_all(attrPath2, attrPathMatches.begin(), attrPathMatches.end(), "\e[0;1m")),
                                 name.version != "" ? " (" + name.version + ")" : "");
                             if (description != "")
                                 logger->cout(
-                                    "  %s", hilite_all(description, descriptionMatches, ANSI_NORMAL));
+                                    "  %s", hilite_all(description, descriptionMatches.begin(), descriptionMatches.end(), ANSI_NORMAL));
                         }
                     }
                 }

From b03fe13b5bb5ce540215a7e8df0d63a99f389db5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hubert=20G=C5=82uchowski?= <hubert.gluchowski19@gmail.com>
Date: Thu, 20 Jan 2022 17:48:38 +0100
Subject: [PATCH 446/567] Add some tests for multiple regex/match highlighting
 in `nix search`

---
 tests/search.sh | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/tests/search.sh b/tests/search.sh
index ee3261687..52e12f381 100644
--- a/tests/search.sh
+++ b/tests/search.sh
@@ -23,3 +23,16 @@ clearCache
 nix search -f search.nix '' |grep -q foo
 nix search -f search.nix '' |grep -q bar
 nix search -f search.nix '' |grep -q hello
+
+## Tests for multiple regex/match highlighting
+
+e=$'\x1b' # grep doesn't support \e, \033 or even \x1b
+# Multiple overlapping regexes
+(( $(nix search -f search.nix '' 'oo' 'foo' 'oo' | grep "$e\[32;1mfoo$e\\[0;1m" | wc -l) == 1 ))
+(( $(nix search -f search.nix '' 'broken b' 'en bar' | grep "$e\[32;1mbroken bar$e\\[0m" | wc -l) == 1 ))
+
+# Multiple matches
+# Searching for 'o' should yield the 'o' in 'broken bar', the 'oo' in foo and 'o' in hello
+(( $(nix search -f search.nix '' 'o' | grep -Eo "$e\[32;1mo{1,2}$e\[(0|0;1)m" | wc -l) == 3 ))
+# Searching for 'b' should yield the 'b' in bar and the two 'b's in 'broken bar'
+(( $(nix search -f search.nix '' 'b' | grep -Eo "$e\[32;1mb$e\[(0|0;1)m" | wc -l) == 3 ))

From 5ee937523da63b26cc6dd264cc3cb2717321c5cd Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Thu, 20 Jan 2022 20:45:34 +0000
Subject: [PATCH 447/567] Add back `copyClosure` for plain `StorePath`s

This was removed in 2e199673a523fa81de31ffdd2a25976ce0814631 when
`copyPath` transitioned to use `RealisedPath`. But then in
e9848beca704d27a13e28b4403251725bd485bb2 we added it back just for
`realisedPath`.

I think it is a good utility function --- one can easily imagine it
becoming optimized in the future, and copying paths *violating* the
closure is a very niche feature.

So if we have `copyPaths` for both sorts of paths, I think we should
have `copyClosure` for both sorts too.
---
 src/libstore/store-api.cc | 15 +++++++++++++++
 src/libstore/store-api.hh |  7 +++++++
 2 files changed, 22 insertions(+)

diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 970bafd88..bb9f0967d 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -1042,6 +1042,21 @@ void copyClosure(
     copyPaths(srcStore, dstStore, closure, repair, checkSigs, substitute);
 }
 
+void copyClosure(
+    Store & srcStore,
+    Store & dstStore,
+    const StorePathSet & storePaths,
+    RepairFlag repair,
+    CheckSigsFlag checkSigs,
+    SubstituteFlag substitute)
+{
+    if (&srcStore == &dstStore) return;
+
+    StorePathSet closure;
+    srcStore.computeFSClosure(storePaths, closure);
+    copyPaths(srcStore, dstStore, closure, repair, checkSigs, substitute);
+}
+
 std::optional<ValidPathInfo> decodeValidPathInfo(const Store & store, std::istream & str, std::optional<HashResult> hashGiven)
 {
     std::string path;
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 4fb6c40c7..81279c90b 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -794,6 +794,13 @@ void copyClosure(
     CheckSigsFlag checkSigs = CheckSigs,
     SubstituteFlag substitute = NoSubstitute);
 
+void copyClosure(
+    Store & srcStore, Store & dstStore,
+    const StorePathSet & paths,
+    RepairFlag repair = NoRepair,
+    CheckSigsFlag checkSigs = CheckSigs,
+    SubstituteFlag substitute = NoSubstitute);
+
 /* Remove the temporary roots file for this process.  Any temporary
    root becomes garbage after this point unless it has been registered
    as a (permanent) root. */

From fa53250c366708ea17dab9d0c549719f0609e3fa Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophane=20Hufschmitt?=
 <7226587+thufschmitt@users.noreply.github.com>
Date: Fri, 21 Jan 2022 09:52:40 +0100
Subject: [PATCH 448/567] Improve the description of the `--precise` option

Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
---
 src/nix/why-depends.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/nix/why-depends.cc b/src/nix/why-depends.cc
index 74377c912..657df30d7 100644
--- a/src/nix/why-depends.cc
+++ b/src/nix/why-depends.cc
@@ -60,7 +60,7 @@ struct CmdWhyDepends : SourceExprCommand
 
         addFlag({
             .longName = "precise",
-            .description = "For each edge of the graph, inspect the parent node to display the exact location in the path that causes the dependency",
+            .description = "For each edge in the dependency graph, show the files in the parent that cause the dependency.",
             .handler = {&precise, true},
         });
     }

From 128098040bc2bed1555b701dae17d5969cf2ce2d Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 21 Jan 2022 13:51:05 +0100
Subject: [PATCH 449/567] Fix exception handling around realisePath()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This no longer worked correctly because 'path' is uninitialised when
an exception occurs, leading to errors like

       … while importing ''

       at /nix/store/rrzz5b1pshvzh1437ac9nkl06br81lkv-source/flake.nix:352:13:

So move the adding of the error context into realisePath().
---
 src/libexpr/primops.cc | 115 ++++++++++++-----------------------------
 1 file changed, 33 insertions(+), 82 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 5c476ddd4..074181e13 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -102,17 +102,30 @@ static Path realisePath(EvalState & state, const Pos & pos, Value & v, const Rea
 {
     PathSet context;
 
-    Path path = flags.requireAbsolutePath
-        ? state.coerceToPath(pos, v, context)
-        : state.coerceToString(pos, v, context, false, false);
+    auto path = [&]()
+    {
+        try {
+            return flags.requireAbsolutePath
+                ? state.coerceToPath(pos, v, context)
+                : state.coerceToString(pos, v, context, false, false);
+        } catch (Error & e) {
+            e.addTrace(pos, "while realising the context of a path");
+            throw;
+        }
+    }();
 
-    StringMap rewrites = state.realiseContext(context);
+    try {
+        StringMap rewrites = state.realiseContext(context);
 
-    auto realPath = state.toRealPath(rewriteStrings(path, rewrites), context);
+        auto realPath = state.toRealPath(rewriteStrings(path, rewrites), context);
 
-    return flags.checkForPureEval
-        ? state.checkSourcePath(realPath)
-        : realPath;
+        return flags.checkForPureEval
+            ? state.checkSourcePath(realPath)
+            : realPath;
+    } catch (Error & e) {
+        e.addTrace(pos, "while realising the context of path '%s'", path);
+        throw;
+    }
 }
 
 /* Add and attribute to the given attribute map from the output name to
@@ -150,18 +163,7 @@ static void mkOutputString(
    argument. */
 static void import(EvalState & state, const Pos & pos, Value & vPath, Value * vScope, Value & v)
 {
-    Path path;
-    try {
-        path = realisePath(state, pos, vPath);
-    } catch (InvalidPathError & e) {
-        throw EvalError({
-            .msg = hintfmt("cannot import '%1%', since path '%2%' is not valid", path, e.path),
-            .errPos = pos
-        });
-    } catch (Error & e) {
-        e.addTrace(pos, "while importing '%s'", path);
-        throw;
-    }
+    auto path = realisePath(state, pos, vPath);
 
     // FIXME
     auto isValidDerivationInStore = [&]() -> std::optional<StorePath> {
@@ -314,18 +316,7 @@ extern "C" typedef void (*ValueInitializer)(EvalState & state, Value & v);
 /* Load a ValueInitializer from a DSO and return whatever it initializes */
 void prim_importNative(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    Path path;
-    try {
-        path = realisePath(state, pos, *args[0]);
-    } catch (InvalidPathError & e) {
-        throw EvalError({
-            .msg = hintfmt("cannot import '%1%', since path '%2%' is not valid", path, e.path),
-            .errPos = pos
-        });
-    } catch (Error & e) {
-        e.addTrace(pos, "while importing '%s'", path);
-        throw;
-    }
+    auto path = realisePath(state, pos, *args[0]);
 
     string sym = state.forceStringNoCtx(*args[1], pos);
 
@@ -1379,22 +1370,12 @@ static RegisterPrimOp primop_storePath({
 
 static void prim_pathExists(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    Path path;
-    try {
-        // We don’t check the path right now, because we don’t want to throw if
-        // the path isn’t allowed, but just return false
-        // (and we can’t just catch the exception here because we still want to
-        // throw if something in the evaluation of `*args[0]` tries to access an
-        // unauthorized path)
-        path = realisePath(state, pos, *args[0], { .checkForPureEval = false });
-    } catch (InvalidPathError & e) {
-        throw EvalError({
-            .msg = hintfmt(
-                "cannot check the existence of '%1%', since path '%2%' is not valid",
-                path, e.path),
-            .errPos = pos
-        });
-    }
+    /* We don’t check the path right now, because we don’t want to
+      throw if the path isn’t allowed, but just return false (and we
+      can’t just catch the exception here because we still want to
+      throw if something in the evaluation of `*args[0]` tries to
+      access an unauthorized path). */
+    auto path = realisePath(state, pos, *args[0], { .checkForPureEval = false });
 
     try {
         v.mkBool(pathExists(state.checkSourcePath(path)));
@@ -1460,15 +1441,7 @@ static RegisterPrimOp primop_dirOf({
 /* Return the contents of a file as a string. */
 static void prim_readFile(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    Path path;
-    try {
-        path = realisePath(state, pos, *args[0]);
-    } catch (InvalidPathError & e) {
-        throw EvalError({
-            .msg = hintfmt("cannot read '%1%', since path '%2%' is not valid", path, e.path),
-            .errPos = pos
-        });
-    }
+    auto path = realisePath(state, pos, *args[0]);
     string s = readFile(path);
     if (s.find((char) 0) != string::npos)
         throw Error("the contents of the file '%1%' cannot be represented as a Nix string", path);
@@ -1512,16 +1485,7 @@ static void prim_findFile(EvalState & state, const Pos & pos, Value * * args, Va
             pos
         );
 
-        Path path;
-
-        try {
-            path = realisePath(state, pos, *i->value, { .requireAbsolutePath = false });
-        } catch (InvalidPathError & e) {
-            throw EvalError({
-                .msg = hintfmt("cannot find '%1%', since path '%2%' is not valid", path, e.path),
-                .errPos = pos
-            });
-        }
+        auto path = realisePath(state, pos, *i->value, { .requireAbsolutePath = false });
 
         searchPath.emplace_back(prefix, path);
     }
@@ -1548,12 +1512,7 @@ static void prim_hashFile(EvalState & state, const Pos & pos, Value * * args, Va
             .errPos = pos
         });
 
-    Path path;
-    try {
-        path = realisePath(state, pos, *args[1]);
-    } catch (InvalidPathError & e) {
-        throw EvalError("cannot read '%s' since path '%s' is not valid, at %s", path, e.path, pos);
-    }
+    auto path = realisePath(state, pos, *args[1]);
 
     v.mkString(hashFile(*ht, path).to_string(Base16, false));
 }
@@ -1572,15 +1531,7 @@ static RegisterPrimOp primop_hashFile({
 /* Read a directory (without . or ..) */
 static void prim_readDir(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    Path path;
-    try {
-        path = realisePath(state, pos, *args[0]);
-    } catch (InvalidPathError & e) {
-        throw EvalError({
-            .msg = hintfmt("cannot read '%1%', since path '%2%' is not valid", path, e.path),
-            .errPos = pos
-        });
-    }
+    auto path = realisePath(state, pos, *args[0]);
 
     DirEntries entries = readDirectory(path);
 

From c79087eb2a19fcfea65e1f31fd087f858f0edd8c Mon Sep 17 00:00:00 2001
From: Rok Garbas <rok@garbas.si>
Date: Fri, 21 Jan 2022 14:40:34 +0100
Subject: [PATCH 450/567] also tagging with latest commit with a `master` tag

---
 .github/workflows/ci.yml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 4ae182cf1..77d9f5250 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -98,9 +98,11 @@ jobs:
     - run: nix-build -A checks.$(nix-instantiate --eval -E 'builtins.currentSystem' --json).dockerImage
     - run: docker load -i ./result/image.tar.gz
     - run: docker tag nix:$NIX_VERSION nixos/nix:$NIX_VERSION
+    - run: docker tag nix:$NIX_VERSION nixos/nix:master
     - name: Login to Docker Hub
       uses: docker/login-action@v1
       with:
         username: ${{ secrets.DOCKERHUB_USERNAME }}
         password: ${{ secrets.DOCKERHUB_TOKEN }}
     - run: docker push nixos/nix:$NIX_VERSION
+    - run: docker push nixos/nix:master

From d463e1176093da1d4541425bc98ecc58e62dcef5 Mon Sep 17 00:00:00 2001
From: Rok Garbas <rok@garbas.si>
Date: Fri, 21 Jan 2022 14:50:34 +0100
Subject: [PATCH 451/567] Adding docs regarding the docker image from master

---
 doc/manual/src/release-notes/rl-next.md | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index f20acbd3f..301683246 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -1,6 +1,8 @@
 # Release X.Y (202?-??-??)
 
-* The Nix cli now searches for a flake.nix up until the root of the current git repository or a filesystem boundary rather than just in the current directory
+* The Nix cli now searches for a `flake.nix` up until the root of the current
+  git repository or a filesystem boundary rather than just in the current
+  directory.
 * The TOML parser used by `builtins.fromTOML` has been replaced by [a
   more compliant one](https://github.com/ToruNiina/toml11).
 * Added `:st`/`:show-trace` commands to nix repl, which are used to
@@ -13,3 +15,5 @@
   to override the commit summary used when commiting an updated lockfile.
   This may be used in conjunction with the nixConfig attribute in
   `flake.nix` to better conform to repository conventions.
+* `docker run -ti nixos/nix:master` will place you in the docker container with
+  the latest version of Nix from the `master` branch.

From 0407436b0f15900399d11da43178cd09fddba0af Mon Sep 17 00:00:00 2001
From: Robert Hensing <roberth@users.noreply.github.com>
Date: Fri, 21 Jan 2022 17:25:37 +0100
Subject: [PATCH 452/567] derivations.cc: Use larger buffer in printString

If we want to be careful about hitting the stack protector page, we should use `-fstack-check` instead.

Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
---
 src/libstore/derivations.cc | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index 5233cfe67..3e3d50144 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -273,15 +273,7 @@ Derivation parseDerivation(const Store & store, std::string && s, std::string_vi
 
 static void printString(string & res, std::string_view s)
 {
-    // Large stack allocations can skip past the stack protection page.
-    const size_t stack_protection_size = 4096;
-    // We reduce the max stack allocated buffer by an extra amount to increase
-    // the chance of hitting it, even when `fun`'s first access is some distance
-    // into its *further* stack frame, particularly if the call was inlined and
-    // therefore not writing a frame pointer.
-    const size_t play = 64 * sizeof(char *); // 512B on 64b archs
-
-    boost::container::small_vector<char, stack_protection_size - play> buffer;
+    boost::container::small_vector<char, 64 * 1024> buffer;
     buffer.reserve(s.size() * 2 + 2);
     char * buf = buffer.data();
     char * p = buf;

From bdb5e0382106d3238cae69095cd1f9ea04679951 Mon Sep 17 00:00:00 2001
From: "Travis A. Everett" <travis.a.everett@gmail.com>
Date: Thu, 20 Jan 2022 20:32:19 -0600
Subject: [PATCH 453/567] install-darwin: dodge bash 3.2 command bug

The script is trying to find chown in a cross-platform-like
way, but there's some sort of deficiency in `command -p` in
the default macOS bash 3.2. It looks like it will just use
whatever PATH is already set, instead of the "default" path.

This attempts to hard-set a PATH via `getconf PATH`. It will
just set an empty PATH if that fails for some reason. A
properly-functioning `command -p` should not care what we
set the PATH to here one way or the other.

Hopefully fixes #5768.
---
 scripts/install-multi-user.sh | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/scripts/install-multi-user.sh b/scripts/install-multi-user.sh
index 3a24296ee..33e4eaa14 100644
--- a/scripts/install-multi-user.sh
+++ b/scripts/install-multi-user.sh
@@ -576,18 +576,37 @@ create_directories() {
         # since this bit is cross-platform:
         # - first try with `command -vp` to try and find
         #   chown in the usual places
+        #   * to work around some sort of deficiency in
+        #     `command -p` in macOS bash 3.2, we also add
+        #     PATH="$(getconf PATH 2>/dev/null)". As long as
+        #     getconf is found, this should set a sane PATH
+        #     which `command -p` in bash 3.2 appears to use.
+        #     A bash with a properly-working `command -p`
+        #     should ignore this hard-set PATH in favor of
+        #     whatever it obtains internally. See
+        #     github.com/NixOS/nix/issues/5768
         # - fall back on `command -v` which would find
         #   any chown on path
         # if we don't find one, the command is already
         # hiding behind || true, and the general state
         # should be one the user can repair once they
         # figure out where chown is...
-        local get_chr_own="$(command -vp chown)"
+        local get_chr_own="$(PATH="$(getconf PATH 2>/dev/null)" command -vp chown)"
         if [[ -z "$get_chr_own" ]]; then
             get_chr_own="$(command -v chown)"
         fi
-        _sudo "to take root ownership of existing Nix store files" \
-              "$get_chr_own" -R "root:$NIX_BUILD_GROUP_NAME" "$NIX_ROOT" || true
+
+        if [[ -z "$get_chr_own" ]]; then
+            reminder <<EOF
+I wanted to take root ownership of existing Nix store files,
+but I couldn't locate 'chown'. (You may need to fix your PATH.)
+To manually change file ownership, you can run:
+    sudo chown -R 'root:$NIX_BUILD_GROUP_NAME' '$NIX_ROOT'
+EOF
+        else
+            _sudo "to take root ownership of existing Nix store files" \
+                  "$get_chr_own" -R "root:$NIX_BUILD_GROUP_NAME" "$NIX_ROOT" || true
+        fi
     fi
     _sudo "to make the basic directory structure of Nix (part 1)" \
           install -dv -m 0755 /nix /nix/var /nix/var/log /nix/var/log/nix /nix/var/log/nix/drvs /nix/var/nix{,/db,/gcroots,/profiles,/temproots,/userpool} /nix/var/nix/{gcroots,profiles}/per-user

From 1e0b7cdc3f3169ae85d71df5b3f80872a8258779 Mon Sep 17 00:00:00 2001
From: Fishhh <hubert.gluchowski19@gmail.com>
Date: Fri, 21 Jan 2022 16:13:34 +0100
Subject: [PATCH 454/567] Move hilite_all into libutil and rename it to
 hiliteMatches

The signature was also changed so the function now accepts a vector
instead of an iterator
---
 src/libutil/fmt.cc | 38 ++++++++++++++++++++++++++++++++
 src/libutil/fmt.hh |  3 +++
 src/nix/search.cc  | 54 ++++------------------------------------------
 3 files changed, 45 insertions(+), 50 deletions(-)
 create mode 100644 src/libutil/fmt.cc

diff --git a/src/libutil/fmt.cc b/src/libutil/fmt.cc
new file mode 100644
index 000000000..914fb62b2
--- /dev/null
+++ b/src/libutil/fmt.cc
@@ -0,0 +1,38 @@
+#include <regex>
+
+namespace nix {
+
+std::string hiliteMatches(const std::string &s, std::vector<std::smatch> matches, std::string prefix, std::string postfix) {
+    // Avoid copy on zero matches
+    if (matches.size() == 0)
+        return s;
+
+    std::sort(matches.begin(), matches.end(), [](const auto &a, const auto &b) {
+        return a.position() < b.position();
+    });
+
+    std::string out;
+    ssize_t last_end = 0;
+
+    for (auto it = matches.begin(); it != matches.end();) {
+        auto m = *it;
+        size_t start = m.position();
+        out.append(s.substr(last_end, m.position() - last_end));
+        // Merge continous matches
+        ssize_t end = start + m.length();
+        while(++it != matches.end() && (*it).position() <= end) {
+            auto n = *it;
+            ssize_t nend = start + (n.position() - start + n.length());
+            if(nend > end)
+                end = nend;
+        }
+        out.append(prefix);
+        out.append(s.substr(start, end - start));
+        out.append(postfix);
+        last_end = end;
+    }
+    out.append(s.substr(last_end));
+    return out;
+}
+
+}
diff --git a/src/libutil/fmt.hh b/src/libutil/fmt.hh
index fd335b811..06c4a2049 100644
--- a/src/libutil/fmt.hh
+++ b/src/libutil/fmt.hh
@@ -2,6 +2,7 @@
 
 #include <boost/format.hpp>
 #include <string>
+#include <regex>
 #include "ansicolor.hh"
 
 
@@ -154,4 +155,6 @@ inline hintformat hintfmt(std::string plain_string)
     // we won't be receiving any args in this case, so just print the original string
     return hintfmt("%s", normaltxt(plain_string));
 }
+
+std::string hiliteMatches(const std::string &s, std::vector<std::smatch> matches, std::string prefix, std::string postfix);
 }
diff --git a/src/nix/search.cc b/src/nix/search.cc
index 01211bae3..0d10d8c2e 100644
--- a/src/nix/search.cc
+++ b/src/nix/search.cc
@@ -9,8 +9,8 @@
 #include "shared.hh"
 #include "eval-cache.hh"
 #include "attr-path.hh"
+#include "fmt.hh"
 
-#include <iterator>
 #include <regex>
 #include <fstream>
 
@@ -21,52 +21,6 @@ std::string wrap(std::string prefix, std::string s)
     return prefix + s + ANSI_NORMAL;
 }
 
-#define HILITE_COLOR ANSI_GREEN
-
-std::string hilite(const std::string & s, const std::smatch & m, std::string postfix)
-{
-    return
-        m.empty()
-        ? s
-        : std::string(m.prefix())
-          + HILITE_COLOR + std::string(m.str()) + postfix
-          + std::string(m.suffix());
-}
-
-template<class Iter>
-std::string hilite_all(const std::string &s, Iter matches_first, Iter matches_last, std::string postfix) {
-    // Avoid copy on zero matches
-    if (matches_first == matches_last)
-        return s;
-
-    std::sort(matches_first, matches_last, [](const auto &a, const auto &b) {
-        return a.position() < b.position();
-    });
-
-    std::string out;
-    ssize_t last_end = 0;
-
-    for (Iter it = matches_first; it != matches_last; ++it) {
-        auto m = *it;
-        size_t start = m.position();
-        out.append(s.substr(last_end, m.position() - last_end));
-        // Merge continous matches
-        ssize_t end = start + m.length();
-        while(it + 1 != matches_last && (*(it + 1)).position() <= end) {
-            auto n = *++it;
-            ssize_t nend = start + (n.position() - start + n.length());
-            if(nend > end)
-                end = nend;
-        }
-        out.append(HILITE_COLOR);
-        out.append(s.substr(start, end - start));
-        out.append(postfix);
-        last_end = end;
-    }
-    out.append(s.substr(last_end));
-    return out;
-}
-
 struct CmdSearch : InstallableCommand, MixJSON
 {
     std::vector<std::string> res;
@@ -177,15 +131,15 @@ struct CmdSearch : InstallableCommand, MixJSON
                             jsonElem.attr("version", name.version);
                             jsonElem.attr("description", description);
                         } else {
-                            auto name2 = hilite_all(name.name, nameMatches.begin(), nameMatches.end(), "\e[0;2m");
+                            auto name2 = hiliteMatches(name.name, std::move(nameMatches), ANSI_GREEN, "\e[0;2m");
                             if (results > 1) logger->cout("");
                             logger->cout(
                                 "* %s%s",
-                                wrap("\e[0;1m", hilite_all(attrPath2, attrPathMatches.begin(), attrPathMatches.end(), "\e[0;1m")),
+                                wrap("\e[0;1m", hiliteMatches(attrPath2, std::move(attrPathMatches), ANSI_GREEN, "\e[0;1m")),
                                 name.version != "" ? " (" + name.version + ")" : "");
                             if (description != "")
                                 logger->cout(
-                                    "  %s", hilite_all(description, descriptionMatches.begin(), descriptionMatches.end(), ANSI_NORMAL));
+                                    "  %s", hiliteMatches(description, std::move(descriptionMatches), ANSI_GREEN, ANSI_NORMAL));
                         }
                     }
                 }

From f82a426502dfd8f583eff3e8b0b895989e10d730 Mon Sep 17 00:00:00 2001
From: Fishhh <hubert.gluchowski19@gmail.com>
Date: Fri, 21 Jan 2022 19:38:06 +0100
Subject: [PATCH 455/567] Add some tests for hiliteMatches in libutil

---
 src/libutil/tests/fmt.cc | 68 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 src/libutil/tests/fmt.cc

diff --git a/src/libutil/tests/fmt.cc b/src/libutil/tests/fmt.cc
new file mode 100644
index 000000000..33772162c
--- /dev/null
+++ b/src/libutil/tests/fmt.cc
@@ -0,0 +1,68 @@
+#include "fmt.hh"
+
+#include <gtest/gtest.h>
+
+#include <regex>
+
+namespace nix {
+/* ----------- tests for fmt.hh -------------------------------------------------*/
+
+    TEST(hiliteMatches, noHighlight) {
+        ASSERT_STREQ(hiliteMatches("Hello, world!", std::vector<std::smatch>(), "(", ")").c_str(), "Hello, world!");
+    }
+
+    TEST(hiliteMatches, simpleHighlight) {
+        std::string str = "Hello, world!";
+        std::regex re = std::regex("world");
+        auto matches = std::vector(std::sregex_iterator(str.begin(), str.end(), re), std::sregex_iterator());
+        ASSERT_STREQ(
+                    hiliteMatches(str, matches, "(", ")").c_str(),
+                    "Hello, (world)!"
+        );
+    }
+
+    TEST(hiliteMatches, multipleMatches) {
+        std::string str = "Hello, world, world, world, world, world, world, Hello!";
+        std::regex re = std::regex("world");
+        auto matches = std::vector(std::sregex_iterator(str.begin(), str.end(), re), std::sregex_iterator());
+        ASSERT_STREQ(
+                    hiliteMatches(str, matches, "(", ")").c_str(),
+                    "Hello, (world), (world), (world), (world), (world), (world), Hello!"
+        );
+    }
+
+    TEST(hiliteMatches, overlappingMatches) {
+        std::string str = "world, Hello, world, Hello, world, Hello, world, Hello, world!";
+        std::regex re = std::regex("Hello, world");
+        std::regex re2 = std::regex("world, Hello");
+        auto v = std::vector(std::sregex_iterator(str.begin(), str.end(), re), std::sregex_iterator());
+        for(auto it = std::sregex_iterator(str.begin(), str.end(), re2); it != std::sregex_iterator(); ++it) {
+            v.push_back(*it);
+        }
+        ASSERT_STREQ(
+                    hiliteMatches(str, v, "(", ")").c_str(),
+                    "(world, Hello, world, Hello, world, Hello, world, Hello, world)!"
+        );
+    }
+
+    TEST(hiliteMatches, complexOverlappingMatches) {
+        std::string str = "legacyPackages.x86_64-linux.git-crypt";
+        std::vector regexes = {
+            std::regex("t-cry"),
+            std::regex("ux\\.git-cry"),
+            std::regex("git-c"),
+            std::regex("pt"),
+        };
+        std::vector<std::smatch> matches;
+        for(auto regex : regexes)
+        {
+            for(auto it = std::sregex_iterator(str.begin(), str.end(), regex); it != std::sregex_iterator(); ++it) {
+                matches.push_back(*it);
+            }
+        }
+        ASSERT_STREQ(
+                    hiliteMatches(str, matches, "(", ")").c_str(),
+                    "legacyPackages.x86_64-lin(ux.git-crypt)"
+        );
+    }
+}

From 49b0bb020663b7283549754a826b1346c93a8bbb Mon Sep 17 00:00:00 2001
From: Kevin Amado <kamadorueda@gmail.com>
Date: Sat, 27 Nov 2021 12:40:24 -0500
Subject: [PATCH 456/567] forceValue: make pos mandatory

- Make passing the position to `forceValue` mandatory,
  this way we remember people that the position is
  important for better error messages
- Add pos to all `forceValue` calls
---
 src/libcmd/installables.cc             | 11 ++++++-----
 src/libexpr/attr-path.cc               |  2 +-
 src/libexpr/eval-cache.cc              |  2 +-
 src/libexpr/eval-inline.hh             |  4 ++--
 src/libexpr/eval.cc                    | 17 +++++++++--------
 src/libexpr/eval.hh                    |  2 +-
 src/libexpr/get-drvs.cc                |  4 ++--
 src/nix-build/nix-build.cc             |  2 +-
 src/nix-env/user-env.cc                |  2 +-
 src/nix-instantiate/nix-instantiate.cc |  2 +-
 src/nix/eval.cc                        |  2 +-
 src/nix/repl.cc                        |  4 ++--
 12 files changed, 28 insertions(+), 26 deletions(-)

diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index 0c2db0399..268861ce8 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -198,8 +198,9 @@ void SourceExprCommand::completeInstallable(std::string_view prefix)
             prefix_ = "";
         }
 
-        Value &v1(*findAlongAttrPath(*state, prefix_, *autoArgs, root).first);
-        state->forceValue(v1);
+        auto [v, pos] = findAlongAttrPath(*state, prefix_, *autoArgs, root);
+        Value &v1(*v);
+        state->forceValue(v1, pos);
         Value v2;
         state->autoCallFunction(*autoArgs, v1, v2);
 
@@ -446,7 +447,7 @@ struct InstallableAttrPath : InstallableValue
     std::pair<Value *, Pos> toValue(EvalState & state) override
     {
         auto [vRes, pos] = findAlongAttrPath(state, attrPath, *cmd.getAutoArgs(state), **v);
-        state.forceValue(*vRes);
+        state.forceValue(*vRes, pos);
         return {vRes, pos};
     }
 
@@ -496,7 +497,7 @@ Value * InstallableFlake::getFlakeOutputs(EvalState & state, const flake::Locked
     auto aOutputs = vFlake->attrs->get(state.symbols.create("outputs"));
     assert(aOutputs);
 
-    state.forceValue(*aOutputs->value);
+    state.forceValue(*aOutputs->value, aOutputs->value->determinePos(noPos));
 
     return aOutputs->value;
 }
@@ -608,7 +609,7 @@ std::pair<Value *, Pos> InstallableFlake::toValue(EvalState & state)
     for (auto & attrPath : getActualAttrPaths()) {
         try {
             auto [v, pos] = findAlongAttrPath(state, attrPath, *emptyArgs, *vOutputs);
-            state.forceValue(*v);
+            state.forceValue(*v, pos);
             return {v, pos};
         } catch (AttrPathNotFound & e) {
         }
diff --git a/src/libexpr/attr-path.cc b/src/libexpr/attr-path.cc
index c50c6d92b..8ec24269f 100644
--- a/src/libexpr/attr-path.cc
+++ b/src/libexpr/attr-path.cc
@@ -58,7 +58,7 @@ std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const string & attr
         Value * vNew = state.allocValue();
         state.autoCallFunction(autoArgs, *v, *vNew);
         v = vNew;
-        state.forceValue(*v);
+        state.forceValue(*v, v->determinePos(vIn.determinePos(noPos)));
 
         /* It should evaluate to either a set or an expression,
            according to what is specified in the attrPath. */
diff --git a/src/libexpr/eval-cache.cc b/src/libexpr/eval-cache.cc
index d7e21783d..a92acafa8 100644
--- a/src/libexpr/eval-cache.cc
+++ b/src/libexpr/eval-cache.cc
@@ -381,7 +381,7 @@ Value & AttrCursor::forceValue()
     auto & v = getValue();
 
     try {
-        root->state.forceValue(v);
+        root->state.forceValue(v, v.determinePos(noPos));
     } catch (EvalError &) {
         debug("setting '%s' to failed", getAttrPathStr());
         if (root->db)
diff --git a/src/libexpr/eval-inline.hh b/src/libexpr/eval-inline.hh
index 655408cd3..cd58315ba 100644
--- a/src/libexpr/eval-inline.hh
+++ b/src/libexpr/eval-inline.hh
@@ -53,7 +53,7 @@ void EvalState::forceValue(Value & v, const Pos & pos)
 
 inline void EvalState::forceAttrs(Value & v)
 {
-    forceValue(v);
+    forceValue(v, v.determinePos(noPos));
     if (v.type() != nAttrs)
         throwTypeError("value is %1% while a set was expected", v);
 }
@@ -69,7 +69,7 @@ inline void EvalState::forceAttrs(Value & v, const Pos & pos)
 
 inline void EvalState::forceList(Value & v)
 {
-    forceValue(v);
+    forceValue(v, v.determinePos(noPos));
     if (!v.isList())
         throwTypeError("value is %1% while a list was expected", v);
 }
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 94ffab175..ee3d86296 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -1280,7 +1280,7 @@ void ExprOpHasAttr::eval(EvalState & state, Env & env, Value & v)
     e->eval(state, env, vTmp);
 
     for (auto & i : attrPath) {
-        state.forceValue(*vAttrs);
+        state.forceValue(*vAttrs, vAttrs->determinePos(noPos));
         Bindings::iterator j;
         Symbol name = getName(i, state, env);
         if (vAttrs->type() != nAttrs ||
@@ -1494,14 +1494,15 @@ void EvalState::incrFunctionCall(ExprLambda * fun)
 
 void EvalState::autoCallFunction(Bindings & args, Value & fun, Value & res)
 {
-    forceValue(fun);
+    Pos pos = fun.determinePos(noPos);
+    forceValue(fun, pos);
 
     if (fun.type() == nAttrs) {
         auto found = fun.attrs->find(sFunctor);
         if (found != fun.attrs->end()) {
             Value * v = allocValue();
-            callFunction(*found->value, fun, *v, noPos);
-            forceValue(*v);
+            callFunction(*found->value, fun, *v, pos);
+            forceValue(*v, pos);
             return autoCallFunction(args, *v, res);
         }
     }
@@ -1787,7 +1788,7 @@ void EvalState::forceValueDeep(Value & v)
     recurse = [&](Value & v) {
         if (!seen.insert(&v).second) return;
 
-        forceValue(v);
+        forceValue(v, v.determinePos(noPos));
 
         if (v.type() == nAttrs) {
             for (auto & i : *v.attrs)
@@ -1924,7 +1925,7 @@ bool EvalState::isDerivation(Value & v)
     if (v.type() != nAttrs) return false;
     Bindings::iterator i = v.attrs->find(sType);
     if (i == v.attrs->end()) return false;
-    forceValue(*i->value);
+    forceValue(*i->value, *i->pos);
     if (i->value->type() != nString) return false;
     return strcmp(i->value->string.s, "derivation") == 0;
 }
@@ -2036,8 +2037,8 @@ Path EvalState::coerceToPath(const Pos & pos, Value & v, PathSet & context)
 
 bool EvalState::eqValues(Value & v1, Value & v2)
 {
-    forceValue(v1);
-    forceValue(v2);
+    forceValue(v1, v1.determinePos(noPos));
+    forceValue(v2, v2.determinePos(noPos));
 
     /* !!! Hack to support some old broken code that relies on pointer
        equality tests between sets.  (Specifically, builderDefs calls
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 82ce9d1b3..f0b94f440 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -221,7 +221,7 @@ public:
        of the evaluation of the thunk.  If `v' is a delayed function
        application, call the function and overwrite `v' with the
        result.  Otherwise, this is a no-op. */
-    inline void forceValue(Value & v, const Pos & pos = noPos);
+    inline void forceValue(Value & v, const Pos & pos);
 
     /* Force a value, then recursively force list elements and
        attributes. */
diff --git a/src/libexpr/get-drvs.cc b/src/libexpr/get-drvs.cc
index 25fd9b949..fe1d11505 100644
--- a/src/libexpr/get-drvs.cc
+++ b/src/libexpr/get-drvs.cc
@@ -172,7 +172,7 @@ StringSet DrvInfo::queryMetaNames()
 
 bool DrvInfo::checkMeta(Value & v)
 {
-    state->forceValue(v);
+    state->forceValue(v, v.determinePos(noPos));
     if (v.type() == nList) {
         for (auto elem : v.listItems())
             if (!checkMeta(*elem)) return false;
@@ -278,7 +278,7 @@ static bool getDerivation(EvalState & state, Value & v,
     bool ignoreAssertionFailures)
 {
     try {
-        state.forceValue(v);
+        state.forceValue(v, v.determinePos(noPos));
         if (!state.isDerivation(v)) return true;
 
         /* Remove spurious duplicates (e.g., a set like `rec { x =
diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index 471a03ac7..66aa145a4 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -318,7 +318,7 @@ static void main_nix_build(int argc, char * * argv)
 
         for (auto & i : attrPaths) {
             Value & v(*findAlongAttrPath(*state, i, *autoArgs, vRoot).first);
-            state->forceValue(v);
+            state->forceValue(v, v.determinePos(noPos));
             getDerivations(*state, v, "", *autoArgs, drvs, false);
         }
     }
diff --git a/src/nix-env/user-env.cc b/src/nix-env/user-env.cc
index 68c1c16b2..727338105 100644
--- a/src/nix-env/user-env.cc
+++ b/src/nix-env/user-env.cc
@@ -129,7 +129,7 @@ bool createUserEnv(EvalState & state, DrvInfos & elems,
 
     /* Evaluate it. */
     debug("evaluating user environment builder");
-    state.forceValue(topLevel);
+    state.forceValue(topLevel, topLevel.determinePos(noPos));
     PathSet context;
     Attr & aDrvPath(*topLevel.attrs->find(state.sDrvPath));
     auto topLevelDrv = state.store->parseStorePath(state.coerceToPath(*aDrvPath.pos, *aDrvPath.value, context));
diff --git a/src/nix-instantiate/nix-instantiate.cc b/src/nix-instantiate/nix-instantiate.cc
index 19a954ddd..8836f810c 100644
--- a/src/nix-instantiate/nix-instantiate.cc
+++ b/src/nix-instantiate/nix-instantiate.cc
@@ -40,7 +40,7 @@ void processExpr(EvalState & state, const Strings & attrPaths,
 
     for (auto & i : attrPaths) {
         Value & v(*findAlongAttrPath(state, i, autoArgs, vRoot).first);
-        state.forceValue(v);
+        state.forceValue(v, v.determinePos(noPos));
 
         PathSet context;
         if (evalOnly) {
diff --git a/src/nix/eval.cc b/src/nix/eval.cc
index c7517cf79..686244be0 100644
--- a/src/nix/eval.cc
+++ b/src/nix/eval.cc
@@ -81,7 +81,7 @@ struct CmdEval : MixJSON, InstallableCommand
 
             recurse = [&](Value & v, const Pos & pos, const Path & path)
             {
-                state->forceValue(v);
+                state->forceValue(v, pos);
                 if (v.type() == nString)
                     // FIXME: disallow strings with contexts?
                     writeFile(path, v.string.s);
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index be9f96836..5c2bf4bfd 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -712,7 +712,7 @@ void NixRepl::evalString(string s, Value & v)
 {
     Expr * e = parseString(s);
     e->eval(*state, *env, v);
-    state->forceValue(v);
+    state->forceValue(v, v.determinePos(noPos));
 }
 
 
@@ -742,7 +742,7 @@ std::ostream & NixRepl::printValue(std::ostream & str, Value & v, unsigned int m
     str.flush();
     checkInterrupt();
 
-    state->forceValue(v);
+    state->forceValue(v, v.determinePos(noPos));
 
     switch (v.type()) {
 

From 1472e045a757af4e289801673b456b78ebf18933 Mon Sep 17 00:00:00 2001
From: Kevin Amado <kamadorueda@gmail.com>
Date: Fri, 21 Jan 2022 10:04:09 -0500
Subject: [PATCH 457/567] avoid unnecesary calls

---
 src/libexpr/eval-inline.hh | 16 ----------------
 src/libexpr/eval.hh        |  2 --
 2 files changed, 18 deletions(-)

diff --git a/src/libexpr/eval-inline.hh b/src/libexpr/eval-inline.hh
index cd58315ba..08acb0877 100644
--- a/src/libexpr/eval-inline.hh
+++ b/src/libexpr/eval-inline.hh
@@ -51,14 +51,6 @@ void EvalState::forceValue(Value & v, const Pos & pos)
 }
 
 
-inline void EvalState::forceAttrs(Value & v)
-{
-    forceValue(v, v.determinePos(noPos));
-    if (v.type() != nAttrs)
-        throwTypeError("value is %1% while a set was expected", v);
-}
-
-
 inline void EvalState::forceAttrs(Value & v, const Pos & pos)
 {
     forceValue(v, pos);
@@ -67,14 +59,6 @@ inline void EvalState::forceAttrs(Value & v, const Pos & pos)
 }
 
 
-inline void EvalState::forceList(Value & v)
-{
-    forceValue(v, v.determinePos(noPos));
-    if (!v.isList())
-        throwTypeError("value is %1% while a list was expected", v);
-}
-
-
 inline void EvalState::forceList(Value & v, const Pos & pos)
 {
     forceValue(v, pos);
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index f0b94f440..11d62ba04 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -231,9 +231,7 @@ public:
     NixInt forceInt(Value & v, const Pos & pos);
     NixFloat forceFloat(Value & v, const Pos & pos);
     bool forceBool(Value & v, const Pos & pos);
-    inline void forceAttrs(Value & v);
     inline void forceAttrs(Value & v, const Pos & pos);
-    inline void forceList(Value & v);
     inline void forceList(Value & v, const Pos & pos);
     void forceFunction(Value & v, const Pos & pos); // either lambda or primop
     string forceString(Value & v, const Pos & pos = noPos);

From c3896e19d0001b4f729017aa96d0a44b6e479a52 Mon Sep 17 00:00:00 2001
From: Kevin Amado <kamadorueda@gmail.com>
Date: Fri, 21 Jan 2022 10:43:16 -0500
Subject: [PATCH 458/567] forceAttrs: make pos mandatory

---
 src/libcmd/installables.cc | 2 +-
 src/libexpr/eval-cache.cc  | 2 +-
 src/libexpr/eval.cc        | 2 +-
 src/libexpr/get-drvs.cc    | 2 +-
 src/libexpr/primops.cc     | 4 ++--
 src/nix/flake.cc           | 5 +++--
 src/nix/prefetch.cc        | 4 ++--
 src/nix/repl.cc            | 4 ++--
 8 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index 268861ce8..ec4f8f6f9 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -522,7 +522,7 @@ ref<eval_cache::EvalCache> openEvalCache(
             auto vFlake = state.allocValue();
             flake::callFlake(state, *lockedFlake, *vFlake);
 
-            state.forceAttrs(*vFlake);
+            state.forceAttrs(*vFlake, noPos);
 
             auto aOutputs = vFlake->attrs->get(state.symbols.create("outputs"));
             assert(aOutputs);
diff --git a/src/libexpr/eval-cache.cc b/src/libexpr/eval-cache.cc
index a92acafa8..222a34116 100644
--- a/src/libexpr/eval-cache.cc
+++ b/src/libexpr/eval-cache.cc
@@ -336,7 +336,7 @@ Value & AttrCursor::getValue()
     if (!_value) {
         if (parent) {
             auto & vParent = parent->first->getValue();
-            root->state.forceAttrs(vParent);
+            root->state.forceAttrs(vParent, vParent.determinePos(noPos));
             auto attr = vParent.attrs->get(parent->second);
             if (!attr)
                 throw Error("attribute '%s' is unexpectedly missing", getAttrPathStr());
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index ee3d86296..e1c089b95 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -1132,7 +1132,7 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
            Hence we need __overrides.) */
         if (hasOverrides) {
             Value * vOverrides = (*v.attrs)[overrides->second.displ].value;
-            state.forceAttrs(*vOverrides);
+            state.forceAttrs(*vOverrides, vOverrides->determinePos(noPos));
             Bindings * newBnds = state.allocBindings(v.attrs->capacity() + vOverrides->attrs->size());
             for (auto & i : *v.attrs)
                 newBnds->push_back(i);
diff --git a/src/libexpr/get-drvs.cc b/src/libexpr/get-drvs.cc
index fe1d11505..d7630fc3c 100644
--- a/src/libexpr/get-drvs.cc
+++ b/src/libexpr/get-drvs.cc
@@ -107,7 +107,7 @@ DrvInfo::Outputs DrvInfo::queryOutputs(bool onlyOutputsToInstall)
                 string name = state->forceStringNoCtx(*elem, *i->pos);
                 Bindings::iterator out = attrs->find(state->symbols.create(name));
                 if (out == attrs->end()) continue; // FIXME: throw error?
-                state->forceAttrs(*out->value);
+                state->forceAttrs(*out->value, *i->pos);
 
                 /* And evaluate its ‘outPath’ attribute. */
                 Bindings::iterator outPath = out->value->attrs->find(state->sOutPath);
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 074181e13..9ed1c85c6 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -214,7 +214,7 @@ static void import(EvalState & state, const Pos & pos, Value & vPath, Value * vS
         if (!vScope)
             state.evalFile(path, v);
         else {
-            state.forceAttrs(*vScope);
+            state.forceAttrs(*vScope, pos);
 
             Env * env = &state.allocEnv(vScope->attrs->size());
             env->up = &state.baseEnv;
@@ -2485,7 +2485,7 @@ static void prim_zipAttrsWith(EvalState & state, const Pos & pos, Value * * args
     for (unsigned int n = 0; n < listSize; ++n) {
         Value * vElem = listElems[n];
         try {
-            state.forceAttrs(*vElem);
+            state.forceAttrs(*vElem, noPos);
             for (auto & attr : *vElem->attrs)
                 attrsSeen[attr.name].first++;
         } catch (TypeError & e) {
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 97f4d911c..486b43f0f 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -124,12 +124,13 @@ struct CmdFlakeLock : FlakeCommand
 static void enumerateOutputs(EvalState & state, Value & vFlake,
     std::function<void(const std::string & name, Value & vProvide, const Pos & pos)> callback)
 {
-    state.forceAttrs(vFlake);
+    auto pos = vFlake.determinePos(noPos);
+    state.forceAttrs(vFlake, pos);
 
     auto aOutputs = vFlake.attrs->get(state.symbols.create("outputs"));
     assert(aOutputs);
 
-    state.forceAttrs(*aOutputs->value);
+    state.forceAttrs(*aOutputs->value, pos);
 
     auto sHydraJobs = state.symbols.create("hydraJobs");
 
diff --git a/src/nix/prefetch.cc b/src/nix/prefetch.cc
index 768d37595..7044ead10 100644
--- a/src/nix/prefetch.cc
+++ b/src/nix/prefetch.cc
@@ -28,7 +28,7 @@ string resolveMirrorUrl(EvalState & state, string url)
     Value vMirrors;
     // FIXME: use nixpkgs flake
     state.eval(state.parseExprFromString("import <nixpkgs/pkgs/build-support/fetchurl/mirrors.nix>", "."), vMirrors);
-    state.forceAttrs(vMirrors);
+    state.forceAttrs(vMirrors, noPos);
 
     auto mirrorList = vMirrors.attrs->find(state.symbols.create(mirrorName));
     if (mirrorList == vMirrors.attrs->end())
@@ -196,7 +196,7 @@ static int main_nix_prefetch_url(int argc, char * * argv)
             Value vRoot;
             state->evalFile(path, vRoot);
             Value & v(*findAlongAttrPath(*state, attrPath, autoArgs, vRoot).first);
-            state->forceAttrs(v);
+            state->forceAttrs(v, noPos);
 
             /* Extract the URL. */
             auto & attr = v.attrs->need(state->symbols.create("urls"));
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 5c2bf4bfd..8b6de1bf2 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -342,7 +342,7 @@ StringSet NixRepl::completePrefix(string prefix)
             Expr * e = parseString(expr);
             Value v;
             e->eval(*state, *env, v);
-            state->forceAttrs(v);
+            state->forceAttrs(v, noPos);
 
             for (auto & i : *v.attrs) {
                 string name = i.name;
@@ -673,7 +673,7 @@ void NixRepl::reloadFiles()
 
 void NixRepl::addAttrsToScope(Value & attrs)
 {
-    state->forceAttrs(attrs);
+    state->forceAttrs(attrs, attrs.determinePos(noPos));
     if (displ + attrs.attrs->size() >= envSize)
         throw Error("environment full; cannot add more variables");
 

From 3d2ad2b70ba26114bfd5ba55d8b580d4f3b158af Mon Sep 17 00:00:00 2001
From: Kevin Amado <kamadorueda@gmail.com>
Date: Fri, 21 Jan 2022 10:43:49 -0500
Subject: [PATCH 459/567] forceList: make pos mandatory

---
 src/nix/prefetch.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/nix/prefetch.cc b/src/nix/prefetch.cc
index 7044ead10..de657d6f5 100644
--- a/src/nix/prefetch.cc
+++ b/src/nix/prefetch.cc
@@ -33,7 +33,7 @@ string resolveMirrorUrl(EvalState & state, string url)
     auto mirrorList = vMirrors.attrs->find(state.symbols.create(mirrorName));
     if (mirrorList == vMirrors.attrs->end())
         throw Error("unknown mirror name '%s'", mirrorName);
-    state.forceList(*mirrorList->value);
+    state.forceList(*mirrorList->value, noPos);
 
     if (mirrorList->value->listSize() < 1)
         throw Error("mirror URL '%s' did not expand to anything", url);
@@ -200,7 +200,7 @@ static int main_nix_prefetch_url(int argc, char * * argv)
 
             /* Extract the URL. */
             auto & attr = v.attrs->need(state->symbols.create("urls"));
-            state->forceList(*attr.value);
+            state->forceList(*attr.value, noPos);
             if (attr.value->listSize() < 1)
                 throw Error("'urls' list is empty");
             url = state->forceString(*attr.value->listElems()[0]);

From 50efc5499a7d924828bed654be207a846c040fa0 Mon Sep 17 00:00:00 2001
From: Kevin Amado <kamadorueda@gmail.com>
Date: Fri, 21 Jan 2022 11:44:19 -0500
Subject: [PATCH 460/567] determinePos: remove from critical path

---
 src/libexpr/attr-path.cc  | 2 +-
 src/libexpr/eval-cache.cc | 4 ++--
 src/libexpr/eval.cc       | 6 +++---
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/libexpr/attr-path.cc b/src/libexpr/attr-path.cc
index 8ec24269f..42a088050 100644
--- a/src/libexpr/attr-path.cc
+++ b/src/libexpr/attr-path.cc
@@ -58,7 +58,7 @@ std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const string & attr
         Value * vNew = state.allocValue();
         state.autoCallFunction(autoArgs, *v, *vNew);
         v = vNew;
-        state.forceValue(*v, v->determinePos(vIn.determinePos(noPos)));
+        state.forceValue(*v, noPos);
 
         /* It should evaluate to either a set or an expression,
            according to what is specified in the attrPath. */
diff --git a/src/libexpr/eval-cache.cc b/src/libexpr/eval-cache.cc
index 222a34116..d6b9ea29b 100644
--- a/src/libexpr/eval-cache.cc
+++ b/src/libexpr/eval-cache.cc
@@ -336,7 +336,7 @@ Value & AttrCursor::getValue()
     if (!_value) {
         if (parent) {
             auto & vParent = parent->first->getValue();
-            root->state.forceAttrs(vParent, vParent.determinePos(noPos));
+            root->state.forceAttrs(vParent, noPos);
             auto attr = vParent.attrs->get(parent->second);
             if (!attr)
                 throw Error("attribute '%s' is unexpectedly missing", getAttrPathStr());
@@ -381,7 +381,7 @@ Value & AttrCursor::forceValue()
     auto & v = getValue();
 
     try {
-        root->state.forceValue(v, v.determinePos(noPos));
+        root->state.forceValue(v, noPos);
     } catch (EvalError &) {
         debug("setting '%s' to failed", getAttrPathStr());
         if (root->db)
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index e1c089b95..df411f3d5 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -1280,7 +1280,7 @@ void ExprOpHasAttr::eval(EvalState & state, Env & env, Value & v)
     e->eval(state, env, vTmp);
 
     for (auto & i : attrPath) {
-        state.forceValue(*vAttrs, vAttrs->determinePos(noPos));
+        state.forceValue(*vAttrs, noPos);
         Bindings::iterator j;
         Symbol name = getName(i, state, env);
         if (vAttrs->type() != nAttrs ||
@@ -2037,8 +2037,8 @@ Path EvalState::coerceToPath(const Pos & pos, Value & v, PathSet & context)
 
 bool EvalState::eqValues(Value & v1, Value & v2)
 {
-    forceValue(v1, v1.determinePos(noPos));
-    forceValue(v2, v2.determinePos(noPos));
+    forceValue(v1, noPos);
+    forceValue(v2, noPos);
 
     /* !!! Hack to support some old broken code that relies on pointer
        equality tests between sets.  (Specifically, builderDefs calls

From 7477974b93240d0437c80aaf8646d8c838c948b5 Mon Sep 17 00:00:00 2001
From: Ross Light <ross@zombiezen.com>
Date: Fri, 21 Jan 2022 18:45:19 -0800
Subject: [PATCH 461/567] Correct NIX_BUILD_PATH default description

Source: https://github.com/NixOS/nix/blob/067076287bf601f8fa2ffe4feff3057b96fa5be8/src/nix-build/nix-build.cc#L362-L381
---
 doc/manual/src/command-ref/nix-shell.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/doc/manual/src/command-ref/nix-shell.md b/doc/manual/src/command-ref/nix-shell.md
index 873311649..a2b6d8a8e 100644
--- a/doc/manual/src/command-ref/nix-shell.md
+++ b/doc/manual/src/command-ref/nix-shell.md
@@ -101,7 +101,8 @@ The following common options are supported:
 
   - `NIX_BUILD_SHELL`\
     Shell used to start the interactive environment. Defaults to the
-    `bash` found in `PATH`.
+    `bash` found in `<nixpkgs>`, falling back to the `bash` found in
+    `PATH` if not found.
 
 # Examples
 

From 12578ba672c3a341190b462892e49c9661a68035 Mon Sep 17 00:00:00 2001
From: Florian Franzen <Florian.Franzen@gmail.com>
Date: Sat, 22 Jan 2022 20:01:54 +0100
Subject: [PATCH 462/567] tests: skip flake search test if no git is present

---
 tests/flake-searching.sh | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tests/flake-searching.sh b/tests/flake-searching.sh
index 6558aff9a..bc55f2bdc 100644
--- a/tests/flake-searching.sh
+++ b/tests/flake-searching.sh
@@ -1,5 +1,10 @@
 source common.sh
 
+if [[ -z $(type -p git) ]]; then
+    echo "Git not installed; skipping flake search tests"
+    exit 99
+fi
+
 clearStore
 
 cp ./simple.nix ./simple.builder.sh ./config.nix $TEST_HOME

From fd5aa6ee3e33a508f3a8ca35e42d36a2437ebacc Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Sat, 22 Jan 2022 21:17:35 +0100
Subject: [PATCH 463/567] allocate a GC root value for the Value cache pointer

keeping it as a simple data member means it won't be scanned by the GC, so
eventually the GC will collect a cache that is still referenced (resulting in
use-after-free of cache elements).

fixes #5962
---
 src/libexpr/eval.cc | 15 ++++++++++-----
 src/libexpr/eval.hh |  2 +-
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 94ffab175..b884b4001 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -435,6 +435,11 @@ EvalState::EvalState(
     , store(store)
     , buildStore(buildStore ? buildStore : store)
     , regexCache(makeRegexCache())
+#if HAVE_BOEHMGC
+    , valueAllocCache(std::allocate_shared<void *>(traceable_allocator<void *>(), nullptr))
+#else
+    , valueAllocCache(std::make_shared<void *>(nullptr))
+#endif
     , baseEnv(allocEnv(128))
     , staticBaseEnv(false, 0)
 {
@@ -852,15 +857,15 @@ Value * EvalState::allocValue()
        GC_malloc_many returns a linked list of objects of the given size, where the first word
        of each object is also the pointer to the next object in the list. This also means that we
        have to explicitly clear the first word of every object we take. */
-    if (!valueAllocCache) {
-        valueAllocCache = GC_malloc_many(sizeof(Value));
-        if (!valueAllocCache) throw std::bad_alloc();
+    if (!*valueAllocCache) {
+        *valueAllocCache = GC_malloc_many(sizeof(Value));
+        if (!*valueAllocCache) throw std::bad_alloc();
     }
 
     /* GC_NEXT is a convenience macro for accessing the first word of an object.
        Take the first list item, advance the list to the next item, and clear the next pointer. */
-    void * p = valueAllocCache;
-    GC_PTR_STORE_AND_DIRTY(&valueAllocCache, GC_NEXT(p));
+    void * p = *valueAllocCache;
+    GC_PTR_STORE_AND_DIRTY(&*valueAllocCache, GC_NEXT(p));
     GC_NEXT(p) = nullptr;
 
     nrValues++;
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 82ce9d1b3..c59203aa5 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -133,7 +133,7 @@ private:
     std::shared_ptr<RegexCache> regexCache;
 
     /* Allocation cache for GC'd Value objects. */
-    void * valueAllocCache = nullptr;
+    std::shared_ptr<void *> valueAllocCache;
 
 public:
 

From 040cb7304af3fd25dd33a8d8961ca91ec81a11d5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sandro=20J=C3=A4ckel?= <sandro.jaeckel@gmail.com>
Date: Sun, 23 Jan 2022 04:58:00 +0100
Subject: [PATCH 464/567] nix-shell: use clean rm, not any aliases/functions

---
 src/nix-build/nix-build.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index 471a03ac7..5cdf5c717 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -483,7 +483,7 @@ static void main_nix_build(int argc, char * * argv)
            lose the current $PATH directories. */
         auto rcfile = (Path) tmpDir + "/rc";
         std::string rc = fmt(
-                R"(_nix_shell_clean_tmpdir() { rm -rf %1%; }; )"s +
+                R"(_nix_shell_clean_tmpdir() { command rm -rf %1%; }; )"s +
                 (keepTmp ?
                     "trap _nix_shell_clean_tmpdir EXIT; "
                     "exitHooks+=(_nix_shell_clean_tmpdir); "

From ffb28eaa1e15f85d3fbf6bfc3a04a4010f9c80c9 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Mon, 24 Jan 2022 10:07:02 +0100
Subject: [PATCH 465/567] Add a small documentation for `hiliteMatches`

---
 src/libutil/fmt.hh | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/libutil/fmt.hh b/src/libutil/fmt.hh
index 06c4a2049..1f81bfcfb 100644
--- a/src/libutil/fmt.hh
+++ b/src/libutil/fmt.hh
@@ -156,5 +156,12 @@ inline hintformat hintfmt(std::string plain_string)
     return hintfmt("%s", normaltxt(plain_string));
 }
 
+/**
+ * Highlight all the given matches in the given string `s` by wrapping them
+ * between `prefix` and `postfix`.
+ *
+ * If some matches overlap, then their union will be wrapped rather than the
+ * individual matches.
+ */
 std::string hiliteMatches(const std::string &s, std::vector<std::smatch> matches, std::string prefix, std::string postfix);
 }

From 378201727233049a4aec215c3a3835c99456d761 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 24 Jan 2022 12:45:35 +0100
Subject: [PATCH 466/567] Tweak release notes

---
 doc/manual/src/release-notes/rl-next.md | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index 301683246..86fb89467 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -1,19 +1,21 @@
 # Release X.Y (202?-??-??)
 
-* The Nix cli now searches for a `flake.nix` up until the root of the current
-  git repository or a filesystem boundary rather than just in the current
+* The Nix CLI now searches for a `flake.nix` up until the root of the current
+  Git repository or a filesystem boundary rather than just in the current
   directory.
 * The TOML parser used by `builtins.fromTOML` has been replaced by [a
   more compliant one](https://github.com/ToruNiina/toml11).
-* Added `:st`/`:show-trace` commands to nix repl, which are used to
+* Added `:st`/`:show-trace` commands to `nix repl`, which are used to
   set or toggle display of error traces.
-* New builtin function `builtins.zipAttrsWith` with same functionality
-  as `lib.zipAttrsWith` from nixpkgs, but much more efficient.
+* New builtin function `builtins.zipAttrsWith` with the same
+  functionality as `lib.zipAttrsWith` from Nixpkgs, but much more
+  efficient.
 * New command `nix store copy-log` to copy build logs from one store
   to another.
-* The `commit-lockfile-summary` option can be set to a non-empty string
-  to override the commit summary used when commiting an updated lockfile.
-  This may be used in conjunction with the nixConfig attribute in
-  `flake.nix` to better conform to repository conventions.
-* `docker run -ti nixos/nix:master` will place you in the docker container with
-  the latest version of Nix from the `master` branch.
+* The `commit-lockfile-summary` option can be set to a non-empty
+  string to override the commit summary used when commiting an updated
+  lockfile.  This may be used in conjunction with the `nixConfig`
+  attribute in `flake.nix` to better conform to repository
+  conventions.
+* `docker run -ti nixos/nix:master` will place you in the Docker
+  container with the latest version of Nix from the `master` branch.

From 72aeae54e55054e0271e7f628fb18bc85222cc3a Mon Sep 17 00:00:00 2001
From: Sandro <sandro.jaeckel@gmail.com>
Date: Sun, 23 Jan 2022 05:09:40 +0100
Subject: [PATCH 467/567] Remove url literals

---
 default.nix | 2 +-
 shell.nix   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/default.nix b/default.nix
index 71d1a80ad..00ec5b617 100644
--- a/default.nix
+++ b/default.nix
@@ -1,3 +1,3 @@
-(import (fetchTarball https://github.com/edolstra/flake-compat/archive/master.tar.gz) {
+(import (fetchTarball "https://github.com/edolstra/flake-compat/archive/master.tar.gz") {
   src = ./.;
 }).defaultNix
diff --git a/shell.nix b/shell.nix
index 330df0ab6..918f4bbd9 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,3 +1,3 @@
-(import (fetchTarball https://github.com/edolstra/flake-compat/archive/master.tar.gz) {
+(import (fetchTarball "https://github.com/edolstra/flake-compat/archive/master.tar.gz") {
   src = ./.;
 }).shellNix

From 7afbdf254519e93ecf3730656d52e19a8727772c Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 24 Jan 2022 14:47:34 +0100
Subject: [PATCH 468/567] hiliteMatches(): Style fixes, pass more stuff by
 reference

---
 src/libutil/fmt.cc | 18 +++++++++++++-----
 src/libutil/fmt.hh | 19 +++++++++++--------
 src/nix/search.cc  | 12 ++++++------
 3 files changed, 30 insertions(+), 19 deletions(-)

diff --git a/src/libutil/fmt.cc b/src/libutil/fmt.cc
index 914fb62b2..3dd93d73e 100644
--- a/src/libutil/fmt.cc
+++ b/src/libutil/fmt.cc
@@ -1,13 +1,20 @@
+#include "fmt.hh"
+
 #include <regex>
 
 namespace nix {
 
-std::string hiliteMatches(const std::string &s, std::vector<std::smatch> matches, std::string prefix, std::string postfix) {
+std::string hiliteMatches(
+    std::string_view s,
+    std::vector<std::smatch> matches,
+    std::string_view prefix,
+    std::string_view postfix)
+{
     // Avoid copy on zero matches
     if (matches.size() == 0)
-        return s;
+        return (std::string) s;
 
-    std::sort(matches.begin(), matches.end(), [](const auto &a, const auto &b) {
+    std::sort(matches.begin(), matches.end(), [](const auto & a, const auto & b) {
         return a.position() < b.position();
     });
 
@@ -20,10 +27,10 @@ std::string hiliteMatches(const std::string &s, std::vector<std::smatch> matches
         out.append(s.substr(last_end, m.position() - last_end));
         // Merge continous matches
         ssize_t end = start + m.length();
-        while(++it != matches.end() && (*it).position() <= end) {
+        while (++it != matches.end() && (*it).position() <= end) {
             auto n = *it;
             ssize_t nend = start + (n.position() - start + n.length());
-            if(nend > end)
+            if (nend > end)
                 end = nend;
         }
         out.append(prefix);
@@ -31,6 +38,7 @@ std::string hiliteMatches(const std::string &s, std::vector<std::smatch> matches
         out.append(postfix);
         last_end = end;
     }
+
     out.append(s.substr(last_end));
     return out;
 }
diff --git a/src/libutil/fmt.hh b/src/libutil/fmt.hh
index 1f81bfcfb..a7126fb65 100644
--- a/src/libutil/fmt.hh
+++ b/src/libutil/fmt.hh
@@ -156,12 +156,15 @@ inline hintformat hintfmt(std::string plain_string)
     return hintfmt("%s", normaltxt(plain_string));
 }
 
-/**
- * Highlight all the given matches in the given string `s` by wrapping them
- * between `prefix` and `postfix`.
- *
- * If some matches overlap, then their union will be wrapped rather than the
- * individual matches.
- */
-std::string hiliteMatches(const std::string &s, std::vector<std::smatch> matches, std::string prefix, std::string postfix);
+/* Highlight all the given matches in the given string `s` by wrapping
+   them between `prefix` and `postfix`.
+
+   If some matches overlap, then their union will be wrapped rather
+   than the individual matches. */
+std::string hiliteMatches(
+    std::string_view s,
+    std::vector<std::smatch> matches,
+    std::string_view prefix,
+    std::string_view postfix);
+
 }
diff --git a/src/nix/search.cc b/src/nix/search.cc
index 0d10d8c2e..e9307342c 100644
--- a/src/nix/search.cc
+++ b/src/nix/search.cc
@@ -106,19 +106,19 @@ struct CmdSearch : InstallableCommand, MixJSON
 
                     for (auto & regex : regexes) {
                         found = false;
-                        auto add_all = [&found](std::sregex_iterator it, std::vector<std::smatch>& vec){
+                        auto addAll = [&found](std::sregex_iterator it, std::vector<std::smatch> & vec) {
                             const auto end = std::sregex_iterator();
-                            while(it != end) {
+                            while (it != end) {
                                 vec.push_back(*it++);
                                 found = true;
                             }
                         };
 
-                        add_all(std::sregex_iterator(attrPath2.begin(), attrPath2.end(), regex), attrPathMatches);
-                        add_all(std::sregex_iterator(name.name.begin(), name.name.end(), regex), nameMatches);
-                        add_all(std::sregex_iterator(description.begin(), description.end(), regex), descriptionMatches);
+                        addAll(std::sregex_iterator(attrPath2.begin(), attrPath2.end(), regex), attrPathMatches);
+                        addAll(std::sregex_iterator(name.name.begin(), name.name.end(), regex), nameMatches);
+                        addAll(std::sregex_iterator(description.begin(), description.end(), regex), descriptionMatches);
 
-                        if(!found)
+                        if (!found)
                             break;
                     }
 

From 3ff6186af1786bd08217bd0b29afb95eacec0f47 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 24 Jan 2022 14:32:25 +0100
Subject: [PATCH 469/567] Add a test for nix-assertion failures in nix-env

---
 tests/user-envs.nix | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tests/user-envs.nix b/tests/user-envs.nix
index 43eff1a68..6ac896ed8 100644
--- a/tests/user-envs.nix
+++ b/tests/user-envs.nix
@@ -9,7 +9,8 @@ assert foo == "foo";
 let
 
   makeDrv = name: progName: (mkDerivation {
-    inherit name progName system;
+    name = assert progName != "fail"; name;
+    inherit progName system;
     builder = ./user-envs.builder.sh;
   } // {
     meta = {
@@ -26,4 +27,5 @@ in
     (makeDrv "foo-2.0" "foo")
     (makeDrv "bar-0.1.1" "bar")
     (makeDrv "foo-0.1" "foo" // { meta.priority = 10; })
+    (makeDrv "fail-0.1" "fail")
   ]

From c4fc9b6a8d4fa279206814295729985dac7bc509 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 24 Jan 2022 15:08:16 +0100
Subject: [PATCH 470/567] ExprConcatStrings::show(): Print values instead of
 pointers

---
 src/libexpr/nixexpr.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc
index 640c44c01..2d2cd96cd 100644
--- a/src/libexpr/nixexpr.cc
+++ b/src/libexpr/nixexpr.cc
@@ -191,7 +191,7 @@ void ExprConcatStrings::show(std::ostream & str) const
     str << "(";
     for (auto & i : *es) {
         if (first) first = false; else str << " + ";
-        str << i.second;
+        str << *i.second;
     }
     str << ")";
 }

From bed8270c0cbaa3007621ad2f0e722abcefe79702 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 24 Jan 2022 15:18:18 +0100
Subject: [PATCH 471/567] Fix parsing of variable names that are a prefix of
 '__curPos'

Fixes

  $ nix-instantiate --parse -E 'x: with x; _'
  (x: (with x; __curPos))
---
 src/libexpr/parser.y                         | 3 ++-
 tests/lang/eval-okay-regression-20220122.exp | 1 +
 tests/lang/eval-okay-regression-20220122.nix | 1 +
 3 files changed, 4 insertions(+), 1 deletion(-)
 create mode 100644 tests/lang/eval-okay-regression-20220122.exp
 create mode 100644 tests/lang/eval-okay-regression-20220122.nix

diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index a3e713937..55f8abcb7 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -404,7 +404,8 @@ expr_select
 
 expr_simple
   : ID {
-      if (strncmp($1.p, "__curPos", $1.l) == 0)
+      std::string_view s = "__curPos";
+      if (strncmp($1.p, s.data(), s.size()) == 0)
           $$ = new ExprPos(CUR_POS);
       else
           $$ = new ExprVar(CUR_POS, data->symbols.create($1));
diff --git a/tests/lang/eval-okay-regression-20220122.exp b/tests/lang/eval-okay-regression-20220122.exp
new file mode 100644
index 000000000..00750edc0
--- /dev/null
+++ b/tests/lang/eval-okay-regression-20220122.exp
@@ -0,0 +1 @@
+3
diff --git a/tests/lang/eval-okay-regression-20220122.nix b/tests/lang/eval-okay-regression-20220122.nix
new file mode 100644
index 000000000..694e9a13b
--- /dev/null
+++ b/tests/lang/eval-okay-regression-20220122.nix
@@ -0,0 +1 @@
+((_: _) 1) + ((__: __) 2)

From 8cbbaf23e889270867420431f0ab6c0ffa722335 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 24 Jan 2022 23:02:28 +0100
Subject: [PATCH 472/567] Allow builtins.{readFile,path} on invalid paths

Stop-gap measure to fix #5975.
---
 src/libexpr/primops.cc | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 074181e13..9d36f72a8 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1445,9 +1445,13 @@ static void prim_readFile(EvalState & state, const Pos & pos, Value * * args, Va
     string s = readFile(path);
     if (s.find((char) 0) != string::npos)
         throw Error("the contents of the file '%1%' cannot be represented as a Nix string", path);
-    auto refs = state.store->isInStore(path) ?
-        state.store->queryPathInfo(state.store->toStorePath(path).first)->references :
-        StorePathSet{};
+    StorePathSet refs;
+    if (state.store->isInStore(path)) {
+        try {
+            refs = state.store->queryPathInfo(state.store->toStorePath(path).first)->references;
+        } catch (Error &) { // FIXME: should be InvalidPathError
+        }
+    }
     auto context = state.store->printStorePathSet(refs);
     v.mkString(s, context);
 }
@@ -1866,10 +1870,13 @@ static void addPath(
         StorePathSet refs;
 
         if (state.store->isInStore(path)) {
-            auto [storePath, subPath] = state.store->toStorePath(path);
-            // FIXME: we should scanForReferences on the path before adding it
-            refs = state.store->queryPathInfo(storePath)->references;
-            path = state.store->toRealPath(storePath) + subPath;
+            try {
+                auto [storePath, subPath] = state.store->toStorePath(path);
+                // FIXME: we should scanForReferences on the path before adding it
+                refs = state.store->queryPathInfo(storePath)->references;
+                path = state.store->toRealPath(storePath) + subPath;
+            } catch (Error &) { // FIXME: should be InvalidPathError
+            }
         }
 
         path = evalSettings.pureEval && expectedHash

From 9ce251120626575222db54bb8ae2233a101f01f0 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 25 Jan 2022 00:02:48 +0100
Subject: [PATCH 473/567] Add regression / performance tests against a fixed
 revision of Nixpkgs

---
 flake.lock | 18 +++++++++++++++++-
 flake.nix  | 33 ++++++++++++++-------------------
 2 files changed, 31 insertions(+), 20 deletions(-)

diff --git a/flake.lock b/flake.lock
index 861af1c54..61eccb73c 100644
--- a/flake.lock
+++ b/flake.lock
@@ -31,10 +31,26 @@
         "type": "indirect"
       }
     },
+    "nixpkgs-regression": {
+      "locked": {
+        "lastModified": 1643052045,
+        "narHash": "sha256-uGJ0VXIhWKGXxkeNnq4TvV3CIOkUJ3PAoLZ3HMzNVMw=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "215d4d0fd80ca5163643b03a33fde804a29cc1e2",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "rev": "215d4d0fd80ca5163643b03a33fde804a29cc1e2",
+        "type": "indirect"
+      }
+    },
     "root": {
       "inputs": {
         "lowdown-src": "lowdown-src",
-        "nixpkgs": "nixpkgs"
+        "nixpkgs": "nixpkgs",
+        "nixpkgs-regression": "nixpkgs-regression"
       }
     }
   },
diff --git a/flake.nix b/flake.nix
index 9bfa36fdf..a6a3d290d 100644
--- a/flake.nix
+++ b/flake.nix
@@ -2,9 +2,10 @@
   description = "The purely functional package manager";
 
   inputs.nixpkgs.url = "nixpkgs/nixos-21.05-small";
+  inputs.nixpkgs-regression.url = "nixpkgs/215d4d0fd80ca5163643b03a33fde804a29cc1e2";
   inputs.lowdown-src = { url = "github:kristapsdz/lowdown"; flake = false; };
 
-  outputs = { self, nixpkgs, lowdown-src }:
+  outputs = { self, nixpkgs, nixpkgs-regression, lowdown-src }:
 
     let
 
@@ -518,29 +519,23 @@
               inherit (self) overlay;
             });
 
-        /*
-        # Check whether we can still evaluate all of Nixpkgs.
+        # Make sure that nix-env still produces the exact same result
+        # on a particular version of Nixpkgs.
         tests.evalNixpkgs =
-          import (nixpkgs + "/pkgs/top-level/make-tarball.nix") {
-            # FIXME: fix pkgs/top-level/make-tarball.nix in NixOS to not require a revCount.
-            inherit nixpkgs;
-            pkgs = nixpkgsFor.x86_64-linux;
-            officialRelease = false;
-          };
-
-        # Check whether we can still evaluate NixOS.
-        tests.evalNixOS =
           with nixpkgsFor.x86_64-linux;
           runCommand "eval-nixos" { buildInputs = [ nix ]; }
             ''
-              export NIX_STATE_DIR=$TMPDIR
-
-              nix-instantiate ${nixpkgs}/nixos/release-combined.nix -A tested --dry-run \
-                --arg nixpkgs '{ outPath = ${nixpkgs}; revCount = 123; shortRev = "abcdefgh"; }'
-
-              touch $out
+              type -p nix-env
+              # Note: we're filtering out nixos-install-tools because https://github.com/NixOS/nixpkgs/pull/153594#issuecomment-1020530593.
+              time nix-env --store dummy:// -f ${nixpkgs-regression} -qaP --drv-path | sort | grep -v nixos-install-tools > packages
+              [[ $(sha1sum < packages | cut -c1-40) = ff451c521e61e4fe72bdbe2d0ca5d1809affa733 ]]
+              mkdir $out
             '';
-        */
+
+        metrics.nixpkgs = import "${nixpkgs-regression}/pkgs/top-level/metrics.nix" {
+          pkgs = nixpkgsFor.x86_64-linux;
+          nixpkgs = nixpkgs-regression;
+        };
 
         installTests = forAllSystems (system:
           let pkgs = nixpkgsFor.${system}; in

From 9faad4c5eb1d6dee8eba32fb2242396ffb689ee6 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 25 Jan 2022 00:11:00 +0100
Subject: [PATCH 474/567] Move rl-next.md to rl-2.5.md

---
 doc/manual/src/SUMMARY.md.in            |  1 +
 doc/manual/src/release-notes/rl-2.6.md  | 21 +++++++++++++++++++++
 doc/manual/src/release-notes/rl-next.md | 19 -------------------
 3 files changed, 22 insertions(+), 19 deletions(-)
 create mode 100644 doc/manual/src/release-notes/rl-2.6.md

diff --git a/doc/manual/src/SUMMARY.md.in b/doc/manual/src/SUMMARY.md.in
index 2876be52a..4e2afa20e 100644
--- a/doc/manual/src/SUMMARY.md.in
+++ b/doc/manual/src/SUMMARY.md.in
@@ -72,6 +72,7 @@
   - [CLI guideline](contributing/cli-guideline.md)
 - [Release Notes](release-notes/release-notes.md)
   - [Release X.Y (202?-??-??)](release-notes/rl-next.md)
+  - [Release 2.6 (2022-01-24)](release-notes/rl-2.6.md)
   - [Release 2.5 (2021-12-13)](release-notes/rl-2.5.md)
   - [Release 2.4 (2021-11-01)](release-notes/rl-2.4.md)
   - [Release 2.3 (2019-09-04)](release-notes/rl-2.3.md)
diff --git a/doc/manual/src/release-notes/rl-2.6.md b/doc/manual/src/release-notes/rl-2.6.md
new file mode 100644
index 000000000..280faead1
--- /dev/null
+++ b/doc/manual/src/release-notes/rl-2.6.md
@@ -0,0 +1,21 @@
+# Release 2.6 (2022-01-24)
+
+* The Nix CLI now searches for a `flake.nix` up until the root of the current
+  Git repository or a filesystem boundary rather than just in the current
+  directory.
+* The TOML parser used by `builtins.fromTOML` has been replaced by [a
+  more compliant one](https://github.com/ToruNiina/toml11).
+* Added `:st`/`:show-trace` commands to `nix repl`, which are used to
+  set or toggle display of error traces.
+* New builtin function `builtins.zipAttrsWith` with the same
+  functionality as `lib.zipAttrsWith` from Nixpkgs, but much more
+  efficient.
+* New command `nix store copy-log` to copy build logs from one store
+  to another.
+* The `commit-lockfile-summary` option can be set to a non-empty
+  string to override the commit summary used when commiting an updated
+  lockfile.  This may be used in conjunction with the `nixConfig`
+  attribute in `flake.nix` to better conform to repository
+  conventions.
+* `docker run -ti nixos/nix:master` will place you in the Docker
+  container with the latest version of Nix from the `master` branch.
diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index 86fb89467..78ae99f4b 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -1,21 +1,2 @@
 # Release X.Y (202?-??-??)
 
-* The Nix CLI now searches for a `flake.nix` up until the root of the current
-  Git repository or a filesystem boundary rather than just in the current
-  directory.
-* The TOML parser used by `builtins.fromTOML` has been replaced by [a
-  more compliant one](https://github.com/ToruNiina/toml11).
-* Added `:st`/`:show-trace` commands to `nix repl`, which are used to
-  set or toggle display of error traces.
-* New builtin function `builtins.zipAttrsWith` with the same
-  functionality as `lib.zipAttrsWith` from Nixpkgs, but much more
-  efficient.
-* New command `nix store copy-log` to copy build logs from one store
-  to another.
-* The `commit-lockfile-summary` option can be set to a non-empty
-  string to override the commit summary used when commiting an updated
-  lockfile.  This may be used in conjunction with the `nixConfig`
-  attribute in `flake.nix` to better conform to repository
-  conventions.
-* `docker run -ti nixos/nix:master` will place you in the Docker
-  container with the latest version of Nix from the `master` branch.

From 2e4d5f220eeef3ff0885c71f5dbabf184b3616b3 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 25 Jan 2022 00:14:59 +0100
Subject: [PATCH 475/567] Bump version

---
 .version | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.version b/.version
index 914ec9671..9aa34646d 100644
--- a/.version
+++ b/.version
@@ -1 +1 @@
-2.6.0
\ No newline at end of file
+2.7.0
\ No newline at end of file

From 0a70b37b5694c769fb855c1afe7642407d1db64f Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 25 Jan 2022 01:28:44 +0100
Subject: [PATCH 476/567] flake.nix: Fix indentation

---
 flake.nix | 357 +++++++++++++++++++++++++++---------------------------
 1 file changed, 179 insertions(+), 178 deletions(-)

diff --git a/flake.nix b/flake.nix
index a6a3d290d..39f6074a0 100644
--- a/flake.nix
+++ b/flake.nix
@@ -141,8 +141,8 @@
           ];
       };
 
-    installScriptFor = systems:
-      with nixpkgsFor.x86_64-linux;
+      installScriptFor = systems:
+        with nixpkgsFor.x86_64-linux;
         runCommand "installer-script"
           { buildInputs = [ nix ];
           }
@@ -206,203 +206,204 @@
         installCheckPhase = "make installcheck -j$NIX_BUILD_CORES -l$NIX_BUILD_CORES";
       };
 
-      binaryTarball = buildPackages: nix: pkgs: let
-        inherit (pkgs) cacert;
-        installerClosureInfo = buildPackages.closureInfo { rootPaths = [ nix cacert ]; };
-      in
+      binaryTarball = buildPackages: nix: pkgs:
+        let
+          inherit (pkgs) cacert;
+          installerClosureInfo = buildPackages.closureInfo { rootPaths = [ nix cacert ]; };
+        in
 
-      buildPackages.runCommand "nix-binary-tarball-${version}"
-        { #nativeBuildInputs = lib.optional (system != "aarch64-linux") shellcheck;
-          meta.description = "Distribution-independent Nix bootstrap binaries for ${pkgs.system}";
-        }
-        ''
-          cp ${installerClosureInfo}/registration $TMPDIR/reginfo
-          cp ${./scripts/create-darwin-volume.sh} $TMPDIR/create-darwin-volume.sh
-          substitute ${./scripts/install-nix-from-closure.sh} $TMPDIR/install \
-            --subst-var-by nix ${nix} \
-            --subst-var-by cacert ${cacert}
+        buildPackages.runCommand "nix-binary-tarball-${version}"
+          { #nativeBuildInputs = lib.optional (system != "aarch64-linux") shellcheck;
+            meta.description = "Distribution-independent Nix bootstrap binaries for ${pkgs.system}";
+          }
+          ''
+            cp ${installerClosureInfo}/registration $TMPDIR/reginfo
+            cp ${./scripts/create-darwin-volume.sh} $TMPDIR/create-darwin-volume.sh
+            substitute ${./scripts/install-nix-from-closure.sh} $TMPDIR/install \
+              --subst-var-by nix ${nix} \
+              --subst-var-by cacert ${cacert}
 
-          substitute ${./scripts/install-darwin-multi-user.sh} $TMPDIR/install-darwin-multi-user.sh \
-            --subst-var-by nix ${nix} \
-            --subst-var-by cacert ${cacert}
-          substitute ${./scripts/install-systemd-multi-user.sh} $TMPDIR/install-systemd-multi-user.sh \
-            --subst-var-by nix ${nix} \
-            --subst-var-by cacert ${cacert}
-          substitute ${./scripts/install-multi-user.sh} $TMPDIR/install-multi-user \
-            --subst-var-by nix ${nix} \
-            --subst-var-by cacert ${cacert}
+            substitute ${./scripts/install-darwin-multi-user.sh} $TMPDIR/install-darwin-multi-user.sh \
+              --subst-var-by nix ${nix} \
+              --subst-var-by cacert ${cacert}
+            substitute ${./scripts/install-systemd-multi-user.sh} $TMPDIR/install-systemd-multi-user.sh \
+              --subst-var-by nix ${nix} \
+              --subst-var-by cacert ${cacert}
+            substitute ${./scripts/install-multi-user.sh} $TMPDIR/install-multi-user \
+              --subst-var-by nix ${nix} \
+              --subst-var-by cacert ${cacert}
 
-          if type -p shellcheck; then
-            # SC1090: Don't worry about not being able to find
-            #         $nix/etc/profile.d/nix.sh
-            shellcheck --exclude SC1090 $TMPDIR/install
-            shellcheck $TMPDIR/create-darwin-volume.sh
-            shellcheck $TMPDIR/install-darwin-multi-user.sh
-            shellcheck $TMPDIR/install-systemd-multi-user.sh
+            if type -p shellcheck; then
+              # SC1090: Don't worry about not being able to find
+              #         $nix/etc/profile.d/nix.sh
+              shellcheck --exclude SC1090 $TMPDIR/install
+              shellcheck $TMPDIR/create-darwin-volume.sh
+              shellcheck $TMPDIR/install-darwin-multi-user.sh
+              shellcheck $TMPDIR/install-systemd-multi-user.sh
 
-            # SC1091: Don't panic about not being able to source
-            #         /etc/profile
-            # SC2002: Ignore "useless cat" "error", when loading
-            #         .reginfo, as the cat is a much cleaner
-            #         implementation, even though it is "useless"
-            # SC2116: Allow ROOT_HOME=$(echo ~root) for resolving
-            #         root's home directory
-            shellcheck --external-sources \
-              --exclude SC1091,SC2002,SC2116 $TMPDIR/install-multi-user
-          fi
+              # SC1091: Don't panic about not being able to source
+              #         /etc/profile
+              # SC2002: Ignore "useless cat" "error", when loading
+              #         .reginfo, as the cat is a much cleaner
+              #         implementation, even though it is "useless"
+              # SC2116: Allow ROOT_HOME=$(echo ~root) for resolving
+              #         root's home directory
+              shellcheck --external-sources \
+                --exclude SC1091,SC2002,SC2116 $TMPDIR/install-multi-user
+            fi
 
-          chmod +x $TMPDIR/install
-          chmod +x $TMPDIR/create-darwin-volume.sh
-          chmod +x $TMPDIR/install-darwin-multi-user.sh
-          chmod +x $TMPDIR/install-systemd-multi-user.sh
-          chmod +x $TMPDIR/install-multi-user
-          dir=nix-${version}-${pkgs.system}
-          fn=$out/$dir.tar.xz
-          mkdir -p $out/nix-support
-          echo "file binary-dist $fn" >> $out/nix-support/hydra-build-products
-          tar cvfJ $fn \
-            --owner=0 --group=0 --mode=u+rw,uga+r \
-            --absolute-names \
-            --hard-dereference \
-            --transform "s,$TMPDIR/install,$dir/install," \
-            --transform "s,$TMPDIR/create-darwin-volume.sh,$dir/create-darwin-volume.sh," \
-            --transform "s,$TMPDIR/reginfo,$dir/.reginfo," \
-            --transform "s,$NIX_STORE,$dir/store,S" \
-            $TMPDIR/install \
-            $TMPDIR/create-darwin-volume.sh \
-            $TMPDIR/install-darwin-multi-user.sh \
-            $TMPDIR/install-systemd-multi-user.sh \
-            $TMPDIR/install-multi-user \
-            $TMPDIR/reginfo \
-            $(cat ${installerClosureInfo}/store-paths)
-        '';
-
-      overlayFor = getStdenv: final: prev:
-      let currentStdenv = getStdenv final; in
-      {
-        nixStable = prev.nix;
-
-        # Forward from the previous stage as we don’t want it to pick the lowdown override
-        nixUnstable = prev.nixUnstable;
-
-        nix = with final; with commonDeps pkgs; currentStdenv.mkDerivation {
-          name = "nix-${version}";
-          inherit version;
-
-          src = self;
-
-          VERSION_SUFFIX = versionSuffix;
-
-          outputs = [ "out" "dev" "doc" ];
-
-          nativeBuildInputs = nativeBuildDeps;
-          buildInputs = buildDeps ++ awsDeps;
-
-          propagatedBuildInputs = propagatedDeps;
-
-          disallowedReferences = [ boost ];
-
-          preConfigure =
-            ''
-              # Copy libboost_context so we don't get all of Boost in our closure.
-              # https://github.com/NixOS/nixpkgs/issues/45462
-              mkdir -p $out/lib
-              cp -pd ${boost}/lib/{libboost_context*,libboost_thread*,libboost_system*} $out/lib
-              rm -f $out/lib/*.a
-              ${lib.optionalString currentStdenv.isLinux ''
-                chmod u+w $out/lib/*.so.*
-                patchelf --set-rpath $out/lib:${currentStdenv.cc.cc.lib}/lib $out/lib/libboost_thread.so.*
-              ''}
-              ${lib.optionalString currentStdenv.isDarwin ''
-                for LIB in $out/lib/*.dylib; do
-                  chmod u+w $LIB
-                  install_name_tool -id $LIB $LIB
-                done
-                install_name_tool -change ${boost}/lib/libboost_system.dylib $out/lib/libboost_system.dylib $out/lib/libboost_thread.dylib
-              ''}
-            '';
-
-          configureFlags = configureFlags ++
-            [ "--sysconfdir=/etc" ];
-
-          enableParallelBuilding = true;
-
-          makeFlags = "profiledir=$(out)/etc/profile.d PRECOMPILE_HEADERS=1";
-
-          doCheck = true;
-
-          installFlags = "sysconfdir=$(out)/etc";
-
-          postInstall = ''
-            mkdir -p $doc/nix-support
-            echo "doc manual $doc/share/doc/nix/manual" >> $doc/nix-support/hydra-build-products
-            ${lib.optionalString currentStdenv.isDarwin ''
-            install_name_tool \
-              -change ${boost}/lib/libboost_context.dylib \
-              $out/lib/libboost_context.dylib \
-              $out/lib/libnixutil.dylib
-            ''}
+            chmod +x $TMPDIR/install
+            chmod +x $TMPDIR/create-darwin-volume.sh
+            chmod +x $TMPDIR/install-darwin-multi-user.sh
+            chmod +x $TMPDIR/install-systemd-multi-user.sh
+            chmod +x $TMPDIR/install-multi-user
+            dir=nix-${version}-${pkgs.system}
+            fn=$out/$dir.tar.xz
+            mkdir -p $out/nix-support
+            echo "file binary-dist $fn" >> $out/nix-support/hydra-build-products
+            tar cvfJ $fn \
+              --owner=0 --group=0 --mode=u+rw,uga+r \
+              --absolute-names \
+              --hard-dereference \
+              --transform "s,$TMPDIR/install,$dir/install," \
+              --transform "s,$TMPDIR/create-darwin-volume.sh,$dir/create-darwin-volume.sh," \
+              --transform "s,$TMPDIR/reginfo,$dir/.reginfo," \
+              --transform "s,$NIX_STORE,$dir/store,S" \
+              $TMPDIR/install \
+              $TMPDIR/create-darwin-volume.sh \
+              $TMPDIR/install-darwin-multi-user.sh \
+              $TMPDIR/install-systemd-multi-user.sh \
+              $TMPDIR/install-multi-user \
+              $TMPDIR/reginfo \
+              $(cat ${installerClosureInfo}/store-paths)
           '';
 
-          doInstallCheck = true;
-          installCheckFlags = "sysconfdir=$(out)/etc";
+      overlayFor = getStdenv: final: prev:
+        let currentStdenv = getStdenv final; in
+        {
+          nixStable = prev.nix;
 
-          separateDebugInfo = true;
+          # Forward from the previous stage as we don’t want it to pick the lowdown override
+          nixUnstable = prev.nixUnstable;
 
-          strictDeps = true;
-
-          passthru.perl-bindings = with final; currentStdenv.mkDerivation {
-            name = "nix-perl-${version}";
+          nix = with final; with commonDeps pkgs; currentStdenv.mkDerivation {
+            name = "nix-${version}";
+            inherit version;
 
             src = self;
 
-            nativeBuildInputs =
-              [ buildPackages.autoconf-archive
-                buildPackages.autoreconfHook
-                buildPackages.pkg-config
-              ];
+            VERSION_SUFFIX = versionSuffix;
 
-            buildInputs =
-              [ nix
-                curl
-                bzip2
-                xz
-                pkgs.perl
-                boost
-              ]
-              ++ lib.optional (currentStdenv.isLinux || currentStdenv.isDarwin) libsodium
-              ++ lib.optional currentStdenv.isDarwin darwin.apple_sdk.frameworks.Security;
+            outputs = [ "out" "dev" "doc" ];
 
-            configureFlags = ''
-              --with-dbi=${perlPackages.DBI}/${pkgs.perl.libPrefix}
-              --with-dbd-sqlite=${perlPackages.DBDSQLite}/${pkgs.perl.libPrefix}
-            '';
+            nativeBuildInputs = nativeBuildDeps;
+            buildInputs = buildDeps ++ awsDeps;
+
+            propagatedBuildInputs = propagatedDeps;
+
+            disallowedReferences = [ boost ];
+
+            preConfigure =
+              ''
+                # Copy libboost_context so we don't get all of Boost in our closure.
+                # https://github.com/NixOS/nixpkgs/issues/45462
+                mkdir -p $out/lib
+                cp -pd ${boost}/lib/{libboost_context*,libboost_thread*,libboost_system*} $out/lib
+                rm -f $out/lib/*.a
+                ${lib.optionalString currentStdenv.isLinux ''
+                  chmod u+w $out/lib/*.so.*
+                  patchelf --set-rpath $out/lib:${currentStdenv.cc.cc.lib}/lib $out/lib/libboost_thread.so.*
+                ''}
+                ${lib.optionalString currentStdenv.isDarwin ''
+                  for LIB in $out/lib/*.dylib; do
+                    chmod u+w $LIB
+                    install_name_tool -id $LIB $LIB
+                  done
+                  install_name_tool -change ${boost}/lib/libboost_system.dylib $out/lib/libboost_system.dylib $out/lib/libboost_thread.dylib
+                ''}
+              '';
+
+            configureFlags = configureFlags ++
+              [ "--sysconfdir=/etc" ];
 
             enableParallelBuilding = true;
 
-            postUnpack = "sourceRoot=$sourceRoot/perl";
+            makeFlags = "profiledir=$(out)/etc/profile.d PRECOMPILE_HEADERS=1";
+
+            doCheck = true;
+
+            installFlags = "sysconfdir=$(out)/etc";
+
+            postInstall = ''
+              mkdir -p $doc/nix-support
+              echo "doc manual $doc/share/doc/nix/manual" >> $doc/nix-support/hydra-build-products
+              ${lib.optionalString currentStdenv.isDarwin ''
+              install_name_tool \
+                -change ${boost}/lib/libboost_context.dylib \
+                $out/lib/libboost_context.dylib \
+                $out/lib/libnixutil.dylib
+              ''}
+            '';
+
+            doInstallCheck = true;
+            installCheckFlags = "sysconfdir=$(out)/etc";
+
+            separateDebugInfo = true;
+
+            strictDeps = true;
+
+            passthru.perl-bindings = with final; currentStdenv.mkDerivation {
+              name = "nix-perl-${version}";
+
+              src = self;
+
+              nativeBuildInputs =
+                [ buildPackages.autoconf-archive
+                  buildPackages.autoreconfHook
+                  buildPackages.pkg-config
+                ];
+
+              buildInputs =
+                [ nix
+                  curl
+                  bzip2
+                  xz
+                  pkgs.perl
+                  boost
+                ]
+                ++ lib.optional (currentStdenv.isLinux || currentStdenv.isDarwin) libsodium
+                ++ lib.optional currentStdenv.isDarwin darwin.apple_sdk.frameworks.Security;
+
+              configureFlags = ''
+                --with-dbi=${perlPackages.DBI}/${pkgs.perl.libPrefix}
+                --with-dbd-sqlite=${perlPackages.DBDSQLite}/${pkgs.perl.libPrefix}
+              '';
+
+              enableParallelBuilding = true;
+
+              postUnpack = "sourceRoot=$sourceRoot/perl";
+            };
+
           };
 
+          lowdown-nix = with final; currentStdenv.mkDerivation rec {
+            name = "lowdown-0.9.0";
+
+            src = lowdown-src;
+
+            outputs = [ "out" "bin" "dev" ];
+
+            nativeBuildInputs = [ buildPackages.which ];
+
+            configurePhase = ''
+                ${if (currentStdenv.isDarwin && currentStdenv.isAarch64) then "echo \"HAVE_SANDBOX_INIT=false\" > configure.local" else ""}
+                ./configure \
+                  PREFIX=${placeholder "dev"} \
+                  BINDIR=${placeholder "bin"}/bin
+            '';
+          };
         };
 
-        lowdown-nix = with final; currentStdenv.mkDerivation rec {
-          name = "lowdown-0.9.0";
-
-          src = lowdown-src;
-
-          outputs = [ "out" "bin" "dev" ];
-
-          nativeBuildInputs = [ buildPackages.which ];
-
-          configurePhase = ''
-              ${if (currentStdenv.isDarwin && currentStdenv.isAarch64) then "echo \"HAVE_SANDBOX_INIT=false\" > configure.local" else ""}
-              ./configure \
-                PREFIX=${placeholder "dev"} \
-                BINDIR=${placeholder "bin"}/bin
-          '';
-        };
-      };
-
     in {
 
       # A Nixpkgs overlay that overrides the 'nix' and

From 3be810f5dbfaac8ced55e22fe8939c094e4a57fc Mon Sep 17 00:00:00 2001
From: Tom Bereknyei <tomberek@gmail.com>
Date: Sun, 31 Oct 2021 13:19:53 -0400
Subject: [PATCH 477/567] bundler: pass drv attrset instead of path

---
 src/nix/bundle.cc | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/src/nix/bundle.cc b/src/nix/bundle.cc
index adb5b3e73..9fc2656bb 100644
--- a/src/nix/bundle.cc
+++ b/src/nix/bundle.cc
@@ -71,6 +71,14 @@ struct CmdBundle : InstallableCommand
 
         auto app = installable->toApp(*evalState).resolve(getEvalStore(), store);
 
+        auto [progFlakeRef, progName] = parseFlakeRefWithFragment(installable->what(), absPath("."));
+        const flake::LockFlags lockFlagsProg{ .writeLockFile = false };
+        auto programInstallable = InstallableFlake(this,
+            evalState, std::move(progFlakeRef),
+            Strings{progName == "" ? "defaultPackage" : progName},
+            Strings({"packages."+settings.thisSystem.get()+".","legacyPackages."+settings.thisSystem.get()+"."}), lockFlagsProg);
+        auto val = programInstallable.toValue(*evalState).first;
+
         auto [bundlerFlakeRef, bundlerName] = parseFlakeRefWithFragment(bundler, absPath("."));
         const flake::LockFlags lockFlags{ .writeLockFile = false };
         auto bundler = InstallableFlake(this,
@@ -80,10 +88,12 @@ struct CmdBundle : InstallableCommand
 
         auto attrs = evalState->buildBindings(2);
 
-        PathSet context;
-        for (auto & i : app.context)
-            context.insert("=" + store->printStorePath(i.path));
-        attrs.alloc("program").mkString(app.program, context);
+        Value & prog = *evalState->allocAttr(*arg, evalState->symbols.create("program"));
+        evalState->mkAttrs(prog,val->attrs->size());
+        for (auto &j : *(val->attrs)){
+            prog.attrs->push_back(j);
+        }
+        prog.attrs->sort();
 
         attrs.alloc("system").mkString(settings.thisSystem.get());
 

From c94db0535c4ddd32957fd80d0713797ec73cc70b Mon Sep 17 00:00:00 2001
From: Tom Bereknyei <tomberek@gmail.com>
Date: Fri, 21 Jan 2022 11:43:11 -0500
Subject: [PATCH 478/567] Refactor bundler API

Bundlers now expect to be located at bundlers.<system>.<name> and are a
function from derivations to derivations.
---
 src/nix/bundle.cc | 32 ++++++++++----------------------
 src/nix/bundle.md | 41 ++++++++++++++++++++++++++++++++++++-----
 src/nix/flake.cc  | 28 +++++++++++++++++++---------
 3 files changed, 65 insertions(+), 36 deletions(-)

diff --git a/src/nix/bundle.cc b/src/nix/bundle.cc
index 9fc2656bb..445db5d5f 100644
--- a/src/nix/bundle.cc
+++ b/src/nix/bundle.cc
@@ -69,39 +69,24 @@ struct CmdBundle : InstallableCommand
     {
         auto evalState = getEvalState();
 
-        auto app = installable->toApp(*evalState).resolve(getEvalStore(), store);
-
         auto [progFlakeRef, progName] = parseFlakeRefWithFragment(installable->what(), absPath("."));
         const flake::LockFlags lockFlagsProg{ .writeLockFile = false };
         auto programInstallable = InstallableFlake(this,
             evalState, std::move(progFlakeRef),
-            Strings{progName == "" ? "defaultPackage" : progName},
-            Strings({"packages."+settings.thisSystem.get()+".","legacyPackages."+settings.thisSystem.get()+"."}), lockFlagsProg);
+            Strings{progName == "" ? "defaultApp" : progName},
+            Strings(this->getDefaultFlakeAttrPathPrefixes()),
+            lockFlagsProg);
         auto val = programInstallable.toValue(*evalState).first;
 
         auto [bundlerFlakeRef, bundlerName] = parseFlakeRefWithFragment(bundler, absPath("."));
         const flake::LockFlags lockFlags{ .writeLockFile = false };
         auto bundler = InstallableFlake(this,
             evalState, std::move(bundlerFlakeRef),
-            Strings{bundlerName == "" ? "defaultBundler" : bundlerName},
+            Strings{bundlerName == "" ? "defaultBundler." + settings.thisSystem.get() : settings.thisSystem.get() + "." + bundlerName},
             Strings({"bundlers."}), lockFlags);
 
-        auto attrs = evalState->buildBindings(2);
-
-        Value & prog = *evalState->allocAttr(*arg, evalState->symbols.create("program"));
-        evalState->mkAttrs(prog,val->attrs->size());
-        for (auto &j : *(val->attrs)){
-            prog.attrs->push_back(j);
-        }
-        prog.attrs->sort();
-
-        attrs.alloc("system").mkString(settings.thisSystem.get());
-
         auto vRes = evalState->allocValue();
-        evalState->callFunction(
-            *bundler.toValue(*evalState).first,
-            evalState->allocValue()->mkAttrs(attrs),
-            *vRes, noPos);
+        evalState->callFunction(*bundler.toValue(*evalState).first, *val, *vRes, noPos);
 
         if (!evalState->isDerivation(*vRes))
             throw Error("the bundler '%s' does not produce a derivation", bundler.what());
@@ -123,9 +108,12 @@ struct CmdBundle : InstallableCommand
 
         auto outPathS = store->printStorePath(outPath);
 
-        if (!outLink)
-            outLink = baseNameOf(app.program);
+        if (!outLink) {
+            auto &attr = vRes->attrs->need(evalState->sName);
+            outLink = evalState->forceStringNoCtx(*attr.value,*attr.pos);
+        }
 
+        // TODO: will crash if not a localFSStore?
         store.dynamic_pointer_cast<LocalFSStore>()->addPermRoot(outPath, absPath(*outLink));
     }
 };
diff --git a/src/nix/bundle.md b/src/nix/bundle.md
index 5e2298376..317b7000b 100644
--- a/src/nix/bundle.md
+++ b/src/nix/bundle.md
@@ -18,12 +18,20 @@ R""(
   nix (Nix) 2.4pre20201215_e3ddffb
   ```
 
+* Bundle a Hello using a specific bundler:
+
+  ```console
+  # nix bundle --bundler github:NixOS/bundlers#toDockerImage nixpkgs#hello
+  # docker load < hello-2.10.tar.gz
+  # docker run hello-2.10:latest hello
+  Hello, world!
+  ```
+
 # Description
 
-`nix bundle` packs the closure of the [Nix app](./nix3-run.md)
-*installable* into a single self-extracting executable. See the
-[`nix-bundle` homepage](https://github.com/matthewbauer/nix-bundle)
-for more details.
+`nix bundle`, by default, packs the closure of the [Nix app](./nix3-run.md)
+*installable* into a single self-extracting executable. See the [`nix-bundle`
+homepage](https://github.com/matthewbauer/nix-bundle) for more details.
 
 > **Note**
 >
@@ -31,6 +39,29 @@ for more details.
 
 # Bundler definitions
 
-TODO
+If no flake output attribute is given, `nix bundle` tries the following
+flake output attributes:
+
+* `defaultBundler.<system>`
+
+If an attribute *name* is given, `nix run` tries the following flake
+output attributes:
+
+* `bundler.<system>.<name>`
+
+# Bundlers
+
+An bundlers is specified by a flake output attribute named
+`bundlers.<system>.<name>` or `defaultBundler.<system>`. It looks like this:
+
+```nix
+bundlers.x86_64-linux.identity = drv: drv;
+
+bundlers.x86_64-linux.blender_2_79 = drv: self.packages.x86_64-linux.blender_2_79;
+
+defaultBundler.x86_64-linux = drv: drv;
+```
+
+A bundler must be a function that accepts a derivation and returns a derivation.
 
 )""
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 97f4d911c..19bf9ab51 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -475,10 +475,7 @@ struct CmdFlakeCheck : FlakeCommand
                 state->forceValue(v, pos);
                 if (!v.isLambda())
                     throw Error("bundler must be a function");
-                if (!v.lambda.fun->formals ||
-                    !v.lambda.fun->formals->argNames.count(state->symbols.create("program")) ||
-                    !v.lambda.fun->formals->argNames.count(state->symbols.create("system")))
-                    throw Error("bundler must take formal arguments 'program' and 'system'");
+                // TODO: check types of inputs/outputs?
             } catch (Error & e) {
                 e.addTrace(pos, hintfmt("while checking the template '%s'", attrPath));
                 reportError(e);
@@ -609,14 +606,27 @@ struct CmdFlakeCheck : FlakeCommand
                                     *attr.value, *attr.pos);
                         }
 
-                        else if (name == "defaultBundler")
-                            checkBundler(name, vOutput, pos);
+                        else if (name == "defaultBundler") {
+                            state->forceAttrs(vOutput, pos);
+                            for (auto & attr : *vOutput.attrs) {
+                                checkSystemName(attr.name, *attr.pos);
+                                checkBundler(
+                                    fmt("%s.%s", name, attr.name),
+                                    *attr.value, *attr.pos);
+                            }
+                        }
 
                         else if (name == "bundlers") {
                             state->forceAttrs(vOutput, pos);
-                            for (auto & attr : *vOutput.attrs)
-                                checkBundler(fmt("%s.%s", name, attr.name),
-                                    *attr.value, *attr.pos);
+                            for (auto & attr : *vOutput.attrs) {
+                                checkSystemName(attr.name, *attr.pos);
+                                state->forceAttrs(*attr.value, *attr.pos);
+                                for (auto & attr2 : *attr.value->attrs) {
+                                    checkBundler(
+                                        fmt("%s.%s.%s", name, attr.name, attr2.name),
+                                        *attr2.value, *attr2.pos);
+                                }
+                            }
                         }
 
                         else

From 8ba7a2d3a8283babea324d3f822c9e5b75a174b4 Mon Sep 17 00:00:00 2001
From: Farid Zakaria <fmzakari@google.com>
Date: Mon, 24 Jan 2022 19:12:13 -0800
Subject: [PATCH 479/567] Do not suppress errors in nix-env from feedback by
 Eelco

---
 src/nix-env/nix-env.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index f95754599..d2636abf7 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -948,7 +948,8 @@ static void queryJSON(Globals & globals, vector<DrvInfo> & elems, bool printOutP
         } catch (AssertionError & e) {
             printMsg(lvlTalkative, "skipping derivation named '%1%' which gives an assertion failure", i.queryName());
         } catch (Error & e) {
-            printMsg(lvlError, "skipping derivation named '%1%' which gives an error '%2%'", i.queryName(), e.msg());
+            e.addTrace(std::nullopt, "while querying the derivation named '%1%'", i.queryName());
+            throw;
         }
     }
 }

From 93299efc7c587194de4c88ddcba5d33df3b51bf6 Mon Sep 17 00:00:00 2001
From: Tom Bereknyei <tomberek@gmail.com>
Date: Tue, 25 Jan 2022 03:39:18 -0500
Subject: [PATCH 480/567] bundler: add tests and change defaults to use a
 derivation

---
 src/nix/bundle.cc      | 10 +++++-----
 tests/flake-bundler.sh | 23 +++++++++++++++++++++++
 tests/local.mk         |  1 +
 3 files changed, 29 insertions(+), 5 deletions(-)
 create mode 100644 tests/flake-bundler.sh

diff --git a/src/nix/bundle.cc b/src/nix/bundle.cc
index 445db5d5f..3d953ebc0 100644
--- a/src/nix/bundle.cc
+++ b/src/nix/bundle.cc
@@ -51,7 +51,7 @@ struct CmdBundle : InstallableCommand
 
     Strings getDefaultFlakeAttrPaths() override
     {
-        Strings res{"defaultApp." + settings.thisSystem.get()};
+        Strings res{"defaultPackage." + settings.thisSystem.get()};
         for (auto & s : SourceExprCommand::getDefaultFlakeAttrPaths())
             res.push_back(s);
         return res;
@@ -59,7 +59,7 @@ struct CmdBundle : InstallableCommand
 
     Strings getDefaultFlakeAttrPathPrefixes() override
     {
-        Strings res{"apps." + settings.thisSystem.get() + "."};
+        Strings res{"packages." + settings.thisSystem.get() + "."};
         for (auto & s : SourceExprCommand::getDefaultFlakeAttrPathPrefixes())
             res.push_back(s);
         return res;
@@ -73,7 +73,7 @@ struct CmdBundle : InstallableCommand
         const flake::LockFlags lockFlagsProg{ .writeLockFile = false };
         auto programInstallable = InstallableFlake(this,
             evalState, std::move(progFlakeRef),
-            Strings{progName == "" ? "defaultApp" : progName},
+            Strings{progName == "" ? "defaultPackage" : progName},
             Strings(this->getDefaultFlakeAttrPathPrefixes()),
             lockFlagsProg);
         auto val = programInstallable.toValue(*evalState).first;
@@ -82,8 +82,8 @@ struct CmdBundle : InstallableCommand
         const flake::LockFlags lockFlags{ .writeLockFile = false };
         auto bundler = InstallableFlake(this,
             evalState, std::move(bundlerFlakeRef),
-            Strings{bundlerName == "" ? "defaultBundler." + settings.thisSystem.get() : settings.thisSystem.get() + "." + bundlerName},
-            Strings({"bundlers."}), lockFlags);
+            Strings{bundlerName == "" ? "defaultBundler." + settings.thisSystem.get() : settings.thisSystem.get() + "." + bundlerName, bundlerName},
+            Strings({"","bundlers."}), lockFlags);
 
         auto vRes = evalState->allocValue();
         evalState->callFunction(*bundler.toValue(*evalState).first, *val, *vRes, noPos);
diff --git a/tests/flake-bundler.sh b/tests/flake-bundler.sh
new file mode 100644
index 000000000..2e52f999d
--- /dev/null
+++ b/tests/flake-bundler.sh
@@ -0,0 +1,23 @@
+source common.sh
+
+clearStore
+rm -rf $TEST_HOME/.cache $TEST_HOME/.config $TEST_HOME/.local
+
+cp ./simple.nix ./simple.builder.sh ./config.nix $TEST_HOME
+
+cd $TEST_HOME
+
+cat <<EOF > flake.nix
+{
+    outputs = {self}: {
+       defaultBundler.$system = drv: drv;
+       defaultPackage.$system = import ./simple.nix;
+    };
+}
+EOF
+nix build .#
+nix bundle --bundler .# .#
+nix bundle --bundler .#defaultBundler.$system .#defaultPackage.$system
+
+clearStore
+
diff --git a/tests/local.mk b/tests/local.mk
index 93cf20d43..9c3e6bbd3 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -48,6 +48,7 @@ nix_tests = \
   flakes.sh \
   flake-local-settings.sh \
   flake-searching.sh \
+  flake-bundler.sh \
   build.sh \
   repl.sh ca/repl.sh \
   ca/build.sh \

From dc85e20684c6763330d35f7855e8ac741dfdfa23 Mon Sep 17 00:00:00 2001
From: Tom Bereknyei <tomberek@gmail.com>
Date: Tue, 25 Jan 2022 03:48:44 -0500
Subject: [PATCH 481/567] bundler: notes and doc update to include bundlers
 repo

---
 doc/manual/src/release-notes/rl-next.md | 6 ++++++
 src/nix/bundle.md                       | 6 +++---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index 78ae99f4b..e755173c0 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -1,2 +1,8 @@
 # Release X.Y (202?-??-??)
 
+* `nix bundle` breaking API change now supports bundlers of the form
+  `bundler.<system>.<name>= derivation: another-derivation;`. This supports
+  additional functionality to inspect evaluation information during bundling. A
+  new [repository](https://github.com/NixOS/bundlers) has various bundlers
+  implemented.
+
diff --git a/src/nix/bundle.md b/src/nix/bundle.md
index 317b7000b..f151eeabc 100644
--- a/src/nix/bundle.md
+++ b/src/nix/bundle.md
@@ -29,9 +29,9 @@ R""(
 
 # Description
 
-`nix bundle`, by default, packs the closure of the [Nix app](./nix3-run.md)
-*installable* into a single self-extracting executable. See the [`nix-bundle`
-homepage](https://github.com/matthewbauer/nix-bundle) for more details.
+`nix bundle`, by default, packs the closure of the *installable* into a single
+self-extracting executable. See the [`bundlers`
+homepage](https://github.com/NixOS/bundlers) for more details.
 
 > **Note**
 >

From f113ea6c739a9f34fc0c79b1857279b9c0803bf1 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Tue, 25 Jan 2022 10:49:27 +0100
Subject: [PATCH 482/567] Fix parsing of variable names that are a suffix of
 '__curPos'

Follow-up from #5969
Fix #5982
---
 src/libexpr/parser.y                         | 2 +-
 tests/lang/eval-okay-regression-20220125.exp | 1 +
 tests/lang/eval-okay-regression-20220125.nix | 2 ++
 3 files changed, 4 insertions(+), 1 deletion(-)
 create mode 100644 tests/lang/eval-okay-regression-20220125.exp
 create mode 100644 tests/lang/eval-okay-regression-20220125.nix

diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 55f8abcb7..7a8e93c12 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -405,7 +405,7 @@ expr_select
 expr_simple
   : ID {
       std::string_view s = "__curPos";
-      if (strncmp($1.p, s.data(), s.size()) == 0)
+      if ($1.l == s.size() && strncmp($1.p, s.data(), s.size()) == 0)
           $$ = new ExprPos(CUR_POS);
       else
           $$ = new ExprVar(CUR_POS, data->symbols.create($1));
diff --git a/tests/lang/eval-okay-regression-20220125.exp b/tests/lang/eval-okay-regression-20220125.exp
new file mode 100644
index 000000000..00750edc0
--- /dev/null
+++ b/tests/lang/eval-okay-regression-20220125.exp
@@ -0,0 +1 @@
+3
diff --git a/tests/lang/eval-okay-regression-20220125.nix b/tests/lang/eval-okay-regression-20220125.nix
new file mode 100644
index 000000000..485502373
--- /dev/null
+++ b/tests/lang/eval-okay-regression-20220125.nix
@@ -0,0 +1,2 @@
+((__curPosFoo: __curPosFoo) 1) + ((__curPosBar: __curPosBar) 2)
+

From fcf3528ad1ad3fc0eeac9a1241b7edfebf67eb3d Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 25 Jan 2022 11:58:00 +0100
Subject: [PATCH 483/567] Remove unused Rust stuff

In particular we were still compiling rust-ffi.cc even though we're
not using it.
---
 nix-rust/Cargo.lock                      | 399 -----------------------
 nix-rust/Cargo.toml                      |  23 --
 nix-rust/local.mk                        |  48 ---
 nix-rust/src/c.rs                        |  77 -----
 nix-rust/src/error.rs                    | 118 -------
 nix-rust/src/lib.rs                      |  10 -
 nix-rust/src/nar.rs                      | 126 -------
 nix-rust/src/store/binary_cache_store.rs |  48 ---
 nix-rust/src/store/mod.rs                |  17 -
 nix-rust/src/store/path.rs               | 224 -------------
 nix-rust/src/store/path_info.rs          |  70 ----
 nix-rust/src/store/store.rs              |  53 ---
 nix-rust/src/util/base32.rs              | 160 ---------
 nix-rust/src/util/mod.rs                 |   1 -
 src/libutil/rust-ffi.cc                  |  24 --
 src/libutil/rust-ffi.hh                  | 189 -----------
 16 files changed, 1587 deletions(-)
 delete mode 100644 nix-rust/Cargo.lock
 delete mode 100644 nix-rust/Cargo.toml
 delete mode 100644 nix-rust/local.mk
 delete mode 100644 nix-rust/src/c.rs
 delete mode 100644 nix-rust/src/error.rs
 delete mode 100644 nix-rust/src/lib.rs
 delete mode 100644 nix-rust/src/nar.rs
 delete mode 100644 nix-rust/src/store/binary_cache_store.rs
 delete mode 100644 nix-rust/src/store/mod.rs
 delete mode 100644 nix-rust/src/store/path.rs
 delete mode 100644 nix-rust/src/store/path_info.rs
 delete mode 100644 nix-rust/src/store/store.rs
 delete mode 100644 nix-rust/src/util/base32.rs
 delete mode 100644 nix-rust/src/util/mod.rs
 delete mode 100644 src/libutil/rust-ffi.cc
 delete mode 100644 src/libutil/rust-ffi.hh

diff --git a/nix-rust/Cargo.lock b/nix-rust/Cargo.lock
deleted file mode 100644
index 957c01e5a..000000000
--- a/nix-rust/Cargo.lock
+++ /dev/null
@@ -1,399 +0,0 @@
-# This file is automatically @generated by Cargo.
-# It is not intended for manual editing.
-[[package]]
-name = "assert_matches"
-version = "1.3.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
-[[package]]
-name = "autocfg"
-version = "0.1.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
-[[package]]
-name = "bit-set"
-version = "0.5.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "bit-vec 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
-name = "bit-vec"
-version = "0.5.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
-[[package]]
-name = "bitflags"
-version = "1.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
-[[package]]
-name = "byteorder"
-version = "1.3.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
-[[package]]
-name = "c2-chacha"
-version = "0.2.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "ppv-lite86 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
-name = "cfg-if"
-version = "0.1.10"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
-[[package]]
-name = "cloudabi"
-version = "0.0.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
-name = "fnv"
-version = "1.0.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
-[[package]]
-name = "fuchsia-cprng"
-version = "0.1.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
-[[package]]
-name = "getrandom"
-version = "0.1.13"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.66 (registry+https://github.com/rust-lang/crates.io-index)",
- "wasi 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
-name = "hex"
-version = "0.3.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
-[[package]]
-name = "lazy_static"
-version = "1.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
-[[package]]
-name = "libc"
-version = "0.2.66"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
-[[package]]
-name = "nix-rust"
-version = "0.1.0"
-dependencies = [
- "assert_matches 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "hex 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.66 (registry+https://github.com/rust-lang/crates.io-index)",
- "proptest 0.9.4 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
-name = "num-traits"
-version = "0.2.10"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "autocfg 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
-name = "ppv-lite86"
-version = "0.2.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
-[[package]]
-name = "proptest"
-version = "0.9.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "bit-set 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "byteorder 1.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
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diff --git a/nix-rust/Cargo.toml b/nix-rust/Cargo.toml
deleted file mode 100644
index 1372e5a73..000000000
--- a/nix-rust/Cargo.toml
+++ /dev/null
@@ -1,23 +0,0 @@
-[package]
-name = "nix-rust"
-version = "0.1.0"
-authors = ["Eelco Dolstra <edolstra@gmail.com>"]
-edition = "2018"
-
-[lib]
-name = "nixrust"
-crate-type = ["cdylib"]
-
-[dependencies]
-libc = "0.2"
-#futures-preview = { version = "=0.3.0-alpha.19" }
-#hyper = "0.13.0-alpha.4"
-#http = "0.1"
-#tokio = { version = "0.2.0-alpha.6", default-features = false, features = ["rt-full"] }
-lazy_static = "1.4"
-#byteorder = "1.3"
-
-[dev-dependencies]
-hex = "0.3"
-assert_matches = "1.3"
-proptest = "0.9"
diff --git a/nix-rust/local.mk b/nix-rust/local.mk
deleted file mode 100644
index 538244594..000000000
--- a/nix-rust/local.mk
+++ /dev/null
@@ -1,48 +0,0 @@
-ifeq ($(OPTIMIZE), 1)
-  RUST_MODE = --release
-  RUST_DIR = release
-else
-  RUST_MODE =
-  RUST_DIR = debug
-endif
-
-libnixrust_PATH := $(d)/target/$(RUST_DIR)/libnixrust.$(SO_EXT)
-libnixrust_INSTALL_PATH := $(libdir)/libnixrust.$(SO_EXT)
-libnixrust_LDFLAGS_USE := -L$(d)/target/$(RUST_DIR) -lnixrust
-libnixrust_LDFLAGS_USE_INSTALLED := -L$(libdir) -lnixrust
-
-ifdef HOST_LINUX
-libnixrust_LDFLAGS_USE += -ldl
-libnixrust_LDFLAGS_USE_INSTALLED += -ldl
-endif
-
-ifdef HOST_DARWIN
-libnixrust_BUILD_FLAGS = NIX_LDFLAGS="-undefined dynamic_lookup"
-else
-libnixrust_LDFLAGS_USE += -Wl,-rpath,$(abspath $(d)/target/$(RUST_DIR))
-libnixrust_LDFLAGS_USE_INSTALLED += -Wl,-rpath,$(libdir)
-endif
-
-$(libnixrust_PATH): $(call rwildcard, $(d)/src, *.rs) $(d)/Cargo.toml
-	$(trace-gen) cd nix-rust && CARGO_HOME=$$(if [[ -d vendor ]]; then echo vendor; fi) \
-	$(libnixrust_BUILD_FLAGS) \
-	  cargo build $(RUST_MODE) $$(if [[ -d vendor ]]; then echo --offline; fi) \
-	&& touch target/$(RUST_DIR)/libnixrust.$(SO_EXT)
-
-$(libnixrust_INSTALL_PATH): $(libnixrust_PATH)
-	$(target-gen) cp $^ $@
-ifdef HOST_DARWIN
-	install_name_tool -id $@ $@
-endif
-
-clean: clean-rust
-
-clean-rust:
-	$(suppress) rm -rfv nix-rust/target
-
-ifndef HOST_DARWIN
-check: rust-tests
-
-rust-tests:
-	$(trace-test) cd nix-rust && CARGO_HOME=$$(if [[ -d vendor ]]; then echo vendor; fi) cargo test --release $$(if [[ -d vendor ]]; then echo --offline; fi)
-endif
diff --git a/nix-rust/src/c.rs b/nix-rust/src/c.rs
deleted file mode 100644
index c1358545f..000000000
--- a/nix-rust/src/c.rs
+++ /dev/null
@@ -1,77 +0,0 @@
-use super::{error, store::path, store::StorePath, util};
-
-#[no_mangle]
-pub unsafe extern "C" fn ffi_String_new(s: &str, out: *mut String) {
-    // FIXME: check whether 's' is valid UTF-8?
-    out.write(s.to_string())
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn ffi_String_drop(self_: *mut String) {
-    std::ptr::drop_in_place(self_);
-}
-
-#[no_mangle]
-pub extern "C" fn ffi_StorePath_new(
-    path: &str,
-    store_dir: &str,
-) -> Result<StorePath, error::CppException> {
-    StorePath::new(std::path::Path::new(path), std::path::Path::new(store_dir))
-        .map_err(|err| err.into())
-}
-
-#[no_mangle]
-pub extern "C" fn ffi_StorePath_new2(
-    hash: &[u8; crate::store::path::STORE_PATH_HASH_BYTES],
-    name: &str,
-) -> Result<StorePath, error::CppException> {
-    StorePath::from_parts(*hash, name).map_err(|err| err.into())
-}
-
-#[no_mangle]
-pub extern "C" fn ffi_StorePath_fromBaseName(
-    base_name: &str,
-) -> Result<StorePath, error::CppException> {
-    StorePath::new_from_base_name(base_name).map_err(|err| err.into())
-}
-
-#[no_mangle]
-pub unsafe extern "C" fn ffi_StorePath_drop(self_: *mut StorePath) {
-    std::ptr::drop_in_place(self_);
-}
-
-#[no_mangle]
-pub extern "C" fn ffi_StorePath_to_string(self_: &StorePath) -> Vec<u8> {
-    let mut buf = vec![0; path::STORE_PATH_HASH_CHARS + 1 + self_.name.name().len()];
-    util::base32::encode_into(self_.hash.hash(), &mut buf[0..path::STORE_PATH_HASH_CHARS]);
-    buf[path::STORE_PATH_HASH_CHARS] = b'-';
-    buf[path::STORE_PATH_HASH_CHARS + 1..].clone_from_slice(self_.name.name().as_bytes());
-    buf
-}
-
-#[no_mangle]
-pub extern "C" fn ffi_StorePath_less_than(a: &StorePath, b: &StorePath) -> bool {
-    a < b
-}
-
-#[no_mangle]
-pub extern "C" fn ffi_StorePath_eq(a: &StorePath, b: &StorePath) -> bool {
-    a == b
-}
-
-#[no_mangle]
-pub extern "C" fn ffi_StorePath_clone(self_: &StorePath) -> StorePath {
-    self_.clone()
-}
-
-#[no_mangle]
-pub extern "C" fn ffi_StorePath_name(self_: &StorePath) -> &str {
-    self_.name.name()
-}
-
-#[no_mangle]
-pub extern "C" fn ffi_StorePath_hash_data(
-    self_: &StorePath,
-) -> &[u8; crate::store::path::STORE_PATH_HASH_BYTES] {
-    self_.hash.hash()
-}
diff --git a/nix-rust/src/error.rs b/nix-rust/src/error.rs
deleted file mode 100644
index bb0c9a933..000000000
--- a/nix-rust/src/error.rs
+++ /dev/null
@@ -1,118 +0,0 @@
-use std::fmt;
-
-#[derive(Debug)]
-pub enum Error {
-    InvalidPath(crate::store::StorePath),
-    BadStorePath(std::path::PathBuf),
-    NotInStore(std::path::PathBuf),
-    BadNarInfo,
-    BadBase32,
-    StorePathNameEmpty,
-    StorePathNameTooLong,
-    BadStorePathName,
-    NarSizeFieldTooBig,
-    BadNarString,
-    BadNarPadding,
-    BadNarVersionMagic,
-    MissingNarOpenTag,
-    MissingNarCloseTag,
-    MissingNarField,
-    BadNarField(String),
-    BadExecutableField,
-    IOError(std::io::Error),
-    #[cfg(unused)]
-    HttpError(hyper::error::Error),
-    Misc(String),
-    #[cfg(not(test))]
-    Foreign(CppException),
-    BadTarFileMemberName(String),
-}
-
-impl From<std::io::Error> for Error {
-    fn from(err: std::io::Error) -> Self {
-        Error::IOError(err)
-    }
-}
-
-#[cfg(unused)]
-impl From<hyper::error::Error> for Error {
-    fn from(err: hyper::error::Error) -> Self {
-        Error::HttpError(err)
-    }
-}
-
-impl fmt::Display for Error {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self {
-            Error::InvalidPath(_) => write!(f, "invalid path"),
-            Error::BadNarInfo => write!(f, ".narinfo file is corrupt"),
-            Error::BadStorePath(path) => write!(f, "path '{}' is not a store path", path.display()),
-            Error::NotInStore(path) => {
-                write!(f, "path '{}' is not in the Nix store", path.display())
-            }
-            Error::BadBase32 => write!(f, "invalid base32 string"),
-            Error::StorePathNameEmpty => write!(f, "store path name is empty"),
-            Error::StorePathNameTooLong => {
-                write!(f, "store path name is longer than 211 characters")
-            }
-            Error::BadStorePathName => write!(f, "store path name contains forbidden character"),
-            Error::NarSizeFieldTooBig => write!(f, "size field in NAR is too big"),
-            Error::BadNarString => write!(f, "NAR string is not valid UTF-8"),
-            Error::BadNarPadding => write!(f, "NAR padding is not zero"),
-            Error::BadNarVersionMagic => write!(f, "unsupported NAR version"),
-            Error::MissingNarOpenTag => write!(f, "NAR open tag is missing"),
-            Error::MissingNarCloseTag => write!(f, "NAR close tag is missing"),
-            Error::MissingNarField => write!(f, "expected NAR field is missing"),
-            Error::BadNarField(s) => write!(f, "unrecognized NAR field '{}'", s),
-            Error::BadExecutableField => write!(f, "bad 'executable' field in NAR"),
-            Error::IOError(err) => write!(f, "I/O error: {}", err),
-            #[cfg(unused)]
-            Error::HttpError(err) => write!(f, "HTTP error: {}", err),
-            #[cfg(not(test))]
-            Error::Foreign(_) => write!(f, "<C++ exception>"), // FIXME
-            Error::Misc(s) => write!(f, "{}", s),
-            Error::BadTarFileMemberName(s) => {
-                write!(f, "tar archive contains illegal file name '{}'", s)
-            }
-        }
-    }
-}
-
-#[cfg(not(test))]
-impl From<Error> for CppException {
-    fn from(err: Error) -> Self {
-        match err {
-            Error::Foreign(ex) => ex,
-            _ => CppException::new(&err.to_string()),
-        }
-    }
-}
-
-#[cfg(not(test))]
-#[repr(C)]
-#[derive(Debug)]
-pub struct CppException(*const libc::c_void); // == std::exception_ptr*
-
-#[cfg(not(test))]
-impl CppException {
-    fn new(s: &str) -> Self {
-        Self(unsafe { make_error(s) })
-    }
-}
-
-#[cfg(not(test))]
-impl Drop for CppException {
-    fn drop(&mut self) {
-        unsafe {
-            destroy_error(self.0);
-        }
-    }
-}
-
-#[cfg(not(test))]
-extern "C" {
-    #[allow(improper_ctypes)] // YOLO
-    fn make_error(s: &str) -> *const libc::c_void;
-
-    fn destroy_error(exc: *const libc::c_void);
-}
diff --git a/nix-rust/src/lib.rs b/nix-rust/src/lib.rs
deleted file mode 100644
index 101de106f..000000000
--- a/nix-rust/src/lib.rs
+++ /dev/null
@@ -1,10 +0,0 @@
-#[allow(improper_ctypes_definitions)]
-#[cfg(not(test))]
-mod c;
-mod error;
-#[cfg(unused)]
-mod nar;
-mod store;
-mod util;
-
-pub use error::Error;
diff --git a/nix-rust/src/nar.rs b/nix-rust/src/nar.rs
deleted file mode 100644
index cb520935e..000000000
--- a/nix-rust/src/nar.rs
+++ /dev/null
@@ -1,126 +0,0 @@
-use crate::Error;
-use byteorder::{LittleEndian, ReadBytesExt};
-use std::convert::TryFrom;
-use std::io::Read;
-
-pub fn parse<R: Read>(input: &mut R) -> Result<(), Error> {
-    if String::read(input)? != NAR_VERSION_MAGIC {
-        return Err(Error::BadNarVersionMagic);
-    }
-
-    parse_file(input)
-}
-
-const NAR_VERSION_MAGIC: &str = "nix-archive-1";
-
-fn parse_file<R: Read>(input: &mut R) -> Result<(), Error> {
-    if String::read(input)? != "(" {
-        return Err(Error::MissingNarOpenTag);
-    }
-
-    if String::read(input)? != "type" {
-        return Err(Error::MissingNarField);
-    }
-
-    match String::read(input)?.as_ref() {
-        "regular" => {
-            let mut _executable = false;
-            let mut tag = String::read(input)?;
-            if tag == "executable" {
-                _executable = true;
-                if String::read(input)? != "" {
-                    return Err(Error::BadExecutableField);
-                }
-                tag = String::read(input)?;
-            }
-            if tag != "contents" {
-                return Err(Error::MissingNarField);
-            }
-            let _contents = Vec::<u8>::read(input)?;
-            if String::read(input)? != ")" {
-                return Err(Error::MissingNarCloseTag);
-            }
-        }
-        "directory" => loop {
-            match String::read(input)?.as_ref() {
-                "entry" => {
-                    if String::read(input)? != "(" {
-                        return Err(Error::MissingNarOpenTag);
-                    }
-                    if String::read(input)? != "name" {
-                        return Err(Error::MissingNarField);
-                    }
-                    let _name = String::read(input)?;
-                    if String::read(input)? != "node" {
-                        return Err(Error::MissingNarField);
-                    }
-                    parse_file(input)?;
-                    let tag = String::read(input)?;
-                    if tag != ")" {
-                        return Err(Error::MissingNarCloseTag);
-                    }
-                }
-                ")" => break,
-                s => return Err(Error::BadNarField(s.into())),
-            }
-        },
-        "symlink" => {
-            if String::read(input)? != "target" {
-                return Err(Error::MissingNarField);
-            }
-            let _target = String::read(input)?;
-            if String::read(input)? != ")" {
-                return Err(Error::MissingNarCloseTag);
-            }
-        }
-        s => return Err(Error::BadNarField(s.into())),
-    }
-
-    Ok(())
-}
-
-trait Deserialize: Sized {
-    fn read<R: Read>(input: &mut R) -> Result<Self, Error>;
-}
-
-impl Deserialize for String {
-    fn read<R: Read>(input: &mut R) -> Result<Self, Error> {
-        let buf = Deserialize::read(input)?;
-        Ok(String::from_utf8(buf).map_err(|_| Error::BadNarString)?)
-    }
-}
-
-impl Deserialize for Vec<u8> {
-    fn read<R: Read>(input: &mut R) -> Result<Self, Error> {
-        let n: usize = Deserialize::read(input)?;
-        let mut buf = vec![0; n];
-        input.read_exact(&mut buf)?;
-        skip_padding(input, n)?;
-        Ok(buf)
-    }
-}
-
-fn skip_padding<R: Read>(input: &mut R, len: usize) -> Result<(), Error> {
-    if len % 8 != 0 {
-        let mut buf = [0; 8];
-        let buf = &mut buf[0..8 - (len % 8)];
-        input.read_exact(buf)?;
-        if !buf.iter().all(|b| *b == 0) {
-            return Err(Error::BadNarPadding);
-        }
-    }
-    Ok(())
-}
-
-impl Deserialize for u64 {
-    fn read<R: Read>(input: &mut R) -> Result<Self, Error> {
-        Ok(input.read_u64::<LittleEndian>()?)
-    }
-}
-
-impl Deserialize for usize {
-    fn read<R: Read>(input: &mut R) -> Result<Self, Error> {
-        let n: u64 = Deserialize::read(input)?;
-        Ok(usize::try_from(n).map_err(|_| Error::NarSizeFieldTooBig)?)
-    }
-}
diff --git a/nix-rust/src/store/binary_cache_store.rs b/nix-rust/src/store/binary_cache_store.rs
deleted file mode 100644
index 9e1e88b7c..000000000
--- a/nix-rust/src/store/binary_cache_store.rs
+++ /dev/null
@@ -1,48 +0,0 @@
-use super::{PathInfo, Store, StorePath};
-use crate::Error;
-use hyper::client::Client;
-
-pub struct BinaryCacheStore {
-    base_uri: String,
-    client: Client<hyper::client::HttpConnector, hyper::Body>,
-}
-
-impl BinaryCacheStore {
-    pub fn new(base_uri: String) -> Self {
-        Self {
-            base_uri,
-            client: Client::new(),
-        }
-    }
-}
-
-impl Store for BinaryCacheStore {
-    fn query_path_info(
-        &self,
-        path: &StorePath,
-    ) -> std::pin::Pin<Box<dyn std::future::Future<Output = Result<PathInfo, Error>> + Send>> {
-        let uri = format!("{}/{}.narinfo", self.base_uri.clone(), path.hash);
-        let path = path.clone();
-        let client = self.client.clone();
-        let store_dir = self.store_dir().to_string();
-
-        Box::pin(async move {
-            let response = client.get(uri.parse::<hyper::Uri>().unwrap()).await?;
-
-            if response.status() == hyper::StatusCode::NOT_FOUND
-                || response.status() == hyper::StatusCode::FORBIDDEN
-            {
-                return Err(Error::InvalidPath(path));
-            }
-
-            let mut body = response.into_body();
-
-            let mut bytes = Vec::new();
-            while let Some(next) = body.next().await {
-                bytes.extend(next?);
-            }
-
-            PathInfo::parse_nar_info(std::str::from_utf8(&bytes).unwrap(), &store_dir)
-        })
-    }
-}
diff --git a/nix-rust/src/store/mod.rs b/nix-rust/src/store/mod.rs
deleted file mode 100644
index da972482c..000000000
--- a/nix-rust/src/store/mod.rs
+++ /dev/null
@@ -1,17 +0,0 @@
-pub mod path;
-
-#[cfg(unused)]
-mod binary_cache_store;
-#[cfg(unused)]
-mod path_info;
-#[cfg(unused)]
-mod store;
-
-pub use path::{StorePath, StorePathHash, StorePathName};
-
-#[cfg(unused)]
-pub use binary_cache_store::BinaryCacheStore;
-#[cfg(unused)]
-pub use path_info::PathInfo;
-#[cfg(unused)]
-pub use store::Store;
diff --git a/nix-rust/src/store/path.rs b/nix-rust/src/store/path.rs
deleted file mode 100644
index 99f7a1f18..000000000
--- a/nix-rust/src/store/path.rs
+++ /dev/null
@@ -1,224 +0,0 @@
-use crate::error::Error;
-use crate::util::base32;
-use std::fmt;
-use std::path::Path;
-
-#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Debug)]
-pub struct StorePath {
-    pub hash: StorePathHash,
-    pub name: StorePathName,
-}
-
-pub const STORE_PATH_HASH_BYTES: usize = 20;
-pub const STORE_PATH_HASH_CHARS: usize = 32;
-
-impl StorePath {
-    pub fn new(path: &Path, store_dir: &Path) -> Result<Self, Error> {
-        if path.parent() != Some(store_dir) {
-            return Err(Error::NotInStore(path.into()));
-        }
-        Self::new_from_base_name(
-            path.file_name()
-                .ok_or_else(|| Error::BadStorePath(path.into()))?
-                .to_str()
-                .ok_or_else(|| Error::BadStorePath(path.into()))?,
-        )
-    }
-
-    pub fn from_parts(hash: [u8; STORE_PATH_HASH_BYTES], name: &str) -> Result<Self, Error> {
-        Ok(StorePath {
-            hash: StorePathHash(hash),
-            name: StorePathName::new(name)?,
-        })
-    }
-
-    pub fn new_from_base_name(base_name: &str) -> Result<Self, Error> {
-        if base_name.len() < STORE_PATH_HASH_CHARS + 1
-            || base_name.as_bytes()[STORE_PATH_HASH_CHARS] != b'-'
-        {
-            return Err(Error::BadStorePath(base_name.into()));
-        }
-
-        Ok(StorePath {
-            hash: StorePathHash::new(&base_name[0..STORE_PATH_HASH_CHARS])?,
-            name: StorePathName::new(&base_name[STORE_PATH_HASH_CHARS + 1..])?,
-        })
-    }
-}
-
-impl fmt::Display for StorePath {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{}-{}", self.hash, self.name)
-    }
-}
-
-#[derive(Clone, PartialEq, Eq, Debug)]
-pub struct StorePathHash([u8; STORE_PATH_HASH_BYTES]);
-
-impl StorePathHash {
-    pub fn new(s: &str) -> Result<Self, Error> {
-        assert_eq!(s.len(), STORE_PATH_HASH_CHARS);
-        let v = base32::decode(s)?;
-        assert_eq!(v.len(), STORE_PATH_HASH_BYTES);
-        let mut bytes: [u8; 20] = Default::default();
-        bytes.copy_from_slice(&v[0..STORE_PATH_HASH_BYTES]);
-        Ok(Self(bytes))
-    }
-
-    pub fn hash(&self) -> &[u8; STORE_PATH_HASH_BYTES] {
-        &self.0
-    }
-}
-
-impl fmt::Display for StorePathHash {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let mut buf = vec![0; STORE_PATH_HASH_CHARS];
-        base32::encode_into(&self.0, &mut buf);
-        f.write_str(std::str::from_utf8(&buf).unwrap())
-    }
-}
-
-impl Ord for StorePathHash {
-    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
-        // Historically we've sorted store paths by their base32
-        // serialization, but our base32 encodes bytes in reverse
-        // order. So compare them in reverse order as well.
-        self.0.iter().rev().cmp(other.0.iter().rev())
-    }
-}
-
-impl PartialOrd for StorePathHash {
-    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Debug)]
-pub struct StorePathName(String);
-
-impl StorePathName {
-    pub fn new(s: &str) -> Result<Self, Error> {
-        if s.is_empty() {
-            return Err(Error::StorePathNameEmpty);
-        }
-
-        if s.len() > 211 {
-            return Err(Error::StorePathNameTooLong);
-        }
-
-        let is_good_path_name = s.chars().all(|c| {
-            c.is_ascii_alphabetic()
-                || c.is_ascii_digit()
-                || c == '+'
-                || c == '-'
-                || c == '.'
-                || c == '_'
-                || c == '?'
-                || c == '='
-        });
-        if s.starts_with('.') || !is_good_path_name {
-            return Err(Error::BadStorePathName);
-        }
-
-        Ok(Self(s.to_string()))
-    }
-
-    pub fn name(&self) -> &str {
-        &self.0
-    }
-}
-
-impl fmt::Display for StorePathName {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.write_str(&self.0)
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use assert_matches::assert_matches;
-
-    #[test]
-    fn test_parse() {
-        let s = "7h7qgvs4kgzsn8a6rb273saxyqh4jxlz-konsole-18.12.3";
-        let p = StorePath::new_from_base_name(&s).unwrap();
-        assert_eq!(p.name.0, "konsole-18.12.3");
-        assert_eq!(
-            p.hash.0,
-            [
-                0x9f, 0x76, 0x49, 0x20, 0xf6, 0x5d, 0xe9, 0x71, 0xc4, 0xca, 0x46, 0x21, 0xab, 0xff,
-                0x9b, 0x44, 0xef, 0x87, 0x0f, 0x3c
-            ]
-        );
-    }
-
-    #[test]
-    fn test_no_name() {
-        let s = "7h7qgvs4kgzsn8a6rb273saxyqh4jxlz-";
-        assert_matches!(
-            StorePath::new_from_base_name(&s),
-            Err(Error::StorePathNameEmpty)
-        );
-    }
-
-    #[test]
-    fn test_no_dash() {
-        let s = "7h7qgvs4kgzsn8a6rb273saxyqh4jxlz";
-        assert_matches!(
-            StorePath::new_from_base_name(&s),
-            Err(Error::BadStorePath(_))
-        );
-    }
-
-    #[test]
-    fn test_short_hash() {
-        let s = "7h7qgvs4kgzsn8a6rb273saxyqh4jxl-konsole-18.12.3";
-        assert_matches!(
-            StorePath::new_from_base_name(&s),
-            Err(Error::BadStorePath(_))
-        );
-    }
-
-    #[test]
-    fn test_invalid_hash() {
-        let s = "7h7qgvs4kgzsn8e6rb273saxyqh4jxlz-konsole-18.12.3";
-        assert_matches!(StorePath::new_from_base_name(&s), Err(Error::BadBase32));
-    }
-
-    #[test]
-    fn test_long_name() {
-        let s = "7h7qgvs4kgzsn8a6rb273saxyqh4jxlz-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";
-        assert_matches!(StorePath::new_from_base_name(&s), Ok(_));
-    }
-
-    #[test]
-    fn test_too_long_name() {
-        let s = "7h7qgvs4kgzsn8a6rb273saxyqh4jxlz-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";
-        assert_matches!(
-            StorePath::new_from_base_name(&s),
-            Err(Error::StorePathNameTooLong)
-        );
-    }
-
-    #[test]
-    fn test_bad_name() {
-        let s = "7h7qgvs4kgzsn8a6rb273saxyqh4jxlz-foo bar";
-        assert_matches!(
-            StorePath::new_from_base_name(&s),
-            Err(Error::BadStorePathName)
-        );
-
-        let s = "7h7qgvs4kgzsn8a6rb273saxyqh4jxlz-kónsole";
-        assert_matches!(
-            StorePath::new_from_base_name(&s),
-            Err(Error::BadStorePathName)
-        );
-    }
-
-    #[test]
-    fn test_roundtrip() {
-        let s = "7h7qgvs4kgzsn8a6rb273saxyqh4jxlz-konsole-18.12.3";
-        assert_eq!(StorePath::new_from_base_name(&s).unwrap().to_string(), s);
-    }
-}
diff --git a/nix-rust/src/store/path_info.rs b/nix-rust/src/store/path_info.rs
deleted file mode 100644
index c2903ed29..000000000
--- a/nix-rust/src/store/path_info.rs
+++ /dev/null
@@ -1,70 +0,0 @@
-use crate::store::StorePath;
-use crate::Error;
-use std::collections::BTreeSet;
-
-#[derive(Clone, Debug)]
-pub struct PathInfo {
-    pub path: StorePath,
-    pub references: BTreeSet<StorePath>,
-    pub nar_size: u64,
-    pub deriver: Option<StorePath>,
-
-    // Additional binary cache info.
-    pub url: Option<String>,
-    pub compression: Option<String>,
-    pub file_size: Option<u64>,
-}
-
-impl PathInfo {
-    pub fn parse_nar_info(nar_info: &str, store_dir: &str) -> Result<Self, Error> {
-        let mut path = None;
-        let mut references = BTreeSet::new();
-        let mut nar_size = None;
-        let mut deriver = None;
-        let mut url = None;
-        let mut compression = None;
-        let mut file_size = None;
-
-        for line in nar_info.lines() {
-            let colon = line.find(':').ok_or(Error::BadNarInfo)?;
-
-            let (name, value) = line.split_at(colon);
-
-            if !value.starts_with(": ") {
-                return Err(Error::BadNarInfo);
-            }
-
-            let value = &value[2..];
-
-            if name == "StorePath" {
-                path = Some(StorePath::new(std::path::Path::new(value), store_dir)?);
-            } else if name == "NarSize" {
-                nar_size = Some(u64::from_str_radix(value, 10).map_err(|_| Error::BadNarInfo)?);
-            } else if name == "References" {
-                if !value.is_empty() {
-                    for r in value.split(' ') {
-                        references.insert(StorePath::new_from_base_name(r)?);
-                    }
-                }
-            } else if name == "Deriver" {
-                deriver = Some(StorePath::new_from_base_name(value)?);
-            } else if name == "URL" {
-                url = Some(value.into());
-            } else if name == "Compression" {
-                compression = Some(value.into());
-            } else if name == "FileSize" {
-                file_size = Some(u64::from_str_radix(value, 10).map_err(|_| Error::BadNarInfo)?);
-            }
-        }
-
-        Ok(PathInfo {
-            path: path.ok_or(Error::BadNarInfo)?,
-            references,
-            nar_size: nar_size.ok_or(Error::BadNarInfo)?,
-            deriver,
-            url: Some(url.ok_or(Error::BadNarInfo)?),
-            compression,
-            file_size,
-        })
-    }
-}
diff --git a/nix-rust/src/store/store.rs b/nix-rust/src/store/store.rs
deleted file mode 100644
index c33dc4a90..000000000
--- a/nix-rust/src/store/store.rs
+++ /dev/null
@@ -1,53 +0,0 @@
-use super::{PathInfo, StorePath};
-use crate::Error;
-use std::collections::{BTreeMap, BTreeSet};
-use std::path::Path;
-
-pub trait Store: Send + Sync {
-    fn store_dir(&self) -> &str {
-        "/nix/store"
-    }
-
-    fn query_path_info(
-        &self,
-        store_path: &StorePath,
-    ) -> std::pin::Pin<Box<dyn std::future::Future<Output = Result<PathInfo, Error>> + Send>>;
-}
-
-impl dyn Store {
-    pub fn parse_store_path(&self, path: &Path) -> Result<StorePath, Error> {
-        StorePath::new(path, self.store_dir())
-    }
-
-    pub async fn compute_path_closure(
-        &self,
-        roots: BTreeSet<StorePath>,
-    ) -> Result<BTreeMap<StorePath, PathInfo>, Error> {
-        let mut done = BTreeSet::new();
-        let mut result = BTreeMap::new();
-        let mut pending = vec![];
-
-        for root in roots {
-            pending.push(self.query_path_info(&root));
-            done.insert(root);
-        }
-
-        while !pending.is_empty() {
-            let (info, _, remaining) = futures::future::select_all(pending).await;
-            pending = remaining;
-
-            let info = info?;
-
-            for path in &info.references {
-                if !done.contains(path) {
-                    pending.push(self.query_path_info(&path));
-                    done.insert(path.clone());
-                }
-            }
-
-            result.insert(info.path.clone(), info);
-        }
-
-        Ok(result)
-    }
-}
diff --git a/nix-rust/src/util/base32.rs b/nix-rust/src/util/base32.rs
deleted file mode 100644
index 7e71dc920..000000000
--- a/nix-rust/src/util/base32.rs
+++ /dev/null
@@ -1,160 +0,0 @@
-use crate::error::Error;
-use lazy_static::lazy_static;
-
-pub fn encoded_len(input_len: usize) -> usize {
-    if input_len == 0 {
-        0
-    } else {
-        (input_len * 8 - 1) / 5 + 1
-    }
-}
-
-pub fn decoded_len(input_len: usize) -> usize {
-    input_len * 5 / 8
-}
-
-static BASE32_CHARS: &[u8; 32] = &b"0123456789abcdfghijklmnpqrsvwxyz";
-
-lazy_static! {
-    static ref BASE32_CHARS_REVERSE: Box<[u8; 256]> = {
-        let mut xs = [0xffu8; 256];
-        for (n, c) in BASE32_CHARS.iter().enumerate() {
-            xs[*c as usize] = n as u8;
-        }
-        Box::new(xs)
-    };
-}
-
-pub fn encode(input: &[u8]) -> String {
-    let mut buf = vec![0; encoded_len(input.len())];
-    encode_into(input, &mut buf);
-    std::str::from_utf8(&buf).unwrap().to_string()
-}
-
-pub fn encode_into(input: &[u8], output: &mut [u8]) {
-    let len = encoded_len(input.len());
-    assert_eq!(len, output.len());
-
-    let mut nr_bits_left: usize = 0;
-    let mut bits_left: u16 = 0;
-    let mut pos = len;
-
-    for b in input {
-        bits_left |= (*b as u16) << nr_bits_left;
-        nr_bits_left += 8;
-        while nr_bits_left > 5 {
-            output[pos - 1] = BASE32_CHARS[(bits_left & 0x1f) as usize];
-            pos -= 1;
-            bits_left >>= 5;
-            nr_bits_left -= 5;
-        }
-    }
-
-    if nr_bits_left > 0 {
-        output[pos - 1] = BASE32_CHARS[(bits_left & 0x1f) as usize];
-        pos -= 1;
-    }
-
-    assert_eq!(pos, 0);
-}
-
-pub fn decode(input: &str) -> Result<Vec<u8>, crate::Error> {
-    let mut res = Vec::with_capacity(decoded_len(input.len()));
-
-    let mut nr_bits_left: usize = 0;
-    let mut bits_left: u16 = 0;
-
-    for c in input.chars().rev() {
-        let b = BASE32_CHARS_REVERSE[c as usize];
-        if b == 0xff {
-            return Err(Error::BadBase32);
-        }
-        bits_left |= (b as u16) << nr_bits_left;
-        nr_bits_left += 5;
-        if nr_bits_left >= 8 {
-            res.push((bits_left & 0xff) as u8);
-            bits_left >>= 8;
-            nr_bits_left -= 8;
-        }
-    }
-
-    if nr_bits_left > 0 && bits_left != 0 {
-        return Err(Error::BadBase32);
-    }
-
-    Ok(res)
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use assert_matches::assert_matches;
-    use hex;
-    use proptest::proptest;
-
-    #[test]
-    fn test_encode() {
-        assert_eq!(encode(&[]), "");
-
-        assert_eq!(
-            encode(&hex::decode("0839703786356bca59b0f4a32987eb2e6de43ae8").unwrap()),
-            "x0xf8v9fxf3jk8zln1cwlsrmhqvp0f88"
-        );
-
-        assert_eq!(
-            encode(
-                &hex::decode("ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad")
-                    .unwrap()
-            ),
-            "1b8m03r63zqhnjf7l5wnldhh7c134ap5vpj0850ymkq1iyzicy5s"
-        );
-
-        assert_eq!(
-            encode(
-                &hex::decode("ddaf35a193617abacc417349ae20413112e6fa4e89a97ea20a9eeee64b55d39a2192992a274fc1a836ba3c23a3feebbd454d4423643ce80e2a9ac94fa54ca49f")
-                    .unwrap()
-            ),
-            "2gs8k559z4rlahfx0y688s49m2vvszylcikrfinm30ly9rak69236nkam5ydvly1ai7xac99vxfc4ii84hawjbk876blyk1jfhkbbyx"
-        );
-    }
-
-    #[test]
-    fn test_decode() {
-        assert_eq!(hex::encode(decode("").unwrap()), "");
-
-        assert_eq!(
-            hex::encode(decode("x0xf8v9fxf3jk8zln1cwlsrmhqvp0f88").unwrap()),
-            "0839703786356bca59b0f4a32987eb2e6de43ae8"
-        );
-
-        assert_eq!(
-            hex::encode(decode("1b8m03r63zqhnjf7l5wnldhh7c134ap5vpj0850ymkq1iyzicy5s").unwrap()),
-            "ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad"
-        );
-
-        assert_eq!(
-            hex::encode(decode("2gs8k559z4rlahfx0y688s49m2vvszylcikrfinm30ly9rak69236nkam5ydvly1ai7xac99vxfc4ii84hawjbk876blyk1jfhkbbyx").unwrap()),
-            "ddaf35a193617abacc417349ae20413112e6fa4e89a97ea20a9eeee64b55d39a2192992a274fc1a836ba3c23a3feebbd454d4423643ce80e2a9ac94fa54ca49f"
-        );
-
-        assert_matches!(
-            decode("xoxf8v9fxf3jk8zln1cwlsrmhqvp0f88"),
-            Err(Error::BadBase32)
-        );
-        assert_matches!(
-            decode("2b8m03r63zqhnjf7l5wnldhh7c134ap5vpj0850ymkq1iyzicy5s"),
-            Err(Error::BadBase32)
-        );
-        assert_matches!(decode("2"), Err(Error::BadBase32));
-        assert_matches!(decode("2gs"), Err(Error::BadBase32));
-        assert_matches!(decode("2gs8"), Err(Error::BadBase32));
-    }
-
-    proptest! {
-
-        #[test]
-        fn roundtrip(s: Vec<u8>) {
-            assert_eq!(s, decode(&encode(&s)).unwrap());
-        }
-    }
-}
diff --git a/nix-rust/src/util/mod.rs b/nix-rust/src/util/mod.rs
deleted file mode 100644
index eaad9d406..000000000
--- a/nix-rust/src/util/mod.rs
+++ /dev/null
@@ -1 +0,0 @@
-pub mod base32;
diff --git a/src/libutil/rust-ffi.cc b/src/libutil/rust-ffi.cc
deleted file mode 100644
index 67924568f..000000000
--- a/src/libutil/rust-ffi.cc
+++ /dev/null
@@ -1,24 +0,0 @@
-#if 0
-#include "logging.hh"
-#include "rust-ffi.hh"
-
-extern "C" std::exception_ptr * make_error(rust::StringSlice s)
-{
-    return new std::exception_ptr(std::make_exception_ptr(nix::Error(std::string(s.ptr, s.size))));
-}
-
-extern "C" void destroy_error(std::exception_ptr * ex)
-{
-    free(ex);
-}
-
-namespace rust {
-
-std::ostream & operator << (std::ostream & str, const String & s)
-{
-    str << (std::string_view) s;
-    return str;
-}
-
-}
-#endif
diff --git a/src/libutil/rust-ffi.hh b/src/libutil/rust-ffi.hh
deleted file mode 100644
index cfbaf9dec..000000000
--- a/src/libutil/rust-ffi.hh
+++ /dev/null
@@ -1,189 +0,0 @@
-#pragma once
-#if 0
-
-#include "serialise.hh"
-
-#include <string_view>
-#include <cstring>
-#include <array>
-
-namespace rust {
-
-typedef void (*DropFun)(void *);
-
-/* A Rust value of N bytes. It can be moved but not copied. When it
-   goes out of scope, the C++ destructor will run the drop
-   function. */
-template<std::size_t N, DropFun drop>
-struct Value
-{
-protected:
-
-    std::array<char, N> raw;
-
-    ~Value()
-    {
-        if (!isEvacuated()) {
-            drop(this);
-            evacuate();
-        }
-    }
-
-    // Must not be called directly.
-    Value()
-    { }
-
-    Value(Value && other)
-        : raw(other.raw)
-    {
-        other.evacuate();
-    }
-
-    void operator =(Value && other)
-    {
-        if (!isEvacuated())
-            drop(this);
-        raw = other.raw;
-        other.evacuate();
-    }
-
-private:
-
-    /* FIXME: optimize these (ideally in such a way that the compiler
-       can elide most calls to evacuate() / isEvacuated(). */
-    inline void evacuate()
-    {
-        for (auto & i : raw) i = 0;
-    }
-
-    inline bool isEvacuated()
-    {
-        for (auto & i : raw)
-            if (i != 0) return false;
-        return true;
-    }
-};
-
-/* A Rust vector. */
-template<typename T, DropFun drop>
-struct Vec : Value<3 * sizeof(void *), drop>
-{
-    inline size_t size() const
-    {
-        return ((const size_t *) &this->raw)[2];
-    }
-
-    const T * data() const
-    {
-        return ((const T * *) &this->raw)[0];
-    }
-};
-
-/* A Rust slice. */
-template<typename T>
-struct Slice
-{
-    const T * ptr;
-    size_t size;
-
-    Slice(const T * ptr, size_t size) : ptr(ptr), size(size)
-    {
-        assert(ptr);
-    }
-};
-
-struct StringSlice : Slice<char>
-{
-    StringSlice(const std::string & s): Slice(s.data(), s.size()) {}
-    explicit StringSlice(std::string_view s): Slice(s.data(), s.size()) {}
-    StringSlice(const char * s): Slice(s, strlen(s)) {}
-
-    operator std::string_view() const
-    {
-        return std::string_view(ptr, size);
-    }
-};
-
-/* A Rust string. */
-struct String;
-
-extern "C" {
-    void ffi_String_new(StringSlice s, String * out);
-    void ffi_String_drop(void * s);
-}
-
-struct String : Vec<char, ffi_String_drop>
-{
-    String() = delete;
-
-    String(std::string_view s)
-    {
-        ffi_String_new(StringSlice(s), this);
-    }
-
-    String(const char * s)
-        : String({s, std::strlen(s)})
-    {
-    }
-
-    operator std::string_view() const
-    {
-        return std::string_view(data(), size());
-    }
-};
-
-std::ostream & operator << (std::ostream & str, const String & s);
-
-/* C++ representation of Rust's Result<T, CppException>. */
-template<typename T>
-struct Result
-{
-    enum { Ok = 0, Err = 1, Uninit = 2 } tag;
-
-    union {
-        T data;
-        std::exception_ptr * exc;
-    };
-
-    Result() : tag(Uninit) { }; // FIXME: remove
-
-    Result(const Result &) = delete;
-
-    Result(Result && other)
-        : tag(other.tag)
-    {
-        other.tag = Uninit;
-        if (tag == Ok)
-            data = std::move(other.data);
-        else if (tag == Err)
-            exc = other.exc;
-    }
-
-    ~Result()
-    {
-        if (tag == Ok)
-            data.~T();
-        else if (tag == Err)
-            free(exc);
-        else if (tag == Uninit)
-            ;
-        else
-            abort();
-    }
-
-    /* Rethrow the wrapped exception or return the wrapped value. */
-    T unwrap()
-    {
-        if (tag == Ok) {
-            tag = Uninit;
-            return std::move(data);
-        }
-        else if (tag == Err)
-            std::rethrow_exception(*exc);
-        else
-            abort();
-    }
-};
-
-}
-#endif

From 203ef26974d5edf9e67bce6153407414be42cf91 Mon Sep 17 00:00:00 2001
From: "lincoln auster [they/them]" <lincolnauster@gmail.com>
Date: Tue, 25 Jan 2022 11:59:51 -0700
Subject: [PATCH 484/567] flakes: document nixConfig option

Fixes #5988.
---
 src/nix/flake.md | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/nix/flake.md b/src/nix/flake.md
index a8436bcaa..db6e20d4f 100644
--- a/src/nix/flake.md
+++ b/src/nix/flake.md
@@ -292,6 +292,12 @@ The following attributes are supported in `flake.nix`:
   value (e.g. `packages.x86_64-linux` must be an attribute set of
   derivations built for the `x86_64-linux` platform).
 
+* `nixConfig`: a set of `nix.conf` options to be set when evaluating any
+  part of a flake. In the interests of security, only a small set of
+  whitelisted options (currently `bash-prompt`, `brash-prompt-suffix`,
+  and `flake-registry`) are allowed to be set without confirmation so long as
+  `accept-flake-config` is not set in the global configuration.
+
 ## Flake inputs
 
 The attribute `inputs` specifies the dependencies of a flake, as an

From 35dbdbedd41dea45bf38ae11d74f72c39eb304c3 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 25 Jan 2022 21:14:27 +0100
Subject: [PATCH 485/567] nix store ping: Report Nix daemon version

Fixes #5952.
---
 doc/manual/src/release-notes/rl-next.md |  1 +
 src/libstore/daemon.cc                  |  6 +++++-
 src/libstore/local-store.cc             |  6 ++++++
 src/libstore/local-store.hh             |  2 ++
 src/libstore/remote-store.cc            | 14 +++++++++++++-
 src/libstore/remote-store.hh            |  3 +++
 src/libstore/store-api.hh               |  3 +++
 src/libstore/worker-protocol.hh         |  2 +-
 src/nix/ping-store.cc                   |  3 +++
 9 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index 78ae99f4b..d795e7b11 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -1,2 +1,3 @@
 # Release X.Y (202?-??-??)
 
+* `nix store ping` now reports the version of the remote Nix daemon.
diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index 101aa13a5..1ddd1a4d5 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -981,7 +981,11 @@ void processConnection(
         readInt(from);
     }
 
-    readInt(from); // obsolete reserveSpace
+    if (GET_PROTOCOL_MINOR(clientVersion) >= 11)
+        readInt(from); // obsolete reserveSpace
+
+    if (GET_PROTOCOL_MINOR(clientVersion) >= 33)
+        to << nixVersion;
 
     /* Send startup error messages to the client. */
     tunnelLogger->startWork();
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 1807940d8..284e385e6 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -1919,4 +1919,10 @@ void LocalStore::addBuildLog(const StorePath & drvPath, std::string_view log)
         throw SysError("renaming '%1%' to '%2%'", tmpFile, logPath);
 }
 
+std::optional<std::string> LocalStore::getVersion()
+{
+    return nixVersion;
+}
+
+
 }  // namespace nix
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 6d867d778..8cf9c68b3 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -211,6 +211,8 @@ public:
     void queryRealisationUncached(const DrvOutput&,
         Callback<std::shared_ptr<const Realisation>> callback) noexcept override;
 
+    std::optional<std::string> getVersion() override;
+
 private:
 
     int getSchema();
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index aac2965e0..573becfbd 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -188,7 +188,12 @@ void RemoteStore::initConnection(Connection & conn)
         }
 
         if (GET_PROTOCOL_MINOR(conn.daemonVersion) >= 11)
-            conn.to << false;
+            conn.to << false; // obsolete reserveSpace
+
+        if (GET_PROTOCOL_MINOR(conn.daemonVersion) >= 33) {
+            conn.to.flush();
+            conn.daemonNixVersion = readString(conn.from);
+        }
 
         auto ex = conn.processStderr();
         if (ex) std::rethrow_exception(ex);
@@ -920,6 +925,13 @@ void RemoteStore::addBuildLog(const StorePath & drvPath, std::string_view log)
 }
 
 
+std::optional<std::string> RemoteStore::getVersion()
+{
+    auto conn(getConnection());
+    return conn->daemonNixVersion;
+}
+
+
 void RemoteStore::connect()
 {
     auto conn(getConnection());
diff --git a/src/libstore/remote-store.hh b/src/libstore/remote-store.hh
index 4754ff45a..b91d25fa9 100644
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@@ -118,6 +118,8 @@ public:
 
     void addBuildLog(const StorePath & drvPath, std::string_view log) override;
 
+    std::optional<std::string> getVersion() override;
+
     void connect() override;
 
     unsigned int getProtocol() override;
@@ -129,6 +131,7 @@ public:
         FdSink to;
         FdSource from;
         unsigned int daemonVersion;
+        std::optional<std::string> daemonNixVersion;
         std::chrono::time_point<std::chrono::steady_clock> startTime;
 
         virtual ~Connection();
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 8306509f3..4068f8f35 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -765,6 +765,9 @@ public:
      * (a no-op when there’s no daemon)
      */
     virtual void setOptions() { }
+
+    virtual std::optional<std::string> getVersion() { return {}; }
+
 protected:
 
     Stats stats;
diff --git a/src/libstore/worker-protocol.hh b/src/libstore/worker-protocol.hh
index ecf42a5d0..c8332afe6 100644
--- a/src/libstore/worker-protocol.hh
+++ b/src/libstore/worker-protocol.hh
@@ -9,7 +9,7 @@ namespace nix {
 #define WORKER_MAGIC_1 0x6e697863
 #define WORKER_MAGIC_2 0x6478696f
 
-#define PROTOCOL_VERSION (1 << 8 | 32)
+#define PROTOCOL_VERSION (1 << 8 | 33)
 #define GET_PROTOCOL_MAJOR(x) ((x) & 0xff00)
 #define GET_PROTOCOL_MINOR(x) ((x) & 0x00ff)
 
diff --git a/src/nix/ping-store.cc b/src/nix/ping-store.cc
index 62b645b06..3c3b7bb45 100644
--- a/src/nix/ping-store.cc
+++ b/src/nix/ping-store.cc
@@ -20,7 +20,10 @@ struct CmdPingStore : StoreCommand
 
     void run(ref<Store> store) override
     {
+        notice("Store URL: %s", store->getUri());
         store->connect();
+        if (auto version = store->getVersion())
+            notice("Version: %s", *version);
     }
 };
 

From c746a429db0e48e60362b6ea45b5d01551ba46d6 Mon Sep 17 00:00:00 2001
From: lincoln auster <lincolnauster@gmail.com>
Date: Tue, 25 Jan 2022 14:55:49 -0700
Subject: [PATCH 486/567] fix typo

Co-authored-by: Cole Helbling <cole.e.helbling@outlook.com>
---
 src/nix/flake.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/nix/flake.md b/src/nix/flake.md
index db6e20d4f..accddd436 100644
--- a/src/nix/flake.md
+++ b/src/nix/flake.md
@@ -294,7 +294,7 @@ The following attributes are supported in `flake.nix`:
 
 * `nixConfig`: a set of `nix.conf` options to be set when evaluating any
   part of a flake. In the interests of security, only a small set of
-  whitelisted options (currently `bash-prompt`, `brash-prompt-suffix`,
+  whitelisted options (currently `bash-prompt`, `bash-prompt-suffix`,
   and `flake-registry`) are allowed to be set without confirmation so long as
   `accept-flake-config` is not set in the global configuration.
 

From 1eac5a6bd0352ff2366e1feedd01abbd83d59546 Mon Sep 17 00:00:00 2001
From: Rok Garbas <rok@garbas.si>
Date: Wed, 26 Jan 2022 09:22:51 +0100
Subject: [PATCH 487/567] Script to push docker image for releases

---
 maintainers/push-docker.sh | 69 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100755 maintainers/push-docker.sh

diff --git a/maintainers/push-docker.sh b/maintainers/push-docker.sh
new file mode 100755
index 000000000..a705f0738
--- /dev/null
+++ b/maintainers/push-docker.sh
@@ -0,0 +1,69 @@
+#/usr/bin/env bash
+
+# TODO: parse from .version
+MAINTENANCE_VERSION="2.6"
+VERSION="$MAINTENANCE_VERSION.0"
+
+# Should be override `latest` tag, default true
+PUSH_AS_LATEST=1
+
+PLATFORMS="x86_64-linux aarch64-linux"
+
+# ensure we are logged to docker hub
+docker login
+
+DOCKER_MANIFEST=""
+DOCKER_MANIFEST_LATEST=""
+
+for PLATFORM in $PLATFORMS;
+do
+  echo "=> Loading docker image for $PLATFORM platform ..."
+
+  DOCKER_IMAGE_TMP_FILE="$PWD/image-$PLATFORM.tar.gz"
+  if [ ! -f "$DOCKER_IMAGE_TMP_FILE" ]; then
+    curl -L https://hydra.nixos.org/job/nix/maintenance-$MAINTENANCE_VERSION/dockerImage.$PLATFORM/latest/download/1 > $DOCKER_IMAGE_TMP_FILE
+  fi
+  docker load -i $DOCKER_IMAGE_TMP_FILE
+
+  if   [ "$PLATFORM" = "x86_64-linux" ];  then DOCKER_PLATFORM="amd64"
+  elif [ "$PLATFORM" = "aarch64-linux" ]; then DOCKER_PLATFORM="arm64"
+  else
+    echo "EROROR: No docker platform found for $PLATFORM platform"
+    exit 1
+  fi
+
+  echo "=> Tagging docker image of version $VERSION for $PLATFORM platform ..."
+
+  docker tag nix:$VERSION nixos/nix:$VERSION-$DOCKER_PLATFORM
+  if [ $PUSH_AS_LATEST -eq 1 ]; then
+    echo "=> Tagging docker image of version latest for $PLATFORM platform ..."
+    docker tag nix:$VERSION nixos/nix:latest
+  fi
+
+  echo "=> Pushing docker image of version $VERSION for $PLATFORM platform ..."
+
+  docker push nixos/nix:$VERSION-$DOCKER_PLATFORM
+  if [ $PUSH_AS_LATEST -eq 1 ]; then
+    echo "=> Pushing docker image of version latest for $PLATFORM platform ..."
+    docker push nixos/nix:latest
+  fi
+
+  DOCKER_MANIFEST="$DOCKER_MANIFEST --amend nixos/nix:$VERSION-$DOCKER_PLATFORM"
+  DOCKER_MANIFEST_LATEST="$DOCKER_MANIFEST_LATEST --amend nixos/nix:latest-$DOCKER_PLATFORM"
+
+  echo
+done
+
+echo "=> Creating $VERSION multi platform docker manifest for the following platforms: $PLATFORMS ..."
+docker manifest create nixos/nix:$VERSION $DOCKER_MANIFEST
+if [ $PUSH_AS_LATEST -eq 1 ]; then
+  echo "=> Creating latest multi platform docker manifest for the following platforms: $PLATFORMS ..."
+  docker manifest create nixos/nix:latest $DOCKER_MANIFEST_LATEST
+fi
+
+echo "=> Pushing $VERSION multi platform docker manifest ..."
+docker manifest push nixos/nix:$VERSION
+if [ $PUSH_AS_LATEST -eq 1 ]; then
+  echo "=> Pushing latest multi platform docker manifest ..."
+  docker manifest push nixos/nix:latest
+fi

From 4fc3c4da7ba81a69c17063950933b45b39646949 Mon Sep 17 00:00:00 2001
From: Rok Garbas <rok@garbas.si>
Date: Wed, 26 Jan 2022 10:01:58 +0100
Subject: [PATCH 488/567] typo

---
 maintainers/push-docker.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/maintainers/push-docker.sh b/maintainers/push-docker.sh
index a705f0738..fe8fe174e 100755
--- a/maintainers/push-docker.sh
+++ b/maintainers/push-docker.sh
@@ -37,7 +37,7 @@ do
   docker tag nix:$VERSION nixos/nix:$VERSION-$DOCKER_PLATFORM
   if [ $PUSH_AS_LATEST -eq 1 ]; then
     echo "=> Tagging docker image of version latest for $PLATFORM platform ..."
-    docker tag nix:$VERSION nixos/nix:latest
+    docker tag nix:$VERSION nixos/nix:latest-$DOCKER_PLATFORM
   fi
 
   echo "=> Pushing docker image of version $VERSION for $PLATFORM platform ..."
@@ -45,7 +45,7 @@ do
   docker push nixos/nix:$VERSION-$DOCKER_PLATFORM
   if [ $PUSH_AS_LATEST -eq 1 ]; then
     echo "=> Pushing docker image of version latest for $PLATFORM platform ..."
-    docker push nixos/nix:latest
+    docker push nixos/nix:latest-$DOCKER_PLATFORM
   fi
 
   DOCKER_MANIFEST="$DOCKER_MANIFEST --amend nixos/nix:$VERSION-$DOCKER_PLATFORM"

From 50a9c48db4dddd6ba4c81dae74aa60f8ff10bfe5 Mon Sep 17 00:00:00 2001
From: Rok Garbas <rok@garbas.si>
Date: Wed, 26 Jan 2022 10:05:33 +0100
Subject: [PATCH 489/567] fail early

---
 maintainers/push-docker.sh | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/maintainers/push-docker.sh b/maintainers/push-docker.sh
index fe8fe174e..f9c5a6b18 100755
--- a/maintainers/push-docker.sh
+++ b/maintainers/push-docker.sh
@@ -17,6 +17,13 @@ DOCKER_MANIFEST_LATEST=""
 
 for PLATFORM in $PLATFORMS;
 do
+  if   [ "$PLATFORM" = "x86_64-linux" ];  then DOCKER_PLATFORM="amd64"
+  elif [ "$PLATFORM" = "aarch64-linux" ]; then DOCKER_PLATFORM="arm64"
+  else
+    echo "EROROR: No docker platform found for $PLATFORM platform"
+    exit 1
+  fi
+
   echo "=> Loading docker image for $PLATFORM platform ..."
 
   DOCKER_IMAGE_TMP_FILE="$PWD/image-$PLATFORM.tar.gz"
@@ -25,13 +32,6 @@ do
   fi
   docker load -i $DOCKER_IMAGE_TMP_FILE
 
-  if   [ "$PLATFORM" = "x86_64-linux" ];  then DOCKER_PLATFORM="amd64"
-  elif [ "$PLATFORM" = "aarch64-linux" ]; then DOCKER_PLATFORM="arm64"
-  else
-    echo "EROROR: No docker platform found for $PLATFORM platform"
-    exit 1
-  fi
-
   echo "=> Tagging docker image of version $VERSION for $PLATFORM platform ..."
 
   docker tag nix:$VERSION nixos/nix:$VERSION-$DOCKER_PLATFORM

From d139474f484ef16850e0d6d3f8706c5bd1f352d0 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Wed, 26 Jan 2022 11:01:25 +0100
Subject: [PATCH 490/567] Add some tests for `nix store ping`

Always good to have :)
---
 tests/local.mk      |  1 +
 tests/store-ping.sh | 12 ++++++++++++
 2 files changed, 13 insertions(+)
 create mode 100644 tests/store-ping.sh

diff --git a/tests/local.mk b/tests/local.mk
index 93cf20d43..47d2862a4 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -62,6 +62,7 @@ nix_tests = \
   ca/nix-copy.sh \
   eval-store.sh \
   readfile-context.sh \
+  store-ping.sh \
   why-depends.sh
   # parallel.sh
 
diff --git a/tests/store-ping.sh b/tests/store-ping.sh
new file mode 100644
index 000000000..4e8c8b770
--- /dev/null
+++ b/tests/store-ping.sh
@@ -0,0 +1,12 @@
+source common.sh
+
+STORE_INFO=$(nix store ping 2>&1)
+
+echo "$STORE_INFO" | grep "Store URL: ${NIX_REMOTE}"
+
+if isDaemonNewer "2.7pre20220126"; then
+    echo "$STORE_INFO" | grep "Version: $($NIX_DAEMON_PACKAGE/bin/nix-daemon --version)"
+fi
+
+expect 127 NIX_REMOTE=unix:$PWD/store nix store ping || \
+    fail "nix store ping on a non-existent store should fail"

From 9691f86ff71a6cd1fc0c6337fa326cb49cfb33fc Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 26 Jan 2022 11:41:51 +0100
Subject: [PATCH 491/567] Stop vendoring nlohmann_json

---
 Makefile                  |     1 -
 configure.ac              |     4 +
 flake.nix                 |     1 +
 src/nlohmann/json.hpp     | 25447 ------------------------------------
 src/nlohmann/json_fwd.hpp |    78 -
 src/nlohmann/local.mk     |     2 -
 6 files changed, 5 insertions(+), 25528 deletions(-)
 delete mode 100644 src/nlohmann/json.hpp
 delete mode 100644 src/nlohmann/json_fwd.hpp
 delete mode 100644 src/nlohmann/local.mk

diff --git a/Makefile b/Makefile
index e6ce50cbd..5040d2884 100644
--- a/Makefile
+++ b/Makefile
@@ -10,7 +10,6 @@ makefiles = \
   src/libexpr/local.mk \
   src/libcmd/local.mk \
   src/nix/local.mk \
-  src/nlohmann/local.mk \
   src/resolve-system-dependencies/local.mk \
   scripts/local.mk \
   misc/bash/local.mk \
diff --git a/configure.ac b/configure.ac
index c35065704..01d674879 100644
--- a/configure.ac
+++ b/configure.ac
@@ -262,6 +262,10 @@ fi
 PKG_CHECK_MODULES([GTEST], [gtest_main])
 
 
+# Look for nlohmann/json.
+PKG_CHECK_MODULES([NLOHMANN_JSON], [nlohmann_json >= 3.9])
+
+
 # documentation generation switch
 AC_ARG_ENABLE(doc-gen, AS_HELP_STRING([--disable-doc-gen],[disable documentation generation]),
   doc_generate=$enableval, doc_generate=yes)
diff --git a/flake.nix b/flake.nix
index 39f6074a0..05b38d1dd 100644
--- a/flake.nix
+++ b/flake.nix
@@ -133,6 +133,7 @@
                 ./boehmgc-coroutine-sp-fallback.diff
               ];
             }))
+            nlohmann_json
           ];
 
         perlDeps =
diff --git a/src/nlohmann/json.hpp b/src/nlohmann/json.hpp
deleted file mode 100644
index a70aaf8cb..000000000
--- a/src/nlohmann/json.hpp
+++ /dev/null
@@ -1,25447 +0,0 @@
-/*
-    __ _____ _____ _____
- __|  |   __|     |   | |  JSON for Modern C++
-|  |  |__   |  |  | | | |  version 3.9.1
-|_____|_____|_____|_|___|  https://github.com/nlohmann/json
-
-Licensed under the MIT License <http://opensource.org/licenses/MIT>.
-SPDX-License-Identifier: MIT
-Copyright (c) 2013-2019 Niels Lohmann <http://nlohmann.me>.
-
-Permission is hereby  granted, free of charge, to any  person obtaining a copy
-of this software and associated  documentation files (the "Software"), to deal
-in the Software  without restriction, including without  limitation the rights
-to  use, copy,  modify, merge,  publish, distribute,  sublicense, and/or  sell
-copies  of  the Software,  and  to  permit persons  to  whom  the Software  is
-furnished to do so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
-
-THE SOFTWARE  IS PROVIDED "AS  IS", WITHOUT WARRANTY  OF ANY KIND,  EXPRESS OR
-IMPLIED,  INCLUDING BUT  NOT  LIMITED TO  THE  WARRANTIES OF  MERCHANTABILITY,
-FITNESS FOR  A PARTICULAR PURPOSE AND  NONINFRINGEMENT. IN NO EVENT  SHALL THE
-AUTHORS  OR COPYRIGHT  HOLDERS  BE  LIABLE FOR  ANY  CLAIM,  DAMAGES OR  OTHER
-LIABILITY, WHETHER IN AN ACTION OF  CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE  OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
-*/
-
-#ifndef INCLUDE_NLOHMANN_JSON_HPP_
-#define INCLUDE_NLOHMANN_JSON_HPP_
-
-#define NLOHMANN_JSON_VERSION_MAJOR 3
-#define NLOHMANN_JSON_VERSION_MINOR 9
-#define NLOHMANN_JSON_VERSION_PATCH 1
-
-#include <algorithm> // all_of, find, for_each
-#include <cstddef> // nullptr_t, ptrdiff_t, size_t
-#include <functional> // hash, less
-#include <initializer_list> // initializer_list
-#include <iosfwd> // istream, ostream
-#include <iterator> // random_access_iterator_tag
-#include <memory> // unique_ptr
-#include <numeric> // accumulate
-#include <string> // string, stoi, to_string
-#include <utility> // declval, forward, move, pair, swap
-#include <vector> // vector
-
-// #include <nlohmann/adl_serializer.hpp>
-
-
-#include <utility>
-
-// #include <nlohmann/detail/conversions/from_json.hpp>
-
-
-#include <algorithm> // transform
-#include <array> // array
-#include <forward_list> // forward_list
-#include <iterator> // inserter, front_inserter, end
-#include <map> // map
-#include <string> // string
-#include <tuple> // tuple, make_tuple
-#include <type_traits> // is_arithmetic, is_same, is_enum, underlying_type, is_convertible
-#include <unordered_map> // unordered_map
-#include <utility> // pair, declval
-#include <valarray> // valarray
-
-// #include <nlohmann/detail/exceptions.hpp>
-
-
-#include <exception> // exception
-#include <stdexcept> // runtime_error
-#include <string> // to_string
-
-// #include <nlohmann/detail/input/position_t.hpp>
-
-
-#include <cstddef> // size_t
-
-namespace nlohmann
-{
-namespace detail
-{
-/// struct to capture the start position of the current token
-struct position_t
-{
-    /// the total number of characters read
-    std::size_t chars_read_total = 0;
-    /// the number of characters read in the current line
-    std::size_t chars_read_current_line = 0;
-    /// the number of lines read
-    std::size_t lines_read = 0;
-
-    /// conversion to size_t to preserve SAX interface
-    constexpr operator size_t() const
-    {
-        return chars_read_total;
-    }
-};
-
-} // namespace detail
-} // namespace nlohmann
-
-// #include <nlohmann/detail/macro_scope.hpp>
-
-
-#include <utility> // pair
-// #include <nlohmann/thirdparty/hedley/hedley.hpp>
-/* Hedley - https://nemequ.github.io/hedley
- * Created by Evan Nemerson <evan@nemerson.com>
- *
- * To the extent possible under law, the author(s) have dedicated all
- * copyright and related and neighboring rights to this software to
- * the public domain worldwide. This software is distributed without
- * any warranty.
- *
- * For details, see <http://creativecommons.org/publicdomain/zero/1.0/>.
- * SPDX-License-Identifier: CC0-1.0
- */
-
-#if !defined(JSON_HEDLEY_VERSION) || (JSON_HEDLEY_VERSION < 13)
-#if defined(JSON_HEDLEY_VERSION)
-    #undef JSON_HEDLEY_VERSION
-#endif
-#define JSON_HEDLEY_VERSION 13
-
-#if defined(JSON_HEDLEY_STRINGIFY_EX)
-    #undef JSON_HEDLEY_STRINGIFY_EX
-#endif
-#define JSON_HEDLEY_STRINGIFY_EX(x) #x
-
-#if defined(JSON_HEDLEY_STRINGIFY)
-    #undef JSON_HEDLEY_STRINGIFY
-#endif
-#define JSON_HEDLEY_STRINGIFY(x) JSON_HEDLEY_STRINGIFY_EX(x)
-
-#if defined(JSON_HEDLEY_CONCAT_EX)
-    #undef JSON_HEDLEY_CONCAT_EX
-#endif
-#define JSON_HEDLEY_CONCAT_EX(a,b) a##b
-
-#if defined(JSON_HEDLEY_CONCAT)
-    #undef JSON_HEDLEY_CONCAT
-#endif
-#define JSON_HEDLEY_CONCAT(a,b) JSON_HEDLEY_CONCAT_EX(a,b)
-
-#if defined(JSON_HEDLEY_CONCAT3_EX)
-    #undef JSON_HEDLEY_CONCAT3_EX
-#endif
-#define JSON_HEDLEY_CONCAT3_EX(a,b,c) a##b##c
-
-#if defined(JSON_HEDLEY_CONCAT3)
-    #undef JSON_HEDLEY_CONCAT3
-#endif
-#define JSON_HEDLEY_CONCAT3(a,b,c) JSON_HEDLEY_CONCAT3_EX(a,b,c)
-
-#if defined(JSON_HEDLEY_VERSION_ENCODE)
-    #undef JSON_HEDLEY_VERSION_ENCODE
-#endif
-#define JSON_HEDLEY_VERSION_ENCODE(major,minor,revision) (((major) * 1000000) + ((minor) * 1000) + (revision))
-
-#if defined(JSON_HEDLEY_VERSION_DECODE_MAJOR)
-    #undef JSON_HEDLEY_VERSION_DECODE_MAJOR
-#endif
-#define JSON_HEDLEY_VERSION_DECODE_MAJOR(version) ((version) / 1000000)
-
-#if defined(JSON_HEDLEY_VERSION_DECODE_MINOR)
-    #undef JSON_HEDLEY_VERSION_DECODE_MINOR
-#endif
-#define JSON_HEDLEY_VERSION_DECODE_MINOR(version) (((version) % 1000000) / 1000)
-
-#if defined(JSON_HEDLEY_VERSION_DECODE_REVISION)
-    #undef JSON_HEDLEY_VERSION_DECODE_REVISION
-#endif
-#define JSON_HEDLEY_VERSION_DECODE_REVISION(version) ((version) % 1000)
-
-#if defined(JSON_HEDLEY_GNUC_VERSION)
-    #undef JSON_HEDLEY_GNUC_VERSION
-#endif
-#if defined(__GNUC__) && defined(__GNUC_PATCHLEVEL__)
-    #define JSON_HEDLEY_GNUC_VERSION JSON_HEDLEY_VERSION_ENCODE(__GNUC__, __GNUC_MINOR__, __GNUC_PATCHLEVEL__)
-#elif defined(__GNUC__)
-    #define JSON_HEDLEY_GNUC_VERSION JSON_HEDLEY_VERSION_ENCODE(__GNUC__, __GNUC_MINOR__, 0)
-#endif
-
-#if defined(JSON_HEDLEY_GNUC_VERSION_CHECK)
-    #undef JSON_HEDLEY_GNUC_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_GNUC_VERSION)
-    #define JSON_HEDLEY_GNUC_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_GNUC_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_GNUC_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_MSVC_VERSION)
-    #undef JSON_HEDLEY_MSVC_VERSION
-#endif
-#if defined(_MSC_FULL_VER) && (_MSC_FULL_VER >= 140000000)
-    #define JSON_HEDLEY_MSVC_VERSION JSON_HEDLEY_VERSION_ENCODE(_MSC_FULL_VER / 10000000, (_MSC_FULL_VER % 10000000) / 100000, (_MSC_FULL_VER % 100000) / 100)
-#elif defined(_MSC_FULL_VER)
-    #define JSON_HEDLEY_MSVC_VERSION JSON_HEDLEY_VERSION_ENCODE(_MSC_FULL_VER / 1000000, (_MSC_FULL_VER % 1000000) / 10000, (_MSC_FULL_VER % 10000) / 10)
-#elif defined(_MSC_VER)
-    #define JSON_HEDLEY_MSVC_VERSION JSON_HEDLEY_VERSION_ENCODE(_MSC_VER / 100, _MSC_VER % 100, 0)
-#endif
-
-#if defined(JSON_HEDLEY_MSVC_VERSION_CHECK)
-    #undef JSON_HEDLEY_MSVC_VERSION_CHECK
-#endif
-#if !defined(_MSC_VER)
-    #define JSON_HEDLEY_MSVC_VERSION_CHECK(major,minor,patch) (0)
-#elif defined(_MSC_VER) && (_MSC_VER >= 1400)
-    #define JSON_HEDLEY_MSVC_VERSION_CHECK(major,minor,patch) (_MSC_FULL_VER >= ((major * 10000000) + (minor * 100000) + (patch)))
-#elif defined(_MSC_VER) && (_MSC_VER >= 1200)
-    #define JSON_HEDLEY_MSVC_VERSION_CHECK(major,minor,patch) (_MSC_FULL_VER >= ((major * 1000000) + (minor * 10000) + (patch)))
-#else
-    #define JSON_HEDLEY_MSVC_VERSION_CHECK(major,minor,patch) (_MSC_VER >= ((major * 100) + (minor)))
-#endif
-
-#if defined(JSON_HEDLEY_INTEL_VERSION)
-    #undef JSON_HEDLEY_INTEL_VERSION
-#endif
-#if defined(__INTEL_COMPILER) && defined(__INTEL_COMPILER_UPDATE)
-    #define JSON_HEDLEY_INTEL_VERSION JSON_HEDLEY_VERSION_ENCODE(__INTEL_COMPILER / 100, __INTEL_COMPILER % 100, __INTEL_COMPILER_UPDATE)
-#elif defined(__INTEL_COMPILER)
-    #define JSON_HEDLEY_INTEL_VERSION JSON_HEDLEY_VERSION_ENCODE(__INTEL_COMPILER / 100, __INTEL_COMPILER % 100, 0)
-#endif
-
-#if defined(JSON_HEDLEY_INTEL_VERSION_CHECK)
-    #undef JSON_HEDLEY_INTEL_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_INTEL_VERSION)
-    #define JSON_HEDLEY_INTEL_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_INTEL_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_INTEL_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_PGI_VERSION)
-    #undef JSON_HEDLEY_PGI_VERSION
-#endif
-#if defined(__PGI) && defined(__PGIC__) && defined(__PGIC_MINOR__) && defined(__PGIC_PATCHLEVEL__)
-    #define JSON_HEDLEY_PGI_VERSION JSON_HEDLEY_VERSION_ENCODE(__PGIC__, __PGIC_MINOR__, __PGIC_PATCHLEVEL__)
-#endif
-
-#if defined(JSON_HEDLEY_PGI_VERSION_CHECK)
-    #undef JSON_HEDLEY_PGI_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_PGI_VERSION)
-    #define JSON_HEDLEY_PGI_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_PGI_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_PGI_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_SUNPRO_VERSION)
-    #undef JSON_HEDLEY_SUNPRO_VERSION
-#endif
-#if defined(__SUNPRO_C) && (__SUNPRO_C > 0x1000)
-    #define JSON_HEDLEY_SUNPRO_VERSION JSON_HEDLEY_VERSION_ENCODE((((__SUNPRO_C >> 16) & 0xf) * 10) + ((__SUNPRO_C >> 12) & 0xf), (((__SUNPRO_C >> 8) & 0xf) * 10) + ((__SUNPRO_C >> 4) & 0xf), (__SUNPRO_C & 0xf) * 10)
-#elif defined(__SUNPRO_C)
-    #define JSON_HEDLEY_SUNPRO_VERSION JSON_HEDLEY_VERSION_ENCODE((__SUNPRO_C >> 8) & 0xf, (__SUNPRO_C >> 4) & 0xf, (__SUNPRO_C) & 0xf)
-#elif defined(__SUNPRO_CC) && (__SUNPRO_CC > 0x1000)
-    #define JSON_HEDLEY_SUNPRO_VERSION JSON_HEDLEY_VERSION_ENCODE((((__SUNPRO_CC >> 16) & 0xf) * 10) + ((__SUNPRO_CC >> 12) & 0xf), (((__SUNPRO_CC >> 8) & 0xf) * 10) + ((__SUNPRO_CC >> 4) & 0xf), (__SUNPRO_CC & 0xf) * 10)
-#elif defined(__SUNPRO_CC)
-    #define JSON_HEDLEY_SUNPRO_VERSION JSON_HEDLEY_VERSION_ENCODE((__SUNPRO_CC >> 8) & 0xf, (__SUNPRO_CC >> 4) & 0xf, (__SUNPRO_CC) & 0xf)
-#endif
-
-#if defined(JSON_HEDLEY_SUNPRO_VERSION_CHECK)
-    #undef JSON_HEDLEY_SUNPRO_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_SUNPRO_VERSION)
-    #define JSON_HEDLEY_SUNPRO_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_SUNPRO_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_SUNPRO_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_EMSCRIPTEN_VERSION)
-    #undef JSON_HEDLEY_EMSCRIPTEN_VERSION
-#endif
-#if defined(__EMSCRIPTEN__)
-    #define JSON_HEDLEY_EMSCRIPTEN_VERSION JSON_HEDLEY_VERSION_ENCODE(__EMSCRIPTEN_major__, __EMSCRIPTEN_minor__, __EMSCRIPTEN_tiny__)
-#endif
-
-#if defined(JSON_HEDLEY_EMSCRIPTEN_VERSION_CHECK)
-    #undef JSON_HEDLEY_EMSCRIPTEN_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_EMSCRIPTEN_VERSION)
-    #define JSON_HEDLEY_EMSCRIPTEN_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_EMSCRIPTEN_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_EMSCRIPTEN_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_ARM_VERSION)
-    #undef JSON_HEDLEY_ARM_VERSION
-#endif
-#if defined(__CC_ARM) && defined(__ARMCOMPILER_VERSION)
-    #define JSON_HEDLEY_ARM_VERSION JSON_HEDLEY_VERSION_ENCODE(__ARMCOMPILER_VERSION / 1000000, (__ARMCOMPILER_VERSION % 1000000) / 10000, (__ARMCOMPILER_VERSION % 10000) / 100)
-#elif defined(__CC_ARM) && defined(__ARMCC_VERSION)
-    #define JSON_HEDLEY_ARM_VERSION JSON_HEDLEY_VERSION_ENCODE(__ARMCC_VERSION / 1000000, (__ARMCC_VERSION % 1000000) / 10000, (__ARMCC_VERSION % 10000) / 100)
-#endif
-
-#if defined(JSON_HEDLEY_ARM_VERSION_CHECK)
-    #undef JSON_HEDLEY_ARM_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_ARM_VERSION)
-    #define JSON_HEDLEY_ARM_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_ARM_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_ARM_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_IBM_VERSION)
-    #undef JSON_HEDLEY_IBM_VERSION
-#endif
-#if defined(__ibmxl__)
-    #define JSON_HEDLEY_IBM_VERSION JSON_HEDLEY_VERSION_ENCODE(__ibmxl_version__, __ibmxl_release__, __ibmxl_modification__)
-#elif defined(__xlC__) && defined(__xlC_ver__)
-    #define JSON_HEDLEY_IBM_VERSION JSON_HEDLEY_VERSION_ENCODE(__xlC__ >> 8, __xlC__ & 0xff, (__xlC_ver__ >> 8) & 0xff)
-#elif defined(__xlC__)
-    #define JSON_HEDLEY_IBM_VERSION JSON_HEDLEY_VERSION_ENCODE(__xlC__ >> 8, __xlC__ & 0xff, 0)
-#endif
-
-#if defined(JSON_HEDLEY_IBM_VERSION_CHECK)
-    #undef JSON_HEDLEY_IBM_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_IBM_VERSION)
-    #define JSON_HEDLEY_IBM_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_IBM_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_IBM_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_TI_VERSION)
-    #undef JSON_HEDLEY_TI_VERSION
-#endif
-#if \
-    defined(__TI_COMPILER_VERSION__) && \
-    ( \
-      defined(__TMS470__) || defined(__TI_ARM__) || \
-      defined(__MSP430__) || \
-      defined(__TMS320C2000__) \
-    )
-#if (__TI_COMPILER_VERSION__ >= 16000000)
-    #define JSON_HEDLEY_TI_VERSION JSON_HEDLEY_VERSION_ENCODE(__TI_COMPILER_VERSION__ / 1000000, (__TI_COMPILER_VERSION__ % 1000000) / 1000, (__TI_COMPILER_VERSION__ % 1000))
-#endif
-#endif
-
-#if defined(JSON_HEDLEY_TI_VERSION_CHECK)
-    #undef JSON_HEDLEY_TI_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_TI_VERSION)
-    #define JSON_HEDLEY_TI_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_TI_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_TI_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_TI_CL2000_VERSION)
-    #undef JSON_HEDLEY_TI_CL2000_VERSION
-#endif
-#if defined(__TI_COMPILER_VERSION__) && defined(__TMS320C2000__)
-    #define JSON_HEDLEY_TI_CL2000_VERSION JSON_HEDLEY_VERSION_ENCODE(__TI_COMPILER_VERSION__ / 1000000, (__TI_COMPILER_VERSION__ % 1000000) / 1000, (__TI_COMPILER_VERSION__ % 1000))
-#endif
-
-#if defined(JSON_HEDLEY_TI_CL2000_VERSION_CHECK)
-    #undef JSON_HEDLEY_TI_CL2000_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_TI_CL2000_VERSION)
-    #define JSON_HEDLEY_TI_CL2000_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_TI_CL2000_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_TI_CL2000_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_TI_CL430_VERSION)
-    #undef JSON_HEDLEY_TI_CL430_VERSION
-#endif
-#if defined(__TI_COMPILER_VERSION__) && defined(__MSP430__)
-    #define JSON_HEDLEY_TI_CL430_VERSION JSON_HEDLEY_VERSION_ENCODE(__TI_COMPILER_VERSION__ / 1000000, (__TI_COMPILER_VERSION__ % 1000000) / 1000, (__TI_COMPILER_VERSION__ % 1000))
-#endif
-
-#if defined(JSON_HEDLEY_TI_CL430_VERSION_CHECK)
-    #undef JSON_HEDLEY_TI_CL430_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_TI_CL430_VERSION)
-    #define JSON_HEDLEY_TI_CL430_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_TI_CL430_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_TI_CL430_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_TI_ARMCL_VERSION)
-    #undef JSON_HEDLEY_TI_ARMCL_VERSION
-#endif
-#if defined(__TI_COMPILER_VERSION__) && (defined(__TMS470__) || defined(__TI_ARM__))
-    #define JSON_HEDLEY_TI_ARMCL_VERSION JSON_HEDLEY_VERSION_ENCODE(__TI_COMPILER_VERSION__ / 1000000, (__TI_COMPILER_VERSION__ % 1000000) / 1000, (__TI_COMPILER_VERSION__ % 1000))
-#endif
-
-#if defined(JSON_HEDLEY_TI_ARMCL_VERSION_CHECK)
-    #undef JSON_HEDLEY_TI_ARMCL_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_TI_ARMCL_VERSION)
-    #define JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_TI_ARMCL_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_TI_CL6X_VERSION)
-    #undef JSON_HEDLEY_TI_CL6X_VERSION
-#endif
-#if defined(__TI_COMPILER_VERSION__) && defined(__TMS320C6X__)
-    #define JSON_HEDLEY_TI_CL6X_VERSION JSON_HEDLEY_VERSION_ENCODE(__TI_COMPILER_VERSION__ / 1000000, (__TI_COMPILER_VERSION__ % 1000000) / 1000, (__TI_COMPILER_VERSION__ % 1000))
-#endif
-
-#if defined(JSON_HEDLEY_TI_CL6X_VERSION_CHECK)
-    #undef JSON_HEDLEY_TI_CL6X_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_TI_CL6X_VERSION)
-    #define JSON_HEDLEY_TI_CL6X_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_TI_CL6X_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_TI_CL6X_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_TI_CL7X_VERSION)
-    #undef JSON_HEDLEY_TI_CL7X_VERSION
-#endif
-#if defined(__TI_COMPILER_VERSION__) && defined(__C7000__)
-    #define JSON_HEDLEY_TI_CL7X_VERSION JSON_HEDLEY_VERSION_ENCODE(__TI_COMPILER_VERSION__ / 1000000, (__TI_COMPILER_VERSION__ % 1000000) / 1000, (__TI_COMPILER_VERSION__ % 1000))
-#endif
-
-#if defined(JSON_HEDLEY_TI_CL7X_VERSION_CHECK)
-    #undef JSON_HEDLEY_TI_CL7X_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_TI_CL7X_VERSION)
-    #define JSON_HEDLEY_TI_CL7X_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_TI_CL7X_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_TI_CL7X_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_TI_CLPRU_VERSION)
-    #undef JSON_HEDLEY_TI_CLPRU_VERSION
-#endif
-#if defined(__TI_COMPILER_VERSION__) && defined(__PRU__)
-    #define JSON_HEDLEY_TI_CLPRU_VERSION JSON_HEDLEY_VERSION_ENCODE(__TI_COMPILER_VERSION__ / 1000000, (__TI_COMPILER_VERSION__ % 1000000) / 1000, (__TI_COMPILER_VERSION__ % 1000))
-#endif
-
-#if defined(JSON_HEDLEY_TI_CLPRU_VERSION_CHECK)
-    #undef JSON_HEDLEY_TI_CLPRU_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_TI_CLPRU_VERSION)
-    #define JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_TI_CLPRU_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_CRAY_VERSION)
-    #undef JSON_HEDLEY_CRAY_VERSION
-#endif
-#if defined(_CRAYC)
-    #if defined(_RELEASE_PATCHLEVEL)
-        #define JSON_HEDLEY_CRAY_VERSION JSON_HEDLEY_VERSION_ENCODE(_RELEASE_MAJOR, _RELEASE_MINOR, _RELEASE_PATCHLEVEL)
-    #else
-        #define JSON_HEDLEY_CRAY_VERSION JSON_HEDLEY_VERSION_ENCODE(_RELEASE_MAJOR, _RELEASE_MINOR, 0)
-    #endif
-#endif
-
-#if defined(JSON_HEDLEY_CRAY_VERSION_CHECK)
-    #undef JSON_HEDLEY_CRAY_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_CRAY_VERSION)
-    #define JSON_HEDLEY_CRAY_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_CRAY_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_CRAY_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_IAR_VERSION)
-    #undef JSON_HEDLEY_IAR_VERSION
-#endif
-#if defined(__IAR_SYSTEMS_ICC__)
-    #if __VER__ > 1000
-        #define JSON_HEDLEY_IAR_VERSION JSON_HEDLEY_VERSION_ENCODE((__VER__ / 1000000), ((__VER__ / 1000) % 1000), (__VER__ % 1000))
-    #else
-        #define JSON_HEDLEY_IAR_VERSION JSON_HEDLEY_VERSION_ENCODE(VER / 100, __VER__ % 100, 0)
-    #endif
-#endif
-
-#if defined(JSON_HEDLEY_IAR_VERSION_CHECK)
-    #undef JSON_HEDLEY_IAR_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_IAR_VERSION)
-    #define JSON_HEDLEY_IAR_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_IAR_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_IAR_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_TINYC_VERSION)
-    #undef JSON_HEDLEY_TINYC_VERSION
-#endif
-#if defined(__TINYC__)
-    #define JSON_HEDLEY_TINYC_VERSION JSON_HEDLEY_VERSION_ENCODE(__TINYC__ / 1000, (__TINYC__ / 100) % 10, __TINYC__ % 100)
-#endif
-
-#if defined(JSON_HEDLEY_TINYC_VERSION_CHECK)
-    #undef JSON_HEDLEY_TINYC_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_TINYC_VERSION)
-    #define JSON_HEDLEY_TINYC_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_TINYC_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_TINYC_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_DMC_VERSION)
-    #undef JSON_HEDLEY_DMC_VERSION
-#endif
-#if defined(__DMC__)
-    #define JSON_HEDLEY_DMC_VERSION JSON_HEDLEY_VERSION_ENCODE(__DMC__ >> 8, (__DMC__ >> 4) & 0xf, __DMC__ & 0xf)
-#endif
-
-#if defined(JSON_HEDLEY_DMC_VERSION_CHECK)
-    #undef JSON_HEDLEY_DMC_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_DMC_VERSION)
-    #define JSON_HEDLEY_DMC_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_DMC_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_DMC_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_COMPCERT_VERSION)
-    #undef JSON_HEDLEY_COMPCERT_VERSION
-#endif
-#if defined(__COMPCERT_VERSION__)
-    #define JSON_HEDLEY_COMPCERT_VERSION JSON_HEDLEY_VERSION_ENCODE(__COMPCERT_VERSION__ / 10000, (__COMPCERT_VERSION__ / 100) % 100, __COMPCERT_VERSION__ % 100)
-#endif
-
-#if defined(JSON_HEDLEY_COMPCERT_VERSION_CHECK)
-    #undef JSON_HEDLEY_COMPCERT_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_COMPCERT_VERSION)
-    #define JSON_HEDLEY_COMPCERT_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_COMPCERT_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_COMPCERT_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_PELLES_VERSION)
-    #undef JSON_HEDLEY_PELLES_VERSION
-#endif
-#if defined(__POCC__)
-    #define JSON_HEDLEY_PELLES_VERSION JSON_HEDLEY_VERSION_ENCODE(__POCC__ / 100, __POCC__ % 100, 0)
-#endif
-
-#if defined(JSON_HEDLEY_PELLES_VERSION_CHECK)
-    #undef JSON_HEDLEY_PELLES_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_PELLES_VERSION)
-    #define JSON_HEDLEY_PELLES_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_PELLES_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_PELLES_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_GCC_VERSION)
-    #undef JSON_HEDLEY_GCC_VERSION
-#endif
-#if \
-    defined(JSON_HEDLEY_GNUC_VERSION) && \
-    !defined(__clang__) && \
-    !defined(JSON_HEDLEY_INTEL_VERSION) && \
-    !defined(JSON_HEDLEY_PGI_VERSION) && \
-    !defined(JSON_HEDLEY_ARM_VERSION) && \
-    !defined(JSON_HEDLEY_TI_VERSION) && \
-    !defined(JSON_HEDLEY_TI_ARMCL_VERSION) && \
-    !defined(JSON_HEDLEY_TI_CL430_VERSION) && \
-    !defined(JSON_HEDLEY_TI_CL2000_VERSION) && \
-    !defined(JSON_HEDLEY_TI_CL6X_VERSION) && \
-    !defined(JSON_HEDLEY_TI_CL7X_VERSION) && \
-    !defined(JSON_HEDLEY_TI_CLPRU_VERSION) && \
-    !defined(__COMPCERT__)
-    #define JSON_HEDLEY_GCC_VERSION JSON_HEDLEY_GNUC_VERSION
-#endif
-
-#if defined(JSON_HEDLEY_GCC_VERSION_CHECK)
-    #undef JSON_HEDLEY_GCC_VERSION_CHECK
-#endif
-#if defined(JSON_HEDLEY_GCC_VERSION)
-    #define JSON_HEDLEY_GCC_VERSION_CHECK(major,minor,patch) (JSON_HEDLEY_GCC_VERSION >= JSON_HEDLEY_VERSION_ENCODE(major, minor, patch))
-#else
-    #define JSON_HEDLEY_GCC_VERSION_CHECK(major,minor,patch) (0)
-#endif
-
-#if defined(JSON_HEDLEY_HAS_ATTRIBUTE)
-    #undef JSON_HEDLEY_HAS_ATTRIBUTE
-#endif
-#if defined(__has_attribute)
-    #define JSON_HEDLEY_HAS_ATTRIBUTE(attribute) __has_attribute(attribute)
-#else
-    #define JSON_HEDLEY_HAS_ATTRIBUTE(attribute) (0)
-#endif
-
-#if defined(JSON_HEDLEY_GNUC_HAS_ATTRIBUTE)
-    #undef JSON_HEDLEY_GNUC_HAS_ATTRIBUTE
-#endif
-#if defined(__has_attribute)
-    #define JSON_HEDLEY_GNUC_HAS_ATTRIBUTE(attribute,major,minor,patch) __has_attribute(attribute)
-#else
-    #define JSON_HEDLEY_GNUC_HAS_ATTRIBUTE(attribute,major,minor,patch) JSON_HEDLEY_GNUC_VERSION_CHECK(major,minor,patch)
-#endif
-
-#if defined(JSON_HEDLEY_GCC_HAS_ATTRIBUTE)
-    #undef JSON_HEDLEY_GCC_HAS_ATTRIBUTE
-#endif
-#if defined(__has_attribute)
-    #define JSON_HEDLEY_GCC_HAS_ATTRIBUTE(attribute,major,minor,patch) __has_attribute(attribute)
-#else
-    #define JSON_HEDLEY_GCC_HAS_ATTRIBUTE(attribute,major,minor,patch) JSON_HEDLEY_GCC_VERSION_CHECK(major,minor,patch)
-#endif
-
-#if defined(JSON_HEDLEY_HAS_CPP_ATTRIBUTE)
-    #undef JSON_HEDLEY_HAS_CPP_ATTRIBUTE
-#endif
-#if \
-    defined(__has_cpp_attribute) && \
-    defined(__cplusplus) && \
-    (!defined(JSON_HEDLEY_SUNPRO_VERSION) || JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,15,0))
-    #define JSON_HEDLEY_HAS_CPP_ATTRIBUTE(attribute) __has_cpp_attribute(attribute)
-#else
-    #define JSON_HEDLEY_HAS_CPP_ATTRIBUTE(attribute) (0)
-#endif
-
-#if defined(JSON_HEDLEY_HAS_CPP_ATTRIBUTE_NS)
-    #undef JSON_HEDLEY_HAS_CPP_ATTRIBUTE_NS
-#endif
-#if !defined(__cplusplus) || !defined(__has_cpp_attribute)
-    #define JSON_HEDLEY_HAS_CPP_ATTRIBUTE_NS(ns,attribute) (0)
-#elif \
-    !defined(JSON_HEDLEY_PGI_VERSION) && \
-    !defined(JSON_HEDLEY_IAR_VERSION) && \
-    (!defined(JSON_HEDLEY_SUNPRO_VERSION) || JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,15,0)) && \
-    (!defined(JSON_HEDLEY_MSVC_VERSION) || JSON_HEDLEY_MSVC_VERSION_CHECK(19,20,0))
-    #define JSON_HEDLEY_HAS_CPP_ATTRIBUTE_NS(ns,attribute) JSON_HEDLEY_HAS_CPP_ATTRIBUTE(ns::attribute)
-#else
-    #define JSON_HEDLEY_HAS_CPP_ATTRIBUTE_NS(ns,attribute) (0)
-#endif
-
-#if defined(JSON_HEDLEY_GNUC_HAS_CPP_ATTRIBUTE)
-    #undef JSON_HEDLEY_GNUC_HAS_CPP_ATTRIBUTE
-#endif
-#if defined(__has_cpp_attribute) && defined(__cplusplus)
-    #define JSON_HEDLEY_GNUC_HAS_CPP_ATTRIBUTE(attribute,major,minor,patch) __has_cpp_attribute(attribute)
-#else
-    #define JSON_HEDLEY_GNUC_HAS_CPP_ATTRIBUTE(attribute,major,minor,patch) JSON_HEDLEY_GNUC_VERSION_CHECK(major,minor,patch)
-#endif
-
-#if defined(JSON_HEDLEY_GCC_HAS_CPP_ATTRIBUTE)
-    #undef JSON_HEDLEY_GCC_HAS_CPP_ATTRIBUTE
-#endif
-#if defined(__has_cpp_attribute) && defined(__cplusplus)
-    #define JSON_HEDLEY_GCC_HAS_CPP_ATTRIBUTE(attribute,major,minor,patch) __has_cpp_attribute(attribute)
-#else
-    #define JSON_HEDLEY_GCC_HAS_CPP_ATTRIBUTE(attribute,major,minor,patch) JSON_HEDLEY_GCC_VERSION_CHECK(major,minor,patch)
-#endif
-
-#if defined(JSON_HEDLEY_HAS_BUILTIN)
-    #undef JSON_HEDLEY_HAS_BUILTIN
-#endif
-#if defined(__has_builtin)
-    #define JSON_HEDLEY_HAS_BUILTIN(builtin) __has_builtin(builtin)
-#else
-    #define JSON_HEDLEY_HAS_BUILTIN(builtin) (0)
-#endif
-
-#if defined(JSON_HEDLEY_GNUC_HAS_BUILTIN)
-    #undef JSON_HEDLEY_GNUC_HAS_BUILTIN
-#endif
-#if defined(__has_builtin)
-    #define JSON_HEDLEY_GNUC_HAS_BUILTIN(builtin,major,minor,patch) __has_builtin(builtin)
-#else
-    #define JSON_HEDLEY_GNUC_HAS_BUILTIN(builtin,major,minor,patch) JSON_HEDLEY_GNUC_VERSION_CHECK(major,minor,patch)
-#endif
-
-#if defined(JSON_HEDLEY_GCC_HAS_BUILTIN)
-    #undef JSON_HEDLEY_GCC_HAS_BUILTIN
-#endif
-#if defined(__has_builtin)
-    #define JSON_HEDLEY_GCC_HAS_BUILTIN(builtin,major,minor,patch) __has_builtin(builtin)
-#else
-    #define JSON_HEDLEY_GCC_HAS_BUILTIN(builtin,major,minor,patch) JSON_HEDLEY_GCC_VERSION_CHECK(major,minor,patch)
-#endif
-
-#if defined(JSON_HEDLEY_HAS_FEATURE)
-    #undef JSON_HEDLEY_HAS_FEATURE
-#endif
-#if defined(__has_feature)
-    #define JSON_HEDLEY_HAS_FEATURE(feature) __has_feature(feature)
-#else
-    #define JSON_HEDLEY_HAS_FEATURE(feature) (0)
-#endif
-
-#if defined(JSON_HEDLEY_GNUC_HAS_FEATURE)
-    #undef JSON_HEDLEY_GNUC_HAS_FEATURE
-#endif
-#if defined(__has_feature)
-    #define JSON_HEDLEY_GNUC_HAS_FEATURE(feature,major,minor,patch) __has_feature(feature)
-#else
-    #define JSON_HEDLEY_GNUC_HAS_FEATURE(feature,major,minor,patch) JSON_HEDLEY_GNUC_VERSION_CHECK(major,minor,patch)
-#endif
-
-#if defined(JSON_HEDLEY_GCC_HAS_FEATURE)
-    #undef JSON_HEDLEY_GCC_HAS_FEATURE
-#endif
-#if defined(__has_feature)
-    #define JSON_HEDLEY_GCC_HAS_FEATURE(feature,major,minor,patch) __has_feature(feature)
-#else
-    #define JSON_HEDLEY_GCC_HAS_FEATURE(feature,major,minor,patch) JSON_HEDLEY_GCC_VERSION_CHECK(major,minor,patch)
-#endif
-
-#if defined(JSON_HEDLEY_HAS_EXTENSION)
-    #undef JSON_HEDLEY_HAS_EXTENSION
-#endif
-#if defined(__has_extension)
-    #define JSON_HEDLEY_HAS_EXTENSION(extension) __has_extension(extension)
-#else
-    #define JSON_HEDLEY_HAS_EXTENSION(extension) (0)
-#endif
-
-#if defined(JSON_HEDLEY_GNUC_HAS_EXTENSION)
-    #undef JSON_HEDLEY_GNUC_HAS_EXTENSION
-#endif
-#if defined(__has_extension)
-    #define JSON_HEDLEY_GNUC_HAS_EXTENSION(extension,major,minor,patch) __has_extension(extension)
-#else
-    #define JSON_HEDLEY_GNUC_HAS_EXTENSION(extension,major,minor,patch) JSON_HEDLEY_GNUC_VERSION_CHECK(major,minor,patch)
-#endif
-
-#if defined(JSON_HEDLEY_GCC_HAS_EXTENSION)
-    #undef JSON_HEDLEY_GCC_HAS_EXTENSION
-#endif
-#if defined(__has_extension)
-    #define JSON_HEDLEY_GCC_HAS_EXTENSION(extension,major,minor,patch) __has_extension(extension)
-#else
-    #define JSON_HEDLEY_GCC_HAS_EXTENSION(extension,major,minor,patch) JSON_HEDLEY_GCC_VERSION_CHECK(major,minor,patch)
-#endif
-
-#if defined(JSON_HEDLEY_HAS_DECLSPEC_ATTRIBUTE)
-    #undef JSON_HEDLEY_HAS_DECLSPEC_ATTRIBUTE
-#endif
-#if defined(__has_declspec_attribute)
-    #define JSON_HEDLEY_HAS_DECLSPEC_ATTRIBUTE(attribute) __has_declspec_attribute(attribute)
-#else
-    #define JSON_HEDLEY_HAS_DECLSPEC_ATTRIBUTE(attribute) (0)
-#endif
-
-#if defined(JSON_HEDLEY_GNUC_HAS_DECLSPEC_ATTRIBUTE)
-    #undef JSON_HEDLEY_GNUC_HAS_DECLSPEC_ATTRIBUTE
-#endif
-#if defined(__has_declspec_attribute)
-    #define JSON_HEDLEY_GNUC_HAS_DECLSPEC_ATTRIBUTE(attribute,major,minor,patch) __has_declspec_attribute(attribute)
-#else
-    #define JSON_HEDLEY_GNUC_HAS_DECLSPEC_ATTRIBUTE(attribute,major,minor,patch) JSON_HEDLEY_GNUC_VERSION_CHECK(major,minor,patch)
-#endif
-
-#if defined(JSON_HEDLEY_GCC_HAS_DECLSPEC_ATTRIBUTE)
-    #undef JSON_HEDLEY_GCC_HAS_DECLSPEC_ATTRIBUTE
-#endif
-#if defined(__has_declspec_attribute)
-    #define JSON_HEDLEY_GCC_HAS_DECLSPEC_ATTRIBUTE(attribute,major,minor,patch) __has_declspec_attribute(attribute)
-#else
-    #define JSON_HEDLEY_GCC_HAS_DECLSPEC_ATTRIBUTE(attribute,major,minor,patch) JSON_HEDLEY_GCC_VERSION_CHECK(major,minor,patch)
-#endif
-
-#if defined(JSON_HEDLEY_HAS_WARNING)
-    #undef JSON_HEDLEY_HAS_WARNING
-#endif
-#if defined(__has_warning)
-    #define JSON_HEDLEY_HAS_WARNING(warning) __has_warning(warning)
-#else
-    #define JSON_HEDLEY_HAS_WARNING(warning) (0)
-#endif
-
-#if defined(JSON_HEDLEY_GNUC_HAS_WARNING)
-    #undef JSON_HEDLEY_GNUC_HAS_WARNING
-#endif
-#if defined(__has_warning)
-    #define JSON_HEDLEY_GNUC_HAS_WARNING(warning,major,minor,patch) __has_warning(warning)
-#else
-    #define JSON_HEDLEY_GNUC_HAS_WARNING(warning,major,minor,patch) JSON_HEDLEY_GNUC_VERSION_CHECK(major,minor,patch)
-#endif
-
-#if defined(JSON_HEDLEY_GCC_HAS_WARNING)
-    #undef JSON_HEDLEY_GCC_HAS_WARNING
-#endif
-#if defined(__has_warning)
-    #define JSON_HEDLEY_GCC_HAS_WARNING(warning,major,minor,patch) __has_warning(warning)
-#else
-    #define JSON_HEDLEY_GCC_HAS_WARNING(warning,major,minor,patch) JSON_HEDLEY_GCC_VERSION_CHECK(major,minor,patch)
-#endif
-
-/* JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_ is for
-   HEDLEY INTERNAL USE ONLY.  API subject to change without notice. */
-#if defined(JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_)
-    #undef JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_
-#endif
-#if defined(__cplusplus)
-#  if JSON_HEDLEY_HAS_WARNING("-Wc++98-compat")
-#    if JSON_HEDLEY_HAS_WARNING("-Wc++17-extensions")
-#      define JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_(xpr) \
-    JSON_HEDLEY_DIAGNOSTIC_PUSH \
-    _Pragma("clang diagnostic ignored \"-Wc++98-compat\"") \
-    _Pragma("clang diagnostic ignored \"-Wc++17-extensions\"") \
-    xpr \
-    JSON_HEDLEY_DIAGNOSTIC_POP
-#    else
-#      define JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_(xpr) \
-    JSON_HEDLEY_DIAGNOSTIC_PUSH \
-    _Pragma("clang diagnostic ignored \"-Wc++98-compat\"") \
-    xpr \
-    JSON_HEDLEY_DIAGNOSTIC_POP
-#    endif
-#  endif
-#endif
-#if !defined(JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_(x) x
-#endif
-
-#if defined(JSON_HEDLEY_CONST_CAST)
-    #undef JSON_HEDLEY_CONST_CAST
-#endif
-#if defined(__cplusplus)
-#  define JSON_HEDLEY_CONST_CAST(T, expr) (const_cast<T>(expr))
-#elif \
-  JSON_HEDLEY_HAS_WARNING("-Wcast-qual") || \
-  JSON_HEDLEY_GCC_VERSION_CHECK(4,6,0) || \
-  JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0)
-#  define JSON_HEDLEY_CONST_CAST(T, expr) (__extension__ ({ \
-        JSON_HEDLEY_DIAGNOSTIC_PUSH \
-        JSON_HEDLEY_DIAGNOSTIC_DISABLE_CAST_QUAL \
-        ((T) (expr)); \
-        JSON_HEDLEY_DIAGNOSTIC_POP \
-    }))
-#else
-#  define JSON_HEDLEY_CONST_CAST(T, expr) ((T) (expr))
-#endif
-
-#if defined(JSON_HEDLEY_REINTERPRET_CAST)
-    #undef JSON_HEDLEY_REINTERPRET_CAST
-#endif
-#if defined(__cplusplus)
-    #define JSON_HEDLEY_REINTERPRET_CAST(T, expr) (reinterpret_cast<T>(expr))
-#else
-    #define JSON_HEDLEY_REINTERPRET_CAST(T, expr) ((T) (expr))
-#endif
-
-#if defined(JSON_HEDLEY_STATIC_CAST)
-    #undef JSON_HEDLEY_STATIC_CAST
-#endif
-#if defined(__cplusplus)
-    #define JSON_HEDLEY_STATIC_CAST(T, expr) (static_cast<T>(expr))
-#else
-    #define JSON_HEDLEY_STATIC_CAST(T, expr) ((T) (expr))
-#endif
-
-#if defined(JSON_HEDLEY_CPP_CAST)
-    #undef JSON_HEDLEY_CPP_CAST
-#endif
-#if defined(__cplusplus)
-#  if JSON_HEDLEY_HAS_WARNING("-Wold-style-cast")
-#    define JSON_HEDLEY_CPP_CAST(T, expr) \
-    JSON_HEDLEY_DIAGNOSTIC_PUSH \
-    _Pragma("clang diagnostic ignored \"-Wold-style-cast\"") \
-    ((T) (expr)) \
-    JSON_HEDLEY_DIAGNOSTIC_POP
-#  elif JSON_HEDLEY_IAR_VERSION_CHECK(8,3,0)
-#    define JSON_HEDLEY_CPP_CAST(T, expr) \
-    JSON_HEDLEY_DIAGNOSTIC_PUSH \
-    _Pragma("diag_suppress=Pe137") \
-    JSON_HEDLEY_DIAGNOSTIC_POP \
-#  else
-#    define JSON_HEDLEY_CPP_CAST(T, expr) ((T) (expr))
-#  endif
-#else
-#  define JSON_HEDLEY_CPP_CAST(T, expr) (expr)
-#endif
-
-#if \
-    (defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)) || \
-    defined(__clang__) || \
-    JSON_HEDLEY_GCC_VERSION_CHECK(3,0,0) || \
-    JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0) || \
-    JSON_HEDLEY_IAR_VERSION_CHECK(8,0,0) || \
-    JSON_HEDLEY_PGI_VERSION_CHECK(18,4,0) || \
-    JSON_HEDLEY_ARM_VERSION_CHECK(4,1,0) || \
-    JSON_HEDLEY_TI_VERSION_CHECK(15,12,0) || \
-    JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(4,7,0) || \
-    JSON_HEDLEY_TI_CL430_VERSION_CHECK(2,0,1) || \
-    JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,1,0) || \
-    JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,0,0) || \
-    JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) || \
-    JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(2,1,0) || \
-    JSON_HEDLEY_CRAY_VERSION_CHECK(5,0,0) || \
-    JSON_HEDLEY_TINYC_VERSION_CHECK(0,9,17) || \
-    JSON_HEDLEY_SUNPRO_VERSION_CHECK(8,0,0) || \
-    (JSON_HEDLEY_IBM_VERSION_CHECK(10,1,0) && defined(__C99_PRAGMA_OPERATOR))
-    #define JSON_HEDLEY_PRAGMA(value) _Pragma(#value)
-#elif JSON_HEDLEY_MSVC_VERSION_CHECK(15,0,0)
-    #define JSON_HEDLEY_PRAGMA(value) __pragma(value)
-#else
-    #define JSON_HEDLEY_PRAGMA(value)
-#endif
-
-#if defined(JSON_HEDLEY_DIAGNOSTIC_PUSH)
-    #undef JSON_HEDLEY_DIAGNOSTIC_PUSH
-#endif
-#if defined(JSON_HEDLEY_DIAGNOSTIC_POP)
-    #undef JSON_HEDLEY_DIAGNOSTIC_POP
-#endif
-#if defined(__clang__)
-    #define JSON_HEDLEY_DIAGNOSTIC_PUSH _Pragma("clang diagnostic push")
-    #define JSON_HEDLEY_DIAGNOSTIC_POP _Pragma("clang diagnostic pop")
-#elif JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_PUSH _Pragma("warning(push)")
-    #define JSON_HEDLEY_DIAGNOSTIC_POP _Pragma("warning(pop)")
-#elif JSON_HEDLEY_GCC_VERSION_CHECK(4,6,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_PUSH _Pragma("GCC diagnostic push")
-    #define JSON_HEDLEY_DIAGNOSTIC_POP _Pragma("GCC diagnostic pop")
-#elif JSON_HEDLEY_MSVC_VERSION_CHECK(15,0,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_PUSH __pragma(warning(push))
-    #define JSON_HEDLEY_DIAGNOSTIC_POP __pragma(warning(pop))
-#elif JSON_HEDLEY_ARM_VERSION_CHECK(5,6,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_PUSH _Pragma("push")
-    #define JSON_HEDLEY_DIAGNOSTIC_POP _Pragma("pop")
-#elif \
-    JSON_HEDLEY_TI_VERSION_CHECK(15,12,0) || \
-    JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(5,2,0) || \
-    JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,4,0) || \
-    JSON_HEDLEY_TI_CL6X_VERSION_CHECK(8,1,0) || \
-    JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) || \
-    JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(2,1,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_PUSH _Pragma("diag_push")
-    #define JSON_HEDLEY_DIAGNOSTIC_POP _Pragma("diag_pop")
-#elif JSON_HEDLEY_PELLES_VERSION_CHECK(2,90,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_PUSH _Pragma("warning(push)")
-    #define JSON_HEDLEY_DIAGNOSTIC_POP _Pragma("warning(pop)")
-#else
-    #define JSON_HEDLEY_DIAGNOSTIC_PUSH
-    #define JSON_HEDLEY_DIAGNOSTIC_POP
-#endif
-
-#if defined(JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED)
-    #undef JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED
-#endif
-#if JSON_HEDLEY_HAS_WARNING("-Wdeprecated-declarations")
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED _Pragma("clang diagnostic ignored \"-Wdeprecated-declarations\"")
-#elif JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED _Pragma("warning(disable:1478 1786)")
-#elif JSON_HEDLEY_PGI_VERSION_CHECK(17,10,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED _Pragma("diag_suppress 1215,1444")
-#elif JSON_HEDLEY_GCC_VERSION_CHECK(4,3,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED _Pragma("GCC diagnostic ignored \"-Wdeprecated-declarations\"")
-#elif JSON_HEDLEY_MSVC_VERSION_CHECK(15,0,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED __pragma(warning(disable:4996))
-#elif \
-    JSON_HEDLEY_TI_VERSION_CHECK(15,12,0) || \
-    (JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(4,8,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(5,2,0) || \
-    (JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,4,0) || \
-    (JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,3,0) || \
-    (JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,2,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,5,0) || \
-    JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) || \
-    JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(2,1,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED _Pragma("diag_suppress 1291,1718")
-#elif JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,13,0) && !defined(__cplusplus)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED _Pragma("error_messages(off,E_DEPRECATED_ATT,E_DEPRECATED_ATT_MESS)")
-#elif JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,13,0) && defined(__cplusplus)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED _Pragma("error_messages(off,symdeprecated,symdeprecated2)")
-#elif JSON_HEDLEY_IAR_VERSION_CHECK(8,0,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED _Pragma("diag_suppress=Pe1444,Pe1215")
-#elif JSON_HEDLEY_PELLES_VERSION_CHECK(2,90,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED _Pragma("warn(disable:2241)")
-#else
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED
-#endif
-
-#if defined(JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS)
-    #undef JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS
-#endif
-#if JSON_HEDLEY_HAS_WARNING("-Wunknown-pragmas")
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS _Pragma("clang diagnostic ignored \"-Wunknown-pragmas\"")
-#elif JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS _Pragma("warning(disable:161)")
-#elif JSON_HEDLEY_PGI_VERSION_CHECK(17,10,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS _Pragma("diag_suppress 1675")
-#elif JSON_HEDLEY_GCC_VERSION_CHECK(4,3,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS _Pragma("GCC diagnostic ignored \"-Wunknown-pragmas\"")
-#elif JSON_HEDLEY_MSVC_VERSION_CHECK(15,0,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS __pragma(warning(disable:4068))
-#elif \
-    JSON_HEDLEY_TI_VERSION_CHECK(16,9,0) || \
-    JSON_HEDLEY_TI_CL6X_VERSION_CHECK(8,0,0) || \
-    JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) || \
-    JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(2,3,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS _Pragma("diag_suppress 163")
-#elif JSON_HEDLEY_TI_CL6X_VERSION_CHECK(8,0,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS _Pragma("diag_suppress 163")
-#elif JSON_HEDLEY_IAR_VERSION_CHECK(8,0,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS _Pragma("diag_suppress=Pe161")
-#else
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS
-#endif
-
-#if defined(JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_CPP_ATTRIBUTES)
-    #undef JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_CPP_ATTRIBUTES
-#endif
-#if JSON_HEDLEY_HAS_WARNING("-Wunknown-attributes")
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_CPP_ATTRIBUTES _Pragma("clang diagnostic ignored \"-Wunknown-attributes\"")
-#elif JSON_HEDLEY_GCC_VERSION_CHECK(4,6,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_CPP_ATTRIBUTES _Pragma("GCC diagnostic ignored \"-Wdeprecated-declarations\"")
-#elif JSON_HEDLEY_INTEL_VERSION_CHECK(17,0,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_CPP_ATTRIBUTES _Pragma("warning(disable:1292)")
-#elif JSON_HEDLEY_MSVC_VERSION_CHECK(19,0,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_CPP_ATTRIBUTES __pragma(warning(disable:5030))
-#elif JSON_HEDLEY_PGI_VERSION_CHECK(17,10,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_CPP_ATTRIBUTES _Pragma("diag_suppress 1097")
-#elif JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,14,0) && defined(__cplusplus)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_CPP_ATTRIBUTES _Pragma("error_messages(off,attrskipunsup)")
-#elif \
-    JSON_HEDLEY_TI_VERSION_CHECK(18,1,0) || \
-    JSON_HEDLEY_TI_CL6X_VERSION_CHECK(8,3,0) || \
-    JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_CPP_ATTRIBUTES _Pragma("diag_suppress 1173")
-#elif JSON_HEDLEY_IAR_VERSION_CHECK(8,0,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_CPP_ATTRIBUTES _Pragma("diag_suppress=Pe1097")
-#else
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_CPP_ATTRIBUTES
-#endif
-
-#if defined(JSON_HEDLEY_DIAGNOSTIC_DISABLE_CAST_QUAL)
-    #undef JSON_HEDLEY_DIAGNOSTIC_DISABLE_CAST_QUAL
-#endif
-#if JSON_HEDLEY_HAS_WARNING("-Wcast-qual")
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_CAST_QUAL _Pragma("clang diagnostic ignored \"-Wcast-qual\"")
-#elif JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_CAST_QUAL _Pragma("warning(disable:2203 2331)")
-#elif JSON_HEDLEY_GCC_VERSION_CHECK(3,0,0)
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_CAST_QUAL _Pragma("GCC diagnostic ignored \"-Wcast-qual\"")
-#else
-    #define JSON_HEDLEY_DIAGNOSTIC_DISABLE_CAST_QUAL
-#endif
-
-#if defined(JSON_HEDLEY_DEPRECATED)
-    #undef JSON_HEDLEY_DEPRECATED
-#endif
-#if defined(JSON_HEDLEY_DEPRECATED_FOR)
-    #undef JSON_HEDLEY_DEPRECATED_FOR
-#endif
-#if JSON_HEDLEY_MSVC_VERSION_CHECK(14,0,0)
-    #define JSON_HEDLEY_DEPRECATED(since) __declspec(deprecated("Since " # since))
-    #define JSON_HEDLEY_DEPRECATED_FOR(since, replacement) __declspec(deprecated("Since " #since "; use " #replacement))
-#elif defined(__cplusplus) && (__cplusplus >= 201402L)
-    #define JSON_HEDLEY_DEPRECATED(since) JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_([[deprecated("Since " #since)]])
-    #define JSON_HEDLEY_DEPRECATED_FOR(since, replacement) JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_([[deprecated("Since " #since "; use " #replacement)]])
-#elif \
-    JSON_HEDLEY_HAS_EXTENSION(attribute_deprecated_with_message) || \
-    JSON_HEDLEY_GCC_VERSION_CHECK(4,5,0) || \
-    JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0) || \
-    JSON_HEDLEY_ARM_VERSION_CHECK(5,6,0) || \
-    JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,13,0) || \
-    JSON_HEDLEY_PGI_VERSION_CHECK(17,10,0) || \
-    JSON_HEDLEY_TI_VERSION_CHECK(18,1,0) || \
-    JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(18,1,0) || \
-    JSON_HEDLEY_TI_CL6X_VERSION_CHECK(8,3,0) || \
-    JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) || \
-    JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(2,3,0)
-    #define JSON_HEDLEY_DEPRECATED(since) __attribute__((__deprecated__("Since " #since)))
-    #define JSON_HEDLEY_DEPRECATED_FOR(since, replacement) __attribute__((__deprecated__("Since " #since "; use " #replacement)))
-#elif \
-    JSON_HEDLEY_HAS_ATTRIBUTE(deprecated) || \
-    JSON_HEDLEY_GCC_VERSION_CHECK(3,1,0) || \
-    JSON_HEDLEY_ARM_VERSION_CHECK(4,1,0) || \
-    JSON_HEDLEY_TI_VERSION_CHECK(15,12,0) || \
-    (JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(4,8,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(5,2,0) || \
-    (JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,4,0) || \
-    (JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,3,0) || \
-    (JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,2,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,5,0) || \
-    JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) || \
-    JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(2,1,0)
-    #define JSON_HEDLEY_DEPRECATED(since) __attribute__((__deprecated__))
-    #define JSON_HEDLEY_DEPRECATED_FOR(since, replacement) __attribute__((__deprecated__))
-#elif \
-    JSON_HEDLEY_MSVC_VERSION_CHECK(13,10,0) || \
-    JSON_HEDLEY_PELLES_VERSION_CHECK(6,50,0)
-    #define JSON_HEDLEY_DEPRECATED(since) __declspec(deprecated)
-    #define JSON_HEDLEY_DEPRECATED_FOR(since, replacement) __declspec(deprecated)
-#elif JSON_HEDLEY_IAR_VERSION_CHECK(8,0,0)
-    #define JSON_HEDLEY_DEPRECATED(since) _Pragma("deprecated")
-    #define JSON_HEDLEY_DEPRECATED_FOR(since, replacement) _Pragma("deprecated")
-#else
-    #define JSON_HEDLEY_DEPRECATED(since)
-    #define JSON_HEDLEY_DEPRECATED_FOR(since, replacement)
-#endif
-
-#if defined(JSON_HEDLEY_UNAVAILABLE)
-    #undef JSON_HEDLEY_UNAVAILABLE
-#endif
-#if \
-    JSON_HEDLEY_HAS_ATTRIBUTE(warning) || \
-    JSON_HEDLEY_GCC_VERSION_CHECK(4,3,0) || \
-    JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0)
-    #define JSON_HEDLEY_UNAVAILABLE(available_since) __attribute__((__warning__("Not available until " #available_since)))
-#else
-    #define JSON_HEDLEY_UNAVAILABLE(available_since)
-#endif
-
-#if defined(JSON_HEDLEY_WARN_UNUSED_RESULT)
-    #undef JSON_HEDLEY_WARN_UNUSED_RESULT
-#endif
-#if defined(JSON_HEDLEY_WARN_UNUSED_RESULT_MSG)
-    #undef JSON_HEDLEY_WARN_UNUSED_RESULT_MSG
-#endif
-#if (JSON_HEDLEY_HAS_CPP_ATTRIBUTE(nodiscard) >= 201907L)
-    #define JSON_HEDLEY_WARN_UNUSED_RESULT JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_([[nodiscard]])
-    #define JSON_HEDLEY_WARN_UNUSED_RESULT_MSG(msg) JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_([[nodiscard(msg)]])
-#elif JSON_HEDLEY_HAS_CPP_ATTRIBUTE(nodiscard)
-    #define JSON_HEDLEY_WARN_UNUSED_RESULT JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_([[nodiscard]])
-    #define JSON_HEDLEY_WARN_UNUSED_RESULT_MSG(msg) JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_([[nodiscard]])
-#elif \
-    JSON_HEDLEY_HAS_ATTRIBUTE(warn_unused_result) || \
-    JSON_HEDLEY_GCC_VERSION_CHECK(3,4,0) || \
-    JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0) || \
-    JSON_HEDLEY_TI_VERSION_CHECK(15,12,0) || \
-    (JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(4,8,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(5,2,0) || \
-    (JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,4,0) || \
-    (JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,3,0) || \
-    (JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,2,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,5,0) || \
-    JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) || \
-    JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(2,1,0) || \
-    (JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,15,0) && defined(__cplusplus)) || \
-    JSON_HEDLEY_PGI_VERSION_CHECK(17,10,0)
-    #define JSON_HEDLEY_WARN_UNUSED_RESULT __attribute__((__warn_unused_result__))
-    #define JSON_HEDLEY_WARN_UNUSED_RESULT_MSG(msg) __attribute__((__warn_unused_result__))
-#elif defined(_Check_return_) /* SAL */
-    #define JSON_HEDLEY_WARN_UNUSED_RESULT _Check_return_
-    #define JSON_HEDLEY_WARN_UNUSED_RESULT_MSG(msg) _Check_return_
-#else
-    #define JSON_HEDLEY_WARN_UNUSED_RESULT
-    #define JSON_HEDLEY_WARN_UNUSED_RESULT_MSG(msg)
-#endif
-
-#if defined(JSON_HEDLEY_SENTINEL)
-    #undef JSON_HEDLEY_SENTINEL
-#endif
-#if \
-    JSON_HEDLEY_HAS_ATTRIBUTE(sentinel) || \
-    JSON_HEDLEY_GCC_VERSION_CHECK(4,0,0) || \
-    JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0) || \
-    JSON_HEDLEY_ARM_VERSION_CHECK(5,4,0)
-    #define JSON_HEDLEY_SENTINEL(position) __attribute__((__sentinel__(position)))
-#else
-    #define JSON_HEDLEY_SENTINEL(position)
-#endif
-
-#if defined(JSON_HEDLEY_NO_RETURN)
-    #undef JSON_HEDLEY_NO_RETURN
-#endif
-#if JSON_HEDLEY_IAR_VERSION_CHECK(8,0,0)
-    #define JSON_HEDLEY_NO_RETURN __noreturn
-#elif JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0)
-    #define JSON_HEDLEY_NO_RETURN __attribute__((__noreturn__))
-#elif defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L
-    #define JSON_HEDLEY_NO_RETURN _Noreturn
-#elif defined(__cplusplus) && (__cplusplus >= 201103L)
-    #define JSON_HEDLEY_NO_RETURN JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_([[noreturn]])
-#elif \
-    JSON_HEDLEY_HAS_ATTRIBUTE(noreturn) || \
-    JSON_HEDLEY_GCC_VERSION_CHECK(3,2,0) || \
-    JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,11,0) || \
-    JSON_HEDLEY_ARM_VERSION_CHECK(4,1,0) || \
-    JSON_HEDLEY_IBM_VERSION_CHECK(10,1,0) || \
-    JSON_HEDLEY_TI_VERSION_CHECK(15,12,0) || \
-    (JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(4,8,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(5,2,0) || \
-    (JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,4,0) || \
-    (JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,3,0) || \
-    (JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,2,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,5,0) || \
-    JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) || \
-    JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(2,1,0)
-    #define JSON_HEDLEY_NO_RETURN __attribute__((__noreturn__))
-#elif JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,10,0)
-    #define JSON_HEDLEY_NO_RETURN _Pragma("does_not_return")
-#elif JSON_HEDLEY_MSVC_VERSION_CHECK(13,10,0)
-    #define JSON_HEDLEY_NO_RETURN __declspec(noreturn)
-#elif JSON_HEDLEY_TI_CL6X_VERSION_CHECK(6,0,0) && defined(__cplusplus)
-    #define JSON_HEDLEY_NO_RETURN _Pragma("FUNC_NEVER_RETURNS;")
-#elif JSON_HEDLEY_COMPCERT_VERSION_CHECK(3,2,0)
-    #define JSON_HEDLEY_NO_RETURN __attribute((noreturn))
-#elif JSON_HEDLEY_PELLES_VERSION_CHECK(9,0,0)
-    #define JSON_HEDLEY_NO_RETURN __declspec(noreturn)
-#else
-    #define JSON_HEDLEY_NO_RETURN
-#endif
-
-#if defined(JSON_HEDLEY_NO_ESCAPE)
-    #undef JSON_HEDLEY_NO_ESCAPE
-#endif
-#if JSON_HEDLEY_HAS_ATTRIBUTE(noescape)
-    #define JSON_HEDLEY_NO_ESCAPE __attribute__((__noescape__))
-#else
-    #define JSON_HEDLEY_NO_ESCAPE
-#endif
-
-#if defined(JSON_HEDLEY_UNREACHABLE)
-    #undef JSON_HEDLEY_UNREACHABLE
-#endif
-#if defined(JSON_HEDLEY_UNREACHABLE_RETURN)
-    #undef JSON_HEDLEY_UNREACHABLE_RETURN
-#endif
-#if defined(JSON_HEDLEY_ASSUME)
-    #undef JSON_HEDLEY_ASSUME
-#endif
-#if \
-    JSON_HEDLEY_MSVC_VERSION_CHECK(13,10,0) || \
-    JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0)
-    #define JSON_HEDLEY_ASSUME(expr) __assume(expr)
-#elif JSON_HEDLEY_HAS_BUILTIN(__builtin_assume)
-    #define JSON_HEDLEY_ASSUME(expr) __builtin_assume(expr)
-#elif \
-    JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,2,0) || \
-    JSON_HEDLEY_TI_CL6X_VERSION_CHECK(4,0,0)
-    #if defined(__cplusplus)
-        #define JSON_HEDLEY_ASSUME(expr) std::_nassert(expr)
-    #else
-        #define JSON_HEDLEY_ASSUME(expr) _nassert(expr)
-    #endif
-#endif
-#if \
-    (JSON_HEDLEY_HAS_BUILTIN(__builtin_unreachable) && (!defined(JSON_HEDLEY_ARM_VERSION))) || \
-    JSON_HEDLEY_GCC_VERSION_CHECK(4,5,0) || \
-    JSON_HEDLEY_PGI_VERSION_CHECK(18,10,0) || \
-    JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0) || \
-    JSON_HEDLEY_IBM_VERSION_CHECK(13,1,5)
-    #define JSON_HEDLEY_UNREACHABLE() __builtin_unreachable()
-#elif defined(JSON_HEDLEY_ASSUME)
-    #define JSON_HEDLEY_UNREACHABLE() JSON_HEDLEY_ASSUME(0)
-#endif
-#if !defined(JSON_HEDLEY_ASSUME)
-    #if defined(JSON_HEDLEY_UNREACHABLE)
-        #define JSON_HEDLEY_ASSUME(expr) JSON_HEDLEY_STATIC_CAST(void, ((expr) ? 1 : (JSON_HEDLEY_UNREACHABLE(), 1)))
-    #else
-        #define JSON_HEDLEY_ASSUME(expr) JSON_HEDLEY_STATIC_CAST(void, expr)
-    #endif
-#endif
-#if defined(JSON_HEDLEY_UNREACHABLE)
-    #if  \
-        JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,2,0) || \
-        JSON_HEDLEY_TI_CL6X_VERSION_CHECK(4,0,0)
-        #define JSON_HEDLEY_UNREACHABLE_RETURN(value) return (JSON_HEDLEY_STATIC_CAST(void, JSON_HEDLEY_ASSUME(0)), (value))
-    #else
-        #define JSON_HEDLEY_UNREACHABLE_RETURN(value) JSON_HEDLEY_UNREACHABLE()
-    #endif
-#else
-    #define JSON_HEDLEY_UNREACHABLE_RETURN(value) return (value)
-#endif
-#if !defined(JSON_HEDLEY_UNREACHABLE)
-    #define JSON_HEDLEY_UNREACHABLE() JSON_HEDLEY_ASSUME(0)
-#endif
-
-JSON_HEDLEY_DIAGNOSTIC_PUSH
-#if JSON_HEDLEY_HAS_WARNING("-Wpedantic")
-    #pragma clang diagnostic ignored "-Wpedantic"
-#endif
-#if JSON_HEDLEY_HAS_WARNING("-Wc++98-compat-pedantic") && defined(__cplusplus)
-    #pragma clang diagnostic ignored "-Wc++98-compat-pedantic"
-#endif
-#if JSON_HEDLEY_GCC_HAS_WARNING("-Wvariadic-macros",4,0,0)
-    #if defined(__clang__)
-        #pragma clang diagnostic ignored "-Wvariadic-macros"
-    #elif defined(JSON_HEDLEY_GCC_VERSION)
-        #pragma GCC diagnostic ignored "-Wvariadic-macros"
-    #endif
-#endif
-#if defined(JSON_HEDLEY_NON_NULL)
-    #undef JSON_HEDLEY_NON_NULL
-#endif
-#if \
-    JSON_HEDLEY_HAS_ATTRIBUTE(nonnull) || \
-    JSON_HEDLEY_GCC_VERSION_CHECK(3,3,0) || \
-    JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0) || \
-    JSON_HEDLEY_ARM_VERSION_CHECK(4,1,0)
-    #define JSON_HEDLEY_NON_NULL(...) __attribute__((__nonnull__(__VA_ARGS__)))
-#else
-    #define JSON_HEDLEY_NON_NULL(...)
-#endif
-JSON_HEDLEY_DIAGNOSTIC_POP
-
-#if defined(JSON_HEDLEY_PRINTF_FORMAT)
-    #undef JSON_HEDLEY_PRINTF_FORMAT
-#endif
-#if defined(__MINGW32__) && JSON_HEDLEY_GCC_HAS_ATTRIBUTE(format,4,4,0) && !defined(__USE_MINGW_ANSI_STDIO)
-    #define JSON_HEDLEY_PRINTF_FORMAT(string_idx,first_to_check) __attribute__((__format__(ms_printf, string_idx, first_to_check)))
-#elif defined(__MINGW32__) && JSON_HEDLEY_GCC_HAS_ATTRIBUTE(format,4,4,0) && defined(__USE_MINGW_ANSI_STDIO)
-    #define JSON_HEDLEY_PRINTF_FORMAT(string_idx,first_to_check) __attribute__((__format__(gnu_printf, string_idx, first_to_check)))
-#elif \
-    JSON_HEDLEY_HAS_ATTRIBUTE(format) || \
-    JSON_HEDLEY_GCC_VERSION_CHECK(3,1,0) || \
-    JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0) || \
-    JSON_HEDLEY_ARM_VERSION_CHECK(5,6,0) || \
-    JSON_HEDLEY_IBM_VERSION_CHECK(10,1,0) || \
-    JSON_HEDLEY_TI_VERSION_CHECK(15,12,0) || \
-    (JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(4,8,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(5,2,0) || \
-    (JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,4,0) || \
-    (JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,3,0) || \
-    (JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,2,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,5,0) || \
-    JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) || \
-    JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(2,1,0)
-    #define JSON_HEDLEY_PRINTF_FORMAT(string_idx,first_to_check) __attribute__((__format__(__printf__, string_idx, first_to_check)))
-#elif JSON_HEDLEY_PELLES_VERSION_CHECK(6,0,0)
-    #define JSON_HEDLEY_PRINTF_FORMAT(string_idx,first_to_check) __declspec(vaformat(printf,string_idx,first_to_check))
-#else
-    #define JSON_HEDLEY_PRINTF_FORMAT(string_idx,first_to_check)
-#endif
-
-#if defined(JSON_HEDLEY_CONSTEXPR)
-    #undef JSON_HEDLEY_CONSTEXPR
-#endif
-#if defined(__cplusplus)
-    #if __cplusplus >= 201103L
-        #define JSON_HEDLEY_CONSTEXPR JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_(constexpr)
-    #endif
-#endif
-#if !defined(JSON_HEDLEY_CONSTEXPR)
-    #define JSON_HEDLEY_CONSTEXPR
-#endif
-
-#if defined(JSON_HEDLEY_PREDICT)
-    #undef JSON_HEDLEY_PREDICT
-#endif
-#if defined(JSON_HEDLEY_LIKELY)
-    #undef JSON_HEDLEY_LIKELY
-#endif
-#if defined(JSON_HEDLEY_UNLIKELY)
-    #undef JSON_HEDLEY_UNLIKELY
-#endif
-#if defined(JSON_HEDLEY_UNPREDICTABLE)
-    #undef JSON_HEDLEY_UNPREDICTABLE
-#endif
-#if JSON_HEDLEY_HAS_BUILTIN(__builtin_unpredictable)
-    #define JSON_HEDLEY_UNPREDICTABLE(expr) __builtin_unpredictable((expr))
-#endif
-#if \
-  JSON_HEDLEY_HAS_BUILTIN(__builtin_expect_with_probability) || \
-  JSON_HEDLEY_GCC_VERSION_CHECK(9,0,0)
-#  define JSON_HEDLEY_PREDICT(expr, value, probability) __builtin_expect_with_probability(  (expr), (value), (probability))
-#  define JSON_HEDLEY_PREDICT_TRUE(expr, probability)   __builtin_expect_with_probability(!!(expr),    1   , (probability))
-#  define JSON_HEDLEY_PREDICT_FALSE(expr, probability)  __builtin_expect_with_probability(!!(expr),    0   , (probability))
-#  define JSON_HEDLEY_LIKELY(expr)                      __builtin_expect                 (!!(expr),    1                  )
-#  define JSON_HEDLEY_UNLIKELY(expr)                    __builtin_expect                 (!!(expr),    0                  )
-#elif \
-  JSON_HEDLEY_HAS_BUILTIN(__builtin_expect) || \
-  JSON_HEDLEY_GCC_VERSION_CHECK(3,0,0) || \
-  JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0) || \
-  (JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,15,0) && defined(__cplusplus)) || \
-  JSON_HEDLEY_ARM_VERSION_CHECK(4,1,0) || \
-  JSON_HEDLEY_IBM_VERSION_CHECK(10,1,0) || \
-  JSON_HEDLEY_TI_VERSION_CHECK(15,12,0) || \
-  JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(4,7,0) || \
-  JSON_HEDLEY_TI_CL430_VERSION_CHECK(3,1,0) || \
-  JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,1,0) || \
-  JSON_HEDLEY_TI_CL6X_VERSION_CHECK(6,1,0) || \
-  JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) || \
-  JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(2,1,0) || \
-  JSON_HEDLEY_TINYC_VERSION_CHECK(0,9,27) || \
-  JSON_HEDLEY_CRAY_VERSION_CHECK(8,1,0)
-#  define JSON_HEDLEY_PREDICT(expr, expected, probability) \
-    (((probability) >= 0.9) ? __builtin_expect((expr), (expected)) : (JSON_HEDLEY_STATIC_CAST(void, expected), (expr)))
-#  define JSON_HEDLEY_PREDICT_TRUE(expr, probability) \
-    (__extension__ ({ \
-        double hedley_probability_ = (probability); \
-        ((hedley_probability_ >= 0.9) ? __builtin_expect(!!(expr), 1) : ((hedley_probability_ <= 0.1) ? __builtin_expect(!!(expr), 0) : !!(expr))); \
-    }))
-#  define JSON_HEDLEY_PREDICT_FALSE(expr, probability) \
-    (__extension__ ({ \
-        double hedley_probability_ = (probability); \
-        ((hedley_probability_ >= 0.9) ? __builtin_expect(!!(expr), 0) : ((hedley_probability_ <= 0.1) ? __builtin_expect(!!(expr), 1) : !!(expr))); \
-    }))
-#  define JSON_HEDLEY_LIKELY(expr)   __builtin_expect(!!(expr), 1)
-#  define JSON_HEDLEY_UNLIKELY(expr) __builtin_expect(!!(expr), 0)
-#else
-#  define JSON_HEDLEY_PREDICT(expr, expected, probability) (JSON_HEDLEY_STATIC_CAST(void, expected), (expr))
-#  define JSON_HEDLEY_PREDICT_TRUE(expr, probability) (!!(expr))
-#  define JSON_HEDLEY_PREDICT_FALSE(expr, probability) (!!(expr))
-#  define JSON_HEDLEY_LIKELY(expr) (!!(expr))
-#  define JSON_HEDLEY_UNLIKELY(expr) (!!(expr))
-#endif
-#if !defined(JSON_HEDLEY_UNPREDICTABLE)
-    #define JSON_HEDLEY_UNPREDICTABLE(expr) JSON_HEDLEY_PREDICT(expr, 1, 0.5)
-#endif
-
-#if defined(JSON_HEDLEY_MALLOC)
-    #undef JSON_HEDLEY_MALLOC
-#endif
-#if \
-    JSON_HEDLEY_HAS_ATTRIBUTE(malloc) || \
-    JSON_HEDLEY_GCC_VERSION_CHECK(3,1,0) || \
-    JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0) || \
-    JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,11,0) || \
-    JSON_HEDLEY_ARM_VERSION_CHECK(4,1,0) || \
-    JSON_HEDLEY_IBM_VERSION_CHECK(12,1,0) || \
-    JSON_HEDLEY_TI_VERSION_CHECK(15,12,0) || \
-    (JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(4,8,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(5,2,0) || \
-    (JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,4,0) || \
-    (JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,3,0) || \
-    (JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,2,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,5,0) || \
-    JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) || \
-    JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(2,1,0)
-    #define JSON_HEDLEY_MALLOC __attribute__((__malloc__))
-#elif JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,10,0)
-    #define JSON_HEDLEY_MALLOC _Pragma("returns_new_memory")
-#elif JSON_HEDLEY_MSVC_VERSION_CHECK(14, 0, 0)
-    #define JSON_HEDLEY_MALLOC __declspec(restrict)
-#else
-    #define JSON_HEDLEY_MALLOC
-#endif
-
-#if defined(JSON_HEDLEY_PURE)
-    #undef JSON_HEDLEY_PURE
-#endif
-#if \
-  JSON_HEDLEY_HAS_ATTRIBUTE(pure) || \
-  JSON_HEDLEY_GCC_VERSION_CHECK(2,96,0) || \
-  JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0) || \
-  JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,11,0) || \
-  JSON_HEDLEY_ARM_VERSION_CHECK(4,1,0) || \
-  JSON_HEDLEY_IBM_VERSION_CHECK(10,1,0) || \
-  JSON_HEDLEY_TI_VERSION_CHECK(15,12,0) || \
-  (JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(4,8,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-  JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(5,2,0) || \
-  (JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-  JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,4,0) || \
-  (JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-  JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,3,0) || \
-  (JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,2,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-  JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,5,0) || \
-  JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) || \
-  JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(2,1,0) || \
-  JSON_HEDLEY_PGI_VERSION_CHECK(17,10,0)
-#  define JSON_HEDLEY_PURE __attribute__((__pure__))
-#elif JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,10,0)
-#  define JSON_HEDLEY_PURE _Pragma("does_not_write_global_data")
-#elif defined(__cplusplus) && \
-    ( \
-      JSON_HEDLEY_TI_CL430_VERSION_CHECK(2,0,1) || \
-      JSON_HEDLEY_TI_CL6X_VERSION_CHECK(4,0,0) || \
-      JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) \
-    )
-#  define JSON_HEDLEY_PURE _Pragma("FUNC_IS_PURE;")
-#else
-#  define JSON_HEDLEY_PURE
-#endif
-
-#if defined(JSON_HEDLEY_CONST)
-    #undef JSON_HEDLEY_CONST
-#endif
-#if \
-    JSON_HEDLEY_HAS_ATTRIBUTE(const) || \
-    JSON_HEDLEY_GCC_VERSION_CHECK(2,5,0) || \
-    JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0) || \
-    JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,11,0) || \
-    JSON_HEDLEY_ARM_VERSION_CHECK(4,1,0) || \
-    JSON_HEDLEY_IBM_VERSION_CHECK(10,1,0) || \
-    JSON_HEDLEY_TI_VERSION_CHECK(15,12,0) || \
-    (JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(4,8,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(5,2,0) || \
-    (JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,4,0) || \
-    (JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,3,0) || \
-    (JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,2,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,5,0) || \
-    JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) || \
-    JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(2,1,0) || \
-    JSON_HEDLEY_PGI_VERSION_CHECK(17,10,0)
-    #define JSON_HEDLEY_CONST __attribute__((__const__))
-#elif \
-    JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,10,0)
-    #define JSON_HEDLEY_CONST _Pragma("no_side_effect")
-#else
-    #define JSON_HEDLEY_CONST JSON_HEDLEY_PURE
-#endif
-
-#if defined(JSON_HEDLEY_RESTRICT)
-    #undef JSON_HEDLEY_RESTRICT
-#endif
-#if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) && !defined(__cplusplus)
-    #define JSON_HEDLEY_RESTRICT restrict
-#elif \
-    JSON_HEDLEY_GCC_VERSION_CHECK(3,1,0) || \
-    JSON_HEDLEY_MSVC_VERSION_CHECK(14,0,0) || \
-    JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0) || \
-    JSON_HEDLEY_ARM_VERSION_CHECK(4,1,0) || \
-    JSON_HEDLEY_IBM_VERSION_CHECK(10,1,0) || \
-    JSON_HEDLEY_PGI_VERSION_CHECK(17,10,0) || \
-    JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,3,0) || \
-    JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,2,4) || \
-    JSON_HEDLEY_TI_CL6X_VERSION_CHECK(8,1,0) || \
-    JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) || \
-    (JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,14,0) && defined(__cplusplus)) || \
-    JSON_HEDLEY_IAR_VERSION_CHECK(8,0,0) || \
-    defined(__clang__)
-    #define JSON_HEDLEY_RESTRICT __restrict
-#elif JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,3,0) && !defined(__cplusplus)
-    #define JSON_HEDLEY_RESTRICT _Restrict
-#else
-    #define JSON_HEDLEY_RESTRICT
-#endif
-
-#if defined(JSON_HEDLEY_INLINE)
-    #undef JSON_HEDLEY_INLINE
-#endif
-#if \
-    (defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)) || \
-    (defined(__cplusplus) && (__cplusplus >= 199711L))
-    #define JSON_HEDLEY_INLINE inline
-#elif \
-    defined(JSON_HEDLEY_GCC_VERSION) || \
-    JSON_HEDLEY_ARM_VERSION_CHECK(6,2,0)
-    #define JSON_HEDLEY_INLINE __inline__
-#elif \
-    JSON_HEDLEY_MSVC_VERSION_CHECK(12,0,0) || \
-    JSON_HEDLEY_ARM_VERSION_CHECK(4,1,0) || \
-    JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(5,1,0) || \
-    JSON_HEDLEY_TI_CL430_VERSION_CHECK(3,1,0) || \
-    JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,2,0) || \
-    JSON_HEDLEY_TI_CL6X_VERSION_CHECK(8,0,0) || \
-    JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) || \
-    JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(2,1,0)
-    #define JSON_HEDLEY_INLINE __inline
-#else
-    #define JSON_HEDLEY_INLINE
-#endif
-
-#if defined(JSON_HEDLEY_ALWAYS_INLINE)
-    #undef JSON_HEDLEY_ALWAYS_INLINE
-#endif
-#if \
-  JSON_HEDLEY_HAS_ATTRIBUTE(always_inline) || \
-  JSON_HEDLEY_GCC_VERSION_CHECK(4,0,0) || \
-  JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0) || \
-  JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,11,0) || \
-  JSON_HEDLEY_ARM_VERSION_CHECK(4,1,0) || \
-  JSON_HEDLEY_IBM_VERSION_CHECK(10,1,0) || \
-  JSON_HEDLEY_TI_VERSION_CHECK(15,12,0) || \
-  (JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(4,8,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-  JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(5,2,0) || \
-  (JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-  JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,4,0) || \
-  (JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-  JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,3,0) || \
-  (JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,2,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-  JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,5,0) || \
-  JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) || \
-  JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(2,1,0)
-#  define JSON_HEDLEY_ALWAYS_INLINE __attribute__((__always_inline__)) JSON_HEDLEY_INLINE
-#elif JSON_HEDLEY_MSVC_VERSION_CHECK(12,0,0)
-#  define JSON_HEDLEY_ALWAYS_INLINE __forceinline
-#elif defined(__cplusplus) && \
-    ( \
-      JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(5,2,0) || \
-      JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,3,0) || \
-      JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,4,0) || \
-      JSON_HEDLEY_TI_CL6X_VERSION_CHECK(6,1,0) || \
-      JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) || \
-      JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(2,1,0) \
-    )
-#  define JSON_HEDLEY_ALWAYS_INLINE _Pragma("FUNC_ALWAYS_INLINE;")
-#elif JSON_HEDLEY_IAR_VERSION_CHECK(8,0,0)
-#  define JSON_HEDLEY_ALWAYS_INLINE _Pragma("inline=forced")
-#else
-#  define JSON_HEDLEY_ALWAYS_INLINE JSON_HEDLEY_INLINE
-#endif
-
-#if defined(JSON_HEDLEY_NEVER_INLINE)
-    #undef JSON_HEDLEY_NEVER_INLINE
-#endif
-#if \
-    JSON_HEDLEY_HAS_ATTRIBUTE(noinline) || \
-    JSON_HEDLEY_GCC_VERSION_CHECK(4,0,0) || \
-    JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0) || \
-    JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,11,0) || \
-    JSON_HEDLEY_ARM_VERSION_CHECK(4,1,0) || \
-    JSON_HEDLEY_IBM_VERSION_CHECK(10,1,0) || \
-    JSON_HEDLEY_TI_VERSION_CHECK(15,12,0) || \
-    (JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(4,8,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_ARMCL_VERSION_CHECK(5,2,0) || \
-    (JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL2000_VERSION_CHECK(6,4,0) || \
-    (JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,0,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL430_VERSION_CHECK(4,3,0) || \
-    (JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,2,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-    JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,5,0) || \
-    JSON_HEDLEY_TI_CL7X_VERSION_CHECK(1,2,0) || \
-    JSON_HEDLEY_TI_CLPRU_VERSION_CHECK(2,1,0)
-    #define JSON_HEDLEY_NEVER_INLINE __attribute__((__noinline__))
-#elif JSON_HEDLEY_MSVC_VERSION_CHECK(13,10,0)
-    #define JSON_HEDLEY_NEVER_INLINE __declspec(noinline)
-#elif JSON_HEDLEY_PGI_VERSION_CHECK(10,2,0)
-    #define JSON_HEDLEY_NEVER_INLINE _Pragma("noinline")
-#elif JSON_HEDLEY_TI_CL6X_VERSION_CHECK(6,0,0) && defined(__cplusplus)
-    #define JSON_HEDLEY_NEVER_INLINE _Pragma("FUNC_CANNOT_INLINE;")
-#elif JSON_HEDLEY_IAR_VERSION_CHECK(8,0,0)
-    #define JSON_HEDLEY_NEVER_INLINE _Pragma("inline=never")
-#elif JSON_HEDLEY_COMPCERT_VERSION_CHECK(3,2,0)
-    #define JSON_HEDLEY_NEVER_INLINE __attribute((noinline))
-#elif JSON_HEDLEY_PELLES_VERSION_CHECK(9,0,0)
-    #define JSON_HEDLEY_NEVER_INLINE __declspec(noinline)
-#else
-    #define JSON_HEDLEY_NEVER_INLINE
-#endif
-
-#if defined(JSON_HEDLEY_PRIVATE)
-    #undef JSON_HEDLEY_PRIVATE
-#endif
-#if defined(JSON_HEDLEY_PUBLIC)
-    #undef JSON_HEDLEY_PUBLIC
-#endif
-#if defined(JSON_HEDLEY_IMPORT)
-    #undef JSON_HEDLEY_IMPORT
-#endif
-#if defined(_WIN32) || defined(__CYGWIN__)
-#  define JSON_HEDLEY_PRIVATE
-#  define JSON_HEDLEY_PUBLIC   __declspec(dllexport)
-#  define JSON_HEDLEY_IMPORT   __declspec(dllimport)
-#else
-#  if \
-    JSON_HEDLEY_HAS_ATTRIBUTE(visibility) || \
-    JSON_HEDLEY_GCC_VERSION_CHECK(3,3,0) || \
-    JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,11,0) || \
-    JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0) || \
-    JSON_HEDLEY_ARM_VERSION_CHECK(4,1,0) || \
-    JSON_HEDLEY_IBM_VERSION_CHECK(13,1,0) || \
-    ( \
-      defined(__TI_EABI__) && \
-      ( \
-        (JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,2,0) && defined(__TI_GNU_ATTRIBUTE_SUPPORT__)) || \
-        JSON_HEDLEY_TI_CL6X_VERSION_CHECK(7,5,0) \
-      ) \
-    )
-#    define JSON_HEDLEY_PRIVATE __attribute__((__visibility__("hidden")))
-#    define JSON_HEDLEY_PUBLIC  __attribute__((__visibility__("default")))
-#  else
-#    define JSON_HEDLEY_PRIVATE
-#    define JSON_HEDLEY_PUBLIC
-#  endif
-#  define JSON_HEDLEY_IMPORT    extern
-#endif
-
-#if defined(JSON_HEDLEY_NO_THROW)
-    #undef JSON_HEDLEY_NO_THROW
-#endif
-#if \
-    JSON_HEDLEY_HAS_ATTRIBUTE(nothrow) || \
-    JSON_HEDLEY_GCC_VERSION_CHECK(3,3,0) || \
-    JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0)
-    #define JSON_HEDLEY_NO_THROW __attribute__((__nothrow__))
-#elif \
-    JSON_HEDLEY_MSVC_VERSION_CHECK(13,1,0) || \
-    JSON_HEDLEY_ARM_VERSION_CHECK(4,1,0)
-    #define JSON_HEDLEY_NO_THROW __declspec(nothrow)
-#else
-    #define JSON_HEDLEY_NO_THROW
-#endif
-
-#if defined(JSON_HEDLEY_FALL_THROUGH)
-    #undef JSON_HEDLEY_FALL_THROUGH
-#endif
-#if \
-    JSON_HEDLEY_HAS_ATTRIBUTE(fallthrough) || \
-    JSON_HEDLEY_GCC_VERSION_CHECK(7,0,0)
-    #define JSON_HEDLEY_FALL_THROUGH __attribute__((__fallthrough__))
-#elif JSON_HEDLEY_HAS_CPP_ATTRIBUTE_NS(clang,fallthrough)
-    #define JSON_HEDLEY_FALL_THROUGH JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_([[clang::fallthrough]])
-#elif JSON_HEDLEY_HAS_CPP_ATTRIBUTE(fallthrough)
-    #define JSON_HEDLEY_FALL_THROUGH JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_([[fallthrough]])
-#elif defined(__fallthrough) /* SAL */
-    #define JSON_HEDLEY_FALL_THROUGH __fallthrough
-#else
-    #define JSON_HEDLEY_FALL_THROUGH
-#endif
-
-#if defined(JSON_HEDLEY_RETURNS_NON_NULL)
-    #undef JSON_HEDLEY_RETURNS_NON_NULL
-#endif
-#if \
-    JSON_HEDLEY_HAS_ATTRIBUTE(returns_nonnull) || \
-    JSON_HEDLEY_GCC_VERSION_CHECK(4,9,0)
-    #define JSON_HEDLEY_RETURNS_NON_NULL __attribute__((__returns_nonnull__))
-#elif defined(_Ret_notnull_) /* SAL */
-    #define JSON_HEDLEY_RETURNS_NON_NULL _Ret_notnull_
-#else
-    #define JSON_HEDLEY_RETURNS_NON_NULL
-#endif
-
-#if defined(JSON_HEDLEY_ARRAY_PARAM)
-    #undef JSON_HEDLEY_ARRAY_PARAM
-#endif
-#if \
-    defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) && \
-    !defined(__STDC_NO_VLA__) && \
-    !defined(__cplusplus) && \
-    !defined(JSON_HEDLEY_PGI_VERSION) && \
-    !defined(JSON_HEDLEY_TINYC_VERSION)
-    #define JSON_HEDLEY_ARRAY_PARAM(name) (name)
-#else
-    #define JSON_HEDLEY_ARRAY_PARAM(name)
-#endif
-
-#if defined(JSON_HEDLEY_IS_CONSTANT)
-    #undef JSON_HEDLEY_IS_CONSTANT
-#endif
-#if defined(JSON_HEDLEY_REQUIRE_CONSTEXPR)
-    #undef JSON_HEDLEY_REQUIRE_CONSTEXPR
-#endif
-/* JSON_HEDLEY_IS_CONSTEXPR_ is for
-   HEDLEY INTERNAL USE ONLY.  API subject to change without notice. */
-#if defined(JSON_HEDLEY_IS_CONSTEXPR_)
-    #undef JSON_HEDLEY_IS_CONSTEXPR_
-#endif
-#if \
-    JSON_HEDLEY_HAS_BUILTIN(__builtin_constant_p) || \
-    JSON_HEDLEY_GCC_VERSION_CHECK(3,4,0) || \
-    JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0) || \
-    JSON_HEDLEY_TINYC_VERSION_CHECK(0,9,19) || \
-    JSON_HEDLEY_ARM_VERSION_CHECK(4,1,0) || \
-    JSON_HEDLEY_IBM_VERSION_CHECK(13,1,0) || \
-    JSON_HEDLEY_TI_CL6X_VERSION_CHECK(6,1,0) || \
-    (JSON_HEDLEY_SUNPRO_VERSION_CHECK(5,10,0) && !defined(__cplusplus)) || \
-    JSON_HEDLEY_CRAY_VERSION_CHECK(8,1,0)
-    #define JSON_HEDLEY_IS_CONSTANT(expr) __builtin_constant_p(expr)
-#endif
-#if !defined(__cplusplus)
-#  if \
-       JSON_HEDLEY_HAS_BUILTIN(__builtin_types_compatible_p) || \
-       JSON_HEDLEY_GCC_VERSION_CHECK(3,4,0) || \
-       JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0) || \
-       JSON_HEDLEY_IBM_VERSION_CHECK(13,1,0) || \
-       JSON_HEDLEY_CRAY_VERSION_CHECK(8,1,0) || \
-       JSON_HEDLEY_ARM_VERSION_CHECK(5,4,0) || \
-       JSON_HEDLEY_TINYC_VERSION_CHECK(0,9,24)
-#if defined(__INTPTR_TYPE__)
-    #define JSON_HEDLEY_IS_CONSTEXPR_(expr) __builtin_types_compatible_p(__typeof__((1 ? (void*) ((__INTPTR_TYPE__) ((expr) * 0)) : (int*) 0)), int*)
-#else
-    #include <stdint.h>
-    #define JSON_HEDLEY_IS_CONSTEXPR_(expr) __builtin_types_compatible_p(__typeof__((1 ? (void*) ((intptr_t) ((expr) * 0)) : (int*) 0)), int*)
-#endif
-#  elif \
-       ( \
-          defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 201112L) && \
-          !defined(JSON_HEDLEY_SUNPRO_VERSION) && \
-          !defined(JSON_HEDLEY_PGI_VERSION) && \
-          !defined(JSON_HEDLEY_IAR_VERSION)) || \
-       JSON_HEDLEY_HAS_EXTENSION(c_generic_selections) || \
-       JSON_HEDLEY_GCC_VERSION_CHECK(4,9,0) || \
-       JSON_HEDLEY_INTEL_VERSION_CHECK(17,0,0) || \
-       JSON_HEDLEY_IBM_VERSION_CHECK(12,1,0) || \
-       JSON_HEDLEY_ARM_VERSION_CHECK(5,3,0)
-#if defined(__INTPTR_TYPE__)
-    #define JSON_HEDLEY_IS_CONSTEXPR_(expr) _Generic((1 ? (void*) ((__INTPTR_TYPE__) ((expr) * 0)) : (int*) 0), int*: 1, void*: 0)
-#else
-    #include <stdint.h>
-    #define JSON_HEDLEY_IS_CONSTEXPR_(expr) _Generic((1 ? (void*) ((intptr_t) * 0) : (int*) 0), int*: 1, void*: 0)
-#endif
-#  elif \
-       defined(JSON_HEDLEY_GCC_VERSION) || \
-       defined(JSON_HEDLEY_INTEL_VERSION) || \
-       defined(JSON_HEDLEY_TINYC_VERSION) || \
-       defined(JSON_HEDLEY_TI_ARMCL_VERSION) || \
-       JSON_HEDLEY_TI_CL430_VERSION_CHECK(18,12,0) || \
-       defined(JSON_HEDLEY_TI_CL2000_VERSION) || \
-       defined(JSON_HEDLEY_TI_CL6X_VERSION) || \
-       defined(JSON_HEDLEY_TI_CL7X_VERSION) || \
-       defined(JSON_HEDLEY_TI_CLPRU_VERSION) || \
-       defined(__clang__)
-#    define JSON_HEDLEY_IS_CONSTEXPR_(expr) ( \
-        sizeof(void) != \
-        sizeof(*( \
-                  1 ? \
-                  ((void*) ((expr) * 0L) ) : \
-((struct { char v[sizeof(void) * 2]; } *) 1) \
-                ) \
-              ) \
-                                            )
-#  endif
-#endif
-#if defined(JSON_HEDLEY_IS_CONSTEXPR_)
-    #if !defined(JSON_HEDLEY_IS_CONSTANT)
-        #define JSON_HEDLEY_IS_CONSTANT(expr) JSON_HEDLEY_IS_CONSTEXPR_(expr)
-    #endif
-    #define JSON_HEDLEY_REQUIRE_CONSTEXPR(expr) (JSON_HEDLEY_IS_CONSTEXPR_(expr) ? (expr) : (-1))
-#else
-    #if !defined(JSON_HEDLEY_IS_CONSTANT)
-        #define JSON_HEDLEY_IS_CONSTANT(expr) (0)
-    #endif
-    #define JSON_HEDLEY_REQUIRE_CONSTEXPR(expr) (expr)
-#endif
-
-#if defined(JSON_HEDLEY_BEGIN_C_DECLS)
-    #undef JSON_HEDLEY_BEGIN_C_DECLS
-#endif
-#if defined(JSON_HEDLEY_END_C_DECLS)
-    #undef JSON_HEDLEY_END_C_DECLS
-#endif
-#if defined(JSON_HEDLEY_C_DECL)
-    #undef JSON_HEDLEY_C_DECL
-#endif
-#if defined(__cplusplus)
-    #define JSON_HEDLEY_BEGIN_C_DECLS extern "C" {
-    #define JSON_HEDLEY_END_C_DECLS }
-    #define JSON_HEDLEY_C_DECL extern "C"
-#else
-    #define JSON_HEDLEY_BEGIN_C_DECLS
-    #define JSON_HEDLEY_END_C_DECLS
-    #define JSON_HEDLEY_C_DECL
-#endif
-
-#if defined(JSON_HEDLEY_STATIC_ASSERT)
-    #undef JSON_HEDLEY_STATIC_ASSERT
-#endif
-#if \
-  !defined(__cplusplus) && ( \
-      (defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 201112L)) || \
-      JSON_HEDLEY_HAS_FEATURE(c_static_assert) || \
-      JSON_HEDLEY_GCC_VERSION_CHECK(6,0,0) || \
-      JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0) || \
-      defined(_Static_assert) \
-    )
-#  define JSON_HEDLEY_STATIC_ASSERT(expr, message) _Static_assert(expr, message)
-#elif \
-  (defined(__cplusplus) && (__cplusplus >= 201103L)) || \
-  JSON_HEDLEY_MSVC_VERSION_CHECK(16,0,0)
-#  define JSON_HEDLEY_STATIC_ASSERT(expr, message) JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_(static_assert(expr, message))
-#else
-#  define JSON_HEDLEY_STATIC_ASSERT(expr, message)
-#endif
-
-#if defined(JSON_HEDLEY_NULL)
-    #undef JSON_HEDLEY_NULL
-#endif
-#if defined(__cplusplus)
-    #if __cplusplus >= 201103L
-        #define JSON_HEDLEY_NULL JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_(nullptr)
-    #elif defined(NULL)
-        #define JSON_HEDLEY_NULL NULL
-    #else
-        #define JSON_HEDLEY_NULL JSON_HEDLEY_STATIC_CAST(void*, 0)
-    #endif
-#elif defined(NULL)
-    #define JSON_HEDLEY_NULL NULL
-#else
-    #define JSON_HEDLEY_NULL ((void*) 0)
-#endif
-
-#if defined(JSON_HEDLEY_MESSAGE)
-    #undef JSON_HEDLEY_MESSAGE
-#endif
-#if JSON_HEDLEY_HAS_WARNING("-Wunknown-pragmas")
-#  define JSON_HEDLEY_MESSAGE(msg) \
-    JSON_HEDLEY_DIAGNOSTIC_PUSH \
-    JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS \
-    JSON_HEDLEY_PRAGMA(message msg) \
-    JSON_HEDLEY_DIAGNOSTIC_POP
-#elif \
-  JSON_HEDLEY_GCC_VERSION_CHECK(4,4,0) || \
-  JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0)
-#  define JSON_HEDLEY_MESSAGE(msg) JSON_HEDLEY_PRAGMA(message msg)
-#elif JSON_HEDLEY_CRAY_VERSION_CHECK(5,0,0)
-#  define JSON_HEDLEY_MESSAGE(msg) JSON_HEDLEY_PRAGMA(_CRI message msg)
-#elif JSON_HEDLEY_IAR_VERSION_CHECK(8,0,0)
-#  define JSON_HEDLEY_MESSAGE(msg) JSON_HEDLEY_PRAGMA(message(msg))
-#elif JSON_HEDLEY_PELLES_VERSION_CHECK(2,0,0)
-#  define JSON_HEDLEY_MESSAGE(msg) JSON_HEDLEY_PRAGMA(message(msg))
-#else
-#  define JSON_HEDLEY_MESSAGE(msg)
-#endif
-
-#if defined(JSON_HEDLEY_WARNING)
-    #undef JSON_HEDLEY_WARNING
-#endif
-#if JSON_HEDLEY_HAS_WARNING("-Wunknown-pragmas")
-#  define JSON_HEDLEY_WARNING(msg) \
-    JSON_HEDLEY_DIAGNOSTIC_PUSH \
-    JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS \
-    JSON_HEDLEY_PRAGMA(clang warning msg) \
-    JSON_HEDLEY_DIAGNOSTIC_POP
-#elif \
-  JSON_HEDLEY_GCC_VERSION_CHECK(4,8,0) || \
-  JSON_HEDLEY_PGI_VERSION_CHECK(18,4,0) || \
-  JSON_HEDLEY_INTEL_VERSION_CHECK(13,0,0)
-#  define JSON_HEDLEY_WARNING(msg) JSON_HEDLEY_PRAGMA(GCC warning msg)
-#elif JSON_HEDLEY_MSVC_VERSION_CHECK(15,0,0)
-#  define JSON_HEDLEY_WARNING(msg) JSON_HEDLEY_PRAGMA(message(msg))
-#else
-#  define JSON_HEDLEY_WARNING(msg) JSON_HEDLEY_MESSAGE(msg)
-#endif
-
-#if defined(JSON_HEDLEY_REQUIRE)
-    #undef JSON_HEDLEY_REQUIRE
-#endif
-#if defined(JSON_HEDLEY_REQUIRE_MSG)
-    #undef JSON_HEDLEY_REQUIRE_MSG
-#endif
-#if JSON_HEDLEY_HAS_ATTRIBUTE(diagnose_if)
-#  if JSON_HEDLEY_HAS_WARNING("-Wgcc-compat")
-#    define JSON_HEDLEY_REQUIRE(expr) \
-    JSON_HEDLEY_DIAGNOSTIC_PUSH \
-    _Pragma("clang diagnostic ignored \"-Wgcc-compat\"") \
-    __attribute__((diagnose_if(!(expr), #expr, "error"))) \
-    JSON_HEDLEY_DIAGNOSTIC_POP
-#    define JSON_HEDLEY_REQUIRE_MSG(expr,msg) \
-    JSON_HEDLEY_DIAGNOSTIC_PUSH \
-    _Pragma("clang diagnostic ignored \"-Wgcc-compat\"") \
-    __attribute__((diagnose_if(!(expr), msg, "error"))) \
-    JSON_HEDLEY_DIAGNOSTIC_POP
-#  else
-#    define JSON_HEDLEY_REQUIRE(expr) __attribute__((diagnose_if(!(expr), #expr, "error")))
-#    define JSON_HEDLEY_REQUIRE_MSG(expr,msg) __attribute__((diagnose_if(!(expr), msg, "error")))
-#  endif
-#else
-#  define JSON_HEDLEY_REQUIRE(expr)
-#  define JSON_HEDLEY_REQUIRE_MSG(expr,msg)
-#endif
-
-#if defined(JSON_HEDLEY_FLAGS)
-    #undef JSON_HEDLEY_FLAGS
-#endif
-#if JSON_HEDLEY_HAS_ATTRIBUTE(flag_enum)
-    #define JSON_HEDLEY_FLAGS __attribute__((__flag_enum__))
-#endif
-
-#if defined(JSON_HEDLEY_FLAGS_CAST)
-    #undef JSON_HEDLEY_FLAGS_CAST
-#endif
-#if JSON_HEDLEY_INTEL_VERSION_CHECK(19,0,0)
-#  define JSON_HEDLEY_FLAGS_CAST(T, expr) (__extension__ ({ \
-        JSON_HEDLEY_DIAGNOSTIC_PUSH \
-        _Pragma("warning(disable:188)") \
-        ((T) (expr)); \
-        JSON_HEDLEY_DIAGNOSTIC_POP \
-    }))
-#else
-#  define JSON_HEDLEY_FLAGS_CAST(T, expr) JSON_HEDLEY_STATIC_CAST(T, expr)
-#endif
-
-#if defined(JSON_HEDLEY_EMPTY_BASES)
-    #undef JSON_HEDLEY_EMPTY_BASES
-#endif
-#if JSON_HEDLEY_MSVC_VERSION_CHECK(19,0,23918) && !JSON_HEDLEY_MSVC_VERSION_CHECK(20,0,0)
-    #define JSON_HEDLEY_EMPTY_BASES __declspec(empty_bases)
-#else
-    #define JSON_HEDLEY_EMPTY_BASES
-#endif
-
-/* Remaining macros are deprecated. */
-
-#if defined(JSON_HEDLEY_GCC_NOT_CLANG_VERSION_CHECK)
-    #undef JSON_HEDLEY_GCC_NOT_CLANG_VERSION_CHECK
-#endif
-#if defined(__clang__)
-    #define JSON_HEDLEY_GCC_NOT_CLANG_VERSION_CHECK(major,minor,patch) (0)
-#else
-    #define JSON_HEDLEY_GCC_NOT_CLANG_VERSION_CHECK(major,minor,patch) JSON_HEDLEY_GCC_VERSION_CHECK(major,minor,patch)
-#endif
-
-#if defined(JSON_HEDLEY_CLANG_HAS_ATTRIBUTE)
-    #undef JSON_HEDLEY_CLANG_HAS_ATTRIBUTE
-#endif
-#define JSON_HEDLEY_CLANG_HAS_ATTRIBUTE(attribute) JSON_HEDLEY_HAS_ATTRIBUTE(attribute)
-
-#if defined(JSON_HEDLEY_CLANG_HAS_CPP_ATTRIBUTE)
-    #undef JSON_HEDLEY_CLANG_HAS_CPP_ATTRIBUTE
-#endif
-#define JSON_HEDLEY_CLANG_HAS_CPP_ATTRIBUTE(attribute) JSON_HEDLEY_HAS_CPP_ATTRIBUTE(attribute)
-
-#if defined(JSON_HEDLEY_CLANG_HAS_BUILTIN)
-    #undef JSON_HEDLEY_CLANG_HAS_BUILTIN
-#endif
-#define JSON_HEDLEY_CLANG_HAS_BUILTIN(builtin) JSON_HEDLEY_HAS_BUILTIN(builtin)
-
-#if defined(JSON_HEDLEY_CLANG_HAS_FEATURE)
-    #undef JSON_HEDLEY_CLANG_HAS_FEATURE
-#endif
-#define JSON_HEDLEY_CLANG_HAS_FEATURE(feature) JSON_HEDLEY_HAS_FEATURE(feature)
-
-#if defined(JSON_HEDLEY_CLANG_HAS_EXTENSION)
-    #undef JSON_HEDLEY_CLANG_HAS_EXTENSION
-#endif
-#define JSON_HEDLEY_CLANG_HAS_EXTENSION(extension) JSON_HEDLEY_HAS_EXTENSION(extension)
-
-#if defined(JSON_HEDLEY_CLANG_HAS_DECLSPEC_DECLSPEC_ATTRIBUTE)
-    #undef JSON_HEDLEY_CLANG_HAS_DECLSPEC_DECLSPEC_ATTRIBUTE
-#endif
-#define JSON_HEDLEY_CLANG_HAS_DECLSPEC_ATTRIBUTE(attribute) JSON_HEDLEY_HAS_DECLSPEC_ATTRIBUTE(attribute)
-
-#if defined(JSON_HEDLEY_CLANG_HAS_WARNING)
-    #undef JSON_HEDLEY_CLANG_HAS_WARNING
-#endif
-#define JSON_HEDLEY_CLANG_HAS_WARNING(warning) JSON_HEDLEY_HAS_WARNING(warning)
-
-#endif /* !defined(JSON_HEDLEY_VERSION) || (JSON_HEDLEY_VERSION < X) */
-
-
-// This file contains all internal macro definitions
-// You MUST include macro_unscope.hpp at the end of json.hpp to undef all of them
-
-// exclude unsupported compilers
-#if !defined(JSON_SKIP_UNSUPPORTED_COMPILER_CHECK)
-    #if defined(__clang__)
-        #if (__clang_major__ * 10000 + __clang_minor__ * 100 + __clang_patchlevel__) < 30400
-            #error "unsupported Clang version - see https://github.com/nlohmann/json#supported-compilers"
-        #endif
-    #elif defined(__GNUC__) && !(defined(__ICC) || defined(__INTEL_COMPILER))
-        #if (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) < 40800
-            #error "unsupported GCC version - see https://github.com/nlohmann/json#supported-compilers"
-        #endif
-    #endif
-#endif
-
-// C++ language standard detection
-#if (defined(__cplusplus) && __cplusplus >= 202002L) || (defined(_MSVC_LANG) && _MSVC_LANG >= 202002L)
-    #define JSON_HAS_CPP_20
-    #define JSON_HAS_CPP_17
-    #define JSON_HAS_CPP_14
-#elif (defined(__cplusplus) && __cplusplus >= 201703L) || (defined(_HAS_CXX17) && _HAS_CXX17 == 1) // fix for issue #464
-    #define JSON_HAS_CPP_17
-    #define JSON_HAS_CPP_14
-#elif (defined(__cplusplus) && __cplusplus >= 201402L) || (defined(_HAS_CXX14) && _HAS_CXX14 == 1)
-    #define JSON_HAS_CPP_14
-#endif
-
-// disable float-equal warnings on GCC/clang
-#if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
-    #pragma GCC diagnostic push
-    #pragma GCC diagnostic ignored "-Wfloat-equal"
-#endif
-
-// disable documentation warnings on clang
-#if defined(__clang__)
-    #pragma GCC diagnostic push
-    #pragma GCC diagnostic ignored "-Wdocumentation"
-#endif
-
-// allow to disable exceptions
-#if (defined(__cpp_exceptions) || defined(__EXCEPTIONS) || defined(_CPPUNWIND)) && !defined(JSON_NOEXCEPTION)
-    #define JSON_THROW(exception) throw exception
-    #define JSON_TRY try
-    #define JSON_CATCH(exception) catch(exception)
-    #define JSON_INTERNAL_CATCH(exception) catch(exception)
-#else
-    #include <cstdlib>
-    #define JSON_THROW(exception) std::abort()
-    #define JSON_TRY if(true)
-    #define JSON_CATCH(exception) if(false)
-    #define JSON_INTERNAL_CATCH(exception) if(false)
-#endif
-
-// override exception macros
-#if defined(JSON_THROW_USER)
-    #undef JSON_THROW
-    #define JSON_THROW JSON_THROW_USER
-#endif
-#if defined(JSON_TRY_USER)
-    #undef JSON_TRY
-    #define JSON_TRY JSON_TRY_USER
-#endif
-#if defined(JSON_CATCH_USER)
-    #undef JSON_CATCH
-    #define JSON_CATCH JSON_CATCH_USER
-    #undef JSON_INTERNAL_CATCH
-    #define JSON_INTERNAL_CATCH JSON_CATCH_USER
-#endif
-#if defined(JSON_INTERNAL_CATCH_USER)
-    #undef JSON_INTERNAL_CATCH
-    #define JSON_INTERNAL_CATCH JSON_INTERNAL_CATCH_USER
-#endif
-
-// allow to override assert
-#if !defined(JSON_ASSERT)
-    #include <cassert> // assert
-    #define JSON_ASSERT(x) assert(x)
-#endif
-
-/*!
-@brief macro to briefly define a mapping between an enum and JSON
-@def NLOHMANN_JSON_SERIALIZE_ENUM
-@since version 3.4.0
-*/
-#define NLOHMANN_JSON_SERIALIZE_ENUM(ENUM_TYPE, ...)                                            \
-    template<typename BasicJsonType>                                                            \
-    inline void to_json(BasicJsonType& j, const ENUM_TYPE& e)                                   \
-    {                                                                                           \
-        static_assert(std::is_enum<ENUM_TYPE>::value, #ENUM_TYPE " must be an enum!");          \
-        static const std::pair<ENUM_TYPE, BasicJsonType> m[] = __VA_ARGS__;                     \
-        auto it = std::find_if(std::begin(m), std::end(m),                                      \
-                               [e](const std::pair<ENUM_TYPE, BasicJsonType>& ej_pair) -> bool  \
-        {                                                                                       \
-            return ej_pair.first == e;                                                          \
-        });                                                                                     \
-        j = ((it != std::end(m)) ? it : std::begin(m))->second;                                 \
-    }                                                                                           \
-    template<typename BasicJsonType>                                                            \
-    inline void from_json(const BasicJsonType& j, ENUM_TYPE& e)                                 \
-    {                                                                                           \
-        static_assert(std::is_enum<ENUM_TYPE>::value, #ENUM_TYPE " must be an enum!");          \
-        static const std::pair<ENUM_TYPE, BasicJsonType> m[] = __VA_ARGS__;                     \
-        auto it = std::find_if(std::begin(m), std::end(m),                                      \
-                               [&j](const std::pair<ENUM_TYPE, BasicJsonType>& ej_pair) -> bool \
-        {                                                                                       \
-            return ej_pair.second == j;                                                         \
-        });                                                                                     \
-        e = ((it != std::end(m)) ? it : std::begin(m))->first;                                  \
-    }
-
-// Ugly macros to avoid uglier copy-paste when specializing basic_json. They
-// may be removed in the future once the class is split.
-
-#define NLOHMANN_BASIC_JSON_TPL_DECLARATION                                \
-    template<template<typename, typename, typename...> class ObjectType,   \
-             template<typename, typename...> class ArrayType,              \
-             class StringType, class BooleanType, class NumberIntegerType, \
-             class NumberUnsignedType, class NumberFloatType,              \
-             template<typename> class AllocatorType,                       \
-             template<typename, typename = void> class JSONSerializer,     \
-             class BinaryType>
-
-#define NLOHMANN_BASIC_JSON_TPL                                            \
-    basic_json<ObjectType, ArrayType, StringType, BooleanType,             \
-    NumberIntegerType, NumberUnsignedType, NumberFloatType,                \
-    AllocatorType, JSONSerializer, BinaryType>
-
-// Macros to simplify conversion from/to types
-
-#define NLOHMANN_JSON_EXPAND( x ) x
-#define NLOHMANN_JSON_GET_MACRO(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, _41, _42, _43, _44, _45, _46, _47, _48, _49, _50, _51, _52, _53, _54, _55, _56, _57, _58, _59, _60, _61, _62, _63, _64, NAME,...) NAME
-#define NLOHMANN_JSON_PASTE(...) NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_GET_MACRO(__VA_ARGS__, \
-        NLOHMANN_JSON_PASTE64, \
-        NLOHMANN_JSON_PASTE63, \
-        NLOHMANN_JSON_PASTE62, \
-        NLOHMANN_JSON_PASTE61, \
-        NLOHMANN_JSON_PASTE60, \
-        NLOHMANN_JSON_PASTE59, \
-        NLOHMANN_JSON_PASTE58, \
-        NLOHMANN_JSON_PASTE57, \
-        NLOHMANN_JSON_PASTE56, \
-        NLOHMANN_JSON_PASTE55, \
-        NLOHMANN_JSON_PASTE54, \
-        NLOHMANN_JSON_PASTE53, \
-        NLOHMANN_JSON_PASTE52, \
-        NLOHMANN_JSON_PASTE51, \
-        NLOHMANN_JSON_PASTE50, \
-        NLOHMANN_JSON_PASTE49, \
-        NLOHMANN_JSON_PASTE48, \
-        NLOHMANN_JSON_PASTE47, \
-        NLOHMANN_JSON_PASTE46, \
-        NLOHMANN_JSON_PASTE45, \
-        NLOHMANN_JSON_PASTE44, \
-        NLOHMANN_JSON_PASTE43, \
-        NLOHMANN_JSON_PASTE42, \
-        NLOHMANN_JSON_PASTE41, \
-        NLOHMANN_JSON_PASTE40, \
-        NLOHMANN_JSON_PASTE39, \
-        NLOHMANN_JSON_PASTE38, \
-        NLOHMANN_JSON_PASTE37, \
-        NLOHMANN_JSON_PASTE36, \
-        NLOHMANN_JSON_PASTE35, \
-        NLOHMANN_JSON_PASTE34, \
-        NLOHMANN_JSON_PASTE33, \
-        NLOHMANN_JSON_PASTE32, \
-        NLOHMANN_JSON_PASTE31, \
-        NLOHMANN_JSON_PASTE30, \
-        NLOHMANN_JSON_PASTE29, \
-        NLOHMANN_JSON_PASTE28, \
-        NLOHMANN_JSON_PASTE27, \
-        NLOHMANN_JSON_PASTE26, \
-        NLOHMANN_JSON_PASTE25, \
-        NLOHMANN_JSON_PASTE24, \
-        NLOHMANN_JSON_PASTE23, \
-        NLOHMANN_JSON_PASTE22, \
-        NLOHMANN_JSON_PASTE21, \
-        NLOHMANN_JSON_PASTE20, \
-        NLOHMANN_JSON_PASTE19, \
-        NLOHMANN_JSON_PASTE18, \
-        NLOHMANN_JSON_PASTE17, \
-        NLOHMANN_JSON_PASTE16, \
-        NLOHMANN_JSON_PASTE15, \
-        NLOHMANN_JSON_PASTE14, \
-        NLOHMANN_JSON_PASTE13, \
-        NLOHMANN_JSON_PASTE12, \
-        NLOHMANN_JSON_PASTE11, \
-        NLOHMANN_JSON_PASTE10, \
-        NLOHMANN_JSON_PASTE9, \
-        NLOHMANN_JSON_PASTE8, \
-        NLOHMANN_JSON_PASTE7, \
-        NLOHMANN_JSON_PASTE6, \
-        NLOHMANN_JSON_PASTE5, \
-        NLOHMANN_JSON_PASTE4, \
-        NLOHMANN_JSON_PASTE3, \
-        NLOHMANN_JSON_PASTE2, \
-        NLOHMANN_JSON_PASTE1)(__VA_ARGS__))
-#define NLOHMANN_JSON_PASTE2(func, v1) func(v1)
-#define NLOHMANN_JSON_PASTE3(func, v1, v2) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE2(func, v2)
-#define NLOHMANN_JSON_PASTE4(func, v1, v2, v3) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE3(func, v2, v3)
-#define NLOHMANN_JSON_PASTE5(func, v1, v2, v3, v4) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE4(func, v2, v3, v4)
-#define NLOHMANN_JSON_PASTE6(func, v1, v2, v3, v4, v5) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE5(func, v2, v3, v4, v5)
-#define NLOHMANN_JSON_PASTE7(func, v1, v2, v3, v4, v5, v6) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE6(func, v2, v3, v4, v5, v6)
-#define NLOHMANN_JSON_PASTE8(func, v1, v2, v3, v4, v5, v6, v7) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE7(func, v2, v3, v4, v5, v6, v7)
-#define NLOHMANN_JSON_PASTE9(func, v1, v2, v3, v4, v5, v6, v7, v8) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE8(func, v2, v3, v4, v5, v6, v7, v8)
-#define NLOHMANN_JSON_PASTE10(func, v1, v2, v3, v4, v5, v6, v7, v8, v9) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE9(func, v2, v3, v4, v5, v6, v7, v8, v9)
-#define NLOHMANN_JSON_PASTE11(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE10(func, v2, v3, v4, v5, v6, v7, v8, v9, v10)
-#define NLOHMANN_JSON_PASTE12(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE11(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11)
-#define NLOHMANN_JSON_PASTE13(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE12(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12)
-#define NLOHMANN_JSON_PASTE14(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE13(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13)
-#define NLOHMANN_JSON_PASTE15(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE14(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14)
-#define NLOHMANN_JSON_PASTE16(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE15(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15)
-#define NLOHMANN_JSON_PASTE17(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE16(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16)
-#define NLOHMANN_JSON_PASTE18(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE17(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17)
-#define NLOHMANN_JSON_PASTE19(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE18(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18)
-#define NLOHMANN_JSON_PASTE20(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE19(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19)
-#define NLOHMANN_JSON_PASTE21(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE20(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20)
-#define NLOHMANN_JSON_PASTE22(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE21(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21)
-#define NLOHMANN_JSON_PASTE23(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE22(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22)
-#define NLOHMANN_JSON_PASTE24(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE23(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23)
-#define NLOHMANN_JSON_PASTE25(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE24(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24)
-#define NLOHMANN_JSON_PASTE26(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE25(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25)
-#define NLOHMANN_JSON_PASTE27(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE26(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26)
-#define NLOHMANN_JSON_PASTE28(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE27(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27)
-#define NLOHMANN_JSON_PASTE29(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE28(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28)
-#define NLOHMANN_JSON_PASTE30(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE29(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29)
-#define NLOHMANN_JSON_PASTE31(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE30(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30)
-#define NLOHMANN_JSON_PASTE32(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE31(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31)
-#define NLOHMANN_JSON_PASTE33(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE32(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32)
-#define NLOHMANN_JSON_PASTE34(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE33(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33)
-#define NLOHMANN_JSON_PASTE35(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE34(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34)
-#define NLOHMANN_JSON_PASTE36(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE35(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35)
-#define NLOHMANN_JSON_PASTE37(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE36(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36)
-#define NLOHMANN_JSON_PASTE38(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE37(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37)
-#define NLOHMANN_JSON_PASTE39(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE38(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38)
-#define NLOHMANN_JSON_PASTE40(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE39(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39)
-#define NLOHMANN_JSON_PASTE41(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE40(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40)
-#define NLOHMANN_JSON_PASTE42(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE41(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41)
-#define NLOHMANN_JSON_PASTE43(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE42(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42)
-#define NLOHMANN_JSON_PASTE44(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE43(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43)
-#define NLOHMANN_JSON_PASTE45(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE44(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44)
-#define NLOHMANN_JSON_PASTE46(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE45(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45)
-#define NLOHMANN_JSON_PASTE47(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE46(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46)
-#define NLOHMANN_JSON_PASTE48(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE47(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47)
-#define NLOHMANN_JSON_PASTE49(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE48(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48)
-#define NLOHMANN_JSON_PASTE50(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE49(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49)
-#define NLOHMANN_JSON_PASTE51(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE50(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50)
-#define NLOHMANN_JSON_PASTE52(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE51(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51)
-#define NLOHMANN_JSON_PASTE53(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE52(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52)
-#define NLOHMANN_JSON_PASTE54(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE53(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53)
-#define NLOHMANN_JSON_PASTE55(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE54(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54)
-#define NLOHMANN_JSON_PASTE56(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54, v55) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE55(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54, v55)
-#define NLOHMANN_JSON_PASTE57(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54, v55, v56) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE56(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54, v55, v56)
-#define NLOHMANN_JSON_PASTE58(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54, v55, v56, v57) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE57(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54, v55, v56, v57)
-#define NLOHMANN_JSON_PASTE59(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54, v55, v56, v57, v58) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE58(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54, v55, v56, v57, v58)
-#define NLOHMANN_JSON_PASTE60(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54, v55, v56, v57, v58, v59) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE59(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54, v55, v56, v57, v58, v59)
-#define NLOHMANN_JSON_PASTE61(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54, v55, v56, v57, v58, v59, v60) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE60(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54, v55, v56, v57, v58, v59, v60)
-#define NLOHMANN_JSON_PASTE62(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54, v55, v56, v57, v58, v59, v60, v61) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE61(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54, v55, v56, v57, v58, v59, v60, v61)
-#define NLOHMANN_JSON_PASTE63(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54, v55, v56, v57, v58, v59, v60, v61, v62) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE62(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54, v55, v56, v57, v58, v59, v60, v61, v62)
-#define NLOHMANN_JSON_PASTE64(func, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54, v55, v56, v57, v58, v59, v60, v61, v62, v63) NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE63(func, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, v48, v49, v50, v51, v52, v53, v54, v55, v56, v57, v58, v59, v60, v61, v62, v63)
-
-#define NLOHMANN_JSON_TO(v1) nlohmann_json_j[#v1] = nlohmann_json_t.v1;
-#define NLOHMANN_JSON_FROM(v1) nlohmann_json_j.at(#v1).get_to(nlohmann_json_t.v1);
-
-/*!
-@brief macro
-@def NLOHMANN_DEFINE_TYPE_INTRUSIVE
-@since version 3.9.0
-*/
-#define NLOHMANN_DEFINE_TYPE_INTRUSIVE(Type, ...)  \
-    friend void to_json(nlohmann::json& nlohmann_json_j, const Type& nlohmann_json_t) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_TO, __VA_ARGS__)) } \
-    friend void from_json(const nlohmann::json& nlohmann_json_j, Type& nlohmann_json_t) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_FROM, __VA_ARGS__)) }
-
-/*!
-@brief macro
-@def NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE
-@since version 3.9.0
-*/
-#define NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(Type, ...)  \
-    inline void to_json(nlohmann::json& nlohmann_json_j, const Type& nlohmann_json_t) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_TO, __VA_ARGS__)) } \
-    inline void from_json(const nlohmann::json& nlohmann_json_j, Type& nlohmann_json_t) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_FROM, __VA_ARGS__)) }
-
-#ifndef JSON_USE_IMPLICIT_CONVERSIONS
-    #define JSON_USE_IMPLICIT_CONVERSIONS 1
-#endif
-
-#if JSON_USE_IMPLICIT_CONVERSIONS
-    #define JSON_EXPLICIT
-#else
-    #define JSON_EXPLICIT explicit
-#endif
-
-
-namespace nlohmann
-{
-namespace detail
-{
-////////////////
-// exceptions //
-////////////////
-
-/*!
-@brief general exception of the @ref basic_json class
-
-This class is an extension of `std::exception` objects with a member @a id for
-exception ids. It is used as the base class for all exceptions thrown by the
-@ref basic_json class. This class can hence be used as "wildcard" to catch
-exceptions.
-
-Subclasses:
-- @ref parse_error for exceptions indicating a parse error
-- @ref invalid_iterator for exceptions indicating errors with iterators
-- @ref type_error for exceptions indicating executing a member function with
-                  a wrong type
-- @ref out_of_range for exceptions indicating access out of the defined range
-- @ref other_error for exceptions indicating other library errors
-
-@internal
-@note To have nothrow-copy-constructible exceptions, we internally use
-      `std::runtime_error` which can cope with arbitrary-length error messages.
-      Intermediate strings are built with static functions and then passed to
-      the actual constructor.
-@endinternal
-
-@liveexample{The following code shows how arbitrary library exceptions can be
-caught.,exception}
-
-@since version 3.0.0
-*/
-class exception : public std::exception
-{
-  public:
-    /// returns the explanatory string
-    JSON_HEDLEY_RETURNS_NON_NULL
-    const char* what() const noexcept override
-    {
-        return m.what();
-    }
-
-    /// the id of the exception
-    const int id;
-
-  protected:
-    JSON_HEDLEY_NON_NULL(3)
-    exception(int id_, const char* what_arg) : id(id_), m(what_arg) {}
-
-    static std::string name(const std::string& ename, int id_)
-    {
-        return "[json.exception." + ename + "." + std::to_string(id_) + "] ";
-    }
-
-  private:
-    /// an exception object as storage for error messages
-    std::runtime_error m;
-};
-
-/*!
-@brief exception indicating a parse error
-
-This exception is thrown by the library when a parse error occurs. Parse errors
-can occur during the deserialization of JSON text, CBOR, MessagePack, as well
-as when using JSON Patch.
-
-Member @a byte holds the byte index of the last read character in the input
-file.
-
-Exceptions have ids 1xx.
-
-name / id                      | example message | description
------------------------------- | --------------- | -------------------------
-json.exception.parse_error.101 | parse error at 2: unexpected end of input; expected string literal | This error indicates a syntax error while deserializing a JSON text. The error message describes that an unexpected token (character) was encountered, and the member @a byte indicates the error position.
-json.exception.parse_error.102 | parse error at 14: missing or wrong low surrogate | JSON uses the `\uxxxx` format to describe Unicode characters. Code points above above 0xFFFF are split into two `\uxxxx` entries ("surrogate pairs"). This error indicates that the surrogate pair is incomplete or contains an invalid code point.
-json.exception.parse_error.103 | parse error: code points above 0x10FFFF are invalid | Unicode supports code points up to 0x10FFFF. Code points above 0x10FFFF are invalid.
-json.exception.parse_error.104 | parse error: JSON patch must be an array of objects | [RFC 6902](https://tools.ietf.org/html/rfc6902) requires a JSON Patch document to be a JSON document that represents an array of objects.
-json.exception.parse_error.105 | parse error: operation must have string member 'op' | An operation of a JSON Patch document must contain exactly one "op" member, whose value indicates the operation to perform. Its value must be one of "add", "remove", "replace", "move", "copy", or "test"; other values are errors.
-json.exception.parse_error.106 | parse error: array index '01' must not begin with '0' | An array index in a JSON Pointer ([RFC 6901](https://tools.ietf.org/html/rfc6901)) may be `0` or any number without a leading `0`.
-json.exception.parse_error.107 | parse error: JSON pointer must be empty or begin with '/' - was: 'foo' | A JSON Pointer must be a Unicode string containing a sequence of zero or more reference tokens, each prefixed by a `/` character.
-json.exception.parse_error.108 | parse error: escape character '~' must be followed with '0' or '1' | In a JSON Pointer, only `~0` and `~1` are valid escape sequences.
-json.exception.parse_error.109 | parse error: array index 'one' is not a number | A JSON Pointer array index must be a number.
-json.exception.parse_error.110 | parse error at 1: cannot read 2 bytes from vector | When parsing CBOR or MessagePack, the byte vector ends before the complete value has been read.
-json.exception.parse_error.112 | parse error at 1: error reading CBOR; last byte: 0xF8 | Not all types of CBOR or MessagePack are supported. This exception occurs if an unsupported byte was read.
-json.exception.parse_error.113 | parse error at 2: expected a CBOR string; last byte: 0x98 | While parsing a map key, a value that is not a string has been read.
-json.exception.parse_error.114 | parse error: Unsupported BSON record type 0x0F | The parsing of the corresponding BSON record type is not implemented (yet).
-json.exception.parse_error.115 | parse error at byte 5: syntax error while parsing UBJSON high-precision number: invalid number text: 1A | A UBJSON high-precision number could not be parsed.
-
-@note For an input with n bytes, 1 is the index of the first character and n+1
-      is the index of the terminating null byte or the end of file. This also
-      holds true when reading a byte vector (CBOR or MessagePack).
-
-@liveexample{The following code shows how a `parse_error` exception can be
-caught.,parse_error}
-
-@sa - @ref exception for the base class of the library exceptions
-@sa - @ref invalid_iterator for exceptions indicating errors with iterators
-@sa - @ref type_error for exceptions indicating executing a member function with
-                    a wrong type
-@sa - @ref out_of_range for exceptions indicating access out of the defined range
-@sa - @ref other_error for exceptions indicating other library errors
-
-@since version 3.0.0
-*/
-class parse_error : public exception
-{
-  public:
-    /*!
-    @brief create a parse error exception
-    @param[in] id_       the id of the exception
-    @param[in] pos       the position where the error occurred (or with
-                         chars_read_total=0 if the position cannot be
-                         determined)
-    @param[in] what_arg  the explanatory string
-    @return parse_error object
-    */
-    static parse_error create(int id_, const position_t& pos, const std::string& what_arg)
-    {
-        std::string w = exception::name("parse_error", id_) + "parse error" +
-                        position_string(pos) + ": " + what_arg;
-        return parse_error(id_, pos.chars_read_total, w.c_str());
-    }
-
-    static parse_error create(int id_, std::size_t byte_, const std::string& what_arg)
-    {
-        std::string w = exception::name("parse_error", id_) + "parse error" +
-                        (byte_ != 0 ? (" at byte " + std::to_string(byte_)) : "") +
-                        ": " + what_arg;
-        return parse_error(id_, byte_, w.c_str());
-    }
-
-    /*!
-    @brief byte index of the parse error
-
-    The byte index of the last read character in the input file.
-
-    @note For an input with n bytes, 1 is the index of the first character and
-          n+1 is the index of the terminating null byte or the end of file.
-          This also holds true when reading a byte vector (CBOR or MessagePack).
-    */
-    const std::size_t byte;
-
-  private:
-    parse_error(int id_, std::size_t byte_, const char* what_arg)
-        : exception(id_, what_arg), byte(byte_) {}
-
-    static std::string position_string(const position_t& pos)
-    {
-        return " at line " + std::to_string(pos.lines_read + 1) +
-               ", column " + std::to_string(pos.chars_read_current_line);
-    }
-};
-
-/*!
-@brief exception indicating errors with iterators
-
-This exception is thrown if iterators passed to a library function do not match
-the expected semantics.
-
-Exceptions have ids 2xx.
-
-name / id                           | example message | description
------------------------------------ | --------------- | -------------------------
-json.exception.invalid_iterator.201 | iterators are not compatible | The iterators passed to constructor @ref basic_json(InputIT first, InputIT last) are not compatible, meaning they do not belong to the same container. Therefore, the range (@a first, @a last) is invalid.
-json.exception.invalid_iterator.202 | iterator does not fit current value | In an erase or insert function, the passed iterator @a pos does not belong to the JSON value for which the function was called. It hence does not define a valid position for the deletion/insertion.
-json.exception.invalid_iterator.203 | iterators do not fit current value | Either iterator passed to function @ref erase(IteratorType first, IteratorType last) does not belong to the JSON value from which values shall be erased. It hence does not define a valid range to delete values from.
-json.exception.invalid_iterator.204 | iterators out of range | When an iterator range for a primitive type (number, boolean, or string) is passed to a constructor or an erase function, this range has to be exactly (@ref begin(), @ref end()), because this is the only way the single stored value is expressed. All other ranges are invalid.
-json.exception.invalid_iterator.205 | iterator out of range | When an iterator for a primitive type (number, boolean, or string) is passed to an erase function, the iterator has to be the @ref begin() iterator, because it is the only way to address the stored value. All other iterators are invalid.
-json.exception.invalid_iterator.206 | cannot construct with iterators from null | The iterators passed to constructor @ref basic_json(InputIT first, InputIT last) belong to a JSON null value and hence to not define a valid range.
-json.exception.invalid_iterator.207 | cannot use key() for non-object iterators | The key() member function can only be used on iterators belonging to a JSON object, because other types do not have a concept of a key.
-json.exception.invalid_iterator.208 | cannot use operator[] for object iterators | The operator[] to specify a concrete offset cannot be used on iterators belonging to a JSON object, because JSON objects are unordered.
-json.exception.invalid_iterator.209 | cannot use offsets with object iterators | The offset operators (+, -, +=, -=) cannot be used on iterators belonging to a JSON object, because JSON objects are unordered.
-json.exception.invalid_iterator.210 | iterators do not fit | The iterator range passed to the insert function are not compatible, meaning they do not belong to the same container. Therefore, the range (@a first, @a last) is invalid.
-json.exception.invalid_iterator.211 | passed iterators may not belong to container | The iterator range passed to the insert function must not be a subrange of the container to insert to.
-json.exception.invalid_iterator.212 | cannot compare iterators of different containers | When two iterators are compared, they must belong to the same container.
-json.exception.invalid_iterator.213 | cannot compare order of object iterators | The order of object iterators cannot be compared, because JSON objects are unordered.
-json.exception.invalid_iterator.214 | cannot get value | Cannot get value for iterator: Either the iterator belongs to a null value or it is an iterator to a primitive type (number, boolean, or string), but the iterator is different to @ref begin().
-
-@liveexample{The following code shows how an `invalid_iterator` exception can be
-caught.,invalid_iterator}
-
-@sa - @ref exception for the base class of the library exceptions
-@sa - @ref parse_error for exceptions indicating a parse error
-@sa - @ref type_error for exceptions indicating executing a member function with
-                    a wrong type
-@sa - @ref out_of_range for exceptions indicating access out of the defined range
-@sa - @ref other_error for exceptions indicating other library errors
-
-@since version 3.0.0
-*/
-class invalid_iterator : public exception
-{
-  public:
-    static invalid_iterator create(int id_, const std::string& what_arg)
-    {
-        std::string w = exception::name("invalid_iterator", id_) + what_arg;
-        return invalid_iterator(id_, w.c_str());
-    }
-
-  private:
-    JSON_HEDLEY_NON_NULL(3)
-    invalid_iterator(int id_, const char* what_arg)
-        : exception(id_, what_arg) {}
-};
-
-/*!
-@brief exception indicating executing a member function with a wrong type
-
-This exception is thrown in case of a type error; that is, a library function is
-executed on a JSON value whose type does not match the expected semantics.
-
-Exceptions have ids 3xx.
-
-name / id                     | example message | description
------------------------------ | --------------- | -------------------------
-json.exception.type_error.301 | cannot create object from initializer list | To create an object from an initializer list, the initializer list must consist only of a list of pairs whose first element is a string. When this constraint is violated, an array is created instead.
-json.exception.type_error.302 | type must be object, but is array | During implicit or explicit value conversion, the JSON type must be compatible to the target type. For instance, a JSON string can only be converted into string types, but not into numbers or boolean types.
-json.exception.type_error.303 | incompatible ReferenceType for get_ref, actual type is object | To retrieve a reference to a value stored in a @ref basic_json object with @ref get_ref, the type of the reference must match the value type. For instance, for a JSON array, the @a ReferenceType must be @ref array_t &.
-json.exception.type_error.304 | cannot use at() with string | The @ref at() member functions can only be executed for certain JSON types.
-json.exception.type_error.305 | cannot use operator[] with string | The @ref operator[] member functions can only be executed for certain JSON types.
-json.exception.type_error.306 | cannot use value() with string | The @ref value() member functions can only be executed for certain JSON types.
-json.exception.type_error.307 | cannot use erase() with string | The @ref erase() member functions can only be executed for certain JSON types.
-json.exception.type_error.308 | cannot use push_back() with string | The @ref push_back() and @ref operator+= member functions can only be executed for certain JSON types.
-json.exception.type_error.309 | cannot use insert() with | The @ref insert() member functions can only be executed for certain JSON types.
-json.exception.type_error.310 | cannot use swap() with number | The @ref swap() member functions can only be executed for certain JSON types.
-json.exception.type_error.311 | cannot use emplace_back() with string | The @ref emplace_back() member function can only be executed for certain JSON types.
-json.exception.type_error.312 | cannot use update() with string | The @ref update() member functions can only be executed for certain JSON types.
-json.exception.type_error.313 | invalid value to unflatten | The @ref unflatten function converts an object whose keys are JSON Pointers back into an arbitrary nested JSON value. The JSON Pointers must not overlap, because then the resulting value would not be well defined.
-json.exception.type_error.314 | only objects can be unflattened | The @ref unflatten function only works for an object whose keys are JSON Pointers.
-json.exception.type_error.315 | values in object must be primitive | The @ref unflatten function only works for an object whose keys are JSON Pointers and whose values are primitive.
-json.exception.type_error.316 | invalid UTF-8 byte at index 10: 0x7E | The @ref dump function only works with UTF-8 encoded strings; that is, if you assign a `std::string` to a JSON value, make sure it is UTF-8 encoded. |
-json.exception.type_error.317 | JSON value cannot be serialized to requested format | The dynamic type of the object cannot be represented in the requested serialization format (e.g. a raw `true` or `null` JSON object cannot be serialized to BSON) |
-
-@liveexample{The following code shows how a `type_error` exception can be
-caught.,type_error}
-
-@sa - @ref exception for the base class of the library exceptions
-@sa - @ref parse_error for exceptions indicating a parse error
-@sa - @ref invalid_iterator for exceptions indicating errors with iterators
-@sa - @ref out_of_range for exceptions indicating access out of the defined range
-@sa - @ref other_error for exceptions indicating other library errors
-
-@since version 3.0.0
-*/
-class type_error : public exception
-{
-  public:
-    static type_error create(int id_, const std::string& what_arg)
-    {
-        std::string w = exception::name("type_error", id_) + what_arg;
-        return type_error(id_, w.c_str());
-    }
-
-  private:
-    JSON_HEDLEY_NON_NULL(3)
-    type_error(int id_, const char* what_arg) : exception(id_, what_arg) {}
-};
-
-/*!
-@brief exception indicating access out of the defined range
-
-This exception is thrown in case a library function is called on an input
-parameter that exceeds the expected range, for instance in case of array
-indices or nonexisting object keys.
-
-Exceptions have ids 4xx.
-
-name / id                       | example message | description
-------------------------------- | --------------- | -------------------------
-json.exception.out_of_range.401 | array index 3 is out of range | The provided array index @a i is larger than @a size-1.
-json.exception.out_of_range.402 | array index '-' (3) is out of range | The special array index `-` in a JSON Pointer never describes a valid element of the array, but the index past the end. That is, it can only be used to add elements at this position, but not to read it.
-json.exception.out_of_range.403 | key 'foo' not found | The provided key was not found in the JSON object.
-json.exception.out_of_range.404 | unresolved reference token 'foo' | A reference token in a JSON Pointer could not be resolved.
-json.exception.out_of_range.405 | JSON pointer has no parent | The JSON Patch operations 'remove' and 'add' can not be applied to the root element of the JSON value.
-json.exception.out_of_range.406 | number overflow parsing '10E1000' | A parsed number could not be stored as without changing it to NaN or INF.
-json.exception.out_of_range.407 | number overflow serializing '9223372036854775808' | UBJSON and BSON only support integer numbers up to 9223372036854775807. (until version 3.8.0) |
-json.exception.out_of_range.408 | excessive array size: 8658170730974374167 | The size (following `#`) of an UBJSON array or object exceeds the maximal capacity. |
-json.exception.out_of_range.409 | BSON key cannot contain code point U+0000 (at byte 2) | Key identifiers to be serialized to BSON cannot contain code point U+0000, since the key is stored as zero-terminated c-string |
-
-@liveexample{The following code shows how an `out_of_range` exception can be
-caught.,out_of_range}
-
-@sa - @ref exception for the base class of the library exceptions
-@sa - @ref parse_error for exceptions indicating a parse error
-@sa - @ref invalid_iterator for exceptions indicating errors with iterators
-@sa - @ref type_error for exceptions indicating executing a member function with
-                    a wrong type
-@sa - @ref other_error for exceptions indicating other library errors
-
-@since version 3.0.0
-*/
-class out_of_range : public exception
-{
-  public:
-    static out_of_range create(int id_, const std::string& what_arg)
-    {
-        std::string w = exception::name("out_of_range", id_) + what_arg;
-        return out_of_range(id_, w.c_str());
-    }
-
-  private:
-    JSON_HEDLEY_NON_NULL(3)
-    out_of_range(int id_, const char* what_arg) : exception(id_, what_arg) {}
-};
-
-/*!
-@brief exception indicating other library errors
-
-This exception is thrown in case of errors that cannot be classified with the
-other exception types.
-
-Exceptions have ids 5xx.
-
-name / id                      | example message | description
------------------------------- | --------------- | -------------------------
-json.exception.other_error.501 | unsuccessful: {"op":"test","path":"/baz", "value":"bar"} | A JSON Patch operation 'test' failed. The unsuccessful operation is also printed.
-
-@sa - @ref exception for the base class of the library exceptions
-@sa - @ref parse_error for exceptions indicating a parse error
-@sa - @ref invalid_iterator for exceptions indicating errors with iterators
-@sa - @ref type_error for exceptions indicating executing a member function with
-                    a wrong type
-@sa - @ref out_of_range for exceptions indicating access out of the defined range
-
-@liveexample{The following code shows how an `other_error` exception can be
-caught.,other_error}
-
-@since version 3.0.0
-*/
-class other_error : public exception
-{
-  public:
-    static other_error create(int id_, const std::string& what_arg)
-    {
-        std::string w = exception::name("other_error", id_) + what_arg;
-        return other_error(id_, w.c_str());
-    }
-
-  private:
-    JSON_HEDLEY_NON_NULL(3)
-    other_error(int id_, const char* what_arg) : exception(id_, what_arg) {}
-};
-}  // namespace detail
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/macro_scope.hpp>
-
-// #include <nlohmann/detail/meta/cpp_future.hpp>
-
-
-#include <cstddef> // size_t
-#include <type_traits> // conditional, enable_if, false_type, integral_constant, is_constructible, is_integral, is_same, remove_cv, remove_reference, true_type
-
-namespace nlohmann
-{
-namespace detail
-{
-// alias templates to reduce boilerplate
-template<bool B, typename T = void>
-using enable_if_t = typename std::enable_if<B, T>::type;
-
-template<typename T>
-using uncvref_t = typename std::remove_cv<typename std::remove_reference<T>::type>::type;
-
-// implementation of C++14 index_sequence and affiliates
-// source: https://stackoverflow.com/a/32223343
-template<std::size_t... Ints>
-struct index_sequence
-{
-    using type = index_sequence;
-    using value_type = std::size_t;
-    static constexpr std::size_t size() noexcept
-    {
-        return sizeof...(Ints);
-    }
-};
-
-template<class Sequence1, class Sequence2>
-struct merge_and_renumber;
-
-template<std::size_t... I1, std::size_t... I2>
-struct merge_and_renumber<index_sequence<I1...>, index_sequence<I2...>>
-        : index_sequence < I1..., (sizeof...(I1) + I2)... > {};
-
-template<std::size_t N>
-struct make_index_sequence
-    : merge_and_renumber < typename make_index_sequence < N / 2 >::type,
-      typename make_index_sequence < N - N / 2 >::type > {};
-
-template<> struct make_index_sequence<0> : index_sequence<> {};
-template<> struct make_index_sequence<1> : index_sequence<0> {};
-
-template<typename... Ts>
-using index_sequence_for = make_index_sequence<sizeof...(Ts)>;
-
-// dispatch utility (taken from ranges-v3)
-template<unsigned N> struct priority_tag : priority_tag < N - 1 > {};
-template<> struct priority_tag<0> {};
-
-// taken from ranges-v3
-template<typename T>
-struct static_const
-{
-    static constexpr T value{};
-};
-
-template<typename T>
-constexpr T static_const<T>::value;
-}  // namespace detail
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/meta/type_traits.hpp>
-
-
-#include <limits> // numeric_limits
-#include <type_traits> // false_type, is_constructible, is_integral, is_same, true_type
-#include <utility> // declval
-
-// #include <nlohmann/detail/iterators/iterator_traits.hpp>
-
-
-#include <iterator> // random_access_iterator_tag
-
-// #include <nlohmann/detail/meta/void_t.hpp>
-
-
-namespace nlohmann
-{
-namespace detail
-{
-template<typename ...Ts> struct make_void
-{
-    using type = void;
-};
-template<typename ...Ts> using void_t = typename make_void<Ts...>::type;
-} // namespace detail
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/meta/cpp_future.hpp>
-
-
-namespace nlohmann
-{
-namespace detail
-{
-template<typename It, typename = void>
-struct iterator_types {};
-
-template<typename It>
-struct iterator_types <
-    It,
-    void_t<typename It::difference_type, typename It::value_type, typename It::pointer,
-    typename It::reference, typename It::iterator_category >>
-{
-    using difference_type = typename It::difference_type;
-    using value_type = typename It::value_type;
-    using pointer = typename It::pointer;
-    using reference = typename It::reference;
-    using iterator_category = typename It::iterator_category;
-};
-
-// This is required as some compilers implement std::iterator_traits in a way that
-// doesn't work with SFINAE. See https://github.com/nlohmann/json/issues/1341.
-template<typename T, typename = void>
-struct iterator_traits
-{
-};
-
-template<typename T>
-struct iterator_traits < T, enable_if_t < !std::is_pointer<T>::value >>
-            : iterator_types<T>
-{
-};
-
-template<typename T>
-struct iterator_traits<T*, enable_if_t<std::is_object<T>::value>>
-{
-    using iterator_category = std::random_access_iterator_tag;
-    using value_type = T;
-    using difference_type = ptrdiff_t;
-    using pointer = T*;
-    using reference = T&;
-};
-} // namespace detail
-} // namespace nlohmann
-
-// #include <nlohmann/detail/macro_scope.hpp>
-
-// #include <nlohmann/detail/meta/cpp_future.hpp>
-
-// #include <nlohmann/detail/meta/detected.hpp>
-
-
-#include <type_traits>
-
-// #include <nlohmann/detail/meta/void_t.hpp>
-
-
-// https://en.cppreference.com/w/cpp/experimental/is_detected
-namespace nlohmann
-{
-namespace detail
-{
-struct nonesuch
-{
-    nonesuch() = delete;
-    ~nonesuch() = delete;
-    nonesuch(nonesuch const&) = delete;
-    nonesuch(nonesuch const&&) = delete;
-    void operator=(nonesuch const&) = delete;
-    void operator=(nonesuch&&) = delete;
-};
-
-template<class Default,
-         class AlwaysVoid,
-         template<class...> class Op,
-         class... Args>
-struct detector
-{
-    using value_t = std::false_type;
-    using type = Default;
-};
-
-template<class Default, template<class...> class Op, class... Args>
-struct detector<Default, void_t<Op<Args...>>, Op, Args...>
-{
-    using value_t = std::true_type;
-    using type = Op<Args...>;
-};
-
-template<template<class...> class Op, class... Args>
-using is_detected = typename detector<nonesuch, void, Op, Args...>::value_t;
-
-template<template<class...> class Op, class... Args>
-using detected_t = typename detector<nonesuch, void, Op, Args...>::type;
-
-template<class Default, template<class...> class Op, class... Args>
-using detected_or = detector<Default, void, Op, Args...>;
-
-template<class Default, template<class...> class Op, class... Args>
-using detected_or_t = typename detected_or<Default, Op, Args...>::type;
-
-template<class Expected, template<class...> class Op, class... Args>
-using is_detected_exact = std::is_same<Expected, detected_t<Op, Args...>>;
-
-template<class To, template<class...> class Op, class... Args>
-using is_detected_convertible =
-    std::is_convertible<detected_t<Op, Args...>, To>;
-}  // namespace detail
-}  // namespace nlohmann
-
-// #include <nlohmann/json_fwd.hpp>
-#ifndef INCLUDE_NLOHMANN_JSON_FWD_HPP_
-#define INCLUDE_NLOHMANN_JSON_FWD_HPP_
-
-#include <cstdint> // int64_t, uint64_t
-#include <map> // map
-#include <memory> // allocator
-#include <string> // string
-#include <vector> // vector
-
-/*!
-@brief namespace for Niels Lohmann
-@see https://github.com/nlohmann
-@since version 1.0.0
-*/
-namespace nlohmann
-{
-/*!
-@brief default JSONSerializer template argument
-
-This serializer ignores the template arguments and uses ADL
-([argument-dependent lookup](https://en.cppreference.com/w/cpp/language/adl))
-for serialization.
-*/
-template<typename T = void, typename SFINAE = void>
-struct adl_serializer;
-
-template<template<typename U, typename V, typename... Args> class ObjectType =
-         std::map,
-         template<typename U, typename... Args> class ArrayType = std::vector,
-         class StringType = std::string, class BooleanType = bool,
-         class NumberIntegerType = std::int64_t,
-         class NumberUnsignedType = std::uint64_t,
-         class NumberFloatType = double,
-         template<typename U> class AllocatorType = std::allocator,
-         template<typename T, typename SFINAE = void> class JSONSerializer =
-         adl_serializer,
-         class BinaryType = std::vector<std::uint8_t>>
-class basic_json;
-
-/*!
-@brief JSON Pointer
-
-A JSON pointer defines a string syntax for identifying a specific value
-within a JSON document. It can be used with functions `at` and
-`operator[]`. Furthermore, JSON pointers are the base for JSON patches.
-
-@sa [RFC 6901](https://tools.ietf.org/html/rfc6901)
-
-@since version 2.0.0
-*/
-template<typename BasicJsonType>
-class json_pointer;
-
-/*!
-@brief default JSON class
-
-This type is the default specialization of the @ref basic_json class which
-uses the standard template types.
-
-@since version 1.0.0
-*/
-using json = basic_json<>;
-
-template<class Key, class T, class IgnoredLess, class Allocator>
-struct ordered_map;
-
-/*!
-@brief ordered JSON class
-
-This type preserves the insertion order of object keys.
-
-@since version 3.9.0
-*/
-using ordered_json = basic_json<nlohmann::ordered_map>;
-
-}  // namespace nlohmann
-
-#endif  // INCLUDE_NLOHMANN_JSON_FWD_HPP_
-
-
-namespace nlohmann
-{
-/*!
-@brief detail namespace with internal helper functions
-
-This namespace collects functions that should not be exposed,
-implementations of some @ref basic_json methods, and meta-programming helpers.
-
-@since version 2.1.0
-*/
-namespace detail
-{
-/////////////
-// helpers //
-/////////////
-
-// Note to maintainers:
-//
-// Every trait in this file expects a non CV-qualified type.
-// The only exceptions are in the 'aliases for detected' section
-// (i.e. those of the form: decltype(T::member_function(std::declval<T>())))
-//
-// In this case, T has to be properly CV-qualified to constraint the function arguments
-// (e.g. to_json(BasicJsonType&, const T&))
-
-template<typename> struct is_basic_json : std::false_type {};
-
-NLOHMANN_BASIC_JSON_TPL_DECLARATION
-struct is_basic_json<NLOHMANN_BASIC_JSON_TPL> : std::true_type {};
-
-//////////////////////
-// json_ref helpers //
-//////////////////////
-
-template<typename>
-class json_ref;
-
-template<typename>
-struct is_json_ref : std::false_type {};
-
-template<typename T>
-struct is_json_ref<json_ref<T>> : std::true_type {};
-
-//////////////////////////
-// aliases for detected //
-//////////////////////////
-
-template<typename T>
-using mapped_type_t = typename T::mapped_type;
-
-template<typename T>
-using key_type_t = typename T::key_type;
-
-template<typename T>
-using value_type_t = typename T::value_type;
-
-template<typename T>
-using difference_type_t = typename T::difference_type;
-
-template<typename T>
-using pointer_t = typename T::pointer;
-
-template<typename T>
-using reference_t = typename T::reference;
-
-template<typename T>
-using iterator_category_t = typename T::iterator_category;
-
-template<typename T>
-using iterator_t = typename T::iterator;
-
-template<typename T, typename... Args>
-using to_json_function = decltype(T::to_json(std::declval<Args>()...));
-
-template<typename T, typename... Args>
-using from_json_function = decltype(T::from_json(std::declval<Args>()...));
-
-template<typename T, typename U>
-using get_template_function = decltype(std::declval<T>().template get<U>());
-
-// trait checking if JSONSerializer<T>::from_json(json const&, udt&) exists
-template<typename BasicJsonType, typename T, typename = void>
-struct has_from_json : std::false_type {};
-
-// trait checking if j.get<T> is valid
-// use this trait instead of std::is_constructible or std::is_convertible,
-// both rely on, or make use of implicit conversions, and thus fail when T
-// has several constructors/operator= (see https://github.com/nlohmann/json/issues/958)
-template <typename BasicJsonType, typename T>
-struct is_getable
-{
-    static constexpr bool value = is_detected<get_template_function, const BasicJsonType&, T>::value;
-};
-
-template<typename BasicJsonType, typename T>
-struct has_from_json < BasicJsonType, T,
-           enable_if_t < !is_basic_json<T>::value >>
-{
-    using serializer = typename BasicJsonType::template json_serializer<T, void>;
-
-    static constexpr bool value =
-        is_detected_exact<void, from_json_function, serializer,
-        const BasicJsonType&, T&>::value;
-};
-
-// This trait checks if JSONSerializer<T>::from_json(json const&) exists
-// this overload is used for non-default-constructible user-defined-types
-template<typename BasicJsonType, typename T, typename = void>
-struct has_non_default_from_json : std::false_type {};
-
-template<typename BasicJsonType, typename T>
-struct has_non_default_from_json < BasicJsonType, T, enable_if_t < !is_basic_json<T>::value >>
-{
-    using serializer = typename BasicJsonType::template json_serializer<T, void>;
-
-    static constexpr bool value =
-        is_detected_exact<T, from_json_function, serializer,
-        const BasicJsonType&>::value;
-};
-
-// This trait checks if BasicJsonType::json_serializer<T>::to_json exists
-// Do not evaluate the trait when T is a basic_json type, to avoid template instantiation infinite recursion.
-template<typename BasicJsonType, typename T, typename = void>
-struct has_to_json : std::false_type {};
-
-template<typename BasicJsonType, typename T>
-struct has_to_json < BasicJsonType, T, enable_if_t < !is_basic_json<T>::value >>
-{
-    using serializer = typename BasicJsonType::template json_serializer<T, void>;
-
-    static constexpr bool value =
-        is_detected_exact<void, to_json_function, serializer, BasicJsonType&,
-        T>::value;
-};
-
-
-///////////////////
-// is_ functions //
-///////////////////
-
-template<typename T, typename = void>
-struct is_iterator_traits : std::false_type {};
-
-template<typename T>
-struct is_iterator_traits<iterator_traits<T>>
-{
-  private:
-    using traits = iterator_traits<T>;
-
-  public:
-    static constexpr auto value =
-        is_detected<value_type_t, traits>::value &&
-        is_detected<difference_type_t, traits>::value &&
-        is_detected<pointer_t, traits>::value &&
-        is_detected<iterator_category_t, traits>::value &&
-        is_detected<reference_t, traits>::value;
-};
-
-// source: https://stackoverflow.com/a/37193089/4116453
-
-template<typename T, typename = void>
-struct is_complete_type : std::false_type {};
-
-template<typename T>
-struct is_complete_type<T, decltype(void(sizeof(T)))> : std::true_type {};
-
-template<typename BasicJsonType, typename CompatibleObjectType,
-         typename = void>
-struct is_compatible_object_type_impl : std::false_type {};
-
-template<typename BasicJsonType, typename CompatibleObjectType>
-struct is_compatible_object_type_impl <
-    BasicJsonType, CompatibleObjectType,
-    enable_if_t < is_detected<mapped_type_t, CompatibleObjectType>::value&&
-    is_detected<key_type_t, CompatibleObjectType>::value >>
-{
-
-    using object_t = typename BasicJsonType::object_t;
-
-    // macOS's is_constructible does not play well with nonesuch...
-    static constexpr bool value =
-        std::is_constructible<typename object_t::key_type,
-        typename CompatibleObjectType::key_type>::value &&
-        std::is_constructible<typename object_t::mapped_type,
-        typename CompatibleObjectType::mapped_type>::value;
-};
-
-template<typename BasicJsonType, typename CompatibleObjectType>
-struct is_compatible_object_type
-    : is_compatible_object_type_impl<BasicJsonType, CompatibleObjectType> {};
-
-template<typename BasicJsonType, typename ConstructibleObjectType,
-         typename = void>
-struct is_constructible_object_type_impl : std::false_type {};
-
-template<typename BasicJsonType, typename ConstructibleObjectType>
-struct is_constructible_object_type_impl <
-    BasicJsonType, ConstructibleObjectType,
-    enable_if_t < is_detected<mapped_type_t, ConstructibleObjectType>::value&&
-    is_detected<key_type_t, ConstructibleObjectType>::value >>
-{
-    using object_t = typename BasicJsonType::object_t;
-
-    static constexpr bool value =
-        (std::is_default_constructible<ConstructibleObjectType>::value &&
-         (std::is_move_assignable<ConstructibleObjectType>::value ||
-          std::is_copy_assignable<ConstructibleObjectType>::value) &&
-         (std::is_constructible<typename ConstructibleObjectType::key_type,
-          typename object_t::key_type>::value &&
-          std::is_same <
-          typename object_t::mapped_type,
-          typename ConstructibleObjectType::mapped_type >::value)) ||
-        (has_from_json<BasicJsonType,
-         typename ConstructibleObjectType::mapped_type>::value ||
-         has_non_default_from_json <
-         BasicJsonType,
-         typename ConstructibleObjectType::mapped_type >::value);
-};
-
-template<typename BasicJsonType, typename ConstructibleObjectType>
-struct is_constructible_object_type
-    : is_constructible_object_type_impl<BasicJsonType,
-      ConstructibleObjectType> {};
-
-template<typename BasicJsonType, typename CompatibleStringType,
-         typename = void>
-struct is_compatible_string_type_impl : std::false_type {};
-
-template<typename BasicJsonType, typename CompatibleStringType>
-struct is_compatible_string_type_impl <
-    BasicJsonType, CompatibleStringType,
-    enable_if_t<is_detected_exact<typename BasicJsonType::string_t::value_type,
-    value_type_t, CompatibleStringType>::value >>
-{
-    static constexpr auto value =
-        std::is_constructible<typename BasicJsonType::string_t, CompatibleStringType>::value;
-};
-
-template<typename BasicJsonType, typename ConstructibleStringType>
-struct is_compatible_string_type
-    : is_compatible_string_type_impl<BasicJsonType, ConstructibleStringType> {};
-
-template<typename BasicJsonType, typename ConstructibleStringType,
-         typename = void>
-struct is_constructible_string_type_impl : std::false_type {};
-
-template<typename BasicJsonType, typename ConstructibleStringType>
-struct is_constructible_string_type_impl <
-    BasicJsonType, ConstructibleStringType,
-    enable_if_t<is_detected_exact<typename BasicJsonType::string_t::value_type,
-    value_type_t, ConstructibleStringType>::value >>
-{
-    static constexpr auto value =
-        std::is_constructible<ConstructibleStringType,
-        typename BasicJsonType::string_t>::value;
-};
-
-template<typename BasicJsonType, typename ConstructibleStringType>
-struct is_constructible_string_type
-    : is_constructible_string_type_impl<BasicJsonType, ConstructibleStringType> {};
-
-template<typename BasicJsonType, typename CompatibleArrayType, typename = void>
-struct is_compatible_array_type_impl : std::false_type {};
-
-template<typename BasicJsonType, typename CompatibleArrayType>
-struct is_compatible_array_type_impl <
-    BasicJsonType, CompatibleArrayType,
-    enable_if_t < is_detected<value_type_t, CompatibleArrayType>::value&&
-    is_detected<iterator_t, CompatibleArrayType>::value&&
-// This is needed because json_reverse_iterator has a ::iterator type...
-// Therefore it is detected as a CompatibleArrayType.
-// The real fix would be to have an Iterable concept.
-    !is_iterator_traits <
-    iterator_traits<CompatibleArrayType >>::value >>
-{
-    static constexpr bool value =
-        std::is_constructible<BasicJsonType,
-        typename CompatibleArrayType::value_type>::value;
-};
-
-template<typename BasicJsonType, typename CompatibleArrayType>
-struct is_compatible_array_type
-    : is_compatible_array_type_impl<BasicJsonType, CompatibleArrayType> {};
-
-template<typename BasicJsonType, typename ConstructibleArrayType, typename = void>
-struct is_constructible_array_type_impl : std::false_type {};
-
-template<typename BasicJsonType, typename ConstructibleArrayType>
-struct is_constructible_array_type_impl <
-    BasicJsonType, ConstructibleArrayType,
-    enable_if_t<std::is_same<ConstructibleArrayType,
-    typename BasicJsonType::value_type>::value >>
-            : std::true_type {};
-
-template<typename BasicJsonType, typename ConstructibleArrayType>
-struct is_constructible_array_type_impl <
-    BasicJsonType, ConstructibleArrayType,
-    enable_if_t < !std::is_same<ConstructibleArrayType,
-    typename BasicJsonType::value_type>::value&&
-    std::is_default_constructible<ConstructibleArrayType>::value&&
-(std::is_move_assignable<ConstructibleArrayType>::value ||
- std::is_copy_assignable<ConstructibleArrayType>::value)&&
-is_detected<value_type_t, ConstructibleArrayType>::value&&
-is_detected<iterator_t, ConstructibleArrayType>::value&&
-is_complete_type <
-detected_t<value_type_t, ConstructibleArrayType >>::value >>
-{
-    static constexpr bool value =
-        // This is needed because json_reverse_iterator has a ::iterator type,
-        // furthermore, std::back_insert_iterator (and other iterators) have a
-        // base class `iterator`... Therefore it is detected as a
-        // ConstructibleArrayType. The real fix would be to have an Iterable
-        // concept.
-        !is_iterator_traits<iterator_traits<ConstructibleArrayType>>::value &&
-
-        (std::is_same<typename ConstructibleArrayType::value_type,
-         typename BasicJsonType::array_t::value_type>::value ||
-         has_from_json<BasicJsonType,
-         typename ConstructibleArrayType::value_type>::value ||
-         has_non_default_from_json <
-         BasicJsonType, typename ConstructibleArrayType::value_type >::value);
-};
-
-template<typename BasicJsonType, typename ConstructibleArrayType>
-struct is_constructible_array_type
-    : is_constructible_array_type_impl<BasicJsonType, ConstructibleArrayType> {};
-
-template<typename RealIntegerType, typename CompatibleNumberIntegerType,
-         typename = void>
-struct is_compatible_integer_type_impl : std::false_type {};
-
-template<typename RealIntegerType, typename CompatibleNumberIntegerType>
-struct is_compatible_integer_type_impl <
-    RealIntegerType, CompatibleNumberIntegerType,
-    enable_if_t < std::is_integral<RealIntegerType>::value&&
-    std::is_integral<CompatibleNumberIntegerType>::value&&
-    !std::is_same<bool, CompatibleNumberIntegerType>::value >>
-{
-    // is there an assert somewhere on overflows?
-    using RealLimits = std::numeric_limits<RealIntegerType>;
-    using CompatibleLimits = std::numeric_limits<CompatibleNumberIntegerType>;
-
-    static constexpr auto value =
-        std::is_constructible<RealIntegerType,
-        CompatibleNumberIntegerType>::value &&
-        CompatibleLimits::is_integer &&
-        RealLimits::is_signed == CompatibleLimits::is_signed;
-};
-
-template<typename RealIntegerType, typename CompatibleNumberIntegerType>
-struct is_compatible_integer_type
-    : is_compatible_integer_type_impl<RealIntegerType,
-      CompatibleNumberIntegerType> {};
-
-template<typename BasicJsonType, typename CompatibleType, typename = void>
-struct is_compatible_type_impl: std::false_type {};
-
-template<typename BasicJsonType, typename CompatibleType>
-struct is_compatible_type_impl <
-    BasicJsonType, CompatibleType,
-    enable_if_t<is_complete_type<CompatibleType>::value >>
-{
-    static constexpr bool value =
-        has_to_json<BasicJsonType, CompatibleType>::value;
-};
-
-template<typename BasicJsonType, typename CompatibleType>
-struct is_compatible_type
-    : is_compatible_type_impl<BasicJsonType, CompatibleType> {};
-
-// https://en.cppreference.com/w/cpp/types/conjunction
-template<class...> struct conjunction : std::true_type { };
-template<class B1> struct conjunction<B1> : B1 { };
-template<class B1, class... Bn>
-struct conjunction<B1, Bn...>
-: std::conditional<bool(B1::value), conjunction<Bn...>, B1>::type {};
-
-template<typename T1, typename T2>
-struct is_constructible_tuple : std::false_type {};
-
-template<typename T1, typename... Args>
-struct is_constructible_tuple<T1, std::tuple<Args...>> : conjunction<std::is_constructible<T1, Args>...> {};
-}  // namespace detail
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/value_t.hpp>
-
-
-#include <array> // array
-#include <cstddef> // size_t
-#include <cstdint> // uint8_t
-#include <string> // string
-
-namespace nlohmann
-{
-namespace detail
-{
-///////////////////////////
-// JSON type enumeration //
-///////////////////////////
-
-/*!
-@brief the JSON type enumeration
-
-This enumeration collects the different JSON types. It is internally used to
-distinguish the stored values, and the functions @ref basic_json::is_null(),
-@ref basic_json::is_object(), @ref basic_json::is_array(),
-@ref basic_json::is_string(), @ref basic_json::is_boolean(),
-@ref basic_json::is_number() (with @ref basic_json::is_number_integer(),
-@ref basic_json::is_number_unsigned(), and @ref basic_json::is_number_float()),
-@ref basic_json::is_discarded(), @ref basic_json::is_primitive(), and
-@ref basic_json::is_structured() rely on it.
-
-@note There are three enumeration entries (number_integer, number_unsigned, and
-number_float), because the library distinguishes these three types for numbers:
-@ref basic_json::number_unsigned_t is used for unsigned integers,
-@ref basic_json::number_integer_t is used for signed integers, and
-@ref basic_json::number_float_t is used for floating-point numbers or to
-approximate integers which do not fit in the limits of their respective type.
-
-@sa @ref basic_json::basic_json(const value_t value_type) -- create a JSON
-value with the default value for a given type
-
-@since version 1.0.0
-*/
-enum class value_t : std::uint8_t
-{
-    null,             ///< null value
-    object,           ///< object (unordered set of name/value pairs)
-    array,            ///< array (ordered collection of values)
-    string,           ///< string value
-    boolean,          ///< boolean value
-    number_integer,   ///< number value (signed integer)
-    number_unsigned,  ///< number value (unsigned integer)
-    number_float,     ///< number value (floating-point)
-    binary,           ///< binary array (ordered collection of bytes)
-    discarded         ///< discarded by the parser callback function
-};
-
-/*!
-@brief comparison operator for JSON types
-
-Returns an ordering that is similar to Python:
-- order: null < boolean < number < object < array < string < binary
-- furthermore, each type is not smaller than itself
-- discarded values are not comparable
-- binary is represented as a b"" string in python and directly comparable to a
-  string; however, making a binary array directly comparable with a string would
-  be surprising behavior in a JSON file.
-
-@since version 1.0.0
-*/
-inline bool operator<(const value_t lhs, const value_t rhs) noexcept
-{
-    static constexpr std::array<std::uint8_t, 9> order = {{
-            0 /* null */, 3 /* object */, 4 /* array */, 5 /* string */,
-            1 /* boolean */, 2 /* integer */, 2 /* unsigned */, 2 /* float */,
-            6 /* binary */
-        }
-    };
-
-    const auto l_index = static_cast<std::size_t>(lhs);
-    const auto r_index = static_cast<std::size_t>(rhs);
-    return l_index < order.size() && r_index < order.size() && order[l_index] < order[r_index];
-}
-}  // namespace detail
-}  // namespace nlohmann
-
-
-namespace nlohmann
-{
-namespace detail
-{
-template<typename BasicJsonType>
-void from_json(const BasicJsonType& j, typename std::nullptr_t& n)
-{
-    if (JSON_HEDLEY_UNLIKELY(!j.is_null()))
-    {
-        JSON_THROW(type_error::create(302, "type must be null, but is " + std::string(j.type_name())));
-    }
-    n = nullptr;
-}
-
-// overloads for basic_json template parameters
-template < typename BasicJsonType, typename ArithmeticType,
-           enable_if_t < std::is_arithmetic<ArithmeticType>::value&&
-                         !std::is_same<ArithmeticType, typename BasicJsonType::boolean_t>::value,
-                         int > = 0 >
-void get_arithmetic_value(const BasicJsonType& j, ArithmeticType& val)
-{
-    switch (static_cast<value_t>(j))
-    {
-        case value_t::number_unsigned:
-        {
-            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>());
-            break;
-        }
-        case value_t::number_integer:
-        {
-            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_integer_t*>());
-            break;
-        }
-        case value_t::number_float:
-        {
-            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_float_t*>());
-            break;
-        }
-
-        default:
-            JSON_THROW(type_error::create(302, "type must be number, but is " + std::string(j.type_name())));
-    }
-}
-
-template<typename BasicJsonType>
-void from_json(const BasicJsonType& j, typename BasicJsonType::boolean_t& b)
-{
-    if (JSON_HEDLEY_UNLIKELY(!j.is_boolean()))
-    {
-        JSON_THROW(type_error::create(302, "type must be boolean, but is " + std::string(j.type_name())));
-    }
-    b = *j.template get_ptr<const typename BasicJsonType::boolean_t*>();
-}
-
-template<typename BasicJsonType>
-void from_json(const BasicJsonType& j, typename BasicJsonType::string_t& s)
-{
-    if (JSON_HEDLEY_UNLIKELY(!j.is_string()))
-    {
-        JSON_THROW(type_error::create(302, "type must be string, but is " + std::string(j.type_name())));
-    }
-    s = *j.template get_ptr<const typename BasicJsonType::string_t*>();
-}
-
-template <
-    typename BasicJsonType, typename ConstructibleStringType,
-    enable_if_t <
-        is_constructible_string_type<BasicJsonType, ConstructibleStringType>::value&&
-        !std::is_same<typename BasicJsonType::string_t,
-                      ConstructibleStringType>::value,
-        int > = 0 >
-void from_json(const BasicJsonType& j, ConstructibleStringType& s)
-{
-    if (JSON_HEDLEY_UNLIKELY(!j.is_string()))
-    {
-        JSON_THROW(type_error::create(302, "type must be string, but is " + std::string(j.type_name())));
-    }
-
-    s = *j.template get_ptr<const typename BasicJsonType::string_t*>();
-}
-
-template<typename BasicJsonType>
-void from_json(const BasicJsonType& j, typename BasicJsonType::number_float_t& val)
-{
-    get_arithmetic_value(j, val);
-}
-
-template<typename BasicJsonType>
-void from_json(const BasicJsonType& j, typename BasicJsonType::number_unsigned_t& val)
-{
-    get_arithmetic_value(j, val);
-}
-
-template<typename BasicJsonType>
-void from_json(const BasicJsonType& j, typename BasicJsonType::number_integer_t& val)
-{
-    get_arithmetic_value(j, val);
-}
-
-template<typename BasicJsonType, typename EnumType,
-         enable_if_t<std::is_enum<EnumType>::value, int> = 0>
-void from_json(const BasicJsonType& j, EnumType& e)
-{
-    typename std::underlying_type<EnumType>::type val;
-    get_arithmetic_value(j, val);
-    e = static_cast<EnumType>(val);
-}
-
-// forward_list doesn't have an insert method
-template<typename BasicJsonType, typename T, typename Allocator,
-         enable_if_t<is_getable<BasicJsonType, T>::value, int> = 0>
-void from_json(const BasicJsonType& j, std::forward_list<T, Allocator>& l)
-{
-    if (JSON_HEDLEY_UNLIKELY(!j.is_array()))
-    {
-        JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name())));
-    }
-    l.clear();
-    std::transform(j.rbegin(), j.rend(),
-                   std::front_inserter(l), [](const BasicJsonType & i)
-    {
-        return i.template get<T>();
-    });
-}
-
-// valarray doesn't have an insert method
-template<typename BasicJsonType, typename T,
-         enable_if_t<is_getable<BasicJsonType, T>::value, int> = 0>
-void from_json(const BasicJsonType& j, std::valarray<T>& l)
-{
-    if (JSON_HEDLEY_UNLIKELY(!j.is_array()))
-    {
-        JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name())));
-    }
-    l.resize(j.size());
-    std::transform(j.begin(), j.end(), std::begin(l),
-                   [](const BasicJsonType & elem)
-    {
-        return elem.template get<T>();
-    });
-}
-
-template<typename BasicJsonType, typename T, std::size_t N>
-auto from_json(const BasicJsonType& j, T (&arr)[N])
--> decltype(j.template get<T>(), void())
-{
-    for (std::size_t i = 0; i < N; ++i)
-    {
-        arr[i] = j.at(i).template get<T>();
-    }
-}
-
-template<typename BasicJsonType>
-void from_json_array_impl(const BasicJsonType& j, typename BasicJsonType::array_t& arr, priority_tag<3> /*unused*/)
-{
-    arr = *j.template get_ptr<const typename BasicJsonType::array_t*>();
-}
-
-template<typename BasicJsonType, typename T, std::size_t N>
-auto from_json_array_impl(const BasicJsonType& j, std::array<T, N>& arr,
-                          priority_tag<2> /*unused*/)
--> decltype(j.template get<T>(), void())
-{
-    for (std::size_t i = 0; i < N; ++i)
-    {
-        arr[i] = j.at(i).template get<T>();
-    }
-}
-
-template<typename BasicJsonType, typename ConstructibleArrayType>
-auto from_json_array_impl(const BasicJsonType& j, ConstructibleArrayType& arr, priority_tag<1> /*unused*/)
--> decltype(
-    arr.reserve(std::declval<typename ConstructibleArrayType::size_type>()),
-    j.template get<typename ConstructibleArrayType::value_type>(),
-    void())
-{
-    using std::end;
-
-    ConstructibleArrayType ret;
-    ret.reserve(j.size());
-    std::transform(j.begin(), j.end(),
-                   std::inserter(ret, end(ret)), [](const BasicJsonType & i)
-    {
-        // get<BasicJsonType>() returns *this, this won't call a from_json
-        // method when value_type is BasicJsonType
-        return i.template get<typename ConstructibleArrayType::value_type>();
-    });
-    arr = std::move(ret);
-}
-
-template<typename BasicJsonType, typename ConstructibleArrayType>
-void from_json_array_impl(const BasicJsonType& j, ConstructibleArrayType& arr,
-                          priority_tag<0> /*unused*/)
-{
-    using std::end;
-
-    ConstructibleArrayType ret;
-    std::transform(
-        j.begin(), j.end(), std::inserter(ret, end(ret)),
-        [](const BasicJsonType & i)
-    {
-        // get<BasicJsonType>() returns *this, this won't call a from_json
-        // method when value_type is BasicJsonType
-        return i.template get<typename ConstructibleArrayType::value_type>();
-    });
-    arr = std::move(ret);
-}
-
-template < typename BasicJsonType, typename ConstructibleArrayType,
-           enable_if_t <
-               is_constructible_array_type<BasicJsonType, ConstructibleArrayType>::value&&
-               !is_constructible_object_type<BasicJsonType, ConstructibleArrayType>::value&&
-               !is_constructible_string_type<BasicJsonType, ConstructibleArrayType>::value&&
-               !std::is_same<ConstructibleArrayType, typename BasicJsonType::binary_t>::value&&
-               !is_basic_json<ConstructibleArrayType>::value,
-               int > = 0 >
-auto from_json(const BasicJsonType& j, ConstructibleArrayType& arr)
--> decltype(from_json_array_impl(j, arr, priority_tag<3> {}),
-j.template get<typename ConstructibleArrayType::value_type>(),
-void())
-{
-    if (JSON_HEDLEY_UNLIKELY(!j.is_array()))
-    {
-        JSON_THROW(type_error::create(302, "type must be array, but is " +
-                                      std::string(j.type_name())));
-    }
-
-    from_json_array_impl(j, arr, priority_tag<3> {});
-}
-
-template<typename BasicJsonType>
-void from_json(const BasicJsonType& j, typename BasicJsonType::binary_t& bin)
-{
-    if (JSON_HEDLEY_UNLIKELY(!j.is_binary()))
-    {
-        JSON_THROW(type_error::create(302, "type must be binary, but is " + std::string(j.type_name())));
-    }
-
-    bin = *j.template get_ptr<const typename BasicJsonType::binary_t*>();
-}
-
-template<typename BasicJsonType, typename ConstructibleObjectType,
-         enable_if_t<is_constructible_object_type<BasicJsonType, ConstructibleObjectType>::value, int> = 0>
-void from_json(const BasicJsonType& j, ConstructibleObjectType& obj)
-{
-    if (JSON_HEDLEY_UNLIKELY(!j.is_object()))
-    {
-        JSON_THROW(type_error::create(302, "type must be object, but is " + std::string(j.type_name())));
-    }
-
-    ConstructibleObjectType ret;
-    auto inner_object = j.template get_ptr<const typename BasicJsonType::object_t*>();
-    using value_type = typename ConstructibleObjectType::value_type;
-    std::transform(
-        inner_object->begin(), inner_object->end(),
-        std::inserter(ret, ret.begin()),
-        [](typename BasicJsonType::object_t::value_type const & p)
-    {
-        return value_type(p.first, p.second.template get<typename ConstructibleObjectType::mapped_type>());
-    });
-    obj = std::move(ret);
-}
-
-// overload for arithmetic types, not chosen for basic_json template arguments
-// (BooleanType, etc..); note: Is it really necessary to provide explicit
-// overloads for boolean_t etc. in case of a custom BooleanType which is not
-// an arithmetic type?
-template < typename BasicJsonType, typename ArithmeticType,
-           enable_if_t <
-               std::is_arithmetic<ArithmeticType>::value&&
-               !std::is_same<ArithmeticType, typename BasicJsonType::number_unsigned_t>::value&&
-               !std::is_same<ArithmeticType, typename BasicJsonType::number_integer_t>::value&&
-               !std::is_same<ArithmeticType, typename BasicJsonType::number_float_t>::value&&
-               !std::is_same<ArithmeticType, typename BasicJsonType::boolean_t>::value,
-               int > = 0 >
-void from_json(const BasicJsonType& j, ArithmeticType& val)
-{
-    switch (static_cast<value_t>(j))
-    {
-        case value_t::number_unsigned:
-        {
-            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>());
-            break;
-        }
-        case value_t::number_integer:
-        {
-            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_integer_t*>());
-            break;
-        }
-        case value_t::number_float:
-        {
-            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_float_t*>());
-            break;
-        }
-        case value_t::boolean:
-        {
-            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::boolean_t*>());
-            break;
-        }
-
-        default:
-            JSON_THROW(type_error::create(302, "type must be number, but is " + std::string(j.type_name())));
-    }
-}
-
-template<typename BasicJsonType, typename A1, typename A2>
-void from_json(const BasicJsonType& j, std::pair<A1, A2>& p)
-{
-    p = {j.at(0).template get<A1>(), j.at(1).template get<A2>()};
-}
-
-template<typename BasicJsonType, typename Tuple, std::size_t... Idx>
-void from_json_tuple_impl(const BasicJsonType& j, Tuple& t, index_sequence<Idx...> /*unused*/)
-{
-    t = std::make_tuple(j.at(Idx).template get<typename std::tuple_element<Idx, Tuple>::type>()...);
-}
-
-template<typename BasicJsonType, typename... Args>
-void from_json(const BasicJsonType& j, std::tuple<Args...>& t)
-{
-    from_json_tuple_impl(j, t, index_sequence_for<Args...> {});
-}
-
-template < typename BasicJsonType, typename Key, typename Value, typename Compare, typename Allocator,
-           typename = enable_if_t < !std::is_constructible <
-                                        typename BasicJsonType::string_t, Key >::value >>
-void from_json(const BasicJsonType& j, std::map<Key, Value, Compare, Allocator>& m)
-{
-    if (JSON_HEDLEY_UNLIKELY(!j.is_array()))
-    {
-        JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name())));
-    }
-    m.clear();
-    for (const auto& p : j)
-    {
-        if (JSON_HEDLEY_UNLIKELY(!p.is_array()))
-        {
-            JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(p.type_name())));
-        }
-        m.emplace(p.at(0).template get<Key>(), p.at(1).template get<Value>());
-    }
-}
-
-template < typename BasicJsonType, typename Key, typename Value, typename Hash, typename KeyEqual, typename Allocator,
-           typename = enable_if_t < !std::is_constructible <
-                                        typename BasicJsonType::string_t, Key >::value >>
-void from_json(const BasicJsonType& j, std::unordered_map<Key, Value, Hash, KeyEqual, Allocator>& m)
-{
-    if (JSON_HEDLEY_UNLIKELY(!j.is_array()))
-    {
-        JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name())));
-    }
-    m.clear();
-    for (const auto& p : j)
-    {
-        if (JSON_HEDLEY_UNLIKELY(!p.is_array()))
-        {
-            JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(p.type_name())));
-        }
-        m.emplace(p.at(0).template get<Key>(), p.at(1).template get<Value>());
-    }
-}
-
-struct from_json_fn
-{
-    template<typename BasicJsonType, typename T>
-    auto operator()(const BasicJsonType& j, T& val) const
-    noexcept(noexcept(from_json(j, val)))
-    -> decltype(from_json(j, val), void())
-    {
-        return from_json(j, val);
-    }
-};
-}  // namespace detail
-
-/// namespace to hold default `from_json` function
-/// to see why this is required:
-/// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4381.html
-namespace
-{
-constexpr const auto& from_json = detail::static_const<detail::from_json_fn>::value;
-} // namespace
-} // namespace nlohmann
-
-// #include <nlohmann/detail/conversions/to_json.hpp>
-
-
-#include <algorithm> // copy
-#include <iterator> // begin, end
-#include <string> // string
-#include <tuple> // tuple, get
-#include <type_traits> // is_same, is_constructible, is_floating_point, is_enum, underlying_type
-#include <utility> // move, forward, declval, pair
-#include <valarray> // valarray
-#include <vector> // vector
-
-// #include <nlohmann/detail/iterators/iteration_proxy.hpp>
-
-
-#include <cstddef> // size_t
-#include <iterator> // input_iterator_tag
-#include <string> // string, to_string
-#include <tuple> // tuple_size, get, tuple_element
-
-// #include <nlohmann/detail/meta/type_traits.hpp>
-
-// #include <nlohmann/detail/value_t.hpp>
-
-
-namespace nlohmann
-{
-namespace detail
-{
-template<typename string_type>
-void int_to_string( string_type& target, std::size_t value )
-{
-    // For ADL
-    using std::to_string;
-    target = to_string(value);
-}
-template<typename IteratorType> class iteration_proxy_value
-{
-  public:
-    using difference_type = std::ptrdiff_t;
-    using value_type = iteration_proxy_value;
-    using pointer = value_type * ;
-    using reference = value_type & ;
-    using iterator_category = std::input_iterator_tag;
-    using string_type = typename std::remove_cv< typename std::remove_reference<decltype( std::declval<IteratorType>().key() ) >::type >::type;
-
-  private:
-    /// the iterator
-    IteratorType anchor;
-    /// an index for arrays (used to create key names)
-    std::size_t array_index = 0;
-    /// last stringified array index
-    mutable std::size_t array_index_last = 0;
-    /// a string representation of the array index
-    mutable string_type array_index_str = "0";
-    /// an empty string (to return a reference for primitive values)
-    const string_type empty_str = "";
-
-  public:
-    explicit iteration_proxy_value(IteratorType it) noexcept : anchor(it) {}
-
-    /// dereference operator (needed for range-based for)
-    iteration_proxy_value& operator*()
-    {
-        return *this;
-    }
-
-    /// increment operator (needed for range-based for)
-    iteration_proxy_value& operator++()
-    {
-        ++anchor;
-        ++array_index;
-
-        return *this;
-    }
-
-    /// equality operator (needed for InputIterator)
-    bool operator==(const iteration_proxy_value& o) const
-    {
-        return anchor == o.anchor;
-    }
-
-    /// inequality operator (needed for range-based for)
-    bool operator!=(const iteration_proxy_value& o) const
-    {
-        return anchor != o.anchor;
-    }
-
-    /// return key of the iterator
-    const string_type& key() const
-    {
-        JSON_ASSERT(anchor.m_object != nullptr);
-
-        switch (anchor.m_object->type())
-        {
-            // use integer array index as key
-            case value_t::array:
-            {
-                if (array_index != array_index_last)
-                {
-                    int_to_string( array_index_str, array_index );
-                    array_index_last = array_index;
-                }
-                return array_index_str;
-            }
-
-            // use key from the object
-            case value_t::object:
-                return anchor.key();
-
-            // use an empty key for all primitive types
-            default:
-                return empty_str;
-        }
-    }
-
-    /// return value of the iterator
-    typename IteratorType::reference value() const
-    {
-        return anchor.value();
-    }
-};
-
-/// proxy class for the items() function
-template<typename IteratorType> class iteration_proxy
-{
-  private:
-    /// the container to iterate
-    typename IteratorType::reference container;
-
-  public:
-    /// construct iteration proxy from a container
-    explicit iteration_proxy(typename IteratorType::reference cont) noexcept
-        : container(cont) {}
-
-    /// return iterator begin (needed for range-based for)
-    iteration_proxy_value<IteratorType> begin() noexcept
-    {
-        return iteration_proxy_value<IteratorType>(container.begin());
-    }
-
-    /// return iterator end (needed for range-based for)
-    iteration_proxy_value<IteratorType> end() noexcept
-    {
-        return iteration_proxy_value<IteratorType>(container.end());
-    }
-};
-// Structured Bindings Support
-// For further reference see https://blog.tartanllama.xyz/structured-bindings/
-// And see https://github.com/nlohmann/json/pull/1391
-template<std::size_t N, typename IteratorType, enable_if_t<N == 0, int> = 0>
-auto get(const nlohmann::detail::iteration_proxy_value<IteratorType>& i) -> decltype(i.key())
-{
-    return i.key();
-}
-// Structured Bindings Support
-// For further reference see https://blog.tartanllama.xyz/structured-bindings/
-// And see https://github.com/nlohmann/json/pull/1391
-template<std::size_t N, typename IteratorType, enable_if_t<N == 1, int> = 0>
-auto get(const nlohmann::detail::iteration_proxy_value<IteratorType>& i) -> decltype(i.value())
-{
-    return i.value();
-}
-}  // namespace detail
-}  // namespace nlohmann
-
-// The Addition to the STD Namespace is required to add
-// Structured Bindings Support to the iteration_proxy_value class
-// For further reference see https://blog.tartanllama.xyz/structured-bindings/
-// And see https://github.com/nlohmann/json/pull/1391
-namespace std
-{
-#if defined(__clang__)
-    // Fix: https://github.com/nlohmann/json/issues/1401
-    #pragma clang diagnostic push
-    #pragma clang diagnostic ignored "-Wmismatched-tags"
-#endif
-template<typename IteratorType>
-class tuple_size<::nlohmann::detail::iteration_proxy_value<IteratorType>>
-            : public std::integral_constant<std::size_t, 2> {};
-
-template<std::size_t N, typename IteratorType>
-class tuple_element<N, ::nlohmann::detail::iteration_proxy_value<IteratorType >>
-{
-  public:
-    using type = decltype(
-                     get<N>(std::declval <
-                            ::nlohmann::detail::iteration_proxy_value<IteratorType >> ()));
-};
-#if defined(__clang__)
-    #pragma clang diagnostic pop
-#endif
-} // namespace std
-
-// #include <nlohmann/detail/meta/cpp_future.hpp>
-
-// #include <nlohmann/detail/meta/type_traits.hpp>
-
-// #include <nlohmann/detail/value_t.hpp>
-
-
-namespace nlohmann
-{
-namespace detail
-{
-//////////////////
-// constructors //
-//////////////////
-
-template<value_t> struct external_constructor;
-
-template<>
-struct external_constructor<value_t::boolean>
-{
-    template<typename BasicJsonType>
-    static void construct(BasicJsonType& j, typename BasicJsonType::boolean_t b) noexcept
-    {
-        j.m_type = value_t::boolean;
-        j.m_value = b;
-        j.assert_invariant();
-    }
-};
-
-template<>
-struct external_constructor<value_t::string>
-{
-    template<typename BasicJsonType>
-    static void construct(BasicJsonType& j, const typename BasicJsonType::string_t& s)
-    {
-        j.m_type = value_t::string;
-        j.m_value = s;
-        j.assert_invariant();
-    }
-
-    template<typename BasicJsonType>
-    static void construct(BasicJsonType& j, typename BasicJsonType::string_t&& s)
-    {
-        j.m_type = value_t::string;
-        j.m_value = std::move(s);
-        j.assert_invariant();
-    }
-
-    template < typename BasicJsonType, typename CompatibleStringType,
-               enable_if_t < !std::is_same<CompatibleStringType, typename BasicJsonType::string_t>::value,
-                             int > = 0 >
-    static void construct(BasicJsonType& j, const CompatibleStringType& str)
-    {
-        j.m_type = value_t::string;
-        j.m_value.string = j.template create<typename BasicJsonType::string_t>(str);
-        j.assert_invariant();
-    }
-};
-
-template<>
-struct external_constructor<value_t::binary>
-{
-    template<typename BasicJsonType>
-    static void construct(BasicJsonType& j, const typename BasicJsonType::binary_t& b)
-    {
-        j.m_type = value_t::binary;
-        typename BasicJsonType::binary_t value{b};
-        j.m_value = value;
-        j.assert_invariant();
-    }
-
-    template<typename BasicJsonType>
-    static void construct(BasicJsonType& j, typename BasicJsonType::binary_t&& b)
-    {
-        j.m_type = value_t::binary;
-        typename BasicJsonType::binary_t value{std::move(b)};
-        j.m_value = value;
-        j.assert_invariant();
-    }
-};
-
-template<>
-struct external_constructor<value_t::number_float>
-{
-    template<typename BasicJsonType>
-    static void construct(BasicJsonType& j, typename BasicJsonType::number_float_t val) noexcept
-    {
-        j.m_type = value_t::number_float;
-        j.m_value = val;
-        j.assert_invariant();
-    }
-};
-
-template<>
-struct external_constructor<value_t::number_unsigned>
-{
-    template<typename BasicJsonType>
-    static void construct(BasicJsonType& j, typename BasicJsonType::number_unsigned_t val) noexcept
-    {
-        j.m_type = value_t::number_unsigned;
-        j.m_value = val;
-        j.assert_invariant();
-    }
-};
-
-template<>
-struct external_constructor<value_t::number_integer>
-{
-    template<typename BasicJsonType>
-    static void construct(BasicJsonType& j, typename BasicJsonType::number_integer_t val) noexcept
-    {
-        j.m_type = value_t::number_integer;
-        j.m_value = val;
-        j.assert_invariant();
-    }
-};
-
-template<>
-struct external_constructor<value_t::array>
-{
-    template<typename BasicJsonType>
-    static void construct(BasicJsonType& j, const typename BasicJsonType::array_t& arr)
-    {
-        j.m_type = value_t::array;
-        j.m_value = arr;
-        j.assert_invariant();
-    }
-
-    template<typename BasicJsonType>
-    static void construct(BasicJsonType& j, typename BasicJsonType::array_t&& arr)
-    {
-        j.m_type = value_t::array;
-        j.m_value = std::move(arr);
-        j.assert_invariant();
-    }
-
-    template < typename BasicJsonType, typename CompatibleArrayType,
-               enable_if_t < !std::is_same<CompatibleArrayType, typename BasicJsonType::array_t>::value,
-                             int > = 0 >
-    static void construct(BasicJsonType& j, const CompatibleArrayType& arr)
-    {
-        using std::begin;
-        using std::end;
-        j.m_type = value_t::array;
-        j.m_value.array = j.template create<typename BasicJsonType::array_t>(begin(arr), end(arr));
-        j.assert_invariant();
-    }
-
-    template<typename BasicJsonType>
-    static void construct(BasicJsonType& j, const std::vector<bool>& arr)
-    {
-        j.m_type = value_t::array;
-        j.m_value = value_t::array;
-        j.m_value.array->reserve(arr.size());
-        for (const bool x : arr)
-        {
-            j.m_value.array->push_back(x);
-        }
-        j.assert_invariant();
-    }
-
-    template<typename BasicJsonType, typename T,
-             enable_if_t<std::is_convertible<T, BasicJsonType>::value, int> = 0>
-    static void construct(BasicJsonType& j, const std::valarray<T>& arr)
-    {
-        j.m_type = value_t::array;
-        j.m_value = value_t::array;
-        j.m_value.array->resize(arr.size());
-        if (arr.size() > 0)
-        {
-            std::copy(std::begin(arr), std::end(arr), j.m_value.array->begin());
-        }
-        j.assert_invariant();
-    }
-};
-
-template<>
-struct external_constructor<value_t::object>
-{
-    template<typename BasicJsonType>
-    static void construct(BasicJsonType& j, const typename BasicJsonType::object_t& obj)
-    {
-        j.m_type = value_t::object;
-        j.m_value = obj;
-        j.assert_invariant();
-    }
-
-    template<typename BasicJsonType>
-    static void construct(BasicJsonType& j, typename BasicJsonType::object_t&& obj)
-    {
-        j.m_type = value_t::object;
-        j.m_value = std::move(obj);
-        j.assert_invariant();
-    }
-
-    template < typename BasicJsonType, typename CompatibleObjectType,
-               enable_if_t < !std::is_same<CompatibleObjectType, typename BasicJsonType::object_t>::value, int > = 0 >
-    static void construct(BasicJsonType& j, const CompatibleObjectType& obj)
-    {
-        using std::begin;
-        using std::end;
-
-        j.m_type = value_t::object;
-        j.m_value.object = j.template create<typename BasicJsonType::object_t>(begin(obj), end(obj));
-        j.assert_invariant();
-    }
-};
-
-/////////////
-// to_json //
-/////////////
-
-template<typename BasicJsonType, typename T,
-         enable_if_t<std::is_same<T, typename BasicJsonType::boolean_t>::value, int> = 0>
-void to_json(BasicJsonType& j, T b) noexcept
-{
-    external_constructor<value_t::boolean>::construct(j, b);
-}
-
-template<typename BasicJsonType, typename CompatibleString,
-         enable_if_t<std::is_constructible<typename BasicJsonType::string_t, CompatibleString>::value, int> = 0>
-void to_json(BasicJsonType& j, const CompatibleString& s)
-{
-    external_constructor<value_t::string>::construct(j, s);
-}
-
-template<typename BasicJsonType>
-void to_json(BasicJsonType& j, typename BasicJsonType::string_t&& s)
-{
-    external_constructor<value_t::string>::construct(j, std::move(s));
-}
-
-template<typename BasicJsonType, typename FloatType,
-         enable_if_t<std::is_floating_point<FloatType>::value, int> = 0>
-void to_json(BasicJsonType& j, FloatType val) noexcept
-{
-    external_constructor<value_t::number_float>::construct(j, static_cast<typename BasicJsonType::number_float_t>(val));
-}
-
-template<typename BasicJsonType, typename CompatibleNumberUnsignedType,
-         enable_if_t<is_compatible_integer_type<typename BasicJsonType::number_unsigned_t, CompatibleNumberUnsignedType>::value, int> = 0>
-void to_json(BasicJsonType& j, CompatibleNumberUnsignedType val) noexcept
-{
-    external_constructor<value_t::number_unsigned>::construct(j, static_cast<typename BasicJsonType::number_unsigned_t>(val));
-}
-
-template<typename BasicJsonType, typename CompatibleNumberIntegerType,
-         enable_if_t<is_compatible_integer_type<typename BasicJsonType::number_integer_t, CompatibleNumberIntegerType>::value, int> = 0>
-void to_json(BasicJsonType& j, CompatibleNumberIntegerType val) noexcept
-{
-    external_constructor<value_t::number_integer>::construct(j, static_cast<typename BasicJsonType::number_integer_t>(val));
-}
-
-template<typename BasicJsonType, typename EnumType,
-         enable_if_t<std::is_enum<EnumType>::value, int> = 0>
-void to_json(BasicJsonType& j, EnumType e) noexcept
-{
-    using underlying_type = typename std::underlying_type<EnumType>::type;
-    external_constructor<value_t::number_integer>::construct(j, static_cast<underlying_type>(e));
-}
-
-template<typename BasicJsonType>
-void to_json(BasicJsonType& j, const std::vector<bool>& e)
-{
-    external_constructor<value_t::array>::construct(j, e);
-}
-
-template < typename BasicJsonType, typename CompatibleArrayType,
-           enable_if_t < is_compatible_array_type<BasicJsonType,
-                         CompatibleArrayType>::value&&
-                         !is_compatible_object_type<BasicJsonType, CompatibleArrayType>::value&&
-                         !is_compatible_string_type<BasicJsonType, CompatibleArrayType>::value&&
-                         !std::is_same<typename BasicJsonType::binary_t, CompatibleArrayType>::value&&
-                         !is_basic_json<CompatibleArrayType>::value,
-                         int > = 0 >
-void to_json(BasicJsonType& j, const CompatibleArrayType& arr)
-{
-    external_constructor<value_t::array>::construct(j, arr);
-}
-
-template<typename BasicJsonType>
-void to_json(BasicJsonType& j, const typename BasicJsonType::binary_t& bin)
-{
-    external_constructor<value_t::binary>::construct(j, bin);
-}
-
-template<typename BasicJsonType, typename T,
-         enable_if_t<std::is_convertible<T, BasicJsonType>::value, int> = 0>
-void to_json(BasicJsonType& j, const std::valarray<T>& arr)
-{
-    external_constructor<value_t::array>::construct(j, std::move(arr));
-}
-
-template<typename BasicJsonType>
-void to_json(BasicJsonType& j, typename BasicJsonType::array_t&& arr)
-{
-    external_constructor<value_t::array>::construct(j, std::move(arr));
-}
-
-template < typename BasicJsonType, typename CompatibleObjectType,
-           enable_if_t < is_compatible_object_type<BasicJsonType, CompatibleObjectType>::value&& !is_basic_json<CompatibleObjectType>::value, int > = 0 >
-void to_json(BasicJsonType& j, const CompatibleObjectType& obj)
-{
-    external_constructor<value_t::object>::construct(j, obj);
-}
-
-template<typename BasicJsonType>
-void to_json(BasicJsonType& j, typename BasicJsonType::object_t&& obj)
-{
-    external_constructor<value_t::object>::construct(j, std::move(obj));
-}
-
-template <
-    typename BasicJsonType, typename T, std::size_t N,
-    enable_if_t < !std::is_constructible<typename BasicJsonType::string_t,
-                  const T(&)[N]>::value,
-                  int > = 0 >
-void to_json(BasicJsonType& j, const T(&arr)[N])
-{
-    external_constructor<value_t::array>::construct(j, arr);
-}
-
-template < typename BasicJsonType, typename T1, typename T2, enable_if_t < std::is_constructible<BasicJsonType, T1>::value&& std::is_constructible<BasicJsonType, T2>::value, int > = 0 >
-void to_json(BasicJsonType& j, const std::pair<T1, T2>& p)
-{
-    j = { p.first, p.second };
-}
-
-// for https://github.com/nlohmann/json/pull/1134
-template<typename BasicJsonType, typename T,
-         enable_if_t<std::is_same<T, iteration_proxy_value<typename BasicJsonType::iterator>>::value, int> = 0>
-void to_json(BasicJsonType& j, const T& b)
-{
-    j = { {b.key(), b.value()} };
-}
-
-template<typename BasicJsonType, typename Tuple, std::size_t... Idx>
-void to_json_tuple_impl(BasicJsonType& j, const Tuple& t, index_sequence<Idx...> /*unused*/)
-{
-    j = { std::get<Idx>(t)... };
-}
-
-template<typename BasicJsonType, typename T, enable_if_t<is_constructible_tuple<BasicJsonType, T>::value, int > = 0>
-void to_json(BasicJsonType& j, const T& t)
-{
-    to_json_tuple_impl(j, t, make_index_sequence<std::tuple_size<T>::value> {});
-}
-
-struct to_json_fn
-{
-    template<typename BasicJsonType, typename T>
-    auto operator()(BasicJsonType& j, T&& val) const noexcept(noexcept(to_json(j, std::forward<T>(val))))
-    -> decltype(to_json(j, std::forward<T>(val)), void())
-    {
-        return to_json(j, std::forward<T>(val));
-    }
-};
-}  // namespace detail
-
-/// namespace to hold default `to_json` function
-namespace
-{
-constexpr const auto& to_json = detail::static_const<detail::to_json_fn>::value;
-} // namespace
-} // namespace nlohmann
-
-
-namespace nlohmann
-{
-
-template<typename, typename>
-struct adl_serializer
-{
-    /*!
-    @brief convert a JSON value to any value type
-
-    This function is usually called by the `get()` function of the
-    @ref basic_json class (either explicit or via conversion operators).
-
-    @param[in] j        JSON value to read from
-    @param[in,out] val  value to write to
-    */
-    template<typename BasicJsonType, typename ValueType>
-    static auto from_json(BasicJsonType&& j, ValueType& val) noexcept(
-        noexcept(::nlohmann::from_json(std::forward<BasicJsonType>(j), val)))
-    -> decltype(::nlohmann::from_json(std::forward<BasicJsonType>(j), val), void())
-    {
-        ::nlohmann::from_json(std::forward<BasicJsonType>(j), val);
-    }
-
-    /*!
-    @brief convert any value type to a JSON value
-
-    This function is usually called by the constructors of the @ref basic_json
-    class.
-
-    @param[in,out] j  JSON value to write to
-    @param[in] val    value to read from
-    */
-    template<typename BasicJsonType, typename ValueType>
-    static auto to_json(BasicJsonType& j, ValueType&& val) noexcept(
-        noexcept(::nlohmann::to_json(j, std::forward<ValueType>(val))))
-    -> decltype(::nlohmann::to_json(j, std::forward<ValueType>(val)), void())
-    {
-        ::nlohmann::to_json(j, std::forward<ValueType>(val));
-    }
-};
-
-}  // namespace nlohmann
-
-// #include <nlohmann/byte_container_with_subtype.hpp>
-
-
-#include <cstdint> // uint8_t
-#include <tuple> // tie
-#include <utility> // move
-
-namespace nlohmann
-{
-
-/*!
-@brief an internal type for a backed binary type
-
-This type extends the template parameter @a BinaryType provided to `basic_json`
-with a subtype used by BSON and MessagePack. This type exists so that the user
-does not have to specify a type themselves with a specific naming scheme in
-order to override the binary type.
-
-@tparam BinaryType container to store bytes (`std::vector<std::uint8_t>` by
-                   default)
-
-@since version 3.8.0
-*/
-template<typename BinaryType>
-class byte_container_with_subtype : public BinaryType
-{
-  public:
-    /// the type of the underlying container
-    using container_type = BinaryType;
-
-    byte_container_with_subtype() noexcept(noexcept(container_type()))
-        : container_type()
-    {}
-
-    byte_container_with_subtype(const container_type& b) noexcept(noexcept(container_type(b)))
-        : container_type(b)
-    {}
-
-    byte_container_with_subtype(container_type&& b) noexcept(noexcept(container_type(std::move(b))))
-        : container_type(std::move(b))
-    {}
-
-    byte_container_with_subtype(const container_type& b, std::uint8_t subtype) noexcept(noexcept(container_type(b)))
-        : container_type(b)
-        , m_subtype(subtype)
-        , m_has_subtype(true)
-    {}
-
-    byte_container_with_subtype(container_type&& b, std::uint8_t subtype) noexcept(noexcept(container_type(std::move(b))))
-        : container_type(std::move(b))
-        , m_subtype(subtype)
-        , m_has_subtype(true)
-    {}
-
-    bool operator==(const byte_container_with_subtype& rhs) const
-    {
-        return std::tie(static_cast<const BinaryType&>(*this), m_subtype, m_has_subtype) ==
-               std::tie(static_cast<const BinaryType&>(rhs), rhs.m_subtype, rhs.m_has_subtype);
-    }
-
-    bool operator!=(const byte_container_with_subtype& rhs) const
-    {
-        return !(rhs == *this);
-    }
-
-    /*!
-    @brief sets the binary subtype
-
-    Sets the binary subtype of the value, also flags a binary JSON value as
-    having a subtype, which has implications for serialization.
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @sa @ref subtype() -- return the binary subtype
-    @sa @ref clear_subtype() -- clears the binary subtype
-    @sa @ref has_subtype() -- returns whether or not the binary value has a
-    subtype
-
-    @since version 3.8.0
-    */
-    void set_subtype(std::uint8_t subtype) noexcept
-    {
-        m_subtype = subtype;
-        m_has_subtype = true;
-    }
-
-    /*!
-    @brief return the binary subtype
-
-    Returns the numerical subtype of the value if it has a subtype. If it does
-    not have a subtype, this function will return size_t(-1) as a sentinel
-    value.
-
-    @return the numerical subtype of the binary value
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @sa @ref set_subtype() -- sets the binary subtype
-    @sa @ref clear_subtype() -- clears the binary subtype
-    @sa @ref has_subtype() -- returns whether or not the binary value has a
-    subtype
-
-    @since version 3.8.0
-    */
-    constexpr std::uint8_t subtype() const noexcept
-    {
-        return m_subtype;
-    }
-
-    /*!
-    @brief return whether the value has a subtype
-
-    @return whether the value has a subtype
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @sa @ref subtype() -- return the binary subtype
-    @sa @ref set_subtype() -- sets the binary subtype
-    @sa @ref clear_subtype() -- clears the binary subtype
-
-    @since version 3.8.0
-    */
-    constexpr bool has_subtype() const noexcept
-    {
-        return m_has_subtype;
-    }
-
-    /*!
-    @brief clears the binary subtype
-
-    Clears the binary subtype and flags the value as not having a subtype, which
-    has implications for serialization; for instance MessagePack will prefer the
-    bin family over the ext family.
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @sa @ref subtype() -- return the binary subtype
-    @sa @ref set_subtype() -- sets the binary subtype
-    @sa @ref has_subtype() -- returns whether or not the binary value has a
-    subtype
-
-    @since version 3.8.0
-    */
-    void clear_subtype() noexcept
-    {
-        m_subtype = 0;
-        m_has_subtype = false;
-    }
-
-  private:
-    std::uint8_t m_subtype = 0;
-    bool m_has_subtype = false;
-};
-
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/conversions/from_json.hpp>
-
-// #include <nlohmann/detail/conversions/to_json.hpp>
-
-// #include <nlohmann/detail/exceptions.hpp>
-
-// #include <nlohmann/detail/hash.hpp>
-
-
-#include <cstddef> // size_t, uint8_t
-#include <functional> // hash
-
-namespace nlohmann
-{
-namespace detail
-{
-
-// boost::hash_combine
-inline std::size_t combine(std::size_t seed, std::size_t h) noexcept
-{
-    seed ^= h + 0x9e3779b9 + (seed << 6U) + (seed >> 2U);
-    return seed;
-}
-
-/*!
-@brief hash a JSON value
-
-The hash function tries to rely on std::hash where possible. Furthermore, the
-type of the JSON value is taken into account to have different hash values for
-null, 0, 0U, and false, etc.
-
-@tparam BasicJsonType basic_json specialization
-@param j JSON value to hash
-@return hash value of j
-*/
-template<typename BasicJsonType>
-std::size_t hash(const BasicJsonType& j)
-{
-    using string_t = typename BasicJsonType::string_t;
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-
-    const auto type = static_cast<std::size_t>(j.type());
-    switch (j.type())
-    {
-        case BasicJsonType::value_t::null:
-        case BasicJsonType::value_t::discarded:
-        {
-            return combine(type, 0);
-        }
-
-        case BasicJsonType::value_t::object:
-        {
-            auto seed = combine(type, j.size());
-            for (const auto& element : j.items())
-            {
-                const auto h = std::hash<string_t> {}(element.key());
-                seed = combine(seed, h);
-                seed = combine(seed, hash(element.value()));
-            }
-            return seed;
-        }
-
-        case BasicJsonType::value_t::array:
-        {
-            auto seed = combine(type, j.size());
-            for (const auto& element : j)
-            {
-                seed = combine(seed, hash(element));
-            }
-            return seed;
-        }
-
-        case BasicJsonType::value_t::string:
-        {
-            const auto h = std::hash<string_t> {}(j.template get_ref<const string_t&>());
-            return combine(type, h);
-        }
-
-        case BasicJsonType::value_t::boolean:
-        {
-            const auto h = std::hash<bool> {}(j.template get<bool>());
-            return combine(type, h);
-        }
-
-        case BasicJsonType::value_t::number_integer:
-        {
-            const auto h = std::hash<number_integer_t> {}(j.template get<number_integer_t>());
-            return combine(type, h);
-        }
-
-        case nlohmann::detail::value_t::number_unsigned:
-        {
-            const auto h = std::hash<number_unsigned_t> {}(j.template get<number_unsigned_t>());
-            return combine(type, h);
-        }
-
-        case nlohmann::detail::value_t::number_float:
-        {
-            const auto h = std::hash<number_float_t> {}(j.template get<number_float_t>());
-            return combine(type, h);
-        }
-
-        case nlohmann::detail::value_t::binary:
-        {
-            auto seed = combine(type, j.get_binary().size());
-            const auto h = std::hash<bool> {}(j.get_binary().has_subtype());
-            seed = combine(seed, h);
-            seed = combine(seed, j.get_binary().subtype());
-            for (const auto byte : j.get_binary())
-            {
-                seed = combine(seed, std::hash<std::uint8_t> {}(byte));
-            }
-            return seed;
-        }
-
-        default: // LCOV_EXCL_LINE
-            JSON_ASSERT(false); // LCOV_EXCL_LINE
-    }
-}
-
-}  // namespace detail
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/input/binary_reader.hpp>
-
-
-#include <algorithm> // generate_n
-#include <array> // array
-#include <cmath> // ldexp
-#include <cstddef> // size_t
-#include <cstdint> // uint8_t, uint16_t, uint32_t, uint64_t
-#include <cstdio> // snprintf
-#include <cstring> // memcpy
-#include <iterator> // back_inserter
-#include <limits> // numeric_limits
-#include <string> // char_traits, string
-#include <utility> // make_pair, move
-
-// #include <nlohmann/detail/exceptions.hpp>
-
-// #include <nlohmann/detail/input/input_adapters.hpp>
-
-
-#include <array> // array
-#include <cstddef> // size_t
-#include <cstdio> //FILE *
-#include <cstring> // strlen
-#include <istream> // istream
-#include <iterator> // begin, end, iterator_traits, random_access_iterator_tag, distance, next
-#include <memory> // shared_ptr, make_shared, addressof
-#include <numeric> // accumulate
-#include <string> // string, char_traits
-#include <type_traits> // enable_if, is_base_of, is_pointer, is_integral, remove_pointer
-#include <utility> // pair, declval
-
-// #include <nlohmann/detail/iterators/iterator_traits.hpp>
-
-// #include <nlohmann/detail/macro_scope.hpp>
-
-
-namespace nlohmann
-{
-namespace detail
-{
-/// the supported input formats
-enum class input_format_t { json, cbor, msgpack, ubjson, bson };
-
-////////////////////
-// input adapters //
-////////////////////
-
-/*!
-Input adapter for stdio file access. This adapter read only 1 byte and do not use any
- buffer. This adapter is a very low level adapter.
-*/
-class file_input_adapter
-{
-  public:
-    using char_type = char;
-
-    JSON_HEDLEY_NON_NULL(2)
-    explicit file_input_adapter(std::FILE* f) noexcept
-        : m_file(f)
-    {}
-
-    // make class move-only
-    file_input_adapter(const file_input_adapter&) = delete;
-    file_input_adapter(file_input_adapter&&) = default;
-    file_input_adapter& operator=(const file_input_adapter&) = delete;
-    file_input_adapter& operator=(file_input_adapter&&) = delete;
-
-    std::char_traits<char>::int_type get_character() noexcept
-    {
-        return std::fgetc(m_file);
-    }
-
-  private:
-    /// the file pointer to read from
-    std::FILE* m_file;
-};
-
-
-/*!
-Input adapter for a (caching) istream. Ignores a UFT Byte Order Mark at
-beginning of input. Does not support changing the underlying std::streambuf
-in mid-input. Maintains underlying std::istream and std::streambuf to support
-subsequent use of standard std::istream operations to process any input
-characters following those used in parsing the JSON input.  Clears the
-std::istream flags; any input errors (e.g., EOF) will be detected by the first
-subsequent call for input from the std::istream.
-*/
-class input_stream_adapter
-{
-  public:
-    using char_type = char;
-
-    ~input_stream_adapter()
-    {
-        // clear stream flags; we use underlying streambuf I/O, do not
-        // maintain ifstream flags, except eof
-        if (is != nullptr)
-        {
-            is->clear(is->rdstate() & std::ios::eofbit);
-        }
-    }
-
-    explicit input_stream_adapter(std::istream& i)
-        : is(&i), sb(i.rdbuf())
-    {}
-
-    // delete because of pointer members
-    input_stream_adapter(const input_stream_adapter&) = delete;
-    input_stream_adapter& operator=(input_stream_adapter&) = delete;
-    input_stream_adapter& operator=(input_stream_adapter&& rhs) = delete;
-
-    input_stream_adapter(input_stream_adapter&& rhs) noexcept : is(rhs.is), sb(rhs.sb)
-    {
-        rhs.is = nullptr;
-        rhs.sb = nullptr;
-    }
-
-    // std::istream/std::streambuf use std::char_traits<char>::to_int_type, to
-    // ensure that std::char_traits<char>::eof() and the character 0xFF do not
-    // end up as the same value, eg. 0xFFFFFFFF.
-    std::char_traits<char>::int_type get_character()
-    {
-        auto res = sb->sbumpc();
-        // set eof manually, as we don't use the istream interface.
-        if (JSON_HEDLEY_UNLIKELY(res == EOF))
-        {
-            is->clear(is->rdstate() | std::ios::eofbit);
-        }
-        return res;
-    }
-
-  private:
-    /// the associated input stream
-    std::istream* is = nullptr;
-    std::streambuf* sb = nullptr;
-};
-
-// General-purpose iterator-based adapter. It might not be as fast as
-// theoretically possible for some containers, but it is extremely versatile.
-template<typename IteratorType>
-class iterator_input_adapter
-{
-  public:
-    using char_type = typename std::iterator_traits<IteratorType>::value_type;
-
-    iterator_input_adapter(IteratorType first, IteratorType last)
-        : current(std::move(first)), end(std::move(last)) {}
-
-    typename std::char_traits<char_type>::int_type get_character()
-    {
-        if (JSON_HEDLEY_LIKELY(current != end))
-        {
-            auto result = std::char_traits<char_type>::to_int_type(*current);
-            std::advance(current, 1);
-            return result;
-        }
-        else
-        {
-            return std::char_traits<char_type>::eof();
-        }
-    }
-
-  private:
-    IteratorType current;
-    IteratorType end;
-
-    template<typename BaseInputAdapter, size_t T>
-    friend struct wide_string_input_helper;
-
-    bool empty() const
-    {
-        return current == end;
-    }
-
-};
-
-
-template<typename BaseInputAdapter, size_t T>
-struct wide_string_input_helper;
-
-template<typename BaseInputAdapter>
-struct wide_string_input_helper<BaseInputAdapter, 4>
-{
-    // UTF-32
-    static void fill_buffer(BaseInputAdapter& input,
-                            std::array<std::char_traits<char>::int_type, 4>& utf8_bytes,
-                            size_t& utf8_bytes_index,
-                            size_t& utf8_bytes_filled)
-    {
-        utf8_bytes_index = 0;
-
-        if (JSON_HEDLEY_UNLIKELY(input.empty()))
-        {
-            utf8_bytes[0] = std::char_traits<char>::eof();
-            utf8_bytes_filled = 1;
-        }
-        else
-        {
-            // get the current character
-            const auto wc = input.get_character();
-
-            // UTF-32 to UTF-8 encoding
-            if (wc < 0x80)
-            {
-                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(wc);
-                utf8_bytes_filled = 1;
-            }
-            else if (wc <= 0x7FF)
-            {
-                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xC0u | ((static_cast<unsigned int>(wc) >> 6u) & 0x1Fu));
-                utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | (static_cast<unsigned int>(wc) & 0x3Fu));
-                utf8_bytes_filled = 2;
-            }
-            else if (wc <= 0xFFFF)
-            {
-                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xE0u | ((static_cast<unsigned int>(wc) >> 12u) & 0x0Fu));
-                utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | ((static_cast<unsigned int>(wc) >> 6u) & 0x3Fu));
-                utf8_bytes[2] = static_cast<std::char_traits<char>::int_type>(0x80u | (static_cast<unsigned int>(wc) & 0x3Fu));
-                utf8_bytes_filled = 3;
-            }
-            else if (wc <= 0x10FFFF)
-            {
-                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xF0u | ((static_cast<unsigned int>(wc) >> 18u) & 0x07u));
-                utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | ((static_cast<unsigned int>(wc) >> 12u) & 0x3Fu));
-                utf8_bytes[2] = static_cast<std::char_traits<char>::int_type>(0x80u | ((static_cast<unsigned int>(wc) >> 6u) & 0x3Fu));
-                utf8_bytes[3] = static_cast<std::char_traits<char>::int_type>(0x80u | (static_cast<unsigned int>(wc) & 0x3Fu));
-                utf8_bytes_filled = 4;
-            }
-            else
-            {
-                // unknown character
-                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(wc);
-                utf8_bytes_filled = 1;
-            }
-        }
-    }
-};
-
-template<typename BaseInputAdapter>
-struct wide_string_input_helper<BaseInputAdapter, 2>
-{
-    // UTF-16
-    static void fill_buffer(BaseInputAdapter& input,
-                            std::array<std::char_traits<char>::int_type, 4>& utf8_bytes,
-                            size_t& utf8_bytes_index,
-                            size_t& utf8_bytes_filled)
-    {
-        utf8_bytes_index = 0;
-
-        if (JSON_HEDLEY_UNLIKELY(input.empty()))
-        {
-            utf8_bytes[0] = std::char_traits<char>::eof();
-            utf8_bytes_filled = 1;
-        }
-        else
-        {
-            // get the current character
-            const auto wc = input.get_character();
-
-            // UTF-16 to UTF-8 encoding
-            if (wc < 0x80)
-            {
-                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(wc);
-                utf8_bytes_filled = 1;
-            }
-            else if (wc <= 0x7FF)
-            {
-                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xC0u | ((static_cast<unsigned int>(wc) >> 6u)));
-                utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | (static_cast<unsigned int>(wc) & 0x3Fu));
-                utf8_bytes_filled = 2;
-            }
-            else if (0xD800 > wc || wc >= 0xE000)
-            {
-                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xE0u | ((static_cast<unsigned int>(wc) >> 12u)));
-                utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | ((static_cast<unsigned int>(wc) >> 6u) & 0x3Fu));
-                utf8_bytes[2] = static_cast<std::char_traits<char>::int_type>(0x80u | (static_cast<unsigned int>(wc) & 0x3Fu));
-                utf8_bytes_filled = 3;
-            }
-            else
-            {
-                if (JSON_HEDLEY_UNLIKELY(!input.empty()))
-                {
-                    const auto wc2 = static_cast<unsigned int>(input.get_character());
-                    const auto charcode = 0x10000u + (((static_cast<unsigned int>(wc) & 0x3FFu) << 10u) | (wc2 & 0x3FFu));
-                    utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xF0u | (charcode >> 18u));
-                    utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | ((charcode >> 12u) & 0x3Fu));
-                    utf8_bytes[2] = static_cast<std::char_traits<char>::int_type>(0x80u | ((charcode >> 6u) & 0x3Fu));
-                    utf8_bytes[3] = static_cast<std::char_traits<char>::int_type>(0x80u | (charcode & 0x3Fu));
-                    utf8_bytes_filled = 4;
-                }
-                else
-                {
-                    utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(wc);
-                    utf8_bytes_filled = 1;
-                }
-            }
-        }
-    }
-};
-
-// Wraps another input apdater to convert wide character types into individual bytes.
-template<typename BaseInputAdapter, typename WideCharType>
-class wide_string_input_adapter
-{
-  public:
-    using char_type = char;
-
-    wide_string_input_adapter(BaseInputAdapter base)
-        : base_adapter(base) {}
-
-    typename std::char_traits<char>::int_type get_character() noexcept
-    {
-        // check if buffer needs to be filled
-        if (utf8_bytes_index == utf8_bytes_filled)
-        {
-            fill_buffer<sizeof(WideCharType)>();
-
-            JSON_ASSERT(utf8_bytes_filled > 0);
-            JSON_ASSERT(utf8_bytes_index == 0);
-        }
-
-        // use buffer
-        JSON_ASSERT(utf8_bytes_filled > 0);
-        JSON_ASSERT(utf8_bytes_index < utf8_bytes_filled);
-        return utf8_bytes[utf8_bytes_index++];
-    }
-
-  private:
-    BaseInputAdapter base_adapter;
-
-    template<size_t T>
-    void fill_buffer()
-    {
-        wide_string_input_helper<BaseInputAdapter, T>::fill_buffer(base_adapter, utf8_bytes, utf8_bytes_index, utf8_bytes_filled);
-    }
-
-    /// a buffer for UTF-8 bytes
-    std::array<std::char_traits<char>::int_type, 4> utf8_bytes = {{0, 0, 0, 0}};
-
-    /// index to the utf8_codes array for the next valid byte
-    std::size_t utf8_bytes_index = 0;
-    /// number of valid bytes in the utf8_codes array
-    std::size_t utf8_bytes_filled = 0;
-};
-
-
-template<typename IteratorType, typename Enable = void>
-struct iterator_input_adapter_factory
-{
-    using iterator_type = IteratorType;
-    using char_type = typename std::iterator_traits<iterator_type>::value_type;
-    using adapter_type = iterator_input_adapter<iterator_type>;
-
-    static adapter_type create(IteratorType first, IteratorType last)
-    {
-        return adapter_type(std::move(first), std::move(last));
-    }
-};
-
-template<typename T>
-struct is_iterator_of_multibyte
-{
-    using value_type = typename std::iterator_traits<T>::value_type;
-    enum
-    {
-        value = sizeof(value_type) > 1
-    };
-};
-
-template<typename IteratorType>
-struct iterator_input_adapter_factory<IteratorType, enable_if_t<is_iterator_of_multibyte<IteratorType>::value>>
-{
-    using iterator_type = IteratorType;
-    using char_type = typename std::iterator_traits<iterator_type>::value_type;
-    using base_adapter_type = iterator_input_adapter<iterator_type>;
-    using adapter_type = wide_string_input_adapter<base_adapter_type, char_type>;
-
-    static adapter_type create(IteratorType first, IteratorType last)
-    {
-        return adapter_type(base_adapter_type(std::move(first), std::move(last)));
-    }
-};
-
-// General purpose iterator-based input
-template<typename IteratorType>
-typename iterator_input_adapter_factory<IteratorType>::adapter_type input_adapter(IteratorType first, IteratorType last)
-{
-    using factory_type = iterator_input_adapter_factory<IteratorType>;
-    return factory_type::create(first, last);
-}
-
-// Convenience shorthand from container to iterator
-template<typename ContainerType>
-auto input_adapter(const ContainerType& container) -> decltype(input_adapter(begin(container), end(container)))
-{
-    // Enable ADL
-    using std::begin;
-    using std::end;
-
-    return input_adapter(begin(container), end(container));
-}
-
-// Special cases with fast paths
-inline file_input_adapter input_adapter(std::FILE* file)
-{
-    return file_input_adapter(file);
-}
-
-inline input_stream_adapter input_adapter(std::istream& stream)
-{
-    return input_stream_adapter(stream);
-}
-
-inline input_stream_adapter input_adapter(std::istream&& stream)
-{
-    return input_stream_adapter(stream);
-}
-
-using contiguous_bytes_input_adapter = decltype(input_adapter(std::declval<const char*>(), std::declval<const char*>()));
-
-// Null-delimited strings, and the like.
-template < typename CharT,
-           typename std::enable_if <
-               std::is_pointer<CharT>::value&&
-               !std::is_array<CharT>::value&&
-               std::is_integral<typename std::remove_pointer<CharT>::type>::value&&
-               sizeof(typename std::remove_pointer<CharT>::type) == 1,
-               int >::type = 0 >
-contiguous_bytes_input_adapter input_adapter(CharT b)
-{
-    auto length = std::strlen(reinterpret_cast<const char*>(b));
-    const auto* ptr = reinterpret_cast<const char*>(b);
-    return input_adapter(ptr, ptr + length);
-}
-
-template<typename T, std::size_t N>
-auto input_adapter(T (&array)[N]) -> decltype(input_adapter(array, array + N))
-{
-    return input_adapter(array, array + N);
-}
-
-// This class only handles inputs of input_buffer_adapter type.
-// It's required so that expressions like {ptr, len} can be implicitely casted
-// to the correct adapter.
-class span_input_adapter
-{
-  public:
-    template < typename CharT,
-               typename std::enable_if <
-                   std::is_pointer<CharT>::value&&
-                   std::is_integral<typename std::remove_pointer<CharT>::type>::value&&
-                   sizeof(typename std::remove_pointer<CharT>::type) == 1,
-                   int >::type = 0 >
-    span_input_adapter(CharT b, std::size_t l)
-        : ia(reinterpret_cast<const char*>(b), reinterpret_cast<const char*>(b) + l) {}
-
-    template<class IteratorType,
-             typename std::enable_if<
-                 std::is_same<typename iterator_traits<IteratorType>::iterator_category, std::random_access_iterator_tag>::value,
-                 int>::type = 0>
-    span_input_adapter(IteratorType first, IteratorType last)
-        : ia(input_adapter(first, last)) {}
-
-    contiguous_bytes_input_adapter&& get()
-    {
-        return std::move(ia);
-    }
-
-  private:
-    contiguous_bytes_input_adapter ia;
-};
-}  // namespace detail
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/input/json_sax.hpp>
-
-
-#include <cstddef>
-#include <string> // string
-#include <utility> // move
-#include <vector> // vector
-
-// #include <nlohmann/detail/exceptions.hpp>
-
-// #include <nlohmann/detail/macro_scope.hpp>
-
-
-namespace nlohmann
-{
-
-/*!
-@brief SAX interface
-
-This class describes the SAX interface used by @ref nlohmann::json::sax_parse.
-Each function is called in different situations while the input is parsed. The
-boolean return value informs the parser whether to continue processing the
-input.
-*/
-template<typename BasicJsonType>
-struct json_sax
-{
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
-    using binary_t = typename BasicJsonType::binary_t;
-
-    /*!
-    @brief a null value was read
-    @return whether parsing should proceed
-    */
-    virtual bool null() = 0;
-
-    /*!
-    @brief a boolean value was read
-    @param[in] val  boolean value
-    @return whether parsing should proceed
-    */
-    virtual bool boolean(bool val) = 0;
-
-    /*!
-    @brief an integer number was read
-    @param[in] val  integer value
-    @return whether parsing should proceed
-    */
-    virtual bool number_integer(number_integer_t val) = 0;
-
-    /*!
-    @brief an unsigned integer number was read
-    @param[in] val  unsigned integer value
-    @return whether parsing should proceed
-    */
-    virtual bool number_unsigned(number_unsigned_t val) = 0;
-
-    /*!
-    @brief an floating-point number was read
-    @param[in] val  floating-point value
-    @param[in] s    raw token value
-    @return whether parsing should proceed
-    */
-    virtual bool number_float(number_float_t val, const string_t& s) = 0;
-
-    /*!
-    @brief a string was read
-    @param[in] val  string value
-    @return whether parsing should proceed
-    @note It is safe to move the passed string.
-    */
-    virtual bool string(string_t& val) = 0;
-
-    /*!
-    @brief a binary string was read
-    @param[in] val  binary value
-    @return whether parsing should proceed
-    @note It is safe to move the passed binary.
-    */
-    virtual bool binary(binary_t& val) = 0;
-
-    /*!
-    @brief the beginning of an object was read
-    @param[in] elements  number of object elements or -1 if unknown
-    @return whether parsing should proceed
-    @note binary formats may report the number of elements
-    */
-    virtual bool start_object(std::size_t elements) = 0;
-
-    /*!
-    @brief an object key was read
-    @param[in] val  object key
-    @return whether parsing should proceed
-    @note It is safe to move the passed string.
-    */
-    virtual bool key(string_t& val) = 0;
-
-    /*!
-    @brief the end of an object was read
-    @return whether parsing should proceed
-    */
-    virtual bool end_object() = 0;
-
-    /*!
-    @brief the beginning of an array was read
-    @param[in] elements  number of array elements or -1 if unknown
-    @return whether parsing should proceed
-    @note binary formats may report the number of elements
-    */
-    virtual bool start_array(std::size_t elements) = 0;
-
-    /*!
-    @brief the end of an array was read
-    @return whether parsing should proceed
-    */
-    virtual bool end_array() = 0;
-
-    /*!
-    @brief a parse error occurred
-    @param[in] position    the position in the input where the error occurs
-    @param[in] last_token  the last read token
-    @param[in] ex          an exception object describing the error
-    @return whether parsing should proceed (must return false)
-    */
-    virtual bool parse_error(std::size_t position,
-                             const std::string& last_token,
-                             const detail::exception& ex) = 0;
-
-    virtual ~json_sax() = default;
-};
-
-
-namespace detail
-{
-/*!
-@brief SAX implementation to create a JSON value from SAX events
-
-This class implements the @ref json_sax interface and processes the SAX events
-to create a JSON value which makes it basically a DOM parser. The structure or
-hierarchy of the JSON value is managed by the stack `ref_stack` which contains
-a pointer to the respective array or object for each recursion depth.
-
-After successful parsing, the value that is passed by reference to the
-constructor contains the parsed value.
-
-@tparam BasicJsonType  the JSON type
-*/
-template<typename BasicJsonType>
-class json_sax_dom_parser
-{
-  public:
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
-    using binary_t = typename BasicJsonType::binary_t;
-
-    /*!
-    @param[in, out] r  reference to a JSON value that is manipulated while
-                       parsing
-    @param[in] allow_exceptions_  whether parse errors yield exceptions
-    */
-    explicit json_sax_dom_parser(BasicJsonType& r, const bool allow_exceptions_ = true)
-        : root(r), allow_exceptions(allow_exceptions_)
-    {}
-
-    // make class move-only
-    json_sax_dom_parser(const json_sax_dom_parser&) = delete;
-    json_sax_dom_parser(json_sax_dom_parser&&) = default;
-    json_sax_dom_parser& operator=(const json_sax_dom_parser&) = delete;
-    json_sax_dom_parser& operator=(json_sax_dom_parser&&) = default;
-    ~json_sax_dom_parser() = default;
-
-    bool null()
-    {
-        handle_value(nullptr);
-        return true;
-    }
-
-    bool boolean(bool val)
-    {
-        handle_value(val);
-        return true;
-    }
-
-    bool number_integer(number_integer_t val)
-    {
-        handle_value(val);
-        return true;
-    }
-
-    bool number_unsigned(number_unsigned_t val)
-    {
-        handle_value(val);
-        return true;
-    }
-
-    bool number_float(number_float_t val, const string_t& /*unused*/)
-    {
-        handle_value(val);
-        return true;
-    }
-
-    bool string(string_t& val)
-    {
-        handle_value(val);
-        return true;
-    }
-
-    bool binary(binary_t& val)
-    {
-        handle_value(std::move(val));
-        return true;
-    }
-
-    bool start_object(std::size_t len)
-    {
-        ref_stack.push_back(handle_value(BasicJsonType::value_t::object));
-
-        if (JSON_HEDLEY_UNLIKELY(len != std::size_t(-1) && len > ref_stack.back()->max_size()))
-        {
-            JSON_THROW(out_of_range::create(408,
-                                            "excessive object size: " + std::to_string(len)));
-        }
-
-        return true;
-    }
-
-    bool key(string_t& val)
-    {
-        // add null at given key and store the reference for later
-        object_element = &(ref_stack.back()->m_value.object->operator[](val));
-        return true;
-    }
-
-    bool end_object()
-    {
-        ref_stack.pop_back();
-        return true;
-    }
-
-    bool start_array(std::size_t len)
-    {
-        ref_stack.push_back(handle_value(BasicJsonType::value_t::array));
-
-        if (JSON_HEDLEY_UNLIKELY(len != std::size_t(-1) && len > ref_stack.back()->max_size()))
-        {
-            JSON_THROW(out_of_range::create(408,
-                                            "excessive array size: " + std::to_string(len)));
-        }
-
-        return true;
-    }
-
-    bool end_array()
-    {
-        ref_stack.pop_back();
-        return true;
-    }
-
-    template<class Exception>
-    bool parse_error(std::size_t /*unused*/, const std::string& /*unused*/,
-                     const Exception& ex)
-    {
-        errored = true;
-        static_cast<void>(ex);
-        if (allow_exceptions)
-        {
-            JSON_THROW(ex);
-        }
-        return false;
-    }
-
-    constexpr bool is_errored() const
-    {
-        return errored;
-    }
-
-  private:
-    /*!
-    @invariant If the ref stack is empty, then the passed value will be the new
-               root.
-    @invariant If the ref stack contains a value, then it is an array or an
-               object to which we can add elements
-    */
-    template<typename Value>
-    JSON_HEDLEY_RETURNS_NON_NULL
-    BasicJsonType* handle_value(Value&& v)
-    {
-        if (ref_stack.empty())
-        {
-            root = BasicJsonType(std::forward<Value>(v));
-            return &root;
-        }
-
-        JSON_ASSERT(ref_stack.back()->is_array() || ref_stack.back()->is_object());
-
-        if (ref_stack.back()->is_array())
-        {
-            ref_stack.back()->m_value.array->emplace_back(std::forward<Value>(v));
-            return &(ref_stack.back()->m_value.array->back());
-        }
-
-        JSON_ASSERT(ref_stack.back()->is_object());
-        JSON_ASSERT(object_element);
-        *object_element = BasicJsonType(std::forward<Value>(v));
-        return object_element;
-    }
-
-    /// the parsed JSON value
-    BasicJsonType& root;
-    /// stack to model hierarchy of values
-    std::vector<BasicJsonType*> ref_stack {};
-    /// helper to hold the reference for the next object element
-    BasicJsonType* object_element = nullptr;
-    /// whether a syntax error occurred
-    bool errored = false;
-    /// whether to throw exceptions in case of errors
-    const bool allow_exceptions = true;
-};
-
-template<typename BasicJsonType>
-class json_sax_dom_callback_parser
-{
-  public:
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
-    using binary_t = typename BasicJsonType::binary_t;
-    using parser_callback_t = typename BasicJsonType::parser_callback_t;
-    using parse_event_t = typename BasicJsonType::parse_event_t;
-
-    json_sax_dom_callback_parser(BasicJsonType& r,
-                                 const parser_callback_t cb,
-                                 const bool allow_exceptions_ = true)
-        : root(r), callback(cb), allow_exceptions(allow_exceptions_)
-    {
-        keep_stack.push_back(true);
-    }
-
-    // make class move-only
-    json_sax_dom_callback_parser(const json_sax_dom_callback_parser&) = delete;
-    json_sax_dom_callback_parser(json_sax_dom_callback_parser&&) = default;
-    json_sax_dom_callback_parser& operator=(const json_sax_dom_callback_parser&) = delete;
-    json_sax_dom_callback_parser& operator=(json_sax_dom_callback_parser&&) = default;
-    ~json_sax_dom_callback_parser() = default;
-
-    bool null()
-    {
-        handle_value(nullptr);
-        return true;
-    }
-
-    bool boolean(bool val)
-    {
-        handle_value(val);
-        return true;
-    }
-
-    bool number_integer(number_integer_t val)
-    {
-        handle_value(val);
-        return true;
-    }
-
-    bool number_unsigned(number_unsigned_t val)
-    {
-        handle_value(val);
-        return true;
-    }
-
-    bool number_float(number_float_t val, const string_t& /*unused*/)
-    {
-        handle_value(val);
-        return true;
-    }
-
-    bool string(string_t& val)
-    {
-        handle_value(val);
-        return true;
-    }
-
-    bool binary(binary_t& val)
-    {
-        handle_value(std::move(val));
-        return true;
-    }
-
-    bool start_object(std::size_t len)
-    {
-        // check callback for object start
-        const bool keep = callback(static_cast<int>(ref_stack.size()), parse_event_t::object_start, discarded);
-        keep_stack.push_back(keep);
-
-        auto val = handle_value(BasicJsonType::value_t::object, true);
-        ref_stack.push_back(val.second);
-
-        // check object limit
-        if (ref_stack.back() && JSON_HEDLEY_UNLIKELY(len != std::size_t(-1) && len > ref_stack.back()->max_size()))
-        {
-            JSON_THROW(out_of_range::create(408, "excessive object size: " + std::to_string(len)));
-        }
-
-        return true;
-    }
-
-    bool key(string_t& val)
-    {
-        BasicJsonType k = BasicJsonType(val);
-
-        // check callback for key
-        const bool keep = callback(static_cast<int>(ref_stack.size()), parse_event_t::key, k);
-        key_keep_stack.push_back(keep);
-
-        // add discarded value at given key and store the reference for later
-        if (keep && ref_stack.back())
-        {
-            object_element = &(ref_stack.back()->m_value.object->operator[](val) = discarded);
-        }
-
-        return true;
-    }
-
-    bool end_object()
-    {
-        if (ref_stack.back() && !callback(static_cast<int>(ref_stack.size()) - 1, parse_event_t::object_end, *ref_stack.back()))
-        {
-            // discard object
-            *ref_stack.back() = discarded;
-        }
-
-        JSON_ASSERT(!ref_stack.empty());
-        JSON_ASSERT(!keep_stack.empty());
-        ref_stack.pop_back();
-        keep_stack.pop_back();
-
-        if (!ref_stack.empty() && ref_stack.back() && ref_stack.back()->is_structured())
-        {
-            // remove discarded value
-            for (auto it = ref_stack.back()->begin(); it != ref_stack.back()->end(); ++it)
-            {
-                if (it->is_discarded())
-                {
-                    ref_stack.back()->erase(it);
-                    break;
-                }
-            }
-        }
-
-        return true;
-    }
-
-    bool start_array(std::size_t len)
-    {
-        const bool keep = callback(static_cast<int>(ref_stack.size()), parse_event_t::array_start, discarded);
-        keep_stack.push_back(keep);
-
-        auto val = handle_value(BasicJsonType::value_t::array, true);
-        ref_stack.push_back(val.second);
-
-        // check array limit
-        if (ref_stack.back() && JSON_HEDLEY_UNLIKELY(len != std::size_t(-1) && len > ref_stack.back()->max_size()))
-        {
-            JSON_THROW(out_of_range::create(408, "excessive array size: " + std::to_string(len)));
-        }
-
-        return true;
-    }
-
-    bool end_array()
-    {
-        bool keep = true;
-
-        if (ref_stack.back())
-        {
-            keep = callback(static_cast<int>(ref_stack.size()) - 1, parse_event_t::array_end, *ref_stack.back());
-            if (!keep)
-            {
-                // discard array
-                *ref_stack.back() = discarded;
-            }
-        }
-
-        JSON_ASSERT(!ref_stack.empty());
-        JSON_ASSERT(!keep_stack.empty());
-        ref_stack.pop_back();
-        keep_stack.pop_back();
-
-        // remove discarded value
-        if (!keep && !ref_stack.empty() && ref_stack.back()->is_array())
-        {
-            ref_stack.back()->m_value.array->pop_back();
-        }
-
-        return true;
-    }
-
-    template<class Exception>
-    bool parse_error(std::size_t /*unused*/, const std::string& /*unused*/,
-                     const Exception& ex)
-    {
-        errored = true;
-        static_cast<void>(ex);
-        if (allow_exceptions)
-        {
-            JSON_THROW(ex);
-        }
-        return false;
-    }
-
-    constexpr bool is_errored() const
-    {
-        return errored;
-    }
-
-  private:
-    /*!
-    @param[in] v  value to add to the JSON value we build during parsing
-    @param[in] skip_callback  whether we should skip calling the callback
-               function; this is required after start_array() and
-               start_object() SAX events, because otherwise we would call the
-               callback function with an empty array or object, respectively.
-
-    @invariant If the ref stack is empty, then the passed value will be the new
-               root.
-    @invariant If the ref stack contains a value, then it is an array or an
-               object to which we can add elements
-
-    @return pair of boolean (whether value should be kept) and pointer (to the
-            passed value in the ref_stack hierarchy; nullptr if not kept)
-    */
-    template<typename Value>
-    std::pair<bool, BasicJsonType*> handle_value(Value&& v, const bool skip_callback = false)
-    {
-        JSON_ASSERT(!keep_stack.empty());
-
-        // do not handle this value if we know it would be added to a discarded
-        // container
-        if (!keep_stack.back())
-        {
-            return {false, nullptr};
-        }
-
-        // create value
-        auto value = BasicJsonType(std::forward<Value>(v));
-
-        // check callback
-        const bool keep = skip_callback || callback(static_cast<int>(ref_stack.size()), parse_event_t::value, value);
-
-        // do not handle this value if we just learnt it shall be discarded
-        if (!keep)
-        {
-            return {false, nullptr};
-        }
-
-        if (ref_stack.empty())
-        {
-            root = std::move(value);
-            return {true, &root};
-        }
-
-        // skip this value if we already decided to skip the parent
-        // (https://github.com/nlohmann/json/issues/971#issuecomment-413678360)
-        if (!ref_stack.back())
-        {
-            return {false, nullptr};
-        }
-
-        // we now only expect arrays and objects
-        JSON_ASSERT(ref_stack.back()->is_array() || ref_stack.back()->is_object());
-
-        // array
-        if (ref_stack.back()->is_array())
-        {
-            ref_stack.back()->m_value.array->push_back(std::move(value));
-            return {true, &(ref_stack.back()->m_value.array->back())};
-        }
-
-        // object
-        JSON_ASSERT(ref_stack.back()->is_object());
-        // check if we should store an element for the current key
-        JSON_ASSERT(!key_keep_stack.empty());
-        const bool store_element = key_keep_stack.back();
-        key_keep_stack.pop_back();
-
-        if (!store_element)
-        {
-            return {false, nullptr};
-        }
-
-        JSON_ASSERT(object_element);
-        *object_element = std::move(value);
-        return {true, object_element};
-    }
-
-    /// the parsed JSON value
-    BasicJsonType& root;
-    /// stack to model hierarchy of values
-    std::vector<BasicJsonType*> ref_stack {};
-    /// stack to manage which values to keep
-    std::vector<bool> keep_stack {};
-    /// stack to manage which object keys to keep
-    std::vector<bool> key_keep_stack {};
-    /// helper to hold the reference for the next object element
-    BasicJsonType* object_element = nullptr;
-    /// whether a syntax error occurred
-    bool errored = false;
-    /// callback function
-    const parser_callback_t callback = nullptr;
-    /// whether to throw exceptions in case of errors
-    const bool allow_exceptions = true;
-    /// a discarded value for the callback
-    BasicJsonType discarded = BasicJsonType::value_t::discarded;
-};
-
-template<typename BasicJsonType>
-class json_sax_acceptor
-{
-  public:
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
-    using binary_t = typename BasicJsonType::binary_t;
-
-    bool null()
-    {
-        return true;
-    }
-
-    bool boolean(bool /*unused*/)
-    {
-        return true;
-    }
-
-    bool number_integer(number_integer_t /*unused*/)
-    {
-        return true;
-    }
-
-    bool number_unsigned(number_unsigned_t /*unused*/)
-    {
-        return true;
-    }
-
-    bool number_float(number_float_t /*unused*/, const string_t& /*unused*/)
-    {
-        return true;
-    }
-
-    bool string(string_t& /*unused*/)
-    {
-        return true;
-    }
-
-    bool binary(binary_t& /*unused*/)
-    {
-        return true;
-    }
-
-    bool start_object(std::size_t /*unused*/ = std::size_t(-1))
-    {
-        return true;
-    }
-
-    bool key(string_t& /*unused*/)
-    {
-        return true;
-    }
-
-    bool end_object()
-    {
-        return true;
-    }
-
-    bool start_array(std::size_t /*unused*/ = std::size_t(-1))
-    {
-        return true;
-    }
-
-    bool end_array()
-    {
-        return true;
-    }
-
-    bool parse_error(std::size_t /*unused*/, const std::string& /*unused*/, const detail::exception& /*unused*/)
-    {
-        return false;
-    }
-};
-}  // namespace detail
-
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/input/lexer.hpp>
-
-
-#include <array> // array
-#include <clocale> // localeconv
-#include <cstddef> // size_t
-#include <cstdio> // snprintf
-#include <cstdlib> // strtof, strtod, strtold, strtoll, strtoull
-#include <initializer_list> // initializer_list
-#include <string> // char_traits, string
-#include <utility> // move
-#include <vector> // vector
-
-// #include <nlohmann/detail/input/input_adapters.hpp>
-
-// #include <nlohmann/detail/input/position_t.hpp>
-
-// #include <nlohmann/detail/macro_scope.hpp>
-
-
-namespace nlohmann
-{
-namespace detail
-{
-///////////
-// lexer //
-///////////
-
-template<typename BasicJsonType>
-class lexer_base
-{
-  public:
-    /// token types for the parser
-    enum class token_type
-    {
-        uninitialized,    ///< indicating the scanner is uninitialized
-        literal_true,     ///< the `true` literal
-        literal_false,    ///< the `false` literal
-        literal_null,     ///< the `null` literal
-        value_string,     ///< a string -- use get_string() for actual value
-        value_unsigned,   ///< an unsigned integer -- use get_number_unsigned() for actual value
-        value_integer,    ///< a signed integer -- use get_number_integer() for actual value
-        value_float,      ///< an floating point number -- use get_number_float() for actual value
-        begin_array,      ///< the character for array begin `[`
-        begin_object,     ///< the character for object begin `{`
-        end_array,        ///< the character for array end `]`
-        end_object,       ///< the character for object end `}`
-        name_separator,   ///< the name separator `:`
-        value_separator,  ///< the value separator `,`
-        parse_error,      ///< indicating a parse error
-        end_of_input,     ///< indicating the end of the input buffer
-        literal_or_value  ///< a literal or the begin of a value (only for diagnostics)
-    };
-
-    /// return name of values of type token_type (only used for errors)
-    JSON_HEDLEY_RETURNS_NON_NULL
-    JSON_HEDLEY_CONST
-    static const char* token_type_name(const token_type t) noexcept
-    {
-        switch (t)
-        {
-            case token_type::uninitialized:
-                return "<uninitialized>";
-            case token_type::literal_true:
-                return "true literal";
-            case token_type::literal_false:
-                return "false literal";
-            case token_type::literal_null:
-                return "null literal";
-            case token_type::value_string:
-                return "string literal";
-            case token_type::value_unsigned:
-            case token_type::value_integer:
-            case token_type::value_float:
-                return "number literal";
-            case token_type::begin_array:
-                return "'['";
-            case token_type::begin_object:
-                return "'{'";
-            case token_type::end_array:
-                return "']'";
-            case token_type::end_object:
-                return "'}'";
-            case token_type::name_separator:
-                return "':'";
-            case token_type::value_separator:
-                return "','";
-            case token_type::parse_error:
-                return "<parse error>";
-            case token_type::end_of_input:
-                return "end of input";
-            case token_type::literal_or_value:
-                return "'[', '{', or a literal";
-            // LCOV_EXCL_START
-            default: // catch non-enum values
-                return "unknown token";
-                // LCOV_EXCL_STOP
-        }
-    }
-};
-/*!
-@brief lexical analysis
-
-This class organizes the lexical analysis during JSON deserialization.
-*/
-template<typename BasicJsonType, typename InputAdapterType>
-class lexer : public lexer_base<BasicJsonType>
-{
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
-    using char_type = typename InputAdapterType::char_type;
-    using char_int_type = typename std::char_traits<char_type>::int_type;
-
-  public:
-    using token_type = typename lexer_base<BasicJsonType>::token_type;
-
-    explicit lexer(InputAdapterType&& adapter, bool ignore_comments_ = false)
-        : ia(std::move(adapter))
-        , ignore_comments(ignore_comments_)
-        , decimal_point_char(static_cast<char_int_type>(get_decimal_point()))
-    {}
-
-    // delete because of pointer members
-    lexer(const lexer&) = delete;
-    lexer(lexer&&) = default;
-    lexer& operator=(lexer&) = delete;
-    lexer& operator=(lexer&&) = default;
-    ~lexer() = default;
-
-  private:
-    /////////////////////
-    // locales
-    /////////////////////
-
-    /// return the locale-dependent decimal point
-    JSON_HEDLEY_PURE
-    static char get_decimal_point() noexcept
-    {
-        const auto* loc = localeconv();
-        JSON_ASSERT(loc != nullptr);
-        return (loc->decimal_point == nullptr) ? '.' : *(loc->decimal_point);
-    }
-
-    /////////////////////
-    // scan functions
-    /////////////////////
-
-    /*!
-    @brief get codepoint from 4 hex characters following `\u`
-
-    For input "\u c1 c2 c3 c4" the codepoint is:
-      (c1 * 0x1000) + (c2 * 0x0100) + (c3 * 0x0010) + c4
-    = (c1 << 12) + (c2 << 8) + (c3 << 4) + (c4 << 0)
-
-    Furthermore, the possible characters '0'..'9', 'A'..'F', and 'a'..'f'
-    must be converted to the integers 0x0..0x9, 0xA..0xF, 0xA..0xF, resp. The
-    conversion is done by subtracting the offset (0x30, 0x37, and 0x57)
-    between the ASCII value of the character and the desired integer value.
-
-    @return codepoint (0x0000..0xFFFF) or -1 in case of an error (e.g. EOF or
-            non-hex character)
-    */
-    int get_codepoint()
-    {
-        // this function only makes sense after reading `\u`
-        JSON_ASSERT(current == 'u');
-        int codepoint = 0;
-
-        const auto factors = { 12u, 8u, 4u, 0u };
-        for (const auto factor : factors)
-        {
-            get();
-
-            if (current >= '0' && current <= '9')
-            {
-                codepoint += static_cast<int>((static_cast<unsigned int>(current) - 0x30u) << factor);
-            }
-            else if (current >= 'A' && current <= 'F')
-            {
-                codepoint += static_cast<int>((static_cast<unsigned int>(current) - 0x37u) << factor);
-            }
-            else if (current >= 'a' && current <= 'f')
-            {
-                codepoint += static_cast<int>((static_cast<unsigned int>(current) - 0x57u) << factor);
-            }
-            else
-            {
-                return -1;
-            }
-        }
-
-        JSON_ASSERT(0x0000 <= codepoint && codepoint <= 0xFFFF);
-        return codepoint;
-    }
-
-    /*!
-    @brief check if the next byte(s) are inside a given range
-
-    Adds the current byte and, for each passed range, reads a new byte and
-    checks if it is inside the range. If a violation was detected, set up an
-    error message and return false. Otherwise, return true.
-
-    @param[in] ranges  list of integers; interpreted as list of pairs of
-                       inclusive lower and upper bound, respectively
-
-    @pre The passed list @a ranges must have 2, 4, or 6 elements; that is,
-         1, 2, or 3 pairs. This precondition is enforced by an assertion.
-
-    @return true if and only if no range violation was detected
-    */
-    bool next_byte_in_range(std::initializer_list<char_int_type> ranges)
-    {
-        JSON_ASSERT(ranges.size() == 2 || ranges.size() == 4 || ranges.size() == 6);
-        add(current);
-
-        for (auto range = ranges.begin(); range != ranges.end(); ++range)
-        {
-            get();
-            if (JSON_HEDLEY_LIKELY(*range <= current && current <= *(++range)))
-            {
-                add(current);
-            }
-            else
-            {
-                error_message = "invalid string: ill-formed UTF-8 byte";
-                return false;
-            }
-        }
-
-        return true;
-    }
-
-    /*!
-    @brief scan a string literal
-
-    This function scans a string according to Sect. 7 of RFC 7159. While
-    scanning, bytes are escaped and copied into buffer token_buffer. Then the
-    function returns successfully, token_buffer is *not* null-terminated (as it
-    may contain \0 bytes), and token_buffer.size() is the number of bytes in the
-    string.
-
-    @return token_type::value_string if string could be successfully scanned,
-            token_type::parse_error otherwise
-
-    @note In case of errors, variable error_message contains a textual
-          description.
-    */
-    token_type scan_string()
-    {
-        // reset token_buffer (ignore opening quote)
-        reset();
-
-        // we entered the function by reading an open quote
-        JSON_ASSERT(current == '\"');
-
-        while (true)
-        {
-            // get next character
-            switch (get())
-            {
-                // end of file while parsing string
-                case std::char_traits<char_type>::eof():
-                {
-                    error_message = "invalid string: missing closing quote";
-                    return token_type::parse_error;
-                }
-
-                // closing quote
-                case '\"':
-                {
-                    return token_type::value_string;
-                }
-
-                // escapes
-                case '\\':
-                {
-                    switch (get())
-                    {
-                        // quotation mark
-                        case '\"':
-                            add('\"');
-                            break;
-                        // reverse solidus
-                        case '\\':
-                            add('\\');
-                            break;
-                        // solidus
-                        case '/':
-                            add('/');
-                            break;
-                        // backspace
-                        case 'b':
-                            add('\b');
-                            break;
-                        // form feed
-                        case 'f':
-                            add('\f');
-                            break;
-                        // line feed
-                        case 'n':
-                            add('\n');
-                            break;
-                        // carriage return
-                        case 'r':
-                            add('\r');
-                            break;
-                        // tab
-                        case 't':
-                            add('\t');
-                            break;
-
-                        // unicode escapes
-                        case 'u':
-                        {
-                            const int codepoint1 = get_codepoint();
-                            int codepoint = codepoint1; // start with codepoint1
-
-                            if (JSON_HEDLEY_UNLIKELY(codepoint1 == -1))
-                            {
-                                error_message = "invalid string: '\\u' must be followed by 4 hex digits";
-                                return token_type::parse_error;
-                            }
-
-                            // check if code point is a high surrogate
-                            if (0xD800 <= codepoint1 && codepoint1 <= 0xDBFF)
-                            {
-                                // expect next \uxxxx entry
-                                if (JSON_HEDLEY_LIKELY(get() == '\\' && get() == 'u'))
-                                {
-                                    const int codepoint2 = get_codepoint();
-
-                                    if (JSON_HEDLEY_UNLIKELY(codepoint2 == -1))
-                                    {
-                                        error_message = "invalid string: '\\u' must be followed by 4 hex digits";
-                                        return token_type::parse_error;
-                                    }
-
-                                    // check if codepoint2 is a low surrogate
-                                    if (JSON_HEDLEY_LIKELY(0xDC00 <= codepoint2 && codepoint2 <= 0xDFFF))
-                                    {
-                                        // overwrite codepoint
-                                        codepoint = static_cast<int>(
-                                                        // high surrogate occupies the most significant 22 bits
-                                                        (static_cast<unsigned int>(codepoint1) << 10u)
-                                                        // low surrogate occupies the least significant 15 bits
-                                                        + static_cast<unsigned int>(codepoint2)
-                                                        // there is still the 0xD800, 0xDC00 and 0x10000 noise
-                                                        // in the result so we have to subtract with:
-                                                        // (0xD800 << 10) + DC00 - 0x10000 = 0x35FDC00
-                                                        - 0x35FDC00u);
-                                    }
-                                    else
-                                    {
-                                        error_message = "invalid string: surrogate U+D800..U+DBFF must be followed by U+DC00..U+DFFF";
-                                        return token_type::parse_error;
-                                    }
-                                }
-                                else
-                                {
-                                    error_message = "invalid string: surrogate U+D800..U+DBFF must be followed by U+DC00..U+DFFF";
-                                    return token_type::parse_error;
-                                }
-                            }
-                            else
-                            {
-                                if (JSON_HEDLEY_UNLIKELY(0xDC00 <= codepoint1 && codepoint1 <= 0xDFFF))
-                                {
-                                    error_message = "invalid string: surrogate U+DC00..U+DFFF must follow U+D800..U+DBFF";
-                                    return token_type::parse_error;
-                                }
-                            }
-
-                            // result of the above calculation yields a proper codepoint
-                            JSON_ASSERT(0x00 <= codepoint && codepoint <= 0x10FFFF);
-
-                            // translate codepoint into bytes
-                            if (codepoint < 0x80)
-                            {
-                                // 1-byte characters: 0xxxxxxx (ASCII)
-                                add(static_cast<char_int_type>(codepoint));
-                            }
-                            else if (codepoint <= 0x7FF)
-                            {
-                                // 2-byte characters: 110xxxxx 10xxxxxx
-                                add(static_cast<char_int_type>(0xC0u | (static_cast<unsigned int>(codepoint) >> 6u)));
-                                add(static_cast<char_int_type>(0x80u | (static_cast<unsigned int>(codepoint) & 0x3Fu)));
-                            }
-                            else if (codepoint <= 0xFFFF)
-                            {
-                                // 3-byte characters: 1110xxxx 10xxxxxx 10xxxxxx
-                                add(static_cast<char_int_type>(0xE0u | (static_cast<unsigned int>(codepoint) >> 12u)));
-                                add(static_cast<char_int_type>(0x80u | ((static_cast<unsigned int>(codepoint) >> 6u) & 0x3Fu)));
-                                add(static_cast<char_int_type>(0x80u | (static_cast<unsigned int>(codepoint) & 0x3Fu)));
-                            }
-                            else
-                            {
-                                // 4-byte characters: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
-                                add(static_cast<char_int_type>(0xF0u | (static_cast<unsigned int>(codepoint) >> 18u)));
-                                add(static_cast<char_int_type>(0x80u | ((static_cast<unsigned int>(codepoint) >> 12u) & 0x3Fu)));
-                                add(static_cast<char_int_type>(0x80u | ((static_cast<unsigned int>(codepoint) >> 6u) & 0x3Fu)));
-                                add(static_cast<char_int_type>(0x80u | (static_cast<unsigned int>(codepoint) & 0x3Fu)));
-                            }
-
-                            break;
-                        }
-
-                        // other characters after escape
-                        default:
-                            error_message = "invalid string: forbidden character after backslash";
-                            return token_type::parse_error;
-                    }
-
-                    break;
-                }
-
-                // invalid control characters
-                case 0x00:
-                {
-                    error_message = "invalid string: control character U+0000 (NUL) must be escaped to \\u0000";
-                    return token_type::parse_error;
-                }
-
-                case 0x01:
-                {
-                    error_message = "invalid string: control character U+0001 (SOH) must be escaped to \\u0001";
-                    return token_type::parse_error;
-                }
-
-                case 0x02:
-                {
-                    error_message = "invalid string: control character U+0002 (STX) must be escaped to \\u0002";
-                    return token_type::parse_error;
-                }
-
-                case 0x03:
-                {
-                    error_message = "invalid string: control character U+0003 (ETX) must be escaped to \\u0003";
-                    return token_type::parse_error;
-                }
-
-                case 0x04:
-                {
-                    error_message = "invalid string: control character U+0004 (EOT) must be escaped to \\u0004";
-                    return token_type::parse_error;
-                }
-
-                case 0x05:
-                {
-                    error_message = "invalid string: control character U+0005 (ENQ) must be escaped to \\u0005";
-                    return token_type::parse_error;
-                }
-
-                case 0x06:
-                {
-                    error_message = "invalid string: control character U+0006 (ACK) must be escaped to \\u0006";
-                    return token_type::parse_error;
-                }
-
-                case 0x07:
-                {
-                    error_message = "invalid string: control character U+0007 (BEL) must be escaped to \\u0007";
-                    return token_type::parse_error;
-                }
-
-                case 0x08:
-                {
-                    error_message = "invalid string: control character U+0008 (BS) must be escaped to \\u0008 or \\b";
-                    return token_type::parse_error;
-                }
-
-                case 0x09:
-                {
-                    error_message = "invalid string: control character U+0009 (HT) must be escaped to \\u0009 or \\t";
-                    return token_type::parse_error;
-                }
-
-                case 0x0A:
-                {
-                    error_message = "invalid string: control character U+000A (LF) must be escaped to \\u000A or \\n";
-                    return token_type::parse_error;
-                }
-
-                case 0x0B:
-                {
-                    error_message = "invalid string: control character U+000B (VT) must be escaped to \\u000B";
-                    return token_type::parse_error;
-                }
-
-                case 0x0C:
-                {
-                    error_message = "invalid string: control character U+000C (FF) must be escaped to \\u000C or \\f";
-                    return token_type::parse_error;
-                }
-
-                case 0x0D:
-                {
-                    error_message = "invalid string: control character U+000D (CR) must be escaped to \\u000D or \\r";
-                    return token_type::parse_error;
-                }
-
-                case 0x0E:
-                {
-                    error_message = "invalid string: control character U+000E (SO) must be escaped to \\u000E";
-                    return token_type::parse_error;
-                }
-
-                case 0x0F:
-                {
-                    error_message = "invalid string: control character U+000F (SI) must be escaped to \\u000F";
-                    return token_type::parse_error;
-                }
-
-                case 0x10:
-                {
-                    error_message = "invalid string: control character U+0010 (DLE) must be escaped to \\u0010";
-                    return token_type::parse_error;
-                }
-
-                case 0x11:
-                {
-                    error_message = "invalid string: control character U+0011 (DC1) must be escaped to \\u0011";
-                    return token_type::parse_error;
-                }
-
-                case 0x12:
-                {
-                    error_message = "invalid string: control character U+0012 (DC2) must be escaped to \\u0012";
-                    return token_type::parse_error;
-                }
-
-                case 0x13:
-                {
-                    error_message = "invalid string: control character U+0013 (DC3) must be escaped to \\u0013";
-                    return token_type::parse_error;
-                }
-
-                case 0x14:
-                {
-                    error_message = "invalid string: control character U+0014 (DC4) must be escaped to \\u0014";
-                    return token_type::parse_error;
-                }
-
-                case 0x15:
-                {
-                    error_message = "invalid string: control character U+0015 (NAK) must be escaped to \\u0015";
-                    return token_type::parse_error;
-                }
-
-                case 0x16:
-                {
-                    error_message = "invalid string: control character U+0016 (SYN) must be escaped to \\u0016";
-                    return token_type::parse_error;
-                }
-
-                case 0x17:
-                {
-                    error_message = "invalid string: control character U+0017 (ETB) must be escaped to \\u0017";
-                    return token_type::parse_error;
-                }
-
-                case 0x18:
-                {
-                    error_message = "invalid string: control character U+0018 (CAN) must be escaped to \\u0018";
-                    return token_type::parse_error;
-                }
-
-                case 0x19:
-                {
-                    error_message = "invalid string: control character U+0019 (EM) must be escaped to \\u0019";
-                    return token_type::parse_error;
-                }
-
-                case 0x1A:
-                {
-                    error_message = "invalid string: control character U+001A (SUB) must be escaped to \\u001A";
-                    return token_type::parse_error;
-                }
-
-                case 0x1B:
-                {
-                    error_message = "invalid string: control character U+001B (ESC) must be escaped to \\u001B";
-                    return token_type::parse_error;
-                }
-
-                case 0x1C:
-                {
-                    error_message = "invalid string: control character U+001C (FS) must be escaped to \\u001C";
-                    return token_type::parse_error;
-                }
-
-                case 0x1D:
-                {
-                    error_message = "invalid string: control character U+001D (GS) must be escaped to \\u001D";
-                    return token_type::parse_error;
-                }
-
-                case 0x1E:
-                {
-                    error_message = "invalid string: control character U+001E (RS) must be escaped to \\u001E";
-                    return token_type::parse_error;
-                }
-
-                case 0x1F:
-                {
-                    error_message = "invalid string: control character U+001F (US) must be escaped to \\u001F";
-                    return token_type::parse_error;
-                }
-
-                // U+0020..U+007F (except U+0022 (quote) and U+005C (backspace))
-                case 0x20:
-                case 0x21:
-                case 0x23:
-                case 0x24:
-                case 0x25:
-                case 0x26:
-                case 0x27:
-                case 0x28:
-                case 0x29:
-                case 0x2A:
-                case 0x2B:
-                case 0x2C:
-                case 0x2D:
-                case 0x2E:
-                case 0x2F:
-                case 0x30:
-                case 0x31:
-                case 0x32:
-                case 0x33:
-                case 0x34:
-                case 0x35:
-                case 0x36:
-                case 0x37:
-                case 0x38:
-                case 0x39:
-                case 0x3A:
-                case 0x3B:
-                case 0x3C:
-                case 0x3D:
-                case 0x3E:
-                case 0x3F:
-                case 0x40:
-                case 0x41:
-                case 0x42:
-                case 0x43:
-                case 0x44:
-                case 0x45:
-                case 0x46:
-                case 0x47:
-                case 0x48:
-                case 0x49:
-                case 0x4A:
-                case 0x4B:
-                case 0x4C:
-                case 0x4D:
-                case 0x4E:
-                case 0x4F:
-                case 0x50:
-                case 0x51:
-                case 0x52:
-                case 0x53:
-                case 0x54:
-                case 0x55:
-                case 0x56:
-                case 0x57:
-                case 0x58:
-                case 0x59:
-                case 0x5A:
-                case 0x5B:
-                case 0x5D:
-                case 0x5E:
-                case 0x5F:
-                case 0x60:
-                case 0x61:
-                case 0x62:
-                case 0x63:
-                case 0x64:
-                case 0x65:
-                case 0x66:
-                case 0x67:
-                case 0x68:
-                case 0x69:
-                case 0x6A:
-                case 0x6B:
-                case 0x6C:
-                case 0x6D:
-                case 0x6E:
-                case 0x6F:
-                case 0x70:
-                case 0x71:
-                case 0x72:
-                case 0x73:
-                case 0x74:
-                case 0x75:
-                case 0x76:
-                case 0x77:
-                case 0x78:
-                case 0x79:
-                case 0x7A:
-                case 0x7B:
-                case 0x7C:
-                case 0x7D:
-                case 0x7E:
-                case 0x7F:
-                {
-                    add(current);
-                    break;
-                }
-
-                // U+0080..U+07FF: bytes C2..DF 80..BF
-                case 0xC2:
-                case 0xC3:
-                case 0xC4:
-                case 0xC5:
-                case 0xC6:
-                case 0xC7:
-                case 0xC8:
-                case 0xC9:
-                case 0xCA:
-                case 0xCB:
-                case 0xCC:
-                case 0xCD:
-                case 0xCE:
-                case 0xCF:
-                case 0xD0:
-                case 0xD1:
-                case 0xD2:
-                case 0xD3:
-                case 0xD4:
-                case 0xD5:
-                case 0xD6:
-                case 0xD7:
-                case 0xD8:
-                case 0xD9:
-                case 0xDA:
-                case 0xDB:
-                case 0xDC:
-                case 0xDD:
-                case 0xDE:
-                case 0xDF:
-                {
-                    if (JSON_HEDLEY_UNLIKELY(!next_byte_in_range({0x80, 0xBF})))
-                    {
-                        return token_type::parse_error;
-                    }
-                    break;
-                }
-
-                // U+0800..U+0FFF: bytes E0 A0..BF 80..BF
-                case 0xE0:
-                {
-                    if (JSON_HEDLEY_UNLIKELY(!(next_byte_in_range({0xA0, 0xBF, 0x80, 0xBF}))))
-                    {
-                        return token_type::parse_error;
-                    }
-                    break;
-                }
-
-                // U+1000..U+CFFF: bytes E1..EC 80..BF 80..BF
-                // U+E000..U+FFFF: bytes EE..EF 80..BF 80..BF
-                case 0xE1:
-                case 0xE2:
-                case 0xE3:
-                case 0xE4:
-                case 0xE5:
-                case 0xE6:
-                case 0xE7:
-                case 0xE8:
-                case 0xE9:
-                case 0xEA:
-                case 0xEB:
-                case 0xEC:
-                case 0xEE:
-                case 0xEF:
-                {
-                    if (JSON_HEDLEY_UNLIKELY(!(next_byte_in_range({0x80, 0xBF, 0x80, 0xBF}))))
-                    {
-                        return token_type::parse_error;
-                    }
-                    break;
-                }
-
-                // U+D000..U+D7FF: bytes ED 80..9F 80..BF
-                case 0xED:
-                {
-                    if (JSON_HEDLEY_UNLIKELY(!(next_byte_in_range({0x80, 0x9F, 0x80, 0xBF}))))
-                    {
-                        return token_type::parse_error;
-                    }
-                    break;
-                }
-
-                // U+10000..U+3FFFF F0 90..BF 80..BF 80..BF
-                case 0xF0:
-                {
-                    if (JSON_HEDLEY_UNLIKELY(!(next_byte_in_range({0x90, 0xBF, 0x80, 0xBF, 0x80, 0xBF}))))
-                    {
-                        return token_type::parse_error;
-                    }
-                    break;
-                }
-
-                // U+40000..U+FFFFF F1..F3 80..BF 80..BF 80..BF
-                case 0xF1:
-                case 0xF2:
-                case 0xF3:
-                {
-                    if (JSON_HEDLEY_UNLIKELY(!(next_byte_in_range({0x80, 0xBF, 0x80, 0xBF, 0x80, 0xBF}))))
-                    {
-                        return token_type::parse_error;
-                    }
-                    break;
-                }
-
-                // U+100000..U+10FFFF F4 80..8F 80..BF 80..BF
-                case 0xF4:
-                {
-                    if (JSON_HEDLEY_UNLIKELY(!(next_byte_in_range({0x80, 0x8F, 0x80, 0xBF, 0x80, 0xBF}))))
-                    {
-                        return token_type::parse_error;
-                    }
-                    break;
-                }
-
-                // remaining bytes (80..C1 and F5..FF) are ill-formed
-                default:
-                {
-                    error_message = "invalid string: ill-formed UTF-8 byte";
-                    return token_type::parse_error;
-                }
-            }
-        }
-    }
-
-    /*!
-     * @brief scan a comment
-     * @return whether comment could be scanned successfully
-     */
-    bool scan_comment()
-    {
-        switch (get())
-        {
-            // single-line comments skip input until a newline or EOF is read
-            case '/':
-            {
-                while (true)
-                {
-                    switch (get())
-                    {
-                        case '\n':
-                        case '\r':
-                        case std::char_traits<char_type>::eof():
-                        case '\0':
-                            return true;
-
-                        default:
-                            break;
-                    }
-                }
-            }
-
-            // multi-line comments skip input until */ is read
-            case '*':
-            {
-                while (true)
-                {
-                    switch (get())
-                    {
-                        case std::char_traits<char_type>::eof():
-                        case '\0':
-                        {
-                            error_message = "invalid comment; missing closing '*/'";
-                            return false;
-                        }
-
-                        case '*':
-                        {
-                            switch (get())
-                            {
-                                case '/':
-                                    return true;
-
-                                default:
-                                {
-                                    unget();
-                                    continue;
-                                }
-                            }
-                        }
-
-                        default:
-                            continue;
-                    }
-                }
-            }
-
-            // unexpected character after reading '/'
-            default:
-            {
-                error_message = "invalid comment; expecting '/' or '*' after '/'";
-                return false;
-            }
-        }
-    }
-
-    JSON_HEDLEY_NON_NULL(2)
-    static void strtof(float& f, const char* str, char** endptr) noexcept
-    {
-        f = std::strtof(str, endptr);
-    }
-
-    JSON_HEDLEY_NON_NULL(2)
-    static void strtof(double& f, const char* str, char** endptr) noexcept
-    {
-        f = std::strtod(str, endptr);
-    }
-
-    JSON_HEDLEY_NON_NULL(2)
-    static void strtof(long double& f, const char* str, char** endptr) noexcept
-    {
-        f = std::strtold(str, endptr);
-    }
-
-    /*!
-    @brief scan a number literal
-
-    This function scans a string according to Sect. 6 of RFC 7159.
-
-    The function is realized with a deterministic finite state machine derived
-    from the grammar described in RFC 7159. Starting in state "init", the
-    input is read and used to determined the next state. Only state "done"
-    accepts the number. State "error" is a trap state to model errors. In the
-    table below, "anything" means any character but the ones listed before.
-
-    state    | 0        | 1-9      | e E      | +       | -       | .        | anything
-    ---------|----------|----------|----------|---------|---------|----------|-----------
-    init     | zero     | any1     | [error]  | [error] | minus   | [error]  | [error]
-    minus    | zero     | any1     | [error]  | [error] | [error] | [error]  | [error]
-    zero     | done     | done     | exponent | done    | done    | decimal1 | done
-    any1     | any1     | any1     | exponent | done    | done    | decimal1 | done
-    decimal1 | decimal2 | decimal2 | [error]  | [error] | [error] | [error]  | [error]
-    decimal2 | decimal2 | decimal2 | exponent | done    | done    | done     | done
-    exponent | any2     | any2     | [error]  | sign    | sign    | [error]  | [error]
-    sign     | any2     | any2     | [error]  | [error] | [error] | [error]  | [error]
-    any2     | any2     | any2     | done     | done    | done    | done     | done
-
-    The state machine is realized with one label per state (prefixed with
-    "scan_number_") and `goto` statements between them. The state machine
-    contains cycles, but any cycle can be left when EOF is read. Therefore,
-    the function is guaranteed to terminate.
-
-    During scanning, the read bytes are stored in token_buffer. This string is
-    then converted to a signed integer, an unsigned integer, or a
-    floating-point number.
-
-    @return token_type::value_unsigned, token_type::value_integer, or
-            token_type::value_float if number could be successfully scanned,
-            token_type::parse_error otherwise
-
-    @note The scanner is independent of the current locale. Internally, the
-          locale's decimal point is used instead of `.` to work with the
-          locale-dependent converters.
-    */
-    token_type scan_number()  // lgtm [cpp/use-of-goto]
-    {
-        // reset token_buffer to store the number's bytes
-        reset();
-
-        // the type of the parsed number; initially set to unsigned; will be
-        // changed if minus sign, decimal point or exponent is read
-        token_type number_type = token_type::value_unsigned;
-
-        // state (init): we just found out we need to scan a number
-        switch (current)
-        {
-            case '-':
-            {
-                add(current);
-                goto scan_number_minus;
-            }
-
-            case '0':
-            {
-                add(current);
-                goto scan_number_zero;
-            }
-
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-            {
-                add(current);
-                goto scan_number_any1;
-            }
-
-            // all other characters are rejected outside scan_number()
-            default:            // LCOV_EXCL_LINE
-                JSON_ASSERT(false);  // LCOV_EXCL_LINE
-        }
-
-scan_number_minus:
-        // state: we just parsed a leading minus sign
-        number_type = token_type::value_integer;
-        switch (get())
-        {
-            case '0':
-            {
-                add(current);
-                goto scan_number_zero;
-            }
-
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-            {
-                add(current);
-                goto scan_number_any1;
-            }
-
-            default:
-            {
-                error_message = "invalid number; expected digit after '-'";
-                return token_type::parse_error;
-            }
-        }
-
-scan_number_zero:
-        // state: we just parse a zero (maybe with a leading minus sign)
-        switch (get())
-        {
-            case '.':
-            {
-                add(decimal_point_char);
-                goto scan_number_decimal1;
-            }
-
-            case 'e':
-            case 'E':
-            {
-                add(current);
-                goto scan_number_exponent;
-            }
-
-            default:
-                goto scan_number_done;
-        }
-
-scan_number_any1:
-        // state: we just parsed a number 0-9 (maybe with a leading minus sign)
-        switch (get())
-        {
-            case '0':
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-            {
-                add(current);
-                goto scan_number_any1;
-            }
-
-            case '.':
-            {
-                add(decimal_point_char);
-                goto scan_number_decimal1;
-            }
-
-            case 'e':
-            case 'E':
-            {
-                add(current);
-                goto scan_number_exponent;
-            }
-
-            default:
-                goto scan_number_done;
-        }
-
-scan_number_decimal1:
-        // state: we just parsed a decimal point
-        number_type = token_type::value_float;
-        switch (get())
-        {
-            case '0':
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-            {
-                add(current);
-                goto scan_number_decimal2;
-            }
-
-            default:
-            {
-                error_message = "invalid number; expected digit after '.'";
-                return token_type::parse_error;
-            }
-        }
-
-scan_number_decimal2:
-        // we just parsed at least one number after a decimal point
-        switch (get())
-        {
-            case '0':
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-            {
-                add(current);
-                goto scan_number_decimal2;
-            }
-
-            case 'e':
-            case 'E':
-            {
-                add(current);
-                goto scan_number_exponent;
-            }
-
-            default:
-                goto scan_number_done;
-        }
-
-scan_number_exponent:
-        // we just parsed an exponent
-        number_type = token_type::value_float;
-        switch (get())
-        {
-            case '+':
-            case '-':
-            {
-                add(current);
-                goto scan_number_sign;
-            }
-
-            case '0':
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-            {
-                add(current);
-                goto scan_number_any2;
-            }
-
-            default:
-            {
-                error_message =
-                    "invalid number; expected '+', '-', or digit after exponent";
-                return token_type::parse_error;
-            }
-        }
-
-scan_number_sign:
-        // we just parsed an exponent sign
-        switch (get())
-        {
-            case '0':
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-            {
-                add(current);
-                goto scan_number_any2;
-            }
-
-            default:
-            {
-                error_message = "invalid number; expected digit after exponent sign";
-                return token_type::parse_error;
-            }
-        }
-
-scan_number_any2:
-        // we just parsed a number after the exponent or exponent sign
-        switch (get())
-        {
-            case '0':
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-            {
-                add(current);
-                goto scan_number_any2;
-            }
-
-            default:
-                goto scan_number_done;
-        }
-
-scan_number_done:
-        // unget the character after the number (we only read it to know that
-        // we are done scanning a number)
-        unget();
-
-        char* endptr = nullptr;
-        errno = 0;
-
-        // try to parse integers first and fall back to floats
-        if (number_type == token_type::value_unsigned)
-        {
-            const auto x = std::strtoull(token_buffer.data(), &endptr, 10);
-
-            // we checked the number format before
-            JSON_ASSERT(endptr == token_buffer.data() + token_buffer.size());
-
-            if (errno == 0)
-            {
-                value_unsigned = static_cast<number_unsigned_t>(x);
-                if (value_unsigned == x)
-                {
-                    return token_type::value_unsigned;
-                }
-            }
-        }
-        else if (number_type == token_type::value_integer)
-        {
-            const auto x = std::strtoll(token_buffer.data(), &endptr, 10);
-
-            // we checked the number format before
-            JSON_ASSERT(endptr == token_buffer.data() + token_buffer.size());
-
-            if (errno == 0)
-            {
-                value_integer = static_cast<number_integer_t>(x);
-                if (value_integer == x)
-                {
-                    return token_type::value_integer;
-                }
-            }
-        }
-
-        // this code is reached if we parse a floating-point number or if an
-        // integer conversion above failed
-        strtof(value_float, token_buffer.data(), &endptr);
-
-        // we checked the number format before
-        JSON_ASSERT(endptr == token_buffer.data() + token_buffer.size());
-
-        return token_type::value_float;
-    }
-
-    /*!
-    @param[in] literal_text  the literal text to expect
-    @param[in] length        the length of the passed literal text
-    @param[in] return_type   the token type to return on success
-    */
-    JSON_HEDLEY_NON_NULL(2)
-    token_type scan_literal(const char_type* literal_text, const std::size_t length,
-                            token_type return_type)
-    {
-        JSON_ASSERT(std::char_traits<char_type>::to_char_type(current) == literal_text[0]);
-        for (std::size_t i = 1; i < length; ++i)
-        {
-            if (JSON_HEDLEY_UNLIKELY(std::char_traits<char_type>::to_char_type(get()) != literal_text[i]))
-            {
-                error_message = "invalid literal";
-                return token_type::parse_error;
-            }
-        }
-        return return_type;
-    }
-
-    /////////////////////
-    // input management
-    /////////////////////
-
-    /// reset token_buffer; current character is beginning of token
-    void reset() noexcept
-    {
-        token_buffer.clear();
-        token_string.clear();
-        token_string.push_back(std::char_traits<char_type>::to_char_type(current));
-    }
-
-    /*
-    @brief get next character from the input
-
-    This function provides the interface to the used input adapter. It does
-    not throw in case the input reached EOF, but returns a
-    `std::char_traits<char>::eof()` in that case.  Stores the scanned characters
-    for use in error messages.
-
-    @return character read from the input
-    */
-    char_int_type get()
-    {
-        ++position.chars_read_total;
-        ++position.chars_read_current_line;
-
-        if (next_unget)
-        {
-            // just reset the next_unget variable and work with current
-            next_unget = false;
-        }
-        else
-        {
-            current = ia.get_character();
-        }
-
-        if (JSON_HEDLEY_LIKELY(current != std::char_traits<char_type>::eof()))
-        {
-            token_string.push_back(std::char_traits<char_type>::to_char_type(current));
-        }
-
-        if (current == '\n')
-        {
-            ++position.lines_read;
-            position.chars_read_current_line = 0;
-        }
-
-        return current;
-    }
-
-    /*!
-    @brief unget current character (read it again on next get)
-
-    We implement unget by setting variable next_unget to true. The input is not
-    changed - we just simulate ungetting by modifying chars_read_total,
-    chars_read_current_line, and token_string. The next call to get() will
-    behave as if the unget character is read again.
-    */
-    void unget()
-    {
-        next_unget = true;
-
-        --position.chars_read_total;
-
-        // in case we "unget" a newline, we have to also decrement the lines_read
-        if (position.chars_read_current_line == 0)
-        {
-            if (position.lines_read > 0)
-            {
-                --position.lines_read;
-            }
-        }
-        else
-        {
-            --position.chars_read_current_line;
-        }
-
-        if (JSON_HEDLEY_LIKELY(current != std::char_traits<char_type>::eof()))
-        {
-            JSON_ASSERT(!token_string.empty());
-            token_string.pop_back();
-        }
-    }
-
-    /// add a character to token_buffer
-    void add(char_int_type c)
-    {
-        token_buffer.push_back(static_cast<typename string_t::value_type>(c));
-    }
-
-  public:
-    /////////////////////
-    // value getters
-    /////////////////////
-
-    /// return integer value
-    constexpr number_integer_t get_number_integer() const noexcept
-    {
-        return value_integer;
-    }
-
-    /// return unsigned integer value
-    constexpr number_unsigned_t get_number_unsigned() const noexcept
-    {
-        return value_unsigned;
-    }
-
-    /// return floating-point value
-    constexpr number_float_t get_number_float() const noexcept
-    {
-        return value_float;
-    }
-
-    /// return current string value (implicitly resets the token; useful only once)
-    string_t& get_string()
-    {
-        return token_buffer;
-    }
-
-    /////////////////////
-    // diagnostics
-    /////////////////////
-
-    /// return position of last read token
-    constexpr position_t get_position() const noexcept
-    {
-        return position;
-    }
-
-    /// return the last read token (for errors only).  Will never contain EOF
-    /// (an arbitrary value that is not a valid char value, often -1), because
-    /// 255 may legitimately occur.  May contain NUL, which should be escaped.
-    std::string get_token_string() const
-    {
-        // escape control characters
-        std::string result;
-        for (const auto c : token_string)
-        {
-            if (static_cast<unsigned char>(c) <= '\x1F')
-            {
-                // escape control characters
-                std::array<char, 9> cs{{}};
-                (std::snprintf)(cs.data(), cs.size(), "<U+%.4X>", static_cast<unsigned char>(c));
-                result += cs.data();
-            }
-            else
-            {
-                // add character as is
-                result.push_back(static_cast<std::string::value_type>(c));
-            }
-        }
-
-        return result;
-    }
-
-    /// return syntax error message
-    JSON_HEDLEY_RETURNS_NON_NULL
-    constexpr const char* get_error_message() const noexcept
-    {
-        return error_message;
-    }
-
-    /////////////////////
-    // actual scanner
-    /////////////////////
-
-    /*!
-    @brief skip the UTF-8 byte order mark
-    @return true iff there is no BOM or the correct BOM has been skipped
-    */
-    bool skip_bom()
-    {
-        if (get() == 0xEF)
-        {
-            // check if we completely parse the BOM
-            return get() == 0xBB && get() == 0xBF;
-        }
-
-        // the first character is not the beginning of the BOM; unget it to
-        // process is later
-        unget();
-        return true;
-    }
-
-    void skip_whitespace()
-    {
-        do
-        {
-            get();
-        }
-        while (current == ' ' || current == '\t' || current == '\n' || current == '\r');
-    }
-
-    token_type scan()
-    {
-        // initially, skip the BOM
-        if (position.chars_read_total == 0 && !skip_bom())
-        {
-            error_message = "invalid BOM; must be 0xEF 0xBB 0xBF if given";
-            return token_type::parse_error;
-        }
-
-        // read next character and ignore whitespace
-        skip_whitespace();
-
-        // ignore comments
-        while (ignore_comments && current == '/')
-        {
-            if (!scan_comment())
-            {
-                return token_type::parse_error;
-            }
-
-            // skip following whitespace
-            skip_whitespace();
-        }
-
-        switch (current)
-        {
-            // structural characters
-            case '[':
-                return token_type::begin_array;
-            case ']':
-                return token_type::end_array;
-            case '{':
-                return token_type::begin_object;
-            case '}':
-                return token_type::end_object;
-            case ':':
-                return token_type::name_separator;
-            case ',':
-                return token_type::value_separator;
-
-            // literals
-            case 't':
-            {
-                std::array<char_type, 4> true_literal = {{'t', 'r', 'u', 'e'}};
-                return scan_literal(true_literal.data(), true_literal.size(), token_type::literal_true);
-            }
-            case 'f':
-            {
-                std::array<char_type, 5> false_literal = {{'f', 'a', 'l', 's', 'e'}};
-                return scan_literal(false_literal.data(), false_literal.size(), token_type::literal_false);
-            }
-            case 'n':
-            {
-                std::array<char_type, 4> null_literal = {{'n', 'u', 'l', 'l'}};
-                return scan_literal(null_literal.data(), null_literal.size(), token_type::literal_null);
-            }
-
-            // string
-            case '\"':
-                return scan_string();
-
-            // number
-            case '-':
-            case '0':
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-                return scan_number();
-
-            // end of input (the null byte is needed when parsing from
-            // string literals)
-            case '\0':
-            case std::char_traits<char_type>::eof():
-                return token_type::end_of_input;
-
-            // error
-            default:
-                error_message = "invalid literal";
-                return token_type::parse_error;
-        }
-    }
-
-  private:
-    /// input adapter
-    InputAdapterType ia;
-
-    /// whether comments should be ignored (true) or signaled as errors (false)
-    const bool ignore_comments = false;
-
-    /// the current character
-    char_int_type current = std::char_traits<char_type>::eof();
-
-    /// whether the next get() call should just return current
-    bool next_unget = false;
-
-    /// the start position of the current token
-    position_t position {};
-
-    /// raw input token string (for error messages)
-    std::vector<char_type> token_string {};
-
-    /// buffer for variable-length tokens (numbers, strings)
-    string_t token_buffer {};
-
-    /// a description of occurred lexer errors
-    const char* error_message = "";
-
-    // number values
-    number_integer_t value_integer = 0;
-    number_unsigned_t value_unsigned = 0;
-    number_float_t value_float = 0;
-
-    /// the decimal point
-    const char_int_type decimal_point_char = '.';
-};
-}  // namespace detail
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/macro_scope.hpp>
-
-// #include <nlohmann/detail/meta/is_sax.hpp>
-
-
-#include <cstdint> // size_t
-#include <utility> // declval
-#include <string> // string
-
-// #include <nlohmann/detail/meta/detected.hpp>
-
-// #include <nlohmann/detail/meta/type_traits.hpp>
-
-
-namespace nlohmann
-{
-namespace detail
-{
-template<typename T>
-using null_function_t = decltype(std::declval<T&>().null());
-
-template<typename T>
-using boolean_function_t =
-    decltype(std::declval<T&>().boolean(std::declval<bool>()));
-
-template<typename T, typename Integer>
-using number_integer_function_t =
-    decltype(std::declval<T&>().number_integer(std::declval<Integer>()));
-
-template<typename T, typename Unsigned>
-using number_unsigned_function_t =
-    decltype(std::declval<T&>().number_unsigned(std::declval<Unsigned>()));
-
-template<typename T, typename Float, typename String>
-using number_float_function_t = decltype(std::declval<T&>().number_float(
-                                    std::declval<Float>(), std::declval<const String&>()));
-
-template<typename T, typename String>
-using string_function_t =
-    decltype(std::declval<T&>().string(std::declval<String&>()));
-
-template<typename T, typename Binary>
-using binary_function_t =
-    decltype(std::declval<T&>().binary(std::declval<Binary&>()));
-
-template<typename T>
-using start_object_function_t =
-    decltype(std::declval<T&>().start_object(std::declval<std::size_t>()));
-
-template<typename T, typename String>
-using key_function_t =
-    decltype(std::declval<T&>().key(std::declval<String&>()));
-
-template<typename T>
-using end_object_function_t = decltype(std::declval<T&>().end_object());
-
-template<typename T>
-using start_array_function_t =
-    decltype(std::declval<T&>().start_array(std::declval<std::size_t>()));
-
-template<typename T>
-using end_array_function_t = decltype(std::declval<T&>().end_array());
-
-template<typename T, typename Exception>
-using parse_error_function_t = decltype(std::declval<T&>().parse_error(
-        std::declval<std::size_t>(), std::declval<const std::string&>(),
-        std::declval<const Exception&>()));
-
-template<typename SAX, typename BasicJsonType>
-struct is_sax
-{
-  private:
-    static_assert(is_basic_json<BasicJsonType>::value,
-                  "BasicJsonType must be of type basic_json<...>");
-
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
-    using binary_t = typename BasicJsonType::binary_t;
-    using exception_t = typename BasicJsonType::exception;
-
-  public:
-    static constexpr bool value =
-        is_detected_exact<bool, null_function_t, SAX>::value &&
-        is_detected_exact<bool, boolean_function_t, SAX>::value &&
-        is_detected_exact<bool, number_integer_function_t, SAX, number_integer_t>::value &&
-        is_detected_exact<bool, number_unsigned_function_t, SAX, number_unsigned_t>::value &&
-        is_detected_exact<bool, number_float_function_t, SAX, number_float_t, string_t>::value &&
-        is_detected_exact<bool, string_function_t, SAX, string_t>::value &&
-        is_detected_exact<bool, binary_function_t, SAX, binary_t>::value &&
-        is_detected_exact<bool, start_object_function_t, SAX>::value &&
-        is_detected_exact<bool, key_function_t, SAX, string_t>::value &&
-        is_detected_exact<bool, end_object_function_t, SAX>::value &&
-        is_detected_exact<bool, start_array_function_t, SAX>::value &&
-        is_detected_exact<bool, end_array_function_t, SAX>::value &&
-        is_detected_exact<bool, parse_error_function_t, SAX, exception_t>::value;
-};
-
-template<typename SAX, typename BasicJsonType>
-struct is_sax_static_asserts
-{
-  private:
-    static_assert(is_basic_json<BasicJsonType>::value,
-                  "BasicJsonType must be of type basic_json<...>");
-
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
-    using binary_t = typename BasicJsonType::binary_t;
-    using exception_t = typename BasicJsonType::exception;
-
-  public:
-    static_assert(is_detected_exact<bool, null_function_t, SAX>::value,
-                  "Missing/invalid function: bool null()");
-    static_assert(is_detected_exact<bool, boolean_function_t, SAX>::value,
-                  "Missing/invalid function: bool boolean(bool)");
-    static_assert(is_detected_exact<bool, boolean_function_t, SAX>::value,
-                  "Missing/invalid function: bool boolean(bool)");
-    static_assert(
-        is_detected_exact<bool, number_integer_function_t, SAX,
-        number_integer_t>::value,
-        "Missing/invalid function: bool number_integer(number_integer_t)");
-    static_assert(
-        is_detected_exact<bool, number_unsigned_function_t, SAX,
-        number_unsigned_t>::value,
-        "Missing/invalid function: bool number_unsigned(number_unsigned_t)");
-    static_assert(is_detected_exact<bool, number_float_function_t, SAX,
-                  number_float_t, string_t>::value,
-                  "Missing/invalid function: bool number_float(number_float_t, const string_t&)");
-    static_assert(
-        is_detected_exact<bool, string_function_t, SAX, string_t>::value,
-        "Missing/invalid function: bool string(string_t&)");
-    static_assert(
-        is_detected_exact<bool, binary_function_t, SAX, binary_t>::value,
-        "Missing/invalid function: bool binary(binary_t&)");
-    static_assert(is_detected_exact<bool, start_object_function_t, SAX>::value,
-                  "Missing/invalid function: bool start_object(std::size_t)");
-    static_assert(is_detected_exact<bool, key_function_t, SAX, string_t>::value,
-                  "Missing/invalid function: bool key(string_t&)");
-    static_assert(is_detected_exact<bool, end_object_function_t, SAX>::value,
-                  "Missing/invalid function: bool end_object()");
-    static_assert(is_detected_exact<bool, start_array_function_t, SAX>::value,
-                  "Missing/invalid function: bool start_array(std::size_t)");
-    static_assert(is_detected_exact<bool, end_array_function_t, SAX>::value,
-                  "Missing/invalid function: bool end_array()");
-    static_assert(
-        is_detected_exact<bool, parse_error_function_t, SAX, exception_t>::value,
-        "Missing/invalid function: bool parse_error(std::size_t, const "
-        "std::string&, const exception&)");
-};
-}  // namespace detail
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/value_t.hpp>
-
-
-namespace nlohmann
-{
-namespace detail
-{
-
-/// how to treat CBOR tags
-enum class cbor_tag_handler_t
-{
-    error,  ///< throw a parse_error exception in case of a tag
-    ignore   ///< ignore tags
-};
-
-/*!
-@brief determine system byte order
-
-@return true if and only if system's byte order is little endian
-
-@note from https://stackoverflow.com/a/1001328/266378
-*/
-static inline bool little_endianess(int num = 1) noexcept
-{
-    return *reinterpret_cast<char*>(&num) == 1;
-}
-
-
-///////////////////
-// binary reader //
-///////////////////
-
-/*!
-@brief deserialization of CBOR, MessagePack, and UBJSON values
-*/
-template<typename BasicJsonType, typename InputAdapterType, typename SAX = json_sax_dom_parser<BasicJsonType>>
-class binary_reader
-{
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
-    using binary_t = typename BasicJsonType::binary_t;
-    using json_sax_t = SAX;
-    using char_type = typename InputAdapterType::char_type;
-    using char_int_type = typename std::char_traits<char_type>::int_type;
-
-  public:
-    /*!
-    @brief create a binary reader
-
-    @param[in] adapter  input adapter to read from
-    */
-    explicit binary_reader(InputAdapterType&& adapter) : ia(std::move(adapter))
-    {
-        (void)detail::is_sax_static_asserts<SAX, BasicJsonType> {};
-    }
-
-    // make class move-only
-    binary_reader(const binary_reader&) = delete;
-    binary_reader(binary_reader&&) = default;
-    binary_reader& operator=(const binary_reader&) = delete;
-    binary_reader& operator=(binary_reader&&) = default;
-    ~binary_reader() = default;
-
-    /*!
-    @param[in] format  the binary format to parse
-    @param[in] sax_    a SAX event processor
-    @param[in] strict  whether to expect the input to be consumed completed
-    @param[in] tag_handler  how to treat CBOR tags
-
-    @return
-    */
-    JSON_HEDLEY_NON_NULL(3)
-    bool sax_parse(const input_format_t format,
-                   json_sax_t* sax_,
-                   const bool strict = true,
-                   const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error)
-    {
-        sax = sax_;
-        bool result = false;
-
-        switch (format)
-        {
-            case input_format_t::bson:
-                result = parse_bson_internal();
-                break;
-
-            case input_format_t::cbor:
-                result = parse_cbor_internal(true, tag_handler);
-                break;
-
-            case input_format_t::msgpack:
-                result = parse_msgpack_internal();
-                break;
-
-            case input_format_t::ubjson:
-                result = parse_ubjson_internal();
-                break;
-
-            default:            // LCOV_EXCL_LINE
-                JSON_ASSERT(false);  // LCOV_EXCL_LINE
-        }
-
-        // strict mode: next byte must be EOF
-        if (result && strict)
-        {
-            if (format == input_format_t::ubjson)
-            {
-                get_ignore_noop();
-            }
-            else
-            {
-                get();
-            }
-
-            if (JSON_HEDLEY_UNLIKELY(current != std::char_traits<char_type>::eof()))
-            {
-                return sax->parse_error(chars_read, get_token_string(),
-                                        parse_error::create(110, chars_read, exception_message(format, "expected end of input; last byte: 0x" + get_token_string(), "value")));
-            }
-        }
-
-        return result;
-    }
-
-  private:
-    //////////
-    // BSON //
-    //////////
-
-    /*!
-    @brief Reads in a BSON-object and passes it to the SAX-parser.
-    @return whether a valid BSON-value was passed to the SAX parser
-    */
-    bool parse_bson_internal()
-    {
-        std::int32_t document_size{};
-        get_number<std::int32_t, true>(input_format_t::bson, document_size);
-
-        if (JSON_HEDLEY_UNLIKELY(!sax->start_object(std::size_t(-1))))
-        {
-            return false;
-        }
-
-        if (JSON_HEDLEY_UNLIKELY(!parse_bson_element_list(/*is_array*/false)))
-        {
-            return false;
-        }
-
-        return sax->end_object();
-    }
-
-    /*!
-    @brief Parses a C-style string from the BSON input.
-    @param[in, out] result  A reference to the string variable where the read
-                            string is to be stored.
-    @return `true` if the \x00-byte indicating the end of the string was
-             encountered before the EOF; false` indicates an unexpected EOF.
-    */
-    bool get_bson_cstr(string_t& result)
-    {
-        auto out = std::back_inserter(result);
-        while (true)
-        {
-            get();
-            if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(input_format_t::bson, "cstring")))
-            {
-                return false;
-            }
-            if (current == 0x00)
-            {
-                return true;
-            }
-            *out++ = static_cast<typename string_t::value_type>(current);
-        }
-    }
-
-    /*!
-    @brief Parses a zero-terminated string of length @a len from the BSON
-           input.
-    @param[in] len  The length (including the zero-byte at the end) of the
-                    string to be read.
-    @param[in, out] result  A reference to the string variable where the read
-                            string is to be stored.
-    @tparam NumberType The type of the length @a len
-    @pre len >= 1
-    @return `true` if the string was successfully parsed
-    */
-    template<typename NumberType>
-    bool get_bson_string(const NumberType len, string_t& result)
-    {
-        if (JSON_HEDLEY_UNLIKELY(len < 1))
-        {
-            auto last_token = get_token_string();
-            return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read, exception_message(input_format_t::bson, "string length must be at least 1, is " + std::to_string(len), "string")));
-        }
-
-        return get_string(input_format_t::bson, len - static_cast<NumberType>(1), result) && get() != std::char_traits<char_type>::eof();
-    }
-
-    /*!
-    @brief Parses a byte array input of length @a len from the BSON input.
-    @param[in] len  The length of the byte array to be read.
-    @param[in, out] result  A reference to the binary variable where the read
-                            array is to be stored.
-    @tparam NumberType The type of the length @a len
-    @pre len >= 0
-    @return `true` if the byte array was successfully parsed
-    */
-    template<typename NumberType>
-    bool get_bson_binary(const NumberType len, binary_t& result)
-    {
-        if (JSON_HEDLEY_UNLIKELY(len < 0))
-        {
-            auto last_token = get_token_string();
-            return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read, exception_message(input_format_t::bson, "byte array length cannot be negative, is " + std::to_string(len), "binary")));
-        }
-
-        // All BSON binary values have a subtype
-        std::uint8_t subtype{};
-        get_number<std::uint8_t>(input_format_t::bson, subtype);
-        result.set_subtype(subtype);
-
-        return get_binary(input_format_t::bson, len, result);
-    }
-
-    /*!
-    @brief Read a BSON document element of the given @a element_type.
-    @param[in] element_type The BSON element type, c.f. http://bsonspec.org/spec.html
-    @param[in] element_type_parse_position The position in the input stream,
-               where the `element_type` was read.
-    @warning Not all BSON element types are supported yet. An unsupported
-             @a element_type will give rise to a parse_error.114:
-             Unsupported BSON record type 0x...
-    @return whether a valid BSON-object/array was passed to the SAX parser
-    */
-    bool parse_bson_element_internal(const char_int_type element_type,
-                                     const std::size_t element_type_parse_position)
-    {
-        switch (element_type)
-        {
-            case 0x01: // double
-            {
-                double number{};
-                return get_number<double, true>(input_format_t::bson, number) && sax->number_float(static_cast<number_float_t>(number), "");
-            }
-
-            case 0x02: // string
-            {
-                std::int32_t len{};
-                string_t value;
-                return get_number<std::int32_t, true>(input_format_t::bson, len) && get_bson_string(len, value) && sax->string(value);
-            }
-
-            case 0x03: // object
-            {
-                return parse_bson_internal();
-            }
-
-            case 0x04: // array
-            {
-                return parse_bson_array();
-            }
-
-            case 0x05: // binary
-            {
-                std::int32_t len{};
-                binary_t value;
-                return get_number<std::int32_t, true>(input_format_t::bson, len) && get_bson_binary(len, value) && sax->binary(value);
-            }
-
-            case 0x08: // boolean
-            {
-                return sax->boolean(get() != 0);
-            }
-
-            case 0x0A: // null
-            {
-                return sax->null();
-            }
-
-            case 0x10: // int32
-            {
-                std::int32_t value{};
-                return get_number<std::int32_t, true>(input_format_t::bson, value) && sax->number_integer(value);
-            }
-
-            case 0x12: // int64
-            {
-                std::int64_t value{};
-                return get_number<std::int64_t, true>(input_format_t::bson, value) && sax->number_integer(value);
-            }
-
-            default: // anything else not supported (yet)
-            {
-                std::array<char, 3> cr{{}};
-                (std::snprintf)(cr.data(), cr.size(), "%.2hhX", static_cast<unsigned char>(element_type));
-                return sax->parse_error(element_type_parse_position, std::string(cr.data()), parse_error::create(114, element_type_parse_position, "Unsupported BSON record type 0x" + std::string(cr.data())));
-            }
-        }
-    }
-
-    /*!
-    @brief Read a BSON element list (as specified in the BSON-spec)
-
-    The same binary layout is used for objects and arrays, hence it must be
-    indicated with the argument @a is_array which one is expected
-    (true --> array, false --> object).
-
-    @param[in] is_array Determines if the element list being read is to be
-                        treated as an object (@a is_array == false), or as an
-                        array (@a is_array == true).
-    @return whether a valid BSON-object/array was passed to the SAX parser
-    */
-    bool parse_bson_element_list(const bool is_array)
-    {
-        string_t key;
-
-        while (auto element_type = get())
-        {
-            if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(input_format_t::bson, "element list")))
-            {
-                return false;
-            }
-
-            const std::size_t element_type_parse_position = chars_read;
-            if (JSON_HEDLEY_UNLIKELY(!get_bson_cstr(key)))
-            {
-                return false;
-            }
-
-            if (!is_array && !sax->key(key))
-            {
-                return false;
-            }
-
-            if (JSON_HEDLEY_UNLIKELY(!parse_bson_element_internal(element_type, element_type_parse_position)))
-            {
-                return false;
-            }
-
-            // get_bson_cstr only appends
-            key.clear();
-        }
-
-        return true;
-    }
-
-    /*!
-    @brief Reads an array from the BSON input and passes it to the SAX-parser.
-    @return whether a valid BSON-array was passed to the SAX parser
-    */
-    bool parse_bson_array()
-    {
-        std::int32_t document_size{};
-        get_number<std::int32_t, true>(input_format_t::bson, document_size);
-
-        if (JSON_HEDLEY_UNLIKELY(!sax->start_array(std::size_t(-1))))
-        {
-            return false;
-        }
-
-        if (JSON_HEDLEY_UNLIKELY(!parse_bson_element_list(/*is_array*/true)))
-        {
-            return false;
-        }
-
-        return sax->end_array();
-    }
-
-    //////////
-    // CBOR //
-    //////////
-
-    /*!
-    @param[in] get_char  whether a new character should be retrieved from the
-                         input (true) or whether the last read character should
-                         be considered instead (false)
-    @param[in] tag_handler how CBOR tags should be treated
-
-    @return whether a valid CBOR value was passed to the SAX parser
-    */
-    bool parse_cbor_internal(const bool get_char,
-                             const cbor_tag_handler_t tag_handler)
-    {
-        switch (get_char ? get() : current)
-        {
-            // EOF
-            case std::char_traits<char_type>::eof():
-                return unexpect_eof(input_format_t::cbor, "value");
-
-            // Integer 0x00..0x17 (0..23)
-            case 0x00:
-            case 0x01:
-            case 0x02:
-            case 0x03:
-            case 0x04:
-            case 0x05:
-            case 0x06:
-            case 0x07:
-            case 0x08:
-            case 0x09:
-            case 0x0A:
-            case 0x0B:
-            case 0x0C:
-            case 0x0D:
-            case 0x0E:
-            case 0x0F:
-            case 0x10:
-            case 0x11:
-            case 0x12:
-            case 0x13:
-            case 0x14:
-            case 0x15:
-            case 0x16:
-            case 0x17:
-                return sax->number_unsigned(static_cast<number_unsigned_t>(current));
-
-            case 0x18: // Unsigned integer (one-byte uint8_t follows)
-            {
-                std::uint8_t number{};
-                return get_number(input_format_t::cbor, number) && sax->number_unsigned(number);
-            }
-
-            case 0x19: // Unsigned integer (two-byte uint16_t follows)
-            {
-                std::uint16_t number{};
-                return get_number(input_format_t::cbor, number) && sax->number_unsigned(number);
-            }
-
-            case 0x1A: // Unsigned integer (four-byte uint32_t follows)
-            {
-                std::uint32_t number{};
-                return get_number(input_format_t::cbor, number) && sax->number_unsigned(number);
-            }
-
-            case 0x1B: // Unsigned integer (eight-byte uint64_t follows)
-            {
-                std::uint64_t number{};
-                return get_number(input_format_t::cbor, number) && sax->number_unsigned(number);
-            }
-
-            // Negative integer -1-0x00..-1-0x17 (-1..-24)
-            case 0x20:
-            case 0x21:
-            case 0x22:
-            case 0x23:
-            case 0x24:
-            case 0x25:
-            case 0x26:
-            case 0x27:
-            case 0x28:
-            case 0x29:
-            case 0x2A:
-            case 0x2B:
-            case 0x2C:
-            case 0x2D:
-            case 0x2E:
-            case 0x2F:
-            case 0x30:
-            case 0x31:
-            case 0x32:
-            case 0x33:
-            case 0x34:
-            case 0x35:
-            case 0x36:
-            case 0x37:
-                return sax->number_integer(static_cast<std::int8_t>(0x20 - 1 - current));
-
-            case 0x38: // Negative integer (one-byte uint8_t follows)
-            {
-                std::uint8_t number{};
-                return get_number(input_format_t::cbor, number) && sax->number_integer(static_cast<number_integer_t>(-1) - number);
-            }
-
-            case 0x39: // Negative integer -1-n (two-byte uint16_t follows)
-            {
-                std::uint16_t number{};
-                return get_number(input_format_t::cbor, number) && sax->number_integer(static_cast<number_integer_t>(-1) - number);
-            }
-
-            case 0x3A: // Negative integer -1-n (four-byte uint32_t follows)
-            {
-                std::uint32_t number{};
-                return get_number(input_format_t::cbor, number) && sax->number_integer(static_cast<number_integer_t>(-1) - number);
-            }
-
-            case 0x3B: // Negative integer -1-n (eight-byte uint64_t follows)
-            {
-                std::uint64_t number{};
-                return get_number(input_format_t::cbor, number) && sax->number_integer(static_cast<number_integer_t>(-1)
-                        - static_cast<number_integer_t>(number));
-            }
-
-            // Binary data (0x00..0x17 bytes follow)
-            case 0x40:
-            case 0x41:
-            case 0x42:
-            case 0x43:
-            case 0x44:
-            case 0x45:
-            case 0x46:
-            case 0x47:
-            case 0x48:
-            case 0x49:
-            case 0x4A:
-            case 0x4B:
-            case 0x4C:
-            case 0x4D:
-            case 0x4E:
-            case 0x4F:
-            case 0x50:
-            case 0x51:
-            case 0x52:
-            case 0x53:
-            case 0x54:
-            case 0x55:
-            case 0x56:
-            case 0x57:
-            case 0x58: // Binary data (one-byte uint8_t for n follows)
-            case 0x59: // Binary data (two-byte uint16_t for n follow)
-            case 0x5A: // Binary data (four-byte uint32_t for n follow)
-            case 0x5B: // Binary data (eight-byte uint64_t for n follow)
-            case 0x5F: // Binary data (indefinite length)
-            {
-                binary_t b;
-                return get_cbor_binary(b) && sax->binary(b);
-            }
-
-            // UTF-8 string (0x00..0x17 bytes follow)
-            case 0x60:
-            case 0x61:
-            case 0x62:
-            case 0x63:
-            case 0x64:
-            case 0x65:
-            case 0x66:
-            case 0x67:
-            case 0x68:
-            case 0x69:
-            case 0x6A:
-            case 0x6B:
-            case 0x6C:
-            case 0x6D:
-            case 0x6E:
-            case 0x6F:
-            case 0x70:
-            case 0x71:
-            case 0x72:
-            case 0x73:
-            case 0x74:
-            case 0x75:
-            case 0x76:
-            case 0x77:
-            case 0x78: // UTF-8 string (one-byte uint8_t for n follows)
-            case 0x79: // UTF-8 string (two-byte uint16_t for n follow)
-            case 0x7A: // UTF-8 string (four-byte uint32_t for n follow)
-            case 0x7B: // UTF-8 string (eight-byte uint64_t for n follow)
-            case 0x7F: // UTF-8 string (indefinite length)
-            {
-                string_t s;
-                return get_cbor_string(s) && sax->string(s);
-            }
-
-            // array (0x00..0x17 data items follow)
-            case 0x80:
-            case 0x81:
-            case 0x82:
-            case 0x83:
-            case 0x84:
-            case 0x85:
-            case 0x86:
-            case 0x87:
-            case 0x88:
-            case 0x89:
-            case 0x8A:
-            case 0x8B:
-            case 0x8C:
-            case 0x8D:
-            case 0x8E:
-            case 0x8F:
-            case 0x90:
-            case 0x91:
-            case 0x92:
-            case 0x93:
-            case 0x94:
-            case 0x95:
-            case 0x96:
-            case 0x97:
-                return get_cbor_array(static_cast<std::size_t>(static_cast<unsigned int>(current) & 0x1Fu), tag_handler);
-
-            case 0x98: // array (one-byte uint8_t for n follows)
-            {
-                std::uint8_t len{};
-                return get_number(input_format_t::cbor, len) && get_cbor_array(static_cast<std::size_t>(len), tag_handler);
-            }
-
-            case 0x99: // array (two-byte uint16_t for n follow)
-            {
-                std::uint16_t len{};
-                return get_number(input_format_t::cbor, len) && get_cbor_array(static_cast<std::size_t>(len), tag_handler);
-            }
-
-            case 0x9A: // array (four-byte uint32_t for n follow)
-            {
-                std::uint32_t len{};
-                return get_number(input_format_t::cbor, len) && get_cbor_array(static_cast<std::size_t>(len), tag_handler);
-            }
-
-            case 0x9B: // array (eight-byte uint64_t for n follow)
-            {
-                std::uint64_t len{};
-                return get_number(input_format_t::cbor, len) && get_cbor_array(static_cast<std::size_t>(len), tag_handler);
-            }
-
-            case 0x9F: // array (indefinite length)
-                return get_cbor_array(std::size_t(-1), tag_handler);
-
-            // map (0x00..0x17 pairs of data items follow)
-            case 0xA0:
-            case 0xA1:
-            case 0xA2:
-            case 0xA3:
-            case 0xA4:
-            case 0xA5:
-            case 0xA6:
-            case 0xA7:
-            case 0xA8:
-            case 0xA9:
-            case 0xAA:
-            case 0xAB:
-            case 0xAC:
-            case 0xAD:
-            case 0xAE:
-            case 0xAF:
-            case 0xB0:
-            case 0xB1:
-            case 0xB2:
-            case 0xB3:
-            case 0xB4:
-            case 0xB5:
-            case 0xB6:
-            case 0xB7:
-                return get_cbor_object(static_cast<std::size_t>(static_cast<unsigned int>(current) & 0x1Fu), tag_handler);
-
-            case 0xB8: // map (one-byte uint8_t for n follows)
-            {
-                std::uint8_t len{};
-                return get_number(input_format_t::cbor, len) && get_cbor_object(static_cast<std::size_t>(len), tag_handler);
-            }
-
-            case 0xB9: // map (two-byte uint16_t for n follow)
-            {
-                std::uint16_t len{};
-                return get_number(input_format_t::cbor, len) && get_cbor_object(static_cast<std::size_t>(len), tag_handler);
-            }
-
-            case 0xBA: // map (four-byte uint32_t for n follow)
-            {
-                std::uint32_t len{};
-                return get_number(input_format_t::cbor, len) && get_cbor_object(static_cast<std::size_t>(len), tag_handler);
-            }
-
-            case 0xBB: // map (eight-byte uint64_t for n follow)
-            {
-                std::uint64_t len{};
-                return get_number(input_format_t::cbor, len) && get_cbor_object(static_cast<std::size_t>(len), tag_handler);
-            }
-
-            case 0xBF: // map (indefinite length)
-                return get_cbor_object(std::size_t(-1), tag_handler);
-
-            case 0xC6: // tagged item
-            case 0xC7:
-            case 0xC8:
-            case 0xC9:
-            case 0xCA:
-            case 0xCB:
-            case 0xCC:
-            case 0xCD:
-            case 0xCE:
-            case 0xCF:
-            case 0xD0:
-            case 0xD1:
-            case 0xD2:
-            case 0xD3:
-            case 0xD4:
-            case 0xD8: // tagged item (1 bytes follow)
-            case 0xD9: // tagged item (2 bytes follow)
-            case 0xDA: // tagged item (4 bytes follow)
-            case 0xDB: // tagged item (8 bytes follow)
-            {
-                switch (tag_handler)
-                {
-                    case cbor_tag_handler_t::error:
-                    {
-                        auto last_token = get_token_string();
-                        return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read, exception_message(input_format_t::cbor, "invalid byte: 0x" + last_token, "value")));
-                    }
-
-                    case cbor_tag_handler_t::ignore:
-                    {
-                        switch (current)
-                        {
-                            case 0xD8:
-                            {
-                                std::uint8_t len{};
-                                get_number(input_format_t::cbor, len);
-                                break;
-                            }
-                            case 0xD9:
-                            {
-                                std::uint16_t len{};
-                                get_number(input_format_t::cbor, len);
-                                break;
-                            }
-                            case 0xDA:
-                            {
-                                std::uint32_t len{};
-                                get_number(input_format_t::cbor, len);
-                                break;
-                            }
-                            case 0xDB:
-                            {
-                                std::uint64_t len{};
-                                get_number(input_format_t::cbor, len);
-                                break;
-                            }
-                            default:
-                                break;
-                        }
-                        return parse_cbor_internal(true, tag_handler);
-                    }
-
-                    default:            // LCOV_EXCL_LINE
-                        JSON_ASSERT(false);  // LCOV_EXCL_LINE
-                }
-            }
-
-            case 0xF4: // false
-                return sax->boolean(false);
-
-            case 0xF5: // true
-                return sax->boolean(true);
-
-            case 0xF6: // null
-                return sax->null();
-
-            case 0xF9: // Half-Precision Float (two-byte IEEE 754)
-            {
-                const auto byte1_raw = get();
-                if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(input_format_t::cbor, "number")))
-                {
-                    return false;
-                }
-                const auto byte2_raw = get();
-                if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(input_format_t::cbor, "number")))
-                {
-                    return false;
-                }
-
-                const auto byte1 = static_cast<unsigned char>(byte1_raw);
-                const auto byte2 = static_cast<unsigned char>(byte2_raw);
-
-                // code from RFC 7049, Appendix D, Figure 3:
-                // As half-precision floating-point numbers were only added
-                // to IEEE 754 in 2008, today's programming platforms often
-                // still only have limited support for them. It is very
-                // easy to include at least decoding support for them even
-                // without such support. An example of a small decoder for
-                // half-precision floating-point numbers in the C language
-                // is shown in Fig. 3.
-                const auto half = static_cast<unsigned int>((byte1 << 8u) + byte2);
-                const double val = [&half]
-                {
-                    const int exp = (half >> 10u) & 0x1Fu;
-                    const unsigned int mant = half & 0x3FFu;
-                    JSON_ASSERT(0 <= exp&& exp <= 32);
-                    JSON_ASSERT(mant <= 1024);
-                    switch (exp)
-                    {
-                        case 0:
-                            return std::ldexp(mant, -24);
-                        case 31:
-                            return (mant == 0)
-                            ? std::numeric_limits<double>::infinity()
-                            : std::numeric_limits<double>::quiet_NaN();
-                        default:
-                            return std::ldexp(mant + 1024, exp - 25);
-                    }
-                }();
-                return sax->number_float((half & 0x8000u) != 0
-                                         ? static_cast<number_float_t>(-val)
-                                         : static_cast<number_float_t>(val), "");
-            }
-
-            case 0xFA: // Single-Precision Float (four-byte IEEE 754)
-            {
-                float number{};
-                return get_number(input_format_t::cbor, number) && sax->number_float(static_cast<number_float_t>(number), "");
-            }
-
-            case 0xFB: // Double-Precision Float (eight-byte IEEE 754)
-            {
-                double number{};
-                return get_number(input_format_t::cbor, number) && sax->number_float(static_cast<number_float_t>(number), "");
-            }
-
-            default: // anything else (0xFF is handled inside the other types)
-            {
-                auto last_token = get_token_string();
-                return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read, exception_message(input_format_t::cbor, "invalid byte: 0x" + last_token, "value")));
-            }
-        }
-    }
-
-    /*!
-    @brief reads a CBOR string
-
-    This function first reads starting bytes to determine the expected
-    string length and then copies this number of bytes into a string.
-    Additionally, CBOR's strings with indefinite lengths are supported.
-
-    @param[out] result  created string
-
-    @return whether string creation completed
-    */
-    bool get_cbor_string(string_t& result)
-    {
-        if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(input_format_t::cbor, "string")))
-        {
-            return false;
-        }
-
-        switch (current)
-        {
-            // UTF-8 string (0x00..0x17 bytes follow)
-            case 0x60:
-            case 0x61:
-            case 0x62:
-            case 0x63:
-            case 0x64:
-            case 0x65:
-            case 0x66:
-            case 0x67:
-            case 0x68:
-            case 0x69:
-            case 0x6A:
-            case 0x6B:
-            case 0x6C:
-            case 0x6D:
-            case 0x6E:
-            case 0x6F:
-            case 0x70:
-            case 0x71:
-            case 0x72:
-            case 0x73:
-            case 0x74:
-            case 0x75:
-            case 0x76:
-            case 0x77:
-            {
-                return get_string(input_format_t::cbor, static_cast<unsigned int>(current) & 0x1Fu, result);
-            }
-
-            case 0x78: // UTF-8 string (one-byte uint8_t for n follows)
-            {
-                std::uint8_t len{};
-                return get_number(input_format_t::cbor, len) && get_string(input_format_t::cbor, len, result);
-            }
-
-            case 0x79: // UTF-8 string (two-byte uint16_t for n follow)
-            {
-                std::uint16_t len{};
-                return get_number(input_format_t::cbor, len) && get_string(input_format_t::cbor, len, result);
-            }
-
-            case 0x7A: // UTF-8 string (four-byte uint32_t for n follow)
-            {
-                std::uint32_t len{};
-                return get_number(input_format_t::cbor, len) && get_string(input_format_t::cbor, len, result);
-            }
-
-            case 0x7B: // UTF-8 string (eight-byte uint64_t for n follow)
-            {
-                std::uint64_t len{};
-                return get_number(input_format_t::cbor, len) && get_string(input_format_t::cbor, len, result);
-            }
-
-            case 0x7F: // UTF-8 string (indefinite length)
-            {
-                while (get() != 0xFF)
-                {
-                    string_t chunk;
-                    if (!get_cbor_string(chunk))
-                    {
-                        return false;
-                    }
-                    result.append(chunk);
-                }
-                return true;
-            }
-
-            default:
-            {
-                auto last_token = get_token_string();
-                return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read, exception_message(input_format_t::cbor, "expected length specification (0x60-0x7B) or indefinite string type (0x7F); last byte: 0x" + last_token, "string")));
-            }
-        }
-    }
-
-    /*!
-    @brief reads a CBOR byte array
-
-    This function first reads starting bytes to determine the expected
-    byte array length and then copies this number of bytes into the byte array.
-    Additionally, CBOR's byte arrays with indefinite lengths are supported.
-
-    @param[out] result  created byte array
-
-    @return whether byte array creation completed
-    */
-    bool get_cbor_binary(binary_t& result)
-    {
-        if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(input_format_t::cbor, "binary")))
-        {
-            return false;
-        }
-
-        switch (current)
-        {
-            // Binary data (0x00..0x17 bytes follow)
-            case 0x40:
-            case 0x41:
-            case 0x42:
-            case 0x43:
-            case 0x44:
-            case 0x45:
-            case 0x46:
-            case 0x47:
-            case 0x48:
-            case 0x49:
-            case 0x4A:
-            case 0x4B:
-            case 0x4C:
-            case 0x4D:
-            case 0x4E:
-            case 0x4F:
-            case 0x50:
-            case 0x51:
-            case 0x52:
-            case 0x53:
-            case 0x54:
-            case 0x55:
-            case 0x56:
-            case 0x57:
-            {
-                return get_binary(input_format_t::cbor, static_cast<unsigned int>(current) & 0x1Fu, result);
-            }
-
-            case 0x58: // Binary data (one-byte uint8_t for n follows)
-            {
-                std::uint8_t len{};
-                return get_number(input_format_t::cbor, len) &&
-                       get_binary(input_format_t::cbor, len, result);
-            }
-
-            case 0x59: // Binary data (two-byte uint16_t for n follow)
-            {
-                std::uint16_t len{};
-                return get_number(input_format_t::cbor, len) &&
-                       get_binary(input_format_t::cbor, len, result);
-            }
-
-            case 0x5A: // Binary data (four-byte uint32_t for n follow)
-            {
-                std::uint32_t len{};
-                return get_number(input_format_t::cbor, len) &&
-                       get_binary(input_format_t::cbor, len, result);
-            }
-
-            case 0x5B: // Binary data (eight-byte uint64_t for n follow)
-            {
-                std::uint64_t len{};
-                return get_number(input_format_t::cbor, len) &&
-                       get_binary(input_format_t::cbor, len, result);
-            }
-
-            case 0x5F: // Binary data (indefinite length)
-            {
-                while (get() != 0xFF)
-                {
-                    binary_t chunk;
-                    if (!get_cbor_binary(chunk))
-                    {
-                        return false;
-                    }
-                    result.insert(result.end(), chunk.begin(), chunk.end());
-                }
-                return true;
-            }
-
-            default:
-            {
-                auto last_token = get_token_string();
-                return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read, exception_message(input_format_t::cbor, "expected length specification (0x40-0x5B) or indefinite binary array type (0x5F); last byte: 0x" + last_token, "binary")));
-            }
-        }
-    }
-
-    /*!
-    @param[in] len  the length of the array or std::size_t(-1) for an
-                    array of indefinite size
-    @param[in] tag_handler how CBOR tags should be treated
-    @return whether array creation completed
-    */
-    bool get_cbor_array(const std::size_t len,
-                        const cbor_tag_handler_t tag_handler)
-    {
-        if (JSON_HEDLEY_UNLIKELY(!sax->start_array(len)))
-        {
-            return false;
-        }
-
-        if (len != std::size_t(-1))
-        {
-            for (std::size_t i = 0; i < len; ++i)
-            {
-                if (JSON_HEDLEY_UNLIKELY(!parse_cbor_internal(true, tag_handler)))
-                {
-                    return false;
-                }
-            }
-        }
-        else
-        {
-            while (get() != 0xFF)
-            {
-                if (JSON_HEDLEY_UNLIKELY(!parse_cbor_internal(false, tag_handler)))
-                {
-                    return false;
-                }
-            }
-        }
-
-        return sax->end_array();
-    }
-
-    /*!
-    @param[in] len  the length of the object or std::size_t(-1) for an
-                    object of indefinite size
-    @param[in] tag_handler how CBOR tags should be treated
-    @return whether object creation completed
-    */
-    bool get_cbor_object(const std::size_t len,
-                         const cbor_tag_handler_t tag_handler)
-    {
-        if (JSON_HEDLEY_UNLIKELY(!sax->start_object(len)))
-        {
-            return false;
-        }
-
-        string_t key;
-        if (len != std::size_t(-1))
-        {
-            for (std::size_t i = 0; i < len; ++i)
-            {
-                get();
-                if (JSON_HEDLEY_UNLIKELY(!get_cbor_string(key) || !sax->key(key)))
-                {
-                    return false;
-                }
-
-                if (JSON_HEDLEY_UNLIKELY(!parse_cbor_internal(true, tag_handler)))
-                {
-                    return false;
-                }
-                key.clear();
-            }
-        }
-        else
-        {
-            while (get() != 0xFF)
-            {
-                if (JSON_HEDLEY_UNLIKELY(!get_cbor_string(key) || !sax->key(key)))
-                {
-                    return false;
-                }
-
-                if (JSON_HEDLEY_UNLIKELY(!parse_cbor_internal(true, tag_handler)))
-                {
-                    return false;
-                }
-                key.clear();
-            }
-        }
-
-        return sax->end_object();
-    }
-
-    /////////////
-    // MsgPack //
-    /////////////
-
-    /*!
-    @return whether a valid MessagePack value was passed to the SAX parser
-    */
-    bool parse_msgpack_internal()
-    {
-        switch (get())
-        {
-            // EOF
-            case std::char_traits<char_type>::eof():
-                return unexpect_eof(input_format_t::msgpack, "value");
-
-            // positive fixint
-            case 0x00:
-            case 0x01:
-            case 0x02:
-            case 0x03:
-            case 0x04:
-            case 0x05:
-            case 0x06:
-            case 0x07:
-            case 0x08:
-            case 0x09:
-            case 0x0A:
-            case 0x0B:
-            case 0x0C:
-            case 0x0D:
-            case 0x0E:
-            case 0x0F:
-            case 0x10:
-            case 0x11:
-            case 0x12:
-            case 0x13:
-            case 0x14:
-            case 0x15:
-            case 0x16:
-            case 0x17:
-            case 0x18:
-            case 0x19:
-            case 0x1A:
-            case 0x1B:
-            case 0x1C:
-            case 0x1D:
-            case 0x1E:
-            case 0x1F:
-            case 0x20:
-            case 0x21:
-            case 0x22:
-            case 0x23:
-            case 0x24:
-            case 0x25:
-            case 0x26:
-            case 0x27:
-            case 0x28:
-            case 0x29:
-            case 0x2A:
-            case 0x2B:
-            case 0x2C:
-            case 0x2D:
-            case 0x2E:
-            case 0x2F:
-            case 0x30:
-            case 0x31:
-            case 0x32:
-            case 0x33:
-            case 0x34:
-            case 0x35:
-            case 0x36:
-            case 0x37:
-            case 0x38:
-            case 0x39:
-            case 0x3A:
-            case 0x3B:
-            case 0x3C:
-            case 0x3D:
-            case 0x3E:
-            case 0x3F:
-            case 0x40:
-            case 0x41:
-            case 0x42:
-            case 0x43:
-            case 0x44:
-            case 0x45:
-            case 0x46:
-            case 0x47:
-            case 0x48:
-            case 0x49:
-            case 0x4A:
-            case 0x4B:
-            case 0x4C:
-            case 0x4D:
-            case 0x4E:
-            case 0x4F:
-            case 0x50:
-            case 0x51:
-            case 0x52:
-            case 0x53:
-            case 0x54:
-            case 0x55:
-            case 0x56:
-            case 0x57:
-            case 0x58:
-            case 0x59:
-            case 0x5A:
-            case 0x5B:
-            case 0x5C:
-            case 0x5D:
-            case 0x5E:
-            case 0x5F:
-            case 0x60:
-            case 0x61:
-            case 0x62:
-            case 0x63:
-            case 0x64:
-            case 0x65:
-            case 0x66:
-            case 0x67:
-            case 0x68:
-            case 0x69:
-            case 0x6A:
-            case 0x6B:
-            case 0x6C:
-            case 0x6D:
-            case 0x6E:
-            case 0x6F:
-            case 0x70:
-            case 0x71:
-            case 0x72:
-            case 0x73:
-            case 0x74:
-            case 0x75:
-            case 0x76:
-            case 0x77:
-            case 0x78:
-            case 0x79:
-            case 0x7A:
-            case 0x7B:
-            case 0x7C:
-            case 0x7D:
-            case 0x7E:
-            case 0x7F:
-                return sax->number_unsigned(static_cast<number_unsigned_t>(current));
-
-            // fixmap
-            case 0x80:
-            case 0x81:
-            case 0x82:
-            case 0x83:
-            case 0x84:
-            case 0x85:
-            case 0x86:
-            case 0x87:
-            case 0x88:
-            case 0x89:
-            case 0x8A:
-            case 0x8B:
-            case 0x8C:
-            case 0x8D:
-            case 0x8E:
-            case 0x8F:
-                return get_msgpack_object(static_cast<std::size_t>(static_cast<unsigned int>(current) & 0x0Fu));
-
-            // fixarray
-            case 0x90:
-            case 0x91:
-            case 0x92:
-            case 0x93:
-            case 0x94:
-            case 0x95:
-            case 0x96:
-            case 0x97:
-            case 0x98:
-            case 0x99:
-            case 0x9A:
-            case 0x9B:
-            case 0x9C:
-            case 0x9D:
-            case 0x9E:
-            case 0x9F:
-                return get_msgpack_array(static_cast<std::size_t>(static_cast<unsigned int>(current) & 0x0Fu));
-
-            // fixstr
-            case 0xA0:
-            case 0xA1:
-            case 0xA2:
-            case 0xA3:
-            case 0xA4:
-            case 0xA5:
-            case 0xA6:
-            case 0xA7:
-            case 0xA8:
-            case 0xA9:
-            case 0xAA:
-            case 0xAB:
-            case 0xAC:
-            case 0xAD:
-            case 0xAE:
-            case 0xAF:
-            case 0xB0:
-            case 0xB1:
-            case 0xB2:
-            case 0xB3:
-            case 0xB4:
-            case 0xB5:
-            case 0xB6:
-            case 0xB7:
-            case 0xB8:
-            case 0xB9:
-            case 0xBA:
-            case 0xBB:
-            case 0xBC:
-            case 0xBD:
-            case 0xBE:
-            case 0xBF:
-            case 0xD9: // str 8
-            case 0xDA: // str 16
-            case 0xDB: // str 32
-            {
-                string_t s;
-                return get_msgpack_string(s) && sax->string(s);
-            }
-
-            case 0xC0: // nil
-                return sax->null();
-
-            case 0xC2: // false
-                return sax->boolean(false);
-
-            case 0xC3: // true
-                return sax->boolean(true);
-
-            case 0xC4: // bin 8
-            case 0xC5: // bin 16
-            case 0xC6: // bin 32
-            case 0xC7: // ext 8
-            case 0xC8: // ext 16
-            case 0xC9: // ext 32
-            case 0xD4: // fixext 1
-            case 0xD5: // fixext 2
-            case 0xD6: // fixext 4
-            case 0xD7: // fixext 8
-            case 0xD8: // fixext 16
-            {
-                binary_t b;
-                return get_msgpack_binary(b) && sax->binary(b);
-            }
-
-            case 0xCA: // float 32
-            {
-                float number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_float(static_cast<number_float_t>(number), "");
-            }
-
-            case 0xCB: // float 64
-            {
-                double number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_float(static_cast<number_float_t>(number), "");
-            }
-
-            case 0xCC: // uint 8
-            {
-                std::uint8_t number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_unsigned(number);
-            }
-
-            case 0xCD: // uint 16
-            {
-                std::uint16_t number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_unsigned(number);
-            }
-
-            case 0xCE: // uint 32
-            {
-                std::uint32_t number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_unsigned(number);
-            }
-
-            case 0xCF: // uint 64
-            {
-                std::uint64_t number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_unsigned(number);
-            }
-
-            case 0xD0: // int 8
-            {
-                std::int8_t number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_integer(number);
-            }
-
-            case 0xD1: // int 16
-            {
-                std::int16_t number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_integer(number);
-            }
-
-            case 0xD2: // int 32
-            {
-                std::int32_t number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_integer(number);
-            }
-
-            case 0xD3: // int 64
-            {
-                std::int64_t number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_integer(number);
-            }
-
-            case 0xDC: // array 16
-            {
-                std::uint16_t len{};
-                return get_number(input_format_t::msgpack, len) && get_msgpack_array(static_cast<std::size_t>(len));
-            }
-
-            case 0xDD: // array 32
-            {
-                std::uint32_t len{};
-                return get_number(input_format_t::msgpack, len) && get_msgpack_array(static_cast<std::size_t>(len));
-            }
-
-            case 0xDE: // map 16
-            {
-                std::uint16_t len{};
-                return get_number(input_format_t::msgpack, len) && get_msgpack_object(static_cast<std::size_t>(len));
-            }
-
-            case 0xDF: // map 32
-            {
-                std::uint32_t len{};
-                return get_number(input_format_t::msgpack, len) && get_msgpack_object(static_cast<std::size_t>(len));
-            }
-
-            // negative fixint
-            case 0xE0:
-            case 0xE1:
-            case 0xE2:
-            case 0xE3:
-            case 0xE4:
-            case 0xE5:
-            case 0xE6:
-            case 0xE7:
-            case 0xE8:
-            case 0xE9:
-            case 0xEA:
-            case 0xEB:
-            case 0xEC:
-            case 0xED:
-            case 0xEE:
-            case 0xEF:
-            case 0xF0:
-            case 0xF1:
-            case 0xF2:
-            case 0xF3:
-            case 0xF4:
-            case 0xF5:
-            case 0xF6:
-            case 0xF7:
-            case 0xF8:
-            case 0xF9:
-            case 0xFA:
-            case 0xFB:
-            case 0xFC:
-            case 0xFD:
-            case 0xFE:
-            case 0xFF:
-                return sax->number_integer(static_cast<std::int8_t>(current));
-
-            default: // anything else
-            {
-                auto last_token = get_token_string();
-                return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read, exception_message(input_format_t::msgpack, "invalid byte: 0x" + last_token, "value")));
-            }
-        }
-    }
-
-    /*!
-    @brief reads a MessagePack string
-
-    This function first reads starting bytes to determine the expected
-    string length and then copies this number of bytes into a string.
-
-    @param[out] result  created string
-
-    @return whether string creation completed
-    */
-    bool get_msgpack_string(string_t& result)
-    {
-        if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(input_format_t::msgpack, "string")))
-        {
-            return false;
-        }
-
-        switch (current)
-        {
-            // fixstr
-            case 0xA0:
-            case 0xA1:
-            case 0xA2:
-            case 0xA3:
-            case 0xA4:
-            case 0xA5:
-            case 0xA6:
-            case 0xA7:
-            case 0xA8:
-            case 0xA9:
-            case 0xAA:
-            case 0xAB:
-            case 0xAC:
-            case 0xAD:
-            case 0xAE:
-            case 0xAF:
-            case 0xB0:
-            case 0xB1:
-            case 0xB2:
-            case 0xB3:
-            case 0xB4:
-            case 0xB5:
-            case 0xB6:
-            case 0xB7:
-            case 0xB8:
-            case 0xB9:
-            case 0xBA:
-            case 0xBB:
-            case 0xBC:
-            case 0xBD:
-            case 0xBE:
-            case 0xBF:
-            {
-                return get_string(input_format_t::msgpack, static_cast<unsigned int>(current) & 0x1Fu, result);
-            }
-
-            case 0xD9: // str 8
-            {
-                std::uint8_t len{};
-                return get_number(input_format_t::msgpack, len) && get_string(input_format_t::msgpack, len, result);
-            }
-
-            case 0xDA: // str 16
-            {
-                std::uint16_t len{};
-                return get_number(input_format_t::msgpack, len) && get_string(input_format_t::msgpack, len, result);
-            }
-
-            case 0xDB: // str 32
-            {
-                std::uint32_t len{};
-                return get_number(input_format_t::msgpack, len) && get_string(input_format_t::msgpack, len, result);
-            }
-
-            default:
-            {
-                auto last_token = get_token_string();
-                return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read, exception_message(input_format_t::msgpack, "expected length specification (0xA0-0xBF, 0xD9-0xDB); last byte: 0x" + last_token, "string")));
-            }
-        }
-    }
-
-    /*!
-    @brief reads a MessagePack byte array
-
-    This function first reads starting bytes to determine the expected
-    byte array length and then copies this number of bytes into a byte array.
-
-    @param[out] result  created byte array
-
-    @return whether byte array creation completed
-    */
-    bool get_msgpack_binary(binary_t& result)
-    {
-        // helper function to set the subtype
-        auto assign_and_return_true = [&result](std::int8_t subtype)
-        {
-            result.set_subtype(static_cast<std::uint8_t>(subtype));
-            return true;
-        };
-
-        switch (current)
-        {
-            case 0xC4: // bin 8
-            {
-                std::uint8_t len{};
-                return get_number(input_format_t::msgpack, len) &&
-                       get_binary(input_format_t::msgpack, len, result);
-            }
-
-            case 0xC5: // bin 16
-            {
-                std::uint16_t len{};
-                return get_number(input_format_t::msgpack, len) &&
-                       get_binary(input_format_t::msgpack, len, result);
-            }
-
-            case 0xC6: // bin 32
-            {
-                std::uint32_t len{};
-                return get_number(input_format_t::msgpack, len) &&
-                       get_binary(input_format_t::msgpack, len, result);
-            }
-
-            case 0xC7: // ext 8
-            {
-                std::uint8_t len{};
-                std::int8_t subtype{};
-                return get_number(input_format_t::msgpack, len) &&
-                       get_number(input_format_t::msgpack, subtype) &&
-                       get_binary(input_format_t::msgpack, len, result) &&
-                       assign_and_return_true(subtype);
-            }
-
-            case 0xC8: // ext 16
-            {
-                std::uint16_t len{};
-                std::int8_t subtype{};
-                return get_number(input_format_t::msgpack, len) &&
-                       get_number(input_format_t::msgpack, subtype) &&
-                       get_binary(input_format_t::msgpack, len, result) &&
-                       assign_and_return_true(subtype);
-            }
-
-            case 0xC9: // ext 32
-            {
-                std::uint32_t len{};
-                std::int8_t subtype{};
-                return get_number(input_format_t::msgpack, len) &&
-                       get_number(input_format_t::msgpack, subtype) &&
-                       get_binary(input_format_t::msgpack, len, result) &&
-                       assign_and_return_true(subtype);
-            }
-
-            case 0xD4: // fixext 1
-            {
-                std::int8_t subtype{};
-                return get_number(input_format_t::msgpack, subtype) &&
-                       get_binary(input_format_t::msgpack, 1, result) &&
-                       assign_and_return_true(subtype);
-            }
-
-            case 0xD5: // fixext 2
-            {
-                std::int8_t subtype{};
-                return get_number(input_format_t::msgpack, subtype) &&
-                       get_binary(input_format_t::msgpack, 2, result) &&
-                       assign_and_return_true(subtype);
-            }
-
-            case 0xD6: // fixext 4
-            {
-                std::int8_t subtype{};
-                return get_number(input_format_t::msgpack, subtype) &&
-                       get_binary(input_format_t::msgpack, 4, result) &&
-                       assign_and_return_true(subtype);
-            }
-
-            case 0xD7: // fixext 8
-            {
-                std::int8_t subtype{};
-                return get_number(input_format_t::msgpack, subtype) &&
-                       get_binary(input_format_t::msgpack, 8, result) &&
-                       assign_and_return_true(subtype);
-            }
-
-            case 0xD8: // fixext 16
-            {
-                std::int8_t subtype{};
-                return get_number(input_format_t::msgpack, subtype) &&
-                       get_binary(input_format_t::msgpack, 16, result) &&
-                       assign_and_return_true(subtype);
-            }
-
-            default:           // LCOV_EXCL_LINE
-                return false;  // LCOV_EXCL_LINE
-        }
-    }
-
-    /*!
-    @param[in] len  the length of the array
-    @return whether array creation completed
-    */
-    bool get_msgpack_array(const std::size_t len)
-    {
-        if (JSON_HEDLEY_UNLIKELY(!sax->start_array(len)))
-        {
-            return false;
-        }
-
-        for (std::size_t i = 0; i < len; ++i)
-        {
-            if (JSON_HEDLEY_UNLIKELY(!parse_msgpack_internal()))
-            {
-                return false;
-            }
-        }
-
-        return sax->end_array();
-    }
-
-    /*!
-    @param[in] len  the length of the object
-    @return whether object creation completed
-    */
-    bool get_msgpack_object(const std::size_t len)
-    {
-        if (JSON_HEDLEY_UNLIKELY(!sax->start_object(len)))
-        {
-            return false;
-        }
-
-        string_t key;
-        for (std::size_t i = 0; i < len; ++i)
-        {
-            get();
-            if (JSON_HEDLEY_UNLIKELY(!get_msgpack_string(key) || !sax->key(key)))
-            {
-                return false;
-            }
-
-            if (JSON_HEDLEY_UNLIKELY(!parse_msgpack_internal()))
-            {
-                return false;
-            }
-            key.clear();
-        }
-
-        return sax->end_object();
-    }
-
-    ////////////
-    // UBJSON //
-    ////////////
-
-    /*!
-    @param[in] get_char  whether a new character should be retrieved from the
-                         input (true, default) or whether the last read
-                         character should be considered instead
-
-    @return whether a valid UBJSON value was passed to the SAX parser
-    */
-    bool parse_ubjson_internal(const bool get_char = true)
-    {
-        return get_ubjson_value(get_char ? get_ignore_noop() : current);
-    }
-
-    /*!
-    @brief reads a UBJSON string
-
-    This function is either called after reading the 'S' byte explicitly
-    indicating a string, or in case of an object key where the 'S' byte can be
-    left out.
-
-    @param[out] result   created string
-    @param[in] get_char  whether a new character should be retrieved from the
-                         input (true, default) or whether the last read
-                         character should be considered instead
-
-    @return whether string creation completed
-    */
-    bool get_ubjson_string(string_t& result, const bool get_char = true)
-    {
-        if (get_char)
-        {
-            get();  // TODO(niels): may we ignore N here?
-        }
-
-        if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(input_format_t::ubjson, "value")))
-        {
-            return false;
-        }
-
-        switch (current)
-        {
-            case 'U':
-            {
-                std::uint8_t len{};
-                return get_number(input_format_t::ubjson, len) && get_string(input_format_t::ubjson, len, result);
-            }
-
-            case 'i':
-            {
-                std::int8_t len{};
-                return get_number(input_format_t::ubjson, len) && get_string(input_format_t::ubjson, len, result);
-            }
-
-            case 'I':
-            {
-                std::int16_t len{};
-                return get_number(input_format_t::ubjson, len) && get_string(input_format_t::ubjson, len, result);
-            }
-
-            case 'l':
-            {
-                std::int32_t len{};
-                return get_number(input_format_t::ubjson, len) && get_string(input_format_t::ubjson, len, result);
-            }
-
-            case 'L':
-            {
-                std::int64_t len{};
-                return get_number(input_format_t::ubjson, len) && get_string(input_format_t::ubjson, len, result);
-            }
-
-            default:
-                auto last_token = get_token_string();
-                return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read, exception_message(input_format_t::ubjson, "expected length type specification (U, i, I, l, L); last byte: 0x" + last_token, "string")));
-        }
-    }
-
-    /*!
-    @param[out] result  determined size
-    @return whether size determination completed
-    */
-    bool get_ubjson_size_value(std::size_t& result)
-    {
-        switch (get_ignore_noop())
-        {
-            case 'U':
-            {
-                std::uint8_t number{};
-                if (JSON_HEDLEY_UNLIKELY(!get_number(input_format_t::ubjson, number)))
-                {
-                    return false;
-                }
-                result = static_cast<std::size_t>(number);
-                return true;
-            }
-
-            case 'i':
-            {
-                std::int8_t number{};
-                if (JSON_HEDLEY_UNLIKELY(!get_number(input_format_t::ubjson, number)))
-                {
-                    return false;
-                }
-                result = static_cast<std::size_t>(number);
-                return true;
-            }
-
-            case 'I':
-            {
-                std::int16_t number{};
-                if (JSON_HEDLEY_UNLIKELY(!get_number(input_format_t::ubjson, number)))
-                {
-                    return false;
-                }
-                result = static_cast<std::size_t>(number);
-                return true;
-            }
-
-            case 'l':
-            {
-                std::int32_t number{};
-                if (JSON_HEDLEY_UNLIKELY(!get_number(input_format_t::ubjson, number)))
-                {
-                    return false;
-                }
-                result = static_cast<std::size_t>(number);
-                return true;
-            }
-
-            case 'L':
-            {
-                std::int64_t number{};
-                if (JSON_HEDLEY_UNLIKELY(!get_number(input_format_t::ubjson, number)))
-                {
-                    return false;
-                }
-                result = static_cast<std::size_t>(number);
-                return true;
-            }
-
-            default:
-            {
-                auto last_token = get_token_string();
-                return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read, exception_message(input_format_t::ubjson, "expected length type specification (U, i, I, l, L) after '#'; last byte: 0x" + last_token, "size")));
-            }
-        }
-    }
-
-    /*!
-    @brief determine the type and size for a container
-
-    In the optimized UBJSON format, a type and a size can be provided to allow
-    for a more compact representation.
-
-    @param[out] result  pair of the size and the type
-
-    @return whether pair creation completed
-    */
-    bool get_ubjson_size_type(std::pair<std::size_t, char_int_type>& result)
-    {
-        result.first = string_t::npos; // size
-        result.second = 0; // type
-
-        get_ignore_noop();
-
-        if (current == '$')
-        {
-            result.second = get();  // must not ignore 'N', because 'N' maybe the type
-            if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(input_format_t::ubjson, "type")))
-            {
-                return false;
-            }
-
-            get_ignore_noop();
-            if (JSON_HEDLEY_UNLIKELY(current != '#'))
-            {
-                if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(input_format_t::ubjson, "value")))
-                {
-                    return false;
-                }
-                auto last_token = get_token_string();
-                return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read, exception_message(input_format_t::ubjson, "expected '#' after type information; last byte: 0x" + last_token, "size")));
-            }
-
-            return get_ubjson_size_value(result.first);
-        }
-
-        if (current == '#')
-        {
-            return get_ubjson_size_value(result.first);
-        }
-
-        return true;
-    }
-
-    /*!
-    @param prefix  the previously read or set type prefix
-    @return whether value creation completed
-    */
-    bool get_ubjson_value(const char_int_type prefix)
-    {
-        switch (prefix)
-        {
-            case std::char_traits<char_type>::eof():  // EOF
-                return unexpect_eof(input_format_t::ubjson, "value");
-
-            case 'T':  // true
-                return sax->boolean(true);
-            case 'F':  // false
-                return sax->boolean(false);
-
-            case 'Z':  // null
-                return sax->null();
-
-            case 'U':
-            {
-                std::uint8_t number{};
-                return get_number(input_format_t::ubjson, number) && sax->number_unsigned(number);
-            }
-
-            case 'i':
-            {
-                std::int8_t number{};
-                return get_number(input_format_t::ubjson, number) && sax->number_integer(number);
-            }
-
-            case 'I':
-            {
-                std::int16_t number{};
-                return get_number(input_format_t::ubjson, number) && sax->number_integer(number);
-            }
-
-            case 'l':
-            {
-                std::int32_t number{};
-                return get_number(input_format_t::ubjson, number) && sax->number_integer(number);
-            }
-
-            case 'L':
-            {
-                std::int64_t number{};
-                return get_number(input_format_t::ubjson, number) && sax->number_integer(number);
-            }
-
-            case 'd':
-            {
-                float number{};
-                return get_number(input_format_t::ubjson, number) && sax->number_float(static_cast<number_float_t>(number), "");
-            }
-
-            case 'D':
-            {
-                double number{};
-                return get_number(input_format_t::ubjson, number) && sax->number_float(static_cast<number_float_t>(number), "");
-            }
-
-            case 'H':
-            {
-                return get_ubjson_high_precision_number();
-            }
-
-            case 'C':  // char
-            {
-                get();
-                if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(input_format_t::ubjson, "char")))
-                {
-                    return false;
-                }
-                if (JSON_HEDLEY_UNLIKELY(current > 127))
-                {
-                    auto last_token = get_token_string();
-                    return sax->parse_error(chars_read, last_token, parse_error::create(113, chars_read, exception_message(input_format_t::ubjson, "byte after 'C' must be in range 0x00..0x7F; last byte: 0x" + last_token, "char")));
-                }
-                string_t s(1, static_cast<typename string_t::value_type>(current));
-                return sax->string(s);
-            }
-
-            case 'S':  // string
-            {
-                string_t s;
-                return get_ubjson_string(s) && sax->string(s);
-            }
-
-            case '[':  // array
-                return get_ubjson_array();
-
-            case '{':  // object
-                return get_ubjson_object();
-
-            default: // anything else
-            {
-                auto last_token = get_token_string();
-                return sax->parse_error(chars_read, last_token, parse_error::create(112, chars_read, exception_message(input_format_t::ubjson, "invalid byte: 0x" + last_token, "value")));
-            }
-        }
-    }
-
-    /*!
-    @return whether array creation completed
-    */
-    bool get_ubjson_array()
-    {
-        std::pair<std::size_t, char_int_type> size_and_type;
-        if (JSON_HEDLEY_UNLIKELY(!get_ubjson_size_type(size_and_type)))
-        {
-            return false;
-        }
-
-        if (size_and_type.first != string_t::npos)
-        {
-            if (JSON_HEDLEY_UNLIKELY(!sax->start_array(size_and_type.first)))
-            {
-                return false;
-            }
-
-            if (size_and_type.second != 0)
-            {
-                if (size_and_type.second != 'N')
-                {
-                    for (std::size_t i = 0; i < size_and_type.first; ++i)
-                    {
-                        if (JSON_HEDLEY_UNLIKELY(!get_ubjson_value(size_and_type.second)))
-                        {
-                            return false;
-                        }
-                    }
-                }
-            }
-            else
-            {
-                for (std::size_t i = 0; i < size_and_type.first; ++i)
-                {
-                    if (JSON_HEDLEY_UNLIKELY(!parse_ubjson_internal()))
-                    {
-                        return false;
-                    }
-                }
-            }
-        }
-        else
-        {
-            if (JSON_HEDLEY_UNLIKELY(!sax->start_array(std::size_t(-1))))
-            {
-                return false;
-            }
-
-            while (current != ']')
-            {
-                if (JSON_HEDLEY_UNLIKELY(!parse_ubjson_internal(false)))
-                {
-                    return false;
-                }
-                get_ignore_noop();
-            }
-        }
-
-        return sax->end_array();
-    }
-
-    /*!
-    @return whether object creation completed
-    */
-    bool get_ubjson_object()
-    {
-        std::pair<std::size_t, char_int_type> size_and_type;
-        if (JSON_HEDLEY_UNLIKELY(!get_ubjson_size_type(size_and_type)))
-        {
-            return false;
-        }
-
-        string_t key;
-        if (size_and_type.first != string_t::npos)
-        {
-            if (JSON_HEDLEY_UNLIKELY(!sax->start_object(size_and_type.first)))
-            {
-                return false;
-            }
-
-            if (size_and_type.second != 0)
-            {
-                for (std::size_t i = 0; i < size_and_type.first; ++i)
-                {
-                    if (JSON_HEDLEY_UNLIKELY(!get_ubjson_string(key) || !sax->key(key)))
-                    {
-                        return false;
-                    }
-                    if (JSON_HEDLEY_UNLIKELY(!get_ubjson_value(size_and_type.second)))
-                    {
-                        return false;
-                    }
-                    key.clear();
-                }
-            }
-            else
-            {
-                for (std::size_t i = 0; i < size_and_type.first; ++i)
-                {
-                    if (JSON_HEDLEY_UNLIKELY(!get_ubjson_string(key) || !sax->key(key)))
-                    {
-                        return false;
-                    }
-                    if (JSON_HEDLEY_UNLIKELY(!parse_ubjson_internal()))
-                    {
-                        return false;
-                    }
-                    key.clear();
-                }
-            }
-        }
-        else
-        {
-            if (JSON_HEDLEY_UNLIKELY(!sax->start_object(std::size_t(-1))))
-            {
-                return false;
-            }
-
-            while (current != '}')
-            {
-                if (JSON_HEDLEY_UNLIKELY(!get_ubjson_string(key, false) || !sax->key(key)))
-                {
-                    return false;
-                }
-                if (JSON_HEDLEY_UNLIKELY(!parse_ubjson_internal()))
-                {
-                    return false;
-                }
-                get_ignore_noop();
-                key.clear();
-            }
-        }
-
-        return sax->end_object();
-    }
-
-    // Note, no reader for UBJSON binary types is implemented because they do
-    // not exist
-
-    bool get_ubjson_high_precision_number()
-    {
-        // get size of following number string
-        std::size_t size{};
-        auto res = get_ubjson_size_value(size);
-        if (JSON_HEDLEY_UNLIKELY(!res))
-        {
-            return res;
-        }
-
-        // get number string
-        std::vector<char> number_vector;
-        for (std::size_t i = 0; i < size; ++i)
-        {
-            get();
-            if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(input_format_t::ubjson, "number")))
-            {
-                return false;
-            }
-            number_vector.push_back(static_cast<char>(current));
-        }
-
-        // parse number string
-        auto number_ia = detail::input_adapter(std::forward<decltype(number_vector)>(number_vector));
-        auto number_lexer = detail::lexer<BasicJsonType, decltype(number_ia)>(std::move(number_ia), false);
-        const auto result_number = number_lexer.scan();
-        const auto number_string = number_lexer.get_token_string();
-        const auto result_remainder = number_lexer.scan();
-
-        using token_type = typename detail::lexer_base<BasicJsonType>::token_type;
-
-        if (JSON_HEDLEY_UNLIKELY(result_remainder != token_type::end_of_input))
-        {
-            return sax->parse_error(chars_read, number_string, parse_error::create(115, chars_read, exception_message(input_format_t::ubjson, "invalid number text: " + number_lexer.get_token_string(), "high-precision number")));
-        }
-
-        switch (result_number)
-        {
-            case token_type::value_integer:
-                return sax->number_integer(number_lexer.get_number_integer());
-            case token_type::value_unsigned:
-                return sax->number_unsigned(number_lexer.get_number_unsigned());
-            case token_type::value_float:
-                return sax->number_float(number_lexer.get_number_float(), std::move(number_string));
-            default:
-                return sax->parse_error(chars_read, number_string, parse_error::create(115, chars_read, exception_message(input_format_t::ubjson, "invalid number text: " + number_lexer.get_token_string(), "high-precision number")));
-        }
-    }
-
-    ///////////////////////
-    // Utility functions //
-    ///////////////////////
-
-    /*!
-    @brief get next character from the input
-
-    This function provides the interface to the used input adapter. It does
-    not throw in case the input reached EOF, but returns a -'ve valued
-    `std::char_traits<char_type>::eof()` in that case.
-
-    @return character read from the input
-    */
-    char_int_type get()
-    {
-        ++chars_read;
-        return current = ia.get_character();
-    }
-
-    /*!
-    @return character read from the input after ignoring all 'N' entries
-    */
-    char_int_type get_ignore_noop()
-    {
-        do
-        {
-            get();
-        }
-        while (current == 'N');
-
-        return current;
-    }
-
-    /*
-    @brief read a number from the input
-
-    @tparam NumberType the type of the number
-    @param[in] format   the current format (for diagnostics)
-    @param[out] result  number of type @a NumberType
-
-    @return whether conversion completed
-
-    @note This function needs to respect the system's endianess, because
-          bytes in CBOR, MessagePack, and UBJSON are stored in network order
-          (big endian) and therefore need reordering on little endian systems.
-    */
-    template<typename NumberType, bool InputIsLittleEndian = false>
-    bool get_number(const input_format_t format, NumberType& result)
-    {
-        // step 1: read input into array with system's byte order
-        std::array<std::uint8_t, sizeof(NumberType)> vec;
-        for (std::size_t i = 0; i < sizeof(NumberType); ++i)
-        {
-            get();
-            if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(format, "number")))
-            {
-                return false;
-            }
-
-            // reverse byte order prior to conversion if necessary
-            if (is_little_endian != InputIsLittleEndian)
-            {
-                vec[sizeof(NumberType) - i - 1] = static_cast<std::uint8_t>(current);
-            }
-            else
-            {
-                vec[i] = static_cast<std::uint8_t>(current); // LCOV_EXCL_LINE
-            }
-        }
-
-        // step 2: convert array into number of type T and return
-        std::memcpy(&result, vec.data(), sizeof(NumberType));
-        return true;
-    }
-
-    /*!
-    @brief create a string by reading characters from the input
-
-    @tparam NumberType the type of the number
-    @param[in] format the current format (for diagnostics)
-    @param[in] len number of characters to read
-    @param[out] result string created by reading @a len bytes
-
-    @return whether string creation completed
-
-    @note We can not reserve @a len bytes for the result, because @a len
-          may be too large. Usually, @ref unexpect_eof() detects the end of
-          the input before we run out of string memory.
-    */
-    template<typename NumberType>
-    bool get_string(const input_format_t format,
-                    const NumberType len,
-                    string_t& result)
-    {
-        bool success = true;
-        for (NumberType i = 0; i < len; i++)
-        {
-            get();
-            if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(format, "string")))
-            {
-                success = false;
-                break;
-            }
-            result.push_back(static_cast<typename string_t::value_type>(current));
-        };
-        return success;
-    }
-
-    /*!
-    @brief create a byte array by reading bytes from the input
-
-    @tparam NumberType the type of the number
-    @param[in] format the current format (for diagnostics)
-    @param[in] len number of bytes to read
-    @param[out] result byte array created by reading @a len bytes
-
-    @return whether byte array creation completed
-
-    @note We can not reserve @a len bytes for the result, because @a len
-          may be too large. Usually, @ref unexpect_eof() detects the end of
-          the input before we run out of memory.
-    */
-    template<typename NumberType>
-    bool get_binary(const input_format_t format,
-                    const NumberType len,
-                    binary_t& result)
-    {
-        bool success = true;
-        for (NumberType i = 0; i < len; i++)
-        {
-            get();
-            if (JSON_HEDLEY_UNLIKELY(!unexpect_eof(format, "binary")))
-            {
-                success = false;
-                break;
-            }
-            result.push_back(static_cast<std::uint8_t>(current));
-        }
-        return success;
-    }
-
-    /*!
-    @param[in] format   the current format (for diagnostics)
-    @param[in] context  further context information (for diagnostics)
-    @return whether the last read character is not EOF
-    */
-    JSON_HEDLEY_NON_NULL(3)
-    bool unexpect_eof(const input_format_t format, const char* context) const
-    {
-        if (JSON_HEDLEY_UNLIKELY(current == std::char_traits<char_type>::eof()))
-        {
-            return sax->parse_error(chars_read, "<end of file>",
-                                    parse_error::create(110, chars_read, exception_message(format, "unexpected end of input", context)));
-        }
-        return true;
-    }
-
-    /*!
-    @return a string representation of the last read byte
-    */
-    std::string get_token_string() const
-    {
-        std::array<char, 3> cr{{}};
-        (std::snprintf)(cr.data(), cr.size(), "%.2hhX", static_cast<unsigned char>(current));
-        return std::string{cr.data()};
-    }
-
-    /*!
-    @param[in] format   the current format
-    @param[in] detail   a detailed error message
-    @param[in] context  further context information
-    @return a message string to use in the parse_error exceptions
-    */
-    std::string exception_message(const input_format_t format,
-                                  const std::string& detail,
-                                  const std::string& context) const
-    {
-        std::string error_msg = "syntax error while parsing ";
-
-        switch (format)
-        {
-            case input_format_t::cbor:
-                error_msg += "CBOR";
-                break;
-
-            case input_format_t::msgpack:
-                error_msg += "MessagePack";
-                break;
-
-            case input_format_t::ubjson:
-                error_msg += "UBJSON";
-                break;
-
-            case input_format_t::bson:
-                error_msg += "BSON";
-                break;
-
-            default:            // LCOV_EXCL_LINE
-                JSON_ASSERT(false);  // LCOV_EXCL_LINE
-        }
-
-        return error_msg + " " + context + ": " + detail;
-    }
-
-  private:
-    /// input adapter
-    InputAdapterType ia;
-
-    /// the current character
-    char_int_type current = std::char_traits<char_type>::eof();
-
-    /// the number of characters read
-    std::size_t chars_read = 0;
-
-    /// whether we can assume little endianess
-    const bool is_little_endian = little_endianess();
-
-    /// the SAX parser
-    json_sax_t* sax = nullptr;
-};
-}  // namespace detail
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/input/input_adapters.hpp>
-
-// #include <nlohmann/detail/input/lexer.hpp>
-
-// #include <nlohmann/detail/input/parser.hpp>
-
-
-#include <cmath> // isfinite
-#include <cstdint> // uint8_t
-#include <functional> // function
-#include <string> // string
-#include <utility> // move
-#include <vector> // vector
-
-// #include <nlohmann/detail/exceptions.hpp>
-
-// #include <nlohmann/detail/input/input_adapters.hpp>
-
-// #include <nlohmann/detail/input/json_sax.hpp>
-
-// #include <nlohmann/detail/input/lexer.hpp>
-
-// #include <nlohmann/detail/macro_scope.hpp>
-
-// #include <nlohmann/detail/meta/is_sax.hpp>
-
-// #include <nlohmann/detail/value_t.hpp>
-
-
-namespace nlohmann
-{
-namespace detail
-{
-////////////
-// parser //
-////////////
-
-enum class parse_event_t : uint8_t
-{
-    /// the parser read `{` and started to process a JSON object
-    object_start,
-    /// the parser read `}` and finished processing a JSON object
-    object_end,
-    /// the parser read `[` and started to process a JSON array
-    array_start,
-    /// the parser read `]` and finished processing a JSON array
-    array_end,
-    /// the parser read a key of a value in an object
-    key,
-    /// the parser finished reading a JSON value
-    value
-};
-
-template<typename BasicJsonType>
-using parser_callback_t =
-    std::function<bool(int depth, parse_event_t event, BasicJsonType& parsed)>;
-
-/*!
-@brief syntax analysis
-
-This class implements a recursive descent parser.
-*/
-template<typename BasicJsonType, typename InputAdapterType>
-class parser
-{
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
-    using lexer_t = lexer<BasicJsonType, InputAdapterType>;
-    using token_type = typename lexer_t::token_type;
-
-  public:
-    /// a parser reading from an input adapter
-    explicit parser(InputAdapterType&& adapter,
-                    const parser_callback_t<BasicJsonType> cb = nullptr,
-                    const bool allow_exceptions_ = true,
-                    const bool skip_comments = false)
-        : callback(cb)
-        , m_lexer(std::move(adapter), skip_comments)
-        , allow_exceptions(allow_exceptions_)
-    {
-        // read first token
-        get_token();
-    }
-
-    /*!
-    @brief public parser interface
-
-    @param[in] strict      whether to expect the last token to be EOF
-    @param[in,out] result  parsed JSON value
-
-    @throw parse_error.101 in case of an unexpected token
-    @throw parse_error.102 if to_unicode fails or surrogate error
-    @throw parse_error.103 if to_unicode fails
-    */
-    void parse(const bool strict, BasicJsonType& result)
-    {
-        if (callback)
-        {
-            json_sax_dom_callback_parser<BasicJsonType> sdp(result, callback, allow_exceptions);
-            sax_parse_internal(&sdp);
-            result.assert_invariant();
-
-            // in strict mode, input must be completely read
-            if (strict && (get_token() != token_type::end_of_input))
-            {
-                sdp.parse_error(m_lexer.get_position(),
-                                m_lexer.get_token_string(),
-                                parse_error::create(101, m_lexer.get_position(),
-                                                    exception_message(token_type::end_of_input, "value")));
-            }
-
-            // in case of an error, return discarded value
-            if (sdp.is_errored())
-            {
-                result = value_t::discarded;
-                return;
-            }
-
-            // set top-level value to null if it was discarded by the callback
-            // function
-            if (result.is_discarded())
-            {
-                result = nullptr;
-            }
-        }
-        else
-        {
-            json_sax_dom_parser<BasicJsonType> sdp(result, allow_exceptions);
-            sax_parse_internal(&sdp);
-            result.assert_invariant();
-
-            // in strict mode, input must be completely read
-            if (strict && (get_token() != token_type::end_of_input))
-            {
-                sdp.parse_error(m_lexer.get_position(),
-                                m_lexer.get_token_string(),
-                                parse_error::create(101, m_lexer.get_position(),
-                                                    exception_message(token_type::end_of_input, "value")));
-            }
-
-            // in case of an error, return discarded value
-            if (sdp.is_errored())
-            {
-                result = value_t::discarded;
-                return;
-            }
-        }
-    }
-
-    /*!
-    @brief public accept interface
-
-    @param[in] strict  whether to expect the last token to be EOF
-    @return whether the input is a proper JSON text
-    */
-    bool accept(const bool strict = true)
-    {
-        json_sax_acceptor<BasicJsonType> sax_acceptor;
-        return sax_parse(&sax_acceptor, strict);
-    }
-
-    template<typename SAX>
-    JSON_HEDLEY_NON_NULL(2)
-    bool sax_parse(SAX* sax, const bool strict = true)
-    {
-        (void)detail::is_sax_static_asserts<SAX, BasicJsonType> {};
-        const bool result = sax_parse_internal(sax);
-
-        // strict mode: next byte must be EOF
-        if (result && strict && (get_token() != token_type::end_of_input))
-        {
-            return sax->parse_error(m_lexer.get_position(),
-                                    m_lexer.get_token_string(),
-                                    parse_error::create(101, m_lexer.get_position(),
-                                            exception_message(token_type::end_of_input, "value")));
-        }
-
-        return result;
-    }
-
-  private:
-    template<typename SAX>
-    JSON_HEDLEY_NON_NULL(2)
-    bool sax_parse_internal(SAX* sax)
-    {
-        // stack to remember the hierarchy of structured values we are parsing
-        // true = array; false = object
-        std::vector<bool> states;
-        // value to avoid a goto (see comment where set to true)
-        bool skip_to_state_evaluation = false;
-
-        while (true)
-        {
-            if (!skip_to_state_evaluation)
-            {
-                // invariant: get_token() was called before each iteration
-                switch (last_token)
-                {
-                    case token_type::begin_object:
-                    {
-                        if (JSON_HEDLEY_UNLIKELY(!sax->start_object(std::size_t(-1))))
-                        {
-                            return false;
-                        }
-
-                        // closing } -> we are done
-                        if (get_token() == token_type::end_object)
-                        {
-                            if (JSON_HEDLEY_UNLIKELY(!sax->end_object()))
-                            {
-                                return false;
-                            }
-                            break;
-                        }
-
-                        // parse key
-                        if (JSON_HEDLEY_UNLIKELY(last_token != token_type::value_string))
-                        {
-                            return sax->parse_error(m_lexer.get_position(),
-                                                    m_lexer.get_token_string(),
-                                                    parse_error::create(101, m_lexer.get_position(),
-                                                            exception_message(token_type::value_string, "object key")));
-                        }
-                        if (JSON_HEDLEY_UNLIKELY(!sax->key(m_lexer.get_string())))
-                        {
-                            return false;
-                        }
-
-                        // parse separator (:)
-                        if (JSON_HEDLEY_UNLIKELY(get_token() != token_type::name_separator))
-                        {
-                            return sax->parse_error(m_lexer.get_position(),
-                                                    m_lexer.get_token_string(),
-                                                    parse_error::create(101, m_lexer.get_position(),
-                                                            exception_message(token_type::name_separator, "object separator")));
-                        }
-
-                        // remember we are now inside an object
-                        states.push_back(false);
-
-                        // parse values
-                        get_token();
-                        continue;
-                    }
-
-                    case token_type::begin_array:
-                    {
-                        if (JSON_HEDLEY_UNLIKELY(!sax->start_array(std::size_t(-1))))
-                        {
-                            return false;
-                        }
-
-                        // closing ] -> we are done
-                        if (get_token() == token_type::end_array)
-                        {
-                            if (JSON_HEDLEY_UNLIKELY(!sax->end_array()))
-                            {
-                                return false;
-                            }
-                            break;
-                        }
-
-                        // remember we are now inside an array
-                        states.push_back(true);
-
-                        // parse values (no need to call get_token)
-                        continue;
-                    }
-
-                    case token_type::value_float:
-                    {
-                        const auto res = m_lexer.get_number_float();
-
-                        if (JSON_HEDLEY_UNLIKELY(!std::isfinite(res)))
-                        {
-                            return sax->parse_error(m_lexer.get_position(),
-                                                    m_lexer.get_token_string(),
-                                                    out_of_range::create(406, "number overflow parsing '" + m_lexer.get_token_string() + "'"));
-                        }
-
-                        if (JSON_HEDLEY_UNLIKELY(!sax->number_float(res, m_lexer.get_string())))
-                        {
-                            return false;
-                        }
-
-                        break;
-                    }
-
-                    case token_type::literal_false:
-                    {
-                        if (JSON_HEDLEY_UNLIKELY(!sax->boolean(false)))
-                        {
-                            return false;
-                        }
-                        break;
-                    }
-
-                    case token_type::literal_null:
-                    {
-                        if (JSON_HEDLEY_UNLIKELY(!sax->null()))
-                        {
-                            return false;
-                        }
-                        break;
-                    }
-
-                    case token_type::literal_true:
-                    {
-                        if (JSON_HEDLEY_UNLIKELY(!sax->boolean(true)))
-                        {
-                            return false;
-                        }
-                        break;
-                    }
-
-                    case token_type::value_integer:
-                    {
-                        if (JSON_HEDLEY_UNLIKELY(!sax->number_integer(m_lexer.get_number_integer())))
-                        {
-                            return false;
-                        }
-                        break;
-                    }
-
-                    case token_type::value_string:
-                    {
-                        if (JSON_HEDLEY_UNLIKELY(!sax->string(m_lexer.get_string())))
-                        {
-                            return false;
-                        }
-                        break;
-                    }
-
-                    case token_type::value_unsigned:
-                    {
-                        if (JSON_HEDLEY_UNLIKELY(!sax->number_unsigned(m_lexer.get_number_unsigned())))
-                        {
-                            return false;
-                        }
-                        break;
-                    }
-
-                    case token_type::parse_error:
-                    {
-                        // using "uninitialized" to avoid "expected" message
-                        return sax->parse_error(m_lexer.get_position(),
-                                                m_lexer.get_token_string(),
-                                                parse_error::create(101, m_lexer.get_position(),
-                                                        exception_message(token_type::uninitialized, "value")));
-                    }
-
-                    default: // the last token was unexpected
-                    {
-                        return sax->parse_error(m_lexer.get_position(),
-                                                m_lexer.get_token_string(),
-                                                parse_error::create(101, m_lexer.get_position(),
-                                                        exception_message(token_type::literal_or_value, "value")));
-                    }
-                }
-            }
-            else
-            {
-                skip_to_state_evaluation = false;
-            }
-
-            // we reached this line after we successfully parsed a value
-            if (states.empty())
-            {
-                // empty stack: we reached the end of the hierarchy: done
-                return true;
-            }
-
-            if (states.back())  // array
-            {
-                // comma -> next value
-                if (get_token() == token_type::value_separator)
-                {
-                    // parse a new value
-                    get_token();
-                    continue;
-                }
-
-                // closing ]
-                if (JSON_HEDLEY_LIKELY(last_token == token_type::end_array))
-                {
-                    if (JSON_HEDLEY_UNLIKELY(!sax->end_array()))
-                    {
-                        return false;
-                    }
-
-                    // We are done with this array. Before we can parse a
-                    // new value, we need to evaluate the new state first.
-                    // By setting skip_to_state_evaluation to false, we
-                    // are effectively jumping to the beginning of this if.
-                    JSON_ASSERT(!states.empty());
-                    states.pop_back();
-                    skip_to_state_evaluation = true;
-                    continue;
-                }
-
-                return sax->parse_error(m_lexer.get_position(),
-                                        m_lexer.get_token_string(),
-                                        parse_error::create(101, m_lexer.get_position(),
-                                                exception_message(token_type::end_array, "array")));
-            }
-            else  // object
-            {
-                // comma -> next value
-                if (get_token() == token_type::value_separator)
-                {
-                    // parse key
-                    if (JSON_HEDLEY_UNLIKELY(get_token() != token_type::value_string))
-                    {
-                        return sax->parse_error(m_lexer.get_position(),
-                                                m_lexer.get_token_string(),
-                                                parse_error::create(101, m_lexer.get_position(),
-                                                        exception_message(token_type::value_string, "object key")));
-                    }
-
-                    if (JSON_HEDLEY_UNLIKELY(!sax->key(m_lexer.get_string())))
-                    {
-                        return false;
-                    }
-
-                    // parse separator (:)
-                    if (JSON_HEDLEY_UNLIKELY(get_token() != token_type::name_separator))
-                    {
-                        return sax->parse_error(m_lexer.get_position(),
-                                                m_lexer.get_token_string(),
-                                                parse_error::create(101, m_lexer.get_position(),
-                                                        exception_message(token_type::name_separator, "object separator")));
-                    }
-
-                    // parse values
-                    get_token();
-                    continue;
-                }
-
-                // closing }
-                if (JSON_HEDLEY_LIKELY(last_token == token_type::end_object))
-                {
-                    if (JSON_HEDLEY_UNLIKELY(!sax->end_object()))
-                    {
-                        return false;
-                    }
-
-                    // We are done with this object. Before we can parse a
-                    // new value, we need to evaluate the new state first.
-                    // By setting skip_to_state_evaluation to false, we
-                    // are effectively jumping to the beginning of this if.
-                    JSON_ASSERT(!states.empty());
-                    states.pop_back();
-                    skip_to_state_evaluation = true;
-                    continue;
-                }
-
-                return sax->parse_error(m_lexer.get_position(),
-                                        m_lexer.get_token_string(),
-                                        parse_error::create(101, m_lexer.get_position(),
-                                                exception_message(token_type::end_object, "object")));
-            }
-        }
-    }
-
-    /// get next token from lexer
-    token_type get_token()
-    {
-        return last_token = m_lexer.scan();
-    }
-
-    std::string exception_message(const token_type expected, const std::string& context)
-    {
-        std::string error_msg = "syntax error ";
-
-        if (!context.empty())
-        {
-            error_msg += "while parsing " + context + " ";
-        }
-
-        error_msg += "- ";
-
-        if (last_token == token_type::parse_error)
-        {
-            error_msg += std::string(m_lexer.get_error_message()) + "; last read: '" +
-                         m_lexer.get_token_string() + "'";
-        }
-        else
-        {
-            error_msg += "unexpected " + std::string(lexer_t::token_type_name(last_token));
-        }
-
-        if (expected != token_type::uninitialized)
-        {
-            error_msg += "; expected " + std::string(lexer_t::token_type_name(expected));
-        }
-
-        return error_msg;
-    }
-
-  private:
-    /// callback function
-    const parser_callback_t<BasicJsonType> callback = nullptr;
-    /// the type of the last read token
-    token_type last_token = token_type::uninitialized;
-    /// the lexer
-    lexer_t m_lexer;
-    /// whether to throw exceptions in case of errors
-    const bool allow_exceptions = true;
-};
-}  // namespace detail
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/iterators/internal_iterator.hpp>
-
-
-// #include <nlohmann/detail/iterators/primitive_iterator.hpp>
-
-
-#include <cstddef> // ptrdiff_t
-#include <limits>  // numeric_limits
-
-namespace nlohmann
-{
-namespace detail
-{
-/*
-@brief an iterator for primitive JSON types
-
-This class models an iterator for primitive JSON types (boolean, number,
-string). It's only purpose is to allow the iterator/const_iterator classes
-to "iterate" over primitive values. Internally, the iterator is modeled by
-a `difference_type` variable. Value begin_value (`0`) models the begin,
-end_value (`1`) models past the end.
-*/
-class primitive_iterator_t
-{
-  private:
-    using difference_type = std::ptrdiff_t;
-    static constexpr difference_type begin_value = 0;
-    static constexpr difference_type end_value = begin_value + 1;
-
-    /// iterator as signed integer type
-    difference_type m_it = (std::numeric_limits<std::ptrdiff_t>::min)();
-
-  public:
-    constexpr difference_type get_value() const noexcept
-    {
-        return m_it;
-    }
-
-    /// set iterator to a defined beginning
-    void set_begin() noexcept
-    {
-        m_it = begin_value;
-    }
-
-    /// set iterator to a defined past the end
-    void set_end() noexcept
-    {
-        m_it = end_value;
-    }
-
-    /// return whether the iterator can be dereferenced
-    constexpr bool is_begin() const noexcept
-    {
-        return m_it == begin_value;
-    }
-
-    /// return whether the iterator is at end
-    constexpr bool is_end() const noexcept
-    {
-        return m_it == end_value;
-    }
-
-    friend constexpr bool operator==(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
-    {
-        return lhs.m_it == rhs.m_it;
-    }
-
-    friend constexpr bool operator<(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
-    {
-        return lhs.m_it < rhs.m_it;
-    }
-
-    primitive_iterator_t operator+(difference_type n) noexcept
-    {
-        auto result = *this;
-        result += n;
-        return result;
-    }
-
-    friend constexpr difference_type operator-(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
-    {
-        return lhs.m_it - rhs.m_it;
-    }
-
-    primitive_iterator_t& operator++() noexcept
-    {
-        ++m_it;
-        return *this;
-    }
-
-    primitive_iterator_t const operator++(int) noexcept
-    {
-        auto result = *this;
-        ++m_it;
-        return result;
-    }
-
-    primitive_iterator_t& operator--() noexcept
-    {
-        --m_it;
-        return *this;
-    }
-
-    primitive_iterator_t const operator--(int) noexcept
-    {
-        auto result = *this;
-        --m_it;
-        return result;
-    }
-
-    primitive_iterator_t& operator+=(difference_type n) noexcept
-    {
-        m_it += n;
-        return *this;
-    }
-
-    primitive_iterator_t& operator-=(difference_type n) noexcept
-    {
-        m_it -= n;
-        return *this;
-    }
-};
-}  // namespace detail
-}  // namespace nlohmann
-
-
-namespace nlohmann
-{
-namespace detail
-{
-/*!
-@brief an iterator value
-
-@note This structure could easily be a union, but MSVC currently does not allow
-unions members with complex constructors, see https://github.com/nlohmann/json/pull/105.
-*/
-template<typename BasicJsonType> struct internal_iterator
-{
-    /// iterator for JSON objects
-    typename BasicJsonType::object_t::iterator object_iterator {};
-    /// iterator for JSON arrays
-    typename BasicJsonType::array_t::iterator array_iterator {};
-    /// generic iterator for all other types
-    primitive_iterator_t primitive_iterator {};
-};
-}  // namespace detail
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/iterators/iter_impl.hpp>
-
-
-#include <iterator> // iterator, random_access_iterator_tag, bidirectional_iterator_tag, advance, next
-#include <type_traits> // conditional, is_const, remove_const
-
-// #include <nlohmann/detail/exceptions.hpp>
-
-// #include <nlohmann/detail/iterators/internal_iterator.hpp>
-
-// #include <nlohmann/detail/iterators/primitive_iterator.hpp>
-
-// #include <nlohmann/detail/macro_scope.hpp>
-
-// #include <nlohmann/detail/meta/cpp_future.hpp>
-
-// #include <nlohmann/detail/meta/type_traits.hpp>
-
-// #include <nlohmann/detail/value_t.hpp>
-
-
-namespace nlohmann
-{
-namespace detail
-{
-// forward declare, to be able to friend it later on
-template<typename IteratorType> class iteration_proxy;
-template<typename IteratorType> class iteration_proxy_value;
-
-/*!
-@brief a template for a bidirectional iterator for the @ref basic_json class
-This class implements a both iterators (iterator and const_iterator) for the
-@ref basic_json class.
-@note An iterator is called *initialized* when a pointer to a JSON value has
-      been set (e.g., by a constructor or a copy assignment). If the iterator is
-      default-constructed, it is *uninitialized* and most methods are undefined.
-      **The library uses assertions to detect calls on uninitialized iterators.**
-@requirement The class satisfies the following concept requirements:
--
-[BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator):
-  The iterator that can be moved can be moved in both directions (i.e.
-  incremented and decremented).
-@since version 1.0.0, simplified in version 2.0.9, change to bidirectional
-       iterators in version 3.0.0 (see https://github.com/nlohmann/json/issues/593)
-*/
-template<typename BasicJsonType>
-class iter_impl
-{
-    /// allow basic_json to access private members
-    friend iter_impl<typename std::conditional<std::is_const<BasicJsonType>::value, typename std::remove_const<BasicJsonType>::type, const BasicJsonType>::type>;
-    friend BasicJsonType;
-    friend iteration_proxy<iter_impl>;
-    friend iteration_proxy_value<iter_impl>;
-
-    using object_t = typename BasicJsonType::object_t;
-    using array_t = typename BasicJsonType::array_t;
-    // make sure BasicJsonType is basic_json or const basic_json
-    static_assert(is_basic_json<typename std::remove_const<BasicJsonType>::type>::value,
-                  "iter_impl only accepts (const) basic_json");
-
-  public:
-
-    /// The std::iterator class template (used as a base class to provide typedefs) is deprecated in C++17.
-    /// The C++ Standard has never required user-defined iterators to derive from std::iterator.
-    /// A user-defined iterator should provide publicly accessible typedefs named
-    /// iterator_category, value_type, difference_type, pointer, and reference.
-    /// Note that value_type is required to be non-const, even for constant iterators.
-    using iterator_category = std::bidirectional_iterator_tag;
-
-    /// the type of the values when the iterator is dereferenced
-    using value_type = typename BasicJsonType::value_type;
-    /// a type to represent differences between iterators
-    using difference_type = typename BasicJsonType::difference_type;
-    /// defines a pointer to the type iterated over (value_type)
-    using pointer = typename std::conditional<std::is_const<BasicJsonType>::value,
-          typename BasicJsonType::const_pointer,
-          typename BasicJsonType::pointer>::type;
-    /// defines a reference to the type iterated over (value_type)
-    using reference =
-        typename std::conditional<std::is_const<BasicJsonType>::value,
-        typename BasicJsonType::const_reference,
-        typename BasicJsonType::reference>::type;
-
-    /// default constructor
-    iter_impl() = default;
-
-    /*!
-    @brief constructor for a given JSON instance
-    @param[in] object  pointer to a JSON object for this iterator
-    @pre object != nullptr
-    @post The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    explicit iter_impl(pointer object) noexcept : m_object(object)
-    {
-        JSON_ASSERT(m_object != nullptr);
-
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-            {
-                m_it.object_iterator = typename object_t::iterator();
-                break;
-            }
-
-            case value_t::array:
-            {
-                m_it.array_iterator = typename array_t::iterator();
-                break;
-            }
-
-            default:
-            {
-                m_it.primitive_iterator = primitive_iterator_t();
-                break;
-            }
-        }
-    }
-
-    /*!
-    @note The conventional copy constructor and copy assignment are implicitly
-          defined. Combined with the following converting constructor and
-          assignment, they support: (1) copy from iterator to iterator, (2)
-          copy from const iterator to const iterator, and (3) conversion from
-          iterator to const iterator. However conversion from const iterator
-          to iterator is not defined.
-    */
-
-    /*!
-    @brief const copy constructor
-    @param[in] other const iterator to copy from
-    @note This copy constructor had to be defined explicitly to circumvent a bug
-          occurring on msvc v19.0 compiler (VS 2015) debug build. For more
-          information refer to: https://github.com/nlohmann/json/issues/1608
-    */
-    iter_impl(const iter_impl<const BasicJsonType>& other) noexcept
-        : m_object(other.m_object), m_it(other.m_it)
-    {}
-
-    /*!
-    @brief converting assignment
-    @param[in] other const iterator to copy from
-    @return const/non-const iterator
-    @note It is not checked whether @a other is initialized.
-    */
-    iter_impl& operator=(const iter_impl<const BasicJsonType>& other) noexcept
-    {
-        m_object = other.m_object;
-        m_it = other.m_it;
-        return *this;
-    }
-
-    /*!
-    @brief converting constructor
-    @param[in] other  non-const iterator to copy from
-    @note It is not checked whether @a other is initialized.
-    */
-    iter_impl(const iter_impl<typename std::remove_const<BasicJsonType>::type>& other) noexcept
-        : m_object(other.m_object), m_it(other.m_it)
-    {}
-
-    /*!
-    @brief converting assignment
-    @param[in] other  non-const iterator to copy from
-    @return const/non-const iterator
-    @note It is not checked whether @a other is initialized.
-    */
-    iter_impl& operator=(const iter_impl<typename std::remove_const<BasicJsonType>::type>& other) noexcept
-    {
-        m_object = other.m_object;
-        m_it = other.m_it;
-        return *this;
-    }
-
-  private:
-    /*!
-    @brief set the iterator to the first value
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    void set_begin() noexcept
-    {
-        JSON_ASSERT(m_object != nullptr);
-
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-            {
-                m_it.object_iterator = m_object->m_value.object->begin();
-                break;
-            }
-
-            case value_t::array:
-            {
-                m_it.array_iterator = m_object->m_value.array->begin();
-                break;
-            }
-
-            case value_t::null:
-            {
-                // set to end so begin()==end() is true: null is empty
-                m_it.primitive_iterator.set_end();
-                break;
-            }
-
-            default:
-            {
-                m_it.primitive_iterator.set_begin();
-                break;
-            }
-        }
-    }
-
-    /*!
-    @brief set the iterator past the last value
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    void set_end() noexcept
-    {
-        JSON_ASSERT(m_object != nullptr);
-
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-            {
-                m_it.object_iterator = m_object->m_value.object->end();
-                break;
-            }
-
-            case value_t::array:
-            {
-                m_it.array_iterator = m_object->m_value.array->end();
-                break;
-            }
-
-            default:
-            {
-                m_it.primitive_iterator.set_end();
-                break;
-            }
-        }
-    }
-
-  public:
-    /*!
-    @brief return a reference to the value pointed to by the iterator
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    reference operator*() const
-    {
-        JSON_ASSERT(m_object != nullptr);
-
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-            {
-                JSON_ASSERT(m_it.object_iterator != m_object->m_value.object->end());
-                return m_it.object_iterator->second;
-            }
-
-            case value_t::array:
-            {
-                JSON_ASSERT(m_it.array_iterator != m_object->m_value.array->end());
-                return *m_it.array_iterator;
-            }
-
-            case value_t::null:
-                JSON_THROW(invalid_iterator::create(214, "cannot get value"));
-
-            default:
-            {
-                if (JSON_HEDLEY_LIKELY(m_it.primitive_iterator.is_begin()))
-                {
-                    return *m_object;
-                }
-
-                JSON_THROW(invalid_iterator::create(214, "cannot get value"));
-            }
-        }
-    }
-
-    /*!
-    @brief dereference the iterator
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    pointer operator->() const
-    {
-        JSON_ASSERT(m_object != nullptr);
-
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-            {
-                JSON_ASSERT(m_it.object_iterator != m_object->m_value.object->end());
-                return &(m_it.object_iterator->second);
-            }
-
-            case value_t::array:
-            {
-                JSON_ASSERT(m_it.array_iterator != m_object->m_value.array->end());
-                return &*m_it.array_iterator;
-            }
-
-            default:
-            {
-                if (JSON_HEDLEY_LIKELY(m_it.primitive_iterator.is_begin()))
-                {
-                    return m_object;
-                }
-
-                JSON_THROW(invalid_iterator::create(214, "cannot get value"));
-            }
-        }
-    }
-
-    /*!
-    @brief post-increment (it++)
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    iter_impl const operator++(int)
-    {
-        auto result = *this;
-        ++(*this);
-        return result;
-    }
-
-    /*!
-    @brief pre-increment (++it)
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    iter_impl& operator++()
-    {
-        JSON_ASSERT(m_object != nullptr);
-
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-            {
-                std::advance(m_it.object_iterator, 1);
-                break;
-            }
-
-            case value_t::array:
-            {
-                std::advance(m_it.array_iterator, 1);
-                break;
-            }
-
-            default:
-            {
-                ++m_it.primitive_iterator;
-                break;
-            }
-        }
-
-        return *this;
-    }
-
-    /*!
-    @brief post-decrement (it--)
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    iter_impl const operator--(int)
-    {
-        auto result = *this;
-        --(*this);
-        return result;
-    }
-
-    /*!
-    @brief pre-decrement (--it)
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    iter_impl& operator--()
-    {
-        JSON_ASSERT(m_object != nullptr);
-
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-            {
-                std::advance(m_it.object_iterator, -1);
-                break;
-            }
-
-            case value_t::array:
-            {
-                std::advance(m_it.array_iterator, -1);
-                break;
-            }
-
-            default:
-            {
-                --m_it.primitive_iterator;
-                break;
-            }
-        }
-
-        return *this;
-    }
-
-    /*!
-    @brief  comparison: equal
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    bool operator==(const iter_impl& other) const
-    {
-        // if objects are not the same, the comparison is undefined
-        if (JSON_HEDLEY_UNLIKELY(m_object != other.m_object))
-        {
-            JSON_THROW(invalid_iterator::create(212, "cannot compare iterators of different containers"));
-        }
-
-        JSON_ASSERT(m_object != nullptr);
-
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-                return (m_it.object_iterator == other.m_it.object_iterator);
-
-            case value_t::array:
-                return (m_it.array_iterator == other.m_it.array_iterator);
-
-            default:
-                return (m_it.primitive_iterator == other.m_it.primitive_iterator);
-        }
-    }
-
-    /*!
-    @brief  comparison: not equal
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    bool operator!=(const iter_impl& other) const
-    {
-        return !operator==(other);
-    }
-
-    /*!
-    @brief  comparison: smaller
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    bool operator<(const iter_impl& other) const
-    {
-        // if objects are not the same, the comparison is undefined
-        if (JSON_HEDLEY_UNLIKELY(m_object != other.m_object))
-        {
-            JSON_THROW(invalid_iterator::create(212, "cannot compare iterators of different containers"));
-        }
-
-        JSON_ASSERT(m_object != nullptr);
-
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-                JSON_THROW(invalid_iterator::create(213, "cannot compare order of object iterators"));
-
-            case value_t::array:
-                return (m_it.array_iterator < other.m_it.array_iterator);
-
-            default:
-                return (m_it.primitive_iterator < other.m_it.primitive_iterator);
-        }
-    }
-
-    /*!
-    @brief  comparison: less than or equal
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    bool operator<=(const iter_impl& other) const
-    {
-        return !other.operator < (*this);
-    }
-
-    /*!
-    @brief  comparison: greater than
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    bool operator>(const iter_impl& other) const
-    {
-        return !operator<=(other);
-    }
-
-    /*!
-    @brief  comparison: greater than or equal
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    bool operator>=(const iter_impl& other) const
-    {
-        return !operator<(other);
-    }
-
-    /*!
-    @brief  add to iterator
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    iter_impl& operator+=(difference_type i)
-    {
-        JSON_ASSERT(m_object != nullptr);
-
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-                JSON_THROW(invalid_iterator::create(209, "cannot use offsets with object iterators"));
-
-            case value_t::array:
-            {
-                std::advance(m_it.array_iterator, i);
-                break;
-            }
-
-            default:
-            {
-                m_it.primitive_iterator += i;
-                break;
-            }
-        }
-
-        return *this;
-    }
-
-    /*!
-    @brief  subtract from iterator
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    iter_impl& operator-=(difference_type i)
-    {
-        return operator+=(-i);
-    }
-
-    /*!
-    @brief  add to iterator
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    iter_impl operator+(difference_type i) const
-    {
-        auto result = *this;
-        result += i;
-        return result;
-    }
-
-    /*!
-    @brief  addition of distance and iterator
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    friend iter_impl operator+(difference_type i, const iter_impl& it)
-    {
-        auto result = it;
-        result += i;
-        return result;
-    }
-
-    /*!
-    @brief  subtract from iterator
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    iter_impl operator-(difference_type i) const
-    {
-        auto result = *this;
-        result -= i;
-        return result;
-    }
-
-    /*!
-    @brief  return difference
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    difference_type operator-(const iter_impl& other) const
-    {
-        JSON_ASSERT(m_object != nullptr);
-
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-                JSON_THROW(invalid_iterator::create(209, "cannot use offsets with object iterators"));
-
-            case value_t::array:
-                return m_it.array_iterator - other.m_it.array_iterator;
-
-            default:
-                return m_it.primitive_iterator - other.m_it.primitive_iterator;
-        }
-    }
-
-    /*!
-    @brief  access to successor
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    reference operator[](difference_type n) const
-    {
-        JSON_ASSERT(m_object != nullptr);
-
-        switch (m_object->m_type)
-        {
-            case value_t::object:
-                JSON_THROW(invalid_iterator::create(208, "cannot use operator[] for object iterators"));
-
-            case value_t::array:
-                return *std::next(m_it.array_iterator, n);
-
-            case value_t::null:
-                JSON_THROW(invalid_iterator::create(214, "cannot get value"));
-
-            default:
-            {
-                if (JSON_HEDLEY_LIKELY(m_it.primitive_iterator.get_value() == -n))
-                {
-                    return *m_object;
-                }
-
-                JSON_THROW(invalid_iterator::create(214, "cannot get value"));
-            }
-        }
-    }
-
-    /*!
-    @brief  return the key of an object iterator
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    const typename object_t::key_type& key() const
-    {
-        JSON_ASSERT(m_object != nullptr);
-
-        if (JSON_HEDLEY_LIKELY(m_object->is_object()))
-        {
-            return m_it.object_iterator->first;
-        }
-
-        JSON_THROW(invalid_iterator::create(207, "cannot use key() for non-object iterators"));
-    }
-
-    /*!
-    @brief  return the value of an iterator
-    @pre The iterator is initialized; i.e. `m_object != nullptr`.
-    */
-    reference value() const
-    {
-        return operator*();
-    }
-
-  private:
-    /// associated JSON instance
-    pointer m_object = nullptr;
-    /// the actual iterator of the associated instance
-    internal_iterator<typename std::remove_const<BasicJsonType>::type> m_it {};
-};
-} // namespace detail
-} // namespace nlohmann
-
-// #include <nlohmann/detail/iterators/iteration_proxy.hpp>
-
-// #include <nlohmann/detail/iterators/json_reverse_iterator.hpp>
-
-
-#include <cstddef> // ptrdiff_t
-#include <iterator> // reverse_iterator
-#include <utility> // declval
-
-namespace nlohmann
-{
-namespace detail
-{
-//////////////////////
-// reverse_iterator //
-//////////////////////
-
-/*!
-@brief a template for a reverse iterator class
-
-@tparam Base the base iterator type to reverse. Valid types are @ref
-iterator (to create @ref reverse_iterator) and @ref const_iterator (to
-create @ref const_reverse_iterator).
-
-@requirement The class satisfies the following concept requirements:
--
-[BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator):
-  The iterator that can be moved can be moved in both directions (i.e.
-  incremented and decremented).
-- [OutputIterator](https://en.cppreference.com/w/cpp/named_req/OutputIterator):
-  It is possible to write to the pointed-to element (only if @a Base is
-  @ref iterator).
-
-@since version 1.0.0
-*/
-template<typename Base>
-class json_reverse_iterator : public std::reverse_iterator<Base>
-{
-  public:
-    using difference_type = std::ptrdiff_t;
-    /// shortcut to the reverse iterator adapter
-    using base_iterator = std::reverse_iterator<Base>;
-    /// the reference type for the pointed-to element
-    using reference = typename Base::reference;
-
-    /// create reverse iterator from iterator
-    explicit json_reverse_iterator(const typename base_iterator::iterator_type& it) noexcept
-        : base_iterator(it) {}
-
-    /// create reverse iterator from base class
-    explicit json_reverse_iterator(const base_iterator& it) noexcept : base_iterator(it) {}
-
-    /// post-increment (it++)
-    json_reverse_iterator const operator++(int)
-    {
-        return static_cast<json_reverse_iterator>(base_iterator::operator++(1));
-    }
-
-    /// pre-increment (++it)
-    json_reverse_iterator& operator++()
-    {
-        return static_cast<json_reverse_iterator&>(base_iterator::operator++());
-    }
-
-    /// post-decrement (it--)
-    json_reverse_iterator const operator--(int)
-    {
-        return static_cast<json_reverse_iterator>(base_iterator::operator--(1));
-    }
-
-    /// pre-decrement (--it)
-    json_reverse_iterator& operator--()
-    {
-        return static_cast<json_reverse_iterator&>(base_iterator::operator--());
-    }
-
-    /// add to iterator
-    json_reverse_iterator& operator+=(difference_type i)
-    {
-        return static_cast<json_reverse_iterator&>(base_iterator::operator+=(i));
-    }
-
-    /// add to iterator
-    json_reverse_iterator operator+(difference_type i) const
-    {
-        return static_cast<json_reverse_iterator>(base_iterator::operator+(i));
-    }
-
-    /// subtract from iterator
-    json_reverse_iterator operator-(difference_type i) const
-    {
-        return static_cast<json_reverse_iterator>(base_iterator::operator-(i));
-    }
-
-    /// return difference
-    difference_type operator-(const json_reverse_iterator& other) const
-    {
-        return base_iterator(*this) - base_iterator(other);
-    }
-
-    /// access to successor
-    reference operator[](difference_type n) const
-    {
-        return *(this->operator+(n));
-    }
-
-    /// return the key of an object iterator
-    auto key() const -> decltype(std::declval<Base>().key())
-    {
-        auto it = --this->base();
-        return it.key();
-    }
-
-    /// return the value of an iterator
-    reference value() const
-    {
-        auto it = --this->base();
-        return it.operator * ();
-    }
-};
-}  // namespace detail
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/iterators/primitive_iterator.hpp>
-
-// #include <nlohmann/detail/json_pointer.hpp>
-
-
-#include <algorithm> // all_of
-#include <cctype> // isdigit
-#include <limits> // max
-#include <numeric> // accumulate
-#include <string> // string
-#include <utility> // move
-#include <vector> // vector
-
-// #include <nlohmann/detail/exceptions.hpp>
-
-// #include <nlohmann/detail/macro_scope.hpp>
-
-// #include <nlohmann/detail/value_t.hpp>
-
-
-namespace nlohmann
-{
-template<typename BasicJsonType>
-class json_pointer
-{
-    // allow basic_json to access private members
-    NLOHMANN_BASIC_JSON_TPL_DECLARATION
-    friend class basic_json;
-
-  public:
-    /*!
-    @brief create JSON pointer
-
-    Create a JSON pointer according to the syntax described in
-    [Section 3 of RFC6901](https://tools.ietf.org/html/rfc6901#section-3).
-
-    @param[in] s  string representing the JSON pointer; if omitted, the empty
-                  string is assumed which references the whole JSON value
-
-    @throw parse_error.107 if the given JSON pointer @a s is nonempty and does
-                           not begin with a slash (`/`); see example below
-
-    @throw parse_error.108 if a tilde (`~`) in the given JSON pointer @a s is
-    not followed by `0` (representing `~`) or `1` (representing `/`); see
-    example below
-
-    @liveexample{The example shows the construction several valid JSON pointers
-    as well as the exceptional behavior.,json_pointer}
-
-    @since version 2.0.0
-    */
-    explicit json_pointer(const std::string& s = "")
-        : reference_tokens(split(s))
-    {}
-
-    /*!
-    @brief return a string representation of the JSON pointer
-
-    @invariant For each JSON pointer `ptr`, it holds:
-    @code {.cpp}
-    ptr == json_pointer(ptr.to_string());
-    @endcode
-
-    @return a string representation of the JSON pointer
-
-    @liveexample{The example shows the result of `to_string`.,json_pointer__to_string}
-
-    @since version 2.0.0
-    */
-    std::string to_string() const
-    {
-        return std::accumulate(reference_tokens.begin(), reference_tokens.end(),
-                               std::string{},
-                               [](const std::string & a, const std::string & b)
-        {
-            return a + "/" + escape(b);
-        });
-    }
-
-    /// @copydoc to_string()
-    operator std::string() const
-    {
-        return to_string();
-    }
-
-    /*!
-    @brief append another JSON pointer at the end of this JSON pointer
-
-    @param[in] ptr  JSON pointer to append
-    @return JSON pointer with @a ptr appended
-
-    @liveexample{The example shows the usage of `operator/=`.,json_pointer__operator_add}
-
-    @complexity Linear in the length of @a ptr.
-
-    @sa @ref operator/=(std::string) to append a reference token
-    @sa @ref operator/=(std::size_t) to append an array index
-    @sa @ref operator/(const json_pointer&, const json_pointer&) for a binary operator
-
-    @since version 3.6.0
-    */
-    json_pointer& operator/=(const json_pointer& ptr)
-    {
-        reference_tokens.insert(reference_tokens.end(),
-                                ptr.reference_tokens.begin(),
-                                ptr.reference_tokens.end());
-        return *this;
-    }
-
-    /*!
-    @brief append an unescaped reference token at the end of this JSON pointer
-
-    @param[in] token  reference token to append
-    @return JSON pointer with @a token appended without escaping @a token
-
-    @liveexample{The example shows the usage of `operator/=`.,json_pointer__operator_add}
-
-    @complexity Amortized constant.
-
-    @sa @ref operator/=(const json_pointer&) to append a JSON pointer
-    @sa @ref operator/=(std::size_t) to append an array index
-    @sa @ref operator/(const json_pointer&, std::size_t) for a binary operator
-
-    @since version 3.6.0
-    */
-    json_pointer& operator/=(std::string token)
-    {
-        push_back(std::move(token));
-        return *this;
-    }
-
-    /*!
-    @brief append an array index at the end of this JSON pointer
-
-    @param[in] array_idx  array index to append
-    @return JSON pointer with @a array_idx appended
-
-    @liveexample{The example shows the usage of `operator/=`.,json_pointer__operator_add}
-
-    @complexity Amortized constant.
-
-    @sa @ref operator/=(const json_pointer&) to append a JSON pointer
-    @sa @ref operator/=(std::string) to append a reference token
-    @sa @ref operator/(const json_pointer&, std::string) for a binary operator
-
-    @since version 3.6.0
-    */
-    json_pointer& operator/=(std::size_t array_idx)
-    {
-        return *this /= std::to_string(array_idx);
-    }
-
-    /*!
-    @brief create a new JSON pointer by appending the right JSON pointer at the end of the left JSON pointer
-
-    @param[in] lhs  JSON pointer
-    @param[in] rhs  JSON pointer
-    @return a new JSON pointer with @a rhs appended to @a lhs
-
-    @liveexample{The example shows the usage of `operator/`.,json_pointer__operator_add_binary}
-
-    @complexity Linear in the length of @a lhs and @a rhs.
-
-    @sa @ref operator/=(const json_pointer&) to append a JSON pointer
-
-    @since version 3.6.0
-    */
-    friend json_pointer operator/(const json_pointer& lhs,
-                                  const json_pointer& rhs)
-    {
-        return json_pointer(lhs) /= rhs;
-    }
-
-    /*!
-    @brief create a new JSON pointer by appending the unescaped token at the end of the JSON pointer
-
-    @param[in] ptr  JSON pointer
-    @param[in] token  reference token
-    @return a new JSON pointer with unescaped @a token appended to @a ptr
-
-    @liveexample{The example shows the usage of `operator/`.,json_pointer__operator_add_binary}
-
-    @complexity Linear in the length of @a ptr.
-
-    @sa @ref operator/=(std::string) to append a reference token
-
-    @since version 3.6.0
-    */
-    friend json_pointer operator/(const json_pointer& ptr, std::string token)
-    {
-        return json_pointer(ptr) /= std::move(token);
-    }
-
-    /*!
-    @brief create a new JSON pointer by appending the array-index-token at the end of the JSON pointer
-
-    @param[in] ptr  JSON pointer
-    @param[in] array_idx  array index
-    @return a new JSON pointer with @a array_idx appended to @a ptr
-
-    @liveexample{The example shows the usage of `operator/`.,json_pointer__operator_add_binary}
-
-    @complexity Linear in the length of @a ptr.
-
-    @sa @ref operator/=(std::size_t) to append an array index
-
-    @since version 3.6.0
-    */
-    friend json_pointer operator/(const json_pointer& ptr, std::size_t array_idx)
-    {
-        return json_pointer(ptr) /= array_idx;
-    }
-
-    /*!
-    @brief returns the parent of this JSON pointer
-
-    @return parent of this JSON pointer; in case this JSON pointer is the root,
-            the root itself is returned
-
-    @complexity Linear in the length of the JSON pointer.
-
-    @liveexample{The example shows the result of `parent_pointer` for different
-    JSON Pointers.,json_pointer__parent_pointer}
-
-    @since version 3.6.0
-    */
-    json_pointer parent_pointer() const
-    {
-        if (empty())
-        {
-            return *this;
-        }
-
-        json_pointer res = *this;
-        res.pop_back();
-        return res;
-    }
-
-    /*!
-    @brief remove last reference token
-
-    @pre not `empty()`
-
-    @liveexample{The example shows the usage of `pop_back`.,json_pointer__pop_back}
-
-    @complexity Constant.
-
-    @throw out_of_range.405 if JSON pointer has no parent
-
-    @since version 3.6.0
-    */
-    void pop_back()
-    {
-        if (JSON_HEDLEY_UNLIKELY(empty()))
-        {
-            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent"));
-        }
-
-        reference_tokens.pop_back();
-    }
-
-    /*!
-    @brief return last reference token
-
-    @pre not `empty()`
-    @return last reference token
-
-    @liveexample{The example shows the usage of `back`.,json_pointer__back}
-
-    @complexity Constant.
-
-    @throw out_of_range.405 if JSON pointer has no parent
-
-    @since version 3.6.0
-    */
-    const std::string& back() const
-    {
-        if (JSON_HEDLEY_UNLIKELY(empty()))
-        {
-            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent"));
-        }
-
-        return reference_tokens.back();
-    }
-
-    /*!
-    @brief append an unescaped token at the end of the reference pointer
-
-    @param[in] token  token to add
-
-    @complexity Amortized constant.
-
-    @liveexample{The example shows the result of `push_back` for different
-    JSON Pointers.,json_pointer__push_back}
-
-    @since version 3.6.0
-    */
-    void push_back(const std::string& token)
-    {
-        reference_tokens.push_back(token);
-    }
-
-    /// @copydoc push_back(const std::string&)
-    void push_back(std::string&& token)
-    {
-        reference_tokens.push_back(std::move(token));
-    }
-
-    /*!
-    @brief return whether pointer points to the root document
-
-    @return true iff the JSON pointer points to the root document
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this function never throws exceptions.
-
-    @liveexample{The example shows the result of `empty` for different JSON
-    Pointers.,json_pointer__empty}
-
-    @since version 3.6.0
-    */
-    bool empty() const noexcept
-    {
-        return reference_tokens.empty();
-    }
-
-  private:
-    /*!
-    @param[in] s  reference token to be converted into an array index
-
-    @return integer representation of @a s
-
-    @throw parse_error.106  if an array index begins with '0'
-    @throw parse_error.109  if an array index begins not with a digit
-    @throw out_of_range.404 if string @a s could not be converted to an integer
-    @throw out_of_range.410 if an array index exceeds size_type
-    */
-    static typename BasicJsonType::size_type array_index(const std::string& s)
-    {
-        using size_type = typename BasicJsonType::size_type;
-
-        // error condition (cf. RFC 6901, Sect. 4)
-        if (JSON_HEDLEY_UNLIKELY(s.size() > 1 && s[0] == '0'))
-        {
-            JSON_THROW(detail::parse_error::create(106, 0,
-                                                   "array index '" + s +
-                                                   "' must not begin with '0'"));
-        }
-
-        // error condition (cf. RFC 6901, Sect. 4)
-        if (JSON_HEDLEY_UNLIKELY(s.size() > 1 && !(s[0] >= '1' && s[0] <= '9')))
-        {
-            JSON_THROW(detail::parse_error::create(109, 0, "array index '" + s + "' is not a number"));
-        }
-
-        std::size_t processed_chars = 0;
-        unsigned long long res = 0;
-        JSON_TRY
-        {
-            res = std::stoull(s, &processed_chars);
-        }
-        JSON_CATCH(std::out_of_range&)
-        {
-            JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + s + "'"));
-        }
-
-        // check if the string was completely read
-        if (JSON_HEDLEY_UNLIKELY(processed_chars != s.size()))
-        {
-            JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + s + "'"));
-        }
-
-        // only triggered on special platforms (like 32bit), see also
-        // https://github.com/nlohmann/json/pull/2203
-        if (res >= static_cast<unsigned long long>((std::numeric_limits<size_type>::max)()))
-        {
-            JSON_THROW(detail::out_of_range::create(410, "array index " + s + " exceeds size_type")); // LCOV_EXCL_LINE
-        }
-
-        return static_cast<size_type>(res);
-    }
-
-    json_pointer top() const
-    {
-        if (JSON_HEDLEY_UNLIKELY(empty()))
-        {
-            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent"));
-        }
-
-        json_pointer result = *this;
-        result.reference_tokens = {reference_tokens[0]};
-        return result;
-    }
-
-    /*!
-    @brief create and return a reference to the pointed to value
-
-    @complexity Linear in the number of reference tokens.
-
-    @throw parse_error.109 if array index is not a number
-    @throw type_error.313 if value cannot be unflattened
-    */
-    BasicJsonType& get_and_create(BasicJsonType& j) const
-    {
-        auto result = &j;
-
-        // in case no reference tokens exist, return a reference to the JSON value
-        // j which will be overwritten by a primitive value
-        for (const auto& reference_token : reference_tokens)
-        {
-            switch (result->type())
-            {
-                case detail::value_t::null:
-                {
-                    if (reference_token == "0")
-                    {
-                        // start a new array if reference token is 0
-                        result = &result->operator[](0);
-                    }
-                    else
-                    {
-                        // start a new object otherwise
-                        result = &result->operator[](reference_token);
-                    }
-                    break;
-                }
-
-                case detail::value_t::object:
-                {
-                    // create an entry in the object
-                    result = &result->operator[](reference_token);
-                    break;
-                }
-
-                case detail::value_t::array:
-                {
-                    // create an entry in the array
-                    result = &result->operator[](array_index(reference_token));
-                    break;
-                }
-
-                /*
-                The following code is only reached if there exists a reference
-                token _and_ the current value is primitive. In this case, we have
-                an error situation, because primitive values may only occur as
-                single value; that is, with an empty list of reference tokens.
-                */
-                default:
-                    JSON_THROW(detail::type_error::create(313, "invalid value to unflatten"));
-            }
-        }
-
-        return *result;
-    }
-
-    /*!
-    @brief return a reference to the pointed to value
-
-    @note This version does not throw if a value is not present, but tries to
-          create nested values instead. For instance, calling this function
-          with pointer `"/this/that"` on a null value is equivalent to calling
-          `operator[]("this").operator[]("that")` on that value, effectively
-          changing the null value to an object.
-
-    @param[in] ptr  a JSON value
-
-    @return reference to the JSON value pointed to by the JSON pointer
-
-    @complexity Linear in the length of the JSON pointer.
-
-    @throw parse_error.106   if an array index begins with '0'
-    @throw parse_error.109   if an array index was not a number
-    @throw out_of_range.404  if the JSON pointer can not be resolved
-    */
-    BasicJsonType& get_unchecked(BasicJsonType* ptr) const
-    {
-        for (const auto& reference_token : reference_tokens)
-        {
-            // convert null values to arrays or objects before continuing
-            if (ptr->is_null())
-            {
-                // check if reference token is a number
-                const bool nums =
-                    std::all_of(reference_token.begin(), reference_token.end(),
-                                [](const unsigned char x)
-                {
-                    return std::isdigit(x);
-                });
-
-                // change value to array for numbers or "-" or to object otherwise
-                *ptr = (nums || reference_token == "-")
-                       ? detail::value_t::array
-                       : detail::value_t::object;
-            }
-
-            switch (ptr->type())
-            {
-                case detail::value_t::object:
-                {
-                    // use unchecked object access
-                    ptr = &ptr->operator[](reference_token);
-                    break;
-                }
-
-                case detail::value_t::array:
-                {
-                    if (reference_token == "-")
-                    {
-                        // explicitly treat "-" as index beyond the end
-                        ptr = &ptr->operator[](ptr->m_value.array->size());
-                    }
-                    else
-                    {
-                        // convert array index to number; unchecked access
-                        ptr = &ptr->operator[](array_index(reference_token));
-                    }
-                    break;
-                }
-
-                default:
-                    JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + reference_token + "'"));
-            }
-        }
-
-        return *ptr;
-    }
-
-    /*!
-    @throw parse_error.106   if an array index begins with '0'
-    @throw parse_error.109   if an array index was not a number
-    @throw out_of_range.402  if the array index '-' is used
-    @throw out_of_range.404  if the JSON pointer can not be resolved
-    */
-    BasicJsonType& get_checked(BasicJsonType* ptr) const
-    {
-        for (const auto& reference_token : reference_tokens)
-        {
-            switch (ptr->type())
-            {
-                case detail::value_t::object:
-                {
-                    // note: at performs range check
-                    ptr = &ptr->at(reference_token);
-                    break;
-                }
-
-                case detail::value_t::array:
-                {
-                    if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
-                    {
-                        // "-" always fails the range check
-                        JSON_THROW(detail::out_of_range::create(402,
-                                                                "array index '-' (" + std::to_string(ptr->m_value.array->size()) +
-                                                                ") is out of range"));
-                    }
-
-                    // note: at performs range check
-                    ptr = &ptr->at(array_index(reference_token));
-                    break;
-                }
-
-                default:
-                    JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + reference_token + "'"));
-            }
-        }
-
-        return *ptr;
-    }
-
-    /*!
-    @brief return a const reference to the pointed to value
-
-    @param[in] ptr  a JSON value
-
-    @return const reference to the JSON value pointed to by the JSON
-    pointer
-
-    @throw parse_error.106   if an array index begins with '0'
-    @throw parse_error.109   if an array index was not a number
-    @throw out_of_range.402  if the array index '-' is used
-    @throw out_of_range.404  if the JSON pointer can not be resolved
-    */
-    const BasicJsonType& get_unchecked(const BasicJsonType* ptr) const
-    {
-        for (const auto& reference_token : reference_tokens)
-        {
-            switch (ptr->type())
-            {
-                case detail::value_t::object:
-                {
-                    // use unchecked object access
-                    ptr = &ptr->operator[](reference_token);
-                    break;
-                }
-
-                case detail::value_t::array:
-                {
-                    if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
-                    {
-                        // "-" cannot be used for const access
-                        JSON_THROW(detail::out_of_range::create(402,
-                                                                "array index '-' (" + std::to_string(ptr->m_value.array->size()) +
-                                                                ") is out of range"));
-                    }
-
-                    // use unchecked array access
-                    ptr = &ptr->operator[](array_index(reference_token));
-                    break;
-                }
-
-                default:
-                    JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + reference_token + "'"));
-            }
-        }
-
-        return *ptr;
-    }
-
-    /*!
-    @throw parse_error.106   if an array index begins with '0'
-    @throw parse_error.109   if an array index was not a number
-    @throw out_of_range.402  if the array index '-' is used
-    @throw out_of_range.404  if the JSON pointer can not be resolved
-    */
-    const BasicJsonType& get_checked(const BasicJsonType* ptr) const
-    {
-        for (const auto& reference_token : reference_tokens)
-        {
-            switch (ptr->type())
-            {
-                case detail::value_t::object:
-                {
-                    // note: at performs range check
-                    ptr = &ptr->at(reference_token);
-                    break;
-                }
-
-                case detail::value_t::array:
-                {
-                    if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
-                    {
-                        // "-" always fails the range check
-                        JSON_THROW(detail::out_of_range::create(402,
-                                                                "array index '-' (" + std::to_string(ptr->m_value.array->size()) +
-                                                                ") is out of range"));
-                    }
-
-                    // note: at performs range check
-                    ptr = &ptr->at(array_index(reference_token));
-                    break;
-                }
-
-                default:
-                    JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + reference_token + "'"));
-            }
-        }
-
-        return *ptr;
-    }
-
-    /*!
-    @throw parse_error.106   if an array index begins with '0'
-    @throw parse_error.109   if an array index was not a number
-    */
-    bool contains(const BasicJsonType* ptr) const
-    {
-        for (const auto& reference_token : reference_tokens)
-        {
-            switch (ptr->type())
-            {
-                case detail::value_t::object:
-                {
-                    if (!ptr->contains(reference_token))
-                    {
-                        // we did not find the key in the object
-                        return false;
-                    }
-
-                    ptr = &ptr->operator[](reference_token);
-                    break;
-                }
-
-                case detail::value_t::array:
-                {
-                    if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
-                    {
-                        // "-" always fails the range check
-                        return false;
-                    }
-                    if (JSON_HEDLEY_UNLIKELY(reference_token.size() == 1 && !("0" <= reference_token && reference_token <= "9")))
-                    {
-                        // invalid char
-                        return false;
-                    }
-                    if (JSON_HEDLEY_UNLIKELY(reference_token.size() > 1))
-                    {
-                        if (JSON_HEDLEY_UNLIKELY(!('1' <= reference_token[0] && reference_token[0] <= '9')))
-                        {
-                            // first char should be between '1' and '9'
-                            return false;
-                        }
-                        for (std::size_t i = 1; i < reference_token.size(); i++)
-                        {
-                            if (JSON_HEDLEY_UNLIKELY(!('0' <= reference_token[i] && reference_token[i] <= '9')))
-                            {
-                                // other char should be between '0' and '9'
-                                return false;
-                            }
-                        }
-                    }
-
-                    const auto idx = array_index(reference_token);
-                    if (idx >= ptr->size())
-                    {
-                        // index out of range
-                        return false;
-                    }
-
-                    ptr = &ptr->operator[](idx);
-                    break;
-                }
-
-                default:
-                {
-                    // we do not expect primitive values if there is still a
-                    // reference token to process
-                    return false;
-                }
-            }
-        }
-
-        // no reference token left means we found a primitive value
-        return true;
-    }
-
-    /*!
-    @brief split the string input to reference tokens
-
-    @note This function is only called by the json_pointer constructor.
-          All exceptions below are documented there.
-
-    @throw parse_error.107  if the pointer is not empty or begins with '/'
-    @throw parse_error.108  if character '~' is not followed by '0' or '1'
-    */
-    static std::vector<std::string> split(const std::string& reference_string)
-    {
-        std::vector<std::string> result;
-
-        // special case: empty reference string -> no reference tokens
-        if (reference_string.empty())
-        {
-            return result;
-        }
-
-        // check if nonempty reference string begins with slash
-        if (JSON_HEDLEY_UNLIKELY(reference_string[0] != '/'))
-        {
-            JSON_THROW(detail::parse_error::create(107, 1,
-                                                   "JSON pointer must be empty or begin with '/' - was: '" +
-                                                   reference_string + "'"));
-        }
-
-        // extract the reference tokens:
-        // - slash: position of the last read slash (or end of string)
-        // - start: position after the previous slash
-        for (
-            // search for the first slash after the first character
-            std::size_t slash = reference_string.find_first_of('/', 1),
-            // set the beginning of the first reference token
-            start = 1;
-            // we can stop if start == 0 (if slash == std::string::npos)
-            start != 0;
-            // set the beginning of the next reference token
-            // (will eventually be 0 if slash == std::string::npos)
-            start = (slash == std::string::npos) ? 0 : slash + 1,
-            // find next slash
-            slash = reference_string.find_first_of('/', start))
-        {
-            // use the text between the beginning of the reference token
-            // (start) and the last slash (slash).
-            auto reference_token = reference_string.substr(start, slash - start);
-
-            // check reference tokens are properly escaped
-            for (std::size_t pos = reference_token.find_first_of('~');
-                    pos != std::string::npos;
-                    pos = reference_token.find_first_of('~', pos + 1))
-            {
-                JSON_ASSERT(reference_token[pos] == '~');
-
-                // ~ must be followed by 0 or 1
-                if (JSON_HEDLEY_UNLIKELY(pos == reference_token.size() - 1 ||
-                                         (reference_token[pos + 1] != '0' &&
-                                          reference_token[pos + 1] != '1')))
-                {
-                    JSON_THROW(detail::parse_error::create(108, 0, "escape character '~' must be followed with '0' or '1'"));
-                }
-            }
-
-            // finally, store the reference token
-            unescape(reference_token);
-            result.push_back(reference_token);
-        }
-
-        return result;
-    }
-
-    /*!
-    @brief replace all occurrences of a substring by another string
-
-    @param[in,out] s  the string to manipulate; changed so that all
-                   occurrences of @a f are replaced with @a t
-    @param[in]     f  the substring to replace with @a t
-    @param[in]     t  the string to replace @a f
-
-    @pre The search string @a f must not be empty. **This precondition is
-    enforced with an assertion.**
-
-    @since version 2.0.0
-    */
-    static void replace_substring(std::string& s, const std::string& f,
-                                  const std::string& t)
-    {
-        JSON_ASSERT(!f.empty());
-        for (auto pos = s.find(f);                // find first occurrence of f
-                pos != std::string::npos;         // make sure f was found
-                s.replace(pos, f.size(), t),      // replace with t, and
-                pos = s.find(f, pos + t.size()))  // find next occurrence of f
-        {}
-    }
-
-    /// escape "~" to "~0" and "/" to "~1"
-    static std::string escape(std::string s)
-    {
-        replace_substring(s, "~", "~0");
-        replace_substring(s, "/", "~1");
-        return s;
-    }
-
-    /// unescape "~1" to tilde and "~0" to slash (order is important!)
-    static void unescape(std::string& s)
-    {
-        replace_substring(s, "~1", "/");
-        replace_substring(s, "~0", "~");
-    }
-
-    /*!
-    @param[in] reference_string  the reference string to the current value
-    @param[in] value             the value to consider
-    @param[in,out] result        the result object to insert values to
-
-    @note Empty objects or arrays are flattened to `null`.
-    */
-    static void flatten(const std::string& reference_string,
-                        const BasicJsonType& value,
-                        BasicJsonType& result)
-    {
-        switch (value.type())
-        {
-            case detail::value_t::array:
-            {
-                if (value.m_value.array->empty())
-                {
-                    // flatten empty array as null
-                    result[reference_string] = nullptr;
-                }
-                else
-                {
-                    // iterate array and use index as reference string
-                    for (std::size_t i = 0; i < value.m_value.array->size(); ++i)
-                    {
-                        flatten(reference_string + "/" + std::to_string(i),
-                                value.m_value.array->operator[](i), result);
-                    }
-                }
-                break;
-            }
-
-            case detail::value_t::object:
-            {
-                if (value.m_value.object->empty())
-                {
-                    // flatten empty object as null
-                    result[reference_string] = nullptr;
-                }
-                else
-                {
-                    // iterate object and use keys as reference string
-                    for (const auto& element : *value.m_value.object)
-                    {
-                        flatten(reference_string + "/" + escape(element.first), element.second, result);
-                    }
-                }
-                break;
-            }
-
-            default:
-            {
-                // add primitive value with its reference string
-                result[reference_string] = value;
-                break;
-            }
-        }
-    }
-
-    /*!
-    @param[in] value  flattened JSON
-
-    @return unflattened JSON
-
-    @throw parse_error.109 if array index is not a number
-    @throw type_error.314  if value is not an object
-    @throw type_error.315  if object values are not primitive
-    @throw type_error.313  if value cannot be unflattened
-    */
-    static BasicJsonType
-    unflatten(const BasicJsonType& value)
-    {
-        if (JSON_HEDLEY_UNLIKELY(!value.is_object()))
-        {
-            JSON_THROW(detail::type_error::create(314, "only objects can be unflattened"));
-        }
-
-        BasicJsonType result;
-
-        // iterate the JSON object values
-        for (const auto& element : *value.m_value.object)
-        {
-            if (JSON_HEDLEY_UNLIKELY(!element.second.is_primitive()))
-            {
-                JSON_THROW(detail::type_error::create(315, "values in object must be primitive"));
-            }
-
-            // assign value to reference pointed to by JSON pointer; Note that if
-            // the JSON pointer is "" (i.e., points to the whole value), function
-            // get_and_create returns a reference to result itself. An assignment
-            // will then create a primitive value.
-            json_pointer(element.first).get_and_create(result) = element.second;
-        }
-
-        return result;
-    }
-
-    /*!
-    @brief compares two JSON pointers for equality
-
-    @param[in] lhs  JSON pointer to compare
-    @param[in] rhs  JSON pointer to compare
-    @return whether @a lhs is equal to @a rhs
-
-    @complexity Linear in the length of the JSON pointer
-
-    @exceptionsafety No-throw guarantee: this function never throws exceptions.
-    */
-    friend bool operator==(json_pointer const& lhs,
-                           json_pointer const& rhs) noexcept
-    {
-        return lhs.reference_tokens == rhs.reference_tokens;
-    }
-
-    /*!
-    @brief compares two JSON pointers for inequality
-
-    @param[in] lhs  JSON pointer to compare
-    @param[in] rhs  JSON pointer to compare
-    @return whether @a lhs is not equal @a rhs
-
-    @complexity Linear in the length of the JSON pointer
-
-    @exceptionsafety No-throw guarantee: this function never throws exceptions.
-    */
-    friend bool operator!=(json_pointer const& lhs,
-                           json_pointer const& rhs) noexcept
-    {
-        return !(lhs == rhs);
-    }
-
-    /// the reference tokens
-    std::vector<std::string> reference_tokens;
-};
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/json_ref.hpp>
-
-
-#include <initializer_list>
-#include <utility>
-
-// #include <nlohmann/detail/meta/type_traits.hpp>
-
-
-namespace nlohmann
-{
-namespace detail
-{
-template<typename BasicJsonType>
-class json_ref
-{
-  public:
-    using value_type = BasicJsonType;
-
-    json_ref(value_type&& value)
-        : owned_value(std::move(value))
-        , value_ref(&owned_value)
-        , is_rvalue(true)
-    {}
-
-    json_ref(const value_type& value)
-        : value_ref(const_cast<value_type*>(&value))
-        , is_rvalue(false)
-    {}
-
-    json_ref(std::initializer_list<json_ref> init)
-        : owned_value(init)
-        , value_ref(&owned_value)
-        , is_rvalue(true)
-    {}
-
-    template <
-        class... Args,
-        enable_if_t<std::is_constructible<value_type, Args...>::value, int> = 0 >
-    json_ref(Args && ... args)
-        : owned_value(std::forward<Args>(args)...)
-        , value_ref(&owned_value)
-        , is_rvalue(true)
-    {}
-
-    // class should be movable only
-    json_ref(json_ref&&) = default;
-    json_ref(const json_ref&) = delete;
-    json_ref& operator=(const json_ref&) = delete;
-    json_ref& operator=(json_ref&&) = delete;
-    ~json_ref() = default;
-
-    value_type moved_or_copied() const
-    {
-        if (is_rvalue)
-        {
-            return std::move(*value_ref);
-        }
-        return *value_ref;
-    }
-
-    value_type const& operator*() const
-    {
-        return *static_cast<value_type const*>(value_ref);
-    }
-
-    value_type const* operator->() const
-    {
-        return static_cast<value_type const*>(value_ref);
-    }
-
-  private:
-    mutable value_type owned_value = nullptr;
-    value_type* value_ref = nullptr;
-    const bool is_rvalue = true;
-};
-}  // namespace detail
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/macro_scope.hpp>
-
-// #include <nlohmann/detail/meta/cpp_future.hpp>
-
-// #include <nlohmann/detail/meta/type_traits.hpp>
-
-// #include <nlohmann/detail/output/binary_writer.hpp>
-
-
-#include <algorithm> // reverse
-#include <array> // array
-#include <cstdint> // uint8_t, uint16_t, uint32_t, uint64_t
-#include <cstring> // memcpy
-#include <limits> // numeric_limits
-#include <string> // string
-#include <cmath> // isnan, isinf
-
-// #include <nlohmann/detail/input/binary_reader.hpp>
-
-// #include <nlohmann/detail/macro_scope.hpp>
-
-// #include <nlohmann/detail/output/output_adapters.hpp>
-
-
-#include <algorithm> // copy
-#include <cstddef> // size_t
-#include <ios> // streamsize
-#include <iterator> // back_inserter
-#include <memory> // shared_ptr, make_shared
-#include <ostream> // basic_ostream
-#include <string> // basic_string
-#include <vector> // vector
-// #include <nlohmann/detail/macro_scope.hpp>
-
-
-namespace nlohmann
-{
-namespace detail
-{
-/// abstract output adapter interface
-template<typename CharType> struct output_adapter_protocol
-{
-    virtual void write_character(CharType c) = 0;
-    virtual void write_characters(const CharType* s, std::size_t length) = 0;
-    virtual ~output_adapter_protocol() = default;
-};
-
-/// a type to simplify interfaces
-template<typename CharType>
-using output_adapter_t = std::shared_ptr<output_adapter_protocol<CharType>>;
-
-/// output adapter for byte vectors
-template<typename CharType>
-class output_vector_adapter : public output_adapter_protocol<CharType>
-{
-  public:
-    explicit output_vector_adapter(std::vector<CharType>& vec) noexcept
-        : v(vec)
-    {}
-
-    void write_character(CharType c) override
-    {
-        v.push_back(c);
-    }
-
-    JSON_HEDLEY_NON_NULL(2)
-    void write_characters(const CharType* s, std::size_t length) override
-    {
-        std::copy(s, s + length, std::back_inserter(v));
-    }
-
-  private:
-    std::vector<CharType>& v;
-};
-
-/// output adapter for output streams
-template<typename CharType>
-class output_stream_adapter : public output_adapter_protocol<CharType>
-{
-  public:
-    explicit output_stream_adapter(std::basic_ostream<CharType>& s) noexcept
-        : stream(s)
-    {}
-
-    void write_character(CharType c) override
-    {
-        stream.put(c);
-    }
-
-    JSON_HEDLEY_NON_NULL(2)
-    void write_characters(const CharType* s, std::size_t length) override
-    {
-        stream.write(s, static_cast<std::streamsize>(length));
-    }
-
-  private:
-    std::basic_ostream<CharType>& stream;
-};
-
-/// output adapter for basic_string
-template<typename CharType, typename StringType = std::basic_string<CharType>>
-class output_string_adapter : public output_adapter_protocol<CharType>
-{
-  public:
-    explicit output_string_adapter(StringType& s) noexcept
-        : str(s)
-    {}
-
-    void write_character(CharType c) override
-    {
-        str.push_back(c);
-    }
-
-    JSON_HEDLEY_NON_NULL(2)
-    void write_characters(const CharType* s, std::size_t length) override
-    {
-        str.append(s, length);
-    }
-
-  private:
-    StringType& str;
-};
-
-template<typename CharType, typename StringType = std::basic_string<CharType>>
-class output_adapter
-{
-  public:
-    output_adapter(std::vector<CharType>& vec)
-        : oa(std::make_shared<output_vector_adapter<CharType>>(vec)) {}
-
-    output_adapter(std::basic_ostream<CharType>& s)
-        : oa(std::make_shared<output_stream_adapter<CharType>>(s)) {}
-
-    output_adapter(StringType& s)
-        : oa(std::make_shared<output_string_adapter<CharType, StringType>>(s)) {}
-
-    operator output_adapter_t<CharType>()
-    {
-        return oa;
-    }
-
-  private:
-    output_adapter_t<CharType> oa = nullptr;
-};
-}  // namespace detail
-}  // namespace nlohmann
-
-
-namespace nlohmann
-{
-namespace detail
-{
-///////////////////
-// binary writer //
-///////////////////
-
-/*!
-@brief serialization to CBOR and MessagePack values
-*/
-template<typename BasicJsonType, typename CharType>
-class binary_writer
-{
-    using string_t = typename BasicJsonType::string_t;
-    using binary_t = typename BasicJsonType::binary_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-
-  public:
-    /*!
-    @brief create a binary writer
-
-    @param[in] adapter  output adapter to write to
-    */
-    explicit binary_writer(output_adapter_t<CharType> adapter) : oa(adapter)
-    {
-        JSON_ASSERT(oa);
-    }
-
-    /*!
-    @param[in] j  JSON value to serialize
-    @pre       j.type() == value_t::object
-    */
-    void write_bson(const BasicJsonType& j)
-    {
-        switch (j.type())
-        {
-            case value_t::object:
-            {
-                write_bson_object(*j.m_value.object);
-                break;
-            }
-
-            default:
-            {
-                JSON_THROW(type_error::create(317, "to serialize to BSON, top-level type must be object, but is " + std::string(j.type_name())));
-            }
-        }
-    }
-
-    /*!
-    @param[in] j  JSON value to serialize
-    */
-    void write_cbor(const BasicJsonType& j)
-    {
-        switch (j.type())
-        {
-            case value_t::null:
-            {
-                oa->write_character(to_char_type(0xF6));
-                break;
-            }
-
-            case value_t::boolean:
-            {
-                oa->write_character(j.m_value.boolean
-                                    ? to_char_type(0xF5)
-                                    : to_char_type(0xF4));
-                break;
-            }
-
-            case value_t::number_integer:
-            {
-                if (j.m_value.number_integer >= 0)
-                {
-                    // CBOR does not differentiate between positive signed
-                    // integers and unsigned integers. Therefore, we used the
-                    // code from the value_t::number_unsigned case here.
-                    if (j.m_value.number_integer <= 0x17)
-                    {
-                        write_number(static_cast<std::uint8_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_integer <= (std::numeric_limits<std::uint8_t>::max)())
-                    {
-                        oa->write_character(to_char_type(0x18));
-                        write_number(static_cast<std::uint8_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_integer <= (std::numeric_limits<std::uint16_t>::max)())
-                    {
-                        oa->write_character(to_char_type(0x19));
-                        write_number(static_cast<std::uint16_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_integer <= (std::numeric_limits<std::uint32_t>::max)())
-                    {
-                        oa->write_character(to_char_type(0x1A));
-                        write_number(static_cast<std::uint32_t>(j.m_value.number_integer));
-                    }
-                    else
-                    {
-                        oa->write_character(to_char_type(0x1B));
-                        write_number(static_cast<std::uint64_t>(j.m_value.number_integer));
-                    }
-                }
-                else
-                {
-                    // The conversions below encode the sign in the first
-                    // byte, and the value is converted to a positive number.
-                    const auto positive_number = -1 - j.m_value.number_integer;
-                    if (j.m_value.number_integer >= -24)
-                    {
-                        write_number(static_cast<std::uint8_t>(0x20 + positive_number));
-                    }
-                    else if (positive_number <= (std::numeric_limits<std::uint8_t>::max)())
-                    {
-                        oa->write_character(to_char_type(0x38));
-                        write_number(static_cast<std::uint8_t>(positive_number));
-                    }
-                    else if (positive_number <= (std::numeric_limits<std::uint16_t>::max)())
-                    {
-                        oa->write_character(to_char_type(0x39));
-                        write_number(static_cast<std::uint16_t>(positive_number));
-                    }
-                    else if (positive_number <= (std::numeric_limits<std::uint32_t>::max)())
-                    {
-                        oa->write_character(to_char_type(0x3A));
-                        write_number(static_cast<std::uint32_t>(positive_number));
-                    }
-                    else
-                    {
-                        oa->write_character(to_char_type(0x3B));
-                        write_number(static_cast<std::uint64_t>(positive_number));
-                    }
-                }
-                break;
-            }
-
-            case value_t::number_unsigned:
-            {
-                if (j.m_value.number_unsigned <= 0x17)
-                {
-                    write_number(static_cast<std::uint8_t>(j.m_value.number_unsigned));
-                }
-                else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint8_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x18));
-                    write_number(static_cast<std::uint8_t>(j.m_value.number_unsigned));
-                }
-                else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint16_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x19));
-                    write_number(static_cast<std::uint16_t>(j.m_value.number_unsigned));
-                }
-                else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint32_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x1A));
-                    write_number(static_cast<std::uint32_t>(j.m_value.number_unsigned));
-                }
-                else
-                {
-                    oa->write_character(to_char_type(0x1B));
-                    write_number(static_cast<std::uint64_t>(j.m_value.number_unsigned));
-                }
-                break;
-            }
-
-            case value_t::number_float:
-            {
-                if (std::isnan(j.m_value.number_float))
-                {
-                    // NaN is 0xf97e00 in CBOR
-                    oa->write_character(to_char_type(0xF9));
-                    oa->write_character(to_char_type(0x7E));
-                    oa->write_character(to_char_type(0x00));
-                }
-                else if (std::isinf(j.m_value.number_float))
-                {
-                    // Infinity is 0xf97c00, -Infinity is 0xf9fc00
-                    oa->write_character(to_char_type(0xf9));
-                    oa->write_character(j.m_value.number_float > 0 ? to_char_type(0x7C) : to_char_type(0xFC));
-                    oa->write_character(to_char_type(0x00));
-                }
-                else
-                {
-                    write_compact_float(j.m_value.number_float, detail::input_format_t::cbor);
-                }
-                break;
-            }
-
-            case value_t::string:
-            {
-                // step 1: write control byte and the string length
-                const auto N = j.m_value.string->size();
-                if (N <= 0x17)
-                {
-                    write_number(static_cast<std::uint8_t>(0x60 + N));
-                }
-                else if (N <= (std::numeric_limits<std::uint8_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x78));
-                    write_number(static_cast<std::uint8_t>(N));
-                }
-                else if (N <= (std::numeric_limits<std::uint16_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x79));
-                    write_number(static_cast<std::uint16_t>(N));
-                }
-                else if (N <= (std::numeric_limits<std::uint32_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x7A));
-                    write_number(static_cast<std::uint32_t>(N));
-                }
-                // LCOV_EXCL_START
-                else if (N <= (std::numeric_limits<std::uint64_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x7B));
-                    write_number(static_cast<std::uint64_t>(N));
-                }
-                // LCOV_EXCL_STOP
-
-                // step 2: write the string
-                oa->write_characters(
-                    reinterpret_cast<const CharType*>(j.m_value.string->c_str()),
-                    j.m_value.string->size());
-                break;
-            }
-
-            case value_t::array:
-            {
-                // step 1: write control byte and the array size
-                const auto N = j.m_value.array->size();
-                if (N <= 0x17)
-                {
-                    write_number(static_cast<std::uint8_t>(0x80 + N));
-                }
-                else if (N <= (std::numeric_limits<std::uint8_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x98));
-                    write_number(static_cast<std::uint8_t>(N));
-                }
-                else if (N <= (std::numeric_limits<std::uint16_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x99));
-                    write_number(static_cast<std::uint16_t>(N));
-                }
-                else if (N <= (std::numeric_limits<std::uint32_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x9A));
-                    write_number(static_cast<std::uint32_t>(N));
-                }
-                // LCOV_EXCL_START
-                else if (N <= (std::numeric_limits<std::uint64_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x9B));
-                    write_number(static_cast<std::uint64_t>(N));
-                }
-                // LCOV_EXCL_STOP
-
-                // step 2: write each element
-                for (const auto& el : *j.m_value.array)
-                {
-                    write_cbor(el);
-                }
-                break;
-            }
-
-            case value_t::binary:
-            {
-                if (j.m_value.binary->has_subtype())
-                {
-                    write_number(static_cast<std::uint8_t>(0xd8));
-                    write_number(j.m_value.binary->subtype());
-                }
-
-                // step 1: write control byte and the binary array size
-                const auto N = j.m_value.binary->size();
-                if (N <= 0x17)
-                {
-                    write_number(static_cast<std::uint8_t>(0x40 + N));
-                }
-                else if (N <= (std::numeric_limits<std::uint8_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x58));
-                    write_number(static_cast<std::uint8_t>(N));
-                }
-                else if (N <= (std::numeric_limits<std::uint16_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x59));
-                    write_number(static_cast<std::uint16_t>(N));
-                }
-                else if (N <= (std::numeric_limits<std::uint32_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x5A));
-                    write_number(static_cast<std::uint32_t>(N));
-                }
-                // LCOV_EXCL_START
-                else if (N <= (std::numeric_limits<std::uint64_t>::max)())
-                {
-                    oa->write_character(to_char_type(0x5B));
-                    write_number(static_cast<std::uint64_t>(N));
-                }
-                // LCOV_EXCL_STOP
-
-                // step 2: write each element
-                oa->write_characters(
-                    reinterpret_cast<const CharType*>(j.m_value.binary->data()),
-                    N);
-
-                break;
-            }
-
-            case value_t::object:
-            {
-                // step 1: write control byte and the object size
-                const auto N = j.m_value.object->size();
-                if (N <= 0x17)
-                {
-                    write_number(static_cast<std::uint8_t>(0xA0 + N));
-                }
-                else if (N <= (std::numeric_limits<std::uint8_t>::max)())
-                {
-                    oa->write_character(to_char_type(0xB8));
-                    write_number(static_cast<std::uint8_t>(N));
-                }
-                else if (N <= (std::numeric_limits<std::uint16_t>::max)())
-                {
-                    oa->write_character(to_char_type(0xB9));
-                    write_number(static_cast<std::uint16_t>(N));
-                }
-                else if (N <= (std::numeric_limits<std::uint32_t>::max)())
-                {
-                    oa->write_character(to_char_type(0xBA));
-                    write_number(static_cast<std::uint32_t>(N));
-                }
-                // LCOV_EXCL_START
-                else if (N <= (std::numeric_limits<std::uint64_t>::max)())
-                {
-                    oa->write_character(to_char_type(0xBB));
-                    write_number(static_cast<std::uint64_t>(N));
-                }
-                // LCOV_EXCL_STOP
-
-                // step 2: write each element
-                for (const auto& el : *j.m_value.object)
-                {
-                    write_cbor(el.first);
-                    write_cbor(el.second);
-                }
-                break;
-            }
-
-            default:
-                break;
-        }
-    }
-
-    /*!
-    @param[in] j  JSON value to serialize
-    */
-    void write_msgpack(const BasicJsonType& j)
-    {
-        switch (j.type())
-        {
-            case value_t::null: // nil
-            {
-                oa->write_character(to_char_type(0xC0));
-                break;
-            }
-
-            case value_t::boolean: // true and false
-            {
-                oa->write_character(j.m_value.boolean
-                                    ? to_char_type(0xC3)
-                                    : to_char_type(0xC2));
-                break;
-            }
-
-            case value_t::number_integer:
-            {
-                if (j.m_value.number_integer >= 0)
-                {
-                    // MessagePack does not differentiate between positive
-                    // signed integers and unsigned integers. Therefore, we used
-                    // the code from the value_t::number_unsigned case here.
-                    if (j.m_value.number_unsigned < 128)
-                    {
-                        // positive fixnum
-                        write_number(static_cast<std::uint8_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint8_t>::max)())
-                    {
-                        // uint 8
-                        oa->write_character(to_char_type(0xCC));
-                        write_number(static_cast<std::uint8_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint16_t>::max)())
-                    {
-                        // uint 16
-                        oa->write_character(to_char_type(0xCD));
-                        write_number(static_cast<std::uint16_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint32_t>::max)())
-                    {
-                        // uint 32
-                        oa->write_character(to_char_type(0xCE));
-                        write_number(static_cast<std::uint32_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint64_t>::max)())
-                    {
-                        // uint 64
-                        oa->write_character(to_char_type(0xCF));
-                        write_number(static_cast<std::uint64_t>(j.m_value.number_integer));
-                    }
-                }
-                else
-                {
-                    if (j.m_value.number_integer >= -32)
-                    {
-                        // negative fixnum
-                        write_number(static_cast<std::int8_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_integer >= (std::numeric_limits<std::int8_t>::min)() &&
-                             j.m_value.number_integer <= (std::numeric_limits<std::int8_t>::max)())
-                    {
-                        // int 8
-                        oa->write_character(to_char_type(0xD0));
-                        write_number(static_cast<std::int8_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_integer >= (std::numeric_limits<std::int16_t>::min)() &&
-                             j.m_value.number_integer <= (std::numeric_limits<std::int16_t>::max)())
-                    {
-                        // int 16
-                        oa->write_character(to_char_type(0xD1));
-                        write_number(static_cast<std::int16_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_integer >= (std::numeric_limits<std::int32_t>::min)() &&
-                             j.m_value.number_integer <= (std::numeric_limits<std::int32_t>::max)())
-                    {
-                        // int 32
-                        oa->write_character(to_char_type(0xD2));
-                        write_number(static_cast<std::int32_t>(j.m_value.number_integer));
-                    }
-                    else if (j.m_value.number_integer >= (std::numeric_limits<std::int64_t>::min)() &&
-                             j.m_value.number_integer <= (std::numeric_limits<std::int64_t>::max)())
-                    {
-                        // int 64
-                        oa->write_character(to_char_type(0xD3));
-                        write_number(static_cast<std::int64_t>(j.m_value.number_integer));
-                    }
-                }
-                break;
-            }
-
-            case value_t::number_unsigned:
-            {
-                if (j.m_value.number_unsigned < 128)
-                {
-                    // positive fixnum
-                    write_number(static_cast<std::uint8_t>(j.m_value.number_integer));
-                }
-                else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint8_t>::max)())
-                {
-                    // uint 8
-                    oa->write_character(to_char_type(0xCC));
-                    write_number(static_cast<std::uint8_t>(j.m_value.number_integer));
-                }
-                else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint16_t>::max)())
-                {
-                    // uint 16
-                    oa->write_character(to_char_type(0xCD));
-                    write_number(static_cast<std::uint16_t>(j.m_value.number_integer));
-                }
-                else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint32_t>::max)())
-                {
-                    // uint 32
-                    oa->write_character(to_char_type(0xCE));
-                    write_number(static_cast<std::uint32_t>(j.m_value.number_integer));
-                }
-                else if (j.m_value.number_unsigned <= (std::numeric_limits<std::uint64_t>::max)())
-                {
-                    // uint 64
-                    oa->write_character(to_char_type(0xCF));
-                    write_number(static_cast<std::uint64_t>(j.m_value.number_integer));
-                }
-                break;
-            }
-
-            case value_t::number_float:
-            {
-                write_compact_float(j.m_value.number_float, detail::input_format_t::msgpack);
-                break;
-            }
-
-            case value_t::string:
-            {
-                // step 1: write control byte and the string length
-                const auto N = j.m_value.string->size();
-                if (N <= 31)
-                {
-                    // fixstr
-                    write_number(static_cast<std::uint8_t>(0xA0 | N));
-                }
-                else if (N <= (std::numeric_limits<std::uint8_t>::max)())
-                {
-                    // str 8
-                    oa->write_character(to_char_type(0xD9));
-                    write_number(static_cast<std::uint8_t>(N));
-                }
-                else if (N <= (std::numeric_limits<std::uint16_t>::max)())
-                {
-                    // str 16
-                    oa->write_character(to_char_type(0xDA));
-                    write_number(static_cast<std::uint16_t>(N));
-                }
-                else if (N <= (std::numeric_limits<std::uint32_t>::max)())
-                {
-                    // str 32
-                    oa->write_character(to_char_type(0xDB));
-                    write_number(static_cast<std::uint32_t>(N));
-                }
-
-                // step 2: write the string
-                oa->write_characters(
-                    reinterpret_cast<const CharType*>(j.m_value.string->c_str()),
-                    j.m_value.string->size());
-                break;
-            }
-
-            case value_t::array:
-            {
-                // step 1: write control byte and the array size
-                const auto N = j.m_value.array->size();
-                if (N <= 15)
-                {
-                    // fixarray
-                    write_number(static_cast<std::uint8_t>(0x90 | N));
-                }
-                else if (N <= (std::numeric_limits<std::uint16_t>::max)())
-                {
-                    // array 16
-                    oa->write_character(to_char_type(0xDC));
-                    write_number(static_cast<std::uint16_t>(N));
-                }
-                else if (N <= (std::numeric_limits<std::uint32_t>::max)())
-                {
-                    // array 32
-                    oa->write_character(to_char_type(0xDD));
-                    write_number(static_cast<std::uint32_t>(N));
-                }
-
-                // step 2: write each element
-                for (const auto& el : *j.m_value.array)
-                {
-                    write_msgpack(el);
-                }
-                break;
-            }
-
-            case value_t::binary:
-            {
-                // step 0: determine if the binary type has a set subtype to
-                // determine whether or not to use the ext or fixext types
-                const bool use_ext = j.m_value.binary->has_subtype();
-
-                // step 1: write control byte and the byte string length
-                const auto N = j.m_value.binary->size();
-                if (N <= (std::numeric_limits<std::uint8_t>::max)())
-                {
-                    std::uint8_t output_type{};
-                    bool fixed = true;
-                    if (use_ext)
-                    {
-                        switch (N)
-                        {
-                            case 1:
-                                output_type = 0xD4; // fixext 1
-                                break;
-                            case 2:
-                                output_type = 0xD5; // fixext 2
-                                break;
-                            case 4:
-                                output_type = 0xD6; // fixext 4
-                                break;
-                            case 8:
-                                output_type = 0xD7; // fixext 8
-                                break;
-                            case 16:
-                                output_type = 0xD8; // fixext 16
-                                break;
-                            default:
-                                output_type = 0xC7; // ext 8
-                                fixed = false;
-                                break;
-                        }
-
-                    }
-                    else
-                    {
-                        output_type = 0xC4; // bin 8
-                        fixed = false;
-                    }
-
-                    oa->write_character(to_char_type(output_type));
-                    if (!fixed)
-                    {
-                        write_number(static_cast<std::uint8_t>(N));
-                    }
-                }
-                else if (N <= (std::numeric_limits<std::uint16_t>::max)())
-                {
-                    std::uint8_t output_type = use_ext
-                                               ? 0xC8 // ext 16
-                                               : 0xC5; // bin 16
-
-                    oa->write_character(to_char_type(output_type));
-                    write_number(static_cast<std::uint16_t>(N));
-                }
-                else if (N <= (std::numeric_limits<std::uint32_t>::max)())
-                {
-                    std::uint8_t output_type = use_ext
-                                               ? 0xC9 // ext 32
-                                               : 0xC6; // bin 32
-
-                    oa->write_character(to_char_type(output_type));
-                    write_number(static_cast<std::uint32_t>(N));
-                }
-
-                // step 1.5: if this is an ext type, write the subtype
-                if (use_ext)
-                {
-                    write_number(static_cast<std::int8_t>(j.m_value.binary->subtype()));
-                }
-
-                // step 2: write the byte string
-                oa->write_characters(
-                    reinterpret_cast<const CharType*>(j.m_value.binary->data()),
-                    N);
-
-                break;
-            }
-
-            case value_t::object:
-            {
-                // step 1: write control byte and the object size
-                const auto N = j.m_value.object->size();
-                if (N <= 15)
-                {
-                    // fixmap
-                    write_number(static_cast<std::uint8_t>(0x80 | (N & 0xF)));
-                }
-                else if (N <= (std::numeric_limits<std::uint16_t>::max)())
-                {
-                    // map 16
-                    oa->write_character(to_char_type(0xDE));
-                    write_number(static_cast<std::uint16_t>(N));
-                }
-                else if (N <= (std::numeric_limits<std::uint32_t>::max)())
-                {
-                    // map 32
-                    oa->write_character(to_char_type(0xDF));
-                    write_number(static_cast<std::uint32_t>(N));
-                }
-
-                // step 2: write each element
-                for (const auto& el : *j.m_value.object)
-                {
-                    write_msgpack(el.first);
-                    write_msgpack(el.second);
-                }
-                break;
-            }
-
-            default:
-                break;
-        }
-    }
-
-    /*!
-    @param[in] j  JSON value to serialize
-    @param[in] use_count   whether to use '#' prefixes (optimized format)
-    @param[in] use_type    whether to use '$' prefixes (optimized format)
-    @param[in] add_prefix  whether prefixes need to be used for this value
-    */
-    void write_ubjson(const BasicJsonType& j, const bool use_count,
-                      const bool use_type, const bool add_prefix = true)
-    {
-        switch (j.type())
-        {
-            case value_t::null:
-            {
-                if (add_prefix)
-                {
-                    oa->write_character(to_char_type('Z'));
-                }
-                break;
-            }
-
-            case value_t::boolean:
-            {
-                if (add_prefix)
-                {
-                    oa->write_character(j.m_value.boolean
-                                        ? to_char_type('T')
-                                        : to_char_type('F'));
-                }
-                break;
-            }
-
-            case value_t::number_integer:
-            {
-                write_number_with_ubjson_prefix(j.m_value.number_integer, add_prefix);
-                break;
-            }
-
-            case value_t::number_unsigned:
-            {
-                write_number_with_ubjson_prefix(j.m_value.number_unsigned, add_prefix);
-                break;
-            }
-
-            case value_t::number_float:
-            {
-                write_number_with_ubjson_prefix(j.m_value.number_float, add_prefix);
-                break;
-            }
-
-            case value_t::string:
-            {
-                if (add_prefix)
-                {
-                    oa->write_character(to_char_type('S'));
-                }
-                write_number_with_ubjson_prefix(j.m_value.string->size(), true);
-                oa->write_characters(
-                    reinterpret_cast<const CharType*>(j.m_value.string->c_str()),
-                    j.m_value.string->size());
-                break;
-            }
-
-            case value_t::array:
-            {
-                if (add_prefix)
-                {
-                    oa->write_character(to_char_type('['));
-                }
-
-                bool prefix_required = true;
-                if (use_type && !j.m_value.array->empty())
-                {
-                    JSON_ASSERT(use_count);
-                    const CharType first_prefix = ubjson_prefix(j.front());
-                    const bool same_prefix = std::all_of(j.begin() + 1, j.end(),
-                                                         [this, first_prefix](const BasicJsonType & v)
-                    {
-                        return ubjson_prefix(v) == first_prefix;
-                    });
-
-                    if (same_prefix)
-                    {
-                        prefix_required = false;
-                        oa->write_character(to_char_type('$'));
-                        oa->write_character(first_prefix);
-                    }
-                }
-
-                if (use_count)
-                {
-                    oa->write_character(to_char_type('#'));
-                    write_number_with_ubjson_prefix(j.m_value.array->size(), true);
-                }
-
-                for (const auto& el : *j.m_value.array)
-                {
-                    write_ubjson(el, use_count, use_type, prefix_required);
-                }
-
-                if (!use_count)
-                {
-                    oa->write_character(to_char_type(']'));
-                }
-
-                break;
-            }
-
-            case value_t::binary:
-            {
-                if (add_prefix)
-                {
-                    oa->write_character(to_char_type('['));
-                }
-
-                if (use_type && !j.m_value.binary->empty())
-                {
-                    JSON_ASSERT(use_count);
-                    oa->write_character(to_char_type('$'));
-                    oa->write_character('U');
-                }
-
-                if (use_count)
-                {
-                    oa->write_character(to_char_type('#'));
-                    write_number_with_ubjson_prefix(j.m_value.binary->size(), true);
-                }
-
-                if (use_type)
-                {
-                    oa->write_characters(
-                        reinterpret_cast<const CharType*>(j.m_value.binary->data()),
-                        j.m_value.binary->size());
-                }
-                else
-                {
-                    for (size_t i = 0; i < j.m_value.binary->size(); ++i)
-                    {
-                        oa->write_character(to_char_type('U'));
-                        oa->write_character(j.m_value.binary->data()[i]);
-                    }
-                }
-
-                if (!use_count)
-                {
-                    oa->write_character(to_char_type(']'));
-                }
-
-                break;
-            }
-
-            case value_t::object:
-            {
-                if (add_prefix)
-                {
-                    oa->write_character(to_char_type('{'));
-                }
-
-                bool prefix_required = true;
-                if (use_type && !j.m_value.object->empty())
-                {
-                    JSON_ASSERT(use_count);
-                    const CharType first_prefix = ubjson_prefix(j.front());
-                    const bool same_prefix = std::all_of(j.begin(), j.end(),
-                                                         [this, first_prefix](const BasicJsonType & v)
-                    {
-                        return ubjson_prefix(v) == first_prefix;
-                    });
-
-                    if (same_prefix)
-                    {
-                        prefix_required = false;
-                        oa->write_character(to_char_type('$'));
-                        oa->write_character(first_prefix);
-                    }
-                }
-
-                if (use_count)
-                {
-                    oa->write_character(to_char_type('#'));
-                    write_number_with_ubjson_prefix(j.m_value.object->size(), true);
-                }
-
-                for (const auto& el : *j.m_value.object)
-                {
-                    write_number_with_ubjson_prefix(el.first.size(), true);
-                    oa->write_characters(
-                        reinterpret_cast<const CharType*>(el.first.c_str()),
-                        el.first.size());
-                    write_ubjson(el.second, use_count, use_type, prefix_required);
-                }
-
-                if (!use_count)
-                {
-                    oa->write_character(to_char_type('}'));
-                }
-
-                break;
-            }
-
-            default:
-                break;
-        }
-    }
-
-  private:
-    //////////
-    // BSON //
-    //////////
-
-    /*!
-    @return The size of a BSON document entry header, including the id marker
-            and the entry name size (and its null-terminator).
-    */
-    static std::size_t calc_bson_entry_header_size(const string_t& name)
-    {
-        const auto it = name.find(static_cast<typename string_t::value_type>(0));
-        if (JSON_HEDLEY_UNLIKELY(it != BasicJsonType::string_t::npos))
-        {
-            JSON_THROW(out_of_range::create(409,
-                                            "BSON key cannot contain code point U+0000 (at byte " + std::to_string(it) + ")"));
-        }
-
-        return /*id*/ 1ul + name.size() + /*zero-terminator*/1u;
-    }
-
-    /*!
-    @brief Writes the given @a element_type and @a name to the output adapter
-    */
-    void write_bson_entry_header(const string_t& name,
-                                 const std::uint8_t element_type)
-    {
-        oa->write_character(to_char_type(element_type)); // boolean
-        oa->write_characters(
-            reinterpret_cast<const CharType*>(name.c_str()),
-            name.size() + 1u);
-    }
-
-    /*!
-    @brief Writes a BSON element with key @a name and boolean value @a value
-    */
-    void write_bson_boolean(const string_t& name,
-                            const bool value)
-    {
-        write_bson_entry_header(name, 0x08);
-        oa->write_character(value ? to_char_type(0x01) : to_char_type(0x00));
-    }
-
-    /*!
-    @brief Writes a BSON element with key @a name and double value @a value
-    */
-    void write_bson_double(const string_t& name,
-                           const double value)
-    {
-        write_bson_entry_header(name, 0x01);
-        write_number<double, true>(value);
-    }
-
-    /*!
-    @return The size of the BSON-encoded string in @a value
-    */
-    static std::size_t calc_bson_string_size(const string_t& value)
-    {
-        return sizeof(std::int32_t) + value.size() + 1ul;
-    }
-
-    /*!
-    @brief Writes a BSON element with key @a name and string value @a value
-    */
-    void write_bson_string(const string_t& name,
-                           const string_t& value)
-    {
-        write_bson_entry_header(name, 0x02);
-
-        write_number<std::int32_t, true>(static_cast<std::int32_t>(value.size() + 1ul));
-        oa->write_characters(
-            reinterpret_cast<const CharType*>(value.c_str()),
-            value.size() + 1);
-    }
-
-    /*!
-    @brief Writes a BSON element with key @a name and null value
-    */
-    void write_bson_null(const string_t& name)
-    {
-        write_bson_entry_header(name, 0x0A);
-    }
-
-    /*!
-    @return The size of the BSON-encoded integer @a value
-    */
-    static std::size_t calc_bson_integer_size(const std::int64_t value)
-    {
-        return (std::numeric_limits<std::int32_t>::min)() <= value && value <= (std::numeric_limits<std::int32_t>::max)()
-               ? sizeof(std::int32_t)
-               : sizeof(std::int64_t);
-    }
-
-    /*!
-    @brief Writes a BSON element with key @a name and integer @a value
-    */
-    void write_bson_integer(const string_t& name,
-                            const std::int64_t value)
-    {
-        if ((std::numeric_limits<std::int32_t>::min)() <= value && value <= (std::numeric_limits<std::int32_t>::max)())
-        {
-            write_bson_entry_header(name, 0x10); // int32
-            write_number<std::int32_t, true>(static_cast<std::int32_t>(value));
-        }
-        else
-        {
-            write_bson_entry_header(name, 0x12); // int64
-            write_number<std::int64_t, true>(static_cast<std::int64_t>(value));
-        }
-    }
-
-    /*!
-    @return The size of the BSON-encoded unsigned integer in @a j
-    */
-    static constexpr std::size_t calc_bson_unsigned_size(const std::uint64_t value) noexcept
-    {
-        return (value <= static_cast<std::uint64_t>((std::numeric_limits<std::int32_t>::max)()))
-               ? sizeof(std::int32_t)
-               : sizeof(std::int64_t);
-    }
-
-    /*!
-    @brief Writes a BSON element with key @a name and unsigned @a value
-    */
-    void write_bson_unsigned(const string_t& name,
-                             const std::uint64_t value)
-    {
-        if (value <= static_cast<std::uint64_t>((std::numeric_limits<std::int32_t>::max)()))
-        {
-            write_bson_entry_header(name, 0x10 /* int32 */);
-            write_number<std::int32_t, true>(static_cast<std::int32_t>(value));
-        }
-        else if (value <= static_cast<std::uint64_t>((std::numeric_limits<std::int64_t>::max)()))
-        {
-            write_bson_entry_header(name, 0x12 /* int64 */);
-            write_number<std::int64_t, true>(static_cast<std::int64_t>(value));
-        }
-        else
-        {
-            JSON_THROW(out_of_range::create(407, "integer number " + std::to_string(value) + " cannot be represented by BSON as it does not fit int64"));
-        }
-    }
-
-    /*!
-    @brief Writes a BSON element with key @a name and object @a value
-    */
-    void write_bson_object_entry(const string_t& name,
-                                 const typename BasicJsonType::object_t& value)
-    {
-        write_bson_entry_header(name, 0x03); // object
-        write_bson_object(value);
-    }
-
-    /*!
-    @return The size of the BSON-encoded array @a value
-    */
-    static std::size_t calc_bson_array_size(const typename BasicJsonType::array_t& value)
-    {
-        std::size_t array_index = 0ul;
-
-        const std::size_t embedded_document_size = std::accumulate(std::begin(value), std::end(value), std::size_t(0), [&array_index](std::size_t result, const typename BasicJsonType::array_t::value_type & el)
-        {
-            return result + calc_bson_element_size(std::to_string(array_index++), el);
-        });
-
-        return sizeof(std::int32_t) + embedded_document_size + 1ul;
-    }
-
-    /*!
-    @return The size of the BSON-encoded binary array @a value
-    */
-    static std::size_t calc_bson_binary_size(const typename BasicJsonType::binary_t& value)
-    {
-        return sizeof(std::int32_t) + value.size() + 1ul;
-    }
-
-    /*!
-    @brief Writes a BSON element with key @a name and array @a value
-    */
-    void write_bson_array(const string_t& name,
-                          const typename BasicJsonType::array_t& value)
-    {
-        write_bson_entry_header(name, 0x04); // array
-        write_number<std::int32_t, true>(static_cast<std::int32_t>(calc_bson_array_size(value)));
-
-        std::size_t array_index = 0ul;
-
-        for (const auto& el : value)
-        {
-            write_bson_element(std::to_string(array_index++), el);
-        }
-
-        oa->write_character(to_char_type(0x00));
-    }
-
-    /*!
-    @brief Writes a BSON element with key @a name and binary value @a value
-    */
-    void write_bson_binary(const string_t& name,
-                           const binary_t& value)
-    {
-        write_bson_entry_header(name, 0x05);
-
-        write_number<std::int32_t, true>(static_cast<std::int32_t>(value.size()));
-        write_number(value.has_subtype() ? value.subtype() : std::uint8_t(0x00));
-
-        oa->write_characters(reinterpret_cast<const CharType*>(value.data()), value.size());
-    }
-
-    /*!
-    @brief Calculates the size necessary to serialize the JSON value @a j with its @a name
-    @return The calculated size for the BSON document entry for @a j with the given @a name.
-    */
-    static std::size_t calc_bson_element_size(const string_t& name,
-            const BasicJsonType& j)
-    {
-        const auto header_size = calc_bson_entry_header_size(name);
-        switch (j.type())
-        {
-            case value_t::object:
-                return header_size + calc_bson_object_size(*j.m_value.object);
-
-            case value_t::array:
-                return header_size + calc_bson_array_size(*j.m_value.array);
-
-            case value_t::binary:
-                return header_size + calc_bson_binary_size(*j.m_value.binary);
-
-            case value_t::boolean:
-                return header_size + 1ul;
-
-            case value_t::number_float:
-                return header_size + 8ul;
-
-            case value_t::number_integer:
-                return header_size + calc_bson_integer_size(j.m_value.number_integer);
-
-            case value_t::number_unsigned:
-                return header_size + calc_bson_unsigned_size(j.m_value.number_unsigned);
-
-            case value_t::string:
-                return header_size + calc_bson_string_size(*j.m_value.string);
-
-            case value_t::null:
-                return header_size + 0ul;
-
-            // LCOV_EXCL_START
-            default:
-                JSON_ASSERT(false);
-                return 0ul;
-                // LCOV_EXCL_STOP
-        }
-    }
-
-    /*!
-    @brief Serializes the JSON value @a j to BSON and associates it with the
-           key @a name.
-    @param name The name to associate with the JSON entity @a j within the
-                current BSON document
-    @return The size of the BSON entry
-    */
-    void write_bson_element(const string_t& name,
-                            const BasicJsonType& j)
-    {
-        switch (j.type())
-        {
-            case value_t::object:
-                return write_bson_object_entry(name, *j.m_value.object);
-
-            case value_t::array:
-                return write_bson_array(name, *j.m_value.array);
-
-            case value_t::binary:
-                return write_bson_binary(name, *j.m_value.binary);
-
-            case value_t::boolean:
-                return write_bson_boolean(name, j.m_value.boolean);
-
-            case value_t::number_float:
-                return write_bson_double(name, j.m_value.number_float);
-
-            case value_t::number_integer:
-                return write_bson_integer(name, j.m_value.number_integer);
-
-            case value_t::number_unsigned:
-                return write_bson_unsigned(name, j.m_value.number_unsigned);
-
-            case value_t::string:
-                return write_bson_string(name, *j.m_value.string);
-
-            case value_t::null:
-                return write_bson_null(name);
-
-            // LCOV_EXCL_START
-            default:
-                JSON_ASSERT(false);
-                return;
-                // LCOV_EXCL_STOP
-        }
-    }
-
-    /*!
-    @brief Calculates the size of the BSON serialization of the given
-           JSON-object @a j.
-    @param[in] j  JSON value to serialize
-    @pre       j.type() == value_t::object
-    */
-    static std::size_t calc_bson_object_size(const typename BasicJsonType::object_t& value)
-    {
-        std::size_t document_size = std::accumulate(value.begin(), value.end(), std::size_t(0),
-                                    [](size_t result, const typename BasicJsonType::object_t::value_type & el)
-        {
-            return result += calc_bson_element_size(el.first, el.second);
-        });
-
-        return sizeof(std::int32_t) + document_size + 1ul;
-    }
-
-    /*!
-    @param[in] j  JSON value to serialize
-    @pre       j.type() == value_t::object
-    */
-    void write_bson_object(const typename BasicJsonType::object_t& value)
-    {
-        write_number<std::int32_t, true>(static_cast<std::int32_t>(calc_bson_object_size(value)));
-
-        for (const auto& el : value)
-        {
-            write_bson_element(el.first, el.second);
-        }
-
-        oa->write_character(to_char_type(0x00));
-    }
-
-    //////////
-    // CBOR //
-    //////////
-
-    static constexpr CharType get_cbor_float_prefix(float /*unused*/)
-    {
-        return to_char_type(0xFA);  // Single-Precision Float
-    }
-
-    static constexpr CharType get_cbor_float_prefix(double /*unused*/)
-    {
-        return to_char_type(0xFB);  // Double-Precision Float
-    }
-
-    /////////////
-    // MsgPack //
-    /////////////
-
-    static constexpr CharType get_msgpack_float_prefix(float /*unused*/)
-    {
-        return to_char_type(0xCA);  // float 32
-    }
-
-    static constexpr CharType get_msgpack_float_prefix(double /*unused*/)
-    {
-        return to_char_type(0xCB);  // float 64
-    }
-
-    ////////////
-    // UBJSON //
-    ////////////
-
-    // UBJSON: write number (floating point)
-    template<typename NumberType, typename std::enable_if<
-                 std::is_floating_point<NumberType>::value, int>::type = 0>
-    void write_number_with_ubjson_prefix(const NumberType n,
-                                         const bool add_prefix)
-    {
-        if (add_prefix)
-        {
-            oa->write_character(get_ubjson_float_prefix(n));
-        }
-        write_number(n);
-    }
-
-    // UBJSON: write number (unsigned integer)
-    template<typename NumberType, typename std::enable_if<
-                 std::is_unsigned<NumberType>::value, int>::type = 0>
-    void write_number_with_ubjson_prefix(const NumberType n,
-                                         const bool add_prefix)
-    {
-        if (n <= static_cast<std::uint64_t>((std::numeric_limits<std::int8_t>::max)()))
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('i'));  // int8
-            }
-            write_number(static_cast<std::uint8_t>(n));
-        }
-        else if (n <= (std::numeric_limits<std::uint8_t>::max)())
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('U'));  // uint8
-            }
-            write_number(static_cast<std::uint8_t>(n));
-        }
-        else if (n <= static_cast<std::uint64_t>((std::numeric_limits<std::int16_t>::max)()))
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('I'));  // int16
-            }
-            write_number(static_cast<std::int16_t>(n));
-        }
-        else if (n <= static_cast<std::uint64_t>((std::numeric_limits<std::int32_t>::max)()))
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('l'));  // int32
-            }
-            write_number(static_cast<std::int32_t>(n));
-        }
-        else if (n <= static_cast<std::uint64_t>((std::numeric_limits<std::int64_t>::max)()))
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('L'));  // int64
-            }
-            write_number(static_cast<std::int64_t>(n));
-        }
-        else
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('H'));  // high-precision number
-            }
-
-            const auto number = BasicJsonType(n).dump();
-            write_number_with_ubjson_prefix(number.size(), true);
-            for (std::size_t i = 0; i < number.size(); ++i)
-            {
-                oa->write_character(to_char_type(static_cast<std::uint8_t>(number[i])));
-            }
-        }
-    }
-
-    // UBJSON: write number (signed integer)
-    template < typename NumberType, typename std::enable_if <
-                   std::is_signed<NumberType>::value&&
-                   !std::is_floating_point<NumberType>::value, int >::type = 0 >
-    void write_number_with_ubjson_prefix(const NumberType n,
-                                         const bool add_prefix)
-    {
-        if ((std::numeric_limits<std::int8_t>::min)() <= n && n <= (std::numeric_limits<std::int8_t>::max)())
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('i'));  // int8
-            }
-            write_number(static_cast<std::int8_t>(n));
-        }
-        else if (static_cast<std::int64_t>((std::numeric_limits<std::uint8_t>::min)()) <= n && n <= static_cast<std::int64_t>((std::numeric_limits<std::uint8_t>::max)()))
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('U'));  // uint8
-            }
-            write_number(static_cast<std::uint8_t>(n));
-        }
-        else if ((std::numeric_limits<std::int16_t>::min)() <= n && n <= (std::numeric_limits<std::int16_t>::max)())
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('I'));  // int16
-            }
-            write_number(static_cast<std::int16_t>(n));
-        }
-        else if ((std::numeric_limits<std::int32_t>::min)() <= n && n <= (std::numeric_limits<std::int32_t>::max)())
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('l'));  // int32
-            }
-            write_number(static_cast<std::int32_t>(n));
-        }
-        else if ((std::numeric_limits<std::int64_t>::min)() <= n && n <= (std::numeric_limits<std::int64_t>::max)())
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('L'));  // int64
-            }
-            write_number(static_cast<std::int64_t>(n));
-        }
-        // LCOV_EXCL_START
-        else
-        {
-            if (add_prefix)
-            {
-                oa->write_character(to_char_type('H'));  // high-precision number
-            }
-
-            const auto number = BasicJsonType(n).dump();
-            write_number_with_ubjson_prefix(number.size(), true);
-            for (std::size_t i = 0; i < number.size(); ++i)
-            {
-                oa->write_character(to_char_type(static_cast<std::uint8_t>(number[i])));
-            }
-        }
-        // LCOV_EXCL_STOP
-    }
-
-    /*!
-    @brief determine the type prefix of container values
-    */
-    CharType ubjson_prefix(const BasicJsonType& j) const noexcept
-    {
-        switch (j.type())
-        {
-            case value_t::null:
-                return 'Z';
-
-            case value_t::boolean:
-                return j.m_value.boolean ? 'T' : 'F';
-
-            case value_t::number_integer:
-            {
-                if ((std::numeric_limits<std::int8_t>::min)() <= j.m_value.number_integer && j.m_value.number_integer <= (std::numeric_limits<std::int8_t>::max)())
-                {
-                    return 'i';
-                }
-                if ((std::numeric_limits<std::uint8_t>::min)() <= j.m_value.number_integer && j.m_value.number_integer <= (std::numeric_limits<std::uint8_t>::max)())
-                {
-                    return 'U';
-                }
-                if ((std::numeric_limits<std::int16_t>::min)() <= j.m_value.number_integer && j.m_value.number_integer <= (std::numeric_limits<std::int16_t>::max)())
-                {
-                    return 'I';
-                }
-                if ((std::numeric_limits<std::int32_t>::min)() <= j.m_value.number_integer && j.m_value.number_integer <= (std::numeric_limits<std::int32_t>::max)())
-                {
-                    return 'l';
-                }
-                if ((std::numeric_limits<std::int64_t>::min)() <= j.m_value.number_integer && j.m_value.number_integer <= (std::numeric_limits<std::int64_t>::max)())
-                {
-                    return 'L';
-                }
-                // anything else is treated as high-precision number
-                return 'H'; // LCOV_EXCL_LINE
-            }
-
-            case value_t::number_unsigned:
-            {
-                if (j.m_value.number_unsigned <= static_cast<std::uint64_t>((std::numeric_limits<std::int8_t>::max)()))
-                {
-                    return 'i';
-                }
-                if (j.m_value.number_unsigned <= static_cast<std::uint64_t>((std::numeric_limits<std::uint8_t>::max)()))
-                {
-                    return 'U';
-                }
-                if (j.m_value.number_unsigned <= static_cast<std::uint64_t>((std::numeric_limits<std::int16_t>::max)()))
-                {
-                    return 'I';
-                }
-                if (j.m_value.number_unsigned <= static_cast<std::uint64_t>((std::numeric_limits<std::int32_t>::max)()))
-                {
-                    return 'l';
-                }
-                if (j.m_value.number_unsigned <= static_cast<std::uint64_t>((std::numeric_limits<std::int64_t>::max)()))
-                {
-                    return 'L';
-                }
-                // anything else is treated as high-precision number
-                return 'H'; // LCOV_EXCL_LINE
-            }
-
-            case value_t::number_float:
-                return get_ubjson_float_prefix(j.m_value.number_float);
-
-            case value_t::string:
-                return 'S';
-
-            case value_t::array: // fallthrough
-            case value_t::binary:
-                return '[';
-
-            case value_t::object:
-                return '{';
-
-            default:  // discarded values
-                return 'N';
-        }
-    }
-
-    static constexpr CharType get_ubjson_float_prefix(float /*unused*/)
-    {
-        return 'd';  // float 32
-    }
-
-    static constexpr CharType get_ubjson_float_prefix(double /*unused*/)
-    {
-        return 'D';  // float 64
-    }
-
-    ///////////////////////
-    // Utility functions //
-    ///////////////////////
-
-    /*
-    @brief write a number to output input
-    @param[in] n number of type @a NumberType
-    @tparam NumberType the type of the number
-    @tparam OutputIsLittleEndian Set to true if output data is
-                                 required to be little endian
-
-    @note This function needs to respect the system's endianess, because bytes
-          in CBOR, MessagePack, and UBJSON are stored in network order (big
-          endian) and therefore need reordering on little endian systems.
-    */
-    template<typename NumberType, bool OutputIsLittleEndian = false>
-    void write_number(const NumberType n)
-    {
-        // step 1: write number to array of length NumberType
-        std::array<CharType, sizeof(NumberType)> vec;
-        std::memcpy(vec.data(), &n, sizeof(NumberType));
-
-        // step 2: write array to output (with possible reordering)
-        if (is_little_endian != OutputIsLittleEndian)
-        {
-            // reverse byte order prior to conversion if necessary
-            std::reverse(vec.begin(), vec.end());
-        }
-
-        oa->write_characters(vec.data(), sizeof(NumberType));
-    }
-
-    void write_compact_float(const number_float_t n, detail::input_format_t format)
-    {
-        if (static_cast<double>(n) >= static_cast<double>(std::numeric_limits<float>::lowest()) &&
-                static_cast<double>(n) <= static_cast<double>((std::numeric_limits<float>::max)()) &&
-                static_cast<double>(static_cast<float>(n)) == static_cast<double>(n))
-        {
-            oa->write_character(format == detail::input_format_t::cbor
-                                ? get_cbor_float_prefix(static_cast<float>(n))
-                                : get_msgpack_float_prefix(static_cast<float>(n)));
-            write_number(static_cast<float>(n));
-        }
-        else
-        {
-            oa->write_character(format == detail::input_format_t::cbor
-                                ? get_cbor_float_prefix(n)
-                                : get_msgpack_float_prefix(n));
-            write_number(n);
-        }
-    }
-
-  public:
-    // The following to_char_type functions are implement the conversion
-    // between uint8_t and CharType. In case CharType is not unsigned,
-    // such a conversion is required to allow values greater than 128.
-    // See <https://github.com/nlohmann/json/issues/1286> for a discussion.
-    template < typename C = CharType,
-               enable_if_t < std::is_signed<C>::value && std::is_signed<char>::value > * = nullptr >
-    static constexpr CharType to_char_type(std::uint8_t x) noexcept
-    {
-        return *reinterpret_cast<char*>(&x);
-    }
-
-    template < typename C = CharType,
-               enable_if_t < std::is_signed<C>::value && std::is_unsigned<char>::value > * = nullptr >
-    static CharType to_char_type(std::uint8_t x) noexcept
-    {
-        static_assert(sizeof(std::uint8_t) == sizeof(CharType), "size of CharType must be equal to std::uint8_t");
-        static_assert(std::is_trivial<CharType>::value, "CharType must be trivial");
-        CharType result;
-        std::memcpy(&result, &x, sizeof(x));
-        return result;
-    }
-
-    template<typename C = CharType,
-             enable_if_t<std::is_unsigned<C>::value>* = nullptr>
-    static constexpr CharType to_char_type(std::uint8_t x) noexcept
-    {
-        return x;
-    }
-
-    template < typename InputCharType, typename C = CharType,
-               enable_if_t <
-                   std::is_signed<C>::value &&
-                   std::is_signed<char>::value &&
-                   std::is_same<char, typename std::remove_cv<InputCharType>::type>::value
-                   > * = nullptr >
-    static constexpr CharType to_char_type(InputCharType x) noexcept
-    {
-        return x;
-    }
-
-  private:
-    /// whether we can assume little endianess
-    const bool is_little_endian = little_endianess();
-
-    /// the output
-    output_adapter_t<CharType> oa = nullptr;
-};
-}  // namespace detail
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/output/output_adapters.hpp>
-
-// #include <nlohmann/detail/output/serializer.hpp>
-
-
-#include <algorithm> // reverse, remove, fill, find, none_of
-#include <array> // array
-#include <clocale> // localeconv, lconv
-#include <cmath> // labs, isfinite, isnan, signbit
-#include <cstddef> // size_t, ptrdiff_t
-#include <cstdint> // uint8_t
-#include <cstdio> // snprintf
-#include <limits> // numeric_limits
-#include <string> // string, char_traits
-#include <type_traits> // is_same
-#include <utility> // move
-
-// #include <nlohmann/detail/conversions/to_chars.hpp>
-
-
-#include <array> // array
-#include <cmath>   // signbit, isfinite
-#include <cstdint> // intN_t, uintN_t
-#include <cstring> // memcpy, memmove
-#include <limits> // numeric_limits
-#include <type_traits> // conditional
-
-// #include <nlohmann/detail/macro_scope.hpp>
-
-
-namespace nlohmann
-{
-namespace detail
-{
-
-/*!
-@brief implements the Grisu2 algorithm for binary to decimal floating-point
-conversion.
-
-This implementation is a slightly modified version of the reference
-implementation which may be obtained from
-http://florian.loitsch.com/publications (bench.tar.gz).
-
-The code is distributed under the MIT license, Copyright (c) 2009 Florian Loitsch.
-
-For a detailed description of the algorithm see:
-
-[1] Loitsch, "Printing Floating-Point Numbers Quickly and Accurately with
-    Integers", Proceedings of the ACM SIGPLAN 2010 Conference on Programming
-    Language Design and Implementation, PLDI 2010
-[2] Burger, Dybvig, "Printing Floating-Point Numbers Quickly and Accurately",
-    Proceedings of the ACM SIGPLAN 1996 Conference on Programming Language
-    Design and Implementation, PLDI 1996
-*/
-namespace dtoa_impl
-{
-
-template<typename Target, typename Source>
-Target reinterpret_bits(const Source source)
-{
-    static_assert(sizeof(Target) == sizeof(Source), "size mismatch");
-
-    Target target;
-    std::memcpy(&target, &source, sizeof(Source));
-    return target;
-}
-
-struct diyfp // f * 2^e
-{
-    static constexpr int kPrecision = 64; // = q
-
-    std::uint64_t f = 0;
-    int e = 0;
-
-    constexpr diyfp(std::uint64_t f_, int e_) noexcept : f(f_), e(e_) {}
-
-    /*!
-    @brief returns x - y
-    @pre x.e == y.e and x.f >= y.f
-    */
-    static diyfp sub(const diyfp& x, const diyfp& y) noexcept
-    {
-        JSON_ASSERT(x.e == y.e);
-        JSON_ASSERT(x.f >= y.f);
-
-        return {x.f - y.f, x.e};
-    }
-
-    /*!
-    @brief returns x * y
-    @note The result is rounded. (Only the upper q bits are returned.)
-    */
-    static diyfp mul(const diyfp& x, const diyfp& y) noexcept
-    {
-        static_assert(kPrecision == 64, "internal error");
-
-        // Computes:
-        //  f = round((x.f * y.f) / 2^q)
-        //  e = x.e + y.e + q
-
-        // Emulate the 64-bit * 64-bit multiplication:
-        //
-        // p = u * v
-        //   = (u_lo + 2^32 u_hi) (v_lo + 2^32 v_hi)
-        //   = (u_lo v_lo         ) + 2^32 ((u_lo v_hi         ) + (u_hi v_lo         )) + 2^64 (u_hi v_hi         )
-        //   = (p0                ) + 2^32 ((p1                ) + (p2                )) + 2^64 (p3                )
-        //   = (p0_lo + 2^32 p0_hi) + 2^32 ((p1_lo + 2^32 p1_hi) + (p2_lo + 2^32 p2_hi)) + 2^64 (p3                )
-        //   = (p0_lo             ) + 2^32 (p0_hi + p1_lo + p2_lo                      ) + 2^64 (p1_hi + p2_hi + p3)
-        //   = (p0_lo             ) + 2^32 (Q                                          ) + 2^64 (H                 )
-        //   = (p0_lo             ) + 2^32 (Q_lo + 2^32 Q_hi                           ) + 2^64 (H                 )
-        //
-        // (Since Q might be larger than 2^32 - 1)
-        //
-        //   = (p0_lo + 2^32 Q_lo) + 2^64 (Q_hi + H)
-        //
-        // (Q_hi + H does not overflow a 64-bit int)
-        //
-        //   = p_lo + 2^64 p_hi
-
-        const std::uint64_t u_lo = x.f & 0xFFFFFFFFu;
-        const std::uint64_t u_hi = x.f >> 32u;
-        const std::uint64_t v_lo = y.f & 0xFFFFFFFFu;
-        const std::uint64_t v_hi = y.f >> 32u;
-
-        const std::uint64_t p0 = u_lo * v_lo;
-        const std::uint64_t p1 = u_lo * v_hi;
-        const std::uint64_t p2 = u_hi * v_lo;
-        const std::uint64_t p3 = u_hi * v_hi;
-
-        const std::uint64_t p0_hi = p0 >> 32u;
-        const std::uint64_t p1_lo = p1 & 0xFFFFFFFFu;
-        const std::uint64_t p1_hi = p1 >> 32u;
-        const std::uint64_t p2_lo = p2 & 0xFFFFFFFFu;
-        const std::uint64_t p2_hi = p2 >> 32u;
-
-        std::uint64_t Q = p0_hi + p1_lo + p2_lo;
-
-        // The full product might now be computed as
-        //
-        // p_hi = p3 + p2_hi + p1_hi + (Q >> 32)
-        // p_lo = p0_lo + (Q << 32)
-        //
-        // But in this particular case here, the full p_lo is not required.
-        // Effectively we only need to add the highest bit in p_lo to p_hi (and
-        // Q_hi + 1 does not overflow).
-
-        Q += std::uint64_t{1} << (64u - 32u - 1u); // round, ties up
-
-        const std::uint64_t h = p3 + p2_hi + p1_hi + (Q >> 32u);
-
-        return {h, x.e + y.e + 64};
-    }
-
-    /*!
-    @brief normalize x such that the significand is >= 2^(q-1)
-    @pre x.f != 0
-    */
-    static diyfp normalize(diyfp x) noexcept
-    {
-        JSON_ASSERT(x.f != 0);
-
-        while ((x.f >> 63u) == 0)
-        {
-            x.f <<= 1u;
-            x.e--;
-        }
-
-        return x;
-    }
-
-    /*!
-    @brief normalize x such that the result has the exponent E
-    @pre e >= x.e and the upper e - x.e bits of x.f must be zero.
-    */
-    static diyfp normalize_to(const diyfp& x, const int target_exponent) noexcept
-    {
-        const int delta = x.e - target_exponent;
-
-        JSON_ASSERT(delta >= 0);
-        JSON_ASSERT(((x.f << delta) >> delta) == x.f);
-
-        return {x.f << delta, target_exponent};
-    }
-};
-
-struct boundaries
-{
-    diyfp w;
-    diyfp minus;
-    diyfp plus;
-};
-
-/*!
-Compute the (normalized) diyfp representing the input number 'value' and its
-boundaries.
-
-@pre value must be finite and positive
-*/
-template<typename FloatType>
-boundaries compute_boundaries(FloatType value)
-{
-    JSON_ASSERT(std::isfinite(value));
-    JSON_ASSERT(value > 0);
-
-    // Convert the IEEE representation into a diyfp.
-    //
-    // If v is denormal:
-    //      value = 0.F * 2^(1 - bias) = (          F) * 2^(1 - bias - (p-1))
-    // If v is normalized:
-    //      value = 1.F * 2^(E - bias) = (2^(p-1) + F) * 2^(E - bias - (p-1))
-
-    static_assert(std::numeric_limits<FloatType>::is_iec559,
-                  "internal error: dtoa_short requires an IEEE-754 floating-point implementation");
-
-    constexpr int      kPrecision = std::numeric_limits<FloatType>::digits; // = p (includes the hidden bit)
-    constexpr int      kBias      = std::numeric_limits<FloatType>::max_exponent - 1 + (kPrecision - 1);
-    constexpr int      kMinExp    = 1 - kBias;
-    constexpr std::uint64_t kHiddenBit = std::uint64_t{1} << (kPrecision - 1); // = 2^(p-1)
-
-    using bits_type = typename std::conditional<kPrecision == 24, std::uint32_t, std::uint64_t >::type;
-
-    const std::uint64_t bits = reinterpret_bits<bits_type>(value);
-    const std::uint64_t E = bits >> (kPrecision - 1);
-    const std::uint64_t F = bits & (kHiddenBit - 1);
-
-    const bool is_denormal = E == 0;
-    const diyfp v = is_denormal
-                    ? diyfp(F, kMinExp)
-                    : diyfp(F + kHiddenBit, static_cast<int>(E) - kBias);
-
-    // Compute the boundaries m- and m+ of the floating-point value
-    // v = f * 2^e.
-    //
-    // Determine v- and v+, the floating-point predecessor and successor if v,
-    // respectively.
-    //
-    //      v- = v - 2^e        if f != 2^(p-1) or e == e_min                (A)
-    //         = v - 2^(e-1)    if f == 2^(p-1) and e > e_min                (B)
-    //
-    //      v+ = v + 2^e
-    //
-    // Let m- = (v- + v) / 2 and m+ = (v + v+) / 2. All real numbers _strictly_
-    // between m- and m+ round to v, regardless of how the input rounding
-    // algorithm breaks ties.
-    //
-    //      ---+-------------+-------------+-------------+-------------+---  (A)
-    //         v-            m-            v             m+            v+
-    //
-    //      -----------------+------+------+-------------+-------------+---  (B)
-    //                       v-     m-     v             m+            v+
-
-    const bool lower_boundary_is_closer = F == 0 && E > 1;
-    const diyfp m_plus = diyfp(2 * v.f + 1, v.e - 1);
-    const diyfp m_minus = lower_boundary_is_closer
-                          ? diyfp(4 * v.f - 1, v.e - 2)  // (B)
-                          : diyfp(2 * v.f - 1, v.e - 1); // (A)
-
-    // Determine the normalized w+ = m+.
-    const diyfp w_plus = diyfp::normalize(m_plus);
-
-    // Determine w- = m- such that e_(w-) = e_(w+).
-    const diyfp w_minus = diyfp::normalize_to(m_minus, w_plus.e);
-
-    return {diyfp::normalize(v), w_minus, w_plus};
-}
-
-// Given normalized diyfp w, Grisu needs to find a (normalized) cached
-// power-of-ten c, such that the exponent of the product c * w = f * 2^e lies
-// within a certain range [alpha, gamma] (Definition 3.2 from [1])
-//
-//      alpha <= e = e_c + e_w + q <= gamma
-//
-// or
-//
-//      f_c * f_w * 2^alpha <= f_c 2^(e_c) * f_w 2^(e_w) * 2^q
-//                          <= f_c * f_w * 2^gamma
-//
-// Since c and w are normalized, i.e. 2^(q-1) <= f < 2^q, this implies
-//
-//      2^(q-1) * 2^(q-1) * 2^alpha <= c * w * 2^q < 2^q * 2^q * 2^gamma
-//
-// or
-//
-//      2^(q - 2 + alpha) <= c * w < 2^(q + gamma)
-//
-// The choice of (alpha,gamma) determines the size of the table and the form of
-// the digit generation procedure. Using (alpha,gamma)=(-60,-32) works out well
-// in practice:
-//
-// The idea is to cut the number c * w = f * 2^e into two parts, which can be
-// processed independently: An integral part p1, and a fractional part p2:
-//
-//      f * 2^e = ( (f div 2^-e) * 2^-e + (f mod 2^-e) ) * 2^e
-//              = (f div 2^-e) + (f mod 2^-e) * 2^e
-//              = p1 + p2 * 2^e
-//
-// The conversion of p1 into decimal form requires a series of divisions and
-// modulos by (a power of) 10. These operations are faster for 32-bit than for
-// 64-bit integers, so p1 should ideally fit into a 32-bit integer. This can be
-// achieved by choosing
-//
-//      -e >= 32   or   e <= -32 := gamma
-//
-// In order to convert the fractional part
-//
-//      p2 * 2^e = p2 / 2^-e = d[-1] / 10^1 + d[-2] / 10^2 + ...
-//
-// into decimal form, the fraction is repeatedly multiplied by 10 and the digits
-// d[-i] are extracted in order:
-//
-//      (10 * p2) div 2^-e = d[-1]
-//      (10 * p2) mod 2^-e = d[-2] / 10^1 + ...
-//
-// The multiplication by 10 must not overflow. It is sufficient to choose
-//
-//      10 * p2 < 16 * p2 = 2^4 * p2 <= 2^64.
-//
-// Since p2 = f mod 2^-e < 2^-e,
-//
-//      -e <= 60   or   e >= -60 := alpha
-
-constexpr int kAlpha = -60;
-constexpr int kGamma = -32;
-
-struct cached_power // c = f * 2^e ~= 10^k
-{
-    std::uint64_t f;
-    int e;
-    int k;
-};
-
-/*!
-For a normalized diyfp w = f * 2^e, this function returns a (normalized) cached
-power-of-ten c = f_c * 2^e_c, such that the exponent of the product w * c
-satisfies (Definition 3.2 from [1])
-
-     alpha <= e_c + e + q <= gamma.
-*/
-inline cached_power get_cached_power_for_binary_exponent(int e)
-{
-    // Now
-    //
-    //      alpha <= e_c + e + q <= gamma                                    (1)
-    //      ==> f_c * 2^alpha <= c * 2^e * 2^q
-    //
-    // and since the c's are normalized, 2^(q-1) <= f_c,
-    //
-    //      ==> 2^(q - 1 + alpha) <= c * 2^(e + q)
-    //      ==> 2^(alpha - e - 1) <= c
-    //
-    // If c were an exact power of ten, i.e. c = 10^k, one may determine k as
-    //
-    //      k = ceil( log_10( 2^(alpha - e - 1) ) )
-    //        = ceil( (alpha - e - 1) * log_10(2) )
-    //
-    // From the paper:
-    // "In theory the result of the procedure could be wrong since c is rounded,
-    //  and the computation itself is approximated [...]. In practice, however,
-    //  this simple function is sufficient."
-    //
-    // For IEEE double precision floating-point numbers converted into
-    // normalized diyfp's w = f * 2^e, with q = 64,
-    //
-    //      e >= -1022      (min IEEE exponent)
-    //           -52        (p - 1)
-    //           -52        (p - 1, possibly normalize denormal IEEE numbers)
-    //           -11        (normalize the diyfp)
-    //         = -1137
-    //
-    // and
-    //
-    //      e <= +1023      (max IEEE exponent)
-    //           -52        (p - 1)
-    //           -11        (normalize the diyfp)
-    //         = 960
-    //
-    // This binary exponent range [-1137,960] results in a decimal exponent
-    // range [-307,324]. One does not need to store a cached power for each
-    // k in this range. For each such k it suffices to find a cached power
-    // such that the exponent of the product lies in [alpha,gamma].
-    // This implies that the difference of the decimal exponents of adjacent
-    // table entries must be less than or equal to
-    //
-    //      floor( (gamma - alpha) * log_10(2) ) = 8.
-    //
-    // (A smaller distance gamma-alpha would require a larger table.)
-
-    // NB:
-    // Actually this function returns c, such that -60 <= e_c + e + 64 <= -34.
-
-    constexpr int kCachedPowersMinDecExp = -300;
-    constexpr int kCachedPowersDecStep = 8;
-
-    static constexpr std::array<cached_power, 79> kCachedPowers =
-    {
-        {
-            { 0xAB70FE17C79AC6CA, -1060, -300 },
-            { 0xFF77B1FCBEBCDC4F, -1034, -292 },
-            { 0xBE5691EF416BD60C, -1007, -284 },
-            { 0x8DD01FAD907FFC3C,  -980, -276 },
-            { 0xD3515C2831559A83,  -954, -268 },
-            { 0x9D71AC8FADA6C9B5,  -927, -260 },
-            { 0xEA9C227723EE8BCB,  -901, -252 },
-            { 0xAECC49914078536D,  -874, -244 },
-            { 0x823C12795DB6CE57,  -847, -236 },
-            { 0xC21094364DFB5637,  -821, -228 },
-            { 0x9096EA6F3848984F,  -794, -220 },
-            { 0xD77485CB25823AC7,  -768, -212 },
-            { 0xA086CFCD97BF97F4,  -741, -204 },
-            { 0xEF340A98172AACE5,  -715, -196 },
-            { 0xB23867FB2A35B28E,  -688, -188 },
-            { 0x84C8D4DFD2C63F3B,  -661, -180 },
-            { 0xC5DD44271AD3CDBA,  -635, -172 },
-            { 0x936B9FCEBB25C996,  -608, -164 },
-            { 0xDBAC6C247D62A584,  -582, -156 },
-            { 0xA3AB66580D5FDAF6,  -555, -148 },
-            { 0xF3E2F893DEC3F126,  -529, -140 },
-            { 0xB5B5ADA8AAFF80B8,  -502, -132 },
-            { 0x87625F056C7C4A8B,  -475, -124 },
-            { 0xC9BCFF6034C13053,  -449, -116 },
-            { 0x964E858C91BA2655,  -422, -108 },
-            { 0xDFF9772470297EBD,  -396, -100 },
-            { 0xA6DFBD9FB8E5B88F,  -369,  -92 },
-            { 0xF8A95FCF88747D94,  -343,  -84 },
-            { 0xB94470938FA89BCF,  -316,  -76 },
-            { 0x8A08F0F8BF0F156B,  -289,  -68 },
-            { 0xCDB02555653131B6,  -263,  -60 },
-            { 0x993FE2C6D07B7FAC,  -236,  -52 },
-            { 0xE45C10C42A2B3B06,  -210,  -44 },
-            { 0xAA242499697392D3,  -183,  -36 },
-            { 0xFD87B5F28300CA0E,  -157,  -28 },
-            { 0xBCE5086492111AEB,  -130,  -20 },
-            { 0x8CBCCC096F5088CC,  -103,  -12 },
-            { 0xD1B71758E219652C,   -77,   -4 },
-            { 0x9C40000000000000,   -50,    4 },
-            { 0xE8D4A51000000000,   -24,   12 },
-            { 0xAD78EBC5AC620000,     3,   20 },
-            { 0x813F3978F8940984,    30,   28 },
-            { 0xC097CE7BC90715B3,    56,   36 },
-            { 0x8F7E32CE7BEA5C70,    83,   44 },
-            { 0xD5D238A4ABE98068,   109,   52 },
-            { 0x9F4F2726179A2245,   136,   60 },
-            { 0xED63A231D4C4FB27,   162,   68 },
-            { 0xB0DE65388CC8ADA8,   189,   76 },
-            { 0x83C7088E1AAB65DB,   216,   84 },
-            { 0xC45D1DF942711D9A,   242,   92 },
-            { 0x924D692CA61BE758,   269,  100 },
-            { 0xDA01EE641A708DEA,   295,  108 },
-            { 0xA26DA3999AEF774A,   322,  116 },
-            { 0xF209787BB47D6B85,   348,  124 },
-            { 0xB454E4A179DD1877,   375,  132 },
-            { 0x865B86925B9BC5C2,   402,  140 },
-            { 0xC83553C5C8965D3D,   428,  148 },
-            { 0x952AB45CFA97A0B3,   455,  156 },
-            { 0xDE469FBD99A05FE3,   481,  164 },
-            { 0xA59BC234DB398C25,   508,  172 },
-            { 0xF6C69A72A3989F5C,   534,  180 },
-            { 0xB7DCBF5354E9BECE,   561,  188 },
-            { 0x88FCF317F22241E2,   588,  196 },
-            { 0xCC20CE9BD35C78A5,   614,  204 },
-            { 0x98165AF37B2153DF,   641,  212 },
-            { 0xE2A0B5DC971F303A,   667,  220 },
-            { 0xA8D9D1535CE3B396,   694,  228 },
-            { 0xFB9B7CD9A4A7443C,   720,  236 },
-            { 0xBB764C4CA7A44410,   747,  244 },
-            { 0x8BAB8EEFB6409C1A,   774,  252 },
-            { 0xD01FEF10A657842C,   800,  260 },
-            { 0x9B10A4E5E9913129,   827,  268 },
-            { 0xE7109BFBA19C0C9D,   853,  276 },
-            { 0xAC2820D9623BF429,   880,  284 },
-            { 0x80444B5E7AA7CF85,   907,  292 },
-            { 0xBF21E44003ACDD2D,   933,  300 },
-            { 0x8E679C2F5E44FF8F,   960,  308 },
-            { 0xD433179D9C8CB841,   986,  316 },
-            { 0x9E19DB92B4E31BA9,  1013,  324 },
-        }
-    };
-
-    // This computation gives exactly the same results for k as
-    //      k = ceil((kAlpha - e - 1) * 0.30102999566398114)
-    // for |e| <= 1500, but doesn't require floating-point operations.
-    // NB: log_10(2) ~= 78913 / 2^18
-    JSON_ASSERT(e >= -1500);
-    JSON_ASSERT(e <=  1500);
-    const int f = kAlpha - e - 1;
-    const int k = (f * 78913) / (1 << 18) + static_cast<int>(f > 0);
-
-    const int index = (-kCachedPowersMinDecExp + k + (kCachedPowersDecStep - 1)) / kCachedPowersDecStep;
-    JSON_ASSERT(index >= 0);
-    JSON_ASSERT(static_cast<std::size_t>(index) < kCachedPowers.size());
-
-    const cached_power cached = kCachedPowers[static_cast<std::size_t>(index)];
-    JSON_ASSERT(kAlpha <= cached.e + e + 64);
-    JSON_ASSERT(kGamma >= cached.e + e + 64);
-
-    return cached;
-}
-
-/*!
-For n != 0, returns k, such that pow10 := 10^(k-1) <= n < 10^k.
-For n == 0, returns 1 and sets pow10 := 1.
-*/
-inline int find_largest_pow10(const std::uint32_t n, std::uint32_t& pow10)
-{
-    // LCOV_EXCL_START
-    if (n >= 1000000000)
-    {
-        pow10 = 1000000000;
-        return 10;
-    }
-    // LCOV_EXCL_STOP
-    else if (n >= 100000000)
-    {
-        pow10 = 100000000;
-        return  9;
-    }
-    else if (n >= 10000000)
-    {
-        pow10 = 10000000;
-        return  8;
-    }
-    else if (n >= 1000000)
-    {
-        pow10 = 1000000;
-        return  7;
-    }
-    else if (n >= 100000)
-    {
-        pow10 = 100000;
-        return  6;
-    }
-    else if (n >= 10000)
-    {
-        pow10 = 10000;
-        return  5;
-    }
-    else if (n >= 1000)
-    {
-        pow10 = 1000;
-        return  4;
-    }
-    else if (n >= 100)
-    {
-        pow10 = 100;
-        return  3;
-    }
-    else if (n >= 10)
-    {
-        pow10 = 10;
-        return  2;
-    }
-    else
-    {
-        pow10 = 1;
-        return 1;
-    }
-}
-
-inline void grisu2_round(char* buf, int len, std::uint64_t dist, std::uint64_t delta,
-                         std::uint64_t rest, std::uint64_t ten_k)
-{
-    JSON_ASSERT(len >= 1);
-    JSON_ASSERT(dist <= delta);
-    JSON_ASSERT(rest <= delta);
-    JSON_ASSERT(ten_k > 0);
-
-    //               <--------------------------- delta ---->
-    //                                  <---- dist --------->
-    // --------------[------------------+-------------------]--------------
-    //               M-                 w                   M+
-    //
-    //                                  ten_k
-    //                                <------>
-    //                                       <---- rest ---->
-    // --------------[------------------+----+--------------]--------------
-    //                                  w    V
-    //                                       = buf * 10^k
-    //
-    // ten_k represents a unit-in-the-last-place in the decimal representation
-    // stored in buf.
-    // Decrement buf by ten_k while this takes buf closer to w.
-
-    // The tests are written in this order to avoid overflow in unsigned
-    // integer arithmetic.
-
-    while (rest < dist
-            && delta - rest >= ten_k
-            && (rest + ten_k < dist || dist - rest > rest + ten_k - dist))
-    {
-        JSON_ASSERT(buf[len - 1] != '0');
-        buf[len - 1]--;
-        rest += ten_k;
-    }
-}
-
-/*!
-Generates V = buffer * 10^decimal_exponent, such that M- <= V <= M+.
-M- and M+ must be normalized and share the same exponent -60 <= e <= -32.
-*/
-inline void grisu2_digit_gen(char* buffer, int& length, int& decimal_exponent,
-                             diyfp M_minus, diyfp w, diyfp M_plus)
-{
-    static_assert(kAlpha >= -60, "internal error");
-    static_assert(kGamma <= -32, "internal error");
-
-    // Generates the digits (and the exponent) of a decimal floating-point
-    // number V = buffer * 10^decimal_exponent in the range [M-, M+]. The diyfp's
-    // w, M- and M+ share the same exponent e, which satisfies alpha <= e <= gamma.
-    //
-    //               <--------------------------- delta ---->
-    //                                  <---- dist --------->
-    // --------------[------------------+-------------------]--------------
-    //               M-                 w                   M+
-    //
-    // Grisu2 generates the digits of M+ from left to right and stops as soon as
-    // V is in [M-,M+].
-
-    JSON_ASSERT(M_plus.e >= kAlpha);
-    JSON_ASSERT(M_plus.e <= kGamma);
-
-    std::uint64_t delta = diyfp::sub(M_plus, M_minus).f; // (significand of (M+ - M-), implicit exponent is e)
-    std::uint64_t dist  = diyfp::sub(M_plus, w      ).f; // (significand of (M+ - w ), implicit exponent is e)
-
-    // Split M+ = f * 2^e into two parts p1 and p2 (note: e < 0):
-    //
-    //      M+ = f * 2^e
-    //         = ((f div 2^-e) * 2^-e + (f mod 2^-e)) * 2^e
-    //         = ((p1        ) * 2^-e + (p2        )) * 2^e
-    //         = p1 + p2 * 2^e
-
-    const diyfp one(std::uint64_t{1} << -M_plus.e, M_plus.e);
-
-    auto p1 = static_cast<std::uint32_t>(M_plus.f >> -one.e); // p1 = f div 2^-e (Since -e >= 32, p1 fits into a 32-bit int.)
-    std::uint64_t p2 = M_plus.f & (one.f - 1);                    // p2 = f mod 2^-e
-
-    // 1)
-    //
-    // Generate the digits of the integral part p1 = d[n-1]...d[1]d[0]
-
-    JSON_ASSERT(p1 > 0);
-
-    std::uint32_t pow10;
-    const int k = find_largest_pow10(p1, pow10);
-
-    //      10^(k-1) <= p1 < 10^k, pow10 = 10^(k-1)
-    //
-    //      p1 = (p1 div 10^(k-1)) * 10^(k-1) + (p1 mod 10^(k-1))
-    //         = (d[k-1]         ) * 10^(k-1) + (p1 mod 10^(k-1))
-    //
-    //      M+ = p1                                             + p2 * 2^e
-    //         = d[k-1] * 10^(k-1) + (p1 mod 10^(k-1))          + p2 * 2^e
-    //         = d[k-1] * 10^(k-1) + ((p1 mod 10^(k-1)) * 2^-e + p2) * 2^e
-    //         = d[k-1] * 10^(k-1) + (                         rest) * 2^e
-    //
-    // Now generate the digits d[n] of p1 from left to right (n = k-1,...,0)
-    //
-    //      p1 = d[k-1]...d[n] * 10^n + d[n-1]...d[0]
-    //
-    // but stop as soon as
-    //
-    //      rest * 2^e = (d[n-1]...d[0] * 2^-e + p2) * 2^e <= delta * 2^e
-
-    int n = k;
-    while (n > 0)
-    {
-        // Invariants:
-        //      M+ = buffer * 10^n + (p1 + p2 * 2^e)    (buffer = 0 for n = k)
-        //      pow10 = 10^(n-1) <= p1 < 10^n
-        //
-        const std::uint32_t d = p1 / pow10;  // d = p1 div 10^(n-1)
-        const std::uint32_t r = p1 % pow10;  // r = p1 mod 10^(n-1)
-        //
-        //      M+ = buffer * 10^n + (d * 10^(n-1) + r) + p2 * 2^e
-        //         = (buffer * 10 + d) * 10^(n-1) + (r + p2 * 2^e)
-        //
-        JSON_ASSERT(d <= 9);
-        buffer[length++] = static_cast<char>('0' + d); // buffer := buffer * 10 + d
-        //
-        //      M+ = buffer * 10^(n-1) + (r + p2 * 2^e)
-        //
-        p1 = r;
-        n--;
-        //
-        //      M+ = buffer * 10^n + (p1 + p2 * 2^e)
-        //      pow10 = 10^n
-        //
-
-        // Now check if enough digits have been generated.
-        // Compute
-        //
-        //      p1 + p2 * 2^e = (p1 * 2^-e + p2) * 2^e = rest * 2^e
-        //
-        // Note:
-        // Since rest and delta share the same exponent e, it suffices to
-        // compare the significands.
-        const std::uint64_t rest = (std::uint64_t{p1} << -one.e) + p2;
-        if (rest <= delta)
-        {
-            // V = buffer * 10^n, with M- <= V <= M+.
-
-            decimal_exponent += n;
-
-            // We may now just stop. But instead look if the buffer could be
-            // decremented to bring V closer to w.
-            //
-            // pow10 = 10^n is now 1 ulp in the decimal representation V.
-            // The rounding procedure works with diyfp's with an implicit
-            // exponent of e.
-            //
-            //      10^n = (10^n * 2^-e) * 2^e = ulp * 2^e
-            //
-            const std::uint64_t ten_n = std::uint64_t{pow10} << -one.e;
-            grisu2_round(buffer, length, dist, delta, rest, ten_n);
-
-            return;
-        }
-
-        pow10 /= 10;
-        //
-        //      pow10 = 10^(n-1) <= p1 < 10^n
-        // Invariants restored.
-    }
-
-    // 2)
-    //
-    // The digits of the integral part have been generated:
-    //
-    //      M+ = d[k-1]...d[1]d[0] + p2 * 2^e
-    //         = buffer            + p2 * 2^e
-    //
-    // Now generate the digits of the fractional part p2 * 2^e.
-    //
-    // Note:
-    // No decimal point is generated: the exponent is adjusted instead.
-    //
-    // p2 actually represents the fraction
-    //
-    //      p2 * 2^e
-    //          = p2 / 2^-e
-    //          = d[-1] / 10^1 + d[-2] / 10^2 + ...
-    //
-    // Now generate the digits d[-m] of p1 from left to right (m = 1,2,...)
-    //
-    //      p2 * 2^e = d[-1]d[-2]...d[-m] * 10^-m
-    //                      + 10^-m * (d[-m-1] / 10^1 + d[-m-2] / 10^2 + ...)
-    //
-    // using
-    //
-    //      10^m * p2 = ((10^m * p2) div 2^-e) * 2^-e + ((10^m * p2) mod 2^-e)
-    //                = (                   d) * 2^-e + (                   r)
-    //
-    // or
-    //      10^m * p2 * 2^e = d + r * 2^e
-    //
-    // i.e.
-    //
-    //      M+ = buffer + p2 * 2^e
-    //         = buffer + 10^-m * (d + r * 2^e)
-    //         = (buffer * 10^m + d) * 10^-m + 10^-m * r * 2^e
-    //
-    // and stop as soon as 10^-m * r * 2^e <= delta * 2^e
-
-    JSON_ASSERT(p2 > delta);
-
-    int m = 0;
-    for (;;)
-    {
-        // Invariant:
-        //      M+ = buffer * 10^-m + 10^-m * (d[-m-1] / 10 + d[-m-2] / 10^2 + ...) * 2^e
-        //         = buffer * 10^-m + 10^-m * (p2                                 ) * 2^e
-        //         = buffer * 10^-m + 10^-m * (1/10 * (10 * p2)                   ) * 2^e
-        //         = buffer * 10^-m + 10^-m * (1/10 * ((10*p2 div 2^-e) * 2^-e + (10*p2 mod 2^-e)) * 2^e
-        //
-        JSON_ASSERT(p2 <= (std::numeric_limits<std::uint64_t>::max)() / 10);
-        p2 *= 10;
-        const std::uint64_t d = p2 >> -one.e;     // d = (10 * p2) div 2^-e
-        const std::uint64_t r = p2 & (one.f - 1); // r = (10 * p2) mod 2^-e
-        //
-        //      M+ = buffer * 10^-m + 10^-m * (1/10 * (d * 2^-e + r) * 2^e
-        //         = buffer * 10^-m + 10^-m * (1/10 * (d + r * 2^e))
-        //         = (buffer * 10 + d) * 10^(-m-1) + 10^(-m-1) * r * 2^e
-        //
-        JSON_ASSERT(d <= 9);
-        buffer[length++] = static_cast<char>('0' + d); // buffer := buffer * 10 + d
-        //
-        //      M+ = buffer * 10^(-m-1) + 10^(-m-1) * r * 2^e
-        //
-        p2 = r;
-        m++;
-        //
-        //      M+ = buffer * 10^-m + 10^-m * p2 * 2^e
-        // Invariant restored.
-
-        // Check if enough digits have been generated.
-        //
-        //      10^-m * p2 * 2^e <= delta * 2^e
-        //              p2 * 2^e <= 10^m * delta * 2^e
-        //                    p2 <= 10^m * delta
-        delta *= 10;
-        dist  *= 10;
-        if (p2 <= delta)
-        {
-            break;
-        }
-    }
-
-    // V = buffer * 10^-m, with M- <= V <= M+.
-
-    decimal_exponent -= m;
-
-    // 1 ulp in the decimal representation is now 10^-m.
-    // Since delta and dist are now scaled by 10^m, we need to do the
-    // same with ulp in order to keep the units in sync.
-    //
-    //      10^m * 10^-m = 1 = 2^-e * 2^e = ten_m * 2^e
-    //
-    const std::uint64_t ten_m = one.f;
-    grisu2_round(buffer, length, dist, delta, p2, ten_m);
-
-    // By construction this algorithm generates the shortest possible decimal
-    // number (Loitsch, Theorem 6.2) which rounds back to w.
-    // For an input number of precision p, at least
-    //
-    //      N = 1 + ceil(p * log_10(2))
-    //
-    // decimal digits are sufficient to identify all binary floating-point
-    // numbers (Matula, "In-and-Out conversions").
-    // This implies that the algorithm does not produce more than N decimal
-    // digits.
-    //
-    //      N = 17 for p = 53 (IEEE double precision)
-    //      N = 9  for p = 24 (IEEE single precision)
-}
-
-/*!
-v = buf * 10^decimal_exponent
-len is the length of the buffer (number of decimal digits)
-The buffer must be large enough, i.e. >= max_digits10.
-*/
-JSON_HEDLEY_NON_NULL(1)
-inline void grisu2(char* buf, int& len, int& decimal_exponent,
-                   diyfp m_minus, diyfp v, diyfp m_plus)
-{
-    JSON_ASSERT(m_plus.e == m_minus.e);
-    JSON_ASSERT(m_plus.e == v.e);
-
-    //  --------(-----------------------+-----------------------)--------    (A)
-    //          m-                      v                       m+
-    //
-    //  --------------------(-----------+-----------------------)--------    (B)
-    //                      m-          v                       m+
-    //
-    // First scale v (and m- and m+) such that the exponent is in the range
-    // [alpha, gamma].
-
-    const cached_power cached = get_cached_power_for_binary_exponent(m_plus.e);
-
-    const diyfp c_minus_k(cached.f, cached.e); // = c ~= 10^-k
-
-    // The exponent of the products is = v.e + c_minus_k.e + q and is in the range [alpha,gamma]
-    const diyfp w       = diyfp::mul(v,       c_minus_k);
-    const diyfp w_minus = diyfp::mul(m_minus, c_minus_k);
-    const diyfp w_plus  = diyfp::mul(m_plus,  c_minus_k);
-
-    //  ----(---+---)---------------(---+---)---------------(---+---)----
-    //          w-                      w                       w+
-    //          = c*m-                  = c*v                   = c*m+
-    //
-    // diyfp::mul rounds its result and c_minus_k is approximated too. w, w- and
-    // w+ are now off by a small amount.
-    // In fact:
-    //
-    //      w - v * 10^k < 1 ulp
-    //
-    // To account for this inaccuracy, add resp. subtract 1 ulp.
-    //
-    //  --------+---[---------------(---+---)---------------]---+--------
-    //          w-  M-                  w                   M+  w+
-    //
-    // Now any number in [M-, M+] (bounds included) will round to w when input,
-    // regardless of how the input rounding algorithm breaks ties.
-    //
-    // And digit_gen generates the shortest possible such number in [M-, M+].
-    // Note that this does not mean that Grisu2 always generates the shortest
-    // possible number in the interval (m-, m+).
-    const diyfp M_minus(w_minus.f + 1, w_minus.e);
-    const diyfp M_plus (w_plus.f  - 1, w_plus.e );
-
-    decimal_exponent = -cached.k; // = -(-k) = k
-
-    grisu2_digit_gen(buf, len, decimal_exponent, M_minus, w, M_plus);
-}
-
-/*!
-v = buf * 10^decimal_exponent
-len is the length of the buffer (number of decimal digits)
-The buffer must be large enough, i.e. >= max_digits10.
-*/
-template<typename FloatType>
-JSON_HEDLEY_NON_NULL(1)
-void grisu2(char* buf, int& len, int& decimal_exponent, FloatType value)
-{
-    static_assert(diyfp::kPrecision >= std::numeric_limits<FloatType>::digits + 3,
-                  "internal error: not enough precision");
-
-    JSON_ASSERT(std::isfinite(value));
-    JSON_ASSERT(value > 0);
-
-    // If the neighbors (and boundaries) of 'value' are always computed for double-precision
-    // numbers, all float's can be recovered using strtod (and strtof). However, the resulting
-    // decimal representations are not exactly "short".
-    //
-    // The documentation for 'std::to_chars' (https://en.cppreference.com/w/cpp/utility/to_chars)
-    // says "value is converted to a string as if by std::sprintf in the default ("C") locale"
-    // and since sprintf promotes float's to double's, I think this is exactly what 'std::to_chars'
-    // does.
-    // On the other hand, the documentation for 'std::to_chars' requires that "parsing the
-    // representation using the corresponding std::from_chars function recovers value exactly". That
-    // indicates that single precision floating-point numbers should be recovered using
-    // 'std::strtof'.
-    //
-    // NB: If the neighbors are computed for single-precision numbers, there is a single float
-    //     (7.0385307e-26f) which can't be recovered using strtod. The resulting double precision
-    //     value is off by 1 ulp.
-#if 0
-    const boundaries w = compute_boundaries(static_cast<double>(value));
-#else
-    const boundaries w = compute_boundaries(value);
-#endif
-
-    grisu2(buf, len, decimal_exponent, w.minus, w.w, w.plus);
-}
-
-/*!
-@brief appends a decimal representation of e to buf
-@return a pointer to the element following the exponent.
-@pre -1000 < e < 1000
-*/
-JSON_HEDLEY_NON_NULL(1)
-JSON_HEDLEY_RETURNS_NON_NULL
-inline char* append_exponent(char* buf, int e)
-{
-    JSON_ASSERT(e > -1000);
-    JSON_ASSERT(e <  1000);
-
-    if (e < 0)
-    {
-        e = -e;
-        *buf++ = '-';
-    }
-    else
-    {
-        *buf++ = '+';
-    }
-
-    auto k = static_cast<std::uint32_t>(e);
-    if (k < 10)
-    {
-        // Always print at least two digits in the exponent.
-        // This is for compatibility with printf("%g").
-        *buf++ = '0';
-        *buf++ = static_cast<char>('0' + k);
-    }
-    else if (k < 100)
-    {
-        *buf++ = static_cast<char>('0' + k / 10);
-        k %= 10;
-        *buf++ = static_cast<char>('0' + k);
-    }
-    else
-    {
-        *buf++ = static_cast<char>('0' + k / 100);
-        k %= 100;
-        *buf++ = static_cast<char>('0' + k / 10);
-        k %= 10;
-        *buf++ = static_cast<char>('0' + k);
-    }
-
-    return buf;
-}
-
-/*!
-@brief prettify v = buf * 10^decimal_exponent
-
-If v is in the range [10^min_exp, 10^max_exp) it will be printed in fixed-point
-notation. Otherwise it will be printed in exponential notation.
-
-@pre min_exp < 0
-@pre max_exp > 0
-*/
-JSON_HEDLEY_NON_NULL(1)
-JSON_HEDLEY_RETURNS_NON_NULL
-inline char* format_buffer(char* buf, int len, int decimal_exponent,
-                           int min_exp, int max_exp)
-{
-    JSON_ASSERT(min_exp < 0);
-    JSON_ASSERT(max_exp > 0);
-
-    const int k = len;
-    const int n = len + decimal_exponent;
-
-    // v = buf * 10^(n-k)
-    // k is the length of the buffer (number of decimal digits)
-    // n is the position of the decimal point relative to the start of the buffer.
-
-    if (k <= n && n <= max_exp)
-    {
-        // digits[000]
-        // len <= max_exp + 2
-
-        std::memset(buf + k, '0', static_cast<size_t>(n) - static_cast<size_t>(k));
-        // Make it look like a floating-point number (#362, #378)
-        buf[n + 0] = '.';
-        buf[n + 1] = '0';
-        return buf + (static_cast<size_t>(n) + 2);
-    }
-
-    if (0 < n && n <= max_exp)
-    {
-        // dig.its
-        // len <= max_digits10 + 1
-
-        JSON_ASSERT(k > n);
-
-        std::memmove(buf + (static_cast<size_t>(n) + 1), buf + n, static_cast<size_t>(k) - static_cast<size_t>(n));
-        buf[n] = '.';
-        return buf + (static_cast<size_t>(k) + 1U);
-    }
-
-    if (min_exp < n && n <= 0)
-    {
-        // 0.[000]digits
-        // len <= 2 + (-min_exp - 1) + max_digits10
-
-        std::memmove(buf + (2 + static_cast<size_t>(-n)), buf, static_cast<size_t>(k));
-        buf[0] = '0';
-        buf[1] = '.';
-        std::memset(buf + 2, '0', static_cast<size_t>(-n));
-        return buf + (2U + static_cast<size_t>(-n) + static_cast<size_t>(k));
-    }
-
-    if (k == 1)
-    {
-        // dE+123
-        // len <= 1 + 5
-
-        buf += 1;
-    }
-    else
-    {
-        // d.igitsE+123
-        // len <= max_digits10 + 1 + 5
-
-        std::memmove(buf + 2, buf + 1, static_cast<size_t>(k) - 1);
-        buf[1] = '.';
-        buf += 1 + static_cast<size_t>(k);
-    }
-
-    *buf++ = 'e';
-    return append_exponent(buf, n - 1);
-}
-
-} // namespace dtoa_impl
-
-/*!
-@brief generates a decimal representation of the floating-point number value in [first, last).
-
-The format of the resulting decimal representation is similar to printf's %g
-format. Returns an iterator pointing past-the-end of the decimal representation.
-
-@note The input number must be finite, i.e. NaN's and Inf's are not supported.
-@note The buffer must be large enough.
-@note The result is NOT null-terminated.
-*/
-template<typename FloatType>
-JSON_HEDLEY_NON_NULL(1, 2)
-JSON_HEDLEY_RETURNS_NON_NULL
-char* to_chars(char* first, const char* last, FloatType value)
-{
-    static_cast<void>(last); // maybe unused - fix warning
-    JSON_ASSERT(std::isfinite(value));
-
-    // Use signbit(value) instead of (value < 0) since signbit works for -0.
-    if (std::signbit(value))
-    {
-        value = -value;
-        *first++ = '-';
-    }
-
-    if (value == 0) // +-0
-    {
-        *first++ = '0';
-        // Make it look like a floating-point number (#362, #378)
-        *first++ = '.';
-        *first++ = '0';
-        return first;
-    }
-
-    JSON_ASSERT(last - first >= std::numeric_limits<FloatType>::max_digits10);
-
-    // Compute v = buffer * 10^decimal_exponent.
-    // The decimal digits are stored in the buffer, which needs to be interpreted
-    // as an unsigned decimal integer.
-    // len is the length of the buffer, i.e. the number of decimal digits.
-    int len = 0;
-    int decimal_exponent = 0;
-    dtoa_impl::grisu2(first, len, decimal_exponent, value);
-
-    JSON_ASSERT(len <= std::numeric_limits<FloatType>::max_digits10);
-
-    // Format the buffer like printf("%.*g", prec, value)
-    constexpr int kMinExp = -4;
-    // Use digits10 here to increase compatibility with version 2.
-    constexpr int kMaxExp = std::numeric_limits<FloatType>::digits10;
-
-    JSON_ASSERT(last - first >= kMaxExp + 2);
-    JSON_ASSERT(last - first >= 2 + (-kMinExp - 1) + std::numeric_limits<FloatType>::max_digits10);
-    JSON_ASSERT(last - first >= std::numeric_limits<FloatType>::max_digits10 + 6);
-
-    return dtoa_impl::format_buffer(first, len, decimal_exponent, kMinExp, kMaxExp);
-}
-
-} // namespace detail
-} // namespace nlohmann
-
-// #include <nlohmann/detail/exceptions.hpp>
-
-// #include <nlohmann/detail/macro_scope.hpp>
-
-// #include <nlohmann/detail/meta/cpp_future.hpp>
-
-// #include <nlohmann/detail/output/binary_writer.hpp>
-
-// #include <nlohmann/detail/output/output_adapters.hpp>
-
-// #include <nlohmann/detail/value_t.hpp>
-
-
-namespace nlohmann
-{
-namespace detail
-{
-///////////////////
-// serialization //
-///////////////////
-
-/// how to treat decoding errors
-enum class error_handler_t
-{
-    strict,  ///< throw a type_error exception in case of invalid UTF-8
-    replace, ///< replace invalid UTF-8 sequences with U+FFFD
-    ignore   ///< ignore invalid UTF-8 sequences
-};
-
-template<typename BasicJsonType>
-class serializer
-{
-    using string_t = typename BasicJsonType::string_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using binary_char_t = typename BasicJsonType::binary_t::value_type;
-    static constexpr std::uint8_t UTF8_ACCEPT = 0;
-    static constexpr std::uint8_t UTF8_REJECT = 1;
-
-  public:
-    /*!
-    @param[in] s  output stream to serialize to
-    @param[in] ichar  indentation character to use
-    @param[in] error_handler_  how to react on decoding errors
-    */
-    serializer(output_adapter_t<char> s, const char ichar,
-               error_handler_t error_handler_ = error_handler_t::strict)
-        : o(std::move(s))
-        , loc(std::localeconv())
-        , thousands_sep(loc->thousands_sep == nullptr ? '\0' : std::char_traits<char>::to_char_type(* (loc->thousands_sep)))
-        , decimal_point(loc->decimal_point == nullptr ? '\0' : std::char_traits<char>::to_char_type(* (loc->decimal_point)))
-        , indent_char(ichar)
-        , indent_string(512, indent_char)
-        , error_handler(error_handler_)
-    {}
-
-    // delete because of pointer members
-    serializer(const serializer&) = delete;
-    serializer& operator=(const serializer&) = delete;
-    serializer(serializer&&) = delete;
-    serializer& operator=(serializer&&) = delete;
-    ~serializer() = default;
-
-    /*!
-    @brief internal implementation of the serialization function
-
-    This function is called by the public member function dump and organizes
-    the serialization internally. The indentation level is propagated as
-    additional parameter. In case of arrays and objects, the function is
-    called recursively.
-
-    - strings and object keys are escaped using `escape_string()`
-    - integer numbers are converted implicitly via `operator<<`
-    - floating-point numbers are converted to a string using `"%g"` format
-    - binary values are serialized as objects containing the subtype and the
-      byte array
-
-    @param[in] val               value to serialize
-    @param[in] pretty_print      whether the output shall be pretty-printed
-    @param[in] ensure_ascii If @a ensure_ascii is true, all non-ASCII characters
-    in the output are escaped with `\uXXXX` sequences, and the result consists
-    of ASCII characters only.
-    @param[in] indent_step       the indent level
-    @param[in] current_indent    the current indent level (only used internally)
-    */
-    void dump(const BasicJsonType& val,
-              const bool pretty_print,
-              const bool ensure_ascii,
-              const unsigned int indent_step,
-              const unsigned int current_indent = 0)
-    {
-        switch (val.m_type)
-        {
-            case value_t::object:
-            {
-                if (val.m_value.object->empty())
-                {
-                    o->write_characters("{}", 2);
-                    return;
-                }
-
-                if (pretty_print)
-                {
-                    o->write_characters("{\n", 2);
-
-                    // variable to hold indentation for recursive calls
-                    const auto new_indent = current_indent + indent_step;
-                    if (JSON_HEDLEY_UNLIKELY(indent_string.size() < new_indent))
-                    {
-                        indent_string.resize(indent_string.size() * 2, ' ');
-                    }
-
-                    // first n-1 elements
-                    auto i = val.m_value.object->cbegin();
-                    for (std::size_t cnt = 0; cnt < val.m_value.object->size() - 1; ++cnt, ++i)
-                    {
-                        o->write_characters(indent_string.c_str(), new_indent);
-                        o->write_character('\"');
-                        dump_escaped(i->first, ensure_ascii);
-                        o->write_characters("\": ", 3);
-                        dump(i->second, true, ensure_ascii, indent_step, new_indent);
-                        o->write_characters(",\n", 2);
-                    }
-
-                    // last element
-                    JSON_ASSERT(i != val.m_value.object->cend());
-                    JSON_ASSERT(std::next(i) == val.m_value.object->cend());
-                    o->write_characters(indent_string.c_str(), new_indent);
-                    o->write_character('\"');
-                    dump_escaped(i->first, ensure_ascii);
-                    o->write_characters("\": ", 3);
-                    dump(i->second, true, ensure_ascii, indent_step, new_indent);
-
-                    o->write_character('\n');
-                    o->write_characters(indent_string.c_str(), current_indent);
-                    o->write_character('}');
-                }
-                else
-                {
-                    o->write_character('{');
-
-                    // first n-1 elements
-                    auto i = val.m_value.object->cbegin();
-                    for (std::size_t cnt = 0; cnt < val.m_value.object->size() - 1; ++cnt, ++i)
-                    {
-                        o->write_character('\"');
-                        dump_escaped(i->first, ensure_ascii);
-                        o->write_characters("\":", 2);
-                        dump(i->second, false, ensure_ascii, indent_step, current_indent);
-                        o->write_character(',');
-                    }
-
-                    // last element
-                    JSON_ASSERT(i != val.m_value.object->cend());
-                    JSON_ASSERT(std::next(i) == val.m_value.object->cend());
-                    o->write_character('\"');
-                    dump_escaped(i->first, ensure_ascii);
-                    o->write_characters("\":", 2);
-                    dump(i->second, false, ensure_ascii, indent_step, current_indent);
-
-                    o->write_character('}');
-                }
-
-                return;
-            }
-
-            case value_t::array:
-            {
-                if (val.m_value.array->empty())
-                {
-                    o->write_characters("[]", 2);
-                    return;
-                }
-
-                if (pretty_print)
-                {
-                    o->write_characters("[\n", 2);
-
-                    // variable to hold indentation for recursive calls
-                    const auto new_indent = current_indent + indent_step;
-                    if (JSON_HEDLEY_UNLIKELY(indent_string.size() < new_indent))
-                    {
-                        indent_string.resize(indent_string.size() * 2, ' ');
-                    }
-
-                    // first n-1 elements
-                    for (auto i = val.m_value.array->cbegin();
-                            i != val.m_value.array->cend() - 1; ++i)
-                    {
-                        o->write_characters(indent_string.c_str(), new_indent);
-                        dump(*i, true, ensure_ascii, indent_step, new_indent);
-                        o->write_characters(",\n", 2);
-                    }
-
-                    // last element
-                    JSON_ASSERT(!val.m_value.array->empty());
-                    o->write_characters(indent_string.c_str(), new_indent);
-                    dump(val.m_value.array->back(), true, ensure_ascii, indent_step, new_indent);
-
-                    o->write_character('\n');
-                    o->write_characters(indent_string.c_str(), current_indent);
-                    o->write_character(']');
-                }
-                else
-                {
-                    o->write_character('[');
-
-                    // first n-1 elements
-                    for (auto i = val.m_value.array->cbegin();
-                            i != val.m_value.array->cend() - 1; ++i)
-                    {
-                        dump(*i, false, ensure_ascii, indent_step, current_indent);
-                        o->write_character(',');
-                    }
-
-                    // last element
-                    JSON_ASSERT(!val.m_value.array->empty());
-                    dump(val.m_value.array->back(), false, ensure_ascii, indent_step, current_indent);
-
-                    o->write_character(']');
-                }
-
-                return;
-            }
-
-            case value_t::string:
-            {
-                o->write_character('\"');
-                dump_escaped(*val.m_value.string, ensure_ascii);
-                o->write_character('\"');
-                return;
-            }
-
-            case value_t::binary:
-            {
-                if (pretty_print)
-                {
-                    o->write_characters("{\n", 2);
-
-                    // variable to hold indentation for recursive calls
-                    const auto new_indent = current_indent + indent_step;
-                    if (JSON_HEDLEY_UNLIKELY(indent_string.size() < new_indent))
-                    {
-                        indent_string.resize(indent_string.size() * 2, ' ');
-                    }
-
-                    o->write_characters(indent_string.c_str(), new_indent);
-
-                    o->write_characters("\"bytes\": [", 10);
-
-                    if (!val.m_value.binary->empty())
-                    {
-                        for (auto i = val.m_value.binary->cbegin();
-                                i != val.m_value.binary->cend() - 1; ++i)
-                        {
-                            dump_integer(*i);
-                            o->write_characters(", ", 2);
-                        }
-                        dump_integer(val.m_value.binary->back());
-                    }
-
-                    o->write_characters("],\n", 3);
-                    o->write_characters(indent_string.c_str(), new_indent);
-
-                    o->write_characters("\"subtype\": ", 11);
-                    if (val.m_value.binary->has_subtype())
-                    {
-                        dump_integer(val.m_value.binary->subtype());
-                    }
-                    else
-                    {
-                        o->write_characters("null", 4);
-                    }
-                    o->write_character('\n');
-                    o->write_characters(indent_string.c_str(), current_indent);
-                    o->write_character('}');
-                }
-                else
-                {
-                    o->write_characters("{\"bytes\":[", 10);
-
-                    if (!val.m_value.binary->empty())
-                    {
-                        for (auto i = val.m_value.binary->cbegin();
-                                i != val.m_value.binary->cend() - 1; ++i)
-                        {
-                            dump_integer(*i);
-                            o->write_character(',');
-                        }
-                        dump_integer(val.m_value.binary->back());
-                    }
-
-                    o->write_characters("],\"subtype\":", 12);
-                    if (val.m_value.binary->has_subtype())
-                    {
-                        dump_integer(val.m_value.binary->subtype());
-                        o->write_character('}');
-                    }
-                    else
-                    {
-                        o->write_characters("null}", 5);
-                    }
-                }
-                return;
-            }
-
-            case value_t::boolean:
-            {
-                if (val.m_value.boolean)
-                {
-                    o->write_characters("true", 4);
-                }
-                else
-                {
-                    o->write_characters("false", 5);
-                }
-                return;
-            }
-
-            case value_t::number_integer:
-            {
-                dump_integer(val.m_value.number_integer);
-                return;
-            }
-
-            case value_t::number_unsigned:
-            {
-                dump_integer(val.m_value.number_unsigned);
-                return;
-            }
-
-            case value_t::number_float:
-            {
-                dump_float(val.m_value.number_float);
-                return;
-            }
-
-            case value_t::discarded:
-            {
-                o->write_characters("<discarded>", 11);
-                return;
-            }
-
-            case value_t::null:
-            {
-                o->write_characters("null", 4);
-                return;
-            }
-
-            default:            // LCOV_EXCL_LINE
-                JSON_ASSERT(false);  // LCOV_EXCL_LINE
-        }
-    }
-
-  private:
-    /*!
-    @brief dump escaped string
-
-    Escape a string by replacing certain special characters by a sequence of an
-    escape character (backslash) and another character and other control
-    characters by a sequence of "\u" followed by a four-digit hex
-    representation. The escaped string is written to output stream @a o.
-
-    @param[in] s  the string to escape
-    @param[in] ensure_ascii  whether to escape non-ASCII characters with
-                             \uXXXX sequences
-
-    @complexity Linear in the length of string @a s.
-    */
-    void dump_escaped(const string_t& s, const bool ensure_ascii)
-    {
-        std::uint32_t codepoint;
-        std::uint8_t state = UTF8_ACCEPT;
-        std::size_t bytes = 0;  // number of bytes written to string_buffer
-
-        // number of bytes written at the point of the last valid byte
-        std::size_t bytes_after_last_accept = 0;
-        std::size_t undumped_chars = 0;
-
-        for (std::size_t i = 0; i < s.size(); ++i)
-        {
-            const auto byte = static_cast<uint8_t>(s[i]);
-
-            switch (decode(state, codepoint, byte))
-            {
-                case UTF8_ACCEPT:  // decode found a new code point
-                {
-                    switch (codepoint)
-                    {
-                        case 0x08: // backspace
-                        {
-                            string_buffer[bytes++] = '\\';
-                            string_buffer[bytes++] = 'b';
-                            break;
-                        }
-
-                        case 0x09: // horizontal tab
-                        {
-                            string_buffer[bytes++] = '\\';
-                            string_buffer[bytes++] = 't';
-                            break;
-                        }
-
-                        case 0x0A: // newline
-                        {
-                            string_buffer[bytes++] = '\\';
-                            string_buffer[bytes++] = 'n';
-                            break;
-                        }
-
-                        case 0x0C: // formfeed
-                        {
-                            string_buffer[bytes++] = '\\';
-                            string_buffer[bytes++] = 'f';
-                            break;
-                        }
-
-                        case 0x0D: // carriage return
-                        {
-                            string_buffer[bytes++] = '\\';
-                            string_buffer[bytes++] = 'r';
-                            break;
-                        }
-
-                        case 0x22: // quotation mark
-                        {
-                            string_buffer[bytes++] = '\\';
-                            string_buffer[bytes++] = '\"';
-                            break;
-                        }
-
-                        case 0x5C: // reverse solidus
-                        {
-                            string_buffer[bytes++] = '\\';
-                            string_buffer[bytes++] = '\\';
-                            break;
-                        }
-
-                        default:
-                        {
-                            // escape control characters (0x00..0x1F) or, if
-                            // ensure_ascii parameter is used, non-ASCII characters
-                            if ((codepoint <= 0x1F) || (ensure_ascii && (codepoint >= 0x7F)))
-                            {
-                                if (codepoint <= 0xFFFF)
-                                {
-                                    (std::snprintf)(string_buffer.data() + bytes, 7, "\\u%04x",
-                                                    static_cast<std::uint16_t>(codepoint));
-                                    bytes += 6;
-                                }
-                                else
-                                {
-                                    (std::snprintf)(string_buffer.data() + bytes, 13, "\\u%04x\\u%04x",
-                                                    static_cast<std::uint16_t>(0xD7C0u + (codepoint >> 10u)),
-                                                    static_cast<std::uint16_t>(0xDC00u + (codepoint & 0x3FFu)));
-                                    bytes += 12;
-                                }
-                            }
-                            else
-                            {
-                                // copy byte to buffer (all previous bytes
-                                // been copied have in default case above)
-                                string_buffer[bytes++] = s[i];
-                            }
-                            break;
-                        }
-                    }
-
-                    // write buffer and reset index; there must be 13 bytes
-                    // left, as this is the maximal number of bytes to be
-                    // written ("\uxxxx\uxxxx\0") for one code point
-                    if (string_buffer.size() - bytes < 13)
-                    {
-                        o->write_characters(string_buffer.data(), bytes);
-                        bytes = 0;
-                    }
-
-                    // remember the byte position of this accept
-                    bytes_after_last_accept = bytes;
-                    undumped_chars = 0;
-                    break;
-                }
-
-                case UTF8_REJECT:  // decode found invalid UTF-8 byte
-                {
-                    switch (error_handler)
-                    {
-                        case error_handler_t::strict:
-                        {
-                            std::string sn(3, '\0');
-                            (std::snprintf)(&sn[0], sn.size(), "%.2X", byte);
-                            JSON_THROW(type_error::create(316, "invalid UTF-8 byte at index " + std::to_string(i) + ": 0x" + sn));
-                        }
-
-                        case error_handler_t::ignore:
-                        case error_handler_t::replace:
-                        {
-                            // in case we saw this character the first time, we
-                            // would like to read it again, because the byte
-                            // may be OK for itself, but just not OK for the
-                            // previous sequence
-                            if (undumped_chars > 0)
-                            {
-                                --i;
-                            }
-
-                            // reset length buffer to the last accepted index;
-                            // thus removing/ignoring the invalid characters
-                            bytes = bytes_after_last_accept;
-
-                            if (error_handler == error_handler_t::replace)
-                            {
-                                // add a replacement character
-                                if (ensure_ascii)
-                                {
-                                    string_buffer[bytes++] = '\\';
-                                    string_buffer[bytes++] = 'u';
-                                    string_buffer[bytes++] = 'f';
-                                    string_buffer[bytes++] = 'f';
-                                    string_buffer[bytes++] = 'f';
-                                    string_buffer[bytes++] = 'd';
-                                }
-                                else
-                                {
-                                    string_buffer[bytes++] = detail::binary_writer<BasicJsonType, char>::to_char_type('\xEF');
-                                    string_buffer[bytes++] = detail::binary_writer<BasicJsonType, char>::to_char_type('\xBF');
-                                    string_buffer[bytes++] = detail::binary_writer<BasicJsonType, char>::to_char_type('\xBD');
-                                }
-
-                                // write buffer and reset index; there must be 13 bytes
-                                // left, as this is the maximal number of bytes to be
-                                // written ("\uxxxx\uxxxx\0") for one code point
-                                if (string_buffer.size() - bytes < 13)
-                                {
-                                    o->write_characters(string_buffer.data(), bytes);
-                                    bytes = 0;
-                                }
-
-                                bytes_after_last_accept = bytes;
-                            }
-
-                            undumped_chars = 0;
-
-                            // continue processing the string
-                            state = UTF8_ACCEPT;
-                            break;
-                        }
-
-                        default:            // LCOV_EXCL_LINE
-                            JSON_ASSERT(false);  // LCOV_EXCL_LINE
-                    }
-                    break;
-                }
-
-                default:  // decode found yet incomplete multi-byte code point
-                {
-                    if (!ensure_ascii)
-                    {
-                        // code point will not be escaped - copy byte to buffer
-                        string_buffer[bytes++] = s[i];
-                    }
-                    ++undumped_chars;
-                    break;
-                }
-            }
-        }
-
-        // we finished processing the string
-        if (JSON_HEDLEY_LIKELY(state == UTF8_ACCEPT))
-        {
-            // write buffer
-            if (bytes > 0)
-            {
-                o->write_characters(string_buffer.data(), bytes);
-            }
-        }
-        else
-        {
-            // we finish reading, but do not accept: string was incomplete
-            switch (error_handler)
-            {
-                case error_handler_t::strict:
-                {
-                    std::string sn(3, '\0');
-                    (std::snprintf)(&sn[0], sn.size(), "%.2X", static_cast<std::uint8_t>(s.back()));
-                    JSON_THROW(type_error::create(316, "incomplete UTF-8 string; last byte: 0x" + sn));
-                }
-
-                case error_handler_t::ignore:
-                {
-                    // write all accepted bytes
-                    o->write_characters(string_buffer.data(), bytes_after_last_accept);
-                    break;
-                }
-
-                case error_handler_t::replace:
-                {
-                    // write all accepted bytes
-                    o->write_characters(string_buffer.data(), bytes_after_last_accept);
-                    // add a replacement character
-                    if (ensure_ascii)
-                    {
-                        o->write_characters("\\ufffd", 6);
-                    }
-                    else
-                    {
-                        o->write_characters("\xEF\xBF\xBD", 3);
-                    }
-                    break;
-                }
-
-                default:            // LCOV_EXCL_LINE
-                    JSON_ASSERT(false);  // LCOV_EXCL_LINE
-            }
-        }
-    }
-
-    /*!
-    @brief count digits
-
-    Count the number of decimal (base 10) digits for an input unsigned integer.
-
-    @param[in] x  unsigned integer number to count its digits
-    @return    number of decimal digits
-    */
-    inline unsigned int count_digits(number_unsigned_t x) noexcept
-    {
-        unsigned int n_digits = 1;
-        for (;;)
-        {
-            if (x < 10)
-            {
-                return n_digits;
-            }
-            if (x < 100)
-            {
-                return n_digits + 1;
-            }
-            if (x < 1000)
-            {
-                return n_digits + 2;
-            }
-            if (x < 10000)
-            {
-                return n_digits + 3;
-            }
-            x = x / 10000u;
-            n_digits += 4;
-        }
-    }
-
-    /*!
-    @brief dump an integer
-
-    Dump a given integer to output stream @a o. Works internally with
-    @a number_buffer.
-
-    @param[in] x  integer number (signed or unsigned) to dump
-    @tparam NumberType either @a number_integer_t or @a number_unsigned_t
-    */
-    template < typename NumberType, detail::enable_if_t <
-                   std::is_same<NumberType, number_unsigned_t>::value ||
-                   std::is_same<NumberType, number_integer_t>::value ||
-                   std::is_same<NumberType, binary_char_t>::value,
-                   int > = 0 >
-    void dump_integer(NumberType x)
-    {
-        static constexpr std::array<std::array<char, 2>, 100> digits_to_99
-        {
-            {
-                {{'0', '0'}}, {{'0', '1'}}, {{'0', '2'}}, {{'0', '3'}}, {{'0', '4'}}, {{'0', '5'}}, {{'0', '6'}}, {{'0', '7'}}, {{'0', '8'}}, {{'0', '9'}},
-                {{'1', '0'}}, {{'1', '1'}}, {{'1', '2'}}, {{'1', '3'}}, {{'1', '4'}}, {{'1', '5'}}, {{'1', '6'}}, {{'1', '7'}}, {{'1', '8'}}, {{'1', '9'}},
-                {{'2', '0'}}, {{'2', '1'}}, {{'2', '2'}}, {{'2', '3'}}, {{'2', '4'}}, {{'2', '5'}}, {{'2', '6'}}, {{'2', '7'}}, {{'2', '8'}}, {{'2', '9'}},
-                {{'3', '0'}}, {{'3', '1'}}, {{'3', '2'}}, {{'3', '3'}}, {{'3', '4'}}, {{'3', '5'}}, {{'3', '6'}}, {{'3', '7'}}, {{'3', '8'}}, {{'3', '9'}},
-                {{'4', '0'}}, {{'4', '1'}}, {{'4', '2'}}, {{'4', '3'}}, {{'4', '4'}}, {{'4', '5'}}, {{'4', '6'}}, {{'4', '7'}}, {{'4', '8'}}, {{'4', '9'}},
-                {{'5', '0'}}, {{'5', '1'}}, {{'5', '2'}}, {{'5', '3'}}, {{'5', '4'}}, {{'5', '5'}}, {{'5', '6'}}, {{'5', '7'}}, {{'5', '8'}}, {{'5', '9'}},
-                {{'6', '0'}}, {{'6', '1'}}, {{'6', '2'}}, {{'6', '3'}}, {{'6', '4'}}, {{'6', '5'}}, {{'6', '6'}}, {{'6', '7'}}, {{'6', '8'}}, {{'6', '9'}},
-                {{'7', '0'}}, {{'7', '1'}}, {{'7', '2'}}, {{'7', '3'}}, {{'7', '4'}}, {{'7', '5'}}, {{'7', '6'}}, {{'7', '7'}}, {{'7', '8'}}, {{'7', '9'}},
-                {{'8', '0'}}, {{'8', '1'}}, {{'8', '2'}}, {{'8', '3'}}, {{'8', '4'}}, {{'8', '5'}}, {{'8', '6'}}, {{'8', '7'}}, {{'8', '8'}}, {{'8', '9'}},
-                {{'9', '0'}}, {{'9', '1'}}, {{'9', '2'}}, {{'9', '3'}}, {{'9', '4'}}, {{'9', '5'}}, {{'9', '6'}}, {{'9', '7'}}, {{'9', '8'}}, {{'9', '9'}},
-            }
-        };
-
-        // special case for "0"
-        if (x == 0)
-        {
-            o->write_character('0');
-            return;
-        }
-
-        // use a pointer to fill the buffer
-        auto buffer_ptr = number_buffer.begin();
-
-        const bool is_negative = std::is_same<NumberType, number_integer_t>::value && !(x >= 0); // see issue #755
-        number_unsigned_t abs_value;
-
-        unsigned int n_chars;
-
-        if (is_negative)
-        {
-            *buffer_ptr = '-';
-            abs_value = remove_sign(static_cast<number_integer_t>(x));
-
-            // account one more byte for the minus sign
-            n_chars = 1 + count_digits(abs_value);
-        }
-        else
-        {
-            abs_value = static_cast<number_unsigned_t>(x);
-            n_chars = count_digits(abs_value);
-        }
-
-        // spare 1 byte for '\0'
-        JSON_ASSERT(n_chars < number_buffer.size() - 1);
-
-        // jump to the end to generate the string from backward
-        // so we later avoid reversing the result
-        buffer_ptr += n_chars;
-
-        // Fast int2ascii implementation inspired by "Fastware" talk by Andrei Alexandrescu
-        // See: https://www.youtube.com/watch?v=o4-CwDo2zpg
-        while (abs_value >= 100)
-        {
-            const auto digits_index = static_cast<unsigned>((abs_value % 100));
-            abs_value /= 100;
-            *(--buffer_ptr) = digits_to_99[digits_index][1];
-            *(--buffer_ptr) = digits_to_99[digits_index][0];
-        }
-
-        if (abs_value >= 10)
-        {
-            const auto digits_index = static_cast<unsigned>(abs_value);
-            *(--buffer_ptr) = digits_to_99[digits_index][1];
-            *(--buffer_ptr) = digits_to_99[digits_index][0];
-        }
-        else
-        {
-            *(--buffer_ptr) = static_cast<char>('0' + abs_value);
-        }
-
-        o->write_characters(number_buffer.data(), n_chars);
-    }
-
-    /*!
-    @brief dump a floating-point number
-
-    Dump a given floating-point number to output stream @a o. Works internally
-    with @a number_buffer.
-
-    @param[in] x  floating-point number to dump
-    */
-    void dump_float(number_float_t x)
-    {
-        // NaN / inf
-        if (!std::isfinite(x))
-        {
-            o->write_characters("null", 4);
-            return;
-        }
-
-        // If number_float_t is an IEEE-754 single or double precision number,
-        // use the Grisu2 algorithm to produce short numbers which are
-        // guaranteed to round-trip, using strtof and strtod, resp.
-        //
-        // NB: The test below works if <long double> == <double>.
-        static constexpr bool is_ieee_single_or_double
-            = (std::numeric_limits<number_float_t>::is_iec559 && std::numeric_limits<number_float_t>::digits == 24 && std::numeric_limits<number_float_t>::max_exponent == 128) ||
-              (std::numeric_limits<number_float_t>::is_iec559 && std::numeric_limits<number_float_t>::digits == 53 && std::numeric_limits<number_float_t>::max_exponent == 1024);
-
-        dump_float(x, std::integral_constant<bool, is_ieee_single_or_double>());
-    }
-
-    void dump_float(number_float_t x, std::true_type /*is_ieee_single_or_double*/)
-    {
-        char* begin = number_buffer.data();
-        char* end = ::nlohmann::detail::to_chars(begin, begin + number_buffer.size(), x);
-
-        o->write_characters(begin, static_cast<size_t>(end - begin));
-    }
-
-    void dump_float(number_float_t x, std::false_type /*is_ieee_single_or_double*/)
-    {
-        // get number of digits for a float -> text -> float round-trip
-        static constexpr auto d = std::numeric_limits<number_float_t>::max_digits10;
-
-        // the actual conversion
-        std::ptrdiff_t len = (std::snprintf)(number_buffer.data(), number_buffer.size(), "%.*g", d, x);
-
-        // negative value indicates an error
-        JSON_ASSERT(len > 0);
-        // check if buffer was large enough
-        JSON_ASSERT(static_cast<std::size_t>(len) < number_buffer.size());
-
-        // erase thousands separator
-        if (thousands_sep != '\0')
-        {
-            const auto end = std::remove(number_buffer.begin(),
-                                         number_buffer.begin() + len, thousands_sep);
-            std::fill(end, number_buffer.end(), '\0');
-            JSON_ASSERT((end - number_buffer.begin()) <= len);
-            len = (end - number_buffer.begin());
-        }
-
-        // convert decimal point to '.'
-        if (decimal_point != '\0' && decimal_point != '.')
-        {
-            const auto dec_pos = std::find(number_buffer.begin(), number_buffer.end(), decimal_point);
-            if (dec_pos != number_buffer.end())
-            {
-                *dec_pos = '.';
-            }
-        }
-
-        o->write_characters(number_buffer.data(), static_cast<std::size_t>(len));
-
-        // determine if need to append ".0"
-        const bool value_is_int_like =
-            std::none_of(number_buffer.begin(), number_buffer.begin() + len + 1,
-                         [](char c)
-        {
-            return c == '.' || c == 'e';
-        });
-
-        if (value_is_int_like)
-        {
-            o->write_characters(".0", 2);
-        }
-    }
-
-    /*!
-    @brief check whether a string is UTF-8 encoded
-
-    The function checks each byte of a string whether it is UTF-8 encoded. The
-    result of the check is stored in the @a state parameter. The function must
-    be called initially with state 0 (accept). State 1 means the string must
-    be rejected, because the current byte is not allowed. If the string is
-    completely processed, but the state is non-zero, the string ended
-    prematurely; that is, the last byte indicated more bytes should have
-    followed.
-
-    @param[in,out] state  the state of the decoding
-    @param[in,out] codep  codepoint (valid only if resulting state is UTF8_ACCEPT)
-    @param[in] byte       next byte to decode
-    @return               new state
-
-    @note The function has been edited: a std::array is used.
-
-    @copyright Copyright (c) 2008-2009 Bjoern Hoehrmann <bjoern@hoehrmann.de>
-    @sa http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
-    */
-    static std::uint8_t decode(std::uint8_t& state, std::uint32_t& codep, const std::uint8_t byte) noexcept
-    {
-        static const std::array<std::uint8_t, 400> utf8d =
-        {
-            {
-                0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 00..1F
-                0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 20..3F
-                0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 40..5F
-                0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 60..7F
-                1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, // 80..9F
-                7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, // A0..BF
-                8, 8, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // C0..DF
-                0xA, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x4, 0x3, 0x3, // E0..EF
-                0xB, 0x6, 0x6, 0x6, 0x5, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, // F0..FF
-                0x0, 0x1, 0x2, 0x3, 0x5, 0x8, 0x7, 0x1, 0x1, 0x1, 0x4, 0x6, 0x1, 0x1, 0x1, 0x1, // s0..s0
-                1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, // s1..s2
-                1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, // s3..s4
-                1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, // s5..s6
-                1, 3, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 // s7..s8
-            }
-        };
-
-        const std::uint8_t type = utf8d[byte];
-
-        codep = (state != UTF8_ACCEPT)
-                ? (byte & 0x3fu) | (codep << 6u)
-                : (0xFFu >> type) & (byte);
-
-        std::size_t index = 256u + static_cast<size_t>(state) * 16u + static_cast<size_t>(type);
-        JSON_ASSERT(index < 400);
-        state = utf8d[index];
-        return state;
-    }
-
-    /*
-     * Overload to make the compiler happy while it is instantiating
-     * dump_integer for number_unsigned_t.
-     * Must never be called.
-     */
-    number_unsigned_t remove_sign(number_unsigned_t x)
-    {
-        JSON_ASSERT(false); // LCOV_EXCL_LINE
-        return x; // LCOV_EXCL_LINE
-    }
-
-    /*
-     * Helper function for dump_integer
-     *
-     * This function takes a negative signed integer and returns its absolute
-     * value as unsigned integer. The plus/minus shuffling is necessary as we can
-     * not directly remove the sign of an arbitrary signed integer as the
-     * absolute values of INT_MIN and INT_MAX are usually not the same. See
-     * #1708 for details.
-     */
-    inline number_unsigned_t remove_sign(number_integer_t x) noexcept
-    {
-        JSON_ASSERT(x < 0 && x < (std::numeric_limits<number_integer_t>::max)());
-        return static_cast<number_unsigned_t>(-(x + 1)) + 1;
-    }
-
-  private:
-    /// the output of the serializer
-    output_adapter_t<char> o = nullptr;
-
-    /// a (hopefully) large enough character buffer
-    std::array<char, 64> number_buffer{{}};
-
-    /// the locale
-    const std::lconv* loc = nullptr;
-    /// the locale's thousand separator character
-    const char thousands_sep = '\0';
-    /// the locale's decimal point character
-    const char decimal_point = '\0';
-
-    /// string buffer
-    std::array<char, 512> string_buffer{{}};
-
-    /// the indentation character
-    const char indent_char;
-    /// the indentation string
-    string_t indent_string;
-
-    /// error_handler how to react on decoding errors
-    const error_handler_t error_handler;
-};
-}  // namespace detail
-}  // namespace nlohmann
-
-// #include <nlohmann/detail/value_t.hpp>
-
-// #include <nlohmann/json_fwd.hpp>
-
-// #include <nlohmann/ordered_map.hpp>
-
-
-#include <functional> // less
-#include <memory> // allocator
-#include <utility> // pair
-#include <vector> // vector
-
-namespace nlohmann
-{
-
-/// ordered_map: a minimal map-like container that preserves insertion order
-/// for use within nlohmann::basic_json<ordered_map>
-template <class Key, class T, class IgnoredLess = std::less<Key>,
-          class Allocator = std::allocator<std::pair<const Key, T>>>
-                  struct ordered_map : std::vector<std::pair<const Key, T>, Allocator>
-{
-    using key_type = Key;
-    using mapped_type = T;
-    using Container = std::vector<std::pair<const Key, T>, Allocator>;
-    using typename Container::iterator;
-    using typename Container::const_iterator;
-    using typename Container::size_type;
-    using typename Container::value_type;
-
-    // Explicit constructors instead of `using Container::Container`
-    // otherwise older compilers choke on it (GCC <= 5.5, xcode <= 9.4)
-    ordered_map(const Allocator& alloc = Allocator()) : Container{alloc} {}
-    template <class It>
-    ordered_map(It first, It last, const Allocator& alloc = Allocator())
-        : Container{first, last, alloc} {}
-    ordered_map(std::initializer_list<T> init, const Allocator& alloc = Allocator() )
-        : Container{init, alloc} {}
-
-    std::pair<iterator, bool> emplace(const key_type& key, T&& t)
-    {
-        for (auto it = this->begin(); it != this->end(); ++it)
-        {
-            if (it->first == key)
-            {
-                return {it, false};
-            }
-        }
-        Container::emplace_back(key, t);
-        return {--this->end(), true};
-    }
-
-    T& operator[](const Key& key)
-    {
-        return emplace(key, T{}).first->second;
-    }
-
-    const T& operator[](const Key& key) const
-    {
-        return at(key);
-    }
-
-    T& at(const Key& key)
-    {
-        for (auto it = this->begin(); it != this->end(); ++it)
-        {
-            if (it->first == key)
-            {
-                return it->second;
-            }
-        }
-
-        throw std::out_of_range("key not found");
-    }
-
-    const T& at(const Key& key) const
-    {
-        for (auto it = this->begin(); it != this->end(); ++it)
-        {
-            if (it->first == key)
-            {
-                return it->second;
-            }
-        }
-
-        throw std::out_of_range("key not found");
-    }
-
-    size_type erase(const Key& key)
-    {
-        for (auto it = this->begin(); it != this->end(); ++it)
-        {
-            if (it->first == key)
-            {
-                // Since we cannot move const Keys, re-construct them in place
-                for (auto next = it; ++next != this->end(); ++it)
-                {
-                    it->~value_type(); // Destroy but keep allocation
-                    new (&*it) value_type{std::move(*next)};
-                }
-                Container::pop_back();
-                return 1;
-            }
-        }
-        return 0;
-    }
-
-    iterator erase(iterator pos)
-    {
-        auto it = pos;
-
-        // Since we cannot move const Keys, re-construct them in place
-        for (auto next = it; ++next != this->end(); ++it)
-        {
-            it->~value_type(); // Destroy but keep allocation
-            new (&*it) value_type{std::move(*next)};
-        }
-        Container::pop_back();
-        return pos;
-    }
-
-    size_type count(const Key& key) const
-    {
-        for (auto it = this->begin(); it != this->end(); ++it)
-        {
-            if (it->first == key)
-            {
-                return 1;
-            }
-        }
-        return 0;
-    }
-
-    iterator find(const Key& key)
-    {
-        for (auto it = this->begin(); it != this->end(); ++it)
-        {
-            if (it->first == key)
-            {
-                return it;
-            }
-        }
-        return Container::end();
-    }
-
-    const_iterator find(const Key& key) const
-    {
-        for (auto it = this->begin(); it != this->end(); ++it)
-        {
-            if (it->first == key)
-            {
-                return it;
-            }
-        }
-        return Container::end();
-    }
-
-    std::pair<iterator, bool> insert( value_type&& value )
-    {
-        return emplace(value.first, std::move(value.second));
-    }
-
-    std::pair<iterator, bool> insert( const value_type& value )
-    {
-        for (auto it = this->begin(); it != this->end(); ++it)
-        {
-            if (it->first == value.first)
-            {
-                return {it, false};
-            }
-        }
-        Container::push_back(value);
-        return {--this->end(), true};
-    }
-};
-
-}  // namespace nlohmann
-
-
-/*!
-@brief namespace for Niels Lohmann
-@see https://github.com/nlohmann
-@since version 1.0.0
-*/
-namespace nlohmann
-{
-
-/*!
-@brief a class to store JSON values
-
-@tparam ObjectType type for JSON objects (`std::map` by default; will be used
-in @ref object_t)
-@tparam ArrayType type for JSON arrays (`std::vector` by default; will be used
-in @ref array_t)
-@tparam StringType type for JSON strings and object keys (`std::string` by
-default; will be used in @ref string_t)
-@tparam BooleanType type for JSON booleans (`bool` by default; will be used
-in @ref boolean_t)
-@tparam NumberIntegerType type for JSON integer numbers (`int64_t` by
-default; will be used in @ref number_integer_t)
-@tparam NumberUnsignedType type for JSON unsigned integer numbers (@c
-`uint64_t` by default; will be used in @ref number_unsigned_t)
-@tparam NumberFloatType type for JSON floating-point numbers (`double` by
-default; will be used in @ref number_float_t)
-@tparam BinaryType type for packed binary data for compatibility with binary
-serialization formats (`std::vector<std::uint8_t>` by default; will be used in
-@ref binary_t)
-@tparam AllocatorType type of the allocator to use (`std::allocator` by
-default)
-@tparam JSONSerializer the serializer to resolve internal calls to `to_json()`
-and `from_json()` (@ref adl_serializer by default)
-
-@requirement The class satisfies the following concept requirements:
-- Basic
- - [DefaultConstructible](https://en.cppreference.com/w/cpp/named_req/DefaultConstructible):
-   JSON values can be default constructed. The result will be a JSON null
-   value.
- - [MoveConstructible](https://en.cppreference.com/w/cpp/named_req/MoveConstructible):
-   A JSON value can be constructed from an rvalue argument.
- - [CopyConstructible](https://en.cppreference.com/w/cpp/named_req/CopyConstructible):
-   A JSON value can be copy-constructed from an lvalue expression.
- - [MoveAssignable](https://en.cppreference.com/w/cpp/named_req/MoveAssignable):
-   A JSON value van be assigned from an rvalue argument.
- - [CopyAssignable](https://en.cppreference.com/w/cpp/named_req/CopyAssignable):
-   A JSON value can be copy-assigned from an lvalue expression.
- - [Destructible](https://en.cppreference.com/w/cpp/named_req/Destructible):
-   JSON values can be destructed.
-- Layout
- - [StandardLayoutType](https://en.cppreference.com/w/cpp/named_req/StandardLayoutType):
-   JSON values have
-   [standard layout](https://en.cppreference.com/w/cpp/language/data_members#Standard_layout):
-   All non-static data members are private and standard layout types, the
-   class has no virtual functions or (virtual) base classes.
-- Library-wide
- - [EqualityComparable](https://en.cppreference.com/w/cpp/named_req/EqualityComparable):
-   JSON values can be compared with `==`, see @ref
-   operator==(const_reference,const_reference).
- - [LessThanComparable](https://en.cppreference.com/w/cpp/named_req/LessThanComparable):
-   JSON values can be compared with `<`, see @ref
-   operator<(const_reference,const_reference).
- - [Swappable](https://en.cppreference.com/w/cpp/named_req/Swappable):
-   Any JSON lvalue or rvalue of can be swapped with any lvalue or rvalue of
-   other compatible types, using unqualified function call @ref swap().
- - [NullablePointer](https://en.cppreference.com/w/cpp/named_req/NullablePointer):
-   JSON values can be compared against `std::nullptr_t` objects which are used
-   to model the `null` value.
-- Container
- - [Container](https://en.cppreference.com/w/cpp/named_req/Container):
-   JSON values can be used like STL containers and provide iterator access.
- - [ReversibleContainer](https://en.cppreference.com/w/cpp/named_req/ReversibleContainer);
-   JSON values can be used like STL containers and provide reverse iterator
-   access.
-
-@invariant The member variables @a m_value and @a m_type have the following
-relationship:
-- If `m_type == value_t::object`, then `m_value.object != nullptr`.
-- If `m_type == value_t::array`, then `m_value.array != nullptr`.
-- If `m_type == value_t::string`, then `m_value.string != nullptr`.
-The invariants are checked by member function assert_invariant().
-
-@internal
-@note ObjectType trick from https://stackoverflow.com/a/9860911
-@endinternal
-
-@see [RFC 7159: The JavaScript Object Notation (JSON) Data Interchange
-Format](http://rfc7159.net/rfc7159)
-
-@since version 1.0.0
-
-@nosubgrouping
-*/
-NLOHMANN_BASIC_JSON_TPL_DECLARATION
-class basic_json
-{
-  private:
-    template<detail::value_t> friend struct detail::external_constructor;
-    friend ::nlohmann::json_pointer<basic_json>;
-
-    template<typename BasicJsonType, typename InputType>
-    friend class ::nlohmann::detail::parser;
-    friend ::nlohmann::detail::serializer<basic_json>;
-    template<typename BasicJsonType>
-    friend class ::nlohmann::detail::iter_impl;
-    template<typename BasicJsonType, typename CharType>
-    friend class ::nlohmann::detail::binary_writer;
-    template<typename BasicJsonType, typename InputType, typename SAX>
-    friend class ::nlohmann::detail::binary_reader;
-    template<typename BasicJsonType>
-    friend class ::nlohmann::detail::json_sax_dom_parser;
-    template<typename BasicJsonType>
-    friend class ::nlohmann::detail::json_sax_dom_callback_parser;
-
-    /// workaround type for MSVC
-    using basic_json_t = NLOHMANN_BASIC_JSON_TPL;
-
-    // convenience aliases for types residing in namespace detail;
-    using lexer = ::nlohmann::detail::lexer_base<basic_json>;
-
-    template<typename InputAdapterType>
-    static ::nlohmann::detail::parser<basic_json, InputAdapterType> parser(
-        InputAdapterType adapter,
-        detail::parser_callback_t<basic_json>cb = nullptr,
-        const bool allow_exceptions = true,
-        const bool ignore_comments = false
-                                 )
-    {
-        return ::nlohmann::detail::parser<basic_json, InputAdapterType>(std::move(adapter),
-                std::move(cb), allow_exceptions, ignore_comments);
-    }
-
-    using primitive_iterator_t = ::nlohmann::detail::primitive_iterator_t;
-    template<typename BasicJsonType>
-    using internal_iterator = ::nlohmann::detail::internal_iterator<BasicJsonType>;
-    template<typename BasicJsonType>
-    using iter_impl = ::nlohmann::detail::iter_impl<BasicJsonType>;
-    template<typename Iterator>
-    using iteration_proxy = ::nlohmann::detail::iteration_proxy<Iterator>;
-    template<typename Base> using json_reverse_iterator = ::nlohmann::detail::json_reverse_iterator<Base>;
-
-    template<typename CharType>
-    using output_adapter_t = ::nlohmann::detail::output_adapter_t<CharType>;
-
-    template<typename InputType>
-    using binary_reader = ::nlohmann::detail::binary_reader<basic_json, InputType>;
-    template<typename CharType> using binary_writer = ::nlohmann::detail::binary_writer<basic_json, CharType>;
-
-    using serializer = ::nlohmann::detail::serializer<basic_json>;
-
-  public:
-    using value_t = detail::value_t;
-    /// JSON Pointer, see @ref nlohmann::json_pointer
-    using json_pointer = ::nlohmann::json_pointer<basic_json>;
-    template<typename T, typename SFINAE>
-    using json_serializer = JSONSerializer<T, SFINAE>;
-    /// how to treat decoding errors
-    using error_handler_t = detail::error_handler_t;
-    /// how to treat CBOR tags
-    using cbor_tag_handler_t = detail::cbor_tag_handler_t;
-    /// helper type for initializer lists of basic_json values
-    using initializer_list_t = std::initializer_list<detail::json_ref<basic_json>>;
-
-    using input_format_t = detail::input_format_t;
-    /// SAX interface type, see @ref nlohmann::json_sax
-    using json_sax_t = json_sax<basic_json>;
-
-    ////////////////
-    // exceptions //
-    ////////////////
-
-    /// @name exceptions
-    /// Classes to implement user-defined exceptions.
-    /// @{
-
-    /// @copydoc detail::exception
-    using exception = detail::exception;
-    /// @copydoc detail::parse_error
-    using parse_error = detail::parse_error;
-    /// @copydoc detail::invalid_iterator
-    using invalid_iterator = detail::invalid_iterator;
-    /// @copydoc detail::type_error
-    using type_error = detail::type_error;
-    /// @copydoc detail::out_of_range
-    using out_of_range = detail::out_of_range;
-    /// @copydoc detail::other_error
-    using other_error = detail::other_error;
-
-    /// @}
-
-
-    /////////////////////
-    // container types //
-    /////////////////////
-
-    /// @name container types
-    /// The canonic container types to use @ref basic_json like any other STL
-    /// container.
-    /// @{
-
-    /// the type of elements in a basic_json container
-    using value_type = basic_json;
-
-    /// the type of an element reference
-    using reference = value_type&;
-    /// the type of an element const reference
-    using const_reference = const value_type&;
-
-    /// a type to represent differences between iterators
-    using difference_type = std::ptrdiff_t;
-    /// a type to represent container sizes
-    using size_type = std::size_t;
-
-    /// the allocator type
-    using allocator_type = AllocatorType<basic_json>;
-
-    /// the type of an element pointer
-    using pointer = typename std::allocator_traits<allocator_type>::pointer;
-    /// the type of an element const pointer
-    using const_pointer = typename std::allocator_traits<allocator_type>::const_pointer;
-
-    /// an iterator for a basic_json container
-    using iterator = iter_impl<basic_json>;
-    /// a const iterator for a basic_json container
-    using const_iterator = iter_impl<const basic_json>;
-    /// a reverse iterator for a basic_json container
-    using reverse_iterator = json_reverse_iterator<typename basic_json::iterator>;
-    /// a const reverse iterator for a basic_json container
-    using const_reverse_iterator = json_reverse_iterator<typename basic_json::const_iterator>;
-
-    /// @}
-
-
-    /*!
-    @brief returns the allocator associated with the container
-    */
-    static allocator_type get_allocator()
-    {
-        return allocator_type();
-    }
-
-    /*!
-    @brief returns version information on the library
-
-    This function returns a JSON object with information about the library,
-    including the version number and information on the platform and compiler.
-
-    @return JSON object holding version information
-    key         | description
-    ----------- | ---------------
-    `compiler`  | Information on the used compiler. It is an object with the following keys: `c++` (the used C++ standard), `family` (the compiler family; possible values are `clang`, `icc`, `gcc`, `ilecpp`, `msvc`, `pgcpp`, `sunpro`, and `unknown`), and `version` (the compiler version).
-    `copyright` | The copyright line for the library as string.
-    `name`      | The name of the library as string.
-    `platform`  | The used platform as string. Possible values are `win32`, `linux`, `apple`, `unix`, and `unknown`.
-    `url`       | The URL of the project as string.
-    `version`   | The version of the library. It is an object with the following keys: `major`, `minor`, and `patch` as defined by [Semantic Versioning](http://semver.org), and `string` (the version string).
-
-    @liveexample{The following code shows an example output of the `meta()`
-    function.,meta}
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes to any JSON value.
-
-    @complexity Constant.
-
-    @since 2.1.0
-    */
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json meta()
-    {
-        basic_json result;
-
-        result["copyright"] = "(C) 2013-2020 Niels Lohmann";
-        result["name"] = "JSON for Modern C++";
-        result["url"] = "https://github.com/nlohmann/json";
-        result["version"]["string"] =
-            std::to_string(NLOHMANN_JSON_VERSION_MAJOR) + "." +
-            std::to_string(NLOHMANN_JSON_VERSION_MINOR) + "." +
-            std::to_string(NLOHMANN_JSON_VERSION_PATCH);
-        result["version"]["major"] = NLOHMANN_JSON_VERSION_MAJOR;
-        result["version"]["minor"] = NLOHMANN_JSON_VERSION_MINOR;
-        result["version"]["patch"] = NLOHMANN_JSON_VERSION_PATCH;
-
-#ifdef _WIN32
-        result["platform"] = "win32";
-#elif defined __linux__
-        result["platform"] = "linux";
-#elif defined __APPLE__
-        result["platform"] = "apple";
-#elif defined __unix__
-        result["platform"] = "unix";
-#else
-        result["platform"] = "unknown";
-#endif
-
-#if defined(__ICC) || defined(__INTEL_COMPILER)
-        result["compiler"] = {{"family", "icc"}, {"version", __INTEL_COMPILER}};
-#elif defined(__clang__)
-        result["compiler"] = {{"family", "clang"}, {"version", __clang_version__}};
-#elif defined(__GNUC__) || defined(__GNUG__)
-        result["compiler"] = {{"family", "gcc"}, {"version", std::to_string(__GNUC__) + "." + std::to_string(__GNUC_MINOR__) + "." + std::to_string(__GNUC_PATCHLEVEL__)}};
-#elif defined(__HP_cc) || defined(__HP_aCC)
-        result["compiler"] = "hp"
-#elif defined(__IBMCPP__)
-        result["compiler"] = {{"family", "ilecpp"}, {"version", __IBMCPP__}};
-#elif defined(_MSC_VER)
-        result["compiler"] = {{"family", "msvc"}, {"version", _MSC_VER}};
-#elif defined(__PGI)
-        result["compiler"] = {{"family", "pgcpp"}, {"version", __PGI}};
-#elif defined(__SUNPRO_CC)
-        result["compiler"] = {{"family", "sunpro"}, {"version", __SUNPRO_CC}};
-#else
-        result["compiler"] = {{"family", "unknown"}, {"version", "unknown"}};
-#endif
-
-#ifdef __cplusplus
-        result["compiler"]["c++"] = std::to_string(__cplusplus);
-#else
-        result["compiler"]["c++"] = "unknown";
-#endif
-        return result;
-    }
-
-
-    ///////////////////////////
-    // JSON value data types //
-    ///////////////////////////
-
-    /// @name JSON value data types
-    /// The data types to store a JSON value. These types are derived from
-    /// the template arguments passed to class @ref basic_json.
-    /// @{
-
-#if defined(JSON_HAS_CPP_14)
-    // Use transparent comparator if possible, combined with perfect forwarding
-    // on find() and count() calls prevents unnecessary string construction.
-    using object_comparator_t = std::less<>;
-#else
-    using object_comparator_t = std::less<StringType>;
-#endif
-
-    /*!
-    @brief a type for an object
-
-    [RFC 7159](http://rfc7159.net/rfc7159) describes JSON objects as follows:
-    > An object is an unordered collection of zero or more name/value pairs,
-    > where a name is a string and a value is a string, number, boolean, null,
-    > object, or array.
-
-    To store objects in C++, a type is defined by the template parameters
-    described below.
-
-    @tparam ObjectType  the container to store objects (e.g., `std::map` or
-    `std::unordered_map`)
-    @tparam StringType the type of the keys or names (e.g., `std::string`).
-    The comparison function `std::less<StringType>` is used to order elements
-    inside the container.
-    @tparam AllocatorType the allocator to use for objects (e.g.,
-    `std::allocator`)
-
-    #### Default type
-
-    With the default values for @a ObjectType (`std::map`), @a StringType
-    (`std::string`), and @a AllocatorType (`std::allocator`), the default
-    value for @a object_t is:
-
-    @code {.cpp}
-    std::map<
-      std::string, // key_type
-      basic_json, // value_type
-      std::less<std::string>, // key_compare
-      std::allocator<std::pair<const std::string, basic_json>> // allocator_type
-    >
-    @endcode
-
-    #### Behavior
-
-    The choice of @a object_t influences the behavior of the JSON class. With
-    the default type, objects have the following behavior:
-
-    - When all names are unique, objects will be interoperable in the sense
-      that all software implementations receiving that object will agree on
-      the name-value mappings.
-    - When the names within an object are not unique, it is unspecified which
-      one of the values for a given key will be chosen. For instance,
-      `{"key": 2, "key": 1}` could be equal to either `{"key": 1}` or
-      `{"key": 2}`.
-    - Internally, name/value pairs are stored in lexicographical order of the
-      names. Objects will also be serialized (see @ref dump) in this order.
-      For instance, `{"b": 1, "a": 2}` and `{"a": 2, "b": 1}` will be stored
-      and serialized as `{"a": 2, "b": 1}`.
-    - When comparing objects, the order of the name/value pairs is irrelevant.
-      This makes objects interoperable in the sense that they will not be
-      affected by these differences. For instance, `{"b": 1, "a": 2}` and
-      `{"a": 2, "b": 1}` will be treated as equal.
-
-    #### Limits
-
-    [RFC 7159](http://rfc7159.net/rfc7159) specifies:
-    > An implementation may set limits on the maximum depth of nesting.
-
-    In this class, the object's limit of nesting is not explicitly constrained.
-    However, a maximum depth of nesting may be introduced by the compiler or
-    runtime environment. A theoretical limit can be queried by calling the
-    @ref max_size function of a JSON object.
-
-    #### Storage
-
-    Objects are stored as pointers in a @ref basic_json type. That is, for any
-    access to object values, a pointer of type `object_t*` must be
-    dereferenced.
-
-    @sa @ref array_t -- type for an array value
-
-    @since version 1.0.0
-
-    @note The order name/value pairs are added to the object is *not*
-    preserved by the library. Therefore, iterating an object may return
-    name/value pairs in a different order than they were originally stored. In
-    fact, keys will be traversed in alphabetical order as `std::map` with
-    `std::less` is used by default. Please note this behavior conforms to [RFC
-    7159](http://rfc7159.net/rfc7159), because any order implements the
-    specified "unordered" nature of JSON objects.
-    */
-    using object_t = ObjectType<StringType,
-          basic_json,
-          object_comparator_t,
-          AllocatorType<std::pair<const StringType,
-          basic_json>>>;
-
-    /*!
-    @brief a type for an array
-
-    [RFC 7159](http://rfc7159.net/rfc7159) describes JSON arrays as follows:
-    > An array is an ordered sequence of zero or more values.
-
-    To store objects in C++, a type is defined by the template parameters
-    explained below.
-
-    @tparam ArrayType  container type to store arrays (e.g., `std::vector` or
-    `std::list`)
-    @tparam AllocatorType allocator to use for arrays (e.g., `std::allocator`)
-
-    #### Default type
-
-    With the default values for @a ArrayType (`std::vector`) and @a
-    AllocatorType (`std::allocator`), the default value for @a array_t is:
-
-    @code {.cpp}
-    std::vector<
-      basic_json, // value_type
-      std::allocator<basic_json> // allocator_type
-    >
-    @endcode
-
-    #### Limits
-
-    [RFC 7159](http://rfc7159.net/rfc7159) specifies:
-    > An implementation may set limits on the maximum depth of nesting.
-
-    In this class, the array's limit of nesting is not explicitly constrained.
-    However, a maximum depth of nesting may be introduced by the compiler or
-    runtime environment. A theoretical limit can be queried by calling the
-    @ref max_size function of a JSON array.
-
-    #### Storage
-
-    Arrays are stored as pointers in a @ref basic_json type. That is, for any
-    access to array values, a pointer of type `array_t*` must be dereferenced.
-
-    @sa @ref object_t -- type for an object value
-
-    @since version 1.0.0
-    */
-    using array_t = ArrayType<basic_json, AllocatorType<basic_json>>;
-
-    /*!
-    @brief a type for a string
-
-    [RFC 7159](http://rfc7159.net/rfc7159) describes JSON strings as follows:
-    > A string is a sequence of zero or more Unicode characters.
-
-    To store objects in C++, a type is defined by the template parameter
-    described below. Unicode values are split by the JSON class into
-    byte-sized characters during deserialization.
-
-    @tparam StringType  the container to store strings (e.g., `std::string`).
-    Note this container is used for keys/names in objects, see @ref object_t.
-
-    #### Default type
-
-    With the default values for @a StringType (`std::string`), the default
-    value for @a string_t is:
-
-    @code {.cpp}
-    std::string
-    @endcode
-
-    #### Encoding
-
-    Strings are stored in UTF-8 encoding. Therefore, functions like
-    `std::string::size()` or `std::string::length()` return the number of
-    bytes in the string rather than the number of characters or glyphs.
-
-    #### String comparison
-
-    [RFC 7159](http://rfc7159.net/rfc7159) states:
-    > Software implementations are typically required to test names of object
-    > members for equality. Implementations that transform the textual
-    > representation into sequences of Unicode code units and then perform the
-    > comparison numerically, code unit by code unit, are interoperable in the
-    > sense that implementations will agree in all cases on equality or
-    > inequality of two strings. For example, implementations that compare
-    > strings with escaped characters unconverted may incorrectly find that
-    > `"a\\b"` and `"a\u005Cb"` are not equal.
-
-    This implementation is interoperable as it does compare strings code unit
-    by code unit.
-
-    #### Storage
-
-    String values are stored as pointers in a @ref basic_json type. That is,
-    for any access to string values, a pointer of type `string_t*` must be
-    dereferenced.
-
-    @since version 1.0.0
-    */
-    using string_t = StringType;
-
-    /*!
-    @brief a type for a boolean
-
-    [RFC 7159](http://rfc7159.net/rfc7159) implicitly describes a boolean as a
-    type which differentiates the two literals `true` and `false`.
-
-    To store objects in C++, a type is defined by the template parameter @a
-    BooleanType which chooses the type to use.
-
-    #### Default type
-
-    With the default values for @a BooleanType (`bool`), the default value for
-    @a boolean_t is:
-
-    @code {.cpp}
-    bool
-    @endcode
-
-    #### Storage
-
-    Boolean values are stored directly inside a @ref basic_json type.
-
-    @since version 1.0.0
-    */
-    using boolean_t = BooleanType;
-
-    /*!
-    @brief a type for a number (integer)
-
-    [RFC 7159](http://rfc7159.net/rfc7159) describes numbers as follows:
-    > The representation of numbers is similar to that used in most
-    > programming languages. A number is represented in base 10 using decimal
-    > digits. It contains an integer component that may be prefixed with an
-    > optional minus sign, which may be followed by a fraction part and/or an
-    > exponent part. Leading zeros are not allowed. (...) Numeric values that
-    > cannot be represented in the grammar below (such as Infinity and NaN)
-    > are not permitted.
-
-    This description includes both integer and floating-point numbers.
-    However, C++ allows more precise storage if it is known whether the number
-    is a signed integer, an unsigned integer or a floating-point number.
-    Therefore, three different types, @ref number_integer_t, @ref
-    number_unsigned_t and @ref number_float_t are used.
-
-    To store integer numbers in C++, a type is defined by the template
-    parameter @a NumberIntegerType which chooses the type to use.
-
-    #### Default type
-
-    With the default values for @a NumberIntegerType (`int64_t`), the default
-    value for @a number_integer_t is:
-
-    @code {.cpp}
-    int64_t
-    @endcode
-
-    #### Default behavior
-
-    - The restrictions about leading zeros is not enforced in C++. Instead,
-      leading zeros in integer literals lead to an interpretation as octal
-      number. Internally, the value will be stored as decimal number. For
-      instance, the C++ integer literal `010` will be serialized to `8`.
-      During deserialization, leading zeros yield an error.
-    - Not-a-number (NaN) values will be serialized to `null`.
-
-    #### Limits
-
-    [RFC 7159](http://rfc7159.net/rfc7159) specifies:
-    > An implementation may set limits on the range and precision of numbers.
-
-    When the default type is used, the maximal integer number that can be
-    stored is `9223372036854775807` (INT64_MAX) and the minimal integer number
-    that can be stored is `-9223372036854775808` (INT64_MIN). Integer numbers
-    that are out of range will yield over/underflow when used in a
-    constructor. During deserialization, too large or small integer numbers
-    will be automatically be stored as @ref number_unsigned_t or @ref
-    number_float_t.
-
-    [RFC 7159](http://rfc7159.net/rfc7159) further states:
-    > Note that when such software is used, numbers that are integers and are
-    > in the range \f$[-2^{53}+1, 2^{53}-1]\f$ are interoperable in the sense
-    > that implementations will agree exactly on their numeric values.
-
-    As this range is a subrange of the exactly supported range [INT64_MIN,
-    INT64_MAX], this class's integer type is interoperable.
-
-    #### Storage
-
-    Integer number values are stored directly inside a @ref basic_json type.
-
-    @sa @ref number_float_t -- type for number values (floating-point)
-
-    @sa @ref number_unsigned_t -- type for number values (unsigned integer)
-
-    @since version 1.0.0
-    */
-    using number_integer_t = NumberIntegerType;
-
-    /*!
-    @brief a type for a number (unsigned)
-
-    [RFC 7159](http://rfc7159.net/rfc7159) describes numbers as follows:
-    > The representation of numbers is similar to that used in most
-    > programming languages. A number is represented in base 10 using decimal
-    > digits. It contains an integer component that may be prefixed with an
-    > optional minus sign, which may be followed by a fraction part and/or an
-    > exponent part. Leading zeros are not allowed. (...) Numeric values that
-    > cannot be represented in the grammar below (such as Infinity and NaN)
-    > are not permitted.
-
-    This description includes both integer and floating-point numbers.
-    However, C++ allows more precise storage if it is known whether the number
-    is a signed integer, an unsigned integer or a floating-point number.
-    Therefore, three different types, @ref number_integer_t, @ref
-    number_unsigned_t and @ref number_float_t are used.
-
-    To store unsigned integer numbers in C++, a type is defined by the
-    template parameter @a NumberUnsignedType which chooses the type to use.
-
-    #### Default type
-
-    With the default values for @a NumberUnsignedType (`uint64_t`), the
-    default value for @a number_unsigned_t is:
-
-    @code {.cpp}
-    uint64_t
-    @endcode
-
-    #### Default behavior
-
-    - The restrictions about leading zeros is not enforced in C++. Instead,
-      leading zeros in integer literals lead to an interpretation as octal
-      number. Internally, the value will be stored as decimal number. For
-      instance, the C++ integer literal `010` will be serialized to `8`.
-      During deserialization, leading zeros yield an error.
-    - Not-a-number (NaN) values will be serialized to `null`.
-
-    #### Limits
-
-    [RFC 7159](http://rfc7159.net/rfc7159) specifies:
-    > An implementation may set limits on the range and precision of numbers.
-
-    When the default type is used, the maximal integer number that can be
-    stored is `18446744073709551615` (UINT64_MAX) and the minimal integer
-    number that can be stored is `0`. Integer numbers that are out of range
-    will yield over/underflow when used in a constructor. During
-    deserialization, too large or small integer numbers will be automatically
-    be stored as @ref number_integer_t or @ref number_float_t.
-
-    [RFC 7159](http://rfc7159.net/rfc7159) further states:
-    > Note that when such software is used, numbers that are integers and are
-    > in the range \f$[-2^{53}+1, 2^{53}-1]\f$ are interoperable in the sense
-    > that implementations will agree exactly on their numeric values.
-
-    As this range is a subrange (when considered in conjunction with the
-    number_integer_t type) of the exactly supported range [0, UINT64_MAX],
-    this class's integer type is interoperable.
-
-    #### Storage
-
-    Integer number values are stored directly inside a @ref basic_json type.
-
-    @sa @ref number_float_t -- type for number values (floating-point)
-    @sa @ref number_integer_t -- type for number values (integer)
-
-    @since version 2.0.0
-    */
-    using number_unsigned_t = NumberUnsignedType;
-
-    /*!
-    @brief a type for a number (floating-point)
-
-    [RFC 7159](http://rfc7159.net/rfc7159) describes numbers as follows:
-    > The representation of numbers is similar to that used in most
-    > programming languages. A number is represented in base 10 using decimal
-    > digits. It contains an integer component that may be prefixed with an
-    > optional minus sign, which may be followed by a fraction part and/or an
-    > exponent part. Leading zeros are not allowed. (...) Numeric values that
-    > cannot be represented in the grammar below (such as Infinity and NaN)
-    > are not permitted.
-
-    This description includes both integer and floating-point numbers.
-    However, C++ allows more precise storage if it is known whether the number
-    is a signed integer, an unsigned integer or a floating-point number.
-    Therefore, three different types, @ref number_integer_t, @ref
-    number_unsigned_t and @ref number_float_t are used.
-
-    To store floating-point numbers in C++, a type is defined by the template
-    parameter @a NumberFloatType which chooses the type to use.
-
-    #### Default type
-
-    With the default values for @a NumberFloatType (`double`), the default
-    value for @a number_float_t is:
-
-    @code {.cpp}
-    double
-    @endcode
-
-    #### Default behavior
-
-    - The restrictions about leading zeros is not enforced in C++. Instead,
-      leading zeros in floating-point literals will be ignored. Internally,
-      the value will be stored as decimal number. For instance, the C++
-      floating-point literal `01.2` will be serialized to `1.2`. During
-      deserialization, leading zeros yield an error.
-    - Not-a-number (NaN) values will be serialized to `null`.
-
-    #### Limits
-
-    [RFC 7159](http://rfc7159.net/rfc7159) states:
-    > This specification allows implementations to set limits on the range and
-    > precision of numbers accepted. Since software that implements IEEE
-    > 754-2008 binary64 (double precision) numbers is generally available and
-    > widely used, good interoperability can be achieved by implementations
-    > that expect no more precision or range than these provide, in the sense
-    > that implementations will approximate JSON numbers within the expected
-    > precision.
-
-    This implementation does exactly follow this approach, as it uses double
-    precision floating-point numbers. Note values smaller than
-    `-1.79769313486232e+308` and values greater than `1.79769313486232e+308`
-    will be stored as NaN internally and be serialized to `null`.
-
-    #### Storage
-
-    Floating-point number values are stored directly inside a @ref basic_json
-    type.
-
-    @sa @ref number_integer_t -- type for number values (integer)
-
-    @sa @ref number_unsigned_t -- type for number values (unsigned integer)
-
-    @since version 1.0.0
-    */
-    using number_float_t = NumberFloatType;
-
-    /*!
-    @brief a type for a packed binary type
-
-    This type is a type designed to carry binary data that appears in various
-    serialized formats, such as CBOR's Major Type 2, MessagePack's bin, and
-    BSON's generic binary subtype. This type is NOT a part of standard JSON and
-    exists solely for compatibility with these binary types. As such, it is
-    simply defined as an ordered sequence of zero or more byte values.
-
-    Additionally, as an implementation detail, the subtype of the binary data is
-    carried around as a `std::uint8_t`, which is compatible with both of the
-    binary data formats that use binary subtyping, (though the specific
-    numbering is incompatible with each other, and it is up to the user to
-    translate between them).
-
-    [CBOR's RFC 7049](https://tools.ietf.org/html/rfc7049) describes this type
-    as:
-    > Major type 2: a byte string. The string's length in bytes is represented
-    > following the rules for positive integers (major type 0).
-
-    [MessagePack's documentation on the bin type
-    family](https://github.com/msgpack/msgpack/blob/master/spec.md#bin-format-family)
-    describes this type as:
-    > Bin format family stores an byte array in 2, 3, or 5 bytes of extra bytes
-    > in addition to the size of the byte array.
-
-    [BSON's specifications](http://bsonspec.org/spec.html) describe several
-    binary types; however, this type is intended to represent the generic binary
-    type which has the description:
-    > Generic binary subtype - This is the most commonly used binary subtype and
-    > should be the 'default' for drivers and tools.
-
-    None of these impose any limitations on the internal representation other
-    than the basic unit of storage be some type of array whose parts are
-    decomposable into bytes.
-
-    The default representation of this binary format is a
-    `std::vector<std::uint8_t>`, which is a very common way to represent a byte
-    array in modern C++.
-
-    #### Default type
-
-    The default values for @a BinaryType is `std::vector<std::uint8_t>`
-
-    #### Storage
-
-    Binary Arrays are stored as pointers in a @ref basic_json type. That is,
-    for any access to array values, a pointer of the type `binary_t*` must be
-    dereferenced.
-
-    #### Notes on subtypes
-
-    - CBOR
-       - Binary values are represented as byte strings. No subtypes are
-         supported and will be ignored when CBOR is written.
-    - MessagePack
-       - If a subtype is given and the binary array contains exactly 1, 2, 4, 8,
-         or 16 elements, the fixext family (fixext1, fixext2, fixext4, fixext8)
-         is used. For other sizes, the ext family (ext8, ext16, ext32) is used.
-         The subtype is then added as singed 8-bit integer.
-       - If no subtype is given, the bin family (bin8, bin16, bin32) is used.
-    - BSON
-       - If a subtype is given, it is used and added as unsigned 8-bit integer.
-       - If no subtype is given, the generic binary subtype 0x00 is used.
-
-    @sa @ref binary -- create a binary array
-
-    @since version 3.8.0
-    */
-    using binary_t = nlohmann::byte_container_with_subtype<BinaryType>;
-    /// @}
-
-  private:
-
-    /// helper for exception-safe object creation
-    template<typename T, typename... Args>
-    JSON_HEDLEY_RETURNS_NON_NULL
-    static T* create(Args&& ... args)
-    {
-        AllocatorType<T> alloc;
-        using AllocatorTraits = std::allocator_traits<AllocatorType<T>>;
-
-        auto deleter = [&](T * object)
-        {
-            AllocatorTraits::deallocate(alloc, object, 1);
-        };
-        std::unique_ptr<T, decltype(deleter)> object(AllocatorTraits::allocate(alloc, 1), deleter);
-        AllocatorTraits::construct(alloc, object.get(), std::forward<Args>(args)...);
-        JSON_ASSERT(object != nullptr);
-        return object.release();
-    }
-
-    ////////////////////////
-    // JSON value storage //
-    ////////////////////////
-
-    /*!
-    @brief a JSON value
-
-    The actual storage for a JSON value of the @ref basic_json class. This
-    union combines the different storage types for the JSON value types
-    defined in @ref value_t.
-
-    JSON type | value_t type    | used type
-    --------- | --------------- | ------------------------
-    object    | object          | pointer to @ref object_t
-    array     | array           | pointer to @ref array_t
-    string    | string          | pointer to @ref string_t
-    boolean   | boolean         | @ref boolean_t
-    number    | number_integer  | @ref number_integer_t
-    number    | number_unsigned | @ref number_unsigned_t
-    number    | number_float    | @ref number_float_t
-    binary    | binary          | pointer to @ref binary_t
-    null      | null            | *no value is stored*
-
-    @note Variable-length types (objects, arrays, and strings) are stored as
-    pointers. The size of the union should not exceed 64 bits if the default
-    value types are used.
-
-    @since version 1.0.0
-    */
-    union json_value
-    {
-        /// object (stored with pointer to save storage)
-        object_t* object;
-        /// array (stored with pointer to save storage)
-        array_t* array;
-        /// string (stored with pointer to save storage)
-        string_t* string;
-        /// binary (stored with pointer to save storage)
-        binary_t* binary;
-        /// boolean
-        boolean_t boolean;
-        /// number (integer)
-        number_integer_t number_integer;
-        /// number (unsigned integer)
-        number_unsigned_t number_unsigned;
-        /// number (floating-point)
-        number_float_t number_float;
-
-        /// default constructor (for null values)
-        json_value() = default;
-        /// constructor for booleans
-        json_value(boolean_t v) noexcept : boolean(v) {}
-        /// constructor for numbers (integer)
-        json_value(number_integer_t v) noexcept : number_integer(v) {}
-        /// constructor for numbers (unsigned)
-        json_value(number_unsigned_t v) noexcept : number_unsigned(v) {}
-        /// constructor for numbers (floating-point)
-        json_value(number_float_t v) noexcept : number_float(v) {}
-        /// constructor for empty values of a given type
-        json_value(value_t t)
-        {
-            switch (t)
-            {
-                case value_t::object:
-                {
-                    object = create<object_t>();
-                    break;
-                }
-
-                case value_t::array:
-                {
-                    array = create<array_t>();
-                    break;
-                }
-
-                case value_t::string:
-                {
-                    string = create<string_t>("");
-                    break;
-                }
-
-                case value_t::binary:
-                {
-                    binary = create<binary_t>();
-                    break;
-                }
-
-                case value_t::boolean:
-                {
-                    boolean = boolean_t(false);
-                    break;
-                }
-
-                case value_t::number_integer:
-                {
-                    number_integer = number_integer_t(0);
-                    break;
-                }
-
-                case value_t::number_unsigned:
-                {
-                    number_unsigned = number_unsigned_t(0);
-                    break;
-                }
-
-                case value_t::number_float:
-                {
-                    number_float = number_float_t(0.0);
-                    break;
-                }
-
-                case value_t::null:
-                {
-                    object = nullptr;  // silence warning, see #821
-                    break;
-                }
-
-                default:
-                {
-                    object = nullptr;  // silence warning, see #821
-                    if (JSON_HEDLEY_UNLIKELY(t == value_t::null))
-                    {
-                        JSON_THROW(other_error::create(500, "961c151d2e87f2686a955a9be24d316f1362bf21 3.9.1")); // LCOV_EXCL_LINE
-                    }
-                    break;
-                }
-            }
-        }
-
-        /// constructor for strings
-        json_value(const string_t& value)
-        {
-            string = create<string_t>(value);
-        }
-
-        /// constructor for rvalue strings
-        json_value(string_t&& value)
-        {
-            string = create<string_t>(std::move(value));
-        }
-
-        /// constructor for objects
-        json_value(const object_t& value)
-        {
-            object = create<object_t>(value);
-        }
-
-        /// constructor for rvalue objects
-        json_value(object_t&& value)
-        {
-            object = create<object_t>(std::move(value));
-        }
-
-        /// constructor for arrays
-        json_value(const array_t& value)
-        {
-            array = create<array_t>(value);
-        }
-
-        /// constructor for rvalue arrays
-        json_value(array_t&& value)
-        {
-            array = create<array_t>(std::move(value));
-        }
-
-        /// constructor for binary arrays
-        json_value(const typename binary_t::container_type& value)
-        {
-            binary = create<binary_t>(value);
-        }
-
-        /// constructor for rvalue binary arrays
-        json_value(typename binary_t::container_type&& value)
-        {
-            binary = create<binary_t>(std::move(value));
-        }
-
-        /// constructor for binary arrays (internal type)
-        json_value(const binary_t& value)
-        {
-            binary = create<binary_t>(value);
-        }
-
-        /// constructor for rvalue binary arrays (internal type)
-        json_value(binary_t&& value)
-        {
-            binary = create<binary_t>(std::move(value));
-        }
-
-        void destroy(value_t t) noexcept
-        {
-            // flatten the current json_value to a heap-allocated stack
-            std::vector<basic_json> stack;
-
-            // move the top-level items to stack
-            if (t == value_t::array)
-            {
-                stack.reserve(array->size());
-                std::move(array->begin(), array->end(), std::back_inserter(stack));
-            }
-            else if (t == value_t::object)
-            {
-                stack.reserve(object->size());
-                for (auto&& it : *object)
-                {
-                    stack.push_back(std::move(it.second));
-                }
-            }
-
-            while (!stack.empty())
-            {
-                // move the last item to local variable to be processed
-                basic_json current_item(std::move(stack.back()));
-                stack.pop_back();
-
-                // if current_item is array/object, move
-                // its children to the stack to be processed later
-                if (current_item.is_array())
-                {
-                    std::move(current_item.m_value.array->begin(), current_item.m_value.array->end(),
-                              std::back_inserter(stack));
-
-                    current_item.m_value.array->clear();
-                }
-                else if (current_item.is_object())
-                {
-                    for (auto&& it : *current_item.m_value.object)
-                    {
-                        stack.push_back(std::move(it.second));
-                    }
-
-                    current_item.m_value.object->clear();
-                }
-
-                // it's now safe that current_item get destructed
-                // since it doesn't have any children
-            }
-
-            switch (t)
-            {
-                case value_t::object:
-                {
-                    AllocatorType<object_t> alloc;
-                    std::allocator_traits<decltype(alloc)>::destroy(alloc, object);
-                    std::allocator_traits<decltype(alloc)>::deallocate(alloc, object, 1);
-                    break;
-                }
-
-                case value_t::array:
-                {
-                    AllocatorType<array_t> alloc;
-                    std::allocator_traits<decltype(alloc)>::destroy(alloc, array);
-                    std::allocator_traits<decltype(alloc)>::deallocate(alloc, array, 1);
-                    break;
-                }
-
-                case value_t::string:
-                {
-                    AllocatorType<string_t> alloc;
-                    std::allocator_traits<decltype(alloc)>::destroy(alloc, string);
-                    std::allocator_traits<decltype(alloc)>::deallocate(alloc, string, 1);
-                    break;
-                }
-
-                case value_t::binary:
-                {
-                    AllocatorType<binary_t> alloc;
-                    std::allocator_traits<decltype(alloc)>::destroy(alloc, binary);
-                    std::allocator_traits<decltype(alloc)>::deallocate(alloc, binary, 1);
-                    break;
-                }
-
-                default:
-                {
-                    break;
-                }
-            }
-        }
-    };
-
-    /*!
-    @brief checks the class invariants
-
-    This function asserts the class invariants. It needs to be called at the
-    end of every constructor to make sure that created objects respect the
-    invariant. Furthermore, it has to be called each time the type of a JSON
-    value is changed, because the invariant expresses a relationship between
-    @a m_type and @a m_value.
-    */
-    void assert_invariant() const noexcept
-    {
-        JSON_ASSERT(m_type != value_t::object || m_value.object != nullptr);
-        JSON_ASSERT(m_type != value_t::array || m_value.array != nullptr);
-        JSON_ASSERT(m_type != value_t::string || m_value.string != nullptr);
-        JSON_ASSERT(m_type != value_t::binary || m_value.binary != nullptr);
-    }
-
-  public:
-    //////////////////////////
-    // JSON parser callback //
-    //////////////////////////
-
-    /*!
-    @brief parser event types
-
-    The parser callback distinguishes the following events:
-    - `object_start`: the parser read `{` and started to process a JSON object
-    - `key`: the parser read a key of a value in an object
-    - `object_end`: the parser read `}` and finished processing a JSON object
-    - `array_start`: the parser read `[` and started to process a JSON array
-    - `array_end`: the parser read `]` and finished processing a JSON array
-    - `value`: the parser finished reading a JSON value
-
-    @image html callback_events.png "Example when certain parse events are triggered"
-
-    @sa @ref parser_callback_t for more information and examples
-    */
-    using parse_event_t = detail::parse_event_t;
-
-    /*!
-    @brief per-element parser callback type
-
-    With a parser callback function, the result of parsing a JSON text can be
-    influenced. When passed to @ref parse, it is called on certain events
-    (passed as @ref parse_event_t via parameter @a event) with a set recursion
-    depth @a depth and context JSON value @a parsed. The return value of the
-    callback function is a boolean indicating whether the element that emitted
-    the callback shall be kept or not.
-
-    We distinguish six scenarios (determined by the event type) in which the
-    callback function can be called. The following table describes the values
-    of the parameters @a depth, @a event, and @a parsed.
-
-    parameter @a event | description | parameter @a depth | parameter @a parsed
-    ------------------ | ----------- | ------------------ | -------------------
-    parse_event_t::object_start | the parser read `{` and started to process a JSON object | depth of the parent of the JSON object | a JSON value with type discarded
-    parse_event_t::key | the parser read a key of a value in an object | depth of the currently parsed JSON object | a JSON string containing the key
-    parse_event_t::object_end | the parser read `}` and finished processing a JSON object | depth of the parent of the JSON object | the parsed JSON object
-    parse_event_t::array_start | the parser read `[` and started to process a JSON array | depth of the parent of the JSON array | a JSON value with type discarded
-    parse_event_t::array_end | the parser read `]` and finished processing a JSON array | depth of the parent of the JSON array | the parsed JSON array
-    parse_event_t::value | the parser finished reading a JSON value | depth of the value | the parsed JSON value
-
-    @image html callback_events.png "Example when certain parse events are triggered"
-
-    Discarding a value (i.e., returning `false`) has different effects
-    depending on the context in which function was called:
-
-    - Discarded values in structured types are skipped. That is, the parser
-      will behave as if the discarded value was never read.
-    - In case a value outside a structured type is skipped, it is replaced
-      with `null`. This case happens if the top-level element is skipped.
-
-    @param[in] depth  the depth of the recursion during parsing
-
-    @param[in] event  an event of type parse_event_t indicating the context in
-    the callback function has been called
-
-    @param[in,out] parsed  the current intermediate parse result; note that
-    writing to this value has no effect for parse_event_t::key events
-
-    @return Whether the JSON value which called the function during parsing
-    should be kept (`true`) or not (`false`). In the latter case, it is either
-    skipped completely or replaced by an empty discarded object.
-
-    @sa @ref parse for examples
-
-    @since version 1.0.0
-    */
-    using parser_callback_t = detail::parser_callback_t<basic_json>;
-
-    //////////////////
-    // constructors //
-    //////////////////
-
-    /// @name constructors and destructors
-    /// Constructors of class @ref basic_json, copy/move constructor, copy
-    /// assignment, static functions creating objects, and the destructor.
-    /// @{
-
-    /*!
-    @brief create an empty value with a given type
-
-    Create an empty JSON value with a given type. The value will be default
-    initialized with an empty value which depends on the type:
-
-    Value type  | initial value
-    ----------- | -------------
-    null        | `null`
-    boolean     | `false`
-    string      | `""`
-    number      | `0`
-    object      | `{}`
-    array       | `[]`
-    binary      | empty array
-
-    @param[in] v  the type of the value to create
-
-    @complexity Constant.
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes to any JSON value.
-
-    @liveexample{The following code shows the constructor for different @ref
-    value_t values,basic_json__value_t}
-
-    @sa @ref clear() -- restores the postcondition of this constructor
-
-    @since version 1.0.0
-    */
-    basic_json(const value_t v)
-        : m_type(v), m_value(v)
-    {
-        assert_invariant();
-    }
-
-    /*!
-    @brief create a null object
-
-    Create a `null` JSON value. It either takes a null pointer as parameter
-    (explicitly creating `null`) or no parameter (implicitly creating `null`).
-    The passed null pointer itself is not read -- it is only used to choose
-    the right constructor.
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this constructor never throws
-    exceptions.
-
-    @liveexample{The following code shows the constructor with and without a
-    null pointer parameter.,basic_json__nullptr_t}
-
-    @since version 1.0.0
-    */
-    basic_json(std::nullptr_t = nullptr) noexcept
-        : basic_json(value_t::null)
-    {
-        assert_invariant();
-    }
-
-    /*!
-    @brief create a JSON value
-
-    This is a "catch all" constructor for all compatible JSON types; that is,
-    types for which a `to_json()` method exists. The constructor forwards the
-    parameter @a val to that method (to `json_serializer<U>::to_json` method
-    with `U = uncvref_t<CompatibleType>`, to be exact).
-
-    Template type @a CompatibleType includes, but is not limited to, the
-    following types:
-    - **arrays**: @ref array_t and all kinds of compatible containers such as
-      `std::vector`, `std::deque`, `std::list`, `std::forward_list`,
-      `std::array`, `std::valarray`, `std::set`, `std::unordered_set`,
-      `std::multiset`, and `std::unordered_multiset` with a `value_type` from
-      which a @ref basic_json value can be constructed.
-    - **objects**: @ref object_t and all kinds of compatible associative
-      containers such as `std::map`, `std::unordered_map`, `std::multimap`,
-      and `std::unordered_multimap` with a `key_type` compatible to
-      @ref string_t and a `value_type` from which a @ref basic_json value can
-      be constructed.
-    - **strings**: @ref string_t, string literals, and all compatible string
-      containers can be used.
-    - **numbers**: @ref number_integer_t, @ref number_unsigned_t,
-      @ref number_float_t, and all convertible number types such as `int`,
-      `size_t`, `int64_t`, `float` or `double` can be used.
-    - **boolean**: @ref boolean_t / `bool` can be used.
-    - **binary**: @ref binary_t / `std::vector<uint8_t>` may be used,
-      unfortunately because string literals cannot be distinguished from binary
-      character arrays by the C++ type system, all types compatible with `const
-      char*` will be directed to the string constructor instead.  This is both
-      for backwards compatibility, and due to the fact that a binary type is not
-      a standard JSON type.
-
-    See the examples below.
-
-    @tparam CompatibleType a type such that:
-    - @a CompatibleType is not derived from `std::istream`,
-    - @a CompatibleType is not @ref basic_json (to avoid hijacking copy/move
-         constructors),
-    - @a CompatibleType is not a different @ref basic_json type (i.e. with different template arguments)
-    - @a CompatibleType is not a @ref basic_json nested type (e.g.,
-         @ref json_pointer, @ref iterator, etc ...)
-    - @ref @ref json_serializer<U> has a
-         `to_json(basic_json_t&, CompatibleType&&)` method
-
-    @tparam U = `uncvref_t<CompatibleType>`
-
-    @param[in] val the value to be forwarded to the respective constructor
-
-    @complexity Usually linear in the size of the passed @a val, also
-                depending on the implementation of the called `to_json()`
-                method.
-
-    @exceptionsafety Depends on the called constructor. For types directly
-    supported by the library (i.e., all types for which no `to_json()` function
-    was provided), strong guarantee holds: if an exception is thrown, there are
-    no changes to any JSON value.
-
-    @liveexample{The following code shows the constructor with several
-    compatible types.,basic_json__CompatibleType}
-
-    @since version 2.1.0
-    */
-    template < typename CompatibleType,
-               typename U = detail::uncvref_t<CompatibleType>,
-               detail::enable_if_t <
-                   !detail::is_basic_json<U>::value && detail::is_compatible_type<basic_json_t, U>::value, int > = 0 >
-    basic_json(CompatibleType && val) noexcept(noexcept(
-                JSONSerializer<U>::to_json(std::declval<basic_json_t&>(),
-                                           std::forward<CompatibleType>(val))))
-    {
-        JSONSerializer<U>::to_json(*this, std::forward<CompatibleType>(val));
-        assert_invariant();
-    }
-
-    /*!
-    @brief create a JSON value from an existing one
-
-    This is a constructor for existing @ref basic_json types.
-    It does not hijack copy/move constructors, since the parameter has different
-    template arguments than the current ones.
-
-    The constructor tries to convert the internal @ref m_value of the parameter.
-
-    @tparam BasicJsonType a type such that:
-    - @a BasicJsonType is a @ref basic_json type.
-    - @a BasicJsonType has different template arguments than @ref basic_json_t.
-
-    @param[in] val the @ref basic_json value to be converted.
-
-    @complexity Usually linear in the size of the passed @a val, also
-                depending on the implementation of the called `to_json()`
-                method.
-
-    @exceptionsafety Depends on the called constructor. For types directly
-    supported by the library (i.e., all types for which no `to_json()` function
-    was provided), strong guarantee holds: if an exception is thrown, there are
-    no changes to any JSON value.
-
-    @since version 3.2.0
-    */
-    template < typename BasicJsonType,
-               detail::enable_if_t <
-                   detail::is_basic_json<BasicJsonType>::value&& !std::is_same<basic_json, BasicJsonType>::value, int > = 0 >
-    basic_json(const BasicJsonType& val)
-    {
-        using other_boolean_t = typename BasicJsonType::boolean_t;
-        using other_number_float_t = typename BasicJsonType::number_float_t;
-        using other_number_integer_t = typename BasicJsonType::number_integer_t;
-        using other_number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-        using other_string_t = typename BasicJsonType::string_t;
-        using other_object_t = typename BasicJsonType::object_t;
-        using other_array_t = typename BasicJsonType::array_t;
-        using other_binary_t = typename BasicJsonType::binary_t;
-
-        switch (val.type())
-        {
-            case value_t::boolean:
-                JSONSerializer<other_boolean_t>::to_json(*this, val.template get<other_boolean_t>());
-                break;
-            case value_t::number_float:
-                JSONSerializer<other_number_float_t>::to_json(*this, val.template get<other_number_float_t>());
-                break;
-            case value_t::number_integer:
-                JSONSerializer<other_number_integer_t>::to_json(*this, val.template get<other_number_integer_t>());
-                break;
-            case value_t::number_unsigned:
-                JSONSerializer<other_number_unsigned_t>::to_json(*this, val.template get<other_number_unsigned_t>());
-                break;
-            case value_t::string:
-                JSONSerializer<other_string_t>::to_json(*this, val.template get_ref<const other_string_t&>());
-                break;
-            case value_t::object:
-                JSONSerializer<other_object_t>::to_json(*this, val.template get_ref<const other_object_t&>());
-                break;
-            case value_t::array:
-                JSONSerializer<other_array_t>::to_json(*this, val.template get_ref<const other_array_t&>());
-                break;
-            case value_t::binary:
-                JSONSerializer<other_binary_t>::to_json(*this, val.template get_ref<const other_binary_t&>());
-                break;
-            case value_t::null:
-                *this = nullptr;
-                break;
-            case value_t::discarded:
-                m_type = value_t::discarded;
-                break;
-            default:            // LCOV_EXCL_LINE
-                JSON_ASSERT(false);  // LCOV_EXCL_LINE
-        }
-        assert_invariant();
-    }
-
-    /*!
-    @brief create a container (array or object) from an initializer list
-
-    Creates a JSON value of type array or object from the passed initializer
-    list @a init. In case @a type_deduction is `true` (default), the type of
-    the JSON value to be created is deducted from the initializer list @a init
-    according to the following rules:
-
-    1. If the list is empty, an empty JSON object value `{}` is created.
-    2. If the list consists of pairs whose first element is a string, a JSON
-       object value is created where the first elements of the pairs are
-       treated as keys and the second elements are as values.
-    3. In all other cases, an array is created.
-
-    The rules aim to create the best fit between a C++ initializer list and
-    JSON values. The rationale is as follows:
-
-    1. The empty initializer list is written as `{}` which is exactly an empty
-       JSON object.
-    2. C++ has no way of describing mapped types other than to list a list of
-       pairs. As JSON requires that keys must be of type string, rule 2 is the
-       weakest constraint one can pose on initializer lists to interpret them
-       as an object.
-    3. In all other cases, the initializer list could not be interpreted as
-       JSON object type, so interpreting it as JSON array type is safe.
-
-    With the rules described above, the following JSON values cannot be
-    expressed by an initializer list:
-
-    - the empty array (`[]`): use @ref array(initializer_list_t)
-      with an empty initializer list in this case
-    - arrays whose elements satisfy rule 2: use @ref
-      array(initializer_list_t) with the same initializer list
-      in this case
-
-    @note When used without parentheses around an empty initializer list, @ref
-    basic_json() is called instead of this function, yielding the JSON null
-    value.
-
-    @param[in] init  initializer list with JSON values
-
-    @param[in] type_deduction internal parameter; when set to `true`, the type
-    of the JSON value is deducted from the initializer list @a init; when set
-    to `false`, the type provided via @a manual_type is forced. This mode is
-    used by the functions @ref array(initializer_list_t) and
-    @ref object(initializer_list_t).
-
-    @param[in] manual_type internal parameter; when @a type_deduction is set
-    to `false`, the created JSON value will use the provided type (only @ref
-    value_t::array and @ref value_t::object are valid); when @a type_deduction
-    is set to `true`, this parameter has no effect
-
-    @throw type_error.301 if @a type_deduction is `false`, @a manual_type is
-    `value_t::object`, but @a init contains an element which is not a pair
-    whose first element is a string. In this case, the constructor could not
-    create an object. If @a type_deduction would have be `true`, an array
-    would have been created. See @ref object(initializer_list_t)
-    for an example.
-
-    @complexity Linear in the size of the initializer list @a init.
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes to any JSON value.
-
-    @liveexample{The example below shows how JSON values are created from
-    initializer lists.,basic_json__list_init_t}
-
-    @sa @ref array(initializer_list_t) -- create a JSON array
-    value from an initializer list
-    @sa @ref object(initializer_list_t) -- create a JSON object
-    value from an initializer list
-
-    @since version 1.0.0
-    */
-    basic_json(initializer_list_t init,
-               bool type_deduction = true,
-               value_t manual_type = value_t::array)
-    {
-        // check if each element is an array with two elements whose first
-        // element is a string
-        bool is_an_object = std::all_of(init.begin(), init.end(),
-                                        [](const detail::json_ref<basic_json>& element_ref)
-        {
-            return element_ref->is_array() && element_ref->size() == 2 && (*element_ref)[0].is_string();
-        });
-
-        // adjust type if type deduction is not wanted
-        if (!type_deduction)
-        {
-            // if array is wanted, do not create an object though possible
-            if (manual_type == value_t::array)
-            {
-                is_an_object = false;
-            }
-
-            // if object is wanted but impossible, throw an exception
-            if (JSON_HEDLEY_UNLIKELY(manual_type == value_t::object && !is_an_object))
-            {
-                JSON_THROW(type_error::create(301, "cannot create object from initializer list"));
-            }
-        }
-
-        if (is_an_object)
-        {
-            // the initializer list is a list of pairs -> create object
-            m_type = value_t::object;
-            m_value = value_t::object;
-
-            std::for_each(init.begin(), init.end(), [this](const detail::json_ref<basic_json>& element_ref)
-            {
-                auto element = element_ref.moved_or_copied();
-                m_value.object->emplace(
-                    std::move(*((*element.m_value.array)[0].m_value.string)),
-                    std::move((*element.m_value.array)[1]));
-            });
-        }
-        else
-        {
-            // the initializer list describes an array -> create array
-            m_type = value_t::array;
-            m_value.array = create<array_t>(init.begin(), init.end());
-        }
-
-        assert_invariant();
-    }
-
-    /*!
-    @brief explicitly create a binary array (without subtype)
-
-    Creates a JSON binary array value from a given binary container. Binary
-    values are part of various binary formats, such as CBOR, MessagePack, and
-    BSON. This constructor is used to create a value for serialization to those
-    formats.
-
-    @note Note, this function exists because of the difficulty in correctly
-    specifying the correct template overload in the standard value ctor, as both
-    JSON arrays and JSON binary arrays are backed with some form of a
-    `std::vector`. Because JSON binary arrays are a non-standard extension it
-    was decided that it would be best to prevent automatic initialization of a
-    binary array type, for backwards compatibility and so it does not happen on
-    accident.
-
-    @param[in] init container containing bytes to use as binary type
-
-    @return JSON binary array value
-
-    @complexity Linear in the size of @a init.
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes to any JSON value.
-
-    @since version 3.8.0
-    */
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json binary(const typename binary_t::container_type& init)
-    {
-        auto res = basic_json();
-        res.m_type = value_t::binary;
-        res.m_value = init;
-        return res;
-    }
-
-    /*!
-    @brief explicitly create a binary array (with subtype)
-
-    Creates a JSON binary array value from a given binary container. Binary
-    values are part of various binary formats, such as CBOR, MessagePack, and
-    BSON. This constructor is used to create a value for serialization to those
-    formats.
-
-    @note Note, this function exists because of the difficulty in correctly
-    specifying the correct template overload in the standard value ctor, as both
-    JSON arrays and JSON binary arrays are backed with some form of a
-    `std::vector`. Because JSON binary arrays are a non-standard extension it
-    was decided that it would be best to prevent automatic initialization of a
-    binary array type, for backwards compatibility and so it does not happen on
-    accident.
-
-    @param[in] init container containing bytes to use as binary type
-    @param[in] subtype subtype to use in MessagePack and BSON
-
-    @return JSON binary array value
-
-    @complexity Linear in the size of @a init.
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes to any JSON value.
-
-    @since version 3.8.0
-    */
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json binary(const typename binary_t::container_type& init, std::uint8_t subtype)
-    {
-        auto res = basic_json();
-        res.m_type = value_t::binary;
-        res.m_value = binary_t(init, subtype);
-        return res;
-    }
-
-    /// @copydoc binary(const typename binary_t::container_type&)
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json binary(typename binary_t::container_type&& init)
-    {
-        auto res = basic_json();
-        res.m_type = value_t::binary;
-        res.m_value = std::move(init);
-        return res;
-    }
-
-    /// @copydoc binary(const typename binary_t::container_type&, std::uint8_t)
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json binary(typename binary_t::container_type&& init, std::uint8_t subtype)
-    {
-        auto res = basic_json();
-        res.m_type = value_t::binary;
-        res.m_value = binary_t(std::move(init), subtype);
-        return res;
-    }
-
-    /*!
-    @brief explicitly create an array from an initializer list
-
-    Creates a JSON array value from a given initializer list. That is, given a
-    list of values `a, b, c`, creates the JSON value `[a, b, c]`. If the
-    initializer list is empty, the empty array `[]` is created.
-
-    @note This function is only needed to express two edge cases that cannot
-    be realized with the initializer list constructor (@ref
-    basic_json(initializer_list_t, bool, value_t)). These cases
-    are:
-    1. creating an array whose elements are all pairs whose first element is a
-    string -- in this case, the initializer list constructor would create an
-    object, taking the first elements as keys
-    2. creating an empty array -- passing the empty initializer list to the
-    initializer list constructor yields an empty object
-
-    @param[in] init  initializer list with JSON values to create an array from
-    (optional)
-
-    @return JSON array value
-
-    @complexity Linear in the size of @a init.
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes to any JSON value.
-
-    @liveexample{The following code shows an example for the `array`
-    function.,array}
-
-    @sa @ref basic_json(initializer_list_t, bool, value_t) --
-    create a JSON value from an initializer list
-    @sa @ref object(initializer_list_t) -- create a JSON object
-    value from an initializer list
-
-    @since version 1.0.0
-    */
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json array(initializer_list_t init = {})
-    {
-        return basic_json(init, false, value_t::array);
-    }
-
-    /*!
-    @brief explicitly create an object from an initializer list
-
-    Creates a JSON object value from a given initializer list. The initializer
-    lists elements must be pairs, and their first elements must be strings. If
-    the initializer list is empty, the empty object `{}` is created.
-
-    @note This function is only added for symmetry reasons. In contrast to the
-    related function @ref array(initializer_list_t), there are
-    no cases which can only be expressed by this function. That is, any
-    initializer list @a init can also be passed to the initializer list
-    constructor @ref basic_json(initializer_list_t, bool, value_t).
-
-    @param[in] init  initializer list to create an object from (optional)
-
-    @return JSON object value
-
-    @throw type_error.301 if @a init is not a list of pairs whose first
-    elements are strings. In this case, no object can be created. When such a
-    value is passed to @ref basic_json(initializer_list_t, bool, value_t),
-    an array would have been created from the passed initializer list @a init.
-    See example below.
-
-    @complexity Linear in the size of @a init.
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes to any JSON value.
-
-    @liveexample{The following code shows an example for the `object`
-    function.,object}
-
-    @sa @ref basic_json(initializer_list_t, bool, value_t) --
-    create a JSON value from an initializer list
-    @sa @ref array(initializer_list_t) -- create a JSON array
-    value from an initializer list
-
-    @since version 1.0.0
-    */
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json object(initializer_list_t init = {})
-    {
-        return basic_json(init, false, value_t::object);
-    }
-
-    /*!
-    @brief construct an array with count copies of given value
-
-    Constructs a JSON array value by creating @a cnt copies of a passed value.
-    In case @a cnt is `0`, an empty array is created.
-
-    @param[in] cnt  the number of JSON copies of @a val to create
-    @param[in] val  the JSON value to copy
-
-    @post `std::distance(begin(),end()) == cnt` holds.
-
-    @complexity Linear in @a cnt.
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes to any JSON value.
-
-    @liveexample{The following code shows examples for the @ref
-    basic_json(size_type\, const basic_json&)
-    constructor.,basic_json__size_type_basic_json}
-
-    @since version 1.0.0
-    */
-    basic_json(size_type cnt, const basic_json& val)
-        : m_type(value_t::array)
-    {
-        m_value.array = create<array_t>(cnt, val);
-        assert_invariant();
-    }
-
-    /*!
-    @brief construct a JSON container given an iterator range
-
-    Constructs the JSON value with the contents of the range `[first, last)`.
-    The semantics depends on the different types a JSON value can have:
-    - In case of a null type, invalid_iterator.206 is thrown.
-    - In case of other primitive types (number, boolean, or string), @a first
-      must be `begin()` and @a last must be `end()`. In this case, the value is
-      copied. Otherwise, invalid_iterator.204 is thrown.
-    - In case of structured types (array, object), the constructor behaves as
-      similar versions for `std::vector` or `std::map`; that is, a JSON array
-      or object is constructed from the values in the range.
-
-    @tparam InputIT an input iterator type (@ref iterator or @ref
-    const_iterator)
-
-    @param[in] first begin of the range to copy from (included)
-    @param[in] last end of the range to copy from (excluded)
-
-    @pre Iterators @a first and @a last must be initialized. **This
-         precondition is enforced with an assertion (see warning).** If
-         assertions are switched off, a violation of this precondition yields
-         undefined behavior.
-
-    @pre Range `[first, last)` is valid. Usually, this precondition cannot be
-         checked efficiently. Only certain edge cases are detected; see the
-         description of the exceptions below. A violation of this precondition
-         yields undefined behavior.
-
-    @warning A precondition is enforced with a runtime assertion that will
-             result in calling `std::abort` if this precondition is not met.
-             Assertions can be disabled by defining `NDEBUG` at compile time.
-             See https://en.cppreference.com/w/cpp/error/assert for more
-             information.
-
-    @throw invalid_iterator.201 if iterators @a first and @a last are not
-    compatible (i.e., do not belong to the same JSON value). In this case,
-    the range `[first, last)` is undefined.
-    @throw invalid_iterator.204 if iterators @a first and @a last belong to a
-    primitive type (number, boolean, or string), but @a first does not point
-    to the first element any more. In this case, the range `[first, last)` is
-    undefined. See example code below.
-    @throw invalid_iterator.206 if iterators @a first and @a last belong to a
-    null value. In this case, the range `[first, last)` is undefined.
-
-    @complexity Linear in distance between @a first and @a last.
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes to any JSON value.
-
-    @liveexample{The example below shows several ways to create JSON values by
-    specifying a subrange with iterators.,basic_json__InputIt_InputIt}
-
-    @since version 1.0.0
-    */
-    template < class InputIT, typename std::enable_if <
-                   std::is_same<InputIT, typename basic_json_t::iterator>::value ||
-                   std::is_same<InputIT, typename basic_json_t::const_iterator>::value, int >::type = 0 >
-    basic_json(InputIT first, InputIT last)
-    {
-        JSON_ASSERT(first.m_object != nullptr);
-        JSON_ASSERT(last.m_object != nullptr);
-
-        // make sure iterator fits the current value
-        if (JSON_HEDLEY_UNLIKELY(first.m_object != last.m_object))
-        {
-            JSON_THROW(invalid_iterator::create(201, "iterators are not compatible"));
-        }
-
-        // copy type from first iterator
-        m_type = first.m_object->m_type;
-
-        // check if iterator range is complete for primitive values
-        switch (m_type)
-        {
-            case value_t::boolean:
-            case value_t::number_float:
-            case value_t::number_integer:
-            case value_t::number_unsigned:
-            case value_t::string:
-            {
-                if (JSON_HEDLEY_UNLIKELY(!first.m_it.primitive_iterator.is_begin()
-                                         || !last.m_it.primitive_iterator.is_end()))
-                {
-                    JSON_THROW(invalid_iterator::create(204, "iterators out of range"));
-                }
-                break;
-            }
-
-            default:
-                break;
-        }
-
-        switch (m_type)
-        {
-            case value_t::number_integer:
-            {
-                m_value.number_integer = first.m_object->m_value.number_integer;
-                break;
-            }
-
-            case value_t::number_unsigned:
-            {
-                m_value.number_unsigned = first.m_object->m_value.number_unsigned;
-                break;
-            }
-
-            case value_t::number_float:
-            {
-                m_value.number_float = first.m_object->m_value.number_float;
-                break;
-            }
-
-            case value_t::boolean:
-            {
-                m_value.boolean = first.m_object->m_value.boolean;
-                break;
-            }
-
-            case value_t::string:
-            {
-                m_value = *first.m_object->m_value.string;
-                break;
-            }
-
-            case value_t::object:
-            {
-                m_value.object = create<object_t>(first.m_it.object_iterator,
-                                                  last.m_it.object_iterator);
-                break;
-            }
-
-            case value_t::array:
-            {
-                m_value.array = create<array_t>(first.m_it.array_iterator,
-                                                last.m_it.array_iterator);
-                break;
-            }
-
-            case value_t::binary:
-            {
-                m_value = *first.m_object->m_value.binary;
-                break;
-            }
-
-            default:
-                JSON_THROW(invalid_iterator::create(206, "cannot construct with iterators from " +
-                                                    std::string(first.m_object->type_name())));
-        }
-
-        assert_invariant();
-    }
-
-
-    ///////////////////////////////////////
-    // other constructors and destructor //
-    ///////////////////////////////////////
-
-    template<typename JsonRef,
-             detail::enable_if_t<detail::conjunction<detail::is_json_ref<JsonRef>,
-                                 std::is_same<typename JsonRef::value_type, basic_json>>::value, int> = 0 >
-    basic_json(const JsonRef& ref) : basic_json(ref.moved_or_copied()) {}
-
-    /*!
-    @brief copy constructor
-
-    Creates a copy of a given JSON value.
-
-    @param[in] other  the JSON value to copy
-
-    @post `*this == other`
-
-    @complexity Linear in the size of @a other.
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes to any JSON value.
-
-    @requirement This function helps `basic_json` satisfying the
-    [Container](https://en.cppreference.com/w/cpp/named_req/Container)
-    requirements:
-    - The complexity is linear.
-    - As postcondition, it holds: `other == basic_json(other)`.
-
-    @liveexample{The following code shows an example for the copy
-    constructor.,basic_json__basic_json}
-
-    @since version 1.0.0
-    */
-    basic_json(const basic_json& other)
-        : m_type(other.m_type)
-    {
-        // check of passed value is valid
-        other.assert_invariant();
-
-        switch (m_type)
-        {
-            case value_t::object:
-            {
-                m_value = *other.m_value.object;
-                break;
-            }
-
-            case value_t::array:
-            {
-                m_value = *other.m_value.array;
-                break;
-            }
-
-            case value_t::string:
-            {
-                m_value = *other.m_value.string;
-                break;
-            }
-
-            case value_t::boolean:
-            {
-                m_value = other.m_value.boolean;
-                break;
-            }
-
-            case value_t::number_integer:
-            {
-                m_value = other.m_value.number_integer;
-                break;
-            }
-
-            case value_t::number_unsigned:
-            {
-                m_value = other.m_value.number_unsigned;
-                break;
-            }
-
-            case value_t::number_float:
-            {
-                m_value = other.m_value.number_float;
-                break;
-            }
-
-            case value_t::binary:
-            {
-                m_value = *other.m_value.binary;
-                break;
-            }
-
-            default:
-                break;
-        }
-
-        assert_invariant();
-    }
-
-    /*!
-    @brief move constructor
-
-    Move constructor. Constructs a JSON value with the contents of the given
-    value @a other using move semantics. It "steals" the resources from @a
-    other and leaves it as JSON null value.
-
-    @param[in,out] other  value to move to this object
-
-    @post `*this` has the same value as @a other before the call.
-    @post @a other is a JSON null value.
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this constructor never throws
-    exceptions.
-
-    @requirement This function helps `basic_json` satisfying the
-    [MoveConstructible](https://en.cppreference.com/w/cpp/named_req/MoveConstructible)
-    requirements.
-
-    @liveexample{The code below shows the move constructor explicitly called
-    via std::move.,basic_json__moveconstructor}
-
-    @since version 1.0.0
-    */
-    basic_json(basic_json&& other) noexcept
-        : m_type(std::move(other.m_type)),
-          m_value(std::move(other.m_value))
-    {
-        // check that passed value is valid
-        other.assert_invariant();
-
-        // invalidate payload
-        other.m_type = value_t::null;
-        other.m_value = {};
-
-        assert_invariant();
-    }
-
-    /*!
-    @brief copy assignment
-
-    Copy assignment operator. Copies a JSON value via the "copy and swap"
-    strategy: It is expressed in terms of the copy constructor, destructor,
-    and the `swap()` member function.
-
-    @param[in] other  value to copy from
-
-    @complexity Linear.
-
-    @requirement This function helps `basic_json` satisfying the
-    [Container](https://en.cppreference.com/w/cpp/named_req/Container)
-    requirements:
-    - The complexity is linear.
-
-    @liveexample{The code below shows and example for the copy assignment. It
-    creates a copy of value `a` which is then swapped with `b`. Finally\, the
-    copy of `a` (which is the null value after the swap) is
-    destroyed.,basic_json__copyassignment}
-
-    @since version 1.0.0
-    */
-    basic_json& operator=(basic_json other) noexcept (
-        std::is_nothrow_move_constructible<value_t>::value&&
-        std::is_nothrow_move_assignable<value_t>::value&&
-        std::is_nothrow_move_constructible<json_value>::value&&
-        std::is_nothrow_move_assignable<json_value>::value
-    )
-    {
-        // check that passed value is valid
-        other.assert_invariant();
-
-        using std::swap;
-        swap(m_type, other.m_type);
-        swap(m_value, other.m_value);
-
-        assert_invariant();
-        return *this;
-    }
-
-    /*!
-    @brief destructor
-
-    Destroys the JSON value and frees all allocated memory.
-
-    @complexity Linear.
-
-    @requirement This function helps `basic_json` satisfying the
-    [Container](https://en.cppreference.com/w/cpp/named_req/Container)
-    requirements:
-    - The complexity is linear.
-    - All stored elements are destroyed and all memory is freed.
-
-    @since version 1.0.0
-    */
-    ~basic_json() noexcept
-    {
-        assert_invariant();
-        m_value.destroy(m_type);
-    }
-
-    /// @}
-
-  public:
-    ///////////////////////
-    // object inspection //
-    ///////////////////////
-
-    /// @name object inspection
-    /// Functions to inspect the type of a JSON value.
-    /// @{
-
-    /*!
-    @brief serialization
-
-    Serialization function for JSON values. The function tries to mimic
-    Python's `json.dumps()` function, and currently supports its @a indent
-    and @a ensure_ascii parameters.
-
-    @param[in] indent If indent is nonnegative, then array elements and object
-    members will be pretty-printed with that indent level. An indent level of
-    `0` will only insert newlines. `-1` (the default) selects the most compact
-    representation.
-    @param[in] indent_char The character to use for indentation if @a indent is
-    greater than `0`. The default is ` ` (space).
-    @param[in] ensure_ascii If @a ensure_ascii is true, all non-ASCII characters
-    in the output are escaped with `\uXXXX` sequences, and the result consists
-    of ASCII characters only.
-    @param[in] error_handler  how to react on decoding errors; there are three
-    possible values: `strict` (throws and exception in case a decoding error
-    occurs; default), `replace` (replace invalid UTF-8 sequences with U+FFFD),
-    and `ignore` (ignore invalid UTF-8 sequences during serialization; all
-    bytes are copied to the output unchanged).
-
-    @return string containing the serialization of the JSON value
-
-    @throw type_error.316 if a string stored inside the JSON value is not
-                          UTF-8 encoded and @a error_handler is set to strict
-
-    @note Binary values are serialized as object containing two keys:
-      - "bytes": an array of bytes as integers
-      - "subtype": the subtype as integer or "null" if the binary has no subtype
-
-    @complexity Linear.
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes in the JSON value.
-
-    @liveexample{The following example shows the effect of different @a indent\,
-    @a indent_char\, and @a ensure_ascii parameters to the result of the
-    serialization.,dump}
-
-    @see https://docs.python.org/2/library/json.html#json.dump
-
-    @since version 1.0.0; indentation character @a indent_char, option
-           @a ensure_ascii and exceptions added in version 3.0.0; error
-           handlers added in version 3.4.0; serialization of binary values added
-           in version 3.8.0.
-    */
-    string_t dump(const int indent = -1,
-                  const char indent_char = ' ',
-                  const bool ensure_ascii = false,
-                  const error_handler_t error_handler = error_handler_t::strict) const
-    {
-        string_t result;
-        serializer s(detail::output_adapter<char, string_t>(result), indent_char, error_handler);
-
-        if (indent >= 0)
-        {
-            s.dump(*this, true, ensure_ascii, static_cast<unsigned int>(indent));
-        }
-        else
-        {
-            s.dump(*this, false, ensure_ascii, 0);
-        }
-
-        return result;
-    }
-
-    /*!
-    @brief return the type of the JSON value (explicit)
-
-    Return the type of the JSON value as a value from the @ref value_t
-    enumeration.
-
-    @return the type of the JSON value
-            Value type                | return value
-            ------------------------- | -------------------------
-            null                      | value_t::null
-            boolean                   | value_t::boolean
-            string                    | value_t::string
-            number (integer)          | value_t::number_integer
-            number (unsigned integer) | value_t::number_unsigned
-            number (floating-point)   | value_t::number_float
-            object                    | value_t::object
-            array                     | value_t::array
-            binary                    | value_t::binary
-            discarded                 | value_t::discarded
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @liveexample{The following code exemplifies `type()` for all JSON
-    types.,type}
-
-    @sa @ref operator value_t() -- return the type of the JSON value (implicit)
-    @sa @ref type_name() -- return the type as string
-
-    @since version 1.0.0
-    */
-    constexpr value_t type() const noexcept
-    {
-        return m_type;
-    }
-
-    /*!
-    @brief return whether type is primitive
-
-    This function returns true if and only if the JSON type is primitive
-    (string, number, boolean, or null).
-
-    @return `true` if type is primitive (string, number, boolean, or null),
-    `false` otherwise.
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @liveexample{The following code exemplifies `is_primitive()` for all JSON
-    types.,is_primitive}
-
-    @sa @ref is_structured() -- returns whether JSON value is structured
-    @sa @ref is_null() -- returns whether JSON value is `null`
-    @sa @ref is_string() -- returns whether JSON value is a string
-    @sa @ref is_boolean() -- returns whether JSON value is a boolean
-    @sa @ref is_number() -- returns whether JSON value is a number
-    @sa @ref is_binary() -- returns whether JSON value is a binary array
-
-    @since version 1.0.0
-    */
-    constexpr bool is_primitive() const noexcept
-    {
-        return is_null() || is_string() || is_boolean() || is_number() || is_binary();
-    }
-
-    /*!
-    @brief return whether type is structured
-
-    This function returns true if and only if the JSON type is structured
-    (array or object).
-
-    @return `true` if type is structured (array or object), `false` otherwise.
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @liveexample{The following code exemplifies `is_structured()` for all JSON
-    types.,is_structured}
-
-    @sa @ref is_primitive() -- returns whether value is primitive
-    @sa @ref is_array() -- returns whether value is an array
-    @sa @ref is_object() -- returns whether value is an object
-
-    @since version 1.0.0
-    */
-    constexpr bool is_structured() const noexcept
-    {
-        return is_array() || is_object();
-    }
-
-    /*!
-    @brief return whether value is null
-
-    This function returns true if and only if the JSON value is null.
-
-    @return `true` if type is null, `false` otherwise.
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @liveexample{The following code exemplifies `is_null()` for all JSON
-    types.,is_null}
-
-    @since version 1.0.0
-    */
-    constexpr bool is_null() const noexcept
-    {
-        return m_type == value_t::null;
-    }
-
-    /*!
-    @brief return whether value is a boolean
-
-    This function returns true if and only if the JSON value is a boolean.
-
-    @return `true` if type is boolean, `false` otherwise.
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @liveexample{The following code exemplifies `is_boolean()` for all JSON
-    types.,is_boolean}
-
-    @since version 1.0.0
-    */
-    constexpr bool is_boolean() const noexcept
-    {
-        return m_type == value_t::boolean;
-    }
-
-    /*!
-    @brief return whether value is a number
-
-    This function returns true if and only if the JSON value is a number. This
-    includes both integer (signed and unsigned) and floating-point values.
-
-    @return `true` if type is number (regardless whether integer, unsigned
-    integer or floating-type), `false` otherwise.
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @liveexample{The following code exemplifies `is_number()` for all JSON
-    types.,is_number}
-
-    @sa @ref is_number_integer() -- check if value is an integer or unsigned
-    integer number
-    @sa @ref is_number_unsigned() -- check if value is an unsigned integer
-    number
-    @sa @ref is_number_float() -- check if value is a floating-point number
-
-    @since version 1.0.0
-    */
-    constexpr bool is_number() const noexcept
-    {
-        return is_number_integer() || is_number_float();
-    }
-
-    /*!
-    @brief return whether value is an integer number
-
-    This function returns true if and only if the JSON value is a signed or
-    unsigned integer number. This excludes floating-point values.
-
-    @return `true` if type is an integer or unsigned integer number, `false`
-    otherwise.
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @liveexample{The following code exemplifies `is_number_integer()` for all
-    JSON types.,is_number_integer}
-
-    @sa @ref is_number() -- check if value is a number
-    @sa @ref is_number_unsigned() -- check if value is an unsigned integer
-    number
-    @sa @ref is_number_float() -- check if value is a floating-point number
-
-    @since version 1.0.0
-    */
-    constexpr bool is_number_integer() const noexcept
-    {
-        return m_type == value_t::number_integer || m_type == value_t::number_unsigned;
-    }
-
-    /*!
-    @brief return whether value is an unsigned integer number
-
-    This function returns true if and only if the JSON value is an unsigned
-    integer number. This excludes floating-point and signed integer values.
-
-    @return `true` if type is an unsigned integer number, `false` otherwise.
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @liveexample{The following code exemplifies `is_number_unsigned()` for all
-    JSON types.,is_number_unsigned}
-
-    @sa @ref is_number() -- check if value is a number
-    @sa @ref is_number_integer() -- check if value is an integer or unsigned
-    integer number
-    @sa @ref is_number_float() -- check if value is a floating-point number
-
-    @since version 2.0.0
-    */
-    constexpr bool is_number_unsigned() const noexcept
-    {
-        return m_type == value_t::number_unsigned;
-    }
-
-    /*!
-    @brief return whether value is a floating-point number
-
-    This function returns true if and only if the JSON value is a
-    floating-point number. This excludes signed and unsigned integer values.
-
-    @return `true` if type is a floating-point number, `false` otherwise.
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @liveexample{The following code exemplifies `is_number_float()` for all
-    JSON types.,is_number_float}
-
-    @sa @ref is_number() -- check if value is number
-    @sa @ref is_number_integer() -- check if value is an integer number
-    @sa @ref is_number_unsigned() -- check if value is an unsigned integer
-    number
-
-    @since version 1.0.0
-    */
-    constexpr bool is_number_float() const noexcept
-    {
-        return m_type == value_t::number_float;
-    }
-
-    /*!
-    @brief return whether value is an object
-
-    This function returns true if and only if the JSON value is an object.
-
-    @return `true` if type is object, `false` otherwise.
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @liveexample{The following code exemplifies `is_object()` for all JSON
-    types.,is_object}
-
-    @since version 1.0.0
-    */
-    constexpr bool is_object() const noexcept
-    {
-        return m_type == value_t::object;
-    }
-
-    /*!
-    @brief return whether value is an array
-
-    This function returns true if and only if the JSON value is an array.
-
-    @return `true` if type is array, `false` otherwise.
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @liveexample{The following code exemplifies `is_array()` for all JSON
-    types.,is_array}
-
-    @since version 1.0.0
-    */
-    constexpr bool is_array() const noexcept
-    {
-        return m_type == value_t::array;
-    }
-
-    /*!
-    @brief return whether value is a string
-
-    This function returns true if and only if the JSON value is a string.
-
-    @return `true` if type is string, `false` otherwise.
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @liveexample{The following code exemplifies `is_string()` for all JSON
-    types.,is_string}
-
-    @since version 1.0.0
-    */
-    constexpr bool is_string() const noexcept
-    {
-        return m_type == value_t::string;
-    }
-
-    /*!
-    @brief return whether value is a binary array
-
-    This function returns true if and only if the JSON value is a binary array.
-
-    @return `true` if type is binary array, `false` otherwise.
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @liveexample{The following code exemplifies `is_binary()` for all JSON
-    types.,is_binary}
-
-    @since version 3.8.0
-    */
-    constexpr bool is_binary() const noexcept
-    {
-        return m_type == value_t::binary;
-    }
-
-    /*!
-    @brief return whether value is discarded
-
-    This function returns true if and only if the JSON value was discarded
-    during parsing with a callback function (see @ref parser_callback_t).
-
-    @note This function will always be `false` for JSON values after parsing.
-    That is, discarded values can only occur during parsing, but will be
-    removed when inside a structured value or replaced by null in other cases.
-
-    @return `true` if type is discarded, `false` otherwise.
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @liveexample{The following code exemplifies `is_discarded()` for all JSON
-    types.,is_discarded}
-
-    @since version 1.0.0
-    */
-    constexpr bool is_discarded() const noexcept
-    {
-        return m_type == value_t::discarded;
-    }
-
-    /*!
-    @brief return the type of the JSON value (implicit)
-
-    Implicitly return the type of the JSON value as a value from the @ref
-    value_t enumeration.
-
-    @return the type of the JSON value
-
-    @complexity Constant.
-
-    @exceptionsafety No-throw guarantee: this member function never throws
-    exceptions.
-
-    @liveexample{The following code exemplifies the @ref value_t operator for
-    all JSON types.,operator__value_t}
-
-    @sa @ref type() -- return the type of the JSON value (explicit)
-    @sa @ref type_name() -- return the type as string
-
-    @since version 1.0.0
-    */
-    constexpr operator value_t() const noexcept
-    {
-        return m_type;
-    }
-
-    /// @}
-
-  private:
-    //////////////////
-    // value access //
-    //////////////////
-
-    /// get a boolean (explicit)
-    boolean_t get_impl(boolean_t* /*unused*/) const
-    {
-        if (JSON_HEDLEY_LIKELY(is_boolean()))
-        {
-            return m_value.boolean;
-        }
-
-        JSON_THROW(type_error::create(302, "type must be boolean, but is " + std::string(type_name())));
-    }
-
-    /// get a pointer to the value (object)
-    object_t* get_impl_ptr(object_t* /*unused*/) noexcept
-    {
-        return is_object() ? m_value.object : nullptr;
-    }
-
-    /// get a pointer to the value (object)
-    constexpr const object_t* get_impl_ptr(const object_t* /*unused*/) const noexcept
-    {
-        return is_object() ? m_value.object : nullptr;
-    }
-
-    /// get a pointer to the value (array)
-    array_t* get_impl_ptr(array_t* /*unused*/) noexcept
-    {
-        return is_array() ? m_value.array : nullptr;
-    }
-
-    /// get a pointer to the value (array)
-    constexpr const array_t* get_impl_ptr(const array_t* /*unused*/) const noexcept
-    {
-        return is_array() ? m_value.array : nullptr;
-    }
-
-    /// get a pointer to the value (string)
-    string_t* get_impl_ptr(string_t* /*unused*/) noexcept
-    {
-        return is_string() ? m_value.string : nullptr;
-    }
-
-    /// get a pointer to the value (string)
-    constexpr const string_t* get_impl_ptr(const string_t* /*unused*/) const noexcept
-    {
-        return is_string() ? m_value.string : nullptr;
-    }
-
-    /// get a pointer to the value (boolean)
-    boolean_t* get_impl_ptr(boolean_t* /*unused*/) noexcept
-    {
-        return is_boolean() ? &m_value.boolean : nullptr;
-    }
-
-    /// get a pointer to the value (boolean)
-    constexpr const boolean_t* get_impl_ptr(const boolean_t* /*unused*/) const noexcept
-    {
-        return is_boolean() ? &m_value.boolean : nullptr;
-    }
-
-    /// get a pointer to the value (integer number)
-    number_integer_t* get_impl_ptr(number_integer_t* /*unused*/) noexcept
-    {
-        return is_number_integer() ? &m_value.number_integer : nullptr;
-    }
-
-    /// get a pointer to the value (integer number)
-    constexpr const number_integer_t* get_impl_ptr(const number_integer_t* /*unused*/) const noexcept
-    {
-        return is_number_integer() ? &m_value.number_integer : nullptr;
-    }
-
-    /// get a pointer to the value (unsigned number)
-    number_unsigned_t* get_impl_ptr(number_unsigned_t* /*unused*/) noexcept
-    {
-        return is_number_unsigned() ? &m_value.number_unsigned : nullptr;
-    }
-
-    /// get a pointer to the value (unsigned number)
-    constexpr const number_unsigned_t* get_impl_ptr(const number_unsigned_t* /*unused*/) const noexcept
-    {
-        return is_number_unsigned() ? &m_value.number_unsigned : nullptr;
-    }
-
-    /// get a pointer to the value (floating-point number)
-    number_float_t* get_impl_ptr(number_float_t* /*unused*/) noexcept
-    {
-        return is_number_float() ? &m_value.number_float : nullptr;
-    }
-
-    /// get a pointer to the value (floating-point number)
-    constexpr const number_float_t* get_impl_ptr(const number_float_t* /*unused*/) const noexcept
-    {
-        return is_number_float() ? &m_value.number_float : nullptr;
-    }
-
-    /// get a pointer to the value (binary)
-    binary_t* get_impl_ptr(binary_t* /*unused*/) noexcept
-    {
-        return is_binary() ? m_value.binary : nullptr;
-    }
-
-    /// get a pointer to the value (binary)
-    constexpr const binary_t* get_impl_ptr(const binary_t* /*unused*/) const noexcept
-    {
-        return is_binary() ? m_value.binary : nullptr;
-    }
-
-    /*!
-    @brief helper function to implement get_ref()
-
-    This function helps to implement get_ref() without code duplication for
-    const and non-const overloads
-
-    @tparam ThisType will be deduced as `basic_json` or `const basic_json`
-
-    @throw type_error.303 if ReferenceType does not match underlying value
-    type of the current JSON
-    */
-    template<typename ReferenceType, typename ThisType>
-    static ReferenceType get_ref_impl(ThisType& obj)
-    {
-        // delegate the call to get_ptr<>()
-        auto ptr = obj.template get_ptr<typename std::add_pointer<ReferenceType>::type>();
-
-        if (JSON_HEDLEY_LIKELY(ptr != nullptr))
-        {
-            return *ptr;
-        }
-
-        JSON_THROW(type_error::create(303, "incompatible ReferenceType for get_ref, actual type is " + std::string(obj.type_name())));
-    }
-
-  public:
-    /// @name value access
-    /// Direct access to the stored value of a JSON value.
-    /// @{
-
-    /*!
-    @brief get special-case overload
-
-    This overloads avoids a lot of template boilerplate, it can be seen as the
-    identity method
-
-    @tparam BasicJsonType == @ref basic_json
-
-    @return a copy of *this
-
-    @complexity Constant.
-
-    @since version 2.1.0
-    */
-    template<typename BasicJsonType, detail::enable_if_t<
-                 std::is_same<typename std::remove_const<BasicJsonType>::type, basic_json_t>::value,
-                 int> = 0>
-    basic_json get() const
-    {
-        return *this;
-    }
-
-    /*!
-    @brief get special-case overload
-
-    This overloads converts the current @ref basic_json in a different
-    @ref basic_json type
-
-    @tparam BasicJsonType == @ref basic_json
-
-    @return a copy of *this, converted into @tparam BasicJsonType
-
-    @complexity Depending on the implementation of the called `from_json()`
-                method.
-
-    @since version 3.2.0
-    */
-    template < typename BasicJsonType, detail::enable_if_t <
-                   !std::is_same<BasicJsonType, basic_json>::value&&
-                   detail::is_basic_json<BasicJsonType>::value, int > = 0 >
-    BasicJsonType get() const
-    {
-        return *this;
-    }
-
-    /*!
-    @brief get a value (explicit)
-
-    Explicit type conversion between the JSON value and a compatible value
-    which is [CopyConstructible](https://en.cppreference.com/w/cpp/named_req/CopyConstructible)
-    and [DefaultConstructible](https://en.cppreference.com/w/cpp/named_req/DefaultConstructible).
-    The value is converted by calling the @ref json_serializer<ValueType>
-    `from_json()` method.
-
-    The function is equivalent to executing
-    @code {.cpp}
-    ValueType ret;
-    JSONSerializer<ValueType>::from_json(*this, ret);
-    return ret;
-    @endcode
-
-    This overloads is chosen if:
-    - @a ValueType is not @ref basic_json,
-    - @ref json_serializer<ValueType> has a `from_json()` method of the form
-      `void from_json(const basic_json&, ValueType&)`, and
-    - @ref json_serializer<ValueType> does not have a `from_json()` method of
-      the form `ValueType from_json(const basic_json&)`
-
-    @tparam ValueTypeCV the provided value type
-    @tparam ValueType the returned value type
-
-    @return copy of the JSON value, converted to @a ValueType
-
-    @throw what @ref json_serializer<ValueType> `from_json()` method throws
-
-    @liveexample{The example below shows several conversions from JSON values
-    to other types. There a few things to note: (1) Floating-point numbers can
-    be converted to integers\, (2) A JSON array can be converted to a standard
-    `std::vector<short>`\, (3) A JSON object can be converted to C++
-    associative containers such as `std::unordered_map<std::string\,
-    json>`.,get__ValueType_const}
-
-    @since version 2.1.0
-    */
-    template < typename ValueTypeCV, typename ValueType = detail::uncvref_t<ValueTypeCV>,
-               detail::enable_if_t <
-                   !detail::is_basic_json<ValueType>::value &&
-                   detail::has_from_json<basic_json_t, ValueType>::value &&
-                   !detail::has_non_default_from_json<basic_json_t, ValueType>::value,
-                   int > = 0 >
-    ValueType get() const noexcept(noexcept(
-                                       JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>(), std::declval<ValueType&>())))
-    {
-        // we cannot static_assert on ValueTypeCV being non-const, because
-        // there is support for get<const basic_json_t>(), which is why we
-        // still need the uncvref
-        static_assert(!std::is_reference<ValueTypeCV>::value,
-                      "get() cannot be used with reference types, you might want to use get_ref()");
-        static_assert(std::is_default_constructible<ValueType>::value,
-                      "types must be DefaultConstructible when used with get()");
-
-        ValueType ret;
-        JSONSerializer<ValueType>::from_json(*this, ret);
-        return ret;
-    }
-
-    /*!
-    @brief get a value (explicit); special case
-
-    Explicit type conversion between the JSON value and a compatible value
-    which is **not** [CopyConstructible](https://en.cppreference.com/w/cpp/named_req/CopyConstructible)
-    and **not** [DefaultConstructible](https://en.cppreference.com/w/cpp/named_req/DefaultConstructible).
-    The value is converted by calling the @ref json_serializer<ValueType>
-    `from_json()` method.
-
-    The function is equivalent to executing
-    @code {.cpp}
-    return JSONSerializer<ValueTypeCV>::from_json(*this);
-    @endcode
-
-    This overloads is chosen if:
-    - @a ValueType is not @ref basic_json and
-    - @ref json_serializer<ValueType> has a `from_json()` method of the form
-      `ValueType from_json(const basic_json&)`
-
-    @note If @ref json_serializer<ValueType> has both overloads of
-    `from_json()`, this one is chosen.
-
-    @tparam ValueTypeCV the provided value type
-    @tparam ValueType the returned value type
-
-    @return copy of the JSON value, converted to @a ValueType
-
-    @throw what @ref json_serializer<ValueType> `from_json()` method throws
-
-    @since version 2.1.0
-    */
-    template < typename ValueTypeCV, typename ValueType = detail::uncvref_t<ValueTypeCV>,
-               detail::enable_if_t < !std::is_same<basic_json_t, ValueType>::value &&
-                                     detail::has_non_default_from_json<basic_json_t, ValueType>::value,
-                                     int > = 0 >
-    ValueType get() const noexcept(noexcept(
-                                       JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>())))
-    {
-        static_assert(!std::is_reference<ValueTypeCV>::value,
-                      "get() cannot be used with reference types, you might want to use get_ref()");
-        return JSONSerializer<ValueType>::from_json(*this);
-    }
-
-    /*!
-    @brief get a value (explicit)
-
-    Explicit type conversion between the JSON value and a compatible value.
-    The value is filled into the input parameter by calling the @ref json_serializer<ValueType>
-    `from_json()` method.
-
-    The function is equivalent to executing
-    @code {.cpp}
-    ValueType v;
-    JSONSerializer<ValueType>::from_json(*this, v);
-    @endcode
-
-    This overloads is chosen if:
-    - @a ValueType is not @ref basic_json,
-    - @ref json_serializer<ValueType> has a `from_json()` method of the form
-      `void from_json(const basic_json&, ValueType&)`, and
-
-    @tparam ValueType the input parameter type.
-
-    @return the input parameter, allowing chaining calls.
-
-    @throw what @ref json_serializer<ValueType> `from_json()` method throws
-
-    @liveexample{The example below shows several conversions from JSON values
-    to other types. There a few things to note: (1) Floating-point numbers can
-    be converted to integers\, (2) A JSON array can be converted to a standard
-    `std::vector<short>`\, (3) A JSON object can be converted to C++
-    associative containers such as `std::unordered_map<std::string\,
-    json>`.,get_to}
-
-    @since version 3.3.0
-    */
-    template < typename ValueType,
-               detail::enable_if_t <
-                   !detail::is_basic_json<ValueType>::value&&
-                   detail::has_from_json<basic_json_t, ValueType>::value,
-                   int > = 0 >
-    ValueType & get_to(ValueType& v) const noexcept(noexcept(
-                JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>(), v)))
-    {
-        JSONSerializer<ValueType>::from_json(*this, v);
-        return v;
-    }
-
-    // specialization to allow to call get_to with a basic_json value
-    // see https://github.com/nlohmann/json/issues/2175
-    template<typename ValueType,
-             detail::enable_if_t <
-                 detail::is_basic_json<ValueType>::value,
-                 int> = 0>
-    ValueType & get_to(ValueType& v) const
-    {
-        v = *this;
-        return v;
-    }
-
-    template <
-        typename T, std::size_t N,
-        typename Array = T (&)[N],
-        detail::enable_if_t <
-            detail::has_from_json<basic_json_t, Array>::value, int > = 0 >
-    Array get_to(T (&v)[N]) const
-    noexcept(noexcept(JSONSerializer<Array>::from_json(
-                          std::declval<const basic_json_t&>(), v)))
-    {
-        JSONSerializer<Array>::from_json(*this, v);
-        return v;
-    }
-
-
-    /*!
-    @brief get a pointer value (implicit)
-
-    Implicit pointer access to the internally stored JSON value. No copies are
-    made.
-
-    @warning Writing data to the pointee of the result yields an undefined
-    state.
-
-    @tparam PointerType pointer type; must be a pointer to @ref array_t, @ref
-    object_t, @ref string_t, @ref boolean_t, @ref number_integer_t,
-    @ref number_unsigned_t, or @ref number_float_t. Enforced by a static
-    assertion.
-
-    @return pointer to the internally stored JSON value if the requested
-    pointer type @a PointerType fits to the JSON value; `nullptr` otherwise
-
-    @complexity Constant.
-
-    @liveexample{The example below shows how pointers to internal values of a
-    JSON value can be requested. Note that no type conversions are made and a
-    `nullptr` is returned if the value and the requested pointer type does not
-    match.,get_ptr}
-
-    @since version 1.0.0
-    */
-    template<typename PointerType, typename std::enable_if<
-                 std::is_pointer<PointerType>::value, int>::type = 0>
-    auto get_ptr() noexcept -> decltype(std::declval<basic_json_t&>().get_impl_ptr(std::declval<PointerType>()))
-    {
-        // delegate the call to get_impl_ptr<>()
-        return get_impl_ptr(static_cast<PointerType>(nullptr));
-    }
-
-    /*!
-    @brief get a pointer value (implicit)
-    @copydoc get_ptr()
-    */
-    template < typename PointerType, typename std::enable_if <
-                   std::is_pointer<PointerType>::value&&
-                   std::is_const<typename std::remove_pointer<PointerType>::type>::value, int >::type = 0 >
-    constexpr auto get_ptr() const noexcept -> decltype(std::declval<const basic_json_t&>().get_impl_ptr(std::declval<PointerType>()))
-    {
-        // delegate the call to get_impl_ptr<>() const
-        return get_impl_ptr(static_cast<PointerType>(nullptr));
-    }
-
-    /*!
-    @brief get a pointer value (explicit)
-
-    Explicit pointer access to the internally stored JSON value. No copies are
-    made.
-
-    @warning The pointer becomes invalid if the underlying JSON object
-    changes.
-
-    @tparam PointerType pointer type; must be a pointer to @ref array_t, @ref
-    object_t, @ref string_t, @ref boolean_t, @ref number_integer_t,
-    @ref number_unsigned_t, or @ref number_float_t.
-
-    @return pointer to the internally stored JSON value if the requested
-    pointer type @a PointerType fits to the JSON value; `nullptr` otherwise
-
-    @complexity Constant.
-
-    @liveexample{The example below shows how pointers to internal values of a
-    JSON value can be requested. Note that no type conversions are made and a
-    `nullptr` is returned if the value and the requested pointer type does not
-    match.,get__PointerType}
-
-    @sa @ref get_ptr() for explicit pointer-member access
-
-    @since version 1.0.0
-    */
-    template<typename PointerType, typename std::enable_if<
-                 std::is_pointer<PointerType>::value, int>::type = 0>
-    auto get() noexcept -> decltype(std::declval<basic_json_t&>().template get_ptr<PointerType>())
-    {
-        // delegate the call to get_ptr
-        return get_ptr<PointerType>();
-    }
-
-    /*!
-    @brief get a pointer value (explicit)
-    @copydoc get()
-    */
-    template<typename PointerType, typename std::enable_if<
-                 std::is_pointer<PointerType>::value, int>::type = 0>
-    constexpr auto get() const noexcept -> decltype(std::declval<const basic_json_t&>().template get_ptr<PointerType>())
-    {
-        // delegate the call to get_ptr
-        return get_ptr<PointerType>();
-    }
-
-    /*!
-    @brief get a reference value (implicit)
-
-    Implicit reference access to the internally stored JSON value. No copies
-    are made.
-
-    @warning Writing data to the referee of the result yields an undefined
-    state.
-
-    @tparam ReferenceType reference type; must be a reference to @ref array_t,
-    @ref object_t, @ref string_t, @ref boolean_t, @ref number_integer_t, or
-    @ref number_float_t. Enforced by static assertion.
-
-    @return reference to the internally stored JSON value if the requested
-    reference type @a ReferenceType fits to the JSON value; throws
-    type_error.303 otherwise
-
-    @throw type_error.303 in case passed type @a ReferenceType is incompatible
-    with the stored JSON value; see example below
-
-    @complexity Constant.
-
-    @liveexample{The example shows several calls to `get_ref()`.,get_ref}
-
-    @since version 1.1.0
-    */
-    template<typename ReferenceType, typename std::enable_if<
-                 std::is_reference<ReferenceType>::value, int>::type = 0>
-    ReferenceType get_ref()
-    {
-        // delegate call to get_ref_impl
-        return get_ref_impl<ReferenceType>(*this);
-    }
-
-    /*!
-    @brief get a reference value (implicit)
-    @copydoc get_ref()
-    */
-    template < typename ReferenceType, typename std::enable_if <
-                   std::is_reference<ReferenceType>::value&&
-                   std::is_const<typename std::remove_reference<ReferenceType>::type>::value, int >::type = 0 >
-    ReferenceType get_ref() const
-    {
-        // delegate call to get_ref_impl
-        return get_ref_impl<ReferenceType>(*this);
-    }
-
-    /*!
-    @brief get a value (implicit)
-
-    Implicit type conversion between the JSON value and a compatible value.
-    The call is realized by calling @ref get() const.
-
-    @tparam ValueType non-pointer type compatible to the JSON value, for
-    instance `int` for JSON integer numbers, `bool` for JSON booleans, or
-    `std::vector` types for JSON arrays. The character type of @ref string_t
-    as well as an initializer list of this type is excluded to avoid
-    ambiguities as these types implicitly convert to `std::string`.
-
-    @return copy of the JSON value, converted to type @a ValueType
-
-    @throw type_error.302 in case passed type @a ValueType is incompatible
-    to the JSON value type (e.g., the JSON value is of type boolean, but a
-    string is requested); see example below
-
-    @complexity Linear in the size of the JSON value.
-
-    @liveexample{The example below shows several conversions from JSON values
-    to other types. There a few things to note: (1) Floating-point numbers can
-    be converted to integers\, (2) A JSON array can be converted to a standard
-    `std::vector<short>`\, (3) A JSON object can be converted to C++
-    associative containers such as `std::unordered_map<std::string\,
-    json>`.,operator__ValueType}
-
-    @since version 1.0.0
-    */
-    template < typename ValueType, typename std::enable_if <
-                   !std::is_pointer<ValueType>::value&&
-                   !std::is_same<ValueType, detail::json_ref<basic_json>>::value&&
-                   !std::is_same<ValueType, typename string_t::value_type>::value&&
-                   !detail::is_basic_json<ValueType>::value
-                   && !std::is_same<ValueType, std::initializer_list<typename string_t::value_type>>::value
-#if defined(JSON_HAS_CPP_17) && (defined(__GNUC__) || (defined(_MSC_VER) && _MSC_VER >= 1910 && _MSC_VER <= 1914))
-                   && !std::is_same<ValueType, typename std::string_view>::value
-#endif
-                   && detail::is_detected<detail::get_template_function, const basic_json_t&, ValueType>::value
-                   , int >::type = 0 >
-    JSON_EXPLICIT operator ValueType() const
-    {
-        // delegate the call to get<>() const
-        return get<ValueType>();
-    }
-
-    /*!
-    @return reference to the binary value
-
-    @throw type_error.302 if the value is not binary
-
-    @sa @ref is_binary() to check if the value is binary
-
-    @since version 3.8.0
-    */
-    binary_t& get_binary()
-    {
-        if (!is_binary())
-        {
-            JSON_THROW(type_error::create(302, "type must be binary, but is " + std::string(type_name())));
-        }
-
-        return *get_ptr<binary_t*>();
-    }
-
-    /// @copydoc get_binary()
-    const binary_t& get_binary() const
-    {
-        if (!is_binary())
-        {
-            JSON_THROW(type_error::create(302, "type must be binary, but is " + std::string(type_name())));
-        }
-
-        return *get_ptr<const binary_t*>();
-    }
-
-    /// @}
-
-
-    ////////////////////
-    // element access //
-    ////////////////////
-
-    /// @name element access
-    /// Access to the JSON value.
-    /// @{
-
-    /*!
-    @brief access specified array element with bounds checking
-
-    Returns a reference to the element at specified location @a idx, with
-    bounds checking.
-
-    @param[in] idx  index of the element to access
-
-    @return reference to the element at index @a idx
-
-    @throw type_error.304 if the JSON value is not an array; in this case,
-    calling `at` with an index makes no sense. See example below.
-    @throw out_of_range.401 if the index @a idx is out of range of the array;
-    that is, `idx >= size()`. See example below.
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes in the JSON value.
-
-    @complexity Constant.
-
-    @since version 1.0.0
-
-    @liveexample{The example below shows how array elements can be read and
-    written using `at()`. It also demonstrates the different exceptions that
-    can be thrown.,at__size_type}
-    */
-    reference at(size_type idx)
-    {
-        // at only works for arrays
-        if (JSON_HEDLEY_LIKELY(is_array()))
-        {
-            JSON_TRY
-            {
-                return m_value.array->at(idx);
-            }
-            JSON_CATCH (std::out_of_range&)
-            {
-                // create better exception explanation
-                JSON_THROW(out_of_range::create(401, "array index " + std::to_string(idx) + " is out of range"));
-            }
-        }
-        else
-        {
-            JSON_THROW(type_error::create(304, "cannot use at() with " + std::string(type_name())));
-        }
-    }
-
-    /*!
-    @brief access specified array element with bounds checking
-
-    Returns a const reference to the element at specified location @a idx,
-    with bounds checking.
-
-    @param[in] idx  index of the element to access
-
-    @return const reference to the element at index @a idx
-
-    @throw type_error.304 if the JSON value is not an array; in this case,
-    calling `at` with an index makes no sense. See example below.
-    @throw out_of_range.401 if the index @a idx is out of range of the array;
-    that is, `idx >= size()`. See example below.
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes in the JSON value.
-
-    @complexity Constant.
-
-    @since version 1.0.0
-
-    @liveexample{The example below shows how array elements can be read using
-    `at()`. It also demonstrates the different exceptions that can be thrown.,
-    at__size_type_const}
-    */
-    const_reference at(size_type idx) const
-    {
-        // at only works for arrays
-        if (JSON_HEDLEY_LIKELY(is_array()))
-        {
-            JSON_TRY
-            {
-                return m_value.array->at(idx);
-            }
-            JSON_CATCH (std::out_of_range&)
-            {
-                // create better exception explanation
-                JSON_THROW(out_of_range::create(401, "array index " + std::to_string(idx) + " is out of range"));
-            }
-        }
-        else
-        {
-            JSON_THROW(type_error::create(304, "cannot use at() with " + std::string(type_name())));
-        }
-    }
-
-    /*!
-    @brief access specified object element with bounds checking
-
-    Returns a reference to the element at with specified key @a key, with
-    bounds checking.
-
-    @param[in] key  key of the element to access
-
-    @return reference to the element at key @a key
-
-    @throw type_error.304 if the JSON value is not an object; in this case,
-    calling `at` with a key makes no sense. See example below.
-    @throw out_of_range.403 if the key @a key is is not stored in the object;
-    that is, `find(key) == end()`. See example below.
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes in the JSON value.
-
-    @complexity Logarithmic in the size of the container.
-
-    @sa @ref operator[](const typename object_t::key_type&) for unchecked
-    access by reference
-    @sa @ref value() for access by value with a default value
-
-    @since version 1.0.0
-
-    @liveexample{The example below shows how object elements can be read and
-    written using `at()`. It also demonstrates the different exceptions that
-    can be thrown.,at__object_t_key_type}
-    */
-    reference at(const typename object_t::key_type& key)
-    {
-        // at only works for objects
-        if (JSON_HEDLEY_LIKELY(is_object()))
-        {
-            JSON_TRY
-            {
-                return m_value.object->at(key);
-            }
-            JSON_CATCH (std::out_of_range&)
-            {
-                // create better exception explanation
-                JSON_THROW(out_of_range::create(403, "key '" + key + "' not found"));
-            }
-        }
-        else
-        {
-            JSON_THROW(type_error::create(304, "cannot use at() with " + std::string(type_name())));
-        }
-    }
-
-    /*!
-    @brief access specified object element with bounds checking
-
-    Returns a const reference to the element at with specified key @a key,
-    with bounds checking.
-
-    @param[in] key  key of the element to access
-
-    @return const reference to the element at key @a key
-
-    @throw type_error.304 if the JSON value is not an object; in this case,
-    calling `at` with a key makes no sense. See example below.
-    @throw out_of_range.403 if the key @a key is is not stored in the object;
-    that is, `find(key) == end()`. See example below.
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes in the JSON value.
-
-    @complexity Logarithmic in the size of the container.
-
-    @sa @ref operator[](const typename object_t::key_type&) for unchecked
-    access by reference
-    @sa @ref value() for access by value with a default value
-
-    @since version 1.0.0
-
-    @liveexample{The example below shows how object elements can be read using
-    `at()`. It also demonstrates the different exceptions that can be thrown.,
-    at__object_t_key_type_const}
-    */
-    const_reference at(const typename object_t::key_type& key) const
-    {
-        // at only works for objects
-        if (JSON_HEDLEY_LIKELY(is_object()))
-        {
-            JSON_TRY
-            {
-                return m_value.object->at(key);
-            }
-            JSON_CATCH (std::out_of_range&)
-            {
-                // create better exception explanation
-                JSON_THROW(out_of_range::create(403, "key '" + key + "' not found"));
-            }
-        }
-        else
-        {
-            JSON_THROW(type_error::create(304, "cannot use at() with " + std::string(type_name())));
-        }
-    }
-
-    /*!
-    @brief access specified array element
-
-    Returns a reference to the element at specified location @a idx.
-
-    @note If @a idx is beyond the range of the array (i.e., `idx >= size()`),
-    then the array is silently filled up with `null` values to make `idx` a
-    valid reference to the last stored element.
-
-    @param[in] idx  index of the element to access
-
-    @return reference to the element at index @a idx
-
-    @throw type_error.305 if the JSON value is not an array or null; in that
-    cases, using the [] operator with an index makes no sense.
-
-    @complexity Constant if @a idx is in the range of the array. Otherwise
-    linear in `idx - size()`.
-
-    @liveexample{The example below shows how array elements can be read and
-    written using `[]` operator. Note the addition of `null`
-    values.,operatorarray__size_type}
-
-    @since version 1.0.0
-    */
-    reference operator[](size_type idx)
-    {
-        // implicitly convert null value to an empty array
-        if (is_null())
-        {
-            m_type = value_t::array;
-            m_value.array = create<array_t>();
-            assert_invariant();
-        }
-
-        // operator[] only works for arrays
-        if (JSON_HEDLEY_LIKELY(is_array()))
-        {
-            // fill up array with null values if given idx is outside range
-            if (idx >= m_value.array->size())
-            {
-                m_value.array->insert(m_value.array->end(),
-                                      idx - m_value.array->size() + 1,
-                                      basic_json());
-            }
-
-            return m_value.array->operator[](idx);
-        }
-
-        JSON_THROW(type_error::create(305, "cannot use operator[] with a numeric argument with " + std::string(type_name())));
-    }
-
-    /*!
-    @brief access specified array element
-
-    Returns a const reference to the element at specified location @a idx.
-
-    @param[in] idx  index of the element to access
-
-    @return const reference to the element at index @a idx
-
-    @throw type_error.305 if the JSON value is not an array; in that case,
-    using the [] operator with an index makes no sense.
-
-    @complexity Constant.
-
-    @liveexample{The example below shows how array elements can be read using
-    the `[]` operator.,operatorarray__size_type_const}
-
-    @since version 1.0.0
-    */
-    const_reference operator[](size_type idx) const
-    {
-        // const operator[] only works for arrays
-        if (JSON_HEDLEY_LIKELY(is_array()))
-        {
-            return m_value.array->operator[](idx);
-        }
-
-        JSON_THROW(type_error::create(305, "cannot use operator[] with a numeric argument with " + std::string(type_name())));
-    }
-
-    /*!
-    @brief access specified object element
-
-    Returns a reference to the element at with specified key @a key.
-
-    @note If @a key is not found in the object, then it is silently added to
-    the object and filled with a `null` value to make `key` a valid reference.
-    In case the value was `null` before, it is converted to an object.
-
-    @param[in] key  key of the element to access
-
-    @return reference to the element at key @a key
-
-    @throw type_error.305 if the JSON value is not an object or null; in that
-    cases, using the [] operator with a key makes no sense.
-
-    @complexity Logarithmic in the size of the container.
-
-    @liveexample{The example below shows how object elements can be read and
-    written using the `[]` operator.,operatorarray__key_type}
-
-    @sa @ref at(const typename object_t::key_type&) for access by reference
-    with range checking
-    @sa @ref value() for access by value with a default value
-
-    @since version 1.0.0
-    */
-    reference operator[](const typename object_t::key_type& key)
-    {
-        // implicitly convert null value to an empty object
-        if (is_null())
-        {
-            m_type = value_t::object;
-            m_value.object = create<object_t>();
-            assert_invariant();
-        }
-
-        // operator[] only works for objects
-        if (JSON_HEDLEY_LIKELY(is_object()))
-        {
-            return m_value.object->operator[](key);
-        }
-
-        JSON_THROW(type_error::create(305, "cannot use operator[] with a string argument with " + std::string(type_name())));
-    }
-
-    /*!
-    @brief read-only access specified object element
-
-    Returns a const reference to the element at with specified key @a key. No
-    bounds checking is performed.
-
-    @warning If the element with key @a key does not exist, the behavior is
-    undefined.
-
-    @param[in] key  key of the element to access
-
-    @return const reference to the element at key @a key
-
-    @pre The element with key @a key must exist. **This precondition is
-         enforced with an assertion.**
-
-    @throw type_error.305 if the JSON value is not an object; in that case,
-    using the [] operator with a key makes no sense.
-
-    @complexity Logarithmic in the size of the container.
-
-    @liveexample{The example below shows how object elements can be read using
-    the `[]` operator.,operatorarray__key_type_const}
-
-    @sa @ref at(const typename object_t::key_type&) for access by reference
-    with range checking
-    @sa @ref value() for access by value with a default value
-
-    @since version 1.0.0
-    */
-    const_reference operator[](const typename object_t::key_type& key) const
-    {
-        // const operator[] only works for objects
-        if (JSON_HEDLEY_LIKELY(is_object()))
-        {
-            JSON_ASSERT(m_value.object->find(key) != m_value.object->end());
-            return m_value.object->find(key)->second;
-        }
-
-        JSON_THROW(type_error::create(305, "cannot use operator[] with a string argument with " + std::string(type_name())));
-    }
-
-    /*!
-    @brief access specified object element
-
-    Returns a reference to the element at with specified key @a key.
-
-    @note If @a key is not found in the object, then it is silently added to
-    the object and filled with a `null` value to make `key` a valid reference.
-    In case the value was `null` before, it is converted to an object.
-
-    @param[in] key  key of the element to access
-
-    @return reference to the element at key @a key
-
-    @throw type_error.305 if the JSON value is not an object or null; in that
-    cases, using the [] operator with a key makes no sense.
-
-    @complexity Logarithmic in the size of the container.
-
-    @liveexample{The example below shows how object elements can be read and
-    written using the `[]` operator.,operatorarray__key_type}
-
-    @sa @ref at(const typename object_t::key_type&) for access by reference
-    with range checking
-    @sa @ref value() for access by value with a default value
-
-    @since version 1.1.0
-    */
-    template<typename T>
-    JSON_HEDLEY_NON_NULL(2)
-    reference operator[](T* key)
-    {
-        // implicitly convert null to object
-        if (is_null())
-        {
-            m_type = value_t::object;
-            m_value = value_t::object;
-            assert_invariant();
-        }
-
-        // at only works for objects
-        if (JSON_HEDLEY_LIKELY(is_object()))
-        {
-            return m_value.object->operator[](key);
-        }
-
-        JSON_THROW(type_error::create(305, "cannot use operator[] with a string argument with " + std::string(type_name())));
-    }
-
-    /*!
-    @brief read-only access specified object element
-
-    Returns a const reference to the element at with specified key @a key. No
-    bounds checking is performed.
-
-    @warning If the element with key @a key does not exist, the behavior is
-    undefined.
-
-    @param[in] key  key of the element to access
-
-    @return const reference to the element at key @a key
-
-    @pre The element with key @a key must exist. **This precondition is
-         enforced with an assertion.**
-
-    @throw type_error.305 if the JSON value is not an object; in that case,
-    using the [] operator with a key makes no sense.
-
-    @complexity Logarithmic in the size of the container.
-
-    @liveexample{The example below shows how object elements can be read using
-    the `[]` operator.,operatorarray__key_type_const}
-
-    @sa @ref at(const typename object_t::key_type&) for access by reference
-    with range checking
-    @sa @ref value() for access by value with a default value
-
-    @since version 1.1.0
-    */
-    template<typename T>
-    JSON_HEDLEY_NON_NULL(2)
-    const_reference operator[](T* key) const
-    {
-        // at only works for objects
-        if (JSON_HEDLEY_LIKELY(is_object()))
-        {
-            JSON_ASSERT(m_value.object->find(key) != m_value.object->end());
-            return m_value.object->find(key)->second;
-        }
-
-        JSON_THROW(type_error::create(305, "cannot use operator[] with a string argument with " + std::string(type_name())));
-    }
-
-    /*!
-    @brief access specified object element with default value
-
-    Returns either a copy of an object's element at the specified key @a key
-    or a given default value if no element with key @a key exists.
-
-    The function is basically equivalent to executing
-    @code {.cpp}
-    try {
-        return at(key);
-    } catch(out_of_range) {
-        return default_value;
-    }
-    @endcode
-
-    @note Unlike @ref at(const typename object_t::key_type&), this function
-    does not throw if the given key @a key was not found.
-
-    @note Unlike @ref operator[](const typename object_t::key_type& key), this
-    function does not implicitly add an element to the position defined by @a
-    key. This function is furthermore also applicable to const objects.
-
-    @param[in] key  key of the element to access
-    @param[in] default_value  the value to return if @a key is not found
-
-    @tparam ValueType type compatible to JSON values, for instance `int` for
-    JSON integer numbers, `bool` for JSON booleans, or `std::vector` types for
-    JSON arrays. Note the type of the expected value at @a key and the default
-    value @a default_value must be compatible.
-
-    @return copy of the element at key @a key or @a default_value if @a key
-    is not found
-
-    @throw type_error.302 if @a default_value does not match the type of the
-    value at @a key
-    @throw type_error.306 if the JSON value is not an object; in that case,
-    using `value()` with a key makes no sense.
-
-    @complexity Logarithmic in the size of the container.
-
-    @liveexample{The example below shows how object elements can be queried
-    with a default value.,basic_json__value}
-
-    @sa @ref at(const typename object_t::key_type&) for access by reference
-    with range checking
-    @sa @ref operator[](const typename object_t::key_type&) for unchecked
-    access by reference
-
-    @since version 1.0.0
-    */
-    // using std::is_convertible in a std::enable_if will fail when using explicit conversions
-    template < class ValueType, typename std::enable_if <
-                   detail::is_getable<basic_json_t, ValueType>::value
-                   && !std::is_same<value_t, ValueType>::value, int >::type = 0 >
-    ValueType value(const typename object_t::key_type& key, const ValueType& default_value) const
-    {
-        // at only works for objects
-        if (JSON_HEDLEY_LIKELY(is_object()))
-        {
-            // if key is found, return value and given default value otherwise
-            const auto it = find(key);
-            if (it != end())
-            {
-                return it->template get<ValueType>();
-            }
-
-            return default_value;
-        }
-
-        JSON_THROW(type_error::create(306, "cannot use value() with " + std::string(type_name())));
-    }
-
-    /*!
-    @brief overload for a default value of type const char*
-    @copydoc basic_json::value(const typename object_t::key_type&, const ValueType&) const
-    */
-    string_t value(const typename object_t::key_type& key, const char* default_value) const
-    {
-        return value(key, string_t(default_value));
-    }
-
-    /*!
-    @brief access specified object element via JSON Pointer with default value
-
-    Returns either a copy of an object's element at the specified key @a key
-    or a given default value if no element with key @a key exists.
-
-    The function is basically equivalent to executing
-    @code {.cpp}
-    try {
-        return at(ptr);
-    } catch(out_of_range) {
-        return default_value;
-    }
-    @endcode
-
-    @note Unlike @ref at(const json_pointer&), this function does not throw
-    if the given key @a key was not found.
-
-    @param[in] ptr  a JSON pointer to the element to access
-    @param[in] default_value  the value to return if @a ptr found no value
-
-    @tparam ValueType type compatible to JSON values, for instance `int` for
-    JSON integer numbers, `bool` for JSON booleans, or `std::vector` types for
-    JSON arrays. Note the type of the expected value at @a key and the default
-    value @a default_value must be compatible.
-
-    @return copy of the element at key @a key or @a default_value if @a key
-    is not found
-
-    @throw type_error.302 if @a default_value does not match the type of the
-    value at @a ptr
-    @throw type_error.306 if the JSON value is not an object; in that case,
-    using `value()` with a key makes no sense.
-
-    @complexity Logarithmic in the size of the container.
-
-    @liveexample{The example below shows how object elements can be queried
-    with a default value.,basic_json__value_ptr}
-
-    @sa @ref operator[](const json_pointer&) for unchecked access by reference
-
-    @since version 2.0.2
-    */
-    template<class ValueType, typename std::enable_if<
-                 detail::is_getable<basic_json_t, ValueType>::value, int>::type = 0>
-    ValueType value(const json_pointer& ptr, const ValueType& default_value) const
-    {
-        // at only works for objects
-        if (JSON_HEDLEY_LIKELY(is_object()))
-        {
-            // if pointer resolves a value, return it or use default value
-            JSON_TRY
-            {
-                return ptr.get_checked(this).template get<ValueType>();
-            }
-            JSON_INTERNAL_CATCH (out_of_range&)
-            {
-                return default_value;
-            }
-        }
-
-        JSON_THROW(type_error::create(306, "cannot use value() with " + std::string(type_name())));
-    }
-
-    /*!
-    @brief overload for a default value of type const char*
-    @copydoc basic_json::value(const json_pointer&, ValueType) const
-    */
-    JSON_HEDLEY_NON_NULL(3)
-    string_t value(const json_pointer& ptr, const char* default_value) const
-    {
-        return value(ptr, string_t(default_value));
-    }
-
-    /*!
-    @brief access the first element
-
-    Returns a reference to the first element in the container. For a JSON
-    container `c`, the expression `c.front()` is equivalent to `*c.begin()`.
-
-    @return In case of a structured type (array or object), a reference to the
-    first element is returned. In case of number, string, boolean, or binary
-    values, a reference to the value is returned.
-
-    @complexity Constant.
-
-    @pre The JSON value must not be `null` (would throw `std::out_of_range`)
-    or an empty array or object (undefined behavior, **guarded by
-    assertions**).
-    @post The JSON value remains unchanged.
-
-    @throw invalid_iterator.214 when called on `null` value
-
-    @liveexample{The following code shows an example for `front()`.,front}
-
-    @sa @ref back() -- access the last element
-
-    @since version 1.0.0
-    */
-    reference front()
-    {
-        return *begin();
-    }
-
-    /*!
-    @copydoc basic_json::front()
-    */
-    const_reference front() const
-    {
-        return *cbegin();
-    }
-
-    /*!
-    @brief access the last element
-
-    Returns a reference to the last element in the container. For a JSON
-    container `c`, the expression `c.back()` is equivalent to
-    @code {.cpp}
-    auto tmp = c.end();
-    --tmp;
-    return *tmp;
-    @endcode
-
-    @return In case of a structured type (array or object), a reference to the
-    last element is returned. In case of number, string, boolean, or binary
-    values, a reference to the value is returned.
-
-    @complexity Constant.
-
-    @pre The JSON value must not be `null` (would throw `std::out_of_range`)
-    or an empty array or object (undefined behavior, **guarded by
-    assertions**).
-    @post The JSON value remains unchanged.
-
-    @throw invalid_iterator.214 when called on a `null` value. See example
-    below.
-
-    @liveexample{The following code shows an example for `back()`.,back}
-
-    @sa @ref front() -- access the first element
-
-    @since version 1.0.0
-    */
-    reference back()
-    {
-        auto tmp = end();
-        --tmp;
-        return *tmp;
-    }
-
-    /*!
-    @copydoc basic_json::back()
-    */
-    const_reference back() const
-    {
-        auto tmp = cend();
-        --tmp;
-        return *tmp;
-    }
-
-    /*!
-    @brief remove element given an iterator
-
-    Removes the element specified by iterator @a pos. The iterator @a pos must
-    be valid and dereferenceable. Thus the `end()` iterator (which is valid,
-    but is not dereferenceable) cannot be used as a value for @a pos.
-
-    If called on a primitive type other than `null`, the resulting JSON value
-    will be `null`.
-
-    @param[in] pos iterator to the element to remove
-    @return Iterator following the last removed element. If the iterator @a
-    pos refers to the last element, the `end()` iterator is returned.
-
-    @tparam IteratorType an @ref iterator or @ref const_iterator
-
-    @post Invalidates iterators and references at or after the point of the
-    erase, including the `end()` iterator.
-
-    @throw type_error.307 if called on a `null` value; example: `"cannot use
-    erase() with null"`
-    @throw invalid_iterator.202 if called on an iterator which does not belong
-    to the current JSON value; example: `"iterator does not fit current
-    value"`
-    @throw invalid_iterator.205 if called on a primitive type with invalid
-    iterator (i.e., any iterator which is not `begin()`); example: `"iterator
-    out of range"`
-
-    @complexity The complexity depends on the type:
-    - objects: amortized constant
-    - arrays: linear in distance between @a pos and the end of the container
-    - strings and binary: linear in the length of the member
-    - other types: constant
-
-    @liveexample{The example shows the result of `erase()` for different JSON
-    types.,erase__IteratorType}
-
-    @sa @ref erase(IteratorType, IteratorType) -- removes the elements in
-    the given range
-    @sa @ref erase(const typename object_t::key_type&) -- removes the element
-    from an object at the given key
-    @sa @ref erase(const size_type) -- removes the element from an array at
-    the given index
-
-    @since version 1.0.0
-    */
-    template < class IteratorType, typename std::enable_if <
-                   std::is_same<IteratorType, typename basic_json_t::iterator>::value ||
-                   std::is_same<IteratorType, typename basic_json_t::const_iterator>::value, int >::type
-               = 0 >
-    IteratorType erase(IteratorType pos)
-    {
-        // make sure iterator fits the current value
-        if (JSON_HEDLEY_UNLIKELY(this != pos.m_object))
-        {
-            JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value"));
-        }
-
-        IteratorType result = end();
-
-        switch (m_type)
-        {
-            case value_t::boolean:
-            case value_t::number_float:
-            case value_t::number_integer:
-            case value_t::number_unsigned:
-            case value_t::string:
-            case value_t::binary:
-            {
-                if (JSON_HEDLEY_UNLIKELY(!pos.m_it.primitive_iterator.is_begin()))
-                {
-                    JSON_THROW(invalid_iterator::create(205, "iterator out of range"));
-                }
-
-                if (is_string())
-                {
-                    AllocatorType<string_t> alloc;
-                    std::allocator_traits<decltype(alloc)>::destroy(alloc, m_value.string);
-                    std::allocator_traits<decltype(alloc)>::deallocate(alloc, m_value.string, 1);
-                    m_value.string = nullptr;
-                }
-                else if (is_binary())
-                {
-                    AllocatorType<binary_t> alloc;
-                    std::allocator_traits<decltype(alloc)>::destroy(alloc, m_value.binary);
-                    std::allocator_traits<decltype(alloc)>::deallocate(alloc, m_value.binary, 1);
-                    m_value.binary = nullptr;
-                }
-
-                m_type = value_t::null;
-                assert_invariant();
-                break;
-            }
-
-            case value_t::object:
-            {
-                result.m_it.object_iterator = m_value.object->erase(pos.m_it.object_iterator);
-                break;
-            }
-
-            case value_t::array:
-            {
-                result.m_it.array_iterator = m_value.array->erase(pos.m_it.array_iterator);
-                break;
-            }
-
-            default:
-                JSON_THROW(type_error::create(307, "cannot use erase() with " + std::string(type_name())));
-        }
-
-        return result;
-    }
-
-    /*!
-    @brief remove elements given an iterator range
-
-    Removes the element specified by the range `[first; last)`. The iterator
-    @a first does not need to be dereferenceable if `first == last`: erasing
-    an empty range is a no-op.
-
-    If called on a primitive type other than `null`, the resulting JSON value
-    will be `null`.
-
-    @param[in] first iterator to the beginning of the range to remove
-    @param[in] last iterator past the end of the range to remove
-    @return Iterator following the last removed element. If the iterator @a
-    second refers to the last element, the `end()` iterator is returned.
-
-    @tparam IteratorType an @ref iterator or @ref const_iterator
-
-    @post Invalidates iterators and references at or after the point of the
-    erase, including the `end()` iterator.
-
-    @throw type_error.307 if called on a `null` value; example: `"cannot use
-    erase() with null"`
-    @throw invalid_iterator.203 if called on iterators which does not belong
-    to the current JSON value; example: `"iterators do not fit current value"`
-    @throw invalid_iterator.204 if called on a primitive type with invalid
-    iterators (i.e., if `first != begin()` and `last != end()`); example:
-    `"iterators out of range"`
-
-    @complexity The complexity depends on the type:
-    - objects: `log(size()) + std::distance(first, last)`
-    - arrays: linear in the distance between @a first and @a last, plus linear
-      in the distance between @a last and end of the container
-    - strings and binary: linear in the length of the member
-    - other types: constant
-
-    @liveexample{The example shows the result of `erase()` for different JSON
-    types.,erase__IteratorType_IteratorType}
-
-    @sa @ref erase(IteratorType) -- removes the element at a given position
-    @sa @ref erase(const typename object_t::key_type&) -- removes the element
-    from an object at the given key
-    @sa @ref erase(const size_type) -- removes the element from an array at
-    the given index
-
-    @since version 1.0.0
-    */
-    template < class IteratorType, typename std::enable_if <
-                   std::is_same<IteratorType, typename basic_json_t::iterator>::value ||
-                   std::is_same<IteratorType, typename basic_json_t::const_iterator>::value, int >::type
-               = 0 >
-    IteratorType erase(IteratorType first, IteratorType last)
-    {
-        // make sure iterator fits the current value
-        if (JSON_HEDLEY_UNLIKELY(this != first.m_object || this != last.m_object))
-        {
-            JSON_THROW(invalid_iterator::create(203, "iterators do not fit current value"));
-        }
-
-        IteratorType result = end();
-
-        switch (m_type)
-        {
-            case value_t::boolean:
-            case value_t::number_float:
-            case value_t::number_integer:
-            case value_t::number_unsigned:
-            case value_t::string:
-            case value_t::binary:
-            {
-                if (JSON_HEDLEY_LIKELY(!first.m_it.primitive_iterator.is_begin()
-                                       || !last.m_it.primitive_iterator.is_end()))
-                {
-                    JSON_THROW(invalid_iterator::create(204, "iterators out of range"));
-                }
-
-                if (is_string())
-                {
-                    AllocatorType<string_t> alloc;
-                    std::allocator_traits<decltype(alloc)>::destroy(alloc, m_value.string);
-                    std::allocator_traits<decltype(alloc)>::deallocate(alloc, m_value.string, 1);
-                    m_value.string = nullptr;
-                }
-                else if (is_binary())
-                {
-                    AllocatorType<binary_t> alloc;
-                    std::allocator_traits<decltype(alloc)>::destroy(alloc, m_value.binary);
-                    std::allocator_traits<decltype(alloc)>::deallocate(alloc, m_value.binary, 1);
-                    m_value.binary = nullptr;
-                }
-
-                m_type = value_t::null;
-                assert_invariant();
-                break;
-            }
-
-            case value_t::object:
-            {
-                result.m_it.object_iterator = m_value.object->erase(first.m_it.object_iterator,
-                                              last.m_it.object_iterator);
-                break;
-            }
-
-            case value_t::array:
-            {
-                result.m_it.array_iterator = m_value.array->erase(first.m_it.array_iterator,
-                                             last.m_it.array_iterator);
-                break;
-            }
-
-            default:
-                JSON_THROW(type_error::create(307, "cannot use erase() with " + std::string(type_name())));
-        }
-
-        return result;
-    }
-
-    /*!
-    @brief remove element from a JSON object given a key
-
-    Removes elements from a JSON object with the key value @a key.
-
-    @param[in] key value of the elements to remove
-
-    @return Number of elements removed. If @a ObjectType is the default
-    `std::map` type, the return value will always be `0` (@a key was not
-    found) or `1` (@a key was found).
-
-    @post References and iterators to the erased elements are invalidated.
-    Other references and iterators are not affected.
-
-    @throw type_error.307 when called on a type other than JSON object;
-    example: `"cannot use erase() with null"`
-
-    @complexity `log(size()) + count(key)`
-
-    @liveexample{The example shows the effect of `erase()`.,erase__key_type}
-
-    @sa @ref erase(IteratorType) -- removes the element at a given position
-    @sa @ref erase(IteratorType, IteratorType) -- removes the elements in
-    the given range
-    @sa @ref erase(const size_type) -- removes the element from an array at
-    the given index
-
-    @since version 1.0.0
-    */
-    size_type erase(const typename object_t::key_type& key)
-    {
-        // this erase only works for objects
-        if (JSON_HEDLEY_LIKELY(is_object()))
-        {
-            return m_value.object->erase(key);
-        }
-
-        JSON_THROW(type_error::create(307, "cannot use erase() with " + std::string(type_name())));
-    }
-
-    /*!
-    @brief remove element from a JSON array given an index
-
-    Removes element from a JSON array at the index @a idx.
-
-    @param[in] idx index of the element to remove
-
-    @throw type_error.307 when called on a type other than JSON object;
-    example: `"cannot use erase() with null"`
-    @throw out_of_range.401 when `idx >= size()`; example: `"array index 17
-    is out of range"`
-
-    @complexity Linear in distance between @a idx and the end of the container.
-
-    @liveexample{The example shows the effect of `erase()`.,erase__size_type}
-
-    @sa @ref erase(IteratorType) -- removes the element at a given position
-    @sa @ref erase(IteratorType, IteratorType) -- removes the elements in
-    the given range
-    @sa @ref erase(const typename object_t::key_type&) -- removes the element
-    from an object at the given key
-
-    @since version 1.0.0
-    */
-    void erase(const size_type idx)
-    {
-        // this erase only works for arrays
-        if (JSON_HEDLEY_LIKELY(is_array()))
-        {
-            if (JSON_HEDLEY_UNLIKELY(idx >= size()))
-            {
-                JSON_THROW(out_of_range::create(401, "array index " + std::to_string(idx) + " is out of range"));
-            }
-
-            m_value.array->erase(m_value.array->begin() + static_cast<difference_type>(idx));
-        }
-        else
-        {
-            JSON_THROW(type_error::create(307, "cannot use erase() with " + std::string(type_name())));
-        }
-    }
-
-    /// @}
-
-
-    ////////////
-    // lookup //
-    ////////////
-
-    /// @name lookup
-    /// @{
-
-    /*!
-    @brief find an element in a JSON object
-
-    Finds an element in a JSON object with key equivalent to @a key. If the
-    element is not found or the JSON value is not an object, end() is
-    returned.
-
-    @note This method always returns @ref end() when executed on a JSON type
-          that is not an object.
-
-    @param[in] key key value of the element to search for.
-
-    @return Iterator to an element with key equivalent to @a key. If no such
-    element is found or the JSON value is not an object, past-the-end (see
-    @ref end()) iterator is returned.
-
-    @complexity Logarithmic in the size of the JSON object.
-
-    @liveexample{The example shows how `find()` is used.,find__key_type}
-
-    @sa @ref contains(KeyT&&) const -- checks whether a key exists
-
-    @since version 1.0.0
-    */
-    template<typename KeyT>
-    iterator find(KeyT&& key)
-    {
-        auto result = end();
-
-        if (is_object())
-        {
-            result.m_it.object_iterator = m_value.object->find(std::forward<KeyT>(key));
-        }
-
-        return result;
-    }
-
-    /*!
-    @brief find an element in a JSON object
-    @copydoc find(KeyT&&)
-    */
-    template<typename KeyT>
-    const_iterator find(KeyT&& key) const
-    {
-        auto result = cend();
-
-        if (is_object())
-        {
-            result.m_it.object_iterator = m_value.object->find(std::forward<KeyT>(key));
-        }
-
-        return result;
-    }
-
-    /*!
-    @brief returns the number of occurrences of a key in a JSON object
-
-    Returns the number of elements with key @a key. If ObjectType is the
-    default `std::map` type, the return value will always be `0` (@a key was
-    not found) or `1` (@a key was found).
-
-    @note This method always returns `0` when executed on a JSON type that is
-          not an object.
-
-    @param[in] key key value of the element to count
-
-    @return Number of elements with key @a key. If the JSON value is not an
-    object, the return value will be `0`.
-
-    @complexity Logarithmic in the size of the JSON object.
-
-    @liveexample{The example shows how `count()` is used.,count}
-
-    @since version 1.0.0
-    */
-    template<typename KeyT>
-    size_type count(KeyT&& key) const
-    {
-        // return 0 for all nonobject types
-        return is_object() ? m_value.object->count(std::forward<KeyT>(key)) : 0;
-    }
-
-    /*!
-    @brief check the existence of an element in a JSON object
-
-    Check whether an element exists in a JSON object with key equivalent to
-    @a key. If the element is not found or the JSON value is not an object,
-    false is returned.
-
-    @note This method always returns false when executed on a JSON type
-          that is not an object.
-
-    @param[in] key key value to check its existence.
-
-    @return true if an element with specified @a key exists. If no such
-    element with such key is found or the JSON value is not an object,
-    false is returned.
-
-    @complexity Logarithmic in the size of the JSON object.
-
-    @liveexample{The following code shows an example for `contains()`.,contains}
-
-    @sa @ref find(KeyT&&) -- returns an iterator to an object element
-    @sa @ref contains(const json_pointer&) const -- checks the existence for a JSON pointer
-
-    @since version 3.6.0
-    */
-    template < typename KeyT, typename std::enable_if <
-                   !std::is_same<typename std::decay<KeyT>::type, json_pointer>::value, int >::type = 0 >
-    bool contains(KeyT && key) const
-    {
-        return is_object() && m_value.object->find(std::forward<KeyT>(key)) != m_value.object->end();
-    }
-
-    /*!
-    @brief check the existence of an element in a JSON object given a JSON pointer
-
-    Check whether the given JSON pointer @a ptr can be resolved in the current
-    JSON value.
-
-    @note This method can be executed on any JSON value type.
-
-    @param[in] ptr JSON pointer to check its existence.
-
-    @return true if the JSON pointer can be resolved to a stored value, false
-    otherwise.
-
-    @post If `j.contains(ptr)` returns true, it is safe to call `j[ptr]`.
-
-    @throw parse_error.106   if an array index begins with '0'
-    @throw parse_error.109   if an array index was not a number
-
-    @complexity Logarithmic in the size of the JSON object.
-
-    @liveexample{The following code shows an example for `contains()`.,contains_json_pointer}
-
-    @sa @ref contains(KeyT &&) const -- checks the existence of a key
-
-    @since version 3.7.0
-    */
-    bool contains(const json_pointer& ptr) const
-    {
-        return ptr.contains(this);
-    }
-
-    /// @}
-
-
-    ///////////////
-    // iterators //
-    ///////////////
-
-    /// @name iterators
-    /// @{
-
-    /*!
-    @brief returns an iterator to the first element
-
-    Returns an iterator to the first element.
-
-    @image html range-begin-end.svg "Illustration from cppreference.com"
-
-    @return iterator to the first element
-
-    @complexity Constant.
-
-    @requirement This function helps `basic_json` satisfying the
-    [Container](https://en.cppreference.com/w/cpp/named_req/Container)
-    requirements:
-    - The complexity is constant.
-
-    @liveexample{The following code shows an example for `begin()`.,begin}
-
-    @sa @ref cbegin() -- returns a const iterator to the beginning
-    @sa @ref end() -- returns an iterator to the end
-    @sa @ref cend() -- returns a const iterator to the end
-
-    @since version 1.0.0
-    */
-    iterator begin() noexcept
-    {
-        iterator result(this);
-        result.set_begin();
-        return result;
-    }
-
-    /*!
-    @copydoc basic_json::cbegin()
-    */
-    const_iterator begin() const noexcept
-    {
-        return cbegin();
-    }
-
-    /*!
-    @brief returns a const iterator to the first element
-
-    Returns a const iterator to the first element.
-
-    @image html range-begin-end.svg "Illustration from cppreference.com"
-
-    @return const iterator to the first element
-
-    @complexity Constant.
-
-    @requirement This function helps `basic_json` satisfying the
-    [Container](https://en.cppreference.com/w/cpp/named_req/Container)
-    requirements:
-    - The complexity is constant.
-    - Has the semantics of `const_cast<const basic_json&>(*this).begin()`.
-
-    @liveexample{The following code shows an example for `cbegin()`.,cbegin}
-
-    @sa @ref begin() -- returns an iterator to the beginning
-    @sa @ref end() -- returns an iterator to the end
-    @sa @ref cend() -- returns a const iterator to the end
-
-    @since version 1.0.0
-    */
-    const_iterator cbegin() const noexcept
-    {
-        const_iterator result(this);
-        result.set_begin();
-        return result;
-    }
-
-    /*!
-    @brief returns an iterator to one past the last element
-
-    Returns an iterator to one past the last element.
-
-    @image html range-begin-end.svg "Illustration from cppreference.com"
-
-    @return iterator one past the last element
-
-    @complexity Constant.
-
-    @requirement This function helps `basic_json` satisfying the
-    [Container](https://en.cppreference.com/w/cpp/named_req/Container)
-    requirements:
-    - The complexity is constant.
-
-    @liveexample{The following code shows an example for `end()`.,end}
-
-    @sa @ref cend() -- returns a const iterator to the end
-    @sa @ref begin() -- returns an iterator to the beginning
-    @sa @ref cbegin() -- returns a const iterator to the beginning
-
-    @since version 1.0.0
-    */
-    iterator end() noexcept
-    {
-        iterator result(this);
-        result.set_end();
-        return result;
-    }
-
-    /*!
-    @copydoc basic_json::cend()
-    */
-    const_iterator end() const noexcept
-    {
-        return cend();
-    }
-
-    /*!
-    @brief returns a const iterator to one past the last element
-
-    Returns a const iterator to one past the last element.
-
-    @image html range-begin-end.svg "Illustration from cppreference.com"
-
-    @return const iterator one past the last element
-
-    @complexity Constant.
-
-    @requirement This function helps `basic_json` satisfying the
-    [Container](https://en.cppreference.com/w/cpp/named_req/Container)
-    requirements:
-    - The complexity is constant.
-    - Has the semantics of `const_cast<const basic_json&>(*this).end()`.
-
-    @liveexample{The following code shows an example for `cend()`.,cend}
-
-    @sa @ref end() -- returns an iterator to the end
-    @sa @ref begin() -- returns an iterator to the beginning
-    @sa @ref cbegin() -- returns a const iterator to the beginning
-
-    @since version 1.0.0
-    */
-    const_iterator cend() const noexcept
-    {
-        const_iterator result(this);
-        result.set_end();
-        return result;
-    }
-
-    /*!
-    @brief returns an iterator to the reverse-beginning
-
-    Returns an iterator to the reverse-beginning; that is, the last element.
-
-    @image html range-rbegin-rend.svg "Illustration from cppreference.com"
-
-    @complexity Constant.
-
-    @requirement This function helps `basic_json` satisfying the
-    [ReversibleContainer](https://en.cppreference.com/w/cpp/named_req/ReversibleContainer)
-    requirements:
-    - The complexity is constant.
-    - Has the semantics of `reverse_iterator(end())`.
-
-    @liveexample{The following code shows an example for `rbegin()`.,rbegin}
-
-    @sa @ref crbegin() -- returns a const reverse iterator to the beginning
-    @sa @ref rend() -- returns a reverse iterator to the end
-    @sa @ref crend() -- returns a const reverse iterator to the end
-
-    @since version 1.0.0
-    */
-    reverse_iterator rbegin() noexcept
-    {
-        return reverse_iterator(end());
-    }
-
-    /*!
-    @copydoc basic_json::crbegin()
-    */
-    const_reverse_iterator rbegin() const noexcept
-    {
-        return crbegin();
-    }
-
-    /*!
-    @brief returns an iterator to the reverse-end
-
-    Returns an iterator to the reverse-end; that is, one before the first
-    element.
-
-    @image html range-rbegin-rend.svg "Illustration from cppreference.com"
-
-    @complexity Constant.
-
-    @requirement This function helps `basic_json` satisfying the
-    [ReversibleContainer](https://en.cppreference.com/w/cpp/named_req/ReversibleContainer)
-    requirements:
-    - The complexity is constant.
-    - Has the semantics of `reverse_iterator(begin())`.
-
-    @liveexample{The following code shows an example for `rend()`.,rend}
-
-    @sa @ref crend() -- returns a const reverse iterator to the end
-    @sa @ref rbegin() -- returns a reverse iterator to the beginning
-    @sa @ref crbegin() -- returns a const reverse iterator to the beginning
-
-    @since version 1.0.0
-    */
-    reverse_iterator rend() noexcept
-    {
-        return reverse_iterator(begin());
-    }
-
-    /*!
-    @copydoc basic_json::crend()
-    */
-    const_reverse_iterator rend() const noexcept
-    {
-        return crend();
-    }
-
-    /*!
-    @brief returns a const reverse iterator to the last element
-
-    Returns a const iterator to the reverse-beginning; that is, the last
-    element.
-
-    @image html range-rbegin-rend.svg "Illustration from cppreference.com"
-
-    @complexity Constant.
-
-    @requirement This function helps `basic_json` satisfying the
-    [ReversibleContainer](https://en.cppreference.com/w/cpp/named_req/ReversibleContainer)
-    requirements:
-    - The complexity is constant.
-    - Has the semantics of `const_cast<const basic_json&>(*this).rbegin()`.
-
-    @liveexample{The following code shows an example for `crbegin()`.,crbegin}
-
-    @sa @ref rbegin() -- returns a reverse iterator to the beginning
-    @sa @ref rend() -- returns a reverse iterator to the end
-    @sa @ref crend() -- returns a const reverse iterator to the end
-
-    @since version 1.0.0
-    */
-    const_reverse_iterator crbegin() const noexcept
-    {
-        return const_reverse_iterator(cend());
-    }
-
-    /*!
-    @brief returns a const reverse iterator to one before the first
-
-    Returns a const reverse iterator to the reverse-end; that is, one before
-    the first element.
-
-    @image html range-rbegin-rend.svg "Illustration from cppreference.com"
-
-    @complexity Constant.
-
-    @requirement This function helps `basic_json` satisfying the
-    [ReversibleContainer](https://en.cppreference.com/w/cpp/named_req/ReversibleContainer)
-    requirements:
-    - The complexity is constant.
-    - Has the semantics of `const_cast<const basic_json&>(*this).rend()`.
-
-    @liveexample{The following code shows an example for `crend()`.,crend}
-
-    @sa @ref rend() -- returns a reverse iterator to the end
-    @sa @ref rbegin() -- returns a reverse iterator to the beginning
-    @sa @ref crbegin() -- returns a const reverse iterator to the beginning
-
-    @since version 1.0.0
-    */
-    const_reverse_iterator crend() const noexcept
-    {
-        return const_reverse_iterator(cbegin());
-    }
-
-  public:
-    /*!
-    @brief wrapper to access iterator member functions in range-based for
-
-    This function allows to access @ref iterator::key() and @ref
-    iterator::value() during range-based for loops. In these loops, a
-    reference to the JSON values is returned, so there is no access to the
-    underlying iterator.
-
-    For loop without iterator_wrapper:
-
-    @code{cpp}
-    for (auto it = j_object.begin(); it != j_object.end(); ++it)
-    {
-        std::cout << "key: " << it.key() << ", value:" << it.value() << '\n';
-    }
-    @endcode
-
-    Range-based for loop without iterator proxy:
-
-    @code{cpp}
-    for (auto it : j_object)
-    {
-        // "it" is of type json::reference and has no key() member
-        std::cout << "value: " << it << '\n';
-    }
-    @endcode
-
-    Range-based for loop with iterator proxy:
-
-    @code{cpp}
-    for (auto it : json::iterator_wrapper(j_object))
-    {
-        std::cout << "key: " << it.key() << ", value:" << it.value() << '\n';
-    }
-    @endcode
-
-    @note When iterating over an array, `key()` will return the index of the
-          element as string (see example).
-
-    @param[in] ref  reference to a JSON value
-    @return iteration proxy object wrapping @a ref with an interface to use in
-            range-based for loops
-
-    @liveexample{The following code shows how the wrapper is used,iterator_wrapper}
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes in the JSON value.
-
-    @complexity Constant.
-
-    @note The name of this function is not yet final and may change in the
-    future.
-
-    @deprecated This stream operator is deprecated and will be removed in
-                future 4.0.0 of the library. Please use @ref items() instead;
-                that is, replace `json::iterator_wrapper(j)` with `j.items()`.
-    */
-    JSON_HEDLEY_DEPRECATED_FOR(3.1.0, items())
-    static iteration_proxy<iterator> iterator_wrapper(reference ref) noexcept
-    {
-        return ref.items();
-    }
-
-    /*!
-    @copydoc iterator_wrapper(reference)
-    */
-    JSON_HEDLEY_DEPRECATED_FOR(3.1.0, items())
-    static iteration_proxy<const_iterator> iterator_wrapper(const_reference ref) noexcept
-    {
-        return ref.items();
-    }
-
-    /*!
-    @brief helper to access iterator member functions in range-based for
-
-    This function allows to access @ref iterator::key() and @ref
-    iterator::value() during range-based for loops. In these loops, a
-    reference to the JSON values is returned, so there is no access to the
-    underlying iterator.
-
-    For loop without `items()` function:
-
-    @code{cpp}
-    for (auto it = j_object.begin(); it != j_object.end(); ++it)
-    {
-        std::cout << "key: " << it.key() << ", value:" << it.value() << '\n';
-    }
-    @endcode
-
-    Range-based for loop without `items()` function:
-
-    @code{cpp}
-    for (auto it : j_object)
-    {
-        // "it" is of type json::reference and has no key() member
-        std::cout << "value: " << it << '\n';
-    }
-    @endcode
-
-    Range-based for loop with `items()` function:
-
-    @code{cpp}
-    for (auto& el : j_object.items())
-    {
-        std::cout << "key: " << el.key() << ", value:" << el.value() << '\n';
-    }
-    @endcode
-
-    The `items()` function also allows to use
-    [structured bindings](https://en.cppreference.com/w/cpp/language/structured_binding)
-    (C++17):
-
-    @code{cpp}
-    for (auto& [key, val] : j_object.items())
-    {
-        std::cout << "key: " << key << ", value:" << val << '\n';
-    }
-    @endcode
-
-    @note When iterating over an array, `key()` will return the index of the
-          element as string (see example). For primitive types (e.g., numbers),
-          `key()` returns an empty string.
-
-    @warning Using `items()` on temporary objects is dangerous. Make sure the
-             object's lifetime exeeds the iteration. See
-             <https://github.com/nlohmann/json/issues/2040> for more
-             information.
-
-    @return iteration proxy object wrapping @a ref with an interface to use in
-            range-based for loops
-
-    @liveexample{The following code shows how the function is used.,items}
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes in the JSON value.
-
-    @complexity Constant.
-
-    @since version 3.1.0, structured bindings support since 3.5.0.
-    */
-    iteration_proxy<iterator> items() noexcept
-    {
-        return iteration_proxy<iterator>(*this);
-    }
-
-    /*!
-    @copydoc items()
-    */
-    iteration_proxy<const_iterator> items() const noexcept
-    {
-        return iteration_proxy<const_iterator>(*this);
-    }
-
-    /// @}
-
-
-    //////////////
-    // capacity //
-    //////////////
-
-    /// @name capacity
-    /// @{
-
-    /*!
-    @brief checks whether the container is empty.
-
-    Checks if a JSON value has no elements (i.e. whether its @ref size is `0`).
-
-    @return The return value depends on the different types and is
-            defined as follows:
-            Value type  | return value
-            ----------- | -------------
-            null        | `true`
-            boolean     | `false`
-            string      | `false`
-            number      | `false`
-            binary      | `false`
-            object      | result of function `object_t::empty()`
-            array       | result of function `array_t::empty()`
-
-    @liveexample{The following code uses `empty()` to check if a JSON
-    object contains any elements.,empty}
-
-    @complexity Constant, as long as @ref array_t and @ref object_t satisfy
-    the Container concept; that is, their `empty()` functions have constant
-    complexity.
-
-    @iterators No changes.
-
-    @exceptionsafety No-throw guarantee: this function never throws exceptions.
-
-    @note This function does not return whether a string stored as JSON value
-    is empty - it returns whether the JSON container itself is empty which is
-    false in the case of a string.
-
-    @requirement This function helps `basic_json` satisfying the
-    [Container](https://en.cppreference.com/w/cpp/named_req/Container)
-    requirements:
-    - The complexity is constant.
-    - Has the semantics of `begin() == end()`.
-
-    @sa @ref size() -- returns the number of elements
-
-    @since version 1.0.0
-    */
-    bool empty() const noexcept
-    {
-        switch (m_type)
-        {
-            case value_t::null:
-            {
-                // null values are empty
-                return true;
-            }
-
-            case value_t::array:
-            {
-                // delegate call to array_t::empty()
-                return m_value.array->empty();
-            }
-
-            case value_t::object:
-            {
-                // delegate call to object_t::empty()
-                return m_value.object->empty();
-            }
-
-            default:
-            {
-                // all other types are nonempty
-                return false;
-            }
-        }
-    }
-
-    /*!
-    @brief returns the number of elements
-
-    Returns the number of elements in a JSON value.
-
-    @return The return value depends on the different types and is
-            defined as follows:
-            Value type  | return value
-            ----------- | -------------
-            null        | `0`
-            boolean     | `1`
-            string      | `1`
-            number      | `1`
-            binary      | `1`
-            object      | result of function object_t::size()
-            array       | result of function array_t::size()
-
-    @liveexample{The following code calls `size()` on the different value
-    types.,size}
-
-    @complexity Constant, as long as @ref array_t and @ref object_t satisfy
-    the Container concept; that is, their size() functions have constant
-    complexity.
-
-    @iterators No changes.
-
-    @exceptionsafety No-throw guarantee: this function never throws exceptions.
-
-    @note This function does not return the length of a string stored as JSON
-    value - it returns the number of elements in the JSON value which is 1 in
-    the case of a string.
-
-    @requirement This function helps `basic_json` satisfying the
-    [Container](https://en.cppreference.com/w/cpp/named_req/Container)
-    requirements:
-    - The complexity is constant.
-    - Has the semantics of `std::distance(begin(), end())`.
-
-    @sa @ref empty() -- checks whether the container is empty
-    @sa @ref max_size() -- returns the maximal number of elements
-
-    @since version 1.0.0
-    */
-    size_type size() const noexcept
-    {
-        switch (m_type)
-        {
-            case value_t::null:
-            {
-                // null values are empty
-                return 0;
-            }
-
-            case value_t::array:
-            {
-                // delegate call to array_t::size()
-                return m_value.array->size();
-            }
-
-            case value_t::object:
-            {
-                // delegate call to object_t::size()
-                return m_value.object->size();
-            }
-
-            default:
-            {
-                // all other types have size 1
-                return 1;
-            }
-        }
-    }
-
-    /*!
-    @brief returns the maximum possible number of elements
-
-    Returns the maximum number of elements a JSON value is able to hold due to
-    system or library implementation limitations, i.e. `std::distance(begin(),
-    end())` for the JSON value.
-
-    @return The return value depends on the different types and is
-            defined as follows:
-            Value type  | return value
-            ----------- | -------------
-            null        | `0` (same as `size()`)
-            boolean     | `1` (same as `size()`)
-            string      | `1` (same as `size()`)
-            number      | `1` (same as `size()`)
-            binary      | `1` (same as `size()`)
-            object      | result of function `object_t::max_size()`
-            array       | result of function `array_t::max_size()`
-
-    @liveexample{The following code calls `max_size()` on the different value
-    types. Note the output is implementation specific.,max_size}
-
-    @complexity Constant, as long as @ref array_t and @ref object_t satisfy
-    the Container concept; that is, their `max_size()` functions have constant
-    complexity.
-
-    @iterators No changes.
-
-    @exceptionsafety No-throw guarantee: this function never throws exceptions.
-
-    @requirement This function helps `basic_json` satisfying the
-    [Container](https://en.cppreference.com/w/cpp/named_req/Container)
-    requirements:
-    - The complexity is constant.
-    - Has the semantics of returning `b.size()` where `b` is the largest
-      possible JSON value.
-
-    @sa @ref size() -- returns the number of elements
-
-    @since version 1.0.0
-    */
-    size_type max_size() const noexcept
-    {
-        switch (m_type)
-        {
-            case value_t::array:
-            {
-                // delegate call to array_t::max_size()
-                return m_value.array->max_size();
-            }
-
-            case value_t::object:
-            {
-                // delegate call to object_t::max_size()
-                return m_value.object->max_size();
-            }
-
-            default:
-            {
-                // all other types have max_size() == size()
-                return size();
-            }
-        }
-    }
-
-    /// @}
-
-
-    ///////////////
-    // modifiers //
-    ///////////////
-
-    /// @name modifiers
-    /// @{
-
-    /*!
-    @brief clears the contents
-
-    Clears the content of a JSON value and resets it to the default value as
-    if @ref basic_json(value_t) would have been called with the current value
-    type from @ref type():
-
-    Value type  | initial value
-    ----------- | -------------
-    null        | `null`
-    boolean     | `false`
-    string      | `""`
-    number      | `0`
-    binary      | An empty byte vector
-    object      | `{}`
-    array       | `[]`
-
-    @post Has the same effect as calling
-    @code {.cpp}
-    *this = basic_json(type());
-    @endcode
-
-    @liveexample{The example below shows the effect of `clear()` to different
-    JSON types.,clear}
-
-    @complexity Linear in the size of the JSON value.
-
-    @iterators All iterators, pointers and references related to this container
-               are invalidated.
-
-    @exceptionsafety No-throw guarantee: this function never throws exceptions.
-
-    @sa @ref basic_json(value_t) -- constructor that creates an object with the
-        same value than calling `clear()`
-
-    @since version 1.0.0
-    */
-    void clear() noexcept
-    {
-        switch (m_type)
-        {
-            case value_t::number_integer:
-            {
-                m_value.number_integer = 0;
-                break;
-            }
-
-            case value_t::number_unsigned:
-            {
-                m_value.number_unsigned = 0;
-                break;
-            }
-
-            case value_t::number_float:
-            {
-                m_value.number_float = 0.0;
-                break;
-            }
-
-            case value_t::boolean:
-            {
-                m_value.boolean = false;
-                break;
-            }
-
-            case value_t::string:
-            {
-                m_value.string->clear();
-                break;
-            }
-
-            case value_t::binary:
-            {
-                m_value.binary->clear();
-                break;
-            }
-
-            case value_t::array:
-            {
-                m_value.array->clear();
-                break;
-            }
-
-            case value_t::object:
-            {
-                m_value.object->clear();
-                break;
-            }
-
-            default:
-                break;
-        }
-    }
-
-    /*!
-    @brief add an object to an array
-
-    Appends the given element @a val to the end of the JSON value. If the
-    function is called on a JSON null value, an empty array is created before
-    appending @a val.
-
-    @param[in] val the value to add to the JSON array
-
-    @throw type_error.308 when called on a type other than JSON array or
-    null; example: `"cannot use push_back() with number"`
-
-    @complexity Amortized constant.
-
-    @liveexample{The example shows how `push_back()` and `+=` can be used to
-    add elements to a JSON array. Note how the `null` value was silently
-    converted to a JSON array.,push_back}
-
-    @since version 1.0.0
-    */
-    void push_back(basic_json&& val)
-    {
-        // push_back only works for null objects or arrays
-        if (JSON_HEDLEY_UNLIKELY(!(is_null() || is_array())))
-        {
-            JSON_THROW(type_error::create(308, "cannot use push_back() with " + std::string(type_name())));
-        }
-
-        // transform null object into an array
-        if (is_null())
-        {
-            m_type = value_t::array;
-            m_value = value_t::array;
-            assert_invariant();
-        }
-
-        // add element to array (move semantics)
-        m_value.array->push_back(std::move(val));
-        // if val is moved from, basic_json move constructor marks it null so we do not call the destructor
-    }
-
-    /*!
-    @brief add an object to an array
-    @copydoc push_back(basic_json&&)
-    */
-    reference operator+=(basic_json&& val)
-    {
-        push_back(std::move(val));
-        return *this;
-    }
-
-    /*!
-    @brief add an object to an array
-    @copydoc push_back(basic_json&&)
-    */
-    void push_back(const basic_json& val)
-    {
-        // push_back only works for null objects or arrays
-        if (JSON_HEDLEY_UNLIKELY(!(is_null() || is_array())))
-        {
-            JSON_THROW(type_error::create(308, "cannot use push_back() with " + std::string(type_name())));
-        }
-
-        // transform null object into an array
-        if (is_null())
-        {
-            m_type = value_t::array;
-            m_value = value_t::array;
-            assert_invariant();
-        }
-
-        // add element to array
-        m_value.array->push_back(val);
-    }
-
-    /*!
-    @brief add an object to an array
-    @copydoc push_back(basic_json&&)
-    */
-    reference operator+=(const basic_json& val)
-    {
-        push_back(val);
-        return *this;
-    }
-
-    /*!
-    @brief add an object to an object
-
-    Inserts the given element @a val to the JSON object. If the function is
-    called on a JSON null value, an empty object is created before inserting
-    @a val.
-
-    @param[in] val the value to add to the JSON object
-
-    @throw type_error.308 when called on a type other than JSON object or
-    null; example: `"cannot use push_back() with number"`
-
-    @complexity Logarithmic in the size of the container, O(log(`size()`)).
-
-    @liveexample{The example shows how `push_back()` and `+=` can be used to
-    add elements to a JSON object. Note how the `null` value was silently
-    converted to a JSON object.,push_back__object_t__value}
-
-    @since version 1.0.0
-    */
-    void push_back(const typename object_t::value_type& val)
-    {
-        // push_back only works for null objects or objects
-        if (JSON_HEDLEY_UNLIKELY(!(is_null() || is_object())))
-        {
-            JSON_THROW(type_error::create(308, "cannot use push_back() with " + std::string(type_name())));
-        }
-
-        // transform null object into an object
-        if (is_null())
-        {
-            m_type = value_t::object;
-            m_value = value_t::object;
-            assert_invariant();
-        }
-
-        // add element to array
-        m_value.object->insert(val);
-    }
-
-    /*!
-    @brief add an object to an object
-    @copydoc push_back(const typename object_t::value_type&)
-    */
-    reference operator+=(const typename object_t::value_type& val)
-    {
-        push_back(val);
-        return *this;
-    }
-
-    /*!
-    @brief add an object to an object
-
-    This function allows to use `push_back` with an initializer list. In case
-
-    1. the current value is an object,
-    2. the initializer list @a init contains only two elements, and
-    3. the first element of @a init is a string,
-
-    @a init is converted into an object element and added using
-    @ref push_back(const typename object_t::value_type&). Otherwise, @a init
-    is converted to a JSON value and added using @ref push_back(basic_json&&).
-
-    @param[in] init  an initializer list
-
-    @complexity Linear in the size of the initializer list @a init.
-
-    @note This function is required to resolve an ambiguous overload error,
-          because pairs like `{"key", "value"}` can be both interpreted as
-          `object_t::value_type` or `std::initializer_list<basic_json>`, see
-          https://github.com/nlohmann/json/issues/235 for more information.
-
-    @liveexample{The example shows how initializer lists are treated as
-    objects when possible.,push_back__initializer_list}
-    */
-    void push_back(initializer_list_t init)
-    {
-        if (is_object() && init.size() == 2 && (*init.begin())->is_string())
-        {
-            basic_json&& key = init.begin()->moved_or_copied();
-            push_back(typename object_t::value_type(
-                          std::move(key.get_ref<string_t&>()), (init.begin() + 1)->moved_or_copied()));
-        }
-        else
-        {
-            push_back(basic_json(init));
-        }
-    }
-
-    /*!
-    @brief add an object to an object
-    @copydoc push_back(initializer_list_t)
-    */
-    reference operator+=(initializer_list_t init)
-    {
-        push_back(init);
-        return *this;
-    }
-
-    /*!
-    @brief add an object to an array
-
-    Creates a JSON value from the passed parameters @a args to the end of the
-    JSON value. If the function is called on a JSON null value, an empty array
-    is created before appending the value created from @a args.
-
-    @param[in] args arguments to forward to a constructor of @ref basic_json
-    @tparam Args compatible types to create a @ref basic_json object
-
-    @return reference to the inserted element
-
-    @throw type_error.311 when called on a type other than JSON array or
-    null; example: `"cannot use emplace_back() with number"`
-
-    @complexity Amortized constant.
-
-    @liveexample{The example shows how `push_back()` can be used to add
-    elements to a JSON array. Note how the `null` value was silently converted
-    to a JSON array.,emplace_back}
-
-    @since version 2.0.8, returns reference since 3.7.0
-    */
-    template<class... Args>
-    reference emplace_back(Args&& ... args)
-    {
-        // emplace_back only works for null objects or arrays
-        if (JSON_HEDLEY_UNLIKELY(!(is_null() || is_array())))
-        {
-            JSON_THROW(type_error::create(311, "cannot use emplace_back() with " + std::string(type_name())));
-        }
-
-        // transform null object into an array
-        if (is_null())
-        {
-            m_type = value_t::array;
-            m_value = value_t::array;
-            assert_invariant();
-        }
-
-        // add element to array (perfect forwarding)
-#ifdef JSON_HAS_CPP_17
-        return m_value.array->emplace_back(std::forward<Args>(args)...);
-#else
-        m_value.array->emplace_back(std::forward<Args>(args)...);
-        return m_value.array->back();
-#endif
-    }
-
-    /*!
-    @brief add an object to an object if key does not exist
-
-    Inserts a new element into a JSON object constructed in-place with the
-    given @a args if there is no element with the key in the container. If the
-    function is called on a JSON null value, an empty object is created before
-    appending the value created from @a args.
-
-    @param[in] args arguments to forward to a constructor of @ref basic_json
-    @tparam Args compatible types to create a @ref basic_json object
-
-    @return a pair consisting of an iterator to the inserted element, or the
-            already-existing element if no insertion happened, and a bool
-            denoting whether the insertion took place.
-
-    @throw type_error.311 when called on a type other than JSON object or
-    null; example: `"cannot use emplace() with number"`
-
-    @complexity Logarithmic in the size of the container, O(log(`size()`)).
-
-    @liveexample{The example shows how `emplace()` can be used to add elements
-    to a JSON object. Note how the `null` value was silently converted to a
-    JSON object. Further note how no value is added if there was already one
-    value stored with the same key.,emplace}
-
-    @since version 2.0.8
-    */
-    template<class... Args>
-    std::pair<iterator, bool> emplace(Args&& ... args)
-    {
-        // emplace only works for null objects or arrays
-        if (JSON_HEDLEY_UNLIKELY(!(is_null() || is_object())))
-        {
-            JSON_THROW(type_error::create(311, "cannot use emplace() with " + std::string(type_name())));
-        }
-
-        // transform null object into an object
-        if (is_null())
-        {
-            m_type = value_t::object;
-            m_value = value_t::object;
-            assert_invariant();
-        }
-
-        // add element to array (perfect forwarding)
-        auto res = m_value.object->emplace(std::forward<Args>(args)...);
-        // create result iterator and set iterator to the result of emplace
-        auto it = begin();
-        it.m_it.object_iterator = res.first;
-
-        // return pair of iterator and boolean
-        return {it, res.second};
-    }
-
-    /// Helper for insertion of an iterator
-    /// @note: This uses std::distance to support GCC 4.8,
-    ///        see https://github.com/nlohmann/json/pull/1257
-    template<typename... Args>
-    iterator insert_iterator(const_iterator pos, Args&& ... args)
-    {
-        iterator result(this);
-        JSON_ASSERT(m_value.array != nullptr);
-
-        auto insert_pos = std::distance(m_value.array->begin(), pos.m_it.array_iterator);
-        m_value.array->insert(pos.m_it.array_iterator, std::forward<Args>(args)...);
-        result.m_it.array_iterator = m_value.array->begin() + insert_pos;
-
-        // This could have been written as:
-        // result.m_it.array_iterator = m_value.array->insert(pos.m_it.array_iterator, cnt, val);
-        // but the return value of insert is missing in GCC 4.8, so it is written this way instead.
-
-        return result;
-    }
-
-    /*!
-    @brief inserts element
-
-    Inserts element @a val before iterator @a pos.
-
-    @param[in] pos iterator before which the content will be inserted; may be
-    the end() iterator
-    @param[in] val element to insert
-    @return iterator pointing to the inserted @a val.
-
-    @throw type_error.309 if called on JSON values other than arrays;
-    example: `"cannot use insert() with string"`
-    @throw invalid_iterator.202 if @a pos is not an iterator of *this;
-    example: `"iterator does not fit current value"`
-
-    @complexity Constant plus linear in the distance between @a pos and end of
-    the container.
-
-    @liveexample{The example shows how `insert()` is used.,insert}
-
-    @since version 1.0.0
-    */
-    iterator insert(const_iterator pos, const basic_json& val)
-    {
-        // insert only works for arrays
-        if (JSON_HEDLEY_LIKELY(is_array()))
-        {
-            // check if iterator pos fits to this JSON value
-            if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
-            {
-                JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value"));
-            }
-
-            // insert to array and return iterator
-            return insert_iterator(pos, val);
-        }
-
-        JSON_THROW(type_error::create(309, "cannot use insert() with " + std::string(type_name())));
-    }
-
-    /*!
-    @brief inserts element
-    @copydoc insert(const_iterator, const basic_json&)
-    */
-    iterator insert(const_iterator pos, basic_json&& val)
-    {
-        return insert(pos, val);
-    }
-
-    /*!
-    @brief inserts elements
-
-    Inserts @a cnt copies of @a val before iterator @a pos.
-
-    @param[in] pos iterator before which the content will be inserted; may be
-    the end() iterator
-    @param[in] cnt number of copies of @a val to insert
-    @param[in] val element to insert
-    @return iterator pointing to the first element inserted, or @a pos if
-    `cnt==0`
-
-    @throw type_error.309 if called on JSON values other than arrays; example:
-    `"cannot use insert() with string"`
-    @throw invalid_iterator.202 if @a pos is not an iterator of *this;
-    example: `"iterator does not fit current value"`
-
-    @complexity Linear in @a cnt plus linear in the distance between @a pos
-    and end of the container.
-
-    @liveexample{The example shows how `insert()` is used.,insert__count}
-
-    @since version 1.0.0
-    */
-    iterator insert(const_iterator pos, size_type cnt, const basic_json& val)
-    {
-        // insert only works for arrays
-        if (JSON_HEDLEY_LIKELY(is_array()))
-        {
-            // check if iterator pos fits to this JSON value
-            if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
-            {
-                JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value"));
-            }
-
-            // insert to array and return iterator
-            return insert_iterator(pos, cnt, val);
-        }
-
-        JSON_THROW(type_error::create(309, "cannot use insert() with " + std::string(type_name())));
-    }
-
-    /*!
-    @brief inserts elements
-
-    Inserts elements from range `[first, last)` before iterator @a pos.
-
-    @param[in] pos iterator before which the content will be inserted; may be
-    the end() iterator
-    @param[in] first begin of the range of elements to insert
-    @param[in] last end of the range of elements to insert
-
-    @throw type_error.309 if called on JSON values other than arrays; example:
-    `"cannot use insert() with string"`
-    @throw invalid_iterator.202 if @a pos is not an iterator of *this;
-    example: `"iterator does not fit current value"`
-    @throw invalid_iterator.210 if @a first and @a last do not belong to the
-    same JSON value; example: `"iterators do not fit"`
-    @throw invalid_iterator.211 if @a first or @a last are iterators into
-    container for which insert is called; example: `"passed iterators may not
-    belong to container"`
-
-    @return iterator pointing to the first element inserted, or @a pos if
-    `first==last`
-
-    @complexity Linear in `std::distance(first, last)` plus linear in the
-    distance between @a pos and end of the container.
-
-    @liveexample{The example shows how `insert()` is used.,insert__range}
-
-    @since version 1.0.0
-    */
-    iterator insert(const_iterator pos, const_iterator first, const_iterator last)
-    {
-        // insert only works for arrays
-        if (JSON_HEDLEY_UNLIKELY(!is_array()))
-        {
-            JSON_THROW(type_error::create(309, "cannot use insert() with " + std::string(type_name())));
-        }
-
-        // check if iterator pos fits to this JSON value
-        if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
-        {
-            JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value"));
-        }
-
-        // check if range iterators belong to the same JSON object
-        if (JSON_HEDLEY_UNLIKELY(first.m_object != last.m_object))
-        {
-            JSON_THROW(invalid_iterator::create(210, "iterators do not fit"));
-        }
-
-        if (JSON_HEDLEY_UNLIKELY(first.m_object == this))
-        {
-            JSON_THROW(invalid_iterator::create(211, "passed iterators may not belong to container"));
-        }
-
-        // insert to array and return iterator
-        return insert_iterator(pos, first.m_it.array_iterator, last.m_it.array_iterator);
-    }
-
-    /*!
-    @brief inserts elements
-
-    Inserts elements from initializer list @a ilist before iterator @a pos.
-
-    @param[in] pos iterator before which the content will be inserted; may be
-    the end() iterator
-    @param[in] ilist initializer list to insert the values from
-
-    @throw type_error.309 if called on JSON values other than arrays; example:
-    `"cannot use insert() with string"`
-    @throw invalid_iterator.202 if @a pos is not an iterator of *this;
-    example: `"iterator does not fit current value"`
-
-    @return iterator pointing to the first element inserted, or @a pos if
-    `ilist` is empty
-
-    @complexity Linear in `ilist.size()` plus linear in the distance between
-    @a pos and end of the container.
-
-    @liveexample{The example shows how `insert()` is used.,insert__ilist}
-
-    @since version 1.0.0
-    */
-    iterator insert(const_iterator pos, initializer_list_t ilist)
-    {
-        // insert only works for arrays
-        if (JSON_HEDLEY_UNLIKELY(!is_array()))
-        {
-            JSON_THROW(type_error::create(309, "cannot use insert() with " + std::string(type_name())));
-        }
-
-        // check if iterator pos fits to this JSON value
-        if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
-        {
-            JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value"));
-        }
-
-        // insert to array and return iterator
-        return insert_iterator(pos, ilist.begin(), ilist.end());
-    }
-
-    /*!
-    @brief inserts elements
-
-    Inserts elements from range `[first, last)`.
-
-    @param[in] first begin of the range of elements to insert
-    @param[in] last end of the range of elements to insert
-
-    @throw type_error.309 if called on JSON values other than objects; example:
-    `"cannot use insert() with string"`
-    @throw invalid_iterator.202 if iterator @a first or @a last does does not
-    point to an object; example: `"iterators first and last must point to
-    objects"`
-    @throw invalid_iterator.210 if @a first and @a last do not belong to the
-    same JSON value; example: `"iterators do not fit"`
-
-    @complexity Logarithmic: `O(N*log(size() + N))`, where `N` is the number
-    of elements to insert.
-
-    @liveexample{The example shows how `insert()` is used.,insert__range_object}
-
-    @since version 3.0.0
-    */
-    void insert(const_iterator first, const_iterator last)
-    {
-        // insert only works for objects
-        if (JSON_HEDLEY_UNLIKELY(!is_object()))
-        {
-            JSON_THROW(type_error::create(309, "cannot use insert() with " + std::string(type_name())));
-        }
-
-        // check if range iterators belong to the same JSON object
-        if (JSON_HEDLEY_UNLIKELY(first.m_object != last.m_object))
-        {
-            JSON_THROW(invalid_iterator::create(210, "iterators do not fit"));
-        }
-
-        // passed iterators must belong to objects
-        if (JSON_HEDLEY_UNLIKELY(!first.m_object->is_object()))
-        {
-            JSON_THROW(invalid_iterator::create(202, "iterators first and last must point to objects"));
-        }
-
-        m_value.object->insert(first.m_it.object_iterator, last.m_it.object_iterator);
-    }
-
-    /*!
-    @brief updates a JSON object from another object, overwriting existing keys
-
-    Inserts all values from JSON object @a j and overwrites existing keys.
-
-    @param[in] j  JSON object to read values from
-
-    @throw type_error.312 if called on JSON values other than objects; example:
-    `"cannot use update() with string"`
-
-    @complexity O(N*log(size() + N)), where N is the number of elements to
-                insert.
-
-    @liveexample{The example shows how `update()` is used.,update}
-
-    @sa https://docs.python.org/3.6/library/stdtypes.html#dict.update
-
-    @since version 3.0.0
-    */
-    void update(const_reference j)
-    {
-        // implicitly convert null value to an empty object
-        if (is_null())
-        {
-            m_type = value_t::object;
-            m_value.object = create<object_t>();
-            assert_invariant();
-        }
-
-        if (JSON_HEDLEY_UNLIKELY(!is_object()))
-        {
-            JSON_THROW(type_error::create(312, "cannot use update() with " + std::string(type_name())));
-        }
-        if (JSON_HEDLEY_UNLIKELY(!j.is_object()))
-        {
-            JSON_THROW(type_error::create(312, "cannot use update() with " + std::string(j.type_name())));
-        }
-
-        for (auto it = j.cbegin(); it != j.cend(); ++it)
-        {
-            m_value.object->operator[](it.key()) = it.value();
-        }
-    }
-
-    /*!
-    @brief updates a JSON object from another object, overwriting existing keys
-
-    Inserts all values from from range `[first, last)` and overwrites existing
-    keys.
-
-    @param[in] first begin of the range of elements to insert
-    @param[in] last end of the range of elements to insert
-
-    @throw type_error.312 if called on JSON values other than objects; example:
-    `"cannot use update() with string"`
-    @throw invalid_iterator.202 if iterator @a first or @a last does does not
-    point to an object; example: `"iterators first and last must point to
-    objects"`
-    @throw invalid_iterator.210 if @a first and @a last do not belong to the
-    same JSON value; example: `"iterators do not fit"`
-
-    @complexity O(N*log(size() + N)), where N is the number of elements to
-                insert.
-
-    @liveexample{The example shows how `update()` is used__range.,update}
-
-    @sa https://docs.python.org/3.6/library/stdtypes.html#dict.update
-
-    @since version 3.0.0
-    */
-    void update(const_iterator first, const_iterator last)
-    {
-        // implicitly convert null value to an empty object
-        if (is_null())
-        {
-            m_type = value_t::object;
-            m_value.object = create<object_t>();
-            assert_invariant();
-        }
-
-        if (JSON_HEDLEY_UNLIKELY(!is_object()))
-        {
-            JSON_THROW(type_error::create(312, "cannot use update() with " + std::string(type_name())));
-        }
-
-        // check if range iterators belong to the same JSON object
-        if (JSON_HEDLEY_UNLIKELY(first.m_object != last.m_object))
-        {
-            JSON_THROW(invalid_iterator::create(210, "iterators do not fit"));
-        }
-
-        // passed iterators must belong to objects
-        if (JSON_HEDLEY_UNLIKELY(!first.m_object->is_object()
-                                 || !last.m_object->is_object()))
-        {
-            JSON_THROW(invalid_iterator::create(202, "iterators first and last must point to objects"));
-        }
-
-        for (auto it = first; it != last; ++it)
-        {
-            m_value.object->operator[](it.key()) = it.value();
-        }
-    }
-
-    /*!
-    @brief exchanges the values
-
-    Exchanges the contents of the JSON value with those of @a other. Does not
-    invoke any move, copy, or swap operations on individual elements. All
-    iterators and references remain valid. The past-the-end iterator is
-    invalidated.
-
-    @param[in,out] other JSON value to exchange the contents with
-
-    @complexity Constant.
-
-    @liveexample{The example below shows how JSON values can be swapped with
-    `swap()`.,swap__reference}
-
-    @since version 1.0.0
-    */
-    void swap(reference other) noexcept (
-        std::is_nothrow_move_constructible<value_t>::value&&
-        std::is_nothrow_move_assignable<value_t>::value&&
-        std::is_nothrow_move_constructible<json_value>::value&&
-        std::is_nothrow_move_assignable<json_value>::value
-    )
-    {
-        std::swap(m_type, other.m_type);
-        std::swap(m_value, other.m_value);
-        assert_invariant();
-    }
-
-    /*!
-    @brief exchanges the values
-
-    Exchanges the contents of the JSON value from @a left with those of @a right. Does not
-    invoke any move, copy, or swap operations on individual elements. All
-    iterators and references remain valid. The past-the-end iterator is
-    invalidated. implemented as a friend function callable via ADL.
-
-    @param[in,out] left JSON value to exchange the contents with
-    @param[in,out] right JSON value to exchange the contents with
-
-    @complexity Constant.
-
-    @liveexample{The example below shows how JSON values can be swapped with
-    `swap()`.,swap__reference}
-
-    @since version 1.0.0
-    */
-    friend void swap(reference left, reference right) noexcept (
-        std::is_nothrow_move_constructible<value_t>::value&&
-        std::is_nothrow_move_assignable<value_t>::value&&
-        std::is_nothrow_move_constructible<json_value>::value&&
-        std::is_nothrow_move_assignable<json_value>::value
-    )
-    {
-        left.swap(right);
-    }
-
-    /*!
-    @brief exchanges the values
-
-    Exchanges the contents of a JSON array with those of @a other. Does not
-    invoke any move, copy, or swap operations on individual elements. All
-    iterators and references remain valid. The past-the-end iterator is
-    invalidated.
-
-    @param[in,out] other array to exchange the contents with
-
-    @throw type_error.310 when JSON value is not an array; example: `"cannot
-    use swap() with string"`
-
-    @complexity Constant.
-
-    @liveexample{The example below shows how arrays can be swapped with
-    `swap()`.,swap__array_t}
-
-    @since version 1.0.0
-    */
-    void swap(array_t& other)
-    {
-        // swap only works for arrays
-        if (JSON_HEDLEY_LIKELY(is_array()))
-        {
-            std::swap(*(m_value.array), other);
-        }
-        else
-        {
-            JSON_THROW(type_error::create(310, "cannot use swap() with " + std::string(type_name())));
-        }
-    }
-
-    /*!
-    @brief exchanges the values
-
-    Exchanges the contents of a JSON object with those of @a other. Does not
-    invoke any move, copy, or swap operations on individual elements. All
-    iterators and references remain valid. The past-the-end iterator is
-    invalidated.
-
-    @param[in,out] other object to exchange the contents with
-
-    @throw type_error.310 when JSON value is not an object; example:
-    `"cannot use swap() with string"`
-
-    @complexity Constant.
-
-    @liveexample{The example below shows how objects can be swapped with
-    `swap()`.,swap__object_t}
-
-    @since version 1.0.0
-    */
-    void swap(object_t& other)
-    {
-        // swap only works for objects
-        if (JSON_HEDLEY_LIKELY(is_object()))
-        {
-            std::swap(*(m_value.object), other);
-        }
-        else
-        {
-            JSON_THROW(type_error::create(310, "cannot use swap() with " + std::string(type_name())));
-        }
-    }
-
-    /*!
-    @brief exchanges the values
-
-    Exchanges the contents of a JSON string with those of @a other. Does not
-    invoke any move, copy, or swap operations on individual elements. All
-    iterators and references remain valid. The past-the-end iterator is
-    invalidated.
-
-    @param[in,out] other string to exchange the contents with
-
-    @throw type_error.310 when JSON value is not a string; example: `"cannot
-    use swap() with boolean"`
-
-    @complexity Constant.
-
-    @liveexample{The example below shows how strings can be swapped with
-    `swap()`.,swap__string_t}
-
-    @since version 1.0.0
-    */
-    void swap(string_t& other)
-    {
-        // swap only works for strings
-        if (JSON_HEDLEY_LIKELY(is_string()))
-        {
-            std::swap(*(m_value.string), other);
-        }
-        else
-        {
-            JSON_THROW(type_error::create(310, "cannot use swap() with " + std::string(type_name())));
-        }
-    }
-
-    /*!
-    @brief exchanges the values
-
-    Exchanges the contents of a JSON string with those of @a other. Does not
-    invoke any move, copy, or swap operations on individual elements. All
-    iterators and references remain valid. The past-the-end iterator is
-    invalidated.
-
-    @param[in,out] other binary to exchange the contents with
-
-    @throw type_error.310 when JSON value is not a string; example: `"cannot
-    use swap() with boolean"`
-
-    @complexity Constant.
-
-    @liveexample{The example below shows how strings can be swapped with
-    `swap()`.,swap__binary_t}
-
-    @since version 3.8.0
-    */
-    void swap(binary_t& other)
-    {
-        // swap only works for strings
-        if (JSON_HEDLEY_LIKELY(is_binary()))
-        {
-            std::swap(*(m_value.binary), other);
-        }
-        else
-        {
-            JSON_THROW(type_error::create(310, "cannot use swap() with " + std::string(type_name())));
-        }
-    }
-
-    /// @copydoc swap(binary_t)
-    void swap(typename binary_t::container_type& other)
-    {
-        // swap only works for strings
-        if (JSON_HEDLEY_LIKELY(is_binary()))
-        {
-            std::swap(*(m_value.binary), other);
-        }
-        else
-        {
-            JSON_THROW(type_error::create(310, "cannot use swap() with " + std::string(type_name())));
-        }
-    }
-
-    /// @}
-
-  public:
-    //////////////////////////////////////////
-    // lexicographical comparison operators //
-    //////////////////////////////////////////
-
-    /// @name lexicographical comparison operators
-    /// @{
-
-    /*!
-    @brief comparison: equal
-
-    Compares two JSON values for equality according to the following rules:
-    - Two JSON values are equal if (1) they are from the same type and (2)
-      their stored values are the same according to their respective
-      `operator==`.
-    - Integer and floating-point numbers are automatically converted before
-      comparison. Note that two NaN values are always treated as unequal.
-    - Two JSON null values are equal.
-
-    @note Floating-point inside JSON values numbers are compared with
-    `json::number_float_t::operator==` which is `double::operator==` by
-    default. To compare floating-point while respecting an epsilon, an alternative
-    [comparison function](https://github.com/mariokonrad/marnav/blob/master/include/marnav/math/floatingpoint.hpp#L34-#L39)
-    could be used, for instance
-    @code {.cpp}
-    template<typename T, typename = typename std::enable_if<std::is_floating_point<T>::value, T>::type>
-    inline bool is_same(T a, T b, T epsilon = std::numeric_limits<T>::epsilon()) noexcept
-    {
-        return std::abs(a - b) <= epsilon;
-    }
-    @endcode
-    Or you can self-defined operator equal function like this:
-    @code {.cpp}
-    bool my_equal(const_reference lhs, const_reference rhs) {
-    const auto lhs_type lhs.type();
-    const auto rhs_type rhs.type();
-    if (lhs_type == rhs_type) {
-        switch(lhs_type)
-            // self_defined case
-            case value_t::number_float:
-                return std::abs(lhs - rhs) <= std::numeric_limits<float>::epsilon();
-            // other cases remain the same with the original
-            ...
-    }
-    ...
-    }
-    @endcode
-
-    @note NaN values never compare equal to themselves or to other NaN values.
-
-    @param[in] lhs  first JSON value to consider
-    @param[in] rhs  second JSON value to consider
-    @return whether the values @a lhs and @a rhs are equal
-
-    @exceptionsafety No-throw guarantee: this function never throws exceptions.
-
-    @complexity Linear.
-
-    @liveexample{The example demonstrates comparing several JSON
-    types.,operator__equal}
-
-    @since version 1.0.0
-    */
-    friend bool operator==(const_reference lhs, const_reference rhs) noexcept
-    {
-        const auto lhs_type = lhs.type();
-        const auto rhs_type = rhs.type();
-
-        if (lhs_type == rhs_type)
-        {
-            switch (lhs_type)
-            {
-                case value_t::array:
-                    return *lhs.m_value.array == *rhs.m_value.array;
-
-                case value_t::object:
-                    return *lhs.m_value.object == *rhs.m_value.object;
-
-                case value_t::null:
-                    return true;
-
-                case value_t::string:
-                    return *lhs.m_value.string == *rhs.m_value.string;
-
-                case value_t::boolean:
-                    return lhs.m_value.boolean == rhs.m_value.boolean;
-
-                case value_t::number_integer:
-                    return lhs.m_value.number_integer == rhs.m_value.number_integer;
-
-                case value_t::number_unsigned:
-                    return lhs.m_value.number_unsigned == rhs.m_value.number_unsigned;
-
-                case value_t::number_float:
-                    return lhs.m_value.number_float == rhs.m_value.number_float;
-
-                case value_t::binary:
-                    return *lhs.m_value.binary == *rhs.m_value.binary;
-
-                default:
-                    return false;
-            }
-        }
-        else if (lhs_type == value_t::number_integer && rhs_type == value_t::number_float)
-        {
-            return static_cast<number_float_t>(lhs.m_value.number_integer) == rhs.m_value.number_float;
-        }
-        else if (lhs_type == value_t::number_float && rhs_type == value_t::number_integer)
-        {
-            return lhs.m_value.number_float == static_cast<number_float_t>(rhs.m_value.number_integer);
-        }
-        else if (lhs_type == value_t::number_unsigned && rhs_type == value_t::number_float)
-        {
-            return static_cast<number_float_t>(lhs.m_value.number_unsigned) == rhs.m_value.number_float;
-        }
-        else if (lhs_type == value_t::number_float && rhs_type == value_t::number_unsigned)
-        {
-            return lhs.m_value.number_float == static_cast<number_float_t>(rhs.m_value.number_unsigned);
-        }
-        else if (lhs_type == value_t::number_unsigned && rhs_type == value_t::number_integer)
-        {
-            return static_cast<number_integer_t>(lhs.m_value.number_unsigned) == rhs.m_value.number_integer;
-        }
-        else if (lhs_type == value_t::number_integer && rhs_type == value_t::number_unsigned)
-        {
-            return lhs.m_value.number_integer == static_cast<number_integer_t>(rhs.m_value.number_unsigned);
-        }
-
-        return false;
-    }
-
-    /*!
-    @brief comparison: equal
-    @copydoc operator==(const_reference, const_reference)
-    */
-    template<typename ScalarType, typename std::enable_if<
-                 std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator==(const_reference lhs, const ScalarType rhs) noexcept
-    {
-        return lhs == basic_json(rhs);
-    }
-
-    /*!
-    @brief comparison: equal
-    @copydoc operator==(const_reference, const_reference)
-    */
-    template<typename ScalarType, typename std::enable_if<
-                 std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator==(const ScalarType lhs, const_reference rhs) noexcept
-    {
-        return basic_json(lhs) == rhs;
-    }
-
-    /*!
-    @brief comparison: not equal
-
-    Compares two JSON values for inequality by calculating `not (lhs == rhs)`.
-
-    @param[in] lhs  first JSON value to consider
-    @param[in] rhs  second JSON value to consider
-    @return whether the values @a lhs and @a rhs are not equal
-
-    @complexity Linear.
-
-    @exceptionsafety No-throw guarantee: this function never throws exceptions.
-
-    @liveexample{The example demonstrates comparing several JSON
-    types.,operator__notequal}
-
-    @since version 1.0.0
-    */
-    friend bool operator!=(const_reference lhs, const_reference rhs) noexcept
-    {
-        return !(lhs == rhs);
-    }
-
-    /*!
-    @brief comparison: not equal
-    @copydoc operator!=(const_reference, const_reference)
-    */
-    template<typename ScalarType, typename std::enable_if<
-                 std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator!=(const_reference lhs, const ScalarType rhs) noexcept
-    {
-        return lhs != basic_json(rhs);
-    }
-
-    /*!
-    @brief comparison: not equal
-    @copydoc operator!=(const_reference, const_reference)
-    */
-    template<typename ScalarType, typename std::enable_if<
-                 std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator!=(const ScalarType lhs, const_reference rhs) noexcept
-    {
-        return basic_json(lhs) != rhs;
-    }
-
-    /*!
-    @brief comparison: less than
-
-    Compares whether one JSON value @a lhs is less than another JSON value @a
-    rhs according to the following rules:
-    - If @a lhs and @a rhs have the same type, the values are compared using
-      the default `<` operator.
-    - Integer and floating-point numbers are automatically converted before
-      comparison
-    - In case @a lhs and @a rhs have different types, the values are ignored
-      and the order of the types is considered, see
-      @ref operator<(const value_t, const value_t).
-
-    @param[in] lhs  first JSON value to consider
-    @param[in] rhs  second JSON value to consider
-    @return whether @a lhs is less than @a rhs
-
-    @complexity Linear.
-
-    @exceptionsafety No-throw guarantee: this function never throws exceptions.
-
-    @liveexample{The example demonstrates comparing several JSON
-    types.,operator__less}
-
-    @since version 1.0.0
-    */
-    friend bool operator<(const_reference lhs, const_reference rhs) noexcept
-    {
-        const auto lhs_type = lhs.type();
-        const auto rhs_type = rhs.type();
-
-        if (lhs_type == rhs_type)
-        {
-            switch (lhs_type)
-            {
-                case value_t::array:
-                    // note parentheses are necessary, see
-                    // https://github.com/nlohmann/json/issues/1530
-                    return (*lhs.m_value.array) < (*rhs.m_value.array);
-
-                case value_t::object:
-                    return (*lhs.m_value.object) < (*rhs.m_value.object);
-
-                case value_t::null:
-                    return false;
-
-                case value_t::string:
-                    return (*lhs.m_value.string) < (*rhs.m_value.string);
-
-                case value_t::boolean:
-                    return (lhs.m_value.boolean) < (rhs.m_value.boolean);
-
-                case value_t::number_integer:
-                    return (lhs.m_value.number_integer) < (rhs.m_value.number_integer);
-
-                case value_t::number_unsigned:
-                    return (lhs.m_value.number_unsigned) < (rhs.m_value.number_unsigned);
-
-                case value_t::number_float:
-                    return (lhs.m_value.number_float) < (rhs.m_value.number_float);
-
-                case value_t::binary:
-                    return (*lhs.m_value.binary) < (*rhs.m_value.binary);
-
-                default:
-                    return false;
-            }
-        }
-        else if (lhs_type == value_t::number_integer && rhs_type == value_t::number_float)
-        {
-            return static_cast<number_float_t>(lhs.m_value.number_integer) < rhs.m_value.number_float;
-        }
-        else if (lhs_type == value_t::number_float && rhs_type == value_t::number_integer)
-        {
-            return lhs.m_value.number_float < static_cast<number_float_t>(rhs.m_value.number_integer);
-        }
-        else if (lhs_type == value_t::number_unsigned && rhs_type == value_t::number_float)
-        {
-            return static_cast<number_float_t>(lhs.m_value.number_unsigned) < rhs.m_value.number_float;
-        }
-        else if (lhs_type == value_t::number_float && rhs_type == value_t::number_unsigned)
-        {
-            return lhs.m_value.number_float < static_cast<number_float_t>(rhs.m_value.number_unsigned);
-        }
-        else if (lhs_type == value_t::number_integer && rhs_type == value_t::number_unsigned)
-        {
-            return lhs.m_value.number_integer < static_cast<number_integer_t>(rhs.m_value.number_unsigned);
-        }
-        else if (lhs_type == value_t::number_unsigned && rhs_type == value_t::number_integer)
-        {
-            return static_cast<number_integer_t>(lhs.m_value.number_unsigned) < rhs.m_value.number_integer;
-        }
-
-        // We only reach this line if we cannot compare values. In that case,
-        // we compare types. Note we have to call the operator explicitly,
-        // because MSVC has problems otherwise.
-        return operator<(lhs_type, rhs_type);
-    }
-
-    /*!
-    @brief comparison: less than
-    @copydoc operator<(const_reference, const_reference)
-    */
-    template<typename ScalarType, typename std::enable_if<
-                 std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator<(const_reference lhs, const ScalarType rhs) noexcept
-    {
-        return lhs < basic_json(rhs);
-    }
-
-    /*!
-    @brief comparison: less than
-    @copydoc operator<(const_reference, const_reference)
-    */
-    template<typename ScalarType, typename std::enable_if<
-                 std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator<(const ScalarType lhs, const_reference rhs) noexcept
-    {
-        return basic_json(lhs) < rhs;
-    }
-
-    /*!
-    @brief comparison: less than or equal
-
-    Compares whether one JSON value @a lhs is less than or equal to another
-    JSON value by calculating `not (rhs < lhs)`.
-
-    @param[in] lhs  first JSON value to consider
-    @param[in] rhs  second JSON value to consider
-    @return whether @a lhs is less than or equal to @a rhs
-
-    @complexity Linear.
-
-    @exceptionsafety No-throw guarantee: this function never throws exceptions.
-
-    @liveexample{The example demonstrates comparing several JSON
-    types.,operator__greater}
-
-    @since version 1.0.0
-    */
-    friend bool operator<=(const_reference lhs, const_reference rhs) noexcept
-    {
-        return !(rhs < lhs);
-    }
-
-    /*!
-    @brief comparison: less than or equal
-    @copydoc operator<=(const_reference, const_reference)
-    */
-    template<typename ScalarType, typename std::enable_if<
-                 std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator<=(const_reference lhs, const ScalarType rhs) noexcept
-    {
-        return lhs <= basic_json(rhs);
-    }
-
-    /*!
-    @brief comparison: less than or equal
-    @copydoc operator<=(const_reference, const_reference)
-    */
-    template<typename ScalarType, typename std::enable_if<
-                 std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator<=(const ScalarType lhs, const_reference rhs) noexcept
-    {
-        return basic_json(lhs) <= rhs;
-    }
-
-    /*!
-    @brief comparison: greater than
-
-    Compares whether one JSON value @a lhs is greater than another
-    JSON value by calculating `not (lhs <= rhs)`.
-
-    @param[in] lhs  first JSON value to consider
-    @param[in] rhs  second JSON value to consider
-    @return whether @a lhs is greater than to @a rhs
-
-    @complexity Linear.
-
-    @exceptionsafety No-throw guarantee: this function never throws exceptions.
-
-    @liveexample{The example demonstrates comparing several JSON
-    types.,operator__lessequal}
-
-    @since version 1.0.0
-    */
-    friend bool operator>(const_reference lhs, const_reference rhs) noexcept
-    {
-        return !(lhs <= rhs);
-    }
-
-    /*!
-    @brief comparison: greater than
-    @copydoc operator>(const_reference, const_reference)
-    */
-    template<typename ScalarType, typename std::enable_if<
-                 std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator>(const_reference lhs, const ScalarType rhs) noexcept
-    {
-        return lhs > basic_json(rhs);
-    }
-
-    /*!
-    @brief comparison: greater than
-    @copydoc operator>(const_reference, const_reference)
-    */
-    template<typename ScalarType, typename std::enable_if<
-                 std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator>(const ScalarType lhs, const_reference rhs) noexcept
-    {
-        return basic_json(lhs) > rhs;
-    }
-
-    /*!
-    @brief comparison: greater than or equal
-
-    Compares whether one JSON value @a lhs is greater than or equal to another
-    JSON value by calculating `not (lhs < rhs)`.
-
-    @param[in] lhs  first JSON value to consider
-    @param[in] rhs  second JSON value to consider
-    @return whether @a lhs is greater than or equal to @a rhs
-
-    @complexity Linear.
-
-    @exceptionsafety No-throw guarantee: this function never throws exceptions.
-
-    @liveexample{The example demonstrates comparing several JSON
-    types.,operator__greaterequal}
-
-    @since version 1.0.0
-    */
-    friend bool operator>=(const_reference lhs, const_reference rhs) noexcept
-    {
-        return !(lhs < rhs);
-    }
-
-    /*!
-    @brief comparison: greater than or equal
-    @copydoc operator>=(const_reference, const_reference)
-    */
-    template<typename ScalarType, typename std::enable_if<
-                 std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator>=(const_reference lhs, const ScalarType rhs) noexcept
-    {
-        return lhs >= basic_json(rhs);
-    }
-
-    /*!
-    @brief comparison: greater than or equal
-    @copydoc operator>=(const_reference, const_reference)
-    */
-    template<typename ScalarType, typename std::enable_if<
-                 std::is_scalar<ScalarType>::value, int>::type = 0>
-    friend bool operator>=(const ScalarType lhs, const_reference rhs) noexcept
-    {
-        return basic_json(lhs) >= rhs;
-    }
-
-    /// @}
-
-    ///////////////////
-    // serialization //
-    ///////////////////
-
-    /// @name serialization
-    /// @{
-
-    /*!
-    @brief serialize to stream
-
-    Serialize the given JSON value @a j to the output stream @a o. The JSON
-    value will be serialized using the @ref dump member function.
-
-    - The indentation of the output can be controlled with the member variable
-      `width` of the output stream @a o. For instance, using the manipulator
-      `std::setw(4)` on @a o sets the indentation level to `4` and the
-      serialization result is the same as calling `dump(4)`.
-
-    - The indentation character can be controlled with the member variable
-      `fill` of the output stream @a o. For instance, the manipulator
-      `std::setfill('\\t')` sets indentation to use a tab character rather than
-      the default space character.
-
-    @param[in,out] o  stream to serialize to
-    @param[in] j  JSON value to serialize
-
-    @return the stream @a o
-
-    @throw type_error.316 if a string stored inside the JSON value is not
-                          UTF-8 encoded
-
-    @complexity Linear.
-
-    @liveexample{The example below shows the serialization with different
-    parameters to `width` to adjust the indentation level.,operator_serialize}
-
-    @since version 1.0.0; indentation character added in version 3.0.0
-    */
-    friend std::ostream& operator<<(std::ostream& o, const basic_json& j)
-    {
-        // read width member and use it as indentation parameter if nonzero
-        const bool pretty_print = o.width() > 0;
-        const auto indentation = pretty_print ? o.width() : 0;
-
-        // reset width to 0 for subsequent calls to this stream
-        o.width(0);
-
-        // do the actual serialization
-        serializer s(detail::output_adapter<char>(o), o.fill());
-        s.dump(j, pretty_print, false, static_cast<unsigned int>(indentation));
-        return o;
-    }
-
-    /*!
-    @brief serialize to stream
-    @deprecated This stream operator is deprecated and will be removed in
-                future 4.0.0 of the library. Please use
-                @ref operator<<(std::ostream&, const basic_json&)
-                instead; that is, replace calls like `j >> o;` with `o << j;`.
-    @since version 1.0.0; deprecated since version 3.0.0
-    */
-    JSON_HEDLEY_DEPRECATED_FOR(3.0.0, operator<<(std::ostream&, const basic_json&))
-    friend std::ostream& operator>>(const basic_json& j, std::ostream& o)
-    {
-        return o << j;
-    }
-
-    /// @}
-
-
-    /////////////////////
-    // deserialization //
-    /////////////////////
-
-    /// @name deserialization
-    /// @{
-
-    /*!
-    @brief deserialize from a compatible input
-
-    @tparam InputType A compatible input, for instance
-    - an std::istream object
-    - a FILE pointer
-    - a C-style array of characters
-    - a pointer to a null-terminated string of single byte characters
-    - an object obj for which begin(obj) and end(obj) produces a valid pair of
-      iterators.
-
-    @param[in] i  input to read from
-    @param[in] cb  a parser callback function of type @ref parser_callback_t
-    which is used to control the deserialization by filtering unwanted values
-    (optional)
-    @param[in] allow_exceptions  whether to throw exceptions in case of a
-    parse error (optional, true by default)
-    @param[in] ignore_comments  whether comments should be ignored and treated
-    like whitespace (true) or yield a parse error (true); (optional, false by
-    default)
-
-    @return deserialized JSON value; in case of a parse error and
-            @a allow_exceptions set to `false`, the return value will be
-            value_t::discarded.
-
-    @throw parse_error.101 if a parse error occurs; example: `""unexpected end
-    of input; expected string literal""`
-    @throw parse_error.102 if to_unicode fails or surrogate error
-    @throw parse_error.103 if to_unicode fails
-
-    @complexity Linear in the length of the input. The parser is a predictive
-    LL(1) parser. The complexity can be higher if the parser callback function
-    @a cb or reading from the input @a i has a super-linear complexity.
-
-    @note A UTF-8 byte order mark is silently ignored.
-
-    @liveexample{The example below demonstrates the `parse()` function reading
-    from an array.,parse__array__parser_callback_t}
-
-    @liveexample{The example below demonstrates the `parse()` function with
-    and without callback function.,parse__string__parser_callback_t}
-
-    @liveexample{The example below demonstrates the `parse()` function with
-    and without callback function.,parse__istream__parser_callback_t}
-
-    @liveexample{The example below demonstrates the `parse()` function reading
-    from a contiguous container.,parse__contiguouscontainer__parser_callback_t}
-
-    @since version 2.0.3 (contiguous containers); version 3.9.0 allowed to
-    ignore comments.
-    */
-    template<typename InputType>
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json parse(InputType&& i,
-                            const parser_callback_t cb = nullptr,
-                            const bool allow_exceptions = true,
-                            const bool ignore_comments = false)
-    {
-        basic_json result;
-        parser(detail::input_adapter(std::forward<InputType>(i)), cb, allow_exceptions, ignore_comments).parse(true, result);
-        return result;
-    }
-
-    /*!
-    @brief deserialize from a pair of character iterators
-
-    The value_type of the iterator must be a integral type with size of 1, 2 or
-    4 bytes, which will be interpreted respectively as UTF-8, UTF-16 and UTF-32.
-
-    @param[in] first iterator to start of character range
-    @param[in] last  iterator to end of character range
-    @param[in] cb  a parser callback function of type @ref parser_callback_t
-    which is used to control the deserialization by filtering unwanted values
-    (optional)
-    @param[in] allow_exceptions  whether to throw exceptions in case of a
-    parse error (optional, true by default)
-    @param[in] ignore_comments  whether comments should be ignored and treated
-    like whitespace (true) or yield a parse error (true); (optional, false by
-    default)
-
-    @return deserialized JSON value; in case of a parse error and
-            @a allow_exceptions set to `false`, the return value will be
-            value_t::discarded.
-
-    @throw parse_error.101 if a parse error occurs; example: `""unexpected end
-    of input; expected string literal""`
-    @throw parse_error.102 if to_unicode fails or surrogate error
-    @throw parse_error.103 if to_unicode fails
-    */
-    template<typename IteratorType>
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json parse(IteratorType first,
-                            IteratorType last,
-                            const parser_callback_t cb = nullptr,
-                            const bool allow_exceptions = true,
-                            const bool ignore_comments = false)
-    {
-        basic_json result;
-        parser(detail::input_adapter(std::move(first), std::move(last)), cb, allow_exceptions, ignore_comments).parse(true, result);
-        return result;
-    }
-
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, parse(ptr, ptr + len))
-    static basic_json parse(detail::span_input_adapter&& i,
-                            const parser_callback_t cb = nullptr,
-                            const bool allow_exceptions = true,
-                            const bool ignore_comments = false)
-    {
-        basic_json result;
-        parser(i.get(), cb, allow_exceptions, ignore_comments).parse(true, result);
-        return result;
-    }
-
-    /*!
-    @brief check if the input is valid JSON
-
-    Unlike the @ref parse(InputType&&, const parser_callback_t,const bool)
-    function, this function neither throws an exception in case of invalid JSON
-    input (i.e., a parse error) nor creates diagnostic information.
-
-    @tparam InputType A compatible input, for instance
-    - an std::istream object
-    - a FILE pointer
-    - a C-style array of characters
-    - a pointer to a null-terminated string of single byte characters
-    - an object obj for which begin(obj) and end(obj) produces a valid pair of
-      iterators.
-
-    @param[in] i input to read from
-    @param[in] ignore_comments  whether comments should be ignored and treated
-    like whitespace (true) or yield a parse error (true); (optional, false by
-    default)
-
-    @return Whether the input read from @a i is valid JSON.
-
-    @complexity Linear in the length of the input. The parser is a predictive
-    LL(1) parser.
-
-    @note A UTF-8 byte order mark is silently ignored.
-
-    @liveexample{The example below demonstrates the `accept()` function reading
-    from a string.,accept__string}
-    */
-    template<typename InputType>
-    static bool accept(InputType&& i,
-                       const bool ignore_comments = false)
-    {
-        return parser(detail::input_adapter(std::forward<InputType>(i)), nullptr, false, ignore_comments).accept(true);
-    }
-
-    template<typename IteratorType>
-    static bool accept(IteratorType first, IteratorType last,
-                       const bool ignore_comments = false)
-    {
-        return parser(detail::input_adapter(std::move(first), std::move(last)), nullptr, false, ignore_comments).accept(true);
-    }
-
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, accept(ptr, ptr + len))
-    static bool accept(detail::span_input_adapter&& i,
-                       const bool ignore_comments = false)
-    {
-        return parser(i.get(), nullptr, false, ignore_comments).accept(true);
-    }
-
-    /*!
-    @brief generate SAX events
-
-    The SAX event lister must follow the interface of @ref json_sax.
-
-    This function reads from a compatible input. Examples are:
-    - an std::istream object
-    - a FILE pointer
-    - a C-style array of characters
-    - a pointer to a null-terminated string of single byte characters
-    - an object obj for which begin(obj) and end(obj) produces a valid pair of
-      iterators.
-
-    @param[in] i  input to read from
-    @param[in,out] sax  SAX event listener
-    @param[in] format  the format to parse (JSON, CBOR, MessagePack, or UBJSON)
-    @param[in] strict  whether the input has to be consumed completely
-    @param[in] ignore_comments  whether comments should be ignored and treated
-    like whitespace (true) or yield a parse error (true); (optional, false by
-    default); only applies to the JSON file format.
-
-    @return return value of the last processed SAX event
-
-    @throw parse_error.101 if a parse error occurs; example: `""unexpected end
-    of input; expected string literal""`
-    @throw parse_error.102 if to_unicode fails or surrogate error
-    @throw parse_error.103 if to_unicode fails
-
-    @complexity Linear in the length of the input. The parser is a predictive
-    LL(1) parser. The complexity can be higher if the SAX consumer @a sax has
-    a super-linear complexity.
-
-    @note A UTF-8 byte order mark is silently ignored.
-
-    @liveexample{The example below demonstrates the `sax_parse()` function
-    reading from string and processing the events with a user-defined SAX
-    event consumer.,sax_parse}
-
-    @since version 3.2.0
-    */
-    template <typename InputType, typename SAX>
-    JSON_HEDLEY_NON_NULL(2)
-    static bool sax_parse(InputType&& i, SAX* sax,
-                          input_format_t format = input_format_t::json,
-                          const bool strict = true,
-                          const bool ignore_comments = false)
-    {
-        auto ia = detail::input_adapter(std::forward<InputType>(i));
-        return format == input_format_t::json
-               ? parser(std::move(ia), nullptr, true, ignore_comments).sax_parse(sax, strict)
-               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia)).sax_parse(format, sax, strict);
-    }
-
-    template<class IteratorType, class SAX>
-    JSON_HEDLEY_NON_NULL(3)
-    static bool sax_parse(IteratorType first, IteratorType last, SAX* sax,
-                          input_format_t format = input_format_t::json,
-                          const bool strict = true,
-                          const bool ignore_comments = false)
-    {
-        auto ia = detail::input_adapter(std::move(first), std::move(last));
-        return format == input_format_t::json
-               ? parser(std::move(ia), nullptr, true, ignore_comments).sax_parse(sax, strict)
-               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia)).sax_parse(format, sax, strict);
-    }
-
-    template <typename SAX>
-    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, sax_parse(ptr, ptr + len, ...))
-    JSON_HEDLEY_NON_NULL(2)
-    static bool sax_parse(detail::span_input_adapter&& i, SAX* sax,
-                          input_format_t format = input_format_t::json,
-                          const bool strict = true,
-                          const bool ignore_comments = false)
-    {
-        auto ia = i.get();
-        return format == input_format_t::json
-               ? parser(std::move(ia), nullptr, true, ignore_comments).sax_parse(sax, strict)
-               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia)).sax_parse(format, sax, strict);
-    }
-
-    /*!
-    @brief deserialize from stream
-    @deprecated This stream operator is deprecated and will be removed in
-                version 4.0.0 of the library. Please use
-                @ref operator>>(std::istream&, basic_json&)
-                instead; that is, replace calls like `j << i;` with `i >> j;`.
-    @since version 1.0.0; deprecated since version 3.0.0
-    */
-    JSON_HEDLEY_DEPRECATED_FOR(3.0.0, operator>>(std::istream&, basic_json&))
-    friend std::istream& operator<<(basic_json& j, std::istream& i)
-    {
-        return operator>>(i, j);
-    }
-
-    /*!
-    @brief deserialize from stream
-
-    Deserializes an input stream to a JSON value.
-
-    @param[in,out] i  input stream to read a serialized JSON value from
-    @param[in,out] j  JSON value to write the deserialized input to
-
-    @throw parse_error.101 in case of an unexpected token
-    @throw parse_error.102 if to_unicode fails or surrogate error
-    @throw parse_error.103 if to_unicode fails
-
-    @complexity Linear in the length of the input. The parser is a predictive
-    LL(1) parser.
-
-    @note A UTF-8 byte order mark is silently ignored.
-
-    @liveexample{The example below shows how a JSON value is constructed by
-    reading a serialization from a stream.,operator_deserialize}
-
-    @sa parse(std::istream&, const parser_callback_t) for a variant with a
-    parser callback function to filter values while parsing
-
-    @since version 1.0.0
-    */
-    friend std::istream& operator>>(std::istream& i, basic_json& j)
-    {
-        parser(detail::input_adapter(i)).parse(false, j);
-        return i;
-    }
-
-    /// @}
-
-    ///////////////////////////
-    // convenience functions //
-    ///////////////////////////
-
-    /*!
-    @brief return the type as string
-
-    Returns the type name as string to be used in error messages - usually to
-    indicate that a function was called on a wrong JSON type.
-
-    @return a string representation of a the @a m_type member:
-            Value type  | return value
-            ----------- | -------------
-            null        | `"null"`
-            boolean     | `"boolean"`
-            string      | `"string"`
-            number      | `"number"` (for all number types)
-            object      | `"object"`
-            array       | `"array"`
-            binary      | `"binary"`
-            discarded   | `"discarded"`
-
-    @exceptionsafety No-throw guarantee: this function never throws exceptions.
-
-    @complexity Constant.
-
-    @liveexample{The following code exemplifies `type_name()` for all JSON
-    types.,type_name}
-
-    @sa @ref type() -- return the type of the JSON value
-    @sa @ref operator value_t() -- return the type of the JSON value (implicit)
-
-    @since version 1.0.0, public since 2.1.0, `const char*` and `noexcept`
-    since 3.0.0
-    */
-    JSON_HEDLEY_RETURNS_NON_NULL
-    const char* type_name() const noexcept
-    {
-        {
-            switch (m_type)
-            {
-                case value_t::null:
-                    return "null";
-                case value_t::object:
-                    return "object";
-                case value_t::array:
-                    return "array";
-                case value_t::string:
-                    return "string";
-                case value_t::boolean:
-                    return "boolean";
-                case value_t::binary:
-                    return "binary";
-                case value_t::discarded:
-                    return "discarded";
-                default:
-                    return "number";
-            }
-        }
-    }
-
-
-  private:
-    //////////////////////
-    // member variables //
-    //////////////////////
-
-    /// the type of the current element
-    value_t m_type = value_t::null;
-
-    /// the value of the current element
-    json_value m_value = {};
-
-    //////////////////////////////////////////
-    // binary serialization/deserialization //
-    //////////////////////////////////////////
-
-    /// @name binary serialization/deserialization support
-    /// @{
-
-  public:
-    /*!
-    @brief create a CBOR serialization of a given JSON value
-
-    Serializes a given JSON value @a j to a byte vector using the CBOR (Concise
-    Binary Object Representation) serialization format. CBOR is a binary
-    serialization format which aims to be more compact than JSON itself, yet
-    more efficient to parse.
-
-    The library uses the following mapping from JSON values types to
-    CBOR types according to the CBOR specification (RFC 7049):
-
-    JSON value type | value/range                                | CBOR type                          | first byte
-    --------------- | ------------------------------------------ | ---------------------------------- | ---------------
-    null            | `null`                                     | Null                               | 0xF6
-    boolean         | `true`                                     | True                               | 0xF5
-    boolean         | `false`                                    | False                              | 0xF4
-    number_integer  | -9223372036854775808..-2147483649          | Negative integer (8 bytes follow)  | 0x3B
-    number_integer  | -2147483648..-32769                        | Negative integer (4 bytes follow)  | 0x3A
-    number_integer  | -32768..-129                               | Negative integer (2 bytes follow)  | 0x39
-    number_integer  | -128..-25                                  | Negative integer (1 byte follow)   | 0x38
-    number_integer  | -24..-1                                    | Negative integer                   | 0x20..0x37
-    number_integer  | 0..23                                      | Integer                            | 0x00..0x17
-    number_integer  | 24..255                                    | Unsigned integer (1 byte follow)   | 0x18
-    number_integer  | 256..65535                                 | Unsigned integer (2 bytes follow)  | 0x19
-    number_integer  | 65536..4294967295                          | Unsigned integer (4 bytes follow)  | 0x1A
-    number_integer  | 4294967296..18446744073709551615           | Unsigned integer (8 bytes follow)  | 0x1B
-    number_unsigned | 0..23                                      | Integer                            | 0x00..0x17
-    number_unsigned | 24..255                                    | Unsigned integer (1 byte follow)   | 0x18
-    number_unsigned | 256..65535                                 | Unsigned integer (2 bytes follow)  | 0x19
-    number_unsigned | 65536..4294967295                          | Unsigned integer (4 bytes follow)  | 0x1A
-    number_unsigned | 4294967296..18446744073709551615           | Unsigned integer (8 bytes follow)  | 0x1B
-    number_float    | *any value representable by a float*       | Single-Precision Float             | 0xFA
-    number_float    | *any value NOT representable by a float*   | Double-Precision Float             | 0xFB
-    string          | *length*: 0..23                            | UTF-8 string                       | 0x60..0x77
-    string          | *length*: 23..255                          | UTF-8 string (1 byte follow)       | 0x78
-    string          | *length*: 256..65535                       | UTF-8 string (2 bytes follow)      | 0x79
-    string          | *length*: 65536..4294967295                | UTF-8 string (4 bytes follow)      | 0x7A
-    string          | *length*: 4294967296..18446744073709551615 | UTF-8 string (8 bytes follow)      | 0x7B
-    array           | *size*: 0..23                              | array                              | 0x80..0x97
-    array           | *size*: 23..255                            | array (1 byte follow)              | 0x98
-    array           | *size*: 256..65535                         | array (2 bytes follow)             | 0x99
-    array           | *size*: 65536..4294967295                  | array (4 bytes follow)             | 0x9A
-    array           | *size*: 4294967296..18446744073709551615   | array (8 bytes follow)             | 0x9B
-    object          | *size*: 0..23                              | map                                | 0xA0..0xB7
-    object          | *size*: 23..255                            | map (1 byte follow)                | 0xB8
-    object          | *size*: 256..65535                         | map (2 bytes follow)               | 0xB9
-    object          | *size*: 65536..4294967295                  | map (4 bytes follow)               | 0xBA
-    object          | *size*: 4294967296..18446744073709551615   | map (8 bytes follow)               | 0xBB
-    binary          | *size*: 0..23                              | byte string                        | 0x40..0x57
-    binary          | *size*: 23..255                            | byte string (1 byte follow)        | 0x58
-    binary          | *size*: 256..65535                         | byte string (2 bytes follow)       | 0x59
-    binary          | *size*: 65536..4294967295                  | byte string (4 bytes follow)       | 0x5A
-    binary          | *size*: 4294967296..18446744073709551615   | byte string (8 bytes follow)       | 0x5B
-
-    @note The mapping is **complete** in the sense that any JSON value type
-          can be converted to a CBOR value.
-
-    @note If NaN or Infinity are stored inside a JSON number, they are
-          serialized properly. This behavior differs from the @ref dump()
-          function which serializes NaN or Infinity to `null`.
-
-    @note The following CBOR types are not used in the conversion:
-          - UTF-8 strings terminated by "break" (0x7F)
-          - arrays terminated by "break" (0x9F)
-          - maps terminated by "break" (0xBF)
-          - byte strings terminated by "break" (0x5F)
-          - date/time (0xC0..0xC1)
-          - bignum (0xC2..0xC3)
-          - decimal fraction (0xC4)
-          - bigfloat (0xC5)
-          - expected conversions (0xD5..0xD7)
-          - simple values (0xE0..0xF3, 0xF8)
-          - undefined (0xF7)
-          - half-precision floats (0xF9)
-          - break (0xFF)
-
-    @param[in] j  JSON value to serialize
-    @return CBOR serialization as byte vector
-
-    @complexity Linear in the size of the JSON value @a j.
-
-    @liveexample{The example shows the serialization of a JSON value to a byte
-    vector in CBOR format.,to_cbor}
-
-    @sa http://cbor.io
-    @sa @ref from_cbor(detail::input_adapter&&, const bool, const bool, const cbor_tag_handler_t) for the
-        analogous deserialization
-    @sa @ref to_msgpack(const basic_json&) for the related MessagePack format
-    @sa @ref to_ubjson(const basic_json&, const bool, const bool) for the
-             related UBJSON format
-
-    @since version 2.0.9; compact representation of floating-point numbers
-           since version 3.8.0
-    */
-    static std::vector<uint8_t> to_cbor(const basic_json& j)
-    {
-        std::vector<uint8_t> result;
-        to_cbor(j, result);
-        return result;
-    }
-
-    static void to_cbor(const basic_json& j, detail::output_adapter<uint8_t> o)
-    {
-        binary_writer<uint8_t>(o).write_cbor(j);
-    }
-
-    static void to_cbor(const basic_json& j, detail::output_adapter<char> o)
-    {
-        binary_writer<char>(o).write_cbor(j);
-    }
-
-    /*!
-    @brief create a MessagePack serialization of a given JSON value
-
-    Serializes a given JSON value @a j to a byte vector using the MessagePack
-    serialization format. MessagePack is a binary serialization format which
-    aims to be more compact than JSON itself, yet more efficient to parse.
-
-    The library uses the following mapping from JSON values types to
-    MessagePack types according to the MessagePack specification:
-
-    JSON value type | value/range                       | MessagePack type | first byte
-    --------------- | --------------------------------- | ---------------- | ----------
-    null            | `null`                            | nil              | 0xC0
-    boolean         | `true`                            | true             | 0xC3
-    boolean         | `false`                           | false            | 0xC2
-    number_integer  | -9223372036854775808..-2147483649 | int64            | 0xD3
-    number_integer  | -2147483648..-32769               | int32            | 0xD2
-    number_integer  | -32768..-129                      | int16            | 0xD1
-    number_integer  | -128..-33                         | int8             | 0xD0
-    number_integer  | -32..-1                           | negative fixint  | 0xE0..0xFF
-    number_integer  | 0..127                            | positive fixint  | 0x00..0x7F
-    number_integer  | 128..255                          | uint 8           | 0xCC
-    number_integer  | 256..65535                        | uint 16          | 0xCD
-    number_integer  | 65536..4294967295                 | uint 32          | 0xCE
-    number_integer  | 4294967296..18446744073709551615  | uint 64          | 0xCF
-    number_unsigned | 0..127                            | positive fixint  | 0x00..0x7F
-    number_unsigned | 128..255                          | uint 8           | 0xCC
-    number_unsigned | 256..65535                        | uint 16          | 0xCD
-    number_unsigned | 65536..4294967295                 | uint 32          | 0xCE
-    number_unsigned | 4294967296..18446744073709551615  | uint 64          | 0xCF
-    number_float    | *any value representable by a float*     | float 32 | 0xCA
-    number_float    | *any value NOT representable by a float* | float 64 | 0xCB
-    string          | *length*: 0..31                   | fixstr           | 0xA0..0xBF
-    string          | *length*: 32..255                 | str 8            | 0xD9
-    string          | *length*: 256..65535              | str 16           | 0xDA
-    string          | *length*: 65536..4294967295       | str 32           | 0xDB
-    array           | *size*: 0..15                     | fixarray         | 0x90..0x9F
-    array           | *size*: 16..65535                 | array 16         | 0xDC
-    array           | *size*: 65536..4294967295         | array 32         | 0xDD
-    object          | *size*: 0..15                     | fix map          | 0x80..0x8F
-    object          | *size*: 16..65535                 | map 16           | 0xDE
-    object          | *size*: 65536..4294967295         | map 32           | 0xDF
-    binary          | *size*: 0..255                    | bin 8            | 0xC4
-    binary          | *size*: 256..65535                | bin 16           | 0xC5
-    binary          | *size*: 65536..4294967295         | bin 32           | 0xC6
-
-    @note The mapping is **complete** in the sense that any JSON value type
-          can be converted to a MessagePack value.
-
-    @note The following values can **not** be converted to a MessagePack value:
-          - strings with more than 4294967295 bytes
-          - byte strings with more than 4294967295 bytes
-          - arrays with more than 4294967295 elements
-          - objects with more than 4294967295 elements
-
-    @note Any MessagePack output created @ref to_msgpack can be successfully
-          parsed by @ref from_msgpack.
-
-    @note If NaN or Infinity are stored inside a JSON number, they are
-          serialized properly. This behavior differs from the @ref dump()
-          function which serializes NaN or Infinity to `null`.
-
-    @param[in] j  JSON value to serialize
-    @return MessagePack serialization as byte vector
-
-    @complexity Linear in the size of the JSON value @a j.
-
-    @liveexample{The example shows the serialization of a JSON value to a byte
-    vector in MessagePack format.,to_msgpack}
-
-    @sa http://msgpack.org
-    @sa @ref from_msgpack for the analogous deserialization
-    @sa @ref to_cbor(const basic_json& for the related CBOR format
-    @sa @ref to_ubjson(const basic_json&, const bool, const bool) for the
-             related UBJSON format
-
-    @since version 2.0.9
-    */
-    static std::vector<uint8_t> to_msgpack(const basic_json& j)
-    {
-        std::vector<uint8_t> result;
-        to_msgpack(j, result);
-        return result;
-    }
-
-    static void to_msgpack(const basic_json& j, detail::output_adapter<uint8_t> o)
-    {
-        binary_writer<uint8_t>(o).write_msgpack(j);
-    }
-
-    static void to_msgpack(const basic_json& j, detail::output_adapter<char> o)
-    {
-        binary_writer<char>(o).write_msgpack(j);
-    }
-
-    /*!
-    @brief create a UBJSON serialization of a given JSON value
-
-    Serializes a given JSON value @a j to a byte vector using the UBJSON
-    (Universal Binary JSON) serialization format. UBJSON aims to be more compact
-    than JSON itself, yet more efficient to parse.
-
-    The library uses the following mapping from JSON values types to
-    UBJSON types according to the UBJSON specification:
-
-    JSON value type | value/range                       | UBJSON type | marker
-    --------------- | --------------------------------- | ----------- | ------
-    null            | `null`                            | null        | `Z`
-    boolean         | `true`                            | true        | `T`
-    boolean         | `false`                           | false       | `F`
-    number_integer  | -9223372036854775808..-2147483649 | int64       | `L`
-    number_integer  | -2147483648..-32769               | int32       | `l`
-    number_integer  | -32768..-129                      | int16       | `I`
-    number_integer  | -128..127                         | int8        | `i`
-    number_integer  | 128..255                          | uint8       | `U`
-    number_integer  | 256..32767                        | int16       | `I`
-    number_integer  | 32768..2147483647                 | int32       | `l`
-    number_integer  | 2147483648..9223372036854775807   | int64       | `L`
-    number_unsigned | 0..127                            | int8        | `i`
-    number_unsigned | 128..255                          | uint8       | `U`
-    number_unsigned | 256..32767                        | int16       | `I`
-    number_unsigned | 32768..2147483647                 | int32       | `l`
-    number_unsigned | 2147483648..9223372036854775807   | int64       | `L`
-    number_unsigned | 2147483649..18446744073709551615  | high-precision | `H`
-    number_float    | *any value*                       | float64     | `D`
-    string          | *with shortest length indicator*  | string      | `S`
-    array           | *see notes on optimized format*   | array       | `[`
-    object          | *see notes on optimized format*   | map         | `{`
-
-    @note The mapping is **complete** in the sense that any JSON value type
-          can be converted to a UBJSON value.
-
-    @note The following values can **not** be converted to a UBJSON value:
-          - strings with more than 9223372036854775807 bytes (theoretical)
-
-    @note The following markers are not used in the conversion:
-          - `Z`: no-op values are not created.
-          - `C`: single-byte strings are serialized with `S` markers.
-
-    @note Any UBJSON output created @ref to_ubjson can be successfully parsed
-          by @ref from_ubjson.
-
-    @note If NaN or Infinity are stored inside a JSON number, they are
-          serialized properly. This behavior differs from the @ref dump()
-          function which serializes NaN or Infinity to `null`.
-
-    @note The optimized formats for containers are supported: Parameter
-          @a use_size adds size information to the beginning of a container and
-          removes the closing marker. Parameter @a use_type further checks
-          whether all elements of a container have the same type and adds the
-          type marker to the beginning of the container. The @a use_type
-          parameter must only be used together with @a use_size = true. Note
-          that @a use_size = true alone may result in larger representations -
-          the benefit of this parameter is that the receiving side is
-          immediately informed on the number of elements of the container.
-
-    @note If the JSON data contains the binary type, the value stored is a list
-          of integers, as suggested by the UBJSON documentation.  In particular,
-          this means that serialization and the deserialization of a JSON
-          containing binary values into UBJSON and back will result in a
-          different JSON object.
-
-    @param[in] j  JSON value to serialize
-    @param[in] use_size  whether to add size annotations to container types
-    @param[in] use_type  whether to add type annotations to container types
-                         (must be combined with @a use_size = true)
-    @return UBJSON serialization as byte vector
-
-    @complexity Linear in the size of the JSON value @a j.
-
-    @liveexample{The example shows the serialization of a JSON value to a byte
-    vector in UBJSON format.,to_ubjson}
-
-    @sa http://ubjson.org
-    @sa @ref from_ubjson(detail::input_adapter&&, const bool, const bool) for the
-        analogous deserialization
-    @sa @ref to_cbor(const basic_json& for the related CBOR format
-    @sa @ref to_msgpack(const basic_json&) for the related MessagePack format
-
-    @since version 3.1.0
-    */
-    static std::vector<uint8_t> to_ubjson(const basic_json& j,
-                                          const bool use_size = false,
-                                          const bool use_type = false)
-    {
-        std::vector<uint8_t> result;
-        to_ubjson(j, result, use_size, use_type);
-        return result;
-    }
-
-    static void to_ubjson(const basic_json& j, detail::output_adapter<uint8_t> o,
-                          const bool use_size = false, const bool use_type = false)
-    {
-        binary_writer<uint8_t>(o).write_ubjson(j, use_size, use_type);
-    }
-
-    static void to_ubjson(const basic_json& j, detail::output_adapter<char> o,
-                          const bool use_size = false, const bool use_type = false)
-    {
-        binary_writer<char>(o).write_ubjson(j, use_size, use_type);
-    }
-
-
-    /*!
-    @brief Serializes the given JSON object `j` to BSON and returns a vector
-           containing the corresponding BSON-representation.
-
-    BSON (Binary JSON) is a binary format in which zero or more ordered key/value pairs are
-    stored as a single entity (a so-called document).
-
-    The library uses the following mapping from JSON values types to BSON types:
-
-    JSON value type | value/range                       | BSON type   | marker
-    --------------- | --------------------------------- | ----------- | ------
-    null            | `null`                            | null        | 0x0A
-    boolean         | `true`, `false`                   | boolean     | 0x08
-    number_integer  | -9223372036854775808..-2147483649 | int64       | 0x12
-    number_integer  | -2147483648..2147483647           | int32       | 0x10
-    number_integer  | 2147483648..9223372036854775807   | int64       | 0x12
-    number_unsigned | 0..2147483647                     | int32       | 0x10
-    number_unsigned | 2147483648..9223372036854775807   | int64       | 0x12
-    number_unsigned | 9223372036854775808..18446744073709551615| --   | --
-    number_float    | *any value*                       | double      | 0x01
-    string          | *any value*                       | string      | 0x02
-    array           | *any value*                       | document    | 0x04
-    object          | *any value*                       | document    | 0x03
-    binary          | *any value*                       | binary      | 0x05
-
-    @warning The mapping is **incomplete**, since only JSON-objects (and things
-    contained therein) can be serialized to BSON.
-    Also, integers larger than 9223372036854775807 cannot be serialized to BSON,
-    and the keys may not contain U+0000, since they are serialized a
-    zero-terminated c-strings.
-
-    @throw out_of_range.407  if `j.is_number_unsigned() && j.get<std::uint64_t>() > 9223372036854775807`
-    @throw out_of_range.409  if a key in `j` contains a NULL (U+0000)
-    @throw type_error.317    if `!j.is_object()`
-
-    @pre The input `j` is required to be an object: `j.is_object() == true`.
-
-    @note Any BSON output created via @ref to_bson can be successfully parsed
-          by @ref from_bson.
-
-    @param[in] j  JSON value to serialize
-    @return BSON serialization as byte vector
-
-    @complexity Linear in the size of the JSON value @a j.
-
-    @liveexample{The example shows the serialization of a JSON value to a byte
-    vector in BSON format.,to_bson}
-
-    @sa http://bsonspec.org/spec.html
-    @sa @ref from_bson(detail::input_adapter&&, const bool strict) for the
-        analogous deserialization
-    @sa @ref to_ubjson(const basic_json&, const bool, const bool) for the
-             related UBJSON format
-    @sa @ref to_cbor(const basic_json&) for the related CBOR format
-    @sa @ref to_msgpack(const basic_json&) for the related MessagePack format
-    */
-    static std::vector<uint8_t> to_bson(const basic_json& j)
-    {
-        std::vector<uint8_t> result;
-        to_bson(j, result);
-        return result;
-    }
-
-    /*!
-    @brief Serializes the given JSON object `j` to BSON and forwards the
-           corresponding BSON-representation to the given output_adapter `o`.
-    @param j The JSON object to convert to BSON.
-    @param o The output adapter that receives the binary BSON representation.
-    @pre The input `j` shall be an object: `j.is_object() == true`
-    @sa @ref to_bson(const basic_json&)
-    */
-    static void to_bson(const basic_json& j, detail::output_adapter<uint8_t> o)
-    {
-        binary_writer<uint8_t>(o).write_bson(j);
-    }
-
-    /*!
-    @copydoc to_bson(const basic_json&, detail::output_adapter<uint8_t>)
-    */
-    static void to_bson(const basic_json& j, detail::output_adapter<char> o)
-    {
-        binary_writer<char>(o).write_bson(j);
-    }
-
-
-    /*!
-    @brief create a JSON value from an input in CBOR format
-
-    Deserializes a given input @a i to a JSON value using the CBOR (Concise
-    Binary Object Representation) serialization format.
-
-    The library maps CBOR types to JSON value types as follows:
-
-    CBOR type              | JSON value type | first byte
-    ---------------------- | --------------- | ----------
-    Integer                | number_unsigned | 0x00..0x17
-    Unsigned integer       | number_unsigned | 0x18
-    Unsigned integer       | number_unsigned | 0x19
-    Unsigned integer       | number_unsigned | 0x1A
-    Unsigned integer       | number_unsigned | 0x1B
-    Negative integer       | number_integer  | 0x20..0x37
-    Negative integer       | number_integer  | 0x38
-    Negative integer       | number_integer  | 0x39
-    Negative integer       | number_integer  | 0x3A
-    Negative integer       | number_integer  | 0x3B
-    Byte string            | binary          | 0x40..0x57
-    Byte string            | binary          | 0x58
-    Byte string            | binary          | 0x59
-    Byte string            | binary          | 0x5A
-    Byte string            | binary          | 0x5B
-    UTF-8 string           | string          | 0x60..0x77
-    UTF-8 string           | string          | 0x78
-    UTF-8 string           | string          | 0x79
-    UTF-8 string           | string          | 0x7A
-    UTF-8 string           | string          | 0x7B
-    UTF-8 string           | string          | 0x7F
-    array                  | array           | 0x80..0x97
-    array                  | array           | 0x98
-    array                  | array           | 0x99
-    array                  | array           | 0x9A
-    array                  | array           | 0x9B
-    array                  | array           | 0x9F
-    map                    | object          | 0xA0..0xB7
-    map                    | object          | 0xB8
-    map                    | object          | 0xB9
-    map                    | object          | 0xBA
-    map                    | object          | 0xBB
-    map                    | object          | 0xBF
-    False                  | `false`         | 0xF4
-    True                   | `true`          | 0xF5
-    Null                   | `null`          | 0xF6
-    Half-Precision Float   | number_float    | 0xF9
-    Single-Precision Float | number_float    | 0xFA
-    Double-Precision Float | number_float    | 0xFB
-
-    @warning The mapping is **incomplete** in the sense that not all CBOR
-             types can be converted to a JSON value. The following CBOR types
-             are not supported and will yield parse errors (parse_error.112):
-             - date/time (0xC0..0xC1)
-             - bignum (0xC2..0xC3)
-             - decimal fraction (0xC4)
-             - bigfloat (0xC5)
-             - expected conversions (0xD5..0xD7)
-             - simple values (0xE0..0xF3, 0xF8)
-             - undefined (0xF7)
-
-    @warning CBOR allows map keys of any type, whereas JSON only allows
-             strings as keys in object values. Therefore, CBOR maps with keys
-             other than UTF-8 strings are rejected (parse_error.113).
-
-    @note Any CBOR output created @ref to_cbor can be successfully parsed by
-          @ref from_cbor.
-
-    @param[in] i  an input in CBOR format convertible to an input adapter
-    @param[in] strict  whether to expect the input to be consumed until EOF
-                       (true by default)
-    @param[in] allow_exceptions  whether to throw exceptions in case of a
-    parse error (optional, true by default)
-    @param[in] tag_handler how to treat CBOR tags (optional, error by default)
-
-    @return deserialized JSON value; in case of a parse error and
-            @a allow_exceptions set to `false`, the return value will be
-            value_t::discarded.
-
-    @throw parse_error.110 if the given input ends prematurely or the end of
-    file was not reached when @a strict was set to true
-    @throw parse_error.112 if unsupported features from CBOR were
-    used in the given input @a v or if the input is not valid CBOR
-    @throw parse_error.113 if a string was expected as map key, but not found
-
-    @complexity Linear in the size of the input @a i.
-
-    @liveexample{The example shows the deserialization of a byte vector in CBOR
-    format to a JSON value.,from_cbor}
-
-    @sa http://cbor.io
-    @sa @ref to_cbor(const basic_json&) for the analogous serialization
-    @sa @ref from_msgpack(detail::input_adapter&&, const bool, const bool) for the
-        related MessagePack format
-    @sa @ref from_ubjson(detail::input_adapter&&, const bool, const bool) for the
-        related UBJSON format
-
-    @since version 2.0.9; parameter @a start_index since 2.1.1; changed to
-           consume input adapters, removed start_index parameter, and added
-           @a strict parameter since 3.0.0; added @a allow_exceptions parameter
-           since 3.2.0; added @a tag_handler parameter since 3.9.0.
-    */
-    template<typename InputType>
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json from_cbor(InputType&& i,
-                                const bool strict = true,
-                                const bool allow_exceptions = true,
-                                const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error)
-    {
-        basic_json result;
-        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        auto ia = detail::input_adapter(std::forward<InputType>(i));
-        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::cbor, &sdp, strict, tag_handler);
-        return res ? result : basic_json(value_t::discarded);
-    }
-
-    /*!
-    @copydoc from_cbor(detail::input_adapter&&, const bool, const bool, const cbor_tag_handler_t)
-    */
-    template<typename IteratorType>
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json from_cbor(IteratorType first, IteratorType last,
-                                const bool strict = true,
-                                const bool allow_exceptions = true,
-                                const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error)
-    {
-        basic_json result;
-        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        auto ia = detail::input_adapter(std::move(first), std::move(last));
-        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::cbor, &sdp, strict, tag_handler);
-        return res ? result : basic_json(value_t::discarded);
-    }
-
-    template<typename T>
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_cbor(ptr, ptr + len))
-    static basic_json from_cbor(const T* ptr, std::size_t len,
-                                const bool strict = true,
-                                const bool allow_exceptions = true,
-                                const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error)
-    {
-        return from_cbor(ptr, ptr + len, strict, allow_exceptions, tag_handler);
-    }
-
-
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_cbor(ptr, ptr + len))
-    static basic_json from_cbor(detail::span_input_adapter&& i,
-                                const bool strict = true,
-                                const bool allow_exceptions = true,
-                                const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error)
-    {
-        basic_json result;
-        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        auto ia = i.get();
-        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::cbor, &sdp, strict, tag_handler);
-        return res ? result : basic_json(value_t::discarded);
-    }
-
-    /*!
-    @brief create a JSON value from an input in MessagePack format
-
-    Deserializes a given input @a i to a JSON value using the MessagePack
-    serialization format.
-
-    The library maps MessagePack types to JSON value types as follows:
-
-    MessagePack type | JSON value type | first byte
-    ---------------- | --------------- | ----------
-    positive fixint  | number_unsigned | 0x00..0x7F
-    fixmap           | object          | 0x80..0x8F
-    fixarray         | array           | 0x90..0x9F
-    fixstr           | string          | 0xA0..0xBF
-    nil              | `null`          | 0xC0
-    false            | `false`         | 0xC2
-    true             | `true`          | 0xC3
-    float 32         | number_float    | 0xCA
-    float 64         | number_float    | 0xCB
-    uint 8           | number_unsigned | 0xCC
-    uint 16          | number_unsigned | 0xCD
-    uint 32          | number_unsigned | 0xCE
-    uint 64          | number_unsigned | 0xCF
-    int 8            | number_integer  | 0xD0
-    int 16           | number_integer  | 0xD1
-    int 32           | number_integer  | 0xD2
-    int 64           | number_integer  | 0xD3
-    str 8            | string          | 0xD9
-    str 16           | string          | 0xDA
-    str 32           | string          | 0xDB
-    array 16         | array           | 0xDC
-    array 32         | array           | 0xDD
-    map 16           | object          | 0xDE
-    map 32           | object          | 0xDF
-    bin 8            | binary          | 0xC4
-    bin 16           | binary          | 0xC5
-    bin 32           | binary          | 0xC6
-    ext 8            | binary          | 0xC7
-    ext 16           | binary          | 0xC8
-    ext 32           | binary          | 0xC9
-    fixext 1         | binary          | 0xD4
-    fixext 2         | binary          | 0xD5
-    fixext 4         | binary          | 0xD6
-    fixext 8         | binary          | 0xD7
-    fixext 16        | binary          | 0xD8
-    negative fixint  | number_integer  | 0xE0-0xFF
-
-    @note Any MessagePack output created @ref to_msgpack can be successfully
-          parsed by @ref from_msgpack.
-
-    @param[in] i  an input in MessagePack format convertible to an input
-                  adapter
-    @param[in] strict  whether to expect the input to be consumed until EOF
-                       (true by default)
-    @param[in] allow_exceptions  whether to throw exceptions in case of a
-    parse error (optional, true by default)
-
-    @return deserialized JSON value; in case of a parse error and
-            @a allow_exceptions set to `false`, the return value will be
-            value_t::discarded.
-
-    @throw parse_error.110 if the given input ends prematurely or the end of
-    file was not reached when @a strict was set to true
-    @throw parse_error.112 if unsupported features from MessagePack were
-    used in the given input @a i or if the input is not valid MessagePack
-    @throw parse_error.113 if a string was expected as map key, but not found
-
-    @complexity Linear in the size of the input @a i.
-
-    @liveexample{The example shows the deserialization of a byte vector in
-    MessagePack format to a JSON value.,from_msgpack}
-
-    @sa http://msgpack.org
-    @sa @ref to_msgpack(const basic_json&) for the analogous serialization
-    @sa @ref from_cbor(detail::input_adapter&&, const bool, const bool, const cbor_tag_handler_t) for the
-        related CBOR format
-    @sa @ref from_ubjson(detail::input_adapter&&, const bool, const bool) for
-        the related UBJSON format
-    @sa @ref from_bson(detail::input_adapter&&, const bool, const bool) for
-        the related BSON format
-
-    @since version 2.0.9; parameter @a start_index since 2.1.1; changed to
-           consume input adapters, removed start_index parameter, and added
-           @a strict parameter since 3.0.0; added @a allow_exceptions parameter
-           since 3.2.0
-    */
-    template<typename InputType>
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json from_msgpack(InputType&& i,
-                                   const bool strict = true,
-                                   const bool allow_exceptions = true)
-    {
-        basic_json result;
-        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        auto ia = detail::input_adapter(std::forward<InputType>(i));
-        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::msgpack, &sdp, strict);
-        return res ? result : basic_json(value_t::discarded);
-    }
-
-    /*!
-    @copydoc from_msgpack(detail::input_adapter&&, const bool, const bool)
-    */
-    template<typename IteratorType>
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json from_msgpack(IteratorType first, IteratorType last,
-                                   const bool strict = true,
-                                   const bool allow_exceptions = true)
-    {
-        basic_json result;
-        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        auto ia = detail::input_adapter(std::move(first), std::move(last));
-        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::msgpack, &sdp, strict);
-        return res ? result : basic_json(value_t::discarded);
-    }
-
-
-    template<typename T>
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_msgpack(ptr, ptr + len))
-    static basic_json from_msgpack(const T* ptr, std::size_t len,
-                                   const bool strict = true,
-                                   const bool allow_exceptions = true)
-    {
-        return from_msgpack(ptr, ptr + len, strict, allow_exceptions);
-    }
-
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_msgpack(ptr, ptr + len))
-    static basic_json from_msgpack(detail::span_input_adapter&& i,
-                                   const bool strict = true,
-                                   const bool allow_exceptions = true)
-    {
-        basic_json result;
-        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        auto ia = i.get();
-        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::msgpack, &sdp, strict);
-        return res ? result : basic_json(value_t::discarded);
-    }
-
-
-    /*!
-    @brief create a JSON value from an input in UBJSON format
-
-    Deserializes a given input @a i to a JSON value using the UBJSON (Universal
-    Binary JSON) serialization format.
-
-    The library maps UBJSON types to JSON value types as follows:
-
-    UBJSON type | JSON value type                         | marker
-    ----------- | --------------------------------------- | ------
-    no-op       | *no value, next value is read*          | `N`
-    null        | `null`                                  | `Z`
-    false       | `false`                                 | `F`
-    true        | `true`                                  | `T`
-    float32     | number_float                            | `d`
-    float64     | number_float                            | `D`
-    uint8       | number_unsigned                         | `U`
-    int8        | number_integer                          | `i`
-    int16       | number_integer                          | `I`
-    int32       | number_integer                          | `l`
-    int64       | number_integer                          | `L`
-    high-precision number | number_integer, number_unsigned, or number_float - depends on number string | 'H'
-    string      | string                                  | `S`
-    char        | string                                  | `C`
-    array       | array (optimized values are supported)  | `[`
-    object      | object (optimized values are supported) | `{`
-
-    @note The mapping is **complete** in the sense that any UBJSON value can
-          be converted to a JSON value.
-
-    @param[in] i  an input in UBJSON format convertible to an input adapter
-    @param[in] strict  whether to expect the input to be consumed until EOF
-                       (true by default)
-    @param[in] allow_exceptions  whether to throw exceptions in case of a
-    parse error (optional, true by default)
-
-    @return deserialized JSON value; in case of a parse error and
-            @a allow_exceptions set to `false`, the return value will be
-            value_t::discarded.
-
-    @throw parse_error.110 if the given input ends prematurely or the end of
-    file was not reached when @a strict was set to true
-    @throw parse_error.112 if a parse error occurs
-    @throw parse_error.113 if a string could not be parsed successfully
-
-    @complexity Linear in the size of the input @a i.
-
-    @liveexample{The example shows the deserialization of a byte vector in
-    UBJSON format to a JSON value.,from_ubjson}
-
-    @sa http://ubjson.org
-    @sa @ref to_ubjson(const basic_json&, const bool, const bool) for the
-             analogous serialization
-    @sa @ref from_cbor(detail::input_adapter&&, const bool, const bool, const cbor_tag_handler_t) for the
-        related CBOR format
-    @sa @ref from_msgpack(detail::input_adapter&&, const bool, const bool) for
-        the related MessagePack format
-    @sa @ref from_bson(detail::input_adapter&&, const bool, const bool) for
-        the related BSON format
-
-    @since version 3.1.0; added @a allow_exceptions parameter since 3.2.0
-    */
-    template<typename InputType>
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json from_ubjson(InputType&& i,
-                                  const bool strict = true,
-                                  const bool allow_exceptions = true)
-    {
-        basic_json result;
-        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        auto ia = detail::input_adapter(std::forward<InputType>(i));
-        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::ubjson, &sdp, strict);
-        return res ? result : basic_json(value_t::discarded);
-    }
-
-    /*!
-    @copydoc from_ubjson(detail::input_adapter&&, const bool, const bool)
-    */
-    template<typename IteratorType>
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json from_ubjson(IteratorType first, IteratorType last,
-                                  const bool strict = true,
-                                  const bool allow_exceptions = true)
-    {
-        basic_json result;
-        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        auto ia = detail::input_adapter(std::move(first), std::move(last));
-        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::ubjson, &sdp, strict);
-        return res ? result : basic_json(value_t::discarded);
-    }
-
-    template<typename T>
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_ubjson(ptr, ptr + len))
-    static basic_json from_ubjson(const T* ptr, std::size_t len,
-                                  const bool strict = true,
-                                  const bool allow_exceptions = true)
-    {
-        return from_ubjson(ptr, ptr + len, strict, allow_exceptions);
-    }
-
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_ubjson(ptr, ptr + len))
-    static basic_json from_ubjson(detail::span_input_adapter&& i,
-                                  const bool strict = true,
-                                  const bool allow_exceptions = true)
-    {
-        basic_json result;
-        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        auto ia = i.get();
-        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::ubjson, &sdp, strict);
-        return res ? result : basic_json(value_t::discarded);
-    }
-
-
-    /*!
-    @brief Create a JSON value from an input in BSON format
-
-    Deserializes a given input @a i to a JSON value using the BSON (Binary JSON)
-    serialization format.
-
-    The library maps BSON record types to JSON value types as follows:
-
-    BSON type       | BSON marker byte | JSON value type
-    --------------- | ---------------- | ---------------------------
-    double          | 0x01             | number_float
-    string          | 0x02             | string
-    document        | 0x03             | object
-    array           | 0x04             | array
-    binary          | 0x05             | still unsupported
-    undefined       | 0x06             | still unsupported
-    ObjectId        | 0x07             | still unsupported
-    boolean         | 0x08             | boolean
-    UTC Date-Time   | 0x09             | still unsupported
-    null            | 0x0A             | null
-    Regular Expr.   | 0x0B             | still unsupported
-    DB Pointer      | 0x0C             | still unsupported
-    JavaScript Code | 0x0D             | still unsupported
-    Symbol          | 0x0E             | still unsupported
-    JavaScript Code | 0x0F             | still unsupported
-    int32           | 0x10             | number_integer
-    Timestamp       | 0x11             | still unsupported
-    128-bit decimal float | 0x13       | still unsupported
-    Max Key         | 0x7F             | still unsupported
-    Min Key         | 0xFF             | still unsupported
-
-    @warning The mapping is **incomplete**. The unsupported mappings
-             are indicated in the table above.
-
-    @param[in] i  an input in BSON format convertible to an input adapter
-    @param[in] strict  whether to expect the input to be consumed until EOF
-                       (true by default)
-    @param[in] allow_exceptions  whether to throw exceptions in case of a
-    parse error (optional, true by default)
-
-    @return deserialized JSON value; in case of a parse error and
-            @a allow_exceptions set to `false`, the return value will be
-            value_t::discarded.
-
-    @throw parse_error.114 if an unsupported BSON record type is encountered
-
-    @complexity Linear in the size of the input @a i.
-
-    @liveexample{The example shows the deserialization of a byte vector in
-    BSON format to a JSON value.,from_bson}
-
-    @sa http://bsonspec.org/spec.html
-    @sa @ref to_bson(const basic_json&) for the analogous serialization
-    @sa @ref from_cbor(detail::input_adapter&&, const bool, const bool, const cbor_tag_handler_t) for the
-        related CBOR format
-    @sa @ref from_msgpack(detail::input_adapter&&, const bool, const bool) for
-        the related MessagePack format
-    @sa @ref from_ubjson(detail::input_adapter&&, const bool, const bool) for the
-        related UBJSON format
-    */
-    template<typename InputType>
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json from_bson(InputType&& i,
-                                const bool strict = true,
-                                const bool allow_exceptions = true)
-    {
-        basic_json result;
-        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        auto ia = detail::input_adapter(std::forward<InputType>(i));
-        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::bson, &sdp, strict);
-        return res ? result : basic_json(value_t::discarded);
-    }
-
-    /*!
-    @copydoc from_bson(detail::input_adapter&&, const bool, const bool)
-    */
-    template<typename IteratorType>
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json from_bson(IteratorType first, IteratorType last,
-                                const bool strict = true,
-                                const bool allow_exceptions = true)
-    {
-        basic_json result;
-        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        auto ia = detail::input_adapter(std::move(first), std::move(last));
-        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::bson, &sdp, strict);
-        return res ? result : basic_json(value_t::discarded);
-    }
-
-    template<typename T>
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_bson(ptr, ptr + len))
-    static basic_json from_bson(const T* ptr, std::size_t len,
-                                const bool strict = true,
-                                const bool allow_exceptions = true)
-    {
-        return from_bson(ptr, ptr + len, strict, allow_exceptions);
-    }
-
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_bson(ptr, ptr + len))
-    static basic_json from_bson(detail::span_input_adapter&& i,
-                                const bool strict = true,
-                                const bool allow_exceptions = true)
-    {
-        basic_json result;
-        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        auto ia = i.get();
-        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::bson, &sdp, strict);
-        return res ? result : basic_json(value_t::discarded);
-    }
-    /// @}
-
-    //////////////////////////
-    // JSON Pointer support //
-    //////////////////////////
-
-    /// @name JSON Pointer functions
-    /// @{
-
-    /*!
-    @brief access specified element via JSON Pointer
-
-    Uses a JSON pointer to retrieve a reference to the respective JSON value.
-    No bound checking is performed. Similar to @ref operator[](const typename
-    object_t::key_type&), `null` values are created in arrays and objects if
-    necessary.
-
-    In particular:
-    - If the JSON pointer points to an object key that does not exist, it
-      is created an filled with a `null` value before a reference to it
-      is returned.
-    - If the JSON pointer points to an array index that does not exist, it
-      is created an filled with a `null` value before a reference to it
-      is returned. All indices between the current maximum and the given
-      index are also filled with `null`.
-    - The special value `-` is treated as a synonym for the index past the
-      end.
-
-    @param[in] ptr  a JSON pointer
-
-    @return reference to the element pointed to by @a ptr
-
-    @complexity Constant.
-
-    @throw parse_error.106   if an array index begins with '0'
-    @throw parse_error.109   if an array index was not a number
-    @throw out_of_range.404  if the JSON pointer can not be resolved
-
-    @liveexample{The behavior is shown in the example.,operatorjson_pointer}
-
-    @since version 2.0.0
-    */
-    reference operator[](const json_pointer& ptr)
-    {
-        return ptr.get_unchecked(this);
-    }
-
-    /*!
-    @brief access specified element via JSON Pointer
-
-    Uses a JSON pointer to retrieve a reference to the respective JSON value.
-    No bound checking is performed. The function does not change the JSON
-    value; no `null` values are created. In particular, the special value
-    `-` yields an exception.
-
-    @param[in] ptr  JSON pointer to the desired element
-
-    @return const reference to the element pointed to by @a ptr
-
-    @complexity Constant.
-
-    @throw parse_error.106   if an array index begins with '0'
-    @throw parse_error.109   if an array index was not a number
-    @throw out_of_range.402  if the array index '-' is used
-    @throw out_of_range.404  if the JSON pointer can not be resolved
-
-    @liveexample{The behavior is shown in the example.,operatorjson_pointer_const}
-
-    @since version 2.0.0
-    */
-    const_reference operator[](const json_pointer& ptr) const
-    {
-        return ptr.get_unchecked(this);
-    }
-
-    /*!
-    @brief access specified element via JSON Pointer
-
-    Returns a reference to the element at with specified JSON pointer @a ptr,
-    with bounds checking.
-
-    @param[in] ptr  JSON pointer to the desired element
-
-    @return reference to the element pointed to by @a ptr
-
-    @throw parse_error.106 if an array index in the passed JSON pointer @a ptr
-    begins with '0'. See example below.
-
-    @throw parse_error.109 if an array index in the passed JSON pointer @a ptr
-    is not a number. See example below.
-
-    @throw out_of_range.401 if an array index in the passed JSON pointer @a ptr
-    is out of range. See example below.
-
-    @throw out_of_range.402 if the array index '-' is used in the passed JSON
-    pointer @a ptr. As `at` provides checked access (and no elements are
-    implicitly inserted), the index '-' is always invalid. See example below.
-
-    @throw out_of_range.403 if the JSON pointer describes a key of an object
-    which cannot be found. See example below.
-
-    @throw out_of_range.404 if the JSON pointer @a ptr can not be resolved.
-    See example below.
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes in the JSON value.
-
-    @complexity Constant.
-
-    @since version 2.0.0
-
-    @liveexample{The behavior is shown in the example.,at_json_pointer}
-    */
-    reference at(const json_pointer& ptr)
-    {
-        return ptr.get_checked(this);
-    }
-
-    /*!
-    @brief access specified element via JSON Pointer
-
-    Returns a const reference to the element at with specified JSON pointer @a
-    ptr, with bounds checking.
-
-    @param[in] ptr  JSON pointer to the desired element
-
-    @return reference to the element pointed to by @a ptr
-
-    @throw parse_error.106 if an array index in the passed JSON pointer @a ptr
-    begins with '0'. See example below.
-
-    @throw parse_error.109 if an array index in the passed JSON pointer @a ptr
-    is not a number. See example below.
-
-    @throw out_of_range.401 if an array index in the passed JSON pointer @a ptr
-    is out of range. See example below.
-
-    @throw out_of_range.402 if the array index '-' is used in the passed JSON
-    pointer @a ptr. As `at` provides checked access (and no elements are
-    implicitly inserted), the index '-' is always invalid. See example below.
-
-    @throw out_of_range.403 if the JSON pointer describes a key of an object
-    which cannot be found. See example below.
-
-    @throw out_of_range.404 if the JSON pointer @a ptr can not be resolved.
-    See example below.
-
-    @exceptionsafety Strong guarantee: if an exception is thrown, there are no
-    changes in the JSON value.
-
-    @complexity Constant.
-
-    @since version 2.0.0
-
-    @liveexample{The behavior is shown in the example.,at_json_pointer_const}
-    */
-    const_reference at(const json_pointer& ptr) const
-    {
-        return ptr.get_checked(this);
-    }
-
-    /*!
-    @brief return flattened JSON value
-
-    The function creates a JSON object whose keys are JSON pointers (see [RFC
-    6901](https://tools.ietf.org/html/rfc6901)) and whose values are all
-    primitive. The original JSON value can be restored using the @ref
-    unflatten() function.
-
-    @return an object that maps JSON pointers to primitive values
-
-    @note Empty objects and arrays are flattened to `null` and will not be
-          reconstructed correctly by the @ref unflatten() function.
-
-    @complexity Linear in the size the JSON value.
-
-    @liveexample{The following code shows how a JSON object is flattened to an
-    object whose keys consist of JSON pointers.,flatten}
-
-    @sa @ref unflatten() for the reverse function
-
-    @since version 2.0.0
-    */
-    basic_json flatten() const
-    {
-        basic_json result(value_t::object);
-        json_pointer::flatten("", *this, result);
-        return result;
-    }
-
-    /*!
-    @brief unflatten a previously flattened JSON value
-
-    The function restores the arbitrary nesting of a JSON value that has been
-    flattened before using the @ref flatten() function. The JSON value must
-    meet certain constraints:
-    1. The value must be an object.
-    2. The keys must be JSON pointers (see
-       [RFC 6901](https://tools.ietf.org/html/rfc6901))
-    3. The mapped values must be primitive JSON types.
-
-    @return the original JSON from a flattened version
-
-    @note Empty objects and arrays are flattened by @ref flatten() to `null`
-          values and can not unflattened to their original type. Apart from
-          this example, for a JSON value `j`, the following is always true:
-          `j == j.flatten().unflatten()`.
-
-    @complexity Linear in the size the JSON value.
-
-    @throw type_error.314  if value is not an object
-    @throw type_error.315  if object values are not primitive
-
-    @liveexample{The following code shows how a flattened JSON object is
-    unflattened into the original nested JSON object.,unflatten}
-
-    @sa @ref flatten() for the reverse function
-
-    @since version 2.0.0
-    */
-    basic_json unflatten() const
-    {
-        return json_pointer::unflatten(*this);
-    }
-
-    /// @}
-
-    //////////////////////////
-    // JSON Patch functions //
-    //////////////////////////
-
-    /// @name JSON Patch functions
-    /// @{
-
-    /*!
-    @brief applies a JSON patch
-
-    [JSON Patch](http://jsonpatch.com) defines a JSON document structure for
-    expressing a sequence of operations to apply to a JSON) document. With
-    this function, a JSON Patch is applied to the current JSON value by
-    executing all operations from the patch.
-
-    @param[in] json_patch  JSON patch document
-    @return patched document
-
-    @note The application of a patch is atomic: Either all operations succeed
-          and the patched document is returned or an exception is thrown. In
-          any case, the original value is not changed: the patch is applied
-          to a copy of the value.
-
-    @throw parse_error.104 if the JSON patch does not consist of an array of
-    objects
-
-    @throw parse_error.105 if the JSON patch is malformed (e.g., mandatory
-    attributes are missing); example: `"operation add must have member path"`
-
-    @throw out_of_range.401 if an array index is out of range.
-
-    @throw out_of_range.403 if a JSON pointer inside the patch could not be
-    resolved successfully in the current JSON value; example: `"key baz not
-    found"`
-
-    @throw out_of_range.405 if JSON pointer has no parent ("add", "remove",
-    "move")
-
-    @throw other_error.501 if "test" operation was unsuccessful
-
-    @complexity Linear in the size of the JSON value and the length of the
-    JSON patch. As usually only a fraction of the JSON value is affected by
-    the patch, the complexity can usually be neglected.
-
-    @liveexample{The following code shows how a JSON patch is applied to a
-    value.,patch}
-
-    @sa @ref diff -- create a JSON patch by comparing two JSON values
-
-    @sa [RFC 6902 (JSON Patch)](https://tools.ietf.org/html/rfc6902)
-    @sa [RFC 6901 (JSON Pointer)](https://tools.ietf.org/html/rfc6901)
-
-    @since version 2.0.0
-    */
-    basic_json patch(const basic_json& json_patch) const
-    {
-        // make a working copy to apply the patch to
-        basic_json result = *this;
-
-        // the valid JSON Patch operations
-        enum class patch_operations {add, remove, replace, move, copy, test, invalid};
-
-        const auto get_op = [](const std::string & op)
-        {
-            if (op == "add")
-            {
-                return patch_operations::add;
-            }
-            if (op == "remove")
-            {
-                return patch_operations::remove;
-            }
-            if (op == "replace")
-            {
-                return patch_operations::replace;
-            }
-            if (op == "move")
-            {
-                return patch_operations::move;
-            }
-            if (op == "copy")
-            {
-                return patch_operations::copy;
-            }
-            if (op == "test")
-            {
-                return patch_operations::test;
-            }
-
-            return patch_operations::invalid;
-        };
-
-        // wrapper for "add" operation; add value at ptr
-        const auto operation_add = [&result](json_pointer & ptr, basic_json val)
-        {
-            // adding to the root of the target document means replacing it
-            if (ptr.empty())
-            {
-                result = val;
-                return;
-            }
-
-            // make sure the top element of the pointer exists
-            json_pointer top_pointer = ptr.top();
-            if (top_pointer != ptr)
-            {
-                result.at(top_pointer);
-            }
-
-            // get reference to parent of JSON pointer ptr
-            const auto last_path = ptr.back();
-            ptr.pop_back();
-            basic_json& parent = result[ptr];
-
-            switch (parent.m_type)
-            {
-                case value_t::null:
-                case value_t::object:
-                {
-                    // use operator[] to add value
-                    parent[last_path] = val;
-                    break;
-                }
-
-                case value_t::array:
-                {
-                    if (last_path == "-")
-                    {
-                        // special case: append to back
-                        parent.push_back(val);
-                    }
-                    else
-                    {
-                        const auto idx = json_pointer::array_index(last_path);
-                        if (JSON_HEDLEY_UNLIKELY(idx > parent.size()))
-                        {
-                            // avoid undefined behavior
-                            JSON_THROW(out_of_range::create(401, "array index " + std::to_string(idx) + " is out of range"));
-                        }
-
-                        // default case: insert add offset
-                        parent.insert(parent.begin() + static_cast<difference_type>(idx), val);
-                    }
-                    break;
-                }
-
-                // if there exists a parent it cannot be primitive
-                default:            // LCOV_EXCL_LINE
-                    JSON_ASSERT(false);  // LCOV_EXCL_LINE
-            }
-        };
-
-        // wrapper for "remove" operation; remove value at ptr
-        const auto operation_remove = [&result](json_pointer & ptr)
-        {
-            // get reference to parent of JSON pointer ptr
-            const auto last_path = ptr.back();
-            ptr.pop_back();
-            basic_json& parent = result.at(ptr);
-
-            // remove child
-            if (parent.is_object())
-            {
-                // perform range check
-                auto it = parent.find(last_path);
-                if (JSON_HEDLEY_LIKELY(it != parent.end()))
-                {
-                    parent.erase(it);
-                }
-                else
-                {
-                    JSON_THROW(out_of_range::create(403, "key '" + last_path + "' not found"));
-                }
-            }
-            else if (parent.is_array())
-            {
-                // note erase performs range check
-                parent.erase(json_pointer::array_index(last_path));
-            }
-        };
-
-        // type check: top level value must be an array
-        if (JSON_HEDLEY_UNLIKELY(!json_patch.is_array()))
-        {
-            JSON_THROW(parse_error::create(104, 0, "JSON patch must be an array of objects"));
-        }
-
-        // iterate and apply the operations
-        for (const auto& val : json_patch)
-        {
-            // wrapper to get a value for an operation
-            const auto get_value = [&val](const std::string & op,
-                                          const std::string & member,
-                                          bool string_type) -> basic_json &
-            {
-                // find value
-                auto it = val.m_value.object->find(member);
-
-                // context-sensitive error message
-                const auto error_msg = (op == "op") ? "operation" : "operation '" + op + "'";
-
-                // check if desired value is present
-                if (JSON_HEDLEY_UNLIKELY(it == val.m_value.object->end()))
-                {
-                    JSON_THROW(parse_error::create(105, 0, error_msg + " must have member '" + member + "'"));
-                }
-
-                // check if result is of type string
-                if (JSON_HEDLEY_UNLIKELY(string_type && !it->second.is_string()))
-                {
-                    JSON_THROW(parse_error::create(105, 0, error_msg + " must have string member '" + member + "'"));
-                }
-
-                // no error: return value
-                return it->second;
-            };
-
-            // type check: every element of the array must be an object
-            if (JSON_HEDLEY_UNLIKELY(!val.is_object()))
-            {
-                JSON_THROW(parse_error::create(104, 0, "JSON patch must be an array of objects"));
-            }
-
-            // collect mandatory members
-            const auto op = get_value("op", "op", true).template get<std::string>();
-            const auto path = get_value(op, "path", true).template get<std::string>();
-            json_pointer ptr(path);
-
-            switch (get_op(op))
-            {
-                case patch_operations::add:
-                {
-                    operation_add(ptr, get_value("add", "value", false));
-                    break;
-                }
-
-                case patch_operations::remove:
-                {
-                    operation_remove(ptr);
-                    break;
-                }
-
-                case patch_operations::replace:
-                {
-                    // the "path" location must exist - use at()
-                    result.at(ptr) = get_value("replace", "value", false);
-                    break;
-                }
-
-                case patch_operations::move:
-                {
-                    const auto from_path = get_value("move", "from", true).template get<std::string>();
-                    json_pointer from_ptr(from_path);
-
-                    // the "from" location must exist - use at()
-                    basic_json v = result.at(from_ptr);
-
-                    // The move operation is functionally identical to a
-                    // "remove" operation on the "from" location, followed
-                    // immediately by an "add" operation at the target
-                    // location with the value that was just removed.
-                    operation_remove(from_ptr);
-                    operation_add(ptr, v);
-                    break;
-                }
-
-                case patch_operations::copy:
-                {
-                    const auto from_path = get_value("copy", "from", true).template get<std::string>();
-                    const json_pointer from_ptr(from_path);
-
-                    // the "from" location must exist - use at()
-                    basic_json v = result.at(from_ptr);
-
-                    // The copy is functionally identical to an "add"
-                    // operation at the target location using the value
-                    // specified in the "from" member.
-                    operation_add(ptr, v);
-                    break;
-                }
-
-                case patch_operations::test:
-                {
-                    bool success = false;
-                    JSON_TRY
-                    {
-                        // check if "value" matches the one at "path"
-                        // the "path" location must exist - use at()
-                        success = (result.at(ptr) == get_value("test", "value", false));
-                    }
-                    JSON_INTERNAL_CATCH (out_of_range&)
-                    {
-                        // ignore out of range errors: success remains false
-                    }
-
-                    // throw an exception if test fails
-                    if (JSON_HEDLEY_UNLIKELY(!success))
-                    {
-                        JSON_THROW(other_error::create(501, "unsuccessful: " + val.dump()));
-                    }
-
-                    break;
-                }
-
-                default:
-                {
-                    // op must be "add", "remove", "replace", "move", "copy", or
-                    // "test"
-                    JSON_THROW(parse_error::create(105, 0, "operation value '" + op + "' is invalid"));
-                }
-            }
-        }
-
-        return result;
-    }
-
-    /*!
-    @brief creates a diff as a JSON patch
-
-    Creates a [JSON Patch](http://jsonpatch.com) so that value @a source can
-    be changed into the value @a target by calling @ref patch function.
-
-    @invariant For two JSON values @a source and @a target, the following code
-    yields always `true`:
-    @code {.cpp}
-    source.patch(diff(source, target)) == target;
-    @endcode
-
-    @note Currently, only `remove`, `add`, and `replace` operations are
-          generated.
-
-    @param[in] source  JSON value to compare from
-    @param[in] target  JSON value to compare against
-    @param[in] path    helper value to create JSON pointers
-
-    @return a JSON patch to convert the @a source to @a target
-
-    @complexity Linear in the lengths of @a source and @a target.
-
-    @liveexample{The following code shows how a JSON patch is created as a
-    diff for two JSON values.,diff}
-
-    @sa @ref patch -- apply a JSON patch
-    @sa @ref merge_patch -- apply a JSON Merge Patch
-
-    @sa [RFC 6902 (JSON Patch)](https://tools.ietf.org/html/rfc6902)
-
-    @since version 2.0.0
-    */
-    JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json diff(const basic_json& source, const basic_json& target,
-                           const std::string& path = "")
-    {
-        // the patch
-        basic_json result(value_t::array);
-
-        // if the values are the same, return empty patch
-        if (source == target)
-        {
-            return result;
-        }
-
-        if (source.type() != target.type())
-        {
-            // different types: replace value
-            result.push_back(
-            {
-                {"op", "replace"}, {"path", path}, {"value", target}
-            });
-            return result;
-        }
-
-        switch (source.type())
-        {
-            case value_t::array:
-            {
-                // first pass: traverse common elements
-                std::size_t i = 0;
-                while (i < source.size() && i < target.size())
-                {
-                    // recursive call to compare array values at index i
-                    auto temp_diff = diff(source[i], target[i], path + "/" + std::to_string(i));
-                    result.insert(result.end(), temp_diff.begin(), temp_diff.end());
-                    ++i;
-                }
-
-                // i now reached the end of at least one array
-                // in a second pass, traverse the remaining elements
-
-                // remove my remaining elements
-                const auto end_index = static_cast<difference_type>(result.size());
-                while (i < source.size())
-                {
-                    // add operations in reverse order to avoid invalid
-                    // indices
-                    result.insert(result.begin() + end_index, object(
-                    {
-                        {"op", "remove"},
-                        {"path", path + "/" + std::to_string(i)}
-                    }));
-                    ++i;
-                }
-
-                // add other remaining elements
-                while (i < target.size())
-                {
-                    result.push_back(
-                    {
-                        {"op", "add"},
-                        {"path", path + "/-"},
-                        {"value", target[i]}
-                    });
-                    ++i;
-                }
-
-                break;
-            }
-
-            case value_t::object:
-            {
-                // first pass: traverse this object's elements
-                for (auto it = source.cbegin(); it != source.cend(); ++it)
-                {
-                    // escape the key name to be used in a JSON patch
-                    const auto key = json_pointer::escape(it.key());
-
-                    if (target.find(it.key()) != target.end())
-                    {
-                        // recursive call to compare object values at key it
-                        auto temp_diff = diff(it.value(), target[it.key()], path + "/" + key);
-                        result.insert(result.end(), temp_diff.begin(), temp_diff.end());
-                    }
-                    else
-                    {
-                        // found a key that is not in o -> remove it
-                        result.push_back(object(
-                        {
-                            {"op", "remove"}, {"path", path + "/" + key}
-                        }));
-                    }
-                }
-
-                // second pass: traverse other object's elements
-                for (auto it = target.cbegin(); it != target.cend(); ++it)
-                {
-                    if (source.find(it.key()) == source.end())
-                    {
-                        // found a key that is not in this -> add it
-                        const auto key = json_pointer::escape(it.key());
-                        result.push_back(
-                        {
-                            {"op", "add"}, {"path", path + "/" + key},
-                            {"value", it.value()}
-                        });
-                    }
-                }
-
-                break;
-            }
-
-            default:
-            {
-                // both primitive type: replace value
-                result.push_back(
-                {
-                    {"op", "replace"}, {"path", path}, {"value", target}
-                });
-                break;
-            }
-        }
-
-        return result;
-    }
-
-    /// @}
-
-    ////////////////////////////////
-    // JSON Merge Patch functions //
-    ////////////////////////////////
-
-    /// @name JSON Merge Patch functions
-    /// @{
-
-    /*!
-    @brief applies a JSON Merge Patch
-
-    The merge patch format is primarily intended for use with the HTTP PATCH
-    method as a means of describing a set of modifications to a target
-    resource's content. This function applies a merge patch to the current
-    JSON value.
-
-    The function implements the following algorithm from Section 2 of
-    [RFC 7396 (JSON Merge Patch)](https://tools.ietf.org/html/rfc7396):
-
-    ```
-    define MergePatch(Target, Patch):
-      if Patch is an Object:
-        if Target is not an Object:
-          Target = {} // Ignore the contents and set it to an empty Object
-        for each Name/Value pair in Patch:
-          if Value is null:
-            if Name exists in Target:
-              remove the Name/Value pair from Target
-          else:
-            Target[Name] = MergePatch(Target[Name], Value)
-        return Target
-      else:
-        return Patch
-    ```
-
-    Thereby, `Target` is the current object; that is, the patch is applied to
-    the current value.
-
-    @param[in] apply_patch  the patch to apply
-
-    @complexity Linear in the lengths of @a patch.
-
-    @liveexample{The following code shows how a JSON Merge Patch is applied to
-    a JSON document.,merge_patch}
-
-    @sa @ref patch -- apply a JSON patch
-    @sa [RFC 7396 (JSON Merge Patch)](https://tools.ietf.org/html/rfc7396)
-
-    @since version 3.0.0
-    */
-    void merge_patch(const basic_json& apply_patch)
-    {
-        if (apply_patch.is_object())
-        {
-            if (!is_object())
-            {
-                *this = object();
-            }
-            for (auto it = apply_patch.begin(); it != apply_patch.end(); ++it)
-            {
-                if (it.value().is_null())
-                {
-                    erase(it.key());
-                }
-                else
-                {
-                    operator[](it.key()).merge_patch(it.value());
-                }
-            }
-        }
-        else
-        {
-            *this = apply_patch;
-        }
-    }
-
-    /// @}
-};
-
-/*!
-@brief user-defined to_string function for JSON values
-
-This function implements a user-defined to_string  for JSON objects.
-
-@param[in] j  a JSON object
-@return a std::string object
-*/
-
-NLOHMANN_BASIC_JSON_TPL_DECLARATION
-std::string to_string(const NLOHMANN_BASIC_JSON_TPL& j)
-{
-    return j.dump();
-}
-} // namespace nlohmann
-
-///////////////////////
-// nonmember support //
-///////////////////////
-
-// specialization of std::swap, and std::hash
-namespace std
-{
-
-/// hash value for JSON objects
-template<>
-struct hash<nlohmann::json>
-{
-    /*!
-    @brief return a hash value for a JSON object
-
-    @since version 1.0.0
-    */
-    std::size_t operator()(const nlohmann::json& j) const
-    {
-        return nlohmann::detail::hash(j);
-    }
-};
-
-/// specialization for std::less<value_t>
-/// @note: do not remove the space after '<',
-///        see https://github.com/nlohmann/json/pull/679
-template<>
-struct less<::nlohmann::detail::value_t>
-{
-    /*!
-    @brief compare two value_t enum values
-    @since version 3.0.0
-    */
-    bool operator()(nlohmann::detail::value_t lhs,
-                    nlohmann::detail::value_t rhs) const noexcept
-    {
-        return nlohmann::detail::operator<(lhs, rhs);
-    }
-};
-
-// C++20 prohibit function specialization in the std namespace.
-#ifndef JSON_HAS_CPP_20
-
-/*!
-@brief exchanges the values of two JSON objects
-
-@since version 1.0.0
-*/
-template<>
-inline void swap<nlohmann::json>(nlohmann::json& j1, nlohmann::json& j2) noexcept(
-    is_nothrow_move_constructible<nlohmann::json>::value&&
-    is_nothrow_move_assignable<nlohmann::json>::value
-                              )
-{
-    j1.swap(j2);
-}
-
-#endif
-
-} // namespace std
-
-/*!
-@brief user-defined string literal for JSON values
-
-This operator implements a user-defined string literal for JSON objects. It
-can be used by adding `"_json"` to a string literal and returns a JSON object
-if no parse error occurred.
-
-@param[in] s  a string representation of a JSON object
-@param[in] n  the length of string @a s
-@return a JSON object
-
-@since version 1.0.0
-*/
-JSON_HEDLEY_NON_NULL(1)
-inline nlohmann::json operator "" _json(const char* s, std::size_t n)
-{
-    return nlohmann::json::parse(s, s + n);
-}
-
-/*!
-@brief user-defined string literal for JSON pointer
-
-This operator implements a user-defined string literal for JSON Pointers. It
-can be used by adding `"_json_pointer"` to a string literal and returns a JSON pointer
-object if no parse error occurred.
-
-@param[in] s  a string representation of a JSON Pointer
-@param[in] n  the length of string @a s
-@return a JSON pointer object
-
-@since version 2.0.0
-*/
-JSON_HEDLEY_NON_NULL(1)
-inline nlohmann::json::json_pointer operator "" _json_pointer(const char* s, std::size_t n)
-{
-    return nlohmann::json::json_pointer(std::string(s, n));
-}
-
-// #include <nlohmann/detail/macro_unscope.hpp>
-
-
-// restore GCC/clang diagnostic settings
-#if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
-    #pragma GCC diagnostic pop
-#endif
-#if defined(__clang__)
-    #pragma GCC diagnostic pop
-#endif
-
-// clean up
-#undef JSON_ASSERT
-#undef JSON_INTERNAL_CATCH
-#undef JSON_CATCH
-#undef JSON_THROW
-#undef JSON_TRY
-#undef JSON_HAS_CPP_14
-#undef JSON_HAS_CPP_17
-#undef NLOHMANN_BASIC_JSON_TPL_DECLARATION
-#undef NLOHMANN_BASIC_JSON_TPL
-#undef JSON_EXPLICIT
-
-// #include <nlohmann/thirdparty/hedley/hedley_undef.hpp>
-#undef JSON_HEDLEY_ALWAYS_INLINE
-#undef JSON_HEDLEY_ARM_VERSION
-#undef JSON_HEDLEY_ARM_VERSION_CHECK
-#undef JSON_HEDLEY_ARRAY_PARAM
-#undef JSON_HEDLEY_ASSUME
-#undef JSON_HEDLEY_BEGIN_C_DECLS
-#undef JSON_HEDLEY_CLANG_HAS_ATTRIBUTE
-#undef JSON_HEDLEY_CLANG_HAS_BUILTIN
-#undef JSON_HEDLEY_CLANG_HAS_CPP_ATTRIBUTE
-#undef JSON_HEDLEY_CLANG_HAS_DECLSPEC_DECLSPEC_ATTRIBUTE
-#undef JSON_HEDLEY_CLANG_HAS_EXTENSION
-#undef JSON_HEDLEY_CLANG_HAS_FEATURE
-#undef JSON_HEDLEY_CLANG_HAS_WARNING
-#undef JSON_HEDLEY_COMPCERT_VERSION
-#undef JSON_HEDLEY_COMPCERT_VERSION_CHECK
-#undef JSON_HEDLEY_CONCAT
-#undef JSON_HEDLEY_CONCAT3
-#undef JSON_HEDLEY_CONCAT3_EX
-#undef JSON_HEDLEY_CONCAT_EX
-#undef JSON_HEDLEY_CONST
-#undef JSON_HEDLEY_CONSTEXPR
-#undef JSON_HEDLEY_CONST_CAST
-#undef JSON_HEDLEY_CPP_CAST
-#undef JSON_HEDLEY_CRAY_VERSION
-#undef JSON_HEDLEY_CRAY_VERSION_CHECK
-#undef JSON_HEDLEY_C_DECL
-#undef JSON_HEDLEY_DEPRECATED
-#undef JSON_HEDLEY_DEPRECATED_FOR
-#undef JSON_HEDLEY_DIAGNOSTIC_DISABLE_CAST_QUAL
-#undef JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_
-#undef JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED
-#undef JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_CPP_ATTRIBUTES
-#undef JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS
-#undef JSON_HEDLEY_DIAGNOSTIC_POP
-#undef JSON_HEDLEY_DIAGNOSTIC_PUSH
-#undef JSON_HEDLEY_DMC_VERSION
-#undef JSON_HEDLEY_DMC_VERSION_CHECK
-#undef JSON_HEDLEY_EMPTY_BASES
-#undef JSON_HEDLEY_EMSCRIPTEN_VERSION
-#undef JSON_HEDLEY_EMSCRIPTEN_VERSION_CHECK
-#undef JSON_HEDLEY_END_C_DECLS
-#undef JSON_HEDLEY_FLAGS
-#undef JSON_HEDLEY_FLAGS_CAST
-#undef JSON_HEDLEY_GCC_HAS_ATTRIBUTE
-#undef JSON_HEDLEY_GCC_HAS_BUILTIN
-#undef JSON_HEDLEY_GCC_HAS_CPP_ATTRIBUTE
-#undef JSON_HEDLEY_GCC_HAS_DECLSPEC_ATTRIBUTE
-#undef JSON_HEDLEY_GCC_HAS_EXTENSION
-#undef JSON_HEDLEY_GCC_HAS_FEATURE
-#undef JSON_HEDLEY_GCC_HAS_WARNING
-#undef JSON_HEDLEY_GCC_NOT_CLANG_VERSION_CHECK
-#undef JSON_HEDLEY_GCC_VERSION
-#undef JSON_HEDLEY_GCC_VERSION_CHECK
-#undef JSON_HEDLEY_GNUC_HAS_ATTRIBUTE
-#undef JSON_HEDLEY_GNUC_HAS_BUILTIN
-#undef JSON_HEDLEY_GNUC_HAS_CPP_ATTRIBUTE
-#undef JSON_HEDLEY_GNUC_HAS_DECLSPEC_ATTRIBUTE
-#undef JSON_HEDLEY_GNUC_HAS_EXTENSION
-#undef JSON_HEDLEY_GNUC_HAS_FEATURE
-#undef JSON_HEDLEY_GNUC_HAS_WARNING
-#undef JSON_HEDLEY_GNUC_VERSION
-#undef JSON_HEDLEY_GNUC_VERSION_CHECK
-#undef JSON_HEDLEY_HAS_ATTRIBUTE
-#undef JSON_HEDLEY_HAS_BUILTIN
-#undef JSON_HEDLEY_HAS_CPP_ATTRIBUTE
-#undef JSON_HEDLEY_HAS_CPP_ATTRIBUTE_NS
-#undef JSON_HEDLEY_HAS_DECLSPEC_ATTRIBUTE
-#undef JSON_HEDLEY_HAS_EXTENSION
-#undef JSON_HEDLEY_HAS_FEATURE
-#undef JSON_HEDLEY_HAS_WARNING
-#undef JSON_HEDLEY_IAR_VERSION
-#undef JSON_HEDLEY_IAR_VERSION_CHECK
-#undef JSON_HEDLEY_IBM_VERSION
-#undef JSON_HEDLEY_IBM_VERSION_CHECK
-#undef JSON_HEDLEY_IMPORT
-#undef JSON_HEDLEY_INLINE
-#undef JSON_HEDLEY_INTEL_VERSION
-#undef JSON_HEDLEY_INTEL_VERSION_CHECK
-#undef JSON_HEDLEY_IS_CONSTANT
-#undef JSON_HEDLEY_IS_CONSTEXPR_
-#undef JSON_HEDLEY_LIKELY
-#undef JSON_HEDLEY_MALLOC
-#undef JSON_HEDLEY_MESSAGE
-#undef JSON_HEDLEY_MSVC_VERSION
-#undef JSON_HEDLEY_MSVC_VERSION_CHECK
-#undef JSON_HEDLEY_NEVER_INLINE
-#undef JSON_HEDLEY_NON_NULL
-#undef JSON_HEDLEY_NO_ESCAPE
-#undef JSON_HEDLEY_NO_RETURN
-#undef JSON_HEDLEY_NO_THROW
-#undef JSON_HEDLEY_NULL
-#undef JSON_HEDLEY_PELLES_VERSION
-#undef JSON_HEDLEY_PELLES_VERSION_CHECK
-#undef JSON_HEDLEY_PGI_VERSION
-#undef JSON_HEDLEY_PGI_VERSION_CHECK
-#undef JSON_HEDLEY_PREDICT
-#undef JSON_HEDLEY_PRINTF_FORMAT
-#undef JSON_HEDLEY_PRIVATE
-#undef JSON_HEDLEY_PUBLIC
-#undef JSON_HEDLEY_PURE
-#undef JSON_HEDLEY_REINTERPRET_CAST
-#undef JSON_HEDLEY_REQUIRE
-#undef JSON_HEDLEY_REQUIRE_CONSTEXPR
-#undef JSON_HEDLEY_REQUIRE_MSG
-#undef JSON_HEDLEY_RESTRICT
-#undef JSON_HEDLEY_RETURNS_NON_NULL
-#undef JSON_HEDLEY_SENTINEL
-#undef JSON_HEDLEY_STATIC_ASSERT
-#undef JSON_HEDLEY_STATIC_CAST
-#undef JSON_HEDLEY_STRINGIFY
-#undef JSON_HEDLEY_STRINGIFY_EX
-#undef JSON_HEDLEY_SUNPRO_VERSION
-#undef JSON_HEDLEY_SUNPRO_VERSION_CHECK
-#undef JSON_HEDLEY_TINYC_VERSION
-#undef JSON_HEDLEY_TINYC_VERSION_CHECK
-#undef JSON_HEDLEY_TI_ARMCL_VERSION
-#undef JSON_HEDLEY_TI_ARMCL_VERSION_CHECK
-#undef JSON_HEDLEY_TI_CL2000_VERSION
-#undef JSON_HEDLEY_TI_CL2000_VERSION_CHECK
-#undef JSON_HEDLEY_TI_CL430_VERSION
-#undef JSON_HEDLEY_TI_CL430_VERSION_CHECK
-#undef JSON_HEDLEY_TI_CL6X_VERSION
-#undef JSON_HEDLEY_TI_CL6X_VERSION_CHECK
-#undef JSON_HEDLEY_TI_CL7X_VERSION
-#undef JSON_HEDLEY_TI_CL7X_VERSION_CHECK
-#undef JSON_HEDLEY_TI_CLPRU_VERSION
-#undef JSON_HEDLEY_TI_CLPRU_VERSION_CHECK
-#undef JSON_HEDLEY_TI_VERSION
-#undef JSON_HEDLEY_TI_VERSION_CHECK
-#undef JSON_HEDLEY_UNAVAILABLE
-#undef JSON_HEDLEY_UNLIKELY
-#undef JSON_HEDLEY_UNPREDICTABLE
-#undef JSON_HEDLEY_UNREACHABLE
-#undef JSON_HEDLEY_UNREACHABLE_RETURN
-#undef JSON_HEDLEY_VERSION
-#undef JSON_HEDLEY_VERSION_DECODE_MAJOR
-#undef JSON_HEDLEY_VERSION_DECODE_MINOR
-#undef JSON_HEDLEY_VERSION_DECODE_REVISION
-#undef JSON_HEDLEY_VERSION_ENCODE
-#undef JSON_HEDLEY_WARNING
-#undef JSON_HEDLEY_WARN_UNUSED_RESULT
-#undef JSON_HEDLEY_WARN_UNUSED_RESULT_MSG
-#undef JSON_HEDLEY_FALL_THROUGH
-
-
-
-#endif  // INCLUDE_NLOHMANN_JSON_HPP_
diff --git a/src/nlohmann/json_fwd.hpp b/src/nlohmann/json_fwd.hpp
deleted file mode 100644
index 332227c1b..000000000
--- a/src/nlohmann/json_fwd.hpp
+++ /dev/null
@@ -1,78 +0,0 @@
-#ifndef INCLUDE_NLOHMANN_JSON_FWD_HPP_
-#define INCLUDE_NLOHMANN_JSON_FWD_HPP_
-
-#include <cstdint> // int64_t, uint64_t
-#include <map> // map
-#include <memory> // allocator
-#include <string> // string
-#include <vector> // vector
-
-/*!
-@brief namespace for Niels Lohmann
-@see https://github.com/nlohmann
-@since version 1.0.0
-*/
-namespace nlohmann
-{
-/*!
-@brief default JSONSerializer template argument
-
-This serializer ignores the template arguments and uses ADL
-([argument-dependent lookup](https://en.cppreference.com/w/cpp/language/adl))
-for serialization.
-*/
-template<typename T = void, typename SFINAE = void>
-struct adl_serializer;
-
-template<template<typename U, typename V, typename... Args> class ObjectType =
-         std::map,
-         template<typename U, typename... Args> class ArrayType = std::vector,
-         class StringType = std::string, class BooleanType = bool,
-         class NumberIntegerType = std::int64_t,
-         class NumberUnsignedType = std::uint64_t,
-         class NumberFloatType = double,
-         template<typename U> class AllocatorType = std::allocator,
-         template<typename T, typename SFINAE = void> class JSONSerializer =
-         adl_serializer,
-         class BinaryType = std::vector<std::uint8_t>>
-class basic_json;
-
-/*!
-@brief JSON Pointer
-
-A JSON pointer defines a string syntax for identifying a specific value
-within a JSON document. It can be used with functions `at` and
-`operator[]`. Furthermore, JSON pointers are the base for JSON patches.
-
-@sa [RFC 6901](https://tools.ietf.org/html/rfc6901)
-
-@since version 2.0.0
-*/
-template<typename BasicJsonType>
-class json_pointer;
-
-/*!
-@brief default JSON class
-
-This type is the default specialization of the @ref basic_json class which
-uses the standard template types.
-
-@since version 1.0.0
-*/
-using json = basic_json<>;
-
-template<class Key, class T, class IgnoredLess, class Allocator>
-struct ordered_map;
-
-/*!
-@brief ordered JSON class
-
-This type preserves the insertion order of object keys.
-
-@since version 3.9.0
-*/
-using ordered_json = basic_json<nlohmann::ordered_map>;
-
-}  // namespace nlohmann
-
-#endif  // INCLUDE_NLOHMANN_JSON_FWD_HPP_
diff --git a/src/nlohmann/local.mk b/src/nlohmann/local.mk
deleted file mode 100644
index 63c427e00..000000000
--- a/src/nlohmann/local.mk
+++ /dev/null
@@ -1,2 +0,0 @@
-$(foreach i, $(wildcard src/nlohmann/*.hpp), \
-  $(eval $(call install-file-in, $(i), $(includedir)/nlohmann, 0644)))

From 3dc1418216d30274695c51ba47e05cf92789d4df Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Wed, 26 Jan 2022 12:49:16 +0100
Subject: [PATCH 492/567] Fix the `store ping` test

---
 tests/store-ping.sh | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tests/store-ping.sh b/tests/store-ping.sh
index 4e8c8b770..f9427cf0a 100644
--- a/tests/store-ping.sh
+++ b/tests/store-ping.sh
@@ -4,8 +4,9 @@ STORE_INFO=$(nix store ping 2>&1)
 
 echo "$STORE_INFO" | grep "Store URL: ${NIX_REMOTE}"
 
-if isDaemonNewer "2.7pre20220126"; then
-    echo "$STORE_INFO" | grep "Version: $($NIX_DAEMON_PACKAGE/bin/nix-daemon --version)"
+if [[ -v NIX_DAEMON_PACKAGE ]] && isDaemonNewer "2.7.0pre20220126"; then
+    DAEMON_VERSION=$($NIX_DAEMON_PACKAGE/bin/nix-daemon --version | cut -d' ' -f3)
+    echo "$STORE_INFO" | grep "Version: $DAEMON_VERSION"
 fi
 
 expect 127 NIX_REMOTE=unix:$PWD/store nix store ping || \

From 7bd85a3bf649a02a7bb428a8fb1f0f96ab690824 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Wed, 26 Jan 2022 14:31:23 +0100
Subject: [PATCH 493/567] Use the `nix` command (and flakes) in the CI
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Apart from a slight simplification and a bit of dogfooding, this also
make the cache behavior more predictable.
For example `nix build .` and `nix build nix/$(git rev-parse HEAD)` will
yield the exact same path, while their “intuitive” non-flake equivalents
(`nix-build` and
`nix-build https://github.com/nixos/nix/archives/$(git rev-parse HEAD).tar.gz`)
don’t.

This was a pain for example in https://github.com/NixOS/nix/pull/5059

Also, the `bar-with-logs` log format is imho nicer (even in an
non-interactive context) because prefixing each log line with the name
of the derivation that produced it makes it much easier to follow what’s
going on.
---
 .github/workflows/ci.yml |  4 ++--
 flake.nix                | 28 +++++++++++++++-------------
 2 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 77d9f5250..09436b7e3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -25,7 +25,7 @@ jobs:
         name: '${{ env.CACHIX_NAME }}'
         signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
         authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
-    - run: nix-build -A checks.$(nix-instantiate --eval -E '(builtins.currentSystem)')
+    - run: nix --experimental-features 'nix-command flakes' flake check -L
 
   check_cachix:
     name: Cachix secret present for installer tests
@@ -95,7 +95,7 @@ jobs:
         name: '${{ env.CACHIX_NAME }}'
         signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
         authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
-    - run: nix-build -A checks.$(nix-instantiate --eval -E 'builtins.currentSystem' --json).dockerImage
+    - run: nix --experimental-features 'nix-command flakes' build .#dockerImage -L
     - run: docker load -i ./result/image.tar.gz
     - run: docker tag nix:$NIX_VERSION nixos/nix:$NIX_VERSION
     - run: docker tag nix:$NIX_VERSION nixos/nix:master
diff --git a/flake.nix b/flake.nix
index 05b38d1dd..5b1e13a16 100644
--- a/flake.nix
+++ b/flake.nix
@@ -447,19 +447,7 @@
         installerScriptForGHA = installScriptFor [ "x86_64-linux" "x86_64-darwin" "armv6l-linux" "armv7l-linux"];
 
         # docker image with Nix inside
-        dockerImage = nixpkgs.lib.genAttrs linux64BitSystems (system:
-          let
-            pkgs = nixpkgsFor.${system};
-            image = import ./docker.nix { inherit pkgs; tag = version; };
-          in pkgs.runCommand "docker-image-tarball-${version}"
-            { meta.description = "Docker image with Nix for ${system}";
-            }
-            ''
-              mkdir -p $out/nix-support
-              image=$out/image.tar.gz
-              ln -s ${image} $image
-              echo "file binary-dist $image" >> $out/nix-support/hydra-build-products
-            '');
+        dockerImage = nixpkgs.lib.genAttrs linux64BitSystems (system: self.packages.${system}.dockerImage);
 
         # Line coverage analysis.
         coverage =
@@ -606,6 +594,20 @@
 
           hardeningDisable = [ "pie" ];
         };
+        dockerImage =
+          let
+            pkgs = nixpkgsFor.${system};
+            image = import ./docker.nix { inherit pkgs; tag = version; };
+          in
+          pkgs.runCommand
+            "docker-image-tarball-${version}"
+            { meta.description = "Docker image with Nix for ${system}"; }
+            ''
+              mkdir -p $out/nix-support
+              image=$out/image.tar.gz
+              ln -s ${image} $image
+              echo "file binary-dist $image" >> $out/nix-support/hydra-build-products
+            '';
       } // builtins.listToAttrs (map (crossSystem: {
         name = "nix-${crossSystem}";
         value = let

From fcdc60ed227ba28f0d0d160d17df27fe179138b0 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Thu, 27 Jan 2022 15:32:14 +0100
Subject: [PATCH 494/567] =?UTF-8?q?Don=E2=80=99t=20require=20`NIX=5FPATH`?=
 =?UTF-8?q?=20entries=20to=20be=20valid=20paths?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

It’s totally valid to have entries in `NIX_PATH` that aren’t valid paths
(they can even be arbitrary urls or `channel:<channel-name>`).

Fix #5998 and #5980
---
 src/libexpr/primops.cc | 20 ++++++++++++++------
 tests/local.mk         |  1 +
 tests/nix_path.sh      | 11 +++++++++++
 3 files changed, 26 insertions(+), 6 deletions(-)
 create mode 100644 tests/nix_path.sh

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 9d36f72a8..acee71d19 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -92,8 +92,6 @@ StringMap EvalState::realiseContext(const PathSet & context)
 }
 
 struct RealisePathFlags {
-    // Whether to check whether the path is a valid absolute path
-    bool requireAbsolutePath = true;
     // Whether to check that the path is allowed in pure eval mode
     bool checkForPureEval = true;
 };
@@ -105,9 +103,7 @@ static Path realisePath(EvalState & state, const Pos & pos, Value & v, const Rea
     auto path = [&]()
     {
         try {
-            return flags.requireAbsolutePath
-                ? state.coerceToPath(pos, v, context)
-                : state.coerceToString(pos, v, context, false, false);
+            return state.coerceToPath(pos, v, context);
         } catch (Error & e) {
             e.addTrace(pos, "while realising the context of a path");
             throw;
@@ -1489,7 +1485,19 @@ static void prim_findFile(EvalState & state, const Pos & pos, Value * * args, Va
             pos
         );
 
-        auto path = realisePath(state, pos, *i->value, { .requireAbsolutePath = false });
+        PathSet context;
+        string path = state.coerceToString(pos, *i->value, context, false, false);
+
+        try {
+            auto rewrites = state.realiseContext(context);
+            path = rewriteStrings(path, rewrites);
+        } catch (InvalidPathError & e) {
+            throw EvalError({
+                .msg = hintfmt("cannot find '%1%', since path '%2%' is not valid", path, e.path),
+                .errPos = pos
+            });
+        }
+
 
         searchPath.emplace_back(prefix, path);
     }
diff --git a/tests/local.mk b/tests/local.mk
index 47d2862a4..2ec9baa12 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -63,6 +63,7 @@ nix_tests = \
   eval-store.sh \
   readfile-context.sh \
   store-ping.sh \
+  nix_path.sh \
   why-depends.sh
   # parallel.sh
 
diff --git a/tests/nix_path.sh b/tests/nix_path.sh
new file mode 100644
index 000000000..d3657abf0
--- /dev/null
+++ b/tests/nix_path.sh
@@ -0,0 +1,11 @@
+# Regression for https://github.com/NixOS/nix/issues/5998 and https://github.com/NixOS/nix/issues/5980
+
+source common.sh
+
+export NIX_PATH=non-existent=/non-existent/but-unused-anyways:by-absolute-path=$PWD:by-relative-path=.
+
+nix-instantiate --eval -E '<by-absolute-path/simple.nix>' --restrict-eval
+nix-instantiate --eval -E '<by-relative-path/simple.nix>' --restrict-eval
+
+# Should ideally also test this, but there’s no pure way to do it, so just trust me that it works
+# nix-instantiate --eval -E '<nixpkgs>' -I nixpkgs=channel:nixos-unstable --restrict-eval

From 0d7fae6a574ec1b6758a7e6d8e639145c1c465a9 Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Fri, 21 Jan 2022 17:55:51 +0100
Subject: [PATCH 495/567] convert a for more utilities to string_view

---
 src/libexpr/eval.hh                           |  4 ++--
 src/libexpr/parser.y                          |  2 +-
 src/libstore/optimise-store.cc                |  9 +++++----
 src/libstore/parsed-derivations.cc            |  2 +-
 src/libutil/util.cc                           | 20 ++++++++++---------
 src/libutil/util.hh                           | 10 +++++++---
 src/nix/develop.cc                            |  6 ++++--
 .../resolve-system-dependencies.cc            |  2 +-
 8 files changed, 32 insertions(+), 23 deletions(-)

diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index c59203aa5..67bdd4de4 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -309,8 +309,8 @@ private:
     friend struct ExprAttrs;
     friend struct ExprLet;
 
-    Expr * parse(char * text, size_t length, FileOrigin origin, const Path & path,
-        const Path & basePath, StaticEnv & staticEnv);
+    Expr * parse(char * text, size_t length, FileOrigin origin, const PathView path,
+        const PathView basePath, StaticEnv & staticEnv);
 
 public:
 
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 7a8e93c12..dd76fd66f 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -598,7 +598,7 @@ namespace nix {
 
 
 Expr * EvalState::parse(char * text, size_t length, FileOrigin origin,
-    const Path & path, const Path & basePath, StaticEnv & staticEnv)
+    const PathView path, const PathView basePath, StaticEnv & staticEnv)
 {
     yyscan_t scanner;
     ParseData data(*this);
diff --git a/src/libstore/optimise-store.cc b/src/libstore/optimise-store.cc
index 1833c954e..13cb142f8 100644
--- a/src/libstore/optimise-store.cc
+++ b/src/libstore/optimise-store.cc
@@ -26,7 +26,7 @@ static void makeWritable(const Path & path)
 struct MakeReadOnly
 {
     Path path;
-    MakeReadOnly(const Path & path) : path(path) { }
+    MakeReadOnly(const PathView path) : path(path) { }
     ~MakeReadOnly()
     {
         try {
@@ -205,12 +205,13 @@ void LocalStore::optimisePath_(Activity * act, OptimiseStats & stats,
     /* Make the containing directory writable, but only if it's not
        the store itself (we don't want or need to mess with its
        permissions). */
-    bool mustToggle = dirOf(path) != realStoreDir.get();
-    if (mustToggle) makeWritable(dirOf(path));
+    const Path dirOfPath(dirOf(path));
+    bool mustToggle = dirOfPath != realStoreDir.get();
+    if (mustToggle) makeWritable(dirOfPath);
 
     /* When we're done, make the directory read-only again and reset
        its timestamp back to 0. */
-    MakeReadOnly makeReadOnly(mustToggle ? dirOf(path) : "");
+    MakeReadOnly makeReadOnly(mustToggle ? dirOfPath : "");
 
     Path tempLink = (format("%1%/.tmp-link-%2%-%3%")
         % realStoreDir % getpid() % random()).str();
diff --git a/src/libstore/parsed-derivations.cc b/src/libstore/parsed-derivations.cc
index caddba9b1..8c65053e4 100644
--- a/src/libstore/parsed-derivations.cc
+++ b/src/libstore/parsed-derivations.cc
@@ -170,7 +170,7 @@ std::string writeStructuredAttrsShell(const nlohmann::json & json)
 
     auto handleSimpleType = [](const nlohmann::json & value) -> std::optional<std::string> {
         if (value.is_string())
-            return shellEscape(value);
+            return shellEscape(value.get<std::string_view>());
 
         if (value.is_number()) {
             auto f = value.get<float>();
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 1f1f2c861..692bcb180 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -81,7 +81,7 @@ void replaceEnv(std::map<std::string, std::string> newEnv)
 }
 
 
-Path absPath(Path path, std::optional<Path> dir, bool resolveSymlinks)
+Path absPath(Path path, std::optional<PathView> dir, bool resolveSymlinks)
 {
     if (path[0] != '/') {
         if (!dir) {
@@ -95,12 +95,12 @@ Path absPath(Path path, std::optional<Path> dir, bool resolveSymlinks)
             if (!getcwd(buf, sizeof(buf)))
 #endif
                 throw SysError("cannot get cwd");
-            dir = buf;
+            path = concatStrings(buf, "/", path);
 #ifdef __GNU__
             free(buf);
 #endif
-        }
-        path = *dir + "/" + path;
+        } else
+            path = concatStrings(*dir, "/", path);
     }
     return canonPath(path, resolveSymlinks);
 }
@@ -172,7 +172,7 @@ Path canonPath(PathView path, bool resolveSymlinks)
 }
 
 
-Path dirOf(const Path & path)
+Path dirOf(const PathView path)
 {
     Path::size_type pos = path.rfind('/');
     if (pos == string::npos)
@@ -1344,9 +1344,11 @@ std::string toLower(const std::string & s)
 }
 
 
-std::string shellEscape(const std::string & s)
+std::string shellEscape(const std::string_view s)
 {
-    std::string r = "'";
+    std::string r;
+    r.reserve(s.size() + 2);
+    r += "'";
     for (auto & i : s)
         if (i == '\'') r += "'\\''"; else r += i;
     r += '\'';
@@ -1751,7 +1753,7 @@ void bind(int fd, const std::string & path)
 
     if (path.size() + 1 >= sizeof(addr.sun_path)) {
         Pid pid = startProcess([&]() {
-            auto dir = dirOf(path);
+            Path dir = dirOf(path);
             if (chdir(dir.c_str()) == -1)
                 throw SysError("chdir to '%s' failed", dir);
             std::string base(baseNameOf(path));
@@ -1780,7 +1782,7 @@ void connect(int fd, const std::string & path)
 
     if (path.size() + 1 >= sizeof(addr.sun_path)) {
         Pid pid = startProcess([&]() {
-            auto dir = dirOf(path);
+            Path dir = dirOf(path);
             if (chdir(dir.c_str()) == -1)
                 throw SysError("chdir to '%s' failed", dir);
             std::string base(baseNameOf(path));
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 369c44f78..579a42785 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -49,7 +49,7 @@ void clearEnv();
    specified directory, or the current directory otherwise.  The path
    is also canonicalised. */
 Path absPath(Path path,
-    std::optional<Path> dir = {},
+    std::optional<PathView> dir = {},
     bool resolveSymlinks = false);
 
 /* Canonicalise a path by removing all `.' or `..' components and
@@ -62,7 +62,7 @@ Path canonPath(PathView path, bool resolveSymlinks = false);
    everything before the final `/'.  If the path is the root or an
    immediate child thereof (e.g., `/foo'), this means `/'
    is returned.*/
-Path dirOf(const Path & path);
+Path dirOf(const PathView path);
 
 /* Return the base name of the given canonical path, i.e., everything
    following the final `/' (trailing slashes are removed). */
@@ -148,6 +148,9 @@ Path getDataDir();
 /* Create a directory and all its parents, if necessary.  Returns the
    list of created directories, in order of creation. */
 Paths createDirs(const Path & path);
+inline Paths createDirs(PathView path) {
+    return createDirs(Path(path));
+}
 
 /* Create a symlink. */
 void createSymlink(const Path & target, const Path & link,
@@ -187,6 +190,7 @@ public:
     void cancel();
     void reset(const Path & p, bool recursive = true);
     operator Path() const { return path; }
+    operator PathView() const { return path; }
 };
 
 
@@ -491,7 +495,7 @@ std::string toLower(const std::string & s);
 
 
 /* Escape a string as a shell word. */
-std::string shellEscape(const std::string & s);
+std::string shellEscape(const std::string_view s);
 
 
 /* Exception handling in destructors: print an error message, then
diff --git a/src/nix/develop.cc b/src/nix/develop.cc
index a8ca1cac2..42e13436a 100644
--- a/src/nix/develop.cc
+++ b/src/nix/develop.cc
@@ -472,9 +472,11 @@ struct CmdDevelop : Common, MixEnvironment
         else {
             script = "[ -n \"$PS1\" ] && [ -e ~/.bashrc ] && source ~/.bashrc;\n" + script;
             if (developSettings.bashPrompt != "")
-                script += fmt("[ -n \"$PS1\" ] && PS1=%s;\n", shellEscape(developSettings.bashPrompt));
+                script += fmt("[ -n \"$PS1\" ] && PS1=%s;\n",
+                    shellEscape(developSettings.bashPrompt.get()));
             if (developSettings.bashPromptSuffix != "")
-                script += fmt("[ -n \"$PS1\" ] && PS1+=%s;\n", shellEscape(developSettings.bashPromptSuffix));
+                script += fmt("[ -n \"$PS1\" ] && PS1+=%s;\n",
+                    shellEscape(developSettings.bashPromptSuffix.get()));
         }
 
         writeFull(rcFileFd.get(), script);
diff --git a/src/resolve-system-dependencies/resolve-system-dependencies.cc b/src/resolve-system-dependencies/resolve-system-dependencies.cc
index 27cf53a45..98c969437 100644
--- a/src/resolve-system-dependencies/resolve-system-dependencies.cc
+++ b/src/resolve-system-dependencies/resolve-system-dependencies.cc
@@ -107,7 +107,7 @@ Path resolveSymlink(const Path & path)
     auto target = readLink(path);
     return hasPrefix(target, "/")
         ? target
-        : dirOf(path) + "/" + target;
+        : concatStrings(dirOf(path), "/", target);
 }
 
 std::set<string> resolveTree(const Path & path, PathSet & deps)

From 41d70a2fc8d243d8c83ecc1c9ba648b625957437 Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Fri, 21 Jan 2022 14:44:00 +0100
Subject: [PATCH 496/567] return string_views from forceString*

once a string has been forced we already have dynamic storage allocated for it,
so we can easily reuse that storage instead of copying.
---
 src/libexpr/attr-path.cc              |  2 +-
 src/libexpr/eval.cc                   | 12 ++--
 src/libexpr/eval.hh                   | 10 ++--
 src/libexpr/flake/flake.cc            |  6 +-
 src/libexpr/get-drvs.cc               |  2 +-
 src/libexpr/json-to-value.cc          |  2 +-
 src/libexpr/json-to-value.hh          |  2 +-
 src/libexpr/parser.y                  | 10 ++--
 src/libexpr/primops.cc                | 81 +++++++++++++++------------
 src/libexpr/primops/context.cc        |  2 +-
 src/libexpr/primops/fetchMercurial.cc |  8 +--
 src/libexpr/primops/fromTOML.cc       |  2 +-
 src/libstore/derivations.cc           |  4 +-
 src/libstore/derivations.hh           |  2 +-
 src/libstore/names.cc                 | 24 ++++----
 src/libstore/names.hh                 |  6 +-
 src/libutil/hash.cc                   |  2 +-
 src/libutil/hash.hh                   |  2 +-
 src/nix/prefetch.cc                   |  2 +-
 19 files changed, 94 insertions(+), 87 deletions(-)

diff --git a/src/libexpr/attr-path.cc b/src/libexpr/attr-path.cc
index c50c6d92b..edef4d9f8 100644
--- a/src/libexpr/attr-path.cc
+++ b/src/libexpr/attr-path.cc
@@ -121,7 +121,7 @@ Pos findPackageFilename(EvalState & state, Value & v, std::string what)
     std::string filename(pos, 0, colon);
     unsigned int lineno;
     try {
-        lineno = std::stoi(std::string(pos, colon + 1));
+        lineno = std::stoi(std::string(pos, colon + 1, string::npos));
     } catch (std::invalid_argument & e) {
         throw ParseError("cannot parse line number '%s'", pos);
     }
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index b884b4001..bfc5d3ebf 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -1857,7 +1857,7 @@ void EvalState::forceFunction(Value & v, const Pos & pos)
 }
 
 
-string EvalState::forceString(Value & v, const Pos & pos)
+std::string_view EvalState::forceString(Value & v, const Pos & pos)
 {
     forceValue(v, pos);
     if (v.type() != nString) {
@@ -1866,7 +1866,7 @@ string EvalState::forceString(Value & v, const Pos & pos)
         else
             throwTypeError("value is %1% while a string was expected", v);
     }
-    return string(v.string.s);
+    return v.string.s;
 }
 
 
@@ -1901,17 +1901,17 @@ std::vector<std::pair<Path, std::string>> Value::getContext()
 }
 
 
-string EvalState::forceString(Value & v, PathSet & context, const Pos & pos)
+std::string_view EvalState::forceString(Value & v, PathSet & context, const Pos & pos)
 {
-    string s = forceString(v, pos);
+    auto s = forceString(v, pos);
     copyContext(v, context);
     return s;
 }
 
 
-string EvalState::forceStringNoCtx(Value & v, const Pos & pos)
+std::string_view EvalState::forceStringNoCtx(Value & v, const Pos & pos)
 {
-    string s = forceString(v, pos);
+    auto s = forceString(v, pos);
     if (v.string.context) {
         if (pos)
             throwEvalError(pos, "the string '%1%' is not allowed to refer to a store path (such as '%2%')",
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 67bdd4de4..5b94a96ca 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -201,8 +201,8 @@ public:
     void resetFileCache();
 
     /* Look up a file in the search path. */
-    Path findFile(const string & path);
-    Path findFile(SearchPath & searchPath, const string & path, const Pos & pos = noPos);
+    Path findFile(const std::string_view path);
+    Path findFile(SearchPath & searchPath, const std::string_view path, const Pos & pos = noPos);
 
     /* If the specified search path element is a URI, download it. */
     std::pair<bool, std::string> resolveSearchPathElem(const SearchPathElem & elem);
@@ -236,9 +236,9 @@ public:
     inline void forceList(Value & v);
     inline void forceList(Value & v, const Pos & pos);
     void forceFunction(Value & v, const Pos & pos); // either lambda or primop
-    string forceString(Value & v, const Pos & pos = noPos);
-    string forceString(Value & v, PathSet & context, const Pos & pos = noPos);
-    string forceStringNoCtx(Value & v, const Pos & pos = noPos);
+    std::string_view forceString(Value & v, const Pos & pos = noPos);
+    std::string_view forceString(Value & v, PathSet & context, const Pos & pos = noPos);
+    std::string_view forceStringNoCtx(Value & v, const Pos & pos = noPos);
 
     /* Return true iff the value `v' denotes a derivation (i.e. a
        set with attribute `type = "derivation"'). */
diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 0fbe9b960..809f54cc0 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -250,7 +250,7 @@ static Flake getFlake(
         for (auto & setting : *nixConfig->value->attrs) {
             forceTrivialValue(state, *setting.value, *setting.pos);
             if (setting.value->type() == nString)
-                flake.config.settings.insert({setting.name, state.forceStringNoCtx(*setting.value, *setting.pos)});
+                flake.config.settings.insert({setting.name, string(state.forceStringNoCtx(*setting.value, *setting.pos))});
             else if (setting.value->type() == nPath) {
                 PathSet emptyContext = {};
                 flake.config.settings.insert({setting.name, state.coerceToString(*setting.pos, *setting.value, emptyContext, false, true, true)});
@@ -265,7 +265,7 @@ static Flake getFlake(
                     if (elem->type() != nString)
                         throw TypeError("list element in flake configuration setting '%s' is %s while a string is expected",
                             setting.name, showType(*setting.value));
-                    ss.push_back(state.forceStringNoCtx(*elem, *setting.pos));
+                    ss.emplace_back(state.forceStringNoCtx(*elem, *setting.pos));
                 }
                 flake.config.settings.insert({setting.name, ss});
             }
@@ -726,7 +726,7 @@ static void prim_getFlake(EvalState & state, const Pos & pos, Value * * args, Va
 {
     state.requireExperimentalFeatureOnEvaluation(Xp::Flakes, "builtins.getFlake", pos);
 
-    auto flakeRefS = state.forceStringNoCtx(*args[0], pos);
+    string flakeRefS(state.forceStringNoCtx(*args[0], pos));
     auto flakeRef = parseFlakeRef(flakeRefS, {}, true);
     if (evalSettings.pureEval && !flakeRef.input.isImmutable())
         throw Error("cannot call 'getFlake' on mutable flake reference '%s', at %s (use --impure to override)", flakeRefS, pos);
diff --git a/src/libexpr/get-drvs.cc b/src/libexpr/get-drvs.cc
index 25fd9b949..2651266b2 100644
--- a/src/libexpr/get-drvs.cc
+++ b/src/libexpr/get-drvs.cc
@@ -104,7 +104,7 @@ DrvInfo::Outputs DrvInfo::queryOutputs(bool onlyOutputsToInstall)
             /* For each output... */
             for (auto elem : i->value->listItems()) {
                 /* Evaluate the corresponding set. */
-                string name = state->forceStringNoCtx(*elem, *i->pos);
+                string name(state->forceStringNoCtx(*elem, *i->pos));
                 Bindings::iterator out = attrs->find(state->symbols.create(name));
                 if (out == attrs->end()) continue; // FIXME: throw error?
                 state->forceAttrs(*out->value);
diff --git a/src/libexpr/json-to-value.cc b/src/libexpr/json-to-value.cc
index 88716250c..99a475ff9 100644
--- a/src/libexpr/json-to-value.cc
+++ b/src/libexpr/json-to-value.cc
@@ -163,7 +163,7 @@ public:
     }
 };
 
-void parseJSON(EvalState & state, const string & s_, Value & v)
+void parseJSON(EvalState & state, const std::string_view & s_, Value & v)
 {
     JSONSax parser(state, v);
     bool res = json::sax_parse(s_, &parser);
diff --git a/src/libexpr/json-to-value.hh b/src/libexpr/json-to-value.hh
index 3b0fdae11..84bec4eba 100644
--- a/src/libexpr/json-to-value.hh
+++ b/src/libexpr/json-to-value.hh
@@ -8,6 +8,6 @@ namespace nix {
 
 MakeError(JSONParseError, EvalError);
 
-void parseJSON(EvalState & state, const string & s, Value & v);
+void parseJSON(EvalState & state, const std::string_view & s, Value & v);
 
 }
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index dd76fd66f..b7910da8c 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -709,24 +709,24 @@ void EvalState::addToSearchPath(const string & s)
 }
 
 
-Path EvalState::findFile(const string & path)
+Path EvalState::findFile(const std::string_view path)
 {
     return findFile(searchPath, path);
 }
 
 
-Path EvalState::findFile(SearchPath & searchPath, const string & path, const Pos & pos)
+Path EvalState::findFile(SearchPath & searchPath, const std::string_view path, const Pos & pos)
 {
     for (auto & i : searchPath) {
         std::string suffix;
         if (i.first.empty())
-            suffix = "/" + path;
+            suffix = concatStrings("/", path);
         else {
             auto s = i.first.size();
             if (path.compare(0, s, i.first) != 0 ||
                 (path.size() > s && path[s] != '/'))
                 continue;
-            suffix = path.size() == s ? "" : "/" + string(path, s);
+            suffix = path.size() == s ? "" : concatStrings("/", path.substr(s));
         }
         auto r = resolveSearchPathElem(i);
         if (!r.first) continue;
@@ -735,7 +735,7 @@ Path EvalState::findFile(SearchPath & searchPath, const string & path, const Pos
     }
 
     if (hasPrefix(path, "nix/"))
-        return corepkgsPrefix + path.substr(4);
+        return concatStrings(corepkgsPrefix, path.substr(4));
 
     throw ThrownError({
         .msg = hintfmt(evalSettings.pureEval
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index acee71d19..0454acc3d 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -314,7 +314,7 @@ void prim_importNative(EvalState & state, const Pos & pos, Value * * args, Value
 {
     auto path = realisePath(state, pos, *args[0]);
 
-    string sym = state.forceStringNoCtx(*args[1], pos);
+    string sym(state.forceStringNoCtx(*args[1], pos));
 
     void *handle = dlopen(path.c_str(), RTLD_LAZY | RTLD_LOCAL);
     if (!handle)
@@ -825,7 +825,7 @@ static RegisterPrimOp primop_tryEval({
 /* Return an environment variable.  Use with care. */
 static void prim_getEnv(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    string name = state.forceStringNoCtx(*args[0], pos);
+    string name(state.forceStringNoCtx(*args[0], pos));
     v.mkString(evalSettings.restrictEval || evalSettings.pureEval ? "" : getEnv(name).value_or(""));
 }
 
@@ -975,7 +975,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
         const string & key = i->name;
         vomit("processing attribute '%1%'", key);
 
-        auto handleHashMode = [&](const std::string & s) {
+        auto handleHashMode = [&](const std::string_view s) {
             if (s == "recursive") ingestionMethod = FileIngestionMethod::Recursive;
             else if (s == "flat") ingestionMethod = FileIngestionMethod::Flat;
             else
@@ -1502,7 +1502,7 @@ static void prim_findFile(EvalState & state, const Pos & pos, Value * * args, Va
         searchPath.emplace_back(prefix, path);
     }
 
-    string path = state.forceStringNoCtx(*args[1], pos);
+    auto path = state.forceStringNoCtx(*args[1], pos);
 
     v.mkPath(state.checkSourcePath(state.findFile(searchPath, path, pos)));
 }
@@ -1516,7 +1516,7 @@ static RegisterPrimOp primop_findFile(RegisterPrimOp::Info {
 /* Return the cryptographic hash of a file in base-16. */
 static void prim_hashFile(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    string type = state.forceStringNoCtx(*args[0], pos);
+    auto type = state.forceStringNoCtx(*args[0], pos);
     std::optional<HashType> ht = parseHashType(type);
     if (!ht)
         throw Error({
@@ -1723,7 +1723,7 @@ static RegisterPrimOp primop_toJSON({
 /* Parse a JSON string to a value. */
 static void prim_fromJSON(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    string s = state.forceStringNoCtx(*args[0], pos);
+    auto s = state.forceStringNoCtx(*args[0], pos);
     try {
         parseJSON(state, s, v);
     } catch (JSONParseError &e) {
@@ -1752,8 +1752,8 @@ static RegisterPrimOp primop_fromJSON({
 static void prim_toFile(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     PathSet context;
-    string name = state.forceStringNoCtx(*args[0], pos);
-    string contents = state.forceString(*args[1], context, pos);
+    string name(state.forceStringNoCtx(*args[0], pos));
+    string contents(state.forceString(*args[1], context, pos));
 
     StorePathSet refs;
 
@@ -2153,7 +2153,7 @@ static RegisterPrimOp primop_attrValues({
 /* Dynamic version of the `.' operator. */
 void prim_getAttr(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    string attr = state.forceStringNoCtx(*args[0], pos);
+    auto attr = state.forceStringNoCtx(*args[0], pos);
     state.forceAttrs(*args[1], pos);
     Bindings::iterator i = getAttr(
         state,
@@ -2183,7 +2183,7 @@ static RegisterPrimOp primop_getAttr({
 /* Return position information of the specified attribute. */
 static void prim_unsafeGetAttrPos(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    string attr = state.forceStringNoCtx(*args[0], pos);
+    auto attr = state.forceStringNoCtx(*args[0], pos);
     state.forceAttrs(*args[1], pos);
     Bindings::iterator i = args[1]->attrs->find(state.symbols.create(attr));
     if (i == args[1]->attrs->end())
@@ -2201,7 +2201,7 @@ static RegisterPrimOp primop_unsafeGetAttrPos(RegisterPrimOp::Info {
 /* Dynamic version of the `?' operator. */
 static void prim_hasAttr(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    string attr = state.forceStringNoCtx(*args[0], pos);
+    auto attr = state.forceStringNoCtx(*args[0], pos);
     state.forceAttrs(*args[1], pos);
     v.mkBool(args[1]->attrs->find(state.symbols.create(attr)) != args[1]->attrs->end());
 }
@@ -2300,7 +2300,7 @@ static void prim_listToAttrs(EvalState & state, const Pos & pos, Value * * args,
             pos
         );
 
-        string name = state.forceStringNoCtx(*j->value, *j->pos);
+        auto name = state.forceStringNoCtx(*j->value, *j->pos);
 
         Symbol sym = state.symbols.create(name);
         if (seen.insert(sym).second) {
@@ -3032,7 +3032,7 @@ static void prim_groupBy(EvalState & state, const Pos & pos, Value * * args, Val
     for (auto vElem : args[1]->listItems()) {
         Value res;
         state.callFunction(*args[0], *vElem, res, pos);
-        string name = state.forceStringNoCtx(res, pos);
+        auto name = state.forceStringNoCtx(res, pos);
         Symbol sym = state.symbols.create(name);
         auto vector = attrs.try_emplace(sym, ValueVector()).first;
         vector->second.push_back(vElem);
@@ -3376,7 +3376,7 @@ static RegisterPrimOp primop_stringLength({
 /* Return the cryptographic hash of a string in base-16. */
 static void prim_hashString(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    string type = state.forceStringNoCtx(*args[0], pos);
+    auto type = state.forceStringNoCtx(*args[0], pos);
     std::optional<HashType> ht = parseHashType(type);
     if (!ht)
         throw Error({
@@ -3385,7 +3385,7 @@ static void prim_hashString(EvalState & state, const Pos & pos, Value * * args,
         });
 
     PathSet context; // discarded
-    string s = state.forceString(*args[1], context, pos);
+    auto s = state.forceString(*args[1], context, pos);
 
     v.mkString(hashString(*ht, s).to_string(Base16, false));
 }
@@ -3403,7 +3403,18 @@ static RegisterPrimOp primop_hashString({
 
 struct RegexCache
 {
-    std::unordered_map<std::string, std::regex> cache;
+    // TODO use C++20 transparent comparison when available
+    std::unordered_map<std::string_view, std::regex> cache;
+    std::list<std::string> keys;
+
+    std::regex get(std::string_view re)
+    {
+        auto it = cache.find(re);
+        if (it != cache.end())
+            return it->second;
+        keys.emplace_back(re);
+        return cache.emplace(keys.back(), std::regex(keys.back(), std::regex::extended)).first->second;
+    }
 };
 
 std::shared_ptr<RegexCache> makeRegexCache()
@@ -3417,15 +3428,13 @@ void prim_match(EvalState & state, const Pos & pos, Value * * args, Value & v)
 
     try {
 
-        auto regex = state.regexCache->cache.find(re);
-        if (regex == state.regexCache->cache.end())
-            regex = state.regexCache->cache.emplace(re, std::regex(re, std::regex::extended)).first;
+        auto regex = state.regexCache->get(re);
 
         PathSet context;
-        const std::string str = state.forceString(*args[1], context, pos);
+        const auto str = state.forceString(*args[1], context, pos);
 
-        std::smatch match;
-        if (!std::regex_match(str, match, regex->second)) {
+        std::cmatch match;
+        if (!std::regex_match(str.begin(), str.end(), match, regex)) {
             v.mkNull();
             return;
         }
@@ -3500,15 +3509,13 @@ void prim_split(EvalState & state, const Pos & pos, Value * * args, Value & v)
 
     try {
 
-        auto regex = state.regexCache->cache.find(re);
-        if (regex == state.regexCache->cache.end())
-            regex = state.regexCache->cache.emplace(re, std::regex(re, std::regex::extended)).first;
+        auto regex = state.regexCache->get(re);
 
         PathSet context;
-        const std::string str = state.forceString(*args[1], context, pos);
+        const auto str = state.forceString(*args[1], context, pos);
 
-        auto begin = std::sregex_iterator(str.begin(), str.end(), regex->second);
-        auto end = std::sregex_iterator();
+        auto begin = std::cregex_iterator(str.begin(), str.end(), regex);
+        auto end = std::cregex_iterator();
 
         // Any matches results are surrounded by non-matching results.
         const size_t len = std::distance(begin, end);
@@ -3520,9 +3527,9 @@ void prim_split(EvalState & state, const Pos & pos, Value * * args, Value & v)
             return;
         }
 
-        for (std::sregex_iterator i = begin; i != end; ++i) {
+        for (auto i = begin; i != end; ++i) {
             assert(idx <= 2 * len + 1 - 3);
-            std::smatch match = *i;
+            auto match = *i;
 
             // Add a string for non-matched characters.
             (v.listElems()[idx++] = state.allocValue())->mkString(match.prefix().str());
@@ -3643,14 +3650,14 @@ static void prim_replaceStrings(EvalState & state, const Pos & pos, Value * * ar
     vector<string> from;
     from.reserve(args[0]->listSize());
     for (auto elem : args[0]->listItems())
-        from.push_back(state.forceString(*elem, pos));
+        from.emplace_back(state.forceString(*elem, pos));
 
     vector<std::pair<string, PathSet>> to;
     to.reserve(args[1]->listSize());
     for (auto elem : args[1]->listItems()) {
         PathSet ctx;
         auto s = state.forceString(*elem, ctx, pos);
-        to.push_back(std::make_pair(std::move(s), std::move(ctx)));
+        to.emplace_back(s, std::move(ctx));
     }
 
     PathSet context;
@@ -3712,7 +3719,7 @@ static RegisterPrimOp primop_replaceStrings({
 
 static void prim_parseDrvName(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    string name = state.forceStringNoCtx(*args[0], pos);
+    auto name = state.forceStringNoCtx(*args[0], pos);
     DrvName parsed(name);
     auto attrs = state.buildBindings(2);
     attrs.alloc(state.sName).mkString(parsed.name);
@@ -3736,8 +3743,8 @@ static RegisterPrimOp primop_parseDrvName({
 
 static void prim_compareVersions(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    string version1 = state.forceStringNoCtx(*args[0], pos);
-    string version2 = state.forceStringNoCtx(*args[1], pos);
+    auto version1 = state.forceStringNoCtx(*args[0], pos);
+    auto version2 = state.forceStringNoCtx(*args[1], pos);
     v.mkInt(compareVersions(version1, version2));
 }
 
@@ -3756,14 +3763,14 @@ static RegisterPrimOp primop_compareVersions({
 
 static void prim_splitVersion(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    string version = state.forceStringNoCtx(*args[0], pos);
+    auto version = state.forceStringNoCtx(*args[0], pos);
     auto iter = version.cbegin();
     Strings components;
     while (iter != version.cend()) {
         auto component = nextComponent(iter, version.cend());
         if (component.empty())
             break;
-        components.emplace_back(std::move(component));
+        components.emplace_back(component);
     }
     state.mkList(v, components.size());
     for (const auto & [n, component] : enumerate(components))
diff --git a/src/libexpr/primops/context.cc b/src/libexpr/primops/context.cc
index a239c06da..cd7eeb588 100644
--- a/src/libexpr/primops/context.cc
+++ b/src/libexpr/primops/context.cc
@@ -180,7 +180,7 @@ static void prim_appendContext(EvalState & state, const Pos & pos, Value * * arg
             }
             for (auto elem : iter->value->listItems()) {
                 auto name = state.forceStringNoCtx(*elem, *iter->pos);
-                context.insert("!" + name + "!" + string(i.name));
+                context.insert(concatStrings("!", name, "!", i.name));
             }
         }
     }
diff --git a/src/libexpr/primops/fetchMercurial.cc b/src/libexpr/primops/fetchMercurial.cc
index 42214c207..f808e2da5 100644
--- a/src/libexpr/primops/fetchMercurial.cc
+++ b/src/libexpr/primops/fetchMercurial.cc
@@ -12,7 +12,7 @@ static void prim_fetchMercurial(EvalState & state, const Pos & pos, Value * * ar
     std::string url;
     std::optional<Hash> rev;
     std::optional<std::string> ref;
-    std::string name = "source";
+    std::string_view name = "source";
     PathSet context;
 
     state.forceValue(*args[0], pos);
@@ -22,14 +22,14 @@ static void prim_fetchMercurial(EvalState & state, const Pos & pos, Value * * ar
         state.forceAttrs(*args[0], pos);
 
         for (auto & attr : *args[0]->attrs) {
-            string n(attr.name);
+            std::string_view n(attr.name);
             if (n == "url")
                 url = state.coerceToString(*attr.pos, *attr.value, context, false, false);
             else if (n == "rev") {
                 // Ugly: unlike fetchGit, here the "rev" attribute can
                 // be both a revision or a branch/tag name.
                 auto value = state.forceStringNoCtx(*attr.value, *attr.pos);
-                if (std::regex_match(value, revRegex))
+                if (std::regex_match(value.begin(), value.end(), revRegex))
                     rev = Hash::parseAny(value, htSHA1);
                 else
                     ref = value;
@@ -62,7 +62,7 @@ static void prim_fetchMercurial(EvalState & state, const Pos & pos, Value * * ar
     fetchers::Attrs attrs;
     attrs.insert_or_assign("type", "hg");
     attrs.insert_or_assign("url", url.find("://") != std::string::npos ? url : "file://" + url);
-    attrs.insert_or_assign("name", name);
+    attrs.insert_or_assign("name", string(name));
     if (ref) attrs.insert_or_assign("ref", *ref);
     if (rev) attrs.insert_or_assign("rev", rev->gitRev());
     auto input = fetchers::Input::fromAttrs(std::move(attrs));
diff --git a/src/libexpr/primops/fromTOML.cc b/src/libexpr/primops/fromTOML.cc
index 80c7e0b82..c0e858b61 100644
--- a/src/libexpr/primops/fromTOML.cc
+++ b/src/libexpr/primops/fromTOML.cc
@@ -9,7 +9,7 @@ static void prim_fromTOML(EvalState & state, const Pos & pos, Value * * args, Va
 {
     auto toml = state.forceStringNoCtx(*args[0], pos);
 
-    std::istringstream tomlStream(toml);
+    std::istringstream tomlStream(string{toml});
 
     std::function<void(Value &, toml::value)> visit;
 
diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index 3e3d50144..40af6a775 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -699,10 +699,10 @@ void writeDerivation(Sink & out, const Store & store, const BasicDerivation & dr
 }
 
 
-std::string hashPlaceholder(const std::string & outputName)
+std::string hashPlaceholder(const std::string_view outputName)
 {
     // FIXME: memoize?
-    return "/" + hashString(htSHA256, "nix-output:" + outputName).to_string(Base32, false);
+    return "/" + hashString(htSHA256, concatStrings("nix-output:", outputName)).to_string(Base32, false);
 }
 
 std::string downstreamPlaceholder(const Store & store, const StorePath & drvPath, std::string_view outputName)
diff --git a/src/libstore/derivations.hh b/src/libstore/derivations.hh
index b1cb68194..a644cec60 100644
--- a/src/libstore/derivations.hh
+++ b/src/libstore/derivations.hh
@@ -236,7 +236,7 @@ void writeDerivation(Sink & out, const Store & store, const BasicDerivation & dr
    It is used as a placeholder to allow derivations to refer to their
    own outputs without needing to use the hash of a derivation in
    itself, making the hash near-impossible to calculate. */
-std::string hashPlaceholder(const std::string & outputName);
+std::string hashPlaceholder(const std::string_view outputName);
 
 /* This creates an opaque and almost certainly unique string
    deterministically from a derivation path and output name.
diff --git a/src/libstore/names.cc b/src/libstore/names.cc
index 54c95055d..277aabf0f 100644
--- a/src/libstore/names.cc
+++ b/src/libstore/names.cc
@@ -56,8 +56,8 @@ bool DrvName::matches(const DrvName & n)
 }
 
 
-string nextComponent(string::const_iterator & p,
-    const string::const_iterator end)
+std::string_view nextComponent(std::string_view::const_iterator & p,
+    const std::string_view::const_iterator end)
 {
     /* Skip any dots and dashes (component separators). */
     while (p != end && (*p == '.' || *p == '-')) ++p;
@@ -67,18 +67,18 @@ string nextComponent(string::const_iterator & p,
     /* If the first character is a digit, consume the longest sequence
        of digits.  Otherwise, consume the longest sequence of
        non-digit, non-separator characters. */
-    string s;
+    auto s = p;
     if (isdigit(*p))
-        while (p != end && isdigit(*p)) s += *p++;
+        while (p != end && isdigit(*p)) p++;
     else
         while (p != end && (!isdigit(*p) && *p != '.' && *p != '-'))
-            s += *p++;
+            p++;
 
-    return s;
+    return {s, size_t(p - s)};
 }
 
 
-static bool componentsLT(const string & c1, const string & c2)
+static bool componentsLT(const std::string_view c1, const std::string_view c2)
 {
     auto n1 = string2Int<int>(c1);
     auto n2 = string2Int<int>(c2);
@@ -94,14 +94,14 @@ static bool componentsLT(const string & c1, const string & c2)
 }
 
 
-int compareVersions(const string & v1, const string & v2)
+int compareVersions(const std::string_view v1, const std::string_view v2)
 {
-    string::const_iterator p1 = v1.begin();
-    string::const_iterator p2 = v2.begin();
+    auto p1 = v1.begin();
+    auto p2 = v2.begin();
 
     while (p1 != v1.end() || p2 != v2.end()) {
-        string c1 = nextComponent(p1, v1.end());
-        string c2 = nextComponent(p2, v2.end());
+        auto c1 = nextComponent(p1, v1.end());
+        auto c2 = nextComponent(p2, v2.end());
         if (componentsLT(c1, c2)) return -1;
         else if (componentsLT(c2, c1)) return 1;
     }
diff --git a/src/libstore/names.hh b/src/libstore/names.hh
index 3f861bc44..6f01fe2a1 100644
--- a/src/libstore/names.hh
+++ b/src/libstore/names.hh
@@ -27,9 +27,9 @@ private:
 
 typedef list<DrvName> DrvNames;
 
-string nextComponent(string::const_iterator & p,
-    const string::const_iterator end);
-int compareVersions(const string & v1, const string & v2);
+std::string_view nextComponent(std::string_view::const_iterator & p,
+    const std::string_view::const_iterator end);
+int compareVersions(const std::string_view v1, const std::string_view v2);
 DrvNames drvNamesFromArgs(const Strings & opArgs);
 
 }
diff --git a/src/libutil/hash.cc b/src/libutil/hash.cc
index 4df8b4ecb..6ed00d43c 100644
--- a/src/libutil/hash.cc
+++ b/src/libutil/hash.cc
@@ -259,7 +259,7 @@ Hash::Hash(std::string_view rest, HashType type, bool isSRI)
         throw BadHash("hash '%s' has wrong length for hash type '%s'", rest, printHashType(this->type));
 }
 
-Hash newHashAllowEmpty(std::string hashStr, std::optional<HashType> ht)
+Hash newHashAllowEmpty(std::string_view hashStr, std::optional<HashType> ht)
 {
     if (hashStr.empty()) {
         if (!ht)
diff --git a/src/libutil/hash.hh b/src/libutil/hash.hh
index 1b626dd85..dff46542f 100644
--- a/src/libutil/hash.hh
+++ b/src/libutil/hash.hh
@@ -107,7 +107,7 @@ public:
 };
 
 /* Helper that defaults empty hashes to the 0 hash. */
-Hash newHashAllowEmpty(std::string hashStr, std::optional<HashType> ht);
+Hash newHashAllowEmpty(std::string_view hashStr, std::optional<HashType> ht);
 
 /* Print a hash in base-16 if it's MD5, or base-32 otherwise. */
 string printHash16or32(const Hash & hash);
diff --git a/src/nix/prefetch.cc b/src/nix/prefetch.cc
index 768d37595..669be0709 100644
--- a/src/nix/prefetch.cc
+++ b/src/nix/prefetch.cc
@@ -38,7 +38,7 @@ string resolveMirrorUrl(EvalState & state, string url)
     if (mirrorList->value->listSize() < 1)
         throw Error("mirror URL '%s' did not expand to anything", url);
 
-    auto mirror = state.forceString(*mirrorList->value->listElems()[0]);
+    string mirror(state.forceString(*mirrorList->value->listElems()[0]));
     return mirror + (hasSuffix(mirror, "/") ? "" : "/") + string(s, p + 1);
 }
 

From d439dceb3bc47f10a6f1f5b8cf4a5b17adc80071 Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Fri, 21 Jan 2022 16:20:54 +0100
Subject: [PATCH 497/567] optionally return string_view from coerceToString

we'll retain the old coerceToString interface that returns a string, but callers
that don't need the returned value to outlive the Value it came from can save
copies by using the new interface instead. for values that weren't stringy we'll
pass a new buffer argument that'll be used for storage and shouldn't be
inspected.
---
 src/libexpr/eval.cc                   | 48 +++++++++++----------
 src/libexpr/eval.hh                   |  3 +-
 src/libexpr/flake/flake.cc            |  4 +-
 src/libexpr/primops.cc                | 38 +++++++++--------
 src/libexpr/primops/context.cc        |  7 ++--
 src/libexpr/primops/fetchMercurial.cc |  4 +-
 src/libexpr/primops/fetchTree.cc      |  4 +-
 src/libutil/types.hh                  | 60 +++++++++++++++++++++++++++
 src/nix/eval.cc                       |  2 +-
 src/nix/repl.cc                       |  2 +-
 10 files changed, 121 insertions(+), 51 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index bfc5d3ebf..3332dd703 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -1,5 +1,6 @@
 #include "eval.hh"
 #include "hash.hh"
+#include "types.hh"
 #include "util.hh"
 #include "store-api.hh"
 #include "derivations.hh"
@@ -1694,7 +1695,7 @@ void EvalState::concatLists(Value & v, size_t nrLists, Value * * lists, const Po
 void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
 {
     PathSet context;
-    std::vector<std::string> s;
+    std::vector<BackedStringView> s;
     size_t sSize = 0;
     NixInt n = 0;
     NixFloat nf = 0;
@@ -1705,7 +1706,7 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
     const auto str = [&] {
         std::string result;
         result.reserve(sSize);
-        for (const auto & part : s) result += part;
+        for (const auto & part : s) result += *part;
         return result;
     };
     /* c_str() is not str().c_str() because we want to create a string
@@ -1715,15 +1716,18 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
         char * result = allocString(sSize + 1);
         char * tmp = result;
         for (const auto & part : s) {
-            memcpy(tmp, part.c_str(), part.size());
-            tmp += part.size();
+            memcpy(tmp, part->data(), part->size());
+            tmp += part->size();
         }
         *tmp = 0;
         return result;
     };
 
+    Value values[es->size()];
+    Value * vTmpP = values;
+
     for (auto & [i_pos, i] : *es) {
-        Value vTmp;
+        Value & vTmp = *vTmpP++;
         i->eval(state, env, vTmp);
 
         /* If the first element is a path, then the result will also
@@ -1756,9 +1760,9 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
             /* skip canonization of first path, which would only be not
             canonized in the first place if it's coming from a ./${foo} type
             path */
-            s.emplace_back(
-                state.coerceToString(i_pos, vTmp, context, false, firstType == nString, !first));
-            sSize += s.back().size();
+            auto part = state.coerceToString(i_pos, vTmp, context, false, firstType == nString, !first);
+            sSize += part->size();
+            s.emplace_back(std::move(part));
         }
 
         first = false;
@@ -1942,34 +1946,35 @@ std::optional<string> EvalState::tryAttrsToString(const Pos & pos, Value & v,
     if (i != v.attrs->end()) {
         Value v1;
         callFunction(*i->value, v, v1, pos);
-        return coerceToString(pos, v1, context, coerceMore, copyToStore);
+        return coerceToString(pos, v1, context, coerceMore, copyToStore).toOwned();
     }
 
     return {};
 }
 
-string EvalState::coerceToString(const Pos & pos, Value & v, PathSet & context,
+BackedStringView EvalState::coerceToString(const Pos & pos, Value & v, PathSet & context,
     bool coerceMore, bool copyToStore, bool canonicalizePath)
 {
     forceValue(v, pos);
 
-    string s;
-
     if (v.type() == nString) {
         copyContext(v, context);
-        return v.string.s;
+        return std::string_view(v.string.s);
     }
 
     if (v.type() == nPath) {
-        Path path(canonicalizePath ? canonPath(v.path) : v.path);
-        return copyToStore ? copyPathToStore(context, path) : path;
+        BackedStringView path(PathView(v.path));
+        if (canonicalizePath)
+            path = canonPath(*path);
+        if (copyToStore)
+            path = copyPathToStore(context, std::move(path).toOwned());
+        return path;
     }
 
     if (v.type() == nAttrs) {
         auto maybeString = tryAttrsToString(pos, v, context, coerceMore, copyToStore);
-        if (maybeString) {
-            return *maybeString;
-        }
+        if (maybeString)
+            return std::move(*maybeString);
         auto i = v.attrs->find(sOutPath);
         if (i == v.attrs->end()) throwTypeError(pos, "cannot coerce a set to a string");
         return coerceToString(pos, *i->value, context, coerceMore, copyToStore);
@@ -1991,14 +1996,13 @@ string EvalState::coerceToString(const Pos & pos, Value & v, PathSet & context,
         if (v.isList()) {
             string result;
             for (auto [n, v2] : enumerate(v.listItems())) {
-                result += coerceToString(pos, *v2,
-                    context, coerceMore, copyToStore);
+                result += *coerceToString(pos, *v2, context, coerceMore, copyToStore);
                 if (n < v.listSize() - 1
                     /* !!! not quite correct */
                     && (!v2->isList() || v2->listSize() != 0))
                     result += " ";
             }
-            return result;
+            return std::move(result);
         }
     }
 
@@ -2032,7 +2036,7 @@ string EvalState::copyPathToStore(PathSet & context, const Path & path)
 
 Path EvalState::coerceToPath(const Pos & pos, Value & v, PathSet & context)
 {
-    string path = coerceToString(pos, v, context, false, false);
+    string path = coerceToString(pos, v, context, false, false).toOwned();
     if (path == "" || path[0] != '/')
         throwEvalError(pos, "string '%1%' doesn't represent an absolute path", path);
     return path;
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 5b94a96ca..04acc5728 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "attr-set.hh"
+#include "types.hh"
 #include "value.hh"
 #include "nixexpr.hh"
 #include "symbol-table.hh"
@@ -251,7 +252,7 @@ public:
        string.  If `coerceMore' is set, also converts nulls, integers,
        booleans and lists to a string.  If `copyToStore' is set,
        referenced paths are copied to the Nix store as a side effect. */
-    string coerceToString(const Pos & pos, Value & v, PathSet & context,
+    BackedStringView coerceToString(const Pos & pos, Value & v, PathSet & context,
         bool coerceMore = false, bool copyToStore = true,
         bool canonicalizePath = true);
 
diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 809f54cc0..27ba3288b 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -253,7 +253,9 @@ static Flake getFlake(
                 flake.config.settings.insert({setting.name, string(state.forceStringNoCtx(*setting.value, *setting.pos))});
             else if (setting.value->type() == nPath) {
                 PathSet emptyContext = {};
-                flake.config.settings.insert({setting.name, state.coerceToString(*setting.pos, *setting.value, emptyContext, false, true, true)});
+                flake.config.settings.emplace(
+                    setting.name,
+                    state.coerceToString(*setting.pos, *setting.value, emptyContext, false, true, true) .toOwned());
             }
             else if (setting.value->type() == nInt)
                 flake.config.settings.insert({setting.name, state.forceInt(*setting.value, *setting.pos)});
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 0454acc3d..b07133d5e 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -350,10 +350,11 @@ void prim_exec(EvalState & state, const Pos & pos, Value * * args, Value & v)
         });
     }
     PathSet context;
-    auto program = state.coerceToString(pos, *elems[0], context, false, false);
+    auto program = state.coerceToString(pos, *elems[0], context, false, false).toOwned();
     Strings commandArgs;
-    for (unsigned int i = 1; i < args[0]->listSize(); ++i)
-        commandArgs.emplace_back(state.coerceToString(pos, *elems[i], context, false, false));
+    for (unsigned int i = 1; i < args[0]->listSize(); ++i) {
+        commandArgs.push_back(state.coerceToString(pos, *elems[i], context, false, false).toOwned());
+    }
     try {
         auto _ = state.realiseContext(context); // FIXME: Handle CA derivations
     } catch (InvalidPathError & e) {
@@ -706,7 +707,7 @@ static RegisterPrimOp primop_abort({
     .fun = [](EvalState & state, const Pos & pos, Value * * args, Value & v)
     {
         PathSet context;
-        string s = state.coerceToString(pos, *args[0], context);
+        string s = state.coerceToString(pos, *args[0], context).toOwned();
         throw Abort("evaluation aborted with the following error message: '%1%'", s);
     }
 });
@@ -724,7 +725,7 @@ static RegisterPrimOp primop_throw({
     .fun = [](EvalState & state, const Pos & pos, Value * * args, Value & v)
     {
       PathSet context;
-      string s = state.coerceToString(pos, *args[0], context);
+      string s = state.coerceToString(pos, *args[0], context).toOwned();
       throw ThrownError(s);
     }
 });
@@ -736,7 +737,7 @@ static void prim_addErrorContext(EvalState & state, const Pos & pos, Value * * a
         v = *args[1];
     } catch (Error & e) {
         PathSet context;
-        e.addTrace(std::nullopt, state.coerceToString(pos, *args[0], context));
+        e.addTrace(std::nullopt, state.coerceToString(pos, *args[0], context).toOwned());
         throw;
     }
 }
@@ -1030,7 +1031,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
             else if (i->name == state.sArgs) {
                 state.forceList(*i->value, pos);
                 for (auto elem : i->value->listItems()) {
-                    string s = state.coerceToString(posDrvName, *elem, context, true);
+                    string s = state.coerceToString(posDrvName, *elem, context, true).toOwned();
                     drv.args.push_back(s);
                 }
             }
@@ -1066,7 +1067,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
                     }
 
                 } else {
-                    auto s = state.coerceToString(*i->pos, *i->value, context, true);
+                    auto s = state.coerceToString(*i->pos, *i->value, context, true).toOwned();
                     drv.env.emplace(key, s);
                     if (i->name == state.sBuilder) drv.builder = std::move(s);
                     else if (i->name == state.sSystem) drv.platform = std::move(s);
@@ -1399,7 +1400,7 @@ static RegisterPrimOp primop_pathExists({
 static void prim_baseNameOf(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     PathSet context;
-    v.mkString(baseNameOf(state.coerceToString(pos, *args[0], context, false, false)), context);
+    v.mkString(baseNameOf(*state.coerceToString(pos, *args[0], context, false, false)), context);
 }
 
 static RegisterPrimOp primop_baseNameOf({
@@ -1419,7 +1420,8 @@ static RegisterPrimOp primop_baseNameOf({
 static void prim_dirOf(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     PathSet context;
-    Path dir = dirOf(state.coerceToString(pos, *args[0], context, false, false));
+    auto path = state.coerceToString(pos, *args[0], context, false, false);
+    auto dir = dirOf(*path);
     if (args[0]->type() == nPath) v.mkPath(dir); else v.mkString(dir, context);
 }
 
@@ -1486,7 +1488,7 @@ static void prim_findFile(EvalState & state, const Pos & pos, Value * * args, Va
         );
 
         PathSet context;
-        string path = state.coerceToString(pos, *i->value, context, false, false);
+        string path = state.coerceToString(pos, *i->value, context, false, false).toOwned();
 
         try {
             auto rewrites = state.realiseContext(context);
@@ -3288,8 +3290,8 @@ static RegisterPrimOp primop_lessThan({
 static void prim_toString(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     PathSet context;
-    string s = state.coerceToString(pos, *args[0], context, true, false);
-    v.mkString(s, context);
+    auto s = state.coerceToString(pos, *args[0], context, true, false);
+    v.mkString(*s, context);
 }
 
 static RegisterPrimOp primop_toString({
@@ -3325,7 +3327,7 @@ static void prim_substring(EvalState & state, const Pos & pos, Value * * args, V
     int start = state.forceInt(*args[0], pos);
     int len = state.forceInt(*args[1], pos);
     PathSet context;
-    string s = state.coerceToString(pos, *args[2], context);
+    auto s = state.coerceToString(pos, *args[2], context);
 
     if (start < 0)
         throw EvalError({
@@ -3333,7 +3335,7 @@ static void prim_substring(EvalState & state, const Pos & pos, Value * * args, V
             .errPos = pos
         });
 
-    v.mkString((unsigned int) start >= s.size() ? "" : string(s, start, len), context);
+    v.mkString((unsigned int) start >= s->size() ? "" : s->substr(start, len), context);
 }
 
 static RegisterPrimOp primop_substring({
@@ -3359,8 +3361,8 @@ static RegisterPrimOp primop_substring({
 static void prim_stringLength(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     PathSet context;
-    string s = state.coerceToString(pos, *args[0], context);
-    v.mkInt(s.size());
+    auto s = state.coerceToString(pos, *args[0], context);
+    v.mkInt(s->size());
 }
 
 static RegisterPrimOp primop_stringLength({
@@ -3620,7 +3622,7 @@ static void prim_concatStringsSep(EvalState & state, const Pos & pos, Value * *
 
     for (auto elem : args[1]->listItems()) {
         if (first) first = false; else res += sep;
-        res += state.coerceToString(pos, *elem, context);
+        res += *state.coerceToString(pos, *elem, context);
     }
 
     v.mkString(res, context);
diff --git a/src/libexpr/primops/context.cc b/src/libexpr/primops/context.cc
index cd7eeb588..654251c23 100644
--- a/src/libexpr/primops/context.cc
+++ b/src/libexpr/primops/context.cc
@@ -7,7 +7,8 @@ namespace nix {
 static void prim_unsafeDiscardStringContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     PathSet context;
-    v.mkString(state.coerceToString(pos, *args[0], context));
+    auto s = state.coerceToString(pos, *args[0], context);
+    v.mkString(*s);
 }
 
 static RegisterPrimOp primop_unsafeDiscardStringContext("__unsafeDiscardStringContext", 1, prim_unsafeDiscardStringContext);
@@ -32,13 +33,13 @@ static RegisterPrimOp primop_hasContext("__hasContext", 1, prim_hasContext);
 static void prim_unsafeDiscardOutputDependency(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     PathSet context;
-    string s = state.coerceToString(pos, *args[0], context);
+    auto s = state.coerceToString(pos, *args[0], context);
 
     PathSet context2;
     for (auto & p : context)
         context2.insert(p.at(0) == '=' ? string(p, 1) : p);
 
-    v.mkString(s, context2);
+    v.mkString(*s, context2);
 }
 
 static RegisterPrimOp primop_unsafeDiscardOutputDependency("__unsafeDiscardOutputDependency", 1, prim_unsafeDiscardOutputDependency);
diff --git a/src/libexpr/primops/fetchMercurial.cc b/src/libexpr/primops/fetchMercurial.cc
index f808e2da5..c4e1a7bf0 100644
--- a/src/libexpr/primops/fetchMercurial.cc
+++ b/src/libexpr/primops/fetchMercurial.cc
@@ -24,7 +24,7 @@ static void prim_fetchMercurial(EvalState & state, const Pos & pos, Value * * ar
         for (auto & attr : *args[0]->attrs) {
             std::string_view n(attr.name);
             if (n == "url")
-                url = state.coerceToString(*attr.pos, *attr.value, context, false, false);
+                url = state.coerceToString(*attr.pos, *attr.value, context, false, false).toOwned();
             else if (n == "rev") {
                 // Ugly: unlike fetchGit, here the "rev" attribute can
                 // be both a revision or a branch/tag name.
@@ -50,7 +50,7 @@ static void prim_fetchMercurial(EvalState & state, const Pos & pos, Value * * ar
             });
 
     } else
-        url = state.coerceToString(pos, *args[0], context, false, false);
+        url = state.coerceToString(pos, *args[0], context, false, false).toOwned();
 
     // FIXME: git externals probably can be used to bypass the URI
     // whitelist. Ah well.
diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index 6647bd35c..d09e2d9e1 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -125,7 +125,7 @@ static void fetchTree(
             if (attr.name == state.sType) continue;
             state.forceValue(*attr.value, *attr.pos);
             if (attr.value->type() == nPath || attr.value->type() == nString) {
-                auto s = state.coerceToString(*attr.pos, *attr.value, context, false, false);
+                auto s = state.coerceToString(*attr.pos, *attr.value, context, false, false).toOwned();
                 attrs.emplace(attr.name,
                     attr.name == "url"
                     ? type == "git"
@@ -151,7 +151,7 @@ static void fetchTree(
 
         input = fetchers::Input::fromAttrs(std::move(attrs));
     } else {
-        auto url = state.coerceToString(pos, *args[0], context, false, false);
+        auto url = state.coerceToString(pos, *args[0], context, false, false).toOwned();
 
         if (type == "git") {
             fetchers::Attrs attrs;
diff --git a/src/libutil/types.hh b/src/libutil/types.hh
index 8f72c926f..e3aca20c9 100644
--- a/src/libutil/types.hh
+++ b/src/libutil/types.hh
@@ -6,6 +6,7 @@
 #include <set>
 #include <string>
 #include <map>
+#include <variant>
 #include <vector>
 
 namespace nix {
@@ -47,4 +48,63 @@ struct Explicit {
     }
 };
 
+
+/* This wants to be a little bit like rust's Cow type.
+   Some parts of the evaluator benefit greatly from being able to reuse
+   existing allocations for strings, but have to be able to also use
+   newly allocated storage for values.
+
+   We do not define implicit conversions, even with ref qualifiers,
+   since those can easily become ambiguous to the reader and can degrade
+   into copying behaviour we want to avoid. */
+class BackedStringView {
+private:
+    std::variant<std::string, std::string_view> data;
+
+    /* Needed to introduce a temporary since operator-> must return
+       a pointer. Without this we'd need to store the view object
+       even when we already own a string. */
+    class Ptr {
+    private:
+        std::string_view view;
+    public:
+        Ptr(std::string_view view): view(view) {}
+        const std::string_view * operator->() const { return &view; }
+    };
+
+public:
+    BackedStringView(std::string && s): data(std::move(s)) {}
+    BackedStringView(std::string_view sv): data(sv) {}
+    template<size_t N>
+    BackedStringView(const char (& lit)[N]): data(std::string_view(lit)) {}
+
+    BackedStringView(const BackedStringView &) = delete;
+    BackedStringView & operator=(const BackedStringView &) = delete;
+
+    /* We only want move operations defined since the sole purpose of
+       this type is to avoid copies. */
+    BackedStringView(BackedStringView && other) = default;
+    BackedStringView & operator=(BackedStringView && other) = default;
+
+    bool isOwned() const
+    {
+        return std::holds_alternative<std::string>(data);
+    }
+
+    std::string toOwned() &&
+    {
+        return isOwned()
+            ? std::move(std::get<std::string>(data))
+            : std::string(std::get<std::string_view>(data));
+    }
+
+    std::string_view operator*() const
+    {
+        return isOwned()
+            ? std::get<std::string>(data)
+            : std::get<std::string_view>(data);
+    }
+    Ptr operator->() const { return Ptr(**this); }
+};
+
 }
diff --git a/src/nix/eval.cc b/src/nix/eval.cc
index c7517cf79..c0435461f 100644
--- a/src/nix/eval.cc
+++ b/src/nix/eval.cc
@@ -107,7 +107,7 @@ struct CmdEval : MixJSON, InstallableCommand
 
         else if (raw) {
             stopProgressBar();
-            std::cout << state->coerceToString(noPos, *v, context);
+            std::cout << *state->coerceToString(noPos, *v, context);
         }
 
         else if (json) {
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index be9f96836..2d983e98e 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -463,7 +463,7 @@ bool NixRepl::processLine(string line)
         if (v.type() == nPath || v.type() == nString) {
             PathSet context;
             auto filename = state->coerceToString(noPos, v, context);
-            pos.file = state->symbols.create(filename);
+            pos.file = state->symbols.create(*filename);
         } else if (v.isLambda()) {
             pos = v.lambda.fun->pos;
         } else {

From 4bf6af7b555033de5c1d6851edb60a91940d43c3 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 28 Jan 2022 15:10:43 +0100
Subject: [PATCH 498/567] Remove a repeated std::move in a for loop

---
 src/libexpr/primops.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index acee71d19..b53425510 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1179,7 +1179,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
             drv.outputs.insert_or_assign(i, DerivationOutput {
                 .output = DerivationOutputCAFloating {
                     .method = ingestionMethod,
-                    .hashType = std::move(ht),
+                    .hashType = ht,
                 },
             });
         }

From 4ebc50d92e65e7fd9cf30fb84a0c39a13475a31f Mon Sep 17 00:00:00 2001
From: Tom Bereknyei <tomberek@gmail.com>
Date: Fri, 28 Jan 2022 09:56:58 -0500
Subject: [PATCH 499/567] bundler: revert default behavior to use defaultApp

Bundlers are now responsible for correctly handling their inputs which
are no longer constrained to be (Drv->Drv)->Drv->Drv, but can be of
type (attrset->Drv)->attrset->Drv.
---
 src/nix/bundle.cc      | 11 ++++++++---
 tests/flake-bundler.sh |  9 ++++++++-
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/src/nix/bundle.cc b/src/nix/bundle.cc
index 3d953ebc0..113ceca33 100644
--- a/src/nix/bundle.cc
+++ b/src/nix/bundle.cc
@@ -51,7 +51,9 @@ struct CmdBundle : InstallableCommand
 
     Strings getDefaultFlakeAttrPaths() override
     {
-        Strings res{"defaultPackage." + settings.thisSystem.get()};
+        Strings res{
+            "defaultApp." + settings.thisSystem.get()
+        };
         for (auto & s : SourceExprCommand::getDefaultFlakeAttrPaths())
             res.push_back(s);
         return res;
@@ -59,7 +61,10 @@ struct CmdBundle : InstallableCommand
 
     Strings getDefaultFlakeAttrPathPrefixes() override
     {
-        Strings res{"packages." + settings.thisSystem.get() + "."};
+        Strings res{
+            "apps." + settings.thisSystem.get() + "."
+
+        };
         for (auto & s : SourceExprCommand::getDefaultFlakeAttrPathPrefixes())
             res.push_back(s);
         return res;
@@ -73,7 +78,7 @@ struct CmdBundle : InstallableCommand
         const flake::LockFlags lockFlagsProg{ .writeLockFile = false };
         auto programInstallable = InstallableFlake(this,
             evalState, std::move(progFlakeRef),
-            Strings{progName == "" ? "defaultPackage" : progName},
+            Strings{progName == "" ? "defaultApp" : progName},
             Strings(this->getDefaultFlakeAttrPathPrefixes()),
             lockFlagsProg);
         auto val = programInstallable.toValue(*evalState).first;
diff --git a/tests/flake-bundler.sh b/tests/flake-bundler.sh
index 2e52f999d..30e2fbd1d 100644
--- a/tests/flake-bundler.sh
+++ b/tests/flake-bundler.sh
@@ -10,8 +10,15 @@ cd $TEST_HOME
 cat <<EOF > flake.nix
 {
     outputs = {self}: {
-       defaultBundler.$system = drv: drv;
+       defaultBundler.$system = drv:
+          if drv?type && drv.type == "derivation"
+          then drv
+          else self.defaultPackage.$system;
        defaultPackage.$system = import ./simple.nix;
+       defaultApp.$system = {
+         type = "app";
+         program = "\${import ./simple.nix}/hello";
+       };
     };
 }
 EOF

From 73e82ae954be991858053df2a6b7323fe3a82c36 Mon Sep 17 00:00:00 2001
From: Tom Bereknyei <tomberek@gmail.com>
Date: Fri, 28 Jan 2022 10:17:51 -0500
Subject: [PATCH 500/567] bundler: tests various combinations of referring to
 installables

---
 tests/flake-bundler.sh | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/tests/flake-bundler.sh b/tests/flake-bundler.sh
index 30e2fbd1d..699920f60 100644
--- a/tests/flake-bundler.sh
+++ b/tests/flake-bundler.sh
@@ -10,10 +10,11 @@ cd $TEST_HOME
 cat <<EOF > flake.nix
 {
     outputs = {self}: {
-       defaultBundler.$system = drv:
+       bundlers.$system.simple = drv:
           if drv?type && drv.type == "derivation"
           then drv
           else self.defaultPackage.$system;
+       defaultBundler.$system = self.bundlers.$system.simple;
        defaultPackage.$system = import ./simple.nix;
        defaultApp.$system = {
          type = "app";
@@ -24,7 +25,11 @@ cat <<EOF > flake.nix
 EOF
 nix build .#
 nix bundle --bundler .# .#
-nix bundle --bundler .#defaultBundler.$system .#defaultPackage.$system
+nix bundle --bundler .#defaultBundler.$system  .#defaultPackage.$system
+nix bundle --bundler .#bundlers.$system.simple .#defaultPackage.$system
+
+nix bundle --bundler .#defaultBundler.$system  .#defaultApp.$system
+nix bundle --bundler .#bundlers.$system.simple .#defaultApp.$system
 
 clearStore
 

From 6e5e64fc7485cc12dd98be07e9abcc52d63dfd86 Mon Sep 17 00:00:00 2001
From: Tom Bereknyei <tomberek@gmail.com>
Date: Fri, 28 Jan 2022 10:23:57 -0500
Subject: [PATCH 501/567] bundler: suggested doc fixes

---
 src/nix/bundle.md | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/nix/bundle.md b/src/nix/bundle.md
index f151eeabc..a5186a996 100644
--- a/src/nix/bundle.md
+++ b/src/nix/bundle.md
@@ -37,7 +37,7 @@ homepage](https://github.com/NixOS/bundlers) for more details.
 >
 > This command only works on Linux.
 
-# Bundler definitions
+# Flake output attributes
 
 If no flake output attribute is given, `nix bundle` tries the following
 flake output attributes:
@@ -51,7 +51,7 @@ output attributes:
 
 # Bundlers
 
-An bundlers is specified by a flake output attribute named
+A bundler is specified by a flake output attribute named
 `bundlers.<system>.<name>` or `defaultBundler.<system>`. It looks like this:
 
 ```nix
@@ -62,6 +62,7 @@ bundlers.x86_64-linux.blender_2_79 = drv: self.packages.x86_64-linux.blender_2_7
 defaultBundler.x86_64-linux = drv: drv;
 ```
 
-A bundler must be a function that accepts a derivation and returns a derivation.
+A bundler must be a function that accepts an arbitrary value (typically a
+derivation or app definition) and returns a derivation.
 
 )""

From a0357abda743496b6731fe1ff63c6be49e03f56f Mon Sep 17 00:00:00 2001
From: Will Dietz <w@wdtz.org>
Date: Sat, 29 Jan 2022 16:23:35 -0600
Subject: [PATCH 502/567] canonPath: fix missing slash when resolving links

Fixes #6017
---
 src/libutil/util.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 1f1f2c861..4cd46c84c 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -147,7 +147,7 @@ Path canonPath(PathView path, bool resolveSymlinks)
                 path = {};
             } else {
                 s += path.substr(0, slash);
-                path = path.substr(slash + 1);
+                path = path.substr(slash);
             }
 
             /* If s points to a symlink, resolve it and continue from there */

From 85b1427662979c6f4fe765839ff7a742216f70f9 Mon Sep 17 00:00:00 2001
From: Thomas Koch <thomas@koch.ro>
Date: Sun, 30 Jan 2022 10:51:39 +0200
Subject: [PATCH 503/567] fix spelling mistakes reported by Debian's lintian
 tool

---
 src/libexpr/primops.cc      | 4 ++--
 src/libstore/globals.hh     | 2 +-
 src/nix/develop.md          | 2 +-
 src/nix/nix.md              | 2 +-
 src/nix/realisation/info.md | 2 +-
 5 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index b53425510..ee0ffcd05 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1269,7 +1269,7 @@ static RegisterPrimOp primop_derivationStrict(RegisterPrimOp::Info {
    substituted by the corresponding output path at build time. For
    example, 'placeholder "out"' returns the string
    /1rz4g4znpzjwh1xymhjpm42vipw92pr73vdgl6xs1hycac8kf2n9. At build
-   time, any occurence of this string in an derivation attribute will
+   time, any occurrence of this string in an derivation attribute will
    be replaced with the concrete path in the Nix store of the output
    ‘out’. */
 static void prim_placeholder(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -2279,7 +2279,7 @@ static RegisterPrimOp primop_removeAttrs({
 /* Builds a set from a list specifying (name, value) pairs.  To be
    precise, a list [{name = "name1"; value = value1;} ... {name =
    "nameN"; value = valueN;}] is transformed to {name1 = value1;
-   ... nameN = valueN;}.  In case of duplicate occurences of the same
+   ... nameN = valueN;}.  In case of duplicate occurrences of the same
    name, the first takes precedence. */
 static void prim_listToAttrs(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index f65893b10..893c95bd6 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -970,7 +970,7 @@ public:
     Setting<std::string> commitLockFileSummary{
         this, "", "commit-lockfile-summary",
         R"(
-          The commit summary to use when commiting changed flake lock files. If
+          The commit summary to use when committing changed flake lock files. If
           empty, the summary is generated based on the action performed.
         )"};
 };
diff --git a/src/nix/develop.md b/src/nix/develop.md
index 1f214966a..3e7e339d5 100644
--- a/src/nix/develop.md
+++ b/src/nix/develop.md
@@ -55,7 +55,7 @@ R""(
   # nix develop /tmp/my-build-env
   ```
 
-* Replace all occurences of the store path corresponding to
+* Replace all occurrences of the store path corresponding to
   `glibc.dev` with a writable directory:
 
   ```console
diff --git a/src/nix/nix.md b/src/nix/nix.md
index 2f54c5e2c..1dc59362d 100644
--- a/src/nix/nix.md
+++ b/src/nix/nix.md
@@ -76,7 +76,7 @@ the Nix store. Here are the recognised types of installables:
     
     Note that the search will only include files indexed by git. In particular, files
     which are matched by `.gitignore` or have never been `git add`-ed will not be
-    available in the flake. If this is undesireable, specify `path:<directory>` explicitly;
+    available in the flake. If this is undesirable, specify `path:<directory>` explicitly;
     
     For example, if `/foo/bar` is a git repository with the following structure:
     ```
diff --git a/src/nix/realisation/info.md b/src/nix/realisation/info.md
index 852240f44..8aa986516 100644
--- a/src/nix/realisation/info.md
+++ b/src/nix/realisation/info.md
@@ -1,7 +1,7 @@
 R"MdBoundary(
 # Description
 
-Display some informations about the given realisation
+Display some information about the given realisation
 
 # Examples
 

From 43509cc69d24d3b8def894a2d47338b7873dc0f4 Mon Sep 17 00:00:00 2001
From: Thomas Koch <thomas@koch.ro>
Date: Sun, 30 Jan 2022 20:59:58 +0200
Subject: [PATCH 504/567] use LOWDOWN_LIBS variable

fixes: #5931
---
 Makefile.config.in  | 1 +
 src/libcmd/local.mk | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/Makefile.config.in b/Makefile.config.in
index c8c4446b4..3505f337e 100644
--- a/Makefile.config.in
+++ b/Makefile.config.in
@@ -16,6 +16,7 @@ LDFLAGS = @LDFLAGS@
 LIBARCHIVE_LIBS = @LIBARCHIVE_LIBS@
 LIBBROTLI_LIBS = @LIBBROTLI_LIBS@
 LIBCURL_LIBS = @LIBCURL_LIBS@
+LOWDOWN_LIBS = @LOWDOWN_LIBS@
 OPENSSL_LIBS = @OPENSSL_LIBS@
 LIBSECCOMP_LIBS = @LIBSECCOMP_LIBS@
 PACKAGE_NAME = @PACKAGE_NAME@
diff --git a/src/libcmd/local.mk b/src/libcmd/local.mk
index 8b0662753..7a2f83cc7 100644
--- a/src/libcmd/local.mk
+++ b/src/libcmd/local.mk
@@ -8,7 +8,7 @@ libcmd_SOURCES := $(wildcard $(d)/*.cc)
 
 libcmd_CXXFLAGS += -I src/libutil -I src/libstore -I src/libexpr -I src/libmain -I src/libfetchers
 
-libcmd_LDFLAGS += -llowdown -pthread
+libcmd_LDFLAGS += $(LOWDOWN_LIBS) -pthread
 
 libcmd_LIBS = libstore libutil libexpr libmain libfetchers
 

From 73d5f38a47e7c3dea62994cfb8f962976194f767 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 1 Feb 2022 10:44:19 +0100
Subject: [PATCH 505/567] Require lowdown 0.9.0

Fixes #6021.
---
 configure.ac | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 01d674879..8a01c33ec 100644
--- a/configure.ac
+++ b/configure.ac
@@ -272,7 +272,7 @@ AC_ARG_ENABLE(doc-gen, AS_HELP_STRING([--disable-doc-gen],[disable documentation
 AC_SUBST(doc_generate)
 
 # Look for lowdown library.
-PKG_CHECK_MODULES([LOWDOWN], [lowdown >= 0.8.0], [CXXFLAGS="$LOWDOWN_CFLAGS $CXXFLAGS"])
+PKG_CHECK_MODULES([LOWDOWN], [lowdown >= 0.9.0], [CXXFLAGS="$LOWDOWN_CFLAGS $CXXFLAGS"])
 
 # Setuid installations.
 AC_CHECK_FUNCS([setresuid setreuid lchown])

From 169ea0b83fe09b473766e22337dfd488c96ff2be Mon Sep 17 00:00:00 2001
From: Alexander Bantyev <balsoft@balsoft.ru>
Date: Wed, 2 Feb 2022 21:41:45 +0300
Subject: [PATCH 506/567] Flake follows: resolve all follows to absolute

It's not possible in general to know in computeLocks, relative to
which path the follows was intended to be. So, we always resolve
follows to their absolute states when we encounter them (which can
either be in parseFlakeInput or computeLocks' fake input population).

Fixes https://github.com/NixOS/nix/issues/6013
Fixes https://github.com/NixOS/nix/issues/5609
Fixes https://github.com/NixOS/nix/issues/5697 (again)
---
 src/libexpr/flake/flake.cc | 87 +++++++++++++++-----------------------
 tests/flakes.sh            |  6 ++-
 2 files changed, 38 insertions(+), 55 deletions(-)

diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 0fbe9b960..22ff9b153 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -89,11 +89,11 @@ static void expectType(EvalState & state, ValueType type,
 
 static std::map<FlakeId, FlakeInput> parseFlakeInputs(
     EvalState & state, Value * value, const Pos & pos,
-    const std::optional<Path> & baseDir);
+    const std::optional<Path> & baseDir, InputPath lockRootPath);
 
 static FlakeInput parseFlakeInput(EvalState & state,
     const std::string & inputName, Value * value, const Pos & pos,
-    const std::optional<Path> & baseDir)
+    const std::optional<Path> & baseDir, InputPath lockRootPath)
 {
     expectType(state, nAttrs, *value, pos);
 
@@ -117,10 +117,12 @@ static FlakeInput parseFlakeInput(EvalState & state,
                 expectType(state, nBool, *attr.value, *attr.pos);
                 input.isFlake = attr.value->boolean;
             } else if (attr.name == sInputs) {
-                input.overrides = parseFlakeInputs(state, attr.value, *attr.pos, baseDir);
+                input.overrides = parseFlakeInputs(state, attr.value, *attr.pos, baseDir, lockRootPath);
             } else if (attr.name == sFollows) {
                 expectType(state, nString, *attr.value, *attr.pos);
-                input.follows = parseInputPath(attr.value->string.s);
+                auto follows(parseInputPath(attr.value->string.s));
+                follows.insert(follows.begin(), lockRootPath.begin(), lockRootPath.end());
+                input.follows = follows;
             } else {
                 switch (attr.value->type()) {
                     case nString:
@@ -166,7 +168,7 @@ static FlakeInput parseFlakeInput(EvalState & state,
 
 static std::map<FlakeId, FlakeInput> parseFlakeInputs(
     EvalState & state, Value * value, const Pos & pos,
-    const std::optional<Path> & baseDir)
+    const std::optional<Path> & baseDir, InputPath lockRootPath)
 {
     std::map<FlakeId, FlakeInput> inputs;
 
@@ -178,7 +180,8 @@ static std::map<FlakeId, FlakeInput> parseFlakeInputs(
                 inputAttr.name,
                 inputAttr.value,
                 *inputAttr.pos,
-                baseDir));
+                baseDir,
+                lockRootPath));
     }
 
     return inputs;
@@ -188,7 +191,8 @@ static Flake getFlake(
     EvalState & state,
     const FlakeRef & originalRef,
     bool allowLookup,
-    FlakeCache & flakeCache)
+    FlakeCache & flakeCache,
+    InputPath lockRootPath)
 {
     auto [sourceInfo, resolvedRef, lockedRef] = fetchOrSubstituteTree(
         state, originalRef, allowLookup, flakeCache);
@@ -223,7 +227,7 @@ static Flake getFlake(
     auto sInputs = state.symbols.create("inputs");
 
     if (auto inputs = vInfo.attrs->get(sInputs))
-        flake.inputs = parseFlakeInputs(state, inputs->value, *inputs->pos, flakeDir);
+        flake.inputs = parseFlakeInputs(state, inputs->value, *inputs->pos, flakeDir, lockRootPath);
 
     auto sOutputs = state.symbols.create("outputs");
 
@@ -287,6 +291,11 @@ static Flake getFlake(
     return flake;
 }
 
+Flake getFlake(EvalState & state, const FlakeRef & originalRef, bool allowLookup, FlakeCache & flakeCache)
+{
+    return getFlake(state, originalRef, allowLookup, flakeCache, {});
+}
+
 Flake getFlake(EvalState & state, const FlakeRef & originalRef, bool allowLookup)
 {
     FlakeCache flakeCache;
@@ -332,22 +341,12 @@ LockedFlake lockFlake(
 
         std::vector<FlakeRef> parents;
 
-        struct LockParent {
-            /* The path to this parent. */
-            InputPath path;
-
-            /* Whether we are currently inside a top-level lockfile
-               (inputs absolute) or subordinate lockfile (inputs
-               relative). */
-            bool absolute;
-        };
-
         std::function<void(
             const FlakeInputs & flakeInputs,
             std::shared_ptr<Node> node,
             const InputPath & inputPathPrefix,
             std::shared_ptr<const Node> oldNode,
-            const LockParent & parent,
+            const InputPath & lockRootPath,
             const Path & parentPath,
             bool trustLock)>
             computeLocks;
@@ -357,7 +356,7 @@ LockedFlake lockFlake(
             std::shared_ptr<Node> node,
             const InputPath & inputPathPrefix,
             std::shared_ptr<const Node> oldNode,
-            const LockParent & parent,
+            const InputPath & lockRootPath,
             const Path & parentPath,
             bool trustLock)
         {
@@ -402,17 +401,7 @@ LockedFlake lockFlake(
                     if (input.follows) {
                         InputPath target;
 
-                        if (parent.absolute && !hasOverride) {
-                            target = *input.follows;
-                        } else {
-                            if (hasOverride) {
-                                target = inputPathPrefix;
-                                target.pop_back();
-                            } else
-                                target = parent.path;
-
-                            for (auto & i : *input.follows) target.push_back(i);
-                        }
+                        target.insert(target.end(), input.follows->begin(), input.follows->end());
 
                         debug("input '%s' follows '%s'", inputPathS, printInputPath(target));
                         node->inputs.insert_or_assign(id, target);
@@ -485,23 +474,25 @@ LockedFlake lockFlake(
                                             break;
                                         }
                                     }
+                                    auto absoluteFollows(lockRootPath);
+                                    absoluteFollows.insert(absoluteFollows.end(), follows->begin(), follows->end());
                                     fakeInputs.emplace(i.first, FlakeInput {
-                                        .follows = *follows,
+                                        .follows = absoluteFollows,
                                     });
                                 }
                             }
                         }
 
-                        LockParent newParent {
-                            .path = inputPath,
-                            .absolute = true
-                        };
-
+                        auto localPath(parentPath);
+                        // If this input is a path, recurse it down.
+                        // This allows us to resolve path inputs relative to the current flake.
+                        if ((*input.ref).input.getType() == "path")
+                            localPath = absPath(*input.ref->input.getSourcePath(), parentPath);
                         computeLocks(
                             mustRefetch
-                            ? getFlake(state, oldLock->lockedRef, false, flakeCache).inputs
+                            ? getFlake(state, oldLock->lockedRef, false, flakeCache, inputPath).inputs
                             : fakeInputs,
-                            childNode, inputPath, oldLock, newParent, parentPath, !mustRefetch);
+                            childNode, inputPath, oldLock, lockRootPath, parentPath, !mustRefetch);
 
                     } else {
                         /* We need to create a new lock file entry. So fetch
@@ -520,7 +511,7 @@ LockedFlake lockFlake(
                             if (localRef.input.getType() == "path")
                                 localPath = absPath(*input.ref->input.getSourcePath(), parentPath);
 
-                            auto inputFlake = getFlake(state, localRef, useRegistries, flakeCache);
+                            auto inputFlake = getFlake(state, localRef, useRegistries, flakeCache, inputPath);
 
                             /* Note: in case of an --override-input, we use
                                the *original* ref (input2.ref) for the
@@ -541,13 +532,6 @@ LockedFlake lockFlake(
                             parents.push_back(*input.ref);
                             Finally cleanup([&]() { parents.pop_back(); });
 
-                            // Follows paths from existing inputs in the top-level lockfile are absolute,
-                            // whereas paths in subordinate lockfiles are relative to those lockfiles.
-                            LockParent newParent {
-                                .path = inputPath,
-                                .absolute = oldLock ? true : false
-                            };
-
                             /* Recursively process the inputs of this
                                flake. Also, unless we already have this flake
                                in the top-level lock file, use this flake's
@@ -558,7 +542,7 @@ LockedFlake lockFlake(
                                 ? std::dynamic_pointer_cast<const Node>(oldLock)
                                 : LockFile::read(
                                     inputFlake.sourceInfo->actualPath + "/" + inputFlake.lockedRef.subdir + "/flake.lock").root,
-                                newParent, localPath, false);
+                                oldLock ? lockRootPath : inputPath, localPath, false);
                         }
 
                         else {
@@ -576,17 +560,12 @@ LockedFlake lockFlake(
             }
         };
 
-        LockParent parent {
-            .path = {},
-            .absolute = true
-        };
-
         // Bring in the current ref for relative path resolution if we have it
         auto parentPath = canonPath(flake.sourceInfo->actualPath + "/" + flake.lockedRef.subdir, true);
 
         computeLocks(
             flake.inputs, newLockFile.root, {},
-            lockFlags.recreateLockFile ? nullptr : oldLockFile.root, parent, parentPath, false);
+            lockFlags.recreateLockFile ? nullptr : oldLockFile.root, {}, parentPath, false);
 
         for (auto & i : lockFlags.inputOverrides)
             if (!overridesUsed.count(i.first))
diff --git a/tests/flakes.sh b/tests/flakes.sh
index 20e6d09c1..db178967f 100644
--- a/tests/flakes.sh
+++ b/tests/flakes.sh
@@ -730,6 +730,7 @@ cat > $flakeFollowsB/flake.nix <<EOF
     description = "Flake B";
     inputs = {
         foobar.url = "path:$flakeFollowsA/flakeE";
+        goodoo.follows = "C/goodoo";
         C = {
             url = "path:./flakeC";
             inputs.foobar.follows = "foobar";
@@ -744,6 +745,7 @@ cat > $flakeFollowsC/flake.nix <<EOF
     description = "Flake C";
     inputs = {
         foobar.url = "path:$flakeFollowsA/flakeE";
+        goodoo.follows = "foobar";
     };
     outputs = { ... }: {};
 }
@@ -759,7 +761,7 @@ EOF
 
 cat > $flakeFollowsE/flake.nix <<EOF
 {
-    description = "Flake D";
+    description = "Flake E";
     inputs = {};
     outputs = { ... }: {};
 }
@@ -768,6 +770,8 @@ EOF
 git -C $flakeFollowsA add flake.nix flakeB/flake.nix \
   flakeB/flakeC/flake.nix flakeD/flake.nix flakeE/flake.nix
 
+nix flake metadata $flakeFollowsA
+
 nix flake update $flakeFollowsA
 
 oldLock="$(cat "$flakeFollowsA/flake.lock")"

From bd383d1b6f91c4fe7ac21c52771e92027f649fa0 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 4 Feb 2022 00:31:33 +0100
Subject: [PATCH 507/567] Make most calls to determinePos() lazy

---
 src/libcmd/installables.cc             |  2 +-
 src/libexpr/eval-inline.hh             | 26 +++++++++++++++++---------
 src/libexpr/eval.cc                    | 14 ++++++++++----
 src/libexpr/eval.hh                    | 10 +++++++++-
 src/libexpr/get-drvs.cc                |  4 ++--
 src/libexpr/value.hh                   |  2 +-
 src/nix-build/nix-build.cc             |  2 +-
 src/nix-env/user-env.cc                |  2 +-
 src/nix-instantiate/nix-instantiate.cc |  2 +-
 src/nix/repl.cc                        |  6 +++---
 10 files changed, 46 insertions(+), 24 deletions(-)

diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index ec4f8f6f9..38a177f80 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -497,7 +497,7 @@ Value * InstallableFlake::getFlakeOutputs(EvalState & state, const flake::Locked
     auto aOutputs = vFlake->attrs->get(state.symbols.create("outputs"));
     assert(aOutputs);
 
-    state.forceValue(*aOutputs->value, aOutputs->value->determinePos(noPos));
+    state.forceValue(*aOutputs->value, [&]() { return aOutputs->value->determinePos(noPos); });
 
     return aOutputs->value;
 }
diff --git a/src/libexpr/eval-inline.hh b/src/libexpr/eval-inline.hh
index 08acb0877..aef1f6351 100644
--- a/src/libexpr/eval-inline.hh
+++ b/src/libexpr/eval-inline.hh
@@ -15,12 +15,6 @@ LocalNoInlineNoReturn(void throwEvalError(const Pos & pos, const char * s))
     });
 }
 
-LocalNoInlineNoReturn(void throwTypeError(const char * s, const Value & v))
-{
-    throw TypeError(s, showType(v));
-}
-
-
 LocalNoInlineNoReturn(void throwTypeError(const Pos & pos, const char * s, const Value & v))
 {
     throw TypeError({
@@ -31,6 +25,13 @@ LocalNoInlineNoReturn(void throwTypeError(const Pos & pos, const char * s, const
 
 
 void EvalState::forceValue(Value & v, const Pos & pos)
+{
+    forceValue(v, [&]() { return pos; });
+}
+
+
+template<typename Callable>
+void EvalState::forceValue(Value & v, Callable getPos)
 {
     if (v.isThunk()) {
         Env * env = v.thunk.env;
@@ -47,15 +48,22 @@ void EvalState::forceValue(Value & v, const Pos & pos)
     else if (v.isApp())
         callFunction(*v.app.left, *v.app.right, v, noPos);
     else if (v.isBlackhole())
-        throwEvalError(pos, "infinite recursion encountered");
+        throwEvalError(getPos(), "infinite recursion encountered");
 }
 
 
 inline void EvalState::forceAttrs(Value & v, const Pos & pos)
 {
-    forceValue(v, pos);
+    forceAttrs(v, [&]() { return pos; });
+}
+
+
+template <typename Callable>
+inline void EvalState::forceAttrs(Value & v, Callable getPos)
+{
+    forceValue(v, getPos);
     if (v.type() != nAttrs)
-        throwTypeError(pos, "value is %1% while a set was expected", v);
+        throwTypeError(getPos(), "value is %1% while a set was expected", v);
 }
 
 
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index afde29d11..2d4eb57fc 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -219,7 +219,7 @@ string showType(const Value & v)
     }
 }
 
-Pos Value::determinePos(const Pos &pos) const
+Pos Value::determinePos(const Pos & pos) const
 {
     switch (internalType) {
         case tAttrs: return *attrs->pos;
@@ -754,6 +754,11 @@ LocalNoInlineNoReturn(void throwTypeError(const Pos & pos, const char * s, const
     });
 }
 
+LocalNoInlineNoReturn(void throwTypeError(const char * s, const Value & v))
+{
+    throw TypeError(s, showType(v));
+}
+
 LocalNoInlineNoReturn(void throwAssertionError(const Pos & pos, const char * s, const string & s1))
 {
     throw AssertionError({
@@ -1138,7 +1143,7 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
            Hence we need __overrides.) */
         if (hasOverrides) {
             Value * vOverrides = (*v.attrs)[overrides->second.displ].value;
-            state.forceAttrs(*vOverrides, vOverrides->determinePos(noPos));
+            state.forceAttrs(*vOverrides, [&]() { return vOverrides->determinePos(noPos); });
             Bindings * newBnds = state.allocBindings(v.attrs->capacity() + vOverrides->attrs->size());
             for (auto & i : *v.attrs)
                 newBnds->push_back(i);
@@ -1500,7 +1505,8 @@ void EvalState::incrFunctionCall(ExprLambda * fun)
 
 void EvalState::autoCallFunction(Bindings & args, Value & fun, Value & res)
 {
-    Pos pos = fun.determinePos(noPos);
+    auto pos = fun.determinePos(noPos);
+
     forceValue(fun, pos);
 
     if (fun.type() == nAttrs) {
@@ -1797,7 +1803,7 @@ void EvalState::forceValueDeep(Value & v)
     recurse = [&](Value & v) {
         if (!seen.insert(&v).second) return;
 
-        forceValue(v, v.determinePos(noPos));
+        forceValue(v, [&]() { return v.determinePos(noPos); });
 
         if (v.type() == nAttrs) {
             for (auto & i : *v.attrs)
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 190dd16dc..ce5a16e11 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -224,6 +224,9 @@ public:
        result.  Otherwise, this is a no-op. */
     inline void forceValue(Value & v, const Pos & pos);
 
+    template <typename Callable>
+    inline void forceValue(Value & v, Callable getPos);
+
     /* Force a value, then recursively force list elements and
        attributes. */
     void forceValueDeep(Value & v);
@@ -232,7 +235,12 @@ public:
     NixInt forceInt(Value & v, const Pos & pos);
     NixFloat forceFloat(Value & v, const Pos & pos);
     bool forceBool(Value & v, const Pos & pos);
-    inline void forceAttrs(Value & v, const Pos & pos);
+
+    void forceAttrs(Value & v, const Pos & pos);
+
+    template <typename Callable>
+    inline void forceAttrs(Value & v, Callable getPos);
+
     inline void forceList(Value & v, const Pos & pos);
     void forceFunction(Value & v, const Pos & pos); // either lambda or primop
     std::string_view forceString(Value & v, const Pos & pos = noPos);
diff --git a/src/libexpr/get-drvs.cc b/src/libexpr/get-drvs.cc
index 1b1cef1bf..5995a857b 100644
--- a/src/libexpr/get-drvs.cc
+++ b/src/libexpr/get-drvs.cc
@@ -172,7 +172,7 @@ StringSet DrvInfo::queryMetaNames()
 
 bool DrvInfo::checkMeta(Value & v)
 {
-    state->forceValue(v, v.determinePos(noPos));
+    state->forceValue(v, [&]() { return v.determinePos(noPos); });
     if (v.type() == nList) {
         for (auto elem : v.listItems())
             if (!checkMeta(*elem)) return false;
@@ -278,7 +278,7 @@ static bool getDerivation(EvalState & state, Value & v,
     bool ignoreAssertionFailures)
 {
     try {
-        state.forceValue(v, v.determinePos(noPos));
+        state.forceValue(v, [&]() { return v.determinePos(noPos); });
         if (!state.isDerivation(v)) return true;
 
         /* Remove spurious duplicates (e.g., a set like `rec { x =
diff --git a/src/libexpr/value.hh b/src/libexpr/value.hh
index 1896c7563..bef5cd6bd 100644
--- a/src/libexpr/value.hh
+++ b/src/libexpr/value.hh
@@ -361,7 +361,7 @@ public:
         return internalType == tList1 ? 1 : internalType == tList2 ? 2 : bigList.size;
     }
 
-    Pos determinePos(const Pos &pos) const;
+    Pos determinePos(const Pos & pos) const;
 
     /* Check whether forcing this value requires a trivial amount of
        computation. In particular, function applications are
diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index a7dce23f1..ae4746955 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -318,7 +318,7 @@ static void main_nix_build(int argc, char * * argv)
 
         for (auto & i : attrPaths) {
             Value & v(*findAlongAttrPath(*state, i, *autoArgs, vRoot).first);
-            state->forceValue(v, v.determinePos(noPos));
+            state->forceValue(v, [&]() { return v.determinePos(noPos); });
             getDerivations(*state, v, "", *autoArgs, drvs, false);
         }
     }
diff --git a/src/nix-env/user-env.cc b/src/nix-env/user-env.cc
index 727338105..5842e6501 100644
--- a/src/nix-env/user-env.cc
+++ b/src/nix-env/user-env.cc
@@ -129,7 +129,7 @@ bool createUserEnv(EvalState & state, DrvInfos & elems,
 
     /* Evaluate it. */
     debug("evaluating user environment builder");
-    state.forceValue(topLevel, topLevel.determinePos(noPos));
+    state.forceValue(topLevel, [&]() { return topLevel.determinePos(noPos); });
     PathSet context;
     Attr & aDrvPath(*topLevel.attrs->find(state.sDrvPath));
     auto topLevelDrv = state.store->parseStorePath(state.coerceToPath(*aDrvPath.pos, *aDrvPath.value, context));
diff --git a/src/nix-instantiate/nix-instantiate.cc b/src/nix-instantiate/nix-instantiate.cc
index 8836f810c..a08683be1 100644
--- a/src/nix-instantiate/nix-instantiate.cc
+++ b/src/nix-instantiate/nix-instantiate.cc
@@ -40,7 +40,7 @@ void processExpr(EvalState & state, const Strings & attrPaths,
 
     for (auto & i : attrPaths) {
         Value & v(*findAlongAttrPath(state, i, autoArgs, vRoot).first);
-        state.forceValue(v, v.determinePos(noPos));
+        state.forceValue(v, [&]() { return v.determinePos(noPos); });
 
         PathSet context;
         if (evalOnly) {
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 54daeb246..e9bebff17 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -673,7 +673,7 @@ void NixRepl::reloadFiles()
 
 void NixRepl::addAttrsToScope(Value & attrs)
 {
-    state->forceAttrs(attrs, attrs.determinePos(noPos));
+    state->forceAttrs(attrs, [&]() { return attrs.determinePos(noPos); });
     if (displ + attrs.attrs->size() >= envSize)
         throw Error("environment full; cannot add more variables");
 
@@ -712,7 +712,7 @@ void NixRepl::evalString(string s, Value & v)
 {
     Expr * e = parseString(s);
     e->eval(*state, *env, v);
-    state->forceValue(v, v.determinePos(noPos));
+    state->forceValue(v, [&]() { return v.determinePos(noPos); });
 }
 
 
@@ -742,7 +742,7 @@ std::ostream & NixRepl::printValue(std::ostream & str, Value & v, unsigned int m
     str.flush();
     checkInterrupt();
 
-    state->forceValue(v, v.determinePos(noPos));
+    state->forceValue(v, [&]() { return v.determinePos(noPos); });
 
     switch (v.type()) {
 

From f222fba4dca69919d28468467e6e5c4c859cfc13 Mon Sep 17 00:00:00 2001
From: Matthew Bauer <mjbauer95@gmail.com>
Date: Thu, 3 Feb 2022 20:51:47 -0600
Subject: [PATCH 508/567] Allow missing flake.nix for --override-input target
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

At this point, we don’t know if the input is a flake or not. So, we
should allow the user to override the input with a directory without a
flake.nix.

Ideally, we could figure whether the input was originally a flake or
not, but that would require instantiating the whole flake. So just
allow it to be missing here, and rely on checks later on to verify the
input for us.
---
 src/libcmd/installables.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index 38a177f80..5e8b62e1a 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -97,7 +97,7 @@ MixFlakeOptions::MixFlakeOptions()
             lockFlags.writeLockFile = false;
             lockFlags.inputOverrides.insert_or_assign(
                 flake::parseInputPath(inputPath),
-                parseFlakeRef(flakeRef, absPath(".")));
+                parseFlakeRef(flakeRef, absPath("."), true));
         }}
     });
 

From 1daf1babf956cab98857db92de8829a1e7f2ae3e Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Fri, 4 Feb 2022 07:36:56 +0100
Subject: [PATCH 509/567] fix nix repl not overriding existing bindings in :a

previously :a would override old bindings of a name with new values if the added
set contained names that were already bound. in nix 2.6 this doesn't happen any
more, which is potentially confusing.

fixes #6041
---
 src/libexpr/nixexpr.hh | 12 ++++++++----
 tests/repl.sh          | 23 +++++++++++++++++++++++
 2 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index 4e923ac89..6f6acb074 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -367,15 +367,19 @@ struct StaticEnv
 
     void sort()
     {
-        std::sort(vars.begin(), vars.end(),
+        std::stable_sort(vars.begin(), vars.end(),
             [](const Vars::value_type & a, const Vars::value_type & b) { return a.first < b.first; });
     }
 
     void deduplicate()
     {
-        const auto last = std::unique(vars.begin(), vars.end(),
-            [] (const Vars::value_type & a, const Vars::value_type & b) { return a.first == b.first; });
-        vars.erase(last, vars.end());
+        auto it = vars.begin(), jt = it, end = vars.end();
+        while (jt != end) {
+            *it = *jt++;
+            while (jt != end && it->first == jt->first) *it = *jt++;
+            it++;
+        }
+        vars.erase(it, end);
     }
 
     Vars::const_iterator find(const Symbol & name) const
diff --git a/tests/repl.sh b/tests/repl.sh
index 0e23a98db..6505f1741 100644
--- a/tests/repl.sh
+++ b/tests/repl.sh
@@ -40,3 +40,26 @@ testRepl () {
 testRepl
 # Same thing (kind-of), but with a remote store.
 testRepl --store "$TEST_ROOT/store?real=$NIX_STORE_DIR"
+
+testReplResponse () {
+    local response="$(nix repl <<< "$1")"
+    echo "$response" | grep -qs "$2" \
+      || fail "repl command set:
+
+$1
+
+does not respond with:
+
+$2
+
+but with:
+
+$response"
+}
+
+# :a uses the newest version of a symbol
+testReplResponse '
+:a { a = "1"; }
+:a { a = "2"; }
+"result: ${a}"
+' "result: 2"

From 9d840758a8d195e52e8b7d08cd9c15f6b8259724 Mon Sep 17 00:00:00 2001
From: Maximilian Bosch <maximilian@mbosch.me>
Date: Fri, 4 Feb 2022 22:43:16 +0100
Subject: [PATCH 510/567] completions: pipe stderr to /dev/null

This fixes weird issues where e.g.

    nix build -L .#<tab>

deletes the current line from the prompt.
---
 misc/bash/completion.sh | 2 +-
 misc/zsh/completion.zsh | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/misc/bash/completion.sh b/misc/bash/completion.sh
index 8fc224792..045053dee 100644
--- a/misc/bash/completion.sh
+++ b/misc/bash/completion.sh
@@ -15,7 +15,7 @@ function _complete_nix {
         else
             COMPREPLY+=("$completion")
         fi
-    done < <(NIX_GET_COMPLETIONS=$cword "${words[@]/#\~/$HOME}")
+    done < <(NIX_GET_COMPLETIONS=$cword "${words[@]/#\~/$HOME}" 2>/dev/null)
     __ltrim_colon_completions "$cur"
 }
 
diff --git a/misc/zsh/completion.zsh b/misc/zsh/completion.zsh
index a902e37dc..e702c721e 100644
--- a/misc/zsh/completion.zsh
+++ b/misc/zsh/completion.zsh
@@ -4,7 +4,7 @@ function _nix() {
   local ifs_bk="$IFS"
   local input=("${(Q)words[@]}")
   IFS=$'\n'
-  local res=($(NIX_GET_COMPLETIONS=$((CURRENT - 1)) "$input[@]"))
+  local res=($(NIX_GET_COMPLETIONS=$((CURRENT - 1)) "$input[@]" 2>/dev/null))
   IFS="$ifs_bk"
   local tpe="${${res[1]}%%>	*}"
   local -a suggestions

From 45eeb2fd6ade832d045884b9a18decb4cddaceb1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sandro=20J=C3=A4ckel?= <sandro.jaeckel@sap.com>
Date: Sat, 5 Feb 2022 17:56:51 +0100
Subject: [PATCH 511/567] nix-shell: set BASH variable to correct shell

---
 src/nix-build/nix-build.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index ae4746955..aeabdcdd4 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -500,6 +500,7 @@ static void main_nix_build(int argc, char * * argv)
                 "%3%"
                 "PATH=%4%:\"$PATH\"; "
                 "SHELL=%5%; "
+                "BASH=%5%; "
                 "set +e; "
                 R"s([ -n "$PS1" -a -z "$NIX_SHELL_PRESERVE_PROMPT" ] && PS1='\n\[\033[1;32m\][nix-shell:\w]\$\[\033[0m\] '; )s"
                 "if [ \"$(type -t runHook)\" = function ]; then runHook shellHook; fi; "

From c3b942e0fc4777f9033f614b6b1f462c0f8c473e Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Sun, 6 Feb 2022 13:25:56 +0100
Subject: [PATCH 512/567] Don't hold interruptCallbacks lock during interrupt
 handling

This changes the representation of the interrupt callback list to
be safe to use during interrupt handling.

Holding a lock while executing arbitrary functions is something to
avoid in general, because of the risk of deadlock.

Such a deadlock occurs in https://github.com/NixOS/nix/issues/3294
where ~CurlDownloader tries to deregister its interrupt callback.

This happens during what seems to be a triggerInterrupt() by the
daemon connection's MonitorFdHup thread. This bit I can not confirm
based on the stack trace though; it's based on reading the code,
so no absolute certainty, but a smoking gun nonetheless.
---
 src/libutil/util.cc | 55 +++++++++++++++++++++++++++++++++++----------
 1 file changed, 43 insertions(+), 12 deletions(-)

diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index cd359cfee..03cbd7765 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1561,7 +1561,22 @@ std::pair<unsigned short, unsigned short> getWindowSize()
 }
 
 
-static Sync<std::list<std::function<void()>>> _interruptCallbacks;
+/* We keep track of interrupt callbacks using integer tokens, so we can iterate
+   safely without having to lock the data structure while executing arbitrary
+   functions.
+ */
+struct InterruptCallbacks {
+    typedef int64_t Token;
+
+    /* We use unique tokens so that we can't accidentally delete the wrong
+       handler because of an erroneous double delete. */
+    Token nextToken = 0;
+
+    /* Used as a list, see InterruptCallbacks comment. */
+    std::map<Token, std::function<void()>> callbacks;
+};
+
+static Sync<InterruptCallbacks> _interruptCallbacks;
 
 static void signalHandlerThread(sigset_t set)
 {
@@ -1583,14 +1598,29 @@ void triggerInterrupt()
     _isInterrupted = true;
 
     {
-        auto interruptCallbacks(_interruptCallbacks.lock());
-        for (auto & callback : *interruptCallbacks) {
-            try {
-                callback();
-            } catch (...) {
-                ignoreException();
+        InterruptCallbacks::Token i = 0;
+        std::function<void()> callback;
+        do {
+            {
+                auto interruptCallbacks(_interruptCallbacks.lock());
+                auto lb = interruptCallbacks->callbacks.lower_bound(i);
+                if (lb != interruptCallbacks->callbacks.end()) {
+                    callback = lb->second;
+                    i = lb->first + 1;
+                } else {
+                    callback = nullptr;
+                }
+            }
+
+            if (callback) {
+                try {
+                    callback();
+                } catch (...) {
+                    ignoreException();
+                }
             }
         }
+        while (callback);
     }
 }
 
@@ -1694,21 +1724,22 @@ void restoreProcessContext(bool restoreMounts)
 /* RAII helper to automatically deregister a callback. */
 struct InterruptCallbackImpl : InterruptCallback
 {
-    std::list<std::function<void()>>::iterator it;
+    InterruptCallbacks::Token token;
     ~InterruptCallbackImpl() override
     {
-        _interruptCallbacks.lock()->erase(it);
+        auto interruptCallbacks(_interruptCallbacks.lock());
+        interruptCallbacks->callbacks.erase(token);
     }
 };
 
 std::unique_ptr<InterruptCallback> createInterruptCallback(std::function<void()> callback)
 {
     auto interruptCallbacks(_interruptCallbacks.lock());
-    interruptCallbacks->push_back(callback);
+    auto token = interruptCallbacks->nextToken++;
+    interruptCallbacks->callbacks.emplace(token, callback);
 
     auto res = std::make_unique<InterruptCallbackImpl>();
-    res->it = interruptCallbacks->end();
-    res->it--;
+    res->token = token;
 
     return std::unique_ptr<InterruptCallback>(res.release());
 }

From c23501a3b24d84376086179756fefd399c2a7cbb Mon Sep 17 00:00:00 2001
From: "lincoln auster [they/them]" <lincolnauster@gmail.com>
Date: Sun, 6 Feb 2022 16:28:21 -0700
Subject: [PATCH 513/567] repl/load-flake: throw error if path isn't specified

---
 src/nix/repl.cc | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index e9bebff17..97ca39145 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -623,6 +623,9 @@ void NixRepl::loadFile(const Path & path)
 
 void NixRepl::loadFlake(const std::string & flakeRefS)
 {
+    if (flakeRefS.empty())
+        throw Error("cannot use `:load-flake` without a path specified. (Use . for the current working directory.)");
+
     auto flakeRef = parseFlakeRef(flakeRefS, absPath("."), true);
     if (evalSettings.pureEval && !flakeRef.input.isImmutable())
         throw Error("cannot use ':load-flake' on mutable flake reference '%s' (use --impure to override)", flakeRefS);

From 97e02c23bde0515540c63081824f85ff1cebd86f Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 7 Feb 2022 10:48:57 +0100
Subject: [PATCH 514/567] Fix 'basic_string::_M_construct null not valid' in
 interrupted download

Fixes #5985.
---
 src/libstore/filetransfer.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libstore/filetransfer.cc b/src/libstore/filetransfer.cc
index 6b62311cf..76fed11db 100644
--- a/src/libstore/filetransfer.cc
+++ b/src/libstore/filetransfer.cc
@@ -128,7 +128,7 @@ struct curlFileTransfer : public FileTransfer
             if (requestHeaders) curl_slist_free_all(requestHeaders);
             try {
                 if (!done)
-                    fail(FileTransferError(Interrupted, nullptr, "download of '%s' was interrupted", request.uri));
+                    fail(FileTransferError(Interrupted, {}, "download of '%s' was interrupted", request.uri));
             } catch (...) {
                 ignoreException();
             }
@@ -704,7 +704,7 @@ struct curlFileTransfer : public FileTransfer
                 auto s3Res = s3Helper.getObject(bucketName, key);
                 FileTransferResult res;
                 if (!s3Res.data)
-                    throw FileTransferError(NotFound, nullptr, "S3 object '%s' does not exist", request.uri);
+                    throw FileTransferError(NotFound, {}, "S3 object '%s' does not exist", request.uri);
                 res.data = std::move(*s3Res.data);
                 callback(std::move(res));
 #else

From b1abfcd0c247df7dc269ba8cb6b1e23d287c20ad Mon Sep 17 00:00:00 2001
From: lincoln auster <lincolnauster@gmail.com>
Date: Mon, 7 Feb 2022 08:35:50 -0700
Subject: [PATCH 515/567] fix markup

Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
---
 src/nix/repl.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 97ca39145..2c39fac91 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -624,7 +624,7 @@ void NixRepl::loadFile(const Path & path)
 void NixRepl::loadFlake(const std::string & flakeRefS)
 {
     if (flakeRefS.empty())
-        throw Error("cannot use `:load-flake` without a path specified. (Use . for the current working directory.)");
+        throw Error("cannot use ':load-flake' without a path specified. (Use '.' for the current working directory.)");
 
     auto flakeRef = parseFlakeRef(flakeRefS, absPath("."), true);
     if (evalSettings.pureEval && !flakeRef.input.isImmutable())

From 3ec02deb20b52bd2c23fbf3c98026898857a4def Mon Sep 17 00:00:00 2001
From: Sergei Trofimovich <slyich@gmail.com>
Date: Mon, 7 Feb 2022 16:14:57 +0000
Subject: [PATCH 516/567] Make sure no exceptions leave ignoreException()

I noticed that occasional Ctrl-C leaves *.lock files around.
`nix-daemon`'s journal logs contained crashes like:

    nix-daemon[30416]: terminate called after throwing an instance of 'nix::SysError'
    nix-daemon[30416]:   what():  error: writing to file: Broken pipe

And core dump backtraces pointed at `teriminate()` call from
destructors:

    ...
    _Unwind_Resume ()
    nix::ignoreException() ()
    nix::LocalDerivationGoal::~LocalDerivationGoal()
    ...

    void ignoreException()
    {
        try {
            throw;
        } catch (std::exception & e) {
            printError("error (ignored): %1%", e.what());
        }
    }

The crashes happen when client side closes early and printError() throws
an IO error.

The change wraps `ignoreException()` into blanket `try { ... } catch (...) {}`.

Closes: https://github.com/NixOS/nix/issues/6046
---
 src/libutil/util.cc | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index cd359cfee..8b317f6a8 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1358,11 +1358,15 @@ std::string shellEscape(const std::string_view s)
 
 void ignoreException()
 {
+    /* Make sure no exceptions leave this function.
+       printError() also throws when remote is closed. */
     try {
-        throw;
-    } catch (std::exception & e) {
-        printError("error (ignored): %1%", e.what());
-    }
+        try {
+            throw;
+        } catch (std::exception & e) {
+            printError("error (ignored): %1%", e.what());
+        }
+    } catch (...) { }
 }
 
 bool shouldANSI()

From 579dcbabd55d5c565ee9769efb6d4377f3022284 Mon Sep 17 00:00:00 2001
From: Sergei Trofimovich <slyich@gmail.com>
Date: Mon, 7 Feb 2022 23:35:34 +0000
Subject: [PATCH 517/567] mk: prefert inplace library paths to system ones
 (take 2)

It's a second attempt to merge the change. Previous attempt
was reverted in b976b34a5b05ba303904cc7b8e0a2579bdb52807.
Since then underlying failure exposed by original change was
fixed by https://github.com/NixOS/nix/pull/5354.

Below goes description of original change:

The link failure happens on a system with stable nix-2.3.15
installed in /usr/lib64 (it's libutil.so API differs from master):

```
LANG=C make V=1
g++ -o /home/slyfox/dev/git/nix/src/libstore/libnixstore.so \
    -shared -L/usr/lib64 -Wl,--no-copy-dt-needed-entries \
    src/libstore/binary-cache-store.o ... src/libstore/uds-remote-store.o \
    -lsqlite3 -lcurl -lsodium -pthread -ldl -lseccomp -Wl,-z,defs -Wl,-soname=libnixstore.so
      -Wl,-rpath,/home/slyfox/dev/git/nix/src/libutil -Lsrc/libutil -lnixutil
ld: src/libstore/binary-cache-store.o: in function `nix::BinaryCacheStore::BinaryCacheStore(
    std::map<std::__cxx11::basic_string<char, std::char_traits<char>, ...
nix/src/libstore/binary-cache-store.cc:30: undefined reference to `nix::readFile(
    std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)' ...
...
```

This happens due to `-L/usr/lib64 -Lsrc/libutil` search path ordering.
The change turns it into `-Lsrc/libutil -L/usr/lib64`.

Closes: https://github.com/NixOS/nix/issues/3087
---
 mk/libraries.mk | 4 ++--
 mk/programs.mk  | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/mk/libraries.mk b/mk/libraries.mk
index ffd7b5610..2a86565c9 100644
--- a/mk/libraries.mk
+++ b/mk/libraries.mk
@@ -91,7 +91,7 @@ define build-library
     $(1)_PATH := $$(_d)/$$($(1)_NAME).$(SO_EXT)
 
     $$($(1)_PATH): $$($(1)_OBJS) $$(_libs) | $$(_d)/
-	$$(trace-ld) $(CXX) -o $$(abspath $$@) -shared $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$($(1)_LDFLAGS_PROPAGATED) $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE)) $$($(1)_LDFLAGS_UNINSTALLED)
+	$$(trace-ld) $(CXX) -o $$(abspath $$@) -shared $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE)) $$($(1)_LDFLAGS_UNINSTALLED) $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$($(1)_LDFLAGS_PROPAGATED)
 
     ifndef HOST_DARWIN
       $(1)_LDFLAGS_USE += -Wl,-rpath,$$(abspath $$(_d))
@@ -105,7 +105,7 @@ define build-library
     $$(eval $$(call create-dir, $$($(1)_INSTALL_DIR)))
 
     $$($(1)_INSTALL_PATH): $$($(1)_OBJS) $$(_libs_final) | $(DESTDIR)$$($(1)_INSTALL_DIR)/
-	$$(trace-ld) $(CXX) -o $$@ -shared $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$($(1)_LDFLAGS_PROPAGATED) $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE_INSTALLED))
+	$$(trace-ld) $(CXX) -o $$@ -shared $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE_INSTALLED)) $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$($(1)_LDFLAGS_PROPAGATED)
 
     $(1)_LDFLAGS_USE_INSTALLED += -L$$(DESTDIR)$$($(1)_INSTALL_DIR) -l$$(patsubst lib%,%,$$(strip $$($(1)_NAME)))
     ifndef HOST_DARWIN
diff --git a/mk/programs.mk b/mk/programs.mk
index d0cf5baf0..70b09f0dd 100644
--- a/mk/programs.mk
+++ b/mk/programs.mk
@@ -32,7 +32,7 @@ define build-program
   $$(eval $$(call create-dir, $$(_d)))
 
   $$($(1)_PATH): $$($(1)_OBJS) $$(_libs) | $$(_d)/
-	$$(trace-ld) $(CXX) -o $$@ $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE))
+	$$(trace-ld) $(CXX) -o $$@ $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE)) $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS)
 
   $(1)_INSTALL_DIR ?= $$(bindir)
 
@@ -49,7 +49,7 @@ define build-program
       _libs_final := $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_INSTALL_PATH))
 
       $(DESTDIR)$$($(1)_INSTALL_PATH): $$($(1)_OBJS) $$(_libs_final) | $(DESTDIR)$$($(1)_INSTALL_DIR)/
-	$$(trace-ld) $(CXX) -o $$@ $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE_INSTALLED))
+	$$(trace-ld) $(CXX) -o $$@ $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE_INSTALLED)) $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS)
 
     else
 

From 28b9bd784ca8c7234693b7bca1ab393ed56f52d3 Mon Sep 17 00:00:00 2001
From: Sergei Trofimovich <slyich@gmail.com>
Date: Wed, 9 Feb 2022 13:00:53 +0000
Subject: [PATCH 518/567] Revert "mk: prefert inplace library paths to system
 ones (take 2)"

---
 mk/libraries.mk | 4 ++--
 mk/programs.mk  | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/mk/libraries.mk b/mk/libraries.mk
index 2a86565c9..ffd7b5610 100644
--- a/mk/libraries.mk
+++ b/mk/libraries.mk
@@ -91,7 +91,7 @@ define build-library
     $(1)_PATH := $$(_d)/$$($(1)_NAME).$(SO_EXT)
 
     $$($(1)_PATH): $$($(1)_OBJS) $$(_libs) | $$(_d)/
-	$$(trace-ld) $(CXX) -o $$(abspath $$@) -shared $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE)) $$($(1)_LDFLAGS_UNINSTALLED) $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$($(1)_LDFLAGS_PROPAGATED)
+	$$(trace-ld) $(CXX) -o $$(abspath $$@) -shared $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$($(1)_LDFLAGS_PROPAGATED) $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE)) $$($(1)_LDFLAGS_UNINSTALLED)
 
     ifndef HOST_DARWIN
       $(1)_LDFLAGS_USE += -Wl,-rpath,$$(abspath $$(_d))
@@ -105,7 +105,7 @@ define build-library
     $$(eval $$(call create-dir, $$($(1)_INSTALL_DIR)))
 
     $$($(1)_INSTALL_PATH): $$($(1)_OBJS) $$(_libs_final) | $(DESTDIR)$$($(1)_INSTALL_DIR)/
-	$$(trace-ld) $(CXX) -o $$@ -shared $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE_INSTALLED)) $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$($(1)_LDFLAGS_PROPAGATED)
+	$$(trace-ld) $(CXX) -o $$@ -shared $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$($(1)_LDFLAGS_PROPAGATED) $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE_INSTALLED))
 
     $(1)_LDFLAGS_USE_INSTALLED += -L$$(DESTDIR)$$($(1)_INSTALL_DIR) -l$$(patsubst lib%,%,$$(strip $$($(1)_NAME)))
     ifndef HOST_DARWIN
diff --git a/mk/programs.mk b/mk/programs.mk
index 70b09f0dd..d0cf5baf0 100644
--- a/mk/programs.mk
+++ b/mk/programs.mk
@@ -32,7 +32,7 @@ define build-program
   $$(eval $$(call create-dir, $$(_d)))
 
   $$($(1)_PATH): $$($(1)_OBJS) $$(_libs) | $$(_d)/
-	$$(trace-ld) $(CXX) -o $$@ $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE)) $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS)
+	$$(trace-ld) $(CXX) -o $$@ $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE))
 
   $(1)_INSTALL_DIR ?= $$(bindir)
 
@@ -49,7 +49,7 @@ define build-program
       _libs_final := $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_INSTALL_PATH))
 
       $(DESTDIR)$$($(1)_INSTALL_PATH): $$($(1)_OBJS) $$(_libs_final) | $(DESTDIR)$$($(1)_INSTALL_DIR)/
-	$$(trace-ld) $(CXX) -o $$@ $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE_INSTALLED)) $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS)
+	$$(trace-ld) $(CXX) -o $$@ $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE_INSTALLED))
 
     else
 

From b8d57e28839587832109f6607eb28819559fc30c Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 10 Feb 2022 11:10:29 +0100
Subject: [PATCH 519/567] check-hydra-status.sh: Improve error behaviour

---
 scripts/check-hydra-status.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/scripts/check-hydra-status.sh b/scripts/check-hydra-status.sh
index c1d2d7c40..7efe9cf97 100644
--- a/scripts/check-hydra-status.sh
+++ b/scripts/check-hydra-status.sh
@@ -19,9 +19,9 @@ for buildId in $BUILDS_FOR_LATEST_EVAL; do
   buildStatus=$(echo "$buildInfo" | \
     jq -r '.buildstatus')
 
-  if [[ "$buildStatus" -ne 0 ]]; then
+  if [[ $buildStatus != 0 ]]; then
     someBuildFailed=1
-    echo "Job “$(echo "$buildInfo" | jq -r '.job')” failed on hydra"
+    echo "Job “$(echo "$buildInfo" | jq -r '.job')” failed on hydra: $buildInfo"
   fi
 done
 

From 5b586575ac5ecb013be56135ecbcb091c8ad419d Mon Sep 17 00:00:00 2001
From: Maximilian Bosch <maximilian@mbosch.me>
Date: Thu, 10 Feb 2022 14:12:06 +0100
Subject: [PATCH 520/567] nix/why-depends: fix output when not using
 `--precise`
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

On Nix 2.6 the output of `nix why-depends --all` seems to be somewhat
off:

    $ nix why-depends /nix/store/kn47hayxab8gc01jhr98dwyywbx561aq-nixos-system-roflmayr-21.11.20220207.6c202a9.drv /nix/store/srn5jbs1q30jpybdmxqrwskyny659qgc-nix-2.6.drv --derivation  --extra-experimental-features nix-command  --all
    /nix/store/kn47hayxab8gc01jhr98dwyywbx561aq-nixos-system-roflmayr-21.11.20220207.6c202a9.drv
        └───/nix/store/g8bpgfjhh5vxrdq0w6r6s64f9kkm9z6c-etc.drv
        │   └───/nix/store/hm0jmhp8shbf3cl846a685nv4f5cp3fy-nspawn-inst.drv
        | [...]
            └───/nix/store/2d6q3ygiim9ijl5d4h0qqx6vnjgxywyr-system-units.drv
                └───/nix/store/dil014y1b8qyjhhhf5fpaah5fzdf0bzs-unit-systemd-nspawn-hydra.service.drv
                    └───/nix/store/a9r72wwx8qrxyp7hjydyg0gsrwnn26zb-activate.drv
                        └───/nix/store/99hlc7i4gl77wq087lbhag4hkf3kvssj-nixos-system-hydra-21.11pre-git.drv

Please note that `[...]-system-units.drv` is supposed to be a direct
child of `[...]-etc.drv`.

The reason for that is that each new level printed by `printNode` is
four spaces off in comparison to `nix why-depends --precise` because the
recursive `printNode()` only prints the path and not the `tree*`-chars in
the case of `--precise` and in this format the path is four spaces further
indented, i.e. on a newline, but on the same level as the path's children, i.e.

    /nix/store/kn47hayxab8gc01jhr98dwyywbx561aq-nixos-system-roflmayr-21.11.20220207.6c202a9.drv
    └───/: …1-p8.drv",["out"]),("/nix/store/g8bpgfjhh5vxrdq0w6r6s64f9kkm9z6c-etc.drv",["out"]),("/nix/store/…
        → /nix/store/g8bpgfjhh5vxrdq0w6r6s64f9kkm9z6c-etc.drv

As you can see `[...]-etc.drv` is a direct child of the root, but four
spaces indented. This logic was directly applied to the code-path with
`precise=false` which resulted in `tree*` being printed four spaces too
deep.

In case of no `--precise`, `hits[hash]` is empty and the path itself
should be printed rather than hits using the same logic as for `hits[hash]`.

With this fix, the output looks correct now:

    /nix/store/kn47hayxab8gc01jhr98dwyywbx561aq-nixos-system-roflmayr-21.11.20220207.6c202a9.drv
    └───/nix/store/g8bpgfjhh5vxrdq0w6r6s64f9kkm9z6c-etc.drv
        ├───/nix/store/hm0jmhp8shbf3cl846a685nv4f5cp3fy-nspawn-inst.drv
        | [...]
        └───/nix/store/2d6q3ygiim9ijl5d4h0qqx6vnjgxywyr-system-units.drv
            └───/nix/store/dil014y1b8qyjhhhf5fpaah5fzdf0bzs-unit-systemd-nspawn-hydra.service.drv
                └───/nix/store/a9r72wwx8qrxyp7hjydyg0gsrwnn26zb-activate.drv
                    └───/nix/store/99hlc7i4gl77wq087lbhag4hkf3kvssj-nixos-system-hydra-21.11pre-git.drv
---
 src/nix/why-depends.cc | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/src/nix/why-depends.cc b/src/nix/why-depends.cc
index 657df30d7..bc8cfb1c5 100644
--- a/src/nix/why-depends.cc
+++ b/src/nix/why-depends.cc
@@ -171,12 +171,6 @@ struct CmdWhyDepends : SourceExprCommand
                     node.visited ? "\e[38;5;244m" : "",
                     firstPad != "" ? "→ " : "",
                     pathS);
-            } else {
-                logger->cout("%s%s%s%s" ANSI_NORMAL,
-                    firstPad,
-                    node.visited ? "\e[38;5;244m" : "",
-                    firstPad != "" ? treeLast : "",
-                    pathS);
             }
 
             if (node.path == dependencyPath && !all
@@ -184,7 +178,7 @@ struct CmdWhyDepends : SourceExprCommand
                 throw BailOut();
 
             if (node.visited) return;
-            node.visited = true;
+            if (precise) node.visited = true;
 
             /* Sort the references by distance to `dependency` to
                ensure that the shortest path is printed first. */
@@ -267,6 +261,16 @@ struct CmdWhyDepends : SourceExprCommand
                     if (!all) break;
                 }
 
+                if (!precise) {
+                    auto pathS = store->printStorePath(ref.second->path);
+                    logger->cout("%s%s%s%s" ANSI_NORMAL,
+                        firstPad,
+                        ref.second->visited ? "\e[38;5;244m" : "",
+                        last ? treeLast : treeConn,
+                        pathS);
+                    node.visited = true;
+                }
+
                 printNode(*ref.second,
                     tailPad + (last ? treeNull : treeLine),
                     tailPad + (last ? treeNull : treeLine));
@@ -275,6 +279,9 @@ struct CmdWhyDepends : SourceExprCommand
 
         RunPager pager;
         try {
+            if (!precise) {
+                logger->cout("%s", store->printStorePath(graph.at(packagePath).path));
+            }
             printNode(graph.at(packagePath), "", "");
         } catch (BailOut & ) { }
     }

From 5b809f9e0e0fe84304c2ae0f5f7b2d4db02565ad Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 10 Feb 2022 21:15:07 +0100
Subject: [PATCH 521/567] check-hydra-status.sh: Ignore unfinished builds

---
 scripts/check-hydra-status.sh | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/scripts/check-hydra-status.sh b/scripts/check-hydra-status.sh
index 7efe9cf97..5e2f03429 100644
--- a/scripts/check-hydra-status.sh
+++ b/scripts/check-hydra-status.sh
@@ -16,8 +16,13 @@ someBuildFailed=0
 for buildId in $BUILDS_FOR_LATEST_EVAL; do
   buildInfo=$(curl -sS -H 'Accept: application/json' "https://hydra.nixos.org/build/$buildId")
 
-  buildStatus=$(echo "$buildInfo" | \
-    jq -r '.buildstatus')
+  finished=$(echo "$buildInfo" | jq -r '.finished')
+
+  if [[ $finished = 0 ]]; then
+    continue
+  fi
+
+  buildStatus=$(echo "$buildInfo" | jq -r '.buildstatus')
 
   if [[ $buildStatus != 0 ]]; then
     someBuildFailed=1

From d2f9a081b81ae0c4ef194fc66b94a31fb8ed6d73 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 11 Feb 2022 14:45:46 +0100
Subject: [PATCH 522/567] flake.nix: Fix indent

---
 flake.nix | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/flake.nix b/flake.nix
index 5b1e13a16..ae9305144 100644
--- a/flake.nix
+++ b/flake.nix
@@ -648,11 +648,10 @@
           installCheckFlags = "sysconfdir=$(out)/etc";
         };
       }) crossSystems)) // (builtins.listToAttrs (map (stdenvName:
-      nixpkgsFor.${system}.lib.nameValuePair
-        "nix-${stdenvName}"
-        nixpkgsFor.${system}."${stdenvName}Packages".nix
-      ) stdenvs))
-      );
+        nixpkgsFor.${system}.lib.nameValuePair
+          "nix-${stdenvName}"
+          nixpkgsFor.${system}."${stdenvName}Packages".nix
+      ) stdenvs)));
 
       defaultPackage = forAllSystems (system: self.packages.${system}.nix);
 

From cdc90c2776ee5542fd4d4e1aaa06d1d826daecb0 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 11 Feb 2022 15:50:12 +0100
Subject: [PATCH 523/567] parseInstallables(): Don't try the flake attr path
 prefixes when no fragment is specified

Fixes #5880.
---
 src/libcmd/installables.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index 5e8b62e1a..9f138b420 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -709,7 +709,7 @@ std::vector<std::shared_ptr<Installable>> SourceExprCommand::parseInstallables(
                         getEvalState(),
                         std::move(flakeRef),
                         fragment == "" ? getDefaultFlakeAttrPaths() : Strings{fragment},
-                        getDefaultFlakeAttrPathPrefixes(),
+                        fragment == "" ? Strings{} : getDefaultFlakeAttrPathPrefixes(),
                         lockFlags));
                 continue;
             } catch (...) {

From 270fb5f192c91977efd45e52ceac7f6002bc1422 Mon Sep 17 00:00:00 2001
From: Tom Bereknyei <tomberek@gmail.com>
Date: Fri, 11 Feb 2022 10:23:19 -0500
Subject: [PATCH 524/567] profile: add verbosity

warn if there are no matches and give notice of removing packages as
they are found
---
 src/nix/profile.cc | 34 ++++++++++++++++++++++++++--------
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/src/nix/profile.cc b/src/nix/profile.cc
index 9b7c999af..b9279414d 100644
--- a/src/nix/profile.cc
+++ b/src/nix/profile.cc
@@ -295,7 +295,11 @@ public:
         expectArgs("elements", &_matchers);
     }
 
-    typedef std::variant<size_t, Path, std::regex> Matcher;
+    struct RegexPattern {
+        std::string pattern;
+        std::regex  reg;
+    };
+    typedef std::variant<size_t, Path, RegexPattern> Matcher;
 
     std::vector<Matcher> getMatchers(ref<Store> store)
     {
@@ -307,7 +311,7 @@ public:
             else if (store->isStorePath(s))
                 res.push_back(s);
             else
-                res.push_back(std::regex(s, std::regex::extended | std::regex::icase));
+                res.push_back(RegexPattern{s,std::regex(s, std::regex::extended | std::regex::icase)});
         }
 
         return res;
@@ -320,9 +324,9 @@ public:
                 if (*n == pos) return true;
             } else if (auto path = std::get_if<Path>(&matcher)) {
                 if (element.storePaths.count(store.parseStorePath(*path))) return true;
-            } else if (auto regex = std::get_if<std::regex>(&matcher)) {
+            } else if (auto regex = std::get_if<RegexPattern>(&matcher)) {
                 if (element.source
-                    && std::regex_match(element.source->attrPath, *regex))
+                    && std::regex_match(element.source->attrPath, regex->reg))
                     return true;
             }
         }
@@ -355,16 +359,30 @@ struct CmdProfileRemove : virtual EvalCommand, MixDefaultProfile, MixProfileElem
 
         for (size_t i = 0; i < oldManifest.elements.size(); ++i) {
             auto & element(oldManifest.elements[i]);
-            if (!matches(*store, element, i, matchers))
+            if (!matches(*store, element, i, matchers)) {
                 newManifest.elements.push_back(std::move(element));
+            } else {
+                notice("removing '%s'", element.describe());
+            }
         }
 
-        // FIXME: warn about unused matchers?
-
+        auto removedCount = oldManifest.elements.size() - newManifest.elements.size();
         printInfo("removed %d packages, kept %d packages",
-            oldManifest.elements.size() - newManifest.elements.size(),
+            removedCount,
             newManifest.elements.size());
 
+        if (removedCount == 0) {
+            for (auto matcher: matchers) {
+                if (const size_t* index = std::get_if<size_t>(&matcher)){
+                    warn("'%d' is not a valid index in profile", *index);
+                } else if (const Path* path = std::get_if<Path>(&matcher)){
+                    warn("'%s' does not match any paths in profile", *path);
+                } else if (const RegexPattern* regex = std::get_if<RegexPattern>(&matcher)){
+                    warn("'%s' does not match any packages in profile", regex->pattern);
+                }
+            }
+            warn ("Try `nix profile list` to see the current profile.");
+        }
         updateProfile(newManifest.build(store));
     }
 };

From c437e1326d900e2563c5859489f3be2cb557a3d3 Mon Sep 17 00:00:00 2001
From: Sebastian Ullrich <sebasti@nullri.ch>
Date: Sat, 12 Feb 2022 16:28:36 +0100
Subject: [PATCH 525/567] Fix using sandbox without user namespaces

---
 src/libstore/build/local-derivation-goal.cc | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 0d0afea2d..b76ad702b 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -912,9 +912,12 @@ void LocalDerivationGoal::startBuilder()
         sandboxMountNamespace = open(fmt("/proc/%d/ns/mnt", (pid_t) pid).c_str(), O_RDONLY);
         if (sandboxMountNamespace.get() == -1)
             throw SysError("getting sandbox mount namespace");
-        sandboxUserNamespace = open(fmt("/proc/%d/ns/user", (pid_t) pid).c_str(), O_RDONLY);
-        if (sandboxUserNamespace.get() == -1)
-            throw SysError("getting sandbox user namespace");
+
+        if (usingUserNamespace) {
+            sandboxUserNamespace = open(fmt("/proc/%d/ns/user", (pid_t) pid).c_str(), O_RDONLY);
+            if (sandboxUserNamespace.get() == -1)
+                throw SysError("getting sandbox user namespace");
+        }
 
         /* Signal the builder that we've updated its user namespace. */
         writeFull(userNamespaceSync.writeSide.get(), "1");

From 023e45977745ffd6c16eec299a00affd65176669 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 14 Feb 2022 20:39:44 +0100
Subject: [PATCH 526/567] InstallableFlake: Default attr paths cleanup

This removes some duplicated logic, and fixes "nix bundle" parsing its
installable twice.
---
 src/libcmd/installables.cc | 16 ++++++++++------
 src/libcmd/installables.hh |  5 +++--
 src/nix/bundle.cc          | 19 +++++++------------
 src/nix/develop.cc         |  3 ++-
 src/nix/flake.cc           | 15 +++++++++------
 src/nix/profile.cc         |  1 +
 6 files changed, 32 insertions(+), 27 deletions(-)

diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index 9f138b420..644954977 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -545,13 +545,14 @@ InstallableFlake::InstallableFlake(
     SourceExprCommand * cmd,
     ref<EvalState> state,
     FlakeRef && flakeRef,
-    Strings && attrPaths,
-    Strings && prefixes,
+    std::string_view fragment,
+    Strings attrPaths,
+    Strings prefixes,
     const flake::LockFlags & lockFlags)
     : InstallableValue(state),
       flakeRef(flakeRef),
-      attrPaths(attrPaths),
-      prefixes(prefixes),
+      attrPaths(fragment == "" ? attrPaths : Strings{(std::string) fragment}),
+      prefixes(fragment == "" ? Strings{} : prefixes),
       lockFlags(lockFlags)
 {
     if (cmd && cmd->getAutoArgs(*state)->size())
@@ -566,6 +567,8 @@ std::tuple<std::string, FlakeRef, InstallableValue::DerivationInfo> InstallableF
     auto root = cache->getRoot();
 
     for (auto & attrPath : getActualAttrPaths()) {
+        debug("trying flake output attribute '%s'", attrPath);
+
         auto attr = root->findAlongAttrPath(
             parseAttrPath(*state, attrPath),
             true
@@ -708,8 +711,9 @@ std::vector<std::shared_ptr<Installable>> SourceExprCommand::parseInstallables(
                         this,
                         getEvalState(),
                         std::move(flakeRef),
-                        fragment == "" ? getDefaultFlakeAttrPaths() : Strings{fragment},
-                        fragment == "" ? Strings{} : getDefaultFlakeAttrPathPrefixes(),
+                        fragment,
+                        getDefaultFlakeAttrPaths(),
+                        getDefaultFlakeAttrPathPrefixes(),
                         lockFlags));
                 continue;
             } catch (...) {
diff --git a/src/libcmd/installables.hh b/src/libcmd/installables.hh
index ced6b3f10..3d2563e4b 100644
--- a/src/libcmd/installables.hh
+++ b/src/libcmd/installables.hh
@@ -102,8 +102,9 @@ struct InstallableFlake : InstallableValue
         SourceExprCommand * cmd,
         ref<EvalState> state,
         FlakeRef && flakeRef,
-        Strings && attrPaths,
-        Strings && prefixes,
+        std::string_view fragment,
+        Strings attrPaths,
+        Strings prefixes,
         const flake::LockFlags & lockFlags);
 
     std::string what() const override { return flakeRef.to_string() + "#" + *attrPaths.begin(); }
diff --git a/src/nix/bundle.cc b/src/nix/bundle.cc
index 113ceca33..c13018328 100644
--- a/src/nix/bundle.cc
+++ b/src/nix/bundle.cc
@@ -74,21 +74,16 @@ struct CmdBundle : InstallableCommand
     {
         auto evalState = getEvalState();
 
-        auto [progFlakeRef, progName] = parseFlakeRefWithFragment(installable->what(), absPath("."));
-        const flake::LockFlags lockFlagsProg{ .writeLockFile = false };
-        auto programInstallable = InstallableFlake(this,
-            evalState, std::move(progFlakeRef),
-            Strings{progName == "" ? "defaultApp" : progName},
-            Strings(this->getDefaultFlakeAttrPathPrefixes()),
-            lockFlagsProg);
-        auto val = programInstallable.toValue(*evalState).first;
+        auto val = installable->toValue(*evalState).first;
 
         auto [bundlerFlakeRef, bundlerName] = parseFlakeRefWithFragment(bundler, absPath("."));
         const flake::LockFlags lockFlags{ .writeLockFile = false };
-        auto bundler = InstallableFlake(this,
-            evalState, std::move(bundlerFlakeRef),
-            Strings{bundlerName == "" ? "defaultBundler." + settings.thisSystem.get() : settings.thisSystem.get() + "." + bundlerName, bundlerName},
-            Strings({"","bundlers."}), lockFlags);
+        InstallableFlake bundler{this,
+            evalState, std::move(bundlerFlakeRef), bundlerName,
+            {"defaultBundler." + settings.thisSystem.get()},
+            {"bundlers." + settings.thisSystem.get() + "."},
+            lockFlags
+        };
 
         auto vRes = evalState->allocValue();
         evalState->callFunction(*bundler.toValue(*evalState).first, *val, *vRes, noPos);
diff --git a/src/nix/develop.cc b/src/nix/develop.cc
index 42e13436a..f88f5909c 100644
--- a/src/nix/develop.cc
+++ b/src/nix/develop.cc
@@ -498,7 +498,8 @@ struct CmdDevelop : Common, MixEnvironment
                 this,
                 state,
                 installable->nixpkgsFlakeRef(),
-                Strings{"bashInteractive"},
+                "bashInteractive",
+                Strings{},
                 Strings{"legacyPackages." + settings.thisSystem.get() + "."},
                 nixpkgsLockFlags);
 
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 4bc79820c..3effce2c1 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -649,12 +649,14 @@ struct CmdFlakeCheck : FlakeCommand
     }
 };
 
+static Strings defaultTemplateAttrPathsPrefixes{"templates."};
+static Strings defaultTemplateAttrPaths = {"defaultTemplate"};
+
 struct CmdFlakeInitCommon : virtual Args, EvalCommand
 {
     std::string templateUrl = "templates";
     Path destDir;
 
-    const Strings attrsPathPrefixes{"templates."};
     const LockFlags lockFlags{ .writeLockFile = false };
 
     CmdFlakeInitCommon()
@@ -669,8 +671,8 @@ struct CmdFlakeInitCommon : virtual Args, EvalCommand
                 completeFlakeRefWithFragment(
                     getEvalState(),
                     lockFlags,
-                    attrsPathPrefixes,
-                    {"defaultTemplate"},
+                    defaultTemplateAttrPathsPrefixes,
+                    defaultTemplateAttrPaths,
                     prefix);
             }}
         });
@@ -685,9 +687,10 @@ struct CmdFlakeInitCommon : virtual Args, EvalCommand
         auto [templateFlakeRef, templateName] = parseFlakeRefWithFragment(templateUrl, absPath("."));
 
         auto installable = InstallableFlake(nullptr,
-            evalState, std::move(templateFlakeRef),
-            Strings{templateName == "" ? "defaultTemplate" : templateName},
-            Strings(attrsPathPrefixes), lockFlags);
+            evalState, std::move(templateFlakeRef), templateName,
+            defaultTemplateAttrPaths,
+            defaultTemplateAttrPathsPrefixes,
+            lockFlags);
 
         auto [cursor, attrPath] = installable.getCursor(*evalState);
 
diff --git a/src/nix/profile.cc b/src/nix/profile.cc
index b9279414d..55b5ff736 100644
--- a/src/nix/profile.cc
+++ b/src/nix/profile.cc
@@ -423,6 +423,7 @@ struct CmdProfileUpgrade : virtual SourceExprCommand, MixDefaultProfile, MixProf
                     this,
                     getEvalState(),
                     FlakeRef(element.source->originalRef),
+                    "",
                     {element.source->attrPath},
                     {},
                     lockFlags);

From 72e8f94081290784e2d115cfbf09375b53d8cbe9 Mon Sep 17 00:00:00 2001
From: Gabriel Fontes <eu@misterio.me>
Date: Wed, 6 Oct 2021 13:32:46 -0300
Subject: [PATCH 527/567] add sourcehut input scheme

---
 src/libfetchers/github.cc | 91 ++++++++++++++++++++++++++++++++++++++-
 src/nix/flake.md          | 32 ++++++++++++++
 2 files changed, 122 insertions(+), 1 deletion(-)

diff --git a/src/libfetchers/github.cc b/src/libfetchers/github.cc
index 1c539b80e..e101aa3d6 100644
--- a/src/libfetchers/github.cc
+++ b/src/libfetchers/github.cc
@@ -8,6 +8,7 @@
 
 #include <optional>
 #include <nlohmann/json.hpp>
+#include <fstream>
 
 namespace nix::fetchers {
 
@@ -17,7 +18,7 @@ struct DownloadUrl
     Headers headers;
 };
 
-// A github or gitlab host
+// A github, gitlab, or sourcehut host
 const static std::string hostRegexS = "[a-zA-Z0-9.]*"; // FIXME: check
 std::regex hostRegex(hostRegexS, std::regex::ECMAScript);
 
@@ -348,7 +349,95 @@ struct GitLabInputScheme : GitArchiveInputScheme
     }
 };
 
+struct SourceHutInputScheme : GitArchiveInputScheme
+{
+    std::string type() override { return "sourcehut"; }
+
+    std::optional<std::pair<std::string, std::string>> accessHeaderFromToken(const std::string & token) const override
+    {
+        // SourceHut supports both PAT and OAuth2. See
+        // https://man.sr.ht/meta.sr.ht/oauth.md
+        return std::pair<std::string, std::string>("Authorization", fmt("Bearer %s", token));
+        // Note: This currently serves no purpose, as this kind of authorization
+        // does not allow for downloading tarballs on sourcehut private repos.
+        // Once it is implemented, however, should work as expected.
+    }
+
+    Hash getRevFromRef(nix::ref<Store> store, const Input & input) const override
+    {
+        // TODO: In the future, when the sourcehut graphql API is implemented for mercurial
+        // and with anonymous access, this method should use it instead.
+
+        auto ref = *input.getRef();
+
+        auto host = maybeGetStrAttr(input.attrs, "host").value_or("git.sr.ht");
+        auto base_url = fmt("https://%s/%s/%s",
+            host, getStrAttr(input.attrs, "owner"), getStrAttr(input.attrs, "repo"));
+
+        Headers headers = makeHeadersWithAuthTokens(host);
+
+        std::string ref_uri;
+        if (ref == "HEAD") {
+            auto file = store->toRealPath(
+                downloadFile(store, fmt("%s/HEAD", base_url), "source", false, headers).storePath);
+            std::ifstream is(file);
+            std::string line;
+            getline(is, line);
+
+            auto ref_index = line.find("ref: ");
+            if (ref_index == std::string::npos) {
+                throw BadURL("in '%d', couldn't resolve HEAD ref '%d'", input.to_string(), ref);
+            }
+
+            ref_uri = line.substr(ref_index+5, line.length()-1);
+        } else
+            ref_uri = fmt("refs/heads/%s", ref);
+
+        auto file = store->toRealPath(
+            downloadFile(store, fmt("%s/info/refs", base_url), "source", false, headers).storePath);
+        std::ifstream is(file);
+
+        std::string line;
+        std::string id;
+        while(getline(is, line)) {
+            auto index = line.find(ref_uri);
+            if (index != std::string::npos) {
+                id = line.substr(0, index-1);
+                break;
+            }
+        }
+
+        if(id.empty())
+            throw BadURL("in '%d', couldn't find ref '%d'", input.to_string(), ref);
+
+        auto rev = Hash::parseAny(id, htSHA1);
+        debug("HEAD revision for '%s' is %s", fmt("%s/%s", base_url, ref), rev.gitRev());
+        return rev;
+    }
+
+    DownloadUrl getDownloadUrl(const Input & input) const override
+    {
+        auto host = maybeGetStrAttr(input.attrs, "host").value_or("git.sr.ht");
+        auto url = fmt("https://%s/%s/%s/archive/%s.tar.gz",
+            host, getStrAttr(input.attrs, "owner"), getStrAttr(input.attrs, "repo"),
+            input.getRev()->to_string(Base16, false));
+
+        Headers headers = makeHeadersWithAuthTokens(host);
+        return DownloadUrl { url, headers };
+    }
+
+    void clone(const Input & input, const Path & destDir) override
+    {
+        auto host = maybeGetStrAttr(input.attrs, "host").value_or("git.sr.ht");
+        Input::fromURL(fmt("git+https://%s/%s/%s",
+                host, getStrAttr(input.attrs, "owner"), getStrAttr(input.attrs, "repo")))
+            .applyOverrides(input.getRef(), input.getRev())
+            .clone(destDir);
+    }
+};
+
 static auto rGitHubInputScheme = OnStartup([] { registerInputScheme(std::make_unique<GitHubInputScheme>()); });
 static auto rGitLabInputScheme = OnStartup([] { registerInputScheme(std::make_unique<GitLabInputScheme>()); });
+static auto rSourceHutInputScheme = OnStartup([] { registerInputScheme(std::make_unique<SourceHutInputScheme>()); });
 
 }
diff --git a/src/nix/flake.md b/src/nix/flake.md
index accddd436..f539a7c28 100644
--- a/src/nix/flake.md
+++ b/src/nix/flake.md
@@ -209,6 +209,38 @@ Currently the `type` attribute can be one of the following:
   * `github:edolstra/dwarffs/unstable`
   * `github:edolstra/dwarffs/d3f2baba8f425779026c6ec04021b2e927f61e31`
 
+* `sourcehut`: Similar to `github`, is a more efficient way to fetch
+  SourceHut repositories. The following attributes are required:
+
+  * `owner`: The owner of the repository (including leading `~`).
+
+  * `repo`: The name of the repository.
+
+  Like `github`, these are downloaded as tarball archives.
+
+  The URL syntax for `sourcehut` flakes is:
+
+  `sourcehut:<owner>/<repo>(/<rev-or-ref>)?(\?<params>)?`
+
+  `<rev-or-ref>` works the same as `github`. Either a branch or tag name
+  (`ref`), or a commit hash (`rev`) can be specified.
+
+  Since SourceHut allows for self-hosting, you can specify `host` as
+  a parameter, to point to any instances other than `git.sr.ht`.
+
+  Currently, `ref` name resolution only works for Git repositories.
+  You can refer to Mercurial repositories by simply changing `host` to
+  `hg.sr.ht` (or any other Mercurial instance). With the caveat
+  that you must explicitly specify a commit hash (`rev`).
+
+  Some examples:
+
+  * `sourcehut:~misterio/nix-colors`
+  * `sourcehut:~misterio/nix-colors/main`
+  * `sourcehut:~misterio/nix-colors?host=git.example.org`
+  * `sourcehut:~misterio/nix-colors/182b4b8709b8ffe4e9774a4c5d6877bf6bb9a21c`
+  * `sourcehut:~misterio/nix-colors/21c1a380a6915d890d408e9f22203436a35bb2de?host=hg.sr.ht`
+
 * `indirect`: Indirections through the flake registry. These have the
   form
 

From f3a2940e70dea2c35dcae3fca019e94bf8758b4d Mon Sep 17 00:00:00 2001
From: Taeer Bar-Yam <taeer@bar-yam.me>
Date: Tue, 15 Feb 2022 11:50:14 -0500
Subject: [PATCH 528/567] add descriptive output when creating templates

this includes a `welcomeText` attribute which can be set in the
template, as well as outputing which files were created.
---
 src/nix/flake-init.md | 8 ++++++++
 src/nix/flake.cc      | 6 ++++++
 2 files changed, 14 insertions(+)

diff --git a/src/nix/flake-init.md b/src/nix/flake-init.md
index 890038016..c8bcee375 100644
--- a/src/nix/flake-init.md
+++ b/src/nix/flake-init.md
@@ -37,6 +37,10 @@ A flake can declare templates through its `templates` and
 
 * `path`: The path of the directory to be copied.
 
+* `welcomeText`: A block of text to display when a user initializes a new flake
+  based on this template.
+
+
 Here is an example:
 
 ```
@@ -45,6 +49,10 @@ outputs = { self }: {
   templates.rust = {
     path = ./rust;
     description = "A simple Rust/Cargo project";
+    welcomeText = ''
+      You've created a simple Rust/Cargo template.
+      Visit https://www.rust-lang.org/ for more info.
+    '';
   };
 
   templates.defaultTemplate = self.templates.rust;
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 4bc79820c..f5d34c10f 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -728,6 +728,7 @@ struct CmdFlakeInitCommon : virtual Args, EvalCommand
                 else
                     throw Error("file '%s' has unsupported type", from2);
                 files.push_back(to2);
+                notice("wrote: %s", to2);
             }
         };
 
@@ -738,6 +739,11 @@ struct CmdFlakeInitCommon : virtual Args, EvalCommand
             for (auto & s : files) args.push_back(s);
             runProgram("git", true, args);
         }
+        auto welcomeText = cursor->maybeGetAttr("welcomeText");
+        if (welcomeText) {
+            notice("\n----------\n");
+            notice(welcomeText->getString());
+        }
     }
 };
 

From d82cf4a016aa0ee136ff62635e909607de78e02a Mon Sep 17 00:00:00 2001
From: Rahul Butani <rrbutani@users.noreply.github.com>
Date: Tue, 15 Feb 2022 15:44:05 -0600
Subject: [PATCH 529/567] manual: fix formatting for options with
 "machine-specific" defaults

---
 doc/manual/generate-options.nix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/manual/generate-options.nix b/doc/manual/generate-options.nix
index 9a77f4d36..84d90beb6 100644
--- a/doc/manual/generate-options.nix
+++ b/doc/manual/generate-options.nix
@@ -20,7 +20,7 @@ concatStrings (map
          # JSON, but that converts to "{ }" here.
          (if isAttrs option.value then "`\"\"`"
           else "`" + toString option.value + "`")) + "\n\n"
-       else "    **Default:** *machine-specific*")
+       else "    **Default:** *machine-specific*\n")
     + (if option.aliases != []
        then "    **Deprecated alias:** " + (concatStringsSep ", " (map (s: "`${s}`") option.aliases)) + "\n\n"
        else "")

From 2d6d9a28ebb17b1ba1fe0dc4d56b6aa311f94d39 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 15 Feb 2022 15:08:06 +0100
Subject: [PATCH 530/567] addToStoreFromDump(): Take std::string_view

---
 src/libstore/binary-cache-store.cc          | 2 +-
 src/libstore/binary-cache-store.hh          | 4 ++--
 src/libstore/build/local-derivation-goal.cc | 2 +-
 src/libstore/local-store.cc                 | 2 +-
 src/libstore/local-store.hh                 | 2 +-
 src/libstore/remote-store.cc                | 4 ++--
 src/libstore/remote-store.hh                | 4 ++--
 src/libstore/store-api.hh                   | 2 +-
 8 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index 6e4458f7a..b3fd991a1 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -307,7 +307,7 @@ void BinaryCacheStore::addToStore(const ValidPathInfo & info, Source & narSource
     }});
 }
 
-StorePath BinaryCacheStore::addToStoreFromDump(Source & dump, const string & name,
+StorePath BinaryCacheStore::addToStoreFromDump(Source & dump, std::string_view name,
     FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, const StorePathSet & references)
 {
     if (method != FileIngestionMethod::Recursive || hashAlgo != htSHA256)
diff --git a/src/libstore/binary-cache-store.hh b/src/libstore/binary-cache-store.hh
index 7599230d9..5b5d064f3 100644
--- a/src/libstore/binary-cache-store.hh
+++ b/src/libstore/binary-cache-store.hh
@@ -98,8 +98,8 @@ public:
     void addToStore(const ValidPathInfo & info, Source & narSource,
         RepairFlag repair, CheckSigsFlag checkSigs) override;
 
-    StorePath addToStoreFromDump(Source & dump, const string & name,
-        FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, const StorePathSet & references ) override;
+    StorePath addToStoreFromDump(Source & dump, std::string_view name,
+        FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, const StorePathSet & references) override;
 
     StorePath addToStore(const string & name, const Path & srcPath,
         FileIngestionMethod method, HashType hashAlgo,
diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index b76ad702b..8861d2c7b 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -1208,7 +1208,7 @@ struct RestrictedStore : public virtual RestrictedStoreConfig, public virtual Lo
         return path;
     }
 
-    StorePath addToStoreFromDump(Source & dump, const string & name,
+    StorePath addToStoreFromDump(Source & dump, std::string_view name,
         FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair,
         const StorePathSet & references = StorePathSet()) override
     {
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 284e385e6..1a02b916a 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -1318,7 +1318,7 @@ void LocalStore::addToStore(const ValidPathInfo & info, Source & source,
 }
 
 
-StorePath LocalStore::addToStoreFromDump(Source & source0, const string & name,
+StorePath LocalStore::addToStoreFromDump(Source & source0, std::string_view name,
     FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, const StorePathSet & references)
 {
     /* For computing the store path. */
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 8cf9c68b3..46aed9bcb 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -144,7 +144,7 @@ public:
     void addToStore(const ValidPathInfo & info, Source & source,
         RepairFlag repair, CheckSigsFlag checkSigs) override;
 
-    StorePath addToStoreFromDump(Source & dump, const string & name,
+    StorePath addToStoreFromDump(Source & dump, std::string_view name,
         FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, const StorePathSet & references) override;
 
     StorePath addTextToStore(const string & name, const string & s,
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index 573becfbd..c6f083dea 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -500,7 +500,7 @@ std::optional<StorePath> RemoteStore::queryPathFromHashPart(const std::string &
 
 ref<const ValidPathInfo> RemoteStore::addCAToStore(
     Source & dump,
-    const string & name,
+    std::string_view name,
     ContentAddressMethod caMethod,
     const StorePathSet & references,
     RepairFlag repair)
@@ -582,7 +582,7 @@ ref<const ValidPathInfo> RemoteStore::addCAToStore(
 }
 
 
-StorePath RemoteStore::addToStoreFromDump(Source & dump, const string & name,
+StorePath RemoteStore::addToStoreFromDump(Source & dump, std::string_view name,
       FileIngestionMethod method, HashType hashType, RepairFlag repair, const StorePathSet & references)
 {
     return addCAToStore(dump, name, FixedOutputHashMethod{ .fileIngestionMethod = method, .hashType = hashType }, references, repair)->path;
diff --git a/src/libstore/remote-store.hh b/src/libstore/remote-store.hh
index b91d25fa9..55cfd5cc6 100644
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@@ -66,13 +66,13 @@ public:
     /* Add a content-addressable store path. `dump` will be drained. */
     ref<const ValidPathInfo> addCAToStore(
         Source & dump,
-        const string & name,
+        std::string_view name,
         ContentAddressMethod caMethod,
         const StorePathSet & references,
         RepairFlag repair);
 
     /* Add a content-addressable store path. Does not support references. `dump` will be drained. */
-    StorePath addToStoreFromDump(Source & dump, const string & name,
+    StorePath addToStoreFromDump(Source & dump, std::string_view name,
         FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair, const StorePathSet & references = StorePathSet()) override;
 
     void addToStore(const ValidPathInfo & info, Source & nar,
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 4068f8f35..90d2e93ed 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -499,7 +499,7 @@ public:
        false).
        `dump` may be drained */
     // FIXME: remove?
-    virtual StorePath addToStoreFromDump(Source & dump, const string & name,
+    virtual StorePath addToStoreFromDump(Source & dump, std::string_view name,
         FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair,
         const StorePathSet & references = StorePathSet())
     { unsupported("addToStoreFromDump"); }

From aa5b83d93ce1b7bb67bf81ceda7ebf7706b1efa0 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 15 Feb 2022 14:33:31 +0100
Subject: [PATCH 531/567] InputScheme::fetch(): Return a StorePath instead of a
 Tree

---
 src/libfetchers/fetchers.cc  | 12 ++++++------
 src/libfetchers/fetchers.hh  |  3 +--
 src/libfetchers/git.cc       | 14 ++++----------
 src/libfetchers/github.cc    |  9 +++------
 src/libfetchers/indirect.cc  |  2 +-
 src/libfetchers/mercurial.cc | 14 ++++----------
 src/libfetchers/path.cc      |  7 ++-----
 src/libfetchers/tarball.cc   |  8 ++++----
 8 files changed, 25 insertions(+), 44 deletions(-)

diff --git a/src/libfetchers/fetchers.cc b/src/libfetchers/fetchers.cc
index e158d914b..c06ccb929 100644
--- a/src/libfetchers/fetchers.cc
+++ b/src/libfetchers/fetchers.cc
@@ -124,15 +124,13 @@ std::pair<Tree, Input> Input::fetch(ref<Store> store) const
             debug("using substituted/cached input '%s' in '%s'",
                 to_string(), store->printStorePath(storePath));
 
-            auto actualPath = store->toRealPath(storePath);
-
-            return {fetchers::Tree(std::move(actualPath), std::move(storePath)), *this};
+            return {Tree { .actualPath = store->toRealPath(storePath), .storePath = std::move(storePath) }, *this};
         } catch (Error & e) {
             debug("substitution of input '%s' failed: %s", to_string(), e.what());
         }
     }
 
-    auto [tree, input] = [&]() -> std::pair<Tree, Input> {
+    auto [storePath, input] = [&]() -> std::pair<StorePath, Input> {
         try {
             return scheme->fetch(store, *this);
         } catch (Error & e) {
@@ -141,8 +139,10 @@ std::pair<Tree, Input> Input::fetch(ref<Store> store) const
         }
     }();
 
-    if (tree.actualPath == "")
-        tree.actualPath = store->toRealPath(tree.storePath);
+    Tree tree {
+        .actualPath = store->toRealPath(storePath),
+        .storePath = storePath,
+    };
 
     auto narHash = store->queryPathInfo(tree.storePath)->narHash;
     input.attrs.insert_or_assign("narHash", narHash.to_string(SRI, true));
diff --git a/src/libfetchers/fetchers.hh b/src/libfetchers/fetchers.hh
index c43b047a7..2836af5fa 100644
--- a/src/libfetchers/fetchers.hh
+++ b/src/libfetchers/fetchers.hh
@@ -16,7 +16,6 @@ struct Tree
 {
     Path actualPath;
     StorePath storePath;
-    Tree(Path && actualPath, StorePath && storePath) : actualPath(actualPath), storePath(std::move(storePath)) {}
 };
 
 struct InputScheme;
@@ -131,7 +130,7 @@ struct InputScheme
 
     virtual void markChangedFile(const Input & input, std::string_view file, std::optional<std::string> commitMsg);
 
-    virtual std::pair<Tree, Input> fetch(ref<Store> store, const Input & input) = 0;
+    virtual std::pair<StorePath, Input> fetch(ref<Store> store, const Input & input) = 0;
 };
 
 void registerInputScheme(std::shared_ptr<InputScheme> && fetcher);
diff --git a/src/libfetchers/git.cc b/src/libfetchers/git.cc
index 544d2ffbf..c3f0f8c8f 100644
--- a/src/libfetchers/git.cc
+++ b/src/libfetchers/git.cc
@@ -172,7 +172,7 @@ struct GitInputScheme : InputScheme
         return {isLocal, isLocal ? url.path : url.base};
     }
 
-    std::pair<Tree, Input> fetch(ref<Store> store, const Input & _input) override
+    std::pair<StorePath, Input> fetch(ref<Store> store, const Input & _input) override
     {
         Input input(_input);
 
@@ -197,17 +197,14 @@ struct GitInputScheme : InputScheme
         };
 
         auto makeResult = [&](const Attrs & infoAttrs, StorePath && storePath)
-            -> std::pair<Tree, Input>
+            -> std::pair<StorePath, Input>
         {
             assert(input.getRev());
             assert(!_input.getRev() || _input.getRev() == input.getRev());
             if (!shallow)
                 input.attrs.insert_or_assign("revCount", getIntAttr(infoAttrs, "revCount"));
             input.attrs.insert_or_assign("lastModified", getIntAttr(infoAttrs, "lastModified"));
-            return {
-                Tree(store->toRealPath(storePath), std::move(storePath)),
-                input
-            };
+            return {std::move(storePath), input};
         };
 
         if (input.getRev()) {
@@ -285,10 +282,7 @@ struct GitInputScheme : InputScheme
                     "lastModified",
                     haveCommits ? std::stoull(runProgram("git", true, { "-C", actualUrl, "log", "-1", "--format=%ct", "--no-show-signature", "HEAD" })) : 0);
 
-                return {
-                    Tree(store->toRealPath(storePath), std::move(storePath)),
-                    input
-                };
+                return {std::move(storePath), input};
             }
         }
 
diff --git a/src/libfetchers/github.cc b/src/libfetchers/github.cc
index 1c539b80e..8ba6935f9 100644
--- a/src/libfetchers/github.cc
+++ b/src/libfetchers/github.cc
@@ -180,7 +180,7 @@ struct GitArchiveInputScheme : InputScheme
 
     virtual DownloadUrl getDownloadUrl(const Input & input) const = 0;
 
-    std::pair<Tree, Input> fetch(ref<Store> store, const Input & _input) override
+    std::pair<StorePath, Input> fetch(ref<Store> store, const Input & _input) override
     {
         Input input(_input);
 
@@ -199,10 +199,7 @@ struct GitArchiveInputScheme : InputScheme
 
         if (auto res = getCache()->lookup(store, immutableAttrs)) {
             input.attrs.insert_or_assign("lastModified", getIntAttr(res->first, "lastModified"));
-            return {
-                Tree(store->toRealPath(res->second), std::move(res->second)),
-                input
-            };
+            return {std::move(res->second), input};
         }
 
         auto url = getDownloadUrl(input);
@@ -221,7 +218,7 @@ struct GitArchiveInputScheme : InputScheme
             tree.storePath,
             true);
 
-        return {std::move(tree), input};
+        return {std::move(tree.storePath), input};
     }
 };
 
diff --git a/src/libfetchers/indirect.cc b/src/libfetchers/indirect.cc
index 10e59919a..9288fc6cf 100644
--- a/src/libfetchers/indirect.cc
+++ b/src/libfetchers/indirect.cc
@@ -94,7 +94,7 @@ struct IndirectInputScheme : InputScheme
         return input;
     }
 
-    std::pair<Tree, Input> fetch(ref<Store> store, const Input & input) override
+    std::pair<StorePath, Input> fetch(ref<Store> store, const Input & input) override
     {
         throw Error("indirect input '%s' cannot be fetched directly", input.to_string());
     }
diff --git a/src/libfetchers/mercurial.cc b/src/libfetchers/mercurial.cc
index d52d4641b..5123bcda4 100644
--- a/src/libfetchers/mercurial.cc
+++ b/src/libfetchers/mercurial.cc
@@ -143,7 +143,7 @@ struct MercurialInputScheme : InputScheme
         return {isLocal, isLocal ? url.path : url.base};
     }
 
-    std::pair<Tree, Input> fetch(ref<Store> store, const Input & _input) override
+    std::pair<StorePath, Input> fetch(ref<Store> store, const Input & _input) override
     {
         Input input(_input);
 
@@ -193,10 +193,7 @@ struct MercurialInputScheme : InputScheme
 
                 auto storePath = store->addToStore(input.getName(), actualUrl, FileIngestionMethod::Recursive, htSHA256, filter);
 
-                return {
-                    Tree(store->toRealPath(storePath), std::move(storePath)),
-                    input
-                };
+                return {std::move(storePath), input};
             }
         }
 
@@ -212,15 +209,12 @@ struct MercurialInputScheme : InputScheme
         };
 
         auto makeResult = [&](const Attrs & infoAttrs, StorePath && storePath)
-            -> std::pair<Tree, Input>
+            -> std::pair<StorePath, Input>
         {
             assert(input.getRev());
             assert(!_input.getRev() || _input.getRev() == input.getRev());
             input.attrs.insert_or_assign("revCount", getIntAttr(infoAttrs, "revCount"));
-            return {
-                Tree(store->toRealPath(storePath), std::move(storePath)),
-                input
-            };
+            return {std::move(storePath), input};
         };
 
         if (input.getRev()) {
diff --git a/src/libfetchers/path.cc b/src/libfetchers/path.cc
index 07e543c53..59e228e97 100644
--- a/src/libfetchers/path.cc
+++ b/src/libfetchers/path.cc
@@ -80,7 +80,7 @@ struct PathInputScheme : InputScheme
         // nothing to do
     }
 
-    std::pair<Tree, Input> fetch(ref<Store> store, const Input & input) override
+    std::pair<StorePath, Input> fetch(ref<Store> store, const Input & input) override
     {
         std::string absPath;
         auto path = getStrAttr(input.attrs, "path");
@@ -115,10 +115,7 @@ struct PathInputScheme : InputScheme
             // FIXME: try to substitute storePath.
             storePath = store->addToStore("source", absPath);
 
-        return {
-            Tree(store->toRealPath(*storePath), std::move(*storePath)),
-            input
-        };
+        return {std::move(*storePath), input};
     }
 };
 
diff --git a/src/libfetchers/tarball.cc b/src/libfetchers/tarball.cc
index c933475ca..74c8097ff 100644
--- a/src/libfetchers/tarball.cc
+++ b/src/libfetchers/tarball.cc
@@ -126,7 +126,7 @@ std::pair<Tree, time_t> downloadTarball(
 
     if (cached && !cached->expired)
         return {
-            Tree(store->toRealPath(cached->storePath), std::move(cached->storePath)),
+            Tree { .actualPath = store->toRealPath(cached->storePath), .storePath = std::move(cached->storePath) },
             getIntAttr(cached->infoAttrs, "lastModified")
         };
 
@@ -163,7 +163,7 @@ std::pair<Tree, time_t> downloadTarball(
         immutable);
 
     return {
-        Tree(store->toRealPath(*unpackedStorePath), std::move(*unpackedStorePath)),
+        Tree { .actualPath = store->toRealPath(*unpackedStorePath), .storePath = std::move(*unpackedStorePath) },
         lastModified,
     };
 }
@@ -225,10 +225,10 @@ struct TarballInputScheme : InputScheme
         return true;
     }
 
-    std::pair<Tree, Input> fetch(ref<Store> store, const Input & input) override
+    std::pair<StorePath, Input> fetch(ref<Store> store, const Input & input) override
     {
         auto tree = downloadTarball(store, getStrAttr(input.attrs, "url"), input.getName(), false).first;
-        return {std::move(tree), input};
+        return {std::move(tree.storePath), input};
     }
 };
 

From 1bec333788df9b1c9d9c68a428cfc79568d87cf2 Mon Sep 17 00:00:00 2001
From: Guillaume Maudoux <layus.on@gmail.com>
Date: Thu, 17 Feb 2022 09:32:15 +0100
Subject: [PATCH 532/567] Create to daemon-socket folder during install

---
 scripts/install-multi-user.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/install-multi-user.sh b/scripts/install-multi-user.sh
index 33e4eaa14..d3ed53d09 100644
--- a/scripts/install-multi-user.sh
+++ b/scripts/install-multi-user.sh
@@ -609,7 +609,7 @@ EOF
         fi
     fi
     _sudo "to make the basic directory structure of Nix (part 1)" \
-          install -dv -m 0755 /nix /nix/var /nix/var/log /nix/var/log/nix /nix/var/log/nix/drvs /nix/var/nix{,/db,/gcroots,/profiles,/temproots,/userpool} /nix/var/nix/{gcroots,profiles}/per-user
+          install -dv -m 0755 /nix /nix/var /nix/var/log /nix/var/log/nix /nix/var/log/nix/drvs /nix/var/nix{,/db,/gcroots,/profiles,/temproots,/userpool,/daemon-socket} /nix/var/nix/{gcroots,profiles}/per-user
 
     _sudo "to make the basic directory structure of Nix (part 2)" \
           install -dv -g "$NIX_BUILD_GROUP_NAME" -m 1775 /nix/store

From f56dd3a36bc8a325028588fd5500cbc33fa48a26 Mon Sep 17 00:00:00 2001
From: Taeer Bar-Yam <taeer@bar-yam.me>
Date: Thu, 17 Feb 2022 13:59:32 -0500
Subject: [PATCH 533/567] make flake template welcomeText markdown

---
 src/nix/flake-init.md | 14 ++++++++++----
 src/nix/flake.cc      |  5 +++--
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/nix/flake-init.md b/src/nix/flake-init.md
index c8bcee375..c13b22248 100644
--- a/src/nix/flake-init.md
+++ b/src/nix/flake-init.md
@@ -37,8 +37,8 @@ A flake can declare templates through its `templates` and
 
 * `path`: The path of the directory to be copied.
 
-* `welcomeText`: A block of text to display when a user initializes a new flake
-  based on this template.
+* `welcomeText`: A block of markdown text to display when a user initializes a
+  new flake based on this template.
 
 
 Here is an example:
@@ -50,8 +50,14 @@ outputs = { self }: {
     path = ./rust;
     description = "A simple Rust/Cargo project";
     welcomeText = ''
-      You've created a simple Rust/Cargo template.
-      Visit https://www.rust-lang.org/ for more info.
+      # Simple Rust/Cargo Template
+      ## Intended usage
+      The intended usage of this flake is...
+
+      ## More info
+      - [Rust language](https://www.rust-lang.org/)
+      - [Rust on the NixOS Wiki](https://nixos.wiki/wiki/Rust)
+      - ...
     '';
   };
 
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index f5d34c10f..ac14bed74 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -13,6 +13,7 @@
 #include "registry.hh"
 #include "json.hh"
 #include "eval-cache.hh"
+#include "markdown.hh"
 
 #include <nlohmann/json.hpp>
 #include <queue>
@@ -741,8 +742,8 @@ struct CmdFlakeInitCommon : virtual Args, EvalCommand
         }
         auto welcomeText = cursor->maybeGetAttr("welcomeText");
         if (welcomeText) {
-            notice("\n----------\n");
-            notice(welcomeText->getString());
+            notice("\n");
+            notice(renderMarkdownToTerminal(welcomeText->getString()));
         }
     }
 };

From 219fa2e43dedbbc7589474f1644da88974690baa Mon Sep 17 00:00:00 2001
From: Taeer Bar-Yam <taeer@bar-yam.me>
Date: Thu, 17 Feb 2022 15:17:20 -0500
Subject: [PATCH 534/567] add release notes for welcomeText

---
 doc/manual/src/release-notes/rl-next.md | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index ad8c27dbc..80eed9397 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -7,3 +7,9 @@
   implemented.
 
 * `nix store ping` now reports the version of the remote Nix daemon.
+
+* `nix flake {init,new}` now display information about which files have been
+  created.
+
+* Templates can now define a `welcomeText` attribute, which is printed out by
+  `nix flake {init,new} --template <template>`.

From f0de5fb8e733e45f1d96fdf842eab7cdfc598c60 Mon Sep 17 00:00:00 2001
From: Rok Garbas <rok@garbas.si>
Date: Fri, 18 Feb 2022 00:32:38 +0100
Subject: [PATCH 535/567] remove the manifest before creating them

---
 maintainers/push-docker.sh | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/maintainers/push-docker.sh b/maintainers/push-docker.sh
index f9c5a6b18..2aa953a78 100755
--- a/maintainers/push-docker.sh
+++ b/maintainers/push-docker.sh
@@ -2,7 +2,7 @@
 
 # TODO: parse from .version
 MAINTENANCE_VERSION="2.6"
-VERSION="$MAINTENANCE_VERSION.0"
+VERSION="$MAINTENANCE_VERSION.1"
 
 # Should be override `latest` tag, default true
 PUSH_AS_LATEST=1
@@ -55,9 +55,11 @@ do
 done
 
 echo "=> Creating $VERSION multi platform docker manifest for the following platforms: $PLATFORMS ..."
+docker manifest rm nixos/nix:$VERSION $DOCKER_MANIFEST
 docker manifest create nixos/nix:$VERSION $DOCKER_MANIFEST
 if [ $PUSH_AS_LATEST -eq 1 ]; then
   echo "=> Creating latest multi platform docker manifest for the following platforms: $PLATFORMS ..."
+  docker manifest rm nixos/nix:latest $DOCKER_MANIFEST_LATEST
   docker manifest create nixos/nix:latest $DOCKER_MANIFEST_LATEST
 fi
 

From 9bc03adbba5334663901c1136203bc07e4776be9 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 18 Feb 2022 13:57:38 +0100
Subject: [PATCH 536/567] Integrate push-docker.sh into the release script

This also makes sure that we get the Docker images from the same Hydra
eval, rather than the latest build from job/nix/.../dockerImage, which
may not be the same.
---
 maintainers/push-docker.sh    | 71 --------------------------------
 maintainers/upload-release.pl | 76 +++++++++++++++++++++++++++++++++--
 2 files changed, 72 insertions(+), 75 deletions(-)
 delete mode 100755 maintainers/push-docker.sh

diff --git a/maintainers/push-docker.sh b/maintainers/push-docker.sh
deleted file mode 100755
index 2aa953a78..000000000
--- a/maintainers/push-docker.sh
+++ /dev/null
@@ -1,71 +0,0 @@
-#/usr/bin/env bash
-
-# TODO: parse from .version
-MAINTENANCE_VERSION="2.6"
-VERSION="$MAINTENANCE_VERSION.1"
-
-# Should be override `latest` tag, default true
-PUSH_AS_LATEST=1
-
-PLATFORMS="x86_64-linux aarch64-linux"
-
-# ensure we are logged to docker hub
-docker login
-
-DOCKER_MANIFEST=""
-DOCKER_MANIFEST_LATEST=""
-
-for PLATFORM in $PLATFORMS;
-do
-  if   [ "$PLATFORM" = "x86_64-linux" ];  then DOCKER_PLATFORM="amd64"
-  elif [ "$PLATFORM" = "aarch64-linux" ]; then DOCKER_PLATFORM="arm64"
-  else
-    echo "EROROR: No docker platform found for $PLATFORM platform"
-    exit 1
-  fi
-
-  echo "=> Loading docker image for $PLATFORM platform ..."
-
-  DOCKER_IMAGE_TMP_FILE="$PWD/image-$PLATFORM.tar.gz"
-  if [ ! -f "$DOCKER_IMAGE_TMP_FILE" ]; then
-    curl -L https://hydra.nixos.org/job/nix/maintenance-$MAINTENANCE_VERSION/dockerImage.$PLATFORM/latest/download/1 > $DOCKER_IMAGE_TMP_FILE
-  fi
-  docker load -i $DOCKER_IMAGE_TMP_FILE
-
-  echo "=> Tagging docker image of version $VERSION for $PLATFORM platform ..."
-
-  docker tag nix:$VERSION nixos/nix:$VERSION-$DOCKER_PLATFORM
-  if [ $PUSH_AS_LATEST -eq 1 ]; then
-    echo "=> Tagging docker image of version latest for $PLATFORM platform ..."
-    docker tag nix:$VERSION nixos/nix:latest-$DOCKER_PLATFORM
-  fi
-
-  echo "=> Pushing docker image of version $VERSION for $PLATFORM platform ..."
-
-  docker push nixos/nix:$VERSION-$DOCKER_PLATFORM
-  if [ $PUSH_AS_LATEST -eq 1 ]; then
-    echo "=> Pushing docker image of version latest for $PLATFORM platform ..."
-    docker push nixos/nix:latest-$DOCKER_PLATFORM
-  fi
-
-  DOCKER_MANIFEST="$DOCKER_MANIFEST --amend nixos/nix:$VERSION-$DOCKER_PLATFORM"
-  DOCKER_MANIFEST_LATEST="$DOCKER_MANIFEST_LATEST --amend nixos/nix:latest-$DOCKER_PLATFORM"
-
-  echo
-done
-
-echo "=> Creating $VERSION multi platform docker manifest for the following platforms: $PLATFORMS ..."
-docker manifest rm nixos/nix:$VERSION $DOCKER_MANIFEST
-docker manifest create nixos/nix:$VERSION $DOCKER_MANIFEST
-if [ $PUSH_AS_LATEST -eq 1 ]; then
-  echo "=> Creating latest multi platform docker manifest for the following platforms: $PLATFORMS ..."
-  docker manifest rm nixos/nix:latest $DOCKER_MANIFEST_LATEST
-  docker manifest create nixos/nix:latest $DOCKER_MANIFEST_LATEST
-fi
-
-echo "=> Pushing $VERSION multi platform docker manifest ..."
-docker manifest push nixos/nix:$VERSION
-if [ $PUSH_AS_LATEST -eq 1 ]; then
-  echo "=> Pushing latest multi platform docker manifest ..."
-  docker manifest push nixos/nix:latest
-fi
diff --git a/maintainers/upload-release.pl b/maintainers/upload-release.pl
index 18ab33424..d3ef63db8 100755
--- a/maintainers/upload-release.pl
+++ b/maintainers/upload-release.pl
@@ -55,6 +55,11 @@ my $releaseDir = "nix/$releaseName";
 my $tmpDir = "$TMPDIR/nix-release/$releaseName";
 File::Path::make_path($tmpDir);
 
+my $narCache = "$TMPDIR/nar-cache";
+File::Path::make_path($narCache);
+
+my $binaryCache = "https://cache.nixos.org/?local-nar-cache=$narCache";
+
 # S3 setup.
 my $aws_access_key_id = $ENV{'AWS_ACCESS_KEY_ID'} or die "No AWS_ACCESS_KEY_ID given.";
 my $aws_secret_access_key = $ENV{'AWS_SECRET_ACCESS_KEY'} or die "No AWS_SECRET_ACCESS_KEY given.";
@@ -80,6 +85,7 @@ sub downloadFile {
     my ($jobName, $productNr, $dstName) = @_;
 
     my $buildInfo = decode_json(fetch("$evalUrl/job/$jobName", 'application/json'));
+    #print STDERR "$jobName: ", Dumper($buildInfo), "\n";
 
     my $srcFile = $buildInfo->{buildproducts}->{$productNr}->{path} or die "job '$jobName' lacks product $productNr\n";
     $dstName //= basename($srcFile);
@@ -87,19 +93,27 @@ sub downloadFile {
 
     if (!-e $tmpFile) {
         print STDERR "downloading $srcFile to $tmpFile...\n";
-        system("NIX_REMOTE=https://cache.nixos.org/ nix store cat '$srcFile' > '$tmpFile'") == 0
+
+        my $fileInfo = decode_json(`NIX_REMOTE=$binaryCache nix store ls --json '$srcFile'`);
+
+        $srcFile = $fileInfo->{target} if $fileInfo->{type} eq 'symlink';
+
+        #print STDERR $srcFile, " ", Dumper($fileInfo), "\n";
+
+        system("NIX_REMOTE=$binaryCache nix store cat '$srcFile' > '$tmpFile'.tmp") == 0
             or die "unable to fetch $srcFile\n";
+        rename("$tmpFile.tmp", $tmpFile) or die;
     }
 
-    my $sha256_expected = $buildInfo->{buildproducts}->{$productNr}->{sha256hash} or die;
+    my $sha256_expected = $buildInfo->{buildproducts}->{$productNr}->{sha256hash};
     my $sha256_actual = `nix hash file --base16 --type sha256 '$tmpFile'`;
     chomp $sha256_actual;
-    if ($sha256_expected ne $sha256_actual) {
+    if (defined($sha256_expected) && $sha256_expected ne $sha256_actual) {
         print STDERR "file $tmpFile is corrupt, got $sha256_actual, expected $sha256_expected\n";
         exit 1;
     }
 
-    write_file("$tmpFile.sha256", $sha256_expected);
+    write_file("$tmpFile.sha256", $sha256_actual);
 
     if (! -e "$tmpFile.asc") {
         system("gpg2 --detach-sign --armor $tmpFile") == 0 or die "unable to sign $tmpFile\n";
@@ -117,6 +131,60 @@ downloadFile("binaryTarballCross.x86_64-linux.armv6l-linux", "1");
 downloadFile("binaryTarballCross.x86_64-linux.armv7l-linux", "1");
 downloadFile("installerScript", "1");
 
+# Upload docker images to dockerhub.
+my $dockerManifest = "";
+my $dockerManifestLatest = "";
+
+for my $platforms (["x86_64-linux", "amd64"], ["aarch64-linux", "arm64"]) {
+    my $system = $platforms->[0];
+    my $dockerPlatform = $platforms->[1];
+    my $fn = "nix-$version-docker-image-$dockerPlatform.tar.gz";
+    downloadFile("dockerImage.$system", "1", $fn);
+
+    print STDERR "loading docker image for $dockerPlatform...\n";
+    system("docker load -i $tmpDir/$fn") == 0 or die;
+
+    my $tag = "nixos/nix:$version-$dockerPlatform";
+    my $latestTag = "nixos/nix:latest-$dockerPlatform";
+
+    print STDERR "tagging $version docker image for $dockerPlatform...\n";
+    system("docker tag nix:$version $tag") == 0 or die;
+
+    if ($isLatest) {
+        print STDERR "tagging latest docker image for $dockerPlatform...\n";
+        system("docker tag nix:$version $latestTag") == 0 or die;
+    }
+
+    print STDERR "pushing $version docker image for $dockerPlatform...\n";
+    system("docker push -q $tag") == 0 or die;
+
+    if ($isLatest) {
+        print STDERR "pushing latest docker image for $dockerPlatform...\n";
+        system("docker push -q $latestTag") == 0 or die;
+    }
+
+    $dockerManifest .= " --amend $tag";
+    $dockerManifestLatest .= " --amend $latestTag"
+}
+
+print STDERR "creating multi-platform docker manifest...\n";
+system("docker manifest rm nixos/nix:$version");
+system("docker manifest create nixos/nix:$version $dockerManifest") == 0 or die;
+if ($isLatest) {
+    print STDERR "creating latest multi-platform docker manifest...\n";
+    system("docker manifest rm nixos/nix:latest");
+    system("docker manifest create nixos/nix:latest $dockerManifestLatest") == 0 or die;
+}
+
+print STDERR "pushing multi-platform docker manifest...\n";
+system("docker manifest push nixos/nix:$version") == 0 or die;
+
+if ($isLatest) {
+    print STDERR "pushing latest multi-platform docker manifest...\n";
+    system("docker manifest push nixos/nix:latest") == 0 or die;
+}
+
+# Upload release files to S3.
 for my $fn (glob "$tmpDir/*") {
     my $name = basename($fn);
     my $dstKey = "$releaseDir/" . $name;

From dbdc63bc41d33a33e75d5fc8efa8e6520f9e6494 Mon Sep 17 00:00:00 2001
From: Linus Heckemann <git@sphalerite.org>
Date: Fri, 18 Feb 2022 23:43:33 +0100
Subject: [PATCH 537/567] path-info: use full store paths when we have them

Fixes #5645
---
 src/libstore/store-api.cc | 3 ++-
 src/nix/path-info.cc      | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 84767e917..8fcdc8b57 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -761,11 +761,11 @@ void Store::pathInfoToJSON(JSONPlaceholder & jsonOut, const StorePathSet & store
 
     for (auto & storePath : storePaths) {
         auto jsonPath = jsonList.object();
-        jsonPath.attr("path", printStorePath(storePath));
 
         try {
             auto info = queryPathInfo(storePath);
 
+            jsonPath.attr("path", printStorePath(info->path));
             jsonPath
                 .attr("narHash", info->narHash.to_string(hashBase, true))
                 .attr("narSize", info->narSize);
@@ -819,6 +819,7 @@ void Store::pathInfoToJSON(JSONPlaceholder & jsonOut, const StorePathSet & store
             }
 
         } catch (InvalidPath &) {
+            jsonPath.attr("path", printStorePath(storePath));
             jsonPath.attr("valid", false);
         }
     }
diff --git a/src/nix/path-info.cc b/src/nix/path-info.cc
index 3743d7504..d690fe594 100644
--- a/src/nix/path-info.cc
+++ b/src/nix/path-info.cc
@@ -97,7 +97,7 @@ struct CmdPathInfo : StorePathsCommand, MixJSON
 
             for (auto & storePath : storePaths) {
                 auto info = store->queryPathInfo(storePath);
-                auto storePathS = store->printStorePath(storePath);
+                auto storePathS = store->printStorePath(info->path);
 
                 std::cout << storePathS;
 

From 1fd127a06833c19a5a2965bd41cf4f695773cca6 Mon Sep 17 00:00:00 2001
From: "Travis A. Everett" <travis.a.everett@gmail.com>
Date: Fri, 18 Feb 2022 23:15:37 -0600
Subject: [PATCH 538/567] install-darwin: fix mount permission edge-case

Fixes #6122, which reports a problem with trying to run the installer
under another user (probably: user is not the disk "owner" and thus
can't mount the volume).
---
 scripts/create-darwin-volume.sh | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/scripts/create-darwin-volume.sh b/scripts/create-darwin-volume.sh
index bd8a7ee3a..ece4f29bb 100755
--- a/scripts/create-darwin-volume.sh
+++ b/scripts/create-darwin-volume.sh
@@ -685,22 +685,27 @@ encrypt_volume() {
     local volume_uuid="$1"
     local volume_label="$2"
     local password
+
+    task "Encrypt the Nix volume" >&2
+
     # Note: mount/unmount are late additions to support the right order
     # of operations for creating the volume and then baking its uuid into
     # other artifacts; not as well-trod wrt to potential errors, race
     # conditions, etc.
 
-    /usr/sbin/diskutil mount "$volume_label"
+    _sudo "to mount your Nix volume for encrypting" \
+        /usr/sbin/diskutil mount "$volume_label"
 
     password="$(/usr/bin/xxd -l 32 -p -c 256 /dev/random)"
     _sudo "to add your Nix volume's password to Keychain" \
         /usr/bin/security -i <<EOF
 add-generic-password -a "$volume_label" -s "$volume_uuid" -l "$volume_label encryption password" -D "Encrypted volume password" -j "Added automatically by the Nix installer for use by $NIX_VOLUME_MOUNTD_DEST" -w "$password" -T /System/Library/CoreServices/APFSUserAgent -T /System/Library/CoreServices/CSUserAgent -T /usr/bin/security "/Library/Keychains/System.keychain"
 EOF
-    builtin printf "%s" "$password" | _sudo "to encrypt your Nix volume" \
+    builtin printf "%s" "$password" | _sudo "to actually encrypt your Nix volume" \
         /usr/sbin/diskutil apfs encryptVolume "$volume_label" -user disk -stdinpassphrase
 
-    /usr/sbin/diskutil unmount force "$volume_label"
+    _sudo "to unmount the encrypted volume" \
+        /usr/sbin/diskutil unmount force "$volume_label"
 }
 
 create_volume() {

From 61295b910f2f2a6f2b0d288248c946713977ff1e Mon Sep 17 00:00:00 2001
From: Matthew Bauer <mjbauer95@gmail.com>
Date: Sun, 20 Feb 2022 23:46:11 -0600
Subject: [PATCH 539/567] Add verbosity to nix profile upgrade

Followup of https://github.com/NixOS/nix/pull/6086. This time adding a
warning if no packages are upgraded.
---
 src/nix/profile.cc | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/src/nix/profile.cc b/src/nix/profile.cc
index 55b5ff736..f0ce7eba8 100644
--- a/src/nix/profile.cc
+++ b/src/nix/profile.cc
@@ -410,12 +410,16 @@ struct CmdProfileUpgrade : virtual SourceExprCommand, MixDefaultProfile, MixProf
         // FIXME: code duplication
         std::vector<DerivedPath> pathsToBuild;
 
+        auto upgradedCount = 0;
+
         for (size_t i = 0; i < manifest.elements.size(); ++i) {
             auto & element(manifest.elements[i]);
             if (element.source
                 && !element.source->originalRef.input.isImmutable()
                 && matches(*store, element, i, matchers))
             {
+                upgradedCount++;
+
                 Activity act(*logger, lvlChatty, actUnknown,
                     fmt("checking '%s' for updates", element.source->attrPath));
 
@@ -448,6 +452,19 @@ struct CmdProfileUpgrade : virtual SourceExprCommand, MixDefaultProfile, MixProf
             }
         }
 
+        if (upgradedCount == 0) {
+            for (auto matcher: matchers) {
+                if (const size_t* index = std::get_if<size_t>(&matcher)){
+                    warn("'%d' is not a valid index in profile", *index);
+                } else if (const Path* path = std::get_if<Path>(&matcher)){
+                    warn("'%s' does not match any paths in profile", *path);
+                } else if (const RegexPattern* regex = std::get_if<RegexPattern>(&matcher)){
+                    warn("'%s' does not match any packages in profile", regex->pattern);
+                }
+            }
+            warn ("Try `nix profile list` to see the current profile.");
+        }
+
         store->buildPaths(pathsToBuild);
 
         updateProfile(manifest.build(store));

From 44b7d104b403062bf9ad57363f76464e355bc9a2 Mon Sep 17 00:00:00 2001
From: Nicolas Mattia <nicolas@nmattia.com>
Date: Mon, 21 Feb 2022 13:35:51 +0100
Subject: [PATCH 540/567] Document usage of MANPATH in nix-profile.sh

While trying to figure out how `nix-env`/`nix profile` work I had a hard
time understand how man pages were being installed.

Took me quite some time to figure this out, thought it might be useful
to others too!
---
 scripts/nix-profile.sh.in | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/scripts/nix-profile.sh.in b/scripts/nix-profile.sh.in
index 8cba1c522..45cbcbe74 100644
--- a/scripts/nix-profile.sh.in
+++ b/scripts/nix-profile.sh.in
@@ -24,6 +24,9 @@ if [ -n "$HOME" ] && [ -n "$USER" ]; then
         export NIX_SSL_CERT_FILE="$NIX_LINK/etc/ca-bundle.crt"
     fi
 
+    # Only use MANPATH if it is already set. In general `man` will just simply
+    # pick up `.nix-profile/share/man` because is it close to `.nix-profile/bin`
+    # which is in the $PATH. For more info, run `manpath -d`.
     if [ -n "${MANPATH-}" ]; then
         export MANPATH="$NIX_LINK/share/man:$MANPATH"
     fi

From ddb6740e7da2ec0cc6ad71ac7e40f8513a1103c2 Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Mon, 21 Feb 2022 15:43:43 +0100
Subject: [PATCH 541/567] triggerInterrupt: Refactor to use break

---
 src/libutil/util.cc | 26 +++++++++++---------------
 1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 03cbd7765..44463161f 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1599,28 +1599,24 @@ void triggerInterrupt()
 
     {
         InterruptCallbacks::Token i = 0;
-        std::function<void()> callback;
-        do {
+        while (true) {
+            std::function<void()> callback;
             {
                 auto interruptCallbacks(_interruptCallbacks.lock());
                 auto lb = interruptCallbacks->callbacks.lower_bound(i);
-                if (lb != interruptCallbacks->callbacks.end()) {
-                    callback = lb->second;
-                    i = lb->first + 1;
-                } else {
-                    callback = nullptr;
-                }
+                if (lb == interruptCallbacks->callbacks.end())
+                    break;
+
+                callback = lb->second;
+                i = lb->first + 1;
             }
 
-            if (callback) {
-                try {
-                    callback();
-                } catch (...) {
-                    ignoreException();
-                }
+            try {
+                callback();
+            } catch (...) {
+                ignoreException();
             }
         }
-        while (callback);
     }
 }
 

From afcdc7606cb9c1a1603a3a51b08ac411f82795db Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 21 Feb 2022 16:25:12 +0100
Subject: [PATCH 542/567] Remove std::list alias

---
 src/libexpr/get-drvs.hh   | 4 ++--
 src/libexpr/primops.cc    | 4 ++--
 src/libstore/names.hh     | 2 +-
 src/libstore/pathlocks.hh | 2 +-
 src/libutil/types.hh      | 5 ++---
 5 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/src/libexpr/get-drvs.hh b/src/libexpr/get-drvs.hh
index 29bb6a660..128354682 100644
--- a/src/libexpr/get-drvs.hh
+++ b/src/libexpr/get-drvs.hh
@@ -70,9 +70,9 @@ public:
 
 
 #if HAVE_BOEHMGC
-typedef list<DrvInfo, traceable_allocator<DrvInfo> > DrvInfos;
+typedef std::list<DrvInfo, traceable_allocator<DrvInfo> > DrvInfos;
 #else
-typedef list<DrvInfo> DrvInfos;
+typedef std::list<DrvInfo> DrvInfos;
 #endif
 
 
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index defb861e6..6f79fc49d 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -574,9 +574,9 @@ struct CompareValues
 
 
 #if HAVE_BOEHMGC
-typedef list<Value *, gc_allocator<Value *> > ValueList;
+typedef std::list<Value *, gc_allocator<Value *> > ValueList;
 #else
-typedef list<Value *> ValueList;
+typedef std::list<Value *> ValueList;
 #endif
 
 
diff --git a/src/libstore/names.hh b/src/libstore/names.hh
index 6f01fe2a1..ecbad10b3 100644
--- a/src/libstore/names.hh
+++ b/src/libstore/names.hh
@@ -25,7 +25,7 @@ private:
     std::unique_ptr<Regex> regex;
 };
 
-typedef list<DrvName> DrvNames;
+typedef std::list<DrvName> DrvNames;
 
 std::string_view nextComponent(std::string_view::const_iterator & p,
     const std::string_view::const_iterator end);
diff --git a/src/libstore/pathlocks.hh b/src/libstore/pathlocks.hh
index 919c8904c..759b9a584 100644
--- a/src/libstore/pathlocks.hh
+++ b/src/libstore/pathlocks.hh
@@ -20,7 +20,7 @@ class PathLocks
 {
 private:
     typedef std::pair<int, Path> FDPair;
-    list<FDPair> fds;
+    std::list<FDPair> fds;
     bool deletePaths;
 
 public:
diff --git a/src/libutil/types.hh b/src/libutil/types.hh
index e3aca20c9..130c04451 100644
--- a/src/libutil/types.hh
+++ b/src/libutil/types.hh
@@ -11,12 +11,11 @@
 
 namespace nix {
 
-using std::list;
 using std::set;
 using std::vector;
 using std::string;
 
-typedef list<string> Strings;
+typedef std::list<string> Strings;
 typedef set<string> StringSet;
 typedef std::map<string, string> StringMap;
 
@@ -24,7 +23,7 @@ typedef std::map<string, string> StringMap;
 
 typedef string Path;
 typedef std::string_view PathView;
-typedef list<Path> Paths;
+typedef std::list<Path> Paths;
 typedef set<Path> PathSet;
 
 typedef vector<std::pair<string, string>> Headers;

From fe9afb65bb35737a144acd612170b2e284298a2f Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 21 Feb 2022 16:28:23 +0100
Subject: [PATCH 543/567] Remove std::set alias

---
 src/libexpr/get-drvs.cc               | 2 +-
 src/libexpr/primops.cc                | 2 +-
 src/libstore/build/derivation-goal.cc | 2 +-
 src/libstore/build/goal.hh            | 4 ++--
 src/libstore/build/worker.cc          | 4 ++--
 src/libstore/build/worker.hh          | 4 ++--
 src/libstore/local-store.hh           | 2 +-
 src/libutil/types.hh                  | 5 ++---
 src/libutil/util.cc                   | 2 +-
 src/libutil/util.hh                   | 2 +-
 src/nix/repl.cc                       | 2 +-
 11 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/src/libexpr/get-drvs.cc b/src/libexpr/get-drvs.cc
index 5995a857b..167fb5fa9 100644
--- a/src/libexpr/get-drvs.cc
+++ b/src/libexpr/get-drvs.cc
@@ -266,7 +266,7 @@ void DrvInfo::setMeta(const string & name, Value * v)
 
 
 /* Cache for already considered attrsets. */
-typedef set<Bindings *> Done;
+typedef std::set<Bindings *> Done;
 
 
 /* Evaluate value `v'.  If it evaluates to a set of type `derivation',
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 6f79fc49d..44f0b19bc 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -654,7 +654,7 @@ static void prim_genericClosure(EvalState & state, const Pos & pos, Value * * ar
     // `doneKeys' doesn't need to be a GC root, because its values are
     // reachable from res.
     auto cmp = CompareValues(state);
-    set<Value *, decltype(cmp)> doneKeys(cmp);
+    std::set<Value *, decltype(cmp)> doneKeys(cmp);
     while (!workSet.empty()) {
         Value * e = *(workSet.begin());
         workSet.pop_front();
diff --git a/src/libstore/build/derivation-goal.cc b/src/libstore/build/derivation-goal.cc
index 151217b8b..27f8c6257 100644
--- a/src/libstore/build/derivation-goal.cc
+++ b/src/libstore/build/derivation-goal.cc
@@ -1091,7 +1091,7 @@ HookReply DerivationGoal::tryBuildHook()
     /* Create the log file and pipe. */
     Path logFile = openLogFile();
 
-    set<int> fds;
+    std::set<int> fds;
     fds.insert(hook->fromHook.readSide.get());
     fds.insert(hook->builderOut.readSide.get());
     worker.childStarted(shared_from_this(), fds, false, false);
diff --git a/src/libstore/build/goal.hh b/src/libstore/build/goal.hh
index 192e416d2..0db0c1938 100644
--- a/src/libstore/build/goal.hh
+++ b/src/libstore/build/goal.hh
@@ -18,8 +18,8 @@ struct CompareGoalPtrs {
 };
 
 /* Set of goals. */
-typedef set<GoalPtr, CompareGoalPtrs> Goals;
-typedef set<WeakGoalPtr, std::owner_less<WeakGoalPtr>> WeakGoals;
+typedef std::set<GoalPtr, CompareGoalPtrs> Goals;
+typedef std::set<WeakGoalPtr, std::owner_less<WeakGoalPtr>> WeakGoals;
 
 /* A map of paths to goals (and the other way around). */
 typedef std::map<StorePath, WeakGoalPtr> WeakGoalMap;
diff --git a/src/libstore/build/worker.cc b/src/libstore/build/worker.cc
index f11c5ce68..0a6108233 100644
--- a/src/libstore/build/worker.cc
+++ b/src/libstore/build/worker.cc
@@ -161,7 +161,7 @@ unsigned Worker::getNrLocalBuilds()
 }
 
 
-void Worker::childStarted(GoalPtr goal, const set<int> & fds,
+void Worker::childStarted(GoalPtr goal, const std::set<int> & fds,
     bool inBuildSlot, bool respectTimeouts)
 {
     Child child;
@@ -377,7 +377,7 @@ void Worker::waitForInput()
         GoalPtr goal = j->goal.lock();
         assert(goal);
 
-        set<int> fds2(j->fds);
+        std::set<int> fds2(j->fds);
         std::vector<unsigned char> buffer(4096);
         for (auto & k : fds2) {
             if (pollStatus.at(fdToPollStatus.at(k)).revents) {
diff --git a/src/libstore/build/worker.hh b/src/libstore/build/worker.hh
index 6a3b99c02..a1e036a96 100644
--- a/src/libstore/build/worker.hh
+++ b/src/libstore/build/worker.hh
@@ -38,7 +38,7 @@ struct Child
 {
     WeakGoalPtr goal;
     Goal * goal2; // ugly hackery
-    set<int> fds;
+    std::set<int> fds;
     bool respectTimeouts;
     bool inBuildSlot;
     steady_time_point lastOutput; /* time we last got output on stdout/stderr */
@@ -167,7 +167,7 @@ public:
 
     /* Registers a running child process.  `inBuildSlot' means that
        the process counts towards the jobs limit. */
-    void childStarted(GoalPtr goal, const set<int> & fds,
+    void childStarted(GoalPtr goal, const std::set<int> & fds,
         bool inBuildSlot, bool respectTimeouts);
 
     /* Unregisters a running child process.  `wakeSleepers' should be
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 46aed9bcb..a9c7475ac 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -292,7 +292,7 @@ private:
 
 
 typedef std::pair<dev_t, ino_t> Inode;
-typedef set<Inode> InodesSeen;
+typedef std::set<Inode> InodesSeen;
 
 
 /* "Fix", or canonicalise, the meta-data of the files in a store path
diff --git a/src/libutil/types.hh b/src/libutil/types.hh
index 130c04451..057c9021c 100644
--- a/src/libutil/types.hh
+++ b/src/libutil/types.hh
@@ -11,12 +11,11 @@
 
 namespace nix {
 
-using std::set;
 using std::vector;
 using std::string;
 
 typedef std::list<string> Strings;
-typedef set<string> StringSet;
+typedef std::set<string> StringSet;
 typedef std::map<string, string> StringMap;
 
 /* Paths are just strings. */
@@ -24,7 +23,7 @@ typedef std::map<string, string> StringMap;
 typedef string Path;
 typedef std::string_view PathView;
 typedef std::list<Path> Paths;
-typedef set<Path> PathSet;
+typedef std::set<Path> PathSet;
 
 typedef vector<std::pair<string, string>> Headers;
 
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 9c2e43cdd..b6041264e 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1174,7 +1174,7 @@ void runProgram2(const RunOptions & options)
 }
 
 
-void closeMostFDs(const set<int> & exceptions)
+void closeMostFDs(const std::set<int> & exceptions)
 {
 #if __linux__
     try {
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 579a42785..319442210 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -343,7 +343,7 @@ std::vector<char *> stringsToCharPtrs(const Strings & ss);
 
 /* Close all file descriptors except those listed in the given set.
    Good practice in child processes. */
-void closeMostFDs(const set<int> & exceptions);
+void closeMostFDs(const std::set<int> & exceptions);
 
 /* Set the close-on-exec flag for the given file descriptor. */
 void closeOnExec(int fd);
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 2c39fac91..60454471d 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -75,7 +75,7 @@ struct NixRepl
     Expr * parseString(string s);
     void evalString(string s, Value & v);
 
-    typedef set<Value *> ValuesSeen;
+    typedef std::set<Value *> ValuesSeen;
     std::ostream &  printValue(std::ostream & str, Value & v, unsigned int maxDepth);
     std::ostream &  printValue(std::ostream & str, Value & v, unsigned int maxDepth, ValuesSeen & seen);
 };

From 1ac2664472d0135503e54f0d924a802023855003 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 21 Feb 2022 16:32:34 +0100
Subject: [PATCH 544/567] Remove std::vector alias

---
 src/build-remote/build-remote.cc |  2 +-
 src/libexpr/nixexpr.hh           |  4 ++--
 src/libexpr/parser.y             | 16 ++++++++--------
 src/libexpr/primops.cc           |  4 ++--
 src/libutil/config.cc            |  4 ++--
 src/libutil/types.hh             |  3 +--
 src/libutil/util.cc              |  2 +-
 src/libutil/util.hh              |  2 +-
 src/nix-env/nix-env.cc           |  6 +++---
 9 files changed, 21 insertions(+), 22 deletions(-)

diff --git a/src/build-remote/build-remote.cc b/src/build-remote/build-remote.cc
index 9d541b45d..4d7b602d8 100644
--- a/src/build-remote/build-remote.cc
+++ b/src/build-remote/build-remote.cc
@@ -208,7 +208,7 @@ static int main_build_remote(int argc, char * * argv)
 
                         for (auto & m : machines)
                             error
-                                % concatStringsSep<vector<string>>(", ", m.systemTypes)
+                                % concatStringsSep<std::vector<string>>(", ", m.systemTypes)
                                 % m.maxJobs
                                 % concatStringsSep<StringSet>(", ", m.supportedFeatures)
                                 % concatStringsSep<StringSet>(", ", m.mandatoryFeatures);
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index 6f6acb074..e7f717eba 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -335,8 +335,8 @@ struct ExprConcatStrings : Expr
 {
     Pos pos;
     bool forceString;
-    vector<std::pair<Pos, Expr *> > * es;
-    ExprConcatStrings(const Pos & pos, bool forceString, vector<std::pair<Pos, Expr *> > * es)
+    std::vector<std::pair<Pos, Expr *> > * es;
+    ExprConcatStrings(const Pos & pos, bool forceString, std::vector<std::pair<Pos, Expr *> > * es)
         : pos(pos), forceString(forceString), es(es) { };
     COMMON_METHODS
 };
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index f0c80ebd5..e1d177c1f 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -193,7 +193,7 @@ static Formals * toFormals(ParseData & data, ParserFormals * formals,
 
 
 static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols,
-    vector<std::pair<Pos, std::variant<Expr *, StringToken> > > & es)
+    std::vector<std::pair<Pos, std::variant<Expr *, StringToken> > > & es)
 {
     if (es.empty()) return new ExprString("");
 
@@ -233,7 +233,7 @@ static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols,
     }
 
     /* Strip spaces from each line. */
-    vector<std::pair<Pos, Expr *> > * es2 = new vector<std::pair<Pos, Expr *> >;
+    std::vector<std::pair<Pos, Expr *> > * es2 = new std::vector<std::pair<Pos, Expr *> >;
     atStartOfLine = true;
     size_t curDropped = 0;
     size_t n = es.size();
@@ -415,7 +415,7 @@ expr_op
   | expr_op UPDATE expr_op { $$ = new ExprOpUpdate(CUR_POS, $1, $3); }
   | expr_op '?' attrpath { $$ = new ExprOpHasAttr($1, *$3); }
   | expr_op '+' expr_op
-    { $$ = new ExprConcatStrings(CUR_POS, false, new vector<std::pair<Pos, Expr *> >({{makeCurPos(@1, data), $1}, {makeCurPos(@3, data), $3}})); }
+    { $$ = new ExprConcatStrings(CUR_POS, false, new std::vector<std::pair<Pos, Expr *> >({{makeCurPos(@1, data), $1}, {makeCurPos(@3, data), $3}})); }
   | expr_op '-' expr_op { $$ = new ExprCall(CUR_POS, new ExprVar(data->symbols.create("__sub")), {$1, $3}); }
   | expr_op '*' expr_op { $$ = new ExprCall(CUR_POS, new ExprVar(data->symbols.create("__mul")), {$1, $3}); }
   | expr_op '/' expr_op { $$ = new ExprCall(CUR_POS, new ExprVar(data->symbols.create("__div")), {$1, $3}); }
@@ -503,9 +503,9 @@ string_parts_interpolated
   : string_parts_interpolated STR
   { $$ = $1; $1->emplace_back(makeCurPos(@2, data), new ExprString(string($2))); }
   | string_parts_interpolated DOLLAR_CURLY expr '}' { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $3); }
-  | DOLLAR_CURLY expr '}' { $$ = new vector<std::pair<Pos, Expr *> >; $$->emplace_back(makeCurPos(@1, data), $2); }
+  | DOLLAR_CURLY expr '}' { $$ = new std::vector<std::pair<Pos, Expr *> >; $$->emplace_back(makeCurPos(@1, data), $2); }
   | STR DOLLAR_CURLY expr '}' {
-      $$ = new vector<std::pair<Pos, Expr *> >;
+      $$ = new std::vector<std::pair<Pos, Expr *> >;
       $$->emplace_back(makeCurPos(@1, data), new ExprString(string($1)));
       $$->emplace_back(makeCurPos(@2, data), $3);
     }
@@ -528,7 +528,7 @@ path_start
 ind_string_parts
   : ind_string_parts IND_STR { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $2); }
   | ind_string_parts DOLLAR_CURLY expr '}' { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $3); }
-  | { $$ = new vector<std::pair<Pos, std::variant<Expr *, StringToken> > >; }
+  | { $$ = new std::vector<std::pair<Pos, std::variant<Expr *, StringToken> > >; }
   ;
 
 binds
@@ -582,9 +582,9 @@ attrpath
       } else
           $$->push_back(AttrName($3));
     }
-  | attr { $$ = new vector<AttrName>; $$->push_back(AttrName(data->symbols.create($1))); }
+  | attr { $$ = new std::vector<AttrName>; $$->push_back(AttrName(data->symbols.create($1))); }
   | string_attr
-    { $$ = new vector<AttrName>;
+    { $$ = new std::vector<AttrName>;
       ExprString *str = dynamic_cast<ExprString *>($1);
       if (str) {
           $$->push_back(AttrName(data->symbols.create(str->s)));
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 44f0b19bc..daf679a5a 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -3649,12 +3649,12 @@ static void prim_replaceStrings(EvalState & state, const Pos & pos, Value * * ar
             .errPos = pos
         });
 
-    vector<string> from;
+    std::vector<string> from;
     from.reserve(args[0]->listSize());
     for (auto elem : args[0]->listItems())
         from.emplace_back(state.forceString(*elem, pos));
 
-    vector<std::pair<string, PathSet>> to;
+    std::vector<std::pair<string, PathSet>> to;
     to.reserve(args[1]->listSize());
     for (auto elem : args[1]->listItems()) {
         PathSet ctx;
diff --git a/src/libutil/config.cc b/src/libutil/config.cc
index 92ab265d3..8e05f1765 100644
--- a/src/libutil/config.cc
+++ b/src/libutil/config.cc
@@ -90,7 +90,7 @@ void AbstractConfig::applyConfig(const std::string & contents, const std::string
         if (hash != string::npos)
             line = string(line, 0, hash);
 
-        vector<string> tokens = tokenizeString<vector<string> >(line);
+        auto tokens = tokenizeString<std::vector<string>>(line);
         if (tokens.empty()) continue;
 
         if (tokens.size() < 2)
@@ -122,7 +122,7 @@ void AbstractConfig::applyConfig(const std::string & contents, const std::string
 
         string name = tokens[0];
 
-        vector<string>::iterator i = tokens.begin();
+        auto i = tokens.begin();
         advance(i, 2);
 
         set(name, concatStringsSep(" ", Strings(i, tokens.end()))); // FIXME: slow
diff --git a/src/libutil/types.hh b/src/libutil/types.hh
index 057c9021c..a26c9a966 100644
--- a/src/libutil/types.hh
+++ b/src/libutil/types.hh
@@ -11,7 +11,6 @@
 
 namespace nix {
 
-using std::vector;
 using std::string;
 
 typedef std::list<string> Strings;
@@ -25,7 +24,7 @@ typedef std::string_view PathView;
 typedef std::list<Path> Paths;
 typedef std::set<Path> PathSet;
 
-typedef vector<std::pair<string, string>> Headers;
+typedef std::vector<std::pair<string, string>> Headers;
 
 /* Helper class to run code at startup. */
 template<typename T>
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index b6041264e..b172e0554 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1250,7 +1250,7 @@ template<class C> C tokenizeString(std::string_view s, std::string_view separato
 
 template Strings tokenizeString(std::string_view s, std::string_view separators);
 template StringSet tokenizeString(std::string_view s, std::string_view separators);
-template vector<string> tokenizeString(std::string_view s, std::string_view separators);
+template std::vector<string> tokenizeString(std::string_view s, std::string_view separators);
 
 
 string chomp(std::string_view s)
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 319442210..a949e6424 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -99,7 +99,7 @@ struct DirEntry
         : name(name), ino(ino), type(type) { }
 };
 
-typedef vector<DirEntry> DirEntries;
+typedef std::vector<DirEntry> DirEntries;
 
 DirEntries readDirectory(const Path & path);
 
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index d2636abf7..52d07e3df 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -840,7 +840,7 @@ void printTable(Table & table)
 {
     auto nrColumns = table.size() > 0 ? table.front().size() : 0;
 
-    vector<size_t> widths;
+    std::vector<size_t> widths;
     widths.resize(nrColumns);
 
     for (auto & i : table) {
@@ -907,7 +907,7 @@ static VersionDiff compareVersionAgainstSet(
 }
 
 
-static void queryJSON(Globals & globals, vector<DrvInfo> & elems, bool printOutPath, bool printMeta)
+static void queryJSON(Globals & globals, std::vector<DrvInfo> & elems, bool printOutPath, bool printMeta)
 {
     JSONObject topObj(cout, true);
     for (auto & i : elems) {
@@ -1020,7 +1020,7 @@ static void opQuery(Globals & globals, Strings opFlags, Strings opArgs)
 
     /* Sort them by name. */
     /* !!! */
-    vector<DrvInfo> elems;
+    std::vector<DrvInfo> elems;
     for (auto & i : elems_) elems.push_back(i);
     sort(elems.begin(), elems.end(), cmpElemByName);
 

From 36c7b12f3354606a50808197f6695c185fd02893 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 21 Feb 2022 16:37:25 +0100
Subject: [PATCH 545/567] Remove std::string alias

---
 src/libexpr/symbol-table.hh |  8 ++++----
 src/libexpr/value.hh        | 10 +++++-----
 src/libstore/machines.hh    | 14 +++++++-------
 src/libstore/names.hh       |  6 +++---
 src/libutil/types.hh        | 13 +++++--------
 5 files changed, 24 insertions(+), 27 deletions(-)

diff --git a/src/libexpr/symbol-table.hh b/src/libexpr/symbol-table.hh
index a090ebae5..48d20c29d 100644
--- a/src/libexpr/symbol-table.hh
+++ b/src/libexpr/symbol-table.hh
@@ -17,8 +17,8 @@ namespace nix {
 class Symbol
 {
 private:
-    const string * s; // pointer into SymbolTable
-    Symbol(const string * s) : s(s) { };
+    const std::string * s; // pointer into SymbolTable
+    Symbol(const std::string * s) : s(s) { };
     friend class SymbolTable;
 
 public:
@@ -72,7 +72,7 @@ class SymbolTable
 {
 private:
     std::unordered_map<std::string_view, Symbol> symbols;
-    std::list<string> store;
+    std::list<std::string> store;
 
 public:
     Symbol create(std::string_view s)
@@ -84,7 +84,7 @@ public:
         auto it = symbols.find(s);
         if (it != symbols.end()) return it->second;
 
-        const string & rawSym = store.emplace_back(s);
+        auto & rawSym = store.emplace_back(s);
         return symbols.emplace(rawSym, Symbol(&rawSym)).first->second;
     }
 
diff --git a/src/libexpr/value.hh b/src/libexpr/value.hh
index bef5cd6bd..3fdff71a5 100644
--- a/src/libexpr/value.hh
+++ b/src/libexpr/value.hh
@@ -77,20 +77,20 @@ class ExternalValueBase
 
     public:
     /* Return a simple string describing the type */
-    virtual string showType() const = 0;
+    virtual std::string showType() const = 0;
 
     /* Return a string to be used in builtins.typeOf */
-    virtual string typeOf() const = 0;
+    virtual std::string typeOf() const = 0;
 
     /* Coerce the value to a string. Defaults to uncoercable, i.e. throws an
-     * error
+     * error.
      */
-    virtual string coerceToString(const Pos & pos, PathSet & context, bool copyMore, bool copyToStore) const;
+    virtual std::string coerceToString(const Pos & pos, PathSet & context, bool copyMore, bool copyToStore) const;
 
     /* Compare to another value of the same type. Defaults to uncomparable,
      * i.e. always false.
      */
-    virtual bool operator==(const ExternalValueBase & b) const;
+    virtual bool operator ==(const ExternalValueBase & b) const;
 
     /* Print the value as JSON. Defaults to unconvertable, i.e. throws an error */
     virtual void printValueAsJSON(EvalState & state, bool strict,
diff --git a/src/libstore/machines.hh b/src/libstore/machines.hh
index 341d9bd97..834626de9 100644
--- a/src/libstore/machines.hh
+++ b/src/libstore/machines.hh
@@ -8,19 +8,19 @@ class Store;
 
 struct Machine {
 
-    const string storeUri;
-    const std::vector<string> systemTypes;
-    const string sshKey;
+    const std::string storeUri;
+    const std::vector<std::string> systemTypes;
+    const std::string sshKey;
     const unsigned int maxJobs;
     const unsigned int speedFactor;
-    const std::set<string> supportedFeatures;
-    const std::set<string> mandatoryFeatures;
+    const std::set<std::string> supportedFeatures;
+    const std::set<std::string> mandatoryFeatures;
     const std::string sshPublicHostKey;
     bool enabled = true;
 
-    bool allSupported(const std::set<string> & features) const;
+    bool allSupported(const std::set<std::string> & features) const;
 
-    bool mandatoryMet(const std::set<string> & features) const;
+    bool mandatoryMet(const std::set<std::string> & features) const;
 
     Machine(decltype(storeUri) storeUri,
         decltype(systemTypes) systemTypes,
diff --git a/src/libstore/names.hh b/src/libstore/names.hh
index ecbad10b3..3977fc6cc 100644
--- a/src/libstore/names.hh
+++ b/src/libstore/names.hh
@@ -10,9 +10,9 @@ struct Regex;
 
 struct DrvName
 {
-    string fullName;
-    string name;
-    string version;
+    std::string fullName;
+    std::string name;
+    std::string version;
     unsigned int hits;
 
     DrvName();
diff --git a/src/libutil/types.hh b/src/libutil/types.hh
index a26c9a966..bea2673ca 100644
--- a/src/libutil/types.hh
+++ b/src/libutil/types.hh
@@ -11,20 +11,17 @@
 
 namespace nix {
 
-using std::string;
-
-typedef std::list<string> Strings;
-typedef std::set<string> StringSet;
-typedef std::map<string, string> StringMap;
+typedef std::list<std::string> Strings;
+typedef std::set<std::string> StringSet;
+typedef std::map<std::string, std::string> StringMap;
 
 /* Paths are just strings. */
-
-typedef string Path;
+typedef std::string Path;
 typedef std::string_view PathView;
 typedef std::list<Path> Paths;
 typedef std::set<Path> PathSet;
 
-typedef std::vector<std::pair<string, string>> Headers;
+typedef std::vector<std::pair<std::string, std::string>> Headers;
 
 /* Helper class to run code at startup. */
 template<typename T>

From 3cd958849b820ba6ec80965afa6268f59c9bb650 Mon Sep 17 00:00:00 2001
From: Matthew Bauer <mjbauer95@gmail.com>
Date: Mon, 21 Feb 2022 10:04:04 -0600
Subject: [PATCH 546/567] Apply suggestions from code review

Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
---
 src/nix/profile.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/nix/profile.cc b/src/nix/profile.cc
index f0ce7eba8..508cbd336 100644
--- a/src/nix/profile.cc
+++ b/src/nix/profile.cc
@@ -453,7 +453,7 @@ struct CmdProfileUpgrade : virtual SourceExprCommand, MixDefaultProfile, MixProf
         }
 
         if (upgradedCount == 0) {
-            for (auto matcher: matchers) {
+            for (auto & matcher : matchers) {
                 if (const size_t* index = std::get_if<size_t>(&matcher)){
                     warn("'%d' is not a valid index in profile", *index);
                 } else if (const Path* path = std::get_if<Path>(&matcher)){
@@ -462,7 +462,7 @@ struct CmdProfileUpgrade : virtual SourceExprCommand, MixDefaultProfile, MixProf
                     warn("'%s' does not match any packages in profile", regex->pattern);
                 }
             }
-            warn ("Try `nix profile list` to see the current profile.");
+            warn ("Use 'nix profile list' to see the current profile.");
         }
 
         store->buildPaths(pathsToBuild);

From 8ffb09a08a375e19208bbe65ba532ce1e462b74e Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 21 Feb 2022 17:14:22 +0100
Subject: [PATCH 547/567] Fix macOS build

---
 .../resolve-system-dependencies.cc               | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/resolve-system-dependencies/resolve-system-dependencies.cc b/src/resolve-system-dependencies/resolve-system-dependencies.cc
index 98c969437..4dd691981 100644
--- a/src/resolve-system-dependencies/resolve-system-dependencies.cc
+++ b/src/resolve-system-dependencies/resolve-system-dependencies.cc
@@ -23,9 +23,9 @@ Path resolveCacheFile(Path lib)
     return cacheDir + "/" + lib;
 }
 
-std::set<string> readCacheFile(const Path & file)
+std::set<std::string> readCacheFile(const Path & file)
 {
-    return tokenizeString<set<string>>(readFile(file), "\n");
+    return tokenizeString<std::set<std::string>>(readFile(file), "\n");
 }
 
 std::set<std::string> runResolver(const Path & filename)
@@ -81,7 +81,7 @@ std::set<std::string> runResolver(const Path & filename)
     bool should_swap = magic == MH_CIGAM_64;
     ptrdiff_t cmd_offset = mach64_offset + sizeof(mach_header_64);
 
-    std::set<string> libs;
+    std::set<std::string> libs;
     for (uint32_t i = 0; i < DO_SWAP(should_swap, m_header->ncmds); i++) {
         load_command * cmd = (load_command *) (obj + cmd_offset);
         switch(DO_SWAP(should_swap, cmd->cmd)) {
@@ -110,9 +110,9 @@ Path resolveSymlink(const Path & path)
         : concatStrings(dirOf(path), "/", target);
 }
 
-std::set<string> resolveTree(const Path & path, PathSet & deps)
+std::set<std::string> resolveTree(const Path & path, PathSet & deps)
 {
-    std::set<string> results;
+    std::set<std::string> results;
     if (!deps.insert(path).second) return {};
     for (auto & lib : runResolver(path)) {
         results.insert(lib);
@@ -123,7 +123,7 @@ std::set<string> resolveTree(const Path & path, PathSet & deps)
     return results;
 }
 
-std::set<string> getPath(const Path & path)
+std::set<std::string> getPath(const Path & path)
 {
     if (hasPrefix(path, "/dev")) return {};
 
@@ -131,7 +131,7 @@ std::set<string> getPath(const Path & path)
     if (pathExists(cacheFile))
         return readCacheFile(cacheFile);
 
-    std::set<string> deps, paths;
+    std::set<std::string> deps, paths;
     paths.insert(path);
 
     Path nextPath(path);
@@ -180,7 +180,7 @@ int main(int argc, char ** argv)
             impurePaths.insert("/usr/lib/libSystem.dylib");
         }
 
-        std::set<string> allPaths;
+        std::set<std::string> allPaths;
 
         for (auto & path : impurePaths)
             for (auto & p : getPath(path))

From 162fbe31ffe4c2b2d7648e5df2d5a0c9b4a44996 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 11 Feb 2022 18:11:08 +0100
Subject: [PATCH 548/567] Replace defaultBla.$system with bla.$system.default

This also simplifies some InstallableFlake logic and fixes 'nix
bundle' parsing its installable twice.

Fixes #5532.
---
 src/libcmd/installables.cc    |  5 ++++-
 src/nix/bundle.cc             | 11 ++++++-----
 src/nix/develop.cc            |  9 ++++++++-
 src/nix/flake.cc              |  2 +-
 src/nix/run.cc                |  5 ++++-
 tests/flake-bundler.sh        | 26 +++++++++++++------------
 tests/flake-local-settings.sh |  2 +-
 tests/flake-searching.sh      |  6 ++++--
 tests/flakes.sh               | 36 ++++++++++++++++++-----------------
 9 files changed, 61 insertions(+), 41 deletions(-)

diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index 644954977..c07e39628 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -158,7 +158,10 @@ SourceExprCommand::SourceExprCommand()
 
 Strings SourceExprCommand::getDefaultFlakeAttrPaths()
 {
-    return {"defaultPackage." + settings.thisSystem.get()};
+    return {
+        "packages." + settings.thisSystem.get() + ".default",
+        "defaultPackage." + settings.thisSystem.get()
+    };
 }
 
 Strings SourceExprCommand::getDefaultFlakeAttrPathPrefixes()
diff --git a/src/nix/bundle.cc b/src/nix/bundle.cc
index c13018328..6b891a6ee 100644
--- a/src/nix/bundle.cc
+++ b/src/nix/bundle.cc
@@ -49,9 +49,11 @@ struct CmdBundle : InstallableCommand
 
     Category category() override { return catSecondary; }
 
+    // FIXME: cut&paste from CmdRun.
     Strings getDefaultFlakeAttrPaths() override
     {
         Strings res{
+            "apps." + settings.thisSystem.get() + ".default",
             "defaultApp." + settings.thisSystem.get()
         };
         for (auto & s : SourceExprCommand::getDefaultFlakeAttrPaths())
@@ -61,10 +63,7 @@ struct CmdBundle : InstallableCommand
 
     Strings getDefaultFlakeAttrPathPrefixes() override
     {
-        Strings res{
-            "apps." + settings.thisSystem.get() + "."
-
-        };
+        Strings res{"apps." + settings.thisSystem.get() + "."};
         for (auto & s : SourceExprCommand::getDefaultFlakeAttrPathPrefixes())
             res.push_back(s);
         return res;
@@ -80,7 +79,9 @@ struct CmdBundle : InstallableCommand
         const flake::LockFlags lockFlags{ .writeLockFile = false };
         InstallableFlake bundler{this,
             evalState, std::move(bundlerFlakeRef), bundlerName,
-            {"defaultBundler." + settings.thisSystem.get()},
+            {"bundlers." + settings.thisSystem.get() + ".default",
+             "defaultBundler." + settings.thisSystem.get()
+            },
             {"bundlers." + settings.thisSystem.get() + "."},
             lockFlags
         };
diff --git a/src/nix/develop.cc b/src/nix/develop.cc
index f88f5909c..92e31599a 100644
--- a/src/nix/develop.cc
+++ b/src/nix/develop.cc
@@ -325,8 +325,15 @@ struct Common : InstallableCommand, MixProfile
 
     Strings getDefaultFlakeAttrPaths() override
     {
-        return {"devShell." + settings.thisSystem.get(), "defaultPackage." + settings.thisSystem.get()};
+        Strings paths{
+            "devShells." + settings.thisSystem.get() + ".default",
+            "devShell." + settings.thisSystem.get(),
+        };
+        for (auto & p : SourceExprCommand::getDefaultFlakeAttrPaths())
+            paths.push_back(p);
+        return paths;
     }
+
     Strings getDefaultFlakeAttrPathPrefixes() override
     {
         auto res = SourceExprCommand::getDefaultFlakeAttrPathPrefixes();
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index cd85bcea6..303edb9fe 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -651,7 +651,7 @@ struct CmdFlakeCheck : FlakeCommand
 };
 
 static Strings defaultTemplateAttrPathsPrefixes{"templates."};
-static Strings defaultTemplateAttrPaths = {"defaultTemplate"};
+static Strings defaultTemplateAttrPaths = {"templates.default", "defaultTemplate"};
 
 struct CmdFlakeInitCommon : virtual Args, EvalCommand
 {
diff --git a/src/nix/run.cc b/src/nix/run.cc
index bae64ed39..a67c23bcb 100644
--- a/src/nix/run.cc
+++ b/src/nix/run.cc
@@ -158,7 +158,10 @@ struct CmdRun : InstallableCommand
 
     Strings getDefaultFlakeAttrPaths() override
     {
-        Strings res{"defaultApp." + settings.thisSystem.get()};
+        Strings res{
+            "apps." + settings.thisSystem.get() + ".default",
+            "defaultApp." + settings.thisSystem.get(),
+        };
         for (auto & s : SourceExprCommand::getDefaultFlakeAttrPaths())
             res.push_back(s);
         return res;
diff --git a/tests/flake-bundler.sh b/tests/flake-bundler.sh
index 699920f60..9496b8f92 100644
--- a/tests/flake-bundler.sh
+++ b/tests/flake-bundler.sh
@@ -10,26 +10,28 @@ cd $TEST_HOME
 cat <<EOF > flake.nix
 {
     outputs = {self}: {
-       bundlers.$system.simple = drv:
+      bundlers.$system = rec {
+        simple = drv:
           if drv?type && drv.type == "derivation"
           then drv
-          else self.defaultPackage.$system;
-       defaultBundler.$system = self.bundlers.$system.simple;
-       defaultPackage.$system = import ./simple.nix;
-       defaultApp.$system = {
-         type = "app";
-         program = "\${import ./simple.nix}/hello";
-       };
+          else self.packages.$system.default;
+        default = simple;
+      };
+      packages.$system.default = import ./simple.nix;
+      apps.$system.default = {
+        type = "app";
+        program = "\${import ./simple.nix}/hello";
+      };
     };
 }
 EOF
 nix build .#
 nix bundle --bundler .# .#
-nix bundle --bundler .#defaultBundler.$system  .#defaultPackage.$system
-nix bundle --bundler .#bundlers.$system.simple .#defaultPackage.$system
+nix bundle --bundler .#bundlers.$system.default .#packages.$system.default
+nix bundle --bundler .#bundlers.$system.simple  .#packages.$system.default
 
-nix bundle --bundler .#defaultBundler.$system  .#defaultApp.$system
-nix bundle --bundler .#bundlers.$system.simple .#defaultApp.$system
+nix bundle --bundler .#bundlers.$system.default .#apps.$system.default
+nix bundle --bundler .#bundlers.$system.simple  .#apps.$system.default
 
 clearStore
 
diff --git a/tests/flake-local-settings.sh b/tests/flake-local-settings.sh
index 7765fe379..e92c16f87 100644
--- a/tests/flake-local-settings.sh
+++ b/tests/flake-local-settings.sh
@@ -21,7 +21,7 @@ cat <<EOF > flake.nix
     nixConfig.allow-dirty = false; # See #5621
 
     outputs = a: {
-       defaultPackage.$system = import ./simple.nix;
+       packages.$system.default = import ./simple.nix;
     };
 }
 EOF
diff --git a/tests/flake-searching.sh b/tests/flake-searching.sh
index bc55f2bdc..db241f6d2 100644
--- a/tests/flake-searching.sh
+++ b/tests/flake-searching.sh
@@ -15,8 +15,10 @@ cat <<EOF > flake.nix
 {
     inputs.foo.url = "$PWD/foo";
     outputs = a: {
-       defaultPackage.$system = import ./simple.nix;
-       packages.$system.test = import ./simple.nix;
+       packages.$system = rec {
+         test = import ./simple.nix;
+         default = test;
+       };
     };
 }
 EOF
diff --git a/tests/flakes.sh b/tests/flakes.sh
index db178967f..ea629ae70 100644
--- a/tests/flakes.sh
+++ b/tests/flakes.sh
@@ -41,8 +41,10 @@ cat > $flake1Dir/flake.nix <<EOF
   description = "Bla bla";
 
   outputs = inputs: rec {
-    packages.$system.foo = import ./simple.nix;
-    defaultPackage.$system = packages.$system.foo;
+    packages.$system = rec {
+      foo = import ./simple.nix;
+      default = foo;
+    };
 
     # To test "nix flake init".
     legacyPackages.x86_64-linux.hello = import ./simple.nix;
@@ -128,7 +130,7 @@ hash2=$(nix flake metadata flake1 --json --refresh | jq -r .revision)
 nix build -o $TEST_ROOT/result flake1#foo
 [[ -e $TEST_ROOT/result/hello ]]
 
-# Test defaultPackage.
+# Test packages.default.
 nix build -o $TEST_ROOT/result flake1
 [[ -e $TEST_ROOT/result/hello ]]
 
@@ -140,11 +142,11 @@ nix build -o $flake1Dir/result git+file://$flake1Dir
 nix path-info $flake1Dir/result
 
 # 'getFlake' on a mutable flakeref should fail in pure mode, but succeed in impure mode.
-(! nix build -o $TEST_ROOT/result --expr "(builtins.getFlake \"$flake1Dir\").defaultPackage.$system")
-nix build -o $TEST_ROOT/result --expr "(builtins.getFlake \"$flake1Dir\").defaultPackage.$system" --impure
+(! nix build -o $TEST_ROOT/result --expr "(builtins.getFlake \"$flake1Dir\").packages.$system.default")
+nix build -o $TEST_ROOT/result --expr "(builtins.getFlake \"$flake1Dir\").packages.$system.default" --impure
 
 # 'getFlake' on an immutable flakeref should succeed even in pure mode.
-nix build -o $TEST_ROOT/result --expr "(builtins.getFlake \"git+file://$flake1Dir?rev=$hash2\").defaultPackage.$system"
+nix build -o $TEST_ROOT/result --expr "(builtins.getFlake \"git+file://$flake1Dir?rev=$hash2\").packages.$system.default"
 
 # Building a flake with an unlocked dependency should fail in pure mode.
 (! nix build -o $TEST_ROOT/result flake2#bar --no-registries)
@@ -370,13 +372,13 @@ cat > $templatesDir/flake.nix <<EOF
   description = "Some templates";
 
   outputs = { self }: {
-    templates = {
+    templates = rec {
       trivial = {
         path = ./trivial;
         description = "A trivial flake";
       };
+      default = trivial;
     };
-    defaultTemplate = self.templates.trivial;
   };
 }
 EOF
@@ -388,8 +390,10 @@ cat > $templatesDir/trivial/flake.nix <<EOF
   description = "A flake for building Hello World";
 
   outputs = { self, nixpkgs }: {
-    packages.x86_64-linux.hello = nixpkgs.legacyPackages.x86_64-linux.hello;
-    defaultPackage.x86_64-linux = self.packages.x86_64-linux.hello;
+    packages.x86_64-linux = rec {
+      hello = nixpkgs.legacyPackages.x86_64-linux.hello;
+      default = hello;
+    };
   };
 }
 EOF
@@ -496,17 +500,15 @@ EOF
 cat > $flake3Dir/flake.nix <<EOF
 {
   outputs = { flake1, self }: {
-    defaultPackage = {
-        system-1 = "foo";
-        system-2 = "bar";
-    };
+    packages.system-1.default = "foo";
+    packages.system-2.default = "bar";
   };
 }
 EOF
 
 checkRes=$(nix flake check --keep-going $flake3Dir 2>&1 && fail "nix flake check should have failed" || true)
-echo "$checkRes" | grep -q "defaultPackage.system-1"
-echo "$checkRes" | grep -q "defaultPackage.system-2"
+echo "$checkRes" | grep -q "packages.system-1.default"
+echo "$checkRes" | grep -q "packages.system-2.default"
 
 # Test 'follows' inputs.
 cat > $flake3Dir/flake.nix <<EOF
@@ -591,7 +593,7 @@ mkdir $flake5Dir
 cat > $flake5Dir/flake.nix <<EOF
 {
   outputs = { self, flake1 }: {
-    defaultPackage.$system = flake1.defaultPackage.$system;
+    packages.$system.default = flake1.packages.$system.default;
     expr = assert builtins.pathExists ./flake.lock; 123;
   };
 }

From d4428d00ae05cd21c256f9490c7f089ec04fd962 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 22 Feb 2022 14:19:39 +0100
Subject: [PATCH 549/567] nix flake check: Warn about deprecated flake outputs

---
 src/nix/flake.cc | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 303edb9fe..14a235501 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -501,6 +501,17 @@ struct CmdFlakeCheck : FlakeCommand
 
                         state->forceValue(vOutput, pos);
 
+                        std::string_view replacement =
+                            name == "defaultPackage" ? "packages.<system>.default" :
+                            name == "defaultApps" ? "apps.<system>.default" :
+                            name == "defaultTemplate" ? "templates.default" :
+                            name == "defaultBundler" ? "bundlers.<system>.default" :
+                            name == "overlay" ? "overlays.default" :
+                            name == "devShell" ? "devShells.<system>.default" :
+                            "";
+                        if (replacement != "")
+                            warn("flake output attribute '%s' is deprecated; use '%s' instead", name, replacement);
+
                         if (name == "checks") {
                             state->forceAttrs(vOutput, pos);
                             for (auto & attr : *vOutput.attrs) {

From 38eea2c503a70e32dd6110937d49705976d5fc7a Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 22 Feb 2022 14:23:39 +0100
Subject: [PATCH 550/567] Update release notes

---
 doc/manual/src/release-notes/rl-next.md | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index 80eed9397..7dd8387d8 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -1,5 +1,18 @@
 # Release X.Y (202?-??-??)
 
+* A number of "default" flake output attributes have been
+  renamed. These are:
+
+  * `defaultPackage.<system>` → `packages.<system>.default`
+  * `defaultApps.<system>` → `apps.<system>.default`
+  * `defaultTemplate` → `templates.default`
+  * `defaultBundler.<system>` → `bundlers.<system>.default`
+  * `overlay` → `overlays.default`
+  * `devShell.<system>` → `devShells.<system>.default`
+
+  The old flake output attributes still work, but `nix flake check`
+  will warn about them.
+
 * `nix bundle` breaking API change now supports bundlers of the form
   `bundler.<system>.<name>= derivation: another-derivation;`. This supports
   additional functionality to inspect evaluation information during bundling. A

From 1a6548ca757f81594f5b54d8dada4c5ba65821de Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 22 Feb 2022 14:32:56 +0100
Subject: [PATCH 551/567] Update docs

---
 src/nix/bundle.md       | 14 ++++++++------
 src/nix/develop.md      |  4 ++--
 src/nix/flake-init.md   |  8 ++++----
 src/nix/flake-show.md   | 11 +++++++----
 src/nix/flake.md        |  2 +-
 src/nix/nix.md          |  6 ++----
 src/nix/profile-list.md |  2 +-
 src/nix/profile.md      |  2 +-
 src/nix/run.md          |  6 +++---
 9 files changed, 29 insertions(+), 26 deletions(-)

diff --git a/src/nix/bundle.md b/src/nix/bundle.md
index a5186a996..2bb70711f 100644
--- a/src/nix/bundle.md
+++ b/src/nix/bundle.md
@@ -42,24 +42,26 @@ homepage](https://github.com/NixOS/bundlers) for more details.
 If no flake output attribute is given, `nix bundle` tries the following
 flake output attributes:
 
-* `defaultBundler.<system>`
+* `bundlers.<system>.default`
 
 If an attribute *name* is given, `nix run` tries the following flake
 output attributes:
 
-* `bundler.<system>.<name>`
+* `bundlers.<system>.<name>`
 
 # Bundlers
 
 A bundler is specified by a flake output attribute named
-`bundlers.<system>.<name>` or `defaultBundler.<system>`. It looks like this:
+`bundlers.<system>.<name>`. It looks like this:
 
 ```nix
-bundlers.x86_64-linux.identity = drv: drv;
+bundlers.x86_64-linux = rec {
+  identity = drv: drv;
 
-bundlers.x86_64-linux.blender_2_79 = drv: self.packages.x86_64-linux.blender_2_79;
+  blender_2_79 = drv: self.packages.x86_64-linux.blender_2_79;
 
-defaultBundler.x86_64-linux = drv: drv;
+  default = identity;
+};
 ```
 
 A bundler must be a function that accepts an arbitrary value (typically a
diff --git a/src/nix/develop.md b/src/nix/develop.md
index 3e7e339d5..8bcff66c9 100644
--- a/src/nix/develop.md
+++ b/src/nix/develop.md
@@ -88,9 +88,9 @@ the flake's `nixConfig` attribute.
 If no flake output attribute is given, `nix develop` tries the following
 flake output attributes:
 
-* `devShell.<system>`
+* `devShells.<system>.default`
 
-* `defaultPackage.<system>`
+* `packages.<system>.default`
 
 If a flake output *name* is given, `nix develop` tries the following flake
 output attributes:
diff --git a/src/nix/flake-init.md b/src/nix/flake-init.md
index c13b22248..fc1f4f805 100644
--- a/src/nix/flake-init.md
+++ b/src/nix/flake-init.md
@@ -24,13 +24,13 @@ R""(
 
 This command creates a flake in the current directory by copying the
 files of a template. It will not overwrite existing files. The default
-template is `templates#defaultTemplate`, but this can be overridden
+template is `templates#templates.default`, but this can be overridden
 using `-t`.
 
 # Template definitions
 
-A flake can declare templates through its `templates` and
-`defaultTemplate` output attributes. A template has two attributes:
+A flake can declare templates through its `templates` output
+attribute. A template has two attributes:
 
 * `description`: A one-line description of the template, in CommonMark
   syntax.
@@ -61,7 +61,7 @@ outputs = { self }: {
     '';
   };
 
-  templates.defaultTemplate = self.templates.rust;
+  templates.default = self.templates.rust;
 }
 ```
 
diff --git a/src/nix/flake-show.md b/src/nix/flake-show.md
index e484cf47e..f3b74285d 100644
--- a/src/nix/flake-show.md
+++ b/src/nix/flake-show.md
@@ -13,10 +13,13 @@ R""(
   │   │   └───build: derivation 'patchelf-0.12.20201207.f34751b'
   │   └───x86_64-linux
   │       └───build: derivation 'patchelf-0.12.20201207.f34751b'
-  ├───defaultPackage
-  │   ├───aarch64-linux: package 'patchelf-0.12.20201207.f34751b'
-  │   ├───i686-linux: package 'patchelf-0.12.20201207.f34751b'
-  │   └───x86_64-linux: package 'patchelf-0.12.20201207.f34751b'
+  ├───packages
+  │   ├───aarch64-linux
+  │   │   └───default: package 'patchelf-0.12.20201207.f34751b'
+  │   ├───i686-linux
+  │   │   └───default: package 'patchelf-0.12.20201207.f34751b'
+  │   └───x86_64-linux
+  │       └───default: package 'patchelf-0.12.20201207.f34751b'
   ├───hydraJobs
   │   ├───build
   │   │   ├───aarch64-linux: derivation 'patchelf-0.12.20201207.f34751b'
diff --git a/src/nix/flake.md b/src/nix/flake.md
index accddd436..48c12d30f 100644
--- a/src/nix/flake.md
+++ b/src/nix/flake.md
@@ -236,7 +236,7 @@ derivation):
 
   outputs = { self, nixpkgs }: {
 
-    defaultPackage.x86_64-linux =
+    packages.x86_64-linux.default =
       # Notice the reference to nixpkgs here.
       with import nixpkgs { system = "x86_64-linux"; };
       stdenv.mkDerivation {
diff --git a/src/nix/nix.md b/src/nix/nix.md
index 1dc59362d..0dacadee6 100644
--- a/src/nix/nix.md
+++ b/src/nix/nix.md
@@ -97,11 +97,9 @@ the Nix store. Here are the recognised types of installables:
     For example, if `/foo/bar/flake.nix` exists, then `/foo/bar/baz/` will resolve to
    `path:/foo/bar`
 
-
-
   If *attrpath* is omitted, Nix tries some default values; for most
-  subcommands, the default is `defaultPackage.`*system*
-  (e.g. `defaultPackage.x86_64-linux`), but some subcommands have
+  subcommands, the default is `packages.`*system*`.default`
+  (e.g. `packages.x86_64-linux.default`), but some subcommands have
   other defaults. If *attrpath* *is* specified, *attrpath* is
   interpreted as relative to one or more prefixes; for most
   subcommands, these are `packages.`*system*,
diff --git a/src/nix/profile-list.md b/src/nix/profile-list.md
index 5c29c0b02..bdab9a208 100644
--- a/src/nix/profile-list.md
+++ b/src/nix/profile-list.md
@@ -8,7 +8,7 @@ R""(
   # nix profile list
   0 flake:nixpkgs#legacyPackages.x86_64-linux.spotify github:NixOS/nixpkgs/c23db78bbd474c4d0c5c3c551877523b4a50db06#legacyPackages.x86_64-linux.spotify /nix/store/akpdsid105phbbvknjsdh7hl4v3fhjkr-spotify-1.1.46.916.g416cacf1
   1 flake:nixpkgs#legacyPackages.x86_64-linux.zoom-us github:NixOS/nixpkgs/c23db78bbd474c4d0c5c3c551877523b4a50db06#legacyPackages.x86_64-linux.zoom-us /nix/store/89pmjmbih5qpi7accgacd17ybpgp4xfm-zoom-us-5.4.53350.1027
-  2 flake:blender-bin#defaultPackage.x86_64-linux github:edolstra/nix-warez/d09d7eea893dcb162e89bc67f6dc1ced14abfc27?dir=blender#defaultPackage.x86_64-linux /nix/store/zfgralhqjnam662kqsgq6isjw8lhrflz-blender-bin-2.91.0
+  2 flake:blender-bin#packages.x86_64-linux.default github:edolstra/nix-warez/d09d7eea893dcb162e89bc67f6dc1ced14abfc27?dir=blender#packages.x86_64-linux.default /nix/store/zfgralhqjnam662kqsgq6isjw8lhrflz-blender-bin-2.91.0
   ```
 
 # Description
diff --git a/src/nix/profile.md b/src/nix/profile.md
index d3ddcd3d1..0a4ff2fa9 100644
--- a/src/nix/profile.md
+++ b/src/nix/profile.md
@@ -96,7 +96,7 @@ has the following fields:
   user specified, but the one resulting from applying the default
   attribute paths and prefixes; for instance, `hello` might resolve to
   `packages.x86_64-linux.hello` and the empty string to
-  `defaultPackage.x86_64-linux`.
+  `packages.x86_64-linux.default`.
 
 * `storePath`: The paths in the Nix store containing the package.
 
diff --git a/src/nix/run.md b/src/nix/run.md
index cd3b978c0..a0f362076 100644
--- a/src/nix/run.md
+++ b/src/nix/run.md
@@ -58,9 +58,9 @@ For instance, if `name` is set to `hello-1.10`, `nix run` will run
 If no flake output attribute is given, `nix run` tries the following
 flake output attributes:
 
-* `defaultApp.<system>`
+* `apps.<system>.default`
 
-* `defaultPackage.<system>`
+* `packages.<system>.default`
 
 If an attribute *name* is given, `nix run` tries the following flake
 output attributes:
@@ -74,7 +74,7 @@ output attributes:
 # Apps
 
 An app is specified by a flake output attribute named
-`apps.<system>.<name>` or `defaultApp.<system>`. It looks like this:
+`apps.<system>.<name>`. It looks like this:
 
 ```nix
 apps.x86_64-linux.blender_2_79 = {

From ba9a8c4b3d0f8f008a2067e26e89d6165d14c814 Mon Sep 17 00:00:00 2001
From: "Travis A. Everett" <travis.a.everett@gmail.com>
Date: Tue, 22 Feb 2022 12:44:15 -0600
Subject: [PATCH 552/567] install-darwin: track mount permission edge-case fix

Same as 1fd127a06833c19a5a2965bd41cf4f695773cca6, but applied to a
code path (volume_pass_works -> verify_volume_pass) that the reporting
user didn't hit and wasn't able to trigger manually. I am not certain
but I suspect it will be easier to add prophylactically than to debug
if its absence causes trouble some day.
---
 scripts/create-darwin-volume.sh | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/scripts/create-darwin-volume.sh b/scripts/create-darwin-volume.sh
index ece4f29bb..4bac4b7ba 100755
--- a/scripts/create-darwin-volume.sh
+++ b/scripts/create-darwin-volume.sh
@@ -246,7 +246,8 @@ get_volume_pass() {
 verify_volume_pass() {
     local volume_special="$1" # (i.e., disk1s7)
     local volume_uuid="$2"
-    /usr/sbin/diskutil apfs unlockVolume "$volume_special" -verify -stdinpassphrase -user "$volume_uuid"
+    _sudo "to confirm the password actually unlocks the volume" \
+        /usr/sbin/diskutil apfs unlockVolume "$volume_special" -verify -stdinpassphrase -user "$volume_uuid"
 }
 
 volume_pass_works() {

From 54f07b66c87fd749f7ecfaeb89d878557b625d78 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophane=20Hufschmitt?=
 <7226587+thufschmitt@users.noreply.github.com>
Date: Wed, 23 Feb 2022 09:17:08 +0100
Subject: [PATCH 553/567] Precise the doc for `--include-outputs`
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Make it explicit that it only includes the existing outputs and not the ones that haven’t been realised
---
 doc/manual/src/command-ref/nix-store.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/doc/manual/src/command-ref/nix-store.md b/doc/manual/src/command-ref/nix-store.md
index 26292f1bb..7db9f0c1c 100644
--- a/doc/manual/src/command-ref/nix-store.md
+++ b/doc/manual/src/command-ref/nix-store.md
@@ -321,8 +321,8 @@ symlink.
     This query has one option:
 
       - `--include-outputs`
-        Also include the output path of store derivations, and their
-        closures.
+        Also include the existing output paths of store derivations,
+        and their closures.
 
     This query can be used to implement various kinds of deployment. A
     *source deployment* is obtained by distributing the closure of a

From 2cc645a91a07458fd23e0aacd6ccdf63cad199b9 Mon Sep 17 00:00:00 2001
From: Guillaume Desforges <guillaume.desforges.pro@gmail.com>
Date: Wed, 23 Feb 2022 15:06:13 +0100
Subject: [PATCH 554/567] Add html make target

---
 doc/manual/local.mk | 1 +
 1 file changed, 1 insertion(+)

diff --git a/doc/manual/local.mk b/doc/manual/local.mk
index 6b232a736..c1ce8aaeb 100644
--- a/doc/manual/local.mk
+++ b/doc/manual/local.mk
@@ -72,6 +72,7 @@ $(d)/builtins.json: $(bindir)/nix
 	@mv $@.tmp $@
 
 # Generate the HTML manual.
+html: $(docdir)/manual/index.html
 install: $(docdir)/manual/index.html
 
 # Generate 'nix' manpages.

From 6462ee61c7c6ea7a93c01c89bf311fe8f454f35f Mon Sep 17 00:00:00 2001
From: Guillaume Desforges <guillaume.desforges.pro@gmail.com>
Date: Wed, 23 Feb 2022 15:07:01 +0100
Subject: [PATCH 555/567] Anchor link for builtin functions in HTML doc

---
 doc/manual/generate-builtins.nix | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/doc/manual/generate-builtins.nix b/doc/manual/generate-builtins.nix
index 92c7b1a31..b481beecd 100644
--- a/doc/manual/generate-builtins.nix
+++ b/doc/manual/generate-builtins.nix
@@ -6,9 +6,9 @@ builtins:
 concatStrings (map
   (name:
     let builtin = builtins.${name}; in
-    "<dt><code>${name} "
+    "<dt id=\"${name}\"><a href=\"#${name}\"><code>${name} "
     + concatStringsSep " " (map (s: "<var>${s}</var>") builtin.args)
-    + "</code></dt>"
+    + "</code></a></dt>"
     + "<dd>\n\n"
     + builtin.doc
     + "\n\n</dd>"

From 770f3af31df552c47ac6bc38d386d10f8ff1c856 Mon Sep 17 00:00:00 2001
From: Gabriel Fontes <eu@misterio.me>
Date: Wed, 23 Feb 2022 11:58:09 -0300
Subject: [PATCH 556/567] add sourcehut integration test

---
 flake.nix                  |   6 ++
 tests/sourcehut-flakes.nix | 156 +++++++++++++++++++++++++++++++++++++
 2 files changed, 162 insertions(+)
 create mode 100644 tests/sourcehut-flakes.nix

diff --git a/flake.nix b/flake.nix
index ae9305144..87b00edf4 100644
--- a/flake.nix
+++ b/flake.nix
@@ -501,6 +501,12 @@
           inherit (self) overlay;
         });
 
+        tests.sourcehutFlakes = (import ./tests/sourcehut-flakes.nix rec {
+          system = "x86_64-linux";
+          inherit nixpkgs;
+          inherit (self) overlay;
+        });
+
         tests.setuid = nixpkgs.lib.genAttrs
           ["i686-linux" "x86_64-linux"]
           (system:
diff --git a/tests/sourcehut-flakes.nix b/tests/sourcehut-flakes.nix
new file mode 100644
index 000000000..d1d89d149
--- /dev/null
+++ b/tests/sourcehut-flakes.nix
@@ -0,0 +1,156 @@
+{ nixpkgs, system, overlay }:
+
+with import (nixpkgs + "/nixos/lib/testing-python.nix")
+{
+  inherit system;
+  extraConfigurations = [{ nixpkgs.overlays = [ overlay ]; }];
+};
+
+let
+  # Generate a fake root CA and a fake git.sr.ht certificate.
+  cert = pkgs.runCommand "cert" { buildInputs = [ pkgs.openssl ]; }
+    ''
+      mkdir -p $out
+
+      openssl genrsa -out ca.key 2048
+      openssl req -new -x509 -days 36500 -key ca.key \
+        -subj "/C=NL/ST=Denial/L=Springfield/O=Dis/CN=Root CA" -out $out/ca.crt
+
+      openssl req -newkey rsa:2048 -nodes -keyout $out/server.key \
+        -subj "/C=CN/ST=Denial/L=Springfield/O=Dis/CN=git.sr.ht" -out server.csr
+      openssl x509 -req -extfile <(printf "subjectAltName=DNS:git.sr.ht") \
+        -days 36500 -in server.csr -CA $out/ca.crt -CAkey ca.key -CAcreateserial -out $out/server.crt
+    '';
+
+  registry = pkgs.writeTextFile {
+    name = "registry";
+    text = ''
+      {
+        "flakes": [
+          {
+            "from": {
+              "type": "indirect",
+              "id": "nixpkgs"
+            },
+            "to": {
+              "type": "sourcehut",
+              "owner": "~NixOS",
+              "repo": "nixpkgs"
+            }
+          }
+        ],
+        "version": 2
+      }
+    '';
+    destination = "/flake-registry.json";
+  };
+
+  nixpkgs-repo = pkgs.runCommand "nixpkgs-flake" { }
+    ''
+      dir=NixOS-nixpkgs-${nixpkgs.shortRev}
+      cp -prd ${nixpkgs} $dir
+
+      # Set the correct timestamp in the tarball.
+      find $dir -print0 | xargs -0 touch -t ${builtins.substring 0 12 nixpkgs.lastModifiedDate}.${builtins.substring 12 2 nixpkgs.lastModifiedDate} --
+
+      mkdir -p $out/archive
+      tar cfz $out/archive/${nixpkgs.rev}.tar.gz $dir --hard-dereference
+
+      echo 'ref: refs/heads/master' > $out/HEAD
+
+      mkdir -p $out/info
+      echo '${nixpkgs.rev} refs/heads/master' > $out/info/refs
+    '';
+
+in
+
+makeTest (
+
+  {
+    name = "sourcehut-flakes";
+
+    nodes =
+      {
+        # Impersonate git.sr.ht
+        sourcehut =
+          { config, pkgs, ... }:
+          {
+            networking.firewall.allowedTCPPorts = [ 80 443 ];
+
+            services.httpd.enable = true;
+            services.httpd.adminAddr = "foo@example.org";
+            services.httpd.extraConfig = ''
+              ErrorLog syslog:local6
+            '';
+            services.httpd.virtualHosts."git.sr.ht" =
+              {
+                forceSSL = true;
+                sslServerKey = "${cert}/server.key";
+                sslServerCert = "${cert}/server.crt";
+                servedDirs =
+                  [
+                    {
+                      urlPath = "/~NixOS/nixpkgs";
+                      dir = nixpkgs-repo;
+                    }
+                    {
+                      urlPath = "/~NixOS/flake-registry/blob/master";
+                      dir = registry;
+                    }
+                  ];
+              };
+          };
+
+        client =
+          { config, lib, pkgs, nodes, ... }:
+          {
+            virtualisation.writableStore = true;
+            virtualisation.diskSize = 2048;
+            virtualisation.pathsInNixDB = [ pkgs.hello pkgs.fuse ];
+            virtualisation.memorySize = 4096;
+            nix.binaryCaches = lib.mkForce [ ];
+            nix.extraOptions = ''
+              experimental-features = nix-command flakes
+              flake-registry = https://git.sr.ht/~NixOS/flake-registry/blob/master/flake-registry.json
+            '';
+            environment.systemPackages = [ pkgs.jq ];
+            networking.hosts.${(builtins.head nodes.sourcehut.config.networking.interfaces.eth1.ipv4.addresses).address} =
+              [ "git.sr.ht" ];
+            security.pki.certificateFiles = [ "${cert}/ca.crt" ];
+          };
+      };
+
+    testScript = { nodes }: ''
+      # fmt: off
+      import json
+      import time
+
+      start_all()
+
+      sourcehut.wait_for_unit("httpd.service")
+
+      client.succeed("curl -v https://git.sr.ht/ >&2")
+      client.succeed("nix registry list | grep nixpkgs")
+
+      rev = client.succeed("nix flake info nixpkgs --json | jq -r .revision")
+      assert rev.strip() == "${nixpkgs.rev}", "revision mismatch"
+
+      client.succeed("nix registry pin nixpkgs")
+
+      client.succeed("nix flake info nixpkgs --tarball-ttl 0 >&2")
+
+      # Shut down the web server. The flake should be cached on the client.
+      sourcehut.succeed("systemctl stop httpd.service")
+
+      info = json.loads(client.succeed("nix flake info nixpkgs --json"))
+      date = time.strftime("%Y%m%d%H%M%S", time.gmtime(info['lastModified']))
+      assert date == "${nixpkgs.lastModifiedDate}", "time mismatch"
+
+      client.succeed("nix build nixpkgs#hello")
+
+      # The build shouldn't fail even with --tarball-ttl 0 (the server
+      # being down should not be a fatal error).
+      client.succeed("nix build nixpkgs#fuse --tarball-ttl 0")
+    '';
+
+  })

From cfbf9ee2ce35b64ced1822c132bd46bd4fd848b2 Mon Sep 17 00:00:00 2001
From: Guillaume Desforges <guillaume.desforges.pro@gmail.com>
Date: Thu, 24 Feb 2022 13:50:50 +0100
Subject: [PATCH 557/567] Anchor with prefix

---
 doc/manual/generate-builtins.nix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/manual/generate-builtins.nix b/doc/manual/generate-builtins.nix
index b481beecd..6c8b88da2 100644
--- a/doc/manual/generate-builtins.nix
+++ b/doc/manual/generate-builtins.nix
@@ -6,7 +6,7 @@ builtins:
 concatStrings (map
   (name:
     let builtin = builtins.${name}; in
-    "<dt id=\"${name}\"><a href=\"#${name}\"><code>${name} "
+    "<dt id=\"builtins-${name}\"><a href=\"#builtins-${name}\"><code>${name} "
     + concatStringsSep " " (map (s: "<var>${s}</var>") builtin.args)
     + "</code></a></dt>"
     + "<dd>\n\n"

From 42766f89246ded45d80bdf62061cbafc42540c54 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Thu, 24 Feb 2022 14:15:27 +0100
Subject: [PATCH 558/567] Sort the tests by wall time

The tests are scheduled in the order they appear, so running the long
ones first slightly improves the scheduling.

On my machine, this decreases the time of `make install` from 40s to 36s
---
 tests/local.mk | 124 ++++++++++++++++++++++++++++++-------------------
 1 file changed, 75 insertions(+), 49 deletions(-)

diff --git a/tests/local.mk b/tests/local.mk
index 47717fa67..53a9179a3 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -1,72 +1,98 @@
 nix_tests = \
-  hash.sh lang.sh add.sh simple.sh dependencies.sh \
-  config.sh \
-  gc.sh \
+  flakes.sh \
   ca/gc.sh \
-  gc-concurrent.sh \
-  gc-non-blocking.sh \
+  gc.sh \
+  remote-store.sh \
+  lang.sh \
+  fetchMercurial.sh \
   gc-auto.sh \
-  referrers.sh user-envs.sh logging.sh nix-build.sh misc.sh fixed.sh \
-  gc-runtime.sh check-refs.sh filter-source.sh \
-  local-store.sh remote-store.sh export.sh export-graph.sh \
-  db-migration.sh \
-  timeout.sh secure-drv-outputs.sh nix-channel.sh \
-  multiple-outputs.sh import-derivation.sh ca/import-derivation.sh fetchurl.sh optimise-store.sh \
+  user-envs.sh \
   binary-cache.sh \
+  multiple-outputs.sh \
+  ca/build.sh \
+  nix-build.sh \
+  gc-concurrent.sh \
+  repair.sh \
+  fixed.sh \
+  export-graph.sh \
+  timeout.sh \
+  fetchGitRefs.sh \
+  gc-runtime.sh \
+  tarball.sh \
+  fetchGit.sh \
+  fetchurl.sh \
+  simple.sh \
+  referrers.sh \
+  optimise-store.sh \
   substitute-with-invalid-ca.sh \
-  binary-cache-build-remote.sh \
-  nix-profile.sh repair.sh dump-db.sh case-hack.sh \
-  check-reqs.sh pass-as-file.sh tarball.sh restricted.sh \
-  placeholders.sh nix-shell.sh \
-  linux-sandbox.sh \
-  build-dry.sh \
+  ca/concurrent-builds.sh \
+  signing.sh \
+  ca/build-with-garbage-path.sh \
+  hash.sh \
+  gc-non-blocking.sh \
+  check.sh \
+  ca/substitute.sh \
+  nix-shell.sh \
+  ca/signatures.sh \
+  ca/nix-shell.sh \
+  ca/nix-copy.sh \
+  check-refs.sh \
   build-remote-input-addressed.sh \
+  secure-drv-outputs.sh \
+  restricted.sh \
+  fetchGitSubmodules.sh \
+  flake-searching.sh \
+  ca/duplicate-realisation-in-closure.sh \
+  readfile-context.sh \
+  nix-channel.sh \
+  recursive.sh \
+  dependencies.sh \
+  check-reqs.sh \
   build-remote-content-addressed-fixed.sh \
   build-remote-content-addressed-floating.sh \
-  ssh-relay.sh \
   nar-access.sh \
+  pure-eval.sh \
+  ca/post-hook.sh \
+  repl.sh \
+  ca/repl.sh \
+  ca/recursive.sh \
+  binary-cache-build-remote.sh \
+  search.sh \
+  logging.sh \
+  export.sh \
+  config.sh \
+  add.sh \
+  local-store.sh \
+  filter-source.sh \
+  misc.sh \
+  dump-db.sh \
+  linux-sandbox.sh \
+  build-dry.sh \
   structured-attrs.sh \
-  fetchGit.sh \
-  fetchGitRefs.sh \
-  fetchGitSubmodules.sh \
-  fetchMercurial.sh \
-  signing.sh \
   shell.sh \
   brotli.sh \
   zstd.sh \
   compression-levels.sh \
-  pure-eval.sh \
-  check.sh \
-  plugins.sh \
-  search.sh \
   nix-copy-ssh.sh \
   post-hook.sh \
-  ca/post-hook.sh \
   function-trace.sh \
-  recursive.sh \
-  describe-stores.sh \
-  flakes.sh \
   flake-local-settings.sh \
-  flake-searching.sh \
-  flake-bundler.sh \
-  build.sh \
-  repl.sh ca/repl.sh \
-  ca/build.sh \
-  ca/build-with-garbage-path.sh \
-  ca/duplicate-realisation-in-closure.sh \
-  ca/substitute.sh \
-  ca/signatures.sh \
-  ca/nix-shell.sh \
-  ca/nix-run.sh \
-  ca/recursive.sh \
-  ca/concurrent-builds.sh \
-  ca/nix-copy.sh \
   eval-store.sh \
-  readfile-context.sh \
-  store-ping.sh \
+  why-depends.sh \
+  import-derivation.sh \
+  ca/import-derivation.sh \
   nix_path.sh \
-  why-depends.sh
-  # parallel.sh
+  case-hack.sh \
+  placeholders.sh \
+  ssh-relay.sh \
+  plugins.sh \
+  build.sh \
+  ca/nix-run.sh \
+  db-migration.sh \
+  nix-profile.sh \
+  pass-as-file.sh \
+  describe-stores.sh \
+  store-ping.sh
 
 ifeq ($(HAVE_LIBCPUID), 1)
 	nix_tests += compute-levels.sh

From 9c470cb9694408078fa2c289b9b776820e611923 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Thu, 24 Feb 2022 14:57:27 +0100
Subject: [PATCH 559/567] testS: poll more eagerly for the daemon start/stop

Polling every 1 second means that even the simplest test takes at least
2 seconds. We can reasonably poll 1/10 of that to make things much
  quicker (esp. given that most of the time 0.1s is enough for the
  daemon to be started or stopped)
---
 tests/common.sh.in | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tests/common.sh.in b/tests/common.sh.in
index 61abab1d7..49068f1c3 100644
--- a/tests/common.sh.in
+++ b/tests/common.sh.in
@@ -91,9 +91,9 @@ startDaemon() {
     # ‘nix-daemon’ should have an option to fork into the background.
     rm -f $NIX_DAEMON_SOCKET_PATH
     PATH=$DAEMON_PATH nix daemon &
-    for ((i = 0; i < 30; i++)); do
+    for ((i = 0; i < 300; i++)); do
         if [[ -S $NIX_DAEMON_SOCKET_PATH ]]; then break; fi
-        sleep 1
+        sleep 0.1
     done
     pidDaemon=$!
     trap "killDaemon" EXIT
@@ -102,9 +102,9 @@ startDaemon() {
 
 killDaemon() {
     kill $pidDaemon
-    for i in {0.10}; do
+    for i in {0..100}; do
         kill -0 $pidDaemon || break
-        sleep 1
+        sleep 0.1
     done
     kill -9 $pidDaemon || true
     wait $pidDaemon || true

From 8518cebfceb36f3744c276cc8dbf432b1275f53f Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 24 Feb 2022 18:09:00 +0100
Subject: [PATCH 560/567] libfetchers: Rename immutable -> locked

This is more consistent with flake terminology.
---
 src/libexpr/flake/flake.cc       |  8 ++++----
 src/libexpr/flake/lockfile.cc    |  4 ++--
 src/libexpr/primops/fetchTree.cc |  6 +++---
 src/libfetchers/cache.cc         |  8 ++++----
 src/libfetchers/cache.hh         |  2 +-
 src/libfetchers/fetchers.cc      |  8 ++++----
 src/libfetchers/fetchers.hh      | 12 +++++++-----
 src/libfetchers/git.cc           | 14 +++++++-------
 src/libfetchers/github.cc        |  6 +++---
 src/libfetchers/mercurial.cc     | 14 +++++++-------
 src/libfetchers/tarball.cc       | 14 +++++++-------
 src/nix/profile.cc               |  2 +-
 src/nix/repl.cc                  |  4 ++--
 13 files changed, 52 insertions(+), 50 deletions(-)

diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 9f3b58909..6e3fa41f7 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -501,7 +501,7 @@ LockedFlake lockFlake(
                            this input. */
                         debug("creating new input '%s'", inputPathS);
 
-                        if (!lockFlags.allowMutable && !input.ref->input.isImmutable())
+                        if (!lockFlags.allowMutable && !input.ref->input.isLocked())
                             throw Error("cannot update flake input '%s' in pure mode", inputPathS);
 
                         if (input.isFlake) {
@@ -650,7 +650,7 @@ LockedFlake lockFlake(
                            now. Corner case: we could have reverted from a
                            dirty to a clean tree! */
                         if (flake.lockedRef.input == prevLockedRef.input
-                            && !flake.lockedRef.input.isImmutable())
+                            && !flake.lockedRef.input.isLocked())
                             throw Error("'%s' did not change after I updated its 'flake.lock' file; is 'flake.lock' under version control?", flake.originalRef);
                     }
                 } else
@@ -709,8 +709,8 @@ static void prim_getFlake(EvalState & state, const Pos & pos, Value * * args, Va
 
     string flakeRefS(state.forceStringNoCtx(*args[0], pos));
     auto flakeRef = parseFlakeRef(flakeRefS, {}, true);
-    if (evalSettings.pureEval && !flakeRef.input.isImmutable())
-        throw Error("cannot call 'getFlake' on mutable flake reference '%s', at %s (use --impure to override)", flakeRefS, pos);
+    if (evalSettings.pureEval && !flakeRef.input.isLocked())
+        throw Error("cannot call 'getFlake' on unlocked flake reference '%s', at %s (use --impure to override)", flakeRefS, pos);
 
     callFlake(state,
         lockFlake(state, flakeRef,
diff --git a/src/libexpr/flake/lockfile.cc b/src/libexpr/flake/lockfile.cc
index fda340789..60b52d578 100644
--- a/src/libexpr/flake/lockfile.cc
+++ b/src/libexpr/flake/lockfile.cc
@@ -35,7 +35,7 @@ LockedNode::LockedNode(const nlohmann::json & json)
     , originalRef(getFlakeRef(json, "original", nullptr))
     , isFlake(json.find("flake") != json.end() ? (bool) json["flake"] : true)
 {
-    if (!lockedRef.input.isImmutable())
+    if (!lockedRef.input.isLocked())
         throw Error("lockfile contains mutable lock '%s'",
             fetchers::attrsToJSON(lockedRef.input.toAttrs()));
 }
@@ -220,7 +220,7 @@ bool LockFile::isImmutable() const
     for (auto & i : nodes) {
         if (i == root) continue;
         auto lockedNode = std::dynamic_pointer_cast<const LockedNode>(i);
-        if (lockedNode && !lockedNode->lockedRef.input.isImmutable()) return false;
+        if (lockedNode && !lockedNode->lockedRef.input.isLocked()) return false;
     }
 
     return true;
diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index d09e2d9e1..7496104b6 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -19,7 +19,7 @@ void emitTreeAttrs(
     bool emptyRevFallback,
     bool forceDirty)
 {
-    assert(input.isImmutable());
+    assert(input.isLocked());
 
     auto attrs = state.buildBindings(8);
 
@@ -166,8 +166,8 @@ static void fetchTree(
     if (!evalSettings.pureEval && !input.isDirect())
         input = lookupInRegistries(state.store, input).first;
 
-    if (evalSettings.pureEval && !input.isImmutable())
-        throw Error("in pure evaluation mode, 'fetchTree' requires an immutable input, at %s", pos);
+    if (evalSettings.pureEval && !input.isLocked())
+        throw Error("in pure evaluation mode, 'fetchTree' requires a locked input, at %s", pos);
 
     auto [tree, input2] = input.fetch(state.store);
 
diff --git a/src/libfetchers/cache.cc b/src/libfetchers/cache.cc
index 34ff6f85b..0c8ecac9d 100644
--- a/src/libfetchers/cache.cc
+++ b/src/libfetchers/cache.cc
@@ -52,13 +52,13 @@ struct CacheImpl : Cache
         const Attrs & inAttrs,
         const Attrs & infoAttrs,
         const StorePath & storePath,
-        bool immutable) override
+        bool locked) override
     {
         _state.lock()->add.use()
             (attrsToJSON(inAttrs).dump())
             (attrsToJSON(infoAttrs).dump())
             (store->printStorePath(storePath))
-            (immutable)
+            (locked)
             (time(0)).exec();
     }
 
@@ -91,7 +91,7 @@ struct CacheImpl : Cache
 
         auto infoJSON = stmt.getStr(0);
         auto storePath = store->parseStorePath(stmt.getStr(1));
-        auto immutable = stmt.getInt(2) != 0;
+        auto locked = stmt.getInt(2) != 0;
         auto timestamp = stmt.getInt(3);
 
         store->addTempRoot(storePath);
@@ -105,7 +105,7 @@ struct CacheImpl : Cache
             inAttrsJSON, infoJSON, store->printStorePath(storePath));
 
         return Result {
-            .expired = !immutable && (settings.tarballTtl.get() == 0 || timestamp + settings.tarballTtl < time(0)),
+            .expired = !locked && (settings.tarballTtl.get() == 0 || timestamp + settings.tarballTtl < time(0)),
             .infoAttrs = jsonToAttrs(nlohmann::json::parse(infoJSON)),
             .storePath = std::move(storePath)
         };
diff --git a/src/libfetchers/cache.hh b/src/libfetchers/cache.hh
index 3db4f081c..3763ee2a6 100644
--- a/src/libfetchers/cache.hh
+++ b/src/libfetchers/cache.hh
@@ -13,7 +13,7 @@ struct Cache
         const Attrs & inAttrs,
         const Attrs & infoAttrs,
         const StorePath & storePath,
-        bool immutable) = 0;
+        bool locked) = 0;
 
     virtual std::optional<std::pair<Attrs, StorePath>> lookup(
         ref<Store> store,
diff --git a/src/libfetchers/fetchers.cc b/src/libfetchers/fetchers.cc
index c06ccb929..976f40d3b 100644
--- a/src/libfetchers/fetchers.cc
+++ b/src/libfetchers/fetchers.cc
@@ -24,11 +24,11 @@ static void fixupInput(Input & input)
     input.getType();
     input.getRef();
     if (input.getRev())
-        input.immutable = true;
+        input.locked = true;
     input.getRevCount();
     input.getLastModified();
     if (input.getNarHash())
-        input.immutable = true;
+        input.locked = true;
 }
 
 Input Input::fromURL(const ParsedURL & url)
@@ -165,7 +165,7 @@ std::pair<Tree, Input> Input::fetch(ref<Store> store) const
                 input.to_string(), *prevRevCount);
     }
 
-    input.immutable = true;
+    input.locked = true;
 
     assert(input.hasAllInfo());
 
@@ -209,7 +209,7 @@ StorePath Input::computeStorePath(Store & store) const
 {
     auto narHash = getNarHash();
     if (!narHash)
-        throw Error("cannot compute store path for mutable input '%s'", to_string());
+        throw Error("cannot compute store path for unlocked input '%s'", to_string());
     return store.makeFixedOutputPath(FileIngestionMethod::Recursive, *narHash, getName());
 }
 
diff --git a/src/libfetchers/fetchers.hh b/src/libfetchers/fetchers.hh
index 2836af5fa..bc9a76b0b 100644
--- a/src/libfetchers/fetchers.hh
+++ b/src/libfetchers/fetchers.hh
@@ -34,7 +34,7 @@ struct Input
 
     std::shared_ptr<InputScheme> scheme; // note: can be null
     Attrs attrs;
-    bool immutable = false;
+    bool locked = false;
     bool direct = true;
 
     /* path of the parent of this input, used for relative path resolution */
@@ -59,9 +59,9 @@ public:
        one that goes through a registry. */
     bool isDirect() const { return direct; }
 
-    /* Check whether this is an "immutable" input, that is,
+    /* Check whether this is a "locked" input, that is,
        one that contains a commit hash or content hash. */
-    bool isImmutable() const { return immutable; }
+    bool isLocked() const { return locked; }
 
     bool hasAllInfo() const;
 
@@ -69,6 +69,8 @@ public:
 
     bool contains(const Input & other) const;
 
+    /* Fetch the input into the Nix store, returning the location in
+       the Nix store and the locked input. */
     std::pair<Tree, Input> fetch(ref<Store> store) const;
 
     Input applyOverrides(
@@ -146,14 +148,14 @@ DownloadFileResult downloadFile(
     ref<Store> store,
     const std::string & url,
     const std::string & name,
-    bool immutable,
+    bool locked,
     const Headers & headers = {});
 
 std::pair<Tree, time_t> downloadTarball(
     ref<Store> store,
     const std::string & url,
     const std::string & name,
-    bool immutable,
+    bool locked,
     const Headers & headers = {});
 
 }
diff --git a/src/libfetchers/git.cc b/src/libfetchers/git.cc
index c3f0f8c8f..7f65c1533 100644
--- a/src/libfetchers/git.cc
+++ b/src/libfetchers/git.cc
@@ -187,7 +187,7 @@ struct GitInputScheme : InputScheme
         if (submodules) cacheType += "-submodules";
         if (allRefs) cacheType += "-all-refs";
 
-        auto getImmutableAttrs = [&]()
+        auto getLockedAttrs = [&]()
         {
             return Attrs({
                 {"type", cacheType},
@@ -208,7 +208,7 @@ struct GitInputScheme : InputScheme
         };
 
         if (input.getRev()) {
-            if (auto res = getCache()->lookup(store, getImmutableAttrs()))
+            if (auto res = getCache()->lookup(store, getLockedAttrs()))
                 return makeResult(res->first, std::move(res->second));
         }
 
@@ -288,7 +288,7 @@ struct GitInputScheme : InputScheme
 
         if (!input.getRef()) input.attrs.insert_or_assign("ref", isLocal ? readHead(actualUrl) : "master");
 
-        Attrs mutableAttrs({
+        Attrs unlockedAttrs({
             {"type", cacheType},
             {"name", name},
             {"url", actualUrl},
@@ -307,7 +307,7 @@ struct GitInputScheme : InputScheme
 
         } else {
 
-            if (auto res = getCache()->lookup(store, mutableAttrs)) {
+            if (auto res = getCache()->lookup(store, unlockedAttrs)) {
                 auto rev2 = Hash::parseAny(getStrAttr(res->first, "rev"), htSHA1);
                 if (!input.getRev() || input.getRev() == rev2) {
                     input.attrs.insert_or_assign("rev", rev2.gitRev());
@@ -404,7 +404,7 @@ struct GitInputScheme : InputScheme
 
         /* Now that we know the ref, check again whether we have it in
            the store. */
-        if (auto res = getCache()->lookup(store, getImmutableAttrs()))
+        if (auto res = getCache()->lookup(store, getLockedAttrs()))
             return makeResult(res->first, std::move(res->second));
 
         Path tmpDir = createTempDir();
@@ -476,14 +476,14 @@ struct GitInputScheme : InputScheme
         if (!_input.getRev())
             getCache()->add(
                 store,
-                mutableAttrs,
+                unlockedAttrs,
                 infoAttrs,
                 storePath,
                 false);
 
         getCache()->add(
             store,
-            getImmutableAttrs(),
+            getLockedAttrs(),
             infoAttrs,
             storePath,
             true);
diff --git a/src/libfetchers/github.cc b/src/libfetchers/github.cc
index 2b3705b1b..70622bf79 100644
--- a/src/libfetchers/github.cc
+++ b/src/libfetchers/github.cc
@@ -193,12 +193,12 @@ struct GitArchiveInputScheme : InputScheme
         input.attrs.erase("ref");
         input.attrs.insert_or_assign("rev", rev->gitRev());
 
-        Attrs immutableAttrs({
+        Attrs lockedAttrs({
             {"type", "git-tarball"},
             {"rev", rev->gitRev()},
         });
 
-        if (auto res = getCache()->lookup(store, immutableAttrs)) {
+        if (auto res = getCache()->lookup(store, lockedAttrs)) {
             input.attrs.insert_or_assign("lastModified", getIntAttr(res->first, "lastModified"));
             return {std::move(res->second), input};
         }
@@ -211,7 +211,7 @@ struct GitArchiveInputScheme : InputScheme
 
         getCache()->add(
             store,
-            immutableAttrs,
+            lockedAttrs,
             {
                 {"rev", rev->gitRev()},
                 {"lastModified", uint64_t(lastModified)}
diff --git a/src/libfetchers/mercurial.cc b/src/libfetchers/mercurial.cc
index 5123bcda4..798369c7a 100644
--- a/src/libfetchers/mercurial.cc
+++ b/src/libfetchers/mercurial.cc
@@ -199,7 +199,7 @@ struct MercurialInputScheme : InputScheme
 
         if (!input.getRef()) input.attrs.insert_or_assign("ref", "default");
 
-        auto getImmutableAttrs = [&]()
+        auto getLockedAttrs = [&]()
         {
             return Attrs({
                 {"type", "hg"},
@@ -218,20 +218,20 @@ struct MercurialInputScheme : InputScheme
         };
 
         if (input.getRev()) {
-            if (auto res = getCache()->lookup(store, getImmutableAttrs()))
+            if (auto res = getCache()->lookup(store, getLockedAttrs()))
                 return makeResult(res->first, std::move(res->second));
         }
 
         auto revOrRef = input.getRev() ? input.getRev()->gitRev() : *input.getRef();
 
-        Attrs mutableAttrs({
+        Attrs unlockedAttrs({
             {"type", "hg"},
             {"name", name},
             {"url", actualUrl},
             {"ref", *input.getRef()},
         });
 
-        if (auto res = getCache()->lookup(store, mutableAttrs)) {
+        if (auto res = getCache()->lookup(store, unlockedAttrs)) {
             auto rev2 = Hash::parseAny(getStrAttr(res->first, "rev"), htSHA1);
             if (!input.getRev() || input.getRev() == rev2) {
                 input.attrs.insert_or_assign("rev", rev2.gitRev());
@@ -277,7 +277,7 @@ struct MercurialInputScheme : InputScheme
         auto revCount = std::stoull(tokens[1]);
         input.attrs.insert_or_assign("ref", tokens[2]);
 
-        if (auto res = getCache()->lookup(store, getImmutableAttrs()))
+        if (auto res = getCache()->lookup(store, getLockedAttrs()))
             return makeResult(res->first, std::move(res->second));
 
         Path tmpDir = createTempDir();
@@ -297,14 +297,14 @@ struct MercurialInputScheme : InputScheme
         if (!_input.getRev())
             getCache()->add(
                 store,
-                mutableAttrs,
+                unlockedAttrs,
                 infoAttrs,
                 storePath,
                 false);
 
         getCache()->add(
             store,
-            getImmutableAttrs(),
+            getLockedAttrs(),
             infoAttrs,
             storePath,
             true);
diff --git a/src/libfetchers/tarball.cc b/src/libfetchers/tarball.cc
index 74c8097ff..dde0ad761 100644
--- a/src/libfetchers/tarball.cc
+++ b/src/libfetchers/tarball.cc
@@ -13,7 +13,7 @@ DownloadFileResult downloadFile(
     ref<Store> store,
     const std::string & url,
     const std::string & name,
-    bool immutable,
+    bool locked,
     const Headers & headers)
 {
     // FIXME: check store
@@ -88,7 +88,7 @@ DownloadFileResult downloadFile(
         inAttrs,
         infoAttrs,
         *storePath,
-        immutable);
+        locked);
 
     if (url != res.effectiveUri)
         getCache()->add(
@@ -100,7 +100,7 @@ DownloadFileResult downloadFile(
             },
             infoAttrs,
             *storePath,
-            immutable);
+            locked);
 
     return {
         .storePath = std::move(*storePath),
@@ -113,7 +113,7 @@ std::pair<Tree, time_t> downloadTarball(
     ref<Store> store,
     const std::string & url,
     const std::string & name,
-    bool immutable,
+    bool locked,
     const Headers & headers)
 {
     Attrs inAttrs({
@@ -130,7 +130,7 @@ std::pair<Tree, time_t> downloadTarball(
             getIntAttr(cached->infoAttrs, "lastModified")
         };
 
-    auto res = downloadFile(store, url, name, immutable, headers);
+    auto res = downloadFile(store, url, name, locked, headers);
 
     std::optional<StorePath> unpackedStorePath;
     time_t lastModified;
@@ -160,7 +160,7 @@ std::pair<Tree, time_t> downloadTarball(
         inAttrs,
         infoAttrs,
         *unpackedStorePath,
-        immutable);
+        locked);
 
     return {
         Tree { .actualPath = store->toRealPath(*unpackedStorePath), .storePath = std::move(*unpackedStorePath) },
@@ -202,7 +202,7 @@ struct TarballInputScheme : InputScheme
 
         Input input;
         input.attrs = attrs;
-        //input.immutable = (bool) maybeGetStrAttr(input.attrs, "hash");
+        //input.locked = (bool) maybeGetStrAttr(input.attrs, "hash");
         return input;
     }
 
diff --git a/src/nix/profile.cc b/src/nix/profile.cc
index 508cbd336..0e8dc4380 100644
--- a/src/nix/profile.cc
+++ b/src/nix/profile.cc
@@ -415,7 +415,7 @@ struct CmdProfileUpgrade : virtual SourceExprCommand, MixDefaultProfile, MixProf
         for (size_t i = 0; i < manifest.elements.size(); ++i) {
             auto & element(manifest.elements[i]);
             if (element.source
-                && !element.source->originalRef.input.isImmutable()
+                && !element.source->originalRef.input.isLocked()
                 && matches(*store, element, i, matchers))
             {
                 upgradedCount++;
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 60454471d..575eb0c4c 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -627,8 +627,8 @@ void NixRepl::loadFlake(const std::string & flakeRefS)
         throw Error("cannot use ':load-flake' without a path specified. (Use '.' for the current working directory.)");
 
     auto flakeRef = parseFlakeRef(flakeRefS, absPath("."), true);
-    if (evalSettings.pureEval && !flakeRef.input.isImmutable())
-        throw Error("cannot use ':load-flake' on mutable flake reference '%s' (use --impure to override)", flakeRefS);
+    if (evalSettings.pureEval && !flakeRef.input.isLocked())
+        throw Error("cannot use ':load-flake' on locked flake reference '%s' (use --impure to override)", flakeRefS);
 
     Value v;
 

From 9d4697453fc760597befa2e3eb887d2d6d375492 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 25 Feb 2022 09:21:04 +0100
Subject: [PATCH 561/567] ExprAttrs::show(): Show attrs in sorted order

Issue #6160.
---
 src/libexpr/nixexpr.cc | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc
index 2d2cd96cd..27ea0f2ad 100644
--- a/src/libexpr/nixexpr.cc
+++ b/src/libexpr/nixexpr.cc
@@ -103,11 +103,18 @@ void ExprAttrs::show(std::ostream & str) const
 {
     if (recursive) str << "rec ";
     str << "{ ";
-    for (auto & i : attrs)
-        if (i.second.inherited)
-            str << "inherit " << i.first << " " << "; ";
+    typedef const decltype(attrs)::value_type * Attr;
+    std::vector<Attr> sorted;
+    for (auto & i : attrs) sorted.push_back(&i);
+        std::sort(sorted.begin(), sorted.end(), [](Attr a, Attr b) {
+            return (const std::string &) a->first < (const std::string &) b->first;
+        });
+    for (auto & i : sorted) {
+        if (i->second.inherited)
+            str << "inherit " << i->first << " " << "; ";
         else
-            str << i.first << " = " << *i.second.e << "; ";
+            str << i->first << " = " << *i->second.e << "; ";
+    }
     for (auto & i : dynamicAttrs)
         str << "\"${" << *i.nameExpr << "}\" = " << *i.valueExpr << "; ";
     str << "}";

From b312d4d09699fc7681b20a956a95c6964cef73e3 Mon Sep 17 00:00:00 2001
From: Kevin Amado <kamadorueda@gmail.com>
Date: Fri, 25 Feb 2022 09:16:16 -0500
Subject: [PATCH 562/567] refactor: remove verbose-build from docs

- From what I see it is an implementation detail
  but is no longer configurable from the settings
---
 src/libstore/globals.hh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index 893c95bd6..4a78729e9 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -113,7 +113,7 @@ public:
     bool verboseBuild = true;
 
     Setting<size_t> logLines{this, 10, "log-lines",
-        "If `verbose-build` is false, the number of lines of the tail of "
+        "The number of lines of the tail of "
         "the log to show if a build fails."};
 
     MaxBuildJobsSetting maxBuildJobs{

From 14b38d0887f8a8d6b75039113eface57cfb19d06 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 25 Feb 2022 13:39:38 +0100
Subject: [PATCH 563/567] xml-writer: Remove std aliases

---
 src/libutil/xml-writer.cc | 10 ++++++----
 src/libutil/xml-writer.hh | 14 +++++---------
 src/nix-env/nix-env.cc    |  2 +-
 3 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/src/libutil/xml-writer.cc b/src/libutil/xml-writer.cc
index 68857e34d..7993bee9a 100644
--- a/src/libutil/xml-writer.cc
+++ b/src/libutil/xml-writer.cc
@@ -31,11 +31,12 @@ void XMLWriter::close()
 void XMLWriter::indent_(size_t depth)
 {
     if (!indent) return;
-    output << string(depth * 2, ' ');
+    output << std::string(depth * 2, ' ');
 }
 
 
-void XMLWriter::openElement(const string & name,
+void XMLWriter::openElement(
+    std::string_view name,
     const XMLAttrs & attrs)
 {
     assert(!closed);
@@ -44,7 +45,7 @@ void XMLWriter::openElement(const string & name,
     writeAttrs(attrs);
     output << ">";
     if (indent) output << std::endl;
-    pendingElems.push_back(name);
+    pendingElems.push_back(std::string(name));
 }
 
 
@@ -59,7 +60,8 @@ void XMLWriter::closeElement()
 }
 
 
-void XMLWriter::writeEmptyElement(const string & name,
+void XMLWriter::writeEmptyElement(
+    std::string_view name,
     const XMLAttrs & attrs)
 {
     assert(!closed);
diff --git a/src/libutil/xml-writer.hh b/src/libutil/xml-writer.hh
index b98b44526..4c91adee6 100644
--- a/src/libutil/xml-writer.hh
+++ b/src/libutil/xml-writer.hh
@@ -8,12 +8,8 @@
 
 namespace nix {
 
-using std::string;
-using std::map;
-using std::list;
 
-
-typedef map<string, string> XMLAttrs;
+typedef std::map<std::string, std::string> XMLAttrs;
 
 
 class XMLWriter
@@ -25,7 +21,7 @@ private:
     bool indent;
     bool closed;
 
-    list<string> pendingElems;
+    std::list<std::string> pendingElems;
 
 public:
 
@@ -34,11 +30,11 @@ public:
 
     void close();
 
-    void openElement(const string & name,
+    void openElement(std::string_view name,
         const XMLAttrs & attrs = XMLAttrs());
     void closeElement();
 
-    void writeEmptyElement(const string & name,
+    void writeEmptyElement(std::string_view name,
         const XMLAttrs & attrs = XMLAttrs());
 
 private:
@@ -53,7 +49,7 @@ class XMLOpenElement
 private:
     XMLWriter & writer;
 public:
-    XMLOpenElement(XMLWriter & writer, const string & name,
+    XMLOpenElement(XMLWriter & writer, std::string_view name,
         const XMLAttrs & attrs = XMLAttrs())
         : writer(writer)
     {
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index 52d07e3df..f83edb6a1 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -833,7 +833,7 @@ static bool cmpElemByName(const DrvInfo & a, const DrvInfo & b)
 }
 
 
-typedef list<Strings> Table;
+typedef std::list<Strings> Table;
 
 
 void printTable(Table & table)

From df552ff53e68dff8ca360adbdbea214ece1d08ee Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 25 Feb 2022 16:00:00 +0100
Subject: [PATCH 564/567] Remove std::string alias (for real this time)

Also use std::string_view in a few more places.
---
 perl/lib/Nix/Store.xs                         |  2 +-
 src/build-remote/build-remote.cc              | 10 +--
 src/libexpr/attr-path.cc                      |  6 +-
 src/libexpr/attr-path.hh                      |  7 +-
 src/libexpr/attr-set.hh                       |  2 +-
 src/libexpr/common-eval-args.cc               |  8 +-
 src/libexpr/common-eval-args.hh               |  2 +-
 src/libexpr/eval-cache.cc                     |  2 +-
 src/libexpr/eval.cc                           | 66 +++++++--------
 src/libexpr/eval.hh                           | 20 ++---
 src/libexpr/flake/flake.cc                    |  4 +-
 src/libexpr/get-drvs.cc                       | 40 ++++-----
 src/libexpr/get-drvs.hh                       | 46 +++++-----
 src/libexpr/nixexpr.cc                        | 14 ++--
 src/libexpr/nixexpr.hh                        | 19 +++--
 src/libexpr/parser.y                          | 30 +++----
 src/libexpr/primops.cc                        | 46 +++++-----
 src/libexpr/primops/context.cc                | 10 +--
 src/libexpr/primops/fetchMercurial.cc         |  2 +-
 src/libexpr/primops/fetchTree.cc              |  4 +-
 src/libexpr/primops/fromTOML.cc               |  2 +-
 src/libexpr/value-to-xml.cc                   |  2 +-
 src/libfetchers/mercurial.cc                  |  4 +-
 src/libmain/common-args.cc                    |  2 +-
 src/libmain/common-args.hh                    |  4 +-
 src/libmain/shared.cc                         | 16 ++--
 src/libmain/shared.hh                         | 14 ++--
 src/libstore/binary-cache-store.cc            | 17 +++-
 src/libstore/binary-cache-store.hh            | 18 ++--
 src/libstore/build/derivation-goal.cc         | 14 ++--
 src/libstore/build/derivation-goal.hh         |  4 +-
 .../build/drv-output-substitution-goal.cc     |  2 +-
 .../build/drv-output-substitution-goal.hh     |  2 +-
 src/libstore/build/goal.cc                    |  4 +-
 src/libstore/build/goal.hh                    |  8 +-
 src/libstore/build/local-derivation-goal.cc   | 64 ++++++++------
 src/libstore/build/local-derivation-goal.hh   |  2 +-
 src/libstore/build/substitution-goal.cc       |  2 +-
 src/libstore/build/substitution-goal.hh       |  4 +-
 src/libstore/build/worker.cc                  |  2 +-
 src/libstore/builtins/buildenv.cc             |  4 +-
 src/libstore/builtins/fetchurl.cc             |  2 +-
 src/libstore/builtins/unpack-channel.cc       |  2 +-
 src/libstore/daemon.cc                        |  8 +-
 src/libstore/derivations.cc                   | 32 +++----
 src/libstore/derivations.hh                   | 12 ++-
 src/libstore/derived-path.cc                  |  4 +-
 src/libstore/dummy-store.cc                   |  9 +-
 src/libstore/filetransfer.cc                  | 26 +++---
 src/libstore/filetransfer.hh                  |  8 +-
 src/libstore/gc.cc                            | 23 +++--
 src/libstore/globals.cc                       |  4 +-
 src/libstore/globals.hh                       |  2 +-
 src/libstore/legacy-ssh-store.cc              | 22 +++--
 src/libstore/local-fs-store.cc                |  2 +-
 src/libstore/local-fs-store.hh                |  2 +-
 src/libstore/local-store.cc                   | 29 ++++---
 src/libstore/local-store.hh                   | 13 ++-
 src/libstore/lock.hh                          |  4 +-
 src/libstore/machines.cc                      | 21 ++---
 src/libstore/nar-accessor.cc                  |  2 +-
 src/libstore/nar-info.cc                      |  2 +-
 src/libstore/optimise-store.cc                |  2 +-
 src/libstore/path-with-outputs.cc             |  4 +-
 src/libstore/path.hh                          |  2 +-
 src/libstore/pathlocks.cc                     |  4 +-
 src/libstore/pathlocks.hh                     |  4 +-
 src/libstore/profiles.cc                      | 16 ++--
 src/libstore/profiles.hh                      |  4 +-
 src/libstore/references.cc                    |  4 +-
 src/libstore/remote-store.cc                  | 11 ++-
 src/libstore/remote-store.hh                  |  7 +-
 src/libstore/s3-binary-cache-store.cc         | 11 ++-
 src/libstore/sqlite.cc                        |  2 +-
 src/libstore/ssh.cc                           |  2 +-
 src/libstore/store-api.cc                     | 32 ++++---
 src/libstore/store-api.hh                     | 26 ++++--
 src/libutil/archive.cc                        | 28 +++----
 src/libutil/archive.hh                        |  6 +-
 src/libutil/args.cc                           | 12 +--
 src/libutil/args.hh                           |  2 +-
 src/libutil/config.cc                         | 14 ++--
 src/libutil/error.cc                          | 12 +--
 src/libutil/error.hh                          | 26 +++---
 src/libutil/fmt.hh                            |  7 +-
 src/libutil/hash.cc                           | 19 +++--
 src/libutil/hash.hh                           |  6 +-
 src/libutil/logging.cc                        |  2 +-
 src/libutil/logging.hh                        |  2 +-
 src/libutil/serialise.cc                      |  4 +-
 src/libutil/serialise.hh                      |  4 +-
 src/libutil/tests/url.cc                      | 18 ++--
 src/libutil/types.hh                          |  1 +
 src/libutil/util.cc                           | 84 +++++++++----------
 src/libutil/util.hh                           | 44 +++++-----
 src/nix-build/nix-build.cc                    | 16 ++--
 src/nix-channel/nix-channel.cc                | 14 ++--
 .../nix-collect-garbage.cc                    |  2 +-
 src/nix-env/nix-env.cc                        | 82 +++++++++---------
 src/nix-env/user-env.cc                       |  2 +-
 src/nix-env/user-env.hh                       |  2 +-
 src/nix-instantiate/nix-instantiate.cc        |  2 +-
 src/nix-store/dotgraph.cc                     | 26 +++---
 src/nix-store/graphml.cc                      |  8 +-
 src/nix-store/nix-store.cc                    | 16 ++--
 src/nix/daemon.cc                             | 16 ++--
 src/nix/hash.cc                               |  2 +-
 src/nix/prefetch.cc                           | 14 ++--
 src/nix/repl.cc                               | 66 +++++++--------
 src/nix/why-depends.cc                        |  4 +-
 110 files changed, 773 insertions(+), 681 deletions(-)

diff --git a/perl/lib/Nix/Store.xs b/perl/lib/Nix/Store.xs
index edbf12f7c..54ad1680c 100644
--- a/perl/lib/Nix/Store.xs
+++ b/perl/lib/Nix/Store.xs
@@ -240,7 +240,7 @@ SV * convertHash(char * algo, char * s, int toBase32)
     PPCODE:
         try {
             auto h = Hash::parseAny(s, parseHashType(algo));
-            string s = h.to_string(toBase32 ? Base32 : Base16, false);
+            auto s = h.to_string(toBase32 ? Base32 : Base16, false);
             XPUSHs(sv_2mortal(newSVpv(s.c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());
diff --git a/src/build-remote/build-remote.cc b/src/build-remote/build-remote.cc
index 4d7b602d8..9d2eacb54 100644
--- a/src/build-remote/build-remote.cc
+++ b/src/build-remote/build-remote.cc
@@ -32,7 +32,7 @@ std::string escapeUri(std::string uri)
     return uri;
 }
 
-static string currentLoad;
+static std::string currentLoad;
 
 static AutoCloseFD openSlotLock(const Machine & m, uint64_t slot)
 {
@@ -97,7 +97,7 @@ static int main_build_remote(int argc, char * * argv)
         }
 
         std::optional<StorePath> drvPath;
-        string storeUri;
+        std::string storeUri;
 
         while (true) {
 
@@ -183,7 +183,7 @@ static int main_build_remote(int argc, char * * argv)
                     else
                     {
                         // build the hint template.
-                        string errorText =
+                        std::string errorText =
                             "Failed to find a machine for remote build!\n"
                             "derivation: %s\nrequired (system, features): (%s, %s)";
                         errorText += "\n%s available machines:";
@@ -193,7 +193,7 @@ static int main_build_remote(int argc, char * * argv)
                             errorText += "\n(%s, %s, %s, %s)";
 
                         // add the template values.
-                        string drvstr;
+                        std::string drvstr;
                         if (drvPath.has_value())
                             drvstr = drvPath->to_string();
                         else
@@ -208,7 +208,7 @@ static int main_build_remote(int argc, char * * argv)
 
                         for (auto & m : machines)
                             error
-                                % concatStringsSep<std::vector<string>>(", ", m.systemTypes)
+                                % concatStringsSep<std::vector<std::string>>(", ", m.systemTypes)
                                 % m.maxJobs
                                 % concatStringsSep<StringSet>(", ", m.supportedFeatures)
                                 % concatStringsSep<StringSet>(", ", m.mandatoryFeatures);
diff --git a/src/libexpr/attr-path.cc b/src/libexpr/attr-path.cc
index bf0c1dabc..eb0e706c7 100644
--- a/src/libexpr/attr-path.cc
+++ b/src/libexpr/attr-path.cc
@@ -9,7 +9,7 @@ namespace nix {
 static Strings parseAttrPath(std::string_view s)
 {
     Strings res;
-    string cur;
+    std::string cur;
     auto i = s.begin();
     while (i != s.end()) {
         if (*i == '.') {
@@ -41,7 +41,7 @@ std::vector<Symbol> parseAttrPath(EvalState & state, std::string_view s)
 }
 
 
-std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const string & attrPath,
+std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const std::string & attrPath,
     Bindings & autoArgs, Value & vIn)
 {
     Strings tokens = parseAttrPath(attrPath);
@@ -121,7 +121,7 @@ Pos findPackageFilename(EvalState & state, Value & v, std::string what)
     std::string filename(pos, 0, colon);
     unsigned int lineno;
     try {
-        lineno = std::stoi(std::string(pos, colon + 1, string::npos));
+        lineno = std::stoi(std::string(pos, colon + 1, std::string::npos));
     } catch (std::invalid_argument & e) {
         throw ParseError("cannot parse line number '%s'", pos);
     }
diff --git a/src/libexpr/attr-path.hh b/src/libexpr/attr-path.hh
index 2ee3ea089..ff1135a06 100644
--- a/src/libexpr/attr-path.hh
+++ b/src/libexpr/attr-path.hh
@@ -10,8 +10,11 @@ namespace nix {
 MakeError(AttrPathNotFound, Error);
 MakeError(NoPositionInfo, Error);
 
-std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const string & attrPath,
-    Bindings & autoArgs, Value & vIn);
+std::pair<Value *, Pos> findAlongAttrPath(
+    EvalState & state,
+    const std::string & attrPath,
+    Bindings & autoArgs,
+    Value & vIn);
 
 /* Heuristic to find the filename and lineno or a nix value. */
 Pos findPackageFilename(EvalState & state, Value & v, std::string what);
diff --git a/src/libexpr/attr-set.hh b/src/libexpr/attr-set.hh
index 3e4899efc..cad9743ea 100644
--- a/src/libexpr/attr-set.hh
+++ b/src/libexpr/attr-set.hh
@@ -105,7 +105,7 @@ public:
         for (size_t n = 0; n < size_; n++)
             res.emplace_back(&attrs[n]);
         std::sort(res.begin(), res.end(), [](const Attr * a, const Attr * b) {
-            return (const string &) a->name < (const string &) b->name;
+            return (const std::string &) a->name < (const std::string &) b->name;
         });
         return res;
     }
diff --git a/src/libexpr/common-eval-args.cc b/src/libexpr/common-eval-args.cc
index fffca4ac5..e50ff244c 100644
--- a/src/libexpr/common-eval-args.cc
+++ b/src/libexpr/common-eval-args.cc
@@ -77,7 +77,7 @@ Bindings * MixEvalArgs::getAutoArgs(EvalState & state)
     for (auto & i : autoArgs) {
         auto v = state.allocValue();
         if (i.second[0] == 'E')
-            state.mkThunk_(*v, state.parseExprFromString(string(i.second, 1), absPath(".")));
+            state.mkThunk_(*v, state.parseExprFromString(i.second.substr(1), absPath(".")));
         else
             v->mkString(((std::string_view) i.second).substr(1));
         res.insert(state.symbols.create(i.first), v);
@@ -85,17 +85,17 @@ Bindings * MixEvalArgs::getAutoArgs(EvalState & state)
     return res.finish();
 }
 
-Path lookupFileArg(EvalState & state, string s)
+Path lookupFileArg(EvalState & state, std::string_view s)
 {
     if (isUri(s)) {
         return state.store->toRealPath(
             fetchers::downloadTarball(
                 state.store, resolveUri(s), "source", false).first.storePath);
     } else if (s.size() > 2 && s.at(0) == '<' && s.at(s.size() - 1) == '>') {
-        Path p = s.substr(1, s.size() - 2);
+        Path p(s.substr(1, s.size() - 2));
         return state.findFile(p);
     } else
-        return absPath(s);
+        return absPath(std::string(s));
 }
 
 }
diff --git a/src/libexpr/common-eval-args.hh b/src/libexpr/common-eval-args.hh
index 0e113fff1..03fa226aa 100644
--- a/src/libexpr/common-eval-args.hh
+++ b/src/libexpr/common-eval-args.hh
@@ -22,6 +22,6 @@ private:
     std::map<std::string, std::string> autoArgs;
 };
 
-Path lookupFileArg(EvalState & state, string s);
+Path lookupFileArg(EvalState & state, std::string_view s);
 
 }
diff --git a/src/libexpr/eval-cache.cc b/src/libexpr/eval-cache.cc
index d6b9ea29b..00d0749f9 100644
--- a/src/libexpr/eval-cache.cc
+++ b/src/libexpr/eval-cache.cc
@@ -596,7 +596,7 @@ std::vector<Symbol> AttrCursor::getAttrs()
     for (auto & attr : *getValue().attrs)
         attrs.push_back(attr.name);
     std::sort(attrs.begin(), attrs.end(), [](const Symbol & a, const Symbol & b) {
-        return (const string &) a < (const string &) b;
+        return (const std::string &) a < (const std::string &) b;
     });
 
     if (root->db)
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 2d4eb57fc..60f0bf08c 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -174,7 +174,7 @@ std::ostream & operator << (std::ostream & str, const Value & v)
 }
 
 
-const Value *getPrimOp(const Value &v) {
+const Value * getPrimOp(const Value &v) {
     const Value * primOp = &v;
     while (primOp->isPrimOpApp()) {
         primOp = primOp->primOpApp.left;
@@ -183,7 +183,7 @@ const Value *getPrimOp(const Value &v) {
     return primOp;
 }
 
-string showType(ValueType type)
+std::string_view showType(ValueType type)
 {
     switch (type) {
         case nInt: return "an integer";
@@ -202,20 +202,20 @@ string showType(ValueType type)
 }
 
 
-string showType(const Value & v)
+std::string showType(const Value & v)
 {
     switch (v.internalType) {
         case tString: return v.string.context ? "a string with context" : "a string";
         case tPrimOp:
-            return fmt("the built-in function '%s'", string(v.primOp->name));
+            return fmt("the built-in function '%s'", std::string(v.primOp->name));
         case tPrimOpApp:
-            return fmt("the partially applied built-in function '%s'", string(getPrimOp(v)->primOp->name));
+            return fmt("the partially applied built-in function '%s'", std::string(getPrimOp(v)->primOp->name));
         case tExternal: return v.external->showType();
         case tThunk: return "a thunk";
         case tApp: return "a function application";
         case tBlackhole: return "a black hole";
     default:
-        return showType(v.type());
+        return std::string(showType(v.type()));
     }
 }
 
@@ -356,7 +356,7 @@ void initGC()
 
 /* Very hacky way to parse $NIX_PATH, which is colon-separated, but
    can contain URLs (e.g. "nixpkgs=https://bla...:foo=https://"). */
-static Strings parseNixPath(const string & s)
+static Strings parseNixPath(const std::string & s)
 {
     Strings res;
 
@@ -606,7 +606,7 @@ Path EvalState::toRealPath(const Path & path, const PathSet & context)
 }
 
 
-Value * EvalState::addConstant(const string & name, Value & v)
+Value * EvalState::addConstant(const std::string & name, Value & v)
 {
     Value * v2 = allocValue();
     *v2 = v;
@@ -615,19 +615,19 @@ Value * EvalState::addConstant(const string & name, Value & v)
 }
 
 
-void EvalState::addConstant(const string & name, Value * v)
+void EvalState::addConstant(const std::string & name, Value * v)
 {
     staticBaseEnv.vars.emplace_back(symbols.create(name), baseEnvDispl);
     baseEnv.values[baseEnvDispl++] = v;
-    string name2 = string(name, 0, 2) == "__" ? string(name, 2) : name;
+    auto name2 = name.substr(0, 2) == "__" ? name.substr(2) : name;
     baseEnv.values[0]->attrs->push_back(Attr(symbols.create(name2), v));
 }
 
 
-Value * EvalState::addPrimOp(const string & name,
+Value * EvalState::addPrimOp(const std::string & name,
     size_t arity, PrimOpFun primOp)
 {
-    auto name2 = string(name, 0, 2) == "__" ? string(name, 2) : name;
+    auto name2 = name.substr(0, 2) == "__" ? name.substr(2) : name;
     Symbol sym = symbols.create(name2);
 
     /* Hack to make constants lazy: turn them into a application of
@@ -675,7 +675,7 @@ Value * EvalState::addPrimOp(PrimOp && primOp)
 }
 
 
-Value & EvalState::getBuiltin(const string & name)
+Value & EvalState::getBuiltin(const std::string & name)
 {
     return *baseEnv.values[0]->attrs->find(symbols.create(name))->value;
 }
@@ -703,12 +703,12 @@ std::optional<EvalState::Doc> EvalState::getDoc(Value & v)
    evaluator.  So here are some helper functions for throwing
    exceptions. */
 
-LocalNoInlineNoReturn(void throwEvalError(const char * s, const string & s2))
+LocalNoInlineNoReturn(void throwEvalError(const char * s, const std::string & s2))
 {
     throw EvalError(s, s2);
 }
 
-LocalNoInlineNoReturn(void throwEvalError(const Pos & pos, const char * s, const string & s2))
+LocalNoInlineNoReturn(void throwEvalError(const Pos & pos, const char * s, const std::string & s2))
 {
     throw EvalError({
         .msg = hintfmt(s, s2),
@@ -716,12 +716,12 @@ LocalNoInlineNoReturn(void throwEvalError(const Pos & pos, const char * s, const
     });
 }
 
-LocalNoInlineNoReturn(void throwEvalError(const char * s, const string & s2, const string & s3))
+LocalNoInlineNoReturn(void throwEvalError(const char * s, const std::string & s2, const std::string & s3))
 {
     throw EvalError(s, s2, s3);
 }
 
-LocalNoInlineNoReturn(void throwEvalError(const Pos & pos, const char * s, const string & s2, const string & s3))
+LocalNoInlineNoReturn(void throwEvalError(const Pos & pos, const char * s, const std::string & s2, const std::string & s3))
 {
     throw EvalError({
         .msg = hintfmt(s, s2, s3),
@@ -759,7 +759,7 @@ LocalNoInlineNoReturn(void throwTypeError(const char * s, const Value & v))
     throw TypeError(s, showType(v));
 }
 
-LocalNoInlineNoReturn(void throwAssertionError(const Pos & pos, const char * s, const string & s1))
+LocalNoInlineNoReturn(void throwAssertionError(const Pos & pos, const char * s, const std::string & s1))
 {
     throw AssertionError({
         .msg = hintfmt(s, s1),
@@ -767,7 +767,7 @@ LocalNoInlineNoReturn(void throwAssertionError(const Pos & pos, const char * s,
     });
 }
 
-LocalNoInlineNoReturn(void throwUndefinedVarError(const Pos & pos, const char * s, const string & s1))
+LocalNoInlineNoReturn(void throwUndefinedVarError(const Pos & pos, const char * s, const std::string & s1))
 {
     throw UndefinedVarError({
         .msg = hintfmt(s, s1),
@@ -775,7 +775,7 @@ LocalNoInlineNoReturn(void throwUndefinedVarError(const Pos & pos, const char *
     });
 }
 
-LocalNoInlineNoReturn(void throwMissingArgumentError(const Pos & pos, const char * s, const string & s1))
+LocalNoInlineNoReturn(void throwMissingArgumentError(const Pos & pos, const char * s, const std::string & s1))
 {
     throw MissingArgumentError({
         .msg = hintfmt(s, s1),
@@ -783,12 +783,12 @@ LocalNoInlineNoReturn(void throwMissingArgumentError(const Pos & pos, const char
     });
 }
 
-LocalNoInline(void addErrorTrace(Error & e, const char * s, const string & s2))
+LocalNoInline(void addErrorTrace(Error & e, const char * s, const std::string & s2))
 {
     e.addTrace(std::nullopt, s, s2);
 }
 
-LocalNoInline(void addErrorTrace(Error & e, const Pos & pos, const char * s, const string & s2))
+LocalNoInline(void addErrorTrace(Error & e, const Pos & pos, const char * s, const std::string & s2))
 {
     e.addTrace(pos, s, s2);
 }
@@ -1221,7 +1221,7 @@ void ExprVar::eval(EvalState & state, Env & env, Value & v)
 }
 
 
-static string showAttrPath(EvalState & state, Env & env, const AttrPath & attrPath)
+static std::string showAttrPath(EvalState & state, Env & env, const AttrPath & attrPath)
 {
     std::ostringstream out;
     bool first = true;
@@ -1395,7 +1395,7 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
                 if (loggerSettings.showTrace.get()) {
                     addErrorTrace(e, lambda.pos, "while evaluating %s",
                         (lambda.name.set()
-                            ? "'" + (string) lambda.name + "'"
+                            ? "'" + (const std::string &) lambda.name + "'"
                             : "anonymous lambda"));
                     addErrorTrace(e, pos, "from call site%s", "");
                 }
@@ -1883,7 +1883,7 @@ std::string_view EvalState::forceString(Value & v, const Pos & pos)
 
 /* Decode a context string ‘!<name>!<path>’ into a pair <path,
    name>. */
-std::pair<string, string> decodeContext(std::string_view s)
+std::pair<std::string, std::string> decodeContext(std::string_view s)
 {
     if (s.at(0) == '!') {
         size_t index = s.find("!", 1);
@@ -1946,7 +1946,7 @@ bool EvalState::isDerivation(Value & v)
 }
 
 
-std::optional<string> EvalState::tryAttrsToString(const Pos & pos, Value & v,
+std::optional<std::string> EvalState::tryAttrsToString(const Pos & pos, Value & v,
     PathSet & context, bool coerceMore, bool copyToStore)
 {
     auto i = v.attrs->find(sToString);
@@ -2001,7 +2001,7 @@ BackedStringView EvalState::coerceToString(const Pos & pos, Value & v, PathSet &
         if (v.type() == nNull) return "";
 
         if (v.isList()) {
-            string result;
+            std::string result;
             for (auto [n, v2] : enumerate(v.listItems())) {
                 result += *coerceToString(pos, *v2, context, coerceMore, copyToStore);
                 if (n < v.listSize() - 1
@@ -2017,7 +2017,7 @@ BackedStringView EvalState::coerceToString(const Pos & pos, Value & v, PathSet &
 }
 
 
-string EvalState::copyPathToStore(PathSet & context, const Path & path)
+std::string EvalState::copyPathToStore(PathSet & context, const Path & path)
 {
     if (nix::isDerivation(path))
         throwEvalError("file names are not allowed to end in '%1%'", drvExtension);
@@ -2043,7 +2043,7 @@ string EvalState::copyPathToStore(PathSet & context, const Path & path)
 
 Path EvalState::coerceToPath(const Pos & pos, Value & v, PathSet & context)
 {
-    string path = coerceToString(pos, v, context, false, false).toOwned();
+    auto path = coerceToString(pos, v, context, false, false).toOwned();
     if (path == "" || path[0] != '/')
         throwEvalError(pos, "string '%1%' doesn't represent an absolute path", path);
     return path;
@@ -2213,11 +2213,11 @@ void EvalState::printStats()
                 for (auto & i : functionCalls) {
                     auto obj = list.object();
                     if (i.first->name.set())
-                        obj.attr("name", (const string &) i.first->name);
+                        obj.attr("name", (const std::string &) i.first->name);
                     else
                         obj.attr("name", nullptr);
                     if (i.first->pos) {
-                        obj.attr("file", (const string &) i.first->pos.file);
+                        obj.attr("file", (const std::string &) i.first->pos.file);
                         obj.attr("line", i.first->pos.line);
                         obj.attr("column", i.first->pos.column);
                     }
@@ -2229,7 +2229,7 @@ void EvalState::printStats()
                 for (auto & i : attrSelects) {
                     auto obj = list.object();
                     if (i.first) {
-                        obj.attr("file", (const string &) i.first.file);
+                        obj.attr("file", (const std::string &) i.first.file);
                         obj.attr("line", i.first.line);
                         obj.attr("column", i.first.column);
                     }
@@ -2246,7 +2246,7 @@ void EvalState::printStats()
 }
 
 
-string ExternalValueBase::coerceToString(const Pos & pos, PathSet & context, bool copyMore, bool copyToStore) const
+std::string ExternalValueBase::coerceToString(const Pos & pos, PathSet & context, bool copyMore, bool copyToStore) const
 {
     throw TypeError({
         .msg = hintfmt("cannot coerce %1% to a string", showType()),
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index ce5a16e11..1f0e97b2e 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -150,7 +150,7 @@ public:
         const Pos & pos
     );
 
-    void addToSearchPath(const string & s);
+    void addToSearchPath(const std::string & s);
 
     SearchPath getSearchPath() { return searchPath; }
 
@@ -251,7 +251,7 @@ public:
        set with attribute `type = "derivation"'). */
     bool isDerivation(Value & v);
 
-    std::optional<string> tryAttrsToString(const Pos & pos, Value & v,
+    std::optional<std::string> tryAttrsToString(const Pos & pos, Value & v,
         PathSet & context, bool coerceMore = false, bool copyToStore = true);
 
     /* String coercion.  Converts strings, paths and derivations to a
@@ -262,7 +262,7 @@ public:
         bool coerceMore = false, bool copyToStore = true,
         bool canonicalizePath = true);
 
-    string copyPathToStore(PathSet & context, const Path & path);
+    std::string copyPathToStore(PathSet & context, const Path & path);
 
     /* Path coercion.  Converts strings, paths and derivations to a
        path.  The result is guaranteed to be a canonicalised, absolute
@@ -284,18 +284,18 @@ private:
 
     void createBaseEnv();
 
-    Value * addConstant(const string & name, Value & v);
+    Value * addConstant(const std::string & name, Value & v);
 
-    void addConstant(const string & name, Value * v);
+    void addConstant(const std::string & name, Value * v);
 
-    Value * addPrimOp(const string & name,
+    Value * addPrimOp(const std::string & name,
         size_t arity, PrimOpFun primOp);
 
     Value * addPrimOp(PrimOp && primOp);
 
 public:
 
-    Value & getBuiltin(const string & name);
+    Value & getBuiltin(const std::string & name);
 
     struct Doc
     {
@@ -414,12 +414,12 @@ private:
 
 
 /* Return a string representing the type of the value `v'. */
-string showType(ValueType type);
-string showType(const Value & v);
+std::string_view showType(ValueType type);
+std::string showType(const Value & v);
 
 /* Decode a context string ‘!<name>!<path>’ into a pair <path,
    name>. */
-std::pair<string, string> decodeContext(std::string_view s);
+std::pair<std::string, std::string> decodeContext(std::string_view s);
 
 /* If `path' refers to a directory, then append "/default.nix". */
 Path resolveExprPath(Path path);
diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 6e3fa41f7..ad0881641 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -254,7 +254,7 @@ static Flake getFlake(
         for (auto & setting : *nixConfig->value->attrs) {
             forceTrivialValue(state, *setting.value, *setting.pos);
             if (setting.value->type() == nString)
-                flake.config.settings.insert({setting.name, string(state.forceStringNoCtx(*setting.value, *setting.pos))});
+                flake.config.settings.insert({setting.name, std::string(state.forceStringNoCtx(*setting.value, *setting.pos))});
             else if (setting.value->type() == nPath) {
                 PathSet emptyContext = {};
                 flake.config.settings.emplace(
@@ -707,7 +707,7 @@ static void prim_getFlake(EvalState & state, const Pos & pos, Value * * args, Va
 {
     state.requireExperimentalFeatureOnEvaluation(Xp::Flakes, "builtins.getFlake", pos);
 
-    string flakeRefS(state.forceStringNoCtx(*args[0], pos));
+    std::string flakeRefS(state.forceStringNoCtx(*args[0], pos));
     auto flakeRef = parseFlakeRef(flakeRefS, {}, true);
     if (evalSettings.pureEval && !flakeRef.input.isLocked())
         throw Error("cannot call 'getFlake' on unlocked flake reference '%s', at %s (use --impure to override)", flakeRefS, pos);
diff --git a/src/libexpr/get-drvs.cc b/src/libexpr/get-drvs.cc
index 167fb5fa9..8393e4225 100644
--- a/src/libexpr/get-drvs.cc
+++ b/src/libexpr/get-drvs.cc
@@ -11,8 +11,8 @@
 namespace nix {
 
 
-DrvInfo::DrvInfo(EvalState & state, const string & attrPath, Bindings * attrs)
-    : state(&state), attrs(attrs), attrPath(attrPath)
+DrvInfo::DrvInfo(EvalState & state, std::string attrPath, Bindings * attrs)
+    : state(&state), attrs(attrs), attrPath(std::move(attrPath))
 {
 }
 
@@ -47,7 +47,7 @@ DrvInfo::DrvInfo(EvalState & state, ref<Store> store, const std::string & drvPat
 }
 
 
-string DrvInfo::queryName() const
+std::string DrvInfo::queryName() const
 {
     if (name == "" && attrs) {
         auto i = attrs->find(state->sName);
@@ -58,7 +58,7 @@ string DrvInfo::queryName() const
 }
 
 
-string DrvInfo::querySystem() const
+std::string DrvInfo::querySystem() const
 {
     if (system == "" && attrs) {
         auto i = attrs->find(state->sSystem);
@@ -68,7 +68,7 @@ string DrvInfo::querySystem() const
 }
 
 
-string DrvInfo::queryDrvPath() const
+std::string DrvInfo::queryDrvPath() const
 {
     if (drvPath == "" && attrs) {
         Bindings::iterator i = attrs->find(state->sDrvPath);
@@ -79,7 +79,7 @@ string DrvInfo::queryDrvPath() const
 }
 
 
-string DrvInfo::queryOutPath() const
+std::string DrvInfo::queryOutPath() const
 {
     if (!outPath && attrs) {
         Bindings::iterator i = attrs->find(state->sOutPath);
@@ -104,7 +104,7 @@ DrvInfo::Outputs DrvInfo::queryOutputs(bool onlyOutputsToInstall)
             /* For each output... */
             for (auto elem : i->value->listItems()) {
                 /* Evaluate the corresponding set. */
-                string name(state->forceStringNoCtx(*elem, *i->pos));
+                std::string name(state->forceStringNoCtx(*elem, *i->pos));
                 Bindings::iterator out = attrs->find(state->symbols.create(name));
                 if (out == attrs->end()) continue; // FIXME: throw error?
                 state->forceAttrs(*out->value, *i->pos);
@@ -138,7 +138,7 @@ DrvInfo::Outputs DrvInfo::queryOutputs(bool onlyOutputsToInstall)
 }
 
 
-string DrvInfo::queryOutputName() const
+std::string DrvInfo::queryOutputName() const
 {
     if (outputName == "" && attrs) {
         Bindings::iterator i = attrs->find(state->sOutputName);
@@ -190,7 +190,7 @@ bool DrvInfo::checkMeta(Value & v)
 }
 
 
-Value * DrvInfo::queryMeta(const string & name)
+Value * DrvInfo::queryMeta(const std::string & name)
 {
     if (!getMeta()) return 0;
     Bindings::iterator a = meta->find(state->symbols.create(name));
@@ -199,7 +199,7 @@ Value * DrvInfo::queryMeta(const string & name)
 }
 
 
-string DrvInfo::queryMetaString(const string & name)
+std::string DrvInfo::queryMetaString(const std::string & name)
 {
     Value * v = queryMeta(name);
     if (!v || v->type() != nString) return "";
@@ -207,7 +207,7 @@ string DrvInfo::queryMetaString(const string & name)
 }
 
 
-NixInt DrvInfo::queryMetaInt(const string & name, NixInt def)
+NixInt DrvInfo::queryMetaInt(const std::string & name, NixInt def)
 {
     Value * v = queryMeta(name);
     if (!v) return def;
@@ -221,7 +221,7 @@ NixInt DrvInfo::queryMetaInt(const string & name, NixInt def)
     return def;
 }
 
-NixFloat DrvInfo::queryMetaFloat(const string & name, NixFloat def)
+NixFloat DrvInfo::queryMetaFloat(const std::string & name, NixFloat def)
 {
     Value * v = queryMeta(name);
     if (!v) return def;
@@ -236,7 +236,7 @@ NixFloat DrvInfo::queryMetaFloat(const string & name, NixFloat def)
 }
 
 
-bool DrvInfo::queryMetaBool(const string & name, bool def)
+bool DrvInfo::queryMetaBool(const std::string & name, bool def)
 {
     Value * v = queryMeta(name);
     if (!v) return def;
@@ -251,7 +251,7 @@ bool DrvInfo::queryMetaBool(const string & name, bool def)
 }
 
 
-void DrvInfo::setMeta(const string & name, Value * v)
+void DrvInfo::setMeta(const std::string & name, Value * v)
 {
     getMeta();
     auto attrs = state->buildBindings(1 + (meta ? meta->size() : 0));
@@ -274,7 +274,7 @@ typedef std::set<Bindings *> Done;
    The result boolean indicates whether it makes sense
    for the caller to recursively search for derivations in `v'. */
 static bool getDerivation(EvalState & state, Value & v,
-    const string & attrPath, DrvInfos & drvs, Done & done,
+    const std::string & attrPath, DrvInfos & drvs, Done & done,
     bool ignoreAssertionFailures)
 {
     try {
@@ -311,7 +311,7 @@ std::optional<DrvInfo> getDerivation(EvalState & state, Value & v,
 }
 
 
-static string addToPath(const string & s1, const string & s2)
+static std::string addToPath(const std::string & s1, const std::string & s2)
 {
     return s1.empty() ? s2 : s1 + "." + s2;
 }
@@ -321,7 +321,7 @@ static std::regex attrRegex("[A-Za-z_][A-Za-z0-9-_+]*");
 
 
 static void getDerivations(EvalState & state, Value & vIn,
-    const string & pathPrefix, Bindings & autoArgs,
+    const std::string & pathPrefix, Bindings & autoArgs,
     DrvInfos & drvs, Done & done,
     bool ignoreAssertionFailures)
 {
@@ -346,7 +346,7 @@ static void getDerivations(EvalState & state, Value & vIn,
             debug("evaluating attribute '%1%'", i->name);
             if (!std::regex_match(std::string(i->name), attrRegex))
                 continue;
-            string pathPrefix2 = addToPath(pathPrefix, i->name);
+            std::string pathPrefix2 = addToPath(pathPrefix, i->name);
             if (combineChannels)
                 getDerivations(state, *i->value, pathPrefix2, autoArgs, drvs, done, ignoreAssertionFailures);
             else if (getDerivation(state, *i->value, pathPrefix2, drvs, done, ignoreAssertionFailures)) {
@@ -364,7 +364,7 @@ static void getDerivations(EvalState & state, Value & vIn,
 
     else if (v.type() == nList) {
         for (auto [n, elem] : enumerate(v.listItems())) {
-            string pathPrefix2 = addToPath(pathPrefix, fmt("%d", n));
+            std::string pathPrefix2 = addToPath(pathPrefix, fmt("%d", n));
             if (getDerivation(state, *elem, pathPrefix2, drvs, done, ignoreAssertionFailures))
                 getDerivations(state, *elem, pathPrefix2, autoArgs, drvs, done, ignoreAssertionFailures);
         }
@@ -374,7 +374,7 @@ static void getDerivations(EvalState & state, Value & vIn,
 }
 
 
-void getDerivations(EvalState & state, Value & v, const string & pathPrefix,
+void getDerivations(EvalState & state, Value & v, const std::string & pathPrefix,
     Bindings & autoArgs, DrvInfos & drvs, bool ignoreAssertionFailures)
 {
     Done done;
diff --git a/src/libexpr/get-drvs.hh b/src/libexpr/get-drvs.hh
index 128354682..d13847785 100644
--- a/src/libexpr/get-drvs.hh
+++ b/src/libexpr/get-drvs.hh
@@ -12,16 +12,16 @@ namespace nix {
 struct DrvInfo
 {
 public:
-    typedef std::map<string, Path> Outputs;
+    typedef std::map<std::string, Path> Outputs;
 
 private:
     EvalState * state;
 
-    mutable string name;
-    mutable string system;
-    mutable string drvPath;
-    mutable std::optional<string> outPath;
-    mutable string outputName;
+    mutable std::string name;
+    mutable std::string system;
+    mutable std::string drvPath;
+    mutable std::optional<std::string> outPath;
+    mutable std::string outputName;
     Outputs outputs;
 
     bool failed = false; // set if we get an AssertionError
@@ -33,36 +33,36 @@ private:
     bool checkMeta(Value & v);
 
 public:
-    string attrPath; /* path towards the derivation */
+    std::string attrPath; /* path towards the derivation */
 
     DrvInfo(EvalState & state) : state(&state) { };
-    DrvInfo(EvalState & state, const string & attrPath, Bindings * attrs);
+    DrvInfo(EvalState & state, std::string attrPath, Bindings * attrs);
     DrvInfo(EvalState & state, ref<Store> store, const std::string & drvPathWithOutputs);
 
-    string queryName() const;
-    string querySystem() const;
-    string queryDrvPath() const;
-    string queryOutPath() const;
-    string queryOutputName() const;
+    std::string queryName() const;
+    std::string querySystem() const;
+    std::string queryDrvPath() const;
+    std::string queryOutPath() const;
+    std::string queryOutputName() const;
     /** Return the list of outputs. The "outputs to install" are determined by `meta.outputsToInstall`. */
     Outputs queryOutputs(bool onlyOutputsToInstall = false);
 
     StringSet queryMetaNames();
-    Value * queryMeta(const string & name);
-    string queryMetaString(const string & name);
-    NixInt queryMetaInt(const string & name, NixInt def);
-    NixFloat queryMetaFloat(const string & name, NixFloat def);
-    bool queryMetaBool(const string & name, bool def);
-    void setMeta(const string & name, Value * v);
+    Value * queryMeta(const std::string & name);
+    std::string queryMetaString(const std::string & name);
+    NixInt queryMetaInt(const std::string & name, NixInt def);
+    NixFloat queryMetaFloat(const std::string & name, NixFloat def);
+    bool queryMetaBool(const std::string & name, bool def);
+    void setMeta(const std::string & name, Value * v);
 
     /*
     MetaInfo queryMetaInfo(EvalState & state) const;
     MetaValue queryMetaInfo(EvalState & state, const string & name) const;
     */
 
-    void setName(const string & s) { name = s; }
-    void setDrvPath(const string & s) { drvPath = s; }
-    void setOutPath(const string & s) { outPath = s; }
+    void setName(const std::string & s) { name = s; }
+    void setDrvPath(const std::string & s) { drvPath = s; }
+    void setOutPath(const std::string & s) { outPath = s; }
 
     void setFailed() { failed = true; };
     bool hasFailed() { return failed; };
@@ -81,7 +81,7 @@ typedef std::list<DrvInfo> DrvInfos;
 std::optional<DrvInfo> getDerivation(EvalState & state,
     Value & v, bool ignoreAssertionFailures);
 
-void getDerivations(EvalState & state, Value & v, const string & pathPrefix,
+void getDerivations(EvalState & state, Value & v, const std::string & pathPrefix,
     Bindings & autoArgs, DrvInfos & drvs,
     bool ignoreAssertionFailures);
 
diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc
index 27ea0f2ad..a2def65a6 100644
--- a/src/libexpr/nixexpr.cc
+++ b/src/libexpr/nixexpr.cc
@@ -16,10 +16,10 @@ std::ostream & operator << (std::ostream & str, const Expr & e)
     return str;
 }
 
-static void showString(std::ostream & str, const string & s)
+static void showString(std::ostream & str, std::string_view s)
 {
     str << '"';
-    for (auto c : (string) s)
+    for (auto c : s)
         if (c == '"' || c == '\\' || c == '$') str << "\\" << c;
         else if (c == '\n') str << "\\n";
         else if (c == '\r') str << "\\r";
@@ -28,7 +28,7 @@ static void showString(std::ostream & str, const string & s)
     str << '"';
 }
 
-static void showId(std::ostream & str, const string & s)
+static void showId(std::ostream & str, std::string_view s)
 {
     if (s.empty())
         str << "\"\"";
@@ -218,7 +218,7 @@ std::ostream & operator << (std::ostream & str, const Pos & pos)
         auto f = format(ANSI_BOLD "%1%" ANSI_NORMAL ":%2%:%3%");
         switch (pos.origin) {
             case foFile:
-                f % (string) pos.file;
+                f % (const std::string &) pos.file;
                 break;
             case foStdin:
             case foString:
@@ -234,7 +234,7 @@ std::ostream & operator << (std::ostream & str, const Pos & pos)
 }
 
 
-string showAttrPath(const AttrPath & attrPath)
+std::string showAttrPath(const AttrPath & attrPath)
 {
     std::ostringstream out;
     bool first = true;
@@ -468,9 +468,9 @@ void ExprLambda::setName(Symbol & name)
 }
 
 
-string ExprLambda::showNamePos() const
+std::string ExprLambda::showNamePos() const
 {
-    return (format("%1% at %2%") % (name.set() ? "'" + (string) name + "'" : "anonymous function") % pos).str();
+    return fmt("%1% at %2%", name.set() ? "'" + (std::string) name + "'" : "anonymous function", pos);
 }
 
 
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index e7f717eba..12b54b8eb 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -26,18 +26,21 @@ struct Pos
     FileOrigin origin;
     Symbol file;
     unsigned int line, column;
-    Pos() : origin(foString), line(0), column(0) { };
+
+    Pos() : origin(foString), line(0), column(0) { }
     Pos(FileOrigin origin, const Symbol & file, unsigned int line, unsigned int column)
-        : origin(origin), file(file), line(line), column(column) { };
+        : origin(origin), file(file), line(line), column(column) { }
+
     operator bool() const
     {
         return line != 0;
     }
+
     bool operator < (const Pos & p2) const
     {
         if (!line) return p2.line;
         if (!p2.line) return false;
-        int d = ((string) file).compare((string) p2.file);
+        int d = ((const std::string &) file).compare((const std::string &) p2.file);
         if (d < 0) return true;
         if (d > 0) return false;
         if (line < p2.line) return true;
@@ -68,7 +71,7 @@ struct AttrName
 
 typedef std::vector<AttrName> AttrPath;
 
-string showAttrPath(const AttrPath & attrPath);
+std::string showAttrPath(const AttrPath & attrPath);
 
 
 /* Abstract syntax of Nix expressions. */
@@ -110,7 +113,7 @@ struct ExprFloat : Expr
 
 struct ExprString : Expr
 {
-    string s;
+    std::string s;
     Value v;
     ExprString(std::string s) : s(std::move(s)) { v.mkString(this->s.data()); };
     COMMON_METHODS
@@ -119,9 +122,9 @@ struct ExprString : Expr
 
 struct ExprPath : Expr
 {
-    string s;
+    std::string s;
     Value v;
-    ExprPath(const string & s) : s(s) { v.mkPath(this->s.c_str()); };
+    ExprPath(std::string s) : s(std::move(s)) { v.mkPath(this->s.c_str()); };
     COMMON_METHODS
     Value * maybeThunk(EvalState & state, Env & env);
 };
@@ -249,7 +252,7 @@ struct ExprLambda : Expr
     {
     };
     void setName(Symbol & name);
-    string showNamePos() const;
+    std::string showNamePos() const;
     inline bool hasFormals() const { return formals != nullptr; }
     COMMON_METHODS
 };
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index e1d177c1f..919b9cfae 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -244,7 +244,7 @@ static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols,
         es2->emplace_back(i->first, e);
     };
     const auto trimString = [&] (const StringToken & t) {
-        string s2;
+        std::string s2;
         for (size_t j = 0; j < t.l; ++j) {
             if (atStartOfLine) {
                 if (t.p[j] == ' ') {
@@ -268,9 +268,9 @@ static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols,
         /* Remove the last line if it is empty and consists only of
            spaces. */
         if (n == 1) {
-            string::size_type p = s2.find_last_of('\n');
-            if (p != string::npos && s2.find_first_not_of(' ', p + 1) == string::npos)
-                s2 = string(s2, 0, p + 1);
+            std::string::size_type p = s2.find_last_of('\n');
+            if (p != std::string::npos && s2.find_first_not_of(' ', p + 1) == std::string::npos)
+                s2 = std::string(s2, 0, p + 1);
         }
 
         es2->emplace_back(i->first, new ExprString(s2));
@@ -466,7 +466,7 @@ expr_simple
       $$ = new ExprConcatStrings(CUR_POS, false, $2);
   }
   | SPATH {
-      string path($1.p + 1, $1.l - 2);
+      std::string path($1.p + 1, $1.l - 2);
       $$ = new ExprCall(CUR_POS,
           new ExprVar(data->symbols.create("__findFile")),
           {new ExprVar(data->symbols.create("__nixPath")),
@@ -479,7 +479,7 @@ expr_simple
               .msg = hintfmt("URL literals are disabled"),
               .errPos = CUR_POS
           });
-      $$ = new ExprString(string($1));
+      $$ = new ExprString(std::string($1));
   }
   | '(' expr ')' { $$ = $2; }
   /* Let expressions `let {..., body = ...}' are just desugared
@@ -494,19 +494,19 @@ expr_simple
   ;
 
 string_parts
-  : STR { $$ = new ExprString(string($1)); }
+  : STR { $$ = new ExprString(std::string($1)); }
   | string_parts_interpolated { $$ = new ExprConcatStrings(CUR_POS, true, $1); }
   | { $$ = new ExprString(""); }
   ;
 
 string_parts_interpolated
   : string_parts_interpolated STR
-  { $$ = $1; $1->emplace_back(makeCurPos(@2, data), new ExprString(string($2))); }
+  { $$ = $1; $1->emplace_back(makeCurPos(@2, data), new ExprString(std::string($2))); }
   | string_parts_interpolated DOLLAR_CURLY expr '}' { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $3); }
   | DOLLAR_CURLY expr '}' { $$ = new std::vector<std::pair<Pos, Expr *> >; $$->emplace_back(makeCurPos(@1, data), $2); }
   | STR DOLLAR_CURLY expr '}' {
       $$ = new std::vector<std::pair<Pos, Expr *> >;
-      $$->emplace_back(makeCurPos(@1, data), new ExprString(string($1)));
+      $$->emplace_back(makeCurPos(@1, data), new ExprString(std::string($1)));
       $$->emplace_back(makeCurPos(@2, data), $3);
     }
   ;
@@ -520,7 +520,7 @@ path_start
     $$ = new ExprPath(path);
   }
   | HPATH {
-    Path path(getHome() + string($1.p + 1, $1.l - 1));
+    Path path(getHome() + std::string($1.p + 1, $1.l - 1));
     $$ = new ExprPath(path);
   }
   ;
@@ -738,16 +738,16 @@ Expr * EvalState::parseStdin()
 }
 
 
-void EvalState::addToSearchPath(const string & s)
+void EvalState::addToSearchPath(const std::string & s)
 {
     size_t pos = s.find('=');
-    string prefix;
+    std::string prefix;
     Path path;
-    if (pos == string::npos) {
+    if (pos == std::string::npos) {
         path = s;
     } else {
-        prefix = string(s, 0, pos);
-        path = string(s, pos + 1);
+        prefix = std::string(s, 0, pos);
+        path = std::string(s, pos + 1);
     }
 
     searchPath.emplace_back(prefix, path);
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index daf679a5a..aa22c3b61 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -141,7 +141,7 @@ static void mkOutputString(
     BindingsBuilder & attrs,
     const StorePath & drvPath,
     const BasicDerivation & drv,
-    const std::pair<string, DerivationOutput> & o)
+    const std::pair<std::string, DerivationOutput> & o)
 {
     auto optOutputPath = o.second.path(*state.store, drv.name, o.first);
     attrs.alloc(o.first).mkString(
@@ -314,7 +314,7 @@ void prim_importNative(EvalState & state, const Pos & pos, Value * * args, Value
 {
     auto path = realisePath(state, pos, *args[0]);
 
-    string sym(state.forceStringNoCtx(*args[1], pos));
+    std::string sym(state.forceStringNoCtx(*args[1], pos));
 
     void *handle = dlopen(path.c_str(), RTLD_LAZY | RTLD_LOCAL);
     if (!handle)
@@ -386,7 +386,7 @@ void prim_exec(EvalState & state, const Pos & pos, Value * * args, Value & v)
 static void prim_typeOf(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     state.forceValue(*args[0], pos);
-    string t;
+    std::string t;
     switch (args[0]->type()) {
         case nInt: t = "int"; break;
         case nBool: t = "bool"; break;
@@ -707,7 +707,7 @@ static RegisterPrimOp primop_abort({
     .fun = [](EvalState & state, const Pos & pos, Value * * args, Value & v)
     {
         PathSet context;
-        string s = state.coerceToString(pos, *args[0], context).toOwned();
+        auto s = state.coerceToString(pos, *args[0], context).toOwned();
         throw Abort("evaluation aborted with the following error message: '%1%'", s);
     }
 });
@@ -725,7 +725,7 @@ static RegisterPrimOp primop_throw({
     .fun = [](EvalState & state, const Pos & pos, Value * * args, Value & v)
     {
       PathSet context;
-      string s = state.coerceToString(pos, *args[0], context).toOwned();
+      auto s = state.coerceToString(pos, *args[0], context).toOwned();
       throw ThrownError(s);
     }
 });
@@ -826,7 +826,7 @@ static RegisterPrimOp primop_tryEval({
 /* Return an environment variable.  Use with care. */
 static void prim_getEnv(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
-    string name(state.forceStringNoCtx(*args[0], pos));
+    std::string name(state.forceStringNoCtx(*args[0], pos));
     v.mkString(evalSettings.restrictEval || evalSettings.pureEval ? "" : getEnv(name).value_or(""));
 }
 
@@ -935,7 +935,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
         pos
     );
 
-    string drvName;
+    std::string drvName;
     Pos & posDrvName(*attr->pos);
     try {
         drvName = state.forceStringNoCtx(*attr->value, pos);
@@ -973,7 +973,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
 
     for (auto & i : args[0]->attrs->lexicographicOrder()) {
         if (i->name == state.sIgnoreNulls) continue;
-        const string & key = i->name;
+        const std::string & key = i->name;
         vomit("processing attribute '%1%'", key);
 
         auto handleHashMode = [&](const std::string_view s) {
@@ -1031,7 +1031,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
             else if (i->name == state.sArgs) {
                 state.forceList(*i->value, pos);
                 for (auto elem : i->value->listItems()) {
-                    string s = state.coerceToString(posDrvName, *elem, context, true).toOwned();
+                    auto s = state.coerceToString(posDrvName, *elem, context, true).toOwned();
                     drv.args.push_back(s);
                 }
             }
@@ -1118,7 +1118,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
 
         /* Handle derivation outputs of the form ‘!<name>!<path>’. */
         else if (path.at(0) == '!') {
-            std::pair<string, string> ctx = decodeContext(path);
+            auto ctx = decodeContext(path);
             drv.inputDrvs[state.store->parseStorePath(ctx.first)].insert(ctx.second);
         }
 
@@ -1440,8 +1440,8 @@ static RegisterPrimOp primop_dirOf({
 static void prim_readFile(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     auto path = realisePath(state, pos, *args[0]);
-    string s = readFile(path);
-    if (s.find((char) 0) != string::npos)
+    auto s = readFile(path);
+    if (s.find((char) 0) != std::string::npos)
         throw Error("the contents of the file '%1%' cannot be represented as a Nix string", path);
     StorePathSet refs;
     if (state.store->isInStore(path)) {
@@ -1474,7 +1474,7 @@ static void prim_findFile(EvalState & state, const Pos & pos, Value * * args, Va
     for (auto v2 : args[0]->listItems()) {
         state.forceAttrs(*v2, pos);
 
-        string prefix;
+        std::string prefix;
         Bindings::iterator i = v2->attrs->find(state.sPrefix);
         if (i != v2->attrs->end())
             prefix = state.forceStringNoCtx(*i->value, pos);
@@ -1488,7 +1488,7 @@ static void prim_findFile(EvalState & state, const Pos & pos, Value * * args, Va
         );
 
         PathSet context;
-        string path = state.coerceToString(pos, *i->value, context, false, false).toOwned();
+        auto path = state.coerceToString(pos, *i->value, context, false, false).toOwned();
 
         try {
             auto rewrites = state.realiseContext(context);
@@ -1754,8 +1754,8 @@ static RegisterPrimOp primop_fromJSON({
 static void prim_toFile(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     PathSet context;
-    string name(state.forceStringNoCtx(*args[0], pos));
-    string contents(state.forceString(*args[1], context, pos));
+    std::string name(state.forceStringNoCtx(*args[0], pos));
+    std::string contents(state.forceString(*args[1], context, pos));
 
     StorePathSet refs;
 
@@ -1863,7 +1863,7 @@ static RegisterPrimOp primop_toFile({
 static void addPath(
     EvalState & state,
     const Pos & pos,
-    const string & name,
+    const std::string & name,
     Path path,
     Value * filterFun,
     FileIngestionMethod method,
@@ -2016,14 +2016,14 @@ static void prim_path(EvalState & state, const Pos & pos, Value * * args, Value
 {
     state.forceAttrs(*args[0], pos);
     Path path;
-    string name;
+    std::string name;
     Value * filterFun = nullptr;
     auto method = FileIngestionMethod::Recursive;
     std::optional<Hash> expectedHash;
     PathSet context;
 
     for (auto & attr : *args[0]->attrs) {
-        const string & n(attr.name);
+        auto & n(attr.name);
         if (n == "path")
             path = state.coerceToPath(*attr.pos, *attr.value, context);
         else if (attr.name == state.sName)
@@ -3616,7 +3616,7 @@ static void prim_concatStringsSep(EvalState & state, const Pos & pos, Value * *
     auto sep = state.forceString(*args[0], context, pos);
     state.forceList(*args[1], pos);
 
-    string res;
+    std::string res;
     res.reserve((args[1]->listSize() + 32) * sep.size());
     bool first = true;
 
@@ -3649,12 +3649,12 @@ static void prim_replaceStrings(EvalState & state, const Pos & pos, Value * * ar
             .errPos = pos
         });
 
-    std::vector<string> from;
+    std::vector<std::string> from;
     from.reserve(args[0]->listSize());
     for (auto elem : args[0]->listItems())
         from.emplace_back(state.forceString(*elem, pos));
 
-    std::vector<std::pair<string, PathSet>> to;
+    std::vector<std::pair<std::string, PathSet>> to;
     to.reserve(args[1]->listSize());
     for (auto elem : args[1]->listItems()) {
         PathSet ctx;
@@ -3665,7 +3665,7 @@ static void prim_replaceStrings(EvalState & state, const Pos & pos, Value * * ar
     PathSet context;
     auto s = state.forceString(*args[2], context, pos);
 
-    string res;
+    std::string res;
     // Loops one past last character to handle the case where 'from' contains an empty string.
     for (size_t p = 0; p <= s.size(); ) {
         bool found = false;
diff --git a/src/libexpr/primops/context.cc b/src/libexpr/primops/context.cc
index 654251c23..3701bd442 100644
--- a/src/libexpr/primops/context.cc
+++ b/src/libexpr/primops/context.cc
@@ -37,7 +37,7 @@ static void prim_unsafeDiscardOutputDependency(EvalState & state, const Pos & po
 
     PathSet context2;
     for (auto & p : context)
-        context2.insert(p.at(0) == '=' ? string(p, 1) : p);
+        context2.insert(p.at(0) == '=' ? std::string(p, 1) : p);
 
     v.mkString(*s, context2);
 }
@@ -76,13 +76,13 @@ static void prim_getContext(EvalState & state, const Pos & pos, Value * * args,
     auto contextInfos = std::map<Path, ContextInfo>();
     for (const auto & p : context) {
         Path drv;
-        string output;
+        std::string output;
         const Path * path = &p;
         if (p.at(0) == '=') {
-            drv = string(p, 1);
+            drv = std::string(p, 1);
             path = &drv;
         } else if (p.at(0) == '!') {
-            std::pair<string, string> ctx = decodeContext(p);
+            std::pair<std::string, std::string> ctx = decodeContext(p);
             drv = ctx.first;
             output = ctx.second;
             path = &drv;
@@ -166,7 +166,7 @@ static void prim_appendContext(EvalState & state, const Pos & pos, Value * * arg
                         .errPos = *i.pos
                     });
                 }
-                context.insert("=" + string(i.name));
+                context.insert("=" + std::string(i.name));
             }
         }
 
diff --git a/src/libexpr/primops/fetchMercurial.cc b/src/libexpr/primops/fetchMercurial.cc
index c4e1a7bf0..b7f715859 100644
--- a/src/libexpr/primops/fetchMercurial.cc
+++ b/src/libexpr/primops/fetchMercurial.cc
@@ -62,7 +62,7 @@ static void prim_fetchMercurial(EvalState & state, const Pos & pos, Value * * ar
     fetchers::Attrs attrs;
     attrs.insert_or_assign("type", "hg");
     attrs.insert_or_assign("url", url.find("://") != std::string::npos ? url : "file://" + url);
-    attrs.insert_or_assign("name", string(name));
+    attrs.insert_or_assign("name", std::string(name));
     if (ref) attrs.insert_or_assign("ref", *ref);
     if (rev) attrs.insert_or_assign("rev", rev->gitRev());
     auto input = fetchers::Input::fromAttrs(std::move(attrs));
diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index 7496104b6..f3e3e70d8 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -186,7 +186,7 @@ static void prim_fetchTree(EvalState & state, const Pos & pos, Value * * args, V
 static RegisterPrimOp primop_fetchTree("fetchTree", 1, prim_fetchTree);
 
 static void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
-    const string & who, bool unpack, std::string name)
+    const std::string & who, bool unpack, std::string name)
 {
     std::optional<std::string> url;
     std::optional<Hash> expectedHash;
@@ -198,7 +198,7 @@ static void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
         state.forceAttrs(*args[0], pos);
 
         for (auto & attr : *args[0]->attrs) {
-            string n(attr.name);
+            std::string n(attr.name);
             if (n == "url")
                 url = state.forceStringNoCtx(*attr.value, *attr.pos);
             else if (n == "sha256")
diff --git a/src/libexpr/primops/fromTOML.cc b/src/libexpr/primops/fromTOML.cc
index c0e858b61..dd4280030 100644
--- a/src/libexpr/primops/fromTOML.cc
+++ b/src/libexpr/primops/fromTOML.cc
@@ -9,7 +9,7 @@ static void prim_fromTOML(EvalState & state, const Pos & pos, Value * * args, Va
 {
     auto toml = state.forceStringNoCtx(*args[0], pos);
 
-    std::istringstream tomlStream(string{toml});
+    std::istringstream tomlStream(std::string{toml});
 
     std::function<void(Value &, toml::value)> visit;
 
diff --git a/src/libexpr/value-to-xml.cc b/src/libexpr/value-to-xml.cc
index a9fb60b0e..afeaf5694 100644
--- a/src/libexpr/value-to-xml.cc
+++ b/src/libexpr/value-to-xml.cc
@@ -9,7 +9,7 @@
 namespace nix {
 
 
-static XMLAttrs singletonAttrs(const string & name, const string & value)
+static XMLAttrs singletonAttrs(const std::string & name, const std::string & value)
 {
     XMLAttrs attrs;
     attrs[name] = value;
diff --git a/src/libfetchers/mercurial.cc b/src/libfetchers/mercurial.cc
index 798369c7a..12cdecbc1 100644
--- a/src/libfetchers/mercurial.cc
+++ b/src/libfetchers/mercurial.cc
@@ -26,7 +26,7 @@ static RunOptions hgOptions(const Strings & args)
 }
 
 // runProgram wrapper that uses hgOptions instead of stock RunOptions.
-static string runHg(const Strings & args, const std::optional<std::string> & input = {})
+static std::string runHg(const Strings & args, const std::optional<std::string> & input = {})
 {
     RunOptions opts = hgOptions(args);
     opts.input = input;
@@ -254,7 +254,7 @@ struct MercurialInputScheme : InputScheme
                     runHg({ "pull", "-R", cacheDir, "--", actualUrl });
                 }
                 catch (ExecError & e) {
-                    string transJournal = cacheDir + "/.hg/store/journal";
+                    auto transJournal = cacheDir + "/.hg/store/journal";
                     /* hg throws "abandoned transaction" error only if this file exists */
                     if (pathExists(transJournal)) {
                         runHg({ "recover", "-R", cacheDir });
diff --git a/src/libmain/common-args.cc b/src/libmain/common-args.cc
index c43e9ebd2..12f5403ea 100644
--- a/src/libmain/common-args.cc
+++ b/src/libmain/common-args.cc
@@ -4,7 +4,7 @@
 
 namespace nix {
 
-MixCommonArgs::MixCommonArgs(const string & programName)
+MixCommonArgs::MixCommonArgs(const std::string & programName)
     : programName(programName)
 {
     addFlag({
diff --git a/src/libmain/common-args.hh b/src/libmain/common-args.hh
index 31bdf527a..25453b8c6 100644
--- a/src/libmain/common-args.hh
+++ b/src/libmain/common-args.hh
@@ -11,8 +11,8 @@ class MixCommonArgs : public virtual Args
 {
     void initialFlagsProcessed() override;
 public:
-    string programName;
-    MixCommonArgs(const string & programName);
+    std::string programName;
+    MixCommonArgs(const std::string & programName);
 protected:
     virtual void pluginsInited() {}
 };
diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index f605184bb..47fc7ab2e 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -94,7 +94,7 @@ void printMissing(ref<Store> store, const StorePathSet & willBuild,
 }
 
 
-string getArg(const string & opt,
+std::string getArg(const std::string & opt,
     Strings::iterator & i, const Strings::iterator & end)
 {
     ++i;
@@ -227,6 +227,8 @@ LegacyArgs::LegacyArgs(const std::string & programName,
     std::function<bool(Strings::iterator & arg, const Strings::iterator & end)> parseArg)
     : MixCommonArgs(programName), parseArg(parseArg)
 {
+    printError("FOO %s", programName);
+    
     addFlag({
         .longName = "no-build-output",
         .shortName = 'Q',
@@ -322,14 +324,14 @@ void parseCmdLine(int argc, char * * argv,
 }
 
 
-void parseCmdLine(const string & programName, const Strings & args,
+void parseCmdLine(const std::string & programName, const Strings & args,
     std::function<bool(Strings::iterator & arg, const Strings::iterator & end)> parseArg)
 {
     LegacyArgs(programName, parseArg).parseCmdline(args);
 }
 
 
-void printVersion(const string & programName)
+void printVersion(const std::string & programName)
 {
     std::cout << format("%1% (Nix) %2%") % programName % nixVersion << std::endl;
     if (verbosity > lvlInfo) {
@@ -352,7 +354,7 @@ void printVersion(const string & programName)
 }
 
 
-void showManPage(const string & name)
+void showManPage(const std::string & name)
 {
     restoreProcessContext();
     setenv("MANPATH", settings.nixManDir.c_str(), 1);
@@ -361,13 +363,13 @@ void showManPage(const string & name)
 }
 
 
-int handleExceptions(const string & programName, std::function<void()> fun)
+int handleExceptions(const std::string & programName, std::function<void()> fun)
 {
     ReceiveInterrupts receiveInterrupts; // FIXME: need better place for this
 
     ErrorInfo::programName = baseNameOf(programName);
 
-    string error = ANSI_RED "error:" ANSI_NORMAL " ";
+    std::string error = ANSI_RED "error:" ANSI_NORMAL " ";
     try {
         try {
             fun();
@@ -407,7 +409,7 @@ RunPager::RunPager()
     if (!isatty(STDOUT_FILENO)) return;
     char * pager = getenv("NIX_PAGER");
     if (!pager) pager = getenv("PAGER");
-    if (pager && ((string) pager == "" || (string) pager == "cat")) return;
+    if (pager && ((std::string) pager == "" || (std::string) pager == "cat")) return;
 
     Pipe toPager;
     toPager.create();
diff --git a/src/libmain/shared.hh b/src/libmain/shared.hh
index ed012959b..0cc56d47d 100644
--- a/src/libmain/shared.hh
+++ b/src/libmain/shared.hh
@@ -22,7 +22,7 @@ public:
     virtual ~Exit();
 };
 
-int handleExceptions(const string & programName, std::function<void()> fun);
+int handleExceptions(const std::string & programName, std::function<void()> fun);
 
 /* Don't forget to call initPlugins() after settings are initialized! */
 void initNix();
@@ -30,10 +30,10 @@ void initNix();
 void parseCmdLine(int argc, char * * argv,
     std::function<bool(Strings::iterator & arg, const Strings::iterator & end)> parseArg);
 
-void parseCmdLine(const string & programName, const Strings & args,
+void parseCmdLine(const std::string & programName, const Strings & args,
     std::function<bool(Strings::iterator & arg, const Strings::iterator & end)> parseArg);
 
-void printVersion(const string & programName);
+void printVersion(const std::string & programName);
 
 /* Ugh.  No better place to put this. */
 void printGCWarning();
@@ -50,10 +50,10 @@ void printMissing(ref<Store> store, const StorePathSet & willBuild,
     const StorePathSet & willSubstitute, const StorePathSet & unknown,
     uint64_t downloadSize, uint64_t narSize, Verbosity lvl = lvlInfo);
 
-string getArg(const string & opt,
+std::string getArg(const std::string & opt,
     Strings::iterator & i, const Strings::iterator & end);
 
-template<class N> N getIntArg(const string & opt,
+template<class N> N getIntArg(const std::string & opt,
     Strings::iterator & i, const Strings::iterator & end, bool allowUnit)
 {
     ++i;
@@ -76,7 +76,7 @@ struct LegacyArgs : public MixCommonArgs
 
 
 /* Show the manual page for the specified program. */
-void showManPage(const string & name);
+void showManPage(const std::string & name);
 
 /* The constructor of this class starts a pager if stdout is a
    terminal and $PAGER is set. Stdout is redirected to the pager. */
@@ -96,7 +96,7 @@ extern volatile ::sig_atomic_t blockInt;
 
 /* GC helpers. */
 
-string showBytes(uint64_t bytes);
+std::string showBytes(uint64_t bytes);
 
 struct GCResults;
 
diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index b3fd991a1..9226c4e19 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -385,8 +385,14 @@ void BinaryCacheStore::queryPathInfoUncached(const StorePath & storePath,
         }});
 }
 
-StorePath BinaryCacheStore::addToStore(const string & name, const Path & srcPath,
-    FileIngestionMethod method, HashType hashAlgo, PathFilter & filter, RepairFlag repair, const StorePathSet & references)
+StorePath BinaryCacheStore::addToStore(
+    std::string_view name,
+    const Path & srcPath,
+    FileIngestionMethod method,
+    HashType hashAlgo,
+    PathFilter & filter,
+    RepairFlag repair,
+    const StorePathSet & references)
 {
     /* FIXME: Make BinaryCacheStore::addToStoreCommon support
        non-recursive+sha256 so we can just use the default
@@ -418,8 +424,11 @@ StorePath BinaryCacheStore::addToStore(const string & name, const Path & srcPath
     })->path;
 }
 
-StorePath BinaryCacheStore::addTextToStore(const string & name, const string & s,
-    const StorePathSet & references, RepairFlag repair)
+StorePath BinaryCacheStore::addTextToStore(
+    std::string_view name,
+    std::string_view s,
+    const StorePathSet & references,
+    RepairFlag repair)
 {
     auto textHash = hashString(htSHA256, s);
     auto path = makeTextPath(name, textHash, references);
diff --git a/src/libstore/binary-cache-store.hh b/src/libstore/binary-cache-store.hh
index 5b5d064f3..9603a8caa 100644
--- a/src/libstore/binary-cache-store.hh
+++ b/src/libstore/binary-cache-store.hh
@@ -101,12 +101,20 @@ public:
     StorePath addToStoreFromDump(Source & dump, std::string_view name,
         FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, const StorePathSet & references) override;
 
-    StorePath addToStore(const string & name, const Path & srcPath,
-        FileIngestionMethod method, HashType hashAlgo,
-        PathFilter & filter, RepairFlag repair, const StorePathSet & references) override;
+    StorePath addToStore(
+        std::string_view name,
+        const Path & srcPath,
+        FileIngestionMethod method,
+        HashType hashAlgo,
+        PathFilter & filter,
+        RepairFlag repair,
+        const StorePathSet & references) override;
 
-    StorePath addTextToStore(const string & name, const string & s,
-        const StorePathSet & references, RepairFlag repair) override;
+    StorePath addTextToStore(
+        std::string_view name,
+        std::string_view s,
+        const StorePathSet & references,
+        RepairFlag repair) override;
 
     void registerDrvOutput(const Realisation & info) override;
 
diff --git a/src/libstore/build/derivation-goal.cc b/src/libstore/build/derivation-goal.cc
index 27f8c6257..95da1841d 100644
--- a/src/libstore/build/derivation-goal.cc
+++ b/src/libstore/build/derivation-goal.cc
@@ -116,7 +116,7 @@ DerivationGoal::~DerivationGoal()
 }
 
 
-string DerivationGoal::key()
+std::string DerivationGoal::key()
 {
     /* Ensure that derivations get built in order of their name,
        i.e. a derivation named "aardvark" always comes before
@@ -1013,7 +1013,7 @@ HookReply DerivationGoal::tryBuildHook()
 
         /* Read the first line of input, which should be a word indicating
            whether the hook wishes to perform the build. */
-        string reply;
+        std::string reply;
         while (true) {
             auto s = [&]() {
                 try {
@@ -1025,8 +1025,8 @@ HookReply DerivationGoal::tryBuildHook()
             }();
             if (handleJSONLogMessage(s, worker.act, worker.hook->activities, true))
                 ;
-            else if (string(s, 0, 2) == "# ") {
-                reply = string(s, 2);
+            else if (s.substr(0, 2) == "# ") {
+                reply = s.substr(2);
                 break;
             }
             else {
@@ -1140,10 +1140,10 @@ Path DerivationGoal::openLogFile()
         logDir = localStore->logDir;
     else
         logDir = settings.nixLogDir;
-    Path dir = fmt("%s/%s/%s/", logDir, LocalFSStore::drvsLogDir, string(baseName, 0, 2));
+    Path dir = fmt("%s/%s/%s/", logDir, LocalFSStore::drvsLogDir, baseName.substr(0, 2));
     createDirs(dir);
 
-    Path logFileName = fmt("%s/%s%s", dir, string(baseName, 2),
+    Path logFileName = fmt("%s/%s%s", dir, baseName.substr(2),
         settings.compressLog ? ".bz2" : "");
 
     fdLogFile = open(logFileName.c_str(), O_CREAT | O_WRONLY | O_TRUNC | O_CLOEXEC, 0666);
@@ -1176,7 +1176,7 @@ bool DerivationGoal::isReadDesc(int fd)
 }
 
 
-void DerivationGoal::handleChildOutput(int fd, const string & data)
+void DerivationGoal::handleChildOutput(int fd, std::string_view data)
 {
     if (isReadDesc(fd))
     {
diff --git a/src/libstore/build/derivation-goal.hh b/src/libstore/build/derivation-goal.hh
index e112542c7..d947482ef 100644
--- a/src/libstore/build/derivation-goal.hh
+++ b/src/libstore/build/derivation-goal.hh
@@ -145,7 +145,7 @@ struct DerivationGoal : public Goal
 
     void timedOut(Error && ex) override;
 
-    string key() override;
+    std::string key() override;
 
     void work() override;
 
@@ -200,7 +200,7 @@ struct DerivationGoal : public Goal
     virtual bool isReadDesc(int fd);
 
     /* Callback used by the worker to write to the log. */
-    void handleChildOutput(int fd, const string & data) override;
+    void handleChildOutput(int fd, std::string_view data) override;
     void handleEOF(int fd) override;
     void flushLine();
 
diff --git a/src/libstore/build/drv-output-substitution-goal.cc b/src/libstore/build/drv-output-substitution-goal.cc
index b9602e696..e6e810cdd 100644
--- a/src/libstore/build/drv-output-substitution-goal.cc
+++ b/src/libstore/build/drv-output-substitution-goal.cc
@@ -137,7 +137,7 @@ void DrvOutputSubstitutionGoal::finished()
     amDone(ecSuccess);
 }
 
-string DrvOutputSubstitutionGoal::key()
+std::string DrvOutputSubstitutionGoal::key()
 {
     /* "a$" ensures substitution goals happen before derivation
        goals. */
diff --git a/src/libstore/build/drv-output-substitution-goal.hh b/src/libstore/build/drv-output-substitution-goal.hh
index 67ae2624a..948dbda8f 100644
--- a/src/libstore/build/drv-output-substitution-goal.hh
+++ b/src/libstore/build/drv-output-substitution-goal.hh
@@ -51,7 +51,7 @@ public:
 
     void timedOut(Error && ex) override { abort(); };
 
-    string key() override;
+    std::string key() override;
 
     void work() override;
     void handleEOF(int fd) override;
diff --git a/src/libstore/build/goal.cc b/src/libstore/build/goal.cc
index 7c985128b..d2420b107 100644
--- a/src/libstore/build/goal.cc
+++ b/src/libstore/build/goal.cc
@@ -5,8 +5,8 @@ namespace nix {
 
 
 bool CompareGoalPtrs::operator() (const GoalPtr & a, const GoalPtr & b) const {
-    string s1 = a->key();
-    string s2 = b->key();
+    std::string s1 = a->key();
+    std::string s2 = b->key();
     return s1 < s2;
 }
 
diff --git a/src/libstore/build/goal.hh b/src/libstore/build/goal.hh
index 0db0c1938..68e08bdf9 100644
--- a/src/libstore/build/goal.hh
+++ b/src/libstore/build/goal.hh
@@ -50,7 +50,7 @@ struct Goal : public std::enable_shared_from_this<Goal>
     unsigned int nrIncompleteClosure;
 
     /* Name of this goal for debugging purposes. */
-    string name;
+    std::string name;
 
     /* Whether the goal is finished. */
     ExitCode exitCode;
@@ -75,7 +75,7 @@ struct Goal : public std::enable_shared_from_this<Goal>
 
     virtual void waiteeDone(GoalPtr waitee, ExitCode result);
 
-    virtual void handleChildOutput(int fd, const string & data)
+    virtual void handleChildOutput(int fd, std::string_view data)
     {
         abort();
     }
@@ -87,7 +87,7 @@ struct Goal : public std::enable_shared_from_this<Goal>
 
     void trace(const FormatOrString & fs);
 
-    string getName()
+    std::string getName()
     {
         return name;
     }
@@ -97,7 +97,7 @@ struct Goal : public std::enable_shared_from_this<Goal>
        by the worker (important!), etc. */
     virtual void timedOut(Error && ex) = 0;
 
-    virtual string key() = 0;
+    virtual std::string key() = 0;
 
     void amDone(ExitCode result, std::optional<Error> ex = {});
 
diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 8861d2c7b..220f80602 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -481,12 +481,12 @@ void LocalDerivationGoal::startBuilder()
            temporary build directory.  The text files have the format used
            by `nix-store --register-validity'.  However, the deriver
            fields are left empty. */
-        string s = get(drv->env, "exportReferencesGraph").value_or("");
+        auto s = get(drv->env, "exportReferencesGraph").value_or("");
         Strings ss = tokenizeString<Strings>(s);
         if (ss.size() % 2 != 0)
             throw BuildError("odd number of tokens in 'exportReferencesGraph': '%1%'", s);
         for (Strings::iterator i = ss.begin(); i != ss.end(); ) {
-            string fileName = *i++;
+            auto fileName = *i++;
             static std::regex regex("[A-Za-z_][A-Za-z0-9_.-]*");
             if (!std::regex_match(fileName, regex))
                 throw Error("invalid file name '%s' in 'exportReferencesGraph'", fileName);
@@ -517,10 +517,10 @@ void LocalDerivationGoal::startBuilder()
                 i.pop_back();
             }
             size_t p = i.find('=');
-            if (p == string::npos)
+            if (p == std::string::npos)
                 dirsInChroot[i] = {i, optional};
             else
-                dirsInChroot[string(i, 0, p)] = {string(i, p + 1), optional};
+                dirsInChroot[i.substr(0, p)] = {i.substr(p + 1), optional};
         }
         dirsInChroot[tmpDirInSandbox] = tmpDir;
 
@@ -671,9 +671,10 @@ void LocalDerivationGoal::startBuilder()
         auto state = stBegin;
         auto lines = runProgram(settings.preBuildHook, false, args);
         auto lastPos = std::string::size_type{0};
-        for (auto nlPos = lines.find('\n'); nlPos != string::npos;
-                nlPos = lines.find('\n', lastPos)) {
-            auto line = std::string{lines, lastPos, nlPos - lastPos};
+        for (auto nlPos = lines.find('\n'); nlPos != std::string::npos;
+                nlPos = lines.find('\n', lastPos))
+        {
+            auto line = lines.substr(lastPos, nlPos - lastPos);
             lastPos = nlPos + 1;
             if (state == stBegin) {
                 if (line == "extra-sandbox-paths" || line == "extra-chroot-dirs") {
@@ -686,10 +687,10 @@ void LocalDerivationGoal::startBuilder()
                     state = stBegin;
                 } else {
                     auto p = line.find('=');
-                    if (p == string::npos)
+                    if (p == std::string::npos)
                         dirsInChroot[line] = line;
                     else
-                        dirsInChroot[string(line, 0, p)] = string(line, p + 1);
+                        dirsInChroot[line.substr(0, p)] = line.substr(p + 1);
                 }
             }
         }
@@ -941,7 +942,7 @@ void LocalDerivationGoal::startBuilder()
     /* Check if setting up the build environment failed. */
     std::vector<std::string> msgs;
     while (true) {
-        string msg = [&]() {
+        std::string msg = [&]() {
             try {
                 return readLine(builderOut.readSide.get());
             } catch (Error & e) {
@@ -953,8 +954,8 @@ void LocalDerivationGoal::startBuilder()
                 throw;
             }
         }();
-        if (string(msg, 0, 1) == "\2") break;
-        if (string(msg, 0, 1) == "\1") {
+        if (msg.substr(0, 1) == "\2") break;
+        if (msg.substr(0, 1) == "\1") {
             FdSource source(builderOut.readSide.get());
             auto ex = readError(source);
             ex.addTrace({}, "while setting up the build environment");
@@ -990,7 +991,7 @@ void LocalDerivationGoal::initTmpDir() {
                 env[i.first] = i.second;
             } else {
                 auto hash = hashString(htSHA256, i.first);
-                string fn = ".attr-" + hash.to_string(Base32, false);
+                std::string fn = ".attr-" + hash.to_string(Base32, false);
                 Path p = tmpDir + "/" + fn;
                 writeFile(p, rewriteStrings(i.second, inputRewrites));
                 chownToBuilder(p);
@@ -1081,7 +1082,7 @@ void LocalDerivationGoal::writeStructuredAttrs()
         for (auto & [i, v] : json["outputs"].get<nlohmann::json::object_t>()) {
             /* The placeholder must have a rewrite, so we use it to cover both the
                cases where we know or don't know the output path ahead of time. */
-            rewritten[i] = rewriteStrings(v, inputRewrites);
+            rewritten[i] = rewriteStrings((std::string) v, inputRewrites);
         }
 
         json["outputs"] = rewritten;
@@ -1187,10 +1188,14 @@ struct RestrictedStore : public virtual RestrictedStoreConfig, public virtual Lo
     std::optional<StorePath> queryPathFromHashPart(const std::string & hashPart) override
     { throw Error("queryPathFromHashPart"); }
 
-    StorePath addToStore(const string & name, const Path & srcPath,
-        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256,
-        PathFilter & filter = defaultPathFilter, RepairFlag repair = NoRepair,
-        const StorePathSet & references = StorePathSet()) override
+    StorePath addToStore(
+        std::string_view name,
+        const Path & srcPath,
+        FileIngestionMethod method,
+        HashType hashAlgo,
+        PathFilter & filter,
+        RepairFlag repair,
+        const StorePathSet & references) override
     { throw Error("addToStore"); }
 
     void addToStore(const ValidPathInfo & info, Source & narSource,
@@ -1200,17 +1205,24 @@ struct RestrictedStore : public virtual RestrictedStoreConfig, public virtual Lo
         goal.addDependency(info.path);
     }
 
-    StorePath addTextToStore(const string & name, const string & s,
-        const StorePathSet & references, RepairFlag repair = NoRepair) override
+    StorePath addTextToStore(
+        std::string_view name,
+        std::string_view s,
+        const StorePathSet & references,
+        RepairFlag repair = NoRepair) override
     {
         auto path = next->addTextToStore(name, s, references, repair);
         goal.addDependency(path);
         return path;
     }
 
-    StorePath addToStoreFromDump(Source & dump, std::string_view name,
-        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair,
-        const StorePathSet & references = StorePathSet()) override
+    StorePath addToStoreFromDump(
+        Source & dump,
+        std::string_view name,
+        FileIngestionMethod method,
+        HashType hashAlgo,
+        RepairFlag repair,
+        const StorePathSet & references) override
     {
         auto path = next->addToStoreFromDump(dump, name, method, hashAlgo, repair, references);
         goal.addDependency(path);
@@ -1992,7 +2004,7 @@ void LocalDerivationGoal::runChild()
             args.push_back(rewriteStrings(i, inputRewrites));
 
         /* Indicate that we managed to set up the build environment. */
-        writeFull(STDERR_FILENO, string("\2\n"));
+        writeFull(STDERR_FILENO, std::string("\2\n"));
 
         /* Execute the program.  This should not return. */
         if (drv->isBuiltin()) {
@@ -2010,7 +2022,7 @@ void LocalDerivationGoal::runChild()
                 else if (drv->builder == "builtin:unpack-channel")
                     builtinUnpackChannel(drv2);
                 else
-                    throw Error("unsupported builtin builder '%1%'", string(drv->builder, 8));
+                    throw Error("unsupported builtin builder '%1%'", drv->builder.substr(8));
                 _exit(0);
             } catch (std::exception & e) {
                 writeFull(STDERR_FILENO, e.what() + std::string("\n"));
@@ -2694,7 +2706,7 @@ void LocalDerivationGoal::checkOutputs(const std::map<Path, ValidPathInfo> & out
                     }
 
                 if (!badPaths.empty()) {
-                    string badPathsStr;
+                    std::string badPathsStr;
                     for (auto & i : badPaths) {
                         badPathsStr += "\n  ";
                         badPathsStr += worker.store.printStorePath(i);
diff --git a/src/libstore/build/local-derivation-goal.hh b/src/libstore/build/local-derivation-goal.hh
index bfdf91d89..2d1222d2f 100644
--- a/src/libstore/build/local-derivation-goal.hh
+++ b/src/libstore/build/local-derivation-goal.hh
@@ -58,7 +58,7 @@ struct LocalDerivationGoal : public DerivationGoal
     typedef map<Path, ChrootPath> DirsInChroot; // maps target path to source path
     DirsInChroot dirsInChroot;
 
-    typedef map<string, string> Environment;
+    typedef map<std::string, std::string> Environment;
     Environment env;
 
 #if __APPLE__
diff --git a/src/libstore/build/substitution-goal.cc b/src/libstore/build/substitution-goal.cc
index 5ecf1da7e..c1bb1941d 100644
--- a/src/libstore/build/substitution-goal.cc
+++ b/src/libstore/build/substitution-goal.cc
@@ -272,7 +272,7 @@ void PathSubstitutionGoal::finished()
 }
 
 
-void PathSubstitutionGoal::handleChildOutput(int fd, const string & data)
+void PathSubstitutionGoal::handleChildOutput(int fd, std::string_view data)
 {
 }
 
diff --git a/src/libstore/build/substitution-goal.hh b/src/libstore/build/substitution-goal.hh
index 70c806d23..d8399d2a8 100644
--- a/src/libstore/build/substitution-goal.hh
+++ b/src/libstore/build/substitution-goal.hh
@@ -59,7 +59,7 @@ public:
 
     void timedOut(Error && ex) override { abort(); };
 
-    string key() override
+    std::string key() override
     {
         /* "a$" ensures substitution goals happen before derivation
            goals. */
@@ -77,7 +77,7 @@ public:
     void finished();
 
     /* Callback used by the worker to write to the log. */
-    void handleChildOutput(int fd, const string & data) override;
+    void handleChildOutput(int fd, std::string_view data) override;
     void handleEOF(int fd) override;
 
     void cleanup() override;
diff --git a/src/libstore/build/worker.cc b/src/libstore/build/worker.cc
index 0a6108233..f72c1cc9c 100644
--- a/src/libstore/build/worker.cc
+++ b/src/libstore/build/worker.cc
@@ -394,7 +394,7 @@ void Worker::waitForInput()
                 } else {
                     printMsg(lvlVomit, "%1%: read %2% bytes",
                         goal->getName(), rd);
-                    string data((char *) buffer.data(), rd);
+                    std::string data((char *) buffer.data(), rd);
                     j->lastOutput = after;
                     goal->handleChildOutput(k, data);
                 }
diff --git a/src/libstore/builtins/buildenv.cc b/src/libstore/builtins/buildenv.cc
index e88fc687a..25d015cb9 100644
--- a/src/libstore/builtins/buildenv.cc
+++ b/src/libstore/builtins/buildenv.cc
@@ -123,7 +123,7 @@ void buildProfile(const Path & out, Packages && pkgs)
         createLinks(state, pkgDir, out, priority);
 
         try {
-            for (const auto & p : tokenizeString<std::vector<string>>(
+            for (const auto & p : tokenizeString<std::vector<std::string>>(
                     readFile(pkgDir + "/nix-support/propagated-user-env-packages"), " \n"))
                 if (!done.count(p))
                     postponed.insert(p);
@@ -161,7 +161,7 @@ void buildProfile(const Path & out, Packages && pkgs)
 
 void builtinBuildenv(const BasicDerivation & drv)
 {
-    auto getAttr = [&](const string & name) {
+    auto getAttr = [&](const std::string & name) {
         auto i = drv.env.find(name);
         if (i == drv.env.end()) throw Error("attribute '%s' missing", name);
         return i->second;
diff --git a/src/libstore/builtins/fetchurl.cc b/src/libstore/builtins/fetchurl.cc
index 4fb5d8a06..af3dfc409 100644
--- a/src/libstore/builtins/fetchurl.cc
+++ b/src/libstore/builtins/fetchurl.cc
@@ -16,7 +16,7 @@ void builtinFetchurl(const BasicDerivation & drv, const std::string & netrcData)
         writeFile(settings.netrcFile, netrcData, 0600);
     }
 
-    auto getAttr = [&](const string & name) {
+    auto getAttr = [&](const std::string & name) {
         auto i = drv.env.find(name);
         if (i == drv.env.end()) throw Error("attribute '%s' missing", name);
         return i->second;
diff --git a/src/libstore/builtins/unpack-channel.cc b/src/libstore/builtins/unpack-channel.cc
index d18e3ddaf..426d58a53 100644
--- a/src/libstore/builtins/unpack-channel.cc
+++ b/src/libstore/builtins/unpack-channel.cc
@@ -5,7 +5,7 @@ namespace nix {
 
 void builtinUnpackChannel(const BasicDerivation & drv)
 {
-    auto getAttr = [&](const string & name) {
+    auto getAttr = [&](const std::string & name) {
         auto i = drv.env.find(name);
         if (i == drv.env.end()) throw Error("attribute '%s' missing", name);
         return i->second;
diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index 1ddd1a4d5..2ba03f0dd 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -479,8 +479,8 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     }
 
     case wopAddTextToStore: {
-        string suffix = readString(from);
-        string s = readString(from);
+        std::string suffix = readString(from);
+        std::string s = readString(from);
         auto refs = worker_proto::read(*store, from, Phantom<StorePathSet> {});
         logger->startWork();
         auto path = store->addTextToStore(suffix, s, refs, NoRepair);
@@ -698,8 +698,8 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         if (GET_PROTOCOL_MINOR(clientVersion) >= 12) {
             unsigned int n = readInt(from);
             for (unsigned int i = 0; i < n; i++) {
-                string name = readString(from);
-                string value = readString(from);
+                auto name = readString(from);
+                auto value = readString(from);
                 clientSettings.overrides.emplace(name, value);
             }
         }
diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index 40af6a775..a49be0057 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -82,7 +82,7 @@ bool derivationIsImpure(DerivationType dt) {
 
 bool BasicDerivation::isBuiltin() const
 {
-    return string(builder, 0, 8) == "builtin:";
+    return builder.substr(0, 8) == "builtin:";
 }
 
 
@@ -104,19 +104,19 @@ StorePath writeDerivation(Store & store,
 
 
 /* Read string `s' from stream `str'. */
-static void expect(std::istream & str, const string & s)
+static void expect(std::istream & str, std::string_view s)
 {
     char s2[s.size()];
     str.read(s2, s.size());
-    if (string(s2, s.size()) != s)
+    if (std::string(s2, s.size()) != s)
         throw FormatError("expected string '%1%'", s);
 }
 
 
 /* Read a C-style string from stream `str'. */
-static string parseString(std::istream & str)
+static std::string parseString(std::istream & str)
 {
-    string res;
+    std::string res;
     expect(str, "\"");
     int c;
     while ((c = str.get()) != '"')
@@ -172,7 +172,7 @@ static DerivationOutput parseDerivationOutput(const Store & store,
 {
     if (hashAlgo != "") {
         auto method = FileIngestionMethod::Flat;
-        if (string(hashAlgo, 0, 2) == "r:") {
+        if (hashAlgo.substr(0, 2) == "r:") {
             method = FileIngestionMethod::Recursive;
             hashAlgo = hashAlgo.substr(2);
         }
@@ -260,8 +260,8 @@ Derivation parseDerivation(const Store & store, std::string && s, std::string_vi
     /* Parse the environment variables. */
     expect(str, ",[");
     while (!endOfList(str)) {
-        expect(str, "("); string name = parseString(str);
-        expect(str, ","); string value = parseString(str);
+        expect(str, "("); auto name = parseString(str);
+        expect(str, ","); auto value = parseString(str);
         expect(str, ")");
         drv.env[name] = value;
     }
@@ -271,7 +271,7 @@ Derivation parseDerivation(const Store & store, std::string && s, std::string_vi
 }
 
 
-static void printString(string & res, std::string_view s)
+static void printString(std::string & res, std::string_view s)
 {
     boost::container::small_vector<char, 64 * 1024> buffer;
     buffer.reserve(s.size() * 2 + 2);
@@ -289,7 +289,7 @@ static void printString(string & res, std::string_view s)
 }
 
 
-static void printUnquotedString(string & res, std::string_view s)
+static void printUnquotedString(std::string & res, std::string_view s)
 {
     res += '"';
     res.append(s);
@@ -298,7 +298,7 @@ static void printUnquotedString(string & res, std::string_view s)
 
 
 template<class ForwardIterator>
-static void printStrings(string & res, ForwardIterator i, ForwardIterator j)
+static void printStrings(std::string & res, ForwardIterator i, ForwardIterator j)
 {
     res += '[';
     bool first = true;
@@ -311,7 +311,7 @@ static void printStrings(string & res, ForwardIterator i, ForwardIterator j)
 
 
 template<class ForwardIterator>
-static void printUnquotedStrings(string & res, ForwardIterator i, ForwardIterator j)
+static void printUnquotedStrings(std::string & res, ForwardIterator i, ForwardIterator j)
 {
     res += '[';
     bool first = true;
@@ -323,10 +323,10 @@ static void printUnquotedStrings(string & res, ForwardIterator i, ForwardIterato
 }
 
 
-string Derivation::unparse(const Store & store, bool maskOutputs,
+std::string Derivation::unparse(const Store & store, bool maskOutputs,
     std::map<std::string, StringSet> * actualInputs) const
 {
-    string s;
+    std::string s;
     s.reserve(65536);
     s += "Derive([";
 
@@ -401,7 +401,7 @@ string Derivation::unparse(const Store & store, bool maskOutputs,
 
 
 // FIXME: remove
-bool isDerivation(const string & fileName)
+bool isDerivation(const std::string & fileName)
 {
     return hasSuffix(fileName, drvExtension);
 }
@@ -593,7 +593,7 @@ std::map<std::string, Hash> staticOutputHashes(Store & store, const Derivation &
 }
 
 
-bool wantOutput(const string & output, const std::set<string> & wanted)
+bool wantOutput(const std::string & output, const std::set<std::string> & wanted)
 {
     return wanted.empty() || wanted.find(output) != wanted.end();
 }
diff --git a/src/libstore/derivations.hh b/src/libstore/derivations.hh
index a644cec60..132de82b6 100644
--- a/src/libstore/derivations.hh
+++ b/src/libstore/derivations.hh
@@ -59,21 +59,19 @@ struct DerivationOutput
     std::optional<StorePath> path(const Store & store, std::string_view drvName, std::string_view outputName) const;
 };
 
-typedef std::map<string, DerivationOutput> DerivationOutputs;
+typedef std::map<std::string, DerivationOutput> DerivationOutputs;
 
 /* These are analogues to the previous DerivationOutputs data type, but they
    also contains, for each output, the (optional) store path in which it would
    be written. To calculate values of these types, see the corresponding
    functions in BasicDerivation */
-typedef std::map<string, std::pair<DerivationOutput, std::optional<StorePath>>>
+typedef std::map<std::string, std::pair<DerivationOutput, std::optional<StorePath>>>
   DerivationOutputsAndOptPaths;
 
 /* For inputs that are sub-derivations, we specify exactly which
    output IDs we are interested in. */
 typedef std::map<StorePath, StringSet> DerivationInputs;
 
-typedef std::map<string, string> StringPairs;
-
 enum struct DerivationType : uint8_t {
     InputAddressed,
     DeferredInputAddressed,
@@ -103,7 +101,7 @@ struct BasicDerivation
 {
     DerivationOutputs outputs; /* keyed on symbolic IDs */
     StorePathSet inputSrcs; /* inputs that are sources */
-    string platform;
+    std::string platform;
     Path builder;
     Strings args;
     StringPairs env;
@@ -164,7 +162,7 @@ StorePath writeDerivation(Store & store,
 Derivation parseDerivation(const Store & store, std::string && s, std::string_view name);
 
 // FIXME: remove
-bool isDerivation(const string & fileName);
+bool isDerivation(const std::string & fileName);
 
 /* Calculate the name that will be used for the store path for this
    output.
@@ -222,7 +220,7 @@ typedef std::map<StorePath, DrvHashModulo> DrvHashes;
 // FIXME: global, though at least thread-safe.
 extern Sync<DrvHashes> drvHashes;
 
-bool wantOutput(const string & output, const std::set<string> & wanted);
+bool wantOutput(const std::string & output, const std::set<std::string> & wanted);
 
 struct Source;
 struct Sink;
diff --git a/src/libstore/derived-path.cc b/src/libstore/derived-path.cc
index 3d188e981..194489580 100644
--- a/src/libstore/derived-path.cc
+++ b/src/libstore/derived-path.cc
@@ -75,9 +75,9 @@ DerivedPath::Built DerivedPath::Built::parse(const Store & store, std::string_vi
     assert(n != s.npos);
     auto drvPath = store.parseStorePath(s.substr(0, n));
     auto outputsS = s.substr(n + 1);
-    std::set<string> outputs;
+    std::set<std::string> outputs;
     if (outputsS != "*")
-        outputs = tokenizeString<std::set<string>>(outputsS, ",");
+        outputs = tokenizeString<std::set<std::string>>(outputsS, ",");
     return {drvPath, outputs};
 }
 
diff --git a/src/libstore/dummy-store.cc b/src/libstore/dummy-store.cc
index 62dc21c59..b4fbe0b70 100644
--- a/src/libstore/dummy-store.cc
+++ b/src/libstore/dummy-store.cc
@@ -21,7 +21,7 @@ struct DummyStore : public virtual DummyStoreConfig, public virtual Store
         , Store(params)
     { }
 
-    string getUri() override
+    std::string getUri() override
     {
         return *uriSchemes().begin();
     }
@@ -43,8 +43,11 @@ struct DummyStore : public virtual DummyStoreConfig, public virtual Store
         RepairFlag repair, CheckSigsFlag checkSigs) override
     { unsupported("addToStore"); }
 
-    StorePath addTextToStore(const string & name, const string & s,
-        const StorePathSet & references, RepairFlag repair) override
+    StorePath addTextToStore(
+        std::string_view name,
+        std::string_view s,
+        const StorePathSet & references,
+        RepairFlag repair) override
     { unsupported("addTextToStore"); }
 
     void narFromPath(const StorePath & path, Sink & sink) override
diff --git a/src/libstore/filetransfer.cc b/src/libstore/filetransfer.cc
index 76fed11db..255b42c49 100644
--- a/src/libstore/filetransfer.cc
+++ b/src/libstore/filetransfer.cc
@@ -33,12 +33,12 @@ FileTransferSettings fileTransferSettings;
 
 static GlobalConfig::Register rFileTransferSettings(&fileTransferSettings);
 
-std::string resolveUri(const std::string & uri)
+std::string resolveUri(std::string_view uri)
 {
     if (uri.compare(0, 8, "channel:") == 0)
-        return "https://nixos.org/channels/" + std::string(uri, 8) + "/nixexprs.tar.xz";
+        return "https://nixos.org/channels/" + std::string(uri.substr(8)) + "/nixexprs.tar.xz";
     else
-        return uri;
+        return std::string(uri);
 }
 
 struct curlFileTransfer : public FileTransfer
@@ -197,15 +197,15 @@ struct curlFileTransfer : public FileTransfer
                 result.etag = "";
                 result.data.clear();
                 result.bodySize = 0;
-                statusMsg = trim(match[1]);
+                statusMsg = trim((std::string &) match[1]);
                 acceptRanges = false;
                 encoding = "";
             } else {
                 auto i = line.find(':');
-                if (i != string::npos) {
-                    string name = toLower(trim(string(line, 0, i)));
+                if (i != std::string::npos) {
+                    std::string name = toLower(trim(line.substr(0, i)));
                     if (name == "etag") {
-                        result.etag = trim(string(line, i + 1));
+                        result.etag = trim(line.substr(i + 1));
                         /* Hack to work around a GitHub bug: it sends
                            ETags, but ignores If-None-Match. So if we get
                            the expected ETag on a 200 response, then shut
@@ -218,8 +218,8 @@ struct curlFileTransfer : public FileTransfer
                             return 0;
                         }
                     } else if (name == "content-encoding")
-                        encoding = trim(string(line, i + 1));
-                    else if (name == "accept-ranges" && toLower(trim(std::string(line, i + 1))) == "bytes")
+                        encoding = trim(line.substr(i + 1));
+                    else if (name == "accept-ranges" && toLower(trim(line.substr(i + 1))) == "bytes")
                         acceptRanges = true;
                 }
             }
@@ -866,18 +866,18 @@ FileTransferError::FileTransferError(FileTransfer::Error error, std::optional<st
     // FIXME: Due to https://github.com/NixOS/nix/issues/3841 we don't know how
     // to print different messages for different verbosity levels. For now
     // we add some heuristics for detecting when we want to show the response.
-    if (response && (response->size() < 1024 || response->find("<html>") != string::npos))
+    if (response && (response->size() < 1024 || response->find("<html>") != std::string::npos))
         err.msg = hintfmt("%1%\n\nresponse body:\n\n%2%", normaltxt(hf.str()), chomp(*response));
     else
         err.msg = hf;
 }
 
-bool isUri(const string & s)
+bool isUri(std::string_view s)
 {
     if (s.compare(0, 8, "channel:") == 0) return true;
     size_t pos = s.find("://");
-    if (pos == string::npos) return false;
-    string scheme(s, 0, pos);
+    if (pos == std::string::npos) return false;
+    std::string scheme(s, 0, pos);
     return scheme == "http" || scheme == "https" || scheme == "file" || scheme == "channel" || scheme == "git" || scheme == "s3" || scheme == "ssh";
 }
 
diff --git a/src/libstore/filetransfer.hh b/src/libstore/filetransfer.hh
index 3e61b23b1..ca61e3937 100644
--- a/src/libstore/filetransfer.hh
+++ b/src/libstore/filetransfer.hh
@@ -119,17 +119,17 @@ class FileTransferError : public Error
 {
 public:
     FileTransfer::Error error;
-    std::optional<string> response; // intentionally optional
+    std::optional<std::string> response; // intentionally optional
 
     template<typename... Args>
-    FileTransferError(FileTransfer::Error error, std::optional<string> response, const Args & ... args);
+    FileTransferError(FileTransfer::Error error, std::optional<std::string> response, const Args & ... args);
 
     virtual const char* sname() const override { return "FileTransferError"; }
 };
 
-bool isUri(const string & s);
+bool isUri(std::string_view s);
 
 /* Resolve deprecated 'channel:<foo>' URLs. */
-std::string resolveUri(const std::string & uri);
+std::string resolveUri(std::string_view uri);
 
 }
diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index e35199b3d..fd38b731c 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -47,9 +47,8 @@ static void makeSymlink(const Path & link, const Path & target)
 
 void LocalStore::addIndirectRoot(const Path & path)
 {
-    string hash = hashString(htSHA1, path).to_string(Base32, false);
-    Path realRoot = canonPath((format("%1%/%2%/auto/%3%")
-        % stateDir % gcRootsDir % hash).str());
+    std::string hash = hashString(htSHA1, path).to_string(Base32, false);
+    Path realRoot = canonPath(fmt("%1%/%2%/auto/%3%", stateDir, gcRootsDir, hash));
     makeSymlink(realRoot, path);
 }
 
@@ -162,7 +161,7 @@ void LocalStore::addTempRoot(const StorePath & path)
     }
 
     /* Append the store path to the temporary roots file. */
-    string s = printStorePath(path) + '\0';
+    auto s = printStorePath(path) + '\0';
     writeFull(state->fdTempRoots.get(), s);
 }
 
@@ -203,12 +202,12 @@ void LocalStore::findTempRoots(Roots & tempRoots, bool censor)
         }
 
         /* Read the entire file. */
-        string contents = readFile(fd.get());
+        auto contents = readFile(fd.get());
 
         /* Extract the roots. */
-        string::size_type pos = 0, end;
+        std::string::size_type pos = 0, end;
 
-        while ((end = contents.find((char) 0, pos)) != string::npos) {
+        while ((end = contents.find((char) 0, pos)) != std::string::npos) {
             Path root(contents, pos, end - pos);
             debug("got temporary root '%s'", root);
             tempRoots[parseStorePath(root)].emplace(censor ? censored : fmt("{temp:%d}", pid));
@@ -305,7 +304,7 @@ Roots LocalStore::findRoots(bool censor)
 
 typedef std::unordered_map<Path, std::unordered_set<std::string>> UncheckedRoots;
 
-static void readProcLink(const string & file, UncheckedRoots & roots)
+static void readProcLink(const std::string & file, UncheckedRoots & roots)
 {
     /* 64 is the starting buffer size gnu readlink uses... */
     auto bufsiz = ssize_t{64};
@@ -328,7 +327,7 @@ try_again:
             .emplace(file);
 }
 
-static string quoteRegexChars(const string & raw)
+static std::string quoteRegexChars(const std::string & raw)
 {
     static auto specialRegex = std::regex(R"([.^$\\*+?()\[\]{}|])");
     return std::regex_replace(raw, specialRegex, R"(\$&)");
@@ -383,7 +382,7 @@ void LocalStore::findRuntimeRoots(Roots & roots, bool censor)
 
                 try {
                     auto mapFile = fmt("/proc/%s/maps", ent->d_name);
-                    auto mapLines = tokenizeString<std::vector<string>>(readFile(mapFile), "\n");
+                    auto mapLines = tokenizeString<std::vector<std::string>>(readFile(mapFile), "\n");
                     for (const auto & line : mapLines) {
                         auto match = std::smatch{};
                         if (std::regex_match(line, match, mapRegex))
@@ -784,7 +783,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
             struct dirent * dirent;
             while (errno = 0, dirent = readdir(dir.get())) {
                 checkInterrupt();
-                string name = dirent->d_name;
+                std::string name = dirent->d_name;
                 if (name == "." || name == ".." || name == linksName) continue;
 
                 if (auto storePath = maybeParseStorePath(storeDir + "/" + name))
@@ -825,7 +824,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
         struct dirent * dirent;
         while (errno = 0, dirent = readdir(dir.get())) {
             checkInterrupt();
-            string name = dirent->d_name;
+            std::string name = dirent->d_name;
             if (name == "." || name == "..") continue;
             Path path = linksDir + "/" + name;
 
diff --git a/src/libstore/globals.cc b/src/libstore/globals.cc
index 81ca9cc0f..cc009a026 100644
--- a/src/libstore/globals.cc
+++ b/src/libstore/globals.cc
@@ -100,7 +100,7 @@ std::vector<Path> getUserConfigFiles()
     // Use the paths specified in NIX_USER_CONF_FILES if it has been defined
     auto nixConfFiles = getEnv("NIX_USER_CONF_FILES");
     if (nixConfFiles.has_value()) {
-        return tokenizeString<std::vector<string>>(nixConfFiles.value(), ":");
+        return tokenizeString<std::vector<std::string>>(nixConfFiles.value(), ":");
     }
 
     // Use the paths specified by the XDG spec
@@ -181,7 +181,7 @@ bool Settings::isWSL1()
     return hasSuffix(utsbuf.release, "-Microsoft");
 }
 
-const string nixVersion = PACKAGE_VERSION;
+const std::string nixVersion = PACKAGE_VERSION;
 
 NLOHMANN_JSON_SERIALIZE_ENUM(SandboxMode, {
     {SandboxMode::smEnabled, true},
diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index 4a78729e9..b31a2e8dc 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -988,6 +988,6 @@ void loadConfFile();
 // Used by the Settings constructor
 std::vector<Path> getUserConfigFiles();
 
-extern const string nixVersion;
+extern const std::string nixVersion;
 
 }
diff --git a/src/libstore/legacy-ssh-store.cc b/src/libstore/legacy-ssh-store.cc
index f8b2662af..6b3daae7f 100644
--- a/src/libstore/legacy-ssh-store.cc
+++ b/src/libstore/legacy-ssh-store.cc
@@ -48,7 +48,7 @@ struct LegacySSHStore : public virtual LegacySSHStoreConfig, public virtual Stor
 
     static std::set<std::string> uriSchemes() { return {"ssh"}; }
 
-    LegacySSHStore(const string & scheme, const string & host, const Params & params)
+    LegacySSHStore(const std::string & scheme, const std::string & host, const Params & params)
         : StoreConfig(params)
         , LegacySSHStoreConfig(params)
         , Store(params)
@@ -107,7 +107,7 @@ struct LegacySSHStore : public virtual LegacySSHStoreConfig, public virtual Stor
         return conn;
     };
 
-    string getUri() override
+    std::string getUri() override
     {
         return *uriSchemes().begin() + "://" + host;
     }
@@ -225,13 +225,21 @@ struct LegacySSHStore : public virtual LegacySSHStoreConfig, public virtual Stor
     std::optional<StorePath> queryPathFromHashPart(const std::string & hashPart) override
     { unsupported("queryPathFromHashPart"); }
 
-    StorePath addToStore(const string & name, const Path & srcPath,
-        FileIngestionMethod method, HashType hashAlgo,
-        PathFilter & filter, RepairFlag repair, const StorePathSet & references) override
+    StorePath addToStore(
+        std::string_view name,
+        const Path & srcPath,
+        FileIngestionMethod method,
+        HashType hashAlgo,
+        PathFilter & filter,
+        RepairFlag repair,
+        const StorePathSet & references) override
     { unsupported("addToStore"); }
 
-    StorePath addTextToStore(const string & name, const string & s,
-        const StorePathSet & references, RepairFlag repair) override
+    StorePath addTextToStore(
+        std::string_view name,
+        std::string_view s,
+        const StorePathSet & references,
+        RepairFlag repair) override
     { unsupported("addTextToStore"); }
 
 private:
diff --git a/src/libstore/local-fs-store.cc b/src/libstore/local-fs-store.cc
index c933251db..c5ae7536f 100644
--- a/src/libstore/local-fs-store.cc
+++ b/src/libstore/local-fs-store.cc
@@ -85,7 +85,7 @@ void LocalFSStore::narFromPath(const StorePath & path, Sink & sink)
     dumpPath(getRealStoreDir() + std::string(printStorePath(path), storeDir.size()), sink);
 }
 
-const string LocalFSStore::drvsLogDir = "drvs";
+const std::string LocalFSStore::drvsLogDir = "drvs";
 
 std::optional<std::string> LocalFSStore::getBuildLog(const StorePath & path_)
 {
diff --git a/src/libstore/local-fs-store.hh b/src/libstore/local-fs-store.hh
index e44b27cc2..d34f0cb62 100644
--- a/src/libstore/local-fs-store.hh
+++ b/src/libstore/local-fs-store.hh
@@ -27,7 +27,7 @@ class LocalFSStore : public virtual LocalFSStoreConfig, public virtual Store
 {
 public:
 
-    const static string drvsLogDir;
+    const static std::string drvsLogDir;
 
     LocalFSStore(const Params & params);
 
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 1a02b916a..1ee71b1c0 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -70,7 +70,7 @@ int getSchema(Path schemaPath)
 {
     int curSchema = 0;
     if (pathExists(schemaPath)) {
-        string s = readFile(schemaPath);
+        auto s = readFile(schemaPath);
         auto n = string2Int<int>(s);
         if (!n)
             throw Error("'%1%' is corrupt", schemaPath);
@@ -239,7 +239,7 @@ LocalStore::LocalStore(const Params & params)
             res = posix_fallocate(fd.get(), 0, settings.reservedSize);
 #endif
             if (res == -1) {
-                writeFull(fd.get(), string(settings.reservedSize, 'X'));
+                writeFull(fd.get(), std::string(settings.reservedSize, 'X'));
                 [[gnu::unused]] auto res2 = ftruncate(fd.get(), settings.reservedSize);
             }
         }
@@ -450,7 +450,7 @@ void LocalStore::openDB(State & state, bool create)
         throw SysError("Nix database directory '%1%' is not writable", dbDir);
 
     /* Open the Nix database. */
-    string dbPath = dbDir + "/db.sqlite";
+    std::string dbPath = dbDir + "/db.sqlite";
     auto & db(state.db);
     state.db = SQLite(dbPath, create);
 
@@ -471,19 +471,19 @@ void LocalStore::openDB(State & state, bool create)
        should be safe enough.  If the user asks for it, don't sync at
        all.  This can cause database corruption if the system
        crashes. */
-    string syncMode = settings.fsyncMetadata ? "normal" : "off";
+    std::string syncMode = settings.fsyncMetadata ? "normal" : "off";
     db.exec("pragma synchronous = " + syncMode);
 
     /* Set the SQLite journal mode.  WAL mode is fastest, so it's the
        default. */
-    string mode = settings.useSQLiteWAL ? "wal" : "truncate";
-    string prevMode;
+    std::string mode = settings.useSQLiteWAL ? "wal" : "truncate";
+    std::string prevMode;
     {
         SQLiteStmt stmt;
         stmt.create(db, "pragma main.journal_mode;");
         if (sqlite3_step(stmt) != SQLITE_ROW)
             throwSQLiteError(db, "querying journal mode");
-        prevMode = string((const char *) sqlite3_column_text(stmt, 0));
+        prevMode = std::string((const char *) sqlite3_column_text(stmt, 0));
     }
     if (prevMode != mode &&
         sqlite3_exec(db, ("pragma main.journal_mode = " + mode + ";").c_str(), 0, 0, 0) != SQLITE_OK)
@@ -679,7 +679,7 @@ void LocalStore::checkDerivationOutputs(const StorePath & drvPath, const Derivat
 {
     assert(drvPath.isDerivation());
     std::string drvName(drvPath.name());
-    drvName = string(drvName, 0, drvName.size() - drvExtension.size());
+    drvName = drvName.substr(0, drvName.size() - drvExtension.size());
 
     auto envHasRightPath = [&](const StorePath & actual, const std::string & varName)
     {
@@ -786,7 +786,11 @@ void LocalStore::registerDrvOutput(const Realisation & info)
     });
 }
 
-void LocalStore::cacheDrvOutputMapping(State & state, const uint64_t deriver, const string & outputName, const StorePath & output)
+void LocalStore::cacheDrvOutputMapping(
+    State & state,
+    const uint64_t deriver,
+    const std::string & outputName,
+    const StorePath & output)
 {
     retrySQLite<void>([&]() {
         state.stmts->AddDerivationOutput.use()
@@ -795,7 +799,6 @@ void LocalStore::cacheDrvOutputMapping(State & state, const uint64_t deriver, co
             (printStorePath(output))
             .exec();
     });
-
 }
 
 
@@ -1436,7 +1439,9 @@ StorePath LocalStore::addToStoreFromDump(Source & source0, std::string_view name
 }
 
 
-StorePath LocalStore::addTextToStore(const string & name, const string & s,
+StorePath LocalStore::addTextToStore(
+    std::string_view name,
+    std::string_view s,
     const StorePathSet & references, RepairFlag repair)
 {
     auto hash = hashString(htSHA256, s);
@@ -1548,7 +1553,7 @@ bool LocalStore::verifyStore(bool checkContents, RepairFlag repair)
         for (auto & link : readDirectory(linksDir)) {
             printMsg(lvlTalkative, "checking contents of '%s'", link.name);
             Path linkPath = linksDir + "/" + link.name;
-            string hash = hashPath(htSHA256, linkPath).first.to_string(Base32, false);
+            std::string hash = hashPath(htSHA256, linkPath).first.to_string(Base32, false);
             if (hash != link.name) {
                 printError("link '%s' was modified! expected hash '%s', got '%s'",
                     linkPath, link.name, hash);
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index a9c7475ac..1a278c9a8 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -147,8 +147,11 @@ public:
     StorePath addToStoreFromDump(Source & dump, std::string_view name,
         FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, const StorePathSet & references) override;
 
-    StorePath addTextToStore(const string & name, const string & s,
-        const StorePathSet & references, RepairFlag repair) override;
+    StorePath addTextToStore(
+        std::string_view name,
+        std::string_view s,
+        const StorePathSet & references,
+        RepairFlag repair) override;
 
     void addTempRoot(const StorePath & path) override;
 
@@ -204,7 +207,11 @@ public:
        derivation 'deriver'. */
     void registerDrvOutput(const Realisation & info) override;
     void registerDrvOutput(const Realisation & info, CheckSigsFlag checkSigs) override;
-    void cacheDrvOutputMapping(State & state, const uint64_t deriver, const string & outputName, const StorePath & output);
+    void cacheDrvOutputMapping(
+        State & state,
+        const uint64_t deriver,
+        const std::string & outputName,
+        const StorePath & output);
 
     std::optional<const Realisation> queryRealisation_(State & state, const DrvOutput & id);
     std::optional<std::pair<int64_t, Realisation>> queryRealisationCore_(State & state, const DrvOutput & id);
diff --git a/src/libstore/lock.hh b/src/libstore/lock.hh
index 8fbb67ddc..3d29a7b5b 100644
--- a/src/libstore/lock.hh
+++ b/src/libstore/lock.hh
@@ -13,7 +13,7 @@ private:
     AutoCloseFD fdUserLock;
 
     bool isEnabled = false;
-    string user;
+    std::string user;
     uid_t uid = 0;
     gid_t gid = 0;
     std::vector<gid_t> supplementaryGIDs;
@@ -23,7 +23,7 @@ public:
 
     void kill();
 
-    string getUser() { return user; }
+    std::string getUser() { return user; }
     uid_t getUID() { assert(uid); return uid; }
     uid_t getGID() { assert(gid); return gid; }
     std::vector<gid_t> getSupplementaryGIDs() { return supplementaryGIDs; }
diff --git a/src/libstore/machines.cc b/src/libstore/machines.cc
index b6270a81b..e87f46980 100644
--- a/src/libstore/machines.cc
+++ b/src/libstore/machines.cc
@@ -39,19 +39,19 @@ Machine::Machine(decltype(storeUri) storeUri,
     sshPublicHostKey(sshPublicHostKey)
 {}
 
-bool Machine::allSupported(const std::set<string> & features) const
+bool Machine::allSupported(const std::set<std::string> & features) const
 {
     return std::all_of(features.begin(), features.end(),
-        [&](const string & feature) {
+        [&](const std::string & feature) {
             return supportedFeatures.count(feature) ||
                 mandatoryFeatures.count(feature);
         });
 }
 
-bool Machine::mandatoryMet(const std::set<string> & features) const
+bool Machine::mandatoryMet(const std::set<std::string> & features) const
 {
     return std::all_of(mandatoryFeatures.begin(), mandatoryFeatures.end(),
-        [&](const string & feature) {
+        [&](const std::string & feature) {
             return features.count(feature);
         });
 }
@@ -89,7 +89,7 @@ ref<Store> Machine::openStore() const
 static std::vector<std::string> expandBuilderLines(const std::string & builders)
 {
     std::vector<std::string> result;
-    for (auto line : tokenizeString<std::vector<string>>(builders, "\n;")) {
+    for (auto line : tokenizeString<std::vector<std::string>>(builders, "\n;")) {
         trim(line);
         line.erase(std::find(line.begin(), line.end(), '#'), line.end());
         if (line.empty()) continue;
@@ -117,7 +117,7 @@ static std::vector<std::string> expandBuilderLines(const std::string & builders)
 
 static Machine parseBuilderLine(const std::string & line)
 {
-    const auto tokens = tokenizeString<std::vector<string>>(line);
+    const auto tokens = tokenizeString<std::vector<std::string>>(line);
 
     auto isSet = [&](size_t fieldIndex) {
         return tokens.size() > fieldIndex && tokens[fieldIndex] != "" && tokens[fieldIndex] != "-";
@@ -146,17 +146,18 @@ static Machine parseBuilderLine(const std::string & line)
 
     return {
         tokens[0],
-        isSet(1) ? tokenizeString<std::vector<string>>(tokens[1], ",") : std::vector<string>{settings.thisSystem},
+        isSet(1) ? tokenizeString<std::vector<std::string>>(tokens[1], ",") : std::vector<std::string>{settings.thisSystem},
         isSet(2) ? tokens[2] : "",
         isSet(3) ? parseUnsignedIntField(3) : 1U,
         isSet(4) ? parseUnsignedIntField(4) : 1U,
-        isSet(5) ? tokenizeString<std::set<string>>(tokens[5], ",") : std::set<string>{},
-        isSet(6) ? tokenizeString<std::set<string>>(tokens[6], ",") : std::set<string>{},
+        isSet(5) ? tokenizeString<std::set<std::string>>(tokens[5], ",") : std::set<std::string>{},
+        isSet(6) ? tokenizeString<std::set<std::string>>(tokens[6], ",") : std::set<std::string>{},
         isSet(7) ? ensureBase64(7) : ""
     };
 }
 
-static Machines parseBuilderLines(const std::vector<std::string>& builders) {
+static Machines parseBuilderLines(const std::vector<std::string> & builders)
+{
     Machines result;
     std::transform(builders.begin(), builders.end(), std::back_inserter(result), parseBuilderLine);
     return result;
diff --git a/src/libstore/nar-accessor.cc b/src/libstore/nar-accessor.cc
index 7d27d7667..72d41cc94 100644
--- a/src/libstore/nar-accessor.cc
+++ b/src/libstore/nar-accessor.cc
@@ -90,7 +90,7 @@ struct NarAccessor : public FSAccessor
         void receiveContents(std::string_view data) override
         { }
 
-        void createSymlink(const Path & path, const string & target) override
+        void createSymlink(const Path & path, const std::string & target) override
         {
             createMember(path,
                 NarMember{FSAccessor::Type::tSymlink, false, 0, 0, target});
diff --git a/src/libstore/nar-info.cc b/src/libstore/nar-info.cc
index 49079388a..2d75e7a82 100644
--- a/src/libstore/nar-info.cc
+++ b/src/libstore/nar-info.cc
@@ -11,7 +11,7 @@ NarInfo::NarInfo(const Store & store, const std::string & s, const std::string &
         return Error("NAR info file '%1%' is corrupt", whence);
     };
 
-    auto parseHashField = [&](const string & s) {
+    auto parseHashField = [&](const std::string & s) {
         try {
             return Hash::parseAnyPrefixed(s);
         } catch (BadHash &) {
diff --git a/src/libstore/optimise-store.cc b/src/libstore/optimise-store.cc
index 13cb142f8..8af9b1dde 100644
--- a/src/libstore/optimise-store.cc
+++ b/src/libstore/optimise-store.cc
@@ -77,7 +77,7 @@ Strings LocalStore::readDirectoryIgnoringInodes(const Path & path, const InodeHa
             continue;
         }
 
-        string name = dirent->d_name;
+        std::string name = dirent->d_name;
         if (name == "." || name == "..") continue;
         names.push_back(name);
     }
diff --git a/src/libstore/path-with-outputs.cc b/src/libstore/path-with-outputs.cc
index e5a121e00..97aa01b57 100644
--- a/src/libstore/path-with-outputs.cc
+++ b/src/libstore/path-with-outputs.cc
@@ -49,9 +49,9 @@ std::pair<std::string_view, StringSet> parsePathWithOutputs(std::string_view s)
 {
     size_t n = s.find("!");
     return n == s.npos
-        ? std::make_pair(s, std::set<string>())
+        ? std::make_pair(s, std::set<std::string>())
         : std::make_pair(((std::string_view) s).substr(0, n),
-            tokenizeString<std::set<string>>(((std::string_view) s).substr(n + 1), ","));
+            tokenizeString<std::set<std::string>>(((std::string_view) s).substr(n + 1), ","));
 }
 
 
diff --git a/src/libstore/path.hh b/src/libstore/path.hh
index 06ba0663b..e65fee622 100644
--- a/src/libstore/path.hh
+++ b/src/libstore/path.hh
@@ -62,7 +62,7 @@ public:
 
 typedef std::set<StorePath> StorePathSet;
 typedef std::vector<StorePath> StorePaths;
-typedef std::map<string, StorePath> OutputPathMap;
+typedef std::map<std::string, StorePath> OutputPathMap;
 
 typedef std::map<StorePath, std::optional<ContentAddress>> StorePathCAMap;
 
diff --git a/src/libstore/pathlocks.cc b/src/libstore/pathlocks.cc
index 2da74e262..42023cd0a 100644
--- a/src/libstore/pathlocks.cc
+++ b/src/libstore/pathlocks.cc
@@ -74,7 +74,7 @@ PathLocks::PathLocks()
 }
 
 
-PathLocks::PathLocks(const PathSet & paths, const string & waitMsg)
+PathLocks::PathLocks(const PathSet & paths, const std::string & waitMsg)
     : deletePaths(false)
 {
     lockPaths(paths, waitMsg);
@@ -82,7 +82,7 @@ PathLocks::PathLocks(const PathSet & paths, const string & waitMsg)
 
 
 bool PathLocks::lockPaths(const PathSet & paths,
-    const string & waitMsg, bool wait)
+    const std::string & waitMsg, bool wait)
 {
     assert(fds.empty());
 
diff --git a/src/libstore/pathlocks.hh b/src/libstore/pathlocks.hh
index 759b9a584..5e3a734b4 100644
--- a/src/libstore/pathlocks.hh
+++ b/src/libstore/pathlocks.hh
@@ -26,9 +26,9 @@ private:
 public:
     PathLocks();
     PathLocks(const PathSet & paths,
-        const string & waitMsg = "");
+        const std::string & waitMsg = "");
     bool lockPaths(const PathSet & _paths,
-        const string & waitMsg = "",
+        const std::string & waitMsg = "",
         bool wait = true);
     ~PathLocks();
     void unlock();
diff --git a/src/libstore/profiles.cc b/src/libstore/profiles.cc
index 73163424c..3e4188188 100644
--- a/src/libstore/profiles.cc
+++ b/src/libstore/profiles.cc
@@ -15,12 +15,12 @@ namespace nix {
 
 /* Parse a generation name of the format
    `<profilename>-<number>-link'. */
-static std::optional<GenerationNumber> parseName(const string & profileName, const string & name)
+static std::optional<GenerationNumber> parseName(const std::string & profileName, const std::string & name)
 {
-    if (string(name, 0, profileName.size() + 1) != profileName + "-") return {};
-    string s = string(name, profileName.size() + 1);
-    string::size_type p = s.find("-link");
-    if (p == string::npos) return {};
+    if (name.substr(0, profileName.size() + 1) != profileName + "-") return {};
+    auto s = name.substr(profileName.size() + 1);
+    auto p = s.find("-link");
+    if (p == std::string::npos) return {};
     if (auto n = string2Int<unsigned int>(s.substr(0, p)))
         return *n;
     else
@@ -209,13 +209,13 @@ void deleteGenerationsOlderThan(const Path & profile, time_t t, bool dryRun)
 }
 
 
-void deleteGenerationsOlderThan(const Path & profile, const string & timeSpec, bool dryRun)
+void deleteGenerationsOlderThan(const Path & profile, std::string_view timeSpec, bool dryRun)
 {
     if (timeSpec.empty() || timeSpec[timeSpec.size() - 1] != 'd')
         throw UsageError("invalid number of days specifier '%1%', expected something like '14d'", timeSpec);
 
     time_t curTime = time(0);
-    string strDays = string(timeSpec, 0, timeSpec.size() - 1);
+    auto strDays = timeSpec.substr(0, timeSpec.size() - 1);
     auto days = string2Int<int>(strDays);
 
     if (!days || *days < 1)
@@ -274,7 +274,7 @@ void lockProfile(PathLocks & lock, const Path & profile)
 }
 
 
-string optimisticLockProfile(const Path & profile)
+std::string optimisticLockProfile(const Path & profile)
 {
     return pathExists(profile) ? readLink(profile) : "";
 }
diff --git a/src/libstore/profiles.hh b/src/libstore/profiles.hh
index d100c970c..408ca039c 100644
--- a/src/libstore/profiles.hh
+++ b/src/libstore/profiles.hh
@@ -42,7 +42,7 @@ void deleteOldGenerations(const Path & profile, bool dryRun);
 
 void deleteGenerationsOlderThan(const Path & profile, time_t t, bool dryRun);
 
-void deleteGenerationsOlderThan(const Path & profile, const string & timeSpec, bool dryRun);
+void deleteGenerationsOlderThan(const Path & profile, std::string_view timeSpec, bool dryRun);
 
 void switchLink(Path link, Path target);
 
@@ -66,7 +66,7 @@ void lockProfile(PathLocks & lock, const Path & profile);
    generally cheap, since the build results are still in the Nix
    store.  Most of the time, only the user environment has to be
    rebuilt. */
-string optimisticLockProfile(const Path & profile);
+std::string optimisticLockProfile(const Path & profile);
 
 /* Resolve ~/.nix-profile. If ~/.nix-profile doesn't exist yet, create
    it. */
diff --git a/src/libstore/references.cc b/src/libstore/references.cc
index 91b3fc142..34dce092c 100644
--- a/src/libstore/references.cc
+++ b/src/libstore/references.cc
@@ -68,7 +68,7 @@ void RefScanSink::operator () (std::string_view data)
 
 
 std::pair<StorePathSet, HashResult> scanForReferences(
-    const string & path,
+    const std::string & path,
     const StorePathSet & refs)
 {
     HashSink hashSink { htSHA256 };
@@ -121,7 +121,7 @@ void RewritingSink::operator () (std::string_view data)
     s.append(data);
 
     size_t j = 0;
-    while ((j = s.find(from, j)) != string::npos) {
+    while ((j = s.find(from, j)) != std::string::npos) {
         matches.push_back(pos + j);
         s.replace(j, from.size(), to);
     }
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index c6f083dea..e7ffa6595 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -661,8 +661,11 @@ void RemoteStore::addMultipleToStore(
 }
 
 
-StorePath RemoteStore::addTextToStore(const string & name, const string & s,
-    const StorePathSet & references, RepairFlag repair)
+StorePath RemoteStore::addTextToStore(
+    std::string_view name,
+    std::string_view s,
+    const StorePathSet & references,
+    RepairFlag repair)
 {
     StringSource source(s);
     return addCAToStore(source, name, TextHashMethod{}, references, repair)->path;
@@ -1000,7 +1003,7 @@ std::exception_ptr RemoteStore::Connection::processStderr(Sink * sink, Source *
         auto msg = readNum<uint64_t>(from);
 
         if (msg == STDERR_WRITE) {
-            string s = readString(from);
+            auto s = readString(from);
             if (!sink) throw Error("no sink");
             (*sink)(s);
         }
@@ -1017,7 +1020,7 @@ std::exception_ptr RemoteStore::Connection::processStderr(Sink * sink, Source *
             if (GET_PROTOCOL_MINOR(daemonVersion) >= 26) {
                 return std::make_exception_ptr(readError(from));
             } else {
-                string error = readString(from);
+                auto error = readString(from);
                 unsigned int status = readInt(from);
                 return std::make_exception_ptr(Error(status, error));
             }
diff --git a/src/libstore/remote-store.hh b/src/libstore/remote-store.hh
index 55cfd5cc6..b94216d31 100644
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@@ -83,8 +83,11 @@ public:
         RepairFlag repair,
         CheckSigsFlag checkSigs) override;
 
-    StorePath addTextToStore(const string & name, const string & s,
-        const StorePathSet & references, RepairFlag repair) override;
+    StorePath addTextToStore(
+        std::string_view name,
+        std::string_view s,
+        const StorePathSet & references,
+        RepairFlag repair) override;
 
     void registerDrvOutput(const Realisation & info) override;
 
diff --git a/src/libstore/s3-binary-cache-store.cc b/src/libstore/s3-binary-cache-store.cc
index a024e971d..844553ad3 100644
--- a/src/libstore/s3-binary-cache-store.cc
+++ b/src/libstore/s3-binary-cache-store.cc
@@ -87,7 +87,11 @@ static void initAWS()
     });
 }
 
-S3Helper::S3Helper(const string & profile, const string & region, const string & scheme, const string & endpoint)
+S3Helper::S3Helper(
+    const std::string & profile,
+    const std::string & region,
+    const std::string & scheme,
+    const std::string & endpoint)
     : config(makeConfig(region, scheme, endpoint))
     , client(make_ref<Aws::S3::S3Client>(
             profile == ""
@@ -121,7 +125,10 @@ class RetryStrategy : public Aws::Client::DefaultRetryStrategy
     }
 };
 
-ref<Aws::Client::ClientConfiguration> S3Helper::makeConfig(const string & region, const string & scheme, const string & endpoint)
+ref<Aws::Client::ClientConfiguration> S3Helper::makeConfig(
+    const std::string & region,
+    const std::string & scheme,
+    const std::string & endpoint)
 {
     initAWS();
     auto res = make_ref<Aws::Client::ClientConfiguration>();
diff --git a/src/libstore/sqlite.cc b/src/libstore/sqlite.cc
index 1d6baf02d..e6ecadd7f 100644
--- a/src/libstore/sqlite.cc
+++ b/src/libstore/sqlite.cc
@@ -71,7 +71,7 @@ uint64_t SQLite::getLastInsertedRowId()
     return sqlite3_last_insert_rowid(db);
 }
 
-void SQLiteStmt::create(sqlite3 * db, const string & sql)
+void SQLiteStmt::create(sqlite3 * db, const std::string & sql)
 {
     checkInterrupt();
     assert(!stmt);
diff --git a/src/libstore/ssh.cc b/src/libstore/ssh.cc
index 93f72675d..1bbad71f2 100644
--- a/src/libstore/ssh.cc
+++ b/src/libstore/ssh.cc
@@ -29,7 +29,7 @@ void SSHMaster::addCommonSSHOpts(Strings & args)
     if (!sshPublicHostKey.empty()) {
         Path fileName = (Path) *state->tmpDir + "/host-key";
         auto p = host.rfind("@");
-        string thost = p != string::npos ? string(host, p + 1) : host;
+        std::string thost = p != std::string::npos ? std::string(host, p + 1) : host;
         writeFile(fileName, thost + " " + base64Decode(sshPublicHostKey) + "\n");
         args.insert(args.end(), {"-oUserKnownHostsFile=" + fileName});
     }
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 8fcdc8b57..86fa6a211 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -39,7 +39,7 @@ Path Store::followLinksToStore(std::string_view _path) const
     Path path = absPath(std::string(_path));
     while (!isInStore(path)) {
         if (!isLink(path)) break;
-        string target = readLink(path);
+        auto target = readLink(path);
         path = absPath(target, dirOf(path));
     }
     if (!isInStore(path))
@@ -138,8 +138,8 @@ StorePath Store::makeStorePath(std::string_view type,
     std::string_view hash, std::string_view name) const
 {
     /* e.g., "source:sha256:1abc...:/nix/store:foo.tar.gz" */
-    string s = std::string { type } + ":" + std::string { hash }
-        + ":" + storeDir + ":" + std::string { name };
+    auto s = std::string(type) + ":" + std::string(hash)
+        + ":" + storeDir + ":" + std::string(name);
     auto h = compressHash(hashString(htSHA256, s), 20);
     return StorePath(h, name);
 }
@@ -161,7 +161,7 @@ StorePath Store::makeOutputPath(std::string_view id,
 
 static std::string makeType(
     const Store & store,
-    string && type,
+    std::string && type,
     const StorePathSet & references,
     bool hasSelfReference = false)
 {
@@ -229,15 +229,23 @@ std::pair<StorePath, Hash> Store::computeStorePathForPath(std::string_view name,
 }
 
 
-StorePath Store::computeStorePathForText(const string & name, const string & s,
+StorePath Store::computeStorePathForText(
+    std::string_view name,
+    std::string_view s,
     const StorePathSet & references) const
 {
     return makeTextPath(name, hashString(htSHA256, s), references);
 }
 
 
-StorePath Store::addToStore(const string & name, const Path & _srcPath,
-    FileIngestionMethod method, HashType hashAlgo, PathFilter & filter, RepairFlag repair, const StorePathSet & references)
+StorePath Store::addToStore(
+    std::string_view name,
+    const Path & _srcPath,
+    FileIngestionMethod method,
+    HashType hashAlgo,
+    PathFilter & filter,
+    RepairFlag repair,
+    const StorePathSet & references)
 {
     Path srcPath(absPath(_srcPath));
     auto source = sinkToSource([&](Sink & sink) {
@@ -688,10 +696,10 @@ StorePathSet Store::queryValidPaths(const StorePathSet & paths, SubstituteFlag m
 /* Return a string accepted by decodeValidPathInfo() that
    registers the specified paths as valid.  Note: it's the
    responsibility of the caller to provide a closure. */
-string Store::makeValidityRegistration(const StorePathSet & paths,
+std::string Store::makeValidityRegistration(const StorePathSet & paths,
     bool showDerivers, bool showHash)
 {
-    string s = "";
+    std::string s = "";
 
     for (auto & i : paths) {
         s += printStorePath(i) + "\n";
@@ -1131,7 +1139,7 @@ std::optional<ValidPathInfo> decodeValidPathInfo(const Store & store, std::istre
     getline(str, path);
     if (str.eof()) { return {}; }
     if (!hashGiven) {
-        string s;
+        std::string s;
         getline(str, s);
         auto narHash = Hash::parseAny(s, htSHA256);
         getline(str, s);
@@ -1144,7 +1152,7 @@ std::optional<ValidPathInfo> decodeValidPathInfo(const Store & store, std::istre
     std::string deriver;
     getline(str, deriver);
     if (deriver != "") info.deriver = store.parseStorePath(deriver);
-    string s;
+    std::string s;
     getline(str, s);
     auto n = string2Int<int>(s);
     if (!n) throw Error("number expected");
@@ -1168,7 +1176,7 @@ std::string Store::showPaths(const StorePathSet & paths)
 }
 
 
-string showPaths(const PathSet & paths)
+std::string showPaths(const PathSet & paths)
 {
     return concatStringsSep(", ", quoteStrings(paths));
 }
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 90d2e93ed..e4fb1f1fd 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -352,7 +352,9 @@ public:
        simply yield a different store path, so other users wouldn't be
        affected), but it has some backwards compatibility issues (the
        hashing scheme changes), so I'm not doing that for now. */
-    StorePath computeStorePathForText(const string & name, const string & s,
+    StorePath computeStorePathForText(
+        std::string_view name,
+        std::string_view s,
         const StorePathSet & references) const;
 
     /* Check whether a path is valid. */
@@ -482,9 +484,14 @@ public:
        validity the resulting path.  The resulting path is returned.
        The function object `filter' can be used to exclude files (see
        libutil/archive.hh). */
-    virtual StorePath addToStore(const string & name, const Path & srcPath,
-        FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256,
-        PathFilter & filter = defaultPathFilter, RepairFlag repair = NoRepair, const StorePathSet & references = StorePathSet());
+    virtual StorePath addToStore(
+        std::string_view name,
+        const Path & srcPath,
+        FileIngestionMethod method = FileIngestionMethod::Recursive,
+        HashType hashAlgo = htSHA256,
+        PathFilter & filter = defaultPathFilter,
+        RepairFlag repair = NoRepair,
+        const StorePathSet & references = StorePathSet());
 
     /* Copy the contents of a path to the store and register the
        validity the resulting path, using a constant amount of
@@ -506,8 +513,11 @@ public:
 
     /* Like addToStore, but the contents written to the output path is
        a regular file containing the given string. */
-    virtual StorePath addTextToStore(const string & name, const string & s,
-        const StorePathSet & references, RepairFlag repair = NoRepair) = 0;
+    virtual StorePath addTextToStore(
+        std::string_view name,
+        std::string_view s,
+        const StorePathSet & references,
+        RepairFlag repair = NoRepair) = 0;
 
     /**
      * Add a mapping indicating that `deriver!outputName` maps to the output path
@@ -608,7 +618,7 @@ public:
     /* Return a string representing information about the path that
        can be loaded into the database using `nix-store --load-db' or
        `nix-store --register-validity'. */
-    string makeValidityRegistration(const StorePathSet & paths,
+    std::string makeValidityRegistration(const StorePathSet & paths,
         bool showDerivers, bool showHash);
 
     /* Write a JSON representation of store path metadata, such as the
@@ -910,7 +920,7 @@ struct RegisterStoreImplementation
 
 /* Display a set of paths in human-readable form (i.e., between quotes
    and separated by commas). */
-string showPaths(const PathSet & paths);
+std::string showPaths(const PathSet & paths);
 
 
 std::optional<ValidPathInfo> decodeValidPathInfo(
diff --git a/src/libutil/archive.cc b/src/libutil/archive.cc
index fdee643b1..eda004756 100644
--- a/src/libutil/archive.cc
+++ b/src/libutil/archive.cc
@@ -37,7 +37,7 @@ static GlobalConfig::Register rArchiveSettings(&archiveSettings);
 
 const std::string narVersionMagic1 = "nix-archive-1";
 
-static string caseHackSuffix = "~nix~case~hack~";
+static std::string caseHackSuffix = "~nix~case~hack~";
 
 PathFilter defaultPathFilter = [](const Path &) { return true; };
 
@@ -84,12 +84,12 @@ static void dump(const Path & path, Sink & sink, PathFilter & filter)
 
         /* If we're on a case-insensitive system like macOS, undo
            the case hack applied by restorePath(). */
-        std::map<string, string> unhacked;
+        std::map<std::string, std::string> unhacked;
         for (auto & i : readDirectory(path))
             if (archiveSettings.useCaseHack) {
-                string name(i.name);
+                std::string name(i.name);
                 size_t pos = i.name.find(caseHackSuffix);
-                if (pos != string::npos) {
+                if (pos != std::string::npos) {
                     debug(format("removing case hack suffix from '%1%'") % (path + "/" + i.name));
                     name.erase(pos);
                 }
@@ -124,13 +124,13 @@ void dumpPath(const Path & path, Sink & sink, PathFilter & filter)
 }
 
 
-void dumpString(const std::string & s, Sink & sink)
+void dumpString(std::string_view s, Sink & sink)
 {
     sink << narVersionMagic1 << "(" << "type" << "regular" << "contents" << s << ")";
 }
 
 
-static SerialisationError badArchive(string s)
+static SerialisationError badArchive(const std::string & s)
 {
     return SerialisationError("bad archive: " + s);
 }
@@ -171,7 +171,7 @@ static void parseContents(ParseSink & sink, Source & source, const Path & path)
 
 struct CaseInsensitiveCompare
 {
-    bool operator() (const string & a, const string & b) const
+    bool operator() (const std::string & a, const std::string & b) const
     {
         return strcasecmp(a.c_str(), b.c_str()) < 0;
     }
@@ -180,7 +180,7 @@ struct CaseInsensitiveCompare
 
 static void parse(ParseSink & sink, Source & source, const Path & path)
 {
-    string s;
+    std::string s;
 
     s = readString(source);
     if (s != "(") throw badArchive("expected open tag");
@@ -201,7 +201,7 @@ static void parse(ParseSink & sink, Source & source, const Path & path)
         else if (s == "type") {
             if (type != tpUnknown)
                 throw badArchive("multiple type fields");
-            string t = readString(source);
+            std::string t = readString(source);
 
             if (t == "regular") {
                 type = tpRegular;
@@ -232,7 +232,7 @@ static void parse(ParseSink & sink, Source & source, const Path & path)
         }
 
         else if (s == "entry" && type == tpDirectory) {
-            string name, prevName;
+            std::string name, prevName;
 
             s = readString(source);
             if (s != "(") throw badArchive("expected open tag");
@@ -246,7 +246,7 @@ static void parse(ParseSink & sink, Source & source, const Path & path)
                     break;
                 } else if (s == "name") {
                     name = readString(source);
-                    if (name.empty() || name == "." || name == ".." || name.find('/') != string::npos || name.find((char) 0) != string::npos)
+                    if (name.empty() || name == "." || name == ".." || name.find('/') != std::string::npos || name.find((char) 0) != std::string::npos)
                         throw Error("NAR contains invalid file name '%1%'", name);
                     if (name <= prevName)
                         throw Error("NAR directory is not sorted");
@@ -269,7 +269,7 @@ static void parse(ParseSink & sink, Source & source, const Path & path)
         }
 
         else if (s == "target" && type == tpSymlink) {
-            string target = readString(source);
+            std::string target = readString(source);
             sink.createSymlink(path, target);
         }
 
@@ -281,7 +281,7 @@ static void parse(ParseSink & sink, Source & source, const Path & path)
 
 void parseDump(ParseSink & sink, Source & source)
 {
-    string version;
+    std::string version;
     try {
         version = readString(source, narVersionMagic1.size());
     } catch (SerialisationError & e) {
@@ -345,7 +345,7 @@ struct RestoreSink : ParseSink
         writeFull(fd.get(), data);
     }
 
-    void createSymlink(const Path & path, const string & target) override
+    void createSymlink(const Path & path, const std::string & target) override
     {
         Path p = dstPath + path;
         nix::createSymlink(target, p);
diff --git a/src/libutil/archive.hh b/src/libutil/archive.hh
index 9e9e11b1a..fca351605 100644
--- a/src/libutil/archive.hh
+++ b/src/libutil/archive.hh
@@ -48,7 +48,7 @@ namespace nix {
 void dumpPath(const Path & path, Sink & sink,
     PathFilter & filter = defaultPathFilter);
 
-void dumpString(const std::string & s, Sink & sink);
+void dumpString(std::string_view s, Sink & sink);
 
 /* FIXME: fix this API, it sucks. */
 struct ParseSink
@@ -60,7 +60,7 @@ struct ParseSink
     virtual void preallocateContents(uint64_t size) { };
     virtual void receiveContents(std::string_view data) { };
 
-    virtual void createSymlink(const Path & path, const string & target) { };
+    virtual void createSymlink(const Path & path, const std::string & target) { };
 };
 
 /* If the NAR archive contains a single file at top-level, then save
@@ -82,7 +82,7 @@ struct RetrieveRegularNARSink : ParseSink
         sink(data);
     }
 
-    void createSymlink(const Path & path, const string & target) override
+    void createSymlink(const Path & path, const std::string & target) override
     {
         regular = false;
     }
diff --git a/src/libutil/args.cc b/src/libutil/args.cc
index a739d6b4e..f970c0e9e 100644
--- a/src/libutil/args.cc
+++ b/src/libutil/args.cc
@@ -76,13 +76,13 @@ void Args::parseCmdline(const Strings & _cmdline)
         /* Expand compound dash options (i.e., `-qlf' -> `-q -l -f',
            `-j3` -> `-j 3`). */
         if (!dashDash && arg.length() > 2 && arg[0] == '-' && arg[1] != '-' && isalpha(arg[1])) {
-            *pos = (string) "-" + arg[1];
+            *pos = (std::string) "-" + arg[1];
             auto next = pos; ++next;
             for (unsigned int j = 2; j < arg.length(); j++)
                 if (isalpha(arg[j]))
-                    cmdline.insert(next, (string) "-" + arg[j]);
+                    cmdline.insert(next, (std::string) "-" + arg[j]);
                 else {
-                    cmdline.insert(next, string(arg, j));
+                    cmdline.insert(next, std::string(arg, j));
                     break;
                 }
             arg = *pos;
@@ -139,7 +139,7 @@ bool Args::processFlag(Strings::iterator & pos, Strings::iterator end)
         return true;
     };
 
-    if (string(*pos, 0, 2) == "--") {
+    if (std::string(*pos, 0, 2) == "--") {
         if (auto prefix = needsCompletion(*pos)) {
             for (auto & [name, flag] : longFlags) {
                 if (!hiddenCategories.count(flag->category)
@@ -147,12 +147,12 @@ bool Args::processFlag(Strings::iterator & pos, Strings::iterator end)
                     completions->add("--" + name, flag->description);
             }
         }
-        auto i = longFlags.find(string(*pos, 2));
+        auto i = longFlags.find(std::string(*pos, 2));
         if (i == longFlags.end()) return false;
         return process("--" + i->first, *i->second);
     }
 
-    if (string(*pos, 0, 1) == "-" && pos->size() == 2) {
+    if (std::string(*pos, 0, 1) == "-" && pos->size() == 2) {
         auto c = (*pos)[1];
         auto i = shortFlags.find(c);
         if (i == shortFlags.end()) return false;
diff --git a/src/libutil/args.hh b/src/libutil/args.hh
index 76b1cfe92..fdd036f9a 100644
--- a/src/libutil/args.hh
+++ b/src/libutil/args.hh
@@ -158,7 +158,7 @@ public:
     }
 
     /* Expect a string argument. */
-    void expectArg(const std::string & label, string * dest, bool optional = false)
+    void expectArg(const std::string & label, std::string * dest, bool optional = false)
     {
         expectArgs({
             .label = label,
diff --git a/src/libutil/config.cc b/src/libutil/config.cc
index 8e05f1765..9bb412b4f 100644
--- a/src/libutil/config.cc
+++ b/src/libutil/config.cc
@@ -81,16 +81,16 @@ void AbstractConfig::applyConfig(const std::string & contents, const std::string
     unsigned int pos = 0;
 
     while (pos < contents.size()) {
-        string line;
+        std::string line;
         while (pos < contents.size() && contents[pos] != '\n')
             line += contents[pos++];
         pos++;
 
-        string::size_type hash = line.find('#');
-        if (hash != string::npos)
-            line = string(line, 0, hash);
+        auto hash = line.find('#');
+        if (hash != std::string::npos)
+            line = std::string(line, 0, hash);
 
-        auto tokens = tokenizeString<std::vector<string>>(line);
+        auto tokens = tokenizeString<std::vector<std::string>>(line);
         if (tokens.empty()) continue;
 
         if (tokens.size() < 2)
@@ -120,7 +120,7 @@ void AbstractConfig::applyConfig(const std::string & contents, const std::string
         if (tokens[1] != "=")
             throw UsageError("illegal configuration line '%1%' in '%2%'", line, path);
 
-        string name = tokens[0];
+        std::string name = tokens[0];
 
         auto i = tokens.begin();
         advance(i, 2);
@@ -132,7 +132,7 @@ void AbstractConfig::applyConfig(const std::string & contents, const std::string
 void AbstractConfig::applyConfigFile(const Path & path)
 {
     try {
-        string contents = readFile(path);
+        std::string contents = readFile(path);
         applyConfig(contents, path);
     } catch (SysError &) { }
 }
diff --git a/src/libutil/error.cc b/src/libutil/error.cc
index dd9678ee7..dcd2f82a5 100644
--- a/src/libutil/error.cc
+++ b/src/libutil/error.cc
@@ -17,7 +17,7 @@ BaseError & BaseError::addTrace(std::optional<ErrPos> e, hintformat hint)
 
 // c++ std::exception descendants must have a 'const char* what()' function.
 // This stringifies the error and caches it for use by what(), or similarly by msg().
-const string & BaseError::calcWhat() const
+const std::string & BaseError::calcWhat() const
 {
     if (what_.has_value())
         return *what_;
@@ -32,14 +32,14 @@ const string & BaseError::calcWhat() const
     }
 }
 
-std::optional<string> ErrorInfo::programName = std::nullopt;
+std::optional<std::string> ErrorInfo::programName = std::nullopt;
 
 std::ostream & operator<<(std::ostream & os, const hintformat & hf)
 {
     return os << hf.str();
 }
 
-string showErrPos(const ErrPos & errPos)
+std::string showErrPos(const ErrPos & errPos)
 {
     if (errPos.line > 0) {
         if (errPos.column > 0) {
@@ -68,7 +68,7 @@ std::optional<LinesOfCode> getCodeLines(const ErrPos & errPos)
 
             // count the newlines.
             int count = 0;
-            string line;
+            std::string line;
             int pl = errPos.line - 1;
             do
             {
@@ -100,7 +100,7 @@ std::optional<LinesOfCode> getCodeLines(const ErrPos & errPos)
         std::istringstream iss(errPos.file);
         // count the newlines.
         int count = 0;
-        string line;
+        std::string line;
         int pl = errPos.line - 1;
 
         LinesOfCode loc;
@@ -132,7 +132,7 @@ std::optional<LinesOfCode> getCodeLines(const ErrPos & errPos)
 
 // print lines of code to the ostream, indicating the error column.
 void printCodeLines(std::ostream & out,
-    const string & prefix,
+    const std::string & prefix,
     const ErrPos & errPos,
     const LinesOfCode & loc)
 {
diff --git a/src/libutil/error.hh b/src/libutil/error.hh
index 6fe5e4857..d55e1d701 100644
--- a/src/libutil/error.hh
+++ b/src/libutil/error.hh
@@ -61,16 +61,16 @@ typedef enum {
 
 // the lines of code surrounding an error.
 struct LinesOfCode {
-    std::optional<string> prevLineOfCode;
-    std::optional<string> errLineOfCode;
-    std::optional<string> nextLineOfCode;
+    std::optional<std::string> prevLineOfCode;
+    std::optional<std::string> errLineOfCode;
+    std::optional<std::string> nextLineOfCode;
 };
 
 // ErrPos indicates the location of an error in a nix file.
 struct ErrPos {
     int line = 0;
     int column = 0;
-    string file;
+    std::string file;
     FileOrigin origin;
 
     operator bool() const
@@ -80,7 +80,7 @@ struct ErrPos {
 
     // convert from the Pos struct, found in libexpr.
     template <class P>
-    ErrPos& operator=(const P &pos)
+    ErrPos & operator=(const P & pos)
     {
         origin = pos.origin;
         line = pos.line;
@@ -94,7 +94,7 @@ struct ErrPos {
     }
 
     template <class P>
-    ErrPos(const P &p)
+    ErrPos(const P & p)
     {
         *this = p;
     }
@@ -107,15 +107,15 @@ struct Trace {
 
 struct ErrorInfo {
     Verbosity level;
-    string name; // FIXME: rename
+    std::string name; // FIXME: rename
     hintformat msg;
     std::optional<ErrPos> errPos;
     std::list<Trace> traces;
 
-    static std::optional<string> programName;
+    static std::optional<std::string> programName;
 };
 
-std::ostream& showErrorInfo(std::ostream &out, const ErrorInfo &einfo, bool showTrace);
+std::ostream & showErrorInfo(std::ostream & out, const ErrorInfo & einfo, bool showTrace);
 
 /* BaseError should generally not be caught, as it has Interrupted as
    a subclass. Catch Error instead. */
@@ -124,8 +124,8 @@ class BaseError : public std::exception
 protected:
     mutable ErrorInfo err;
 
-    mutable std::optional<string> what_;
-    const string& calcWhat() const;
+    mutable std::optional<std::string> what_;
+    const std::string & calcWhat() const;
 
 public:
     unsigned int status = 1; // exit status
@@ -162,11 +162,11 @@ public:
     const char * what() const noexcept override { return calcWhat().c_str(); }
 #endif
 
-    const string & msg() const { return calcWhat(); }
+    const std::string & msg() const { return calcWhat(); }
     const ErrorInfo & info() const { calcWhat(); return err; }
 
     template<typename... Args>
-    BaseError & addTrace(std::optional<ErrPos> e, const string &fs, const Args & ... args)
+    BaseError & addTrace(std::optional<ErrPos> e, const std::string & fs, const Args & ... args)
     {
         return addTrace(e, hintfmt(fs, args...));
     }
diff --git a/src/libutil/fmt.hh b/src/libutil/fmt.hh
index a7126fb65..0821b3b74 100644
--- a/src/libutil/fmt.hh
+++ b/src/libutil/fmt.hh
@@ -10,7 +10,6 @@ namespace nix {
 
 
 /* Inherit some names from other namespaces for convenience. */
-using std::string;
 using boost::format;
 
 
@@ -21,8 +20,8 @@ struct nop { template<typename... T> nop(T...) {} };
 
 struct FormatOrString
 {
-    string s;
-    FormatOrString(const string & s) : s(s) { };
+    std::string s;
+    FormatOrString(std::string s) : s(std::move(s)) { };
     template<class F>
     FormatOrString(const F & f) : s(f.str()) { };
     FormatOrString(const char * s) : s(s) { };
@@ -102,7 +101,7 @@ std::ostream & operator<<(std::ostream & out, const normaltxt<T> & y)
 class hintformat
 {
 public:
-    hintformat(const string & format) : fmt(format)
+    hintformat(const std::string & format) : fmt(format)
     {
         fmt.exceptions(boost::io::all_error_bits ^
                        boost::io::too_many_args_bit ^
diff --git a/src/libutil/hash.cc b/src/libutil/hash.cc
index 6ed00d43c..a4d632161 100644
--- a/src/libutil/hash.cc
+++ b/src/libutil/hash.cc
@@ -66,31 +66,31 @@ bool Hash::operator < (const Hash & h) const
 }
 
 
-const string base16Chars = "0123456789abcdef";
+const std::string base16Chars = "0123456789abcdef";
 
 
-static string printHash16(const Hash & hash)
+static std::string printHash16(const Hash & hash)
 {
     char buf[hash.hashSize * 2];
     for (unsigned int i = 0; i < hash.hashSize; i++) {
         buf[i * 2] = base16Chars[hash.hash[i] >> 4];
         buf[i * 2 + 1] = base16Chars[hash.hash[i] & 0x0f];
     }
-    return string(buf, hash.hashSize * 2);
+    return std::string(buf, hash.hashSize * 2);
 }
 
 
 // omitted: E O U T
-const string base32Chars = "0123456789abcdfghijklmnpqrsvwxyz";
+const std::string base32Chars = "0123456789abcdfghijklmnpqrsvwxyz";
 
 
-static string printHash32(const Hash & hash)
+static std::string printHash32(const Hash & hash)
 {
     assert(hash.hashSize);
     size_t len = hash.base32Len();
     assert(len);
 
-    string s;
+    std::string s;
     s.reserve(len);
 
     for (int n = (int) len - 1; n >= 0; n--) {
@@ -107,7 +107,7 @@ static string printHash32(const Hash & hash)
 }
 
 
-string printHash16or32(const Hash & hash)
+std::string printHash16or32(const Hash & hash)
 {
     assert(hash.type);
     return hash.to_string(hash.type == htMD5 ? Base16 : Base32, false);
@@ -151,7 +151,8 @@ Hash Hash::parseSRI(std::string_view original) {
 }
 
 // Mutates the string to eliminate the prefixes when found
-static std::pair<std::optional<HashType>, bool> getParsedTypeAndSRI(std::string_view & rest) {
+static std::pair<std::optional<HashType>, bool> getParsedTypeAndSRI(std::string_view & rest)
+{
     bool isSRI = false;
 
     // Parse the has type before the separater, if there was one.
@@ -402,7 +403,7 @@ HashType parseHashType(std::string_view s)
         throw UsageError("unknown hash algorithm '%1%'", s);
 }
 
-string printHashType(HashType ht)
+std::string printHashType(HashType ht)
 {
     switch (ht) {
     case htMD5: return "md5";
diff --git a/src/libutil/hash.hh b/src/libutil/hash.hh
index dff46542f..56b5938b3 100644
--- a/src/libutil/hash.hh
+++ b/src/libutil/hash.hh
@@ -20,7 +20,7 @@ const int sha512HashSize = 64;
 
 extern std::set<std::string> hashTypes;
 
-extern const string base32Chars;
+extern const std::string base32Chars;
 
 enum Base : int { Base64, Base32, Base16, SRI };
 
@@ -110,7 +110,7 @@ public:
 Hash newHashAllowEmpty(std::string_view hashStr, std::optional<HashType> ht);
 
 /* Print a hash in base-16 if it's MD5, or base-32 otherwise. */
-string printHash16or32(const Hash & hash);
+std::string printHash16or32(const Hash & hash);
 
 /* Compute the hash of the given string. */
 Hash hashString(HashType ht, std::string_view s);
@@ -135,7 +135,7 @@ HashType parseHashType(std::string_view s);
 std::optional<HashType> parseHashTypeOpt(std::string_view s);
 
 /* And the reverse. */
-string printHashType(HashType ht);
+std::string printHashType(HashType ht);
 
 
 union Ctx;
diff --git a/src/libutil/logging.cc b/src/libutil/logging.cc
index f8a121ed1..74ee2f063 100644
--- a/src/libutil/logging.cc
+++ b/src/libutil/logging.cc
@@ -113,7 +113,7 @@ void warnOnce(bool & haveWarned, const FormatOrString & fs)
     }
 }
 
-void writeToStderr(const string & s)
+void writeToStderr(std::string_view s)
 {
     try {
         writeFull(STDERR_FILENO, s, false);
diff --git a/src/libutil/logging.hh b/src/libutil/logging.hh
index 5560d2bed..bd28036ae 100644
--- a/src/libutil/logging.hh
+++ b/src/libutil/logging.hh
@@ -216,6 +216,6 @@ inline void warn(const std::string & fs, const Args & ... args)
 
 void warnOnce(bool & haveWarned, const FormatOrString & fs);
 
-void writeToStderr(const string & s);
+void writeToStderr(std::string_view s);
 
 }
diff --git a/src/libutil/serialise.cc b/src/libutil/serialise.cc
index fe703de06..6445b3f1b 100644
--- a/src/libutil/serialise.cc
+++ b/src/libutil/serialise.cc
@@ -391,7 +391,7 @@ size_t readString(char * buf, size_t max, Source & source)
 }
 
 
-string readString(Source & source, size_t max)
+std::string readString(Source & source, size_t max)
 {
     auto len = readNum<size_t>(source);
     if (len > max) throw SerialisationError("string is too long");
@@ -401,7 +401,7 @@ string readString(Source & source, size_t max)
     return res;
 }
 
-Source & operator >> (Source & in, string & s)
+Source & operator >> (Source & in, std::string & s)
 {
     s = readString(in);
     return in;
diff --git a/src/libutil/serialise.hh b/src/libutil/serialise.hh
index fdd35aa00..13da26c6a 100644
--- a/src/libutil/serialise.hh
+++ b/src/libutil/serialise.hh
@@ -364,10 +364,10 @@ inline uint64_t readLongLong(Source & source)
 
 void readPadding(size_t len, Source & source);
 size_t readString(char * buf, size_t max, Source & source);
-string readString(Source & source, size_t max = std::numeric_limits<size_t>::max());
+std::string readString(Source & source, size_t max = std::numeric_limits<size_t>::max());
 template<class T> T readStrings(Source & source);
 
-Source & operator >> (Source & in, string & s);
+Source & operator >> (Source & in, std::string & s);
 
 template<typename T>
 Source & operator >> (Source & in, T & n)
diff --git a/src/libutil/tests/url.cc b/src/libutil/tests/url.cc
index aff58e9ee..f20e2dc41 100644
--- a/src/libutil/tests/url.cc
+++ b/src/libutil/tests/url.cc
@@ -5,9 +5,9 @@ namespace nix {
 
 /* ----------- tests for url.hh --------------------------------------------------*/
 
-    string print_map(std::map<string, string> m) {
-        std::map<string, string>::iterator it;
-        string s = "{ ";
+    std::string print_map(std::map<std::string, std::string> m) {
+        std::map<std::string, std::string>::iterator it;
+        std::string s = "{ ";
         for (it = m.begin(); it != m.end(); ++it) {
             s += "{ ";
             s += it->first;
@@ -262,21 +262,21 @@ namespace nix {
      * --------------------------------------------------------------------------*/
 
     TEST(percentDecode, decodesUrlEncodedString) {
-        string s = "==@==";
-        string d = percentDecode("%3D%3D%40%3D%3D");
+        std::string s = "==@==";
+        std::string d = percentDecode("%3D%3D%40%3D%3D");
         ASSERT_EQ(d, s);
     }
 
     TEST(percentDecode, multipleDecodesAreIdempotent) {
-        string once = percentDecode("%3D%3D%40%3D%3D");
-        string twice = percentDecode(once);
+        std::string once = percentDecode("%3D%3D%40%3D%3D");
+        std::string twice = percentDecode(once);
 
         ASSERT_EQ(once, twice);
     }
 
     TEST(percentDecode, trailingPercent) {
-        string s = "==@==%";
-        string d = percentDecode("%3D%3D%40%3D%3D%25");
+        std::string s = "==@==%";
+        std::string d = percentDecode("%3D%3D%40%3D%3D%25");
 
         ASSERT_EQ(d, s);
     }
diff --git a/src/libutil/types.hh b/src/libutil/types.hh
index bea2673ca..00ba567c6 100644
--- a/src/libutil/types.hh
+++ b/src/libutil/types.hh
@@ -14,6 +14,7 @@ namespace nix {
 typedef std::list<std::string> Strings;
 typedef std::set<std::string> StringSet;
 typedef std::map<std::string, std::string> StringMap;
+typedef std::map<std::string, std::string> StringPairs;
 
 /* Paths are just strings. */
 typedef std::string Path;
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index b172e0554..88c5ae806 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -110,13 +110,13 @@ Path canonPath(PathView path, bool resolveSymlinks)
 {
     assert(path != "");
 
-    string s;
+    std::string s;
     s.reserve(256);
 
     if (path[0] != '/')
         throw Error("not an absolute path: '%1%'", path);
 
-    string temp;
+    std::string temp;
 
     /* Count the number of times we follow a symlink and stop at some
        arbitrary (but high) limit to prevent infinite loops. */
@@ -142,7 +142,7 @@ Path canonPath(PathView path, bool resolveSymlinks)
         /* Normal component; copy it. */
         else {
             s += '/';
-            if (const auto slash = path.find('/'); slash == string::npos) {
+            if (const auto slash = path.find('/'); slash == std::string::npos) {
                 s += path;
                 path = {};
             } else {
@@ -175,7 +175,7 @@ Path canonPath(PathView path, bool resolveSymlinks)
 Path dirOf(const PathView path)
 {
     Path::size_type pos = path.rfind('/');
-    if (pos == string::npos)
+    if (pos == std::string::npos)
         return ".";
     return pos == 0 ? "/" : Path(path, 0, pos);
 }
@@ -191,7 +191,7 @@ std::string_view baseNameOf(std::string_view path)
         last -= 1;
 
     auto pos = path.rfind('/', last);
-    if (pos == string::npos)
+    if (pos == std::string::npos)
         pos = 0;
     else
         pos += 1;
@@ -249,7 +249,7 @@ Path readLink(const Path & path)
             else
                 throw SysError("reading symbolic link '%1%'", path);
         else if (rlSize < bufSize)
-            return string(buf.data(), rlSize);
+            return std::string(buf.data(), rlSize);
     }
 }
 
@@ -269,7 +269,7 @@ DirEntries readDirectory(DIR *dir, const Path & path)
     struct dirent * dirent;
     while (errno = 0, dirent = readdir(dir)) { /* sic */
         checkInterrupt();
-        string name = dirent->d_name;
+        std::string name = dirent->d_name;
         if (name == "." || name == "..") continue;
         entries.emplace_back(name, dirent->d_ino,
 #ifdef HAVE_STRUCT_DIRENT_D_TYPE
@@ -303,7 +303,7 @@ unsigned char getFileType(const Path & path)
 }
 
 
-string readFile(int fd)
+std::string readFile(int fd)
 {
     struct stat st;
     if (fstat(fd, &st) == -1)
@@ -313,7 +313,7 @@ string readFile(int fd)
 }
 
 
-string readFile(const Path & path)
+std::string readFile(const Path & path)
 {
     AutoCloseFD fd = open(path.c_str(), O_RDONLY | O_CLOEXEC);
     if (!fd)
@@ -366,9 +366,9 @@ void writeFile(const Path & path, Source & source, mode_t mode)
     }
 }
 
-string readLine(int fd)
+std::string readLine(int fd)
 {
-    string s;
+    std::string s;
     while (1) {
         checkInterrupt();
         char ch;
@@ -387,7 +387,7 @@ string readLine(int fd)
 }
 
 
-void writeLine(int fd, string s)
+void writeLine(int fd, std::string s)
 {
     s += '\n';
     writeFull(fd, s);
@@ -398,7 +398,7 @@ static void _deletePath(int parentfd, const Path & path, uint64_t & bytesFreed)
 {
     checkInterrupt();
 
-    string name(baseNameOf(path));
+    std::string name(baseNameOf(path));
 
     struct stat st;
     if (fstatat(parentfd, name.c_str(), &st, AT_SYMLINK_NOFOLLOW) == -1) {
@@ -566,8 +566,8 @@ Path getConfigDir()
 std::vector<Path> getConfigDirs()
 {
     Path configHome = getConfigDir();
-    string configDirs = getEnv("XDG_CONFIG_DIRS").value_or("/etc/xdg");
-    std::vector<Path> result = tokenizeString<std::vector<string>>(configDirs, ":");
+    auto configDirs = getEnv("XDG_CONFIG_DIRS").value_or("/etc/xdg");
+    std::vector<Path> result = tokenizeString<std::vector<std::string>>(configDirs, ":");
     result.insert(result.begin(), configHome);
     return result;
 }
@@ -670,7 +670,7 @@ void writeFull(int fd, std::string_view s, bool allowInterrupts)
 }
 
 
-string drainFD(int fd, bool block, const size_t reserveSize)
+std::string drainFD(int fd, bool block, const size_t reserveSize)
 {
     // the parser needs two extra bytes to append terminating characters, other users will
     // not care very much about the extra memory.
@@ -719,7 +719,7 @@ void drainFD(int fd, Sink & sink, bool block)
 
 AutoDelete::AutoDelete() : del{false} {}
 
-AutoDelete::AutoDelete(const string & p, bool recursive) : path(p)
+AutoDelete::AutoDelete(const std::string & p, bool recursive) : path(p)
 {
     del = true;
     this->recursive = recursive;
@@ -1036,7 +1036,7 @@ std::vector<char *> stringsToCharPtrs(const Strings & ss)
     return res;
 }
 
-string runProgram(Path program, bool searchPath, const Strings & args,
+std::string runProgram(Path program, bool searchPath, const Strings & args,
     const std::optional<std::string> & input)
 {
     auto res = runProgram(RunOptions {.program = program, .searchPath = searchPath, .args = args, .input = input});
@@ -1238,11 +1238,11 @@ void _interrupted()
 template<class C> C tokenizeString(std::string_view s, std::string_view separators)
 {
     C result;
-    string::size_type pos = s.find_first_not_of(separators, 0);
-    while (pos != string::npos) {
-        string::size_type end = s.find_first_of(separators, pos + 1);
-        if (end == string::npos) end = s.size();
-        result.insert(result.end(), string(s, pos, end - pos));
+    auto pos = s.find_first_not_of(separators, 0);
+    while (pos != std::string::npos) {
+        auto end = s.find_first_of(separators, pos + 1);
+        if (end == std::string::npos) end = s.size();
+        result.insert(result.end(), std::string(s, pos, end - pos));
         pos = s.find_first_not_of(separators, end);
     }
     return result;
@@ -1250,29 +1250,30 @@ template<class C> C tokenizeString(std::string_view s, std::string_view separato
 
 template Strings tokenizeString(std::string_view s, std::string_view separators);
 template StringSet tokenizeString(std::string_view s, std::string_view separators);
-template std::vector<string> tokenizeString(std::string_view s, std::string_view separators);
+template std::vector<std::string> tokenizeString(std::string_view s, std::string_view separators);
 
 
-string chomp(std::string_view s)
+std::string chomp(std::string_view s)
 {
     size_t i = s.find_last_not_of(" \n\r\t");
-    return i == string::npos ? "" : string(s, 0, i + 1);
+    return i == std::string_view::npos ? "" : std::string(s, 0, i + 1);
 }
 
 
-string trim(const string & s, const string & whitespace)
+std::string trim(std::string_view s, std::string_view whitespace)
 {
     auto i = s.find_first_not_of(whitespace);
-    if (i == string::npos) return "";
+    if (i == std::string_view::npos) return "";
     auto j = s.find_last_not_of(whitespace);
-    return string(s, i, j == string::npos ? j : j - i + 1);
+    return std::string(s, i, j == std::string::npos ? j : j - i + 1);
 }
 
 
-string replaceStrings(std::string_view s,
-    const std::string & from, const std::string & to)
+std::string replaceStrings(
+    std::string res,
+    std::string_view from,
+    std::string_view to)
 {
-    string res(s);
     if (from.empty()) return res;
     size_t pos = 0;
     while ((pos = res.find(from, pos)) != std::string::npos) {
@@ -1283,20 +1284,19 @@ string replaceStrings(std::string_view s,
 }
 
 
-std::string rewriteStrings(const std::string & _s, const StringMap & rewrites)
+std::string rewriteStrings(std::string s, const StringMap & rewrites)
 {
-    auto s = _s;
     for (auto & i : rewrites) {
         if (i.first == i.second) continue;
         size_t j = 0;
-        while ((j = s.find(i.first, j)) != string::npos)
+        while ((j = s.find(i.first, j)) != std::string::npos)
             s.replace(j, i.first.size(), i.second);
     }
     return s;
 }
 
 
-string statusToString(int status)
+std::string statusToString(int status)
 {
     if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
         if (WIFEXITED(status))
@@ -1448,9 +1448,9 @@ std::string filterANSIEscapes(const std::string & s, bool filterAll, unsigned in
 
 constexpr char base64Chars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 
-string base64Encode(std::string_view s)
+std::string base64Encode(std::string_view s)
 {
-    string res;
+    std::string res;
     int data = 0, nbits = 0;
 
     for (char c : s) {
@@ -1469,7 +1469,7 @@ string base64Encode(std::string_view s)
 }
 
 
-string base64Decode(std::string_view s)
+std::string base64Decode(std::string_view s)
 {
     constexpr char npos = -1;
     constexpr std::array<char, 256> base64DecodeChars = [&]() {
@@ -1481,7 +1481,7 @@ string base64Decode(std::string_view s)
         return result;
     }();
 
-    string res;
+    std::string res;
     unsigned int d = 0, bits = 0;
 
     for (char c : s) {
@@ -1835,7 +1835,7 @@ void connect(int fd, const std::string & path)
 }
 
 
-string showBytes(uint64_t bytes)
+std::string showBytes(uint64_t bytes)
 {
     return fmt("%.2f MiB", bytes / (1024.0 * 1024.0));
 }
@@ -1846,7 +1846,7 @@ void commonChildInit(Pipe & logPipe)
 {
     logger = makeSimpleLogger();
 
-    const static string pathNullDevice = "/dev/null";
+    const static std::string pathNullDevice = "/dev/null";
     restoreProcessContext(false);
 
     /* Put the child in a separate session (and thus a separate
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index a949e6424..20591952d 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -92,11 +92,11 @@ bool isLink(const Path & path);
    removed. */
 struct DirEntry
 {
-    string name;
+    std::string name;
     ino_t ino;
     unsigned char type; // one of DT_*
-    DirEntry(const string & name, ino_t ino, unsigned char type)
-        : name(name), ino(ino), type(type) { }
+    DirEntry(std::string name, ino_t ino, unsigned char type)
+        : name(std::move(name)), ino(ino), type(type) { }
 };
 
 typedef std::vector<DirEntry> DirEntries;
@@ -106,8 +106,8 @@ DirEntries readDirectory(const Path & path);
 unsigned char getFileType(const Path & path);
 
 /* Read the contents of a file into a string. */
-string readFile(int fd);
-string readFile(const Path & path);
+std::string readFile(int fd);
+std::string readFile(const Path & path);
 void readFile(const Path & path, Sink & sink);
 
 /* Write a string to a file. */
@@ -116,10 +116,10 @@ void writeFile(const Path & path, std::string_view s, mode_t mode = 0666);
 void writeFile(const Path & path, Source & source, mode_t mode = 0666);
 
 /* Read a line from a file descriptor. */
-string readLine(int fd);
+std::string readLine(int fd);
 
 /* Write a line to a file descriptor. */
-void writeLine(int fd, string s);
+void writeLine(int fd, std::string s);
 
 /* Delete a path; i.e., in the case of a directory, it is deleted
    recursively. It's not an error if the path does not exist. The
@@ -170,7 +170,7 @@ MakeError(EndOfFile, Error);
 
 
 /* Read a file descriptor until EOF occurs. */
-string drainFD(int fd, bool block = true, const size_t reserveSize=0);
+std::string drainFD(int fd, bool block = true, const size_t reserveSize=0);
 
 void drainFD(int fd, Sink & sink, bool block = true);
 
@@ -268,7 +268,7 @@ void killUser(uid_t uid);
    pid to the caller. */
 struct ProcessOptions
 {
-    string errorPrefix = "";
+    std::string errorPrefix = "";
     bool dieWithParent = true;
     bool runExitHandlers = false;
     bool allowVfork = false;
@@ -279,7 +279,7 @@ pid_t startProcess(std::function<void()> fun, const ProcessOptions & options = P
 
 /* Run a program and return its stdout in a string (i.e., like the
    shell backtick operator). */
-string runProgram(Path program, bool searchPath = false,
+std::string runProgram(Path program, bool searchPath = false,
     const Strings & args = Strings(),
     const std::optional<std::string> & input = {});
 
@@ -378,12 +378,12 @@ template<class C> C tokenizeString(std::string_view s, std::string_view separato
 /* Concatenate the given strings with a separator between the
    elements. */
 template<class C>
-string concatStringsSep(const std::string_view sep, const C & ss)
+std::string concatStringsSep(const std::string_view sep, const C & ss)
 {
     size_t size = 0;
     // need a cast to string_view since this is also called with Symbols
     for (const auto & s : ss) size += sep.size() + std::string_view(s).size();
-    string s;
+    std::string s;
     s.reserve(size);
     for (auto & i : ss) {
         if (s.size() != 0) s += sep;
@@ -394,7 +394,7 @@ string concatStringsSep(const std::string_view sep, const C & ss)
 
 template<class ... Parts>
 auto concatStrings(Parts && ... parts)
-    -> std::enable_if_t<(... && std::is_convertible_v<Parts, std::string_view>), string>
+    -> std::enable_if_t<(... && std::is_convertible_v<Parts, std::string_view>), std::string>
 {
     std::string_view views[sizeof...(parts)] = { parts... };
     return concatStringsSep({}, views);
@@ -413,24 +413,26 @@ template<class C> Strings quoteStrings(const C & c)
 
 /* Remove trailing whitespace from a string. FIXME: return
    std::string_view. */
-string chomp(std::string_view s);
+std::string chomp(std::string_view s);
 
 
 /* Remove whitespace from the start and end of a string. */
-string trim(const string & s, const string & whitespace = " \n\r\t");
+std::string trim(std::string_view s, std::string_view whitespace = " \n\r\t");
 
 
 /* Replace all occurrences of a string inside another string. */
-string replaceStrings(std::string_view s,
-    const std::string & from, const std::string & to);
+std::string replaceStrings(
+    std::string s,
+    std::string_view from,
+    std::string_view to);
 
 
-std::string rewriteStrings(const std::string & s, const StringMap & rewrites);
+std::string rewriteStrings(std::string s, const StringMap & rewrites);
 
 
 /* Convert the exit status of a child as returned by wait() into an
    error string. */
-string statusToString(int status);
+std::string statusToString(int status);
 
 bool statusOk(int status);
 
@@ -525,8 +527,8 @@ std::string filterANSIEscapes(const std::string & s,
 
 
 /* Base64 encoding/decoding. */
-string base64Encode(std::string_view s);
-string base64Decode(std::string_view s);
+std::string base64Encode(std::string_view s);
+std::string base64Decode(std::string_view s);
 
 
 /* Remove common leading whitespace from the lines in the string
diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index aeabdcdd4..3d189f934 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -32,11 +32,11 @@ extern char * * environ __attribute__((weak));
 /* Recreate the effect of the perl shellwords function, breaking up a
  * string into arguments like a shell word, including escapes
  */
-std::vector<string> shellwords(const string & s)
+static std::vector<std::string> shellwords(const std::string & s)
 {
     std::regex whitespace("^(\\s+).*");
     auto begin = s.cbegin();
-    std::vector<string> res;
+    std::vector<std::string> res;
     std::string cur;
     enum state {
         sBegin,
@@ -96,14 +96,14 @@ static void main_nix_build(int argc, char * * argv)
 
     auto inShebang = false;
     std::string script;
-    std::vector<string> savedArgs;
+    std::vector<std::string> savedArgs;
 
     AutoDelete tmpDir(createTempDir("", myName));
 
     std::string outLink = "./result";
 
     // List of environment variables kept for --pure
-    std::set<string> keepVars{
+    std::set<std::string> keepVars{
         "HOME", "XDG_RUNTIME_DIR", "USER", "LOGNAME", "DISPLAY",
         "WAYLAND_DISPLAY", "WAYLAND_SOCKET", "PATH", "TERM", "IN_NIX_SHELL",
         "NIX_SHELL_PRESERVE_PROMPT", "TZ", "PAGER", "NIX_BUILD_SHELL", "SHLVL",
@@ -384,7 +384,9 @@ static void main_nix_build(int argc, char * * argv)
         // Build or fetch all dependencies of the derivation.
         for (const auto & input : drv.inputDrvs)
             if (std::all_of(envExclude.cbegin(), envExclude.cend(),
-                    [&](const string & exclude) { return !std::regex_search(store->printStorePath(input.first), std::regex(exclude)); }))
+                    [&](const std::string & exclude) {
+                        return !std::regex_search(store->printStorePath(input.first), std::regex(exclude));
+                    }))
             {
                 pathsToBuild.push_back({input.first, input.second});
                 pathsToCopy.insert(input.first);
@@ -437,7 +439,7 @@ static void main_nix_build(int argc, char * * argv)
         for (auto & var : drv.env)
             if (passAsFile.count(var.first)) {
                 keepTmp = true;
-                string fn = ".attr-" + std::to_string(fileNr++);
+                auto fn = ".attr-" + std::to_string(fileNr++);
                 Path p = (Path) tmpDir + "/" + fn;
                 writeFile(p, var.second);
                 env[var.first + "Path"] = p;
@@ -514,7 +516,7 @@ static void main_nix_build(int argc, char * * argv)
                 (pure ? "" : "PATH=$PATH:$p; unset p; "),
                 shellEscape(dirOf(*shell)),
                 shellEscape(*shell),
-                (getenv("TZ") ? (string("export TZ=") + shellEscape(getenv("TZ")) + "; ") : ""),
+                (getenv("TZ") ? (std::string("export TZ=") + shellEscape(getenv("TZ")) + "; ") : ""),
                 envCommand);
         vomit("Sourcing nix-shell with file %s and contents:\n%s", rcfile, rc);
         writeFile(rcfile, rc);
diff --git a/src/nix-channel/nix-channel.cc b/src/nix-channel/nix-channel.cc
index eae15885a..f46b90b90 100755
--- a/src/nix-channel/nix-channel.cc
+++ b/src/nix-channel/nix-channel.cc
@@ -11,7 +11,7 @@
 
 using namespace nix;
 
-typedef std::map<string,string> Channels;
+typedef std::map<std::string, std::string> Channels;
 
 static Channels channels;
 static Path channelsList;
@@ -22,11 +22,11 @@ static void readChannels()
     if (!pathExists(channelsList)) return;
     auto channelsFile = readFile(channelsList);
 
-    for (const auto & line : tokenizeString<std::vector<string>>(channelsFile, "\n")) {
+    for (const auto & line : tokenizeString<std::vector<std::string>>(channelsFile, "\n")) {
         chomp(line);
         if (std::regex_search(line, std::regex("^\\s*\\#")))
             continue;
-        auto split = tokenizeString<std::vector<string>>(line, " ");
+        auto split = tokenizeString<std::vector<std::string>>(line, " ");
         auto url = std::regex_replace(split[0], std::regex("/*$"), "");
         auto name = split.size() > 1 ? split[1] : std::string(baseNameOf(url));
         channels[name] = url;
@@ -44,7 +44,7 @@ static void writeChannels()
 }
 
 // Adds a channel.
-static void addChannel(const string & url, const string & name)
+static void addChannel(const std::string & url, const std::string & name)
 {
     if (!regex_search(url, std::regex("^(file|http|https)://")))
         throw Error("invalid channel URL '%1%'", url);
@@ -58,7 +58,7 @@ static void addChannel(const string & url, const string & name)
 static Path profile;
 
 // Remove a channel.
-static void removeChannel(const string & name)
+static void removeChannel(const std::string & name)
 {
     readChannels();
     channels.erase(name);
@@ -96,7 +96,7 @@ static void update(const StringSet & channelNames)
         std::smatch match;
         auto urlBase = std::string(baseNameOf(url));
         if (std::regex_search(urlBase, match, std::regex("(-\\d.*)$")))
-            cname = cname + (string) match[1];
+            cname = cname + (std::string) match[1];
 
         std::string extraAttrs;
 
@@ -176,7 +176,7 @@ static int main_nix_channel(int argc, char ** argv)
             cUpdate,
             cRollback
         } cmd = cNone;
-        std::vector<string> args;
+        std::vector<std::string> args;
         parseCmdLine(argc, argv, [&](Strings::iterator & arg, const Strings::iterator & end) {
             if (*arg == "--help") {
                 showManPage("nix-channel");
diff --git a/src/nix-collect-garbage/nix-collect-garbage.cc b/src/nix-collect-garbage/nix-collect-garbage.cc
index 4f953fab4..48c030b18 100644
--- a/src/nix-collect-garbage/nix-collect-garbage.cc
+++ b/src/nix-collect-garbage/nix-collect-garbage.cc
@@ -36,7 +36,7 @@ void removeOldGenerations(std::string dir)
             } catch (SysError & e) {
                 if (e.errNo == ENOENT) continue;
             }
-            if (link.find("link") != string::npos) {
+            if (link.find("link") != std::string::npos) {
                 printInfo(format("removing old generations of profile %1%") % path);
                 if (deleteOlderThan != "")
                     deleteGenerationsOlderThan(path, deleteOlderThan, dryRun);
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index f83edb6a1..12e08bbe1 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -46,7 +46,7 @@ struct InstallSourceInfo
     InstallSourceType type;
     Path nixExprPath; /* for srcNixExprDrvs, srcNixExprs */
     Path profile; /* for srcProfile */
-    string systemFilter; /* for srcNixExprDrvs */
+    std::string systemFilter; /* for srcNixExprDrvs */
     Bindings * autoArgs;
 };
 
@@ -59,7 +59,7 @@ struct Globals
     bool dryRun;
     bool preserveInstalled;
     bool removeAll;
-    string forceName;
+    std::string forceName;
     bool prebuiltOnly;
 };
 
@@ -68,8 +68,8 @@ typedef void (* Operation) (Globals & globals,
     Strings opFlags, Strings opArgs);
 
 
-static string needArg(Strings::iterator & i,
-    Strings & args, const string & arg)
+static std::string needArg(Strings::iterator & i,
+    Strings & args, const std::string & arg)
 {
     if (i == args.end()) throw UsageError("'%1%' requires an argument", arg);
     return *i++;
@@ -77,7 +77,7 @@ static string needArg(Strings::iterator & i,
 
 
 static bool parseInstallSourceOptions(Globals & globals,
-    Strings::iterator & i, Strings & args, const string & arg)
+    Strings::iterator & i, Strings & args, const std::string & arg)
 {
     if (arg == "--from-expression" || arg == "-E")
         globals.instSource.type = srcNixExprs;
@@ -124,9 +124,9 @@ static void getAllExprs(EvalState & state,
                otherwise the attribute cannot be selected with the
                `-A' option.  Useful if you want to stick a Nix
                expression directly in ~/.nix-defexpr. */
-            string attrName = i;
+            std::string attrName = i;
             if (hasSuffix(attrName, ".nix"))
-                attrName = string(attrName, 0, attrName.size() - 4);
+                attrName = std::string(attrName, 0, attrName.size() - 4);
             if (!seen.insert(attrName).second) {
                 printError("warning: name collision in input Nix expressions, skipping '%1%'", path2);
                 continue;
@@ -175,8 +175,8 @@ static void loadSourceExpr(EvalState & state, const Path & path, Value & v)
 
 
 static void loadDerivations(EvalState & state, Path nixExprPath,
-    string systemFilter, Bindings & autoArgs,
-    const string & pathPrefix, DrvInfos & elems)
+    std::string systemFilter, Bindings & autoArgs,
+    const std::string & pathPrefix, DrvInfos & elems)
 {
     Value vRoot;
     loadSourceExpr(state, nixExprPath, vRoot);
@@ -343,9 +343,9 @@ static DrvInfos filterBySelector(EvalState & state, const DrvInfos & allElems,
 
         if (selector.hits == 0 && selector.fullName != "*") {
             const auto prefixHits = searchByPrefix(allElems, selector.name);
-            
+
             if (prefixHits.empty()) {
-                throw Error("selector '%1%' matches no derivations", selector.fullName);    
+                throw Error("selector '%1%' matches no derivations", selector.fullName);
             } else {
                 std::string suggestionMessage = ", maybe you meant:";
                 for (const auto & drvName : prefixHits) {
@@ -360,9 +360,9 @@ static DrvInfos filterBySelector(EvalState & state, const DrvInfos & allElems,
 }
 
 
-static bool isPath(const string & s)
+static bool isPath(std::string_view s)
 {
-    return s.find('/') != string::npos;
+    return s.find('/') != std::string_view::npos;
 }
 
 
@@ -433,8 +433,8 @@ static void queryInstSources(EvalState & state,
                     auto outputs = state.store->queryDerivationOutputMap(path);
                     elem.setOutPath(state.store->printStorePath(outputs.at("out")));
                     if (name.size() >= drvExtension.size() &&
-                        string(name, name.size() - drvExtension.size()) == drvExtension)
-                        name = string(name, 0, name.size() - drvExtension.size());
+                        std::string(name, name.size() - drvExtension.size()) == drvExtension)
+                        name = name.substr(0, name.size() - drvExtension.size());
                 }
                 else elem.setOutPath(state.store->printStorePath(path));
 
@@ -515,7 +515,7 @@ static void installDerivations(Globals & globals,
 
 
     while (true) {
-        string lockToken = optimisticLockProfile(profile);
+        auto lockToken = optimisticLockProfile(profile);
 
         DrvInfos allElems(newElems);
 
@@ -551,7 +551,7 @@ static void installDerivations(Globals & globals,
 static void opInstall(Globals & globals, Strings opFlags, Strings opArgs)
 {
     for (Strings::iterator i = opFlags.begin(); i != opFlags.end(); ) {
-        string arg = *i++;
+        auto arg = *i++;
         if (parseInstallSourceOptions(globals, i, opFlags, arg)) ;
         else if (arg == "--preserve-installed" || arg == "-P")
             globals.preserveInstalled = true;
@@ -578,7 +578,7 @@ static void upgradeDerivations(Globals & globals,
        name and a higher version number. */
 
     while (true) {
-        string lockToken = optimisticLockProfile(globals.profile);
+        auto lockToken = optimisticLockProfile(globals.profile);
 
         DrvInfos installedElems = queryInstalled(*globals.state, globals.profile);
 
@@ -606,7 +606,7 @@ static void upgradeDerivations(Globals & globals,
                    take the one with the highest version.
                    Do not upgrade if it would decrease the priority. */
                 DrvInfos::iterator bestElem = availElems.end();
-                string bestVersion;
+                std::string bestVersion;
                 for (auto j = availElems.begin(); j != availElems.end(); ++j) {
                     if (comparePriorities(*globals.state, i, *j) > 0)
                         continue;
@@ -662,7 +662,7 @@ static void opUpgrade(Globals & globals, Strings opFlags, Strings opArgs)
 {
     UpgradeType upgradeType = utLt;
     for (Strings::iterator i = opFlags.begin(); i != opFlags.end(); ) {
-        string arg = *i++;
+        std::string arg = *i++;
         if (parseInstallSourceOptions(globals, i, opFlags, arg)) ;
         else if (arg == "--lt") upgradeType = utLt;
         else if (arg == "--leq") upgradeType = utLeq;
@@ -676,7 +676,7 @@ static void opUpgrade(Globals & globals, Strings opFlags, Strings opArgs)
 
 
 static void setMetaFlag(EvalState & state, DrvInfo & drv,
-    const string & name, const string & value)
+    const std::string & name, const std::string & value)
 {
     auto v = state.allocValue();
     v->mkString(value);
@@ -692,12 +692,12 @@ static void opSetFlag(Globals & globals, Strings opFlags, Strings opArgs)
         throw UsageError("not enough arguments to '--set-flag'");
 
     Strings::iterator arg = opArgs.begin();
-    string flagName = *arg++;
-    string flagValue = *arg++;
+    std::string flagName = *arg++;
+    std::string flagValue = *arg++;
     DrvNames selectors = drvNamesFromArgs(Strings(arg, opArgs.end()));
 
     while (true) {
-        string lockToken = optimisticLockProfile(globals.profile);
+        std::string lockToken = optimisticLockProfile(globals.profile);
 
         DrvInfos installedElems = queryInstalled(*globals.state, globals.profile);
 
@@ -728,7 +728,7 @@ static void opSet(Globals & globals, Strings opFlags, Strings opArgs)
     if (!store2) throw Error("--set is not supported for this Nix store");
 
     for (Strings::iterator i = opFlags.begin(); i != opFlags.end(); ) {
-        string arg = *i++;
+        std::string arg = *i++;
         if (parseInstallSourceOptions(globals, i, opFlags, arg)) ;
         else throw UsageError("unknown flag '%1%'", arg);
     }
@@ -769,7 +769,7 @@ static void uninstallDerivations(Globals & globals, Strings & selectors,
     Path & profile)
 {
     while (true) {
-        string lockToken = optimisticLockProfile(profile);
+        auto lockToken = optimisticLockProfile(profile);
 
         DrvInfos workingElems = queryInstalled(*globals.state, profile);
 
@@ -855,11 +855,11 @@ void printTable(Table & table)
         Strings::iterator j;
         size_t column;
         for (j = i.begin(), column = 0; j != i.end(); ++j, ++column) {
-            string s = *j;
+            std::string s = *j;
             replace(s.begin(), s.end(), '\n', ' ');
             cout << s;
             if (column < nrColumns - 1)
-                cout << string(widths[column] - s.size() + 2, ' ');
+                cout << std::string(widths[column] - s.size() + 2, ' ');
         }
         cout << std::endl;
     }
@@ -876,7 +876,7 @@ void printTable(Table & table)
 typedef enum { cvLess, cvEqual, cvGreater, cvUnavail } VersionDiff;
 
 static VersionDiff compareVersionAgainstSet(
-    const DrvInfo & elem, const DrvInfos & elems, string & version)
+    const DrvInfo & elem, const DrvInfos & elems, std::string & version)
 {
     DrvName name(elem.queryName());
 
@@ -958,7 +958,7 @@ static void queryJSON(Globals & globals, std::vector<DrvInfo> & elems, bool prin
 static void opQuery(Globals & globals, Strings opFlags, Strings opArgs)
 {
     Strings remaining;
-    string attrPath;
+    std::string attrPath;
 
     bool printStatus = false;
     bool printName = true;
@@ -977,7 +977,7 @@ static void opQuery(Globals & globals, Strings opFlags, Strings opArgs)
     settings.readOnlyMode = true; /* makes evaluation a bit faster */
 
     for (Strings::iterator i = opFlags.begin(); i != opFlags.end(); ) {
-        string arg = *i++;
+        auto arg = *i++;
         if (arg == "--status" || arg == "-s") printStatus = true;
         else if (arg == "--no-name") printName = false;
         else if (arg == "--system") printSystem = true;
@@ -1094,7 +1094,7 @@ static void opQuery(Globals & globals, Strings opFlags, Strings opArgs)
                     attrs["substitutable"] = hasSubs ? "1" : "0";
                 } else
                     columns.push_back(
-                        (string) (isInstalled ? "I" : "-")
+                        (std::string) (isInstalled ? "I" : "-")
                         + (isValid ? "P" : "-")
                         + (hasSubs ? "S" : "-"));
             }
@@ -1118,7 +1118,7 @@ static void opQuery(Globals & globals, Strings opFlags, Strings opArgs)
                    same named packages in either the set of available
                    elements, or the set of installed elements.  !!!
                    This is O(N * M), should be O(N * lg M). */
-                string version;
+                std::string version;
                 VersionDiff diff = compareVersionAgainstSet(i, otherElems, version);
 
                 char ch;
@@ -1136,7 +1136,7 @@ static void opQuery(Globals & globals, Strings opFlags, Strings opArgs)
                         attrs["maxComparedVersion"] = version;
                     }
                 } else {
-                    string column = (string) "" + ch + " " + version;
+                    auto column = (std::string) "" + ch + " " + version;
                     if (diff == cvGreater && tty)
                         column = ANSI_RED + column + ANSI_NORMAL;
                     columns.push_back(column);
@@ -1150,7 +1150,7 @@ static void opQuery(Globals & globals, Strings opFlags, Strings opArgs)
                 columns.push_back(i.querySystem());
 
             if (printDrvPath) {
-                string drvPath = i.queryDrvPath();
+                auto drvPath = i.queryDrvPath();
                 if (xmlOutput) {
                     if (drvPath != "") attrs["drvPath"] = drvPath;
                 } else
@@ -1159,7 +1159,7 @@ static void opQuery(Globals & globals, Strings opFlags, Strings opArgs)
 
             if (printOutPath && !xmlOutput) {
                 DrvInfo::Outputs outputs = i.queryOutputs();
-                string s;
+                std::string s;
                 for (auto & j : outputs) {
                     if (!s.empty()) s += ';';
                     if (j.first != "out") { s += j.first; s += "="; }
@@ -1169,7 +1169,7 @@ static void opQuery(Globals & globals, Strings opFlags, Strings opArgs)
             }
 
             if (printDescription) {
-                string descr = i.queryMetaString("description");
+                auto descr = i.queryMetaString("description");
                 if (xmlOutput) {
                     if (descr != "") attrs["description"] = descr;
                 } else
@@ -1331,12 +1331,12 @@ static void opDeleteGenerations(Globals & globals, Strings opFlags, Strings opAr
 
     if (opArgs.size() == 1 && opArgs.front() == "old") {
         deleteOldGenerations(globals.profile, globals.dryRun);
-    } else if (opArgs.size() == 1 && opArgs.front().find('d') != string::npos) {
+    } else if (opArgs.size() == 1 && opArgs.front().find('d') != std::string::npos) {
         deleteGenerationsOlderThan(globals.profile, opArgs.front(), globals.dryRun);
-    } else if (opArgs.size() == 1 && opArgs.front().find('+') != string::npos) {
+    } else if (opArgs.size() == 1 && opArgs.front().find('+') != std::string::npos) {
         if (opArgs.front().size() < 2)
             throw Error("invalid number of generations '%1%'", opArgs.front());
-        string str_max = string(opArgs.front(), 1, opArgs.front().size());
+        auto str_max = opArgs.front().substr(1);
         auto max = string2Int<GenerationNumber>(str_max);
         if (!max || *max == 0)
             throw Error("invalid number of generations to keep '%1%'", opArgs.front());
@@ -1366,7 +1366,7 @@ static int main_nix_env(int argc, char * * argv)
         Strings opFlags, opArgs;
         Operation op = 0;
         RepairFlag repair = NoRepair;
-        string file;
+        std::string file;
 
         Globals globals;
 
diff --git a/src/nix-env/user-env.cc b/src/nix-env/user-env.cc
index 5842e6501..37e4086cb 100644
--- a/src/nix-env/user-env.cc
+++ b/src/nix-env/user-env.cc
@@ -32,7 +32,7 @@ DrvInfos queryInstalled(EvalState & state, const Path & userEnv)
 
 bool createUserEnv(EvalState & state, DrvInfos & elems,
     const Path & profile, bool keepDerivations,
-    const string & lockToken)
+    const std::string & lockToken)
 {
     /* Build the components in the user environment, if they don't
        exist already. */
diff --git a/src/nix-env/user-env.hh b/src/nix-env/user-env.hh
index f188efe9b..10646f713 100644
--- a/src/nix-env/user-env.hh
+++ b/src/nix-env/user-env.hh
@@ -8,6 +8,6 @@ DrvInfos queryInstalled(EvalState & state, const Path & userEnv);
 
 bool createUserEnv(EvalState & state, DrvInfos & elems,
     const Path & profile, bool keepDerivations,
-    const string & lockToken);
+    const std::string & lockToken);
 
 }
diff --git a/src/nix-instantiate/nix-instantiate.cc b/src/nix-instantiate/nix-instantiate.cc
index a08683be1..12fc8baf9 100644
--- a/src/nix-instantiate/nix-instantiate.cc
+++ b/src/nix-instantiate/nix-instantiate.cc
@@ -64,7 +64,7 @@ void processExpr(EvalState & state, const Strings & attrPaths,
                 Path drvPath = i.queryDrvPath();
 
                 /* What output do we want? */
-                string outputName = i.queryOutputName();
+                std::string outputName = i.queryOutputName();
                 if (outputName == "")
                     throw Error("derivation '%1%' lacks an 'outputName' attribute ", drvPath);
 
diff --git a/src/nix-store/dotgraph.cc b/src/nix-store/dotgraph.cc
index 8b699f39b..577cadceb 100644
--- a/src/nix-store/dotgraph.cc
+++ b/src/nix-store/dotgraph.cc
@@ -10,37 +10,35 @@ using std::cout;
 namespace nix {
 
 
-static string dotQuote(std::string_view s)
+static std::string dotQuote(std::string_view s)
 {
     return "\"" + std::string(s) + "\"";
 }
 
 
-static string nextColour()
+static const std::string & nextColour()
 {
     static int n = 0;
-    static string colours[] =
+    static std::vector<std::string> colours
         { "black", "red", "green", "blue"
         , "magenta", "burlywood" };
-    return colours[n++ % (sizeof(colours) / sizeof(string))];
+    return colours[n++ % colours.size()];
 }
 
 
-static string makeEdge(const string & src, const string & dst)
+static std::string makeEdge(std::string_view src, std::string_view dst)
 {
-    format f = format("%1% -> %2% [color = %3%];\n")
-        % dotQuote(src) % dotQuote(dst) % dotQuote(nextColour());
-    return f.str();
+    return fmt("%1% -> %2% [color = %3%];\n",
+        dotQuote(src), dotQuote(dst), dotQuote(nextColour()));
 }
 
 
-static string makeNode(const string & id, std::string_view label,
-    const string & colour)
+static std::string makeNode(std::string_view id, std::string_view label,
+    std::string_view colour)
 {
-    format f = format("%1% [label = %2%, shape = box, "
-        "style = filled, fillcolor = %3%];\n")
-        % dotQuote(id) % dotQuote(label) % dotQuote(colour);
-    return f.str();
+    return fmt("%1% [label = %2%, shape = box, "
+        "style = filled, fillcolor = %3%];\n",
+        dotQuote(id), dotQuote(label), dotQuote(colour));
 }
 
 
diff --git a/src/nix-store/graphml.cc b/src/nix-store/graphml.cc
index 8ca5c9c8d..425d61e53 100644
--- a/src/nix-store/graphml.cc
+++ b/src/nix-store/graphml.cc
@@ -19,20 +19,20 @@ static inline std::string_view xmlQuote(std::string_view s)
 }
 
 
-static string symbolicName(const std::string & p)
+static std::string symbolicName(std::string_view p)
 {
-    return string(p, p.find('-') + 1);
+    return std::string(p.substr(0, p.find('-') + 1));
 }
 
 
-static string makeEdge(std::string_view src, std::string_view dst)
+static std::string makeEdge(std::string_view src, std::string_view dst)
 {
     return fmt("  <edge source=\"%1%\" target=\"%2%\"/>\n",
         xmlQuote(src), xmlQuote(dst));
 }
 
 
-static string makeNode(const ValidPathInfo & info)
+static std::string makeNode(const ValidPathInfo & info)
 {
     return fmt(
         "  <node id=\"%1%\">\n"
diff --git a/src/nix-store/nix-store.cc b/src/nix-store/nix-store.cc
index f0ce0368a..ecd7279e9 100644
--- a/src/nix-store/nix-store.cc
+++ b/src/nix-store/nix-store.cc
@@ -208,8 +208,8 @@ static void opPrintFixedPath(Strings opFlags, Strings opArgs)
 
     Strings::iterator i = opArgs.begin();
     HashType hashAlgo = parseHashType(*i++);
-    string hash = *i++;
-    string name = *i++;
+    std::string hash = *i++;
+    std::string name = *i++;
 
     cout << fmt("%s\n", store->printStorePath(store->makeFixedOutputPath(recursive, Hash::parseAny(hash, hashAlgo), name)));
 }
@@ -238,7 +238,7 @@ static StorePathSet maybeUseOutputs(const StorePath & storePath, bool useOutput,
    graph.  Topological sorting is used to keep the tree relatively
    flat. */
 static void printTree(const StorePath & path,
-    const string & firstPad, const string & tailPad, StorePathSet & done)
+    const std::string & firstPad, const std::string & tailPad, StorePathSet & done)
 {
     if (!done.insert(path).second) {
         cout << fmt("%s%s [...]\n", firstPad, store->printStorePath(path));
@@ -277,7 +277,7 @@ static void opQuery(Strings opFlags, Strings opArgs)
     bool useOutput = false;
     bool includeOutputs = false;
     bool forceRealise = false;
-    string bindingName;
+    std::string bindingName;
 
     for (auto & i : opFlags) {
         QueryType prev = query;
@@ -637,7 +637,7 @@ static void opDump(Strings opFlags, Strings opArgs)
     if (opArgs.size() != 1) throw UsageError("only one argument allowed");
 
     FdSink sink(STDOUT_FILENO);
-    string path = *opArgs.begin();
+    std::string path = *opArgs.begin();
     dumpPath(path, sink);
     sink.flush();
 }
@@ -975,9 +975,9 @@ static void opGenerateBinaryCacheKey(Strings opFlags, Strings opArgs)
 
     if (opArgs.size() != 3) throw UsageError("three arguments expected");
     auto i = opArgs.begin();
-    string keyName = *i++;
-    string secretKeyFile = *i++;
-    string publicKeyFile = *i++;
+    std::string keyName = *i++;
+    std::string secretKeyFile = *i++;
+    std::string publicKeyFile = *i++;
 
     auto secretKey = SecretKey::generate(keyName);
 
diff --git a/src/nix/daemon.cc b/src/nix/daemon.cc
index 6a40a0bd3..940923d3b 100644
--- a/src/nix/daemon.cc
+++ b/src/nix/daemon.cc
@@ -76,7 +76,7 @@ static void setSigChldAction(bool autoReap)
 }
 
 
-bool matchUser(const string & user, const string & group, const Strings & users)
+bool matchUser(const std::string & user, const std::string & group, const Strings & users)
 {
     if (find(users.begin(), users.end(), "*") != users.end())
         return true;
@@ -85,12 +85,12 @@ bool matchUser(const string & user, const string & group, const Strings & users)
         return true;
 
     for (auto & i : users)
-        if (string(i, 0, 1) == "@") {
-            if (group == string(i, 1)) return true;
+        if (i.substr(0, 1) == "@") {
+            if (group == i.substr(1)) return true;
             struct group * gr = getgrnam(i.c_str() + 1);
             if (!gr) continue;
             for (char * * mem = gr->gr_mem; *mem; mem++)
-                if (user == string(*mem)) return true;
+                if (user == std::string(*mem)) return true;
         }
 
     return false;
@@ -198,10 +198,10 @@ static void daemonLoop()
             PeerInfo peer = getPeerInfo(remote.get());
 
             struct passwd * pw = peer.uidKnown ? getpwuid(peer.uid) : 0;
-            string user = pw ? pw->pw_name : std::to_string(peer.uid);
+            std::string user = pw ? pw->pw_name : std::to_string(peer.uid);
 
             struct group * gr = peer.gidKnown ? getgrgid(peer.gid) : 0;
-            string group = gr ? gr->gr_name : std::to_string(peer.gid);
+            std::string group = gr ? gr->gr_name : std::to_string(peer.gid);
 
             Strings trustedUsers = settings.trustedUsers;
             Strings allowedUsers = settings.allowedUsers;
@@ -212,7 +212,7 @@ static void daemonLoop()
             if ((!trusted && !matchUser(user, group, allowedUsers)) || group == settings.buildUsersGroup)
                 throw Error("user '%1%' is not allowed to connect to the Nix daemon", user);
 
-            printInfo(format((string) "accepted connection from pid %1%, user %2%" + (trusted ? " (trusted)" : ""))
+            printInfo(format((std::string) "accepted connection from pid %1%, user %2%" + (trusted ? " (trusted)" : ""))
                 % (peer.pidKnown ? std::to_string(peer.pid) : "<unknown>")
                 % (peer.uidKnown ? user : "<unknown>"));
 
@@ -234,7 +234,7 @@ static void daemonLoop()
 
                 //  For debugging, stuff the pid into argv[1].
                 if (peer.pidKnown && savedArgv[1]) {
-                    string processName = std::to_string(peer.pid);
+                    auto processName = std::to_string(peer.pid);
                     strncpy(savedArgv[1], processName.c_str(), strlen(savedArgv[1]));
                 }
 
diff --git a/src/nix/hash.cc b/src/nix/hash.cc
index 4535e4ab0..60d9593a7 100644
--- a/src/nix/hash.cc
+++ b/src/nix/hash.cc
@@ -177,7 +177,7 @@ static int compatNixHash(int argc, char * * argv)
         else if (*arg == "--base32") base32 = true;
         else if (*arg == "--truncate") truncate = true;
         else if (*arg == "--type") {
-            string s = getArg(*arg, arg, end);
+            std::string s = getArg(*arg, arg, end);
             ht = parseHashType(s);
         }
         else if (*arg == "--to-base16") op = opTo16;
diff --git a/src/nix/prefetch.cc b/src/nix/prefetch.cc
index 094d2a519..f2dd44ba4 100644
--- a/src/nix/prefetch.cc
+++ b/src/nix/prefetch.cc
@@ -16,7 +16,7 @@ using namespace nix;
 
 /* If ‘url’ starts with ‘mirror://’, then resolve it using the list of
    mirrors defined in Nixpkgs. */
-string resolveMirrorUrl(EvalState & state, string url)
+std::string resolveMirrorUrl(EvalState & state, const std::string & url)
 {
     if (url.substr(0, 9) != "mirror://") return url;
 
@@ -38,8 +38,8 @@ string resolveMirrorUrl(EvalState & state, string url)
     if (mirrorList->value->listSize() < 1)
         throw Error("mirror URL '%s' did not expand to anything", url);
 
-    string mirror(state.forceString(*mirrorList->value->listElems()[0]));
-    return mirror + (hasSuffix(mirror, "/") ? "" : "/") + string(s, p + 1);
+    std::string mirror(state.forceString(*mirrorList->value->listElems()[0]));
+    return mirror + (hasSuffix(mirror, "/") ? "" : "/") + s.substr(p + 1);
 }
 
 std::tuple<StorePath, Hash> prefetchFile(
@@ -128,10 +128,10 @@ static int main_nix_prefetch_url(int argc, char * * argv)
 {
     {
         HashType ht = htSHA256;
-        std::vector<string> args;
+        std::vector<std::string> args;
         bool printPath = getEnv("PRINT_PATH") == "1";
         bool fromExpr = false;
-        string attrPath;
+        std::string attrPath;
         bool unpack = false;
         bool executable = false;
         std::optional<std::string> name;
@@ -147,7 +147,7 @@ static int main_nix_prefetch_url(int argc, char * * argv)
             else if (*arg == "--version")
                 printVersion("nix-prefetch-url");
             else if (*arg == "--type") {
-                string s = getArg(*arg, arg, end);
+                auto s = getArg(*arg, arg, end);
                 ht = parseHashType(s);
             }
             else if (*arg == "--print-path")
@@ -186,7 +186,7 @@ static int main_nix_prefetch_url(int argc, char * * argv)
 
         /* If -A is given, get the URL from the specified Nix
            expression. */
-        string url;
+        std::string url;
         if (!fromExpr) {
             if (args.empty())
                 throw UsageError("you must specify a URL");
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 575eb0c4c..731337004 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -45,7 +45,7 @@ struct NixRepl
     : gc
     #endif
 {
-    string curDir;
+    std::string curDir;
     std::unique_ptr<EvalState> state;
     Bindings * autoArgs;
 
@@ -62,18 +62,18 @@ struct NixRepl
     NixRepl(const Strings & searchPath, nix::ref<Store> store);
     ~NixRepl();
     void mainLoop(const std::vector<std::string> & files);
-    StringSet completePrefix(string prefix);
-    bool getLine(string & input, const std::string &prompt);
+    StringSet completePrefix(const std::string & prefix);
+    bool getLine(std::string & input, const std::string &prompt);
     StorePath getDerivationPath(Value & v);
-    bool processLine(string line);
+    bool processLine(std::string line);
     void loadFile(const Path & path);
     void loadFlake(const std::string & flakeRef);
     void initEnv();
     void reloadFiles();
     void addAttrsToScope(Value & attrs);
     void addVarToScope(const Symbol & name, Value & v);
-    Expr * parseString(string s);
-    void evalString(string s, Value & v);
+    Expr * parseString(std::string s);
+    void evalString(std::string s, Value & v);
 
     typedef std::set<Value *> ValuesSeen;
     std::ostream &  printValue(std::ostream & str, Value & v, unsigned int maxDepth);
@@ -81,11 +81,11 @@ struct NixRepl
 };
 
 
-string removeWhitespace(string s)
+std::string removeWhitespace(std::string s)
 {
     s = chomp(s);
     size_t n = s.find_first_not_of(" \n\r\t");
-    if (n != string::npos) s = string(s, n);
+    if (n != std::string::npos) s = std::string(s, n);
     return s;
 }
 
@@ -104,7 +104,7 @@ NixRepl::~NixRepl()
     write_history(historyFile.c_str());
 }
 
-string runNix(Path program, const Strings & args,
+std::string runNix(Path program, const Strings & args,
     const std::optional<std::string> & input = {})
 {
     auto subprocessEnv = getEnv();
@@ -198,7 +198,7 @@ namespace {
 
 void NixRepl::mainLoop(const std::vector<std::string> & files)
 {
-    string error = ANSI_RED "error:" ANSI_NORMAL " ";
+    std::string error = ANSI_RED "error:" ANSI_NORMAL " ";
     notice("Welcome to Nix " + nixVersion + ". Type :? for help.\n");
 
     for (auto & i : files)
@@ -252,7 +252,7 @@ void NixRepl::mainLoop(const std::vector<std::string> & files)
 }
 
 
-bool NixRepl::getLine(string & input, const std::string &prompt)
+bool NixRepl::getLine(std::string & input, const std::string & prompt)
 {
     struct sigaction act, old;
     sigset_t savedSignalMask, set;
@@ -297,7 +297,7 @@ bool NixRepl::getLine(string & input, const std::string &prompt)
 }
 
 
-StringSet NixRepl::completePrefix(string prefix)
+StringSet NixRepl::completePrefix(const std::string & prefix)
 {
     StringSet completions;
 
@@ -313,7 +313,7 @@ StringSet NixRepl::completePrefix(string prefix)
 
     size_t slash, dot;
 
-    if ((slash = cur.rfind('/')) != string::npos) {
+    if ((slash = cur.rfind('/')) != std::string::npos) {
         try {
             auto dir = std::string(cur, 0, slash);
             auto prefix2 = std::string(cur, slash + 1);
@@ -323,11 +323,11 @@ StringSet NixRepl::completePrefix(string prefix)
             }
         } catch (Error &) {
         }
-    } else if ((dot = cur.rfind('.')) == string::npos) {
+    } else if ((dot = cur.rfind('.')) == std::string::npos) {
         /* This is a variable name; look it up in the current scope. */
         StringSet::iterator i = varNames.lower_bound(cur);
         while (i != varNames.end()) {
-            if (string(*i, 0, cur.size()) != cur) break;
+            if (i->substr(0, cur.size()) != cur) break;
             completions.insert(prev + *i);
             i++;
         }
@@ -336,8 +336,8 @@ StringSet NixRepl::completePrefix(string prefix)
             /* This is an expression that should evaluate to an
                attribute set.  Evaluate it to get the names of the
                attributes. */
-            string expr(cur, 0, dot);
-            string cur2 = string(cur, dot + 1);
+            auto expr = cur.substr(0, dot);
+            auto cur2 = cur.substr(dot + 1);
 
             Expr * e = parseString(expr);
             Value v;
@@ -345,8 +345,8 @@ StringSet NixRepl::completePrefix(string prefix)
             state->forceAttrs(v, noPos);
 
             for (auto & i : *v.attrs) {
-                string name = i.name;
-                if (string(name, 0, cur2.size()) != cur2) continue;
+                std::string name = i.name;
+                if (name.substr(0, cur2.size()) != cur2) continue;
                 completions.insert(prev + expr + "." + name);
             }
 
@@ -365,7 +365,7 @@ StringSet NixRepl::completePrefix(string prefix)
 }
 
 
-bool isVarName(const string & s)
+static bool isVarName(std::string_view s)
 {
     if (s.size() == 0) return false;
     char c = s[0];
@@ -394,18 +394,18 @@ StorePath NixRepl::getDerivationPath(Value & v) {
 }
 
 
-bool NixRepl::processLine(string line)
+bool NixRepl::processLine(std::string line)
 {
     if (line == "") return true;
 
     _isInterrupted = false;
 
-    string command, arg;
+    std::string command, arg;
 
     if (line[0] == ':') {
         size_t p = line.find_first_of(" \n\r\t");
-        command = string(line, 0, p);
-        if (p != string::npos) arg = removeWhitespace(string(line, p));
+        command = line.substr(0, p);
+        if (p != std::string::npos) arg = removeWhitespace(line.substr(p));
     } else {
         arg = line;
     }
@@ -590,13 +590,13 @@ bool NixRepl::processLine(string line)
 
     else {
         size_t p = line.find('=');
-        string name;
-        if (p != string::npos &&
+        std::string name;
+        if (p != std::string::npos &&
             p < line.size() &&
             line[p + 1] != '=' &&
-            isVarName(name = removeWhitespace(string(line, 0, p))))
+            isVarName(name = removeWhitespace(line.substr(0, p))))
         {
-            Expr * e = parseString(string(line, p + 1));
+            Expr * e = parseString(line.substr(p + 1));
             Value & v(*state->allocValue());
             v.mkThunk(env, e);
             addVarToScope(state->symbols.create(name), v);
@@ -683,7 +683,7 @@ void NixRepl::addAttrsToScope(Value & attrs)
     for (auto & i : *attrs.attrs) {
         staticEnv.vars.emplace_back(i.name, displ);
         env->values[displ++] = i.value;
-        varNames.insert((string) i.name);
+        varNames.insert((std::string) i.name);
     }
     staticEnv.sort();
     staticEnv.deduplicate();
@@ -700,18 +700,18 @@ void NixRepl::addVarToScope(const Symbol & name, Value & v)
     staticEnv.vars.emplace_back(name, displ);
     staticEnv.sort();
     env->values[displ++] = &v;
-    varNames.insert((string) name);
+    varNames.insert((std::string) name);
 }
 
 
-Expr * NixRepl::parseString(string s)
+Expr * NixRepl::parseString(std::string s)
 {
     Expr * e = state->parseExprFromString(std::move(s), curDir, staticEnv);
     return e;
 }
 
 
-void NixRepl::evalString(string s, Value & v)
+void NixRepl::evalString(std::string s, Value & v)
 {
     Expr * e = parseString(s);
     e->eval(*state, *env, v);
@@ -787,7 +787,7 @@ std::ostream & NixRepl::printValue(std::ostream & str, Value & v, unsigned int m
         else if (maxDepth > 0) {
             str << "{ ";
 
-            typedef std::map<string, Value *> Sorted;
+            typedef std::map<std::string, Value *> Sorted;
             Sorted sorted;
             for (auto & i : *v.attrs)
                 sorted[i.name] = i.value;
diff --git a/src/nix/why-depends.cc b/src/nix/why-depends.cc
index 657df30d7..cc05deda0 100644
--- a/src/nix/why-depends.cc
+++ b/src/nix/why-depends.cc
@@ -157,11 +157,11 @@ struct CmdWhyDepends : SourceExprCommand
            closure (i.e., that have a non-infinite distance to
            'dependency'). Print every edge on a path between `package`
            and `dependency`. */
-        std::function<void(Node &, const string &, const string &)> printNode;
+        std::function<void(Node &, const std::string &, const std::string &)> printNode;
 
         struct BailOut { };
 
-        printNode = [&](Node & node, const string & firstPad, const string & tailPad) {
+        printNode = [&](Node & node, const std::string & firstPad, const std::string & tailPad) {
             auto pathS = store->printStorePath(node.path);
 
             assert(node.dist != inf);

From a949673a5b4a08429e9866bc8558e961bb8fe130 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 28 Feb 2022 15:21:03 +0100
Subject: [PATCH 565/567] Fix Darwin build

Fixes #6169
---
 src/libstore/build/local-derivation-goal.cc | 4 ++--
 src/libstore/build/local-derivation-goal.hh | 2 +-
 src/libstore/gc.cc                          | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 220f80602..a2a52e8f9 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -1933,7 +1933,7 @@ void LocalDerivationGoal::runChild()
                             "can't map '%1%' to '%2%': mismatched impure paths not supported on Darwin",
                             i.first, i.second.source);
 
-                    string path = i.first;
+                    std::string path = i.first;
                     struct stat st;
                     if (lstat(path.c_str(), &st)) {
                         if (i.second.optional && errno == ENOENT)
@@ -1985,7 +1985,7 @@ void LocalDerivationGoal::runChild()
                 args.push_back("IMPORT_DIR=" + settings.nixDataDir + "/nix/sandbox/");
                 if (allowLocalNetworking) {
                     args.push_back("-D");
-                    args.push_back(string("_ALLOW_LOCAL_NETWORKING=1"));
+                    args.push_back(std::string("_ALLOW_LOCAL_NETWORKING=1"));
                 }
                 args.push_back(drv->builder);
             } else {
diff --git a/src/libstore/build/local-derivation-goal.hh b/src/libstore/build/local-derivation-goal.hh
index 2d1222d2f..95692c60d 100644
--- a/src/libstore/build/local-derivation-goal.hh
+++ b/src/libstore/build/local-derivation-goal.hh
@@ -62,7 +62,7 @@ struct LocalDerivationGoal : public DerivationGoal
     Environment env;
 
 #if __APPLE__
-    typedef string SandboxProfile;
+    typedef std::string SandboxProfile;
     SandboxProfile additionalSandboxProfile;
 #endif
 
diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index fd38b731c..024da66c1 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -413,7 +413,7 @@ void LocalStore::findRuntimeRoots(Roots & roots, bool censor)
         try {
             std::regex lsofRegex(R"(^n(/.*)$)");
             auto lsofLines =
-                tokenizeString<std::vector<string>>(runProgram(LSOF, true, { "-n", "-w", "-F", "n" }), "\n");
+                tokenizeString<std::vector<std::string>>(runProgram(LSOF, true, { "-n", "-w", "-F", "n" }), "\n");
             for (const auto & line : lsofLines) {
                 std::smatch match;
                 if (std::regex_match(line, match, lsofRegex))

From b91500a14e5f1bab33cd9dccbe9a85ad2832062a Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 28 Feb 2022 15:24:24 +0100
Subject: [PATCH 566/567] Fix clang warning

---
 src/libstore/build/local-derivation-goal.cc | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index a2a52e8f9..7e69d4145 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -2383,14 +2383,10 @@ void LocalDerivationGoal::registerOutputs()
             [&](DerivationOutputCAFloating dof) {
                 return newInfoFromCA(dof);
             },
-                [&](DerivationOutputDeferred) {
+            [&](DerivationOutputDeferred) -> ValidPathInfo {
                 // No derivation should reach that point without having been
                 // rewritten first
                 assert(false);
-                // Ugly, but the compiler insists on having this return a value
-                // of type `ValidPathInfo` despite the `assert(false)`, so
-                // let's provide it
-                return *(ValidPathInfo*)0;
             },
         }, output.output);
 

From b8f8aef9d3d026af474a4f7ef8f09678c3e5a7d4 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Mon, 28 Feb 2022 14:41:09 +0100
Subject: [PATCH 567/567] tests: Fix the start of the daemon
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- Make sure that it starts even without the `nix-command` xp feature
- Fail if it doesn’t manage to start

This fixes a 30s wait for every test in `init.sh` as the daemon couldn’t
start, but the code was just waiting 30s and continuing as if everything
was all right.
---
 tests/common.sh.in | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/tests/common.sh.in b/tests/common.sh.in
index 49068f1c3..e485329ba 100644
--- a/tests/common.sh.in
+++ b/tests/common.sh.in
@@ -90,12 +90,18 @@ startDaemon() {
     # Start the daemon, wait for the socket to appear.  !!!
     # ‘nix-daemon’ should have an option to fork into the background.
     rm -f $NIX_DAEMON_SOCKET_PATH
-    PATH=$DAEMON_PATH nix daemon &
+    PATH=$DAEMON_PATH nix-daemon&
+    pidDaemon=$!
     for ((i = 0; i < 300; i++)); do
-        if [[ -S $NIX_DAEMON_SOCKET_PATH ]]; then break; fi
+        if [[ -S $NIX_DAEMON_SOCKET_PATH ]]; then
+          DAEMON_STARTED=1
+          break;
+        fi
         sleep 0.1
     done
-    pidDaemon=$!
+    if [[ -z ${DAEMON_STARTED+x} ]]; then
+      fail "Didn’t manage to start the daemon"
+    fi
     trap "killDaemon" EXIT
     export NIX_REMOTE=daemon
 }