Merge branch 'master' into caveman-LOCs

.gitignore

@@ -49,6 +49,9 @@ perl/Makefile.config
 # /src/libstore/
 *.gen.*
 
+# /src/libutil/
+/src/libutil/tests/libutil-tests
+
 /src/nix/nix
 
 # /src/nix-env/

Makefile

@@ -1,7 +1,6 @@
 makefiles = \
   mk/precompiled-headers.mk \
   local.mk \
-  nix-rust/local.mk \
   src/libutil/local.mk \
   src/libutil/tests/local.mk \
   src/libstore/local.mk \

doc/manual/advanced-topics/diff-hook.xml

@@ -70,7 +70,7 @@ path just built.</para>
 
   <screen>
 $ nix-build ./deterministic.nix -A stable
-these derivations will be built:
+this derivation will be built:
   /nix/store/z98fasz2jqy9gs0xbvdj939p27jwda38-stable.drv
 building '/nix/store/z98fasz2jqy9gs0xbvdj939p27jwda38-stable.drv'...
 /nix/store/yyxlzw3vqaas7wfp04g0b1xg51f2czgq-stable
@@ -85,7 +85,7 @@ checking outputs of '/nix/store/z98fasz2jqy9gs0xbvdj939p27jwda38-stable.drv'...
 
   <screen>
 $ nix-build ./deterministic.nix -A unstable
-these derivations will be built:
+this derivation will be built:
   /nix/store/cgl13lbj1w368r5z8gywipl1ifli7dhk-unstable.drv
 building '/nix/store/cgl13lbj1w368r5z8gywipl1ifli7dhk-unstable.drv'...
 /nix/store/krpqk0l9ib0ibi1d2w52z293zw455cap-unstable
@@ -193,7 +193,7 @@ repeat = 1
     An example output of this configuration:
     <screen>
 $ nix-build ./test.nix -A unstable
-these derivations will be built:
+this derivation will be built:
   /nix/store/ch6llwpr2h8c3jmnf3f2ghkhx59aa97f-unstable.drv
 building '/nix/store/ch6llwpr2h8c3jmnf3f2ghkhx59aa97f-unstable.drv' (round 1/2)...
 building '/nix/store/ch6llwpr2h8c3jmnf3f2ghkhx59aa97f-unstable.drv' (round 2/2)...

doc/manual/advanced-topics/post-build-hook.xml

@@ -122,7 +122,7 @@ post-build-hook = /etc/nix/upload-to-cache.sh
 
   <screen>
 $ nix-build -E '(import &lt;nixpkgs&gt; {}).writeText "example" (builtins.toString builtins.currentTime)'
-these derivations will be built:
+this derivation will be built:
   /nix/store/s4pnfbkalzy5qz57qs6yybna8wylkig6-example.drv
 building '/nix/store/s4pnfbkalzy5qz57qs6yybna8wylkig6-example.drv'...
 running post-build-hook '/home/grahamc/projects/github.com/NixOS/nix/post-hook.sh'...

doc/manual/command-ref/nix-env.xml

@@ -516,7 +516,7 @@ source:
 $ nix-env -f '<nixpkgs>' -iA hello --dry-run
 (dry run; not doing anything)
 installing ‘hello-2.10’
-these paths will be fetched (0.04 MiB download, 0.19 MiB unpacked):
+this path will be fetched (0.04 MiB download, 0.19 MiB unpacked):
   /nix/store/wkhdf9jinag5750mqlax6z2zbwhqb76n-hello-2.10
   <replaceable>...</replaceable></screen>
 

doc/manual/command-ref/opt-common-syn.xml

@@ -11,6 +11,10 @@
 <arg>
   <arg choice='plain'><option>--quiet</option></arg>
 </arg>
+<arg>
+  <option>--log-format</option>
+  <replaceable>format</replaceable>
+</arg>
 <arg>
   <group choice='plain'>
     <arg choice='plain'><option>--no-build-output</option></arg>

doc/manual/command-ref/opt-common.xml

@@ -92,6 +92,37 @@
 </varlistentry>
 
 
+<varlistentry xml:id="opt-log-format"><term><option>--log-format</option> <replaceable>format</replaceable></term>
+
+  <listitem>
+
+  <para>This option can be used to change the output of the log format, with
+  <replaceable>format</replaceable> being one of:</para>
+
+  <variablelist>
+
+    <varlistentry><term>raw</term>
+    <listitem><para>This is the raw format, as outputted by nix-build.</para></listitem>
+    </varlistentry>
+
+    <varlistentry><term>internal-json</term>
+    <listitem><para>Outputs the logs in a structured manner. NOTE: the json schema is not guarantees to be stable between releases.</para></listitem>
+    </varlistentry>
+
+    <varlistentry><term>bar</term>
+    <listitem><para>Only display a progress bar during the builds.</para></listitem>
+    </varlistentry>
+
+    <varlistentry><term>bar-with-logs</term>
+    <listitem><para>Display the raw logs, with the progress bar at the bottom.</para></listitem>
+    </varlistentry>
+
+  </variablelist>
+
+  </listitem>
+
+</varlistentry>
+
 <varlistentry><term><option>--no-build-output</option> / <option>-Q</option></term>
 
   <listitem><para>By default, output written by builders to standard

doc/manual/installation/env-variables.xml

@@ -39,7 +39,7 @@ bundle.</para>
   <step><para>Set the environment variable and install Nix</para>
     <screen>
 $ export NIX_SSL_CERT_FILE=/etc/ssl/my-certificate-bundle.crt
-$ sh &lt;(curl https://nixos.org/nix/install)
+$ sh &lt;(curl -L https://nixos.org/nix/install)
 </screen></step>
 
   <step><para>In the shell profile and rc files (for example,

doc/manual/installation/installing-binary.xml

@@ -12,7 +12,7 @@
 </para>
 
 <screen>
-  $ sh &lt;(curl https://nixos.org/nix/install)
+  $ sh &lt;(curl -L https://nixos.org/nix/install)
 </screen>
 
 <para>
@@ -39,7 +39,7 @@
     To explicitly select a single-user installation on your system:
 
     <screen>
-  sh &lt;(curl https://nixos.org/nix/install) --no-daemon
+  sh &lt;(curl -L https://nixos.org/nix/install) --no-daemon
 </screen>
   </para>
 

doc/manual/introduction/quick-start.xml

@@ -15,7 +15,7 @@ to subsequent chapters.</para>
 <step><para>Install single-user Nix by running the following:
 
 <screen>
-$ bash &lt;(curl https://nixos.org/nix/install)
+$ bash &lt;(curl -L https://nixos.org/nix/install)
 </screen>
 
 This will install Nix in <filename>/nix</filename>. The install script

maintainers/upload-release.pl

@@ -142,8 +142,12 @@ $oldName =~ s/"//g;
 sub getStorePath {
     my ($jobName) = @_;
     my $buildInfo = decode_json(fetch("$evalUrl/job/$jobName", 'application/json'));
-    die unless $buildInfo->{buildproducts}->{1}->{type} eq "nix-build";
+    for my $product (values %{$buildInfo->{buildproducts}}) {
-    return $buildInfo->{buildproducts}->{1}->{path};
+        next unless $product->{type} eq "nix-build";
+        next if $product->{path} =~ /[a-z]+$/;
+        return $product->{path};
+    }
+    die;
 }
 
 write_file("$nixpkgsDir/nixos/modules/installer/tools/nix-fallback-paths.nix",

mk/libraries.mk

@@ -125,7 +125,8 @@ define build-library
     $(1)_PATH := $$(_d)/$$($(1)_NAME).a
 
     $$($(1)_PATH): $$($(1)_OBJS) | $$(_d)/
-	$(trace-ar) $(AR) crs $$@ $$?
+	$(trace-ld) $(LD) -Ur -o $$(_d)/$$($(1)_NAME).o $$?
+	$(trace-ar) $(AR) crs $$@ $$(_d)/$$($(1)_NAME).o
 
     $(1)_LDFLAGS_USE += $$($(1)_PATH) $$($(1)_LDFLAGS)
 

perl/lib/Nix/Store.xs

@@ -80,7 +80,7 @@ SV * queryReferences(char * path)
 SV * queryPathHash(char * path)
     PPCODE:
         try {
-            auto s = store()->queryPathInfo(store()->parseStorePath(path))->narHash.to_string();
+            auto s = store()->queryPathInfo(store()->parseStorePath(path))->narHash.to_string(Base32, true);
             XPUSHs(sv_2mortal(newSVpv(s.c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());
@@ -106,7 +106,7 @@ SV * queryPathInfo(char * path, int base32)
                 XPUSHs(&PL_sv_undef);
             else
                 XPUSHs(sv_2mortal(newSVpv(store()->printStorePath(*info->deriver).c_str(), 0)));
-            auto s = info->narHash.to_string(base32 ? Base32 : Base16);
+            auto s = info->narHash.to_string(base32 ? Base32 : Base16, true);
             XPUSHs(sv_2mortal(newSVpv(s.c_str(), 0)));
             mXPUSHi(info->registrationTime);
             mXPUSHi(info->narSize);

release-common.nix

@@ -50,7 +50,6 @@ rec {
       libarchive
       boost
       nlohmann_json
-      rustc cargo
 
       # Tests
       git

release.nix

@@ -12,64 +12,8 @@ let
     builtins.readFile ./.version
     + (if officialRelease then "" else "pre${toString nix.revCount}_${nix.shortRev}");
 
-  # Create a "vendor" directory that contains the crates listed in
-  # Cargo.lock. This allows Nix to be built without network access.
-  vendoredCrates' =
-    let
-      lockFile = builtins.fromTOML (builtins.readFile nix-rust/Cargo.lock);
-
-      files = map (pkg: import <nix/fetchurl.nix> {
-        url = "https://crates.io/api/v1/crates/${pkg.name}/${pkg.version}/download";
-        sha256 = lockFile.metadata."checksum ${pkg.name} ${pkg.version} (registry+https://github.com/rust-lang/crates.io-index)";
-      }) (builtins.filter (pkg: pkg.source or "" == "registry+https://github.com/rust-lang/crates.io-index") lockFile.package);
-
-    in pkgs.runCommand "cargo-vendor-dir" {}
-      ''
-        mkdir -p $out/vendor
-
-        cat > $out/vendor/config <<EOF
-        [source.crates-io]
-        replace-with = "vendored-sources"
-
-        [source.vendored-sources]
-        directory = "vendor"
-        EOF
-
-        ${toString (builtins.map (file: ''
-          mkdir $out/vendor/tmp
-          tar xvf ${file} -C $out/vendor/tmp
-          dir=$(echo $out/vendor/tmp/*)
-
-          # Add just enough metadata to keep Cargo happy.
-          printf '{"files":{},"package":"${file.outputHash}"}' > "$dir/.cargo-checksum.json"
-
-          # Clean up some cruft from the winapi crates. FIXME: find
-          # a way to remove winapi* from our dependencies.
-          if [[ $dir =~ /winapi ]]; then
-            find $dir -name "*.a" -print0 | xargs -0 rm -f --
-          fi
-
-          mv "$dir" $out/vendor/
-
-          rm -rf $out/vendor/tmp
-        '') files)}
-      '';
-
   jobs = rec {
 
-    vendoredCrates =
-      with pkgs;
-      runCommand "vendored-crates" {}
-        ''
-          mkdir -p $out/nix-support
-          name=nix-vendored-crates-${version}
-          fn=$out/$name.tar.xz
-            tar cvfJ $fn -C ${vendoredCrates'} vendor \
-              --owner=0 --group=0 --mode=u+rw,uga+r \
-              --transform "s,vendor,$name,"
-            echo "file crates-tarball $fn" >> $out/nix-support/hydra-build-products
-        '';
-
     build = pkgs.lib.genAttrs systems (system:
 
       let pkgs = import nixpkgs { inherit system; }; in
@@ -101,8 +45,6 @@ let
               patchelf --set-rpath $out/lib:${stdenv.cc.cc.lib}/lib $out/lib/libboost_thread.so.*
             ''}
 
-            ln -sfn ${vendoredCrates'}/vendor/ nix-rust/vendor
-
             (cd perl; autoreconf --install --force --verbose)
           '';
 
@@ -247,11 +189,6 @@ let
 
         src = nix;
 
-        preConfigure =
-          ''
-            ln -sfn ${vendoredCrates'}/vendor/ nix-rust/vendor
-          '';
-
         enableParallelBuilding = true;
 
         buildInputs = buildDeps ++ propagatedDeps;

shell.nix

@@ -7,7 +7,7 @@ with import ./release-common.nix { inherit pkgs; };
 (if useClang then clangStdenv else stdenv).mkDerivation {
   name = "nix";
 
-  buildInputs = buildDeps ++ propagatedDeps ++ perlDeps ++ [ pkgs.rustfmt ];
+  buildInputs = buildDeps ++ propagatedDeps ++ perlDeps;
 
   inherit configureFlags;
 

src/build-remote/build-remote.cc

@@ -244,7 +244,7 @@ connected:
 
         uploadLock = -1;
 
-        BasicDerivation drv(readDerivation(*store, store->realStoreDir + "/" + std::string(drvPath->to_string())));
+        auto drv = store->readDerivation(*drvPath);
         drv.inputSrcs = store->parseStorePathSet(inputs);
 
         auto result = sshStore->buildDerivation(*drvPath, drv);

src/libexpr/attr-path.cc

@@ -6,11 +6,11 @@
 namespace nix {
 
 
-static Strings parseAttrPath(const string & s)
+static Strings parseAttrPath(std::string_view s)
 {
     Strings res;
     string cur;
-    string::const_iterator i = s.begin();
+    auto i = s.begin();
     while (i != s.end()) {
         if (*i == '.') {
             res.push_back(cur);
@@ -32,6 +32,15 @@ static Strings parseAttrPath(const string & s)
 }
 
 
+std::vector<Symbol> parseAttrPath(EvalState & state, std::string_view s)
+{
+    std::vector<Symbol> res;
+    for (auto & a : parseAttrPath(s))
+        res.push_back(state.symbols.create(a));
+    return res;
+}
+
+
 std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const string & attrPath,
     Bindings & autoArgs, Value & vIn)
 {

src/libexpr/attr-path.hh

@@ -16,4 +16,6 @@ std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const string & attr
 /* Heuristic to find the filename and lineno or a nix value. */
 Pos findDerivationFilename(EvalState & state, Value & v, std::string what);
 
+std::vector<Symbol> parseAttrPath(EvalState & state, std::string_view s);
+
 }

src/libexpr/attr-set.hh

@@ -76,8 +76,7 @@ public:
     {
         auto a = get(name);
         if (!a)
-            throw Error(
+            throw Error({
-                ErrorInfo { 
                 .hint = hintfmt("attribute '%s' missing", name),
                 .nixCode = NixCode { .errPos = pos }
             });

src/libexpr/eval-inline.hh

@@ -9,8 +9,7 @@ namespace nix {
 
 LocalNoInlineNoReturn(void throwEvalError(const Pos & pos, const char * s))
 {
-    throw EvalError(
+    throw EvalError({
-        ErrorInfo { 
         .hint = hintfmt(s),
         .nixCode = NixCode { .errPos = pos }
     });
@@ -24,8 +23,7 @@ LocalNoInlineNoReturn(void throwTypeError(const char * s, const Value & v))
 
 LocalNoInlineNoReturn(void throwTypeError(const Pos & pos, const char * s, const Value & v))
 {
-    throw TypeError(
+    throw TypeError({
-        ErrorInfo { 
         .hint = hintfmt(s, showType(v)),
         .nixCode = NixCode { .errPos = pos }
     });

src/libexpr/eval.cc

@@ -161,12 +161,12 @@ const Value *getPrimOp(const Value &v) {
 }
 
 
-string showType(const Value & v)
+string showType(ValueType type)
 {
-    switch (v.type) {
+    switch (type) {
         case tInt: return "an integer";
-        case tBool: return "a boolean";
+        case tBool: return "a Boolean";
-        case tString: return v.string.context ? "a string with context" : "a string";
+        case tString: return "a string";
         case tPath: return "a path";
         case tNull: return "null";
         case tAttrs: return "a set";
@@ -175,14 +175,27 @@ string showType(const Value & v)
         case tApp: return "a function application";
         case tLambda: return "a function";
         case tBlackhole: return "a black hole";
+        case tPrimOp: return "a built-in function";
+        case tPrimOpApp: return "a partially applied built-in function";
+        case tExternal: return "an external value";
+        case tFloat: return "a float";
+    }
+    abort();
+}
+
+
+string showType(const Value & v)
+{
+    switch (v.type) {
+        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));
         case tPrimOpApp:
             return fmt("the partially applied built-in function '%s'", string(getPrimOp(v)->primOp->name));
         case tExternal: return v.external->showType();
-        case tFloat: return "a float";
+    default:
+        return showType(v.type);
     }
-    abort();
 }
 
 
@@ -323,6 +336,7 @@ EvalState::EvalState(const Strings & _searchPath, ref<Store> store)
     , sOutputHash(symbols.create("outputHash"))
     , sOutputHashAlgo(symbols.create("outputHashAlgo"))
     , sOutputHashMode(symbols.create("outputHashMode"))
+    , sRecurseForDerivations(symbols.create("recurseForDerivations"))
     , repair(NoRepair)
     , store(store)
     , baseEnv(allocEnv(128))
@@ -471,14 +485,21 @@ Value * EvalState::addConstant(const string & name, Value & v)
 Value * EvalState::addPrimOp(const string & name,
     size_t arity, PrimOpFun primOp)
 {
+    auto name2 = string(name, 0, 2) == "__" ? string(name, 2) : name;
+    Symbol sym = symbols.create(name2);
+
+    /* Hack to make constants lazy: turn them into a application of
+       the primop to a dummy value. */
     if (arity == 0) {
+        auto vPrimOp = allocValue();
+        vPrimOp->type = tPrimOp;
+        vPrimOp->primOp = new PrimOp(primOp, 1, sym);
         Value v;
-        primOp(*this, noPos, nullptr, v);
+        mkApp(v, *vPrimOp, *vPrimOp);
         return addConstant(name, v);
     }
+
     Value * v = allocValue();
-    string name2 = string(name, 0, 2) == "__" ? string(name, 2) : name;
-    Symbol sym = symbols.create(name2);
     v->type = tPrimOp;
     v->primOp = new PrimOp(primOp, arity, sym);
     staticBaseEnv.vars[symbols.create(name)] = baseEnvDispl;
@@ -506,8 +527,7 @@ LocalNoInlineNoReturn(void throwEvalError(const char * s, const string & s2))
 
 LocalNoInlineNoReturn(void throwEvalError(const Pos & pos, const char * s, const string & s2))
 {
-    throw EvalError(
+    throw EvalError({
-        ErrorInfo { 
         .hint = hintfmt(s, s2),
         .nixCode = NixCode { .errPos = pos }
     });
@@ -520,8 +540,7 @@ LocalNoInlineNoReturn(void throwEvalError(const char * s, const string & s2, con
 
 LocalNoInlineNoReturn(void throwEvalError(const Pos & pos, const char * s, const string & s2, const string & s3))
 {
-    throw EvalError(
+    throw EvalError({
-        ErrorInfo { 
         .hint = hintfmt(s, s2, s3),
         .nixCode = NixCode { .errPos = pos }
     });
@@ -530,8 +549,7 @@ LocalNoInlineNoReturn(void throwEvalError(const Pos & pos, const char * s, const
 LocalNoInlineNoReturn(void throwEvalError(const Pos & p1, const char * s, const Symbol & sym, const Pos & p2))
 {
     // p1 is where the error occurred; p2 is a position mentioned in the message.
-    throw EvalError(
+    throw EvalError({
-        ErrorInfo { 
         .hint = hintfmt(s, sym, p2),
         .nixCode = NixCode { .errPos = p1 }
     });
@@ -539,8 +557,7 @@ LocalNoInlineNoReturn(void throwEvalError(const Pos & p1, const char * s, const
 
 LocalNoInlineNoReturn(void throwTypeError(const Pos & pos, const char * s))
 {
-    throw TypeError(
+    throw TypeError({
-        ErrorInfo { 
         .hint = hintfmt(s),
         .nixCode = NixCode { .errPos = pos }
     });
@@ -553,8 +570,7 @@ LocalNoInlineNoReturn(void throwTypeError(const char * s, const string & s1))
 
 LocalNoInlineNoReturn(void throwTypeError(const Pos & pos, const char * s, const ExprLambda & fun, const Symbol & s2))
 {
-    throw TypeError(
+    throw TypeError({
-        ErrorInfo { 
         .hint = hintfmt(s, fun.showNamePos(), s2),
         .nixCode = NixCode { .errPos = pos }
     });
@@ -562,8 +578,7 @@ LocalNoInlineNoReturn(void throwTypeError(const Pos & pos, const char * s, const
 
 LocalNoInlineNoReturn(void throwAssertionError(const Pos & pos, const char * s, const string & s1))
 {
-    throw AssertionError(
+    throw AssertionError({
-        ErrorInfo { 
         .hint = hintfmt(s, s1),
         .nixCode = NixCode { .errPos = pos }
     });
@@ -571,8 +586,7 @@ LocalNoInlineNoReturn(void throwAssertionError(const Pos & pos, const char * s,
 
 LocalNoInlineNoReturn(void throwUndefinedVarError(const Pos & pos, const char * s, const string & s1))
 {
-    throw UndefinedVarError(
+    throw UndefinedVarError({
-        ErrorInfo { 
         .hint = hintfmt(s, s1),
         .nixCode = NixCode { .errPos = pos }
     });
@@ -1920,8 +1934,7 @@ void EvalState::printStats()
 
 string ExternalValueBase::coerceToString(const Pos & pos, PathSet & context, bool copyMore, bool copyToStore) const
 {
-    throw TypeError(
+    throw TypeError({
-        ErrorInfo { 
         .hint = hintfmt("cannot coerce %1% to a string", showType()),
         .nixCode = NixCode { .errPos = pos }
     });

src/libexpr/eval.hh

@@ -18,7 +18,7 @@ namespace nix {
 
 class Store;
 class EvalState;
-struct StorePath;
+class StorePath;
 enum RepairFlag : bool;
 
 
@@ -74,7 +74,8 @@ public:
         sSystem, sOverrides, sOutputs, sOutputName, sIgnoreNulls,
         sFile, sLine, sColumn, sFunctor, sToString,
         sRight, sWrong, sStructuredAttrs, sBuilder, sArgs,
-        sOutputHash, sOutputHashAlgo, sOutputHashMode;
+        sOutputHash, sOutputHashAlgo, sOutputHashMode,
+        sRecurseForDerivations;
     Symbol sDerivationNix;
 
     /* If set, force copying files to the Nix store even if they
@@ -324,6 +325,7 @@ private:
 
 
 /* Return a string representing the type of the value `v'. */
+string showType(ValueType type);
 string showType(const Value & v);
 
 /* Decode a context string ‘!<name>!<path>’ into a pair <path,

src/libexpr/get-drvs.cc

@@ -348,7 +348,7 @@ static void getDerivations(EvalState & state, Value & vIn,
                    should we recurse into it?  => Only if it has a
                    `recurseForDerivations = true' attribute. */
                 if (i->value->type == tAttrs) {
-                    Bindings::iterator j = i->value->attrs->find(state.symbols.create("recurseForDerivations"));
+                    Bindings::iterator j = i->value->attrs->find(state.sRecurseForDerivations);
                     if (j != i->value->attrs->end() && state.forceBool(*j->value, *j->pos))
                         getDerivations(state, *i->value, pathPrefix2, autoArgs, drvs, done, ignoreAssertionFailures);
                 }

src/libexpr/lexer.l

@@ -219,4 +219,3 @@ or          { return OR_KW; }
             }
 
 %%
-

src/libexpr/local.mk

@@ -8,7 +8,7 @@ libexpr_SOURCES := $(wildcard $(d)/*.cc) $(wildcard $(d)/primops/*.cc) $(d)/lexe
 
 libexpr_CXXFLAGS += -I src/libutil -I src/libstore -I src/libfetchers -I src/libmain -I src/libexpr
 
-libexpr_LIBS = libutil libstore libfetchers libnixrust
+libexpr_LIBS = libutil libstore libfetchers
 
 libexpr_LDFLAGS =
 ifneq ($(OS), FreeBSD)

src/libexpr/nixexpr.cc

@@ -283,8 +283,7 @@ void ExprVar::bindVars(const StaticEnv & env)
        enclosing `with'.  If there is no `with', then we can issue an
        "undefined variable" error now. */
     if (withLevel == -1)
-        throw UndefinedVarError(
+        throw UndefinedVarError({
-            ErrorInfo {
             .hint = hintfmt("undefined variable '%1%'", name),
             .nixCode = NixCode { .errPos = pos }
         });

src/libexpr/nixexpr.hh

@@ -237,8 +237,7 @@ struct ExprLambda : Expr
         : pos(pos), arg(arg), matchAttrs(matchAttrs), formals(formals), body(body)
     {
         if (!arg.empty() && formals && formals->argNames.find(arg) != formals->argNames.end())
-            throw ParseError(
+            throw ParseError({
-                ErrorInfo {
                 .hint = hintfmt("duplicate formal function argument '%1%'", arg),
                 .nixCode = NixCode { .errPos = pos }
             });

src/libexpr/parser.y

@@ -65,8 +65,7 @@ namespace nix {
 
 static void dupAttr(const AttrPath & attrPath, const Pos & pos, const Pos & prevPos)
 {
-    throw ParseError(
+    throw ParseError({
-        ErrorInfo {
         .hint = hintfmt("attribute '%1%' already defined at %2%",
             showAttrPath(attrPath), prevPos),
         .nixCode = NixCode { .errPos = pos },
@@ -76,10 +75,8 @@ static void dupAttr(const AttrPath & attrPath, const Pos & pos, const Pos & prev
 
 static void dupAttr(Symbol attr, const Pos & pos, const Pos & prevPos)
 {
-    throw ParseError(
+    throw ParseError({
-        ErrorInfo {
+        .hint = hintfmt("attribute '%1%' already defined at %2%", attr, prevPos),
-            .hint = hintfmt("attribute '%1%' already defined at %2%",
-                attr, prevPos),
         .nixCode = NixCode { .errPos = pos },
     });
 }
@@ -149,8 +146,7 @@ static void addAttr(ExprAttrs * attrs, AttrPath & attrPath,
 static void addFormal(const Pos & pos, Formals * formals, const Formal & formal)
 {
     if (!formals->argNames.insert(formal.name).second)
-        throw ParseError(
+        throw ParseError({
-            ErrorInfo {
             .hint = hintfmt("duplicate formal function argument '%1%'",
                 formal.name),
             .nixCode = NixCode { .errPos = pos },
@@ -262,7 +258,7 @@ static inline Pos makeCurPos(const YYLTYPE & loc, ParseData * data)
 
 void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * error)
 {
-    data->error = ErrorInfo { 
+    data->error = {
         .hint = hintfmt(error),
         .nixCode = NixCode { .errPos = makeCurPos(*loc, data) }
     };
@@ -342,8 +338,7 @@ expr_function
     { $$ = new ExprWith(CUR_POS, $2, $4); }
   | LET binds IN expr_function
     { if (!$2->dynamicAttrs.empty())
-        throw ParseError(
+        throw ParseError({
-            ErrorInfo {
             .hint = hintfmt("dynamic attributes not allowed in let"),
             .nixCode = NixCode { .errPos = CUR_POS },
         });
@@ -423,8 +418,7 @@ expr_simple
   | URI {
       static bool noURLLiterals = settings.isExperimentalFeatureEnabled("no-url-literals");
       if (noURLLiterals)
-          throw ParseError(
+          throw ParseError({
-              ErrorInfo { 
               .hint = hintfmt("URL literals are disabled"),
               .nixCode = NixCode { .errPos = CUR_POS }
           });
@@ -497,8 +491,7 @@ attrs
           $$->push_back(AttrName(str->s));
           delete str;
       } else
-          throw ParseError(
+          throw ParseError({
-              ErrorInfo {
               .hint = hintfmt("dynamic attributes not allowed in inherit"),
               .nixCode = NixCode { .errPos = makeCurPos(@2, data) },
           });
@@ -707,9 +700,11 @@ Path EvalState::findFile(SearchPath & searchPath, const string & path, const Pos
         Path res = r.second + suffix;
         if (pathExists(res)) return canonPath(res);
     }
-    throw ThrownError(
+    throw ThrownError({
-        ErrorInfo { 
+        .hint = hintfmt(evalSettings.pureEval
-            .hint = hintfmt("file '%1%' was not found in the Nix search path (add it using $NIX_PATH or -I)", path),
+            ? "cannot look up '<%s>' in pure evaluation mode (use '--impure' to override)"
+            : "file '%s' was not found in the Nix search path (add it using $NIX_PATH or -I)",
+            path),
         .nixCode = NixCode { .errPos = pos }
     });
 }
@@ -727,8 +722,7 @@ std::pair<bool, std::string> EvalState::resolveSearchPathElem(const SearchPathEl
             res = { true, store->toRealPath(fetchers::downloadTarball(
                         store, resolveUri(elem.second), "source", false).storePath) };
         } catch (FileTransferError & e) {
-            logWarning(
+            logWarning({
-                ErrorInfo { 
                 .name = "Entry download",
                 .hint = hintfmt("Nix search path entry '%1%' cannot be downloaded, ignoring", elem.second)
             });
@@ -739,8 +733,7 @@ std::pair<bool, std::string> EvalState::resolveSearchPathElem(const SearchPathEl
         if (pathExists(path))
             res = { true, path };
         else {
-            logWarning(
+            logWarning({
-                ErrorInfo { 
                 .name = "Entry not found",
                 .hint = hintfmt("warning: Nix search path entry '%1%' does not exist, ignoring", elem.second)
             });

src/libexpr/primops.cc

@@ -50,20 +50,20 @@ void EvalState::realiseContext(const PathSet & context)
     std::vector<StorePathWithOutputs> drvs;
 
     for (auto & i : context) {
-        std::pair<string, string> decoded = decodeContext(i);
+        auto [ctxS, outputName] = decodeContext(i);
-        auto ctx = store->parseStorePath(decoded.first);
+        auto ctx = store->parseStorePath(ctxS);
         if (!store->isValidPath(ctx))
             throw InvalidPathError(store->printStorePath(ctx));
-        if (!decoded.second.empty() && ctx.isDerivation()) {
+        if (!outputName.empty() && ctx.isDerivation()) {
-            drvs.push_back(StorePathWithOutputs{ctx.clone(), {decoded.second}});
+            drvs.push_back(StorePathWithOutputs{ctx, {outputName}});
 
             /* Add the output of this derivation to the allowed
                paths. */
             if (allowedPaths) {
-                auto drv = store->derivationFromPath(store->parseStorePath(decoded.first));
+                auto drv = store->derivationFromPath(ctx);
-                DerivationOutputs::iterator i = drv.outputs.find(decoded.second);
+                DerivationOutputs::iterator i = drv.outputs.find(outputName);
                 if (i == drv.outputs.end())
-                    throw Error("derivation '%s' does not have an output named '%s'", decoded.first, decoded.second);
+                    throw Error("derivation '%s' does not have an output named '%s'", ctxS, outputName);
                 allowedPaths->insert(store->printStorePath(i->second.path));
             }
         }
@@ -79,6 +79,7 @@ void EvalState::realiseContext(const PathSet & context)
     StorePathSet willBuild, willSubstitute, unknown;
     unsigned long long downloadSize, narSize;
     store->queryMissing(drvs, willBuild, willSubstitute, unknown, downloadSize, narSize);
+
     store->buildPaths(drvs);
 }
 
@@ -93,10 +94,8 @@ static void prim_scopedImport(EvalState & state, const Pos & pos, Value * * args
     try {
         state.realiseContext(context);
     } catch (InvalidPathError & e) {
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo { 
+            .hint = hintfmt("cannot import '%1%', since path '%2%' is not valid", path, e.path),
-                .hint = hintfmt("cannot import '%1%', since path '%2%' is not valid",
-                        path, e.path),
             .nixCode = NixCode { .errPos = pos }
         });
     }
@@ -174,8 +173,7 @@ void prim_importNative(EvalState & state, const Pos & pos, Value * * args, Value
     try {
         state.realiseContext(context);
     } catch (InvalidPathError & e) {
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo {
             .hint = hintfmt(
                 "cannot import '%1%', since path '%2%' is not valid",
                 path, e.path),
@@ -215,8 +213,7 @@ void prim_exec(EvalState & state, const Pos & pos, Value * * args, Value & v)
     auto elems = args[0]->listElems();
     auto count = args[0]->listSize();
     if (count == 0) {
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo {
             .hint = hintfmt("at least one argument to 'exec' required"),
             .nixCode = NixCode { .errPos = pos }
         });
@@ -230,12 +227,12 @@ void prim_exec(EvalState & state, const Pos & pos, Value * * args, Value & v)
     try {
         state.realiseContext(context);
     } catch (InvalidPathError & e) {
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo {
             .hint = hintfmt("cannot execute '%1%', since path '%2%' is not valid",
                 program, e.path),
             .nixCode = NixCode { .errPos = pos }
-            });}
+        });
+    }
 
     auto output = runProgram(program, true, commandArgs);
     Expr * parsed;
@@ -386,8 +383,7 @@ static void prim_genericClosure(EvalState & state, const Pos & pos, Value * * ar
     Bindings::iterator startSet =
         args[0]->attrs->find(state.symbols.create("startSet"));
     if (startSet == args[0]->attrs->end())
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo {
             .hint = hintfmt("attribute 'startSet' required"),
             .nixCode = NixCode { .errPos = pos }
         });
@@ -401,8 +397,7 @@ static void prim_genericClosure(EvalState & state, const Pos & pos, Value * * ar
     Bindings::iterator op =
         args[0]->attrs->find(state.symbols.create("operator"));
     if (op == args[0]->attrs->end())
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo {
             .hint = hintfmt("attribute 'operator' required"),
             .nixCode = NixCode { .errPos = pos }
         });
@@ -424,8 +419,7 @@ static void prim_genericClosure(EvalState & state, const Pos & pos, Value * * ar
         Bindings::iterator key =
             e->attrs->find(state.symbols.create("key"));
         if (key == e->attrs->end())
-            throw EvalError(
+            throw EvalError({
-                ErrorInfo {
                 .hint = hintfmt("attribute 'key' required"),
                 .nixCode = NixCode { .errPos = pos }
             });
@@ -560,8 +554,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
     /* Figure out the name first (for stack backtraces). */
     Bindings::iterator attr = args[0]->attrs->find(state.sName);
     if (attr == args[0]->attrs->end())
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo {
             .hint = hintfmt("required attribute 'name' missing"),
             .nixCode = NixCode { .errPos = pos }
         });
@@ -608,8 +601,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
             if (s == "recursive") ingestionMethod = FileIngestionMethod::Recursive;
             else if (s == "flat") ingestionMethod = FileIngestionMethod::Flat;
             else
-                throw EvalError(
+                throw EvalError({
-                    ErrorInfo { 
                     .hint = hintfmt("invalid value '%s' for 'outputHashMode' attribute", s),
                     .nixCode = NixCode { .errPos = posDrvName }
                 });
@@ -619,8 +611,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
             outputs.clear();
             for (auto & j : ss) {
                 if (outputs.find(j) != outputs.end())
-                    throw EvalError(
+                    throw EvalError({
-                        ErrorInfo { 
                         .hint = hintfmt("duplicate derivation output '%1%'", j),
                         .nixCode = NixCode { .errPos = posDrvName }
                     });
@@ -630,16 +621,14 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
                    then we'd have an attribute ‘drvPath’ in
                    the resulting set. */
                 if (j == "drv")
-                    throw EvalError(
+                    throw EvalError({
-                        ErrorInfo { 
                         .hint = hintfmt("invalid derivation output name 'drv'" ),
                         .nixCode = NixCode { .errPos = posDrvName }
                     });
                 outputs.insert(j);
             }
             if (outputs.empty())
-                throw EvalError(
+                throw EvalError({
-                    ErrorInfo { 
                     .hint = hintfmt("derivation cannot have an empty set of outputs"),
                     .nixCode = NixCode { .errPos = posDrvName }
                 });
@@ -735,9 +724,9 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
             StorePathSet refs;
             state.store->computeFSClosure(state.store->parseStorePath(std::string_view(path).substr(1)), refs);
             for (auto & j : refs) {
-                drv.inputSrcs.insert(j.clone());
+                drv.inputSrcs.insert(j);
                 if (j.isDerivation())
-                    drv.inputDrvs[j.clone()] = state.store->queryDerivationOutputNames(j);
+                    drv.inputDrvs[j] = state.store->readDerivation(j).outputNames();
             }
         }
 
@@ -754,23 +743,20 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
 
     /* Do we have all required attributes? */
     if (drv.builder == "")
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo { 
             .hint = hintfmt("required attribute 'builder' missing"),
             .nixCode = NixCode { .errPos = posDrvName }
         });
 
     if (drv.platform == "")
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo { 
             .hint = hintfmt("required attribute 'system' missing"),
             .nixCode = NixCode { .errPos = posDrvName }
         });
 
     /* Check whether the derivation name is valid. */
     if (isDerivation(drvName))
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo { 
             .hint = hintfmt("derivation names are not allowed to end in '%s'", drvExtension),
             .nixCode = NixCode { .errPos = posDrvName }
         });
@@ -778,14 +764,14 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
     if (outputHash) {
         /* Handle fixed-output derivations. */
         if (outputs.size() != 1 || *(outputs.begin()) != "out")
-            throw Error(
+            throw Error({
-                ErrorInfo { 
                 .hint = hintfmt("multiple outputs are not supported in fixed-output derivations"),
                 .nixCode = NixCode { .errPos = posDrvName }
             });
 
         HashType ht = outputHashAlgo.empty() ? htUnknown : parseHashType(outputHashAlgo);
-        Hash h(*outputHash, ht);
+
+        Hash h = newHashAllowEmpty(*outputHash, ht);
 
         auto outPath = state.store->makeFixedOutputPath(ingestionMethod, h, drvName);
         if (!jsonObject) drv.env["out"] = state.store->printStorePath(outPath);
@@ -807,7 +793,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
         for (auto & i : outputs) {
             if (!jsonObject) drv.env[i] = "";
             drv.outputs.insert_or_assign(i,
-                DerivationOutput(StorePath::dummy.clone(), "", ""));
+                DerivationOutput { StorePath::dummy, "", "" });
         }
 
         Hash h = hashDerivationModulo(*state.store, Derivation(drv), true);
@@ -816,7 +802,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
             auto outPath = state.store->makeOutputPath(i, h, drvName);
             if (!jsonObject) drv.env[i] = state.store->printStorePath(outPath);
             drv.outputs.insert_or_assign(i,
-                DerivationOutput(std::move(outPath), "", ""));
+                DerivationOutput { std::move(outPath), "", "" });
         }
     }
 
@@ -829,7 +815,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
     /* Optimisation, but required in read-only mode! because in that
        case we don't actually write store derivations, so we can't
        read them later. */
-    drvHashes.insert_or_assign(drvPath.clone(),
+    drvHashes.insert_or_assign(drvPath,
         hashDerivationModulo(*state.store, Derivation(drv), false));
 
     state.mkAttrs(v, 1 + drv.outputs.size());
@@ -886,8 +872,7 @@ static void prim_storePath(EvalState & state, const Pos & pos, Value * * args, V
        e.g. nix-push does the right thing. */
     if (!state.store->isStorePath(path)) path = canonPath(path, true);
     if (!state.store->isInStore(path))
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo {
             .hint = hintfmt("path '%1%' is not in the Nix store", path),
             .nixCode = NixCode { .errPos = pos }
         });
@@ -906,8 +891,7 @@ static void prim_pathExists(EvalState & state, const Pos & pos, Value * * args,
     try {
         state.realiseContext(context);
     } catch (InvalidPathError & e) {
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo {
             .hint = hintfmt(
                 "cannot check the existence of '%1%', since path '%2%' is not valid",
                 path, e.path),
@@ -955,10 +939,8 @@ static void prim_readFile(EvalState & state, const Pos & pos, Value * * args, Va
     try {
         state.realiseContext(context);
     } catch (InvalidPathError & e) {
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo {
+            .hint = hintfmt("cannot read '%1%', since path '%2%' is not valid", path, e.path),
-                .hint = hintfmt("cannot read '%1%', since path '%2%' is not valid"
-                     , path, e.path),
             .nixCode = NixCode { .errPos = pos }
         });
     }
@@ -988,8 +970,7 @@ static void prim_findFile(EvalState & state, const Pos & pos, Value * * args, Va
 
         i = v2.attrs->find(state.symbols.create("path"));
         if (i == v2.attrs->end())
-            throw EvalError(
+            throw EvalError({
-                ErrorInfo {
                 .hint = hintfmt("attribute 'path' missing"),
                 .nixCode = NixCode { .errPos = pos }
             });
@@ -1000,10 +981,8 @@ static void prim_findFile(EvalState & state, const Pos & pos, Value * * args, Va
         try {
             state.realiseContext(context);
         } catch (InvalidPathError & e) {
-            throw EvalError(
+            throw EvalError({
-                ErrorInfo {
+                .hint = hintfmt("cannot find '%1%', since path '%2%' is not valid", path, e.path),
-                    .hint = hintfmt("cannot find '%1%', since path '%2%' is not valid",
-                        path, e.path),
                 .nixCode = NixCode { .errPos = pos }
             });
         }
@@ -1022,8 +1001,7 @@ static void prim_hashFile(EvalState & state, const Pos & pos, Value * * args, Va
     string type = state.forceStringNoCtx(*args[0], pos);
     HashType ht = parseHashType(type);
     if (ht == htUnknown)
-      throw Error(
+      throw Error({
-          ErrorInfo {
           .hint = hintfmt("unknown hash type '%1%'", type),
           .nixCode = NixCode { .errPos = pos }
       });
@@ -1042,10 +1020,8 @@ static void prim_readDir(EvalState & state, const Pos & pos, Value * * args, Val
     try {
         state.realiseContext(ctx);
     } catch (InvalidPathError & e) {
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo {
+            .hint = hintfmt("cannot read '%1%', since path '%2%' is not valid", path, e.path),
-                .hint = hintfmt("cannot read '%1%', since path '%2%' is not valid",
-                        path, e.path),
             .nixCode = NixCode { .errPos = pos }
         });
     }
@@ -1117,13 +1093,11 @@ static void prim_toFile(EvalState & state, const Pos & pos, Value * * args, Valu
 
     for (auto path : context) {
         if (path.at(0) != '/')
-            throw EvalError(
+            throw EvalError( {
-                ErrorInfo { 
                 .hint = hintfmt(
                     "in 'toFile': the file named '%1%' must not contain a reference "
                     "to a derivation but contains (%2%)",
-                        name,
+                    name, path),
-                        path),
                 .nixCode = NixCode { .errPos = pos }
             });
         refs.insert(state.store->parseStorePath(path));
@@ -1193,16 +1167,14 @@ 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(
+        throw EvalError({
-            ErrorInfo { 
             .hint = hintfmt("string '%1%' cannot refer to other paths", path),
             .nixCode = NixCode { .errPos = pos }
         });
 
     state.forceValue(*args[0], pos);
     if (args[0]->type != tLambda)
-        throw TypeError(
+        throw TypeError({
-            ErrorInfo { 
             .hint = hintfmt(
                 "first argument in call to 'filterSource' is not a function but %1%",
                 showType(*args[0])),
@@ -1227,10 +1199,8 @@ static void prim_path(EvalState & state, const Pos & pos, Value * * args, Value
             PathSet context;
             path = state.coerceToPath(*attr.pos, *attr.value, context);
             if (!context.empty())
-                throw EvalError(
+                throw EvalError({
-                    ErrorInfo { 
+                    .hint = hintfmt("string '%1%' cannot refer to other paths", path),
-                        .hint = hintfmt("string '%1%' cannot refer to other paths", 
-                            path),
                     .nixCode = NixCode { .errPos = *attr.pos }
                 });
         } else if (attr.name == state.sName)
@@ -1241,18 +1211,15 @@ static void prim_path(EvalState & state, const Pos & pos, Value * * args, Value
         } else if (n == "recursive")
             method = FileIngestionMethod { state.forceBool(*attr.value, *attr.pos) };
         else if (n == "sha256")
-            expectedHash = Hash(state.forceStringNoCtx(*attr.value, *attr.pos), htSHA256);
+            expectedHash = newHashAllowEmpty(state.forceStringNoCtx(*attr.value, *attr.pos), htSHA256);
         else
-            throw EvalError(
+            throw EvalError({
-                ErrorInfo { 
+                .hint = hintfmt("unsupported argument '%1%' to 'addPath'", attr.name),
-                    .hint = hintfmt("unsupported argument '%1%' to 'addPath'",
-                        attr.name),
                 .nixCode = NixCode { .errPos = *attr.pos }
             });
     }
     if (path.empty())
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo { 
             .hint = hintfmt("'path' required"),
             .nixCode = NixCode { .errPos = pos }
         });
@@ -1313,8 +1280,7 @@ void prim_getAttr(EvalState & state, const Pos & pos, Value * * args, Value & v)
     // !!! Should we create a symbol here or just do a lookup?
     Bindings::iterator i = args[1]->attrs->find(state.symbols.create(attr));
     if (i == args[1]->attrs->end())
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo { 
             .hint = hintfmt("attribute '%1%' missing", attr),
             .nixCode = NixCode { .errPos = pos }
         });
@@ -1397,8 +1363,7 @@ static void prim_listToAttrs(EvalState & state, const Pos & pos, Value * * args,
 
         Bindings::iterator j = v2.attrs->find(state.sName);
         if (j == v2.attrs->end())
-            throw TypeError(
+            throw TypeError({
-                ErrorInfo { 
                 .hint = hintfmt("'name' attribute missing in a call to 'listToAttrs'"),
                 .nixCode = NixCode { .errPos = pos }
             });
@@ -1408,8 +1373,7 @@ static void prim_listToAttrs(EvalState & state, const Pos & pos, Value * * args,
         if (seen.insert(sym).second) {
             Bindings::iterator j2 = v2.attrs->find(state.symbols.create(state.sValue));
             if (j2 == v2.attrs->end())
-                throw TypeError(
+                throw TypeError({
-                    ErrorInfo { 
                     .hint = hintfmt("'value' attribute missing in a call to 'listToAttrs'"),
                     .nixCode = NixCode { .errPos = pos }
                 });
@@ -1485,8 +1449,7 @@ static void prim_functionArgs(EvalState & state, const Pos & pos, Value * * args
 {
     state.forceValue(*args[0], pos);
     if (args[0]->type != tLambda)
-        throw TypeError(
+        throw TypeError({
-            ErrorInfo { 
             .hint = hintfmt("'functionArgs' requires a function"),
             .nixCode = NixCode { .errPos = pos }
         });
@@ -1542,8 +1505,7 @@ static void elemAt(EvalState & state, const Pos & pos, Value & list, int n, Valu
 {
     state.forceList(list, pos);
     if (n < 0 || (unsigned int) n >= list.listSize())
-        throw Error(
+        throw Error({
-            ErrorInfo { 
             .hint = hintfmt("list index %1% is out of bounds", n),
             .nixCode = NixCode { .errPos = pos }
         });
@@ -1573,8 +1535,7 @@ static void prim_tail(EvalState & state, const Pos & pos, Value * * args, Value
 {
     state.forceList(*args[0], pos);
     if (args[0]->listSize() == 0)
-        throw Error(
+        throw Error({
-            ErrorInfo { 
             .hint = hintfmt("'tail' called on an empty list"),
             .nixCode = NixCode { .errPos = pos }
         });
@@ -1719,13 +1680,11 @@ static void prim_genList(EvalState & state, const Pos & pos, Value * * args, Val
     auto len = state.forceInt(*args[1], pos);
 
     if (len < 0)
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo { 
             .hint = hintfmt("cannot create list of size %1%", len),
             .nixCode = NixCode { .errPos = pos }
         });
 
-
     state.mkList(v, len);
 
     for (unsigned int n = 0; n < (unsigned int) len; ++n) {
@@ -1883,8 +1842,7 @@ static void prim_div(EvalState & state, const Pos & pos, Value * * args, Value &
 
     NixFloat f2 = state.forceFloat(*args[1], pos);
     if (f2 == 0)
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo { 
             .hint = hintfmt("division by zero"),
             .nixCode = NixCode { .errPos = pos }
         });
@@ -1896,8 +1854,7 @@ static void prim_div(EvalState & state, const Pos & pos, Value * * args, Value &
         NixInt i2 = state.forceInt(*args[1], pos);
         /* Avoid division overflow as it might raise SIGFPE. */
         if (i1 == std::numeric_limits<NixInt>::min() && i2 == -1)
-            throw EvalError(
+            throw EvalError({
-                ErrorInfo { 
                 .hint = hintfmt("overflow in integer division"),
                 .nixCode = NixCode { .errPos = pos }
             });
@@ -1958,8 +1915,7 @@ static void prim_substring(EvalState & state, const Pos & pos, Value * * args, V
     string s = state.coerceToString(pos, *args[2], context);
 
     if (start < 0)
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo { 
             .hint = hintfmt("negative start position in 'substring'"),
             .nixCode = NixCode { .errPos = pos }
         });
@@ -1982,8 +1938,7 @@ static void prim_hashString(EvalState & state, const Pos & pos, Value * * args,
     string type = state.forceStringNoCtx(*args[0], pos);
     HashType ht = parseHashType(type);
     if (ht == htUnknown)
-        throw Error(
+        throw Error({
-            ErrorInfo { 
             .hint = hintfmt("unknown hash type '%1%'", type),
             .nixCode = NixCode { .errPos = pos }
         });
@@ -2029,14 +1984,12 @@ void prim_match(EvalState & state, const Pos & pos, Value * * args, Value & v)
     } catch (std::regex_error &e) {
         if (e.code() == std::regex_constants::error_space) {
             // limit is _GLIBCXX_REGEX_STATE_LIMIT for libstdc++
-            throw EvalError(
+            throw EvalError({
-                ErrorInfo {
                 .hint = hintfmt("memory limit exceeded by regular expression '%s'", re),
                 .nixCode = NixCode { .errPos = pos }
             });
         } else {
-            throw EvalError(
+            throw EvalError({
-                ErrorInfo {
                 .hint = hintfmt("invalid regular expression '%s'", re),
                 .nixCode = NixCode { .errPos = pos }
             });
@@ -2104,14 +2057,12 @@ static void prim_split(EvalState & state, const Pos & pos, Value * * args, Value
     } catch (std::regex_error &e) {
         if (e.code() == std::regex_constants::error_space) {
             // limit is _GLIBCXX_REGEX_STATE_LIMIT for libstdc++
-            throw EvalError(
+            throw EvalError({
-                ErrorInfo {
                 .hint = hintfmt("memory limit exceeded by regular expression '%s'", re),
                 .nixCode = NixCode { .errPos = pos }
             });
         } else {
-            throw EvalError(
+            throw EvalError({
-                ErrorInfo {
                 .hint = hintfmt("invalid regular expression '%s'", re),
                 .nixCode = NixCode { .errPos = pos }
             });
@@ -2145,8 +2096,7 @@ static void prim_replaceStrings(EvalState & state, const Pos & pos, Value * * ar
     state.forceList(*args[0], pos);
     state.forceList(*args[1], pos);
     if (args[0]->listSize() != args[1]->listSize())
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo { 
             .hint = hintfmt("'from' and 'to' arguments to 'replaceStrings' have different lengths"),
             .nixCode = NixCode { .errPos = pos }
         });
@@ -2252,10 +2202,11 @@ static void prim_splitVersion(EvalState & state, const Pos & pos, Value * * args
 RegisterPrimOp::PrimOps * RegisterPrimOp::primOps;
 
 
-RegisterPrimOp::RegisterPrimOp(std::string name, size_t arity, PrimOpFun fun)
+RegisterPrimOp::RegisterPrimOp(std::string name, size_t arity, PrimOpFun fun,
+    std::optional<std::string> requiredFeature)
 {
     if (!primOps) primOps = new PrimOps;
-    primOps->emplace_back(name, arity, fun);
+    primOps->push_back({name, arity, fun, requiredFeature});
 }
 
 
@@ -2447,7 +2398,8 @@ void EvalState::createBaseEnv()
 
     if (RegisterPrimOp::primOps)
         for (auto & primOp : *RegisterPrimOp::primOps)
-            addPrimOp(std::get<0>(primOp), std::get<1>(primOp), std::get<2>(primOp));
+            if (!primOp.requiredFeature || settings.isExperimentalFeatureEnabled(*primOp.requiredFeature))
+                addPrimOp(primOp.name, primOp.arity, primOp.primOp);
 
     /* Now that we've added all primops, sort the `builtins' set,
        because attribute lookups expect it to be sorted. */

src/libexpr/primops.hh

@@ -7,12 +7,25 @@ namespace nix {
 
 struct RegisterPrimOp
 {
-    typedef std::vector<std::tuple<std::string, size_t, PrimOpFun>> PrimOps;
+    struct Info
+    {
+        std::string name;
+        size_t arity;
+        PrimOpFun primOp;
+        std::optional<std::string> requiredFeature;
+    };
+
+    typedef std::vector<Info> PrimOps;
     static PrimOps * primOps;
+
     /* You can register a constant by passing an arity of 0. fun
        will get called during EvalState initialization, so there
        may be primops not yet added and builtins is not yet sorted. */
-    RegisterPrimOp(std::string name, size_t arity, PrimOpFun fun);
+    RegisterPrimOp(
+        std::string name,
+        size_t arity,
+        PrimOpFun fun,
+        std::optional<std::string> requiredFeature = {});
 };
 
 /* These primops are disabled without enableNativeCode, but plugins

src/libexpr/primops/context.cc

@@ -146,8 +146,7 @@ static void prim_appendContext(EvalState & state, const Pos & pos, Value * * arg
     auto sAllOutputs = state.symbols.create("allOutputs");
     for (auto & i : *args[1]->attrs) {
         if (!state.store->isStorePath(i.name))
-            throw EvalError(
+            throw EvalError({
-                ErrorInfo { 
                 .hint = hintfmt("Context key '%s' is not a store path", i.name),
                 .nixCode = NixCode { .errPos = *i.pos }
             });
@@ -164,8 +163,7 @@ static void prim_appendContext(EvalState & state, const Pos & pos, Value * * arg
         if (iter != i.value->attrs->end()) {
             if (state.forceBool(*iter->value, *iter->pos)) {
                 if (!isDerivation(i.name)) {
-                    throw EvalError(
+                    throw EvalError({
-                        ErrorInfo { 
                         .hint = hintfmt("Tried to add all-outputs context of %s, which is not a derivation, to a string", i.name),
                         .nixCode = NixCode { .errPos = *i.pos }
                     });
@@ -178,8 +176,7 @@ static void prim_appendContext(EvalState & state, const Pos & pos, Value * * arg
         if (iter != i.value->attrs->end()) {
             state.forceList(*iter->value, *iter->pos);
             if (iter->value->listSize() && !isDerivation(i.name)) {
-                throw EvalError(
+                throw EvalError({
-                    ErrorInfo { 
                     .hint = hintfmt("Tried to add derivation output context of %s, which is not a derivation, to a string", i.name),
                     .nixCode = NixCode { .errPos = *i.pos }
                 });

src/libexpr/primops/fetchGit.cc

@@ -35,16 +35,14 @@ static void prim_fetchGit(EvalState & state, const Pos & pos, Value * * args, Va
             else if (n == "submodules")
                 fetchSubmodules = state.forceBool(*attr.value, *attr.pos);
             else
-                throw EvalError(
+                throw EvalError({
-                    ErrorInfo { 
                     .hint = hintfmt("unsupported argument '%s' to 'fetchGit'", attr.name),
                     .nixCode = NixCode { .errPos = *attr.pos }
                 });
         }
 
         if (url.empty())
-            throw EvalError(
+            throw EvalError({
-                ErrorInfo { 
                 .hint = hintfmt("'url' argument required"),
                 .nixCode = NixCode { .errPos = pos }
             });

src/libexpr/primops/fetchMercurial.cc

@@ -38,16 +38,14 @@ static void prim_fetchMercurial(EvalState & state, const Pos & pos, Value * * ar
             else if (n == "name")
                 name = state.forceStringNoCtx(*attr.value, *attr.pos);
             else
-                throw EvalError(
+                throw EvalError({
-                    ErrorInfo { 
                     .hint = hintfmt("unsupported argument '%s' to 'fetchMercurial'", attr.name),
                     .nixCode = NixCode { .errPos = *attr.pos }
                 });
         }
 
         if (url.empty())
-            throw EvalError(
+            throw EvalError({
-                ErrorInfo { 
                 .hint = hintfmt("'url' argument required"),
                 .nixCode = NixCode { .errPos = pos }
             });

src/libexpr/primops/fetchTree.cc

@@ -23,7 +23,7 @@ void emitTreeAttrs(
 
     assert(tree.info.narHash);
     mkString(*state.allocAttr(v, state.symbols.create("narHash")),
-        tree.info.narHash.to_string(SRI));
+        tree.info.narHash.to_string(SRI, true));
 
     if (input->getRev()) {
         mkString(*state.allocAttr(v, state.symbols.create("rev")), input->getRev()->gitRev());
@@ -66,8 +66,7 @@ static void prim_fetchTree(EvalState & state, const Pos & pos, Value * * args, V
         }
 
         if (!attrs.count("type"))
-            throw Error(
+            throw Error({
-                ErrorInfo {
                 .hint = hintfmt("attribute 'type' is missing in call to 'fetchTree'"),
                 .nixCode = NixCode { .errPos = pos }
             });
@@ -107,21 +106,18 @@ static void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
             if (n == "url")
                 url = state.forceStringNoCtx(*attr.value, *attr.pos);
             else if (n == "sha256")
-                expectedHash = Hash(state.forceStringNoCtx(*attr.value, *attr.pos), htSHA256);
+                expectedHash = newHashAllowEmpty(state.forceStringNoCtx(*attr.value, *attr.pos), htSHA256);
             else if (n == "name")
                 name = state.forceStringNoCtx(*attr.value, *attr.pos);
             else
-                throw EvalError(
+                throw EvalError({
-                    ErrorInfo {
+                    .hint = hintfmt("unsupported argument '%s' to '%s'", attr.name, who),
-                        .hint = hintfmt("unsupported argument '%s' to '%s'",
-                            attr.name, who),
                     .nixCode = NixCode { .errPos = *attr.pos }
                 });
             }
 
         if (!url)
-            throw EvalError(
+            throw EvalError({
-                ErrorInfo {
                 .hint = hintfmt("'url' argument required"),
                 .nixCode = NixCode { .errPos = pos }
             });
@@ -151,7 +147,7 @@ static void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
             : hashFile(htSHA256, path);
         if (hash != *expectedHash)
             throw Error((unsigned int) 102, "hash mismatch in file downloaded from '%s':\n  wanted: %s\n  got:    %s",
-                *url, expectedHash->to_string(), hash.to_string());
+                *url, expectedHash->to_string(Base32, true), hash.to_string(Base32, true));
     }
 
     if (state.allowedPaths)

src/libexpr/primops/fromTOML.cc

@@ -81,8 +81,7 @@ static void prim_fromTOML(EvalState & state, const Pos & pos, Value * * args, Va
     try {
         visit(v, parser(tomlStream).parse());
     } catch (std::runtime_error & e) {
-        throw EvalError(
+        throw EvalError({
-            ErrorInfo {
             .hint = hintfmt("while parsing a TOML string: %s", e.what()),
             .nixCode = NixCode { .errPos = pos }
         });

src/libfetchers/fetchers.cc

@@ -36,7 +36,7 @@ std::unique_ptr<Input> inputFromAttrs(const Attrs & attrs)
         if (res) {
             if (auto narHash = maybeGetStrAttr(attrs, "narHash"))
                 // FIXME: require SRI hash.
-                res->narHash = Hash(*narHash);
+                res->narHash = newHashAllowEmpty(*narHash, htUnknown);
             return res;
         }
     }
@@ -47,7 +47,7 @@ Attrs Input::toAttrs() const
 {
     auto attrs = toAttrsInternal();
     if (narHash)
-        attrs.emplace("narHash", narHash->to_string(SRI));
+        attrs.emplace("narHash", narHash->to_string(SRI, true));
     attrs.emplace("type", type());
     return attrs;
 }
@@ -67,7 +67,7 @@ std::pair<Tree, std::shared_ptr<const Input>> Input::fetchTree(ref<Store> store)
 
     if (narHash && narHash != input->narHash)
         throw Error("NAR hash mismatch in input '%s' (%s), expected '%s', got '%s'",
-            to_string(), tree.actualPath, narHash->to_string(SRI), input->narHash->to_string(SRI));
+            to_string(), tree.actualPath, narHash->to_string(SRI, true), input->narHash->to_string(SRI, true));
 
     return {std::move(tree), input};
 }

src/libfetchers/github.cc

@@ -76,7 +76,7 @@ struct GitHubInput : Input
                 readFile(
                     store->toRealPath(
                         downloadFile(store, url, "source", false).storePath)));
-            rev = Hash(json["sha"], htSHA1);
+            rev = Hash(std::string { json["sha"] }, htSHA1);
             debug("HEAD revision for '%s' is %s", url, rev->gitRev());
         }
 

src/libfetchers/local.mk

@@ -8,4 +8,4 @@ libfetchers_SOURCES := $(wildcard $(d)/*.cc)
 
 libfetchers_CXXFLAGS += -I src/libutil -I src/libstore
 
-libfetchers_LIBS = libutil libstore libnixrust
+libfetchers_LIBS = libutil libstore

src/libfetchers/tarball.cc

@@ -196,9 +196,9 @@ struct TarballInput : Input
         // NAR hashes are preferred over file hashes since tar/zip files
         // don't have a canonical representation.
         if (narHash)
-            url2.query.insert_or_assign("narHash", narHash->to_string(SRI));
+            url2.query.insert_or_assign("narHash", narHash->to_string(SRI, true));
         else if (hash)
-            url2.query.insert_or_assign("hash", hash->to_string(SRI));
+            url2.query.insert_or_assign("hash", hash->to_string(SRI, true));
         return url2;
     }
 
@@ -207,7 +207,7 @@ struct TarballInput : Input
         Attrs attrs;
         attrs.emplace("url", url.to_string());
         if (hash)
-            attrs.emplace("hash", hash->to_string(SRI));
+            attrs.emplace("hash", hash->to_string(SRI, true));
         return attrs;
     }
 
@@ -264,8 +264,7 @@ struct TarballInputScheme : InputScheme
 
         auto input = std::make_unique<TarballInput>(parseURL(getStrAttr(attrs, "url")));
         if (auto hash = maybeGetStrAttr(attrs, "hash"))
-            // FIXME: require SRI hash.
+            input->hash = newHashAllowEmpty(*hash, htUnknown);
-            input->hash = Hash(*hash);
 
         return input;
     }

src/libmain/common-args.cc

@@ -1,5 +1,6 @@
 #include "common-args.hh"
 #include "globals.hh"
+#include "loggers.hh"
 
 namespace nix {
 
@@ -38,6 +39,14 @@ MixCommonArgs::MixCommonArgs(const string & programName)
         }},
     });
 
+    addFlag({
+        .longName = "log-format",
+        .description = "format of log output; \"raw\", \"internal-json\", \"bar\" "
+                        "or \"bar-with-logs\"",
+        .labels = {"format"},
+        .handler = {[](std::string format) { setLogFormat(format); }},
+    });
+
     addFlag({
         .longName = "max-jobs",
         .shortName = 'j',

src/libmain/loggers.cc

@@ -0,0 +1,52 @@
+#include "loggers.hh"
+#include "progress-bar.hh"
+
+namespace nix {
+
+LogFormat defaultLogFormat = LogFormat::raw;
+
+LogFormat parseLogFormat(const std::string & logFormatStr) {
+    if (logFormatStr == "raw")
+        return LogFormat::raw;
+    else if (logFormatStr == "raw-with-logs")
+        return LogFormat::rawWithLogs;
+    else if (logFormatStr == "internal-json")
+        return LogFormat::internalJson;
+    else if (logFormatStr == "bar")
+        return LogFormat::bar;
+    else if (logFormatStr == "bar-with-logs")
+        return LogFormat::barWithLogs;
+    throw Error("option 'log-format' has an invalid value '%s'", logFormatStr);
+}
+
+Logger * makeDefaultLogger() {
+    switch (defaultLogFormat) {
+    case LogFormat::raw:
+        return makeSimpleLogger(false);
+    case LogFormat::rawWithLogs:
+        return makeSimpleLogger(true);
+    case LogFormat::internalJson:
+        return makeJSONLogger(*makeSimpleLogger());
+    case LogFormat::bar:
+        return makeProgressBar();
+    case LogFormat::barWithLogs:
+        return makeProgressBar(true);
+    default:
+        abort();
+    }
+}
+
+void setLogFormat(const std::string & logFormatStr) {
+    setLogFormat(parseLogFormat(logFormatStr));
+}
+
+void setLogFormat(const LogFormat & logFormat) {
+    defaultLogFormat = logFormat;
+    createDefaultLogger();
+}
+
+void createDefaultLogger() {
+    logger = makeDefaultLogger();
+}
+
+}

src/libmain/loggers.hh

@@ -0,0 +1,20 @@
+#pragma once
+
+#include "types.hh"
+
+namespace nix {
+
+enum class LogFormat {
+  raw,
+  rawWithLogs,
+  internalJson,
+  bar,
+  barWithLogs,
+};
+
+void setLogFormat(const std::string & logFormatStr);
+void setLogFormat(const LogFormat & logFormat);
+
+void createDefaultLogger();
+
+}

src/libmain/progress-bar.cc

@@ -106,19 +106,20 @@ public:
         updateThread.join();
     }
 
-    void stop()
+    void stop() override
     {
         auto state(state_.lock());
         if (!state->active) return;
         state->active = false;
-        std::string status = getStatus(*state);
         writeToStderr("\r\e[K");
-        if (status != "")
-            writeToStderr("[" + status + "]\n");
         updateCV.notify_one();
         quitCV.notify_one();
     }
 
+    bool isVerbose() override {
+        return printBuildLogs;
+    }
+
     void log(Verbosity lvl, const FormatOrString & fs) override
     {
         auto state(state_.lock());
@@ -152,7 +153,7 @@ public:
     {
         auto state(state_.lock());
 
-        if (lvl <= verbosity && !s.empty())
+        if (lvl <= verbosity && !s.empty() && type != actBuildWaiting)
             log(*state, lvl, s + "...");
 
         state->activities.emplace_back(ActInfo());
@@ -164,7 +165,7 @@ public:
         state->activitiesByType[type].its.emplace(act, i);
 
         if (type == actBuild) {
-            auto name = storePathToName(getS(fields, 0));
+            std::string name(storePathToName(getS(fields, 0)));
             if (hasSuffix(name, ".drv"))
                 name = name.substr(0, name.size() - 4);
             i->s = fmt("building " ANSI_BOLD "%s" ANSI_NORMAL, name);
@@ -467,11 +468,17 @@ public:
     }
 };
 
+Logger * makeProgressBar(bool printBuildLogs)
+{
+    return new ProgressBar(
+        printBuildLogs,
+        isatty(STDERR_FILENO) && getEnv("TERM").value_or("dumb") != "dumb"
+    );
+}
+
 void startProgressBar(bool printBuildLogs)
 {
-    logger = new ProgressBar(
+    logger = makeProgressBar(printBuildLogs);
-        printBuildLogs,
-        isatty(STDERR_FILENO) && getEnv("TERM").value_or("dumb") != "dumb");
 }
 
 void stopProgressBar()

src/libmain/progress-bar.hh

@@ -4,6 +4,8 @@
 
 namespace nix {
 
+Logger * makeProgressBar(bool printBuildLogs = false);
+
 void startProgressBar(bool printBuildLogs = false);
 
 void stopProgressBar();

src/libmain/shared.cc

@@ -2,6 +2,7 @@
 #include "shared.hh"
 #include "store-api.hh"
 #include "util.hh"
+#include "loggers.hh"
 
 #include <algorithm>
 #include <cctype>
@@ -47,7 +48,10 @@ void printMissing(ref<Store> store, const StorePathSet & willBuild,
     unsigned long long downloadSize, unsigned long long narSize, Verbosity lvl)
 {
     if (!willBuild.empty()) {
-        printMsg(lvl, "these derivations will be built:");
+        if (willBuild.size() == 1)
+            printMsg(lvl, fmt("this derivation will be built:"));
+        else
+            printMsg(lvl, fmt("these %d derivations will be built:", willBuild.size()));
         auto sorted = store->topoSortPaths(willBuild);
         reverse(sorted.begin(), sorted.end());
         for (auto & i : sorted)
@@ -55,9 +59,18 @@ void printMissing(ref<Store> store, const StorePathSet & willBuild,
     }
 
     if (!willSubstitute.empty()) {
-        printMsg(lvl, fmt("these paths will be fetched (%.2f MiB download, %.2f MiB unpacked):",
+        const float downloadSizeMiB = downloadSize / (1024.f * 1024.f);
-                downloadSize / (1024.0 * 1024.0),
+        const float narSizeMiB = narSize / (1024.f * 1024.f);
-                narSize / (1024.0 * 1024.0)));
+        if (willSubstitute.size() == 1) {
+            printMsg(lvl, fmt("this path will be fetched (%.2f MiB download, %.2f MiB unpacked):",
+                downloadSizeMiB,
+                narSizeMiB));
+        } else {
+            printMsg(lvl, fmt("these %d paths will be fetched (%.2f MiB download, %.2f MiB unpacked):",
+                willSubstitute.size(),
+                downloadSizeMiB,
+                narSizeMiB));
+        }
         for (auto & i : willSubstitute)
             printMsg(lvl, fmt("  %s", store->printStorePath(i)));
     }
@@ -169,7 +182,7 @@ LegacyArgs::LegacyArgs(const std::string & programName,
         .longName = "no-build-output",
         .shortName = 'Q',
         .description = "do not show build output",
-        .handler = {&settings.verboseBuild, false},
+        .handler = {[&]() {setLogFormat(LogFormat::raw); }},
     });
 
     addFlag({
@@ -289,7 +302,7 @@ int handleExceptions(const string & programName, std::function<void()> fun)
 {
     ReceiveInterrupts receiveInterrupts; // FIXME: need better place for this
 
-    ErrorInfo::programName = programName;
+    ErrorInfo::programName = baseNameOf(programName);
 
     string error = ANSI_RED "error:" ANSI_NORMAL " ";
     try {

src/libstore/binary-cache-store.cc

@@ -93,7 +93,7 @@ std::shared_ptr<std::string> BinaryCacheStore::getFile(const std::string & path)
 
 std::string BinaryCacheStore::narInfoFileFor(const StorePath & storePath)
 {
-    return storePathToHash(printStorePath(storePath)) + ".narinfo";
+    return std::string(storePath.hashPart()) + ".narinfo";
 }
 
 void BinaryCacheStore::writeNarInfo(ref<NarInfo> narInfo)
@@ -102,7 +102,7 @@ void BinaryCacheStore::writeNarInfo(ref<NarInfo> narInfo)
 
     upsertFile(narInfoFile, narInfo->to_string(*this), "text/x-nix-narinfo");
 
-    auto hashPart = storePathToHash(printStorePath(narInfo->path));
+    std::string hashPart(narInfo->path.hashPart());
 
     {
         auto state_(state.lock());
@@ -164,7 +164,7 @@ void BinaryCacheStore::addToStore(const ValidPathInfo & info, Source & narSource
             }
         }
 
-        upsertFile(storePathToHash(printStorePath(info.path)) + ".ls", jsonOut.str(), "application/json");
+        upsertFile(std::string(info.path.to_string()) + ".ls", jsonOut.str(), "application/json");
     }
 
     /* Compress the NAR. */
@@ -360,7 +360,7 @@ StorePath BinaryCacheStore::addTextToStore(const string & name, const string & s
     const StorePathSet & references, RepairFlag repair)
 {
     ValidPathInfo info(computeStorePathForText(name, s, references));
-    info.references = cloneStorePathSet(references);
+    info.references = references;
 
     if (repair || !isValidPath(info.path)) {
         StringSink sink;
@@ -388,21 +388,19 @@ void BinaryCacheStore::addSignatures(const StorePath & storePath, const StringSe
 
     narInfo->sigs.insert(sigs.begin(), sigs.end());
 
-    auto narInfoFile = narInfoFileFor(narInfo->path);
-
     writeNarInfo(narInfo);
 }
 
 std::shared_ptr<std::string> BinaryCacheStore::getBuildLog(const StorePath & path)
 {
-    auto drvPath = path.clone();
+    auto drvPath = path;
 
     if (!path.isDerivation()) {
         try {
             auto info = queryPathInfo(path);
             // FIXME: add a "Log" field to .narinfo
             if (!info->deriver) return nullptr;
-            drvPath = info->deriver->clone();
+            drvPath = *info->deriver;
         } catch (InvalidPath &) {
             return nullptr;
         }

src/libstore/build.cc

@@ -86,7 +86,7 @@ struct HookInstance;
 
 
 /* A pointer to a goal. */
-class Goal;
+struct Goal;
 class DerivationGoal;
 typedef std::shared_ptr<Goal> GoalPtr;
 typedef std::weak_ptr<Goal> WeakGoalPtr;
@@ -104,13 +104,10 @@ typedef std::map<StorePath, WeakGoalPtr> WeakGoalMap;
 
 
 
-class Goal : public std::enable_shared_from_this<Goal>
+struct Goal : public std::enable_shared_from_this<Goal>
 {
-public:
     typedef enum {ecBusy, ecSuccess, ecFailed, ecNoSubstituters, ecIncompleteClosure} ExitCode;
 
-protected:
-
     /* Backlink to the worker. */
     Worker & worker;
 
@@ -138,6 +135,9 @@ protected:
     /* Whether the goal is finished. */
     ExitCode exitCode;
 
+    /* Exception containing an error message, if any. */
+    std::optional<Error> ex;
+
     Goal(Worker & worker) : worker(worker)
     {
         nrFailed = nrNoSubstituters = nrIncompleteClosure = 0;
@@ -149,7 +149,6 @@ protected:
         trace("goal destroyed");
     }
 
-public:
     virtual void work() = 0;
 
     void addWaitee(GoalPtr waitee);
@@ -173,21 +172,14 @@ public:
         return name;
     }
 
-    ExitCode getExitCode()
-    {
-        return exitCode;
-    }
-
     /* Callback in case of a timeout.  It should wake up its waiters,
        get rid of any running child processes that are being monitored
        by the worker (important!), etc. */
-    virtual void timedOut() = 0;
+    virtual void timedOut(Error && ex) = 0;
 
     virtual string key() = 0;
 
-protected:
+    void amDone(ExitCode result, std::optional<Error> ex = {});
-
-    virtual void amDone(ExitCode result);
 };
 
 
@@ -303,7 +295,7 @@ public:
 
     /* Make a goal (with caching). */
     GoalPtr makeDerivationGoal(const StorePath & drvPath, const StringSet & wantedOutputs, BuildMode buildMode = bmNormal);
-    std::shared_ptr<DerivationGoal> makeBasicDerivationGoal(StorePath && drvPath,
+    std::shared_ptr<DerivationGoal> makeBasicDerivationGoal(const StorePath & drvPath,
         const BasicDerivation & drv, BuildMode buildMode = bmNormal);
     GoalPtr makeSubstitutionGoal(const StorePath & storePath, RepairFlag repair = NoRepair);
 
@@ -355,7 +347,7 @@ public:
        contents. */
     bool pathContentsGood(const StorePath & path);
 
-    void markContentsGood(StorePath && path);
+    void markContentsGood(const StorePath & path);
 
     void updateProgress()
     {
@@ -392,8 +384,7 @@ void Goal::waiteeDone(GoalPtr waitee, ExitCode result)
     assert(waitees.find(waitee) != waitees.end());
     waitees.erase(waitee);
 
-    trace(format("waitee '%1%' done; %2% left") %
+    trace(fmt("waitee '%s' done; %d left", waitee->name, waitees.size()));
-        waitee->name % waitees.size());
 
     if (result == ecFailed || result == ecNoSubstituters || result == ecIncompleteClosure) ++nrFailed;
 
@@ -418,12 +409,20 @@ void Goal::waiteeDone(GoalPtr waitee, ExitCode result)
 }
 
 
-void Goal::amDone(ExitCode result)
+void Goal::amDone(ExitCode result, std::optional<Error> ex)
 {
     trace("done");
     assert(exitCode == ecBusy);
     assert(result == ecSuccess || result == ecFailed || result == ecNoSubstituters || result == ecIncompleteClosure);
     exitCode = result;
+
+    if (ex) {
+        if (!waiters.empty())
+            logError(ex->info());
+        else
+            this->ex = std::move(*ex);
+    }
+
     for (auto & i : waiters) {
         GoalPtr goal = i.lock();
         if (goal) goal->waiteeDone(shared_from_this(), result);
@@ -869,6 +868,9 @@ private:
 
     std::unique_ptr<Activity> act;
 
+    /* Activity that denotes waiting for a lock. */
+    std::unique_ptr<Activity> actLock;
+
     std::map<ActivityId, Activity> builderActivities;
 
     /* The remote machine on which we're building. */
@@ -898,16 +900,16 @@ private:
     friend struct RestrictedStore;
 
 public:
-    DerivationGoal(StorePath && drvPath, const StringSet & wantedOutputs,
+    DerivationGoal(const StorePath & drvPath, const StringSet & wantedOutputs,
         Worker & worker, BuildMode buildMode = bmNormal);
-    DerivationGoal(StorePath && drvPath, const BasicDerivation & drv,
+    DerivationGoal(const StorePath & drvPath, const BasicDerivation & drv,
         Worker & worker, BuildMode buildMode = bmNormal);
     ~DerivationGoal();
 
     /* Whether we need to perform hash rewriting if there are valid output paths. */
     bool needsHashRewrite();
 
-    void timedOut() override;
+    void timedOut(Error && ex) override;
 
     string key() override
     {
@@ -922,7 +924,7 @@ public:
 
     StorePath getDrvPath()
     {
-        return drvPath.clone();
+        return drvPath;
     }
 
     /* Add wanted outputs to an already existing derivation goal. */
@@ -1006,14 +1008,11 @@ private:
 
     void repairClosure();
 
-    void amDone(ExitCode result) override
-    {
-        Goal::amDone(result);
-    }
-
     void started();
 
-    void done(BuildResult::Status status, const string & msg = "");
+    void done(
+        BuildResult::Status status,
+        std::optional<Error> ex = {});
 
     StorePathSet exportReferences(const StorePathSet & storePaths);
 };
@@ -1022,11 +1021,11 @@ private:
 const Path DerivationGoal::homeDir = "/homeless-shelter";
 
 
-DerivationGoal::DerivationGoal(StorePath && drvPath, const StringSet & wantedOutputs,
+DerivationGoal::DerivationGoal(const StorePath & drvPath, const StringSet & wantedOutputs,
     Worker & worker, BuildMode buildMode)
     : Goal(worker)
     , useDerivation(true)
-    , drvPath(std::move(drvPath))
+    , drvPath(drvPath)
     , wantedOutputs(wantedOutputs)
     , buildMode(buildMode)
 {
@@ -1039,11 +1038,11 @@ DerivationGoal::DerivationGoal(StorePath && drvPath, const StringSet & wantedOut
 }
 
 
-DerivationGoal::DerivationGoal(StorePath && drvPath, const BasicDerivation & drv,
+DerivationGoal::DerivationGoal(const StorePath & drvPath, const BasicDerivation & drv,
     Worker & worker, BuildMode buildMode)
     : Goal(worker)
     , useDerivation(false)
-    , drvPath(std::move(drvPath))
+    , drvPath(drvPath)
     , buildMode(buildMode)
 {
     this->drv = std::make_unique<BasicDerivation>(BasicDerivation(drv));
@@ -1107,10 +1106,10 @@ void DerivationGoal::killChild()
 }
 
 
-void DerivationGoal::timedOut()
+void DerivationGoal::timedOut(Error && ex)
 {
     killChild();
-    done(BuildResult::TimedOut);
+    done(BuildResult::TimedOut, ex);
 }
 
 
@@ -1158,11 +1157,7 @@ void DerivationGoal::loadDerivation()
     trace("loading derivation");
 
     if (nrFailed != 0) {
-        logError({
+        done(BuildResult::MiscFailure, Error("cannot build missing derivation '%s'", worker.store.printStorePath(drvPath)));
-            .name = "missing derivation during build",
-            .hint = hintfmt("cannot build missing derivation '%s'", worker.store.printStorePath(drvPath))
-        });
-        done(BuildResult::MiscFailure);
         return;
     }
 
@@ -1198,7 +1193,13 @@ void DerivationGoal::haveDerivation()
         return;
     }
 
-    parsedDrv = std::make_unique<ParsedDerivation>(drvPath.clone(), *drv);
+    parsedDrv = std::make_unique<ParsedDerivation>(drvPath, *drv);
+
+    if (parsedDrv->contentAddressed()) {
+        settings.requireExperimentalFeature("ca-derivations");
+        throw Error("ca-derivations isn't implemented yet");
+    }
+
 
     /* We are first going to try to create the invalid output paths
        through substitutes.  If that doesn't work, we'll build
@@ -1306,7 +1307,7 @@ void DerivationGoal::repairClosure()
         if (i.isDerivation()) {
             Derivation drv = worker.store.derivationFromPath(i);
             for (auto & j : drv.outputs)
-                outputsToDrv.insert_or_assign(j.second.path.clone(), i.clone());
+                outputsToDrv.insert_or_assign(j.second.path, i);
         }
 
     /* Check each path (slow!). */
@@ -1351,13 +1352,9 @@ void DerivationGoal::inputsRealised()
     if (nrFailed != 0) {
         if (!useDerivation)
             throw Error("some dependencies of '%s' are missing", worker.store.printStorePath(drvPath));
-        logError({
+        done(BuildResult::DependencyFailed, Error(
-            .name = "Dependencies could not be built",
+                "%s dependencies of derivation '%s' failed to build",
-            .hint = hintfmt(
+                nrFailed, worker.store.printStorePath(drvPath)));
-                "cannot build derivation '%s': %s dependencies couldn't be built",
-                worker.store.printStorePath(drvPath), nrFailed)
-        });
-        done(BuildResult::DependencyFailed);
         return;
     }
 
@@ -1439,10 +1436,15 @@ void DerivationGoal::tryToBuild()
         lockFiles.insert(worker.store.Store::toRealPath(outPath));
 
     if (!outputLocks.lockPaths(lockFiles, "", false)) {
+        if (!actLock)
+            actLock = std::make_unique<Activity>(*logger, lvlWarn, actBuildWaiting,
+                fmt("waiting for lock on %s", yellowtxt(showPaths(lockFiles))));
         worker.waitForAWhile(shared_from_this());
         return;
     }
 
+    actLock.reset();
+
     /* Now check again whether the outputs are valid.  This is because
        another process may have started building in parallel.  After
        it has finished and released the locks, we can (and should)
@@ -1458,7 +1460,7 @@ void DerivationGoal::tryToBuild()
         return;
     }
 
-    missingPaths = cloneStorePathSet(drv->outputPaths());
+    missingPaths = drv->outputPaths();
     if (buildMode != bmCheck)
         for (auto & i : validPaths) missingPaths.erase(i);
 
@@ -1481,6 +1483,7 @@ void DerivationGoal::tryToBuild()
             case rpAccept:
                 /* Yes, it has started doing so.  Wait until we get
                    EOF from the hook. */
+                actLock.reset();
                 result.startTime = time(0); // inexact
                 state = &DerivationGoal::buildDone;
                 started();
@@ -1488,6 +1491,9 @@ void DerivationGoal::tryToBuild()
             case rpPostpone:
                 /* Not now; wait until at least one child finishes or
                    the wake-up timeout expires. */
+                if (!actLock)
+                    actLock = std::make_unique<Activity>(*logger, lvlWarn, actBuildWaiting,
+                        fmt("waiting for a machine to build '%s'", yellowtxt(worker.store.printStorePath(drvPath))));
                 worker.waitForAWhile(shared_from_this());
                 outputLocks.unlock();
                 return;
@@ -1497,6 +1503,8 @@ void DerivationGoal::tryToBuild()
         }
     }
 
+    actLock.reset();
+
     /* Make sure that we are allowed to start a build.  If this
        derivation prefers to be done locally, do it even if
        maxBuildJobs is 0. */
@@ -1524,7 +1532,9 @@ void DerivationGoal::tryLocalBuild() {
                uid. */
             buildUser->kill();
         } else {
-            debug("waiting for build users");
+            if (!actLock)
+                actLock = std::make_unique<Activity>(*logger, lvlWarn, actBuildWaiting,
+                    fmt("waiting for UID to build '%s'", yellowtxt(worker.store.printStorePath(drvPath))));
             worker.waitForAWhile(shared_from_this());
             return;
         }
@@ -1535,17 +1545,18 @@ void DerivationGoal::tryLocalBuild() {
 #endif
     }
 
+    actLock.reset();
+
     try {
 
         /* Okay, we have to build. */
         startBuilder();
 
     } catch (BuildError & e) {
-        logError(e.info());
         outputLocks.unlock();
         buildUser.reset();
         worker.permanentFailure = true;
-        done(BuildResult::InputRejected, e.msg());
+        done(BuildResult::InputRejected, e);
         return;
     }
 
@@ -1657,10 +1668,10 @@ void DerivationGoal::buildDone()
                 }
 
             auto msg = fmt("builder for '%s' %s",
-                worker.store.printStorePath(drvPath),
+                yellowtxt(worker.store.printStorePath(drvPath)),
                 statusToString(status));
 
-            if (!settings.verboseBuild && !logTail.empty()) {
+            if (!logger->isVerbose() && !logTail.empty()) {
                 msg += (format("; last %d log lines:") % logTail.size()).str();
                 for (auto & line : logTail)
                     msg += "\n  " + line;
@@ -1709,11 +1720,7 @@ void DerivationGoal::buildDone()
                 }
 
                 void flushLine() {
-                    if (settings.verboseBuild) {
-                        printError("post-build-hook: " + currentLine);
-                    } else {
                     act.result(resPostBuildLogLine, currentLine);
-                    }
                     currentLine.clear();
                 }
 
@@ -1762,8 +1769,6 @@ void DerivationGoal::buildDone()
         outputLocks.unlock();
 
     } catch (BuildError & e) {
-        logError(e.info());
-
         outputLocks.unlock();
 
         BuildResult::Status st = BuildResult::MiscFailure;
@@ -1782,7 +1787,7 @@ void DerivationGoal::buildDone()
                 BuildResult::PermanentFailure;
         }
 
-        done(st, e.msg());
+        done(st, e);
         return;
     }
 
@@ -1902,14 +1907,14 @@ StorePathSet DerivationGoal::exportReferences(const StorePathSet & storePaths)
         if (!inputPaths.count(storePath))
             throw BuildError("cannot export references of path '%s' because it is not in the input closure of the derivation", worker.store.printStorePath(storePath));
 
-        worker.store.computeFSClosure(singleton(storePath), paths);
+        worker.store.computeFSClosure({storePath}, paths);
     }
 
     /* If there are derivations in the graph, then include their
        outputs as well.  This is useful if you want to do things
        like passing all build-time dependencies of some path to a
        derivation that builds a NixOS DVD image. */
-    auto paths2 = cloneStorePathSet(paths);
+    auto paths2 = paths;
 
     for (auto & j : paths2) {
         if (j.isDerivation()) {
@@ -2038,7 +2043,7 @@ void DerivationGoal::startBuilder()
             /* Write closure info to <fileName>. */
             writeFile(tmpDir + "/" + fileName,
                 worker.store.makeValidityRegistration(
-                    exportReferences(singleton(storePath)), false, false));
+                    exportReferences({storePath}), false, false));
         }
     }
 
@@ -2223,7 +2228,7 @@ void DerivationGoal::startBuilder()
             for (auto & i : missingPaths)
                 if (worker.store.isValidPath(i) && pathExists(worker.store.printStorePath(i))) {
                     addHashRewrite(i);
-                    redirectedBadOutputs.insert(i.clone());
+                    redirectedBadOutputs.insert(i);
                 }
     }
 
@@ -2718,8 +2723,8 @@ struct RestrictedStore : public LocalFSStore
     StorePathSet queryAllValidPaths() override
     {
         StorePathSet paths;
-        for (auto & p : goal.inputPaths) paths.insert(p.clone());
+        for (auto & p : goal.inputPaths) paths.insert(p);
-        for (auto & p : goal.addedPaths) paths.insert(p.clone());
+        for (auto & p : goal.addedPaths) paths.insert(p);
         return paths;
     }
 
@@ -2748,9 +2753,6 @@ struct RestrictedStore : public LocalFSStore
     StorePathSet queryDerivationOutputs(const StorePath & path) override
     { throw Error("queryDerivationOutputs"); }
 
-    StringSet queryDerivationOutputNames(const StorePath & path) override
-    { throw Error("queryDerivationOutputNames"); }
-
     std::optional<StorePath> queryPathFromHashPart(const std::string & hashPart) override
     { throw Error("queryPathFromHashPart"); }
 
@@ -2810,7 +2812,7 @@ struct RestrictedStore : public LocalFSStore
                 auto drv = derivationFromPath(path.path);
                 for (auto & output : drv.outputs)
                     if (wantOutput(output.first, path.outputs))
-                        newPaths.insert(output.second.path.clone());
+                        newPaths.insert(output.second.path);
             } else if (!goal.isAllowed(path.path))
                 throw InvalidPath("cannot build unknown path '%s' in recursive Nix", printStorePath(path.path));
         }
@@ -2855,7 +2857,7 @@ struct RestrictedStore : public LocalFSStore
             if (goal.isAllowed(path.path))
                 allowed.emplace_back(path);
             else
-                unknown.insert(path.path.clone());
+                unknown.insert(path.path);
         }
 
         next->queryMissing(allowed, willBuild, willSubstitute,
@@ -2950,7 +2952,7 @@ void DerivationGoal::addDependency(const StorePath & path)
 {
     if (isAllowed(path)) return;
 
-    addedPaths.insert(path.clone());
+    addedPaths.insert(path);
 
     /* If we're doing a sandbox build, then we have to make the path
        appear in the sandbox. */
@@ -3572,7 +3574,7 @@ StorePathSet parseReferenceSpecifiers(Store & store, const BasicDerivation & drv
         if (store.isStorePath(i))
             result.insert(store.parseStorePath(i));
         else if (drv.outputs.count(i))
-            result.insert(drv.outputs.find(i)->second.path.clone());
+            result.insert(drv.outputs.find(i)->second.path);
         else throw BuildError("derivation contains an illegal reference specifier '%s'", i);
     }
     return result;
@@ -3630,9 +3632,9 @@ void DerivationGoal::registerOutputs()
        output paths, and any paths that have been built via recursive
        Nix calls. */
     StorePathSet referenceablePaths;
-    for (auto & p : inputPaths) referenceablePaths.insert(p.clone());
+    for (auto & p : inputPaths) referenceablePaths.insert(p);
-    for (auto & i : drv->outputs) referenceablePaths.insert(i.second.path.clone());
+    for (auto & i : drv->outputs) referenceablePaths.insert(i.second.path);
-    for (auto & p : addedPaths) referenceablePaths.insert(p.clone());
+    for (auto & p : addedPaths) referenceablePaths.insert(p);
 
     /* Check whether the output paths were created, and grep each
        output path to determine what other paths it references.  Also make all
@@ -3743,7 +3745,7 @@ void DerivationGoal::registerOutputs()
                 worker.hashMismatch = true;
                 delayedException = std::make_exception_ptr(
                     BuildError("hash mismatch in fixed-output derivation '%s':\n  wanted: %s\n  got:    %s",
-                        worker.store.printStorePath(dest), h.to_string(SRI), h2.to_string(SRI)));
+                        worker.store.printStorePath(dest), h.to_string(SRI, true), h2.to_string(SRI, true)));
 
                 Path actualDest = worker.store.Store::toRealPath(dest);
 
@@ -3831,7 +3833,7 @@ void DerivationGoal::registerOutputs()
         info.narHash = hash.first;
         info.narSize = hash.second;
         info.references = std::move(references);
-        info.deriver = drvPath.clone();
+        info.deriver = drvPath;
         info.ultimate = true;
         info.ca = ca;
         worker.store.signPathInfo(info);
@@ -3875,7 +3877,6 @@ void DerivationGoal::registerOutputs()
                     .hint = hint
                 });
 
-
                 curRound = nrRounds; // we know enough, bail out early
             }
     }
@@ -3947,23 +3948,23 @@ void DerivationGoal::checkOutputs(const std::map<Path, ValidPathInfo> & outputs)
             uint64_t closureSize = 0;
             StorePathSet pathsDone;
             std::queue<StorePath> pathsLeft;
-            pathsLeft.push(path.clone());
+            pathsLeft.push(path);
 
             while (!pathsLeft.empty()) {
-                auto path = pathsLeft.front().clone();
+                auto path = pathsLeft.front();
                 pathsLeft.pop();
-                if (!pathsDone.insert(path.clone()).second) continue;
+                if (!pathsDone.insert(path).second) continue;
 
                 auto i = outputsByPath.find(worker.store.printStorePath(path));
                 if (i != outputsByPath.end()) {
                     closureSize += i->second.narSize;
                     for (auto & ref : i->second.references)
-                        pathsLeft.push(ref.clone());
+                        pathsLeft.push(ref);
                 } else {
                     auto info = worker.store.queryPathInfo(path);
                     closureSize += info->narSize;
                     for (auto & ref : info->references)
-                        pathsLeft.push(ref.clone());
+                        pathsLeft.push(ref);
                 }
             }
 
@@ -3990,8 +3991,8 @@ void DerivationGoal::checkOutputs(const std::map<Path, ValidPathInfo> & outputs)
                 auto spec = parseReferenceSpecifiers(worker.store, *drv, *value);
 
                 auto used = recursive
-                    ? cloneStorePathSet(getClosure(info.path).first)
+                    ? getClosure(info.path).first
-                    : cloneStorePathSet(info.references);
+                    : info.references;
 
                 if (recursive && checks.ignoreSelfRefs)
                     used.erase(info.path);
@@ -4001,10 +4002,10 @@ void DerivationGoal::checkOutputs(const std::map<Path, ValidPathInfo> & outputs)
                 for (auto & i : used)
                     if (allowed) {
                         if (!spec.count(i))
-                            badPaths.insert(i.clone());
+                            badPaths.insert(i);
                     } else {
                         if (spec.count(i))
-                            badPaths.insert(i.clone());
+                            badPaths.insert(i);
                     }
 
                 if (!badPaths.empty()) {
@@ -4139,14 +4140,11 @@ void DerivationGoal::handleChildOutput(int fd, const string & data)
     {
         logSize += data.size();
         if (settings.maxLogSize && logSize > settings.maxLogSize) {
-            logError({
-                .name = "Max log size exceeded",
-                .hint = hintfmt(
-                    "%1% killed after writing more than %2% bytes of log output",
-                    getName(), settings.maxLogSize)
-            });
             killChild();
-            done(BuildResult::LogLimitExceeded);
+            done(
+                BuildResult::LogLimitExceeded,
+                Error("%s killed after writing more than %d bytes of log output",
+                    getName(), settings.maxLogSize));
             return;
         }
 
@@ -4187,14 +4185,9 @@ void DerivationGoal::flushLine()
     if (handleJSONLogMessage(currentLogLine, *act, builderActivities, false))
         ;
 
-    else {
-        if (settings.verboseBuild &&
-            (settings.printRepeatedBuilds || curRound == 1))
-            printError(currentLogLine);
     else {
         logTail.push_back(currentLogLine);
         if (logTail.size() > settings.logLines) logTail.pop_front();
-        }
 
         act->result(resBuildLogLine, currentLogLine);
     }
@@ -4212,7 +4205,7 @@ StorePathSet DerivationGoal::checkPathValidity(bool returnValid, bool checkHash)
         bool good =
             worker.store.isValidPath(i.second.path) &&
             (!checkHash || worker.pathContentsGood(i.second.path));
-        if (good == returnValid) result.insert(i.second.path.clone());
+        if (good == returnValid) result.insert(i.second.path);
     }
     return result;
 }
@@ -4228,15 +4221,16 @@ void DerivationGoal::addHashRewrite(const StorePath & path)
     deletePath(worker.store.printStorePath(p));
     inputRewrites[h1] = h2;
     outputRewrites[h2] = h1;
-    redirectedOutputs.insert_or_assign(path.clone(), std::move(p));
+    redirectedOutputs.insert_or_assign(path, std::move(p));
 }
 
 
-void DerivationGoal::done(BuildResult::Status status, const string & msg)
+void DerivationGoal::done(BuildResult::Status status, std::optional<Error> ex)
 {
     result.status = status;
-    result.errorMsg = msg;
+    if (ex)
-    amDone(result.success() ? ecSuccess : ecFailed);
+        result.errorMsg = ex->what();
+    amDone(result.success() ? ecSuccess : ecFailed, ex);
     if (result.status == BuildResult::TimedOut)
         worker.timedOut = true;
     if (result.status == BuildResult::PermanentFailure)
@@ -4302,10 +4296,10 @@ private:
     GoalState state;
 
 public:
-    SubstitutionGoal(StorePath && storePath, Worker & worker, RepairFlag repair = NoRepair);
+    SubstitutionGoal(const StorePath & storePath, Worker & worker, RepairFlag repair = NoRepair);
     ~SubstitutionGoal();
 
-    void timedOut() override { abort(); };
+    void timedOut(Error && ex) override { abort(); };
 
     string key() override
     {
@@ -4328,18 +4322,13 @@ public:
     void handleChildOutput(int fd, const string & data) override;
     void handleEOF(int fd) override;
 
-    StorePath getStorePath() { return storePath.clone(); }
+    StorePath getStorePath() { return storePath; }
-
-    void amDone(ExitCode result) override
-    {
-        Goal::amDone(result);
-    }
 };
 
 
-SubstitutionGoal::SubstitutionGoal(StorePath && storePath, Worker & worker, RepairFlag repair)
+SubstitutionGoal::SubstitutionGoal(const StorePath & storePath, Worker & worker, RepairFlag repair)
     : Goal(worker)
-    , storePath(std::move(storePath))
+    , storePath(storePath)
     , repair(repair)
 {
     state = &SubstitutionGoal::init;
@@ -4573,7 +4562,7 @@ void SubstitutionGoal::finished()
         return;
     }
 
-    worker.markContentsGood(storePath.clone());
+    worker.markContentsGood(storePath);
 
     printMsg(lvlChatty, "substitution of path '%s' succeeded", worker.store.printStorePath(storePath));
 
@@ -4643,10 +4632,10 @@ Worker::~Worker()
 GoalPtr Worker::makeDerivationGoal(const StorePath & path,
     const StringSet & wantedOutputs, BuildMode buildMode)
 {
-    GoalPtr goal = derivationGoals[path.clone()].lock(); // FIXME
+    GoalPtr goal = derivationGoals[path].lock(); // FIXME
     if (!goal) {
-        goal = std::make_shared<DerivationGoal>(path.clone(), wantedOutputs, *this, buildMode);
+        goal = std::make_shared<DerivationGoal>(path, wantedOutputs, *this, buildMode);
-        derivationGoals.insert_or_assign(path.clone(), goal);
+        derivationGoals.insert_or_assign(path, goal);
         wakeUp(goal);
     } else
         (dynamic_cast<DerivationGoal *>(goal.get()))->addWantedOutputs(wantedOutputs);
@@ -4654,10 +4643,10 @@ GoalPtr Worker::makeDerivationGoal(const StorePath & path,
 }
 
 
-std::shared_ptr<DerivationGoal> Worker::makeBasicDerivationGoal(StorePath && drvPath,
+std::shared_ptr<DerivationGoal> Worker::makeBasicDerivationGoal(const StorePath & drvPath,
     const BasicDerivation & drv, BuildMode buildMode)
 {
-    auto goal = std::make_shared<DerivationGoal>(std::move(drvPath), drv, *this, buildMode);
+    auto goal = std::make_shared<DerivationGoal>(drvPath, drv, *this, buildMode);
     wakeUp(goal);
     return goal;
 }
@@ -4665,10 +4654,10 @@ std::shared_ptr<DerivationGoal> Worker::makeBasicDerivationGoal(StorePath && drv
 
 GoalPtr Worker::makeSubstitutionGoal(const StorePath & path, RepairFlag repair)
 {
-    GoalPtr goal = substitutionGoals[path.clone()].lock(); // FIXME
+    GoalPtr goal = substitutionGoals[path].lock(); // FIXME
     if (!goal) {
-        goal = std::make_shared<SubstitutionGoal>(path.clone(), *this, repair);
+        goal = std::make_shared<SubstitutionGoal>(path, *this, repair);
-        substitutionGoals.insert_or_assign(path.clone(), goal);
+        substitutionGoals.insert_or_assign(path, goal);
         wakeUp(goal);
     }
     return goal;
@@ -4697,7 +4686,7 @@ void Worker::removeGoal(GoalPtr goal)
         topGoals.erase(goal);
         /* If a top-level goal failed, then kill all other goals
            (unless keepGoing was set). */
-        if (goal->getExitCode() == Goal::ecFailed && !settings.keepGoing)
+        if (goal->exitCode == Goal::ecFailed && !settings.keepGoing)
             topGoals.clear();
     }
 
@@ -4875,8 +4864,6 @@ void Worker::waitForInput()
        up after a few seconds at most. */
     if (!waitingForAWhile.empty()) {
         useTimeout = true;
-        if (lastWokenUp == steady_time_point::min())
-            printInfo("waiting for locks, build slots or build users...");
         if (lastWokenUp == steady_time_point::min() || lastWokenUp > before) lastWokenUp = before;
         timeout = std::max(1L,
             (long) std::chrono::duration_cast<std::chrono::seconds>(
@@ -4941,32 +4928,24 @@ void Worker::waitForInput()
             }
         }
 
-        if (goal->getExitCode() == Goal::ecBusy &&
+        if (goal->exitCode == Goal::ecBusy &&
             0 != settings.maxSilentTime &&
             j->respectTimeouts &&
             after - j->lastOutput >= std::chrono::seconds(settings.maxSilentTime))
         {
-            logError({
+            goal->timedOut(Error(
-                .name = "Silent build timeout",
-                .hint = hintfmt(
                     "%1% timed out after %2% seconds of silence",
-                    goal->getName(), settings.maxSilentTime)
+                    goal->getName(), settings.maxSilentTime));
-            });
-            goal->timedOut();
         }
 
-        else if (goal->getExitCode() == Goal::ecBusy &&
+        else if (goal->exitCode == Goal::ecBusy &&
             0 != settings.buildTimeout &&
             j->respectTimeouts &&
             after - j->timeStarted >= std::chrono::seconds(settings.buildTimeout))
         {
-            logError({
+            goal->timedOut(Error(
-                .name = "Build timeout",
-                .hint = hintfmt(
                     "%1% timed out after %2% seconds",
-                    goal->getName(), settings.buildTimeout)
+                    goal->getName(), settings.buildTimeout));
-            });
-            goal->timedOut();
         }
     }
 
@@ -5023,7 +5002,7 @@ bool Worker::pathContentsGood(const StorePath & path)
         Hash nullHash(htSHA256);
         res = info->narHash == nullHash || info->narHash == current.first;
     }
-    pathContentsGoodCache.insert_or_assign(path.clone(), res);
+    pathContentsGoodCache.insert_or_assign(path, res);
     if (!res)
         logError({
             .name = "Corrupted path",
@@ -5033,9 +5012,9 @@ bool Worker::pathContentsGood(const StorePath & path)
 }
 
 
-void Worker::markContentsGood(StorePath && path)
+void Worker::markContentsGood(const StorePath & path)
 {
-    pathContentsGoodCache.insert_or_assign(std::move(path), true);
+    pathContentsGoodCache.insert_or_assign(path, true);
 }
 
 
@@ -5072,23 +5051,35 @@ void LocalStore::buildPaths(const std::vector<StorePathWithOutputs> & drvPaths,
     worker.run(goals);
 
     StorePathSet failed;
+    std::optional<Error> ex;
     for (auto & i : goals) {
-        if (i->getExitCode() != Goal::ecSuccess) {
+        if (i->ex) {
+            if (ex)
+                logError(i->ex->info());
+            else
+                ex = i->ex;
+        }
+        if (i->exitCode != Goal::ecSuccess) {
             DerivationGoal * i2 = dynamic_cast<DerivationGoal *>(i.get());
             if (i2) failed.insert(i2->getDrvPath());
             else failed.insert(dynamic_cast<SubstitutionGoal *>(i.get())->getStorePath());
         }
     }
 
-    if (!failed.empty())
+    if (failed.size() == 1 && ex) {
+        ex->status = worker.exitStatus();
+        throw *ex;
+    } else if (!failed.empty()) {
+        if (ex) logError(ex->info());
         throw Error(worker.exitStatus(), "build of %s failed", showPaths(failed));
     }
+}
 
 BuildResult LocalStore::buildDerivation(const StorePath & drvPath, const BasicDerivation & drv,
     BuildMode buildMode)
 {
     Worker worker(*this);
-    auto goal = worker.makeBasicDerivationGoal(drvPath.clone(), drv, buildMode);
+    auto goal = worker.makeBasicDerivationGoal(drvPath, drv, buildMode);
 
     BuildResult result;
 
@@ -5109,7 +5100,7 @@ void LocalStore::ensurePath(const StorePath & path)
     /* If the path is already valid, we're done. */
     if (isValidPath(path)) return;
 
-    primeCache(*this, {StorePathWithOutputs(path)});
+    primeCache(*this, {{path}});
 
     Worker worker(*this);
     GoalPtr goal = worker.makeSubstitutionGoal(path);
@@ -5117,9 +5108,14 @@ void LocalStore::ensurePath(const StorePath & path)
 
     worker.run(goals);
 
-    if (goal->getExitCode() != Goal::ecSuccess)
+    if (goal->exitCode != Goal::ecSuccess) {
+        if (goal->ex) {
+            goal->ex->status = worker.exitStatus();
+            throw *goal->ex;
+        } else
             throw Error(worker.exitStatus(), "path '%s' does not exist and cannot be created", printStorePath(path));
     }
+}
 
 
 void LocalStore::repairPath(const StorePath & path)
@@ -5130,7 +5126,7 @@ void LocalStore::repairPath(const StorePath & path)
 
     worker.run(goals);
 
-    if (goal->getExitCode() != Goal::ecSuccess) {
+    if (goal->exitCode != Goal::ecSuccess) {
         /* Since substituting the path didn't work, if we have a valid
            deriver, then rebuild the deriver. */
         auto info = queryPathInfo(path);

src/libstore/builtins/buildenv.cc

@@ -22,8 +22,7 @@ static void createLinks(State & state, const Path & srcDir, const Path & dstDir,
         srcFiles = readDirectory(srcDir);
     } catch (SysError & e) {
         if (e.errNo == ENOTDIR) {
-            logWarning(
+            logWarning({
-                ErrorInfo { 
                 .name = "Create links - directory",
                 .hint = hintfmt("not including '%s' in the user environment because it's not a directory", srcDir)
             });
@@ -45,8 +44,7 @@ static void createLinks(State & state, const Path & srcDir, const Path & dstDir,
                 throw SysError("getting status of '%1%'", srcFile);
         } catch (SysError & e) {
             if (e.errNo == ENOENT || e.errNo == ENOTDIR) {
-                logWarning(
+                logWarning({
-                    ErrorInfo { 
                     .name = "Create links - skipping symlink",
                     .hint = hintfmt("skipping dangling symlink '%s'", dstFile)
                 });

src/libstore/daemon.cc

@@ -293,7 +293,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         auto path = store->parseStorePath(readString(from));
         logger->startWork();
         StorePathSet paths; // FIXME
-        paths.insert(path.clone());
+        paths.insert(path);
         auto res = store->querySubstitutablePaths(paths);
         logger->stopWork();
         to << (res.count(path) != 0);
@@ -327,7 +327,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         StorePathSet paths;
         if (op == wopQueryReferences)
             for (auto & i : store->queryPathInfo(path)->references)
-                paths.insert(i.clone());
+                paths.insert(i);
         else if (op == wopQueryReferrers)
             store->queryReferrers(path, paths);
         else if (op == wopQueryValidDerivers)
@@ -341,8 +341,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     case wopQueryDerivationOutputNames: {
         auto path = store->parseStorePath(readString(from));
         logger->startWork();
-        StringSet names;
+        auto names = store->readDerivation(path).outputNames();
-        names = store->queryDerivationOutputNames(path);
         logger->stopWork();
         to << names;
         break;
@@ -370,8 +369,10 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         std::string s, baseName;
         FileIngestionMethod method;
         {
-            bool fixed, recursive;
+            bool fixed; uint8_t recursive;
             from >> baseName >> fixed /* obsolete */ >> recursive >> s;
+            if (recursive > (uint8_t) FileIngestionMethod::Recursive)
+                throw Error("unsupported FileIngestionMethod with value of %i; you may need to upgrade nix-daemon", recursive);
             method = FileIngestionMethod { recursive };
             /* Compatibility hack. */
             if (!fixed) {
@@ -592,9 +593,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         auto path = store->parseStorePath(readString(from));
         logger->startWork();
         SubstitutablePathInfos infos;
-        StorePathSet paths;
+        store->querySubstitutablePathInfos({path}, infos);
-        paths.insert(path.clone()); // FIXME
-        store->querySubstitutablePathInfos(paths, infos);
         logger->stopWork();
         auto i = infos.find(path);
         if (i == infos.end())

src/libstore/derivations.cc

@@ -27,28 +27,6 @@ void DerivationOutput::parseHashInfo(FileIngestionMethod & recursive, Hash & has
 }
 
 
-BasicDerivation::BasicDerivation(const BasicDerivation & other)
-    : platform(other.platform)
-    , builder(other.builder)
-    , args(other.args)
-    , env(other.env)
-{
-    for (auto & i : other.outputs)
-        outputs.insert_or_assign(i.first,
-            DerivationOutput(i.second.path.clone(), std::string(i.second.hashAlgo), std::string(i.second.hash)));
-    for (auto & i : other.inputSrcs)
-        inputSrcs.insert(i.clone());
-}
-
-
-Derivation::Derivation(const Derivation & other)
-    : BasicDerivation(other)
-{
-    for (auto & i : other.inputDrvs)
-        inputDrvs.insert_or_assign(i.first.clone(), i.second);
-}
-
-
 const StorePath & BasicDerivation::findOutput(const string & id) const
 {
     auto i = outputs.find(id);
@@ -67,9 +45,9 @@ bool BasicDerivation::isBuiltin() const
 StorePath writeDerivation(ref<Store> store,
     const Derivation & drv, std::string_view name, RepairFlag repair)
 {
-    auto references = cloneStorePathSet(drv.inputSrcs);
+    auto references = drv.inputSrcs;
     for (auto & i : drv.inputDrvs)
-        references.insert(i.first.clone());
+        references.insert(i.first);
     /* Note that the outputs of a derivation are *not* references
        (that can be missing (of course) and should not necessarily be
        held during a garbage collection). */
@@ -155,7 +133,11 @@ static Derivation parseDerivation(const Store & store, const string & s)
         expect(str, ","); auto hashAlgo = parseString(str);
         expect(str, ","); auto hash = parseString(str);
         expect(str, ")");
-        drv.outputs.emplace(id, DerivationOutput(std::move(path), std::move(hashAlgo), std::move(hash)));
+        drv.outputs.emplace(id, DerivationOutput {
+            .path = std::move(path),
+            .hashAlgo = std::move(hashAlgo),
+            .hash = std::move(hash)
+        });
     }
 
     /* Parse the list of input derivations. */
@@ -204,6 +186,12 @@ Derivation readDerivation(const Store & store, const Path & drvPath)
 Derivation Store::derivationFromPath(const StorePath & drvPath)
 {
     ensurePath(drvPath);
+    return readDerivation(drvPath);
+}
+
+
+Derivation Store::readDerivation(const StorePath & drvPath)
+{
     auto accessor = getFSAccessor();
     try {
         return parseDerivation(*this, accessor->readFile(printStorePath(drvPath)));
@@ -377,8 +365,8 @@ Hash hashDerivationModulo(Store & store, const Derivation & drv, bool maskOutput
         auto h = drvHashes.find(i.first);
         if (h == drvHashes.end()) {
             assert(store.isValidPath(i.first));
-            h = drvHashes.insert_or_assign(i.first.clone(), hashDerivationModulo(store,
+            h = drvHashes.insert_or_assign(i.first, hashDerivationModulo(store,
-                readDerivation(store, store.toRealPath(i.first)), false)).first;
+                store.readDerivation(i.first), false)).first;
         }
         inputs2.insert_or_assign(h->second.to_string(Base16, false), i.second);
     }
@@ -405,11 +393,20 @@ StorePathSet BasicDerivation::outputPaths() const
 {
     StorePathSet paths;
     for (auto & i : outputs)
-        paths.insert(i.second.path.clone());
+        paths.insert(i.second.path);
     return paths;
 }
 
 
+StringSet BasicDerivation::outputNames() const
+{
+    StringSet names;
+    for (auto & i : outputs)
+        names.insert(i.first);
+    return names;
+}
+
+
 Source & readDerivation(Source & in, const Store & store, BasicDerivation & drv)
 {
     drv.outputs.clear();
@@ -419,7 +416,11 @@ Source & readDerivation(Source & in, const Store & store, BasicDerivation & drv)
         auto path = store.parseStorePath(readString(in));
         auto hashAlgo = readString(in);
         auto hash = readString(in);
-        drv.outputs.emplace(name, DerivationOutput(std::move(path), std::move(hashAlgo), std::move(hash)));
+        drv.outputs.emplace(name, DerivationOutput {
+            .path = std::move(path),
+            .hashAlgo = std::move(hashAlgo),
+            .hash = std::move(hash)
+        });
     }
 
     drv.inputSrcs = readStorePaths<StorePathSet>(store, in);

src/libstore/derivations.hh

@@ -17,11 +17,6 @@ struct DerivationOutput
     StorePath path;
     std::string hashAlgo; /* hash used for expected hash computation */
     std::string hash; /* expected hash, may be null */
-    DerivationOutput(StorePath && path, std::string && hashAlgo, std::string && hash)
-        : path(std::move(path))
-        , hashAlgo(std::move(hashAlgo))
-        , hash(std::move(hash))
-    { }
     void parseHashInfo(FileIngestionMethod & recursive, Hash & hash) const;
 };
 
@@ -43,7 +38,6 @@ struct BasicDerivation
     StringPairs env;
 
     BasicDerivation() { }
-    explicit BasicDerivation(const BasicDerivation & other);
     virtual ~BasicDerivation() { };
 
     /* Return the path corresponding to the output identifier `id' in
@@ -58,6 +52,8 @@ struct BasicDerivation
     /* Return the output paths of a derivation. */
     StorePathSet outputPaths() const;
 
+    /* Return the output names of a derivation. */
+    StringSet outputNames() const;
 };
 
 struct Derivation : BasicDerivation
@@ -69,8 +65,6 @@ struct Derivation : BasicDerivation
         std::map<std::string, StringSet> * actualInputs = nullptr) const;
 
     Derivation() { }
-    Derivation(Derivation && other) = default;
-    explicit Derivation(const Derivation & other);
 };
 
 

src/libstore/export-import.cc

@@ -57,7 +57,7 @@ void Store::exportPath(const StorePath & path, Sink & sink)
     Hash hash = hashAndWriteSink.currentHash();
     if (hash != info->narHash && info->narHash != Hash(info->narHash.type))
         throw Error("hash of path '%s' has changed from '%s' to '%s'!",
-            printStorePath(path), info->narHash.to_string(), hash.to_string());
+            printStorePath(path), info->narHash.to_string(Base32, true), hash.to_string(Base32, true));
 
     hashAndWriteSink
         << exportMagic
@@ -105,7 +105,7 @@ StorePaths Store::importPaths(Source & source, std::shared_ptr<FSAccessor> acces
         auto source = StringSource { *tee.source.data };
         addToStore(info, source, NoRepair, checkSigs, accessor);
 
-        res.push_back(info.path.clone());
+        res.push_back(info.path);
     }
 
     return res;

src/libstore/filetransfer.cc

@@ -72,6 +72,18 @@ struct curlFileTransfer : public FileTransfer
 
         curl_off_t writtenToSink = 0;
 
+        inline static const std::set<long> successfulStatuses {200, 201, 204, 206, 304, 0 /* other protocol */};
+        /* Get the HTTP status code, or 0 for other protocols. */
+        long getHTTPStatus()
+        {
+            long httpStatus = 0;
+            long protocol = 0;
+            curl_easy_getinfo(req, CURLINFO_PROTOCOL, &protocol);
+            if (protocol == CURLPROTO_HTTP || protocol == CURLPROTO_HTTPS)
+                curl_easy_getinfo(req, CURLINFO_RESPONSE_CODE, &httpStatus);
+            return httpStatus;
+        }
+
         TransferItem(curlFileTransfer & fileTransfer,
             const FileTransferRequest & request,
             Callback<FileTransferResult> && callback)
@@ -83,12 +95,11 @@ struct curlFileTransfer : public FileTransfer
             , callback(std::move(callback))
             , finalSink([this](const unsigned char * data, size_t len) {
                 if (this->request.dataCallback) {
-                    long httpStatus = 0;
+                    auto httpStatus = getHTTPStatus();
-                    curl_easy_getinfo(req, CURLINFO_RESPONSE_CODE, &httpStatus);
 
                     /* Only write data to the sink if this is a
                        successful response. */
-                    if (httpStatus == 0 || httpStatus == 200 || httpStatus == 201 || httpStatus == 206) {
+                    if (successfulStatuses.count(httpStatus)) {
                         writtenToSink += len;
                         this->request.dataCallback((char *) data, len);
                     }
@@ -316,8 +327,7 @@ struct curlFileTransfer : public FileTransfer
 
         void finish(CURLcode code)
         {
-            long httpStatus = 0;
+            auto httpStatus = getHTTPStatus();
-            curl_easy_getinfo(req, CURLINFO_RESPONSE_CODE, &httpStatus);
 
             char * effectiveUriCStr;
             curl_easy_getinfo(req, CURLINFO_EFFECTIVE_URL, &effectiveUriCStr);
@@ -343,8 +353,7 @@ struct curlFileTransfer : public FileTransfer
             if (writeException)
                 failEx(writeException);
 
-            else if (code == CURLE_OK &&
+            else if (code == CURLE_OK && successfulStatuses.count(httpStatus))
-                (httpStatus == 200 || httpStatus == 201 || httpStatus == 204 || httpStatus == 206 || httpStatus == 304 || httpStatus == 226 /* FTP */ || httpStatus == 0 /* other protocol */))
             {
                 result.cached = httpStatus == 304;
                 act.progress(result.bodySize, result.bodySize);

src/libstore/gc.cc

@@ -128,9 +128,8 @@ Path LocalFSStore::addPermRoot(const StorePath & storePath,
        gcroots directory. */
     if (settings.checkRootReachability) {
         auto roots = findRoots(false);
-        if (roots[storePath.clone()].count(gcRoot) == 0)
+        if (roots[storePath].count(gcRoot) == 0)
-            logWarning(
+            logWarning({
-                ErrorInfo { 
                 .name = "GC root",
                 .hint = hintfmt("warning: '%1%' is not in a directory where the garbage collector looks for roots; "
                     "therefore, '%2%' might be removed by the garbage collector",
@@ -479,9 +478,9 @@ void LocalStore::findRuntimeRoots(Roots & roots, bool censor)
         if (!isValidPath(path)) continue;
         debug("got additional root '%1%'", pathS);
         if (censor)
-            roots[path.clone()].insert(censored);
+            roots[path].insert(censored);
         else
-            roots[path.clone()].insert(links.begin(), links.end());
+            roots[path].insert(links.begin(), links.end());
     }
 }
 
@@ -593,11 +592,11 @@ bool LocalStore::canReachRoot(GCState & state, StorePathSet & visited, const Sto
 
     if (state.roots.count(path)) {
         debug("cannot delete '%1%' because it's a root", printStorePath(path));
-        state.alive.insert(path.clone());
+        state.alive.insert(path);
         return true;
     }
 
-    visited.insert(path.clone());
+    visited.insert(path);
 
     if (!isValidPath(path)) return false;
 
@@ -611,7 +610,7 @@ bool LocalStore::canReachRoot(GCState & state, StorePathSet & visited, const Sto
     if (state.gcKeepDerivations && path.isDerivation()) {
         for (auto & i : queryDerivationOutputs(path))
             if (isValidPath(i) && queryPathInfo(i)->deriver == path)
-                incoming.insert(i.clone());
+                incoming.insert(i);
     }
 
     /* If keep-outputs is set, then don't delete this path if there
@@ -619,13 +618,13 @@ bool LocalStore::canReachRoot(GCState & state, StorePathSet & visited, const Sto
     if (state.gcKeepOutputs) {
         auto derivers = queryValidDerivers(path);
         for (auto & i : derivers)
-            incoming.insert(i.clone());
+            incoming.insert(i);
     }
 
     for (auto & i : incoming)
         if (i != path)
             if (canReachRoot(state, visited, i)) {
-                state.alive.insert(path.clone());
+                state.alive.insert(path);
                 return true;
             }
 
@@ -669,7 +668,7 @@ void LocalStore::tryToDelete(GCState & state, const Path & path)
            ‘nix-store --delete’ doesn't have the unexpected effect of
            recursing into derivations and outputs. */
         for (auto & i : visited)
-            state.dead.insert(i.clone());
+            state.dead.insert(i);
         if (state.shouldDelete)
             deletePathRecursive(state, path);
     }
@@ -755,7 +754,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
     if (!options.ignoreLiveness)
         findRootsNoTemp(rootMap, true);
 
-    for (auto & i : rootMap) state.roots.insert(i.first.clone());
+    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
@@ -764,8 +763,8 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
     Roots tempRoots;
     findTempRoots(fds, tempRoots, true);
     for (auto & root : tempRoots) {
-        state.tempRoots.insert(root.first.clone());
+        state.tempRoots.insert(root.first);
-        state.roots.insert(root.first.clone());
+        state.roots.insert(root.first);
     }
 
     /* After this point the set of roots or temporary roots cannot

src/libstore/globals.hh

@@ -271,7 +271,7 @@ public:
         "listed in 'trusted-public-keys'."};
 
     Setting<StringSet> extraPlatforms{this,
-        std::string{SYSTEM} == "x86_64-linux" ? StringSet{"i686-linux"} : StringSet{},
+        std::string{SYSTEM} == "x86_64-linux" && !isWSL1() ? StringSet{"i686-linux"} : StringSet{},
         "extra-platforms",
         "Additional platforms that can be built on the local system. "
         "These may be supported natively (e.g. armv7 on some aarch64 CPUs "

src/libstore/legacy-ssh-store.cc

@@ -256,7 +256,7 @@ struct LegacySSHStore : public Store
         conn->to.flush();
 
         for (auto & i : readStorePaths<StorePathSet>(*this, conn->from))
-            out.insert(i.clone());
+            out.insert(i);
     }
 
     StorePathSet queryValidPaths(const StorePathSet & paths,

src/libstore/local-fs-store.cc

@@ -90,13 +90,13 @@ const string LocalFSStore::drvsLogDir = "drvs";
 
 std::shared_ptr<std::string> LocalFSStore::getBuildLog(const StorePath & path_)
 {
-    auto path = path_.clone();
+    auto path = path_;
 
     if (!path.isDerivation()) {
         try {
             auto info = queryPathInfo(path);
             if (!info->deriver) return nullptr;
-            path = info->deriver->clone();
+            path = *info->deriver;
         } catch (InvalidPath &) {
             return nullptr;
         }

src/libstore/local-store.cc

@@ -584,7 +584,7 @@ uint64_t LocalStore::addValidPath(State & state,
 
     state.stmtRegisterValidPath.use()
         (printStorePath(info.path))
-        (info.narHash.to_string(Base16))
+        (info.narHash.to_string(Base16, true))
         (info.registrationTime == 0 ? time(0) : info.registrationTime)
         (info.deriver ? printStorePath(*info.deriver) : "", (bool) info.deriver)
         (info.narSize, info.narSize != 0)
@@ -599,7 +599,7 @@ uint64_t LocalStore::addValidPath(State & state,
        efficiently query whether a path is an output of some
        derivation. */
     if (info.path.isDerivation()) {
-        auto drv = readDerivation(*this, realStoreDir + "/" + std::string(info.path.to_string()));
+        auto drv = readDerivation(info.path);
 
         /* Verify that the output paths in the derivation are correct
            (i.e., follow the scheme for computing output paths from
@@ -619,7 +619,7 @@ uint64_t LocalStore::addValidPath(State & state,
 
     {
         auto state_(Store::state.lock());
-        state_->pathInfoCache.upsert(storePathToHash(printStorePath(info.path)),
+        state_->pathInfoCache.upsert(std::string(info.path.hashPart()),
             PathInfoCacheValue{ .value = std::make_shared<const ValidPathInfo>(info) });
     }
 
@@ -631,7 +631,7 @@ void LocalStore::queryPathInfoUncached(const StorePath & path,
     Callback<std::shared_ptr<const ValidPathInfo>> callback) noexcept
 {
     try {
-        auto info = std::make_shared<ValidPathInfo>(path.clone());
+        auto info = std::make_shared<ValidPathInfo>(path);
 
         callback(retrySQLite<std::shared_ptr<ValidPathInfo>>([&]() {
             auto state(_state.lock());
@@ -684,7 +684,7 @@ void LocalStore::updatePathInfo(State & state, const ValidPathInfo & info)
 {
     state.stmtUpdatePathInfo.use()
         (info.narSize, info.narSize != 0)
-        (info.narHash.to_string(Base16))
+        (info.narHash.to_string(Base16, true))
         (info.ultimate ? 1 : 0, info.ultimate)
         (concatStringsSep(" ", info.sigs), !info.sigs.empty())
         (info.ca, !info.ca.empty())
@@ -721,7 +721,7 @@ StorePathSet LocalStore::queryValidPaths(const StorePathSet & paths, SubstituteF
 {
     StorePathSet res;
     for (auto & i : paths)
-        if (isValidPath(i)) res.insert(i.clone());
+        if (isValidPath(i)) res.insert(i);
     return res;
 }
 
@@ -789,26 +789,9 @@ StorePathSet LocalStore::queryDerivationOutputs(const StorePath & path)
 }
 
 
-StringSet LocalStore::queryDerivationOutputNames(const StorePath & path)
-{
-    return retrySQLite<StringSet>([&]() {
-        auto state(_state.lock());
-
-        auto useQueryDerivationOutputs(state->stmtQueryDerivationOutputs.use()
-            (queryValidPathId(*state, path)));
-
-        StringSet outputNames;
-        while (useQueryDerivationOutputs.next())
-            outputNames.insert(useQueryDerivationOutputs.getStr(0));
-
-        return outputNames;
-    });
-}
-
-
 std::optional<StorePath> LocalStore::queryPathFromHashPart(const std::string & hashPart)
 {
-    if (hashPart.size() != storePathHashLen) throw Error("invalid hash part");
+    if (hashPart.size() != StorePath::HashLen) throw Error("invalid hash part");
 
     Path prefix = storeDir + "/" + hashPart;
 
@@ -833,7 +816,7 @@ StorePathSet LocalStore::querySubstitutablePaths(const StorePathSet & paths)
 
     StorePathSet remaining;
     for (auto & i : paths)
-        remaining.insert(i.clone());
+        remaining.insert(i);
 
     StorePathSet res;
 
@@ -847,9 +830,9 @@ StorePathSet LocalStore::querySubstitutablePaths(const StorePathSet & paths)
         StorePathSet remaining2;
         for (auto & path : remaining)
             if (valid.count(path))
-                res.insert(path.clone());
+                res.insert(path);
             else
-                remaining2.insert(path.clone());
+                remaining2.insert(path);
 
         std::swap(remaining, remaining2);
     }
@@ -871,9 +854,9 @@ void LocalStore::querySubstitutablePathInfos(const StorePathSet & paths,
                 auto info = sub->queryPathInfo(path);
                 auto narInfo = std::dynamic_pointer_cast<const NarInfo>(
                     std::shared_ptr<const ValidPathInfo>(info));
-                infos.insert_or_assign(path.clone(), SubstitutablePathInfo{
+                infos.insert_or_assign(path, SubstitutablePathInfo{
-                    info->deriver ? info->deriver->clone() : std::optional<StorePath>(),
+                    info->deriver,
-                    cloneStorePathSet(info->references),
+                    info->references,
                     narInfo ? narInfo->fileSize : 0,
                     info->narSize});
             } catch (InvalidPath &) {
@@ -917,7 +900,7 @@ void LocalStore::registerValidPaths(const ValidPathInfos & infos)
                 updatePathInfo(*state, i);
             else
                 addValidPath(*state, i, false);
-            paths.insert(i.path.clone());
+            paths.insert(i.path);
         }
 
         for (auto & i : infos) {
@@ -932,8 +915,7 @@ void LocalStore::registerValidPaths(const ValidPathInfos & infos)
         for (auto & i : infos)
             if (i.path.isDerivation()) {
                 // FIXME: inefficient; we already loaded the derivation in addValidPath().
-                checkDerivationOutputs(i.path,
+                checkDerivationOutputs(i.path, readDerivation(i.path));
-                    readDerivation(*this, realStoreDir + "/" + std::string(i.path.to_string())));
             }
 
         /* Do a topological sort of the paths.  This will throw an
@@ -960,7 +942,7 @@ void LocalStore::invalidatePath(State & state, const StorePath & path)
 
     {
         auto state_(Store::state.lock());
-        state_->pathInfoCache.erase(storePathToHash(printStorePath(path)));
+        state_->pathInfoCache.erase(std::string(path.hashPart()));
     }
 }
 
@@ -1012,7 +994,7 @@ void LocalStore::addToStore(const ValidPathInfo & info, Source & source,
             if (info.ca == "" || !info.references.count(info.path))
                 hashSink = std::make_unique<HashSink>(htSHA256);
             else
-                hashSink = std::make_unique<HashModuloSink>(htSHA256, storePathToHash(printStorePath(info.path)));
+                hashSink = std::make_unique<HashModuloSink>(htSHA256, std::string(info.path.hashPart()));
 
             LambdaSource wrapperSource([&](unsigned char * data, size_t len) -> size_t {
                 size_t n = source.read(data, len);
@@ -1026,7 +1008,7 @@ void LocalStore::addToStore(const ValidPathInfo & info, Source & source,
 
             if (hashResult.first != info.narHash)
                 throw Error("hash mismatch importing path '%s';\n  wanted: %s\n  got:    %s",
-                    printStorePath(info.path), info.narHash.to_string(), hashResult.first.to_string());
+                    printStorePath(info.path), info.narHash.to_string(Base32, true), hashResult.first.to_string(Base32, true));
 
             if (hashResult.second != info.narSize)
                 throw Error("size mismatch importing path '%s';\n  wanted: %s\n  got:   %s",
@@ -1092,7 +1074,7 @@ StorePath LocalStore::addToStoreFromDump(const string & dump, const string & nam
 
             optimisePath(realPath); // FIXME: combine with hashPath()
 
-            ValidPathInfo info(dstPath.clone());
+            ValidPathInfo info(dstPath);
             info.narHash = hash.first;
             info.narSize = hash.second;
             info.ca = makeFixedOutputCA(method, h);
@@ -1155,11 +1137,11 @@ StorePath LocalStore::addTextToStore(const string & name, const string & s,
 
             optimisePath(realPath);
 
-            ValidPathInfo info(dstPath.clone());
+            ValidPathInfo info(dstPath);
             info.narHash = narHash;
             info.narSize = sink.s->size();
-            info.references = cloneStorePathSet(references);
+            info.references = references;
-            info.ca = "text:" + hash.to_string();
+            info.ca = "text:" + hash.to_string(Base32, true);
             registerValidPath(info);
         }
 
@@ -1273,7 +1255,7 @@ bool LocalStore::verifyStore(bool checkContents, RepairFlag repair)
                 if (info->ca == "" || !info->references.count(info->path))
                     hashSink = std::make_unique<HashSink>(info->narHash.type);
                 else
-                    hashSink = std::make_unique<HashModuloSink>(info->narHash.type, storePathToHash(printStorePath(info->path)));
+                    hashSink = std::make_unique<HashModuloSink>(info->narHash.type, std::string(info->path.hashPart()));
 
                 dumpPath(Store::toRealPath(i), *hashSink);
                 auto current = hashSink->finish();
@@ -1282,7 +1264,7 @@ bool LocalStore::verifyStore(bool checkContents, RepairFlag repair)
                     logError({
                         .name = "Invalid hash - path modified",
                         .hint = hintfmt("path '%s' was modified! expected hash '%s', got '%s'",
-                        printStorePath(i), info->narHash.to_string(), current.first.to_string())
+                        printStorePath(i), info->narHash.to_string(Base32, true), current.first.to_string(Base32, true))
                     });
                     if (repair) repairPath(i); else errors = true;
                 } else {

src/libstore/local-store.hh

@@ -135,8 +135,6 @@ public:
 
     StorePathSet queryDerivationOutputs(const StorePath & path) override;
 
-    StringSet queryDerivationOutputNames(const StorePath & path) override;
-
     std::optional<StorePath> queryPathFromHashPart(const std::string & hashPart) override;
 
     StorePathSet querySubstitutablePaths(const StorePathSet & paths) override;

src/libstore/local.mk

@@ -6,7 +6,7 @@ libstore_DIR := $(d)
 
 libstore_SOURCES := $(wildcard $(d)/*.cc $(d)/builtins/*.cc)
 
-libstore_LIBS = libutil libnixrust
+libstore_LIBS = libutil
 
 libstore_LDFLAGS = $(SQLITE3_LIBS) -lbz2 $(LIBCURL_LIBS) $(SODIUM_LIBS) -pthread
 ifneq ($(OS), FreeBSD)

src/libstore/misc.cc

@@ -103,7 +103,7 @@ void Store::computeFSClosure(const StorePath & startPath,
     StorePathSet & paths_, bool flipDirection, bool includeOutputs, bool includeDerivers)
 {
     StorePathSet paths;
-    paths.insert(startPath.clone());
+    paths.insert(startPath);
     computeFSClosure(paths, paths_, flipDirection, includeOutputs, includeDerivers);
 }
 
@@ -141,11 +141,11 @@ void Store::queryMissing(const std::vector<StorePathWithOutputs> & targets,
     auto mustBuildDrv = [&](const StorePath & drvPath, const Derivation & drv) {
         {
             auto state(state_.lock());
-            state->willBuild.insert(drvPath.clone());
+            state->willBuild.insert(drvPath);
         }
 
         for (auto & i : drv.inputDrvs)
-            pool.enqueue(std::bind(doPath, StorePathWithOutputs(i.first, i.second)));
+            pool.enqueue(std::bind(doPath, StorePathWithOutputs { i.first, i.second }));
     };
 
     auto checkOutput = [&](
@@ -157,9 +157,7 @@ void Store::queryMissing(const std::vector<StorePathWithOutputs> & targets,
         auto outPath = parseStorePath(outPathS);
 
         SubstitutablePathInfos infos;
-        StorePathSet paths; // FIXME
+        querySubstitutablePathInfos({outPath}, infos);
-        paths.insert(outPath.clone());
-        querySubstitutablePathInfos(paths, infos);
 
         if (infos.empty()) {
             drvState_->lock()->done = true;
@@ -170,10 +168,10 @@ void Store::queryMissing(const std::vector<StorePathWithOutputs> & targets,
                 if (drvState->done) return;
                 assert(drvState->left);
                 drvState->left--;
-                drvState->outPaths.insert(outPath.clone());
+                drvState->outPaths.insert(outPath);
                 if (!drvState->left) {
                     for (auto & path : drvState->outPaths)
-                        pool.enqueue(std::bind(doPath, StorePathWithOutputs(path.clone())));
+                        pool.enqueue(std::bind(doPath, StorePathWithOutputs { path } ));
                 }
             }
         }
@@ -190,12 +188,12 @@ void Store::queryMissing(const std::vector<StorePathWithOutputs> & targets,
             if (!isValidPath(path.path)) {
                 // FIXME: we could try to substitute the derivation.
                 auto state(state_.lock());
-                state->unknown.insert(path.path.clone());
+                state->unknown.insert(path.path);
                 return;
             }
 
             auto drv = make_ref<Derivation>(derivationFromPath(path.path));
-            ParsedDerivation parsedDrv(path.path.clone(), *drv);
+            ParsedDerivation parsedDrv(StorePath(path.path), *drv);
 
             PathSet invalid;
             for (auto & j : drv->outputs)
@@ -216,13 +214,11 @@ void Store::queryMissing(const std::vector<StorePathWithOutputs> & targets,
             if (isValidPath(path.path)) return;
 
             SubstitutablePathInfos infos;
-            StorePathSet paths; // FIXME
+            querySubstitutablePathInfos({path.path}, infos);
-            paths.insert(path.path.clone());
-            querySubstitutablePathInfos(paths, infos);
 
             if (infos.empty()) {
                 auto state(state_.lock());
-                state->unknown.insert(path.path.clone());
+                state->unknown.insert(path.path);
                 return;
             }
 
@@ -231,13 +227,13 @@ void Store::queryMissing(const std::vector<StorePathWithOutputs> & targets,
 
             {
                 auto state(state_.lock());
-                state->willSubstitute.insert(path.path.clone());
+                state->willSubstitute.insert(path.path);
                 state->downloadSize += info->second.downloadSize;
                 state->narSize += info->second.narSize;
             }
 
             for (auto & ref : info->second.references)
-                pool.enqueue(std::bind(doPath, StorePathWithOutputs(ref)));
+                pool.enqueue(std::bind(doPath, StorePathWithOutputs { ref }));
         }
     };
 
@@ -260,12 +256,12 @@ StorePaths Store::topoSortPaths(const StorePathSet & paths)
             throw BuildError("cycle detected in the references of '%s' from '%s'",
                 printStorePath(path), printStorePath(*parent));
 
-        if (!visited.insert(path.clone()).second) return;
+        if (!visited.insert(path).second) return;
-        parents.insert(path.clone());
+        parents.insert(path);
 
         StorePathSet references;
         try {
-            references = cloneStorePathSet(queryPathInfo(path)->references);
+            references = queryPathInfo(path)->references;
         } catch (InvalidPath &) {
         }
 
@@ -275,7 +271,7 @@ StorePaths Store::topoSortPaths(const StorePathSet & paths)
             if (i != path && paths.count(i))
                 dfsVisit(i, &path);
 
-        sorted.push_back(path.clone());
+        sorted.push_back(path);
         parents.erase(path);
     };
 

src/libstore/nar-info-disk-cache.cc

@@ -189,7 +189,7 @@ public:
                 return {oInvalid, 0};
 
             auto namePart = queryNAR.getStr(1);
-            auto narInfo = make_ref<NarInfo>(StorePath::fromBaseName(hashPart + "-" + namePart));
+            auto narInfo = make_ref<NarInfo>(StorePath(hashPart + "-" + namePart));
             narInfo->url = queryNAR.getStr(2);
             narInfo->compression = queryNAR.getStr(3);
             if (!queryNAR.isNull(4))
@@ -198,9 +198,9 @@ public:
             narInfo->narHash = Hash(queryNAR.getStr(6));
             narInfo->narSize = queryNAR.getInt(7);
             for (auto & r : tokenizeString<Strings>(queryNAR.getStr(8), " "))
-                narInfo->references.insert(StorePath::fromBaseName(r));
+                narInfo->references.insert(StorePath(r));
             if (!queryNAR.isNull(9))
-                narInfo->deriver = StorePath::fromBaseName(queryNAR.getStr(9));
+                narInfo->deriver = StorePath(queryNAR.getStr(9));
             for (auto & sig : tokenizeString<Strings>(queryNAR.getStr(10), " "))
                 narInfo->sigs.insert(sig);
             narInfo->ca = queryNAR.getStr(11);
@@ -230,9 +230,9 @@ public:
                     (std::string(info->path.name()))
                     (narInfo ? narInfo->url : "", narInfo != 0)
                     (narInfo ? narInfo->compression : "", narInfo != 0)
-                    (narInfo && narInfo->fileHash ? narInfo->fileHash.to_string() : "", narInfo && narInfo->fileHash)
+                    (narInfo && narInfo->fileHash ? narInfo->fileHash.to_string(Base32, true) : "", narInfo && narInfo->fileHash)
                     (narInfo ? narInfo->fileSize : 0, narInfo != 0 && narInfo->fileSize)
-                    (info->narHash.to_string())
+                    (info->narHash.to_string(Base32, true))
                     (info->narSize)
                     (concatStringsSep(" ", info->shortRefs()))
                     (info->deriver ? std::string(info->deriver->to_string()) : "", (bool) info->deriver)

src/libstore/nar-info.cc

@@ -4,7 +4,7 @@
 namespace nix {
 
 NarInfo::NarInfo(const Store & store, const std::string & s, const std::string & whence)
-    : ValidPathInfo(StorePath::dummy.clone()) // FIXME: hack
+    : ValidPathInfo(StorePath(StorePath::dummy)) // FIXME: hack
 {
     auto corrupt = [&]() {
         throw Error("NAR info file '%1%' is corrupt", whence);
@@ -56,11 +56,11 @@ NarInfo::NarInfo(const Store & store, const std::string & s, const std::string &
             auto refs = tokenizeString<Strings>(value, " ");
             if (!references.empty()) corrupt();
             for (auto & r : refs)
-                references.insert(StorePath::fromBaseName(r));
+                references.insert(StorePath(r));
         }
         else if (name == "Deriver") {
             if (value != "unknown-deriver")
-                deriver = StorePath::fromBaseName(value);
+                deriver = StorePath(value);
         }
         else if (name == "System")
             system = value;
@@ -87,10 +87,10 @@ std::string NarInfo::to_string(const Store & store) const
     assert(compression != "");
     res += "Compression: " + compression + "\n";
     assert(fileHash.type == htSHA256);
-    res += "FileHash: " + fileHash.to_string(Base32) + "\n";
+    res += "FileHash: " + fileHash.to_string(Base32, true) + "\n";
     res += "FileSize: " + std::to_string(fileSize) + "\n";
     assert(narHash.type == htSHA256);
-    res += "NarHash: " + narHash.to_string(Base32) + "\n";
+    res += "NarHash: " + narHash.to_string(Base32, true) + "\n";
     res += "NarSize: " + std::to_string(narSize) + "\n";
 
     res += "References: " + concatStringsSep(" ", shortRefs()) + "\n";

src/libstore/optimise-store.cc

@@ -153,7 +153,7 @@ void LocalStore::optimisePath_(Activity * act, OptimiseStats & stats,
        contents of the symlink (i.e. the result of readlink()), not
        the contents of the target (which may not even exist). */
     Hash hash = hashPath(htSHA256, path).first;
-    debug(format("'%1%' has hash '%2%'") % path % hash.to_string());
+    debug(format("'%1%' has hash '%2%'") % path % hash.to_string(Base32, true));
 
     /* Check if this is a known hash. */
     Path linkPath = linksDir + "/" + hash.to_string(Base32, false);

src/libstore/parsed-derivations.cc

@@ -4,8 +4,8 @@
 
 namespace nix {
 
-ParsedDerivation::ParsedDerivation(StorePath && drvPath, BasicDerivation & drv)
+ParsedDerivation::ParsedDerivation(const StorePath & drvPath, BasicDerivation & drv)
-    : drvPath(std::move(drvPath)), drv(drv)
+    : drvPath(drvPath), drv(drv)
 {
     /* Parse the __json attribute, if any. */
     auto jsonAttr = drv.env.find("__json");
@@ -117,4 +117,9 @@ bool ParsedDerivation::substitutesAllowed() const
     return getBoolAttr("allowSubstitutes", true);
 }
 
+bool ParsedDerivation::contentAddressed() const
+{
+    return getBoolAttr("__contentAddressed", false);
+}
+
 }

src/libstore/parsed-derivations.hh

@@ -12,7 +12,7 @@ class ParsedDerivation
 
 public:
 
-    ParsedDerivation(StorePath && drvPath, BasicDerivation & drv);
+    ParsedDerivation(const StorePath & drvPath, BasicDerivation & drv);
 
     ~ParsedDerivation();
 
@@ -34,6 +34,8 @@ public:
     bool willBuildLocally() const;
 
     bool substitutesAllowed() const;
+
+    bool contentAddressed() const;
 };
 
 }

src/libstore/path.cc

@@ -2,38 +2,38 @@
 
 namespace nix {
 
-extern "C" {
+MakeError(BadStorePath, Error);
-    rust::Result<StorePath> ffi_StorePath_new(rust::StringSlice path, rust::StringSlice storeDir);
+
-    rust::Result<StorePath> ffi_StorePath_new2(unsigned char hash[20], rust::StringSlice storeDir);
+static void checkName(std::string_view path, std::string_view name)
-    rust::Result<StorePath> ffi_StorePath_fromBaseName(rust::StringSlice baseName);
+{
-    rust::String ffi_StorePath_to_string(const StorePath & _this);
+    if (name.empty())
-    StorePath ffi_StorePath_clone(const StorePath & _this);
+        throw BadStorePath("store path '%s' has an empty name", path);
-    rust::StringSlice ffi_StorePath_name(const StorePath & _this);
+    if (name.size() > 211)
+        throw BadStorePath("store path '%s' has a name longer than 211 characters", path);
+    for (auto c : name)
+        if (!((c >= '0' && c <= '9')
+                || (c >= 'a' && c <= 'z')
+                || (c >= 'A' && c <= 'Z')
+                || c == '+' || c == '-' || c == '.' || c == '_' || c == '?' || c == '='))
+            throw BadStorePath("store path '%s' contains illegal character '%s'", path, c);
 }
 
-StorePath StorePath::make(std::string_view path, std::string_view storeDir)
+StorePath::StorePath(std::string_view _baseName)
+    : baseName(_baseName)
 {
-    return ffi_StorePath_new((rust::StringSlice) path, (rust::StringSlice) storeDir).unwrap();
+    if (baseName.size() < HashLen + 1)
+        throw BadStorePath("'%s' is too short to be a valid store path", baseName);
+    for (auto c : hashPart())
+        if (c == 'e' || c == 'o' || c == 'u' || c == 't'
+            || !((c >= '0' && c <= '9') || (c >= 'a' && c <= 'z')))
+            throw BadStorePath("store path '%s' contains illegal base-32 character '%s'", baseName, c);
+    checkName(baseName, name());
 }
 
-StorePath StorePath::make(unsigned char hash[20], std::string_view name)
+StorePath::StorePath(const Hash & hash, std::string_view _name)
+    : baseName((hash.to_string(Base32, false) + "-").append(std::string(_name)))
 {
-    return ffi_StorePath_new2(hash, (rust::StringSlice) name).unwrap();
+    checkName(baseName, name());
-}
-
-StorePath StorePath::fromBaseName(std::string_view baseName)
-{
-    return ffi_StorePath_fromBaseName((rust::StringSlice) baseName).unwrap();
-}
-
-rust::String StorePath::to_string() const
-{
-    return ffi_StorePath_to_string(*this);
-}
-
-StorePath StorePath::clone() const
-{
-    return ffi_StorePath_clone(*this);
 }
 
 bool StorePath::isDerivation() const
@@ -41,18 +41,14 @@ bool StorePath::isDerivation() const
     return hasSuffix(name(), drvExtension);
 }
 
-std::string_view StorePath::name() const
+StorePath StorePath::dummy("ffffffffffffffffffffffffffffffff-x");
-{
-    return ffi_StorePath_name(*this);
-}
-
-StorePath StorePath::dummy(
-    StorePath::make(
-        (unsigned char *) "xxxxxxxxxxxxxxxxxxxx", "x"));
 
 StorePath Store::parseStorePath(std::string_view path) const
 {
-    return StorePath::make(path, storeDir);
+    auto p = canonPath(std::string(path));
+    if (dirOf(p) != storeDir)
+        throw BadStorePath("path '%s' is not in the Nix store", p);
+    return StorePath(baseNameOf(p));
 }
 
 std::optional<StorePath> Store::maybeParseStorePath(std::string_view path) const
@@ -78,9 +74,7 @@ StorePathSet Store::parseStorePathSet(const PathSet & paths) const
 
 std::string Store::printStorePath(const StorePath & path) const
 {
-    auto s = storeDir + "/";
+    return (storeDir + "/").append(path.to_string());
-    s += (std::string_view) path.to_string();
-    return s;
 }
 
 PathSet Store::printStorePathSet(const StorePathSet & paths) const
@@ -90,29 +84,6 @@ PathSet Store::printStorePathSet(const StorePathSet & paths) const
     return res;
 }
 
-StorePathSet cloneStorePathSet(const StorePathSet & paths)
-{
-    StorePathSet res;
-    for (auto & p : paths)
-        res.insert(p.clone());
-    return res;
-}
-
-StorePathSet storePathsToSet(const StorePaths & paths)
-{
-    StorePathSet res;
-    for (auto & p : paths)
-        res.insert(p.clone());
-    return res;
-}
-
-StorePathSet singleton(const StorePath & path)
-{
-    StorePathSet res;
-    res.insert(path.clone());
-    return res;
-}
-
 std::pair<std::string_view, StringSet> parsePathWithOutputs(std::string_view s)
 {
     size_t n = s.find("!");

src/libstore/path.hh

@@ -1,59 +1,59 @@
 #pragma once
 
-#include "rust-ffi.hh"
+#include "types.hh"
 
 namespace nix {
 
-/* See path.rs. */
-struct StorePath;
-
 class Store;
+struct Hash;
 
-extern "C" {
+class StorePath
-    void ffi_StorePath_drop(void *);
-    bool ffi_StorePath_less_than(const StorePath & a, const StorePath & b);
-    bool ffi_StorePath_eq(const StorePath & a, const StorePath & b);
-    unsigned char * ffi_StorePath_hash_data(const StorePath & p);
-}
-
-struct StorePath : rust::Value<3 * sizeof(void *) + 24, ffi_StorePath_drop>
 {
+    std::string baseName;
+
+public:
+
+    /* Size of the hash part of store paths, in base-32 characters. */
+    constexpr static size_t HashLen = 32; // i.e. 160 bits
+
     StorePath() = delete;
 
-    static StorePath make(std::string_view path, std::string_view storeDir);
+    StorePath(std::string_view baseName);
 
-    static StorePath make(unsigned char hash[20], std::string_view name);
+    StorePath(const Hash & hash, std::string_view name);
 
-    static StorePath fromBaseName(std::string_view baseName);
+    std::string_view to_string() const
-
+    {
-    rust::String to_string() const;
+        return baseName;
+    }
 
     bool operator < (const StorePath & other) const
     {
-        return ffi_StorePath_less_than(*this, other);
+        return baseName < other.baseName;
     }
 
     bool operator == (const StorePath & other) const
     {
-        return ffi_StorePath_eq(*this, other);
+        return baseName == other.baseName;
     }
 
     bool operator != (const StorePath & other) const
     {
-        return !(*this == other);
+        return baseName != other.baseName;
     }
 
-    StorePath clone() const;
-
     /* Check whether a file name ends with the extension for
        derivations. */
     bool isDerivation() const;
 
-    std::string_view name() const;
+    std::string_view name() const
-
-    unsigned char * hashData() const
     {
-        return ffi_StorePath_hash_data(*this);
+        return std::string_view(baseName).substr(HashLen + 1);
+    }
+
+    std::string_view hashPart() const
+    {
+        return std::string_view(baseName).substr(0, HashLen);
     }
 
     static StorePath dummy;
@@ -62,14 +62,6 @@ struct StorePath : rust::Value<3 * sizeof(void *) + 24, ffi_StorePath_drop>
 typedef std::set<StorePath> StorePathSet;
 typedef std::vector<StorePath> StorePaths;
 
-StorePathSet cloneStorePathSet(const StorePathSet & paths);
-StorePathSet storePathsToSet(const StorePaths & paths);
-
-StorePathSet singleton(const StorePath & path);
-
-/* Size of the hash part of store paths, in base-32 characters. */
-const size_t storePathHashLen = 32; // i.e. 160 bits
-
 /* Extension of derivations in the Nix store. */
 const std::string drvExtension = ".drv";
 
@@ -83,18 +75,6 @@ struct StorePathWithOutputs
     StorePath path;
     std::set<std::string> outputs;
 
-    StorePathWithOutputs(const StorePath & path, const std::set<std::string> & outputs = {})
-        : path(path.clone()), outputs(outputs)
-    { }
-
-    StorePathWithOutputs(StorePath && path, std::set<std::string> && outputs)
-        : path(std::move(path)), outputs(std::move(outputs))
-    { }
-
-    StorePathWithOutputs(const StorePathWithOutputs & other)
-        : path(other.path.clone()), outputs(other.outputs)
-    { }
-
     std::string to_string(const Store & store) const;
 };
 
@@ -107,7 +87,7 @@ namespace std {
 template<> struct hash<nix::StorePath> {
     std::size_t operator()(const nix::StorePath & path) const noexcept
     {
-        return * (std::size_t *) path.hashData();
+        return * (std::size_t *) path.to_string().data();
     }
 };
 

src/libstore/remote-fs-accessor.cc

@@ -19,7 +19,7 @@ RemoteFSAccessor::RemoteFSAccessor(ref<Store> store, const Path & cacheDir)
 Path RemoteFSAccessor::makeCacheFile(const Path & storePath, const std::string & ext)
 {
     assert(cacheDir != "");
-    return fmt("%s/%s.%s", cacheDir, storePathToHash(storePath), ext);
+    return fmt("%s/%s.%s", cacheDir, store->parseStorePath(storePath).hashPart(), ext);
 }
 
 void RemoteFSAccessor::addToCache(const Path & storePath, const std::string & nar,

src/libstore/remote-store.cc

@@ -228,7 +228,7 @@ struct ConnectionHandle
 
     ~ConnectionHandle()
     {
-        if (!daemonException && std::uncaught_exception()) {
+        if (!daemonException && std::uncaught_exceptions()) {
             handle.markBad();
             debug("closing daemon connection because of an exception");
         }
@@ -268,7 +268,7 @@ StorePathSet RemoteStore::queryValidPaths(const StorePathSet & paths, Substitute
     if (GET_PROTOCOL_MINOR(conn->daemonVersion) < 12) {
         StorePathSet res;
         for (auto & i : paths)
-            if (isValidPath(i)) res.insert(i.clone());
+            if (isValidPath(i)) res.insert(i);
         return res;
     } else {
         conn->to << wopQueryValidPaths;
@@ -296,7 +296,7 @@ StorePathSet RemoteStore::querySubstitutablePaths(const StorePathSet & paths)
         for (auto & i : paths) {
             conn->to << wopHasSubstitutes << printStorePath(i);
             conn.processStderr();
-            if (readInt(conn->from)) res.insert(i.clone());
+            if (readInt(conn->from)) res.insert(i);
         }
         return res;
     } else {
@@ -329,7 +329,7 @@ void RemoteStore::querySubstitutablePathInfos(const StorePathSet & paths,
             info.references = readStorePaths<StorePathSet>(*this, conn->from);
             info.downloadSize = readLongLong(conn->from);
             info.narSize = readLongLong(conn->from);
-            infos.insert_or_assign(i.clone(), std::move(info));
+            infos.insert_or_assign(i, std::move(info));
         }
 
     } else {
@@ -372,7 +372,7 @@ void RemoteStore::queryPathInfoUncached(const StorePath & path,
                 bool valid; conn->from >> valid;
                 if (!valid) throw InvalidPath("path '%s' is not valid", printStorePath(path));
             }
-            info = std::make_shared<ValidPathInfo>(path.clone());
+            info = std::make_shared<ValidPathInfo>(StorePath(path));
             auto deriver = readString(conn->from);
             if (deriver != "") info->deriver = parseStorePath(deriver);
             info->narHash = Hash(readString(conn->from), htSHA256);
@@ -396,7 +396,7 @@ void RemoteStore::queryReferrers(const StorePath & path,
     conn->to << wopQueryReferrers << printStorePath(path);
     conn.processStderr();
     for (auto & i : readStorePaths<StorePathSet>(*this, conn->from))
-        referrers.insert(i.clone());
+        referrers.insert(i);
 }
 
 
@@ -418,15 +418,6 @@ StorePathSet RemoteStore::queryDerivationOutputs(const StorePath & path)
 }
 
 
-PathSet RemoteStore::queryDerivationOutputNames(const StorePath & path)
-{
-    auto conn(getConnection());
-    conn->to << wopQueryDerivationOutputNames << printStorePath(path);
-    conn.processStderr();
-    return readStrings<PathSet>(conn->from);
-}
-
-
 std::optional<StorePath> RemoteStore::queryPathFromHashPart(const std::string & hashPart)
 {
     auto conn(getConnection());

src/libstore/remote-store.hh

@@ -51,8 +51,6 @@ public:
 
     StorePathSet queryDerivationOutputs(const StorePath & path) override;
 
-    StringSet queryDerivationOutputNames(const StorePath & path) override;
-
     std::optional<StorePath> queryPathFromHashPart(const std::string & hashPart) override;
 
     StorePathSet querySubstitutablePaths(const StorePathSet & paths) override;

src/libstore/sqlite.cc

@@ -204,8 +204,8 @@ void handleSQLiteBusy(const SQLiteBusy & e)
 
     if (now > lastWarned + 10) {
         lastWarned = now;
-        logWarning(
+        logWarning({
-            ErrorInfo { .name = "Sqlite busy",
+            .name = "Sqlite busy",
             .hint = hintfmt(e.what())
         });
     }

src/libstore/store-api.cc

@@ -55,21 +55,13 @@ StorePath Store::followLinksToStorePath(std::string_view path) const
 StorePathWithOutputs Store::followLinksToStorePathWithOutputs(std::string_view path) const
 {
     auto [path2, outputs] = nix::parsePathWithOutputs(path);
-    return StorePathWithOutputs(followLinksToStorePath(path2), std::move(outputs));
+    return StorePathWithOutputs { followLinksToStorePath(path2), std::move(outputs) };
-}
-
-
-string storePathToHash(const Path & path)
-{
-    auto base = baseNameOf(path);
-    assert(base.size() >= storePathHashLen);
-    return string(base, 0, storePathHashLen);
 }
 
 
 /* Store paths have the following form:
 
-   <store>/<h>-<name>
+   <realized-path> = <store>/<h>-<name>
 
    where
 
@@ -93,11 +85,14 @@ string storePathToHash(const Path & path)
    <type> = one of:
      "text:<r1>:<r2>:...<rN>"
        for plain text files written to the store using
-       addTextToStore(); <r1> ... <rN> are the references of the
+       addTextToStore(); <r1> ... <rN> are the store paths referenced
-       path.
+       by this path, in the form described by <realized-path>
-     "source"
+     "source:<r1>:<r2>:...:<rN>:self"
        for paths copied to the store using addToStore() when recursive
-       = true and hashAlgo = "sha256"
+       = true and hashAlgo = "sha256". Just like in the text case, we
+       can have the store paths referenced by the path.
+       Additionally, we can have an optional :self label to denote self
+       reference.
      "output:<id>"
        for either the outputs created by derivations, OR paths copied
        to the store using addToStore() with recursive != true or
@@ -125,6 +120,12 @@ string storePathToHash(const Path & path)
              the contents of the path (or expected contents of the
              path for fixed-output derivations)
 
+   Note that since an output derivation has always type output, while
+   something added by addToStore can have type output or source depending
+   on the hash, this means that the same input can be hashed differently
+   if added to the store via addToStore or via a derivation, in the sha256
+   recursive case.
+
    It would have been nicer to handle fixed-output derivations under
    "source", e.g. have something like "source:<rec><algo>", but we're
    stuck with this for now...
@@ -142,9 +143,9 @@ StorePath Store::makeStorePath(const string & type,
     const Hash & hash, std::string_view name) const
 {
     /* e.g., "source:sha256:1abc...:/nix/store:foo.tar.gz" */
-    string s = type + ":" + hash.to_string(Base16) + ":" + storeDir + ":" + std::string(name);
+    string s = type + ":" + hash.to_string(Base16, true) + ":" + storeDir + ":" + std::string(name);
     auto h = compressHash(hashString(htSHA256, s), 20);
-    return StorePath::make(h.hash, name);
+    return StorePath(h, name);
 }
 
 
@@ -186,7 +187,7 @@ StorePath Store::makeFixedOutputPath(
             hashString(htSHA256,
                 "fixed:out:"
                 + (recursive == FileIngestionMethod::Recursive ? (string) "r:" : "")
-                + hash.to_string(Base16) + ":"),
+                + hash.to_string(Base16, true) + ":"),
             name);
     }
 }
@@ -243,7 +244,7 @@ bool Store::PathInfoCacheValue::isKnownNow()
 
 bool Store::isValidPath(const StorePath & storePath)
 {
-    auto hashPart = storePathToHash(printStorePath(storePath));
+    std::string hashPart(storePath.hashPart());
 
     {
         auto state_(state.lock());
@@ -311,7 +312,7 @@ void Store::queryPathInfo(const StorePath & storePath,
     std::string hashPart;
 
     try {
-        hashPart = storePathToHash(printStorePath(storePath));
+        hashPart = storePath.hashPart();
 
         {
             auto res = state.lock()->pathInfoCache.get(hashPart);
@@ -461,7 +462,7 @@ void Store::pathInfoToJSON(JSONPlaceholder & jsonOut, const StorePathSet & store
             auto info = queryPathInfo(storePath);
 
             jsonPath
-                .attr("narHash", info->narHash.to_string(hashBase))
+                .attr("narHash", info->narHash.to_string(hashBase, true))
                 .attr("narSize", info->narSize);
 
             {
@@ -504,7 +505,7 @@ void Store::pathInfoToJSON(JSONPlaceholder & jsonOut, const StorePathSet & store
                     if (!narInfo->url.empty())
                         jsonPath.attr("url", narInfo->url);
                     if (narInfo->fileHash)
-                        jsonPath.attr("downloadHash", narInfo->fileHash.to_string());
+                        jsonPath.attr("downloadHash", narInfo->fileHash.to_string(Base32, true));
                     if (narInfo->fileSize)
                         jsonPath.attr("downloadSize", narInfo->fileSize);
                     if (showClosureSize)
@@ -553,7 +554,7 @@ void Store::buildPaths(const std::vector<StorePathWithOutputs> & paths, BuildMod
     for (auto & path : paths) {
         if (path.path.isDerivation())
             unsupported("buildPaths");
-        paths2.insert(path.path.clone());
+        paths2.insert(path.path);
     }
 
     if (queryValidPaths(paths2).size() != paths2.size())
@@ -693,21 +694,6 @@ void copyClosure(ref<Store> srcStore, ref<Store> dstStore,
 }
 
 
-ValidPathInfo::ValidPathInfo(const ValidPathInfo & other)
-    : path(other.path.clone())
-    , deriver(other.deriver ? other.deriver->clone(): std::optional<StorePath>{})
-    , narHash(other.narHash)
-    , references(cloneStorePathSet(other.references))
-    , registrationTime(other.registrationTime)
-    , narSize(other.narSize)
-    , id(other.id)
-    , ultimate(other.ultimate)
-    , sigs(other.sigs)
-    , ca(other.ca)
-{
-}
-
-
 std::optional<ValidPathInfo> decodeValidPathInfo(const Store & store, std::istream & str, bool hashGiven)
 {
     std::string path;
@@ -760,7 +746,7 @@ std::string ValidPathInfo::fingerprint(const Store & store) const
             store.printStorePath(path));
     return
         "1;" + store.printStorePath(path) + ";"
-        + narHash.to_string(Base32) + ";"
+        + narHash.to_string(Base32, true) + ";"
         + std::to_string(narSize) + ";"
         + concatStringsSep(",", store.printStorePathSet(references));
 }
@@ -783,7 +769,7 @@ bool ValidPathInfo::isContentAddressed(const Store & store) const
     };
 
     if (hasPrefix(ca, "text:")) {
-        Hash hash(std::string(ca, 5));
+        Hash hash(ca.substr(5));
         if (store.makeTextPath(path.name(), hash, references) == path)
             return true;
         else
@@ -792,8 +778,8 @@ bool ValidPathInfo::isContentAddressed(const Store & store) const
 
     else if (hasPrefix(ca, "fixed:")) {
         FileIngestionMethod recursive { ca.compare(6, 2, "r:") == 0 };
-        Hash hash(std::string(ca, recursive == FileIngestionMethod::Recursive ? 8 : 6));
+        Hash hash(ca.substr(recursive == FileIngestionMethod::Recursive ? 8 : 6));
-        auto refs = cloneStorePathSet(references);
+        auto refs = references;
         bool hasSelfReference = false;
         if (refs.count(path)) {
             hasSelfReference = true;
@@ -840,7 +826,7 @@ std::string makeFixedOutputCA(FileIngestionMethod recursive, const Hash & hash)
 {
     return "fixed:"
         + (recursive == FileIngestionMethod::Recursive ? (std::string) "r:" : "")
-        + hash.to_string();
+        + hash.to_string(Base32, true);
 }
 
 

src/libstore/store-api.hh

@@ -189,8 +189,9 @@ struct ValidPathInfo
 
     Strings shortRefs() const;
 
+    ValidPathInfo(const StorePath & path) : path(path) { }
+
     ValidPathInfo(StorePath && path) : path(std::move(path)) { }
-    explicit ValidPathInfo(const ValidPathInfo & other);
 
     virtual ~ValidPathInfo() { }
 };
@@ -430,10 +431,6 @@ public:
     virtual StorePathSet queryDerivationOutputs(const StorePath & path)
     { unsupported("queryDerivationOutputs"); }
 
-    /* Query the output names of the derivation denoted by `path'. */
-    virtual StringSet queryDerivationOutputNames(const StorePath & path)
-    { unsupported("queryDerivationOutputNames"); }
-
     /* Query the full store path given the hash part of a valid store
        path, or empty if the path doesn't exist. */
     virtual std::optional<StorePath> queryPathFromHashPart(const std::string & hashPart) = 0;
@@ -587,6 +584,9 @@ public:
        ensurePath(). */
     Derivation derivationFromPath(const StorePath & drvPath);
 
+    /* Read a derivation (which must already be valid). */
+    Derivation readDerivation(const StorePath & drvPath);
+
     /* Place in `out' the set of all store paths in the file system
        closure of `storePath'; that is, all paths than can be directly
        or indirectly reached from it.  `out' is not cleared.  If
@@ -732,10 +732,6 @@ public:
 };
 
 
-/* Extract the hash part of the given store path. */
-string storePathToHash(const Path & path);
-
-
 /* Copy a path from one store to another. */
 void copyStorePath(ref<Store> srcStore, ref<Store> dstStore,
     const StorePath & storePath, RepairFlag repair = NoRepair, CheckSigsFlag checkSigs = CheckSigs);

src/libstore/worker-protocol.hh

@@ -36,7 +36,7 @@ typedef enum {
     wopClearFailedPaths = 25,
     wopQueryPathInfo = 26,
     wopImportPaths = 27, // obsolete
-    wopQueryDerivationOutputNames = 28,
+    wopQueryDerivationOutputNames = 28, // obsolete
     wopQueryPathFromHashPart = 29,
     wopQuerySubstitutablePathInfos = 30,
     wopQueryValidPaths = 31,

src/libutil/ansicolor.hh

@@ -11,5 +11,7 @@ namespace nix {
 #define ANSI_GREEN "\e[32;1m"
 #define ANSI_YELLOW "\e[33;1m"
 #define ANSI_BLUE "\e[34;1m"
+#define ANSI_MAGENTA "\e[35m;1m"
+#define ANSI_CYAN "\e[36m;1m"
 
 }

src/libutil/args.cc

@@ -217,10 +217,15 @@ MultiCommand::MultiCommand(const Commands & commands)
 {
     expectedArgs.push_back(ExpectedArg{"command", 1, true, [=](std::vector<std::string> ss) {
         assert(!command);
-        auto i = commands.find(ss[0]);
+        auto cmd = ss[0];
+        if (auto alias = get(deprecatedAliases, cmd)) {
+            warn("'%s' is a deprecated alias for '%s'", cmd, *alias);
+            cmd = *alias;
+        }
+        auto i = commands.find(cmd);
         if (i == commands.end())
-            throw UsageError("'%s' is not a recognised command", ss[0]);
+            throw UsageError("'%s' is not a recognised command", cmd);
-        command = {ss[0], i->second()};
+        command = {cmd, i->second()};
     }});
 
     categories[Command::catDefault] = "Available commands";

src/libutil/args.hh

@@ -234,6 +234,8 @@ public:
 
     std::map<Command::Category, std::string> categories;
 
+    std::map<std::string, std::string> deprecatedAliases;
+
     // Selected command, if any.
     std::optional<std::pair<std::string, ref<Command>>> command;
 

src/libutil/config.hh

@@ -1,3 +1,4 @@
+#include <cassert>
 #include <map>
 #include <set>
 

src/libutil/error.cc

@@ -176,7 +176,7 @@ void printCodeLines(std::ostream &out, const string &prefix, const NixCode &nixC
 
 std::ostream& operator<<(std::ostream &out, const ErrorInfo &einfo)
 {
-    int errwidth = 80;
+    auto errwidth = std::max<size_t>(getWindowSize().second, 20);
     string prefix = "";
 
     string levelString;
@@ -229,12 +229,10 @@ std::ostream& operator<<(std::ostream &out, const ErrorInfo &einfo)
         }
     }
 
-    int ndl = prefix.length() + levelString.length() + 3 + einfo.name.length() + einfo.programName.value_or("").length();
+    auto ndl = prefix.length() + levelString.length() + 3 + einfo.name.length() + einfo.programName.value_or("").length();
-    int dashwidth = ndl > (errwidth - 3) ? 3 : errwidth - ndl;
+    auto dashwidth = ndl > (errwidth - 3) ? 3 : errwidth - ndl;
 
-    string dashes;
+    std::string dashes(dashwidth, '-');
-    for (int i = 0; i < dashwidth; ++i)
-        dashes.append("-");
 
     // divider.
     if (einfo.name != "")

src/libutil/error.hh

@@ -4,6 +4,7 @@
 #include "ref.hh"
 #include "types.hh"
 
+#include <cstring>
 #include <list>
 #include <memory>
 #include <map>
@@ -127,9 +128,9 @@ public:
     { }
 
     template<typename... Args>
-    BaseError(const Args & ... args)
+    BaseError(const std::string & fs, const Args & ... args)
         : err { .level = lvlError,
-                .hint = hintfmt(args...)
+                .hint = hintfmt(fs, args...)
               }
     { }
 
@@ -139,7 +140,11 @@ public:
               }
     { }
 
-    BaseError(ErrorInfo e)
+    BaseError(ErrorInfo && e)
+        : err(std::move(e))
+    { }
+
+    BaseError(const ErrorInfo & e)
         : err(e)
     { }
 

src/libutil/hash.cc

@@ -125,7 +125,7 @@ std::string Hash::to_string(Base base, bool includeType) const
 }
 
 
-Hash::Hash(const std::string & s, HashType type)
+Hash::Hash(std::string_view s, HashType type)
     : type(type)
 {
     size_t pos = 0;
@@ -194,7 +194,7 @@ Hash::Hash(const std::string & s, HashType type)
     }
 
     else if (isSRI || size == base64Len()) {
-        auto d = base64Decode(std::string(s, pos));
+        auto d = base64Decode(s.substr(pos));
         if (d.size() != hashSize)
             throw BadHash("invalid %s hash '%s'", isSRI ? "SRI" : "base-64", s);
         assert(hashSize);
@@ -205,6 +205,16 @@ Hash::Hash(const std::string & s, HashType type)
         throw BadHash("hash '%s' has wrong length for hash type '%s'", s, printHashType(type));
 }
 
+Hash newHashAllowEmpty(std::string hashStr, HashType ht)
+{
+    if (hashStr.empty()) {
+        Hash h(ht);
+        warn("found empty hash, assuming '%s'", h.to_string(SRI, true));
+        return h;
+    } else
+        return Hash(hashStr, ht);
+}
+
 
 union Ctx
 {

src/libutil/hash.hh

@@ -42,7 +42,7 @@ struct Hash
        Subresource Integrity hash expression). If the 'type' argument
        is htUnknown, then the hash type must be specified in the
        string. */
-    Hash(const std::string & s, HashType type = htUnknown);
+    Hash(std::string_view s, HashType type = htUnknown);
 
     void init();
 
@@ -79,7 +79,7 @@ struct Hash
     /* Return a string representation of the hash, in base-16, base-32
        or base-64. By default, this is prefixed by the hash type
        (e.g. "sha256:"). */
-    std::string to_string(Base base = Base32, bool includeType = true) const;
+    std::string to_string(Base base, bool includeType) const;
 
     std::string gitRev() const
     {
@@ -94,6 +94,8 @@ struct Hash
     }
 };
 
+/* Helper that defaults empty hashes to the 0 hash. */
+Hash newHashAllowEmpty(std::string hashStr, HashType ht);
 
 /* Print a hash in base-16 if it's MD5, or base-32 otherwise. */
 string printHash16or32(const Hash & hash);

src/libutil/json.cc

@@ -173,7 +173,7 @@ JSONObject JSONPlaceholder::object()
 
 JSONPlaceholder::~JSONPlaceholder()
 {
-    assert(!first || std::uncaught_exception());
+    assert(!first || std::uncaught_exceptions());
 }
 
 }

src/libutil/local.mk

@@ -7,5 +7,3 @@ libutil_DIR := $(d)
 libutil_SOURCES := $(wildcard $(d)/*.cc)
 
 libutil_LDFLAGS = $(LIBLZMA_LIBS) -lbz2 -pthread $(OPENSSL_LIBS) $(LIBBROTLI_LIBS) $(LIBARCHIVE_LIBS) $(BOOST_LDFLAGS) -lboost_context
-
-libutil_LIBS = libnixrust

src/libutil/logging.cc

@@ -18,7 +18,7 @@ void setCurActivity(const ActivityId activityId)
     curActivity = activityId;
 }
 
-Logger * logger = makeDefaultLogger();
+Logger * logger = makeSimpleLogger(true);
 
 void Logger::warn(const std::string & msg)
 {
@@ -35,13 +35,19 @@ class SimpleLogger : public Logger
 public:
 
     bool systemd, tty;
+    bool printBuildLogs;
 
-    SimpleLogger()
+    SimpleLogger(bool printBuildLogs)
+        : printBuildLogs(printBuildLogs)
     {
         systemd = getEnv("IN_SYSTEMD") == "1";
         tty = isatty(STDERR_FILENO);
     }
 
+    bool isVerbose() override {
+        return printBuildLogs;
+    }
+
     void log(Verbosity lvl, const FormatOrString & fs) override
     {
         if (lvl > verbosity) return;
@@ -78,6 +84,18 @@ public:
         if (lvl <= verbosity && !s.empty())
             log(lvl, s + "...");
     }
+
+    void result(ActivityId act, ResultType type, const Fields & fields) override
+    {
+        if (type == resBuildLogLine && printBuildLogs) {
+            auto lastLine = fields[0].s;
+            printError(lastLine);
+        }
+        else if (type == resPostBuildLogLine && printBuildLogs) {
+            auto lastLine = fields[0].s;
+            printError("post-build-hook: " + lastLine);
+        }
+    }
 };
 
 Verbosity verbosity = lvlInfo;
@@ -102,9 +120,9 @@ void writeToStderr(const string & s)
     }
 }
 
-Logger * makeDefaultLogger()
+Logger * makeSimpleLogger(bool printBuildLogs)
 {
-    return new SimpleLogger();
+    return new SimpleLogger(printBuildLogs);
 }
 
 std::atomic<uint64_t> nextId{(uint64_t) getpid() << 32};
@@ -121,6 +139,10 @@ struct JSONLogger : Logger {
 
     JSONLogger(Logger & prevLogger) : prevLogger(prevLogger) { }
 
+    bool isVerbose() override {
+        return true;
+    }
+
     void addFields(nlohmann::json & json, const Fields & fields)
     {
         if (fields.empty()) return;

src/libutil/logging.hh

@@ -18,6 +18,7 @@ typedef enum {
     actSubstitute = 108,
     actQueryPathInfo = 109,
     actPostBuildHook = 110,
+    actBuildWaiting = 111,
 } ActivityType;
 
 typedef enum {
@@ -54,6 +55,11 @@ public:
 
     virtual ~Logger() { }
 
+    virtual void stop() { };
+
+    // Whether the logger prints the whole build log
+    virtual bool isVerbose() { return false; }
+
     virtual void log(Verbosity lvl, const FormatOrString & fs) = 0;
 
     void log(const FormatOrString & fs)
@@ -140,7 +146,7 @@ struct PushActivity
 
 extern Logger * logger;
 
-Logger * makeDefaultLogger();
+Logger * makeSimpleLogger(bool printBuildLogs = true);
 
 Logger * makeJSONLogger(Logger & prevLogger);
 

src/libutil/rust-ffi.cc

@@ -1,3 +1,4 @@
+#if 0
 #include "logging.hh"
 #include "rust-ffi.hh"
 
@@ -20,3 +21,4 @@ std::ostream & operator << (std::ostream & str, const String & s)
 }
 
 }
+#endif

src/libutil/rust-ffi.hh

@@ -1,4 +1,5 @@
 #pragma once
+#if 0
 
 #include "serialise.hh"
 
@@ -185,3 +186,4 @@ struct Result
 };
 
 }
+#endif

src/libutil/serialise.cc

@@ -52,7 +52,7 @@ size_t threshold = 256 * 1024 * 1024;
 
 static void warnLargeDump()
 {
-    logWarning(ErrorInfo {
+    logWarning({
         .name = "Large path",
         .description = "dumping very large path (> 256 MiB); this may run out of memory"
     });

src/libutil/tests/hash.cc

@@ -11,28 +11,28 @@ namespace nix {
         // values taken from: https://tools.ietf.org/html/rfc1321
         auto s1 = "";
         auto hash = hashString(HashType::htMD5, s1);
-        ASSERT_EQ(hash.to_string(Base::Base16), "md5:d41d8cd98f00b204e9800998ecf8427e");
+        ASSERT_EQ(hash.to_string(Base::Base16, true), "md5:d41d8cd98f00b204e9800998ecf8427e");
     }
 
     TEST(hashString, testKnownMD5Hashes2) {
         // values taken from: https://tools.ietf.org/html/rfc1321
         auto s2 = "abc";
         auto hash = hashString(HashType::htMD5, s2);
-        ASSERT_EQ(hash.to_string(Base::Base16), "md5:900150983cd24fb0d6963f7d28e17f72");
+        ASSERT_EQ(hash.to_string(Base::Base16, true), "md5:900150983cd24fb0d6963f7d28e17f72");
     }
 
     TEST(hashString, testKnownSHA1Hashes1) {
         // values taken from: https://tools.ietf.org/html/rfc3174
         auto s = "abc";
         auto hash = hashString(HashType::htSHA1, s);
-        ASSERT_EQ(hash.to_string(Base::Base16),"sha1:a9993e364706816aba3e25717850c26c9cd0d89d");
+        ASSERT_EQ(hash.to_string(Base::Base16, true),"sha1:a9993e364706816aba3e25717850c26c9cd0d89d");
     }
 
     TEST(hashString, testKnownSHA1Hashes2) {
         // values taken from: https://tools.ietf.org/html/rfc3174
         auto s = "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq";
         auto hash = hashString(HashType::htSHA1, s);
-        ASSERT_EQ(hash.to_string(Base::Base16),"sha1:84983e441c3bd26ebaae4aa1f95129e5e54670f1");
+        ASSERT_EQ(hash.to_string(Base::Base16, true),"sha1:84983e441c3bd26ebaae4aa1f95129e5e54670f1");
     }
 
     TEST(hashString, testKnownSHA256Hashes1) {
@@ -40,7 +40,7 @@ namespace nix {
         auto s = "abc";
 
         auto hash = hashString(HashType::htSHA256, s);
-        ASSERT_EQ(hash.to_string(Base::Base16),
+        ASSERT_EQ(hash.to_string(Base::Base16, true),
                 "sha256:ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad");
     }
 
@@ -48,7 +48,7 @@ namespace nix {
         // values taken from: https://tools.ietf.org/html/rfc4634
         auto s = "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq";
         auto hash = hashString(HashType::htSHA256, s);
-        ASSERT_EQ(hash.to_string(Base::Base16),
+        ASSERT_EQ(hash.to_string(Base::Base16, true),
                 "sha256:248d6a61d20638b8e5c026930c3e6039a33ce45964ff2167f6ecedd419db06c1");
     }
 
@@ -56,7 +56,7 @@ namespace nix {
         // values taken from: https://tools.ietf.org/html/rfc4634
         auto s = "abc";
         auto hash = hashString(HashType::htSHA512, s);
-        ASSERT_EQ(hash.to_string(Base::Base16),
+        ASSERT_EQ(hash.to_string(Base::Base16, true),
                 "sha512:ddaf35a193617abacc417349ae20413112e6fa4e89a9"
                 "7ea20a9eeee64b55d39a2192992a274fc1a836ba3c23a3feebbd"
                 "454d4423643ce80e2a9ac94fa54ca49f");
@@ -67,7 +67,7 @@ namespace nix {
         auto s = "abcdefghbcdefghicdefghijdefghijkefghijklfghijklmghijklmnhijklmnoijklmnopjklmnopqklmnopqrlmnopqrsmnopqrstnopqrstu";
 
         auto hash = hashString(HashType::htSHA512, s);
-        ASSERT_EQ(hash.to_string(Base::Base16),
+        ASSERT_EQ(hash.to_string(Base::Base16, true),
                 "sha512:8e959b75dae313da8cf4f72814fc143f8f7779c6eb9f7fa1"
                 "7299aeadb6889018501d289e4900f7e4331b99dec4b5433a"
                 "c7d329eeb6dd26545e96e55b874be909");

src/libutil/tests/logging.cc

@@ -22,7 +22,7 @@ namespace nix {
             logger->logEI(e.info());
             auto str = testing::internal::GetCapturedStderr();
 
-            ASSERT_STREQ(str.c_str(),"\x1B[31;1merror:\x1B[0m\x1B[34;1m --- TestError ------------------------------------ error-unit-test\x1B[0m\nan error for testing purposes\n");
+            ASSERT_STREQ(str.c_str(),"\x1B[31;1merror:\x1B[0m\x1B[34;1m --- TestError --- error-unit-test\x1B[0m\nan error for testing purposes\n");
         }
     }
 
@@ -42,7 +42,7 @@ namespace nix {
             logger->logEI(ei);
             auto str = testing::internal::GetCapturedStderr();
 
-            ASSERT_STREQ(str.c_str(), "\x1B[31;1merror:\x1B[0m\x1B[34;1m --- TestError ------------------------------------ error-unit-test\x1B[0m\n\x1B[33;1m\x1B[0minitial error\x1B[0m; subsequent error message.\n");
+            ASSERT_STREQ(str.c_str(), "\x1B[31;1merror:\x1B[0m\x1B[34;1m --- TestError --- error-unit-test\x1B[0m\n\x1B[33;1m\x1B[0minitial error\x1B[0m; subsequent error message.\n");
         }
 
     }
@@ -60,7 +60,7 @@ namespace nix {
             logError(e.info());
             auto str = testing::internal::GetCapturedStderr();
 
-            ASSERT_STREQ(str.c_str(), "\x1B[31;1merror:\x1B[0m\x1B[34;1m --- SysError ------------------------------------- error-unit-test\x1B[0m\n\x1B[33;1m\x1B[0mstatting file\x1B[0m: \x1B[33;1mBad file descriptor\x1B[0m\n");
+            ASSERT_STREQ(str.c_str(), "\x1B[31;1merror:\x1B[0m\x1B[34;1m --- SysError --- error-unit-test\x1B[0m\n\x1B[33;1m\x1B[0mstatting file\x1B[0m: \x1B[33;1mBad file descriptor\x1B[0m\n");
 
         }
     }
@@ -74,7 +74,7 @@ namespace nix {
                 });
 
         auto str = testing::internal::GetCapturedStderr();
-        ASSERT_STREQ(str.c_str(), "\x1B[32;1minfo:\x1B[0m\x1B[34;1m --- Info name ------------------------------------- error-unit-test\x1B[0m\nInfo description\n");
+        ASSERT_STREQ(str.c_str(), "\x1B[32;1minfo:\x1B[0m\x1B[34;1m --- Info name --- error-unit-test\x1B[0m\nInfo description\n");
     }
 
     TEST(logEI, loggingErrorOnTalkativeLevel) {
@@ -88,7 +88,7 @@ namespace nix {
                         });
 
         auto str = testing::internal::GetCapturedStderr();
-        ASSERT_STREQ(str.c_str(), "\x1B[32;1mtalk:\x1B[0m\x1B[34;1m --- Talkative name -------------------------------- error-unit-test\x1B[0m\nTalkative description\n");
+        ASSERT_STREQ(str.c_str(), "\x1B[32;1mtalk:\x1B[0m\x1B[34;1m --- Talkative name --- error-unit-test\x1B[0m\nTalkative description\n");
     }
 
     TEST(logEI, loggingErrorOnChattyLevel) {
@@ -102,7 +102,7 @@ namespace nix {
                         });
 
         auto str = testing::internal::GetCapturedStderr();
-        ASSERT_STREQ(str.c_str(), "\x1B[32;1mchat:\x1B[0m\x1B[34;1m --- Chatty name ----------------------------------- error-unit-test\x1B[0m\nTalkative description\n");
+        ASSERT_STREQ(str.c_str(), "\x1B[32;1mchat:\x1B[0m\x1B[34;1m --- Chatty name --- error-unit-test\x1B[0m\nTalkative description\n");
     }
 
     TEST(logEI, loggingErrorOnDebugLevel) {
@@ -116,7 +116,7 @@ namespace nix {
                         });
 
         auto str = testing::internal::GetCapturedStderr();
-        ASSERT_STREQ(str.c_str(), "\x1B[33;1mdebug:\x1B[0m\x1B[34;1m --- Debug name ----------------------------------- error-unit-test\x1B[0m\nDebug description\n");
+        ASSERT_STREQ(str.c_str(), "\x1B[33;1mdebug:\x1B[0m\x1B[34;1m --- Debug name --- error-unit-test\x1B[0m\nDebug description\n");
     }
 
     TEST(logEI, loggingErrorOnVomitLevel) {
@@ -130,7 +130,7 @@ namespace nix {
                         });
 
         auto str = testing::internal::GetCapturedStderr();
-        ASSERT_STREQ(str.c_str(), "\x1B[32;1mvomit:\x1B[0m\x1B[34;1m --- Vomit name ----------------------------------- error-unit-test\x1B[0m\nVomit description\n");
+        ASSERT_STREQ(str.c_str(), "\x1B[32;1mvomit:\x1B[0m\x1B[34;1m --- Vomit name --- error-unit-test\x1B[0m\nVomit description\n");
     }
 
     /* ----------------------------------------------------------------------------
@@ -147,7 +147,7 @@ namespace nix {
                 });
 
         auto str = testing::internal::GetCapturedStderr();
-        ASSERT_STREQ(str.c_str(), "\x1B[31;1merror:\x1B[0m\x1B[34;1m --- name ----------------------------------------- error-unit-test\x1B[0m\nerror description\n");
+        ASSERT_STREQ(str.c_str(), "\x1B[31;1merror:\x1B[0m\x1B[34;1m --- name --- error-unit-test\x1B[0m\nerror description\n");
     }
 
     TEST(logError, logErrorWithPreviousAndNextLinesOfCode) {
@@ -171,7 +171,7 @@ namespace nix {
 
 
         auto str = testing::internal::GetCapturedStderr();
-        ASSERT_STREQ(str.c_str(), "\x1B[31;1merror:\x1B[0m\x1B[34;1m --- error name ----------------------------------- error-unit-test\x1B[0m\nin file: \x1B[34;1mmyfile.nix (40:13)\x1B[0m\n\nerror with code lines\n\n    39| previous line of code\n    40| this is the problem line of code\n      |             \x1B[31;1m^\x1B[0m\n    41| next line of code\n\nthis hint has \x1B[33;1myellow\x1B[0m templated \x1B[33;1mvalues\x1B[0m!!\n");
+        ASSERT_STREQ(str.c_str(), "\x1B[31;1merror:\x1B[0m\x1B[34;1m --- error name --- error-unit-test\x1B[0m\nin file: \x1B[34;1mmyfile.nix (40:13)\x1B[0m\n\nerror with code lines\n\n    39| previous line of code\n    40| this is the problem line of code\n      |             \x1B[31;1m^\x1B[0m\n    41| next line of code\n\nthis hint has \x1B[33;1myellow\x1B[0m templated \x1B[33;1mvalues\x1B[0m!!\n");
     }
 
     TEST(logError, logErrorWithoutLinesOfCode) {
@@ -190,7 +190,7 @@ namespace nix {
                 }});
 
         auto str = testing::internal::GetCapturedStderr();
-        ASSERT_STREQ(str.c_str(), "\x1B[31;1merror:\x1B[0m\x1B[34;1m --- error name ----------------------------------- error-unit-test\x1B[0m\nin file: \x1B[34;1mmyfile.nix (40:13)\x1B[0m\n\nerror without any code lines.\n\nthis hint has \x1B[33;1myellow\x1B[0m templated \x1B[33;1mvalues\x1B[0m!!\n");
+        ASSERT_STREQ(str.c_str(), "\x1B[31;1merror:\x1B[0m\x1B[34;1m --- error name --- error-unit-test\x1B[0m\nin file: \x1B[34;1mmyfile.nix (40:13)\x1B[0m\n\nerror without any code lines.\n\nthis hint has \x1B[33;1myellow\x1B[0m templated \x1B[33;1mvalues\x1B[0m!!\n");
     }
 
     TEST(logError, logErrorWithOnlyHintAndName) {
@@ -206,7 +206,7 @@ namespace nix {
                 }});
 
         auto str = testing::internal::GetCapturedStderr();
-        ASSERT_STREQ(str.c_str(), "\x1B[31;1merror:\x1B[0m\x1B[34;1m --- error name ----------------------------------- error-unit-test\x1B[0m\nin file: \x1B[34;1mmyfile.nix (40:13)\x1B[0m\n\nhint \x1B[33;1monly\x1B[0m\n");
+        ASSERT_STREQ(str.c_str(), "\x1B[31;1merror:\x1B[0m\x1B[34;1m --- error name --- error-unit-test\x1B[0m\nin file: \x1B[34;1mmyfile.nix (40:13)\x1B[0m\n\nhint \x1B[33;1monly\x1B[0m\n");
 
     }
 
@@ -224,7 +224,7 @@ namespace nix {
         });
 
         auto str = testing::internal::GetCapturedStderr();
-        ASSERT_STREQ(str.c_str(), "\x1B[33;1mwarning:\x1B[0m\x1B[34;1m --- name --------------------------------------- error-unit-test\x1B[0m\nerror description\n\nthere was a \x1B[33;1mwarning\x1B[0m\n");
+        ASSERT_STREQ(str.c_str(), "\x1B[33;1mwarning:\x1B[0m\x1B[34;1m --- name --- error-unit-test\x1B[0m\nerror description\n\nthere was a \x1B[33;1mwarning\x1B[0m\n");
     }
 
     TEST(logWarning, logWarningWithFileLineNumAndCode) {
@@ -249,7 +249,7 @@ namespace nix {
 
 
         auto str = testing::internal::GetCapturedStderr();
-        ASSERT_STREQ(str.c_str(), "\x1B[33;1mwarning:\x1B[0m\x1B[34;1m --- warning name ------------------------------- error-unit-test\x1B[0m\nin file: \x1B[34;1mmyfile.nix (40:13)\x1B[0m\n\nwarning description\n\n    40| this is the problem line of code\n      |             \x1B[31;1m^\x1B[0m\n\nthis hint has \x1B[33;1myellow\x1B[0m templated \x1B[33;1mvalues\x1B[0m!!\n");
+        ASSERT_STREQ(str.c_str(), "\x1B[33;1mwarning:\x1B[0m\x1B[34;1m --- warning name --- error-unit-test\x1B[0m\nin file: \x1B[34;1mmyfile.nix (40:13)\x1B[0m\n\nwarning description\n\n    40| this is the problem line of code\n      |             \x1B[31;1m^\x1B[0m\n\nthis hint has \x1B[33;1myellow\x1B[0m templated \x1B[33;1mvalues\x1B[0m!!\n");
     }
 
 }

src/libutil/tests/pool.cc

@@ -0,0 +1,127 @@
+#include "pool.hh"
+#include <gtest/gtest.h>
+
+namespace nix {
+
+    struct TestResource
+    {
+
+        TestResource() {
+            static int counter = 0;
+            num = counter++;
+        }
+
+        int dummyValue = 1;
+        bool good = true;
+        int num;
+    };
+
+    /* ----------------------------------------------------------------------------
+     * Pool
+     * --------------------------------------------------------------------------*/
+
+    TEST(Pool, freshPoolHasZeroCountAndSpecifiedCapacity) {
+        auto isGood = [](const ref<TestResource> & r) { return r->good; };
+        auto createResource = []() { return make_ref<TestResource>(); };
+
+        Pool<TestResource> pool = Pool<TestResource>((size_t)1, createResource, isGood);
+
+        ASSERT_EQ(pool.count(), 0);
+        ASSERT_EQ(pool.capacity(), 1);
+    }
+
+    TEST(Pool, freshPoolCanGetAResource) {
+        auto isGood = [](const ref<TestResource> & r) { return r->good; };
+        auto createResource = []() { return make_ref<TestResource>(); };
+
+        Pool<TestResource> pool = Pool<TestResource>((size_t)1, createResource, isGood);
+        ASSERT_EQ(pool.count(), 0);
+
+        TestResource r = *(pool.get());
+
+        ASSERT_EQ(pool.count(), 1);
+        ASSERT_EQ(pool.capacity(), 1);
+        ASSERT_EQ(r.dummyValue, 1);
+        ASSERT_EQ(r.good, true);
+    }
+
+    TEST(Pool, capacityCanBeIncremented) {
+        auto isGood = [](const ref<TestResource> & r) { return r->good; };
+        auto createResource = []() { return make_ref<TestResource>(); };
+
+        Pool<TestResource> pool = Pool<TestResource>((size_t)1, createResource, isGood);
+        ASSERT_EQ(pool.capacity(), 1);
+        pool.incCapacity();
+        ASSERT_EQ(pool.capacity(), 2);
+    }
+
+    TEST(Pool, capacityCanBeDecremented) {
+        auto isGood = [](const ref<TestResource> & r) { return r->good; };
+        auto createResource = []() { return make_ref<TestResource>(); };
+
+        Pool<TestResource> pool = Pool<TestResource>((size_t)1, createResource, isGood);
+        ASSERT_EQ(pool.capacity(), 1);
+        pool.decCapacity();
+        ASSERT_EQ(pool.capacity(), 0);
+    }
+
+    TEST(Pool, flushBadDropsOutOfScopeResources) {
+        auto isGood = [](const ref<TestResource> & r) { return false; };
+        auto createResource = []() { return make_ref<TestResource>(); };
+
+        Pool<TestResource> pool = Pool<TestResource>((size_t)1, createResource, isGood);
+
+        {
+            auto _r = pool.get();
+            ASSERT_EQ(pool.count(), 1);
+        }
+
+        pool.flushBad();
+        ASSERT_EQ(pool.count(), 0);
+    }
+
+    // Test that the resources we allocate are being reused when they are still good.
+    TEST(Pool, reuseResource) {
+        auto isGood = [](const ref<TestResource> & r) { return true; };
+        auto createResource = []() { return make_ref<TestResource>(); };
+
+        Pool<TestResource> pool = Pool<TestResource>((size_t)1, createResource, isGood);
+
+        // Compare the instance counter between the two handles. We expect them to be equal
+        // as the pool should hand out the same (still) good one again.
+        int counter = -1;
+        {
+            Pool<TestResource>::Handle h = pool.get();
+            counter = h->num;
+        } // the first handle goes out of scope
+
+        { // the second handle should contain the same resource (with the same counter value)
+            Pool<TestResource>::Handle h = pool.get();
+            ASSERT_EQ(h->num, counter);
+        }
+    }
+
+    // Test that the resources we allocate are being thrown away when they are no longer good.
+    TEST(Pool, badResourceIsNotReused) {
+        auto isGood = [](const ref<TestResource> & r) { return false; };
+        auto createResource = []() { return make_ref<TestResource>(); };
+
+        Pool<TestResource> pool = Pool<TestResource>((size_t)1, createResource, isGood);
+
+        // Compare the instance counter between the two handles. We expect them
+        // to *not* be equal as the pool should hand out a new instance after
+        // the first one was returned.
+        int counter = -1;
+        {
+            Pool<TestResource>::Handle h = pool.get();
+            counter = h->num;
+        } // the first handle goes out of scope
+
+        {
+          // the second handle should contain a different resource (with a
+          //different counter value)
+            Pool<TestResource>::Handle h = pool.get();
+            ASSERT_NE(h->num, counter);
+        }
+    }
+}

src/libutil/types.hh

@@ -1,6 +1,5 @@
 #pragma once
 
-
 #include "ref.hh"
 
 #include <list>
@@ -25,7 +24,6 @@ typedef string Path;
 typedef list<Path> Paths;
 typedef set<Path> PathSet;
 
-
 /* Helper class to run code at startup. */
 template<typename T>
 struct OnStartup
@@ -33,5 +31,4 @@ struct OnStartup
     OnStartup(T && t) { t(); }
 };
 
-
 }

src/libutil/util.cc

@@ -35,7 +35,7 @@
 #endif
 
 
-extern char * * environ;
+extern char * * environ __attribute__((weak));
 
 
 namespace nix {
@@ -972,7 +972,7 @@ pid_t startProcess(std::function<void()> fun, const ProcessOptions & options)
 {
     auto wrapper = [&]() {
         if (!options.allowVfork)
-            logger = makeDefaultLogger();
+            logger = makeSimpleLogger();
         try {
 #if __linux__
             if (options.dieWithParent && prctl(PR_SET_PDEATHSIG, SIGKILL) == -1)
@@ -1199,7 +1199,7 @@ void _interrupted()
     /* Block user interrupts while an exception is being handled.
        Throwing an exception while another exception is being handled
        kills the program! */
-    if (!interruptThrown && !std::uncaught_exception()) {
+    if (!interruptThrown && !std::uncaught_exceptions()) {
         interruptThrown = true;
         throw Interrupted("interrupted by the user");
     }
@@ -1297,7 +1297,7 @@ bool statusOk(int status)
 }
 
 
-bool hasPrefix(const string & s, const string & prefix)
+bool hasPrefix(std::string_view s, std::string_view prefix)
 {
     return s.compare(0, prefix.size(), prefix) == 0;
 }
@@ -1391,7 +1391,7 @@ std::string filterANSIEscapes(const std::string & s, bool filterAll, unsigned in
 static char base64Chars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 
 
-string base64Encode(const string & s)
+string base64Encode(std::string_view s)
 {
     string res;
     int data = 0, nbits = 0;
@@ -1412,7 +1412,7 @@ string base64Encode(const string & s)
 }
 
 
-string base64Decode(const string & s)
+string base64Decode(std::string_view s)
 {
     bool init = false;
     char decode[256];

src/libutil/util.hh

@@ -417,7 +417,7 @@ template<class N> bool string2Float(const string & s, N & n)
 
 
 /* Return true iff `s' starts with `prefix'. */
-bool hasPrefix(const string & s, const string & prefix);
+bool hasPrefix(std::string_view s, std::string_view prefix);
 
 
 /* Return true iff `s' ends in `suffix'. */
@@ -456,12 +456,11 @@ std::string filterANSIEscapes(const std::string & s,
 
 
 /* Base64 encoding/decoding. */
-string base64Encode(const string & s);
+string base64Encode(std::string_view s);
-string base64Decode(const string & s);
+string base64Decode(std::string_view s);
 
 
-/* Get a value for the specified key from an associate container, or a
+/* Get a value for the specified key from an associate container. */
-   default value if the key doesn't exist. */
 template <class T>
 std::optional<typename T::mapped_type> get(const T & map, const typename T::key_type & key)
 {

src/nix-build/nix-build.cc

@@ -21,7 +21,7 @@
 using namespace nix;
 using namespace std::string_literals;
 
-extern char * * environ;
+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
@@ -363,13 +363,12 @@ static void _main(int argc, char * * argv)
                 if (!drv)
                     throw Error("the 'bashInteractive' attribute in <nixpkgs> did not evaluate to a derivation");
 
-                pathsToBuild.emplace_back(store->parseStorePath(drv->queryDrvPath()));
+                pathsToBuild.push_back({store->parseStorePath(drv->queryDrvPath())});
 
                 shell = drv->queryOutPath() + "/bin/bash";
 
             } catch (Error & e) {
-                logWarning(
+                logWarning({
-                    ErrorInfo {
                     .name = "bashInteractive",
                     .hint = hintfmt("%s; will use bash from your environment",
                         (e.info().hint ? e.info().hint->str() : ""))
@@ -382,9 +381,9 @@ static void _main(int argc, char * * argv)
         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)); }))
-                pathsToBuild.emplace_back(input.first, input.second);
+                pathsToBuild.push_back({input.first, input.second});
         for (const auto & src : drv.inputSrcs)
-            pathsToBuild.emplace_back(src);
+            pathsToBuild.push_back({src});
 
         buildPaths(pathsToBuild);
 
@@ -477,6 +476,8 @@ static void _main(int argc, char * * argv)
 
         restoreSignals();
 
+        logger->stop();
+
         execvp(shell->c_str(), argPtrs.data());
 
         throw SysError("executing shell '%s'", *shell);
@@ -498,7 +499,7 @@ static void _main(int argc, char * * argv)
             if (outputName == "")
                 throw Error("derivation '%s' lacks an 'outputName' attribute", drvPath);
 
-            pathsToBuild.emplace_back(store->parseStorePath(drvPath), StringSet{outputName});
+            pathsToBuild.push_back({store->parseStorePath(drvPath), {outputName}});
 
             std::string drvPrefix;
             auto i = drvPrefixes.find(drvPath);
@@ -526,6 +527,8 @@ static void _main(int argc, char * * argv)
             if (auto store2 = store.dynamic_pointer_cast<LocalFSStore>())
                 store2->addPermRoot(store->parseStorePath(symlink.second), absPath(symlink.first), true);
 
+        logger->stop();
+
         for (auto & path : outPaths)
             std::cout << path << '\n';
     }