Merge changes I0fc80718,Ia182b86f,I355f82cb,I8a9b58fa,Id89f8a1f, ... into main

* changes:
  tree-wide: fix various lint warnings
  flake & doxygen: update tagline
  nix flake metadata: print modified dates for input flakes
  cli: eat terminal codes from stdout also
  Implement forcing CLI colour on, and document it better
  manual: fix a syntax error in redirects.js that made it not do anything
  misc docs/meson tidying
  build: implement clang-tidy using our plugin

clang-tidy/meson.build

@@ -1,13 +0,0 @@
-project('lix-clang-tidy', ['cpp', 'c'],
-  version : '0.1',
-  default_options : ['warning_level=3', 'cpp_std=c++20'])
-
-llvm = dependency('Clang', version: '>= 14', modules: ['libclang'])
-sources = files(
-  'HasPrefixSuffix.cc',
-  'LixClangTidyChecks.cc',
-  'FixIncludes.cc',
-)
-
-shared_module('lix-clang-tidy', sources,
-  dependencies: llvm)

doc/internal-api/doxygen.cfg.in

@@ -20,7 +20,7 @@ OUTPUT_DIRECTORY       = @docdir@
 # for a project that appears at the top of each page and should give viewer a
 # quick idea about the purpose of the project. Keep the description short.
 
-PROJECT_BRIEF          = "Nix, the purely functional package manager; unstable internal interfaces"
+PROJECT_BRIEF          = "Lix: A modern, delicious implementation of the Nix package manager; unstable internal interfaces"
 
 # If the GENERATE_LATEX tag is set to YES, doxygen will generate LaTeX output.
 # The default value is: YES.

doc/manual/redirects.js

@@ -345,7 +345,7 @@ const redirects = {
     "linux": "uninstall.html#linux",
     "macos": "uninstall.html#macos",
     "uninstalling": "uninstall.html",
-  }
+  },
   "contributing/hacking.html": {
     "nix-with-flakes": "#building-nix-with-flakes",
     "classic-nix": "#building-nix",

doc/manual/rl-next/clang-tidy-sorta.md

@@ -0,0 +1,10 @@
+---
+synopsis: "clang-tidy support"
+cls: 1697
+issues: fj#147
+credits: jade
+category: Development
+---
+
+`clang-tidy` can be used to lint Lix with a limited set of lints using `ninja -C build clang-tidy` and `ninja -C build clang-tidy-fix`.
+In practice, this fixes the built-in meson rule that was used the same as above being broken ever since precompiled headers were introduced.

doc/manual/rl-next/clicolor-clarity.md

@@ -0,0 +1,26 @@
+---
+synopsis: "Better usage of colour control environment variables"
+cls: [1699, 1702]
+credits: [jade]
+category: Improvements
+---
+
+Lix now heeds `NO_COLOR`/`NOCOLOR` for more output types, such as that used in `nix search`, `nix flake metadata` and similar.
+
+It also now supports `CLICOLOR_FORCE`/`FORCE_COLOR` to force colours regardless of whether there is a terminal on the other side.
+
+It now follows rules compatible with those described on <https://bixense.com/clicolors/> with `CLICOLOR` defaulted to enabled.
+
+That is to say, the following procedure is followed in order:
+- NO_COLOR or NOCOLOR set
+
+  Always disable colour
+- CLICOLOR_FORCE or FORCE_COLOR set
+
+  Enable colour
+- The output is a tty; TERM != "dumb"
+
+  Enable colour
+- Otherwise
+
+  Disable colour

doc/manual/rl-next/flake-metadata-time.md

@@ -0,0 +1,28 @@
+---
+synopsis: "`nix flake metadata` prints modified date"
+cls: 1700
+credits: jade
+category: Improvements
+---
+
+Ever wonder "gee, when *did* I update nixpkgs"?
+Wonder no more, because `nix flake metadata` now simply tells you the times every locked flake input was updated:
+
+```
+<...>
+Description:   The purely functional package manager
+Path:          /nix/store/c91yi8sxakc2ry7y4ac1smzwka4l5p78-source
+Revision:      c52cff582043838bbe29768e7da232483d52b61d-dirty
+Last modified: 2024-07-31 22:15:54
+Inputs:
+├───flake-compat: github:edolstra/flake-compat/0f9255e01c2351cc7d116c072cb317785dd33b33
+│   Last modified: 2023-10-04 06:37:54
+├───nix2container: github:nlewo/nix2container/3853e5caf9ad24103b13aa6e0e8bcebb47649fe4
+│   Last modified: 2024-07-10 13:15:56
+├───nixpkgs: github:NixOS/nixpkgs/e21630230c77140bc6478a21cd71e8bb73706fce
+│   Last modified: 2024-07-25 11:26:27
+├───nixpkgs-regression: github:NixOS/nixpkgs/215d4d0fd80ca5163643b03a33fde804a29cc1e2
+│   Last modified: 2022-01-24 11:20:45
+└───pre-commit-hooks: github:cachix/git-hooks.nix/f451c19376071a90d8c58ab1a953c6e9840527fd
+    Last modified: 2024-07-15 04:21:09
+```

doc/manual/src/contributing/testing.md

@@ -427,6 +427,7 @@ I grepped `src/` for `get[eE]nv\("` to find the mentions in Lix code.
 - `NIX_SHOW_STATS_PATH` - Writes those statistics into a file at the given path instead of stdout. Undocumented.
 - `NIX_SHOW_SYMBOLS` - Dumps the symbol table into the show-stats json output.
 - `TERM` - If `dumb` or unset, disables ANSI colour output.
+- `FORCE_COLOR`, `CLICOLOR_FORCE` - Enables ANSI colour output if `NO_COLOR`/`NOCOLOR` not set.
 - `NO_COLOR`, `NOCOLOR` - Disables ANSI colour output.
 - `_NIX_DEVELOPER_SHOW_UNKNOWN_LOCATIONS` - Highlights unknown locations in errors.
 - `NIX_PROFILE` - Selects which profile `nix-env` will operate on. Documented elsewhere.

doc/manual/src/language/advanced-attributes.md

@@ -326,7 +326,6 @@ Derivations can declare some infrequently used optional attributes.
     ```
 
   - [`unsafeDiscardReferences`]{#adv-attr-unsafeDiscardReferences}\
-
     When using [structured attributes](#adv-attr-structuredAttrs), the
     attribute `unsafeDiscardReferences` is an attribute set with a boolean value for each output name.
     If set to `true`, it disables scanning the output for runtime dependencies.

flake.nix

@@ -1,5 +1,5 @@
 {
-  description = "The purely functional package manager";
+  description = "Lix: A modern, delicious implementation of the Nix package manager";
 
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05-small";
@@ -197,6 +197,8 @@
             busybox-sandbox-shell = final.busybox-sandbox-shell or final.default-busybox-sandbox-shell;
           };
 
+          lix-clang-tidy = final.callPackage ./subprojects/lix-clang-tidy { };
+
           # Export the patched version of boehmgc that Lix uses into the overlay
           # for consumers of this flake.
           boehmgc-nix = final.nix.passthru.boehmgc-nix;
@@ -290,6 +292,24 @@
             werror = true;
           };
 
+          # Although this might be nicer to do with pre-commit, that would
+          # require adding 12MB of nodejs to the dev shell, whereas building it
+          # in CI with Nix avoids that at a cost of slower feedback on rarely
+          # touched files.
+          jsSyntaxCheck =
+            let
+              nixpkgs = nixpkgsFor.x86_64-linux.native;
+              inherit (nixpkgs) pkgs;
+              docSources = lib.fileset.toSource {
+                root = ./doc;
+                fileset = lib.fileset.fileFilter (f: f.hasExt "js") ./doc;
+              };
+            in
+            pkgs.runCommand "js-syntax-check" { } ''
+              find ${docSources} -type f -print -exec ${pkgs.nodejs-slim}/bin/node --check '{}' ';'
+              touch $out
+            '';
+
           # Make sure that nix-env still produces the exact same result
           # on a particular version of Nixpkgs.
           evalNixpkgs =
@@ -384,6 +404,8 @@
         rec {
           inherit (nixpkgsFor.${system}.native) nix;
           default = nix;
+
+          inherit (nixpkgsFor.${system}.native) lix-clang-tidy;
         }
         // (
           lib.optionalAttrs (builtins.elem system linux64BitSystems) {

justfile

@@ -25,3 +25,13 @@ install *OPTIONS: (build OPTIONS)
 # Run tests
 test *OPTIONS:
     meson test -C build --print-errorlogs {{ OPTIONS }}
+
+alias clang-tidy := lint
+
+lint:
+    ninja -C build clang-tidy
+
+alias clang-tidy-fix := lint-fix
+
+lint-fix:
+    ninja -C build clang-tidy-fix

meson.build

@@ -548,3 +548,5 @@ if enable_tests
   subdir('tests/unit')
   subdir('tests/functional')
 endif
+
+subdir('meson/clang-tidy')

meson.options

@@ -1,7 +1,7 @@
 # vim: filetype=meson
 
 option('enable-build', type : 'boolean', value : true,
-  description : 'Set to false to not actually build. Only really makes sense with -Dinternal-api-docs=true',
+  description : 'set to false to not actually build. Only really makes sense with -Dinternal-api-docs=true',
 )
 
 option('gc', type : 'feature',
@@ -37,7 +37,7 @@ option('tests-brief', type : 'boolean', value : false,
 )
 
 option('profile-build', type : 'feature', value: 'disabled',
-  description : 'whether to enable -ftime-trace in clang builds, allowing for speeding up the build.'
+  description : 'whether to enable -ftime-trace in clang builds, allowing for diagnosing the cause of build time.'
 )
 
 option('store-dir', type : 'string', value : '/nix/store',
@@ -68,3 +68,7 @@ option('profile-dir', type : 'string', value : 'etc/profile.d',
 option('enable-pch-std', type : 'boolean', value : true,
   description : 'whether to use precompiled headers for C++\'s standard library (breaks clangd if you\'re using GCC)',
 )
+
+option('lix-clang-tidy-checks-path', type : 'string', value : '',
+  description: 'path to lix-clang-tidy-checks library file, if providing it externally. Uses an internal one if this is not set',
+)

meson/clang-tidy/build_required_targets.py

@@ -0,0 +1,21 @@
+#!/usr/bin/env python3
+import subprocess
+
+def get_targets_of_rule(build_root: str, rule_name: str) -> list[str]:
+    return subprocess.check_output(['ninja', '-C', build_root, '-t', 'targets', 'rule', rule_name]).decode().strip().splitlines()
+
+def ninja_build(build_root: str, targets: list[str]):
+    subprocess.check_call(['ninja', '-C', build_root, '--', *targets])
+
+def main():
+    import argparse
+    ap = argparse.ArgumentParser(description='Builds required targets for clang-tidy')
+    ap.add_argument('build_root', help='Ninja build root', type=str)
+
+    args = ap.parse_args()
+
+    targets = [t for t in get_targets_of_rule(args.build_root, 'CUSTOM_COMMAND') if t.endswith('gen.hh')]
+    ninja_build(args.build_root, targets)
+
+if __name__ == '__main__':
+    main()

meson/clang-tidy/clean_compdb.py

@@ -0,0 +1,53 @@
+#!/usr/bin/env python3
+# Deletes the PCH arguments from a compilation database, to workaround nixpkgs
+# stdenv having a cc-wrapper that is impossible to use for anything except cc
+# itself, for example, clang-tidy.
+
+import json
+import shlex
+
+
+def process_compdb(compdb: list[dict]) -> list[dict]:
+
+    def munch_command(args: list[str]) -> list[str]:
+        out = []
+        eat_next = False
+        for i, arg in enumerate(args):
+            if arg == '-fpch-preprocess':
+                # as used with gcc
+                continue
+            elif arg == '-include-pch' or (arg == '-include' and args[i + 1] == 'precompiled-headers.hh'):
+                # -include-pch some-pch (clang), or -include some-pch (gcc)
+                eat_next = True
+                continue
+            if not eat_next:
+                out.append(arg)
+            eat_next = False
+        return out
+
+    def chomp(item: dict) -> dict:
+        item = item.copy()
+        item['command'] = shlex.join(munch_command(shlex.split(item['command'])))
+        return item
+
+    return [chomp(x) for x in compdb if not x['file'].endswith('precompiled-headers.hh')]
+
+
+def main():
+    import argparse
+    ap = argparse.ArgumentParser(
+        description='Delete pch arguments from compilation database')
+    ap.add_argument('input',
+                    type=argparse.FileType('r'),
+                    help='Input json file')
+    ap.add_argument('output',
+                    type=argparse.FileType('w'),
+                    help='Output json file')
+    args = ap.parse_args()
+
+    input_json = json.load(args.input)
+    json.dump(process_compdb(input_json), args.output, indent=2)
+
+
+if __name__ == '__main__':
+    main()

meson/clang-tidy/meson.build

@@ -0,0 +1,98 @@
+# The clang-tidy target for Lix
+
+run_clang_tidy = find_program('run-clang-tidy', required : false)
+# Although this looks like it wants to be pkg-config, pkg-config does not
+# really work for *plugins*, which are executable-like .so files that also
+# cannot be found via find_program. Fun!
+if get_option('lix-clang-tidy-checks-path') != ''
+  lix_clang_tidy_so = get_option('lix-clang-tidy-checks-path')
+  lix_clang_tidy_so_found = true
+else
+  lix_clang_tidy_subproj = subproject(
+    'lix-clang-tidy',
+    required : false,
+    default_options : {'build-by-default': false}
+  )
+  if lix_clang_tidy_subproj.found()
+    lix_clang_tidy_so = lix_clang_tidy_subproj.get_variable('lix_clang_tidy')
+    lix_clang_tidy_so_found = true
+  else
+    lix_clang_tidy_so_found = false
+  endif
+endif
+
+# Due to numerous problems, such as:
+# - Meson does not expose pch targets, but *fine*, I can just ask Ninja for
+#   them with `ninja -t targets rule cpp_PCH` and build them manually:
+#   https://github.com/mesonbuild/meson/issues/13499
+# - Nixpkgs stdenv buries the cc-wrapper under a giant pile of assumptions
+#   about the cc-wrapper actually being used on the cc of a stdenv, rather than
+#   independently for clang-tidy, and we need to use cc-wrapper to get the
+#   correct hardening flags so that clang-tidy can actually parse the PCH file
+#
+# I give up. I am going to delete the damn PCH args and then it will work.
+meson.add_postconf_script(
+  python,
+  meson.current_source_dir() / 'clean_compdb.py',
+  meson.global_build_root() / 'compile_commands.json',
+  meson.current_build_dir() / 'compile_commands.json',
+)
+
+# Horrible hack to get around not being able to depend on another target's
+# generated headers in any way in the meson DSL
+# https://github.com/mesonbuild/meson/issues/12817 which was incorrectly
+# closed, if you *actually* need to generate the files once.
+# Also related: https://github.com/mesonbuild/meson/issues/3667
+#
+# Or we could ban meson generators because their design is broken.
+build_all_generated_headers = custom_target(
+  command : [
+    python,
+    meson.current_source_dir() / 'build_required_targets.py',
+    meson.global_build_root(),
+  ],
+  output : 'generated_headers.stamp',
+  build_by_default : false,
+  build_always_stale : true,
+)
+
+if lix_clang_tidy_so_found
+  run_clang_tidy_args = [
+    '-load',
+    lix_clang_tidy_so,
+    '-p',
+    # We have to workaround a run-clang-tidy bug too, so we must give the
+    # directory name rather than the actual compdb file.
+    # https://github.com/llvm/llvm-project/issues/101440
+    meson.current_build_dir(),
+    '-quiet',
+  ]
+  run_target(
+    'clang-tidy',
+    command : [
+      # XXX: This explicitly invokes it with python because of a nixpkgs bug
+      # where clang-unwrapped does not patch interpreters in run-clang-tidy.
+      # However, making clang-unwrapped depend on python is also silly, so idk.
+      python,
+      run_clang_tidy,
+      run_clang_tidy_args,
+      '-warnings-as-errors',
+      '*',
+    ],
+    depends : [
+      build_all_generated_headers,
+    ],
+  )
+  run_target(
+    'clang-tidy-fix',
+    command : [
+      python,
+      run_clang_tidy,
+      run_clang_tidy_args,
+      '-fix',
+    ],
+    depends : [
+      build_all_generated_headers,
+    ],
+  )
+endif

src/libexpr/flake/config.cc

@@ -53,7 +53,7 @@ void ConfigFile::apply()
 
         bool trusted = whitelist.count(baseName);
         if (!trusted) {
-            switch (nix::fetchSettings.acceptFlakeConfig) {
+            switch (nix::fetchSettings.acceptFlakeConfig.get()) {
             case AcceptFlakeConfig::True: {
                 trusted = true;
                 break;

src/libexpr/parser/parser.cc

@@ -12,7 +12,6 @@
 #include "state.hh"
 
 #include <charconv>
-#include <clocale>
 #include <memory>
 
 // flip this define when doing parser development to enable some g checks.
@@ -254,7 +253,8 @@ struct AttrState : SubexprState {
 
     std::vector<AttrName> attrs;
 
-    void pushAttr(auto && attr, PosIdx) { attrs.emplace_back(std::move(attr)); }
+    template <typename T>
+    void pushAttr(T && attr, PosIdx) { attrs.emplace_back(std::forward<T>(attr)); }
 };
 
 template<> struct BuildAST<grammar::attr::simple> {
@@ -290,7 +290,8 @@ struct InheritState : SubexprState {
     std::unique_ptr<Expr> from;
     PosIdx fromPos;
 
-    void pushAttr(auto && attr, PosIdx pos) { attrs.emplace_back(std::move(attr), pos); }
+    template <typename T>
+    void pushAttr(T && attr, PosIdx pos) { attrs.emplace_back(std::forward<T>(attr), pos); }
 };
 
 template<> struct BuildAST<grammar::inherit::from> {

src/libstore/filetransfer.cc

@@ -477,8 +477,17 @@ struct curlFileTransfer : public FileTransfer
 
     ~curlFileTransfer()
     {
-        stopWorkerThread();
-
+        try {
+            stopWorkerThread();
+        } catch (nix::Error e) {
+            // This can only fail if a socket to our own process cannot be
+            // written to, so it is always a bug in the program if it fails.
+            //
+            // Joining the thread would probably only cause a deadlock if this
+            // happened, so just die on purpose.
+            printError("failed to join curl file transfer worker thread: %1%", e.what());
+            std::terminate();
+        }
         workerThread.join();
 
         if (curlm) curl_multi_cleanup(curlm);

src/libstore/machines.cc

@@ -33,7 +33,7 @@ Machine::Machine(decltype(storeUri) storeUri,
     systemTypes(systemTypes),
     sshKey(sshKey),
     maxJobs(maxJobs),
-    speedFactor(speedFactor == 0.0f ? 1.0f : std::move(speedFactor)),
+    speedFactor(speedFactor == 0.0f ? 1.0f : speedFactor),
     supportedFeatures(supportedFeatures),
     mandatoryFeatures(mandatoryFeatures),
     sshPublicHostKey(sshPublicHostKey)

src/libutil/archive.cc

@@ -192,7 +192,7 @@ static Generator<Entry> parseObject(Source & source, const Path & path)
 #define EXPECT(raw, kind)                              \
     do {                                               \
         const auto s = readString(source);             \
-        if (s != raw) {                                \
+        if (s != (raw)) {                                \
             throw badArchive("expected " kind " tag"); \
         }                                              \
         co_yield MetadataString{s};                    \

src/libutil/file-descriptor.cc

@@ -131,7 +131,7 @@ AutoCloseFD::AutoCloseFD(AutoCloseFD && that) : fd{that.fd}
 }
 
 
-AutoCloseFD & AutoCloseFD::operator =(AutoCloseFD && that)
+AutoCloseFD & AutoCloseFD::operator =(AutoCloseFD && that) noexcept(false)
 {
     close();
     fd = that.fd;

src/libutil/hash.cc

@@ -229,7 +229,7 @@ Hash::Hash(std::string_view rest, HashType type, bool isSRI)
 
         for (unsigned int n = 0; n < rest.size(); ++n) {
             char c = rest[rest.size() - n - 1];
-            unsigned char digit;
+            size_t digit;
             for (digit = 0; digit < base32Chars.size(); ++digit) /* !!! slow */
                 if (base32Chars[digit] == c) break;
             if (digit >= 32)

src/libutil/logging.cc

@@ -37,7 +37,7 @@ void Logger::warn(const std::string & msg)
 
 void Logger::writeToStdout(std::string_view s)
 {
-    writeFull(STDOUT_FILENO, s);
+    writeFull(STDOUT_FILENO, filterANSIEscapes(s, !shouldANSI(), std::numeric_limits<unsigned int>::max(), false));
     writeFull(STDOUT_FILENO, "\n");
 }
 

src/libutil/shlex.cc

@@ -62,6 +62,8 @@ std::vector<std::string> shell_split(const std::string & input)
                 begin = ++iterator;
             }
             break;
+            // no other relevant cases; silence exhaustiveness compiler warning
+            default: break;
         }
     }
 

src/libutil/terminal.cc

@@ -9,12 +9,25 @@ namespace nix {
 
 bool shouldANSI()
 {
-    return isatty(STDERR_FILENO)
-        && getEnv("TERM").value_or("dumb") != "dumb"
-        && !(getEnv("NO_COLOR").has_value() || getEnv("NOCOLOR").has_value());
+    // Implements the behaviour described by https://bixense.com/clicolors/
+    // As well as https://force-color.org/ for compatibility, since it fits in the same shape.
+    // NO_COLOR CLICOLOR CLICOLOR_FORCE Colours?
+    // set      x        x              No
+    // unset    x        set            Yes
+    // unset    x        unset          If attached to a terminal
+    //                                  [we choose the "modern" approach of colour-by-default]
+    auto compute = []() -> bool {
+        bool mustNotColour = getEnv("NO_COLOR").has_value() || getEnv("NOCOLOR").has_value();
+        bool shouldForce = getEnv("CLICOLOR_FORCE").has_value() || getEnv("FORCE_COLOR").has_value();
+        bool isTerminal = isatty(STDERR_FILENO) && getEnv("TERM").value_or("dumb") != "dumb";
+        return !mustNotColour && (shouldForce || isTerminal);
+    };
+    static bool cached = compute();
+    return cached;
 }
 
-std::string filterANSIEscapes(std::string_view s, bool filterAll, unsigned int width)
+// FIXME(jade): replace with TerminalCodeEater. wowie this is evil code.
+std::string filterANSIEscapes(std::string_view s, bool filterAll, unsigned int width, bool eatTabs)
 {
     std::string t, e;
     size_t w = 0;
@@ -43,7 +56,7 @@ std::string filterANSIEscapes(std::string_view s, bool filterAll, unsigned int w
                 t += e;
         }
 
-        else if (*i == '\t') {
+        else if (*i == '\t' && eatTabs) {
             i++; t += ' '; w++;
             while (w < (size_t) width && w % 8) {
                 t += ' '; w++;

src/libutil/terminal.hh

@@ -9,6 +9,15 @@ namespace nix {
 /**
  * Determine whether ANSI escape sequences are appropriate for the
  * present output.
+ *
+ * This follows the rules described on https://bixense.com/clicolors/
+ * with CLICOLOR defaulted to enabled (and thus ignored).
+ *
+ * That is to say, the following procedure is followed in order:
+ * - NO_COLOR or NOCOLOR set             -> always disable colour
+ * - CLICOLOR_FORCE or FORCE_COLOR set   -> enable colour
+ * - The output is a tty; TERM != "dumb" -> enable colour
+ * - Otherwise                           -> disable colour
  */
 bool shouldANSI();
 
@@ -21,7 +30,8 @@ bool shouldANSI();
  */
 std::string filterANSIEscapes(std::string_view s,
     bool filterAll = false,
-    unsigned int width = std::numeric_limits<unsigned int>::max());
+    unsigned int width = std::numeric_limits<unsigned int>::max(),
+    bool eatTabs = true);
 
 /**
  * Recalculate the window size, updating a global variable. Used in the

src/libutil/url.cc

@@ -63,7 +63,7 @@ std::string percentDecode(std::string_view in)
             if (i + 2 >= in.size())
                 throw BadURL("invalid URI parameter '%s'", in);
             try {
-                decoded += std::stoul(std::string(in, i + 1, 2), 0, 16);
+                decoded += char8_t(std::stoul(std::string(in, i + 1, 2), 0, 16));
                 i += 3;
             } catch (...) {
                 throw BadURL("invalid URI parameter '%s'", in);

src/nix/flake.cc

@@ -209,6 +209,11 @@ struct CmdFlakeMetadata : FlakeCommand, MixJSON
     {
         auto lockedFlake = lockFlake();
         auto & flake = lockedFlake.flake;
+        auto formatTime = [](time_t time) -> std::string {
+            std::ostringstream os{};
+            os << std::put_time(std::localtime(&time), "%F %T");
+            return os.str();
+        };
 
         if (json) {
             nlohmann::json j;
@@ -260,7 +265,7 @@ struct CmdFlakeMetadata : FlakeCommand, MixJSON
             if (auto lastModified = flake.lockedRef.input.getLastModified())
                 logger->cout(
                     ANSI_BOLD "Last modified:" ANSI_NORMAL " %s",
-                    std::put_time(std::localtime(&*lastModified), "%F %T"));
+                    formatTime(*lastModified));
 
             if (!lockedFlake.lockFile.root->inputs.empty())
                 logger->cout(ANSI_BOLD "Inputs:" ANSI_NORMAL);
@@ -275,16 +280,25 @@ struct CmdFlakeMetadata : FlakeCommand, MixJSON
                     bool last = i + 1 == node.inputs.size();
 
                     if (auto lockedNode = std::get_if<0>(&input.second)) {
-                        logger->cout("%s" ANSI_BOLD "%s" ANSI_NORMAL ": %s",
-                            prefix + (last ? treeLast : treeConn), input.first,
+                        // ├───agenix: github:ryantm/agenix/8d37c5bdeade12b6479c85acd133063ab53187a0
+                        logger->cout("%s%s" ANSI_BOLD "%s" ANSI_NORMAL ": %s",
+                            prefix, last ? treeLast : treeConn, input.first,
                             (*lockedNode)->lockedRef);
 
+                        // ├───lix: https://git.lix.systems/api/v1/repos/lix-project <....>
+                        // │   Last modified: 2024-07-31 21:01:34
+                        if (auto lastModified = (*lockedNode)->lockedRef.input.getLastModified()) {
+                            logger->cout("%s%s" ANSI_BOLD "%s" ANSI_NORMAL ": %s",
+                                prefix, last ? treeNull : treeLine, "Last modified", formatTime(*lastModified));
+                        }
+
                         bool firstVisit = visited.insert(*lockedNode).second;
 
                         if (firstVisit) recurse(**lockedNode, prefix + (last ? treeNull : treeLine));
                     } else if (auto follows = std::get_if<1>(&input.second)) {
-                        logger->cout("%s" ANSI_BOLD "%s" ANSI_NORMAL " follows input '%s'",
-                            prefix + (last ? treeLast : treeConn), input.first,
+                        // │   ├───darwin follows input 'flake-utils'
+                        logger->cout("%s%s" ANSI_BOLD "%s" ANSI_NORMAL " follows input '%s'",
+                            prefix, last ? treeLast : treeConn, input.first,
                             printInputPath(*follows));
                     }
                 }

src/nix/meson.build

@@ -1,8 +1,8 @@
-generate_manpage_gen = gen_header.process(meson.project_source_root() / 'doc/manual/generate-manpage.nix')
-
-utils_gen = gen_header.process(meson.project_source_root() / 'doc/manual/utils.nix')
-
-get_env_gen = gen_header.process('get-env.sh')
+nix_generated_headers = [
+  gen_header.process(meson.project_source_root() / 'doc/manual/generate-manpage.nix'),
+  gen_header.process(meson.project_source_root() / 'doc/manual/utils.nix'),
+  gen_header.process('get-env.sh'),
+]
 
 # src/nix/profile.cc includes src/nix/profile.md, which includes "doc/files/profiles.md.gen.hh".
 # Unfortunately, https://github.com/mesonbuild/meson/issues/2320.
@@ -18,7 +18,7 @@ run_command(
   meson.current_build_dir() / 'doc/files/profiles.md',
   check : true,
 )
-profiles_md_gen = gen_header.process(
+nix_generated_headers += gen_header.process(
   meson.current_build_dir() / 'doc/files/profiles.md',
   preserve_path_from : meson.current_build_dir(),
 )
@@ -74,10 +74,7 @@ nix_sources = files(
 nix = executable(
   'nix',
   nix_sources,
-  generate_manpage_gen,
-  utils_gen,
-  get_env_gen,
-  profiles_md_gen,
+  nix_generated_headers,
   nix2_commands_sources,
   dependencies : [
     libasanoptions,

subprojects/lix-clang-tidy/default.nix

@@ -0,0 +1,44 @@
+{
+  lib,
+  stdenv,
+  cmake,
+  meson,
+  ninja,
+  llvmPackages,
+}:
+let
+  inherit (lib) fileset;
+in
+stdenv.mkDerivation {
+  pname = "lix-clang-tidy-checks";
+  # Setting the version to the Lix version is just going to cause pointless
+  # rebuilds due to versionSuffix and similar, and I cannot conceive of a usage
+  # where we actually care about its version since this is internal-only.
+  version = "0.1";
+
+  src = fileset.toSource {
+    root = ./.;
+    fileset = fileset.unions [
+      ./meson.build
+      ./meson.options
+      (fileset.fileFilter (
+        { hasExt, ... }:
+        builtins.any hasExt [
+          "cc"
+          "hh"
+        ]
+      ) ./.)
+    ];
+  };
+
+  nativeBuildInputs = [
+    meson
+    cmake
+    ninja
+  ];
+
+  buildInputs = [
+    llvmPackages.llvm
+    llvmPackages.clang-unwrapped.dev
+  ];
+}

subprojects/lix-clang-tidy/meson.build

@@ -0,0 +1,18 @@
+project('lix-clang-tidy', ['cpp', 'c'],
+  version : '0.1',
+  default_options : ['warning_level=3', 'cpp_std=c++20']
+)
+
+llvm = dependency('Clang', version: '>= 17', modules: ['libclang'])
+sources = files(
+  'HasPrefixSuffix.cc',
+  'LixClangTidyChecks.cc',
+  'FixIncludes.cc',
+)
+
+lix_clang_tidy = shared_module('lix-clang-tidy', sources,
+  dependencies: llvm,
+  # overrides build_by_default, see https://github.com/mesonbuild/meson/issues/13498
+  install : get_option('build-by-default'),
+  build_by_default : get_option('build-by-default')
+)

subprojects/lix-clang-tidy/meson.options

@@ -0,0 +1,3 @@
+option('build-by-default', type : 'boolean', value : true,
+  description : 'set to false to not actually build targets by default. This is a hack to deal with meson lacking a build_by_default default option and building subprojects by default'
+)

tests/functional/flakes/flake-metadata.sh

@@ -0,0 +1,36 @@
+source ./common.sh
+
+flakeDir=$TEST_ROOT/flake
+mkdir -p "$flakeDir"
+
+cat > "$flakeDir/flake.nix" <<-'EOF'
+{
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable-small";
+    flake-utils.url = "github:numtide/flake-utils";
+    flake-compat = {
+      url = "github:edolstra/flake-compat";
+      flake = false;
+    };
+    lanzaboote = {
+      url = "github:nix-community/lanzaboote";
+      inputs.nixpkgs.follows = "nixpkgs";
+      inputs.flake-utils.follows = "flake-utils";
+      inputs.flake-compat.follows = "flake-compat";
+    };
+  };
+
+  outputs = { ... }: {};
+}
+EOF
+
+cp flake-metadata/flake.lock "$flakeDir"
+touch -d @1000 "$flakeDir/flake.nix" "$flakeDir/flake.lock" "$flakeDir"
+
+# For some reason we use NIX_STORE_DIR which causes unstable paths. This is
+# goofy. We can just use --store, which sets rootDir and does not have this
+# problem.
+actualStore=$NIX_STORE_DIR
+unset NIX_STORE_DIR
+NOCOLOR=1 TZ=UTC LC_ALL=C.UTF-8 nix flake metadata --store "$actualStore" "$flakeDir" | grep -v -e 'Locked URL:' -e 'Resolved URL:' > "$TEST_ROOT/metadata.out.actual"
+diff -u flake-metadata/metadata.out.expected "$TEST_ROOT/metadata.out.actual"

tests/functional/flakes/flake-metadata/flake.lock

@@ -0,0 +1,245 @@
+{
+  "nodes": {
+    "crane": {
+      "inputs": {
+        "nixpkgs": [
+          "lanzaboote",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1711299236,
+        "narHash": "sha256-6/JsyozOMKN8LUGqWMopKTSiK8N79T8Q+hcxu2KkTXg=",
+        "owner": "ipetkov",
+        "repo": "crane",
+        "rev": "880573f80d09e18a11713f402b9e6172a085449f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "ipetkov",
+        "repo": "crane",
+        "type": "github"
+      }
+    },
+    "flake-compat": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1696426674,
+        "narHash": "sha256-kvjfFW7WAETZlt09AgDn1MrtKzP7t90Vf7vypd3OL1U=",
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "rev": "0f9255e01c2351cc7d116c072cb317785dd33b33",
+        "type": "github"
+      },
+      "original": {
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "type": "github"
+      }
+    },
+    "flake-parts": {
+      "inputs": {
+        "nixpkgs-lib": [
+          "lanzaboote",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1709336216,
+        "narHash": "sha256-Dt/wOWeW6Sqm11Yh+2+t0dfEWxoMxGBvv3JpIocFl9E=",
+        "owner": "hercules-ci",
+        "repo": "flake-parts",
+        "rev": "f7b3c975cf067e56e7cda6cb098ebe3fb4d74ca2",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "repo": "flake-parts",
+        "type": "github"
+      }
+    },
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1710146030,
+        "narHash": "sha256-SZ5L6eA7HJ/nmkzGG7/ISclqe6oZdOZTNoesiInkXPQ=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "b1d9ab70662946ef0850d488da1c9019f3a9752a",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "gitignore": {
+      "inputs": {
+        "nixpkgs": [
+          "lanzaboote",
+          "pre-commit-hooks-nix",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1709087332,
+        "narHash": "sha256-HG2cCnktfHsKV0s4XW83gU3F57gaTljL9KNSuG6bnQs=",
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "rev": "637db329424fd7e46cf4185293b9cc8c88c95394",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "type": "github"
+      }
+    },
+    "lanzaboote": {
+      "inputs": {
+        "crane": "crane",
+        "flake-compat": [
+          "flake-compat"
+        ],
+        "flake-parts": "flake-parts",
+        "flake-utils": [
+          "flake-utils"
+        ],
+        "nixpkgs": [
+          "nixpkgs"
+        ],
+        "pre-commit-hooks-nix": "pre-commit-hooks-nix",
+        "rust-overlay": "rust-overlay"
+      },
+      "locked": {
+        "lastModified": 1713369831,
+        "narHash": "sha256-G4OGxvlIIjphpkxcRAkf1QInYsAeqbfNh6Yl1JLy2uM=",
+        "owner": "nix-community",
+        "repo": "lanzaboote",
+        "rev": "850f27322239f8cfa56b122cc9a278ab99a49015",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "lanzaboote",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1719824438,
+        "narHash": "sha256-pY0wosAgcr9W4vmGML0T3BVhQiGuKoozCbs2t+Je1zc=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "7f993cdf26ccef564eabf31fdb40d140821e12bc",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable-small",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs-stable": {
+      "locked": {
+        "lastModified": 1710695816,
+        "narHash": "sha256-3Eh7fhEID17pv9ZxrPwCLfqXnYP006RKzSs0JptsN84=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "614b4613980a522ba49f0d194531beddbb7220d3",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-23.11",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "pre-commit-hooks-nix": {
+      "inputs": {
+        "flake-compat": [
+          "lanzaboote",
+          "flake-compat"
+        ],
+        "flake-utils": [
+          "lanzaboote",
+          "flake-utils"
+        ],
+        "gitignore": "gitignore",
+        "nixpkgs": [
+          "lanzaboote",
+          "nixpkgs"
+        ],
+        "nixpkgs-stable": "nixpkgs-stable"
+      },
+      "locked": {
+        "lastModified": 1710923068,
+        "narHash": "sha256-6hOpUiuxuwpXXc/xfJsBUJeqqgGI+JMJuLo45aG3cKc=",
+        "owner": "cachix",
+        "repo": "pre-commit-hooks.nix",
+        "rev": "e611897ddfdde3ed3eaac4758635d7177ff78673",
+        "type": "github"
+      },
+      "original": {
+        "owner": "cachix",
+        "repo": "pre-commit-hooks.nix",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-compat": "flake-compat",
+        "flake-utils": "flake-utils",
+        "lanzaboote": "lanzaboote",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "rust-overlay": {
+      "inputs": {
+        "flake-utils": [
+          "lanzaboote",
+          "flake-utils"
+        ],
+        "nixpkgs": [
+          "lanzaboote",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1711246447,
+        "narHash": "sha256-g9TOluObcOEKewFo2fR4cn51Y/jSKhRRo4QZckHLop0=",
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "rev": "dcc802a6ec4e9cc6a1c8c393327f0c42666f22e4",
+        "type": "github"
+      },
+      "original": {
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "type": "github"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

tests/functional/flakes/flake-metadata/metadata.out.expected

@@ -0,0 +1,36 @@
+Path:          /nix/store/gaxb42z68bcr8lch467shvmnhjjzgd8b-source
+Last modified: 1970-01-01 00:16:40
+Inputs:
+├───flake-compat: github:edolstra/flake-compat/0f9255e01c2351cc7d116c072cb317785dd33b33
+│   Last modified: 2023-10-04 13:37:54
+├───flake-utils: github:numtide/flake-utils/b1d9ab70662946ef0850d488da1c9019f3a9752a
+│   Last modified: 2024-03-11 08:33:50
+│   └───systems: github:nix-systems/default/da67096a3b9bf56a91d16901293e51ba5b49a27e
+│       Last modified: 2023-04-09 08:27:08
+├───lanzaboote: github:nix-community/lanzaboote/850f27322239f8cfa56b122cc9a278ab99a49015
+│   Last modified: 2024-04-17 16:03:51
+│   ├───crane: github:ipetkov/crane/880573f80d09e18a11713f402b9e6172a085449f
+│   │   Last modified: 2024-03-24 16:53:56
+│   │   └───nixpkgs follows input 'lanzaboote/nixpkgs'
+│   ├───flake-compat follows input 'flake-compat'
+│   ├───flake-parts: github:hercules-ci/flake-parts/f7b3c975cf067e56e7cda6cb098ebe3fb4d74ca2
+│   │   Last modified: 2024-03-01 23:36:56
+│   │   └───nixpkgs-lib follows input 'lanzaboote/nixpkgs'
+│   ├───flake-utils follows input 'flake-utils'
+│   ├───nixpkgs follows input 'nixpkgs'
+│   ├───pre-commit-hooks-nix: github:cachix/pre-commit-hooks.nix/e611897ddfdde3ed3eaac4758635d7177ff78673
+│   │   Last modified: 2024-03-20 08:24:28
+│   │   ├───flake-compat follows input 'lanzaboote/flake-compat'
+│   │   ├───flake-utils follows input 'lanzaboote/flake-utils'
+│   │   ├───gitignore: github:hercules-ci/gitignore.nix/637db329424fd7e46cf4185293b9cc8c88c95394
+│   │   │   Last modified: 2024-02-28 02:28:52
+│   │   │   └───nixpkgs follows input 'lanzaboote/pre-commit-hooks-nix/nixpkgs'
+│   │   ├───nixpkgs follows input 'lanzaboote/nixpkgs'
+│   │   └───nixpkgs-stable: github:NixOS/nixpkgs/614b4613980a522ba49f0d194531beddbb7220d3
+│   │       Last modified: 2024-03-17 17:16:56
+│   └───rust-overlay: github:oxalica/rust-overlay/dcc802a6ec4e9cc6a1c8c393327f0c42666f22e4
+│       Last modified: 2024-03-24 02:14:07
+│       ├───flake-utils follows input 'lanzaboote/flake-utils'
+│       └───nixpkgs follows input 'lanzaboote/nixpkgs'
+└───nixpkgs: github:nixos/nixpkgs/7f993cdf26ccef564eabf31fdb40d140821e12bc
+    Last modified: 2024-07-01 09:00:38

tests/functional/meson.build

@@ -69,8 +69,9 @@ functional_tests_scripts = [
   'flakes/unlocked-override.sh',
   'flakes/absolute-paths.sh',
   'flakes/build-paths.sh',
-  'flakes/flake-registry.sh',
   'flakes/flake-in-submodule.sh',
+  'flakes/flake-metadata.sh',
+  'flakes/flake-registry.sh',
   'flakes/subdir-flake.sh',
   'gc.sh',
   'nix-collect-garbage-d.sh',

tests/functional/search.sh

@@ -29,6 +29,8 @@ nix search -f search.nix '' ^ | grepQuiet hello
 
 ## Tests for multiple regex/match highlighting
 
+# FIXME: possibly not test this with colour in the future
+export CLICOLOR_FORCE=1
 e=$'\x1b' # grep doesn't support \e, \033 or even \x1b
 # Multiple overlapping regexes
 (( $(nix search -f search.nix '' 'oo' 'foo' 'oo' | grep -c "$e\[32;1mfoo$e\\[0;1m") == 1 ))

tests/unit/libutil-support/tests/cli-literate-parser.cc

@@ -1,20 +1,16 @@
 #include "cli-literate-parser.hh"
 #include "escape-string.hh"
-#include "escape-char.hh"
-#include "libexpr/print.hh"
 #include "types.hh"
 #include <ranges>
 #include <boost/algorithm/string/replace.hpp>
 #include <boost/algorithm/string/trim.hpp>
 #include <iostream>
-#include <memory>
 #include <sstream>
 #include <variant>
 
 #include "cli-literate-parser.hh"
 #include "escape-string.hh"
 #include "fmt.hh"
-#include "libexpr/print.hh"
 #include "shlex.hh"
 #include "types.hh"
 #include "strings.hh"
@@ -361,9 +357,8 @@ const char * ParseError::what() const noexcept
         return what_->c_str();
     } else {
         auto escaped = escapeString(rest, {.maxLength = 256, .escapeNonPrinting = true});
-        auto hint =
-            new HintFmt("Parse error: Expected %1%, got:\n%2%", expected, Uncolored(escaped));
-        what_ = hint->str();
+        auto hint = HintFmt("Parse error: Expected %1%, got:\n%2%", expected, Uncolored(escaped));
+        what_ = hint.str();
         return what_->c_str();
     }
 }