copyPathToStore(): Preserve symlinks

E.g. in a derivation attribute `foo = ./bar`, if ./bar is a symlink,
we should copy the symlink to the store, not its target. This restores
the behaviour of Nix <= 2.19.

(cherry picked from commit 26b87e78b5)

# Conflicts:
#	tests/functional/meson.build

src/libexpr/eval.cc

@@ -2400,7 +2400,7 @@ StorePath EvalState::copyPathToStore(NixStringContext & context, const SourcePat
         : [&]() {
             auto dstPath = fetchToStore(
                 *store,
-                path.resolveSymlinks(),
+                path.resolveSymlinks(SymlinkResolution::Ancestors),
                 settings.readOnlyMode ? FetchMode::DryRun : FetchMode::Copy,
                 path.baseName(),
                 ContentAddressMethod::Raw::NixArchive,

tests/functional/meson.build

@@ -0,0 +1,248 @@
+project('nix-functional-tests',
+  version : files('.version'),
+  default_options : [
+    'cpp_std=c++2a',
+    # TODO(Qyriad): increase the warning level
+    'warning_level=1',
+    'errorlogs=true', # Please print logs for tests that fail
+  ],
+  meson_version : '>= 1.3',
+  license : 'LGPL-2.1-or-later',
+)
+
+fs = import('fs')
+
+nix = find_program('nix')
+bash = find_program('bash', native : true)
+busybox = find_program('busybox', native : true, required : false)
+# Look up `coreutils` package by searching for `ls` binary.
+# Previously we looked up `coreutils` on `linux`, but that is not
+# guaranteed to exist either.
+coreutils = find_program('ls', native : true)
+dot = find_program('dot', native : true, required : false)
+
+nix_bin_dir = fs.parent(nix.full_path())
+
+test_confdata = {
+  'bindir': nix_bin_dir,
+  'coreutils': fs.parent(coreutils.full_path()),
+  'dot': dot.found() ? dot.full_path() : '',
+  'bash': bash.full_path(),
+  'sandbox_shell': busybox.found() ? busybox.full_path() : '',
+  'PACKAGE_VERSION': meson.project_version(),
+  'system': host_machine.cpu_family() + '-' + host_machine.system(),
+}
+
+# Just configures `common/vars-and-functions.sh.in`.
+# Done as a subdir() so Meson places it under `common` in the build directory as well.
+subdir('common')
+
+config_nix_in = configure_file(
+  input : 'config.nix.in',
+  output : 'config.nix',
+  configuration : test_confdata,
+)
+
+suites = [
+  {
+    'name' : 'main',
+    'deps': [],
+    'tests': [
+      'test-infra.sh',
+      'gc.sh',
+      'nix-collect-garbage-d.sh',
+      'remote-store.sh',
+      'legacy-ssh-store.sh',
+      'lang.sh',
+      'lang-gc.sh',
+      'characterisation-test-infra.sh',
+      'experimental-features.sh',
+      'fetchMercurial.sh',
+      'gc-auto.sh',
+      'user-envs.sh',
+      'user-envs-migration.sh',
+      'binary-cache.sh',
+      'multiple-outputs.sh',
+      'nix-build.sh',
+      'gc-concurrent.sh',
+      'repair.sh',
+      'fixed.sh',
+      'export-graph.sh',
+      'timeout.sh',
+      'fetchGitRefs.sh',
+      'gc-runtime.sh',
+      'tarball.sh',
+      'fetchGit.sh',
+      'fetchurl.sh',
+      'fetchPath.sh',
+      'fetchTree-file.sh',
+      'simple.sh',
+      'referrers.sh',
+      'optimise-store.sh',
+      'substitute-with-invalid-ca.sh',
+      'signing.sh',
+      'hash-convert.sh',
+      'hash-path.sh',
+      'gc-non-blocking.sh',
+      'check.sh',
+      'nix-shell.sh',
+      'check-refs.sh',
+      'build-remote-input-addressed.sh',
+      'secure-drv-outputs.sh',
+      'restricted.sh',
+      'fetchGitSubmodules.sh',
+      'fetchGitVerification.sh',
+      'readfile-context.sh',
+      'nix-channel.sh',
+      'recursive.sh',
+      'dependencies.sh',
+      'check-reqs.sh',
+      'build-remote-content-addressed-fixed.sh',
+      'build-remote-content-addressed-floating.sh',
+      'build-remote-trustless-should-pass-0.sh',
+      'build-remote-trustless-should-pass-1.sh',
+      'build-remote-trustless-should-pass-2.sh',
+      'build-remote-trustless-should-pass-3.sh',
+      'build-remote-trustless-should-fail-0.sh',
+      'build-remote-with-mounted-ssh-ng.sh',
+      'nar-access.sh',
+      'impure-eval.sh',
+      'pure-eval.sh',
+      'eval.sh',
+      'repl.sh',
+      'binary-cache-build-remote.sh',
+      'search.sh',
+      'logging.sh',
+      'export.sh',
+      'config.sh',
+      'add.sh',
+      'chroot-store.sh',
+      'filter-source.sh',
+      'misc.sh',
+      'dump-db.sh',
+      'linux-sandbox.sh',
+      'supplementary-groups.sh',
+      'build-dry.sh',
+      'structured-attrs.sh',
+      'shell.sh',
+      'brotli.sh',
+      'zstd.sh',
+      'compression-levels.sh',
+      'nix-copy-ssh.sh',
+      'nix-copy-ssh-ng.sh',
+      'post-hook.sh',
+      'function-trace.sh',
+      'fmt.sh',
+      'eval-store.sh',
+      'why-depends.sh',
+      'derivation-json.sh',
+      'derivation-advanced-attributes.sh',
+      'import-from-derivation.sh',
+      'nix_path.sh',
+      'nars.sh',
+      'placeholders.sh',
+      'ssh-relay.sh',
+      'build.sh',
+      'build-delete.sh',
+      'output-normalization.sh',
+      'selfref-gc.sh',
+      'db-migration.sh',
+      'bash-profile.sh',
+      'pass-as-file.sh',
+      'nix-profile.sh',
+      'suggestions.sh',
+      'store-info.sh',
+      'fetchClosure.sh',
+      'completions.sh',
+      'impure-derivations.sh',
+      'path-from-hash-part.sh',
+      'path-info.sh',
+      'toString-path.sh',
+      'read-only-store.sh',
+      'nested-sandboxing.sh',
+      'impure-env.sh',
+      'debugger.sh',
+      'extra-sandbox-profile.sh',
+      'help.sh',
+      'symlinks.sh',
+    ],
+    'workdir': meson.current_source_dir(),
+  },
+]
+
+nix_store = dependency('nix-store', required : false)
+if nix_store.found()
+  add_languages('cpp')
+  subdir('test-libstoreconsumer')
+  suites += {
+    'name': 'libstoreconsumer',
+    'deps': [
+      libstoreconsumer_tester,
+    ],
+    'tests': [
+      'test-libstoreconsumer.sh',
+    ],
+    'workdir': meson.current_source_dir(),
+  }
+
+endif
+
+# Plugin tests require shared libraries support.
+nix_expr = dependency('nix-expr', required : false)
+if nix_expr.found() and get_option('default_library') != 'static'
+  add_languages('cpp')
+  subdir('plugins')
+  suites += {
+    'name': 'plugins',
+    'deps': [
+      libplugintest,
+    ],
+    'tests': [
+      'plugins.sh',
+    ],
+    'workdir': meson.current_source_dir(),
+  }
+endif
+
+subdir('ca')
+subdir('dyn-drv')
+subdir('flakes')
+subdir('git-hashing')
+subdir('local-overlay-store')
+
+foreach suite : suites
+  workdir = suite['workdir']
+  suite_name = suite['name']
+  foreach script : suite['tests']
+    # Turns, e.g., `tests/functional/flakes/show.sh` into a Meson test target called
+    # `functional-flakes-show`.
+    name = fs.replace_suffix(script, '')
+
+    test(
+      name,
+      bash,
+      args: [
+        '-x',
+        '-e',
+        '-u',
+        '-o', 'pipefail',
+        script,
+      ],
+      suite : suite_name,
+      env : {
+        '_NIX_TEST_SOURCE_DIR': meson.current_source_dir(),
+        '_NIX_TEST_BUILD_DIR': meson.current_build_dir(),
+        'TEST_NAME': suite_name / name,
+        'NIX_REMOTE': '',
+        'PS4': '+(${BASH_SOURCE[0]-$0}:$LINENO) ',
+      },
+      # Some tests take 15+ seconds even on an otherwise idle machine;
+      # on a loaded machine this can easily drive them to failure. Give
+      # them more time than the default of 30 seconds.
+      timeout : 300,
+      # Used for target dependency/ordering tracking, not adding compiler flags or anything.
+      depends : suite['deps'],
+      workdir : workdir,
+    )
+  endforeach
+endforeach

tests/functional/simple.sh

@@ -15,7 +15,7 @@ echo "output path is $outPath"
 (! [ -w $outPath ])
 
 text=$(cat "$outPath/hello")
-if test "$text" != "Hello World!"; then exit 1; fi
+[[ "$text" = "Hello World!" ]]
 
 TODO_NixOS
 

tests/functional/symlinks.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+
+source common.sh
+
+# Check that when we have a derivation attribute that refers to a
+# symlink, we copy the symlink, not its target.
+# shellcheck disable=SC2016
+nix build --impure --no-link --expr '
+  with import ./config.nix;
+
+  mkDerivation {
+    name = "simple";
+    builder = builtins.toFile "builder.sh" "[[ -L \"$symlink\" ]]; mkdir $out";
+    symlink = ./lang/symlink-resolution/foo/overlays;
+  }
+'