Merge pull request #71 from Radvendii/master

discard string context of git config's core.excludesFile

find-files.nix

@@ -242,7 +242,12 @@ rec {
         for
           (guard (toLower section == "core" && toLower key == "excludesfile"))
           (_:
-            resolveFile (home /.) value
+            # Paths with context can't be appended to other paths, so we have to
+            # remove the context here.
+            # SAFETY: gitignore.nix is not responsible for making sure the
+            # store paths pointed to in your global git config have been
+            # realised.
+            resolveFile (home /.) (builtins.unsafeDiscardStringContext value)
           )
       )
     );
@@ -290,7 +295,7 @@ rec {
    */
   # TODO: get something like builtins.pathType or builtins.stat into Nix
   guardFile = p: if pathExists p then [p] else [];
-  guardNonEmptyString = s: if s == "" then [s] else [];
+  guardNonEmptyString = s: if s == "" then [] else [s];
   guardNonNull = a: if a != null then a else [];
 
 

tests/default.nix

@@ -3,6 +3,8 @@
 let
   testdata = import ./testdata.nix { inherit pkgs; };
   runner = import ./runner.nix { inherit pkgs; };
+  gitignoreNix = (import ../. { inherit lib; });
+  inherit (gitignoreNix) gitignoreSource;
 in
 {
   plain = runner.makeTest { name = "plain"; rootDir = testdata.sourceUnfiltered + "/test-tree"; };
@@ -22,6 +24,87 @@ in
   subdir-9 = runner.makeTest { name = "subdir-9"; rootDir = testdata.sourceUnfiltered + "/test-tree"; subpath = "9-expected"; };
   subdir-10 = runner.makeTest { name = "subdir-10"; rootDir = testdata.sourceUnfiltered + "/test-tree"; subpath = "10-subdir-ignoring-itself"; };
 
+  # https://github.com/hercules-ci/gitignore.nix/pull/71
+  regression-config-with-store-path =
+    pkgs.stdenv.mkDerivation {
+      name = "config-with-store-path";
+      src = testdata.sourceUnfiltered + "/test-tree";
+      buildInputs = [ pkgs.nix ];
+      NIX_PATH="nixpkgs=${pkgs.path}";
+      buildPhase = ''
+        # Set up an alternate nix store with a different store directory
+        export TEST_ROOT=$(pwd)/test-root
+        export NIX_BUILD_HOOK=
+        export NIX_CONF_DIR=$TEST_ROOT/etc
+        export NIX_LOCALSTATE_DIR=$TEST_ROOT/var
+        export NIX_LOG_DIR=$TEST_ROOT/var/log/nix
+        export NIX_STATE_DIR=$TEST_ROOT/var/nix
+        export NIX_STORE_DIR=$TEST_ROOT/store
+        export NIX_STORE=$TEST_ROOT/store
+
+        mkdir -p $NIX_STORE_DIR $NIX_CONF_DIR
+
+        # Write nix.conf - disable sandbox for nested builds
+        cat > $NIX_CONF_DIR/nix.conf <<EOF
+        sandbox = false
+        substituters =  # none
+        EOF
+
+        nix-store --init
+
+        # Create config directory with gitconfig that references excludesfile
+        # This simulates home-manager creating a config in the store
+        # Both derivations are created in one expression so excludesfile can be referenced directly
+        configdir=$(nix-build --no-out-link --expr "
+          let
+            pkgs = import <nixpkgs> {};
+            excludesfile = derivation {
+              name = \"excludesfile\";
+              system = builtins.currentSystem;
+              builder = \"/bin/sh\";
+              args = [\"-c\" \"echo -n \\\"\\\" > \\\$out\"];
+            };
+          in
+          derivation {
+            name = \"home-config\";
+            system = builtins.currentSystem;
+            builder = \"${pkgs.bash}/bin/bash\";
+            PATH = \"${pkgs.coreutils}/bin\";
+            inherit excludesfile;
+            args = [\"-c\" \"
+              mkdir -p \\\$out/git
+              printf '[core]\\\\n    excludesfile = %s\\\\n' \\\$excludesfile > \\\$out/git/config
+            \"];
+          }
+        ")
+
+        # Use XDG_CONFIG_HOME pointing directly to this store path (like home-manager does)
+        export XDG_CONFIG_HOME=$configdir
+        echo "XDG_CONFIG_HOME is now: $XDG_CONFIG_HOME"
+        echo "Config file contents:"
+        cat $XDG_CONFIG_HOME/git/config
+
+        echo "---------------"
+        echo "Testing gitignoreSource with store path in git config:"
+        # This calls the real main code (gitignoreSource) which will naturally
+        # evaluate globalConfiguredExcludesFile when building the pattern tree
+        # Without the fix: fails with "a string that refers to a store path cannot be appended to a path"
+        # With the fix: succeeds (unsafeDiscardStringContext strips the context)
+        if nix-instantiate --eval --expr \
+            '((import ${gitignoreSource ../.} {}).gitignoreSource ./.).outPath'
+        then touch $out
+        else
+          echo
+          echo "Failed to run with a global excludes file from the nix store."
+          echo "This may be because the store path gets misinterpreted as a string context."
+          echo "See https://github.com/hercules-ci/gitignore.nix/pull/71"
+          exit 1
+        fi
+      '';
+      preInstall = "";
+      installPhase = ":";
+    };
+
   # Make sure the files aren't added to the store before filtering.
   shortcircuit = runner.makeTest {
     name = "nested";
@@ -34,8 +117,7 @@ in
   };
 
   unit-tests =
-    let gitignoreNix = import ../default.nix { inherit (pkgs) lib; };
-        inherit (gitignoreNix) gitignoreFilterWith gitignoreSourceWith;
+    let inherit (gitignoreNix) gitignoreFilterWith gitignoreSourceWith;
         example = gitignoreFilterWith { basePath = ./.; extraRules = ''
           *.foo
           !*.bar