Test LRE fixes

Author: aaronmondal

flake.nix

@@ -35,6 +35,12 @@
 
           customStdenv = import ./tools/llvmStdenv.nix { inherit pkgs; };
 
+          # TODO(aaronmondal): This doesn't work with rules_rust yet.
+          customClang = pkgs.callPackage ./tools/customClang.nix {
+            inherit pkgs;
+            stdenv = customStdenv;
+          };
+
           craneLib = crane.lib.${system};
 
           src = pkgs.lib.cleanSourceWith {
@@ -128,6 +134,7 @@
               # Additional tools from within our development environment.
               local-image-test
               generate-toolchains
+              customClang
             ] ++ maybeDarwinDeps;
             shellHook = ''
               # Generate the .pre-commit-config.yaml symlink when entering the

local-remote-execution/image.nix

@@ -2,27 +2,10 @@
 
 let
   customStdenv = import ../tools/llvmStdenv.nix { inherit pkgs; };
-
-  # Bazel expects a single frontend for both C and C++. That works for GCC but
-  # not for clang. This wrapper selects `clang` or `clang++` depending on file
-  # ending.
-  # TODO(aaronmondal): The necessity of this is a bug.
-  #                    See: https://github.com/NixOS/nixpkgs/issues/216047
-  #                    and https://github.com/NixOS/nixpkgs/issues/150655
-  customClang = pkgs.writeShellScriptBin "customClang" ''
-    #! ${customStdenv.shell}
-    function isCxx() {
-       if [ $# -eq 0 ]; then false
-       elif [ "$1" == '-xc++' ]; then true
-       elif [[ -f "$1" && "$1" =~ [.](hh|H|hp|hxx|hpp|HPP|h[+]{2}|tcc|cc|cp|cxx|cpp|CPP|c[+]{2}|C)$ ]]; then true
-       else isCxx "''${@:2}"; fi
-    }
-    if isCxx "$@"; then
-      exec "${customStdenv.cc}/bin/clang++" "$@"
-    else
-      exec "${customStdenv.cc}/bin/clang" "$@"
-    fi
-  '';
+  customClang = pkgs.callPackage ../tools/customClang.nix {
+    inherit pkgs;
+    stdenv = customStdenv;
+  };
 in
 
 # TODO(aaronmondal): Bazel and a few other tools in this container are only

tools/customClang.nix

@@ -0,0 +1,22 @@
+{ pkgs, stdenv }:
+
+# Bazel expects a single frontend for both C and C++. That works for GCC but
+# not for clang. This wrapper selects `clang` or `clang++` depending on file
+# ending.
+# TODO(aaronmondal): The necessity of this is a bug.
+#                    See: https://github.com/NixOS/nixpkgs/issues/216047
+#                    and https://github.com/NixOS/nixpkgs/issues/150655
+pkgs.writeShellScriptBin "customClang" ''
+  #! ${stdenv.shell}
+  function isCxx() {
+     if [ $# -eq 0 ]; then false
+     elif [ "$1" == '-xc++' ]; then true
+     elif [[ -f "$1" && "$1" =~ [.](hh|H|hp|hxx|hpp|HPP|h[+]{2}|tcc|cc|cp|cxx|cpp|CPP|c[+]{2}|C)$ ]]; then true
+     else isCxx "''${@:2}"; fi
+  }
+  if isCxx "$@"; then
+    exec "${stdenv.cc}/bin/clang++" "$@"
+  else
+    exec "${stdenv.cc}/bin/clang" "$@"
+  fi
+''