cc-wrapper.sh: mktemp: command not found

[cormacrelf]

Describe the bug

cc-wrapper.sh is not using Nix mktemp, it's expecting one to be in the environment. So it fails when you run it with an empty PATH.

This is happening because it's:

1. Saving a PATH backup
2. Setting PATH to nix's coreutils/bin:gnugrep:bin
3. Using it for grep & cat etc
4. Restoring the PATH backup
5. Attempting to use mktemp

nixpkgs/pkgs/build-support/cc-wrapper/cc-wrapper.sh

Lines 239 to 249 in 0e97035

	PATH="$path_backup"
	# Old bash workaround, see above.
	# if a cc-wrapper-hook exists, run it.
	if [[ -e @out@/nix-support/cc-wrapper-hook ]]; then
	compiler=@prog@
	source @out@/nix-support/cc-wrapper-hook
	fi
	if (( "${NIX_CC_USE_RESPONSE_FILE:-@use_response_file_by_default@}" >= 1 )); then
	responseFile=$(mktemp "${TMPDIR:-/tmp}/cc-params.XXXXXX")

Steps To Reproduce

1. On pretty much any system:

   $ env - $(which nix) run nixpkgs#clang
   /nix/store/c1ib07kj7baid3s3wf5m98hcpbvgs8mk-clang-wrapper-16.0.6/bin/clang: line 249: mktemp: command not found

There is no step 2. You might encounter a situation like this when running Clang with a heavily stripped environment in a Remote Build Execution context.

Expected behavior

cc-wrapper should not error if the PATH is empty

Additional context

It looks to me like this is the root cause of #258608. Probably same with tweag/rules_nixpkgs#439.

Notify maintainers

No maintainers seem to be listed in cc-wrapper's metadata. But maybe @Artturin?

Metadata

Please run nix-shell -p nix-info --run "nix-info -m" and paste the result.

[user@system:~]$ nix-shell -p nix-info --run "nix-info -m"
almost any system imaginable

---

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[Artturin]

#316700