Understanding binutils-darwin-wrapper/nix-support bad substitution

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1

I’m getting the following error in a GitHub action on macOS

/nix/store/3z9jfr419kz91rzx0sq5880k14s70sjk-cctools-binutils-darwin-wrapper-927.0.2/nix-support/setup-hook: line 134: ${cmd^^}${role_post}=${cmd}: bad substitution

As I don’t have a Mac available locally, It’s especially difficult to understand what’s going on.

Can you offer any hints on how to understand what is going on?

2

looks to me an illegal bash command. A guess out of the blue, the darwin system is using the system’s bash (which behaves bit differently on macos vs linux). I git grepped ${cmd^^}${role_post} and it’s coming from nigpkgs/pkgs/build-support/bintools-wrapper/setup-hook.sh I wonder if you can avoid running this by using clang or more darwin specific compilation tools. Sorry if Im not of much help.

3

Spot on!

It turns out that nix-shell --run <whatever> gave the warning:

warning: file 'nixpkgs' was not found in the Nix search path (add it using $NIX_PATH or -I), at (string):1:9; will use bash from your environment

This is in a GitHub action where I install Nix with cachix/install-nix-action@v12, so this particular problem is easily fixed by setting nixpkgs thus:

- name: Install Nix
  uses: cachix/install-nix-action@v12
  with:
    nix_path: nixpkgs=channel:nixos-unstable

I don’t like that nixos-unstable, but that is best discussed elsewhere.

1 Like
4

Hmm, interesting. Looking at the source code, maybe setting NIX_BUILD_SHELL environment variable to bash in the GH workflow and adding bashInteractive to shell.nix would be able to bypass this? Or are inputs added to the environment too late?