Issue when trying to use hdf5-mpi on GitHub actions

[astrofrog]

Output of brew config

HOMEBREW_VERSION: 4.2.18
ORIGIN: https://github.com/Homebrew/brew
HEAD: 9edabf02ce29e54d0b717baa757cff38ad0c0e25
Last commit: 6 days ago
Core tap HEAD: 90dbab17ffad6249b4995cca409ba1a416e4b65f
Core tap last commit: 21 minutes ago
Core tap JSON: 20 Apr 20:14 UTC
Core cask tap HEAD: 6fd5fab818cc72c3946db37af0708de1c9bddb57
Core cask tap last commit: 35 minutes ago
Core cask tap JSON: 20 Apr 20:14 UTC
HOMEBREW_PREFIX: /opt/homebrew
HOMEBREW_CASK_OPTS: ["--no-quarantine"]
HOMEBREW_COLOR: set
HOMEBREW_MAKE_JOBS: 3
HOMEBREW_NO_AUTO_UPDATE: set
HOMEBREW_NO_INSTALL_CLEANUP: set
Homebrew Ruby: 3.1.4 => /opt/homebrew/Library/Homebrew/vendor/portable-ruby/3.1.4/bin/ruby
CPU: 3-core 64-bit dunno
Clang: 15.0.0 build 1500
Git: 2.44.0 => /opt/homebrew/bin/git
Curl: 8.4.0 => /usr/bin/curl
macOS: 14.4.1-arm64
CLT: 15.3.0.0.1.1708646388
Xcode: 15.0.1 => /Applications/Xcode_15.0.1.app/Contents/Developer
Rosetta 2: false

Output of brew doctor

Warning: Some installed formulae are deprecated or disabled.
You should find replacements for the following formulae:
  [email protected]
  packer

Warning: You have an unnecessary local Cask tap.
This can cause problems installing up-to-date casks.
Please remove it by running:
  brew untap homebrew/cask

Warning: You have an unnecessary local Core tap!
This can cause problems installing up-to-date formulae.
Please remove it by running:
 brew untap homebrew/core

Description of issue

I am running into an issue when using Homebrew on GitHub actions. If I use the following minimal configuration:

name: CI

on:
  push:
  pull_request:
  workflow_dispatch:

jobs:
  build:
    runs-on: macos-14
    steps:
      - uses: actions/checkout@v3
      - name: brew update
        run: brew update
      - name: Install hdf5-mpi
        run: brew install hdf5-mpi
      - name: brew config
        run: brew config
      - name: brew doctor
        run: brew doctor
      - name: Compile test file
        run: h5pfc test.f90

where test.f90 just contains:

program test
print *,"Hello, world!"
end program test

The compilation/last step fails with the following error:

--------------------------------------------------------------------------
The Open MPI wrapper compiler was unable to find the specified compiler
gfortran in your PATH.
Note that this compiler was either specified at configure time or in
one of several possible environment variables.
--------------------------------------------------------------------------

Full log: https://github.com/astrofrog/homebrew-test/actions/runs/8767514207/job/24060852030

The issue seems to be related to the fact that the gfortran binary doesn't exist in /opt/homebrew/bin/ on GitHub Actions, only gfortran-11, gfortran-12 and gfortran-13. On my local computer gfortran seems to exist in /opt/homebrew/bin/ so I don't have the same issue. I can't figure out if this is a problem with Homebrew, or GitHub Action's installation of it, or something else.

[ZhongRuoyu]

This issue is specific to GitHub Actions runner images: https://github.com/actions/runner-images/blob/macos-14/20240414.1/images/macos/scripts/build/install-gcc.sh#L15-L19

As a workaround, you can try brew unlink gcc && brew link gcc.