export variables with msys environment path, and add options to append to PATH variable

[windelbouwman]

Hi,

I would like to use this action to build the hdf5 rust crate against a msys2 package for HDF5.

Things I would like to request for this github action:

• I want to use the default shell, and extend the PATH environment variable with the bin folder in the msys2 installation. Is this possible to add to this action? So not using the msys2 shell, but having the PATH environment variable extended by the setup-msys2 action?
• An exported variable with the location of the msys2 installation. For now, I must manually specify a path to the installation to find HDF5. Specifically, I need to set HDF5_DIR=D:\a\_temp\msys64\mingw64, for the D:\a\_temp\msys64\mingw64 part I would like to be able to use some sort of variable.

[Biswa96]

Is not it possible to build the whole hdf5 rust crate in msys2's mingw environment? It may not require those path manipulation. We've rust package also.

[eine]

You can get the location of the MSYS2 installation by executing cygpath -m /. See https://github.com/msys2/setup-msys2/runs/6554920729?check_suite_focus=true#step:5:7 and https://github.com/msys2/setup-msys2/blob/main/.github/workflows/Test.yml#L399.

[eine]

As commented in #228 (comment), I added a couple of examples to show how to save the MSYS2 root location to a variable, either from powershell or from python:

setup-msys2/.github/workflows/Test.yml

Lines 400 to 408 in 066de4c

	- shell: pwsh
	run: |
	$Env:MSYS2_ROOT = msys2 -c 'cygpath -m /'
	$Env:MSYS2_ROOT
	- shell: python
	run: |
	from subprocess import check_output
	MSYS2_ROOT = check_output(['msys2', '-c', 'cygpath -m /'], shell=True).decode('utf-8')
	print(MSYS2_ROOT)

[lazka]

There is now an action output which you can use to extend your PATH: https://github.com/msys2/setup-msys2?tab=readme-ov-file#msys2-location (This is an absolute Windows path)

I think it would be best to leave it to users on how, in which order, and when to extend PATH. setup-python has it, via an update-environment option https://github.com/actions/setup-python/blob/04c1311429f7be71707d8ab66c7af8a14e54b938/src/find-python.ts#L111 but I'm a bit worried that this might lead to conflicts if users enable it without understanding the consequences. And under normal circumstances with users using bash this isn't needed.