Allow specifying compiler version for 'spack stack create env'

[AlexanderRichert-NOAA]

Summary

This PR borrows the logic from #1213 that allows a compiler version to be specified in spack stack create env. It's a couple of tweaks to stack_env.py. This isn't strictly urgent, but I'm hoping to put this in the 1.8.0 release in anticipation of supporting installations by NCO (plus maybe others will find it useful; I know it will be useful for Acorn, and maybe also for NRL?).

Testing

Tested on Acorn and personal machine.

• spack stack create env --compiler gcc correctly yields prefer: ['%gcc'] in spack.yaml
• spack stack create env --compiler [email protected] correctly yields prefer: ['%[email protected]'] in spack.yaml
• spack stack create env --compiler gcc with unspecified name correctly yields env directory with name empty.linux.default.gcc
• spack stack create env --compiler [email protected] with unspecified name correctly yields env directory with name empty.linux.default.gcc-8.5.0

Applications affected

n/a

Systems affected

All

Dependencies

none

Issue(s) addressed

none

Checklist

• This PR addresses one issue/problem/enhancement, or has a very good reason for not doing so.
• These changes have been tested on the affected systems and applications.
• All dependency PRs/issues have been resolved and this PR can be merged.

[climbfuji]

I am fine with merging this into the release branch. I haven't tested this myself, but I will when I move to the next platform to roll out 1.8.0.

Note that there's no need to go back to existing 1.8.0 installs and redo them. Thanks for making these changes.

[climbfuji]

This is so much easier; do you remember why we put that complicated logic in place originally (I don't)?

[AlexanderRichert-NOAA]

No I don't remember... Maybe something to do with supporting multiple compilers in an environment..?

[climbfuji]

Oh right. This is something we need to test before we merge. The Intel or oneAPI environments require some packages to be built with gcc, therefore the compilers line in the spack config must contain both compilers. See

spack-stack/configs/sites/tier1/nautilus/packages_intel.yaml

Line 3 in a8bb4fb

compiler:: [[email protected],[email protected]]

We need to make sure that this still works (i.e. a spack module [tcl|lmod] refresh followed by spack stack setup-meta-modules still works as expected. I think it does, but better to check.

[AlexanderRichert-NOAA]

Sure. I think we would expect it to work though, on account of there being only one value for target_compiler (based on self.compiler)? Unless users can specify multiple...

[climbfuji]

It works. See "test env" step in https://github.com/JCSDA/spack-stack/actions/runs/10816758746/job/30008609091?pr=1294 (look for ecflow)