Modify `compilers.yaml` through through Spack CLI

Summary

Modifying compilers.yaml manually and using spack compiler {find/add} [path] are both very effective in setting compiler configuration. I'd like a quick way add paths/flags/environment variables through the Spack CLI. Something like:

spack config add compilers:clang@16.0.6:flags:cflags:[-O3,-fPIC]

or

spack compiler set llvm@16.0.6 paths:f77:usr/bin/gfortran

Rationale

This feature request is related to a problem I have in CI/CD.

I have a tool that that tests compilers with different flags. Ideally, I'd like to run a script that goes along the lines of:

./run_compiler_test.sh

spack config add compilers:clang@16.0.6:flags:cflags:[-O1]
./run_compiler_test.sh

spack config add compilers:clang@16.0.6:flags:cflags:[-O2]
./run_compiler_test.sh

spack config add compilers:clang@16.0.6:flags:cflags:[-O3]
./run_compiler_test.sh

Description

No response

Additional information

I've looked into using spack config add compilers:... but because compilers.yaml is a list structure, the spack config add command fails for structural reasons.

I found success in creating a parser argument ,spack compiler set, that enabled me to add the features above but ideally the command should be spack config add for software consistency.

General information

• I have searched the issues of this repo and believe this is not a duplicate

Start by examining the existing spack config add and spack compiler set CLI behavior, along with how compilers.yaml represents compiler lists. Reproduce the structural failure with the example commands, then define and verify CLI support for adding compiler paths, flags, and environment variables without breaking the configuration structure.