do not use "flags": "-march={name} -mtune={name}" because it's redundant

[Jeff Hammond]

Summary

-march={name} -mtune={name} should be replaced with -march={name}. When -march={name} is set, it implies -mtune={name} unless -mtune is set to something else.

Rationale

flang-new does not support -mtune, only -march and -mcpu. I am trying to get this fixed (llvm/llvm-project#89888).

However, this change should be made independent of my issue, because Spack should not specify a redundant argument.

Description

The solution:

sed -i "s/\"-march={name} -mtune={name}\"/\"-march={name}\"/g" lib/spack/external/archspec/json/cpu/microarchitectures.json

I will submit a PR shortly.

Additional information

No response

General information

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

[Jeff Hammond]

Attempting to fix here: archspec/archspec-json#100.