Pip CI should be tested against MacOS ARM (M1)

[notatallshaw]

What's the problem this feature will solve?

MacOS ARM (M1) is a very popular user platform, but currently Pip's CI only runs against MacOS x86, which at this point is deminishing rapidly in terms of users who are on it

Describe the solution you'd like

Enable MacOS ARM (M1) via the macos-latest GitHub runners

Alternative Solutions

Well, at some point macos-12 will stop being supported by GitHub so the alternative is eventually not testing against MacOS

Additional context

Last I checked Python 3.8 and 3.9 had a failing test (test_uninstall_editable_from_usersite) on MacOS ARM, but Python 3.10+ all worked fine.

Code of Conduct

• I agree to follow the PSF Code of Conduct.

[uranusjr]

I think it’d be reasonable enough to keep 3.8 and 3.9 on Intel and only run 3.10+ on ARM. We’re probably going to drop 3.8 before GHA drops macos-12. They only just dropped 11 in June, and 10 was dropped in 2022, so 2026 should be a reasonable deadline for 12. That’s roughly the timeline we should drop 3.8 anyway.

3.9 is more problematic, but we can probably figure something out when we need to. Worst case scenario we can just skip the test (those usersite tests are known to be problematic due to system configurations)

[ichard26]

Even if the number of Python users on MacOS x86 is declining, is it going to continue being a substantial amount? I tried to find some data on this, but I wasn't able to (I don't use MacOS at all). I'm totally in favour of adding MacOS ARM to our CI matrix (gating it to Python 3.10+) but I'm less sure of removing Python 3.10+ on Intel from CI.

[notatallshaw]

I don't propose removing MacOS x86 while the github runners are still available.

[ichard26]

We’re probably going to drop 3.8 before GHA drops macos-12

macos-12 is now deprecated and will no longer exist after December 3rd this year. We can migrate to macos-13 to retain CI coverage on Intel MacOS for at least a few more months after that.

[notatallshaw]

I think it makes sense to switch macos-12 to macos-13, as well as test macos-latest.