python: improve ABI name detection

[minijackson]

Description of changes

This makes pkgsCross.ppc64.python3Packages.pip work again.

We somewhat recently changed the PPC64 arch to be powerpc64-unknown-linux-gnuabielfv2 with this ABI name as a way to differentiate between the ELFv1 and ELFv1 variant of PowerPC64. Python doesn't support this ABI name (which is expected), so I went and changed the mapping between nixpkgs' ABI names and Python's ABI names.

This basically use the ABI name as-is, if it is supported by Python, and will fallback to the "gnu" ABI if it is not supported.

This targets master as this shouldn't cause rebuilds for Tier 1, Tier 2, or Tier 3 architectures.

Pinging @NixOS/exotic-platform-maintainers and @FRidh

Things done

• Tested platforms (by building python3Packages.pip:
  • x86_64-linux (cache hit)
  • pkgsCross.ppc64
  • pkgsCross.ppc64-musl
  • pkgsCross.raspberryPi
  • pkgsCross.aarch64-multiplatform
  • pkgsCross.gnu32
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
  • Nothing to be built.
• Tested basic functionality of all binary files (usually in ./result/bin/)
  • pip --version works for gnu32 cross
• 23.05 Release Notes (or backporting 22.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
  • (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• Fits CONTRIBUTING.md.

[sternenseemann]

cc @amjoseph-nixpkgs

[FRidh]

cc @pjjw

[pjjw]

nice! thanks for doing a more complete sol'n.

[minijackson]

Would it be also possible to backport this PR? I'd like to keep using stable for work, but I can't for the life of me figure out how to override the cross-compiled python, but not the native one.

[FRidh]

With the backport label added a new PR targeting stable will be automatically opened.

[github-actions]

Successfully created backport PR #211589 for release-22.11.

[ghost]

LGTM

[lopsided98]

This breaks in the case of musl on armv7l, because parsed.abi.name is musleabihf, which needs to be mapped to gnueabihf.

[ghost]

musleabihf, which needs to be mapped to gnueabihf.

Seriously? Python calls all Linux platforms -gnu even if they don't use the GNU C Library?

I mean given the state of the Python ecosystem I'm willing to believe this, but it just sounds so totally crazy that I wanted to double-check. Is there some documentation of this weirdness somewhere?

[lopsided98]

The only "documentation" I know of is the configure script: https://github.com/python/cpython/blob/e488e300f5c01289c10906c2e53a8e43d6de32d8/configure.ac#L724

[r-burns]

There is some discussion about it in this thread: python/cpython#87278

[pjjw]

yeah, looks like the "real" fix is stuck here: python/cpython#96001