[neutrinoceros]

This allows targeting CPython's LimitedAPI (and stable ABI) by setting PYPROJ_LIMITED_API=1 at build time. Resulting wheels are future compatible with yet-unreleased Python versions.
The trade-off is that runtime performance might be impacted, though I suggest measuring it against real load-bearing applications, as I found that in many numpy-based extensions the impact to be negligible or even non-measurable.
I could successfully build the package and run the test suite with this locally.

I suggest a couple possible approaches to leverage this:

• append a cp314-abi3 target to the existing build matrix. Version-specific wheels will still be prefered by installers when available but will default to these otherwise, instead of having to, and often failing to build pyproj from source.
• replace version-specific wheels with a single cp311-abi3 wheel per platform. If there are no visible performance regressions this is definitely the way to go.

Blocked by

• MNT: deduplicate static PROJ_* env vars in cibw settings #1663

[neutrinoceros]

note this comment is going to age like milk because there's a new version of the Limited API coming up in Python 3.15 that's compatible with both GIL-enabled and free-threaded builds. However there are a couple other blockers right now (Cython and setuptools both have work-in-progress patches to support this). I'd be happy to revisit this later this year to add cp315-abi3.abi3t as a target

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.81%. Comparing base (cce793d) to head (3599d2d).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1600   +/-   ##
=======================================
  Coverage   95.81%   95.81%           
=======================================
  Files          20       20           
  Lines        1886     1886           
=======================================
  Hits         1807     1807           
  Misses         79       79           

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[snowman2]

Mind enabling this in the wheel builds to test?

[neutrinoceros]

enabling this in CI revealed that it is currently blocked by cython

pyproj/_geod.c:1412:6: This module uses CPython specific internals of 'array.array', which are not available in PyPy or the limited API

and indeed, compilation then predictibly fails because the generated module isn't limited-api-compliant

[snowman2]

You could test it by adding a flag to use the slower alternative:

pyproj/pyproj/_compat.pyx

Line 20 in 40d7cf8

IF CTE_PYTHON_IMPLEMENTATION == "CPython":

[neutrinoceros]

thanks for the pointer. I now expect the current CI run to succeed. Should I drop the second commit before undrafting ?

[snowman2]

I appreciate your work on this and have learned a few things in the process.

I hesitate to add this in. It doesn't significantly reduce the wheel count and makes the code slower. Someone could enable this without being aware of the consequences.

I would probably want a more performant alternative when this is enabled before merging.

[neutrinoceros]

Note that the branch currently implements my second suggested approach, but I actually would favor the first one if you like it best

[snowman2]

I should have read your comment. The first approach sounds like a good strategy.

[neutrinoceros]

I think I won't be able to avoid duplication between jobs, but it should be possible to mitigate it by moving the static part of your cibw configuration to pyproject.toml first. It could absolutely be a separate, preliminary PR, though I do not know yet when I'll have time for it. Does it seem like an acceptable plan to you ?

[snowman2]

Feel free to try it and see what it looks like.

[neutrinoceros]

see gh-1661

[neutrinoceros]

I'm planning to rebase this atop #1663 once stable

[neutrinoceros]

so the current PR tower is

• BLD: improve build logs around proj directory discovery #1664
• MNT: move the static part of cibuildwheel's configuration to pyproject.toml #1661
  • MNT: deduplicate static PROJ_* env vars in cibw settings #1663
    • BLD: add option to build future-compatible abi3 wheels #1600 (this one)