pip 20 and pypy - changes needed to pep425tags.py

[mattip]

pip20 now uses packaging.tags, not pep425tags.py, but wheel does not seem to have made that change yet. This breaks building wheels for PyPy, since the semantics of the python tag changed.
At a minimum, the pypy-specific stanza should be removed from get_impl_version_info, so the implementation becomes a one-liner sys.version_info[0], sys.version_info[1]. Are there plans to transition wheel to packaging.tags?

Is there a way to add PyPy to the testing matrix for wheel?

See pypa/packaging#233, pypa/packaging#184, and pypa/pip#7629

[mattip]

I see there is an entry in the travis CI for pypy. Is wheel testing with pip20?

[agronholm]

I've switched wheel to use Github Actions instead of Travis, and PyPy3 is part of the matrix now. The test suite does not involve calling pip.

I will look at packaging.tags to see if wheel can use them.

[agronholm]

I've implemented the minimum required changes in pep425tags.py. Please test with the pypytags branch and report back here.

As for packaging.tags, it cannot replace pep425tags.py, at least not completely. I would also have to decide whether it's okay to add it as a dependency or to vendor it.

[mattip]

looks good to me. I tried it out and the wheel created is now lxml-4.5.0a0-pp36-pypy36_pp73-linux_x86_64.whl where master created lxml-4.5.0a0-pp373-pypy36_pp73-linux_x86_64.whl @antocuni, does this look right: pp36 in place of pp373?

[antocuni]

LGTM. I confirm that with the patched version of wheel, I can build a wheel and install it on PyPy

[agronholm]

I'm going to cram a couple more PRs in and then make a release. Shouldn't take more than a few days max.

[pradyunsg]

Hurrah! Thanks @agronholm! ^>^