Implement PEP 639: support for Metadata-Version: 2.4

[agriyakhetarpal]

Description

This PR implements PEP 0639 for make_wheels.py, which bumps the core metadata version from 2.1 to 2.4.

Here's a short summary of the changes that have been added:

• the 'License': 'MIT' (now deprecated) field has been changed to the favoured 'License-Expression': 'MIT' field, i.e., the SPDX identifier for the MIT License;
• License classifiers, while still common, have been deprecated: I removed the MIT license classifier in favour of compliance with the standard (in the above point), even though the deprecation cycle could be very long;
• The metadata is now not defined as a dictionary but as a list of tuples (the cleanest method I could find to implement without breaking or changing too much of the code), since we need to add multiple instances of the same key for 'License-File':. The multiple uses of this field include all of the licensing-related files I could find in the RECORD file that gets generated and re-checked manually in the source. There is a chance I might have missed a few, so, if you find any, please let me know!
• Added seven new classifiers to the project that I found are relevant enough to be included here, based on PyPI search related to them. If this is better to do as a follow-up PR, I'm happy to put up another.

I'll add additional information and context in a self-review below where I feel more context is needed, please let me know if I should add a few in-line comments in the code, too, for future references. Thank you!

[whitequark]

LGTM

[agriyakhetarpal]

This metadata version bump is backwards compatible. Please see https://peps.python.org/pep-0639/#backwards-compatibility for more. I tested recent versions of pip and uv, and they installed a wheel I generated for my M-series device without hiccups. I'll need to see if compliance with PyPI uploads is working, though, that's more important to figure out.

[agriyakhetarpal]

https://endoflife.date/python states that security releases for Python 3.7 have ended. Now that 3.13 is just around the corner, maybe we should update to a minimum of 3.8 (either here or as a separate PR). Please let me know.

[whitequark]

I'm aware of the EOL status of Python 3.5 (it was EOL when I wrote this package). I decided that this requirement should be bumped only if the package isn't installable/usable, since there isn't really a cost to keeping it low, and it could help someone using old Python versions.

[agriyakhetarpal]

Sure, makes sense!

[whitequark]

If we do change the launcher in such a way it stops working on earlier Python versions, we should support the last non-EOL version, of course.

zig-pypi/make_wheels.py

Lines 122 to 127 in f1cd7a9

	import os, sys
	argv = [os.path.join(os.path.dirname(__file__), "{entry_name}"), *sys.argv[1:]]
	if os.name == 'posix':
	os.execv(argv[0], argv)
	else:
	import subprocess; sys.exit(subprocess.call(argv))

[agriyakhetarpal]

I can't access a Python version that old unless I use actions/setup-python in a CI setup – and I remember that your previous mention in our earlier conversations of one to not become a maintenance burden. So we could leave it until someone asks; I doubt anyone will, though, since those Pythons are really old 😄

[whitequark]

Thanks!

[agriyakhetarpal]

Running twine --strict on a wheel currently fails:

❯ uvx twine check dist/ziglang-0.13.0-py3-none-macosx_12_0_arm64.whl --strict     

Checking dist/ziglang-0.13.0-py3-none-macosx_12_0_arm64.whl: ERROR    InvalidDistribution: Metadata is missing required fields: Name, Version.                                                                          
         Make sure the distribution includes the files where those fields are specified, and is using a supported Metadata-Version: 1.0, 1.1, 1.2, 2.0,    
         2.1, 2.2, 2.3.

I guess this might be because twine hasn't been updated yet, since the PEP was approved just last month, in August 2024. I'll take a deeper look, and if this would take time, maybe we should bump to just version 2.3 for now? 2.2 and 2.3 did not contain too many changes, and none of those are relevant for us here.

[agriyakhetarpal]

Oops, you merged too quickly, maybe! :D I'll open a new PR to fix any changes, though I would request not to upload any missing wheels with this.

[agriyakhetarpal]

Upstream issue: pypa/twine#1146

[agriyakhetarpal]

A fix should get merged soon: pypa/twine#1123

[whitequark]

I would request not to upload any missing wheels with this.

Noted.