allow to include license text file in the wheel metadata

[anthrotype]

the official wheel package (used by setuptools' bdist_wheel) has a handy license_files option (defined in setup.cfg [metadata] section) that allows one to list the license file paths to be included in the generated wheel.

https://wheel.readthedocs.io/en/stable/user_guide.html?highlight=license_files#including-license-files-in-the-generated-wheel-file

Some OSS licenses require one to include the license text along with distributed binaries.

I couldn't find a way to achive this when using maturin. Is it possible to add support for this?

thank you for considering.

[messense]

I think you can use the license field defined in PEP 621: https://maturin.rs/metadata.html

[anthrotype]

oh I didn't know that, thanks! Will that copy the full text of the license file to the wheel .dist-info?

[anthrotype]

ok I just tried, I see it copied the full LICENSE text to the METADATA file, not as a separate LICENSE file. That's fine by me. Thank you!

[anthrotype]

actually I'm having issues embedding the full text of the LICENSE file when running on Windows.
When I use license = {file = LICENSE.txt}, the LICENSE.txt full text is copied to the METADATA file as a multi-line RFC5322 string separated by CRLF, but on Windows I get CRLF twice and that breaks parsing the following README section.

E.g. download the dist.zip file from here, and try to run twine check pngquant_cli-2.17.0.post2-py3-none-win32.whl. I get this FAIL error:

Checking /Users/clupo/Downloads/dist (8)/pngquant_cli-2.17.0.post2-py3-none-win32.whl: FAILED
  `long_description` has syntax errors in markup and would not be rendered on PyPI.
    line 1335: Warning: Block quote ends without a blank line; unexpected unindent.

If I do the same for the other non-Windows wheels (e.g. the mac or linux ones in the same archive), it works. They differ only by their line endings.

[messense]

@anthrotype Thanks for the report, I'll look into it soon.

[messense]

@anthrotype Can you try #836 ? Released in v0.12.10-beta.8.

[anthrotype]

thanks! The windows wheels now pass twine check.
However, I noticed that when I upload it to PyPI, it shows the full text of the license under the section named "Meta" at the lower left corner, but it loses all line breaks and formatting, it's like it's on a single very long line of uninterrupted text: e.g.
https://pypi.org/project/pngquant-cli/2.17.1b1/

What the wheel module does (when building a wheel with setup.py bdist_wheel command) is adding the license file as its own separate text file inside .dist-info directory. The name of the license is what the setup.py's license keyword contains, then the LICENSE.txt file contains the actual license full text and is automatically included in the sdist manifest. Then bdst_wheel can be configured (via setup.cfg's license_files) to include the license files in the distribution.

Would it be possible for maturin to distinguish between the license parameter (being the name or short line describing a license) and the license_files pointing to the paths of the files to be added to the wheel dist-info?

[messense]

Notes:

1. https://peps.python.org/pep-0639/#license-file-multiple-use
2. Add License-File field to package metadata pypa/setuptools#2645

[messense]

@anthrotype Opened #837 .