advice for maintainers on dropping universal=1 wheels

[graingert]

There should be some advice on what to do about universal wheels when dropping support for python versions in this guide: https://packaging.python.org/guides/dropping-older-python-versions/

eg, should this:

# setup.cfg
[bdist_wheel]
universal=1

be removed?

[webknjaz]

Yes! It's a great idea! I keep having universal=1 in some places because it never occured to me that it should be changed. Earlier today @gaborbernat pointed out to me that this is wrong and causes the wheels to be py2.py3. I somehow didn't realize this.

So I was about to file an issue about it when I found this one :)

The docs change should point out that the maintainers should be mindful of what their wheel tags are compared to what's written in the Requires-Python fields in metadata.

It also seems like a good idea to improve the linting side of the problem in the ecosystem: pypa/twine#739.

P.S. I tested that projects having such metadata mismatches are harmless (if they don't have a hard conflict in that metadata) and pip seems to do the right thing but it's still a good idea to keep it in sync.

[hugovk]

Yep, comparing wheel filenames created with and without the flag:

pyflakes-2.2.0-py2.py3-none-any.whl
pyflakes-2.2.0-py3-none-any.whl

Their contents are identical, except for pyflakes-2.2.0.dist-info/WHEEL (and RECORD's hash of this file):

Wheel-Version: 1.0
Generator: bdist_wheel (0.36.0)
Root-Is-Purelib: true
Tag: py2-none-any
Tag: py3-none-any

Wheel-Version: 1.0
Generator: bdist_wheel (0.36.0)
Root-Is-Purelib: true
Tag: py3-none-any

[webknjaz]

Here you go #858.