"wheel convert" depends on setuptools

[SpecLad]

Since 0de0c1a, wheel no longer declares a runtime dependency on setuptools. However, the convert command still needs setuptools to work. (Never mind this part, there was never a runtime dependency to start with.)

wheel doesn't declare a runtime dependency on setuptools, but the convert command needs it to work. Here's what happens when setuptools is not installed:

> .\venv\Scripts\wheel.exe convert
Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File ".\venv\Scripts\wheel.exe\__main__.py", line 7, in <module>
  File ".\venv\Lib\site-packages\wheel\cli\__init__.py", line 91, in main
    args.func(args)
  File ".\venv\Lib\site-packages\wheel\cli\__init__.py", line 29, in convert_f
    from .convert import convert
  File ".\venv\Lib\site-packages\wheel\cli\convert.py", line 10, in <module>
    from ..bdist_wheel import bdist_wheel
  File ".\venv\Lib\site-packages\wheel\bdist_wheel.py", line 24, in <module>
    import pkg_resources
ModuleNotFoundError: No module named 'pkg_resources'

[henryiii]

It also contains the somewhat useless extra lines (AFAICT?):

try:
    from setuptools import Distribution
except ImportError:
    from distutils.dist import Distribution

Besides distutils going away, from ..bdist_wheel import bdist_wheel right above requires setuptools (or pkg_resources in the current version, same difference)

This is literally the only usage of raw distutils, too. :)

[henryiii]

Oh, convert only converts eggs to wheels? Are there still eggs around to convert? Looks like all the other commands are fine.

[agronholm]

It converts both .egg and .msi to wheels. I don't know if it's used anymore, since the tool doesn't exactly phone home to report statistics.

[henryiii]

A temporary workaround would be to keep the runtime dependency on setuptools for now, and deprecate it. A second possibility would be to add an extra, like [convert], that would add the setuptools dependency. The ideal solution, removing the requirement on setuptools for this command, sounds tricky since I'm assuming eggs and msi conversion will likely touch stuff in setuptools. Though I haven't investigated that much.

[agronholm]

My quick assessment is that they don't really need setuptools since all they do is convert the metadata and repackage the files.

[nanonyme]

I'm not really sure if it would be a problem if this runtime depended on setuptools. Depends on whether pip dep resolver regards it a cycle or not. I think setuptools has some bootstrap magic to discover itself from source tree.

[nanonyme]

This is a blocker for release with flit, right?

[henryiii]

Regardless of resolving, it would be bad if wheel had a public API (#472) that was intended to be used by tools other than setuptools, but still pulled in setuptools. That's a longer term issue, though, which is why I suggested the temporary workaround. I'm a fan of smaller but more frequent changes over a rare "break everyone" release. :) Though, now that you mention it, it might be an issue if setuptools requires wheel, which then gets installed, and therefore pulls it's dependencies, which include setuptools... Yeah, that might be a problem. Runtime dep on setuptools might truly be not an option, even short term.

It doesn't need to be bootstrap magic, self-builds are built into PEP 517. Flit-core builds itself that way.

It would be great, though, if this could be solved properly without setuptools!

[SpecLad]

FWIW, I don't think convert functionality is needed in the API. It seems like a pretty niche command, and it'll only become less and less relevant as time goes on.

[nanonyme]

@henryiii indeed wheel is a build dependency of setuptools.

[agronholm]

Given how nobody has complained about it requiring setuptools but without wheel declaring it, it seems like it's not getting a lot of use. I'll probably just drop it in the publicapi branch.

[nanonyme]

I think this may be partially explained by abundant usage of pkg_resources from setuptools by basically everyone which is now getting replaced by importlib.resources. It's possible setuptools has been widely available on platforms where wheel convert has been used but this may stop being the case.

[henryiii]

But if it that is the case, it's not a problem of the flit conversion, and is just as present in the current release. :)

[nanonyme]

Yeah, I think seems probable that it's a side-effect of something that the stable release didn't fail for @SpecLad