Please consider undeprecating setup_requires

I have run into an issue with the deprecation of setup_requires: the recommended alternative appears to be PEP 517/build-system.requires, but that comes with its own issues:

• apparently it breaks wheels unless you use special options like --no-binary. This breaks very common tools like tox which no longer can install a project if this package is a dependency - also, why would you want to not have wheels? this is wrong, my apologies

• setup_requires isn’t installed when invoking hooks.get_requires_for_build_wheel() as called by pip/pep517. However the new build-system.requires is. In practice this is an issue when putting a Cython project as a build dependency for .pxd imports: a .pxd dep is only actually required when building the wheel (where setup_requires will provide it) but not for basic package analysis (where build-system.requires per design provides it too, setup_requires won't). In practice since “providing it” means building the whole package, as a result obtaining any package metadata is greatly slowed down

• pyproject.tomls build-system.requires is declarative but not exhaustive. the problem with that is that the dependencies are then spread over multiple places, e.g. no longer just requirements.txt parsed by setup.py - which can’t be parsed similarly in the declarative pyproject.toml file with its static build_system.requires

Edit: a lot of this was initially quite misinformed so I corrected the reasons

[McSinyx]

Thanks, that should be officially documented elsewhere, but that’s out of the scope of this issue I guess.

[Hierosme]

For me it type of breakout is not a good news. Like Python 2 to 3, it have take almost 10 years for back to reality. That it not the first time where a PEP is totaly worng.

The PEP in question transform something it have been simple during years by something totaly strange, with nobody it have experience, and no clear documentation.

I not understand that need to break the work of world developper’s.

My point is: Please consider to limit the negative impact of it type a change. I’m not sure maintain a Alias will be the end of the world.

Regards