October 31st deadline for fetch_build_egg - what exactly will happen?

Packaging
1

Hi!

My organization has a lot of packages emitting the _DeprecatedInstaller warning. They use setup_requires to get a setuptools plugin similar to PBR. Pip is apparently choosing to install them with setup.py install.

Clearly the best solution is to go through and add pyproject.toml, but that doesn’t fix our historical versions.

The packages install fine with --use-pep517. So I’m wondering, what is the plan for October 31st…

  1. Will the setuptools _DeprecatedInstaller warning become an error?
  2. Will pip default to --use-pep517 in more cases?
  3. Something else?

If #1 happens without #2, then that will make many package versions uninstallable for us. But if they both happen in combination, that’s fine.

Thank you to the packaging team, I appreciate your work getting this all to work in a truly wild variety of situations.

-Thomas

2

I can’t answer what setuptools is planning to do, but I can tell you that pip plans to use PEP 517 for all builds in the next release, pip 25.3, which is scheduled to be released late October 2025.

However this will depend on volunteer maintainer time, and so it is within the realm of possibility it could get pushed to a subsequent release.

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