[BUG] Setuptools 69.0.0 breaks Astropy's setup

[neutrinoceros]

setuptools version

setuptools==69.0.0

Python version

3.12

OS

Ubuntu

Additional environment information

No response

Description

About 15h ago, Astropy's CI started failing to build with

ImportError: cannot import name 'newer_group' from 'setuptools.dep_util'

This seems to correspond to an intentional change in setuptools 69.
Nonetheless, from reading the PR that introduced the change (#4069), I'm not sure that this was supposed to break immediately. Was this intended ?

Expected behavior

a deprecation warning instead of a hard error ?

How to Reproduce

$ python -c "from setuptools.dep_util import newer_group"

Output

Traceback (most recent call last):
  File "<string>", line 1, in <module>
ImportError: cannot import name 'newer_group' from 'setuptools.dep_util' (/private/tmp/venv/lib/python3.12/site-packages/setuptools/dep_util.py)

[abravalheri]

I see, astropy was using a function that was imported by setuptools.dep_util in order to implement another function.

I think I can prepare a fix quickly...

[abravalheri]

Hi @neutrinoceros, could you please check if #4127 works for you?

You can install that version of setuptools with:

python -m venv .venv
.venv/bin/python -m pip install -U pip wheel
.venv/bin/python -m pip install https://github.com/abravalheri/setuptools/archive/refs/heads/issue-4126.zip

+any other build dependencies.

Then you can run .venv/bin/python -m pip install . --no-build-isolation or .venv/bin/python -m build --no-isolation to test if it works for you.

[neutrinoceros]

@abravalheri I confirm that #4127 works for us, thank you !
For the record, I was also able to resolve the incompatibility on Astropy's side astropy/astropy#15634, but having a fix in setuptools itself will also fix building existing releases, so that's still desirable for us.

[abravalheri]

Thank you very much for confirming.
I will wait for the CI and cut a release, it might take about 1h (maybe a bit more) until it is properly published on PyPI.