Deprecate `sysconfig.expand_makefile_vars`

[picnixz]

Feature or enhancement

Proposal:

Per #128978, the function was not working (since 3.13 after 4a53a39) because of a NameError. There are very few occurrences of that function: https://github.com/search?q=expand_makefile_vars+language%3APython&type=code&l=Python and most of them are actually bundled (and working) versions of that function using distutils.sysconfig.expand_makefile_vars instead of sysconfig.expand_makefile_vars.

Since distutils was removed in Python 3.12, users will need to access sysconfig.expand_makefile_vars directly if they use it (and if the function is called!). Now, AFAIK, there are some usages in the wild (e.g., https://github.com/ncbi/ncbi-cxx-toolkit-public/blob/52b6b3c2cea0af8553b026f84cb697afb16ecb64/src/dbapi/lang_bind/python/setup.py#L66) that could hit it at runtime, so if they decide to drop distutils support for whatever reason, and use our sysconfig, they would be a bit annoyed =/

So we can either decide to deprecate it (since it's not documented nor tested actually), or we can document it and properly test it. It's easy to deprecate it but it would add some burden on downstream users, so maybe we can just test it and document it?

cc @vstinner

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• GH-129064: deprecate sysconfig.expand_makefile_vars #129082
• GH-129064: Fix RST markup for the NEWS and What's New entries #129131

[tomasr8]

Seems like a best-case scenario for deprecation given that the function was broken for all this time and nobody (apparently?) noticed

[picnixz]

Ok, my bad but it was only broken in 3.13+. I thought it was 3.12 but I misread the change history. So 3.12 is working, but 3.13 and 3.14 are broken.

[FFY00]

Cross-posting from the duplicated issue I open in GH-129075.

This function has been broken since v3.13.0a1 (see GH-128978), and nobody noticed. It was originally meant to posteriorly expand the values from sysconfig.get_paths(..., expand=False), which achieves the same as passing a custom vars argument to sysconfig.get_paths, a function that is actually tested.

[picnixz]

Considering it has been decided to be deprecated, I'm going to close this issue. Thanks for the PR by the way!

[vstinner]

The documentation is not rendered properly:

The ~sysconfig.expand_makefile_vars function has been deprecated ...

I'm talking about the ~ character.

[picnixz]

This character is not needed actually (since there is no documentation, we can decide not to use :func: as well). Reopening until this has been fixed (just to remember).