Leftover code in sysconfig.expand_makefile_vars

[picnixz]

Bug report

Bug description:

I think there is some leftover code in sysconfig.expand_makefile_vars (4a53a39):

cpython/Lib/sysconfig/__init__.py

Lines 727 to 734 in 4dade05

	while True:
	m = re.search(_findvar1_rx, s) or re.search(_findvar2_rx, s)
	if m:
	(beg, end) = m.span()
	s = s[0:beg] + vars.get(m.group(1)) + s[end:]
	else:
	break
	return s

The _findvar1_rx and _findvar2_rx variables are not declared at all (they were moved to sysconfig/__main__.py). Since the function is publicly named (but not exported nor documented), I prefer backporting the changes of #110785, namely re-use the patterns as is.

cc @FFY00

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-128978: Fix a NameError in sysconfig.expand_makefile_vars #128979
• [3.13] gh-128978: Fix a NameError in sysconfig.expand_makefile_vars (GH-128979) #129065
• [3.12] gh-128978: Fix a NameError in sysconfig.expand_makefile_vars (GH-128979) #129066 (not needed)

[vstinner]

Is it time to deprecate this untested and undocumented function?

[picnixz]

Probably. It was introduced in 2000 and fixed in 2016 but nothing else: https://github.com/search?q=repo%3Apython%2Fcpython+expand_makefile_vars&type=commits.

So how about I first fix the NameError, then in a follow-up PR, I deprecate the function (so that I can have a dedicated What's New entry)?

[picnixz]

Also, distutils or graalpython seems to provide a (working) bundled version of that function so I don't think we need to worry about?

[vstinner]

So how about I first fix the NameError, then in a follow-up PR, I deprecate the function (so that I can have a dedicated What's New entry)?

Sure, if we decide to deprecate the function, it should be done in separated change.

[FFY00]

Is it time to deprecate this untested and undocumented function?

It's sort-of tested through sysconfig.get_paths. Edit: It's not. sysconfig.get_paths uses sysconfig._expand_vars.

I am up to rename it to _expand_makefile_vars, and deprecate expand_makefile_vars. Searching Github for usages of this function (https://github.com/search?q=expand_makefile_vars%20language:Python&type=code&l=Python), I only very few unique usages of it in the wild. And for folks that still need it, as a quick fix, they can add a dependency on setuptools and use distutils.sysconfig.expand_makefile_vars instead.