[BUG] Fail to compile extensions on Windows free-threading non-MSVC

[crusaderky]

setuptools version

setuptools == 80.9.0

Python version

3.13t, 3.14t

OS

Windows

Description

blis uses setuptools to compile Cython extensions with cmake. Due to nuances around the pure-C libraries, it does not use MSVC, but instead it uses new_compiler(plat="nt", compiler="unix").

Compilation fails on 3.13t and 3.14t:

 clang.exe [...] -lpython314 [...]
 LINK : fatal error LNK1181: cannot open input file 'python314.lib'

In some environments which for some reason deploy both python314.lib and python314t.lib, like actions/setup-python, the linking instead succeeds but then the interpreter segfaults on import.

The issue is caused by this code branch, which fails to account for "t" variants of python*.lib:

setuptools/setuptools/_distutils/command/build_ext.py

Lines 772 to 782 in d198e86

	if not isinstance(self.compiler, MSVCCompiler):
	template = "python%d%d"
	if self.debug:
	template = template + '_d'
	pythonlib = template % (
	sys.hexversion >> 24,
	(sys.hexversion >> 16) & 0xFF,
	)
	# don't extend ext.libraries, it may be shared with other
	# extensions, it is a reference to the original list
	return ext.libraries + [pythonlib]

Expected behavior

On 3.14t clang must be passed -lpython314t instead of -lpython314

Workaround

Subclass build_ext and override the method build_ext.get_libraries to make it return ["python314t"] instead of ["python314"].

How to Reproduce

pip install git+https://github.com/explosion/cython-blis.git@9dbe572cef57b394f97b3114a3e28ec04eb3a39e