Improve path-related type hints for setuptools.Extension() and distutils.CCompiler() (#12958)

Co-authored-by: Avasam <samuel.06@hotmail.com>

stubs/setuptools/@tests/test_cases/check_distutils.py

@@ -1,3 +1,31 @@
+from __future__ import annotations
+
 import distutils.command.sdist
+from _typeshed import StrPath
+from os import PathLike
+from pathlib import Path
+
+from setuptools._distutils.ccompiler import CCompiler
 
 c = distutils.command.sdist.sdist
+
+# Test CCompiler().compile with varied sources
+
+compiler = CCompiler()
+
+str_list: list[str] = ["file1.c", "file2.c"]
+compiler.compile(sources=str_list)
+
+path_list: list[Path] = [Path("file1.c"), Path("file2.c")]
+compiler.compile(sources=path_list)
+
+pathlike_list: list[PathLike[str]] = [Path("file1.c"), Path("file2.c")]
+compiler.compile(sources=pathlike_list)
+
+strpath_list: list[StrPath] = [Path("file1.c"), "file2.c"]
+compiler.compile(sources=strpath_list)
+
+# Direct literals should also work
+compiler.compile(sources=["file1.c", "file2.c"])
+compiler.compile(sources=[Path("file1.c"), Path("file2.c")])
+compiler.compile(sources=[Path("file1.c"), "file2.c"])

stubs/setuptools/@tests/test_cases/check_extension.py

@@ -0,0 +1,15 @@
+from __future__ import annotations
+
+from os import PathLike
+from pathlib import Path
+
+from setuptools import Extension
+
+# Dummy extensions
+ext1 = Extension(name="test1", sources=["file1.c", "file2.c"])  # plain list[str] works
+
+path_sources: list[Path] = [Path("file1.c"), Path("file2.c")]
+ext2 = Extension(name="test2", sources=path_sources)  # list of Path(s)
+
+mixed_sources: list[str | PathLike[str]] = [Path("file1.c"), "file2.c"]  # or list[StrPath]
+ext3 = Extension(name="test3", sources=mixed_sources)  # mixed types