[setuptools] setuptools.setup Complete partially Unknown method and fix Command type variance issue (#15161)

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

@@ -0,0 +1,23 @@
+from typing_extensions import assert_type
+
+from setuptools import Command as setuptools_Command, Distribution as setuptools_Distribution, setup
+from setuptools._distutils.cmd import Command as distutils_Command
+from setuptools._distutils.dist import Distribution as distutils_Distribution
+
+# Ensure that any distutils-derived classes are usable w/o type variance issues
+assert_type(
+    setup(
+        cmdclass=dict[str, type[distutils_Command]](),
+        command_obj=dict[str, distutils_Command](),
+        distclass=distutils_Distribution,
+    ),
+    distutils_Distribution,
+)
+assert_type(
+    setup(
+        cmdclass=dict[str, type[setuptools_Command]](),
+        command_obj=dict[str, setuptools_Command](),
+        distclass=setuptools_Distribution,
+    ),
+    setuptools_Distribution,
+)