Hi distutils-sig,
There's a bit of discussion going on at http://bugs.python.org/issue22980 about extending SO tags to include bitness values, and I took the opportunity to look into adding platform tags for .pyd files on Windows.
There's a patch up there, but I'm interested in any thoughts or concerns people may have that I haven't considered. Distribution is likely to be most affected, and I figured distutils-sig is most likely to have people with strong opinions on the subject anyway, so I'm posting here :)
Basically, importlib.machinery.EXTENSION_SUFFIXES is all that changes. It'll go from [".pyd"] to [".cp35-win32.pyd", ".cp3-win32.pyd", ".pyd"] (where "win32" may also be "win_amd64", "win_ia64" or "win_arm", which are the platforms that have #ifdefs in pyconfig.h).
By default, distutils' build_ext will use the first extension, and so builds will get the ".cp35-win32.pyd" tag. You can only get the ".cp3-win32.pyd" tag (for stable ABI) by customizing the build process - I don't think that's an unreasonable expectation, especially on Windows.
I can see potential for making more generic installable packages with this change, though I'm not pushing for that. The big win is when you're building and testing 32-bit and 64-bit pyds through an IDE - it greatly simplifies how the output directories and search paths are organized.
Thoughts/concerns?
Cheers, Steve