bpo-32604: Add the _xxsubinterpreters extension module under Windows. by ericsnowcurrently · Pull Request #5436 · python/cpython
I removed the Windows extension module metadata from #1748 and am addressing it separately here.
As it currently stands, this PR is still running into link-time problems. I suspect my problem is with Py_BUILD_CORE. When I don't set it I don't get the symbols out of Include/internal. When I do set it I end up missing stuff from python37.lib at link time. I tried adding a "Link" directive right below where I set Py_BUILD_CORE, but that did not help.