> PTHREAD_KEY_T_IS_COMPATIBLE_WITH_INT is defined on most (pthread) platforms, no?

> I propose to cast pthread_key_create() result to int, but only define PyThread_create_key() in Python/thread_pthread.h if PTHREAD_KEY_T_IS_COMPATIBLE_WITH_INT is defined.

I don't think that's a good idea. Changing API, even for platforms that aren't officially supported, sounds very harsh this late in the release cycle.

But! I suppose we could fix the bug only for platforms with PTHREAD_KEY_T_IS_COMPATIBLE_WITH_INT. Other platforms would keep the current implementation -- they'd still have the bug, but the API would stay unchanged.