After commenting [1] on the fact that the current datetime module C API [2] is problematic due to its reliance on C level global variables, I discovered that this is actually the outcome of our recommended approach to using capsules to export a C API as function pointers: https://docs.python.org/3/extending/extending.html#providing-a-c-api-for-an-extension-module

So we first need to fix the documentation to propose a reloading friendly way of using capsules in other extension modules, and then we can then propose updating the public datetime C API accordingly (probably by defining new macros that accept the capsule reference as their first argument).

[1] https://bugs.python.org/issue10381#msg309214
[2] https://docs.python.org/3/c-api/datetime.html
[3] https://docs.python.org/3/extending/extending.html#providing-a-c-api-for-an-extension-module