METH_FASTCALL is documented as part of the stable API since Python 3.10.

The accompanying function pointer typedefs_PyCFunctionFast and_PyCFunctionFastWithKeywords have leading underscore names, which I understand to hint at these being private / internal APIs.

I think this is potentially an oversight and these function pointer typedefs should have new public namesPyCFunctionFast andPyCFunctionFastWithKeywords?

Linked PRs

• gh-114626: add PyCFunctionFast and PyCFunctionFastWithKeywords #114627
• gh-114626: Add again _PyCFunctionFastWithKeywords name #115561