@vstinner Are you sure that function was restored? I don't see it in my repo (I see_PyObject_FastCallDict though).

Oh, wait. I was confused between _PyObject_FastCall() and _PyObject_FastCallDict() :-(

I checked each function since I was really confused about these removals and changes.

Removed, private:

• _PyObject_FastCall()
• _PY_FASTCALL_SMALL_STACK: moved to the internal C API

Removed, internal:

• _PyObject_FastCallTstate()
• _PyObject_FastCallDictTstate(): renamed to _PyObject_VectorcallDictTstate()

Kept:

• METH_FASTCALL
• _PyStack_AsDict()

Kept, PEP 590:

• _PyObject_Vectorcall()
• _PyObject_VectorcallMethod()
• _PyVectorcall_Function()
• _PyObject_CallOneArg()
• _PyObject_CallMethodNoArgs()
• _PyObject_CallMethodOneArg()
• _PyObject_FastCallDict()
• _Py_TPFLAGS_HAVE_VECTORCALL

I wrote PRgh-117676 to add again the What's New entry. Even if it's a private function, I prefer to document how to update affected code for this very specific function, since I know that it's used in the wild.