Feature or enhancement

The tp_vectorcall slot can be used with static types to define a more efficient implementation of __new__ / __init__. This slot does not have a typedef in typeslots.h, so it cannot currently be set for PyType_FromSpec or read using PyType_GetSlot.

In 3.12 other vectorcall functionality looks set to stabilise, so please consider adding a Py_tp_vectorcall typedef and allow heap types to set / get this member.

Pitch

Adding the ability for tp_vectorcall to be used in the limited API enables extension types to make use of the vectorcall optimisation in more functionality.

Previous discussion

I see in #85784 that tp_vectorcall is deliberately inaccessible with PyType_GetSlot because it is not part of the limited API.

If there is support for this proposal, I am happy to have a first stab at implementation.

Linked PRs

• gh-100554: Add Py_tp_vectorcall slot to set PyTypeObject.tp_vectorcall using the PyType_FromSpec function family. #123332
• gh-100554: Fix formatting of type.rst modifications #124066