Allow ABCMeta in PyType_FromMetaclass

Feature or enhancement

Proposal:

Currently Python 3.14 will deny any metaclass that implements tp_new, which ABCMeta does.

My suggestion is to add special logic in PyType_FromMetaclass that if the metaclass is ABCMeta or a subtype uses its tp_new instead of custom that it adds the abstract flag, and calls the method that calculates abstractmethods attribute.

Currently there is logic in CPython to mark native methods as abstract.

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

No response

首先定位 PyType_FromMetaclass 以及将原生方法标记为抽象方法的现有逻辑。跟踪 ABCMeta 及其子类型如何处理 tp_new，以及如何计算 abstractmethods。完成的标准是接受与 ABCMeta 兼容的元类，同时保留抽象标志和计算行为。