Behaviour change in py312 for protocols with non-callable members and custom __subclasshook__ methods #105974
Description
Bug report
On Python 3.11:
>>> from typing import * >>> @runtime_checkable ... class Foo(Protocol): ... x = 1 ... @classmethod ... def __subclasshook__(cls, other): ... return hasattr(other, 'x') ... >>> issubclass(object, Foo) FalseOn Python 3.12:
>>> from typing import * >>> @runtime_checkable ... class Foo(Protocol): ... x = 1 ... @classmethod ... def __subclasshook__(cls, other): ... return hsattr(cls, 'x') ... >>> issubclass(object, Foo) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "C:\Users\alexw\coding\cpython\Lib\typing.py", line 1829, in __subclasscheck__ raise TypeError( TypeError: Protocols with non-method members don't support issubclass()I think I prefer the Python 3.11 behaviour here, since the whole point of allowing protocols to define custom __subclasshook__ methods is so that users can customise how issubclass() works on user-defined protocols.