problem

class A: def __eq__(self, o: object, /) -> bool: return self is o reveal_type(A().__hash__) # def () -> builtins.int

https://mypy-play.net/?mypy=latest&python=3.13&flags=strict%2Clocal-partial-types&gist=2b23624b1df772175b70c08e36a6e912

yet

>>> class A: ... def __eq__(self, o: object, /) -> bool: ... return self is o ... >>> type(A.__hash__) <class 'NoneType'>

solution

iff. class A, and only class A (i.e. excluding any base classes)

• implements __eq__, and
• does not implement __hash__

infer A.__hash__: ClassVar[None]