When I define methods ('__or__', '__and__', '__xor__', '__ror__', '__rand__', '__rxor__', '__invert__')
directly in the class inheriting from enum.Flag, these methods are "added" (mro) to the members, however, if the method is defined in the mixin, the methods defined in enum.Flag are added (e.g. Flag.__or__). I would expect methods to be called from mixin.

from enum import Flag


class Mixin:
    def __or__(self, value): ...


class MyFlag(Mixin, Flag):
    pass


class MyFlag2(Flag):
    def __or__(self, value): ...


print(MyFlag.__or__.__qualname__)  # Flag.__or__, I would expect Mixin.__or__
print(MyFlag2.__or__.__qualname__)  # MyFlag2.__or__ - GOOD

Linked PRs

• gh-121291: Respect mixin bitwise-operator overrides on Flag subclasses #155862