(🎁) final class without a __bool__ or __len__ method can never test false #12158
Description
This clashes with truthy-bool error code, which assumes that subtypes won't implement these methods.
from typing import final
@final
class A:
b: int
if A():
print("hi") # no unreachable error
print(A() and "hi")Any instance of A will never have a __bool__ or __len__, method so these condition will always test true.
More real life scenario:
from typing import final
@final
class A:
b: int
a: A | None
r1: int | None = a.b if a else None
r2: int | None = a and a.b # error: Incompatible types in assignment (expression has type "Union[A, None, int]", variable has type "Optional[int]")