Return type of method is lost/ignored when overriding a method of a generic class

[digulla]

I have the following code and would expect more errors:

class A[T]:
    def f(self, x: T) -> T:
        return x


class E1(A[int]):
    def f(self, x: str) -> str:  # Should be an error: A[int].f is defined to return int plus A[int].f requires x to by of type int
        return x  # No error since it matches the return type defined on E.f.


class E2(A[int]):
    def f(
        self, _: int
    ):  # Method signature (on hover in IDE) should read "...) -> int". Instead if says "...) -> Literal['xxx']" Looks like the type from A.f is lost somewhere
        return "xxx"  # Should be an error: A[int].f requires int here but was str.

As it currently is, this code looks fine in my IDE. Is there a rule which I forgot to enable or is this not supported by ruff?

[MichaReiser]

Ruff is a linter and not a type checker. For type checking, try https://docs.astral.sh/ty/ or https://microsoft.github.io/pyright/#/