Summary

The following code emits a diagnostic while it looks fine:

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

class B[T](A[T]):
    def f(self: "B", a: T) -> T:
        # `B[Unknown]` is not an instance or subclass of `<class 'B'>` in `super(<class 'B'>, B[Unknown])` call (invalid-super-argument) [Ln 9, Col 16]
        return super().f(a)

playground, while pyright accepts this code.

I also tried annotating self with other types:

With specialized instance: playground
With Self type: playground
(Currently the self type example will not pass even with a non-generic too. But that will be fixed once we have implicit self.)

The problem seems to be in the Specilization::has_relation_to method because it returns false.

Version

9d8cba4 2025-06-25