Summary

In the following snippet, the return type of wrap falls back to Wrapper[Any | None]. Note that this only happens if wrap itself is generic. When the (dummy) generic context [S] is removed, the return type is Wrapper[Recursive], as expected:

type Recursive = Recursive | None

class Wrapper[T]: ...

class C[T]:
    @staticmethod
    def wrap[S]() -> Wrapper[T]:
        return Wrapper()

reveal_type(C[Recursive].wrap())  # Wrapper[Any | None]

https://play.ty.dev/14d6e89f-8f51-4322-a862-c14799c67e9a

Version

current main (25853e237)