Forward reference to decorated class method has type Any

[JukkaL]

In the program below, the type inferred for cls.g in A.f is Any, even though it should be def (x: builtins.str):

from typing import TypeVar, Callable

T = TypeVar('T')
def dec() -> Callable[[T], T]: pass

class A:
    @classmethod
    def f(cls) -> None:
        reveal_type(cls.g)  # Any  <-- unexpected

    @classmethod
    @dec()
    def g(cls, x: str) -> None:
        pass

    @classmethod
    def h(cls) -> None:
        reveal_type(cls.g)  # def (x: builtins.str)  <-- ok

This works correctly when the decorated method is accessed using an instance type (such as self).

In fine-grained incremental mode the types can be more precise, which can result in additional errors in fine-grained incremental mode.