False positive for overriding decorated method in an import cycle

[ilevkivskyi]

Consider this test:

[case testCyclicDecoratir]
import b
[file a.py]
import b
import c

class A(b.B):
    @c.deco
    def meth(self) -> int: ...
[file b.py]
import a
import c

class B:
    @c.deco
    def meth(self) -> int: ...
[file c.py]
from typing import TypeVar, Tuple, Callable
T = TypeVar('T')
def deco(f: Callable[..., T]) -> Callable[..., Tuple[T, int]]: ...
[out]

It currently fails with

tmp/a.py:6: error: Signature of "meth" incompatible with supertype "B"

Although it is obviously compatible (it is actually identical). The error goes away if I change the order files are processed in the cycle (by importing a in main).

The reason is that non-trivial decorator needs to be type-checked to find the type in superclass first. A potential solution is to just defer the subclass method node.