(🐞) 1.2 regression invalid error and bad message with Concatenate return value #15086
Description
from typing import Callable, Concatenate, Generic, ParamSpec, TypeVar
R = TypeVar("R")
P = ParamSpec("P")
def f() -> Callable[[Callable[Concatenate[str, P], R]], Callable[P, R]]:
def decorator(fn: Callable[Concatenate[str, P], R], /) -> Callable[P, R]:
...
return decoratorIncompatible return value type (got "Callable[[Callable[[str, **P], R]], Callable[P, R]]", expected "Callable[[Callable[[str, **P], R]], Callable[P, R]]")