Inferred return type of a decorated function is incorrect

[michitaro]

Inferred return type of a decorated function is incorrect.
(That is the one for the function without the decoration.)

Environment data

• Language Server version: 0.5.10.0
• OS and version: macOS 10.15
• Python version (& distribution if applicable, e.g. Anaconda): Anaconda3 Python 3.7.3

Expected behaviour

• The LS infers a correct return type of a decorated function.

Actual behaviour

• The LS infers a return type of a decorated function as if the function is not decorated.

Logs

N/A

Code Snippet / Additional lnformation

from typing import Any, Callable


def stringify(f: Callable[..., Any]) -> Callable[..., str]:
    def wrapper(*args) -> str:
        return str(f(*args))
    return wrapper

@stringify
def one() -> int:
    return 1

value = one() # inferred type of `value` by the LS is `int`,
              # but it should be `str`

print(type(value))
# <class 'str'>

[MikhailArkhipov]

True, currently analysis does not look into decorators in order to find out possible return type. Also, Callable is not currently handled. #1115 and #535