mypy doesn't understand `@abc.abstractmethod` on `__getattr__`

[hotpxl]

Bug Report

mypy doesn't understand

    @abc.abstractmethod
    def __getattr__(self, name:str) -> Any:

and complains about missing attributes

To Reproduce

Run mypy on:

import abc
from typing import *

class CC(abc.ABC):
    @abc.abstractmethod
    def __getattr__(self, name:str) -> Any:
        ...

def foo(c: CC) -> None:
    print(c.hello)

Expected Behavior

mypy shouldn't complain about attribute "hello" because I've overridden __getattr__. mypy exhibits the correct behavior when the @abc.abstractmethod decorator is removed.

Actual Behavior

mypy complains that main.py:11: error: "CC" has no attribute "hello". But if I comment out @abc.abstractmethod mypy will not complain.

Your Environment

• Mypy version used: mypy 0.820+dev.8bc1115a7469ac4702d29da87acf5831c696d007 (just pip installed from git)
• Mypy command-line flags: mypy main.py
• Mypy configuration options from mypy.ini (and other config files): None
• Python version used: 3.7.3
• Operating system and version: Debian GNU/Linux 10

[finite-state-machine]

This is also true for __getattribute__, and any decorator.

For example,

from typing import (
        Any,
        Callable,
        TypeVar,
        )


T = TypeVar('T', bound=Callable[..., Any])


def labeled(function: T) -> T:
    function.__labeled__ = True # type: ignore[attr-defined]
    return function


class One:
    @labeled
    def __getattribute__(self, _: str) -> str:
        return "hello"


def function() -> None:

    one = One()
    print(one.foo) # error: "One" has no attribute "foo" [attr-defined]