type checking of member assigned with lambda

Bug Report

What this https://github.com/python/mypy/pull/13400 looks like it's supposed to fix is not working here.

To Reproduce

from typing import Callable


class C:
    f: Callable[[int], bool] = staticmethod(lambda x: print(type(x)) or True)


c = C()
c.f(3)


class D:
    f: Callable[[int], bool] = lambda x: print(type(x)) or True


d = D()
d.f(3)

Expected Behavior

The one that works correctly should not have a mypy error.
The one that doesn't work correctly should be found by mypy.

Actual Behavior

The first one, class C, works correctly, but mypy says it's wrong.
output:

<class 'int'>

mypy:
Incompatible types in assignment (expression has type "staticmethod[bool]", variable has type "Callable[[int], bool]") [assignment]

The second one, class D, fails, but mypy doesn't see any problem with it.
output:

Traceback (most recent call last):
  File ...
    d.f(3)
TypeError: <lambda>() takes 1 positional argument but 2 were given

Your Environment

• Mypy version used: 0.990+dev
• Python version used: 3.8

Inizia eseguendo il riproduttore Python 3.8 fornito con la versione di mypy segnalata e confronta le diagnosi per le classi C e D. Traccia la gestione da parte di mypy delle assegnazioni a membri di classe annotati che coinvolgono espressioni lambda e staticmethod; il lavoro è completato quando l'assegnazione valida a C viene accettata, il binding non valido di D viene segnalato e sono presenti test di regressione per entrambi i casi.