(🐞) `type.__call__` not checked properly

class A:
    def __init__(self, x: int):
        print(x)

A.__call__("a")  # no error
A("a")  # Argument 1 to "A" has incompatible type "str"; expected "int"  [arg-type]

The typing spec says:

At runtime, a call to a class’ constructor typically results in the invocation of three methods in the following order:

1. The __call__ method of the metaclass (which is typically supplied by the type class but can be overridden by a custom metaclass and which is responsible for calling the next two methods)

So mypy is checking that usages of the call syntax (()) are conforming to the constructor type, but the functionally identical call attribute __call__. This is against the spec, which specifies that type checkers should mirror the behavior that __call__ will invoke __new__ and __init__

Inizia esaminando come mypy gestisce le chiamate al costruttore e le chiamate tramite attributo a type.__call__, usando l’esempio nell’issue come riproduzione. Segui come viene verificato A("a") rispetto a A.__call__("a"), quindi aggiungi una copertura che dimostri che entrambe le forme impongono il tipo dell’argomento del costruttore.