`NoReturn` on `__new__` and `__init__` disables accessing `@classmethod`s and `ClassVar`s directly from the class

Bug Report

Annotating __new__(...) -> typing.NoReturn or __init__(...) -> typing.NoReturn causes false positives when accessing @classmethods and typing.ClassVar-annotated attributes.

To Reproduce

from typing import NoReturn, Any, ClassVar

class A:
    attr: ClassVar[str] = ""
    def __init__(cls, *args: Any, **kwargs: Any) -> NoReturn:
        raise RuntimeError
    @classmethod
    def f(cls) -> None:
        pass

class B:
    attr: ClassVar[str] = ""
    @classmethod
    def f(cls) -> None:
        pass

Expected Behavior

No issues on any of the following:

A.f()
A.attr
B.f()
B.attr

Actual Behavior

A.f()  # mypy: "Callable[[VarArg(Any), KwArg(Any)], NoReturn]" has no attribute "f"  [attr-defined]
A.attr  # mypy: "Callable[[VarArg(Any), KwArg(Any)], NoReturn]" has no attribute "attr"  [attr-defined]
B.f()
B.attr

Your Environment

• Mypy version used: 0.990 and master branch of https://mypy-play.net/
• Mypy command-line flags: None
• Mypy configuration options from mypy.ini (and other config files): None
• Python version used: 3.10

Commencez par le reproducteur Python fourni et suivez la manière dont mypy représente les classes dont new ou init renvoie NoReturn. Ajoutez une couverture de régression pour l’accès à classmethod et ClassVar, en vous assurant que A.f(), A.attr, B.f() et B.attr ne produisent aucun problème.