Enum exhaustiveness checks fail with @enum.member-decorated members #18722

from enum import Enum, member
from typing import assert_never

class E1(Enum):
    C = 1

def check_1(e: E1) -> None:
    match e:
        case E1.C:
            pass
        case other:
            assert_never(other)  # OK

    if e is E1.C:
        pass
    else:
        assert_never(e)  # OK


class E2(Enum):
    @member
    def C() -> None: ...  # E: Method must have at least one argument. Did you forget the "self" argument?  [misc]

def check_2(e: E2) -> None:
    match e:
        case E2.C:
            pass
        case other:
            assert_never(other)  # E: Argument 1 to "assert_never" has incompatible type "E2"; expected "Never"  [arg-type]

    if e is E2.C:
        pass
    else:
        assert_never(e)  # E: Argument 1 to "assert_never" has incompatible type "<subclass of "enum.member[Callable[[], None]]" and "__main__.E2">"; expected "Never"  [arg-type]