An enum attribute with a private (mangled) name should not be considered an enum member

[erictraut]

This is based on a bug report that someone just filed against pyright. Mypy appears to have the same bug.

The enum documentation indicates that an attribute with a private (mangled) name is not treated as an enum member.

from enum import Enum

class MyEnum(Enum):
    A = 1
    B = 2
    C = 3

    __my_dict = {A: "ham", B: "spam", C: "egg"}

# Should reveal `dict[MyEnum, str]`, not `Literal[MyEnum.__my_dict]`
reveal_type(MyEnum.__my_dict)