MyIntEnum.ONE should be passable to functions expecting Literal[1] arguments

Bug Report

This is related but distinct from #19576, #16327, and #17162. It's also not specific to IntEnums, but I use them in the example for clarity. StrEnums as well as enums based on (int, Enum), or (str, Enum), etc.

To Reproduce

import enum
from typing import Literal

type One = Literal[1]
type Two = Literal[2]
type Three = Literal[3]

def option(arg: One | Two | Three) -> None:
    ...

class MyEnum(enum.IntEnum):
    ONE = 1
    TWO = 2
    THREE = 3

option(MyEnum.TWO)  #  error: Argument 1 to "option" has incompatible type "Literal[MyEnum.TWO]"; expected "Literal[1, 2, 3]"  [arg-type]

Expected Behavior

No error reported.

Actual Behavior

The error in the comment in the example is a false positive. This code works fine at runtime.

Your Environment

• Mypy version used: master as of 0d791b29b7ba4e5a9b04c0b6bdba11faf4a186a2
• Python version used: 3.13

まず、提供された Python 3.13 の例を mypy master に対して実行し、MyEnum.TWO に関係する Literal 引数の処理を追跡します。例が非互換な引数のエラーを報告しなくなり、issue で説明されている関連する enum と Literal の動作を維持できれば、修正は完了です。