Allow `float("inf")` and `float("-inf")` in literals

I have been frequently using positive and negative infinity as default values for values that should otherwise be ints. Because of Python's duck typing this is a convenient pattern that sometimes allows reducing some special-casing logic.

def less_than(value: int, limit: int | None) -> bool:
    if limit is None:
        return True
    return value < limit

vs

def less_than(value: int, limit: int | Literal[float("inf")]) -> bool:
    return value < limit

Would it be feasible to special-case the expressions float("inf") and float("-inf") and make type-checkers regard them as literal values, even though they aren't strictly speaking language-level literals?

For posterity, PEP 586 mentions this with:

Representing Literals of infinity or NaN in a clean way is tricky; real-world APIs are unlikely to vary their behavior based on a float parameter.

So I guess what I'm asking here is: am I an odd duckling or could it be worth considering +/- infinity as legal values in literal types?

首先阅读 PEP 586 中关于非法 Literal 参数的讨论，以及此 issue 中的 21 条评论。确定 typing 社区是否已经就将 float("inf") 和 float("-inf") 作为字面量值处理达成决定；只有在已有一致同意的规范并确定了需要对 type-checker 进行的更改时，才能算完成，而该 issue 并未提供这些内容。