a way to refer to result type of an overloaded function

I am looking for a way to refer to result type of an overloaded function.

To illustrate:

import typing as tp


T = tp.TypeVar("T")


@tp.overload
def gf1(i: int, j: tp.Any) -> str:
    ...


@tp.overload
def gf1(i: tp.Iterable[T], j: bool) -> tp.Dict[T, T]:
    ...


def gf1(i: tp.Union[int, tp.Iterable[T]], j: tp.Any) -> tp.Union[str, tp.Dict[T, T]]:
    pass


gf1.resultType = lambda *a: None



class C(tp.Generic[T]):
    def f1(self) -> gf1.resultType(T, bool):
        pass

    def f2(self) -> gf1.resultType(tp.List[T], bool):
        pass


if not tp.TYPE_CHECKING:
    def reveal_type(x):
        pass


# outputs: builtins.str
reveal_type(gf1(1, True))
# wanted: builtins.str
reveal_type(C[int]().f1())

# outputs: builtins.dict[builtins.int*, builtins.int*]
reveal_type(gf1([1], True))
# wanted: builtins.dict[builtins.int*, builtins.int*]
reveal_type(C[int]().f2())

The f.resultOf syntax is, of course, tentative.

Issue #623 seems to suggest that this may be achievable with a clever use of of Protocol but I just cannot twist my head around that.

Upon request I can elaborate on my specific use case for this but I believe it would suffice to say that in real code gf1.resultType would be used multiple times. Specific argument types for gf1 were chosen arbitrarily for the sake of example.

Not sure whether #548 is anyhow related.

从这个 issue 中的重载函数示例开始，并查看 issues #623 和 #548 中的相关讨论。没有确定任何 repository 文件或测试；只有在就引用重载函数的结果类型达成一个约定且可实现的范围后，才能视为完成。