Overly broad type inference when using zip(*x) to tranpose 2d iterable

Description:

When transposing a 2d iterable x: Iterable[Iterable[T]] using zip(*x), I've noticed typeshed's type annotations result in the return type being inferred as zip[tuple[Any, ...]] rather than the expected zip[tuple[T, ...]]. It would be nice if builtins.py^1 had an overload for this use case.

Expected behavior

When x has type Iterable[Iterable[T]], the expression zip(*x) should be inferred as zip[tuple[T, ...]], preserving the element type information through the transpose operation.

Actual behavior

The expression zip(*x) is inferred as zip[tuple[Any, ...]].

Possible solution

Add the following overloads to zip:

Pre 3.10:

        @overload
        def __new__(
            cls,
            *iterables: Iterable[_T1],
        ) -> zip[tuple[_T1, ...]]: ...

3.10 or later:

        @overload
        def __new__(
            cls,
            *iterables: Iterable[_T1],
            *,
            strict: bool = ...
        ) -> zip[tuple[_T1, ...]]: ...

While I have seen zip(*x) in the wild, I have not seen zip(a,b,c,*x) in any environment before, so I don't think it's necessary to write an overload for that edge case.

Mở stdlib/builtins.pyi tại định nghĩa zip được liên kết và so sánh các overload hiện có với các signature được đề xuất cho trước 3.10 và 3.10+. Xác nhận rằng zip(*x) đối với Iterable[Iterable[T]] được suy luận là zip[tuple[T, ...]] thay vì zip[tuple[Any, ...]], đồng thời vẫn giữ cách xử lý strict.