Faulty type narrowing with value restrictions

Bug Report

When passing an empty list directly into a value restricted generic function, the inferred return type can end up being too narrow.

To Reproduce

from typing import TypeVar


TV = TypeVar("TV", str, int)


def foo(x: list[TV]) -> list[TV]:
    return x
    

# Should be: builtins.list[builtins.str] | builtins.list[builtins.int]
reveal_type(foo([]))  # "builtins.list[builtins.str]"

https://mypy-play.net/?mypy=latest&python=3.10&flags=strict&gist=129ba2fed0c6ba1a861149f944db3420

Expected Behavior

I would expect the revealed type to either be builtins.list[builtins.str] | builtins.list[builtins.int].

Alternatively, having this result in an error of some sort would be fine. As a reference, when assigning the empty list first, it becomes a list[Any] instead of a list[<nothing>]. This results in the revealed type being list[Any], but also an error along the lines of Need type annotation for "l" (hint: "l: List[<type>] = ...").

Actual Behavior

The revealed type was builtins.list[builtins.str]

Comienza con el caso reproducible de mypy-play enlazado y rastrea el tratamiento de los argumentos de listas vacías durante la inferencia de un TypeVar restringido por valores. Compara el tipo inferido con la unión esperada y con el comportamiento de diagnóstico aceptable descrito en el issue. Se considera terminado cuando el ejemplo ya no se restringe incorrectamente a list[str].