False positive for function that takes a `Callable` as a parameter and returns a `Tuple` of `Union`

Bug Report

The following code

from typing import (
    Callable,
    TypeVar,
    Union,
    Tuple,
)


T = TypeVar("T")


def test(pred: Callable[[T], bool]) -> Tuple[Union[T, int]]:
    return (1,)


def main(pred: Callable[[T], bool]) -> None:
    (val,) = test(pred)  # the error appears here


def f(x: int) -> bool:
    return x > 1


main(f)

triggers the mypy error

Argument 1 to "test" has incompatible type "Callable[[T], bool]"; expected "Callable[[Union[T, int]], bool]"

at the line that I marked with a comment. I believe this is a bug as this correction makes no sense to me (of couse, I could be wrong).
I'm aware that this code is meaningless, but it's the simplest sample I was able to produce that causes the error.
From the tests that I've done it seems to depend both on the type variable being used and on the function test returning a Tuple[Union[...]]. So if I replace T with a regular type of if I return either Union[T, int] or Tuple[int] instead of Tuple[Union[T, int]] the error goes away. It also disappears by not upacking the the result of test(pred).

To Reproduce

Take the code above and check it with mypy. That's it.

Expected Behavior

No error triggered.

Actual Behavior

Mypy detects the error reported above.

Your Environment

• Mypy version used: 0.812
• Mypy command-line flags: --ignore-missing-imports --follow-imports=silent --show-column-numbers
• Mypy configuration options from mypy.ini (and other config files): none
• Python version used: 3.9.2
• Operating system and version: Linux x64

まず、提供された Python スニペットを mypy 0.812 で実行し、アンパック呼び出しでのエラーを確認します。Callable、Tuple、Union の型変数の推論を追跡します。完了とは、報告された false-positive エラーなしで再現コードの型チェックが通り、回帰テストのカバレッジによってこの動作が保護されることを意味します。