No error emitted with `ParamSpec` on a signature that is a union of callables with `ParamSpec` and without `ParamSpec`

Bug Report

See discussion on pyright at : https://github.com/microsoft/pyright/issues/6796

mypy doesn't emit an error, but pyright does, and it isn't clear which is correct!
We're trying to support something with pandas with DataFrame.pipe() that allows functions with any kind of argument list to be passed. But the function can be specified in one of two ways:

• as a function
• as a tuple, with the tuple being the name of an argument and the function

To Reproduce

from typing import Callable, Concatenate
from typing_extensions import ParamSpec

P = ParamSpec("P")


def func1(x: int):
    print(x)


def func2(x: int, /, y: str):
    print(x)


def accept_func(
    f: Callable[Concatenate[int, P], None] | tuple[int, Callable[..., None]],
    *args: P.args,
    **kwargs: P.kwargs,
) -> None:
    if isinstance(f, tuple):
        if args:
            f[1](f[0], args)
        else:
            f[1](f[0])
    else:
        f(5)


accept_func(func1)
accept_func((2, func1))
accept_func((3, func2), "abc")

Expected Behavior

pyright reports:

 pspec.py:26:9 - error: Arguments for ParamSpec "P@accept_func" are missing (reportGeneralTypeIssues)
 pspec.py:29:1 - error: Arguments for ParamSpec "P@accept_func" are missing (reportGeneralTypeIssues)
 pspec.py:30:25 - error: Arguments for ParamSpec "P@accept_func" are missing (reportGeneralTypeIssues)

pyright authors think mypy should report all 3. See discussion in linked issue.

Actual Behavior

mypy reports:

Success: no issues found in 1 source file

Your Environment

• Mypy version used: 1.7.1
• Mypy command-line flags: None
• Mypy configuration options from mypy.ini (and other config files): None
• Python version used: 3.11.3

Inizia con la riproduzione fornita di ParamSpec e Callable-union, quindi leggi la discussione collegata di pyright per comprendere le interpretazioni concorrenti. Eseguila con mypy nell’ambiente indicato e traccia il comportamento di controllo di ParamSpec; il lavoro è concluso quando la gestione è stata risolta e coperta da un test di regressione oppure documentata come intenzionale.