Within Annotated[T, x], type errors in x are completely ignored

Bug Report

mypy ignores the x expression in Annotated[T, x] without type-checking it. Although x has no effect on the typing interpretation of T, the expression x is still code that’s going to be executed at runtime*, so mypy should type-check x (as a separate object) before ignoring it.

(* Although it might not be executed immediately if from __future__ import annotations is in effect, it will be executed when typing.get_type_hints is used, so it’s still important for mypy to check it.)

An example of a real subtle bug that was missed because of this is zulip/zulip#26710.

To Reproduce

from typing import Annotated

def f(p: Annotated[int, 2 + "oops"]) -> None:
    pass

mypy Playground, Pyright playground

Expected Behavior

I expect a type error at 2 + "oops". (Pyright agrees.)

Actual Behavior

mypy finds no errors.

Your Environment

• Mypy version used: 1.5.1
• Mypy command-line flags: --strict
• Mypy configuration options from mypy.ini (and other config files): none
• Python version used: 3.11.4

Empieza reproduciendo el ejemplo Annotated[int, 2 + "oops"] en Python 3.11 con --strict y, a continuación, sigue el tratamiento que hace mypy de los metadatos de Annotated. Se considera terminado cuando mypy informa de un error de tipo para la expresión de metadatos, manteniendo al mismo tiempo la interpretación de typing de int.