Literal infers tuple literal as Union of the items though this syntax is forbidden by PEP 586

The section Illegal parameters for Literal at type check time describes that tuple literals inside Literal are forbidden:

Tuples containing valid literal types like Literal[(1, "foo", "bar")]. The user could always express this type as Tuple[Literal[1], Literal["foo"], Literal["bar"]] instead. Also, tuples are likely to be confused with the Literal[1, 2, 3] shortcut.

Nevertheless mypy seems to be taking this shortcut since it doesn't flag the following code:

from typing_extensions import Literal

a : Literal[(1, 2)] = 1 

Python 3.7, mypy 0.740, typing-extensions 3.7.4.

Inizia riproducendo lo snippet Python segnalato con Literal[(1, 2)] e conferma se mypy lo accetta. Individua il percorso di type-checking di Literal e i relativi test esistenti; il lavoro è completato quando i literal di tupla in Literal vengono rifiutati in conformità con PEP 586.