ClassVar[TypeAlias] in dataclass-like classes becomes Any

Bug Report

When defining a type alias within a dataclass (or attrs) class, it has to be marked as ClassVar[^1] which causes the field to be treated as Any.

This bug has been already reported in https://github.com/python/mypy/issues/9238#issuecomment-1089065588 but never followed up.

To Reproduce

from dataclasses import dataclass
from typing import ClassVar, TypeAlias


@dataclass
class Namespace:
    Alias: ClassVar[TypeAlias] = int
    
reveal_type(Namespace.Alias)

https://mypy-play.net/?mypy=latest&python=3.12&gist=e66e903f3b055fa8433707a5e8b99ebc

Expected Behavior

main.py:16: note: Revealed type is "int"

Actual Behavior

main.py:16: note: Revealed type is "Any"

Your Environment

See the playground. Python 3.12 on Mypy 1.9.0.

[^1]: The attrs plugin crashes with an assertion error if this is forgotten, but that's a bug for another day.

Empieza ejecutando el reproductor de Python proporcionado con mypy 1.9.0 y compara el tipo revelado con el int esperado. Traza cómo se gestiona ClassVar[TypeAlias] en clases similares a dataclass y, después, añade o actualiza la cobertura para que el tipo revelado ya no sea Any; la aserción de attrs-plugin queda explícitamente fuera del alcance.