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.

Beginne damit, den bereitgestellten Python-Reproducer mit mypy 1.9.0 auszuführen, und vergleiche den angezeigten Typ mit dem erwarteten int. Verfolge, wie ClassVar[TypeAlias] in dataclass-ähnlichen Klassen verarbeitet wird, und füge dann Tests hinzu oder aktualisiere die Testabdeckung, sodass der angezeigte Typ nicht mehr Any ist; die Assertion des attrs-plugin liegt ausdrücklich außerhalb des Umfangs.