I want to print class variable `animal_name` for multiple classes. Multiple classes consist of dataclass `Cat` and non-dataclass `Bird`.

Bug Report

I want to print class variable animal_name for multiple classes. Multiple classes consist of dataclass Cat and non-dataclass Bird.
Parent class of class Cat and Bird has class variable animal_name.
But mypy raised error.

Details: https://qiita.com/yuji38kwmt/items/29c9163a69dc37917d33

To Reproduce
https://gist.github.com/mypy-play/4e59803f4761dbbf59f6e253ca53d420
https://mypy-play.net/?mypy=latest&python=3.11&gist=4e59803f4761dbbf59f6e253ca53d420

from dataclasses import dataclass
from typing import ClassVar


class Animal:
    animal_name: ClassVar[str]


@dataclass
class Cat(Animal):
    cat_id: str
    animal_name: ClassVar[str] = "cat"

    def only_cat_method(self) -> None:
        print("only cat method")


class Bird(Animal):
    """Not dataclass"""

    animal_name: ClassVar[str] = "bird"

    def only_bird_method(self) -> None:
        print("only bird method")


for cls in [Cat, Bird]:
    print(cls.animal_name)

Expected Behavior
no error

Actual Behavior

The following error occurred.

$ mypy sample.py
sample.py:28: error: "type" has no attribute "animal_name"  [attr-defined]
Found 1 error in 1 file (checked 1 source file)

But I create __init__ method to Bird class, error did not occurre.

class Bird(Animal):
    """Not dataclass"""
    animal_name: ClassVar[str] = "bird"

    def only_bird_method(self) -> None:
        print("only bird method")

    def __init__(self, foo) -> None:
        pass

Your Environment

• Mypy version used: 1.2.0
• Mypy command-line flags: no options
• Mypy configuration options from mypy.ini (and other config files): no file
• Python version used: 3.11.2

Start by running the sample.py reproduction from the issue or the linked mypy-play gist with mypy 1.2.0, then trace how the type checker infers the common class type for Cat and Bird and handles dataclass versus non-dataclass classes. Done means the reproduction reports no error for cls.animal_name while preserving the existing behavior for the shown classes.