Concrete class considered abstract when base class has additional python type

Bug Report

When using a TypeVar from an abstract class, and the abstract class additionally inherits from some integrated types (I found dict, int, str, set; not float), mypy incorrectly alarms about instantiating an abstract class.

To Reproduce

from abc import ABC, abstractmethod
from typing import TypeVar, Type


class User(ABC, dict):  # removing dict makes mypy happy
    @abstractmethod
    def method(self):
        ...


class BasicUser(User):
    def method(self):
        print('basic')


U = TypeVar('U', bound=User)


def new_user(user_class: Type[U]) -> U:
  user = user_class()
  return user


joe = new_user(BasicUser)

Expected Behavior

It should not report an error, as it does not when inheriting from another class or just ABC.

Actual Behavior

test.py:20: error: Cannot instantiate abstract class "User" with abstract attribute "method" [abstract]

Your Environment

• Mypy version used: 0.990
• Mypy command-line flags: None
• Mypy configuration options from mypy.ini (and other config files): None
• Python version used: 3.10.8

まず、提供された test.py の再現コードを mypy 0.990 で実行し、BasicUser に対する抽象クラスエラーを確認します。TypeVar の境界、抽象メソッド、追加の組み込み基底クラスの処理を追跡し、その後、誤った診断なしで new_user(BasicUser) が受け入れられることを示す回帰テストを追加します。