typing.Self does not work properly with class variables

[McDic]

Bug Report

typing.Self does not work well with class variables.

To Reproduce

In Python 3.11, write and execute the same code from here, which is

import math
import typing


class Team:
    """
    Represent "team" in Minecraft.
    """

    _cache: dict[str, typing.Self] = {}

    def __init__(self, name: str):
        self._name = name
        if self._name in type(self)._cache:
            raise ValueError('Team "%s" already exists;' % (self._name,))
        else:
            type(self)._cache[self._name] = self

    @property
    def name(self):
        return self._name

    @classmethod
    def get_team(cls, name: str) -> typing.Self:
        """
        Use this method to create a team instead of calling constructor directly.
        """
        if name in cls._cache:
            return cls._cache[name]
        else:
            return cls(name)

Expected Behavior

There should be no error.

Actual Behavior

Mypy reports Incompatible return value type (got "Team", expected "Self") on return cls._cache[name].

Your Environment

• Mypy version used: 1.1.6
• Mypy command-line flags: mypy (filename)
• Mypy configuration options from mypy.ini (and other config files): Nothing
• Python version used: 3.11.6

[cossor]

i think this is a minor issue, so i'm commenting only because i think we should minimize quoted string usage in type hints.

mypy 1.7.0 (Python 3.12) also emits a return-value complaint after checking a smaller example:

import typing


class Spam:
    @classmethod
    def instance(cls) -> typing.Self:
        return Eggs()


class Eggs(Spam):
    pass

in the first example, cls might not be Self so my example doesn't really change anything?