Overloads in super-class for sub-class specific return types

[twoertwein]

Bug Report
It is probably not good coding style to implement sub-class specific behavior in a super-class, but it would be great to still be able to write type annotations for it.

The sub-class specific overloads in the example below make mypy and pyright correctly infer the return type. Unfortunately, mypy throws an error for the two sub-class specific overloads. Are these false-positives?

To Reproduce

from __future__ import annotations

from typing import overload


class Base:
    @overload
    def any(self: A) -> bool:   # mypy:  The erased type of self "test.A" is not a supertype of its class "test.Base"
        ...

    @overload
    def any(self: B) -> str:  # mypy:  The erased type of self "test.B" is not a supertype of its class "test.Base"
        ...

    @overload
    def any(self) -> bool | str:
        ...

    def any(self) -> bool | str:
        # implementation that handles sub-classes differently
        ...


class A(Base):
    ...


class B(Base):
    ...


# mypy&pyright: bool | str
reveal_type(Base().any())

# mypy&pyright: bool
reveal_type(A().any())

# mypy&pyright: str
reveal_type(B().any())

Expected Behavior
No erased type errors?

Actual Behavior
See inline comments.

Your Environment

• Mypy version used: 0.910
• Mypy command-line flags: -
• Mypy configuration options from mypy.ini (and other config files): -
• Python version used: 3.9.6
• Operating system and version: 3.10.0-693.5.2.el7.x86_64

[AlexWaygood]

Is this feature really necessary? You can achieve the same thing just by doing this:

from __future__ import annotations
from typing import Callable


class Base:
    def any(self) -> bool | str:
        # implementation that handles sub-classes differently
        ...


class A(Base):
    any: Callable[[A], bool]


class B(Base):
    any: Callable[[B], str]


reveal_type(Base().any())  # Revealed type is "Union[builtins.bool, builtins.str]"
reveal_type(A().any())  # Revealed type is "builtins.bool"
reveal_type(B().any())  # Revealed type is "builtins.str"

Mypy has no complaints, and it's even more concise.

[twoertwein]

Thank you @AlexWaygood, I like it!