Abstract And Final Method

What it does

Checks for methods decorated with both @abstractmethod and @final.

Why is this bad?

An abstract method must be overridden for a subclass to become concrete, but a final method cannot be overridden. Combining the decorators therefore makes it impossible for a subclass to provide a concrete implementation.

Example

from abc import ABC, abstractmethod
from typing import final


class Base(ABC):
    @final
    @abstractmethod
    def method(self) -> None: ...  # error