Invalid Dataclass Override

What it does

Checks for dataclass definitions that have both frozen=True and a custom __setattr__ or __delattr__ method defined.

Why is this bad?

Frozen dataclasses synthesize __setattr__ and __delattr__ methods which raise a FrozenInstanceError to emulate immutability.

Overriding either of these methods raises a runtime error.

Examples

from dataclasses import dataclass


@dataclass(frozen=True)
class A:
    def __setattr__(self, name: str, value: object) -> None: ...  # error