Overriding reserved NamedTuple methods

[lolpack]

Overriding reserved methods like _asdict and _make in a NamedTuple subclass should produce an error.

from typing import NamedTuple

class Record(NamedTuple):
    name: str
    value: int

    def _asdict(self) -> dict[str, object]:
        return {}

    @classmethod
    def _make(cls, iterable: object) -> "Record":
        return cls("", 0)

Sandbox: Pyrefly

[yangdanny97]

shouldn't they be decorated with @final if they don't want to be overridden?

[DetachHead]

i've made a PR to typeshed to fix this: python/typeshed#15895. i agree that it should not be the type checker's responsibility to special-case this