Inconsistent dataclass declaration

The dataclass decorator in the typeshed package has an inconsistency in its overloads. Specifically, when cls is passed explicitly as None, it is unclear whether additional arguments (e.g., init, repr, etc.) should be allowed or not. The current implementation allows passing cls=None alongside additional arguments, but this usage is not explicitly documented or validated.

Expected Behavior

The overloads should clearly define and document the behavior of cls=None when additional arguments are provided:

If allowed, the typing should reflect that explicitly.
If not allowed, the implementation should prevent or warn against such usage.

Current Behavior

Passing cls=None with arguments like kw_only=True is allowed, but this behavior is not described in the overloads. For example:

decorator = dataclass(None, kw_only=True)
@decorator
class MyClass:
    x: int

The above works but is ambiguous in terms of type checking and intended usage.

まず、typeshed パッケージ内の dataclass デコレーターのオーバーロードを見つけ、示されている dataclass(None, kw_only=True) の例と比較します。追加の引数を伴う cls=None がサポートされているかを明確にし、そのうえでオーバーロードとドキュメントがその判断を一貫して表すようにします。型チェッカーとユーザーにとって動作が明確になれば完了です。