@attrs.frozen
class A:
    foo: int = 1

@attrs.frozen
class B:
    a: A = A()  # should be valid, but gives RUF009

@dataclasses.dataclass(frozen=True)
class C:
    foo: int = 1

@dataclasses.dataclass(frozen=True)
class D:
    d: C = C()  # should be valid , but gives RUF009