Actually I'm not sure if the fix is so simple. What happens if B does not inherit from dataclass, but still inherits from A? Do we want to use the new __post_init__? I would assume we do, meaning we don't necessarily want to attach the __post_init__ to the dataclass, but to subclasses.

If so, the suggestion to call __init__() from __post_init__() might be the problematic part, and is what conceptually breaks the inheritance linearization.