Structural equality across every kind-specific field.
Cast-free: the union narrows on kind, so a future variant with a new discriminating field becomes a compile error here rather than silently comparing equal. Three rebinding guards depend on that.
kind
Structural equality across every kind-specific field.
Cast-free: the union narrows on
kind, so a future variant with a new discriminating field becomes a compile error here rather than silently comparing equal. Three rebinding guards depend on that.