Comment by el_pollo_diablo

So there are now two ways to represent the same state: None or Some(struct whose fields are all None). Even though one of these representations is never produced by the deserialization routine, anyone could construct it if the constructor is public. And even if they don't, the different representations will show up in pattern matching as separate paths for every access to the field. This looks like a good opportunity to make these types (optimized for storage) private, and to define public view objects/accessors (optimized for usage) on top of them that merge equivalent representations.