Should deriving `InvariantFree` require that a structs fields are the same pub level as the struct?

[rylev]

Since InvariantFree types are meant to represent types without invariants, it should reason that all the fields of the type should be accessible. Should we require that a structs fields are the same visibility level as the struct itself?

[RustyYato]

No, it should be fine for the fields to be more private than the struct. There doesn't seem to be any reason to make this restriction.