@aszs Thanks for the reference! This makes a lot of sense. Luckily, both traits that are currently interesting to me (Secret and ValueType) do stop at indirection.
@Vorpal Despite the fact Secret stops at indirection, I started trying to make the trait optional (and, at the same time, removing my keyword that defines it in favour of explicit implementations) and while not finished, it looks very much doable. So regardless of the performance cost, I think this is a fair solution.
Anyway, I hope the idea of the Sectet trait is somewhat clear now. Any comments on whether this concept should be generalized?