DST Receivers/Idempotent unsize

[marcianx]

@stebalien

I don't quite understand how you intend to implement DerefMut<Target=Wrapper<Trait>>. The return type of deref_mut() would be &'a mut Wrapper<Trait>. But Wrapper<T> does not contain a Wrapper<Trait> and you would need to return a reference to the latter with the right lifetime. As far as I can see a conversion function, not a dereferencing one, needs to be implemented that unwraps T, casts it to Trait and returns the wrapped version of it; i.e. &'a Wrapper<T> --> Wrapper<Trait + 'a>.

I can already do this. See my other thread.

Wow, yes, you can! Can someone explain what that means? Specifically, given

struct Wrapper<A: ?Sized + Trait>(A);

what's the binary representation of Wrapper<Trait>? It doesn't seem to be a wrapped trait object. What exactly does, e.g. Wrapper(1u32) as Wrapper<Trait> create/do?