Suggest using Self in traits

[ChrisJefferson]

I wrote the following trait: trait Area : Sized { fn f(a : Area) -> Area; }. What I meant (I've now discovered) was trait Area : Sized { fn f(a : Self) -> Self; }. However, it isn't easy to get "to that point".

Reading the pages linked to from the compiler warning, and the rust book, I didn't find anything which discussed what using the name of a trait inside the trait means -- in particular (and this was I believe the source of my confusion), it isn't like C++ where, while defining template<typename T> vector { ... }, we use vector to refer to the type we are currently defining.

I'm not suggesting a change of behaviour, but I wonder if this could be a common enough bug to say "did you mean Self?"