How can I enforce equality of two associated type parameters of traits?

Question

I have a function f which takes two arguments of the same type, and a function g which takes two arguments of different types, but both types have

Answer 1

I found a solution. It's not done by a where clause, but this way:

fn g>(a: T, b: U) { // where T::A is equal to B::A
    f(a.getter(), b.getter())
}