bounds in ty params can't seem to refer to other ty params

[catamorphism]

This is more-or-less taken from commented-out code in core::iter-trait:

import iter;
import iter::base_iter;

impl Q<A> for base_iter<A> {
   fn flat_map_to_vec<B:copy, IB:base_iter<B>>(op: fn(B) -> IB) -> [B] {
      iter::flat_map_to_vec(self, op)
   }
}

This fails to compile with unresolved typename: B. That's not right, since the method should get resolved in a scope that includes its own ty params. Strangely enough, the same function does compile if it's not inside an impl and takes its self arg explicitly.

[catamorphism]

Adding (xfailed) test case as run-pass/issue-2611.rs

[bstrie]

Post-0.3, the test case gives this error instead:

mismatched types: expected `core::iter::base_iter<'b>` but found `core::iter::base_iter<'a>` (type parameter vs type parameter)
2611.rs:6       iter::flat_map_to_vec(self, op)
                ^~~~~~~~~~~~~~~~~~~~~

Not sure whether or not the message is accurate, but it's certainly unhelpful.

[catamorphism]

I'll try fixing the error message.

[msullivan]

Now it fails with a message saying they have incompatible type parameters. I think I'm going to look into this some.

[catamorphism]

I'm going to take this one, since @msullivan already has plenty of stuff ;-) I'm still getting the "incompatible type parameters" message too, which seems wrong. I'll keep looking.