HashSet/HashMap nesting results to methods not being defined properly

[tijsmaas]

This compiles just fine:

fn x(input: HashSet<usize>) {
    for i in input.iter() {}
}

This gives compile time error:

no method named iter found for type std::collections::hash::set::HashSet<std::collections::hash::set::HashSet<usize>> in the current scope

fn x(input: HashSet<HashSet<usize>>) {
    for i in input.iter() {}
}

I tested this code on multiple versions of rust using play.rust-lang.org and all versions seem to be affected in the same way. I also noticed that using a HashMap results to the same issue, and in both cases not only iter() is gone, but no single method seems to work. (I only tested iter(), capacity() and clear())

[tijsmaas]

Here is a live source code example http://is.gd/AEf0vx

[alexcrichton]

This is actually because HashSet<T> does not itself implement Hash, so this is a dupe of #20941, but thanks for the report!