Traits on vectors do strange things.

gistfile1.rs

import to_bytes::{IterBytes,iter_le_bytes_2,iter_be_bytes_2};

enum thing = uint;
impl thing : IterBytes {
    fn iter_le_bytes(f: to_bytes::Cb) { (*self).iter_le_bytes(f) }
    fn iter_be_bytes(f: to_bytes::Cb) { (*self).iter_be_bytes(f) }
}

enum stuff1 = ~[thing];
impl stuff1 : IterBytes {
    fn iter_le_bytes(f: to_bytes::Cb) { (*self).iter_le_bytes(f) }
    fn iter_be_bytes(f: to_bytes::Cb) { (*self).iter_be_bytes(f) }
}

enum stuff = (uint, ~[thing]);
impl stuff : IterBytes {
    fn iter_le_bytes(f: to_bytes::Cb) {
        match *self { (ref i, ref v) => iter_le_bytes_2(i, v, f) }
    }
    fn iter_be_bytes(f: to_bytes::Cb) {
        match *self { (ref i, ref v) => iter_be_bytes_2(i, v, f) }
    }
}

// minim2.rs:18:40: 18:55 error: failed to find an implementation of trait @core::to_bytes::IterBytes for ~[thing]
// minim2.rs:18         match *self { (ref i, ref v) => iter_le_bytes_2(i, v, f) }
//                                                      ^~~~~~~~~~~~~~~