auto merge of #11510 : wycats/rust/clone-treeset, r=huonw

Author: bors

Diff for: src/libextra/treemap.rs

@@ -549,6 +549,7 @@ impl<'a, T> Iterator<&'a T> for TreeSetRevIterator<'a, T> {
 /// A implementation of the `Set` trait on top of the `TreeMap` container. The
 /// only requirement is that the type of the elements contained ascribes to the
 /// `TotalOrd` trait.
+#[deriving(Clone)]
 pub struct TreeSet<T> {
     priv map: TreeMap<T, ()>
 }
@@ -1588,6 +1589,16 @@ mod test_set {
         }
     }
 
+    #[test]
+    fn test_clone_eq() {
+      let mut m = TreeSet::new();
+
+      m.insert(1);
+      m.insert(2);
+
+      assert!(m.clone() == m);
+    }
+
     fn check(a: &[int],
              b: &[int],
              expected: &[int],