Implement RFC 839 for EnumSet

Author: jooert

src/libcollections/enum_set.rs

@@ -288,3 +288,10 @@ impl<E:CLike> Extend<E> for EnumSet<E> {
         }
     }
 }
+
+#[unstable(feature = "extend_ref", reason = "recently added")]
+impl<'a, E: 'a + CLike + Copy> Extend<&'a E> for EnumSet<E> {
+    fn extend<I: IntoIterator<Item=&'a E>>(&mut self, iter: I) {
+        self.extend(iter.into_iter().cloned());
+    }
+}

src/libcollectionstest/enum_set.rs

@@ -242,3 +242,25 @@ fn test_overflow() {
     let mut set = EnumSet::new();
     set.insert(Bar::V64);
 }
+
+#[test]
+fn test_extend_ref() {
+    let mut a = EnumSet::new();
+    a.insert(A);
+
+    a.extend(&[A, C]);
+
+    assert_eq!(a.len(), 2);
+    assert!(a.contains(&A));
+    assert!(a.contains(&C));
+
+    let mut b = EnumSet::new();
+    b.insert(B);
+
+    a.extend(&b);
+
+    assert_eq!(a.len(), 3);
+    assert!(a.contains(&A));
+    assert!(a.contains(&B));
+    assert!(a.contains(&C));
+}