Implement RFC 839 for LinkedList

Author: jooert

src/libcollections/linked_list.rs

@@ -871,6 +871,13 @@ impl<A> Extend<A> for LinkedList<A> {
     }
 }
 
+#[unstable(feature = "extend_ref", reason = "recently added")]
+impl<'a, T: 'a + Copy> Extend<&'a T> for LinkedList<T> {
+    fn extend<I: IntoIterator<Item=&'a T>>(&mut self, iter: I) {
+        self.extend(iter.into_iter().cloned());
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<A: PartialEq> PartialEq for LinkedList<A> {
     fn eq(&self, other: &LinkedList<A>) -> bool {

src/libcollectionstest/linked_list.rs

@@ -321,6 +321,25 @@ fn test_show() {
     assert_eq!(format!("{:?}", list), "[\"just\", \"one\", \"test\", \"more\"]");
 }
 
+#[test]
+fn test_extend_ref() {
+    let mut a = LinkedList::new();
+    a.push_back(1);
+
+    a.extend(&[2, 3, 4]);
+
+    assert_eq!(a.len(), 4);
+    assert_eq!(a, list_from(&[1, 2, 3, 4]));
+
+    let mut b = LinkedList::new();
+    b.push_back(5);
+    b.push_back(6);
+    a.extend(&b);
+
+    assert_eq!(a.len(), 6);
+    assert_eq!(a, list_from(&[1, 2, 3, 4, 5, 6]));
+}
+
 #[bench]
 fn bench_collect_into(b: &mut test::Bencher) {
     let v = &[0; 64];