rollup merge of #23637: apasel422/iter

src/libcollections/bit.rs

@@ -1804,12 +1804,16 @@ struct TwoBitPositions<'a> {
     next_idx: usize
 }
 
+#[derive(Clone)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Union<'a>(TwoBitPositions<'a>);
+#[derive(Clone)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Intersection<'a>(Take<TwoBitPositions<'a>>);
+#[derive(Clone)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Difference<'a>(TwoBitPositions<'a>);
+#[derive(Clone)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct SymmetricDifference<'a>(TwoBitPositions<'a>);
 

src/libcollections/linked_list.rs

@@ -832,6 +832,8 @@ impl<A> DoubleEndedIterator for IntoIter<A> {
     fn next_back(&mut self) -> Option<A> { self.list.pop_back() }
 }
 
+impl<A> ExactSizeIterator for IntoIter<A> {}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<A> FromIterator<A> for LinkedList<A> {
     fn from_iter<T: IntoIterator<Item=A>>(iter: T) -> LinkedList<A> {

src/libcollections/vec_deque.rs

@@ -556,7 +556,7 @@ pub fn iter_mut(&mut self) -> IterMut<T> {
         }
     }
 
-    /// Consumes the list into an iterator yielding elements by value.
+    /// Consumes the list into a front-to-back iterator yielding elements by value.
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn into_iter(self) -> IntoIter<T> {
         IntoIter {
@@ -1573,6 +1573,7 @@ fn next_back(&mut self) -> Option<&'a mut T> {
 impl<'a, T> ExactSizeIterator for IterMut<'a, T> {}
 
 /// A by-value VecDeque iterator
+#[derive(Clone)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct IntoIter<T> {
     inner: VecDeque<T>,

src/libstd/collections/hash/set.rs

@@ -853,6 +853,9 @@ fn into_iter(self) -> IntoIter<T> {
     }
 }
 
+impl<'a, K> Clone for Iter<'a, K> {
+    fn clone(&self) -> Iter<'a, K> { Iter { iter: self.iter.clone() } }
+}
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, K> Iterator for Iter<'a, K> {
     type Item = &'a K;
@@ -889,6 +892,12 @@ impl<'a, K> ExactSizeIterator for Drain<'a, K> {
     fn len(&self) -> usize { self.iter.len() }
 }
 
+impl<'a, T, S> Clone for Intersection<'a, T, S> {
+    fn clone(&self) -> Intersection<'a, T, S> {
+        Intersection { iter: self.iter.clone(), ..*self }
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T, S> Iterator for Intersection<'a, T, S>
     where T: Eq + Hash, S: HashState
@@ -912,6 +921,12 @@ fn size_hint(&self) -> (usize, Option<usize>) {
     }
 }
 
+impl<'a, T, S> Clone for Difference<'a, T, S> {
+    fn clone(&self) -> Difference<'a, T, S> {
+        Difference { iter: self.iter.clone(), ..*self }
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T, S> Iterator for Difference<'a, T, S>
     where T: Eq + Hash, S: HashState
@@ -935,6 +950,12 @@ fn size_hint(&self) -> (usize, Option<usize>) {
     }
 }
 
+impl<'a, T, S> Clone for SymmetricDifference<'a, T, S> {
+    fn clone(&self) -> SymmetricDifference<'a, T, S> {
+        SymmetricDifference { iter: self.iter.clone() }
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T, S> Iterator for SymmetricDifference<'a, T, S>
     where T: Eq + Hash, S: HashState
@@ -945,6 +966,10 @@ fn next(&mut self) -> Option<&'a T> { self.iter.next() }
     fn size_hint(&self) -> (usize, Option<usize>) { self.iter.size_hint() }
 }
 
+impl<'a, T, S> Clone for Union<'a, T, S> {
+    fn clone(&self) -> Union<'a, T, S> { Union { iter: self.iter.clone() } }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T, S> Iterator for Union<'a, T, S>
     where T: Eq + Hash, S: HashState