rollup merge of #23604: apasel422/btree

`btree_map::IntoIter` (and `btree_set::IntoIter`) remains, but it is a bit trickier.

src/libcollections/btree/map.rs

@@ -78,6 +78,7 @@ pub struct BTreeMap<K, V> {
 }
 
 /// An abstract base over-which all other BTree iterators are built.
+#[derive(Clone)]
 struct AbsIter<T> {
     traversals: VecDeque<T>,
     size: usize,
@@ -1040,6 +1041,9 @@ fn next_back(&mut self) -> Option<(K, V)> {
     }
 }
 
+impl<'a, K, V> Clone for Iter<'a, K, V> {
+    fn clone(&self) -> Iter<'a, K, V> { Iter { inner: self.inner.clone() } }
+}
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, K, V> Iterator for Iter<'a, K, V> {
     type Item = (&'a K, &'a V);
@@ -1082,6 +1086,9 @@ fn next_back(&mut self) -> Option<(K, V)> { self.inner.next_back() }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<K, V> ExactSizeIterator for IntoIter<K, V> {}
 
+impl<'a, K, V> Clone for Keys<'a, K, V> {
+    fn clone(&self) -> Keys<'a, K, V> { Keys { inner: self.inner.clone() } }
+}
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, K, V> Iterator for Keys<'a, K, V> {
     type Item = &'a K;
@@ -1097,6 +1104,9 @@ fn next_back(&mut self) -> Option<(&'a K)> { self.inner.next_back() }
 impl<'a, K, V> ExactSizeIterator for Keys<'a, K, V> {}
 
 
+impl<'a, K, V> Clone for Values<'a, K, V> {
+    fn clone(&self) -> Values<'a, K, V> { Values { inner: self.inner.clone() } }
+}
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, K, V> Iterator for Values<'a, K, V> {
     type Item = &'a V;
@@ -1111,6 +1121,9 @@ fn next_back(&mut self) -> Option<(&'a V)> { self.inner.next_back() }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, K, V> ExactSizeIterator for Values<'a, K, V> {}
 
+impl<'a, K, V> Clone for Range<'a, K, V> {
+    fn clone(&self) -> Range<'a, K, V> { Range { inner: self.inner.clone() } }
+}
 impl<'a, K, V> Iterator for Range<'a, K, V> {
     type Item = (&'a K, &'a V);
 

src/libcollections/btree/node.rs

@@ -1326,6 +1326,7 @@ trait TraversalImpl {
 
 /// A `TraversalImpl` that actually is backed by two iterators. This works in the non-moving case,
 /// as no deallocation needs to be done.
+#[derive(Clone)]
 struct ElemsAndEdges<Elems, Edges>(Elems, Edges);
 
 impl<K, V, E, Elems: DoubleEndedIterator, Edges: DoubleEndedIterator>
@@ -1404,6 +1405,7 @@ fn drop(&mut self) {
 }
 
 /// An abstraction over all the different kinds of traversals a node supports
+#[derive(Clone)]
 struct AbsTraversal<Impl> {
     inner: Impl,
     head_is_edge: bool,

src/libcollections/btree/set.rs

@@ -628,6 +628,9 @@ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
     }
 }
 
+impl<'a, T> Clone for Iter<'a, T> {
+    fn clone(&self) -> Iter<'a, T> { Iter { iter: self.iter.clone() } }
+}
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T> Iterator for Iter<'a, T> {
     type Item = &'a T;
@@ -658,6 +661,9 @@ fn next_back(&mut self) -> Option<T> { self.iter.next_back() }
 impl<T> ExactSizeIterator for IntoIter<T> {}
 
 
+impl<'a, T> Clone for Range<'a, T> {
+    fn clone(&self) -> Range<'a, T> { Range { iter: self.iter.clone() } }
+}
 impl<'a, T> Iterator for Range<'a, T> {
     type Item = &'a T;
 
@@ -677,6 +683,11 @@ fn cmp_opt<T: Ord>(x: Option<&T>, y: Option<&T>,
     }
 }
 
+impl<'a, T> Clone for Difference<'a, T> {
+    fn clone(&self) -> Difference<'a, T> {
+        Difference { a: self.a.clone(), b: self.b.clone() }
+    }
+}
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T: Ord> Iterator for Difference<'a, T> {
     type Item = &'a T;
@@ -692,6 +703,11 @@ fn next(&mut self) -> Option<&'a T> {
     }
 }
 
+impl<'a, T> Clone for SymmetricDifference<'a, T> {
+    fn clone(&self) -> SymmetricDifference<'a, T> {
+        SymmetricDifference { a: self.a.clone(), b: self.b.clone() }
+    }
+}
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T: Ord> Iterator for SymmetricDifference<'a, T> {
     type Item = &'a T;
@@ -707,6 +723,11 @@ fn next(&mut self) -> Option<&'a T> {
     }
 }
 
+impl<'a, T> Clone for Intersection<'a, T> {
+    fn clone(&self) -> Intersection<'a, T> {
+        Intersection { a: self.a.clone(), b: self.b.clone() }
+    }
+}
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T: Ord> Iterator for Intersection<'a, T> {
     type Item = &'a T;
@@ -728,6 +749,11 @@ fn next(&mut self) -> Option<&'a T> {
     }
 }
 
+impl<'a, T> Clone for Union<'a, T> {
+    fn clone(&self) -> Union<'a, T> {
+        Union { a: self.a.clone(), b: self.b.clone() }
+    }
+}
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T: Ord> Iterator for Union<'a, T> {
     type Item = &'a T;