Fix LWG issue #2106: move_iterators returning prvalues

llvm-svn: 267091
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 906c50859b0d75725850b770f87b71b9d541ecd4
diff --git a/include/iterator b/include/iterator
index e6f4723..0e60aa9 100644
--- a/include/iterator
+++ b/include/iterator
@@ -951,7 +951,12 @@
     typedef typename iterator_traits<iterator_type>::difference_type difference_type;
     typedef iterator_type pointer;
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
-    typedef value_type&& reference;
+    typedef typename iterator_traits<iterator_type>::reference __reference;
+    typedef typename conditional<
+            is_reference<__reference>::value,
+            typename remove_reference<__reference>::type&&,
+            __reference
+        >::type reference;
 #else
     typedef typename iterator_traits<iterator_type>::reference reference;
 #endif