Index: include/iosfwd
===================================================================
--- include/iosfwd
+++ include/iosfwd
@@ -194,6 +194,11 @@
 typedef basic_string<char, char_traits<char>, allocator<char> > string;
 typedef basic_string<wchar_t, char_traits<wchar_t>, allocator<wchar_t> > wstring;
 
+
+// Include other forward declarations here
+template <class _Tp, class _Alloc = allocator<_Tp> >
+class _LIBCPP_TYPE_VIS_ONLY vector;
+
 _LIBCPP_END_NAMESPACE_STD
 
 #endif  // _LIBCPP_IOSFWD
Index: include/iterator
===================================================================
--- include/iterator
+++ include/iterator
@@ -340,10 +340,10 @@
 */
 
 #include <__config>
+#include <iosfwd> // for forward declarations of vector and string.
 #include <__functional_base>
 #include <type_traits>
 #include <cstddef>
-#include <iosfwd>
 #include <initializer_list>
 #ifdef __APPLE__
 #include <Availability.h>
Index: include/vector
===================================================================
--- include/vector
+++ include/vector
@@ -262,6 +262,7 @@
 */
 
 #include <__config>
+#include <iosfwd> // for forward declaration of vector
 #include <__bit_reference>
 #include <type_traits>
 #include <climits>
@@ -453,7 +454,7 @@
     }
 }
 
-template <class _Tp, class _Allocator = allocator<_Tp> >
+template <class _Tp, class _Allocator /* = allocator<_Tp> */>
 class _LIBCPP_TYPE_VIS_ONLY vector
     : private __vector_base<_Tp, _Allocator>
 {