Implement LWG3144 - span does not have a const_pointer typedef

[mclow.lists]

Summary

This issue is due to be adopted in Kona in Feb.
We already had it - as an extension.

[mclow.lists]

Thanks for the quick review. I'm going to hold off on landing this until after Kona.

[mclow.lists]

Committed as revision 354802

include/span

     using index_type = ptrdiff_t;
     using difference_type = ptrdiff_t;
     using pointer = element_type*;
+    using const_pointer = const element_type*;
     using reference = element_type&;
     using iterator = implementation-defined;
+    using const_reference = const element_type&;
     using const_iterator = implementation-defined;
     using reverse_iterator = std::reverse_iterator<iterator>;
     using const_reverse_iterator = std::reverse_iterator<const_iterator>;

     using index_type             = ptrdiff_t;
     using difference_type        = ptrdiff_t;
     using pointer                = _Tp *;
-    using const_pointer          = const _Tp *; // not in standard
+    using const_pointer          = const _Tp *;
     using reference              = _Tp &;
-    using const_reference        = const _Tp &; // not in standard
+    using const_reference        = const _Tp &;
     using iterator               =  __wrap_iter<pointer>;
     using const_iterator         =  __wrap_iter<const_pointer>;
     using reverse_iterator       = _VSTD::reverse_iterator<iterator>;

     using index_type             = ptrdiff_t;
     using difference_type        = ptrdiff_t;
     using pointer                = _Tp *;
-    using const_pointer          = const _Tp *; // not in standard
+    using const_pointer          = const _Tp *;
     using reference              = _Tp &;
-    using const_reference        = const _Tp &; // not in standard
+    using const_reference        = const _Tp &;
     using iterator               =  __wrap_iter<pointer>;
     using const_iterator         =  __wrap_iter<const_pointer>;
     using reverse_iterator       = _VSTD::reverse_iterator<iterator>;

test/std/containers/views/types.pass.cpp

 //  using difference_type        = ptrdiff_t;
 //  using pointer                = element_type *;
 //  using reference              = element_type &;
+//  using const_pointe           = const element_type *;
+//  using const_reference        = const element_type &;
 //  using iterator               = implementation-defined;
 //  using const_iterator         = implementation-defined;
 //  using reverse_iterator       = std::reverse_iterator<iterator>;

     ASSERT_SAME_TYPE(typename S::index_type,      std::ptrdiff_t);
     ASSERT_SAME_TYPE(typename S::difference_type, std::ptrdiff_t);
     ASSERT_SAME_TYPE(typename S::pointer,         ElementType *);
+    ASSERT_SAME_TYPE(typename S::const_pointer,   const ElementType *);
     ASSERT_SAME_TYPE(typename S::reference,       ElementType &);
+    ASSERT_SAME_TYPE(typename S::const_reference, const ElementType &);
 
     static_assert(S::extent == Size); // check that it exists