[Bug libstdc++/43813] [DR1234] vector<T*>(3, NULL) fails to compile

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43813

--- Comment #15 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-03-04 12:00:52 UTC ---
(In reply to comment #14)
> Well, besides wrapping the thing in an __is_input_iterator helper.

That's what I was going to suggest, possibly using an alias template:

+#ifdef __GXX_EXPERIMENTAL_CXX0X__
+  private:
+      template<typename _InIter>
+        using _RequireInputerIter = typename
+              enable_if<is_convertible<typename
+                        iterator_traits<_InputIterator>::iterator_category,
+                        input_iterator_tag>::value>::type;
+
+  public:
+      template<typename _InputIterator, typename =
+               _RequireInputIter<_InputIterator>>
+        deque(_InputIterator __first, _InputIterator __last,
+             const allocator_type& __a = allocator_type())
+       : _Base(__a)
+        {
+         typedef typename iterator_traits<_InputIterator>::
+           iterator_category _IterCategory;
+         _M_range_initialize(__first, __last, _IterCategory());
+       }
+#else