2010-05-27 Paolo Carlini <paolo.carlini@oracle.com>

	PR libstdc++/40497
	* include/bits/cpp_type_traits.h (__is_iterator): Add.
	* include/bits/stl_iterator_base_funcs.h (next, prev): Use it.
	* testsuite/24_iterators/operations/40497.cc: New.


git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@159933 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 28 insertions, 0 deletions

diff --git a/libstdc++-v3/include/bits/cpp_type_traits.h b/libstdc++-v3/include/bits/cpp_type_traits.h
index 0d7b9ff09fc..8c5d8e9ca27 100644
--- a/libstdc++-v3/include/bits/cpp_type_traits.h
+++ b/libstdc++-v3/include/bits/cpp_type_traits.h
@@ -414,6 +414,34 @@ _GLIBCXX_BEGIN_NAMESPACE(std)
     };
 #endif
 
+  template<typename _Tp>
+    class __is_iterator_helper
+    {
+      typedef char __one;
+      typedef struct { char __arr[2]; } __two;
+
+      template<typename _Up>
+        struct _Wrap_type
+	{ };
+
+      template<typename _Up>
+        static __one __test(_Wrap_type<typename _Up::iterator_category>*);
+
+      template<typename _Up>
+        static __two __test(...);
+
+    public:
+      static const bool __value = (sizeof(__test<_Tp>(0)) == 1
+				   || __is_pointer<_Tp>::__value);
+    };
+
+  template<typename _Tp>
+    struct __is_iterator
+    {
+      enum { __value = __is_iterator_helper<_Tp>::__value };
+      typedef typename __truth_type<__value>::__type __type;
+    };
+
 _GLIBCXX_END_NAMESPACE
 
 #endif //_CPP_TYPE_TRAITS_H