Ticket #2640: counting_iterator.hpp.patch

./VC/boost_1_42_0/boost/iterator/counting_iterator.hpp

@@ -108 +107 @@
                  // criterion (see boost/iterator/detail/facade_iterator_category.hpp)
 # endif 
         , traversal
-        , Incrementable const&                                    // reference
+        , Incrementable                                                                                 // reference
+                // boost ticket #2640: counting_iterator::reference lifetime tied to iterator
+                // Counting_iterators must return copies because they only keep their current value in memory
+                // Otherwise the following doesn't work:
+                //              counting_iterator a;
+                //              counting_iterator b=a;
+                //              return *(--b);
+                // This will return a reference to the Incrementable member of local variable b. reverse_iterator does just that.
         , difference
       > type;
   };