diff -Naur boost_1_47_0-orig/boost/ptr_container/detail/void_ptr_iterator.hpp boost_1_47_0/boost/ptr_container/detail/void_ptr_iterator.hpp
--- boost_1_47_0-orig/boost/ptr_container/detail/void_ptr_iterator.hpp	2011-09-29 14:51:31.860893983 +0100
+++ boost_1_47_0/boost/ptr_container/detail/void_ptr_iterator.hpp	2011-09-30 11:38:28.785314034 +0100
@@ -161,8 +161,22 @@
             return r;
         }
 
+
+        namespace ptr_container_detail
+        {
+            template<typename T, typename U>
+            struct is_compatible
+            {
+                static const bool value = boost::is_same< typename boost::remove_const<T>::type, typename boost::remove_const<U>::type >::value;
+            };
+        }
+
+          
         template< class VoidIter, class T, class VoidIterU, class U >
-        inline BOOST_DEDUCED_TYPENAME void_ptr_iterator<VoidIter,T>::difference_type
+        inline BOOST_DEDUCED_TYPENAME boost::enable_if<
+            ptr_container_detail::is_compatible<T, U>,
+            BOOST_DEDUCED_TYPENAME void_ptr_iterator<VoidIter,T>::difference_type
+        >::type
         operator-( void_ptr_iterator<VoidIter,T> l,
                    void_ptr_iterator<VoidIterU,U> r ) 
 
@@ -173,7 +187,11 @@
 
 
         template< class VoidIterT, class T, class VoidIterU, class U >
-        inline bool operator==( const void_ptr_iterator<VoidIterT,T>& l,
+        inline BOOST_DEDUCED_TYPENAME boost::enable_if<
+            ptr_container_detail::is_compatible<T, U>,
+            bool
+        >::type
+        operator==( const void_ptr_iterator<VoidIterT,T>& l,
                                 const void_ptr_iterator<VoidIterU,U>& r )
         {
             return l.base() == r.base();
@@ -182,7 +200,11 @@
 
         
         template< class VoidIterT, class T, class VoidIterU, class U >
-        inline bool operator!=( const void_ptr_iterator<VoidIterT,T>& l,
+        inline BOOST_DEDUCED_TYPENAME boost::enable_if<
+            ptr_container_detail::is_compatible<T, U>,
+            bool
+        >::type
+        operator!=( const void_ptr_iterator<VoidIterT,T>& l,
                                 const void_ptr_iterator<VoidIterU,U>& r )
         {
             return l.base() != r.base();
@@ -191,7 +213,11 @@
 
 
         template< class VoidIterT, class T, class VoidIterU, class U >
-        inline bool operator<( const void_ptr_iterator<VoidIterT,T>& l,
+        inline BOOST_DEDUCED_TYPENAME boost::enable_if<
+            ptr_container_detail::is_compatible<T, U>,
+            bool
+        >::type
+        operator<( const void_ptr_iterator<VoidIterT,T>& l,
                                const void_ptr_iterator<VoidIterU,U>& r )
         {
             return l.base() < r.base();
@@ -200,7 +226,11 @@
 
         
         template< class VoidIterT, class T, class VoidIterU, class U >
-        inline bool operator<=( const void_ptr_iterator<VoidIterT,T>& l,
+        inline BOOST_DEDUCED_TYPENAME boost::enable_if<
+            ptr_container_detail::is_compatible<T, U>,
+            bool
+        >::type
+        operator<=( const void_ptr_iterator<VoidIterT,T>& l,
                                const void_ptr_iterator<VoidIterU,U>& r )
         {
             return l.base() <= r.base();
@@ -209,7 +239,11 @@
 
         
         template< class VoidIterT, class T, class VoidIterU, class U >
-        inline bool operator>( const void_ptr_iterator<VoidIterT,T>& l,
+        inline BOOST_DEDUCED_TYPENAME boost::enable_if<
+            ptr_container_detail::is_compatible<T, U>,
+            bool
+        >::type
+        operator>( const void_ptr_iterator<VoidIterT,T>& l,
                                const void_ptr_iterator<VoidIterU,U>& r )
         {
             return l.base() > r.base();
@@ -218,7 +252,11 @@
 
         
         template< class VoidIterT, class T, class VoidIterU, class U >
-        inline bool operator>=( const void_ptr_iterator<VoidIterT,T>& l,
+        inline BOOST_DEDUCED_TYPENAME boost::enable_if<
+            ptr_container_detail::is_compatible<T, U>,
+            bool
+        >::type
+        operator>=( const void_ptr_iterator<VoidIterT,T>& l,
                                const void_ptr_iterator<VoidIterU,U>& r )
         {
             return l.base() >= r.base();