trac 5816 - fix any_range requiring copyable elements.

include/boost/range/detail/any_iterator_interface.hpp

@@ -27,25 +27,40 @@ namespace boost
         {
             typedef typename mpl::if_<
                 typename is_reference<T>::type,
-                typename add_reference<
+                typename add_const<
-                    typename add_const<
+                    typename remove_reference<T>::type
-                        typename remove_reference<T>::type
+                >::type&,
-                    >::type
-                >::type,
                 T
             >::type type;
         };
 
+        template<class T>
+        struct mutable_reference_type_generator
+        {
+            typedef typename mpl::if_<
+                typename mpl::and_<
+                    typename is_const<T>::type,
+                    typename mpl::not_<typename is_reference<T>::type>::type
+                >::type,
+                T,
+                typename add_reference<T>::type
+            >::type type;
+        };
+
         template<
             class Reference
           , class Buffer
         >
         struct any_incrementable_iterator_interface
         {
-            typedef Reference reference;
+            typedef typename mutable_reference_type_generator<
+                Reference
+            >::type reference;
+
             typedef typename const_reference_type_generator<
                 Reference
             >::type const_reference;
+
             typedef typename remove_const<
                 typename remove_reference<Reference>::type
             >::type reference_as_value_type;
@@ -87,7 +102,7 @@ namespace boost
             virtual any_single_pass_iterator_interface<reference_as_value_type, Buffer>*
                         clone_reference_as_value(buffer_type& buffer) const = 0;
 
-            virtual Reference dereference() const = 0;
+            virtual reference dereference() const = 0;
 
             virtual bool equal(const any_single_pass_iterator_interface& other) const = 0;
         };

include/boost/range/detail/any_iterator_wrapper.hpp

@@ -19,6 +19,17 @@ namespace boost
 {
     namespace range_detail
     {
+        template<class Reference, class T>
+        Reference dereference_cast(T& x)
+        {
+            return static_cast<Reference>(x);
+        }
+        template<class Reference, class T>
+        Reference dereference_cast(const T& x)
+        {
+            return static_cast<Reference>(const_cast<T&>(x));
+        }
+
         template<
             class WrappedIterator
           , class Reference
@@ -114,7 +125,13 @@ namespace boost
         {
             struct disabler {};
             BOOST_RANGE_CONCEPT_ASSERT(( SinglePassIteratorConcept<WrappedIterator> ));
+            typedef any_single_pass_iterator_interface<
+                Reference,
+                Buffer
+            > base_type;
+
         public:
+            typedef typename base_type::reference reference;
 
             any_single_pass_iterator_wrapper()
                 : m_it()
@@ -178,9 +195,9 @@ namespace boost
                 return m_it == boost::polymorphic_downcast<const any_single_pass_iterator_wrapper*>(&other)->m_it;
             }
 
-            virtual Reference dereference() const
+            virtual reference dereference() const
             {
-                return *m_it;
+                return dereference_cast<reference>(*m_it);
             }
 
         private:
@@ -199,7 +216,14 @@ namespace boost
                     >
         {
             BOOST_RANGE_CONCEPT_ASSERT(( ForwardIteratorConcept<WrappedIterator> ));
+            typedef any_forward_iterator_interface<
+                Reference,
+                Buffer
+            > base_type;
+
         public:
+            typedef typename base_type::reference reference;
+
             any_forward_iterator_wrapper()
                 : m_it()
             {}
@@ -263,9 +287,9 @@ namespace boost
                 return m_it == boost::polymorphic_downcast<const any_forward_iterator_wrapper*>(&other)->m_it;
             }
 
-            virtual Reference dereference() const
+            virtual reference dereference() const
             {
-                return *m_it;
+                return dereference_cast<reference>(*m_it);
             }
         private:
             WrappedIterator m_it;
@@ -283,7 +307,14 @@ namespace boost
                     >
         {
             BOOST_RANGE_CONCEPT_ASSERT(( BidirectionalIteratorConcept<WrappedIterator> ));
+            typedef any_bidirectional_iterator_interface<
+                Reference,
+                Buffer
+            > base_type;
+
         public:
+            typedef typename base_type::reference reference;
+
             any_bidirectional_iterator_wrapper()
                 : m_it()
             {
@@ -353,9 +384,9 @@ namespace boost
                 return m_it == boost::polymorphic_downcast<const any_bidirectional_iterator_wrapper*>(&other)->m_it;
             }
 
-            virtual Reference dereference() const
+            virtual reference dereference() const
             {
-                return *m_it;
+                return dereference_cast<reference>(*m_it);
             }
 
         private:
@@ -376,7 +407,14 @@ namespace boost
                         >
         {
             BOOST_RANGE_CONCEPT_ASSERT(( RandomAccessIteratorConcept<WrappedIterator> ));
+            typedef any_random_access_iterator_interface<
+                Reference,
+                Difference,
+                Buffer
+            > base_type;
+
         public:
+            typedef typename base_type::reference reference;
             typedef Difference difference_type;
 
             any_random_access_iterator_wrapper()
@@ -457,9 +495,9 @@ namespace boost
                 m_it += offset;
             }
 
-            virtual Reference dereference() const
+            virtual reference dereference() const
             {
-                return *m_it;
+                return dereference_cast<reference>(*m_it);
             }
 
             virtual Difference distance_to(const any_random_access_iterator_interface<Reference, Difference, Buffer>& other) const

test/adaptor_test/type_erased.cpp

@@ -476,6 +476,60 @@ namespace boost_range_adaptor_type_erased_test
             BOOST_CHECK_EQUAL( rng[i], i );
         }
     }
+
+    class dummy_interface
+    {
+    public:
+        virtual ~dummy_interface() { }
+        virtual void test() = 0;
+    protected:
+        dummy_interface() { }
+    private:
+        dummy_interface(const dummy_interface&);
+        void operator=(const dummy_interface&);
+    };
+
+    class dummy_impl
+        : public dummy_interface
+    {
+    public:
+        dummy_impl() { }
+        dummy_impl(const dummy_impl&) { }
+        dummy_impl& operator=(const dummy_impl&) { return *this; }
+        virtual void test() { }
+    };
+
+    typedef boost::any_range<
+        dummy_interface,
+        boost::random_access_traversal_tag,
+        dummy_interface&,
+        std::ptrdiff_t
+    > any_interface_range;
+
+    struct foo_dummy_interface_fn
+    {
+        void operator()(dummy_interface& iface)
+        {
+            iface.test();
+        }
+    };
+
+    void foo_test_dummy_interface_range(any_interface_range rng)
+    {
+        std::for_each(boost::begin(rng), boost::end(rng),
+                      foo_dummy_interface_fn());
+    }
+
+    void test_type_erased_abstract()
+    {
+        std::vector<dummy_impl> v(10);
+
+        any_interface_range r(v);
+
+        foo_test_dummy_interface_range(r);
+        
+        foo_test_dummy_interface_range(any_interface_range(v));
+    }
 }
 
 boost::unit_test::test_suite*
@@ -492,6 +546,7 @@ init_unit_test_suite(int argc, char* argv[])
     test->add( BOOST_TEST_CASE( &boost_range_adaptor_type_erased_test::test_type_erased_multiple_different_template_parameter_conversion ) );
     test->add( BOOST_TEST_CASE( &boost_range_adaptor_type_erased_test::test_type_erased_mix_values ) );
     test->add( BOOST_TEST_CASE( &boost_range_adaptor_type_erased_test::test_type_erased_operator_brackets ) );
+    test->add( BOOST_TEST_CASE( &boost_range_adaptor_type_erased_test::test_type_erased_abstract ) );
 
     return test;
 }