Boost.Range defect fix for the operator[] of iterator_range. This now reverts to a simpler implementation when the iterator is a pointer.

[SVN r61258]

include/boost/range/iterator_range_core.hpp

@@ -298,13 +298,21 @@ namespace boost
                return m_Begin[at];
            }
 #else
+            // Using the operator_brackets_result mechanism properly supports
+            // the corner cases with proxies for references etc. However
+            // the operator_brackets_result implementation does not support
+            // pointers as iterators. Since a pointer can't have the
+            // issues with proxies this implementation uses a simpler
+            // implementation if the iterator is a pointer.
+            BOOST_DEDUCED_TYPENAME boost::mpl::if_<
+                boost::is_pointer<iterator>,
+                reference,
                 BOOST_DEDUCED_TYPENAME boost::detail::operator_brackets_result<iterator, value_type, reference>::type
+            >::type
             operator[]( difference_type at ) const
             {
                 BOOST_ASSERT( at >= 0 && at < size() );
-
-               typedef boost::detail::use_operator_brackets_proxy<value_type,reference> use_proxy;
-               return boost::detail::make_operator_brackets_result<iterator>(m_Begin + at, use_proxy());
+                return get_at(m_Begin, at);
             }
 #endif
 
@@ -332,6 +340,27 @@ namespace boost
            }
 
         private:
+            template<class Iterator>
+            static BOOST_DEDUCED_TYPENAME boost::enable_if<
+                boost::is_pointer<Iterator>,
+                reference
+                >::type
+            get_at( Iterator it, difference_type at )
+            {
+                return it[at];
+            }
+
+            template<class Iterator>
+            static BOOST_DEDUCED_TYPENAME boost::disable_if<
+                boost::is_pointer<Iterator>,
+                BOOST_DEDUCED_TYPENAME boost::detail::operator_brackets_result<Iterator, value_type, reference>::type
+                >::type
+            get_at( Iterator it, difference_type at )
+            {
+               typedef boost::detail::use_operator_brackets_proxy<value_type,reference> use_proxy;
+               return boost::detail::make_operator_brackets_result<Iterator>(it + at, use_proxy());
+            }
+
             // begin and end iterators
             IteratorT m_Begin;
             IteratorT m_End;

test/Jamfile.v2

@@ -133,6 +133,7 @@ test-suite range :
 #   	[ range-test mfc : <include>$(VC71_ROOT)/atlmfc/include ]
     [ range-test join ]
 	[ range-test partial_workaround ]
+	[ range-test pointer_as_iterator ]
 	[ range-test reversible_range ]
 	[ range-test std_container ]
 	[ range-test string ]

test/pointer_as_iterator.cpp

@@ -0,0 +1,39 @@
+// Boost.Range library
+//
+//  Copyright Neil Groves 2010. Use, modification and
+//  distribution is subject to the Boost Software License, Version
+//  1.0. (See accompanying file LICENSE_1_0.txt or copy at
+//  http://www.boost.org/LICENSE_1_0.txt)
+//
+//
+// For more information, see http://www.boost.org/libs/range/
+//
+#include <boost/range/iterator_range.hpp>
+#include <boost/range/begin.hpp>
+#include <boost/range/end.hpp>
+#include <boost/array.hpp>
+#include <boost/test/test_tools.hpp>
+#include <boost/test/unit_test.hpp>
+#include <iostream>
+#include <vector>
+
+namespace
+{
+    void test_pointer_as_iterator()
+    {
+        boost::array<int,3> arr;
+        boost::iterator_range<const int*> r(arr.begin(), arr.end());
+        r[0];
+    }
+} // anonymous namespace
+
+boost::unit_test::test_suite*
+init_unit_test_suite(int argc, char* argv[])
+{
+    boost::unit_test::test_suite* test
+        = BOOST_TEST_SUITE( "RangeTestSuite.pointer_as_iterator" );
+
+    test->add(BOOST_TEST_CASE( &test_pointer_as_iterator ));
+
+    return test;
+}