better auto_ptr support

[SVN r17592]

include/boost/python/detail/copy_ctor_mutates_rhs.hpp

@@ -0,0 +1,64 @@
+// Copyright David Abrahams 2003. Permission to copy, use,
+// modify, sell and distribute this software is granted provided this
+// copyright notice appears in all copies. This software is provided
+// "as is" without express or implied warranty, and with no claim as
+// to its suitability for any purpose.
+#include <boost/mpl/bool_c.hpp>
+#ifndef BOOST_NO_AUTO_PTR
+# include <memory>
+#endif 
+
+#ifndef COPY_CTOR_MUTATES_RHS_DWA2003219_HPP
+# define COPY_CTOR_MUTATES_RHS_DWA2003219_HPP
+
+namespace boost { namespace python { namespace detail { 
+
+# if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) && !defined(BOOST_NO_AUTO_PTR)
+
+template <class T>
+struct is_auto_ptr
+{
+    typedef char yes;
+    typedef char (&no)[2];
+
+    static
+    T& f();
+
+    template <class U>
+    static yes test(std::auto_ptr<U>&, int);
+
+    template <class U>
+    static no test(U&, ...);
+    
+    BOOST_STATIC_CONSTANT(
+        bool, value = sizeof(test(f(), 0)) == sizeof(yes));
+
+    typedef mpl::bool_c<value> type;
+                              
+};
+
+# else
+
+template <class T>
+struct is_auto_ptr : mpl::false_c
+{
+};
+
+#  if !defined(BOOST_NO_AUTO_PTR)
+template <class T>
+struct is_auto_ptr<std::auto_ptr<T> > : mpl::true_c
+{
+};
+
+#  endif
+# endif
+
+template <class T>
+struct copy_ctor_mutates_rhs
+    : is_auto_ptr<T>
+{
+};
+
+}}} // namespace boost::python::detail
+
+#endif // COPY_CTOR_MUTATES_RHS_DWA2003219_HPP

include/boost/python/extract.hpp

@@ -11,12 +11,13 @@
 # include <boost/python/converter/rvalue_from_python_data.hpp>
 # include <boost/python/converter/registered.hpp>
 # include <boost/python/converter/registered_pointee.hpp>
-# include <boost/python/detail/void_ptr.hpp>
 # include <boost/call_traits.hpp>
-# include <boost/python/detail/void_return.hpp>
 # include <boost/python/object_core.hpp>
 # include <boost/python/refcount.hpp>
 # include <boost/utility.hpp>
+# include <boost/python/detail/copy_ctor_mutates_rhs.hpp>
+# include <boost/python/detail/void_ptr.hpp>
+# include <boost/python/detail/void_return.hpp>
 
 namespace boost { namespace python {
 
@@ -53,7 +54,12 @@ namespace converter
   template <class T>
   struct extract_rvalue : private noncopyable
   {
-      typedef typename call_traits<T>::param_type result_type;
+      typedef typename mpl::if_<
+          python::detail::copy_ctor_mutates_rhs<T>
+        , T&
+        , typename call_traits<T>::param_type
+      >::type result_type;
+
       extract_rvalue(PyObject*);
 
       bool check() const;