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;

test/auto_ptr.cpp

@@ -66,10 +66,17 @@ BOOST_PYTHON_MODULE(auto_ptr_ext)
         .def("value", &X::value)
         ;
     
-    class_<Y, std::auto_ptr<Y>, bases<X>, boost::noncopyable>("X", init<int>())
+    class_<Y, std::auto_ptr<Y>, bases<X>, boost::noncopyable>("Y", init<int>())
         ;
 
+    // VC6 auto_ptrs do not have converting constructors    
+#if defined(BOOST_MSVC_STD_ITERATOR)
+    scope().attr("broken_auto_ptr") = 1;
+#else
+    scope().attr("broken_auto_ptr") = 0;
     implicitly_convertible<std::auto_ptr<Y>, std::auto_ptr<X> >();
+#endif
+    
     def("look", look);
     def("steal", steal);
     def("maybe_steal", maybe_steal);

test/auto_ptr.py

@@ -13,13 +13,13 @@
 
 >>> maybe_steal(x, 1)
 42
->>> (not '--broken-auto-ptr' in sys.argv) and look(x) or -1
+>>> broken_auto_ptr and -1 or look(x)
 -1
 
 >>> x = X(69)
 >>> steal(x)
 69
->>> (not '--broken-auto-ptr' in sys.argv) and look(x) or -1
+>>> broken_auto_ptr and -1 or look(x)
 -1
 
 >>> if not '--broken-auto-ptr' in sys.argv:
@@ -46,9 +46,6 @@
 >>> y.value()
 42
 
->>> maybe_steal(y, 0)
-42
-
 >>> try: maybe_steal(y, 0)
 ... except TypeError: pass
 ... else: print 'expected a TypeError exception'
@@ -56,10 +53,10 @@
 >>> y.value()
 42
 
->>> steal(y)
+>>> broken_auto_ptr and 42 or steal(y)
 42
 
->>> if not '--broken-auto-ptr' in sys.argv:
+>>> if not broken_auto_ptr:
 ...     try: y.value()
 ...     except TypeError: pass
 ...     else: print 'expected a TypeError exception'

test/copy_ctor_mutates_rhs.cpp

@@ -0,0 +1,23 @@
+// 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/python/detail/copy_ctor_mutates_rhs.hpp>
+#include <boost/static_assert.hpp>
+#include <memory>
+#include <string>
+
+struct foo
+{
+    operator std::auto_ptr<int>&() const;
+};
+
+int main()
+{
+    using namespace boost::python::detail;
+    BOOST_STATIC_ASSERT(!copy_ctor_mutates_rhs<int>::value);
+    BOOST_STATIC_ASSERT(copy_ctor_mutates_rhs<std::auto_ptr<int> >::value);
+    BOOST_STATIC_ASSERT(!copy_ctor_mutates_rhs<std::string>::value);
+    BOOST_STATIC_ASSERT(!copy_ctor_mutates_rhs<foo>::value);
+}