Call clear before checking for the existence of push_back

[SVN r54949]

include/boost/mpl/aux_/inserter_algorithm.hpp

@@ -49,7 +49,7 @@ template< \
       BOOST_MPL_PP_PARAMS(BOOST_PP_DEC(arity), typename P) \
     > \
 struct name< BOOST_MPL_PP_PARAMS(BOOST_PP_DEC(arity), P),na > \
-    : if_< has_push_back<P1> \
+    : if_< has_push_back< typename clear<P1>::type> \
         , aux::name##_impl< \
               BOOST_MPL_PP_PARAMS(BOOST_PP_DEC(arity), P) \
             , back_inserter< typename clear<P1>::type > \

test/copy.cpp

@@ -20,6 +20,20 @@
 #include <boost/mpl/front_inserter.hpp>
 #include <boost/mpl/size.hpp>
 #include <boost/mpl/equal.hpp>
+#include <boost/mpl/less.hpp>
+
+#include <boost/mpl/begin_end_fwd.hpp>
+#include <boost/mpl/size_fwd.hpp>
+#include <boost/mpl/empty_fwd.hpp>
+#include <boost/mpl/front_fwd.hpp>
+#include <boost/mpl/insert_fwd.hpp>
+#include <boost/mpl/insert_range_fwd.hpp>
+#include <boost/mpl/erase_fwd.hpp>
+#include <boost/mpl/clear_fwd.hpp>
+#include <boost/mpl/push_back_fwd.hpp>
+#include <boost/mpl/pop_back_fwd.hpp>
+#include <boost/mpl/back_fwd.hpp>
+
 #include <boost/mpl/aux_/test.hpp>
 
 MPL_TEST_CASE()
@@ -45,3 +59,153 @@ MPL_TEST_CASE()
     MPL_ASSERT_RELATION( size<result>::value, ==,  20 );
     MPL_ASSERT(( equal< result,range_c<int,0,20> > ));
 }
+
+struct push_back_only_tag {};
+
+template< typename Seq >
+struct push_back_only
+{
+    typedef push_back_only_tag tag;
+    typedef Seq seq;
+};
+
+namespace boost { namespace mpl {
+
+template<>
+struct begin_impl< ::push_back_only_tag >
+{
+    template< typename Seq > struct apply
+        : begin< typename Seq::seq >
+    {
+    };
+};
+
+template<>
+struct end_impl< ::push_back_only_tag >
+{
+    template< typename Seq > struct apply
+        : end< typename Seq::seq >
+    {
+    };
+};
+
+template<>
+struct size_impl< ::push_back_only_tag >
+{
+    template< typename Seq > struct apply
+        : size< typename Seq::seq >
+    {
+    };
+};
+
+template<>
+struct empty_impl< ::push_back_only_tag >
+{
+    template< typename Seq > struct apply
+        : empty< typename Seq::seq >
+    {
+    };
+};
+
+template<>
+struct front_impl< ::push_back_only_tag >
+{
+    template< typename Seq > struct apply
+        : front< typename Seq::seq >
+    {
+    };
+};
+
+template<>
+struct insert_impl< ::push_back_only_tag >
+{
+    template< typename Seq, typename Pos, typename X > struct apply
+    {
+        typedef ::push_back_only<
+            typename insert< typename Seq::seq, Pos, X >::type
+        > type;
+    };
+};
+
+template<>
+struct insert_range_impl< ::push_back_only_tag >
+{
+    template< typename Seq, typename Pos, typename X > struct apply
+    {
+        typedef ::push_back_only<
+            typename insert_range< typename Seq::seq, Pos, X >::type
+        > type;
+    };
+};
+
+template<>
+struct erase_impl< ::push_back_only_tag >
+{
+    template< typename Seq, typename Iter1, typename Iter2 > struct apply
+    {
+        typedef ::push_back_only<
+            typename erase< typename Seq::seq, Iter1, Iter2 >::type
+        > type;
+    };
+};
+
+template<>
+struct clear_impl< ::push_back_only_tag >
+{
+    template< typename Seq > struct apply
+    {
+        typedef ::push_back_only<
+            typename clear< typename Seq::seq >::type
+        > type;
+    };
+};
+
+template<>
+struct push_back_impl< ::push_back_only_tag >
+{
+    template< typename Seq, typename X > struct apply
+    {
+        typedef ::push_back_only<
+            typename push_back< typename Seq::seq, X >::type
+        > type;
+    };
+};
+
+template<>
+struct pop_back_impl< ::push_back_only_tag >
+{
+    template< typename Seq > struct apply
+    {
+        typedef ::push_back_only<
+            typename pop_back< typename Seq::seq >::type
+        > type;
+    };
+};
+
+template<>
+struct back_impl< ::push_back_only_tag >
+{
+    template< typename Seq > struct apply
+        : back< typename Seq::seq >
+    {
+    };
+};
+
+template<>
+struct has_push_back_impl< ::push_back_only_tag >
+{
+    template< typename Seq > struct apply
+        : less< size<Seq>,int_<10> >
+    {
+    };
+};
+
+}}
+
+MPL_TEST_CASE()
+{
+    typedef vector10_c<int,0,1,2,3,4,5,6,7,8,9> numbers;
+    typedef copy< push_back_only< numbers > >::type result;
+
+    MPL_ASSERT((equal< numbers, result >));
+}