+# if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
+
+ template<typename From, typename To>
+ struct enable_if_convertible
+ {
+ typedef typename mpl::if_<
+ mpl::or_<
+ is_same<From,To>
+ , is_convertible<From, To>
+ >
+ , boost::detail::enable_type
+ , int&
+ >::type type;
+ };
+
+# elif defined(BOOST_NO_IS_CONVERTIBLE) || defined(BOOST_NO_SFINAE)