// Copyright (C) 2003, Fernando Luis Cacciola Carballal.
-// Copyright (C) 2014 Andrzej Krzemienski.
+// Copyright (C) 2014, 2015 Andrzej Krzemienski.
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
namespace boost {
#ifdef BOOST_OPTIONAL_USE_OLD_DEFINITION_OF_NONE
+
none_t const none = (static_cast<none_t>(0)) ;
-#else
+
+#elif defined BOOST_OPTIONAL_USE_SINGLETON_DEFINITION_OF_NONE
namespace detail { namespace optional_detail {
const none_t& none = detail::optional_detail::none_instance<none_t>::instance;
}
-#endif
+#else
+
+const none_t none ((none_t::init_tag()));
+
+#endif // older definitions
} // namespace boost
-#endif
+#endif // header guard