// // cpp14/can_prefer_not_preferable_free_prefer.cpp // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ // // Copyright (c) 2003-2024 Christopher M. Kohlhoff (chris at kohlhoff dot com) // // Distributed under the Boost Software License, Version 1.0. (See accompanying // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) // #include "asio/prefer.hpp" #include template struct prop { template static constexpr bool is_applicable_property_v = true; static constexpr bool is_preferable = false; }; template struct object { template friend constexpr object prefer(const object&, prop) { return object(); } }; int main() { static_assert(!asio::can_prefer_v, prop<2>>, ""); static_assert(!asio::can_prefer_v, prop<2>, prop<3>>, ""); static_assert(!asio::can_prefer_v, prop<2>, prop<3>, prop<4>>, ""); static_assert(!asio::can_prefer_v, prop<2>>, ""); static_assert(!asio::can_prefer_v, prop<2>, prop<3>>, ""); static_assert(!asio::can_prefer_v, prop<2>, prop<3>, prop<4>>, ""); }