1 // 2 // cpp14/require_concept_static.cpp 3 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 4 // 5 // Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com) 6 // 7 // Distributed under the Boost Software License, Version 1.0. (See accompanying 8 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 9 // 10 11 #include <boost/asio/require_concept.hpp> 12 #include <cassert> 13 14 template <int> 15 struct prop 16 { 17 template <typename> static constexpr bool is_applicable_property_v = true; 18 static constexpr bool is_requirable_concept = true; 19 template <typename> static constexpr bool static_query_v = true; valueprop20 static constexpr bool value() { return true; } 21 }; 22 23 template <int> 24 struct object 25 { 26 }; 27 main()28int main() 29 { 30 object<1> o1 = {}; 31 const object<1>& o2 = boost::asio::require_concept(o1, prop<1>()); 32 assert(&o1 == &o2); 33 (void)o2; 34 35 const object<1> o3 = {}; 36 const object<1>& o4 = boost::asio::require_concept(o3, prop<1>()); 37 assert(&o3 == &o4); 38 (void)o4; 39 40 constexpr object<1> o5 = boost::asio::require_concept(object<1>(), prop<1>()); 41 (void)o5; 42 } 43