1 //
2 // cpp11/prefer_unsupported.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/prefer.hpp>
12 #include <cassert>
13
14 template <int>
15 struct prop
16 {
17 static constexpr bool is_preferable = true;
18 };
19
20 template <int>
21 struct object
22 {
23 };
24
25 namespace boost {
26 namespace asio {
27
28 template<int N, int M>
29 struct is_applicable_property<object<N>, prop<M> >
30 {
31 static constexpr bool value = true;
32 };
33
34 } // namespace asio
35 } // namespace boost
36
main()37 int main()
38 {
39 object<1> o1 = {};
40 object<1> o2 = boost::asio::prefer(o1, prop<2>());
41 object<1> o3 = boost::asio::prefer(o1, prop<2>(), prop<3>());
42 object<1> o4 = boost::asio::prefer(o1, prop<2>(), prop<3>(), prop<4>());
43 (void)o2;
44 (void)o3;
45 (void)o4;
46
47 const object<1> o5 = {};
48 object<1> o6 = boost::asio::prefer(o5, prop<2>());
49 object<1> o7 = boost::asio::prefer(o5, prop<2>(), prop<3>());
50 object<1> o8 = boost::asio::prefer(o5, prop<2>(), prop<3>(), prop<4>());
51 (void)o6;
52 (void)o7;
53 (void)o8;
54
55 constexpr object<1> o9 = boost::asio::prefer(object<1>(), prop<2>());
56 constexpr object<1> o10 = boost::asio::prefer(object<1>(), prop<2>(), prop<3>());
57 constexpr object<1> o11 = boost::asio::prefer(object<1>(), prop<2>(), prop<3>(), prop<4>());
58 (void)o9;
59 (void)o10;
60 (void)o11;
61 }
62