ceph/src/boost/libs/spirit/test/x3/unused_type.cpp

   1 /*=============================================================================
   2     Copyright (c) 2019 Nikita Kniazev
   3
   4     Use, modification and distribution is subject to the Boost Software
   5     License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   6     http://www.boost.org/LICENSE_1_0.txt)
   7 =============================================================================*/
   8
   9 #include <boost/spirit/home/x3/support/unused.hpp>
  10 #include <type_traits>
  11 #include <iostream>
  12
  13 void test_use(boost::spirit::x3::unused_type) {}
  14
  15 int main()
  16 {
  17     using boost::spirit::x3::unused;
  18     using boost::spirit::x3::unused_type;
  19
  20     static_assert(std::is_trivial<unused_type>::value, "");
  21
  22     unused_type unused_mut;
  23     static_assert(std::is_same<decltype((unused)), unused_type const&>::value, "");
  24     static_assert(std::is_same<decltype((unused_mut)), unused_type&>::value, "");
  25     static_assert(std::is_same<decltype(unused = 123), unused_type const&>::value, "");
  26     static_assert(std::is_same<decltype(unused = unused), unused_type const&>::value, "");
  27     static_assert(std::is_same<decltype(unused = unused_mut), unused_type const&>::value, "");
  28     static_assert(std::is_same<decltype(unused_mut = 123), unused_type&>::value, "");
  29     static_assert(std::is_same<decltype(unused_mut = unused), unused_type&>::value, "");
  30     static_assert(std::is_same<decltype(unused_mut = unused_mut), unused_type&>::value, "");
  31
  32     test_use(0);
  33     test_use(unused);
  34     test_use(unused_mut);
  35
  36     std::cout << unused;
  37     std::cout << unused_mut;
  38     std::cin >> unused_mut;
  39 }