ceph/src/boost/libs/hana/test/ext/std/pair/issue_90.cpp

   1 // Copyright Louis Dionne 2013-2017
   2 // Distributed under the Boost Software License, Version 1.0.
   3 // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
   4
   5 #include <boost/hana/ext/std/pair.hpp>
   6 #include <boost/hana/first.hpp>
   7 #include <boost/hana/second.hpp>
   8
   9 #include <utility>
  10 namespace hana = boost::hana;
  11
  12
  13 template <typename T>
  14 T const& cref(T& t) { return t; }
  15
  16 // a non-movable, non-copyable type
  17 template <int i>
  18 struct RefOnly {
  19     RefOnly() = default;
  20     RefOnly(RefOnly const&) = delete;
  21     RefOnly(RefOnly&&) = delete;
  22 };
  23
  24 int main() {
  25     // This test makes sure that we return the proper reference types from
  26     // `first` and `second`.
  27     std::pair<RefOnly<0>, RefOnly<1>> p;
  28
  29     {
  30         RefOnly<0>&& r1 = hana::first(std::move(p));
  31         RefOnly<0>& r2 = hana::first(p);
  32         RefOnly<0> const& r3 = hana::first(cref(p));
  33
  34         (void)r1; (void)r2; (void)r3;
  35     }
  36
  37     {
  38         RefOnly<1>&& r1 = hana::second(std::move(p));
  39         RefOnly<1>& r2 = hana::second(p);
  40         RefOnly<1> const& r3 = hana::second(cref(p));
  41
  42         (void)r1; (void)r2; (void)r3;
  43     }
  44 }