ceph/src/boost/libs/hana/test/ext/std/tuple/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/at.hpp>
   6 #include <boost/hana/at_key.hpp>
   7 #include <boost/hana/back.hpp>
   8 #include <boost/hana/ext/std/tuple.hpp>
   9 #include <boost/hana/front.hpp>
  10 #include <boost/hana/integral_constant.hpp>
  11
  12 #include <tuple>
  13 #include <utility>
  14 namespace hana = boost::hana;
  15
  16
  17 template <typename T>
  18 T const& cref(T& t) { return t; }
  19
  20 // a non-movable, non-copyable type
  21 struct RefOnly {
  22     RefOnly() = default;
  23     RefOnly(RefOnly const&) = delete;
  24     RefOnly(RefOnly&&) = delete;
  25 };
  26
  27 template <int i>
  28 struct RefOnly_i : hana::int_<i> {
  29     RefOnly_i() = default;
  30     RefOnly_i(RefOnly_i const&) = delete;
  31     RefOnly_i(RefOnly_i&&) = delete;
  32 };
  33
  34 int main() {
  35     std::tuple<RefOnly> t;
  36
  37     // Make sure that we return the proper reference types from `at`.
  38     {
  39         RefOnly&& r1 = hana::at_c<0>(std::move(t));
  40         RefOnly& r2 = hana::at_c<0>(t);
  41         RefOnly const& r3 = hana::at_c<0>(cref(t));
  42
  43         (void)r1; (void)r2; (void)r3;
  44     }
  45
  46     // Make sure we return the proper reference types from `front`.
  47     {
  48         RefOnly&& r1 = hana::front(std::move(t));
  49         RefOnly& r2 = hana::front(t);
  50         RefOnly const& r3 = hana::front(cref(t));
  51
  52         (void)r1; (void)r2; (void)r3;
  53     }
  54
  55     // Make sure we return the proper reference types from `back`.
  56     {
  57         RefOnly&& r1 = hana::back(std::move(t));
  58         RefOnly& r2 = hana::back(t);
  59         RefOnly const& r3 = hana::back(cref(t));
  60
  61         (void)r1; (void)r2; (void)r3;
  62     }
  63
  64     // Make sure we return the proper reference types from `at_key`.
  65     {
  66         std::tuple<RefOnly_i<3>> t{};
  67         RefOnly_i<3>& r1 = hana::at_key(t, RefOnly_i<3>{});
  68         RefOnly_i<3> const& r2 = hana::at_key(cref(t), RefOnly_i<3>{});
  69         RefOnly_i<3>&& r3 = hana::at_key(std::move(t), RefOnly_i<3>{});
  70
  71         (void)r1; (void)r2; (void)r3;
  72     }
  73 }