ceph/src/boost/libs/hana/test/pair/cnstr.copy.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/assert.hpp>
   6 #include <boost/hana/first.hpp>
   7 #include <boost/hana/pair.hpp>
   8 #include <boost/hana/second.hpp>
   9
  10 #include <type_traits>
  11 namespace hana = boost::hana;
  12
  13
  14 template <typename Target>
  15 struct implicit_to {
  16     constexpr operator Target() const { return Target{}; }
  17 };
  18
  19 struct NoCopy {
  20     NoCopy() = default;
  21     NoCopy(NoCopy const&) = delete;
  22 };
  23
  24 // Note: It is also useful to check with a non-empty class, because that
  25 //       triggers different instantiations due to EBO.
  26 struct NoCopy_nonempty {
  27     NoCopy_nonempty() = default;
  28     NoCopy_nonempty(NoCopy_nonempty const&) = delete;
  29     int i;
  30 };
  31
  32 int main() {
  33     {
  34         typedef std::pair<int, short> P1;
  35         hana::pair<int, short> p1(3, 4);
  36         hana::pair<int, short> p2 = p1;
  37         BOOST_HANA_RUNTIME_CHECK(hana::first(p2) == 3);
  38         BOOST_HANA_RUNTIME_CHECK(hana::second(p2) == 4);
  39     }
  40
  41     static_assert(std::is_trivially_copy_constructible<hana::pair<int, int>>{}, "");
  42
  43     // make sure it also works constexpr
  44     {
  45         constexpr hana::pair<int, short> p1(3, 4);
  46         constexpr hana::pair<int, short> p2 = p1;
  47         static_assert(hana::first(p2) == 3, "");
  48         static_assert(hana::second(p2) == 4, "");
  49     }
  50
  51     // Make sure it works across pair types (pair<T, U> -> pair<U, V>)
  52     {
  53         hana::pair<int, short> p1(3, 4);
  54         hana::pair<double, long> p2 = p1;
  55         BOOST_HANA_RUNTIME_CHECK(hana::first(p2) == 3);
  56         BOOST_HANA_RUNTIME_CHECK(hana::second(p2) == 4);
  57     }
  58     {
  59         struct target1 { };
  60         struct target2 { };
  61         using Target = hana::pair<target1, target2>;
  62
  63         auto p1_ = hana::make_pair(target1{}, target2{});
  64         Target p1(p1_); (void)p1;
  65
  66         auto p2_ = hana::make_pair(implicit_to<target1>{}, target2{});
  67         Target p2(p2_);
  68
  69         auto p3_ = hana::make_pair(target1{}, implicit_to<target2>{});
  70         Target p3(p3_);
  71
  72         auto p4_ = hana::make_pair(implicit_to<target1>{}, implicit_to<target2>{});
  73         Target p4(p4_);
  74     }
  75
  76     // And also constexpr across pair types
  77     {
  78         constexpr hana::pair<int, short> p1(3, 4);
  79         constexpr hana::pair<double, long> p2 = p1;
  80         static_assert(hana::first(p2) == 3, "");
  81         static_assert(hana::second(p2) == 4, "");
  82     }
  83
  84     // Make sure we don't define the copy constructor when it shouldn't be defined.
  85     {
  86         using Pair1 = hana::pair<NoCopy, NoCopy>;
  87         Pair1 pair1;
  88         static_assert(!std::is_copy_constructible<Pair1>::value, "");
  89
  90         using Pair2 = hana::pair<NoCopy_nonempty, NoCopy_nonempty>;
  91         Pair2 pair2;
  92         static_assert(!std::is_copy_constructible<Pair2>::value, "");
  93     }
  94 }