ceph/src/boost/libs/hana/test/pair/cnstr.default.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 struct NoDefault {
  15     NoDefault() = delete;
  16     explicit constexpr NoDefault(int) { }
  17 };
  18
  19 struct NoDefault_nonempty {
  20     NoDefault_nonempty() = delete;
  21     explicit constexpr NoDefault_nonempty(int k) : i(k) { }
  22     int i;
  23 };
  24
  25 struct DefaultOnly {
  26     DefaultOnly() = default;
  27     DefaultOnly(DefaultOnly const&) = delete;
  28     DefaultOnly(DefaultOnly&&) = delete;
  29 };
  30
  31 struct NonConstexprDefault {
  32     NonConstexprDefault() { }
  33 };
  34
  35 int main() {
  36     {
  37         hana::pair<float, short*> p;
  38         BOOST_HANA_RUNTIME_CHECK(hana::first(p) == 0.0f);
  39         BOOST_HANA_RUNTIME_CHECK(hana::second(p) == nullptr);
  40     }
  41
  42     // make sure it also works constexpr
  43     {
  44         constexpr hana::pair<float, short*> p;
  45         static_assert(hana::first(p) == 0.0f, "");
  46         static_assert(hana::second(p) == nullptr, "");
  47     }
  48
  49     // make sure the default constructor is not instantiated when the
  50     // members of the pair are not default-constructible
  51     {
  52         using Pair1 = hana::pair<NoDefault, NoDefault>;
  53         Pair1 p1{NoDefault{1}, NoDefault{2}}; (void)p1;
  54         static_assert(!std::is_default_constructible<Pair1>{}, "");
  55
  56         using Pair2 = hana::pair<NoDefault_nonempty, NoDefault_nonempty>;
  57         Pair2 p2{NoDefault_nonempty{1}, NoDefault_nonempty{2}}; (void)p2;
  58         static_assert(!std::is_default_constructible<Pair2>{}, "");
  59     }
  60
  61     // make sure it works when only the default constructor is defined
  62     {
  63         hana::pair<DefaultOnly, DefaultOnly> p;
  64         (void)p;
  65     }
  66
  67     {
  68         hana::pair<NonConstexprDefault, NonConstexprDefault> p;
  69         (void)p;
  70     }
  71 }