1// Copyright Louis Dionne 2013-2022
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>
11namespace hana = boost::hana;
12
13
14template <typename Target>
15struct implicit_to {
16 constexpr operator Target() const { return Target{}; }
17};
18
19struct 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.
26struct NoCopy_nonempty {
27 NoCopy_nonempty() = default;
28 NoCopy_nonempty(NoCopy_nonempty const&) = delete;
29 int i;
30};
31
32int 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_); (void)p2;
68
69 auto p3_ = hana::make_pair(target1{}, implicit_to<target2>{});
70 Target p3(p3_); (void)p3;
71
72 auto p4_ = hana::make_pair(implicit_to<target1>{}, implicit_to<target2>{});
73 Target p4(p4_); (void)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; (void)pair1;
88 static_assert(!std::is_copy_constructible<Pair1>::value, "");
89
90 using Pair2 = hana::pair<NoCopy_nonempty, NoCopy_nonempty>;
91 Pair2 pair2; (void)pair2;
92 static_assert(!std::is_copy_constructible<Pair2>::value, "");
93 }
94}
95

source code of boost/libs/hana/test/pair/cnstr.copy.cpp