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/config.hpp>
7 #include <boost/hana/first.hpp>
8 #include <boost/hana/pair.hpp>
9 #include <boost/hana/second.hpp>
10
11 #include <utility>
12 namespace hana = boost::hana;
13
14
15 struct MoveOnly {
16 int data_;
17 MoveOnly(MoveOnly const&) = delete;
18 MoveOnly& operator=(MoveOnly const&) = delete;
MoveOnlyMoveOnly19 MoveOnly(int data = 1) : data_(data) { }
MoveOnlyMoveOnly20 MoveOnly(MoveOnly&& x) : data_(x.data_) { x.data_ = 0; }
21
operator =MoveOnly22 MoveOnly& operator=(MoveOnly&& x)
23 { data_ = x.data_; x.data_ = 0; return *this; }
24
operator ==MoveOnly25 bool operator==(const MoveOnly& x) const { return data_ == x.data_; }
26 };
27
28 struct MoveOnlyDerived : MoveOnly {
29 MoveOnlyDerived(MoveOnlyDerived&&) = default;
MoveOnlyDerivedMoveOnlyDerived30 MoveOnlyDerived(int data = 1) : MoveOnly(data) { }
31 };
32
in_constexpr_context(int a,short b)33 constexpr auto in_constexpr_context(int a, short b) {
34 hana::pair<int, short> p1(a, b);
35 hana::pair<int, short> p2;
36 hana::pair<double, long> p3;
37 p2 = std::move(p1);
38 p3 = std::move(p2);
39 return p3;
40 }
41
main()42 int main() {
43 // from pair<T, U> to pair<T, U>
44 {
45 hana::pair<MoveOnly, short> p1(MoveOnly{3}, 4);
46 hana::pair<MoveOnly, short> p2;
47 p2 = std::move(p1);
48 BOOST_HANA_RUNTIME_CHECK(hana::first(p2) == MoveOnly{3});
49 BOOST_HANA_RUNTIME_CHECK(hana::second(p2) == 4);
50 }
51
52 // from pair<T, U> to pair<V, W>
53 {
54 hana::pair<MoveOnlyDerived, short> p1(MoveOnlyDerived{3}, 4);
55 hana::pair<MoveOnly, long> p2;
56 p2 = std::move(p1);
57 BOOST_HANA_RUNTIME_CHECK(hana::first(p2) == MoveOnly{3});
58 BOOST_HANA_RUNTIME_CHECK(hana::second(p2) == 4);
59 }
60
61 // make sure that also works in a constexpr context
62 // (test fails under GCC <= 6 due to buggy constexpr)
63 #if BOOST_HANA_CONFIG_GCC >= BOOST_HANA_CONFIG_VERSION(7, 0, 0)
64 {
65 constexpr auto p = in_constexpr_context(3, 4);
66 static_assert(hana::first(p) == 3, "");
67 static_assert(hana::second(p) == 4, "");
68 }
69 #endif
70 }
71