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b32b8144 | 1 | // Copyright Louis Dionne 2013-2017 |
7c673cae FG |
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/tuple.hpp> | |
6 | ||
7 | #include <utility> | |
8 | namespace hana = boost::hana; | |
9 | ||
10 | ||
b32b8144 FG |
11 | // Make sure that the tuple(Yn&&...) is not preferred over copy constructors |
12 | // in single-element cases and other similar cases. | |
7c673cae FG |
13 | |
14 | struct Trap1 { | |
15 | Trap1() = default; | |
16 | Trap1(Trap1 const&) = default; | |
17 | Trap1(Trap1&) = default; | |
18 | Trap1(Trap1&&) = default; | |
19 | ||
20 | template <typename X> | |
21 | Trap1(X&&) { | |
22 | static_assert(sizeof(X) && false, | |
23 | "this constructor must not be instantiated"); | |
24 | } | |
25 | }; | |
26 | ||
27 | struct Trap2 { | |
28 | Trap2() = default; | |
29 | Trap2(Trap2 const&) = default; | |
30 | Trap2(Trap2&) = default; | |
31 | Trap2(Trap2&&) = default; | |
32 | ||
33 | template <typename X> | |
34 | Trap2(X) { // not by reference | |
35 | static_assert(sizeof(X) && false, | |
36 | "this constructor must not be instantiated"); | |
37 | } | |
38 | }; | |
39 | ||
b32b8144 FG |
40 | struct Trap3 { |
41 | Trap3() = default; | |
42 | Trap3(Trap3 const&) = default; | |
43 | Trap3(Trap3&) = default; | |
44 | Trap3(Trap3&&) = default; | |
45 | ||
46 | template <typename X> | |
47 | constexpr explicit Trap3(X&&) { // explicit, and constexpr | |
48 | static_assert(sizeof(X) && false, | |
49 | "this constructor must not be instantiated"); | |
50 | } | |
51 | }; | |
52 | ||
53 | struct Trap4 { | |
54 | template <typename Args> | |
55 | constexpr explicit Trap4(Args&&) { | |
56 | static_assert(sizeof(Args) && false, "must never be instantiated"); | |
57 | } | |
58 | ||
59 | Trap4(Trap4 const&) = default; | |
60 | Trap4(Trap4&&) = default; | |
61 | }; | |
62 | ||
7c673cae FG |
63 | int main() { |
64 | { | |
65 | hana::tuple<Trap1> tuple{}; | |
66 | hana::tuple<Trap1> implicit_copy = tuple; | |
67 | hana::tuple<Trap1> explicit_copy(tuple); | |
68 | hana::tuple<Trap1> implicit_move = std::move(tuple); | |
69 | hana::tuple<Trap1> explicit_move(std::move(tuple)); | |
70 | ||
71 | (void)implicit_copy; | |
72 | (void)explicit_copy; | |
73 | (void)implicit_move; | |
74 | (void)explicit_move; | |
75 | } | |
76 | ||
77 | { | |
78 | hana::tuple<Trap2> tuple{}; | |
79 | hana::tuple<Trap2> implicit_copy = tuple; | |
80 | hana::tuple<Trap2> explicit_copy(tuple); | |
81 | hana::tuple<Trap2> implicit_move = std::move(tuple); | |
82 | hana::tuple<Trap2> explicit_move(std::move(tuple)); | |
83 | ||
84 | (void)implicit_copy; | |
85 | (void)explicit_copy; | |
86 | (void)implicit_move; | |
87 | (void)explicit_move; | |
88 | } | |
b32b8144 FG |
89 | |
90 | { | |
91 | hana::tuple<Trap3> tuple{}; | |
92 | hana::tuple<Trap3> implicit_copy = tuple; | |
93 | hana::tuple<Trap3> explicit_copy(tuple); | |
94 | hana::tuple<Trap3> implicit_move = std::move(tuple); | |
95 | hana::tuple<Trap3> explicit_move(std::move(tuple)); | |
96 | ||
97 | (void)implicit_copy; | |
98 | (void)explicit_copy; | |
99 | (void)implicit_move; | |
100 | (void)explicit_move; | |
101 | } | |
102 | ||
103 | // Just defining the structure used to cause a failure, because of the | |
104 | // explicitly defaulted copy-constructor. | |
105 | { | |
106 | struct Foo { | |
107 | Foo() = default; | |
108 | Foo(Foo const&) = default; | |
109 | Foo(Foo&&) = default; | |
110 | hana::tuple<Trap4> t; | |
111 | }; | |
112 | } | |
7c673cae | 113 | } |