1
2 // Copyright 2017 Peter Dimov.
3 //
4 // Distributed under the Boost Software License, Version 1.0.
5 //
6 // See accompanying file LICENSE_1_0.txt or copy at
7 // http://www.boost.org/LICENSE_1_0.txt
8
9 #include <boost/variant2/variant.hpp>
10 #include <utility>
11
12 using namespace boost::variant2;
13
14 struct X
15 {
16 int v;
17 X() = default;
XX18 constexpr X( int v ): v( v ) {}
operator intX19 constexpr operator int() const { return v; }
20 };
21
22 struct Y
23 {
24 int v;
YY25 constexpr Y(): v() {}
YY26 constexpr Y( int v ): v( v ) {}
operator intY27 constexpr operator int() const { return v; }
28 };
29
30 enum E
31 {
32 v
33 };
34
35 #define STATIC_ASSERT(...) static_assert(__VA_ARGS__, #__VA_ARGS__)
36
test(A && a)37 template<class V, class T, class A> constexpr T test( A&& a )
38 {
39 V v;
40
41 v = std::forward<A>(a);
42
43 return get<T>(v);
44 }
45
main()46 int main()
47 {
48 {
49 constexpr auto w = test<variant<int>, int>( variant<int>( 1 ) );
50 STATIC_ASSERT( w == 1 );
51 }
52
53 {
54 constexpr auto w = test<variant<X>, X>( variant<X>( 1 ) );
55 STATIC_ASSERT( w == 1 );
56 }
57
58 #if defined( BOOST_LIBSTDCXX_VERSION ) && BOOST_LIBSTDCXX_VERSION < 50000
59 #else
60
61 {
62 constexpr auto w = test<variant<Y>, Y>( variant<Y>( 1 ) );
63 STATIC_ASSERT( w == 1 );
64 }
65
66 #endif
67
68 {
69 constexpr auto w = test<variant<int, float>, int>( variant<int, float>( 1 ) );
70 STATIC_ASSERT( w == 1 );
71 }
72
73 {
74 constexpr auto w = test<variant<int, float>, float>( variant<int, float>( 3.0f ) );
75 STATIC_ASSERT( w == 3.0f );
76 }
77
78 {
79 constexpr auto w = test<variant<int, int, float>, float>( variant<int, int, float>( 3.0f ) );
80 STATIC_ASSERT( w == 3.0f );
81 }
82
83 {
84 constexpr auto w = test<variant<E, E, X>, X>( variant<E, E, X>( 1 ) );
85 STATIC_ASSERT( w == 1 );
86 }
87
88 {
89 constexpr auto w = test<variant<int, int, float, float, X>, X>( variant<int, int, float, float, X>( X(1) ) );
90 STATIC_ASSERT( w == 1 );
91 }
92
93 #if defined( BOOST_LIBSTDCXX_VERSION ) && BOOST_LIBSTDCXX_VERSION < 50000
94 #else
95
96 {
97 constexpr auto w = test<variant<E, E, Y>, Y>( variant<E, E, Y>( 1 ) );
98 STATIC_ASSERT( w == 1 );
99 }
100
101 {
102 constexpr auto w = test<variant<int, int, float, float, Y>, Y>( variant<int, int, float, float, Y>( Y(1) ) );
103 STATIC_ASSERT( w == 1 );
104 }
105
106 #endif
107 }
108