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(V && v)37 template<class T, class V> constexpr T test( V&& v )
38 {
39 V v2( std::forward<V>(v) );
40 return get<T>( v2 );
41 }
42
main()43 int main()
44 {
45 {
46 constexpr auto w = test<int>( variant<int>( 1 ) );
47 STATIC_ASSERT( w == 1 );
48 }
49
50 {
51 constexpr auto w = test<X>( variant<X>( 1 ) );
52 STATIC_ASSERT( w == 1 );
53 }
54
55 #if defined( BOOST_LIBSTDCXX_VERSION ) && BOOST_LIBSTDCXX_VERSION < 50000
56 #else
57
58 {
59 constexpr auto w = test<Y>( variant<Y>( 1 ) );
60 STATIC_ASSERT( w == 1 );
61 }
62
63 #endif
64
65 {
66 constexpr auto w = test<int>( variant<int, float>( 1 ) );
67 STATIC_ASSERT( w == 1 );
68 }
69
70 {
71 constexpr auto w = test<float>( variant<int, float>( 3.0f ) );
72 STATIC_ASSERT( w == 3.0f );
73 }
74
75 {
76 constexpr auto w = test<float>( variant<int, int, float>( 3.0f ) );
77 STATIC_ASSERT( w == 3.0f );
78 }
79
80 {
81 constexpr auto w = test<X>( variant<E, E, X>( 1 ) );
82 STATIC_ASSERT( w == 1 );
83 }
84
85 {
86 constexpr auto w = test<X>( variant<int, int, float, float, X>( X(1) ) );
87 STATIC_ASSERT( w == 1 );
88 }
89
90 #if defined( BOOST_LIBSTDCXX_VERSION ) && BOOST_LIBSTDCXX_VERSION < 50000
91 #else
92
93 {
94 constexpr auto w = test<Y>( variant<E, E, Y>( 1 ) );
95 STATIC_ASSERT( w == 1 );
96 }
97
98 {
99 constexpr auto w = test<Y>( variant<int, int, float, float, Y>( Y(1) ) );
100 STATIC_ASSERT( w == 1 );
101 }
102
103 #endif
104 }
105