12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576777879808182838485868788899091 |
- // Copyright 2017 Peter Dimov.
- //
- // Distributed under the Boost Software License, Version 1.0.
- //
- // See accompanying file LICENSE_1_0.txt or copy at
- // http://www.boost.org/LICENSE_1_0.txt
- #include <boost/variant2/variant.hpp>
- using namespace boost::variant2;
- struct X
- {
- int v;
- X() = default;
- constexpr explicit X( int v ): v( v ) {}
- constexpr operator int() const { return v; }
- };
- struct Y
- {
- int v;
- constexpr Y(): v() {}
- constexpr explicit Y( int v ): v( v ) {}
- constexpr operator int() const { return v; }
- };
- #define STATIC_ASSERT(...) static_assert(__VA_ARGS__, #__VA_ARGS__)
- template<class V, class T, class A> constexpr A test( A const& a )
- {
- V v;
- v.template emplace<T>( a );
- return get<T>(v);
- }
- int main()
- {
- {
- constexpr auto w = test<variant<int>, int>( 1 );
- STATIC_ASSERT( w == 1 );
- }
- {
- constexpr auto w = test<variant<X>, X>( 1 );
- STATIC_ASSERT( w == 1 );
- }
- #if defined( BOOST_LIBSTDCXX_VERSION ) && BOOST_LIBSTDCXX_VERSION < 50000
- #else
- {
- constexpr auto w = test<variant<Y>, Y>( 1 );
- STATIC_ASSERT( w == 1 );
- }
- #endif
- {
- constexpr auto w = test<variant<int, float>, int>( 1 );
- STATIC_ASSERT( w == 1 );
- }
- {
- constexpr auto w = test<variant<int, float>, float>( 3.0f );
- STATIC_ASSERT( w == 3.0f );
- }
- {
- constexpr auto w = test<variant<int, int, float>, float>( 3.0f );
- STATIC_ASSERT( w == 3.0f );
- }
- {
- constexpr auto w = test<variant<int, int, float, float, X>, X>( 1 );
- STATIC_ASSERT( w == 1 );
- }
- #if defined( BOOST_LIBSTDCXX_VERSION ) && BOOST_LIBSTDCXX_VERSION < 50000
- #else
- {
- constexpr auto w = test<variant<int, int, float, float, Y>, Y>( 1 );
- STATIC_ASSERT( w == 1 );
- }
- #endif
- }
|