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- // Copyright 2015 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
- #if defined(_MSC_VER)
- #pragma warning( disable: 4244 ) // 'initializing': conversion from 'int' to 'char', possible loss of data
- #endif
- #include <boost/mp11/tuple.hpp>
- #include <boost/mp11/detail/config.hpp>
- // Technically std::tuple isn't constexpr enabled in C++11, but it works with libstdc++
- #if defined( BOOST_MP11_NO_CONSTEXPR ) || ( !defined( __GLIBCXX__ ) && __cplusplus < 201400L )
- int main() {}
- #else
- #include <tuple>
- #include <array>
- #include <utility>
- struct T1
- {
- int x, y, z;
- constexpr T1( int x = 0, int y = 0, int z = 0 ): x(x), y(y), z(z) {}
- };
- int main()
- {
- using boost::mp11::construct_from_tuple;
- {
- constexpr std::tuple<int, short, char> tp{ 1, 2, 3 };
- constexpr auto r = construct_from_tuple<T1>( tp );
- static_assert( r.x == 1, "r.x == 1" );
- static_assert( r.y == 2, "r.y == 2" );
- static_assert( r.z == 3, "r.z == 3" );
- }
- {
- constexpr std::pair<short, char> tp{ 1, 2 };
- constexpr auto r = construct_from_tuple<T1>( tp );
- static_assert( r.x == 1, "r.x == 1" );
- static_assert( r.y == 2, "r.y == 2" );
- static_assert( r.z == 0, "r.z == 0" );
- }
- {
- constexpr std::array<short, 3> tp{{ 1, 2, 3 }};
- constexpr auto r = construct_from_tuple<T1>( tp );
- static_assert( r.x == 1, "r.x == 1" );
- static_assert( r.y == 2, "r.y == 2" );
- static_assert( r.z == 3, "r.z == 3" );
- }
- #if defined( __clang_major__ ) && __clang_major__ == 3 && __clang_minor__ < 9
- // "error: default initialization of an object of const type 'const std::tuple<>' without a user-provided default constructor"
- #else
- {
- constexpr std::tuple<> tp;
- constexpr auto r = construct_from_tuple<T1>( tp );
- static_assert( r.x == 0, "r.x == 0" );
- static_assert( r.y == 0, "r.y == 0" );
- static_assert( r.z == 0, "r.z == 0" );
- }
- #endif
- }
- #endif
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