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- // Copyright Louis Dionne 2013-2017
- // Distributed under the Boost Software License, Version 1.0.
- // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
- #include <boost/hana/assert.hpp>
- #include <boost/hana/config.hpp>
- #include <boost/hana/first.hpp>
- #include <boost/hana/pair.hpp>
- #include <boost/hana/second.hpp>
- #include <utility>
- namespace hana = boost::hana;
- struct MoveOnly {
- int data_;
- MoveOnly(MoveOnly const&) = delete;
- MoveOnly& operator=(MoveOnly const&) = delete;
- MoveOnly(int data = 1) : data_(data) { }
- MoveOnly(MoveOnly&& x) : data_(x.data_) { x.data_ = 0; }
- MoveOnly& operator=(MoveOnly&& x)
- { data_ = x.data_; x.data_ = 0; return *this; }
- bool operator==(const MoveOnly& x) const { return data_ == x.data_; }
- };
- struct MoveOnlyDerived : MoveOnly {
- MoveOnlyDerived(MoveOnlyDerived&&) = default;
- MoveOnlyDerived(int data = 1) : MoveOnly(data) { }
- };
- constexpr auto in_constexpr_context(int a, short b) {
- hana::pair<int, short> p1(a, b);
- hana::pair<int, short> p2;
- hana::pair<double, long> p3;
- p2 = std::move(p1);
- p3 = std::move(p2);
- return p3;
- }
- int main() {
- // from pair<T, U> to pair<T, U>
- {
- hana::pair<MoveOnly, short> p1(MoveOnly{3}, 4);
- hana::pair<MoveOnly, short> p2;
- p2 = std::move(p1);
- BOOST_HANA_RUNTIME_CHECK(hana::first(p2) == MoveOnly{3});
- BOOST_HANA_RUNTIME_CHECK(hana::second(p2) == 4);
- }
- // from pair<T, U> to pair<V, W>
- {
- hana::pair<MoveOnlyDerived, short> p1(MoveOnlyDerived{3}, 4);
- hana::pair<MoveOnly, long> p2;
- p2 = std::move(p1);
- BOOST_HANA_RUNTIME_CHECK(hana::first(p2) == MoveOnly{3});
- BOOST_HANA_RUNTIME_CHECK(hana::second(p2) == 4);
- }
- // make sure that also works in a constexpr context
- // (test fails under GCC <= 6 due to buggy constexpr)
- #if BOOST_HANA_CONFIG_GCC >= BOOST_HANA_CONFIG_VERSION(7, 0, 0)
- {
- constexpr auto p = in_constexpr_context(3, 4);
- static_assert(hana::first(p) == 3, "");
- static_assert(hana::second(p) == 4, "");
- }
- #endif
- }
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