Function swap

crates/cpp/test_headers/expected.hpp:2438–2441

                              std::is_move_constructible<E>::value &&
                              detail::is_swappable<E>::value> * = nullptr>
void swap(expected<T, E> &lhs,
          expected<T, E> &rhs) noexcept(noexcept(lhs.swap(rhs))) {
  lhs.swap(rhs);
}
} // namespace tl

#endif