Class type

include/asio/execution/execute.hpp:173–187

  {
#if defined(ASIO_HAS_DEDUCED_EXECUTE_MEMBER_TRAIT)
    struct type
    {
      template <typename F>
      auto execute(ASIO_MOVE_ARG(F) f)
        noexcept(
          noexcept(
            declval<typename conditional<true, T, F>::type>().execute(
              ASIO_MOVE_CAST(F)(f))
          )
        )
        -> decltype(
          declval<typename conditional<true, T, F>::type>().execute(
            ASIO_MOVE_CAST(F)(f))
        );
    };
#else // defined(ASIO_HAS_DEDUCED_EXECUTE_MEMBER_TRAIT)
    typedef T type;
#endif // defined(ASIO_HAS_DEDUCED_EXECUTE_MEMBER_TRAIT)