Function action_assignable_to_val_direct

include/boost/parser/parser.hpp:4631–4651

        template<typename Action, typename Attribute, typename Context>
        constexpr auto action_assignable_to_val_direct()
        {
            if constexpr (is_nope_v<decltype(*std::declval<Context>().val_)>) {
                return false;
            } else if constexpr (!is_detected_v<
                                     action_direct_call_expr,
                                     Action,
                                     Attribute>) {
                return false;
            } else if constexpr (std::is_same_v<
                                     action_direct_call_expr<Action, Attribute>,
                                     void>) {
                return false;
            } else {
                return is_detected_v<
                    action_assignable_to_val_direct_expr,
                    Action,
                    Attribute,
                    Context>;
            }
        }

        template<typename Action, typename Attribute, typename Context>
        constexpr auto action_assignable_to_val_apply()