ROS 2 rclcpp + rcl - humble  humble
ROS 2 C++ Client Library with ROS Client Library

detail → rcl Relation

File in rclcpp/include/rclcpp/detailIncludes file in rcl
rmw_implementation_specific_publisher_payload.hppinclude / rcl / publisher.h
rmw_implementation_specific_subscription_payload.hppinclude / rcl / subscription.h
utilities.hppinclude / rcl / allocator.h
utilities.hppinclude / rcl / arguments.h