I have create a raise_warning_level branch on various repositories to raise the warning level. For now it includes: -Wall -Wextra Please check the changes in those branches. I would like to avoid creating separate PRs for all of those.

• https://github.com/ros2/common_interfaces/tree/raise_warning_level
• https://github.com/ros2/examples/tree/raise_warning_level
• https://github.com/ros2/rcl_interfaces/tree/raise_warning_level
• https://github.com/ros2/rclcpp/tree/raise_warning_level
• https://github.com/ros2/rmw/tree/raise_warning_level
• https://github.com/ros2/rmw_connext/tree/raise_warning_level
• https://github.com/ros2/rmw_opensplice/tree/raise_warning_level
• https://github.com/ros2/rosidl/tree/raise_warning_level
• https://github.com/ros2/rosidl_dds/tree/raise_warning_level
• https://github.com/ros2/system_tests/tree/raise_warning_level

The CI build is happy with the stricter settings: http://ci.ros2.org/job/ros2_batch_ci_linux/58/