* [#315 Drop build dependency on std_msgs (backport #314)](https://github.com/ros2/rclc/pull/315) has been created for branch `humble`
* [#316 Drop build dependency on std_msgs (backport #314)](https://github.com/ros2/rclc/pull/316) has been created for branch `galactic`
* [#317 Drop build dependency on std_msgs (backport #314)](https://github.com/ros2/rclc/pull/317) has been created for branch `foxy`
This dependency is only needed when BUILD_TESTING is specified, and is already found via find_package() there.
Building packages with -DBUILD_TESTING=OFF should succeed in the absence of dependencies, which is why this issue came to my attention.
This change should be backported to Humble to avoid breaking the deb builds when we disable tests in the near future.