questions on ROS2 foxy source code
1) With the instructions on "Building ROS 2 on Windows", executing "colcon build --merge-install" tooks about one hour on my desktop. Occasionally, I saw the warning messages showing up like this:
[270.259s] colcon.colcon_cmake.task.cmake.build WARNING Could not run installation step for package 'tlsf' because it has no 'install' target
[391.952s] colcon.colcon_cmake.task.cmake.build WARNING Could not run installation step for package 'rttest' because it has no 'install' target
--- stderr: rosidl_typesupport_connext_cpp
CMake Warning at CMakeLists.txt:32 (message):
Could not find RTI Connext - skipping 'rosidl_typesupport_connext_cpp'
--- stderr: rmw_connext_shared_cpp
CMake Warning at CMakeLists.txt:22 (message):
Could not find RTI Connext - skipping 'rmw_connext_shared_cpp'
--- stderr: rosidl_typesupport_connext_c
CMake Warning at CMakeLists.txt:37 (message):
Could not find RTI Connext - skipping 'rosidl_typesupport_connext_c'
--- stderr: rmw_connext_cpp
CMake Warning at CMakeLists.txt:32 (message):
Could not find RTI Connext - skipping 'rmw_connext_cpp'
[2006.735s] colcon.colcon_cmake.task.cmake.build WARNING Could not run installation step for package 'tlsf_cpp' because it has no 'install' target
[2851.735s] colcon.colcon_ros.task.ament_python.build WARNING Package 'test_launch_ros' doesn't explicitly install a marker in the package index (colcon-ros currently does it implicitly but that fallback will be removed in the future)
[2900.816s] colcon.colcon_cmake.task.cmake.build WARNING Could not run installation step for package 'pendulum_control' because it has no 'install' target
--- stderr: ros1_bridge
CMake Warning at CMakeLists.txt:26 (message):
Failed to find PkgConfig, skipping...
Are these warning messages safe to be ignored? Or, is it worth of fixing by a beginner like me?
2) At the end of the instructions on "Building ROS 2 on Windows", there is a section of "Staying up to date" where it points us to the instructions of "Maintaining a source checkout of ROS 2". I need some clarifications on how to properly refresh ROS2 foxy source code.
Am I right to say that https://raw.githubusercontent.com/ros... will always remain unchanged? In order to refresh, one must first obtain https://raw.githubusercontent.com/ros... or https://raw.githubusercontent.com/ros... and then execute "vcs import --input ros2.repos src" to update the source code. What vcs does is that it will overwrite existing files with newer versions. Correct?
What is the difference between the latest release and the master branch? Is it that the former is stable but the latter is unstable? Is it that the former is slightly behind the latter? How frequently should I refresh the source code? On a daily basis, or, on a weekly basis?
Every time I want to refresh, I just repeat the three commands: 1) use curl to obtain ros2.repos; 2) use "vcs import --input ros2.repos" to update the source code; 3) use "colcon build --merge-install" to rebuild. Correct?
3) Is it better for me to maintain two separate bases of the source code in my local hard drive, one is foxy/ros2.repos + updates from the latest release and the other is foxy/ros2.repos + updates from the mater branch?
