DEPENDS in catkin_package() not adding package INCLUDE_DIRS

[po1]

... or more accurately, not adding PACKAGE_INCLUDE_DIRS (note the uppercase).

This issue was triggered in gazebo_ros_control.
In the CMakeLists.txt, we can see something similar to the following:

catkin_package(gazebo_ros_control
  [...]
  DEPENDS gazebo
)

What catkin does when we specify this is to add ${gazebo_INCLUDE_DIRS} to PROJECT_CMAKE_CONFIG_INCLUDE_DIRS, which is ultimately appended to catkin_INCLUDE_DIRS of whatever projects that uses find_package(catkin COMPONENTS gazebo_ros_control)

A quick glance inside of gazebo-config.cmake reveals that the variable that is set is GAZEBO_INCLUDE_DIRS (note the uppercase), which is what is recommended in the CMake tutorials.

The result is that if package foo uses find_package(catkin COMPONENTS gazebo_ros_control) will not have gazebo include dirs in its catkin_INCLUDE_DIRS, and will result in a build fail at first, and then in a declaration of an unnecessary dependency of foo to gazebo.

Another workaround is to change the CMakeLists.txt in gazebo_ros_control to the following:

catkin_package(gazebo_ros_control
  [...]
  DEPENDS GAZEBO
)

I don't know exactly what should be done here. If I understand the problem correctly, catkin has no way to guess the case of the XY_INCLUDE_DIRS variables, and assumes that the case is the same as that of the package name. Also, I could not find a mention of this case subtlety anywhere in the doc, and thought that it would be at least worth mentioning.

[dirk-thomas]

Since catkin has no way of guessing the case (and should not just try to use all possible cases). It uses the name exactly as passed to catkin_package(DEPENDS).

In this case where the package defines all uppercase variable you need to pass an all uppercase package name to DEPENDS. Therefore please fill this issue against gazebo_ros_control and suggest your above fix to that package.

[wjwwood]

catkin has no way to guess the case of the XY_INCLUDE_DIRS variables, and assumes that the case is the same as that of the package name

That is exactly correct, if the package does not follow the convention where <pkg_name> is used consistently in find_package(<pkg_name> ...) and resulting variables like <pkg_name>_INCLUDE_DIRS, then catkin cannot determine it automatically.

In times like this you must manually pass include directories and libraries to the catkin_export call, and you cannot depend on the DEPENDS syntactic sugar.

For the documentation, I think it is already ticked here: #491