catkin command for rosbuild_invoke_rospack(${PROJECT_NAME} ${_prefix} DIRS depends-manifests)

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thanks, we have defined idl message compilation helper cmake functions, that searches all downlostreamy dependent directories with ./idl folder and compile them https://code.google.com/p/rtm-ros-robotics/source/browse/trunk/rtmros_common/rtmbuild/#rtmbuild%2Fcmake

Without further information I would just guess that this should be handled differently. Message generation is very similar to this an genmsg/genpy/gencpp provide cmake functions and additional scripts to perform the generation. But each downstream package explicitly invokes the generation for its messages. That also makes it more in line with the goal that the result should be bundled within each package (and not with the generator).

Ok, but how about [1] case, To invoke message generation for each downstream package, for custom client library which is not available as ubuntu system package? [1] http://ros-users.122217.n3.nabble.com/Shared-installation-wiki-page-td1313245.html

The clean way is to write a generator and build all message packages from source to also generate messages with your custom generator. Otherwise I don't see a good way to perform clean dependencies and checking for rebuilds.