Handle multiple link libraries for FCL

[rhaschke]

This is in preparation to use fcl 0.6.1 in Noetic. See ros/rosdistro#26527 for details.
Our cmake code to find absolute library paths of FCL libs was only handling a single lib (namely libfcl). However, future releases of libfcl declare several link libraries. To correctly link to those, we need to find absolute paths for all of them.

[codecov]

Codecov Report

Merging #2325 into master will decrease coverage by 0.18%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2325      +/-   ##
==========================================
- Coverage   57.93%   57.75%   -0.17%     
==========================================
  Files         327      327              
  Lines       25633    25633              
==========================================
- Hits        14848    14802      -46     
- Misses      10785    10831      +46     

Impacted Files	Coverage Δ
.../move_group_interface/src/move_group_interface.cpp	44.45% <0.00%> (-3.63%)	⬇️
...e/src/parameterization/model_based_state_space.cpp	72.23% <0.00%> (-2.77%)	⬇️
moveit_core/robot_model/src/joint_model_group.cpp	59.34% <0.00%> (-2.71%)	⬇️
...ipulation/pick_place/src/manipulation_pipeline.cpp	76.42% <0.00%> (-0.94%)	⬇️
...meterization/work_space/pose_model_state_space.cpp	82.32% <0.00%> (-0.68%)	⬇️
moveit_core/robot_state/src/robot_state.cpp	47.40% <0.00%> (+0.10%)	⬆️
...dl_kinematics_plugin/src/kdl_kinematics_plugin.cpp	79.38% <0.00%> (+0.45%)	⬆️
...on/pick_place/src/approach_and_translate_stage.cpp	73.60% <0.00%> (+0.80%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 1d8d51e...ed502c6. Read the comment docs.

[simonschmeisser]

Newer versions of fcl (ie not the system version in noetic ... what a mess ...) also provide a cmake config. So maybe

find_package(fcl REQUIRED)

already does the trick?

[rhaschke]

Yes, I tried this before. It works here, locally. But exporting the required fcl libs to downstream packages didn't work:
catkin provides two mechanisms to do this:

1. For catkin packages via CATKIN_DEPENDS and
2. for 3rd-party packages via DEPENDS in catkin_package().

The latter - required here - requires to declare LIBFCL_INCLUDE_DIRS and LIBFCL_LIBRARIES. But, I failed to assemble LIBFCL_LIBRARIES because fcl's cmake config declares an imported library target. Manually accessing IMPORTED_LOCATION and INTERFACE_LINK_LIBRARIES of that target was a nightmare and I gave up.

[simonschmeisser]

Hmm, who besides collision_detection_fcl needs that dependency? But looking at the documentation of catkin_package I see your problem

[rhaschke]

Who besides collision_detection_fcl needs that dependency?

moveit_compare_collision_checking_speed_fcl_bullet was failing to link.

[simonschmeisser]

Then the clean and lean find_package could be moved to these two directly? Normally the fcl dependency should be abstracted away right?

[rhaschke]

Maybe. I'm not sure moveit_compare_collision_checking_speed_fcl_bullet explicitly uses fcl functionality. If so, it should find_package(fcl) itself, I agree.

[rhaschke]

Given the fact that we need to handle FCL 0.5 for Melodic, we are stuck to pkgconfig for now.
Hence, I would like to get this basic fix merged as is.

[v4hn]

Thanks for working on this. Makes sense to me.