Add CMake config using pkg-config internally

[wxmerkt]

This is a WIP to test generating a CMake config (#98). This does not yet export the include directories properly (i.e., ${eigenpy_INCLUDE_DIRS} is not populated). I'd love some feedback on which steps I have missed to include :-)

[olivier-stasse]

Hi @wxmerkt , I gave a shot to CMake export + jrl-cmakemodule on dynamic-graph and I have a preliminary version working. It seems to me that the problem comes from the fact you do not install the include in your INSTALL macro (https://github.com/wxmerkt/eigenpy/blob/b518cbefbb0bca5e3aa33045d1e59e8dc6a36ac1/CMakeLists.txt#L130)
You should have something:

INSTALL(TARGETS ${PROJECT_NAME}
  EXPORT ${TARGETS_EXPORT_NAME}
  PUBLIC_HEADER 
  INCLUDES DESTINATION include
...

and then for target_include_directories the INTERFACE option specifies the directory to include,
and it seems to me that:

$<INSTALL_INTERFACE:include>

will create the entry

${_IMPORT_PREFIX}/include

in your eigenpyTargets.cmake file
while your current value

$<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}>

is probably ignored as far as I understood as it is used to build the interface.
But what I suspect is that your current CMakeLists.txt is not installing the header.
In addition you might have to specify PUBLIC_HEADER:

SET (PUBLIC_HEADER ${{PROJECT_NAME}_HEADERS})

Hope it helps.

[wxmerkt]

Hi @olivier-stasse,
Thank you very much for looking into this and the detailed instructions. I think we need some additional steps to export PKG_CONFIG_APPEND_CFLAGS and other cflags dependencies into the target, i.e.:

• Boost::python
• Eigen
• Python include directories

This minimal example works, but obviously all flags should be set by eigenpy::eigenpy/correctly exported:

project(test_test CXX)

find_package(eigenpy REQUIRED)

# TODO: This should not be necessary
find_package(PythonLibs REQUIRED)
include_directories(${PYTHON_INCLUDE_DIRS})

# TODO: This should not be necessary
find_package(Boost REQUIRED COMPONENTS python numpy)

# TODO: This should not be necessary
find_package(Eigen3 REQUIRED)

add_library(${PROJECT_NAME} test.cpp)
# TODO: This should only link against `eigenpy::eigenpy`
target_link_libraries(${PROJECT_NAME} PUBLIC eigenpy::eigenpy Boost::python Boost::numpy Eigen3::Eigen)

There is a ton of macros in cmake-modules that only use pkg-config and would need to be fixed. It may be easier to do a clean modern CMake from scratch.

Thanks,
Wolfgang

[jmirabel]

There is a ton of macros in cmake-modules that only use pkg-config and would need to be fixed. It may be easier to do a clean modern CMake from scratch.

I agree, although it requires some work.

[nim65s]

Hi,

I pretty much think this is my job to do this kind of stuff ; so if you can wait a week or two, I can handle this.

[jcarpent]

I also agree with @wxmerkt and @jmirabel and it is related to discussions in stack-of-tasks/pinocchio#919
From my side, I can take the charge of moving Pinocchio, EigenPy and HPP-FCL towards this new features.

[olivier-stasse]

This was for me the occasion to have a look to the impact to use modern CMake.
I agree that this will have a profund impact on the jrl-cmakemodules to the point it
does not make sense to start from the current one.
The new approach is suppose to make pkg-config useless.
As far as I can see, the main impact is that all the macros handling the PKG_CONFIG information should be switch to proper Targets.cmake files.
We have to check dependency by dependency what make sense.
Now given the number of packages, I am not sure that everything should fall down on the shoulder of Guilhem (thanks Justin for your proposal)

Another question: should we continue with submodule or use something else ?
I do not see real alternative (catkin is not suppose to survive ROS1)

[jmirabel]

Pure CMake based and pkg-config based configuration have both their downsides. The cons of CMake is that you cannot use CMake files outside of CMake.

Commiting to CMake is fine for me. The submodule can be useful to configure the generate of the cmake config, target and version files. I also think it is a good idea to continue generating pc files on linux and mac.

[jcarpent]

@jmirabel I do not think we should continue this discussion but rather on the cmake modules ;) But I agree, we should mainteed the generation of the pkg-config files.

[wxmerkt]

This is now changed to install a cmake config that internally uses pkg-config. This is a temporary solution to fix the MoveIt builds (per discussion at IROS) and provide backward compatibility with a previously released version.

When the targets-export-version in jrl-cmake supports dependencies etc. that are currently handled via pkg-config macros, we will overwrite the cmake config with an automatically generated one (via SETUP_PROJECT_PACKAGE_FINALIZE).

[jcarpent]

@wxmerkt Do you need a release?

[wxmerkt]

@jcarpent: Yes, please! :-)

[jcarpent]

Done!