Doubt on comments on API.cmake

[SMorettini]

Why in the example of the comments at the lines

fprime/cmake/API.cmake

Lines 80 to 91 in 85fa25b

	# - **MOD_DEPS:** (optional) cmake list of extra link dependencies. This is optional, and only
	# needed if non-standard link dependencies are used, or if a dependency cannot be inferred from the include graph of
	# the autocoder inputs to the module. If not set or supplied, only fprime inferable dependencies will be available.
	# Link flags like "-lpthread" can be added here as well.
	#
	# **i.e.:**
	# ```
	# set(LINK_DEPS
	# Os
	# Module1
	# Module2
	# -lpthread)

and at the lines

fprime/cmake/API.cmake

Lines 191 to 201 in 85fa25b

	# - **MOD_DEPS:** (optional) cmake list of extra link dependencies. This is optional, and only
	# needed if non-standard link dependencies are used, or if a dependency cannot be inferred from the include graph of
	# the autocoder inputs to the module. If not set or supplied, only fprime
	# inferable dependencies will be available. Link flags like "-lpthread" can be here.
	#
	# **i.e.:**
	# ```
	# set(LINK_DEPS
	# Module1
	# Module2
	# -lpthread)

LINK_DEPS is used in the snippet of code? The comment is not about the variable MOD_DEPS?

[LeStarch]

This looks like an oversight. I am going to make this into an issue and we'll get it resolved.

[SMorettini]

About those variables, there is something else I don't understand.
When I was using FPrime 1.5.3 my CMakeList.txt had these lines for using external libraries:

find_package (orocos_kdl REQUIRED)
include_directories (${orocos_kdl_INCLUDE_DIRS})

find_package(OpenCV REQUIRED)
include_directories (${OpenCV_INCLUDE_DIRS})

...

set(MOD_DEPS
    "${orocos_kdl_LIBRARIES}"
     "${OpenCV_LIBRARIES}"
)

...

set(UT_MOD_DEPS
    "${orocos_kdl_LIBRARIES}"
    "${OpenCV_LIBRARIES}"
)

After migrating to 2.0.1 using the previous CMakeList.txt I have the following error:

No rule to make target 'MyAwesomeModule/opencv_videoio_package_gen', needed by 'MyAwesomeModule/CMakeFiles/MyAwesomeModule_package_gen'.  Stop.
No rule to make target 'MyAwesomeModule/opencv_videoio_package_gen', needed by 'MyAwesomeModule/CMakeFiles/MyAwesomeModule_package_gen'.  Stop.

I tried multiple solutions and I managed to make it works using these lines:

find_package (orocos_kdl REQUIRED)
include_directories (${orocos_kdl_INCLUDE_DIRS})

find_package(OpenCV REQUIRED)
include_directories (${OpenCV_INCLUDE_DIRS})

...

set(MOD_DEPS
    "-l${orocos_kdl_LIBRARIES}" #### added the -l ####
)
set(LINK_DEPS
    "${OpenCV_LIBRARIES}"    ###Only adding the -l as with orocos_kdl was giving the error as above
)
...

set(UT_MOD_DEPS
    "${orocos_kdl_LIBRARIES}"
    "${OpenCV_LIBRARIES}"
)

The questions are:

1. Am I using the right approach to use external libraries?
2. If I'm using the right approach, why for orocos_kdl adding the -l works and for OpenCV no?
3. Why for UT_MOD_DEPS I don't need to add -l(as it was for the FPrime 1.5.3)?

p.s.: I was not sure If I had to continue the discussion here or open a new one. If I have to open a new one tell me and I'll move this post to a new discussion.

[LeStarch]

Some help:

1. Remove quotes. I think your libraries are lists, as are mod deps. If you use quotes you'' get an internally escaped list (e.g. "orocoslib1;orocoslib2" "OpenCVlib1;OpenCVlib2"

set(MOD_DEPS
     ${orocos_kdl_LIBRARIES}
     ${OpenCV_LIBRARIES}
)

2. To fix MyAwesomeModule/opencv_videoio_package_gen, you can add dummy targets.

add_custom_target(MyAwesomeModule/opencv_videoio_package_gen)

This is a known issue with F´ < v3.0.0.

[LeStarch]

Hmmm, you have a point -l is needed for non-F´ libraries. Here is likely the cleanest work around

find_package (orocos_kdl REQUIRED)
include_directories (${orocos_kdl_INCLUDE_DIRS})

find_package(OpenCV REQUIRED)
include_directories (${OpenCV_INCLUDE_DIRS})
...
...
add_fprime_module()
# Code comes after add F´ module
get_module_name()
target_link_libraries("${MODULE_NAME}"  ${orocos_kdl_LIBRARIES} ${OpenCV_LIBRARIES})
...
... 

Note: here we are not setting MOD_DEPS at all, but just adding them as link libraries to the module directly. Note: you should only call target_link_libraries after add_fprime_module as it creates the given target.

[LeStarch]

You could also add -l to each library and then set it in mod deps....but that is more painful.