How to export non-standard include directories in catkin?

Question

This question spawned from question 68680.

I'm using yujin_tools to cross-compile ROS for ARM. I've created a Catkin package for tinyxml that installs headers to /include/tinyxml, and the package advertises "include" and "include/tinyxml" in the catkin_package() macro.

When I build rospack, it complains about not finding the tinyxml.h header:

/home/user/ros_yujin_ws/src/rospack/src/rospack.cpp:30: fatal error: tinyxml.h: No such file or directory

rospack is using the non-namespaced version of the tinyxml include directive, but I've installed them namespaced. How do I tell rospack to look in /include/tinyxml instead of or in addition to /include?

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Originally posted by dustingooding on ROS Answers with karma: 139 on 2013-10-22

Post score: 3

Answer 1

So catkin makes the assumption that you install all of your headers into the root of the include folder, i.e. <prefix>/include, when generating your CMake config file and pkg-config files. So your resulting pkg_name_INCLUDE_DIRS will by default be <prefix>/include. In this instance you want to have that also include <prefix>/include/pkg_name as well.

There are two ways to accomplish this. The first is simple, but will break if you relocate the installed package.

Simply pass this to your catkin_package(...) call:

catkin_package(
  INCLUDE_DIRS include include/tinyxml ${CMAKE_INSTALL_PREFIX}/include/tinyxml
  ...
)

The second way uses the pkg_name_DIR variable which allows you to make a relocatable addition to your _INCLUDE_DIRS. The problem is that this variable is not available in your CMakeLists.txt, but is available when your package is find_package'ed, so you have to use a CMake extras file (which gets evaluated at find_package time) in order to do this correctly.

Reference: http://docs.ros.org/api/catkin/html/dev_guide/generated_cmake_api.html#catkin_package (CFG_EXTRAS)

In order to do this, what you will want to do is to is create a file in your project cmake/<pkg_name>-extras.cmake.in where you replace <pkg_name> with your package name. In that file you should do something like this:

list(APPEND @PROJECT_NAME@_INCLUDE_DIRS "${@PROJECT_NAME@_DIR}/../../../@CATKIN_GLOBAL_INCLUDE_DESTINATION@/tinyxml")

The elements inside of @..@ will get templated at build time of your package. You will need to tell catkin to do this templating for you:

catkin_package(
  ...
  CFG_EXTRAS <pkg_name>-extras.cmake
)

Note that you do not include the .in extension here.

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Originally posted by William with karma: 17335 on 2013-10-22

This answer was ACCEPTED on the original site

Post score: 8

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Original comments

Comment by William on 2013-10-22:
@Dirk Thomas please review this answer

Comment by Dirk Thomas on 2013-10-22:
Looks all good to me. Great answer.

Comment by hawesie on 2014-10-28:
When doing this for a package to be released, should the <pkg_name>-extras.cmake file be installed? I'm guessing yes.

Comment by Dirk Thomas on 2014-10-28:
When you use CFG_EXTRAS the file gets installed automatically.

Comment by hawesie on 2014-10-28:
Awesome, thanks.