Question

Brief:
Does anyone know if it possible to add a custom_target in CMake that is included in all submodules? An example would be how the Install/Run_Tests/Package targets are added to every submodule in a build.

More Detail:
My scenario is that for a directory structure such as:

Project
  --CMakeLists.txt
  --SubMod A
      --CMakeListsA.txt
  --SubMod B
      --CMakeListsB.txt

I would like to add a custom_target for doxygen generation to the top level CMakeLists.txt file and have that included in Sub Module A and B. The command will be exactly the same between all modules.

I could add the custom_target to each sub-module’s cmake file but this seems wrong. The other issue with this is if I have CMake generate a Visual Studio solution there will be conflicts with a “doc” project already existing (if opening the top level solution). CMake provided targets are however smart enough to not be included twice.

Answer 1

I think the best you can do is wrap the add_custom_target in a function defined in your top-level CMakeLists.txt and use it in each CMakeLists.txt.

To avoid the problem of repeating target names, you could define the function something like:

function(AddDoxygenTarget)
  add_custom_target(Doxygen${PROJECT_NAME} ...)
endfunction()

This depends on each submodule’s CMakeLists.txt having a project command. If not, you could use each subdirectory’s name:

  get_filename_component(SubDirName ${CMAKE_CURRENT_LIST_DIR} NAME)
  add_custom_target(Doxygen${SubDirName} ...)