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MITK cannot handle CMake target namespaces in module and plugin package dependencies
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More and more libraries use namespace notation for their targets like tinyxml2::tinyxml2, boost::headers, Qt5::Core, cpprestsdk::cpprest, or OpenSSL::SSL. It is not clear how they should be written in MITK's package dependency notation based on package names and component names. For some reason, Qt seems to work with Qt5|Core+Widgets for example, while all other examples above don't. The expected mix of both notations would be something like Boost|boost::headers which does not work. Same for Boost|headers. We have some workarounds in our code base like:


  target_link_libraries(${MODULE_TARGET} PUBLIC cpprestsdk::cpprest OpenSSL::SSL)

Event Timeline

kislinsk triaged this task as Unbreak Now! priority.Nov 23 2020, 11:35 PM
kislinsk created this task.
How the PACKAGE_DEPENDS parameter of mitk_create_module() works
  • mitk_create_module() passes PACKAGE_DEPENDS to _mitk_parse_package_args()
    • The PACKAGE[|COMPONENT1[+COMPONENT2]...] syntax is processed and the following variables are set in parent scope:
      • <PUBLIC|PRIVATE|INTERFACE>_PACKAGE_NAMES: Lists of package names for different visibilities
      • PACKAGE_NAMES: Joined lists from above (may contain duplicates!)
      • <PUBLIC|PRIVATE|INTERFACE>_<PACKAGE>_REQUIRED_COMPONENTS: Lists of components for different visibilities and packages
  • mitk_create_module() passes PACKAGE_NAMES to mitk_check_module_dependencies()
    • mitk_check_module_dependencies() passes PACKAGE_NAMES to _mitk_parse_package_args()
      • Notice that PACKAGE_NAMES does not contain visibilities anymore, so everything is put into PRIVATE_PACKAGE_NAMES by default
    • Nevertheless, all visibility lists are joined into package_names and duplicates are removed (why not just use PACKAGE_NAMES in the first place and remove duplicates?)
    • For each package, check if MITK_USE_<package> is not set and add package to _MISSING_DEP in parent scope together with missing modules
  • Also: Duplicates in PACKAGE_NAMES were removed by mitk_check_module_dependencies()
  • The module is disabled if there are any missing dependencies
  • PACKAGE_DEPENDS is passed to mitk_use_modules() as PACKAGES parameter
How the PACKAGE_DEPENDS parameter of mitk_create_plugin() works
  • mitk_create_plugin() just passes PACKAGE_DEPENDS to mitk_check_module_dependencies() and mitk_use_modules()
How mitk_use_modules() works
  • mitk_use_modules() is basically an interface between a target (module or plugin) and the corresponding CMake/PackageDepends/<package>.cmake file
    • Inputs for these files are:
      • MODULE_NAME: The target
      • <package>_REQUIRED_COMPONENTS_BY_MODULE: Required components
    • Outputs (variables that are parsed after including these files) are:
      • ALL_INCLUDE_DIRECTORIES: Is passed to target_include_directories()
      • ALL_LIBRARIES: Is passed to target_link_libraries()
      • ALL_COMPILE_DEFINITIONS: Is passed to target_compile_definitions(PRIVATE)
      • ALL_COMPILE_OPTIONS: Is passed to target_compile_options()
    • Notice that these files are included once per visibility

Holy moly, I just learned that the package depends files work completely different than I thought/was told the past 9 years. Instead of fixing the mitk_use_modules() function we just need to use the package depends files correctly.

Fixed VTK and TinyXML-2 so far.

Public API change: Depending on VTK does not add a transitive dependency to Qt5 Widgets anymore, except, when the required VTK components have a public dependency to Qt5 Widgets of course.

Introduced TARGET_DEPENDS option.

TARGET_DEPENDS parameters are directly passed to target_link_libraries() and bypass the PACKAGE_DEPENDS mechanism.

The option was added to:

  • mitk_create_module()
  • mitk_create_plugin()
  • mitk_create_executable()
  • mitkFunctionCreateCommandLineApp()
  • mitkFunctionCreateMatchPointDeployedAlgorithm()

PACKAGE_DEPENDS now properly supports Boost, OpenMesh, OpenMP, OpenSSL, and Python3. For example:

  • PACKAGE_DEPENDS Boost is short for Boost|boost (header-only part of Boost)
  • PACKAGE_DEPENDS Boost|date_time+random maps to Boost::date_time Boost::random
  • PACKAGE_DEPENDS OpenMesh|Tools maps to OpenMeshTools
  • PACKAGE_DEPENDS OpenMP maps to OpenMP::OpenMP_CXX
  • PACKAGE_DEPENDS Python3|NumPy maps to Python3::NumPy

ITK, OpenGL, Poco and Qt5 dependencies are now based on targets instead of directories as well.

Deleted branch bugfix/T28002-ImprovePackageDependsFiles.