Failure to configure module externally

[SimonRit]

Description

Since 5b09d546666f6110250aa7edbb59d4469791b944, configuring a module separately fails.

Steps to Reproduce

Compile ITK with default modules, then configure a module with cmake.

Expected behavior

The module is configured

Actual behavior

Tested with RTK, cmake gives

CMake Error at /home/srit/src/itk/itk/CMake/ITKModuleAPI.cmake:78 (message):
  No such module: "RTK"
Call Stack (most recent call first):
  /home/srit/src/itk/itk/CMake/ITKModuleAPI.cmake:7 (itk_module_load)
  /home/srit/src/itk/itk/CMake/ITKModuleAPI.cmake:153 (_itk_module_use_recurse)
  /home/srit/src/itk/itk/CMake/ITKModuleMacros.cmake:324 (itk_module_use)
  test/CMakeLists.txt:43 (itk_module_test)

and scifio-image, cmake gives

CMake Error at src/CMakeLists.txt:118 (install):
  install DIRECTORY given no DESTINATION!

Reverting 5b09d546666f6110250aa7edbb59d4469791b944 removes the errors.

Reproducibility

100%

Versions

master

Environment

Linux, cmake 3.20.4.

Additional Information

[SimonRit]

cc @hjmjohnson

[SimonRit]

I think I start to understand the issue. Before 5b09d546666f6110250aa7edbb59d4469791b944, the default CMAKE_INSTALL_LIBDIR was overwritten with lib, see here. This is no longer the case after the commit. To make it work for RTK, I had to

• rebuild ITK from scratch to use the default CMAKE_INSTALL_LIBDIR, i.e. lib64 on my machine,
• mimick the same thing on RTK side with SimonRit/RTK@bce50cd48ea658732f8866267c8fbe4387e7b01f.

That would solve the issue (to be confirmed) but one still has to force CMAKE_INSTALL_LIBDIR to be the same as ITK's in an externally built module.

[SimonRit]

The problem has been solved in RTK since SimonRit/RTK#510 has been merged. However, I have the feeling that there is a general issue for other modules. For example, if I compile ITKSplitComponent separately (first compile ITK, then Split component), the SplitComponent info and targets are put in cmake/ITK-5.3/Modules/SplitComponents.cmake and cmake/ITK-5.3/Modules/Targets/SplitComponentsTargets.cmake instead of lib/cmake/ITK-5.3/Modules/SplitComponents.cmake and lib/cmake/ITK-5.3/Modules/Targets/SplitComponentsTargets.cmake . Therefore, if a project uses ITK with find_package(ITK REQUIRED COMPONENTS SplitComponent) it won't find SplitComponent and say

CMake Error at /home/srit/src/itk/itk/CMake/ITKModuleAPI.cmake:78 (message):
  No such module: "SplitComponent"

What do you think @tbirdso (since you work on SplitComponent)?

[thewtex]

@SimonRit @tbirdso @hjmjohnson , should we add

if(NOT CMAKE_INSTALL_LIBDIR)
 set(CMAKE_INSTALL_LIBDIR lib)
endif()

Here: https://github.com/InsightSoftwareConsortium/ITK/blob/8e34f1078e13b4ae39d8aaa600ff936a9a3050bb/CMake/ITKModuleExternal.cmake#L74-L77

Similar to: https://github.com/SimonRit/RTK/commit/bce50cd48ea658732f8866267c8fbe4387e7b01f

?

[SimonRit]

Yes, it fixes the problem for me. Thanks!