Critical bug in using ycm_ep_helper with a non-bootstrapped (i.e. found via find_package) YCM

[traversaro]

@MSECode in icub-tech-iit/docker-deployment-images#35 (comment) found a critical bug. If one consumes ycm via find_package and then calls ycm_ep_helper, an error occurs.

conda create -n testrobsub cmake pkg-config cxx-compiler make ninja ycm-cmake-modules
conda activate testrobsub
git clone https://github.com/robotology/robotology-superbuild/
cd robotology-superbuild/
cmake -Bbuild -S.

it fails with:

(testrobsub2) traversaro@IITBMP014LW012:~/testrobsub2/robotology-superbuild$ cmake -Bbuild -S.
-- The C compiler identification is GNU 13.3.0
-- The CXX compiler identification is GNU 13.3.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /home/traversaro/miniforge3/envs/testrobsub2/bin/x86_64-conda-linux-gnu-cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /home/traversaro/miniforge3/envs/testrobsub2/bin/x86_64-conda-linux-gnu-c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- YCM found in /home/traversaro/miniforge3/envs/testrobsub2/share/YCM.
CMake Error: File /home/traversaro/miniforge3/envs/testrobsub2/share/YCM/modules/YCMEPHelper/gitsafeclone.txt.in does not exist.
CMake Error at /home/traversaro/miniforge3/envs/testrobsub2/share/YCM/modules/YCMEPHelper.cmake:883 (configure_file):
  configure_file Problem configuring file
Call Stack (most recent call first):
  /home/traversaro/miniforge3/envs/testrobsub2/share/YCM/modules/YCMEPHelper.cmake:1242 (_ycm_ep_write_gitclone_script)
  cmake/BuildYCM.cmake:8 (ycm_ep_helper)
  /home/traversaro/miniforge3/envs/testrobsub2/share/YCM/modules/FindOrBuildPackage.cmake:205 (include)
  cmake/BuildYARP.cmake:8 (find_or_build_package)
  /home/traversaro/miniforge3/envs/testrobsub2/share/YCM/modules/FindOrBuildPackage.cmake:205 (include)
  cmake/RobotologySuperbuildLogic.cmake:68 (find_or_build_package)
  CMakeLists.txt:67 (include)


CMake Error: File /home/traversaro/miniforge3/envs/testrobsub2/share/YCM/modules/YCMEPHelper/RepositoryInfo.txt.in does not exist.
CMake Error at /home/traversaro/miniforge3/envs/testrobsub2/share/YCM/modules/YCMEPHelper.cmake:1272 (configure_file):
  configure_file Problem configuring file
Call Stack (most recent call first):
  cmake/BuildYCM.cmake:8 (ycm_ep_helper)
  /home/traversaro/miniforge3/envs/testrobsub2/share/YCM/modules/FindOrBuildPackage.cmake:205 (include)
  cmake/BuildYARP.cmake:8 (find_or_build_package)
  /home/traversaro/miniforge3/envs/testrobsub2/share/YCM/modules/FindOrBuildPackage.cmake:205 (include)
  cmake/RobotologySuperbuildLogic.cmake:68 (find_or_build_package)
  CMakeLists.txt:67 (include)

[traversaro]

The error went unnoticed as most users of the superbuild (i.e. the robotology-superbuild) use YCM via bootstrap/FetchContent.

[traversaro]

As a first step in handling the issue, in #468 I added a test in the CI that tries to run the configuration of the robotology-superbuild as part of the CI, so that a problem like that can be detected as early as possible.

[traversaro]

The regression is probably in #457, so it affects YCM versions from 0.16.7 to 0.18.0 only when used with CMake >= 3.22 .

[traversaro]

A fix and test to prevent similar failures to happen in the future are provided in #468 .