ctkMacroBuildQtPlugin uses ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}, which might not have been set (the user also may want to have a different directory as output)

[RafaelPalomar]

ctkMacroBuildQtPlugin makes use of ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}`

CTK/CMake/ctkMacroBuildQtPlugin.cmake

Line 145 in dd9c675

LIBRARY_OUTPUT_DIRECTORY "${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${MY_PLUGIN_DIR}"

This variable may have not been set by the project calling the macro. Possible solutions:

1. Make a check and trigger an error message on `${CMAKE_LIBRARY_OUTPUT_DIRECTORY} not set.

2. Make the PLUGIN_DIR not a relative but an absolute directory. This will need to get propagated up to ctkMacroBuildQtDesignerPlugin and further to its caller. ⚠️ WARNING ⚠️ : This change would break the API.

I would lean towards 2. The final user may want to have an output directory different from ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}.