cmake os x failure ar no archive members specific - c++

Question

I have a simple cmake project going that I can't get to compile on OS X 10.8.4. The cmake/make process works great on Linux but on OS X I am getting this error:
Linking CXX static library libImageFilter.a
ar: no archive members specified
...
make[2]: *** [lib/libImageFilter.a] Error 1
make[1]: *** [lib/CMakeFiles/ImageFilter.dir/all] Error 2
make: *** [all] Error 2
I am using the Eclipse CDT4 Generator Unix MakeFile on both platforms. This seems like something to with the difference between ar on the two systems. But, I couldn't find much on google to help me troubleshoot.
Here is some more info for you
src/CMakeList.txt
make_minimum_required(VERSION 2.8)
project(itkNormals)
FIND_PACKAGE (ITK REQUIRED)
IF( ITK_FOUND )
include( ${ITK_USE_FILE} )
ENDIF( ITK_FOUND )
add_subdirectory(test)
add_subdirectory(lib)
src/lib/CMakeList.txt
add_library(DotImageFilter itkDotImageFilter.h)
SET_TARGET_PROPERTIES(DotImageFilter PROPERTIES LINKER_LANGUAGE CXX)
target_link_libraries(DotImageFilter ${ITK_LIBRARIES})
add_library(ImageFilter itkImageFilter.hxx)
SET_TARGET_PROPERTIES(ImageFilter PROPERTIES LINKER_LANGUAGE CXX)
target_link_libraries(ImageFilter ${ITK_LIBRARIES})
src/test/CMakeLists.txt:
include_directories(${PROJECT_SOURCE_DIR}/lib)
add_executable(itkNormalsMain itkNormals.cxx)
TARGET_LINK_LIBRARIES(itkNormalsMain ${ITK_LIBRARIES})
TARGET_LINK_LIBRARIES(itkNormalsMain ImageFilter)
TARGET_LINK_LIBRARIES(itkNormalsMain DotImageFilter)
add_executable(dotTestMain dotTester.cxx)
TARGET_LINK_LIBRARIES(dotTestMain ${ITK_LIBRARIES})
TARGET_LINK_LIBRARIES(dotTestMain ImageFilter)
TARGET_LINK_LIBRARIES(dotTestMain DotImageFilter)
add_executable(IST ImageSourceTest.cxx)
TARGET_LINK_LIBRARIES(IST ${ITK_LIBRARIES})
TARGET_LINK_LIBRARIES(IST ImageFilter)

Answer 1

You can't create library from one header file:
add_library(ImageFilter itkImageFilter.hxx)
SET_TARGET_PROPERTIES(ImageFilter PROPERTIES LINKER_LANGUAGE CXX)
target_link_libraries(ImageFilter ${ITK_LIBRARIES})
that's the reason why you set LINKER_LANGUAGE explicitly - there is nothing to link and cmake is confused.
So include_directories is enough:
include_directories(${PROJECT_SOURCE_DIR}/lib)
BTW:
You don't need to check ITK_FOUND if you specify REQUIRED:
FIND_PACKAGE (ITK REQUIRED)
IF( ITK_FOUND )
include( ${ITK_USE_FILE} )
ENDIF( ITK_FOUND )
from documentation:
The REQUIRED option stops processing with an error message if the package cannot be found.
PROJECT_SOURCE_DIR is not necessary equal itkNormals_SOURCE_DIR (you may use this file from other project):
include_directories(${PROJECT_SOURCE_DIR}/lib)
Can be fixed one of this way:
include_directories(${itkNormals_SOURCE_DIR}/lib)
include_directories(${CMAKE_CURRENT_LIST_DIR}/../lib)
or simply include from parent file:
# src/CMakeLists.txt
include_directories("./lib")