[CMake] Dependent Libraries added automatically?

[Michael Jackson]

On Sep 26, 2008, at 2:28 PM, Bill Hoffman wrote:

> Mike Jackson wrote:
>> I started noticing some warnings when I am linking my project  
>> executables that bascially says libraries are listed multiple times  
>> on the link line. Now this is just a warning so I _could_ ignore it  
>> but I am curios about how cmake is working at this point. Here is  
>> what I have:
>> Library MXADataModel built by CMake.
>> It depends on Expat, Tiff and HDF5 (which are installed on the  
>> local filesystem and NOT build by cmake).
>> I have some Examples that are built in the same project as the  
>> MXADataModel library. Lets take one of those examples as and  
>> "example"..
>> SET (DATAIMPORT_EXAMPLE_SOURCES
>> ${MXA_SOURCE_DIR}/src/Examples/DataImport/main.cpp
>> ${MXA_SOURCE_DIR}/src/Examples/DataImport/SimpleImportExample.cpp
>> ${MXA_SOURCE_DIR}/src/Examples/DataImport/ExampleImportDelegate.cpp
>> ${MXA_SOURCE_DIR}/src/Examples/DataImport/ 
>> ExampleImportDelegateFactory.cpp
>> )
>> SET (DATAIMPORT_EXAMPLE_HEADERS
>>  ${MXA_SOURCE_DIR}/src/Examples/DataImport/SimpleImportExample.h
>>  ${MXA_SOURCE_DIR}/src/Examples/DataImport/ExampleImportDelegate.h
>>  ${MXA_SOURCE_DIR}/src/Examples/DataImport/ 
>> ExampleImportDelegateFactory.h
>> )
>> source_group(src\\Examples\\DataImport FILES $ 
>> {DATAIMPORT_EXAMPLE_SOURCES} ${DATAIMPORT_EXAMPLE_HEADERS})
>> ADD_EXECUTABLE(DataImportExample ${DATAIMPORT_EXAMPLE_SOURCES})
>> TARGET_LINK_LIBRARIES(DataImportExample ${MXADATAMODEL_LIB_NAME} )
>> MXADATAMODEL_LIB_NAME is the name of the MXADataModel library that  
>> is built earlier in the project and has dependencies on hdf5, tiff  
>> and expat.
>> If I use the code as is then cmake will actually add the tiff, hdf5  
>> and expat libraries to the link line. Is CMake _supposed_ to do  
>> that? This is building shared libraries and tiff, expat and hdf5  
>> are all dylibs also. Building MXADataModel as a static library  
>> shows the same behavior.
>> This is on OS X 10.5.5 with Xcode 3.1.x tooling generating  
>> Makefiles. Same thing using Xcode generated targets. So maybe I  
>> just don't understand how linking works on OS X?
>> Just wondering if I make changes to the CMake files will it mess up  
>> windows builds?
> Yes, cmake automatically chains this stuff.
>
> add_library(a ...)
> target_link_library(a b c)
>
> add_executable(foo ...)
> target_link_libraries(foo a)
>
> This will cause foo to link to a b c.
>
> With CMake 2.6.2 you can stop this from happening with a target  
> property:
>
> http://www.cmake.org/cmake/help/ 
> cmake2.6docs.html#prop_tgt:LINK_INTERFACE_LIBRARIES
>
> -Bill

And just to be clear this will work on all platforms, all compilers?

Mike.