[CMake] intercomponent link dependencies?

[Michael Wild]

Hi Nico

In that case you need to do this:

add_library(${COMPONENT} IMPORTED)
set_target_properties(${COMPONENT} PROPERTIES
  IMPORTED_LOCATION "${${COMPONENT}_LIBRARY}"
  LINK_INTERFACE_LIBRARIES "${${COMPONENT}_LINK_INTERFACE_LIBRARIES}"
  )

where each of the components X has a variable X_LIBRARY containing its path on the system (e.g. determined by find_library(X_LIBRARY ...)) and a variable X_LINK_INTERFACE_LIBRARIES which you have to set outside the foreach loop.

HTH

Michael

On 7. Jan, 2010, at 11:51 , Nico Schlömer wrote:

> Hi Michael,
> 
> thanks for the explanations.
> 
> I'm indeed about to write a FindModule.cmake for a library which I did
> *not* write, but to certain components of which I'd like to link
> against using CMake (in a clean fashion).
> I'm FOREACHing through the components of the library, and upon trying to set
> 
>  ADD_LIBRARY( ${COMPONENT} )
> 
> cmake complains about
> 
>  add_library cannot create target "A" because another target with the
>  same name already exists.  The existing target is a static library created
>  in source directory "/path/to/A".  See
>  documentation for policy CMP0002 for more details.
> 
> Okay, so it exists already? Fine. Let's then
> 
>  SET_TARGET_PROPERTIES( ${COMPONENT} PROPERTIES
> LINK_INTERFACE_LIBRARIES "B;C;" )
> 
> -- but again, cmake complains that
> 
>  set_target_properties Can not find target to add properties to: A
> 
> TARGET_LINK_LIBRARIES doesn't work anyway as I'm not *building the
> libraries (cmake says).
> 
> Hmmm...
> Nico
> 
> 
> 
> On Thu, Jan 7, 2010 at 11:08 AM, Michael Wild <themiwi at gmail.com> wrote:
>> 
>> One quick question: Are these libraries created by you? In that case you shouldn't write a FindMymodule.cmake, but a MymoduleConfig.cmake (see the documentation of find_package).
>> 
>> Anyhow, to define the transitive link dependencies you can either use target_link_libraries(A LINK_INTERFACE_LIBRARIES B C) if your CMake is new enough, or you can use set_target_properties(A PROPERTIES LINK_INTERFACE_LIBRARIES "B;C"). Both solutions require that you use add_library(X IMPORTED) (where X = A, B and C) and set their IMPORTED_LOCATION property to the location on the file system. All of this is full automatic if you write a MymoduleConfig.cmake, because then you can use
>> 
>> install_targets(A B C EXPORT MymoduleExports
>>  ARCHIVE DESTINATION lib
>>  LIBRARY DESTINATION lib
>>  RUNTIME DESTINATION bin
>>  PUBLIC_HEADER DESTINATION include
>>  )
>> 
>> install(EXPORT MymoduleExports
>>  NAMESPACE Mymodule_
>>  DESTINATION share/mymodule/cmake
>>  )
>> 
>> which will install a file ${CMAKE_INSTALL_PREFIX}/share/mymodule/cmake/MymoduleExports.cmake containing all the IMPORT stuff and which you can INCLUDE in your MymoduleConfig.cmake.
>> 
>> 
>> I hope I could help a bit, otherwise tell us which case it is and I'll be able to help more.
>> 
>> Michael
>> 
>>