[CMake] Setting IMPORTED_LOCATION_* for existing packages

[Michael Hertling]

On 09/22/2011 09:21 PM, Hauke Heibel wrote:
> Hi Michael,
> 
> First, thank you for the feedback.
> 
> On Thu, Sep 22, 2011 at 7:19 PM, Michael Hertling <mhertling at online.de> wrote:
>> AFAICS, you've a single imported target GTest, and you are continuously
>> setting *this* target's location - sometimes for a debug configuration,
>> sometimes without configuration - to the location of its *prerequisite*
>> libraries reported by the GTest package's find module or config file.
> 
> If I am not totally wrong, in this case I am only setting the GTest
> libraries and no additional *prerequisite*. The variable
> GTEST_LIBRARIES only contains full qualified paths to gtest.lib and
> gtestd.lib.
> 
>> IMO, this doesn't make any sense. Possibly, you want to set the GTest
>> target's IMPORTED_LINK_INTERFACE_LIBRARIES[_<CONFIG>] properties in
>> place of the IMPORTED_LOCATION[_<CONFIG>] ones.
> 
> Maybe I am wrong, but I just tried to copy what is done in the
> FindQt4.cmake file or in other words to manually define what the
> export() directive generates. I recognized an issue since I forgot to
> define the property IMPORTED_CONFIGURATIONS. If I did not
> misunderstand things completely, you were right if GTEST_LIBRARIES
> would contain non GTest libs (the prerequisites).
> 
>> What do you actually intent to achieve? Introduce a GTest imported
>> target and set up its prerequisites reported in GTEST_LIBRARIES as
>> it would be done for imported targets from the first?
> 
> I think that's pretty much what I want to do. Create the import target
> as if GTest were compiled with an export() directive.
> 
>> Doesn't the
>> GTEST_LIBRARIES variable per se work for you?
> 
> To be honest, in this case it does. Maybe the example was bad. I think
> I really need it for shared library targets, such as e.g. OpenCL.
> 
> I want to prepare my libraries such that in the future a CMake based
> installation also collects and installs DLLs of interface libraries. I
> am further assuming that if I define a target of mine and link it
> against an imported (let's say) OpenCL target with properly specified
> IMPORTED_LOCATION (the DLL for shared libs), install() will copy it
> for me.

No, it won't:

CMAKE_MINIMUM_REQUIRED(VERSION 2.8 FATAL_ERROR)
PROJECT(IMPORTTARGET C)
SET(CMAKE_VERBOSE_MAKEFILE ON)
FILE(WRITE ${CMAKE_BINARY_DIR}/main.c "int main(void){return 0;}\n")
ADD_EXECUTABLE(main main.c)
FIND_LIBRARY(M_LIBRARY m PATHS /usr/lib NO_DEFAULT_PATH)
ADD_LIBRARY(m SHARED IMPORTED)
SET_TARGET_PROPERTIES(m PROPERTIES IMPORTED_LOCATION ${M_LIBRARY})
TARGET_LINK_LIBRARIES(main m)
INSTALL(TARGETS main RUNTIME DESTINATION bin)

As you'll see after "cmake -DCMAKE_INSTALL_PREFIX=/dev/shm/usr ...",
e.g., a "make install" will install the main executable but not the
prerequisite libm.so library. Imported targets are meant to inform
the project about targets already built - and possibly installed -
by other projects; they don't suit to resolve a project's external
dependencies during the installation. If you need this, you
should definitely have a look at the BundleUtilities.

> Maybe that's long shot - I need to read more about the actual
> installation process and how it deals with dependencies.
> 
> Regards,
> Hauke

Regards,

Michael