[CMake] Fwd: Removing overkill linking

[Paul McEnery]

On 2 October 2010 21:49, Marcel (ASTRON) <loose at astron.nl> wrote:
> Op zaterdag 02-10-2010 om 19:11 uur [tijdzone +0100], schreef Paul
> McEnery:
>> No sure what happened to this message. I checked the list archive, and
>> only half of the message appeared....
>>
>> http://www.cmake.org/pipermail/cmake/2010-October/039975.html
>>
>>
>> On 1 October 2010 16:40, Marcel Loose <loose at astron.nl> wrote:
>> > Hi Paul,
>> >
>> > Probably one of the packages that you "pull in" -- dbus, dbug-glib,
>> > libftdi, libglade, gtk+2, hal -- is introducing this dependency. Check
>> > the different *_LIBRARIES variables and you'll probably find the fly in
>> > your ointment.
>> >
>> > You may definitely want to look into the LINK_INTERFACE_LIBRARIES option
>> > of target_link_libraries to avoid over-linking.
>> >
>>
>> Thanks Marcel.
>>
>> I have managed to solve the issue on the shared library, however, I'm
>> still having an issue with the executable being excessively linked.
>> I've tried a number of different ways, but don't think I have the
>> syntax right for what I'm trying to achieve.
>>
>> ====================================
>> # Dependencies
>> find_package      (PkgConfig)
>> pkg_check_modules (DBUS       REQUIRED   dbus-1>=1.2.12)
>> pkg_check_modules (DBUS-GLIB  REQUIRED   dbus-glib-1>=0.80)
>> pkg_check_modules (FTDI       REQUIRED   libftdi>=0.13)
>> pkg_check_modules (GLADE      REQUIRED   libglade-2.0>=2.6.4)
>> pkg_check_modules (GTK2       REQUIRED   gtk+-2.0>=2.16.1)
>> pkg_check_modules (HAL        REQUIRED   hal>=0.5.12)
>>
>> # Main config
>> add_definitions(-DGLADEFILE="${CMAKE_INSTALL_PREFIX}/${sharedir}/galinette_gtk.glade")
>> add_definitions(-DGALINETTE_VERSION="${GALINETTE_VERSION}")
>>
>> # Include & build
>> include_directories   (. ${DBUS_INCLUDE_DIRS}
>> ${DBUS-GLIB_INCLUDE_DIRS} ${GLADE_INCLUDE_DIRS} ${GTK2_INCLUDE_DIRS}
>> ${HAL_INCLUDE_DIRS})
>> add_executable        (galinette callbacks.c callbacks.h
>> galinette-gtk.c galinette_gtk.glade galinette-gtk.h hal.c hal.h
>> main.c)
>> add_dependencies      (galinette libgalinette)
>> target_link_libraries (galinette libgalinette ${DBUS_LIBRARIES}
>> ${DBUS-GLIB_LIBRARIES} ${GLADE_LIBRARIES} ${GTK2_LIBRARIES}
>> ${HAL_LIBRARIES})
>> target_link_libraries (galinette LINK_INTERFACE_LIBRARIES "")
>>
>> # Other resources
>> add_custom_target (galinette_gtk.glade)
>>
>> # Install
>> install (TARGETS galinette           DESTINATION ${bindir})
>> install (FILES   galinette_gtk.glade DESTINATION ${sharedir})
>> ====================================
>>
>> From what I can gather from the lists and documentation, executables
>> are handled slightly differently to libraries. To solve the library
>> issue, I used the following which worked correctly:
>>
>> ====================================
>> # Dependencies
>> find_package          (PkgConfig)
>> pkg_check_modules     (FTDI  REQUIRED  libftdi>=0.13)
>>
>> # Include & build
>> include_directories   (. ${FTDI_INCLUDE_DIRS})
>> add_library           (libgalinette SHARED device.c error.c firmware.c
>> flash.c libgalinette.h libgalinette-private.h)
>> set_target_properties (libgalinette PROPERTIES PREFIX ""
>> LINK_INTERFACE_LIBRARIES "" SOVERSION 0)
>> target_link_libraries (libgalinette ${FTDI_LIBRARIES})
>>
>> # Install
>> install (TARGETS libgalinette LIBRARY DESTINATION ${libdir})
>> ====================================
>>
>> set_target_properties doesn't seem to work on executables though.
>>
>> Hopefully someone who knows a bit more than I do will be able to spot
>> what I'm doing wrong...
>>
>> Kind regards,
>> Paul.
> Hi Paul,
>
> How exactly did you check which libraries your executable are linked to.
> If on Linux, you should use 'readelf -d', not 'ldd'. The latter will
> also show all transitive dependencies, which is useful, of course, when
> you want to know which libraries are needed. However, 'ldd' gives you a
> false impression w.r.t. overlinking.
>

Hi Marcel.

Thanks for the reply. I was relying on dpkg-shlibs which was throwing
the warnings about unnecessary linking. I've just gone back now and
checked the binary with readelf -d, and this too is showing the links
to unneeded libraries.

I have tried a number of different configurations, but I just cant
find examples of how to correctly use LINK_INTERFACE_LIBRARIES with an
executable - rather than a library. Here is my most recent attempt:

http://pastebin.com/JdVPvYim

=============================
[...]
#
# Include & build
#
include_directories   (. ${DBUS_INCLUDE_DIRS}
${DBUS-GLIB_INCLUDE_DIRS} ${GLADE_INCLUDE_DIRS} ${GTK2_INCLUDE_DIRS}
${HAL_INCLUDE_DIRS})
add_executable        (galinette callbacks.c callbacks.h
galinette-gtk.c galinette_gtk.glade galinette-gtk.h hal.c hal.h
main.c)
add_dependencies      (galinette libgalinette)
target_link_libraries (galinette LINK_INTERFACE_LIBRARIES libgalinette
${DBUS_LIBRARIES} ${DBUS-GLIB_LIBRARIES} ${GLADE_LIBRARIES}
${GTK2_LIBRARIES} ${HAL_LIBRARIES})
 [...]
=============================

But this just seems to lose all the linking altogether.

I cant seem to find any projects that use LINK_INTERFACE_LIBRARIES to
control linking with regard to "executables" rather than libraries.

I assume the above simply has some sort of syntax incorrect. Hopefully
someone can spot the issue and point me in the right direction.

Regards,
Paul.