[Qt-creator] error with position independent code : qt 5.x

[Konstantin Tokarev]

16.09.2016, 18:09, "Tobias Hunger" <tobias.hunger at gmail.com>:
> Hi Kapil,
>
> according to the error message you will need to build your code with
> -fPIC. Not very helpful, but the best I can do with that information,
> sorry.
>
> https://cmake.org/cmake/help/v3.6/variable/CMAKE_POSITION_INDEPENDENT_CODE.html#variable:CMAKE_POSITION_INDEPENDENT_CODE
> might help though:-)
>
> You will need to figure out how to tell that to your project's build
> system. That is a task I do not expect creator being able to help with
> -- each project has its own set of particularities:-/

When Qt5Core module is linked to the target, it adds -fPIC automatically in case Qt requires it. So this error usually happens when tartget's sources include Qt headers but no Qt library is linked.

>
> Best Regards,
> Tobias
>
> On Fri, Sep 16, 2016 at 4:28 PM, Kapil Gupta <kpgupta98 at gmail.com> wrote:
>>  Hi,
>>
>>  I am having this error with qt code :
>>  ```
>>  In file included from
>>  /usr/include/x86_64-linux-gnu/qt5/QtCore/qnamespace.h:37:0,
>>                   from
>>  /usr/include/x86_64-linux-gnu/qt5/QtCore/qobjectdefs.h:41,
>>                   from /usr/include/x86_64-linux-gnu/qt5/QtCore/qobject.h:40,
>>                   from
>>  /usr/include/x86_64-linux-gnu/qt5/QtMultimedia/qaudioformat.h:38,
>>                   from
>>  /home/cortana/libdash/libdash/qtplayer/libdashframework/Buffer/AudioChunk.h:16,
>>                   from
>>  /home/cortana/libdash/libdash/qtplayer/libdashframework/Buffer/AudioChunk.cpp:12:
>>  /usr/include/x86_64-linux-gnu/qt5/QtCore/qglobal.h:1067:4: error: #error
>>  "You must build your code with position independent code if Qt was built
>>  with -reduce-relocations. " "Compile your code with -fPIC (-fPIE is not
>>  enough)."
>>   # error "You must build your code with position independent code if Qt was
>>  built with -reduce-relocations. "\
>>      ^
>>  [ 57%] Building CXX object
>>  CMakeFiles/qtsampleplayer.dir/libdashframework/Buffer/MediaObjectBuffer.cpp.o
>>  [ 60%] Building CXX object
>>  CMakeFiles/qtsampleplayer.dir/libdashframework/Input/DASHReceiver.cpp.o
>>  [ 63%] Building CXX object
>>  CMakeFiles/qtsampleplayer.dir/libdashframework/Input/MediaObject.cpp.o
>>  [ 66%] Building CXX object
>>  CMakeFiles/qtsampleplayer.dir/libdashframework/Input/DASHManager.cpp.o
>>  CMakeFiles/qtsampleplayer.dir/build.make:389: recipe for target
>>  'CMakeFiles/qtsampleplayer.dir/libdashframework/Buffer/AudioChunk.cpp.o'
>>  failed
>>  make[2]: ***
>>  [CMakeFiles/qtsampleplayer.dir/libdashframework/Buffer/AudioChunk.cpp.o]
>>  Error 1
>>  make[2]: *** Waiting for unfinished jobs....
>>  In file included from
>>  /usr/include/x86_64-linux-gnu/qt5/QtCore/qnamespace.h:37:0,
>>                   from
>>  /usr/include/x86_64-linux-gnu/qt5/QtCore/qobjectdefs.h:41,
>>                   from /usr/include/x86_64-linux-gnu/qt5/QtCore/qobject.h:40,
>>                   from
>>  /usr/include/x86_64-linux-gnu/qt5/QtMultimedia/qaudioformat.h:38,
>>                   from
>>  /home/cortana/libdash/libdash/qtplayer/libdashframework/Input/DASHManager.h:23,
>>                   from
>>  /home/cortana/libdash/libdash/qtplayer/libdashframework/Input/DASHManager.cpp:12:
>>  /usr/include/x86_64-linux-gnu/qt5/QtCore/qglobal.h:1067:4: error: #error
>>  "You must build your code with position independent code if Qt was built
>>  with -reduce-relocations. " "Compile your code with -fPIC (-fPIE is not
>>  enough)."
>>   # error "You must build your code with position independent code if Qt was
>>  built with -reduce-relocations. "\
>>  ```
>>  What can I do to remove this error? The code is the libdash library's
>>  qtsampleplayer which is based on cmake.
>>
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>
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-- 
Regards,
Konstantin