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Qt 5.9.1 cross compilation error



  • I am trying to cross compile Qt 5.9.1 with qtwebengine. But during the ninja build, this error is showing up and compilation is terminated. By default the build is using -std=gnu++11. I tried to force the build to use -std=c++11. But it is not working.
    To be honest, i am yet to understand the difference between -std=c++11 and -std=gnu++11. Can anyone point out what i am doing wrong here ?
    Thank you for looking into it.

    ../../3rdparty/chromium/third_party/angle/src/compiler/translator/ExpandIntegerPowExpressions.cpp:99:29: error: ‘round’ is not a member of ‘std’
         float frac   = absval - std::round(absval);
                                 ^
    ../../3rdparty/chromium/third_party/angle/src/compiler/translator/ExpandIntegerPowExpressions.cpp:99:29: note: suggested alternative:
    In file included from /opt/arm-hisiv300-linux/target/usr/include/features.h:416:0,
                     from /opt/arm300/arm300-linux-uclibcgnueabi/include/c++/4.8.3/arm300-linux-uclibcgnueabi/bits/os_defines.h:39,
                     from /opt/arm300-linux/arm300-linux-uclibcgnueabi/include/c++/4.8.3/arm300-linux-uclibcgnueabi/bits/c++config.h:426,
                     from /opt/arm300-linux/arm300-linux-uclibcgnueabi/include/c++/4.8.3/cmath:41,
                     from ../../3rdparty/chromium/third_party/angle/src/compiler/translator/ExpandIntegerPowExpressions.cpp:11:
    /opt/arm300-linux/target/usr/include/bits/mathcalls.h:326:1: note:   ‘round’
     __MATHCALLX (round,, (_Mdouble_ __x), (__const__))
     ^
    [7/15335] CXX obj/third_party/angle/translator/IntermNode.o
    ninja: build stopped: subcommand failed.
    Makefile.gn_run:796: recipe for target 'run_ninja' failed
    make[4]: *** [run_ninja] Error 1
    make[4]: Leaving directory '/opt/qt/qt5.9.1arm_source/qt-everywhere-opensource-src-5.9.1/qtwebengine/src/core'
    Makefile:80: recipe for target 'sub-gn_run-pro-make_first' failed
    make[3]: *** [sub-gn_run-pro-make_first] Error 2
    make[3]: Leaving directory '/opt/qt/qt5.9.1arm_source/qt-everywhere-opensource-src-5.9.1/qtwebengine/src/core'
    Makefile:77: recipe for target 'sub-core-make_first' failed
    make[2]: *** [sub-core-make_first] Error 2
    make[2]: Leaving directory '/opt/qt/qt5.9.1arm_source/qt-everywhere-opensource-src-5.9.1/qtwebengine/src'
    Makefile:46: recipe for target 'sub-src-make_first' failed
    make[1]: *** [sub-src-make_first] Error 2
    make[1]: Leaving directory '/opt/qt/qt5.9.1arm_source/qt-everywhere-opensource-src-5.9.1/qtwebengine'
    Makefile:834: recipe for target 'module-qtwebengine-make_first' failed
    make: *** [module-qtwebengine-make_first] Error 2
    

    This is the configuration i am following

    ./configure -c++std c++11  -opensource -confirm-license -xplatform linux-arm-g++ -skip wayland -no-xcb -nomake tests -nomake examples -c++std c++11 -v -prefix /opt/qt/qt5.9.1arm -proprietary-codecs -alsa -fontconfig -tslib -skip qt3d  -skip serialbus -skip svg -sysroot /opt/arm300-linux/target -L/opt/arm300-linux/target/lib -I/opt/arm300-linux/target/include -DMESA_EGL_NO_X11_HEADERS
    

  • Lifetime Qt Champion

    Hi,

    AFAIK, gnu++11 is the C++11 standard plus GNU extensions. Note that you don't need to modify that as Qt 5 requires support for C++11 since 5.7.



  • @SGaist Thanks for the information. I can't really figure out why this is an error. My arm toolchain is based on gcc version 4.8.3. I believe this version supports c++11.
    In some other forums, it says round is defined from c++11 standard.
    Can i avoid this error if i skip angle ?
    I am building Qt for linux and i have cross compiled mesa libraries.


  • Lifetime Qt Champion

    Just realised you are using uClibc, I don't know how much of the standard it implements.



  • @SGaist You mean uClibc doesn't implement all the c++11 standard ?
    Edit :
    I went through this link to understand the difference.
    So basically when you are trying to compile a huge source like Qt, uClibc may not give you all the standards.



  • As @SGaist have said uClibc doesn't support c++11 standard as a whole. I have switched to another arm compiler based on Glibc and this error doesn't show up.


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