[Solved] Clang on Pi returns undefined reference to `operator new(unsigned long)'



  • Hi. I am stuck trying to link programs using clang. All is fine with gcc, but when I use either of these with the current Raspbian

    QT5
    @qmake -makefile -spec linux-clang
    @

    Or QT4

    @qmake -makefile -spec unsupported/linux-clang
    @

    At link time this happens:

    main.o: In function main': main.cpp:(.text+0x2c): undefined reference tooperator new(unsigned long)'
    main.cpp:(.text+0xa0): undefined reference to `QArrayData::deallocate(QArrayData*, unsigned long, unsigned long)'
    clang: error: linker command failed with exit code 1 (use -v to see invocation)
    make: *** [clang_test2] Error 1

    It happens even with the simplest of programs, for example this:

    main.cpp

    @#include <QApplication>
    #include <QPushButton>
    int main(int argc, char **argv)
    {
    QApplication app (argc, argv);
    QPushButton *b = new QPushButton ("Hello world !");
    QObject::connect(b,SIGNAL(pressed()),&app,SLOT(closeAllWindows()));
    b->show();
    app.exec();
    delete b;
    }@

    simple_test.pro

    @TEMPLATE = app
    TARGET = clang_test2
    QT = core gui
    greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
    SOURCES += main.cpp@

    Anyone any ideas?


  • Moderators

    linux-clang is a mkspec written for x86 architecture. You need to modify the linux-rasp-pi-g++ to use clang, then it should work.



  • Cool, thank you! I didn't realise clang could interpret so many of gcc's options and switches. I literally replaced g++ with clang and it ran!

    Being curious I took the compile and link commands make generated and deleted the options one at a time until it broke as before. The simplest working compile and link is

    @clang -c -mabi=aapcs-linux -fPIE -I/usr/include/qt5 -I/usr/include/qt5/QtWidgets -o main.o main.cpp
    clang -o clang_test2 main.o -lQt5Widgets -lstdc++@

    and if you drop the -mabi=aapcs-linux option on the compiler you get the error about the missing new operator.


  • Moderators

    Good inqusitiveness :-) I'm glad it helped you. Happy coding


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