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"Undebuggable" segmentation fault

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  • M Offline
    M Offline
    Mark81
    wrote on last edited by
    #1

    I wrote a simple custom editor for a QTableView delegate:

    class SignatureEditor : public QWidget
    {
        Q_OBJECT
    
    public:
        explicit SignatureEditor(QWidget *parent = nullptr) : QWidget(parent)
        {
            QHBoxLayout *layout = new QHBoxLayout();
            _btn.setText("...");
            _btn.setSizePolicy(QSizePolicy::Minimum, QSizePolicy::Expanding);
            QFont font = _btn.font();
            font.setPointSize(8);
            _btn.setFont(font);
            _line.setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
            layout->setContentsMargins(0, 0, 0, 0);
            layout->setSpacing(0);
            layout->addWidget(&_line);
            layout->addWidget(&_btn);
            this->setLayout(layout);
    
            connect(&_btn, &QToolButton::clicked, [this]()
            {
                QString filename = QFileDialog::getOpenFileName(this, tr("Select signature image"), QDir::homePath(), tr("Portable Network Graphics (*.png)"));
                if (!filename.isEmpty()) this->_line.setText(filename);
            });
        }
    
        void setText(QString text) { _line.setText(text); }
        QString text() { return _line.text(); }
        void activate() { _line.setFocus(); }
    
    private:
        QLineEdit _line;
        QToolButton _btn;
    };
    

    but when I close the file dialog (either pressing cancel or selecting a file) I get a segmentation fault, but the debugger doesn't show any piece of my code:

    0_1548250767089_Clipboard 1.jpg

    I looked into all 17 threads but none shows anything useful (only disassembled code).
    Hence I don't understand neither where is my error nor how to debug this...

    1 Reply Last reply
    0
    • mrjjM Offline
      mrjjM Offline
      mrjj
      Lifetime Qt Champion
      wrote on last edited by mrjj
      #2

      hi
      You have
      private:
      QLineEdit _line;
      QToolButton _btn;

      which means if you put those in any layout/assign parent you would/might get double deletion as
      parent will delete them (Qt) and then they are also allocated as part of the c++ clean up as they are
      not pointers. and are deleted as part of the holding class destruction.
      So make them pointers and new them and see if issue goes away.

      M 1 Reply Last reply
      2
      • mrjjM mrjj

        hi
        You have
        private:
        QLineEdit _line;
        QToolButton _btn;

        which means if you put those in any layout/assign parent you would/might get double deletion as
        parent will delete them (Qt) and then they are also allocated as part of the c++ clean up as they are
        not pointers. and are deleted as part of the holding class destruction.
        So make them pointers and new them and see if issue goes away.

        M Offline
        M Offline
        Mark81
        wrote on last edited by Mark81
        #3

        @mrjj said in "Undebuggable" segmentation fault:

        So make them pointers and new them and see if issue goes away.

        Code updated:

        class SignatureEditor : public QWidget
        {
            Q_OBJECT
        
        public:
            explicit SignatureEditor(QWidget *parent = nullptr) : QWidget(parent)
            {
                QHBoxLayout *layout = new QHBoxLayout();
                _btn = new QToolButton();
                _btn->setText("...");
                _btn->setSizePolicy(QSizePolicy::Minimum, QSizePolicy::Expanding);
                QFont font = _btn->font();
                font.setPointSize(8);
                _btn->setFont(font);
        
                _line = new QLineEdit();
                _line->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
                layout->setContentsMargins(0, 0, 0, 0);
                layout->setSpacing(0);
                layout->addWidget(_line);
                layout->addWidget(_btn);
                this->setLayout(layout);
        
                connect(_btn, &QToolButton::clicked, [this]()
                {
                    QString filename = QFileDialog::getOpenFileName(this, tr("Select signature image"), QDir::homePath(), tr("Portable Network Graphics (*->png)"));
                    if (!filename.isEmpty())
                    {
                        this->_line->setText(filename);
                    }
                });
            }
        
            void setText(QString text) { _line->setText(text); }
            QString text() { return _line->text(); }
            void activate() { _line->setFocus(); }
        
        private:
            QLineEdit *_line;
            QToolButton *_btn;
        };
        

        and here its usage:

        CustomDelegateOperators::CustomDelegateOperators(QObject *parent) : QStyledItemDelegate(parent) { }
        
        QWidget *CustomDelegateOperators::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex & index ) const
        {
            switch (index.column())
            {
            case MODEL_OPERATORS_COL_SIGNATURE:   {  SignatureEditor *editor = new SignatureEditor(parent);  return editor; }
            default: return QStyledItemDelegate::createEditor(parent, option, index);
            }
        }
        
        void CustomDelegateOperators::setEditorData(QWidget *editor, const QModelIndex &index) const
        {
            switch (index.column())
            {
            case MODEL_OPERATORS_COL_SIGNATURE:
            {
                QString value = index.model()->data(index, Qt::EditRole).toString();
                SignatureEditor *widget = static_cast<SignatureEditor *>(editor);
                widget->setText(value);
                widget->activate();
                break;
            }
            default: QStyledItemDelegate::setEditorData(editor, index); break;
            }
        }
        
        void CustomDelegateOperators::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &idx) const
        {
            switch (idx.column())
            {
            case MODEL_OPERATORS_COL_SIGNATURE:
            {
                SignatureEditor *widget = static_cast<SignatureEditor *>(editor);
                QString value = widget->text();
                // TODO: save model data
                break;
            }
            default:
                QStyledItemDelegate::setModelData(editor, model, idx);
                break;
            }
        }
        

        Nothing has changed.
        Another bit of information. The seg fault is due to the file dialog call. If I remove it (i.e. adding just a Debug() << "pressed") it works. But leaving only:

        QString filename = QFileDialog::getOpenFileName(this, tr("Select signature image"), QDir::homePath(), tr("Portable Network Graphics (*->png)"));
        

        leads to the seg fault.

        1 Reply Last reply
        0
        • M Offline
          M Offline
          Mark81
          wrote on last edited by Mark81
          #4

          Partially fixed:

          QString filename = QFileDialog::getOpenFileName(nullptr, tr("Select signature image"), QDir::homePath(), tr("Portable Network Graphics (*->png)"));
          

          Now I can open and close the file dialog, but if I select a file the segmentation fault happens here:

          this->_line->setText(filename);
          

          it seems it doesn't like "this". But I don't know why.
          Furthermore if I place a breakpoint there, it will stops, but the debugger shows no information about variables.

          1 Reply Last reply
          0
          • mrjjM Offline
            mrjjM Offline
            mrjj
            Lifetime Qt Champion
            wrote on last edited by mrjj
            #5

            Hi
            Its looks ok.
            however, every place you do
            SignatureEditor *widget = static_cast<SignatureEditor *>(editor);
            should make a check if is not null.
            before using it.

            the error/crash you get looks like being inside invalid object. ( not liking this ptr etc )

            so i would start check each cast.

            SignatureEditor *widget = static_cast<SignatureEditor *>(editor);
            if (widget) {
              widget->setText(value);
              widget->activate();
            } else
              qDebug() << "invalid cast for editor";
            
            M 1 Reply Last reply
            2
            • mrjjM mrjj

              Hi
              Its looks ok.
              however, every place you do
              SignatureEditor *widget = static_cast<SignatureEditor *>(editor);
              should make a check if is not null.
              before using it.

              the error/crash you get looks like being inside invalid object. ( not liking this ptr etc )

              so i would start check each cast.

              SignatureEditor *widget = static_cast<SignatureEditor *>(editor);
              if (widget) {
                widget->setText(value);
                widget->activate();
              } else
                qDebug() << "invalid cast for editor";
              
              M Offline
              M Offline
              Mark81
              wrote on last edited by Mark81
              #6

              @mrjj said in "Undebuggable" segmentation fault:

              so i would start check each cast.

              They return a non-zero pointer (i.e. no debug message is shown). And the address is the same among the creation of the editor and the two casts.

              mrjjM 1 Reply Last reply
              0
              • M Mark81

                @mrjj said in "Undebuggable" segmentation fault:

                so i would start check each cast.

                They return a non-zero pointer (i.e. no debug message is shown). And the address is the same among the creation of the editor and the two casts.

                mrjjM Offline
                mrjjM Offline
                mrjj
                Lifetime Qt Champion
                wrote on last edited by
                #7

                @Mark81
                Hi
                ok, so seems not that.
                Could you try with a completely normal slot and not a lambda ?

                M 1 Reply Last reply
                0
                • mrjjM mrjj

                  @Mark81
                  Hi
                  ok, so seems not that.
                  Could you try with a completely normal slot and not a lambda ?

                  M Offline
                  M Offline
                  Mark81
                  wrote on last edited by
                  #8

                  @mrjj said in "Undebuggable" segmentation fault:

                  Could you try with a completely normal slot and not a lambda ?

                  Ahah, you read my mind. I've already done that with the same results.
                  Is really so difficult to do what I'm trying to achieve?

                  mrjjM 1 Reply Last reply
                  0
                  • M Mark81

                    @mrjj said in "Undebuggable" segmentation fault:

                    Could you try with a completely normal slot and not a lambda ?

                    Ahah, you read my mind. I've already done that with the same results.
                    Is really so difficult to do what I'm trying to achieve?

                    mrjjM Offline
                    mrjjM Offline
                    mrjj
                    Lifetime Qt Champion
                    wrote on last edited by
                    #9

                    @Mark81
                    hi
                    Hmm. out of ideas then.
                    No, it seems very ok to have a custom widget and open a file dialog.

                    so if it crashes at
                    this->_line->setText(filename);
                    its either "this" or _line that is not ok and we need to find out why.
                    i assume
                    this->_line->setText("test");
                    with no dialog also crashes ?

                    M 1 Reply Last reply
                    0
                    • mrjjM mrjj

                      @Mark81
                      hi
                      Hmm. out of ideas then.
                      No, it seems very ok to have a custom widget and open a file dialog.

                      so if it crashes at
                      this->_line->setText(filename);
                      its either "this" or _line that is not ok and we need to find out why.
                      i assume
                      this->_line->setText("test");
                      with no dialog also crashes ?

                      M Offline
                      M Offline
                      Mark81
                      wrote on last edited by
                      #10

                      @mrjj said in "Undebuggable" segmentation fault:

                      i assume
                      this->_line->setText("test");
                      with no dialog also crashes ?

                      Instead this works!
                      BUT:

                      this also works:

                      connect(_btn, &QToolButton::clicked, [this]()
                              {
                                  QString filename = QFileDialog::getOpenFileName(nullptr, tr("Select signature image"), QDir::homePath(), tr("Portable Network Graphics (*.png)"));
                              });
                      

                      while this crashes:

                      connect(_btn, &QToolButton::clicked, [this]()
                              {
                                  QString filename = QFileDialog::getOpenFileName(nullptr, tr("Select signature image"), QDir::homePath(), tr("Portable Network Graphics (*.png)"));
                                  this->_line->setText("test");
                              });
                      
                      kshegunovK 1 Reply Last reply
                      0
                      • mrjjM Offline
                        mrjjM Offline
                        mrjj
                        Lifetime Qt Champion
                        wrote on last edited by
                        #11

                        Hi
                        but

                        connect(_btn, &QToolButton::clicked, [this]()
                                {            
                                    this->_line->setText("test");
                                });
                        

                        does not crash? so it does seems to be dialog related ?

                        M 1 Reply Last reply
                        0
                        • mrjjM mrjj

                          Hi
                          but

                          connect(_btn, &QToolButton::clicked, [this]()
                                  {            
                                      this->_line->setText("test");
                                  });
                          

                          does not crash? so it does seems to be dialog related ?

                          M Offline
                          M Offline
                          Mark81
                          wrote on last edited by
                          #12

                          @mrjj said in "Undebuggable" segmentation fault:

                          does not crash? so it does seems to be dialog related ?

                          Exactly, this doesn't crash and fill the QLineEdit with the string.

                          1 Reply Last reply
                          0
                          • M Mark81

                            @mrjj said in "Undebuggable" segmentation fault:

                            i assume
                            this->_line->setText("test");
                            with no dialog also crashes ?

                            Instead this works!
                            BUT:

                            this also works:

                            connect(_btn, &QToolButton::clicked, [this]()
                                    {
                                        QString filename = QFileDialog::getOpenFileName(nullptr, tr("Select signature image"), QDir::homePath(), tr("Portable Network Graphics (*.png)"));
                                    });
                            

                            while this crashes:

                            connect(_btn, &QToolButton::clicked, [this]()
                                    {
                                        QString filename = QFileDialog::getOpenFileName(nullptr, tr("Select signature image"), QDir::homePath(), tr("Portable Network Graphics (*.png)"));
                                        this->_line->setText("test");
                                    });
                            
                            kshegunovK Offline
                            kshegunovK Offline
                            kshegunov
                            Moderators
                            wrote on last edited by kshegunov
                            #13

                            Does this:

                            connect(_btn, &QToolButton::clicked, this, [this] () -> void  {
                                QString filename = QFileDialog::getOpenFileName(nullptr, tr("Select signature image"), QDir::homePath(), tr("Portable Network Graphics (*.png)"));
                                _line->setText("test");
                            });
                            

                            crash?

                            From the behaviour described it does seem you have a dangling pointer/reference. Also don't do that:

                            SignatureEditor *widget = static_cast<SignatureEditor *>(editor);
                            

                            without at least having a debug-time check on it:

                            Q_ASSERT(qobject_cast<SignatureEditor *>(editor));
                            SignatureEditor *widget = static_cast<SignatureEditor *>(editor);
                            

                            Read and abide by the Qt Code of Conduct

                            M 1 Reply Last reply
                            1
                            • kshegunovK kshegunov

                              Does this:

                              connect(_btn, &QToolButton::clicked, this, [this] () -> void  {
                                  QString filename = QFileDialog::getOpenFileName(nullptr, tr("Select signature image"), QDir::homePath(), tr("Portable Network Graphics (*.png)"));
                                  _line->setText("test");
                              });
                              

                              crash?

                              From the behaviour described it does seem you have a dangling pointer/reference. Also don't do that:

                              SignatureEditor *widget = static_cast<SignatureEditor *>(editor);
                              

                              without at least having a debug-time check on it:

                              Q_ASSERT(qobject_cast<SignatureEditor *>(editor));
                              SignatureEditor *widget = static_cast<SignatureEditor *>(editor);
                              
                              M Offline
                              M Offline
                              Mark81
                              wrote on last edited by
                              #14

                              @kshegunov said in "Undebuggable" segmentation fault:

                              Does this:

                              connect(_btn, &QToolButton::clicked, this, [this] () -> void  {
                                  QString filename = QFileDialog::getOpenFileName(nullptr, tr("Select signature image"), QDir::homePath(), tr("Portable Network Graphics (*.png)"));
                                  _line->setText("test");
                              });
                              

                              crash?

                              Yes, it crashes.

                              From the behaviour described it does seem you have dangling pointer/reference. Also don't do that:
                              without at least having a debug time check on it:

                              We've already checked the pointers and are not null.

                              kshegunovK 1 Reply Last reply
                              0
                              • M Mark81

                                @kshegunov said in "Undebuggable" segmentation fault:

                                Does this:

                                connect(_btn, &QToolButton::clicked, this, [this] () -> void  {
                                    QString filename = QFileDialog::getOpenFileName(nullptr, tr("Select signature image"), QDir::homePath(), tr("Portable Network Graphics (*.png)"));
                                    _line->setText("test");
                                });
                                

                                crash?

                                Yes, it crashes.

                                From the behaviour described it does seem you have dangling pointer/reference. Also don't do that:
                                without at least having a debug time check on it:

                                We've already checked the pointers and are not null.

                                kshegunovK Offline
                                kshegunovK Offline
                                kshegunov
                                Moderators
                                wrote on last edited by kshegunov
                                #15

                                @Mark81 said in "Undebuggable" segmentation fault:

                                Yes, it crashes.

                                Please break before the QLineEdit::setText and extract the backtrace for the thread.

                                We've already checked the pointers and are not null.

                                static_cast does not check if the types involved behind the pointer are compatible or convertible, so whether the pointer's null or not is meaningless if the typing is wrong.

                                Read and abide by the Qt Code of Conduct

                                1 Reply Last reply
                                2
                                • mrjjM Offline
                                  mrjjM Offline
                                  mrjj
                                  Lifetime Qt Champion
                                  wrote on last edited by mrjj
                                  #16

                                  Hi
                                  Shit i read
                                  SignatureEditor *widget = static_cast<SignatureEditor *>(editor);
                                  as qobject_cast
                                  so good catch, its most likely that.

                                  M 1 Reply Last reply
                                  0
                                  • mrjjM mrjj

                                    Hi
                                    Shit i read
                                    SignatureEditor *widget = static_cast<SignatureEditor *>(editor);
                                    as qobject_cast
                                    so good catch, its most likely that.

                                    M Offline
                                    M Offline
                                    Mark81
                                    wrote on last edited by
                                    #17

                                    @mrjj said in "Undebuggable" segmentation fault:

                                    as qobject_cast
                                    so good catch, its most likely that.

                                    I changed all static_cast to qobject_cast with no differences.

                                    @kshegunov
                                    here we are:

                                    0_1548257528392_Clipboard 1.jpg

                                    kshegunovK 1 Reply Last reply
                                    0
                                    • M Mark81

                                      @mrjj said in "Undebuggable" segmentation fault:

                                      as qobject_cast
                                      so good catch, its most likely that.

                                      I changed all static_cast to qobject_cast with no differences.

                                      @kshegunov
                                      here we are:

                                      0_1548257528392_Clipboard 1.jpg

                                      kshegunovK Offline
                                      kshegunovK Offline
                                      kshegunov
                                      Moderators
                                      wrote on last edited by kshegunov
                                      #18

                                      @Mark81 said in "Undebuggable" segmentation fault:

                                      here we are:

                                      Two problems with the screenshot:

                                      1. I can't see the whole stack (including the root), more important. Use right click and from the context menu extract it as text please.
                                      2. You didn't specify a context object for the lambda, which I requested in my previous post.

                                      Read and abide by the Qt Code of Conduct

                                      M 1 Reply Last reply
                                      2
                                      • kshegunovK kshegunov

                                        @Mark81 said in "Undebuggable" segmentation fault:

                                        here we are:

                                        Two problems with the screenshot:

                                        1. I can't see the whole stack (including the root), more important. Use right click and from the context menu extract it as text please.
                                        2. You didn't specify a context object for the lambda, which I requested in my previous post.
                                        M Offline
                                        M Offline
                                        Mark81
                                        wrote on last edited by
                                        #19

                                        @kshegunov said in "Undebuggable" segmentation fault:

                                        Two problems with the screenshot:

                                        1. I can't see the whole stack (including the root), more important. Use right click and from the context menu extract it as text please.
                                        2. You didn't specify a context object for the lambda, which I requested in my previous post.

                                        Sorry Sir, but we made a lot of trials. I wasn't sure about which code you want. By the way it's another syntax, very different! Why? Here the update screenshot and text:

                                        0_1548257990470_Clipboard 1.jpg

                                        Full backtrace attached as it's too big for the post. Here just the same info extracted as text:

                                        1  SignatureEditor::SignatureEditor(QWidget *)::{lambda()#1}::operator()() const                                                                                                              customdelegateoperators.h      37   0x492bb0   
                                        2  QtPrivate::FunctorCall<QtPrivate::IndexesList<>, QtPrivate::List<>, void, SignatureEditor::SignatureEditor(QWidget *)::{lambda()#1}>::call({lambda()#1}&, void * *)                        qobjectdefs_impl.h             128  0x48739a   
                                        3  QtPrivate::Functor<SignatureEditor::SignatureEditor(QWidget *)::{lambda()#1}, 0>::call<QtPrivate::List<>, void>({lambda()#1}&, void *, {lambda()#1}& *)                                    qobjectdefs_impl.h             238  0x48bf44   
                                        4  QtPrivate::QFunctorSlotObject<SignatureEditor::SignatureEditor(QWidget *)::{lambda()#1}, 0, QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase *, QObject *, void * *, bool *) qobjectdefs_impl.h             421  0x48ba8d   
                                        5  QtPrivate::QSlotObjectBase::call                                                                                                                                                           qobjectdefs_impl.h             376  0x281c173  
                                        6  QMetaObject::activate                                                                                                                                                                      qobject.cpp                    3754 0x281c173  
                                        7  QMetaObject::activate                                                                                                                                                                      qobject.cpp                    3633 0x281c575  
                                        8  QAbstractButton::clicked                                                                                                                                                                   moc_qabstractbutton.cpp        308  0x1b48b7ac 
                                        9  QAbstractButtonPrivate::emitClicked                                                                                                                                                        qabstractbutton.cpp            414  0x1b48b9d5 
                                        10 QAbstractButtonPrivate::click                                                                                                                                                              qabstractbutton.cpp            407  0x1b48d17a 
                                        11 QAbstractButton::mouseReleaseEvent                                                                                                                                                         qabstractbutton.cpp            1011 0x1b48d3aa 
                                        12 QToolButton::mouseReleaseEvent                                                                                                                                                             qtoolbutton.cpp                622  0x1b576fd1 
                                        13 QWidget::event                                                                                                                                                                             qwidget.cpp                    8901 0x1b3db0e0 
                                        14 QAbstractButton::event                                                                                                                                                                     qabstractbutton.cpp            968  0x1b48e7bc 
                                        15 QToolButton::event                                                                                                                                                                         qtoolbutton.cpp                985  0x1b57711e 
                                        16 QApplicationPrivate::notify_helper                                                                                                                                                         qapplication.cpp               3727 0x1b3985ca 
                                        17 QApplication::notify                                                                                                                                                                       qapplication.cpp               3203 0x1b3a0107 
                                        18 QCoreApplication::notifyInternal2                                                                                                                                                          qcoreapplication.cpp           1048 0x27f5119  
                                        19 QCoreApplication::sendSpontaneousEvent                                                                                                                                                     qcoreapplication.h             237  0x1b39f077 
                                        20 QApplicationPrivate::sendMouseEvent                                                                                                                                                        qapplication.cpp               2693 0x1b39f077 
                                        21 QWidgetWindow::handleMouseEvent                                                                                                                                                            qwidgetwindow.cpp              660  0x1b3f1af4 
                                        22 QWidgetWindow::event                                                                                                                                                                       qwidgetwindow.cpp              281  0x1b3f3bf9 
                                        23 QApplicationPrivate::notify_helper                                                                                                                                                         qapplication.cpp               3727 0x1b3985ca 
                                        24 QApplication::notify                                                                                                                                                                       qapplication.cpp               3099 0x1b39fb83 
                                        25 QCoreApplication::notifyInternal2                                                                                                                                                          qcoreapplication.cpp           1048 0x27f5119  
                                        26 QCoreApplication::sendSpontaneousEvent                                                                                                                                                     qcoreapplication.h             237  0x99cabfc  
                                        27 QGuiApplicationPrivate::processMouseEvent                                                                                                                                                  qguiapplication.cpp            2081 0x99cabfc  
                                        28 QGuiApplicationPrivate::processWindowSystemEvent                                                                                                                                           qguiapplication.cpp            1816 0x99cc4d7  
                                        29 QWindowSystemInterface::sendWindowSystemEvents                                                                                                                                             qwindowsysteminterface.cpp     1032 0x99adf99  
                                        30 QWindowsGuiEventDispatcher::sendPostedEvents                                                                                                                                               qwindowsguieventdispatcher.cpp 82   0x2883dae4 
                                        31 qt_internal_proc(HWND__ *, unsigned int, unsigned int, long) *16                                                                                                                           qeventdispatcher_win.cpp       237  0x284538d  
                                        32 gapfnScSendMessage                                                                                                                                                                                                             0x769f62fa 
                                        33 ??                                                                                                                                                                                                                             0x62047e   
                                        34 USER32!GetThreadDesktop                                                                                                                                                                                                        0x769f6d3a 
                                        35 QEventDispatcherWin32Private::sendTimerEvent                                                                                                                                               qeventdispatcher_win.cpp       456  0x2844dc9  
                                        36 ??                                                                                                                                                                                                                             0x62047e   
                                        37 USER32!CharPrevW                                                                                                                                                                                                               0x769f77c4 
                                        38 USER32!DispatchMessageW                                                                                                                                                                                                        0x769f788a 
                                        39 QEventDispatcherWin32::processEvents                                                                                                                                                       qeventdispatcher_win.cpp       629  0x2844ae8  
                                        40 QWindowsGuiEventDispatcher::processEvents                                                                                                                                                  qwindowsguieventdispatcher.cpp 74   0x2883dab7 
                                        41 QEventLoop::processEvents                                                                                                                                                                  qeventloop.cpp                 136  0x27f37c8  
                                        42 QEventLoop::exec                                                                                                                                                                           qeventloop.cpp                 214  0x27f3c20  
                                        43 QDialog::exec                                                                                                                                                                              qdialog.cpp                    546  0x1b5907de 
                                        44 MainWindow::on_actionImpostazioni_triggered                                                                                                                                                mainwindow.cpp                 1518 0x40e152   
                                        45 MainWindow::qt_static_metacall                                                                                                                                                             moc_mainwindow.cpp             298  0x43f973   
                                        46 MainWindow::qt_metacall                                                                                                                                                                    moc_mainwindow.cpp             368  0x43fcc2   
                                        47 QMetaObject::metacall                                                                                                                                                                      qmetaobject.cpp                301  0x27fe365  
                                        48 QMetaObject::activate                                                                                                                                                                      qobject.cpp                    3786 0x281c37f  
                                        49 QMetaObject::activate                                                                                                                                                                      qobject.cpp                    3633 0x281c575  
                                        50 QAction::triggered                                                                                                                                                                         moc_qaction.cpp                376  0x1b391618 
                                        51 QAction::activate                                                                                                                                                                          qaction.cpp                    1167 0x1b394579 
                                        52 QMenuPrivate::activateCausedStack                                                                                                                                                          qmenu.cpp                      1371 0x1b50d432 
                                        53 QMenuPrivate::activateAction                                                                                                                                                               qmenu.cpp                      1448 0x1b51507e 
                                        54 QMenu::mouseReleaseEvent                                                                                                                                                                   qmenu.cpp                      2942 0x1b515c07 
                                        55 QWidget::event                                                                                                                                                                             qwidget.cpp                    8901 0x1b3db0e0 
                                        56 QMenu::event                                                                                                                                                                               qmenu.cpp                      3064 0x1b5180de 
                                        57 QApplicationPrivate::notify_helper                                                                                                                                                         qapplication.cpp               3727 0x1b3985ca 
                                        58 QApplication::notify                                                                                                                                                                       qapplication.cpp               3203 0x1b3a0107 
                                        59 QCoreApplication::notifyInternal2                                                                                                                                                          qcoreapplication.cpp           1048 0x27f5119  
                                        60 QCoreApplication::sendSpontaneousEvent                                                                                                                                                     qcoreapplication.h             237  0x1b39f077 
                                        61 QApplicationPrivate::sendMouseEvent                                                                                                                                                        qapplication.cpp               2693 0x1b39f077 
                                        62 QWidgetWindow::handleMouseEvent                                                                                                                                                            qwidgetwindow.cpp              556  0x1b3f0ed3 
                                        63 QWidgetWindow::event                                                                                                                                                                       qwidgetwindow.cpp              281  0x1b3f3bf9 
                                        64 QApplicationPrivate::notify_helper                                                                                                                                                         qapplication.cpp               3727 0x1b3985ca 
                                        65 QApplication::notify                                                                                                                                                                       qapplication.cpp               3099 0x1b39fb83 
                                        66 QCoreApplication::notifyInternal2                                                                                                                                                          qcoreapplication.cpp           1048 0x27f5119  
                                        67 QCoreApplication::sendSpontaneousEvent                                                                                                                                                     qcoreapplication.h             237  0x99cabfc  
                                        68 QGuiApplicationPrivate::processMouseEvent                                                                                                                                                  qguiapplication.cpp            2081 0x99cabfc  
                                        69 QGuiApplicationPrivate::processWindowSystemEvent                                                                                                                                           qguiapplication.cpp            1816 0x99cc4d7  
                                        70 QWindowSystemInterface::sendWindowSystemEvents                                                                                                                                             qwindowsysteminterface.cpp     1032 0x99adf99  
                                        71 QWindowsGuiEventDispatcher::sendPostedEvents                                                                                                                                               qwindowsguieventdispatcher.cpp 82   0x2883dae4 
                                        72 qt_internal_proc(HWND__ *, unsigned int, unsigned int, long) *16                                                                                                                           qeventdispatcher_win.cpp       237  0x284538d  
                                        73 gapfnScSendMessage                                                                                                                                                                                                             0x769f62fa 
                                        74 ??                                                                                                                                                                                                                             0x62047e   
                                        75 USER32!GetThreadDesktop                                                                                                                                                                                                        0x769f6d3a 
                                        76 QEventDispatcherWin32Private::sendTimerEvent                                                                                                                                               qeventdispatcher_win.cpp       456  0x2844dc9  
                                        77 ??                                                                                                                                                                                                                             0x62047e   
                                        78 USER32!CharPrevW                                                                                                                                                                                                               0x769f77c4 
                                        79 USER32!DispatchMessageW                                                                                                                                                                                                        0x769f788a 
                                        80 QEventDispatcherWin32::processEvents                                                                                                                                                       qeventdispatcher_win.cpp       629  0x2844ae8  
                                        81 QWindowsGuiEventDispatcher::processEvents                                                                                                                                                  qwindowsguieventdispatcher.cpp 74   0x2883dab7 
                                        82 QEventLoop::processEvents                                                                                                                                                                  qeventloop.cpp                 136  0x27f37c8  
                                        83 QEventLoop::exec                                                                                                                                                                           qeventloop.cpp                 214  0x27f3c20  
                                        84 QCoreApplication::exec                                                                                                                                                                     qcoreapplication.cpp           1336 0x27fc30e  
                                        85 QGuiApplication::exec                                                                                                                                                                      qguiapplication.cpp            1761 0x99c1552  
                                        86 QApplication::exec                                                                                                                                                                         qapplication.cpp               2901 0x1b3984a9 
                                        87 qMain                                                                                                                                                                                      main.cpp                       37   0x401859   
                                        88 WinMain *16                                                                                                                                                                                qtmain_win.cpp                 104  0x447465   
                                        89 main                                                                                                                                                                                                                           0x49883d   [0_1548258146048_backtrace.txt](Uploading 100%) 
                                        
                                        kshegunovK 1 Reply Last reply
                                        0
                                        • mrjjM Offline
                                          mrjjM Offline
                                          mrjj
                                          Lifetime Qt Champion
                                          wrote on last edited by
                                          #20

                                          Hi
                                          Just to be 100% sure.
                                          You still have the checks at your casts, right ?

                                          SignatureEditor *widget = qobject_cast<SignatureEditor *>(editor); // Note qobject_cast !
                                          if (widget) {
                                            widget->setText(value);
                                            widget->activate();
                                          } else
                                            qDebug() << "invalid cast for editor";
                                          
                                          1 Reply Last reply
                                          1

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