SIGSEGV on QTabWidget::close

pauledd

Hi there,

I have a problem with proper closing my application without a SIGSEGV.

My window is made of a QTabWidget derived widget. The tabwidget
has four tabs and each has an ordinary qwidget in it.

class TabWidget : public QTabWidget
{
    Q_OBJECT
public:
    explicit TabWidget(QTabWidget *parent = Q_NULLPTR);

In one of the tabs qwidget I have a pushbutton that is connected to the tabwidgets
close() function.

connect(pbExit,&QPushButton::clicked,this,&TabWidget::close);

If I press the button (or click on the close window cross) the application quits with SIGSEGV:

The program has unexpectedly finished.
The process was ended forcefully.
/home/paul/store/c++/qt/build-qt-wetter-0.7-Desktop-Debug/qt-wetter-0 crashed.

If I debug the app it shows me the arrow where the error might be but the arrow is pointing at the Tabwidget class declaration itself, how could I debug further to find the problem?

SGaist

Hi,

Do you have any of your widgets on the stack and giving it a parent at the same time ?

VRonin

An other possibility is you having set the Qt::WA_DeleteOnClose attribute

pauledd

@VRonin I indeed set that ~~flag~~ attribute, just to see if that changes something but removing it does not solve it.

@SGaist no, the widgets I use for the tabs do not have a parent,

tab1 = new QWidget;
tab2 = new QWidget;
tab3 = new QWidget;
tab4 = new QWidget;
this->addTab(tab1,"Sensoren");
this->addTab(tab2,"Regenradar");
this->addTab(tab3, "Graph");
this->addTab(tab4, "System");

I will try to comment out parts of my code to condense the problem

pauledd

Okay I am getting closer, I found a line in the TabWidget constructor where I add a QHBoxLayout to a VBoxLayout (addLayout)... that causes the trouble. Trying to fix that :)

pauledd

That faulty QHBoxLayout has the problem that I added a QSpacerItem (addSpacerItem) to it two times... So I guess that is not the right way to use QSpacerItem? Can it only be added once to a QHBoxLayout?

EDIT:
Normally, you don't need to use this class directly. Qt's built-in layout managers provide the following functions for manipulating empty space in layouts

http://doc.qt.io/archives/qt-4.8/qspaceritem.html

pauledd

Solved my removing all addSpacerItems.

Solved SIGSEGV on QTabWidget::close