using a model view on a "local" dialog causes a seg fault on close

[knobby67]

Hi All,
I open a "local" dialog from my mainwindow. Using

Add_Dialog madd_dialog;
 
    madd_dialog.setModal( true );
  madd_dialog.exec( );

Add_Dialog madd_dialog;

    madd_dialog.setModal( true );
  madd_dialog.exec( );

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everything works fine however when I go to close it I get a segmentation fault.
On commenting out everything except the constructor and de-constructor I've found that putting a model in my class produces the crash, so my class shows

private:
    Ui::Add_Dialog *ui;
 
//    QStandardItemModel model;

private:
    Ui::Add_Dialog *ui;

//    QStandardItemModel model;

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if I comment out model it works fine. I presume this is something to do with memory however am not knowledge of Qt is not enough to work out the issue.

Also related to this does the debugger have a backtrace like ddd so when I get a seg fault I can see what's causing it.


Thanks

[anda_skoa]

If you have a crash, then the stack trace of that crash is a valuable source of information on where it actually crashed.

Cheers,
_

P.S. no need to set modality, QDialog::exec() does that already

[knobby67]

Hi,
in Qt the stack shows "0 ??" from ddd "#0 0x00000000 in ?? ()" also in ddd backtrace normally shows all your function calls on the stack and I can set an execution point in the function then just step to the seg fault. However again backtrace just shows #0 0x0000000 in ??(). To be honest I've never seen this before, can anyone advise on this. The error occurs when I close a dialog with either the x button or calling this->close. I f I comment out the model from the class the error doesn't happen. Thanks

[wysota]

Maybe your code is built in release mode and thus no trace is available. Or maybe the stack is corrupted. The code should not crash just because you have a model as a member variable. Did you try rebuilding the project?

[knobby67]

Ok solved it, when I set up the dialog I use

madd_dialog.setModal( true );
    madd_dialog.exec( );

madd_dialog.setModal( true );
    madd_dialog.exec( );

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if I comment out setmodel it works. Don't know why as the tutorials I'm following always call this function. I only commented out because of anda's advise that it's not needed. However this seems to have go everything working. No idea why don't know enough about Qt.