How do I delete the current QTreeWidget element correctly?

JonB

@Helg1980 said in How do I delete the current QTreeWidget element correctly?:

The only thing is that I couldn't start Q_ASSERT

I have no idea what you mean by this. What does "start" mean here? Q_ASSERT() is a macro, producing code during compilation.

and still it doesn't work for me.

In what way "work" or "doesn't work"?

BTW, your Build Settings are not relevant to this.

Helg1980

I mean, Q_ASSERT does not output a message in which line the crash occurred (in the case of Q_ASSERT(parentItem);)
Therefore, I concluded that this command does not work for me..

JonB

@Helg1980
Are you compiling for Debug or Release? Q_ASSERT() does nothing when compiled for Release, only for Debug.

Helg1980

Compilation I have in Debud mode, here is my compilation command:

cine_encoder.pro -spec linux-g++ CONFIG+=debug CONFIG+=force_debug_info CONFIG+=separate_debug_info && /usr/bin/make qmake_all

JonB

@Helg1980
That's not actually any kind of compiler command, just a make-type one, but never mind.

I really don't know. If the first line of your program is a Q_ASSERT(false) it should produce an error (when run) if compiled for Debug. And if you run your application from the debugger it should cause that to break on the offending line. If it's Q_ASSERT(true) it should do precisely nothing. You might test with these two.

P.S.
Where are you looking for the message to appear? If running from Qt Creator I think it would go to the Application Output pane.

Helg1980

@Helg1980 said in How do I delete the current QTreeWidget element correctly?:

Q_ASSERT(parentItem);

That's the point, that in Q_ASSERT(parentItem), the value 'parrentItem' is false, but Q_ASSERT does not give a message about this, but simply crashes the program;

Helg1980

Yes, I work in QtCreator.
Here is my Application Output:

18:31:38: Starting /run/media/helg/GOODRAM-SDB/QtCreatorProjects/CineEncoder/build-cine_encoder-Desktop-Debug/cine_encoder ...
18:31:53: The program has unexpectedly finished.
18:31:53: The process was ended forcefully.
18:31:53: /run/media/helg/GOODRAM-SDB/QtCreatorProjects/CineEncoder/build-cine_encoder-Desktop-Debug/cine_encoder crashed.

JonB

@Helg1980
OK, I don't know what you are doing, and what your program is doing.

It is time now to use the debugger to put a breakpoint in your program, and step through offending code. Besides, I don't know how you are getting a "crashed" without the debugger catching it and showing you a stack trace back to the faulting line. If you are not familiar with using the debugger it's time you were, as you can resolve these issues very simply by using it!

VRonin

@Helg1980
Start the debugger. If you have a debugger in the background it will tell you where the assertion occurred.

Q_ASSERT and Q_ASSUME are used to test implicit assumptions you make in your code.

Looking at the sources QTreeWidget it looked like item->parent() for a top level item would return the invisible root item. I tested this implicit assumption with Q_ASSERT and it turns out I was wrong (but at least we know why)

void SelectPreset::on_actionRemove_preset_clicked()  // Remove preset
{
    QTreeWidgetItem *item = ui_selectpreset->treeWidget->currentItem();
    if(!item)
        return;
    QTreeWidgetItem *parentItem = item->parent();
    QTreeWidgetItem *takenItem = nullptr;
    if(parentItem)
        takenItem  = parentItem->takeChild(parentItem->indexOfChild(item));
    else
        takenItem  = ui_selectpreset->treeWidget->takeTopLevelItem(ui_selectpreset->treeWidget->indexOfTopLevelItem(item));
    Q_ASSERT(takenItem==item);
    delete takenItem;
}

Helg1980

Finally, I finished the program and ran it through 'valgrind'. The result was disappointing:

valgrind --leak-check=full --leak-resolution=med /run/media/helg/GOODRAM-SDB/QtCreatorProjects/CineEncoder/build-cine_encoder-Desktop-Debug/cine_encoder
.
.
.
==2615== HEAP SUMMARY:
==2615==     in use at exit: 568,907 bytes in 7,703 blocks
==2615==   total heap usage: 880,287 allocs, 872,584 frees, 5,593,630,039 bytes allocated
==2615== 
==2615== 24 bytes in 1 blocks are definitely lost in loss record 89 of 557
==2615==    at 0x483A77F: malloc (vg_replace_malloc.c:307)
==2615==    by 0xDE61E5E: XextCreateExtension (in /usr/lib/libXext.so.6.4.0)
==2615==    by 0x1074014B: ???
==2615==    by 0x1073775C: ???
==2615==    by 0x10662091: ??? (in /usr/lib/qt/plugins/xcbglintegrations/libqxcb-glx-integration.so)
==2615==    by 0xA28C084: QXcbWindow::create() (in /usr/lib/libQt5XcbQpa.so.5.15.1)
==2615==    by 0xA27A746: QXcbIntegration::createPlatformWindow(QWindow*) const (in /usr/lib/libQt5XcbQpa.so.5.15.1)
==2615==    by 0x5842F26: QWindowPrivate::create(bool, unsigned long long) (in /usr/lib/libQt5Gui.so.5.15.1)
==2615==    by 0x51F78A7: QWidgetPrivate::create() (in /usr/lib/libQt5Widgets.so.5.15.1)
==2615==    by 0x51F7E20: QWidget::create(unsigned long long, bool, bool) (in /usr/lib/libQt5Widgets.so.5.15.1)
==2615==    by 0x520551B: QWidgetPrivate::setVisible(bool) (in /usr/lib/libQt5Widgets.so.5.15.1)
==2615==    by 0x117E3F: main (main.cpp:10)
==2615== 
==2615== 96 (64 direct, 32 indirect) bytes in 1 blocks are definitely lost in loss record 316 of 557
==2615==    at 0x483ADEF: operator new(unsigned long) (vg_replace_malloc.c:342)
==2615==    by 0x159CCB: SelectPreset::SelectPreset(QWidget*) (selectpreset.cpp:28)
==2615==    by 0x129258: MainWindow::on_actionPreset_clicked() (mainwindow.cpp:1279)
==2615==    by 0x1659B3: MainWindow::qt_static_metacall(QObject*, QMetaObject::Call, int, void**) (moc_mainwindow.cpp:156)
==2615==    by 0x165B5F: MainWindow::qt_metacall(QMetaObject::Call, int, void**) (moc_mainwindow.cpp:204)
==2615==    by 0x60B5D71: ??? (in /usr/lib/libQt5Core.so.5.15.1)
==2615==    by 0x52B5B22: QAbstractButton::clicked(bool) (in /usr/lib/libQt5Widgets.so.5.15.1)
==2615==    by 0x52B64AB: ??? (in /usr/lib/libQt5Widgets.so.5.15.1)
==2615==    by 0x52B7E52: ??? (in /usr/lib/libQt5Widgets.so.5.15.1)
==2615==    by 0x52B8032: QAbstractButton::mouseReleaseEvent(QMouseEvent*) (in /usr/lib/libQt5Widgets.so.5.15.1)
==2615==    by 0x5205B0D: QWidget::event(QEvent*) (in /usr/lib/libQt5Widgets.so.5.15.1)
==2615==    by 0x51C4751: QApplicationPrivate::notify_helper(QObject*, QEvent*) (in /usr/lib/libQt5Widgets.so.5.15.1)
==2615== 
==2615== 160 bytes in 1 blocks are possibly lost in loss record 369 of 557
==2615==    at 0x483A77F: malloc (vg_replace_malloc.c:307)
==2615==    by 0x60A8595: QObjectPrivate::addConnection(int, QObjectPrivate::Connection*) (in /usr/lib/libQt5Core.so.5.15.1)
==2615==    by 0x60AC9DE: QObjectPrivate::connectImpl(QObject const*, int, QObject const*, void**, QtPrivate::QSlotObjectBase*, Qt::ConnectionType, int const*, QMetaObject const*) (in /usr/lib/libQt5Core.so.5.15.1)
==2615==    by 0x60ACEB5: QObject::connectImpl(QObject const*, void**, QObject const*, void**, QtPrivate::QSlotObjectBase*, Qt::ConnectionType, int const*, QMetaObject const*) (in /usr/lib/libQt5Core.so.5.15.1)
==2615==    by 0xA3D1BBD: QDBusConnectionInterface::QDBusConnectionInterface(QDBusConnection const&, QObject*) (in /usr/lib/libQt5DBus.so.5.15.1)
==2615==    by 0xA3CEB3A: ??? (in /usr/lib/libQt5DBus.so.5.15.1)
==2615==    by 0xA3CFD13: ??? (in /usr/lib/libQt5DBus.so.5.15.1)
==2615==    by 0x60AB7E1: QObject::event(QEvent*) (in /usr/lib/libQt5Core.so.5.15.1)
==2615==    by 0x607ECAF: QCoreApplication::notifyInternal2(QObject*, QEvent*) (in /usr/lib/libQt5Core.so.5.15.1)
==2615==    by 0x60817D2: QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) (in /usr/lib/libQt5Core.so.5.15.1)
==2615==    by 0x60D8303: ??? (in /usr/lib/libQt5Core.so.5.15.1)
==2615==    by 0x6A2CBFB: g_main_context_dispatch (in /usr/lib/libglib-2.0.so.0.6600.0)
==2615== 
==2615== 302 (256 direct, 46 indirect) bytes in 1 blocks are definitely lost in loss record 409 of 557
==2615==    at 0x483A77F: malloc (vg_replace_malloc.c:307)
==2615==    by 0xA38F9E2: ??? (in /usr/lib/libfontconfig.so.1.12.0)
==2615==    by 0xA3902E4: ??? (in /usr/lib/libfontconfig.so.1.12.0)
==2615==    by 0xA391BEB: ??? (in /usr/lib/libfontconfig.so.1.12.0)
==2615==    by 0xA399E59: ??? (in /usr/lib/libfontconfig.so.1.12.0)
==2615==    by 0xA5309E7: ??? (in /usr/lib/libexpat.so.1.6.11)
==2615==    by 0xA52EDDC: ??? (in /usr/lib/libexpat.so.1.6.11)
==2615==    by 0xA532620: ??? (in /usr/lib/libexpat.so.1.6.11)
==2615==    by 0xA5348CB: XML_ParseBuffer (in /usr/lib/libexpat.so.1.6.11)
==2615==    by 0xA397024: ??? (in /usr/lib/libfontconfig.so.1.12.0)
==2615==    by 0xA397657: ??? (in /usr/lib/libfontconfig.so.1.12.0)
==2615==    by 0xA397713: ??? (in /usr/lib/libfontconfig.so.1.12.0)
==2615== 
==2615== LEAK SUMMARY:
==2615==    definitely lost: 344 bytes in 3 blocks
==2615==    indirectly lost: 78 bytes in 3 blocks
==2615==      possibly lost: 160 bytes in 1 blocks
==2615==    still reachable: 568,305 bytes in 7,694 blocks
==2615==                       of which reachable via heuristic:
==2615==                         newarray           : 4,264 bytes in 1 blocks
==2615==         suppressed: 20 bytes in 2 blocks
==2615== Reachable blocks (those to which a pointer was found) are not shown.
==2615== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==2615== 
==2615== Use --track-origins=yes to see where uninitialised values come from
==2615== For lists of detected and suppressed errors, rerun with: -s
==2615== ERROR SUMMARY: 107 errors from 107 contexts (suppressed: 0 from 0)

Christian Ehrlicher

@Helg1980 said in How do I delete the current QTreeWidget element correctly?:

The result was disappointing:

Why? There is only one leak which should interest you:

==2615== by 0x159CCB: SelectPreset::SelectPreset(QWidget*) (selectpreset.cpp:28)

The rest are no real 'leaks' and can be ignored.

Helg1980

Here is a part of the text where there may be an error:

SelectPreset::SelectPreset(QWidget *parent) :
    QDialog(parent),
    ui_selectpreset(new Ui::SelectPreset)
{
    ui_selectpreset->setupUi(this);
    ui_selectpreset->treeWidget->clear();
    int n =  _preset_table[0].size();
    int m = _preset_table.size();
    QString type;
    QColor color;
    color.setRgba(qRgb(120, 120, 150));
    QFont font;
    font.setBold(true);
    QTreeWidgetItem *item = new QTreeWidgetItem();    //    line 28  -  deleted this line
    for (int i = 0; i < n; i++) {
        type = _preset_table[23][i];
        if (type == "TopLewelItem") {
            QTreeWidgetItem *root = new QTreeWidgetItem();
            root->setText(0, _preset_table[0][i]);
            ui_selectpreset->treeWidget->addTopLevelItem(root);
            ui_selectpreset->treeWidget->setCurrentItem(root);
            root->setFlags(Qt::ItemIsEnabled | Qt::ItemIsSelectable | Qt::ItemIsEditable);
            root->setFont(0, font);
            root->setForeground(0, color);
        };
        if (type == "ChildItem") {
            item = ui_selectpreset->treeWidget->currentItem();   // replaced with: QTreeWidgetItem *item =  ....
            QTreeWidgetItem *child = new QTreeWidgetItem();
            for (int j = 0; j < 23; j++) {
                child->setText(j, _preset_table[j][i]);
            };
            child->setFlags(Qt::ItemIsEnabled | Qt::ItemIsSelectable | Qt::ItemIsEditable);
            item->addChild(child);
        };
    };
    item = ui_selectpreset->treeWidget->topLevelItem(pos_top)->child(pos_cld);   // replaced with: QTreeWidgetItem *item =  ....
    ui_selectpreset->treeWidget->setCurrentItem(item);
    std::cout << n << " x " << m << std::endl; // Table size
    ui_selectpreset->treeWidget->expandAll();
    for (int i=1; i<=24; i++) {
        ui_selectpreset->treeWidget->hideColumn(i);
    };
    QAction *addsection = new QAction(tr("Add section"), this);
    QAction *addpreset = new QAction(tr("Add new preset"), this);
    connect(addsection, &QAction::triggered, this, &SelectPreset::add_section);
    connect(addpreset, &QAction::triggered, this, &SelectPreset::add_preset);
    QMenu* menu = new QMenu(this);
    menu->addAction(addsection);
    menu->addAction(addpreset);
    menu->setStyleSheet("QMenu {background-color: rgb(5, 20, 25);} "
                        "QMenu::item {background-color: transparent;} "
                        "QMenu::item:selected {background-color: rgb(5, 40, 45);}");
    ui_selectpreset->actionAdd_preset->setMenu(menu);
}

JonB

@Helg1980 said in How do I delete the current QTreeWidget element correctly?:

QTreeWidgetItem *item = new QTreeWidgetItem(); // line 28

So, as the valgrind tells you, in all cases you do not use/overwrite this newed item without using it. Hence the leak.

Helg1980

This post is deleted!

JonB

@Helg1980
So I see. So now has that leak gone away? That's all you are looking to resolve.

Helg1980

It looks like the error has disappeared. I don't work very well with valgrind yet. So I understand that I only need to search for lines where there are links to my files.

==7099== HEAP SUMMARY:
==7099==     in use at exit: 571,790 bytes in 7,682 blocks
==7099==   total heap usage: 833,977 allocs, 826,295 frees, 5,575,110,174 bytes allocated
==7099== 
==7099== 24 bytes in 1 blocks are definitely lost in loss record 94 of 561
==7099==    at 0x483A77F: malloc (vg_replace_malloc.c:307)
==7099==    by 0xDE61E5E: XextCreateExtension (in /usr/lib/libXext.so.6.4.0)
==7099==    by 0x1074014B: ???
==7099==    by 0x1073775C: ???
==7099==    by 0x10662091: ??? (in /usr/lib/qt/plugins/xcbglintegrations/libqxcb-glx-integration.so)
==7099==    by 0xA28C084: QXcbWindow::create() (in /usr/lib/libQt5XcbQpa.so.5.15.1)
==7099==    by 0xA27A746: QXcbIntegration::createPlatformWindow(QWindow*) const (in /usr/lib/libQt5XcbQpa.so.5.15.1)
==7099==    by 0x5842F26: QWindowPrivate::create(bool, unsigned long long) (in /usr/lib/libQt5Gui.so.5.15.1)
==7099==    by 0x51F78A7: QWidgetPrivate::create() (in /usr/lib/libQt5Widgets.so.5.15.1)
==7099==    by 0x51F7E20: QWidget::create(unsigned long long, bool, bool) (in /usr/lib/libQt5Widgets.so.5.15.1)
==7099==    by 0x520551B: QWidgetPrivate::setVisible(bool) (in /usr/lib/libQt5Widgets.so.5.15.1)
==7099==    by 0x117E3F: main (main.cpp:10)
==7099== 
==7099== 160 bytes in 1 blocks are possibly lost in loss record 372 of 561
==7099==    at 0x483A77F: malloc (vg_replace_malloc.c:307)
==7099==    by 0x60A8595: QObjectPrivate::addConnection(int, QObjectPrivate::Connection*) (in /usr/lib/libQt5Core.so.5.15.1)
==7099==    by 0x60AC9DE: QObjectPrivate::connectImpl(QObject const*, int, QObject const*, void**, QtPrivate::QSlotObjectBase*, Qt::ConnectionType, int const*, QMetaObject const*) (in /usr/lib/libQt5Core.so.5.15.1)
==7099==    by 0x60ACEB5: QObject::connectImpl(QObject const*, void**, QObject const*, void**, QtPrivate::QSlotObjectBase*, Qt::ConnectionType, int const*, QMetaObject const*) (in /usr/lib/libQt5Core.so.5.15.1)
==7099==    by 0xA3D1BBD: QDBusConnectionInterface::QDBusConnectionInterface(QDBusConnection const&, QObject*) (in /usr/lib/libQt5DBus.so.5.15.1)
==7099==    by 0xA3CEB3A: ??? (in /usr/lib/libQt5DBus.so.5.15.1)
==7099==    by 0xA3CFD13: ??? (in /usr/lib/libQt5DBus.so.5.15.1)
==7099==    by 0x60AB7E1: QObject::event(QEvent*) (in /usr/lib/libQt5Core.so.5.15.1)
==7099==    by 0x607ECAF: QCoreApplication::notifyInternal2(QObject*, QEvent*) (in /usr/lib/libQt5Core.so.5.15.1)
==7099==    by 0x60817D2: QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) (in /usr/lib/libQt5Core.so.5.15.1)
==7099==    by 0x60D8303: ??? (in /usr/lib/libQt5Core.so.5.15.1)
==7099==    by 0x6A2CBFB: g_main_context_dispatch (in /usr/lib/libglib-2.0.so.0.6600.0)
==7099== 
==7099== 302 (256 direct, 46 indirect) bytes in 1 blocks are definitely lost in loss record 414 of 561
==7099==    at 0x483A77F: malloc (vg_replace_malloc.c:307)
==7099==    by 0xA38F9E2: ??? (in /usr/lib/libfontconfig.so.1.12.0)
==7099==    by 0xA3902E4: ??? (in /usr/lib/libfontconfig.so.1.12.0)
==7099==    by 0xA391BEB: ??? (in /usr/lib/libfontconfig.so.1.12.0)
==7099==    by 0xA399E59: ??? (in /usr/lib/libfontconfig.so.1.12.0)
==7099==    by 0xA5309E7: ??? (in /usr/lib/libexpat.so.1.6.11)
==7099==    by 0xA52EDDC: ??? (in /usr/lib/libexpat.so.1.6.11)
==7099==    by 0xA532620: ??? (in /usr/lib/libexpat.so.1.6.11)
==7099==    by 0xA5348CB: XML_ParseBuffer (in /usr/lib/libexpat.so.1.6.11)
==7099==    by 0xA397024: ??? (in /usr/lib/libfontconfig.so.1.12.0)
==7099==    by 0xA397657: ??? (in /usr/lib/libfontconfig.so.1.12.0)
==7099==    by 0xA397713: ??? (in /usr/lib/libfontconfig.so.1.12.0)
==7099== 
==7099== LEAK SUMMARY:
==7099==    definitely lost: 280 bytes in 2 blocks
==7099==    indirectly lost: 46 bytes in 2 blocks
==7099==      possibly lost: 160 bytes in 1 blocks
==7099==    still reachable: 571,284 bytes in 7,675 blocks
==7099==                       of which reachable via heuristic:
==7099==                         newarray           : 4,264 bytes in 1 blocks
==7099==         suppressed: 20 bytes in 2 blocks
==7099== Reachable blocks (those to which a pointer was found) are not shown.
==7099== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==7099== 
==7099== Use --track-origins=yes to see where uninitialised values come from
==7099== For lists of detected and suppressed errors, rerun with: -s
==7099== ERROR SUMMARY: 80 errors from 80 contexts (suppressed: 0 from 0)

JonB

@Helg1980
Are you running valgrind yourself with those command-line arguments? I run it from inside Qt Creator, from the menu item. I (Ubuntu 20.04) always get exactly 32 leaks, which with the default of the checkbox which says something about "don't report system ones" being checked, are always suppressed, so I don't see them. Any genuine ones from my own code are then the only ones reported.

Helg1980

This post is deleted!

Helg1980

Here's what valgrind QtCreator gives me. There are 35 errors in total.

160 bytes in 1 blocks are possibly lost in loss record 6,742 of 8,837
  in Ui_MainWindow::setupUi(QMainWindow*) in /run/media/helg/GOODRAM-SDB/QtCreatorProjects/CineEncoder/build-cine_encoder-Desktop-Debug/ui_mainwindow.h:556
  1: malloc in /build/valgrind/src/valgrind-3.16.1/coregrind/m_replacemalloc/vg_replace_malloc.c:307
  2: QObjectPrivate::addConnection(int, QObjectPrivate::Connection*) in /usr/lib/libQt5Core.so.5.15.1
  3: /usr/lib/libQt5Core.so.5.15.1
  4: QObject::connect(QObject const*, char const*, QObject const*, char const*, Qt::ConnectionType) in /usr/lib/libQt5Core.so.5.15.1
  5: /usr/lib/libQt5Widgets.so.5.15.1
  6: Ui_MainWindow::setupUi(QMainWindow*) in /run/media/helg/GOODRAM-SDB/QtCreatorProjects/CineEncoder/build-cine_encoder-Desktop-Debug/ui_mainwindow.h:556
  7: MainWindow::MainWindow(QWidget*) in /run/media/helg/GOODRAM-SDB/QtCreatorProjects/CineEncoder/cine-encoder-3.0/app/mainwindow.cpp:71
  8: main in /run/media/helg/GOODRAM-SDB/QtCreatorProjects/CineEncoder/cine-encoder-3.0/app/main.cpp:9
288 bytes in 1 blocks are possibly lost in loss record 7,317 of 8,837
  in Ui_MainWindow::setupUi(QMainWindow*) in /run/media/helg/GOODRAM-SDB/QtCreatorProjects/CineEncoder/build-cine_encoder-Desktop-Debug/ui_mainwindow.h:556
  1: malloc in /build/valgrind/src/valgrind-3.16.1/coregrind/m_replacemalloc/vg_replace_malloc.c:307
  2: QObjectPrivate::addConnection(int, QObjectPrivate::Connection*) in /usr/lib/libQt5Core.so.5.15.1
  3: /usr/lib/libQt5Core.so.5.15.1
  4: QObject::connect(QObject const*, char const*, QObject const*, char const*, Qt::ConnectionType) in /usr/lib/libQt5Core.so.5.15.1
  5: /usr/lib/libQt5Widgets.so.5.15.1
  6: Ui_MainWindow::setupUi(QMainWindow*) in /run/media/helg/GOODRAM-SDB/QtCreatorProjects/CineEncoder/build-cine_encoder-Desktop-Debug/ui_mainwindow.h:556
  7: MainWindow::MainWindow(QWidget*) in /run/media/helg/GOODRAM-SDB/QtCreatorProjects/CineEncoder/cine-encoder-3.0/app/mainwindow.cpp:71
  8: main in /run/media/helg/GOODRAM-SDB/QtCreatorProjects/CineEncoder/cine-encoder-3.0/app/main.cpp:9

VRonin

All looks good to me, only false positives left