QFileSystemModel QML type crashes upon MultiSelection when mouse pointer moves beyond row 0

Diracsbracket

Hi
The following miminal example, basically a stripped-down version of
https://doc.qt.io/qt-5.11/qtquickcontrols-filesystembrowser-example.html
crashes when in a multi selection mode (e.g. SelectionMode.MultiSelection or SelectionMode.ExtendedSelection), the selection mouse pointer is dragged beyond row 0.

filesystembrowser.pro:

TEMPLATE = app
TARGET = filesystembrowser
QT += qml quick widgets

SOURCES += main.cpp

RESOURCES += qml.qrc
CONFIG += c++11

INSTALLS += target

main.cpp:

#include <QApplication>
#include <QQmlApplicationEngine>
#include <QtQml>
#include <QFileSystemModel>

class DisplayFileSystemModel : public QFileSystemModel {
    Q_OBJECT
public:
    explicit DisplayFileSystemModel(QObject *parent = nullptr)
        : QFileSystemModel(parent) {}

    QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override
    {
        return QFileSystemModel::data(index, role);
    }

    QHash<int,QByteArray> roleNames() const override
    {
         QHash<int, QByteArray> result = QFileSystemModel::roleNames();
         return result;
    }
};

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QQmlApplicationEngine engine;
    qmlRegisterUncreatableType<DisplayFileSystemModel>("io.qt.examples.quick.controls.filesystembrowser", 1, 0,
                                                       "FileSystemModel", "Cannot create a FileSystemModel instance.");

    QFileSystemModel *fsm = new DisplayFileSystemModel(&engine);

    fsm->setRootPath(QDir::homePath());
    fsm->setResolveSymlinks(true);
    engine.rootContext()->setContextProperty("fileSystemModel", fsm);
    engine.rootContext()->setContextProperty("rootPathIndex", fsm->index(fsm->rootPath()));
    engine.load(QUrl(QStringLiteral("qrc:///main.qml")));

    if (engine.rootObjects().isEmpty())
        return -1;

    return app.exec();
}

#include "main.moc"

main.qml:

import QtQuick 2.11
import QtQuick.Controls 1.4
import QtQml.Models 2.11

ApplicationWindow {
    visible: true
    width: 640
    height: 480
    title: qsTr("File System")

    ItemSelectionModel {
        id: selectionModel
        model: fileSystemModel
    }

    TreeView {
        id: view
        anchors.fill: parent
        model: fileSystemModel
        rootIndex: rootPathIndex

        selection: selectionModel
        selectionMode: SelectionMode.MultiSelection //SelectionMode.ExtendedSelection

        TableViewColumn {
            title: "Name"
            role: "fileName"
            resizable: true
        }
    }
}

The debugger halts at:

QPersistentModelIndex::operator const QModelIndex&() const
{
    static const QModelIndex invalid;
    if (d)                                                         <-- DEBUGGER HALTS HERE
        return d->index;
    return invalid;
}

The stack backtrace is:

1  QPersistentModelIndex::operator QModelIndex const& qabstractitemmodel.cpp           272  0x7ffff585d2e0 
2  QQuickTreeModelAdaptor1::selectionForRowRange      qquicktreemodeladaptor.cpp       292  0x7fffd8cdd9b8 
3  QQuickTreeModelAdaptor1::qt_static_metacall        moc_qquicktreemodeladaptor_p.cpp 212  0x7fffd8cf4ec8 
4  QQuickTreeModelAdaptor1::qt_metacall               moc_qquicktreemodeladaptor_p.cpp 337  0x7fffd8cf56e8 
5  QQmlObjectOrGadget::metacall                       qqmlpropertycache.cpp            1733 0x7ffff637d389 
6  CallMethod                                         qv4qobjectwrapper.cpp            1175 0x7ffff62ead8d 
7  CallPrecise                                        qv4qobjectwrapper.cpp            1437 0x7ffff62ec2dd 
8  QV4::QObjectMethod::callInternal                   qv4qobjectwrapper.cpp            1975 0x7ffff62ed066 
9  QV4::FunctionObject::call                          qv4functionobject_p.h            163  0x7ffff6307fb0 
10 QV4::Runtime::method_callProperty                  qv4runtime.cpp                   1062 0x7ffff6307fb0 
11 QV4::Moth::VME::exec                               qv4vme_moth.cpp                  800  0x7ffff62fad5a 
12 QV4::FunctionObject::call                          qv4functionobject_p.h            163  0x7ffff6307fb0 
13 QV4::Runtime::method_callProperty                  qv4runtime.cpp                   1062 0x7ffff6307fb0 
14 QV4::Moth::VME::exec                               qv4vme_moth.cpp                  800  0x7ffff62fad5a 
15 QV4::Moth::VME::exec                               qv4vme_moth_p.h                  72   0x7ffff63ac1d6 
16 QV4::Function::call                                qv4function_p.h                  72   0x7ffff63ac1d6 
17 QQmlJavaScriptExpression::evaluate                 qqmljavascriptexpression.cpp     217  0x7ffff63ac1d6 
18 QQmlBoundSignalExpression::evaluate                qqmlboundsignal.cpp              237  0x7ffff6342269 
19 QQmlBoundSignal_callback                           qqmlboundsignal.cpp              370  0x7ffff6343753 
20 QQmlNotifier::emitNotify                           qqmlnotifier.cpp                 106  0x7ffff63875f4 
21 QQmlData::signalEmitted                            qqmlengine.cpp                   861  0x7ffff6326194 
22 QMetaObject::activate                              qobject.cpp                      3649 0x7ffff58d6e32 
23 QMetaObject::activate                              qobject.cpp                      3633 0x7ffff58d70d7 
24 QQmlTimer::triggered                               moc_qqmltimer_p.cpp              261  0x7ffff6413750 
25 QQmlTimer::ticked                                  qqmltimer.cpp                    323  0x7ffff6413b7f 
26 QQmlTimer::event                                   qqmltimer.cpp                    335  0x7ffff6413e4c 
27 QApplicationPrivate::notify_helper                 qapplication.cpp                 3727 0x7ffff7083eac 
28 QApplication::notify                               qapplication.cpp                 3486 0x7ffff708afe0 
29 QCoreApplication::notifyInternal2                  qcoreapplication.cpp             1048 0x7ffff58ab918 
30 QCoreApplication::sendEvent                        qcoreapplication.h               234  0x7ffff58ae32b 
31 QCoreApplicationPrivate::sendPostedEvents          qcoreapplication.cpp             1745 0x7ffff58ae32b 
32 QCoreApplication::sendPostedEvents                 qcoreapplication.cpp             1599 0x7ffff58ae818 
33 postEventSourceDispatch                            qeventdispatcher_glib.cpp        276  0x7ffff59001c3 
34 g_main_context_dispatch                                                                  0x7ffff18547f7 
35 ??                                                                                       0x7ffff1854a60 
36 g_main_context_iteration                                                                 0x7ffff1854b0c 
37 QEventDispatcherGlib::processEvents                qeventdispatcher_glib.cpp        423  0x7ffff58ff81f 
38 QPAEventDispatcherGlib::processEvents              qeventdispatcher_glib.cpp        69   0x7fffee875831 
39 QEventLoop::exec                                   qeventloop.cpp                   214  0x7ffff58aa27a 
40 QCoreApplication::exec                             qcoreapplication.cpp             1336 0x7ffff58b2c80 
41 main                                               main.cpp                         43   0x5555555572f5

I tested this with Qt 5.11.1 and 5.11.2 on a Debian 9.5 VM and Qt 5.11.0 on Windows 10 x64. They all crash.

Any ideas?
Thanks!

Edit: this is not specific to QFileSystemModel it seems. I have another QAbstractItemModel-derived model that also crashes in a similar fashion.

SGaist

Hi,

It's a bug. You should check the bug report system to see if it's something known. If not, please consider opening a new report providing your complete example.

Diracsbracket

@SGaist
Thanks. I reported it.
https://bugreports.qt.io/browse/QTBUG-71789