Simple QML QtCharts is crashing with SegFault

[Tonelllo]

Hello everybody,
I don't know if I missing something trivial but what I did was:

• Opening a new qml desktop project in qt 6.10.1
• Add an example ChartView element in Main.qml
• Add the required elements in CMakeLists.txt

I am on linux.

It builds fine but when I try to run the app I get a:

The command "<path>/appSSTV" terminated abnormally.

And If I run the debugger this is the stack trace:

1  QWidgetTextControl::setCursorWidth                      qwidgettextcontrol.cpp    2493  0x7ffff77f9367 
2  QWidgetTextControlPrivate::init                         qwidgettextcontrol.cpp    406   0x7ffff77f962f 
3  QWidgetTextControl::QWidgetTextControl                  qwidgettextcontrol.cpp    868   0x7ffff77f962f 
4  QGraphicsTextItemPrivate::textControl                   qgraphicsitem.cpp         10318 0x7ffff7967ce4 
5  QGraphicsTextItem::document                             qgraphicsitem.cpp         9979  0x7ffff7968201 
6  ChartTitle::ChartTitle                                  charttitle.cpp            16    0x7ffff7d03425 
7  ChartPresenter::createTitleItem                         chartpresenter.cpp        244   0x7ffff7cf564f 
8  ChartPresenter::createTitleItem                         chartpresenter.cpp        241   0x7ffff7cf564f 
9  ChartPresenter::setTitleFont                            chartpresenter.cpp        341   0x7ffff7cf5a45 
10 QChart::setTitleFont                                    qchart.cpp                331   0x7ffff7d21071 
11 ChartThemeManager::decorateChart                        chartthememanager.cpp     82    0x7ffff7cfafe5 
12 ChartThemeManager::setTheme                             chartthememanager.cpp     61    0x7ffff7cfd4cf 
13 QChart::setTheme                                        qchart.cpp                360   0x7ffff7d21151 
14 QChartPrivate::init                                     qchart.cpp                876   0x7ffff7d22163 
15 QChart::QChart                                          qchart.cpp                226   0x7ffff7d22254 
16 DeclarativeChart::initChart                             declarativechart.cpp      470   0x7fffe95b3586 
17 DeclarativeChart::DeclarativeChart                      declarativechart.cpp      422   0x7fffe95b3aa9 
18 QQmlPrivate::QQmlElement<DeclarativeChart>::QQmlElement qqmlprivate.h             100   0x7fffe95c4cef 
19 QQmlPrivate::createInto<DeclarativeChart>               qqmlprivate.h             175   0x7fffe95c4cef 
20 QQmlType::create                                        qqmltype.cpp              510   0x7ffff5c06876 
21 QQmlType::create                                        qqmltype.cpp              504   0x7ffff5c06876 
22 QQmlType::createWithQQmlData                            qqmltype.cpp              525   0x7ffff5c06922 
23 QQmlObjectCreator::createInstance                       qqmlobjectcreator.cpp     1342  0x7ffff5bb3a12 
24 QQmlObjectCreator::setPropertyBinding                   qendian.h                 258   0x7ffff5bb55e5 
25 QQmlObjectCreator::setupBindings                        qqmlobjectcreator.cpp     825   0x7ffff5bb7bb6 
26 QQmlObjectCreator::populateInstance                     qqmlobjectcreator.cpp     1831  0x7ffff5bb996a 
27 QQmlObjectCreator::createInstance                       qqmlobjectcreator.cpp     1492  0x7ffff5bb2fef 
28 QQmlObjectCreator::create                               qqmlobjectcreator.cpp     199   0x7ffff5bbb7e1 
29 QQmlComponentPrivate::beginCreate                       qqmlcomponent.cpp         1137  0x7ffff5b32a6d 
30 QQmlComponent::beginCreate                              qqmlcomponent.cpp         1054  0x7ffff5b3310d 
31 QQmlComponentPrivate::createWithProperties              qqmlcomponent.cpp         977   0x7ffff5b342b2 
32 QQmlComponent::create                                   qqmlcomponent.cpp         938   0x7ffff5b3463d 
33 QQmlApplicationEnginePrivate::finishLoad                qqmlapplicationengine.cpp 158   0x7ffff5b0cc93 
34 QQmlApplicationEnginePrivate::ensureLoadingFinishes     qqmlapplicationengine.cpp 185   0x7ffff5b0ce9c 
35 QQmlApplicationEnginePrivate::startLoad                 qqmlapplicationengine.cpp 144   0x7ffff5b0d236 
36 main                                                    main.cpp                  15    0x55555555784a

That at the end points in setCursorWidth to:

void QWidgetTextControl::setCursorWidth(int width)
{
    Q_D(QWidgetTextControl);
    if (width == -1)
        width = QApplication::style()->pixelMetric(QStyle::PM_TextCursorWidth, nullptr, qobject_cast<QWidget *>(parent()));
                           ^^^^^^ QApplication::style() is nullptr
    d->doc->documentLayout()->setProperty("cursorWidth", width);
    d->repaintCursor();
}

These are the relevant files:
CMakeLists.txt:

cmake_minimum_required(VERSION 3.16)

project(SSTV VERSION 0.1 LANGUAGES CXX)

set(CMAKE_CXX_STANDARD_REQUIRED ON)

find_package(Qt6 REQUIRED COMPONENTS Charts Core Gui Qml Quick Graphs)
find_package(Qt6 REQUIRED COMPONENTS QuickControls2)

qt_standard_project_setup(REQUIRES 6.8)

qt_add_executable(appSSTV
    main.cpp
)

qt_add_qml_module(appSSTV
    URI SSTV
    QML_FILES
        Main.qml
)

# Qt for iOS sets MACOSX_BUNDLE_GUI_IDENTIFIER automatically since Qt 6.1.
# If you are developing for iOS or macOS you should consider setting an
# explicit, fixed bundle identifier manually though.
set_target_properties(appSSTV PROPERTIES
#    MACOSX_BUNDLE_GUI_IDENTIFIER com.example.appSSTV
    MACOSX_BUNDLE_BUNDLE_VERSION ${PROJECT_VERSION}
    MACOSX_BUNDLE_SHORT_VERSION_STRING ${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}
    MACOSX_BUNDLE TRUE
    WIN32_EXECUTABLE TRUE
)

target_link_libraries(appSSTV
    PRIVATE
    Qt::Charts
    Qt::Core
    Qt::Gui
    Qt::Qml
    Qt::Quick
    Qt6::QuickControls2
)

include(GNUInstallDirs)
install(TARGETS appSSTV
    BUNDLE DESTINATION .
    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
    RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
)

main.cpp not changed from the template:

#include <QGuiApplication>
#include <QQmlApplicationEngine>

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

    QQmlApplicationEngine engine;
    QObject::connect(
        &engine,
        &QQmlApplicationEngine::objectCreationFailed,
        &app,
        []() { QCoreApplication::exit(-1); },
        Qt::QueuedConnection);
    engine.loadFromModule("SSTV", "Main");

    return app.exec();
}

And main.qml:

import QtQuick
import QtQuick.Controls.Universal
import QtCharts

ApplicationWindow {
    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")

    Universal.theme: Universal.Dark
    Universal.accent: Universal.Crimson

    ChartView {
        title: "Line Chart"
        anchors.fill: parent
        antialiasing: true

        LineSeries {
            name: "Line"
            XYPoint { x: 0; y: 0 }
            XYPoint { x: 1.1; y: 2.1 }
            XYPoint { x: 1.9; y: 3.3 }
            XYPoint { x: 2.1; y: 2.1 }
            XYPoint { x: 2.9; y: 4.9 }
            XYPoint { x: 3.4; y: 3.0 }
            XYPoint { x: 4.1; y: 3.3 }
        }
    }
}

[Christian Ehrlicher]

QChart needs a QApplication as it derives from QGraphicsWidget which is a QWidget: https://doc.qt.io/qt-6/qchart-qtcharts.html

[Tonelllo]

@Christian-Ehrlicher
Tank you very much for your reply. This was indeed the problem