LeveyJenningsSimple-example segfaults

[krf]

Steps to reproduce:

Run valgrind ./bin/LeveyJenningsSimple-example

Result:

==220254== Invalid read of size 8
==220254==    at 0x4959143: KDChart::Chart::Private::paintAll(QPainter*) (src/kdab/KDChart/src/KDChart/KDChartChart.cpp:1093)
==220254==    by 0x495A5C9: KDChart::Chart::paintEvent(QPaintEvent*) (src/kdab/KDChart/src/KDChart/KDChartChart.cpp:1410)
==220254==    by 0x4CFD5DD: QWidget::event(QEvent*) (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.15.2)
==220254==    by 0x495D0AB: KDChart::Chart::event(QEvent*) (src/kdab/KDChart/src/KDChart/KDChartChart.cpp:1768)
==220254==    by 0x4CBA782: QApplicationPrivate::notify_helper(QObject*, QEvent*) (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.15.2)
==220254==    by 0x5C027B9: QCoreApplication::notifyInternal2(QObject*, QEvent*) (in /usr/lib/x86_64-linux-gnu/libQt5Core.so.5.15.2)
==220254==    by 0x4CF5539: QWidgetPrivate::sendPaintEvent(QRegion const&) (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.15.2)
==220254==    by 0x4CF5D61: QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, QFlags<QWidgetPrivate::DrawWidgetFlag>, QPainter*, QWidgetRepaintManager*) (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.15.2)
==220254==    by 0x4CF71C2: QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList<QObject*> const&, int, QRegion const&, QPoint const&, QFlags<QWidgetPrivate::DrawWidgetFlag>, QPainter*, QWidgetRepaintManager*) (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.15.2)
==220254==    by 0x4CF6FE1: QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList<QObject*> const&, int, QRegion const&, QPoint const&, QFlags<QWidgetPrivate::DrawWidgetFlag>, QPainter*, QWidgetRepaintManager*) (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.15.2)
==220254==    by 0x4CF6FE1: QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList<QObject*> const&, int, QRegion const&, QPoint const&, QFlags<QWidgetPrivate::DrawWidgetFlag>, QPainter*, QWidgetRepaintManager*) (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.15.2)
==220254==    by 0x4CF5A7B: QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, QFlags<QWidgetPrivate::DrawWidgetFlag>, QPainter*, QWidgetRepaintManager*) (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.15.2)
==220254==  Address 0x17fad360 is 0 bytes inside a block of size 96 free'd
==220254==    at 0x484584F: operator delete(void*) (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==220254==    by 0x4955EB9: KDChart::Chart::Private::slotLayoutPlanes() (src/kdab/KDChart/src/KDChart/KDChartChart.cpp:652)
==220254==    by 0x5C3A5FF: ??? (in /usr/lib/x86_64-linux-gnu/libQt5Core.so.5.15.2)
==220254==    by 0x49CE3A2: KDChart::LeveyJenningsAxis::paintAsAbscissa(KDChart::PaintContext*) (src/kdab/KDChart/src/KDChart/Cartesian/KDChartLeveyJenningsAxis.cpp:210)
==220254==    by 0x49A3AB2: KDChart::CartesianAxis::paint(QPainter*) (src/kdab/KDChart/src/KDChart/Cartesian/KDChartCartesianAxis.cpp:553)
==220254==    by 0x4970D2C: KDChart::AbstractArea::paintAll(QPainter&) (src/kdab/KDChart/src/KDChart/KDChartAbstractArea.cpp:130)
==220254==    by 0x495914E: KDChart::Chart::Private::paintAll(QPainter*) (src/kdab/KDChart/src/KDChart/KDChartChart.cpp:1093)
==220254==    by 0x495A5C9: KDChart::Chart::paintEvent(QPaintEvent*) (src/kdab/KDChart/src/KDChart/KDChartChart.cpp:1410)
==220254==    by 0x4CFD5DD: QWidget::event(QEvent*) (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.15.2)
==220254==    by 0x495D0AB: KDChart::Chart::event(QEvent*) (src/kdab/KDChart/src/KDChart/KDChartChart.cpp:1768)
==220254==    by 0x4CBA782: QApplicationPrivate::notify_helper(QObject*, QEvent*) (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.15.2)
==220254==    by 0x5C027B9: QCoreApplication::notifyInternal2(QObject*, QEvent*) (in /usr/lib/x86_64-linux-gnu/libQt5Core.so.5.15.2)
==220254==  Block was alloc'd at
==220254==    at 0x4842FB3: operator new(unsigned long) (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==220254==    by 0x49568CF: KDChart::Chart::Private::slotLayoutPlanes() (src/kdab/KDChart/src/KDChart/KDChartChart.cpp:951)
==220254==    by 0x5C3A5FF: ??? (in /usr/lib/x86_64-linux-gnu/libQt5Core.so.5.15.2)
==220254==    by 0x4958BC2: KDChart::Chart::Private::updateDirtyLayouts() (src/kdab/KDChart/src/KDChart/KDChartChart.cpp:1057)
==220254==    by 0x4959067: KDChart::Chart::Private::paintAll(QPainter*) (src/kdab/KDChart/src/KDChart/KDChartChart.cpp:1079)
==220254==    by 0x495A5C9: KDChart::Chart::paintEvent(QPaintEvent*) (src/kdab/KDChart/src/KDChart/KDChartChart.cpp:1410)
==220254==    by 0x4CFD5DD: QWidget::event(QEvent*) (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.15.2)
==220254==    by 0x495D0AB: KDChart::Chart::event(QEvent*) (src/kdab/KDChart/src/KDChart/KDChartChart.cpp:1768)
==220254==    by 0x4CBA782: QApplicationPrivate::notify_helper(QObject*, QEvent*) (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.15.2)
==220254==    by 0x5C027B9: QCoreApplication::notifyInternal2(QObject*, QEvent*) (in /usr/lib/x86_64-linux-gnu/libQt5Core.so.5.15.2)
==220254==    by 0x4CF5539: QWidgetPrivate::sendPaintEvent(QRegion const&) (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.15.2)
==220254==    by 0x4CF5D61: QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, QFlags<QWidgetPrivate::DrawWidgetFlag>, QPainter*, QWidgetRepaintManager*) (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.15.2)

Problem:
The member planeLayoutItems gets modified during iteration over it inside the Chart::Private::paintAll method.

This must be a longer term issue. It doesn't seem to be related to the recent Qt 6 port of KDChart (checked by reverting the code base to the previous state).

[krf]

@ivan-cukic Could you have a look maybe? You have the best overview of KDChart internals right now.