Stack trace with Qt5.10.1 on an iPad. This was generated in the following way: (a) - prepare a breakpoint at the beginning of QQuickPointerTouchEvent::reset (b) - deactivate the breakpoint (c) - start the example (d) - tap once to bring up the overlay (e) - activate the breakpoint (f) - tap once (g) - when the debugger stops, continue program execution once (h) - inspect pointerEvent.m_event at #58 on the stack and note that it is != NULL (i) - at #0 advance single step past the line m_event = ev; (j) - inspect pointerEvent.m_event at #58 on the stack and note that it is == NULL (reused data structure, see QQuickWindowPrivate::queryPointerEventInstance) (k) - when you step out and the stack reaches #58 the crash happens pointerEvent->isPressed() #0 0x00000001018f1500 in QQuickPointerTouchEvent::reset(QEvent*) at /qt5101_ios/qtdeclarative/src/quick/items/qquickevents.cpp:1261 #1 0x000000010193e6b8 in QQuickWindowPrivate::deliverPointerEvent(QQuickPointerEvent*) at /qt5101_ios/qtdeclarative/src/quick/items/qquickwindow.cpp:2309 #2 0x000000010193b264 in QQuickWindowPrivate::handleTouchEvent(QTouchEvent*) at /qt5101_ios/qtdeclarative/src/quick/items/qquickwindow.cpp:2090 #3 0x000000010193ad8c in QQuickWindow::event(QEvent*) at /qt5101_ios/qtdeclarative/src/quick/items/qquickwindow.cpp:1546 #4 0x00000001013e559c in QApplicationPrivate::notify_helper(QObject*, QEvent*) at /qt5101_ios/qtbase/src/widgets/kernel/qapplication.cpp:3732 #5 0x00000001013e7220 in QApplication::notify(QObject*, QEvent*) at /qt5101_ios/qtbase/src/widgets/kernel/qapplication.cpp:3104 #6 0x000000010273b958 in QCoreApplication::notifyInternal2(QObject*, QEvent*) at /qt5101_ios/qtbase/src/corelib/kernel/qcoreapplication.cpp:1050 #7 0x00000001013e4490 in QCoreApplication::sendSpontaneousEvent(QObject*, QEvent*) at /qt5101_ios/qtbase/src/widgets/../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:237 #8 0x0000000101f30004 in QGuiApplicationPrivate::processTouchEvent(QWindowSystemInterfacePrivate::TouchEvent*) at /qt5101_ios/qtbase/src/gui/kernel/qguiapplication.cpp:2709 #9 0x0000000101f2da94 in QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) at /qt5101_ios/qtbase/src/gui/kernel/qguiapplication.cpp:1750 #10 0x0000000101f174a4 in bool QWindowSystemInterfacePrivate::handleWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) at /qt5101_ios/qtbase/src/gui/kernel/qwindowsysteminterface.cpp:101 #11 0x0000000101f19a9c in void QWindowSystemInterface::handleTouchEvent(QWindow*, unsigned long, QTouchDevice*, QList const&, QFlags) at /qt5101_ios/qtbase/src/gui/kernel/qwindowsysteminterface.cpp:696 #12 0x0000000101263b60 in ::-[QUIView sendTouchEventWithTimestamp:](ulong) at /qt5101_ios/qtbase/src/plugins/platforms/ios/quiview.mm:411 #13 0x0000000101264010 in ::-[QUIView touchesBegan:withEvent:](NSSet *, UIEvent *) at /qt5101_ios/qtbase/src/plugins/platforms/ios/quiview.mm:436 #14 0x000000018f25d830 in -[UIWindow _sendTouchesForEvent:] () #15 0x000000018f2528f8 in -[UIWindow sendEvent:] () #16 0x000000010124fde8 in ::-[QUIWindow sendEvent:](UIEvent *) at /qt5101_ios/qtbase/src/plugins/platforms/ios/qiosscreen.mm:207 #17 0x000000018f251238 in -[UIApplication sendEvent:] () #18 0x000000018fa32c0c in __dispatchPreprocessedEventFromEventQueue () #19 0x000000018fa351b8 in __handleEventQueueInternal () #20 0x000000018fa2e258 in __handleHIDEventFetcherDrain () #21 0x0000000185453404 in __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ () #22 0x0000000185452c2c in __CFRunLoopDoSources0 () #23 0x000000018545079c in __CFRunLoopRun () #24 0x0000000185370da8 in CFRunLoopRunSpecific () #25 0x000000010281d57c in QEventDispatcherCoreFoundation::processEvents(QFlags) at /qt5101_ios/qtbase/src/corelib/kernel/qeventdispatcher_cf.mm:293 #26 0x000000010124c1c8 in QIOSEventDispatcher::processEvents(QFlags) at /qt5101_ios/qtbase/src/plugins/platforms/ios/qioseventdispatcher.mm:470 #27 0x000000010273c020 in QCoreApplication::processEvents(QFlags) at /qt5101_ios/qtbase/src/corelib/kernel/qcoreapplication.cpp:1254 #28 0x00000001011e74e0 in CppJob::startJob() at /test/touch_build/CppJob.cpp:24 #29 0x00000001011e88c4 in CppJob::qt_static_metacall(QObject*, QMetaObject::Call, int, void**) at /test/touch_build/moc_CppJob.cpp:71 #30 0x00000001011e8a58 in CppJob::qt_metacall(QMetaObject::Call, int, void**) at /test/touch_build/moc_CppJob.cpp:104 #31 0x0000000102744e2c in QMetaObject::metacall(QObject*, QMetaObject::Call, int, void**) at /qt5101_ios/qtbase/src/corelib/kernel/qmetaobject.cpp:301 #32 0x0000000101e3ceac in QQmlObjectOrGadget::metacall(QMetaObject::Call, int, void**) const at /qt5101_ios/qtdeclarative/src/qml/qml/qqmlpropertycache.cpp:1732 #33 0x0000000101d53858 in CallMethod(QQmlObjectOrGadget const&, int, int, int, int*, QV4::ExecutionEngine*, QV4::CallData*, QMetaObject::Call) at /qt5101_ios/qtdeclarative/src/qml/jsruntime/qv4qobjectwrapper.cpp:1180 #34 0x0000000101d50290 in CallPrecise(QQmlObjectOrGadget const&, QQmlPropertyData const&, QV4::ExecutionEngine*, QV4::CallData*, QMetaObject::Call) at /qt5101_ios/qtdeclarative/src/qml/jsruntime/qv4qobjectwrapper.cpp:1428 #35 0x0000000101d4fce0 in QV4::QObjectMethod::callInternal(QV4::CallData*, QV4::Scope&) const at /qt5101_ios/qtdeclarative/src/qml/jsruntime/qv4qobjectwrapper.cpp:1970 #36 0x0000000101d4f838 in QV4::QObjectMethod::call(QV4::Managed const*, QV4::Scope&, QV4::CallData*) at /qt5101_ios/qtdeclarative/src/qml/jsruntime/qv4qobjectwrapper.cpp:1899 #37 0x0000000101dbade4 in QV4::Object::call(QV4::Scope&, QV4::CallData*) const at /qt5101_ios/qtdeclarative/src/qml/../../include/QtQml/5.10.1/QtQml/private/../../../../../src/qml/jsruntime/qv4object_p.h:445 #38 0x0000000101d79f08 in QV4::Runtime::method_callProperty(QV4::ExecutionEngine*, int, QV4::CallData*) at /qt5101_ios/qtdeclarative/src/qml/jsruntime/qv4runtime.cpp:1104 #39 0x0000000101d704f8 in QV4::Moth::VME::run(QV4::ExecutionEngine*, unsigned char const*) at /qt5101_ios/qtdeclarative/src/qml/jsruntime/qv4vme_moth.cpp:600 #40 0x0000000101d78708 in QV4::Moth::VME::exec(QV4::ExecutionEngine*, unsigned char const*) at /qt5101_ios/qtdeclarative/src/qml/jsruntime/qv4vme_moth.cpp:976 #41 0x0000000101c4c004 in QV4::ExecutionContext::simpleCall(QV4::Scope&, QV4::CallData*, QV4::Function*) at /qt5101_ios/qtdeclarative/src/qml/jsruntime/qv4context.cpp:302 #42 0x0000000101e692f4 in QQmlJavaScriptExpression::evaluate(QV4::CallData*, bool*, QV4::Scope&) at /qt5101_ios/qtdeclarative/src/qml/qml/qqmljavascriptexpression.cpp:223 #43 0x0000000101dc8e48 in QQmlBoundSignalExpression::evaluate(void**) at /qt5101_ios/qtdeclarative/src/qml/qml/qqmlboundsignal.cpp:223 #44 0x0000000101dc989c in QQmlBoundSignal_callback(QQmlNotifierEndpoint*, void**) at /qt5101_ios/qtdeclarative/src/qml/qml/qqmlboundsignal.cpp:355 #45 0x0000000101e44f68 in QQmlNotifier::emitNotify(QQmlNotifierEndpoint*, void**) at /qt5101_ios/qtdeclarative/src/qml/qml/qqmlnotifier.cpp:106 #46 0x0000000101d96794 in QQmlData::signalEmitted(QAbstractDeclarativeData*, QObject*, int, void**) at /qt5101_ios/qtdeclarative/src/qml/qml/qqmlengine.cpp:856 #47 0x000000010278468c in QMetaObject::activate(QObject*, int, int, void**) at /qt5101_ios/qtbase/src/corelib/kernel/qobject.cpp:3644 #48 0x00000001027845b0 in QMetaObject::activate(QObject*, QMetaObject const*, int, void**) at /qt5101_ios/qtbase/src/corelib/kernel/qobject.cpp:3629 #49 0x00000001019fc7e8 in QQuickMouseArea::released(QQuickMouseEvent*) at /qt5101_ios/qtdeclarative/src/quick/.moc/debug/moc_qquickmousearea_p.cpp:655 #50 0x00000001019fa26c in QQuickMouseArea::setPressed(Qt::MouseButton, bool, Qt::MouseEventSource) at /qt5101_ios/qtdeclarative/src/quick/items/qquickmousearea.cpp:1232 #51 0x00000001019faf3c in QQuickMouseArea::mouseReleaseEvent(QMouseEvent*) at /qt5101_ios/qtdeclarative/src/quick/items/qquickmousearea.cpp:805 #52 0x0000000101917974 in QQuickItem::event(QEvent*) at /qt5101_ios/qtdeclarative/src/quick/items/qquickitem.cpp:7897 #53 0x00000001013e559c in QApplicationPrivate::notify_helper(QObject*, QEvent*) at /qt5101_ios/qtbase/src/widgets/kernel/qapplication.cpp:3732 #54 0x00000001013e7220 in QApplication::notify(QObject*, QEvent*) at /qt5101_ios/qtbase/src/widgets/kernel/qapplication.cpp:3104 #55 0x000000010273b958 in QCoreApplication::notifyInternal2(QObject*, QEvent*) at /qt5101_ios/qtbase/src/corelib/kernel/qcoreapplication.cpp:1050 #56 0x000000010277cb1c in QCoreApplication::sendEvent(QObject*, QEvent*) at /qt5101_ios/qtbase/src/corelib/../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:234 #57 0x0000000101936e00 in QQuickWindowPrivate::deliverTouchAsMouse(QQuickItem*, QQuickPointerEvent*) at /qt5101_ios/qtdeclarative/src/quick/items/qquickwindow.cpp:738 #58 0x00000001019412d0 in QQuickWindowPrivate::deliverMatchingPointsToItem(QQuickItem*, QQuickPointerEvent*, bool) at /qt5101_ios/qtdeclarative/src/quick/items/qquickwindow.cpp:2580 #59 0x000000010194076c in QQuickWindowPrivate::deliverUpdatedTouchPoints(QQuickPointerTouchEvent*) at /qt5101_ios/qtdeclarative/src/quick/items/qquickwindow.cpp:2431 #60 0x000000010193fe9c in QQuickWindowPrivate::deliverTouchEvent(QQuickPointerTouchEvent*) at /qt5101_ios/qtdeclarative/src/quick/items/qquickwindow.cpp:2381 #61 0x000000010193e67c in QQuickWindowPrivate::deliverPointerEvent(QQuickPointerEvent*) at /qt5101_ios/qtdeclarative/src/quick/items/qquickwindow.cpp:2304 #62 0x000000010193b2b8 in QQuickWindowPrivate::handleTouchEvent(QTouchEvent*) at /qt5101_ios/qtdeclarative/src/quick/items/qquickwindow.cpp:2097 #63 0x000000010193ad8c in QQuickWindow::event(QEvent*) at /qt5101_ios/qtdeclarative/src/quick/items/qquickwindow.cpp:1546 #64 0x00000001013e559c in QApplicationPrivate::notify_helper(QObject*, QEvent*) at /qt5101_ios/qtbase/src/widgets/kernel/qapplication.cpp:3732 #65 0x00000001013e7220 in QApplication::notify(QObject*, QEvent*) at /qt5101_ios/qtbase/src/widgets/kernel/qapplication.cpp:3104 #66 0x000000010273b958 in QCoreApplication::notifyInternal2(QObject*, QEvent*) at /qt5101_ios/qtbase/src/corelib/kernel/qcoreapplication.cpp:1050 #67 0x00000001013e4490 in QCoreApplication::sendSpontaneousEvent(QObject*, QEvent*) at /qt5101_ios/qtbase/src/widgets/../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:237 #68 0x0000000101f30004 in QGuiApplicationPrivate::processTouchEvent(QWindowSystemInterfacePrivate::TouchEvent*) at /qt5101_ios/qtbase/src/gui/kernel/qguiapplication.cpp:2709 #69 0x0000000101f2da94 in QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) at /qt5101_ios/qtbase/src/gui/kernel/qguiapplication.cpp:1750 #70 0x0000000101f174a4 in bool QWindowSystemInterfacePrivate::handleWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) at /qt5101_ios/qtbase/src/gui/kernel/qwindowsysteminterface.cpp:101 #71 0x0000000101f19a9c in void QWindowSystemInterface::handleTouchEvent(QWindow*, unsigned long, QTouchDevice*, QList const&, QFlags) at /qt5101_ios/qtbase/src/gui/kernel/qwindowsysteminterface.cpp:696 #72 0x0000000101263b60 in ::-[QUIView sendTouchEventWithTimestamp:](ulong) at /qt5101_ios/qtbase/src/plugins/platforms/ios/quiview.mm:411 #73 0x00000001012641e8 in ::-[QUIView touchesEnded:withEvent:](NSSet *, UIEvent *) at /qt5101_ios/qtbase/src/plugins/platforms/ios/quiview.mm:448 #74 0x000000018f25da48 in -[UIWindow _sendTouchesForEvent:] () #75 0x000000018f2528f8 in -[UIWindow sendEvent:] () #76 0x000000010124fde8 in ::-[QUIWindow sendEvent:](UIEvent *) at /qt5101_ios/qtbase/src/plugins/platforms/ios/qiosscreen.mm:207 #77 0x000000018f251238 in -[UIApplication sendEvent:] () #78 0x000000018fa32c0c in __dispatchPreprocessedEventFromEventQueue () #79 0x000000018fa351b8 in __handleEventQueueInternal () #80 0x000000018fa2e258 in __handleHIDEventFetcherDrain () #81 0x0000000185453404 in __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ () #82 0x0000000185452c2c in __CFRunLoopDoSources0 () #83 0x000000018545079c in __CFRunLoopRun () #84 0x0000000185370da8 in CFRunLoopRunSpecific () #85 0x0000000187353020 in GSEventRunModal () #86 0x000000018f35178c in UIApplicationMain () #87 0x000000010124ad68 in ::qt_main_wrapper(int, char **) at /qt5101_ios/qtbase/src/plugins/platforms/ios/qioseventdispatcher.mm:232 #88 0x0000000184e01fc0 in start ()