[Development] QtQuick: new Drag&Drop crashes

[Mitch Curtis]

https://bugreports.qt-project.org/browse/QTBUG-35702

On 01/21/2014 09:54 AM, Fabien Castan wrote:
> Hi,
> I get some troubles in building Qt by myself... (errors with pch files).
> Could someone with a debug version of qmlscene try to open the external
> drag&drop example ?
>
> qmlscene
> qt5/qtdeclarative/examples/quick/externaldraganddrop/externaldraganddrop.qml
>
> It's reproductible. Just try to drag the qml item inside the qml
> application or to an external application. It crashes in both cases.
>
>
>
> 2014/1/21 Thiago Macieira <thiago.macieira at intel.com
> <mailto:thiago.macieira at intel.com>>
>
>     Please run valgrind with debug-mode Qt too. Valgrinding release-mode
>     Qt is not
>     helpful. We need to know what these question marks mean:
>
>     On terça-feira, 21 de janeiro de 2014 01:36:36, Fabien Castan wrote:
>     > ==22064== Invalid read of size 8
>     > ==22064==    at 0x6306D30: QDrag::mimeData() const (in
>     > /opt/Qt5.2.0/5.2.0/gcc_64/lib/libQt5Gui.so.5.2.0)
>     > ==22064==    by 0xD4BA356: ??? (in
>     > /opt/Qt5.2.0/5.2.0/gcc_64/plugins/platforms/libqxcb.so)
>     > ==22064==    by 0xD4B1E67: ??? (in
>     > /opt/Qt5.2.0/5.2.0/gcc_64/plugins/platforms/libqxcb.so)
>     > ==22064==    by 0xD4B2A5A: ??? (in
>     > /opt/Qt5.2.0/5.2.0/gcc_64/plugins/platforms/libqxcb.so)
>     > ==22064==    by 0x6B4D90D: QObject::event(QEvent*) (in
>     > /opt/Qt5.2.0/5.2.0/gcc_64/lib/libQt5Core.so.5.2.0)
>     > ==22064==    by 0x5B16F33: QApplicationPrivate::notify_helper(QObject*,
>     > QEvent*) (in /opt/Qt5.2.0/5.2.0/gcc_64/lib/libQt5Widgets.so.5.2.0)
>     > ==22064==    by 0x5B1A50D: QApplication::notify(QObject*, QEvent*) (in
>     > /opt/Qt5.2.0/5.2.0/gcc_64/lib/libQt5Widgets.so.5.2.0)
>     > ==22064==    by 0x6B23553: QCoreApplication::notifyInternal(QObject*,
>     > QEvent*) (in /opt/Qt5.2.0/5.2.0/gcc_64/lib/libQt5Core.so.5.2.0)
>     > ==22064==    by 0x6B25E08:
>     > QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) (in
>     > /opt/Qt5.2.0/5.2.0/gcc_64/lib/libQt5Core.so.5.2.0)
>     > ==22064==    by 0x6B73B82: ??? (in
>     > /opt/Qt5.2.0/5.2.0/gcc_64/lib/libQt5Core.so.5.2.0)
>     > ==22064==    by 0x83A43B5: g_main_context_dispatch (in
>     > /lib/x86_64-linux-gnu/libglib-2.0.so.0.3800.1)
>     > ==22064==    by 0x83A4707: ??? (in
>     > /lib/x86_64-linux-gnu/libglib-2.0.so.0.3800.1)
>     > ==22064==  Address 0x13b07288 is 8 bytes inside a block of size 16 free'd
>     > ==22064==    at 0x4C2BADC: operator delete(void*) (in
>     > /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
>     > ==22064==    by 0x5074AB9: ??? (in
>     > /opt/Qt5.2.0/5.2.0/gcc_64/lib/libQt5Quick.so.5.2.0)
>
>     These here. What deleted the pointer?
>
>     > ==22064==    by 0x5074F02: ??? (in
>     > /opt/Qt5.2.0/5.2.0/gcc_64/lib/libQt5Quick.so.5.2.0)
>     > ==22064==    by 0x50EAFEF: ??? (in
>     > /opt/Qt5.2.0/5.2.0/gcc_64/lib/libQt5Quick.so.5.2.0)
>     > ==22064==    by 0x55DD022: QQmlPropertyPrivate::write(QObject*,
>     > QQmlPropertyData const&, QVariant const&, QQmlContextData*,
>     > QFlags<QQmlPropertyPrivate::WriteFlag>) (in
>     > /opt/Qt5.2.0/5.2.0/gcc_64/lib/libQt5Qml.so.5.2.0)
>     > ==22064==    by 0x55DEB32:
>     > QQmlPropertyPrivate::writeValueProperty(QObject*, QQmlPropertyData const&,
>     > QVariant const&, QQmlContextData*, QFlags<QQmlPropertyPrivate::WriteFlag>)
>     > (in /opt/Qt5.2.0/5.2.0/gcc_64/lib/libQt5Qml.so.5.2.0)
>     > ==22064==    by 0x55DF174: QQmlPropertyPrivate::writeBinding(QObject*,
>     > QQmlPropertyData const&, QQmlContextData*, QQmlJavaScriptExpression*,
>     > QV4::ValueRef, bool, QFlags<QQmlPropertyPrivate::WriteFlag>) (in
>     > /opt/Qt5.2.0/5.2.0/gcc_64/lib/libQt5Qml.so.5.2.0)
>     > ==22064==    by 0x5684169:
>     > QQmlBinding::update(QFlags<QQmlPropertyPrivate::WriteFlag>) (in
>     > /opt/Qt5.2.0/5.2.0/gcc_64/lib/libQt5Qml.so.5.2.0)
>     > ==22064==    by 0x56844DD:
>     > QQmlBinding::expressionChanged(QQmlJavaScriptExpression*) (in
>     > /opt/Qt5.2.0/5.2.0/gcc_64/lib/libQt5Qml.so.5.2.0)
>     > ==22064==    by 0x565AE46: QQmlNotifier::emitNotify(QQmlNotifierEndpoint*,
>     > void**) (in /opt/Qt5.2.0/5.2.0/gcc_64/lib/libQt5Qml.so.5.2.0)
>     > ==22064==    by 0x55CA1CB:
>     > QQmlData::signalEmitted(QAbstractDeclarativeData*, QObject*, int, void**)
>     > (in /opt/Qt5.2.0/5.2.0/gcc_64/lib/libQt5Qml.so.5.2.0)
>     > ==22064==    by 0x6B4C126: QMetaObject::activate(QObject*, int, int,
>     > void**) (in /opt/Qt5.2.0/5.2.0/gcc_64/lib/libQt5Core.so.5.2.0)
>
>     --
>     Thiago Macieira - thiago.macieira (AT) intel.com <http://intel.com>
>        Software Architect - Intel Open Source Technology Center
>
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