Details
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Bug
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Resolution: Done
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P1: Critical
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6.3.0, 6.4
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Linux/X11
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dc77f7c71c (qt/qtdeclarative/dev) dc77f7c71c (qt/tqtc-qtdeclarative/dev)
Description
The sample code has a custom implemented QAbstratListModel that returns an empty/invalid QVariant as data. When using this model in a (qml) Repeater where the delegate item has it declared as a required property, it causes a segfault.
QVariant MyModel::data(const QModelIndex&, int) const { return QVariant(); }
Repeater {
model: MyModel
delegate: Text {
id: delegate
text: delegate.name
required property string name
}
}
1 QV4::Function::sourceLocation qv4function.cpp 222 0x7ffff74c5327 2 QQmlJavaScriptExpression::sourceLocation qtaggedpointer.h 135 0x7ffff760c01d 3 QQmlBinding::sourceLocation qqmlbinding.cpp 113 0x7ffff75a9ee5 4 QQmlNonbindingBinding::doUpdate qqmlbinding.cpp 291 0x7ffff75ad629 5 QQmlBinding::update qqmlbinding.cpp 199 0x7ffff75a9869 6 QQDMIncubationTask::initializeRequiredProperties qqmldelegatemodel.cpp 1037 0x7ffff78e52c3 7 QQmlDelegateModelPrivate::setInitialState qqmldelegatemodel.cpp 1213 0x7ffff78e55e2 8 QQmlIncubatorPrivate::incubate qqmlincubator.cpp 334 0x7ffff760914b 9 QQmlEnginePrivate::incubate qqmlincubator.cpp 90 0x7ffff7609414 10 QQmlDelegateModelPrivate::object qqmldelegatemodel.cpp 1309 0x7ffff78e6caf 11 QQuickRepeaterPrivate::requestItems qquickrepeater.cpp 403 0x7ffff7df5a8f 12 QQuickRepeater::componentComplete qquickrepeater.cpp 347 0x7ffff7df8b73 13 QQmlObjectCreator::finalize qqmlobjectcreator.cpp 1452 0x7ffff763523e 14 QQmlComponentPrivate::complete unique_ptr.h 173 0x7ffff75c22a9 15 QQmlComponentPrivate::complete qqmlcomponent.cpp 1049 0x7ffff75c22a9 16 QQmlComponentPrivate::completeCreate qqmlcomponent.cpp 1147 0x7ffff75c5547 17 QQmlComponent::completeCreate qqmlcomponent.cpp 1134 0x7ffff75c5693 18 QQmlComponent::create qqmlcomponent.cpp 866 0x7ffff75c5693 19 QQmlApplicationEnginePrivate::finishLoad qqmlapplicationengine.cpp 158 0x7ffff75a5673 20 QQmlApplicationEngine::load qqmlapplicationengine.cpp 323 0x7ffff75a5c1c 21 main main.cpp 16 0x404ad6
We are having code running with Qt 5.15.9 that does not produce the segfault, so this was probably introduced in some 6.x version.
When implementing a Q_INVOKABLE that returns an empty QVariant, there is a message like this:
qrc:/riq/main.qml:12:9: Unable to assign [undefined] to QString
I understand that it is not a good idea to use invalid QVariants, but imho it should not result in a segfault. A warning or even exception in the way of the Q_INVOKABLE case would be ok, but right now there is just a stack trace which does not really point to the problem.