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  1. Qt
  2. QTBUG-140220

qml plugins are not re-instantiated if qapplication is recreated

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    • Icon: Bug Bug
    • Resolution: Unresolved
    • Icon: P2: Important P2: Important
    • None
    • 6.10
    • Quick: Controls 2
    • None

      i'm seeing a crash in this scenario:

      • create qApp, QQuickView
      • destroy them
      • re-create qApp, QQuickView

      it crashes when QQuickNativeStyle::style() will returns a nullptr:

      1   QtMin::QQuickStyleItemSlider::calculateGeometry()                                                                                                                                                qquickstyleitemslider.cpp   32   0x1736f15c4 
2   QtMin::QQuickStyleItem::updateGeometry()                                                                                                                                                         qquickstyleitem.cpp         275  0x1736e8728 
3   QtMin::QQuickStyleItem::componentComplete()                                                                                                                                                      qquickstyleitem.cpp         471  0x1736ea314 
4   QtMin::QQmlObjectCreator::finalize(QtMin::QQmlInstantiationInterrupt&)                                                                                                                           qqmlobjectcreator.cpp       1615 0x171d9c92c 
5   QtMin::QQmlComponentPrivate::complete(QtMin::QQmlEnginePrivate *, QtMin::QQmlComponentPrivate::ConstructionState *)                                                                              qqmlcomponent.cpp           1224 0x171ef84e0 
6   QtMin::QQmlComponentPrivate::completeDeferred(QtMin::QQmlEnginePrivate *, std::vector<QtMin::QQmlComponentPrivate::ConstructionState> *)                                                         qqmlcomponent.cpp           1217 0x171ee0224 
7   QtMin::QtQuickPrivate::completeDeferred(QtMin::QObject *, QtMin::QString const&, QtMin::QQuickUntypedDeferredPointer *, QtMin::QQmlEngine *)                                                     qquickdeferredexecute.cpp   166  0x17393c0a8 
8   void QtMin::quickCompleteDeferred<QtMin::QQuickItem>(QtMin::QObject *, QtMin::QString const&, QtMin::QQuickDeferredPointer<QtMin::QQuickItem>&)                                                  qquickdeferredexecute_p_p.h 67   0x1737f75d4 
9   QtMin::QQuickSliderPrivate::executeHandle(bool)                                                                                                                                                  qquickslider.cpp            223  0x1738d9928 
10  QtMin::QQuickSlider::componentComplete()                                                                                                                                                         qquickslider.cpp            867  0x1738db3fc 
11  QtMin::QQmlObjectCreator::finalize(QtMin::QQmlInstantiationInterrupt&)                                                                                                                           qqmlobjectcreator.cpp       1615 0x171d9c92c 
12  QtMin::QQmlComponentPrivate::complete(QtMin::QQmlEnginePrivate *, QtMin::QQmlComponentPrivate::ConstructionState *)                                                                              qqmlcomponent.cpp           1224 0x171ef84e0 
13  QtMin::QQmlComponentPrivate::completeCreate()                                                                                                                                                    qqmlcomponent.cpp           1342 0x171ef68e0 
14  QtMin::QQmlComponent::completeCreate()                                                                                                                                                           qqmlcomponent.cpp           1308 0x171efa6e4 
15  QtMin::QQmlComponentPrivate::createWithProperties(QtMin::QObject *, QtMin::QMap<QtMin::QString, QtMin::QVariant>const&, QtMin::QQmlContext *, QtMin::QQmlComponentPrivate::CreateBehavior, bool) qqmlcomponent.cpp           996  0x171ef8328 
16  QtMin::QQmlComponent::createWithInitialProperties(QtMin::QMap<QtMin::QString, QtMin::QVariant>const&, QtMin::QQmlContext *)                                                                      qqmlcomponent.cpp           962  0x171eee444 
17  QtMin::QQuickView::continueExecute()                                                                                                                                                             qquickview.cpp              516  0x1728befc0 
18  QtMin::QQuickViewPrivate::execute(QtMin::QAnyStringView, QtMin::QAnyStringView)                                                                                                                  qquickview.cpp              92   0x1728bf2f8 
19  QtMin::QQuickView::loadFromModule(QtMin::QAnyStringView, QtMin::QAnyStringView)                                                                                                                  qquickview.cpp              259  0x1728bf67c

      observations:

      • QtQuickControls2NativeStylePlugin::initializeEngine deletes/nulls the s_style pointer via qAddPostRoutine()
      • QQuickNativeStyle::setStyle is never re-populated again via `QtQuickControls2NativeStylePlugin::initializeEngine`

      so it smells like there is some caching that outlives the lifetime of the QApplication, which prevents initializeEngine from running again ...

        For Gerrit Dashboard: QTBUG-140220
        # Subject Branch Project Status CR V
        676880,1 Native style: re-initialize engine after re-creating qApplication dev qt/qtdeclarative Status: NEW 0 0

            qt.team.quick.subscriptions Qt Quick and Widgets Team
            timblechmann tim blechmann
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              Created:
              Updated:

                There is 1 open Gerrit change