Fix crash with StackView::initialItem

The following binding

    initialView: Qt.createComponent("blah.qml")

works with QQC1 but crashes with QQC2 as soon as the garbage collector
kicks in. In QQC1 StackView was implemented in a .qml file and the
property was declared as

    property var initialItem

For such declared properties the QML engine takes care of ensuring that
the reference assigned is a strong reference towards the GC and it also
tracks the life-time of the QObject in case it's explicitly deleted by
somebody else.

In QQC2 the property continues to be documented as "var" property,
however it is implemented in C++ as QVariant property. The QVariant is
not known to the GC at all and it also doesn't do life-cycle tracking.

The C++ equivalent to "var" in QML is QJSValue, which is a strong
reference and also ends up using a QPointer internally when holding a
QObject.

Task-number: QTBUG-67118
Change-Id: I43e473c7bf2c40f9843e9d50fe4fd805b54fd256
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/quicktemplates2/qquickstackview_p_p.h b/src/quicktemplates2/qquickstackview_p_p.h
index d86f35cd..7f1b77b1 100644
--- a/src/quicktemplates2/qquickstackview_p_p.h
+++ b/src/quicktemplates2/qquickstackview_p_p.h
@@ -96,7 +96,7 @@ public:
 
     bool busy;
     QString operation;
-    QVariant initialItem;
+    QJSValue initialItem;
     QQuickItem *currentItem;
     QSet<QQuickStackElement*> removing;
     QList<QQuickStackElement*> removed;