Don't crash if calling a method on a QObject that has been gc()'d

As we don't actually delete an object immediately when it is collected,
it is possible to get into a situation where a method is called on an
object after the collector has marked it to be destroyed.  This fixes
a crash in this case.

Change-Id: I131d4c5d7ed788a91aa52f6af2e5c089d9bf5e08
Reviewed-by: Roberto Raggi <roberto.raggi@nokia.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/src/qml/qml/qqmldata_p.h b/src/qml/qml/qqmldata_p.h
index e7e001c4f2..3dd1c3ccba 100644
--- a/src/qml/qml/qqmldata_p.h
+++ b/src/qml/qml/qqmldata_p.h
@@ -181,11 +181,25 @@ public:
     QQmlNotifier *objectNameNotifier() const;
     QHash<int, QObject *> *attachedProperties() const;
 
+    static inline bool wasDeleted(QObject *);
 private:
     // For objectNameNotifier and attachedProperties
     mutable QQmlDataExtended *extendedData;
 };
 
+bool QQmlData::wasDeleted(QObject *object)
+{
+    if (!object)
+        return true;
+
+    QObjectPrivate *priv = QObjectPrivate::get(const_cast<QObject *>(object));
+    if (priv->wasDeleted)
+        return true;
+
+    return priv->declarativeData &&
+           static_cast<QQmlData *>(priv->declarativeData)->isQueuedForDeletion;
+}
+
 QQmlNotifierEndpoint *QQmlData::notify(int index)
 {
     Q_ASSERT(index <= 0xFFFF);