QtQml: Reset context object when destroying it from QObjectWrapper

There may be other objects that still hold on to the context data. We
should not leave them with a dangling context obejct.

Fixes: QTBUG-116228
Change-Id: I3dddd20b13956408d0e66c3a46e59377e45d91e5
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
(cherry picked from commit 1d3385e9887e912a79835c7defc878edf4ab7ec5)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

3 files changed, 35 insertions, 0 deletions

diff --git a/src/qml/jsruntime/qv4qobjectwrapper.cpp b/src/qml/jsruntime/qv4qobjectwrapper.cpp
index dcb4887511..3caad8bde9 100644
--- a/src/qml/jsruntime/qv4qobjectwrapper.cpp
+++ b/src/qml/jsruntime/qv4qobjectwrapper.cpp
@@ -1383,6 +1383,8 @@ void QObjectWrapper::destroyObject(bool lastCall)
                 if (ddata && ddata->ownContext) {
                     Q_ASSERT(ddata->ownContext.data() == ddata->context);
                     ddata->ownContext->emitDestruction();
+                    if (ddata->ownContext->contextObject() == o)
+                        ddata->ownContext->setContextObject(nullptr);
                     ddata->ownContext.reset();
                     ddata->context = nullptr;
                 }
diff --git a/tests/auto/qml/qqmlcontext/data/gcDeletesContextObject.qml b/tests/auto/qml/qqmlcontext/data/gcDeletesContextObject.qml
new file mode 100644
index 0000000000..a478a587df
--- /dev/null
+++ b/tests/auto/qml/qqmlcontext/data/gcDeletesContextObject.qml
@@ -0,0 +1,5 @@
+import QtQml
+QtObject {
+    property Component c: MyItem {}
+    property QtObject o: c.createObject()
+}
diff --git a/tests/auto/qml/qqmlcontext/tst_qqmlcontext.cpp b/tests/auto/qml/qqmlcontext/tst_qqmlcontext.cpp
index 95e4732fd0..055c6225f3 100644
--- a/tests/auto/qml/qqmlcontext/tst_qqmlcontext.cpp
+++ b/tests/auto/qml/qqmlcontext/tst_qqmlcontext.cpp
@@ -51,6 +51,7 @@ private slots:
     void destroyContextProperty();
 
     void numericContextProperty();
+    void gcDeletesContextObject();
 
 private:
     QQmlEngine engine;
@@ -989,6 +990,33 @@ void tst_qqmlcontext::numericContextProperty()
     QCOMPARE(context->contextProperty(QLatin1String("11")).toInt(), 42);
 }
 
+void tst_qqmlcontext::gcDeletesContextObject()
+{
+    QQmlEngine engine;
+    QQmlComponent c(&engine, testFileUrl("gcDeletesContextObject.qml"));
+
+    QVERIFY2(c.isReady(), qPrintable(c.errorString()));
+    QScopedPointer<QObject> o(c.create());
+
+    QVERIFY(!o.isNull());
+
+    QPointer<QObject> contextObject = o->property("o").value<QObject *>();
+    QVERIFY(contextObject != nullptr);
+
+    QQmlData *data = QQmlData::get(contextObject);
+    QVERIFY(data);
+    QQmlRefPointer<QQmlContextData> context = data->ownContext;
+    QVERIFY(context);
+    QCOMPARE(context->contextObject(), contextObject);
+
+    o->setProperty("o", QVariant::fromValue<QObject *>(nullptr));
+    QCOMPARE(o->property("o").value<QObject *>(), nullptr);
+    engine.collectGarbage();
+
+    QTRY_VERIFY(contextObject.isNull());
+    QCOMPARE(context->contextObject(), nullptr);
+}
+
 QTEST_MAIN(tst_qqmlcontext)
 
 #include "tst_qqmlcontext.moc"