Fix JS ownership of model and delegate properties in QtQuick item views

When assigning a JS owned model or delegate to an item view, we must
ensure that they stay alive as long as the item view. This happens
easily for example when doing something like

    delegate: Qt.createComponent(...)

This patch takes the minimally invasive approach by changing the QObject
parent of such objects.

Task-number: QTBUG-50319
Task-number: QTBUG-51620
Change-Id: Ie6384b8dd93dcdc62d49f64b38173b3fc4ffd3b3
Reviewed-by: J-P Nurmi <jpnurmi@qt.io>

2 files changed, 68 insertions, 0 deletions

diff --git a/tests/auto/quick/qquickrepeater/data/ownership.qml b/tests/auto/quick/qquickrepeater/data/ownership.qml
new file mode 100644
index 0000000000..e13df3ab3a
--- /dev/null
+++ b/tests/auto/quick/qquickrepeater/data/ownership.qml
@@ -0,0 +1,4 @@
+import QtQuick 2.0
+
+Repeater {
+}
diff --git a/tests/auto/quick/qquickrepeater/tst_qquickrepeater.cpp b/tests/auto/quick/qquickrepeater/tst_qquickrepeater.cpp
index 791c3ae19a..0860956224 100644
--- a/tests/auto/quick/qquickrepeater/tst_qquickrepeater.cpp
+++ b/tests/auto/quick/qquickrepeater/tst_qquickrepeater.cpp
@@ -37,6 +37,7 @@
 #include <QtQuick/private/qquicktext_p.h>
 #include <QtQml/private/qqmllistmodel_p.h>
 #include <QtQml/private/qqmlobjectmodel_p.h>
+#include <QtGui/qstandarditemmodel.h>
 
 #include "../../shared/util.h"
 #include "../shared/viewtestutil.h"
@@ -77,6 +78,7 @@ private slots:
     void objectModel();
     void QTBUG54859_asynchronousMove();
     void package();
+    void ownership();
 };
 
 class TestObject : public QObject
@@ -1038,6 +1040,68 @@ void tst_QQuickRepeater::package()
     }
 }
 
+void tst_QQuickRepeater::ownership()
+{
+    QQmlEngine engine;
+
+    QQmlComponent component(&engine, testFileUrl("ownership.qml"));
+
+    QScopedPointer<QAbstractItemModel> aim(new QStandardItemModel);
+    QPointer<QAbstractItemModel> modelGuard(aim.data());
+    QQmlEngine::setObjectOwnership(aim.data(), QQmlEngine::JavaScriptOwnership);
+    {
+        QJSValue wrapper = engine.newQObject(aim.data());
+    }
+
+    QScopedPointer<QObject> repeater(component.create());
+    QVERIFY(!repeater.isNull());
+
+    QVERIFY(!QQmlData::keepAliveDuringGarbageCollection(aim.data()));
+
+    repeater->setProperty("model", QVariant::fromValue<QObject*>(aim.data()));
+
+    QVERIFY(!QQmlData::keepAliveDuringGarbageCollection(aim.data()));
+
+    engine.collectGarbage();
+    QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete);
+
+    QVERIFY(modelGuard);
+
+    QScopedPointer<QQmlComponent> delegate(new QQmlComponent(&engine));
+    delegate->setData(QByteArrayLiteral("import QtQuick 2.0\nItem{}"), dataDirectoryUrl().resolved(QUrl("inline.qml")));
+    QPointer<QQmlComponent> delegateGuard(delegate.data());
+    QQmlEngine::setObjectOwnership(delegate.data(), QQmlEngine::JavaScriptOwnership);
+    {
+        QJSValue wrapper = engine.newQObject(delegate.data());
+    }
+
+    QVERIFY(!QQmlData::keepAliveDuringGarbageCollection(delegate.data()));
+
+    repeater->setProperty("delegate", QVariant::fromValue<QObject*>(delegate.data()));
+
+    QVERIFY(!QQmlData::keepAliveDuringGarbageCollection(delegate.data()));
+
+    engine.collectGarbage();
+    QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete);
+
+    QVERIFY(delegateGuard);
+
+    repeater->setProperty("model", QVariant());
+    repeater->setProperty("delegate", QVariant());
+
+    QVERIFY(delegateGuard);
+    QVERIFY(modelGuard);
+
+    delegate.take();
+    aim.take();
+
+    engine.collectGarbage();
+    QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete);
+
+    QVERIFY(!delegateGuard);
+    QVERIFY(!modelGuard);
+}
+
 QTEST_MAIN(tst_QQuickRepeater)
 
 #include "tst_qquickrepeater.moc"