Fix crash when accessing a deleted object

In QObjectWrapper::query(), return QV4::Attr_Invalid if the object was
deleted.

Task-number: QTBUG-44153
Change-Id: I53e8be6196489c323b190dbfa20d2dda2a54315e
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

2 files changed, 36 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmllanguage/data/accessDeletedObject.qml b/tests/auto/qml/qqmllanguage/data/accessDeletedObject.qml
new file mode 100644
index 0000000000..e5151096e5
--- /dev/null
+++ b/tests/auto/qml/qqmllanguage/data/accessDeletedObject.qml
@@ -0,0 +1,12 @@
+import QtQuick 2.0
+
+Item {
+    id: root
+
+    Component.onCompleted: {
+        var createdObject = objectCreator.create()
+        createdObject.del()
+        // Shouldn't crash.
+        var test = "index" in createdObject
+    }
+}
diff --git a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
index b1a17afd2c..1af57f9247 100644
--- a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
+++ b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
@@ -269,6 +269,8 @@ private slots:
 
     void concurrentLoadQmlDir();
 
+    void accessDeletedObject();
+
 private:
     QQmlEngine engine;
     QStringList defaultImportPathList;
@@ -4571,6 +4573,28 @@ void tst_qqmllanguage::concurrentLoadQmlDir()
     engine.setImportPathList(defaultImportPathList);
 }
 
+// Test that deleting an object and then accessing it doesn't crash.
+// QTBUG-44153
+class ObjectCreator : public QObject
+{
+    Q_OBJECT
+public slots:
+    QObject *create() { return (new ObjectCreator); }
+    void del() { delete this; }
+};
+
+void tst_qqmllanguage::accessDeletedObject()
+{
+    QQmlEngine engine;
+
+    engine.rootContext()->setContextProperty("objectCreator", new ObjectCreator);
+    QQmlComponent component(&engine, testFileUrl("accessDeletedObject.qml"));
+    VERIFY_ERRORS(0);
+
+    QScopedPointer<QObject> o(component.create());
+    QVERIFY(!o.isNull());
+}
+
 QTEST_MAIN(tst_qqmllanguage)
 
 #include "tst_qqmllanguage.moc"