Update var property to null on object deletion

When a var property contains a pointer to a QObject-derived instance,
ensure that object deletion causes the property to be updated.

Task-number: QTBUG-26542
Change-Id: I67a59ffd7f09063328d45dc84889add55a5428e4
Reviewed-by: Martin Jones <martin.jones@nokia.com>

5 files changed, 193 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmllanguage/data/objectDeletionNotify.1.qml b/tests/auto/qml/qqmllanguage/data/objectDeletionNotify.1.qml
new file mode 100644
index 0000000000..acd5463a3c
--- /dev/null
+++ b/tests/auto/qml/qqmllanguage/data/objectDeletionNotify.1.qml
@@ -0,0 +1,37 @@
+import QtQuick 2.0
+
+Item {
+    property bool success: false
+
+    Component {
+        id: internal
+
+        Item {
+        }
+    }
+
+    property bool expectNull: null
+
+    function setExpectNull(b) {
+        success = false;
+        expectNull = b;
+    }
+
+    property QtObject obj: null
+    onObjChanged: success = (expectNull ? obj == null : obj != null)
+
+    Component.onCompleted: {
+        setExpectNull(false)
+        obj = internal.createObject(null, {})
+        if (!success) return
+
+        // Replace with a different object
+        setExpectNull(false)
+        obj = internal.createObject(null, {})
+    }
+
+    function destroyObject() {
+        setExpectNull(true)
+        obj.destroy();
+    }
+}
diff --git a/tests/auto/qml/qqmllanguage/data/objectDeletionNotify.2.qml b/tests/auto/qml/qqmllanguage/data/objectDeletionNotify.2.qml
new file mode 100644
index 0000000000..ed0e0d10f0
--- /dev/null
+++ b/tests/auto/qml/qqmllanguage/data/objectDeletionNotify.2.qml
@@ -0,0 +1,37 @@
+import QtQuick 2.0
+
+Item {
+    property bool success: false
+
+    Component {
+        id: internal
+
+        Item {
+        }
+    }
+
+    property bool expectNull: null
+
+    function setExpectNull(b) {
+        success = false;
+        expectNull = b;
+    }
+
+    property variant obj: null
+    onObjChanged: success = (expectNull ? obj == null : obj != null)
+
+    Component.onCompleted: {
+        setExpectNull(false)
+        obj = internal.createObject(null, {})
+        if (!success) return
+
+        // Replace with a different object
+        setExpectNull(false)
+        obj = internal.createObject(null, {})
+    }
+
+    function destroyObject() {
+        setExpectNull(true)
+        obj.destroy();
+    }
+}
diff --git a/tests/auto/qml/qqmllanguage/data/objectDeletionNotify.3.qml b/tests/auto/qml/qqmllanguage/data/objectDeletionNotify.3.qml
new file mode 100644
index 0000000000..f5e94ba715
--- /dev/null
+++ b/tests/auto/qml/qqmllanguage/data/objectDeletionNotify.3.qml
@@ -0,0 +1,37 @@
+import QtQuick 2.0
+
+Item {
+    property bool success: false
+
+    Component {
+        id: internal
+
+        Item {
+        }
+    }
+
+    property bool expectNull: null
+
+    function setExpectNull(b) {
+        success = false;
+        expectNull = b;
+    }
+
+    property var obj: null
+    onObjChanged: success = (expectNull ? obj == null : obj != null)
+
+    Component.onCompleted: {
+        setExpectNull(false)
+        obj = internal.createObject(null, {})
+        if (!success) return
+
+        // Replace with a different object
+        setExpectNull(false)
+        obj = internal.createObject(null, {})
+    }
+
+    function destroyObject() {
+        setExpectNull(true)
+        obj.destroy();
+    }
+}
diff --git a/tests/auto/qml/qqmllanguage/data/objectDeletionNotify.4.qml b/tests/auto/qml/qqmllanguage/data/objectDeletionNotify.4.qml
new file mode 100644
index 0000000000..ccfda01644
--- /dev/null
+++ b/tests/auto/qml/qqmllanguage/data/objectDeletionNotify.4.qml
@@ -0,0 +1,48 @@
+import QtQuick 2.0
+
+Item {
+    property bool success: false
+
+    Component {
+        id: internal
+
+        Item {
+        }
+    }
+
+    property var expectNull: null
+
+    function setExpectNull(b) {
+        success = false;
+        expectNull = b;
+    }
+
+    function setExpectNoChange() {
+        success = true;
+        expectNull = null;
+    }
+
+    property var obj: null
+    onObjChanged: success = (expectNull == null) ? false : (expectNull ? obj == null : obj != null)
+
+    property var temp: null
+
+    Component.onCompleted: {
+        // Set obj to contain an object
+        setExpectNull(false)
+        obj = internal.createObject(null, {})
+        if (!success) return
+
+        // Use temp variable to keep object reference alive
+        temp = obj
+
+        // Change obj to contain a string
+        setExpectNull(false)
+        obj = 'hello'
+    }
+
+    function destroyObject() {
+        setExpectNoChange()
+        temp.destroy();
+    }
+}
diff --git a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
index 2c9593bd01..316d7e28a7 100644
--- a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
+++ b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
@@ -179,6 +179,9 @@ private slots:
     void literals_data();
     void literals();
 
+    void objectDeletionNotify_data();
+    void objectDeletionNotify();
+
 private:
     QQmlEngine engine;
     QStringList defaultImportPathList;
@@ -2987,6 +2990,37 @@ void tst_qqmllanguage::literals()
     delete object;
 }
 
+void tst_qqmllanguage::objectDeletionNotify_data()
+{
+    QTest::addColumn<QString>("file");
+
+    QTest::newRow("property QtObject") << "objectDeletionNotify.1.qml";
+    QTest::newRow("property variant") << "objectDeletionNotify.2.qml";
+    QTest::newRow("property var") << "objectDeletionNotify.3.qml";
+    QTest::newRow("property var guard removed") << "objectDeletionNotify.4.qml";
+}
+
+void tst_qqmllanguage::objectDeletionNotify()
+{
+    QFETCH(QString, file);
+
+    QQmlComponent component(&engine, testFile(file));
+
+    QObject *object = component.create();
+    QVERIFY(object != 0);
+    QCOMPARE(object->property("success").toBool(), true);
+
+    QMetaObject::invokeMethod(object, "destroyObject");
+
+    // Process the deletion event
+    QCoreApplication::sendPostedEvents(0, QEvent::DeferredDelete);
+    QCoreApplication::processEvents();
+
+    QCOMPARE(object->property("success").toBool(), true);
+
+    delete object;
+}
+
 QTEST_MAIN(tst_qqmllanguage)
 
 #include "tst_qqmllanguage.moc"