Fixed a memory-leak when changing property bindings in states.

Bindings that were still stored in the revert-list when the state
was destructed were not deleted before. This could lead to considerable
memory leaks in big applications.

Change-Id: I73250f7d03a42c25ca729c18082125fd8f3c8989
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>

2 files changed, 41 insertions, 0 deletions

diff --git a/tests/auto/quick/qquickstates/data/revertListMemoryLeak.qml b/tests/auto/quick/qquickstates/data/revertListMemoryLeak.qml
new file mode 100644
index 0000000000..b49487c895
--- /dev/null
+++ b/tests/auto/quick/qquickstates/data/revertListMemoryLeak.qml
@@ -0,0 +1,16 @@
+import QtQuick 2.0
+
+Item {
+    id: rect
+    width: 40;
+    property real boundHeight: 42
+    height: boundHeight;
+
+    states: [
+        State {
+            objectName: "testState"
+            name: "testState"
+            PropertyChanges { target: rect; height: 60; }
+        }
+    ]
+}
diff --git a/tests/auto/quick/qquickstates/tst_qquickstates.cpp b/tests/auto/quick/qquickstates/tst_qquickstates.cpp
index 51fe9b4c96..6c42a7a0ee 100644
--- a/tests/auto/quick/qquickstates/tst_qquickstates.cpp
+++ b/tests/auto/quick/qquickstates/tst_qquickstates.cpp
@@ -141,6 +141,7 @@ private slots:
     void avoidFastForward();
     void revertListBug();
     void QTBUG_38492();
+    void revertListMemoryLeak();
 };
 
 void tst_qquickstates::initTestCase()
@@ -1634,6 +1635,30 @@ void tst_qquickstates::QTBUG_38492()
     delete item;
 }
 
+void tst_qquickstates::revertListMemoryLeak()
+{
+    QWeakPointer<QQmlAbstractBinding> weakPtr;
+    {
+        QQmlEngine engine;
+
+        QQmlComponent c(&engine, testFileUrl("revertListMemoryLeak.qml"));
+        QQuickItem *item = qobject_cast<QQuickItem *>(c.create());
+        QVERIFY(item);
+        QQuickState *state = item->findChild<QQuickState*>("testState");
+        QVERIFY(state);
+
+        item->setState("testState");
+
+        QQmlAbstractBinding *binding = state->bindingInRevertList(item, "height");
+        QVERIFY(binding);
+        weakPtr = QQmlAbstractBinding::getPointer(binding);
+        QVERIFY(!weakPtr.toStrongRef().isNull());
+
+        delete item;
+    }
+    QVERIFY(weakPtr.toStrongRef().isNull());
+}
+
 QTEST_MAIN(tst_qquickstates)
 
 #include "tst_qquickstates.moc"