Space optimize QQmlStrongJSQObjectReference

We can get rid of the boolean member by reusing the objectDestroyed
function pointer.

Change-Id: Idb9e4d0ddfb04b109126378a6c18799018c74785
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
Reviewed-by: Marc Mutz <marc.mutz@qt.io>

2 files changed, 20 insertions, 4 deletions

diff --git a/src/qml/qml/qqmlengine.cpp b/src/qml/qml/qqmlengine.cpp
index 54f0698f79..99697f8e1a 100644
--- a/src/qml/qml/qqmlengine.cpp
+++ b/src/qml/qml/qqmlengine.cpp
@@ -1959,6 +1959,8 @@ bool QQml_isFileCaseCorrect(const QString &fileName, int lengthIn /* = -1 */)
     \sa {QQmlEngine::contextForObject()}{contextForObject()}, qmlEngine()
 */
 
+void hasJsOwnershipIndicator(QQmlGuardImpl *) {};
+
 QT_END_NAMESPACE
 
 #include "moc_qqmlengine.cpp"
diff --git a/src/qml/qml/qqmlguard_p.h b/src/qml/qml/qqmlguard_p.h
index 4286414bba..9c167b684b 100644
--- a/src/qml/qml/qqmlguard_p.h
+++ b/src/qml/qml/qqmlguard_p.h
@@ -103,6 +103,13 @@ public:
     T *data() const noexcept { return object(); }
 };
 
+/* used in QQmlStrongJSQObjectReference to indicate that the
+ * object has JS ownership
+ * We save it in objectDestroyFn to save space
+ * (implemented in qqmlengine.cpp)
+ */
+void Q_QML_PRIVATE_EXPORT hasJsOwnershipIndicator(QQmlGuardImpl *);
+
 template <typename T>
 class QQmlStrongJSQObjectReference : protected QQmlGuardImpl
 {
@@ -115,26 +122,33 @@ public:
     T &operator*() const { return *object(); }
     operator T *() const noexcept { return object(); }
     T *data() const noexcept { return object(); }
+
     void setObject(T *obj, QObject *parent) {
         T *old = object();
         if (obj == old)
             return;
 
-        if (m_jsOwnership && old && old->parent() == parent)
+        if (hasJsOwnership() && old && old->parent() == parent)
             QQml_setParent_noEvent(old, nullptr);
 
         QQmlGuardImpl::setObject(obj);
 
         if (obj && !obj->parent() && !QQmlData::keepAliveDuringGarbageCollection(obj)) {
-            m_jsOwnership = true;
+            setJsOwnership(true);
             QQml_setParent_noEvent(obj, parent);
         } else {
-            m_jsOwnership = false;
+            setJsOwnership(false);
         }
     }
 
 private:
-    bool m_jsOwnership = false;
+    bool hasJsOwnership() {
+        return objectDestroyed == hasJsOwnershipIndicator;
+    }
+
+    void setJsOwnership(bool itHasOwnership) {
+        objectDestroyed = itHasOwnership ? hasJsOwnershipIndicator : nullptr;
+    }
 };
 
 QT_END_NAMESPACE