Cocoa Menus: Give platform menu ownership back to QWidgets

We don't want to be in the situation where a QCocoaMenuItem
owns a QCocoaMenu (because that item is a submenu), and then
the actual QMenu "sees" that same QCocoaMenu being deleted.

Instead, since all the QCocoaMenu* classes inherit QObject,
we rely on meta-object properties to set the hierarchy and
climb the hierarchy when guessing the menu item's role.

This ammends most of commit 370e89f06465a4d61c7b.

Task-number: QTBUG-36785
Change-Id: I0e03acb593e93061c8c6c1fdd161669cf0d2a293
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>

3 files changed, 12 insertions, 9 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoamenu.mm b/src/plugins/platforms/cocoa/qcocoamenu.mm
index aa6b71df31..35e8fdebb4 100644
--- a/src/plugins/platforms/cocoa/qcocoamenu.mm
+++ b/src/plugins/platforms/cocoa/qcocoamenu.mm
@@ -269,7 +269,7 @@ void QCocoaMenu::insertMenuItem(QPlatformMenuItem *menuItem, QPlatformMenuItem *
     QCocoaMenuItem *cocoaItem = static_cast<QCocoaMenuItem *>(menuItem);
     QCocoaMenuItem *beforeItem = static_cast<QCocoaMenuItem *>(before);
 
-    menuItem->setParent(this);
+    SET_COCOA_MENU_ANCESTOR(menuItem, this);
     cocoaItem->sync();
     if (beforeItem) {
         int index = m_menuItems.indexOf(beforeItem);
@@ -326,8 +326,8 @@ void QCocoaMenu::removeMenuItem(QPlatformMenuItem *menuItem)
         return;
     }
 
-    if (menuItem->parent() == this)
-        menuItem->setParent(0);
+    if (COCOA_MENU_ANCESTOR(menuItem) == this)
+        SET_COCOA_MENU_ANCESTOR(menuItem, 0);
 
     m_menuItems.removeOne(cocoaItem);
     if (!cocoaItem->isMerged()) {
@@ -551,7 +551,7 @@ void QCocoaMenu::syncModalState(bool modal)
 void QCocoaMenu::setMenuBar(QCocoaMenuBar *menuBar)
 {
     m_menuBar = menuBar;
-    setParent(menuBar);
+    SET_COCOA_MENU_ANCESTOR(this, menuBar);
 }
 
 QCocoaMenuBar *QCocoaMenu::menuBar() const
diff --git a/src/plugins/platforms/cocoa/qcocoamenuitem.h b/src/plugins/platforms/cocoa/qcocoamenuitem.h
index 1e69ed5a4b..b0169b9746 100644
--- a/src/plugins/platforms/cocoa/qcocoamenuitem.h
+++ b/src/plugins/platforms/cocoa/qcocoamenuitem.h
@@ -118,6 +118,9 @@ private:
     quintptr m_tag;
 };
 
+#define COCOA_MENU_ANCESTOR(m) ((m)->property("_qCocoaMenuAncestor").value<QObject *>())
+#define SET_COCOA_MENU_ANCESTOR(m, ancestor) (m)->setProperty("_qCocoaMenuAncestor", QVariant::fromValue<QObject *>(ancestor))
+
 QT_END_NAMESPACE
 
 #endif
diff --git a/src/plugins/platforms/cocoa/qcocoamenuitem.mm b/src/plugins/platforms/cocoa/qcocoamenuitem.mm
index 3bba1ee1d5..2246d2ce46 100644
--- a/src/plugins/platforms/cocoa/qcocoamenuitem.mm
+++ b/src/plugins/platforms/cocoa/qcocoamenuitem.mm
@@ -126,13 +126,13 @@ void QCocoaMenuItem::setMenu(QPlatformMenu *menu)
 {
     if (menu == m_menu)
         return;
-    if (m_menu && m_menu->parent() == this)
-        m_menu->setParent(0);
+    if (m_menu && COCOA_MENU_ANCESTOR(m_menu) == this)
+        SET_COCOA_MENU_ANCESTOR(m_menu, 0);
 
     QCocoaAutoReleasePool pool;
     m_menu = static_cast<QCocoaMenu *>(menu);
     if (m_menu) {
-        m_menu->setParent(this);
+        SET_COCOA_MENU_ANCESTOR(m_menu, this);
     } else {
         // we previously had a menu, but no longer
         // clear out our item so the nexy sync() call builds a new one
@@ -217,12 +217,12 @@ NSMenuItem *QCocoaMenuItem::sync()
             mergeItem = [loader preferencesMenuItem];
             break;
         case TextHeuristicRole: {
-            QObject *p = parent();
+            QObject *p = COCOA_MENU_ANCESTOR(this);
             int depth = 1;
             QCocoaMenuBar *menubar = 0;
             while (depth < 3 && p && !(menubar = qobject_cast<QCocoaMenuBar *>(p))) {
                 ++depth;
-                p = p->parent();
+                p = COCOA_MENU_ANCESTOR(p);
             }
             if (depth == 3 || !menubar)
                 break; // Menu item too deep in the hierarchy, or not connected to any menubar