4 files changed, 44 insertions, 17 deletions
diff --git a/src/corelib/kernel/qabstracteventdispatcher.cpp b/src/corelib/kernel/qabstracteventdispatcher.cpp
index 31369f9a09..907b3ccf1f 100644
--- a/src/corelib/kernel/qabstracteventdispatcher.cpp
+++ b/src/corelib/kernel/qabstracteventdispatcher.cpp
@@ -458,7 +458,7 @@ bool QAbstractEventDispatcher::filterNativeEvent(const QByteArray &eventType, vo
     if (!d->eventFilters.isEmpty()) {
         // Raise the loopLevel so that deleteLater() calls in or triggered
         // by event_filter() will be processed from the main event loop.
-        QScopedLoopLevelCounter loopLevelCounter(d->threadData);
+        QScopedScopeLevelCounter scopeLevelCounter(d->threadData);
         for (int i = 0; i < d->eventFilters.size(); ++i) {
             QAbstractNativeEventFilter *filter = d->eventFilters.at(i);
             if (!filter)
diff --git a/src/corelib/kernel/qcoreapplication.cpp b/src/corelib/kernel/qcoreapplication.cpp
index 60f3dc0db0..42bda25be5 100644
--- a/src/corelib/kernel/qcoreapplication.cpp
+++ b/src/corelib/kernel/qcoreapplication.cpp
@@ -980,7 +980,7 @@ bool QCoreApplication::notifyInternal2(QObject *receiver, QEvent *event)
     // call overhead.
     QObjectPrivate *d = receiver->d_func();
     QThreadData *threadData = d->threadData;
-    QScopedLoopLevelCounter loopLevelCounter(threadData);
+    QScopedScopeLevelCounter scopeLevelCounter(threadData);
     if (!selfRequired)
         return doNotify(receiver, event);
     return self->notify(receiver, event);
@@ -1193,6 +1193,9 @@ void QCoreApplication::processEvents(QEventLoop::ProcessEventsFlags flags)
 */
 void QCoreApplication::processEvents(QEventLoop::ProcessEventsFlags flags, int maxtime)
 {
+    // ### Qt 6: consider splitting this method into a public and a private
+    //           one, so that a user-invoked processEvents can be detected
+    //           and handled properly.
     QThreadData *data = QThreadData::current();
     if (!data->hasEventDispatcher())
         return;
@@ -1396,8 +1399,24 @@ void QCoreApplication::postEvent(QObject *receiver, QEvent *event, int priority)
 
     if (event->type() == QEvent::DeferredDelete && data == QThreadData::current()) {
         // remember the current running eventloop for DeferredDelete
-        // events posted in the receiver's thread
-        static_cast<QDeferredDeleteEvent *>(event)->level = data->loopLevel;
+        // events posted in the receiver's thread.
+
+        // Events sent by non-Qt event handlers (such as glib) may not
+        // have the scopeLevel set correctly. The scope level makes sure that
+        // code like this:
+        //     foo->deleteLater();
+        //     qApp->processEvents(); // without passing QEvent::DeferredDelete
+        // will not cause "foo" to be deleted before returning to the event loop.
+
+        // If the scope level is 0 while loopLevel != 0, we are called from a
+        // non-conformant code path, and our best guess is that the scope level
+        // should be 1. (Loop level 0 is special: it means that no event loops
+        // are running.)
+        int loopLevel = data->loopLevel;
+        int scopeLevel = data->scopeLevel;
+        if (scopeLevel == 0 && loopLevel != 0)
+            scopeLevel = 1;
+        static_cast<QDeferredDeleteEvent *>(event)->level = loopLevel + scopeLevel;
     }
 
     // delete the event on exceptions to protect against memory leaks till the event is
@@ -1474,6 +1493,9 @@ bool QCoreApplication::compressEvent(QEvent *event, QObject *receiver, QPostEven
 */
 void QCoreApplication::sendPostedEvents(QObject *receiver, int event_type)
 {
+    // ### Qt 6: consider splitting this method into a public and a private
+    //           one, so that a user-invoked sendPostedEvents can be detected
+    //           and handled properly.
     QThreadData *data = QThreadData::current();
 
     QCoreApplicationPrivate::sendPostedEvents(receiver, event_type, data);
@@ -1565,15 +1587,19 @@ void QCoreApplicationPrivate::sendPostedEvents(QObject *receiver, int event_type
         }
 
         if (pe.event->type() == QEvent::DeferredDelete) {
-            // DeferredDelete events are only sent when we are explicitly asked to
-            // (s.a. QEvent::DeferredDelete), and then only if the event loop that
-            // posted the event has returned.
-            int loopLevel = static_cast<QDeferredDeleteEvent *>(pe.event)->loopLevel();
+            // DeferredDelete events are sent either
+            // 1) when the event loop that posted the event has returned; or
+            // 2) if explicitly requested (with QEvent::DeferredDelete) for
+            //    events posted by the current event loop; or
+            // 3) if the event was posted before the outermost event loop.
+
+            int eventLevel = static_cast<QDeferredDeleteEvent *>(pe.event)->loopLevel();
+            int loopLevel = data->loopLevel + data->scopeLevel;
             const bool allowDeferredDelete =
-                (loopLevel > data->loopLevel
-                 || (!loopLevel && data->loopLevel > 0)
+                (eventLevel > loopLevel
+                 || (!eventLevel && loopLevel > 0)
                  || (event_type == QEvent::DeferredDelete
-                     && loopLevel == data->loopLevel));
+                     && eventLevel == loopLevel));
             if (!allowDeferredDelete) {
                 // cannot send deferred delete
                 if (!event_type && !receiver) {
diff --git a/src/corelib/thread/qthread.cpp b/src/corelib/thread/qthread.cpp
index 14209d8d8c..69f8d72b47 100644
--- a/src/corelib/thread/qthread.cpp
+++ b/src/corelib/thread/qthread.cpp
@@ -56,7 +56,7 @@ QT_BEGIN_NAMESPACE
 */
 
 QThreadData::QThreadData(int initialRefCount)
-    : _ref(initialRefCount), loopLevel(0), thread(0), threadId(0),
+    : _ref(initialRefCount), loopLevel(0), scopeLevel(0), thread(0), threadId(0),
       eventDispatcher(0),
       quitNow(false), canWait(true), isAdopted(false), requiresCoreApplication(true)
 {
diff --git a/src/corelib/thread/qthread_p.h b/src/corelib/thread/qthread_p.h
index 39a41f1ef4..5f7d01f50f 100644
--- a/src/corelib/thread/qthread_p.h
+++ b/src/corelib/thread/qthread_p.h
@@ -280,6 +280,7 @@ private:
 
 public:
     int loopLevel;
+    int scopeLevel;
 
     QStack<QEventLoop *> eventLoops;
     QPostEventList postEventList;
@@ -295,15 +296,15 @@ public:
     bool requiresCoreApplication;
 };
 
-class QScopedLoopLevelCounter
+class QScopedScopeLevelCounter
 {
     QThreadData *threadData;
 public:
-    inline QScopedLoopLevelCounter(QThreadData *threadData)
+    inline QScopedScopeLevelCounter(QThreadData *threadData)
         : threadData(threadData)
-    { ++threadData->loopLevel; }
-    inline ~QScopedLoopLevelCounter()
-    { --threadData->loopLevel; }
+    { ++threadData->scopeLevel; }
+    inline ~QScopedScopeLevelCounter()
+    { --threadData->scopeLevel; }
 };
 
 // thread wrapper for the main() thread