Q*Application: move the compressEvent() virtual to the Private class

One of the parameters is the QPostEventList, which is declared in
qthread_p.h:
   class QPostEventList : public QList<QPostEvent>
and is thus private API anyway. This also requires the ELFVERSION: token
in qthread_p.h to avoid marking every class derived from Q*Application
as needing private Qt ABI.

We can't remove the virtual in Qt 6, so we keep the fallback
implementations to just forward to the Private::compressEvent() call.

I've elected to mark the QApplication's override as final.

Change-Id: I49a46f42e62bcaf7db69fffd12a664d8720bbe46
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/kernel/qcoreapplication.cpp

@@ -1686,7 +1686,14 @@ void QCoreApplication::postEvent(QObject *receiver, QEvent *event, int priority)
   \internal
   Returns \c true if \a event was compressed away (possibly deleted) and should not be added to the list.
 */
+#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0)
 bool QCoreApplication::compressEvent(QEvent *event, QObject *receiver, QPostEventList *postedEvents)
+{
+    return d_func()->compressEvent(event, receiver, postedEvents);
+}
+#endif
+
+bool QCoreApplicationPrivate::compressEvent(QEvent *event, QObject *receiver, QPostEventList *postedEvents)
 {
     Q_ASSERT(event);
     Q_ASSERT(receiver);

src/corelib/kernel/qcoreapplication.h

@@ -30,7 +30,9 @@ QT_BEGIN_NAMESPACE
 
 class QCoreApplicationPrivate;
 class QTranslator;
+#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0)
 class QPostEventList;
+#endif
 class QAbstractEventDispatcher;
 class QAbstractNativeEventFilter;
 class QEventLoopLocker;
@@ -211,7 +213,9 @@ public Q_SLOTS:
 protected:
     bool event(QEvent *) override;
 
+#  if QT_VERSION < QT_VERSION_CHECK(7, 0, 0)
     virtual bool compressEvent(QEvent *, QObject *receiver, QPostEventList *);
+#  endif
 #endif // QT_NO_QOBJECT
 
 protected:

src/corelib/kernel/qcoreapplication_p.h

@@ -98,6 +98,7 @@ class Q_CORE_EXPORT QCoreApplicationPrivate
 
     virtual void createEventDispatcher();
     virtual void eventDispatcherReady();
+    virtual bool compressEvent(QEvent *event, QObject *receiver, QPostEventList *postedEvents);
     static void removePostedEvent(QEvent *);
 #ifdef Q_OS_WIN
     static void removePostedTimerEvent(QObject *object, int timerId);

src/corelib/thread/qthread_p.h

@@ -58,6 +58,7 @@ inline bool operator<(const QPostEvent &first, const QPostEvent &second)
 
 // This class holds the list of posted events.
 //  The list has to be kept sorted by priority
+// ### Qt7 remove the next line
 // It's used in a virtual in QCoreApplication, so ELFVERSION:ignore-next
 class QPostEventList : public QList<QPostEvent>
 {

src/gui/kernel/qevent.h

@@ -510,6 +510,7 @@ class Q_GUI_EXPORT QMoveEvent : public QEvent
 protected:
     QPoint m_pos, m_oldPos;
     friend class QApplication;
+    friend class QApplicationPrivate;
 };
 
 class Q_GUI_EXPORT QExposeEvent : public QEvent
@@ -556,6 +557,7 @@ class Q_GUI_EXPORT QResizeEvent : public QEvent
 protected:
     QSize m_size, m_oldSize;
     friend class QApplication;
+    friend class QApplicationPrivate;
 };
 
 

src/gui/kernel/qguiapplication.cpp

@@ -2120,13 +2120,15 @@ bool QGuiApplication::event(QEvent *e)
     return QCoreApplication::event(e);
 }
 
+#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0)
 /*!
     \internal
 */
 bool QGuiApplication::compressEvent(QEvent *event, QObject *receiver, QPostEventList *postedEvents)
 {
     return QCoreApplication::compressEvent(event, receiver, postedEvents);
 }
+#endif
 
 bool QGuiApplicationPrivate::sendQWindowEventToQPlatformWindow(QWindow *window, QEvent *event)
 {

src/gui/kernel/qguiapplication.h

@@ -163,7 +163,9 @@ class Q_GUI_EXPORT QGuiApplication : public QCoreApplication
 #endif
 protected:
     bool event(QEvent *) override;
+#  if QT_VERSION < QT_VERSION_CHECK(7, 0, 0)
     bool compressEvent(QEvent *, QObject *receiver, QPostEventList *) override;
+#  endif
 
     QGuiApplication(QGuiApplicationPrivate &p);
 

src/widgets/kernel/qapplication.cpp

@@ -782,7 +782,14 @@ QWidget *QApplication::widgetAt(const QPoint &p)
 /*!
     \internal
 */
+#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0)
 bool QApplication::compressEvent(QEvent *event, QObject *receiver, QPostEventList *postedEvents)
+{
+    return d_func()->compressEvent(event, receiver, postedEvents);
+}
+#endif
+
+bool QApplicationPrivate::compressEvent(QEvent *event, QObject *receiver, QPostEventList *postedEvents)
 {
     // Only compress the following events:
     const QEvent::Type type = event->type();
@@ -795,7 +802,7 @@ bool QApplication::compressEvent(QEvent *event, QObject *receiver, QPostEventLis
     case QEvent::LanguageChange:
         break;
     default:
-        return QGuiApplication::compressEvent(event, receiver, postedEvents);
+        return QGuiApplicationPrivate::compressEvent(event, receiver, postedEvents);
     }
 
     for (const auto &postedEvent : std::as_const(*postedEvents)) {

src/widgets/kernel/qapplication.h

@@ -140,7 +140,9 @@ public Q_SLOTS:
 
 protected:
     bool event(QEvent *) override;
+#  if QT_VERSION < QT_VERSION_CHECK(7, 0, 0)
     bool compressEvent(QEvent *, QObject *receiver, QPostEventList *) override;
+#  endif
 
 private:
     Q_DISABLE_COPY(QApplication)

src/widgets/kernel/qapplication_p.h

@@ -75,6 +75,7 @@ class Q_WIDGETS_EXPORT QApplicationPrivate : public QGuiApplicationPrivate
     static void dispatchEnterLeave(QWidget *enter, QWidget *leave, const QPointF &globalPosF);
     static QWidget *desktop();
     void notifyWindowIconChanged() override;
+    bool compressEvent(QEvent *event, QObject *receiver, QPostEventList *postedEvents) final;
 
 #ifndef QT_NO_ACTION
     QActionPrivate *createActionPrivate() const override;

src/widgets/kernel/qwidget_p.h

@@ -83,6 +83,7 @@ class QUpdateLaterEvent : public QEvent
 
 protected:
     friend class QApplication;
+    friend class QApplicationPrivate;
     QRegion m_region;
 };