QObject::dumpObject*: add const overloads

They don't modify "this", so they should be const. Mark
the existing non-const overloads for removal in Qt 6.

[ChangeLog][QtCore][QObject] QObject::dumpObjectInfo and
QObject::dumpObjectTree now have const overloads.

Change-Id: If9fb15692d2d1536930f86d043d688236d4b778a
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/kernel/qobject.cpp

@@ -3941,7 +3941,7 @@ QList<QByteArray> QObject::dynamicPropertyNames() const
   QObject debugging output routines.
  *****************************************************************************/
 
-static void dumpRecursive(int level, QObject *object)
+static void dumpRecursive(int level, const QObject *object)
 {
     if (object) {
         QByteArray buf;
@@ -3974,17 +3974,36 @@ static void dumpRecursive(int level, QObject *object)
 }
 
 /*!
+    \overload
+    \obsolete
+
     Dumps a tree of children to the debug output.
 
     \sa dumpObjectInfo()
 */
 
 void QObject::dumpObjectTree()
+{
+    const_cast<const QObject *>(this)->dumpObjectTree();
+}
+
+/*!
+    Dumps a tree of children to the debug output.
+
+    \note before Qt 5.9, this function was not const.
+
+    \sa dumpObjectInfo()
+*/
+
+void QObject::dumpObjectTree() const
 {
     dumpRecursive(0, this);
 }
 
 /*!
+    \overload
+    \obsolete
+
     Dumps information about signal connections, etc. for this object
     to the debug output.
 
@@ -3992,11 +4011,25 @@ void QObject::dumpObjectTree()
 */
 
 void QObject::dumpObjectInfo()
+{
+    const_cast<const QObject *>(this)->dumpObjectInfo();
+}
+
+/*!
+    Dumps information about signal connections, etc. for this object
+    to the debug output.
+
+    \note before Qt 5.9, this function was not const.
+
+    \sa dumpObjectTree()
+*/
+
+void QObject::dumpObjectInfo() const
 {
     qDebug("OBJECT %s::%s", metaObject()->className(),
            objectName().isEmpty() ? "unnamed" : objectName().toLocal8Bit().data());
 
-    Q_D(QObject);
+    Q_D(const QObject);
     QMutexLocker locker(signalSlotLock(this));
 
     // first, look for connections where this object is the sender

src/corelib/kernel/qobject.h

@@ -375,8 +375,12 @@ public:
 #endif //Q_QDOC
 
 
-    void dumpObjectTree();
-    void dumpObjectInfo();
+#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
+    void dumpObjectTree(); // ### Qt 6: remove
+    void dumpObjectInfo(); // ### Qt 6: remove
+#endif
+    void dumpObjectTree() const;
+    void dumpObjectInfo() const;
 
 #ifndef QT_NO_PROPERTIES
     bool setProperty(const char *name, const QVariant &value);