Revert "Properly implement qobject_cast for const pointers."

This commit added new symbols to the 4.7 branch after 4.7.0 was
frozen.

This reverts commit 0b0aa7603b27447a5abe55c55d0514bc56b35f9e.

3 files changed, 6 insertions, 21 deletions

diff --git a/src/corelib/kernel/qmetaobject.cpp b/src/corelib/kernel/qmetaobject.cpp
index 3b9b04a..9854e68 100644
--- a/src/corelib/kernel/qmetaobject.cpp
+++ b/src/corelib/kernel/qmetaobject.cpp
@@ -266,25 +266,7 @@ QObject *QMetaObject::cast(QObject *obj) const
         const QMetaObject *m = obj->metaObject();
         do {
             if (m == this)
-                return obj;
-        } while ((m = m->d.superdata));
-    }
-    return 0;
-}
-
-/*!
-    \internal
-
-    Returns \a obj if object \a obj inherits from this
-    meta-object; otherwise returns 0.
-*/
-const QObject *QMetaObject::cast(const QObject *obj) const
-{
-    if (obj) {
-        const QMetaObject *m = obj->metaObject();
-        do {
-            if (m == this)
-                return obj;
+                return const_cast<QObject*>(obj);
         } while ((m = m->d.superdata));
     }
     return 0;
diff --git a/src/corelib/kernel/qobject.h b/src/corelib/kernel/qobject.h
index b5c772e..d98d1f0 100644
--- a/src/corelib/kernel/qobject.h
+++ b/src/corelib/kernel/qobject.h
@@ -369,10 +369,14 @@ inline T qobject_cast(QObject *object)
 template <class T>
 inline T qobject_cast(const QObject *object)
 {
+    // this will cause a compilation error if T is not const
+    register T ptr = static_cast<T>(object);
+    Q_UNUSED(ptr);
+
 #if !defined(QT_NO_MEMBER_TEMPLATES) && !defined(QT_NO_QOBJECT_CHECK)
     reinterpret_cast<T>(0)->qt_check_for_QOBJECT_macro(*reinterpret_cast<T>(const_cast<QObject *>(object)));
 #endif
-    return static_cast<T>(reinterpret_cast<T>(0)->staticMetaObject.cast(object));
+    return static_cast<T>(const_cast<QObject *>(reinterpret_cast<T>(0)->staticMetaObject.cast(const_cast<QObject *>(object))));
 }
 
 
diff --git a/src/corelib/kernel/qobjectdefs.h b/src/corelib/kernel/qobjectdefs.h
index 0d045dc..555a1f5 100644
--- a/src/corelib/kernel/qobjectdefs.h
+++ b/src/corelib/kernel/qobjectdefs.h
@@ -298,7 +298,6 @@ struct Q_CORE_EXPORT QMetaObject
     const QMetaObject *superClass() const;
 
     QObject *cast(QObject *obj) const;
-    const QObject *cast(const QObject *obj) const;
 
 #ifndef QT_NO_TRANSLATION
     // ### Qt 4: Merge overloads