Use Q_STATIC_ASSERT to report error about missing Q_OBJECT

Q_STATIC_ASSERT gives better error with C++11 enabled.

Aslo the qt_check_for_QOBJECT_macro had warning on some compiler since
it used null reference

Change-Id: Ic6115da800064b00c50a5762f0b79f5f656bf750
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 18 insertions, 8 deletions

diff --git a/src/corelib/kernel/qobject.h b/src/corelib/kernel/qobject.h
index aaa09fac50..9d49bf26d2 100644
--- a/src/corelib/kernel/qobject.h
+++ b/src/corelib/kernel/qobject.h
@@ -217,7 +217,9 @@ public:
     {
         typedef QtPrivate::FunctionPointer<Func1> SignalType;
         typedef QtPrivate::FunctionPointer<Func2> SlotType;
-        reinterpret_cast<typename SignalType::Object *>(0)->qt_check_for_QOBJECT_macro(*reinterpret_cast<typename SignalType::Object *>(0));
+
+        Q_STATIC_ASSERT_X(QtPrivate::HasQ_OBJECT_Macro<typename SignalType::Object>::Value,
+                          "No Q_OBJECT in the class with the signal");
 
         //compilation error if the arguments does not match.
         Q_STATIC_ASSERT_X(int(SignalType::ArgumentCount) >= int(SlotType::ArgumentCount),
@@ -246,6 +248,9 @@ public:
         typedef QtPrivate::FunctionPointer<Func1> SignalType;
         typedef QtPrivate::FunctionPointer<Func2> SlotType;
 
+        Q_STATIC_ASSERT_X(QtPrivate::HasQ_OBJECT_Macro<typename SignalType::Object>::Value,
+                          "No Q_OBJECT in the class with the signal");
+
         //compilation error if the arguments does not match.
         Q_STATIC_ASSERT_X(int(SignalType::ArgumentCount) >= int(SlotType::ArgumentCount),
                           "The slot requires more arguments than the signal provides.");
@@ -307,6 +312,9 @@ public:
         Q_STATIC_ASSERT_X((QtPrivate::AreArgumentsCompatible<SlotReturnType, typename SignalType::ReturnType>::value),
                           "Return type of the slot is not compatible with the return type of the signal.");
 
+        Q_STATIC_ASSERT_X(QtPrivate::HasQ_OBJECT_Macro<typename SignalType::Object>::Value,
+                          "No Q_OBJECT in the class with the signal");
+
         return connectImpl(sender, reinterpret_cast<void **>(&signal), sender, 0,
                            new QtPrivate::QFunctorSlotObject<Func2, SlotArgumentCount,
                                 typename QtPrivate::List_Left<typename SignalType::Arguments, SlotArgumentCount>::Value,
@@ -335,7 +343,9 @@ public:
     {
         typedef QtPrivate::FunctionPointer<Func1> SignalType;
         typedef QtPrivate::FunctionPointer<Func2> SlotType;
-        reinterpret_cast<typename SignalType::Object *>(0)->qt_check_for_QOBJECT_macro(*reinterpret_cast<typename SignalType::Object *>(0));
+
+        Q_STATIC_ASSERT_X(QtPrivate::HasQ_OBJECT_Macro<typename SignalType::Object>::Value,
+                          "No Q_OBJECT in the class with the signal");
 
         //compilation error if the arguments does not match.
         Q_STATIC_ASSERT_X((QtPrivate::CheckCompatibleArguments<typename SignalType::Arguments, typename SlotType::Arguments>::value),
@@ -477,18 +487,18 @@ inline QT_DEPRECATED QList<T> qFindChildren(const QObject *o, const QRegExp &re)
 template <class T>
 inline T qobject_cast(QObject *object)
 {
-#if !defined(QT_NO_QOBJECT_CHECK)
-    reinterpret_cast<T>(object)->qt_check_for_QOBJECT_macro(*reinterpret_cast<T>(object));
-#endif
+    typedef typename QtPrivate::remove_cv<typename QtPrivate::remove_pointer<T>::type>::type ObjType;
+    Q_STATIC_ASSERT_X(QtPrivate::HasQ_OBJECT_Macro<ObjType>::Value,
+                    "qobject_cast require the type to have a Q_OBJECT macro");
     return static_cast<T>(reinterpret_cast<T>(object)->staticMetaObject.cast(object));
 }
 
 template <class T>
 inline T qobject_cast(const QObject *object)
 {
-#if !defined(QT_NO_QOBJECT_CHECK)
-    reinterpret_cast<T>(object)->qt_check_for_QOBJECT_macro(*reinterpret_cast<T>(const_cast<QObject *>(object)));
-#endif
+    typedef typename QtPrivate::remove_cv<typename QtPrivate::remove_pointer<T>::type>::type ObjType;
+    Q_STATIC_ASSERT_X(QtPrivate::HasQ_OBJECT_Macro<ObjType>::Value,
+                      "qobject_cast require the type to have a Q_OBJECT macro");
     return static_cast<T>(reinterpret_cast<T>(object)->staticMetaObject.cast(object));
 }