Make the signal argument in Q_OBJECT_BINDABLE_PROPERTY optional

The intention was always that you can define properties that do
not require a changed signal. But having to explicitly pass
a nullptr as signal parameter into the macro is ugly, so
use the cool QT_OVERLOADED_MACRO to make it optional.

Change-Id: I0ce366d043850f983c968d73c544d89933c48df9
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
(cherry picked from commit cb39ea05810bc207100018589da658a0cce98edb)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

2 files changed, 15 insertions, 2 deletions

diff --git a/src/corelib/kernel/qproperty.cpp b/src/corelib/kernel/qproperty.cpp
index e9256c7b42..27e2de7c4f 100644
--- a/src/corelib/kernel/qproperty.cpp
+++ b/src/corelib/kernel/qproperty.cpp
@@ -952,6 +952,9 @@ QString QPropertyBindingError::description() const
         Q_OBJECT_BINDABLE_PROPERTY(MyClass, int, xProp, &MyClass::xChanged)
     };
   \endcode
+
+  If the property does not need a changed notification, you can leave out the "NOFITY xChanged" in the Q_PROPERTY macro as well as the last argument
+  of the Q_OBJECT_BINDABLE_PROPERTY macro.
 */
 
 /*!
diff --git a/src/corelib/kernel/qproperty.h b/src/corelib/kernel/qproperty.h
index a533f424e8..b6653c0411 100644
--- a/src/corelib/kernel/qproperty.h
+++ b/src/corelib/kernel/qproperty.h
@@ -1013,13 +1013,23 @@ private:
     }
 };
 
-#define Q_OBJECT_BINDABLE_PROPERTY(Class, Type, name,  ...) \
+#define Q_OBJECT_BINDABLE_PROPERTY3(Class, Type, name) \
     static constexpr size_t _qt_property_##name##_offset() { \
         QT_WARNING_PUSH QT_WARNING_DISABLE_INVALID_OFFSETOF \
         return offsetof(Class, name); \
         QT_WARNING_POP \
     } \
-    QObjectBindableProperty<Class, Type, Class::_qt_property_##name##_offset, __VA_ARGS__> name;
+    QObjectBindableProperty<Class, Type, Class::_qt_property_##name##_offset, nullptr> name;
+
+#define Q_OBJECT_BINDABLE_PROPERTY4(Class, Type, name, Signal) \
+    static constexpr size_t _qt_property_##name##_offset() { \
+        QT_WARNING_PUSH QT_WARNING_DISABLE_INVALID_OFFSETOF \
+        return offsetof(Class, name); \
+        QT_WARNING_POP \
+    } \
+    QObjectBindableProperty<Class, Type, Class::_qt_property_##name##_offset, Signal> name;
+
+#define Q_OBJECT_BINDABLE_PROPERTY(...) QT_OVERLOADED_MACRO(Q_OBJECT_BINDABLE_PROPERTY, __VA_ARGS__)
 
 template<typename Class, typename T, auto Offset, auto Getter>
 class QObjectComputedProperty : public QUntypedPropertyData