Merge 5.5 into 5.5.0

Change-Id: I27921a25a0fc56afb5429e40fc1e9b4b9a645a9a

2 files changed, 10 insertions, 5 deletions

diff --git a/src/corelib/kernel/qmetatype.h b/src/corelib/kernel/qmetatype.h
index b854dc16fd..1b214e9f74 100644
--- a/src/corelib/kernel/qmetatype.h
+++ b/src/corelib/kernel/qmetatype.h
@@ -1357,12 +1357,16 @@ namespace QtPrivate
         enum { Value = sizeof(checkType(static_cast<T*>(0))) == sizeof(yes_type) };
     };
 
+    template<typename T, typename Enable = void>
+    struct IsGadgetHelper { enum { Value = false }; };
+
     template<typename T>
-    struct IsGadgetHelper
+    struct IsGadgetHelper<T, typename T::QtGadgetHelper>
     {
-        template<typename X> static typename X::QtGadgetHelper *checkType(X*);
-        static char checkType(void*);
-        enum { Value = sizeof(checkType(static_cast<T*>(0))) == sizeof(void*)  };
+        template <typename X>
+        static char checkType(void (X::*)());
+        static void *checkType(void (T::*)());
+        enum { Value =  sizeof(checkType(&T::qt_check_for_QGADGET_macro)) == sizeof(void *) };
     };
 
 
@@ -1769,7 +1773,7 @@ template <typename T>
 struct QMetaTypeIdQObject<T, QMetaType::IsGadget>
 {
     enum {
-        Defined = 1
+        Defined = QtPrivate::is_default_constructible<T>::value
     };
 
     static int qt_metatype_id()
diff --git a/src/corelib/kernel/qobjectdefs.h b/src/corelib/kernel/qobjectdefs.h
index 31e8a670e9..4d01264906 100644
--- a/src/corelib/kernel/qobjectdefs.h
+++ b/src/corelib/kernel/qobjectdefs.h
@@ -172,6 +172,7 @@ private: \
 #define Q_GADGET \
 public: \
     static const QMetaObject staticMetaObject; \
+    void qt_check_for_QGADGET_macro(); \
     typedef void QtGadgetHelper; \
 private: \
     Q_DECL_HIDDEN_STATIC_METACALL static void qt_static_metacall(QObject *, QMetaObject::Call, int, void **);