QtDBus: Use Q_NULLPTR instead of 0 in all public headers

This is in preparation of adding -Wzero-as-null-pointer-constant (or similar)
to the headers check.

Task-number: QTBUG-45291
Change-Id: If258b503c5ce335ecc22a5176d3e2b21aa7a278a
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/dbus/qdbusargument.h

@@ -147,7 +147,7 @@ QT_BEGIN_NAMESPACE
 
 template<typename T> inline T qdbus_cast(const QDBusArgument &arg
 #ifndef Q_QDOC
-, T * = 0
+, T * = Q_NULLPTR
 #endif
     )
 {
@@ -158,7 +158,7 @@ template<typename T> inline T qdbus_cast(const QDBusArgument &arg
 
 template<typename T> inline T qdbus_cast(const QVariant &v
 #ifndef Q_QDOC
-, T * = 0
+, T * = Q_NULLPTR
 #endif
     )
 {

src/dbus/qdbusinterface.h

@@ -52,7 +52,7 @@ private:
 public:
     QDBusInterface(const QString &service, const QString &path, const QString &interface = QString(),
                    const QDBusConnection &connection = QDBusConnection::sessionBus(),
-                   QObject *parent = 0);
+                   QObject *parent = Q_NULLPTR);
     ~QDBusInterface();
 
     virtual const QMetaObject *metaObject() const Q_DECL_OVERRIDE;

src/dbus/qdbuspendingcall.h

@@ -96,7 +96,7 @@ class Q_DBUS_EXPORT QDBusPendingCallWatcher: public QObject, public QDBusPending
 {
     Q_OBJECT
 public:
-    explicit QDBusPendingCallWatcher(const QDBusPendingCall &call, QObject *parent = 0);
+    explicit QDBusPendingCallWatcher(const QDBusPendingCall &call, QObject *parent = Q_NULLPTR);
     ~QDBusPendingCallWatcher();
 
 #ifdef Q_QDOC

src/dbus/qdbusreply.h

@@ -125,7 +125,7 @@ private:
 template<> inline QDBusReply<QVariant>&
 QDBusReply<QVariant>::operator=(const QDBusMessage &reply)
 {
-    void *null = 0;
+    void *null = Q_NULLPTR;
     QVariant data(qMetaTypeId<QDBusVariant>(), null);
     qDBusReplyFill(reply, m_error, data);
     m_data = qvariant_cast<QDBusVariant>(data).variant();

src/dbus/qdbusserver.h

@@ -50,8 +50,8 @@ class Q_DBUS_EXPORT QDBusServer: public QObject
 {
     Q_OBJECT
 public:
-    explicit QDBusServer(const QString &address, QObject *parent = 0);
-    explicit QDBusServer(QObject *parent = 0);
+    explicit QDBusServer(const QString &address, QObject *parent = Q_NULLPTR);
+    explicit QDBusServer(QObject *parent = Q_NULLPTR);
     virtual ~QDBusServer();
 
     bool isConnected() const;

src/dbus/qdbusservicewatcher.h

@@ -58,9 +58,9 @@ public:
     };
     Q_DECLARE_FLAGS(WatchMode, WatchModeFlag)
 
-    explicit QDBusServiceWatcher(QObject *parent = 0);
+    explicit QDBusServiceWatcher(QObject *parent = Q_NULLPTR);
     QDBusServiceWatcher(const QString &service, const QDBusConnection &connection,
-                        WatchMode watchMode = WatchForOwnerChange, QObject *parent = 0);
+                        WatchMode watchMode = WatchForOwnerChange, QObject *parent = Q_NULLPTR);
     ~QDBusServiceWatcher();
 
     QStringList watchedServices() const;

src/dbus/qdbusvirtualobject.h

@@ -51,7 +51,7 @@ class Q_DBUS_EXPORT QDBusVirtualObject : public QObject
 {
     Q_OBJECT
 public:
-    explicit QDBusVirtualObject(QObject *parent = 0);
+    explicit QDBusVirtualObject(QObject *parent = Q_NULLPTR);
     virtual ~QDBusVirtualObject();
 
     virtual QString introspect(const QString &path) const = 0;