Use nullptr

messageviewer/src/viewer/pluginloader.h

@@ -112,7 +112,7 @@ public:
     {
         auto main_func = mainFunc(type, T_config::mainfunc);
         if (!main_func) {
-            return 0;
+            return nullptr;
         }
 
         // cast to a pointer to a function returning T*, call it and

messageviewer/src/viewer/viewer.cpp

@@ -502,7 +502,7 @@ QAbstractItemModel *Viewer::messageTreeModel() const
 #ifndef QT_NO_TREEVIEW
     return d_func()->mMimePartTree->mimePartModel();
 #else
-    return 0;
+    return nullptr;
 #endif
 }