--- /dev/null
+/* Copyright (c) 2016. The SimGrid Team. All rights reserved. */
+
+/* This program is free software; you can redistribute it and/or modify it
+ * under the terms of the license (GNU LGPL) which comes with this package. */
+
+#ifndef SIMGRID_S4U_FORWARD_HPP
+#define SIMGRID_S4U_FORWARD_HPP
+
+namespace simgrid {
+namespace s4u {
+
+class Async;
+class Comm;
+class Engine;
+class Host;
+class Mailbox;
+class Storage;
+
+}
+}
+
+#endif