Move.

coupler/opc-ua-server/common.h

 /* This work is licensed under a Creative Commons CCZero 1.0 Universal License.
  * See http://creativecommons.org/publicdomain/zero/1.0/for more information. */
+#define countof(a) (sizeof(a)/sizeof(*(a)))
 
 #include <open62541/server.h>
 

coupler/opc-ua-server/server.c

@@ -34,8 +34,6 @@
 #include <open62541/plugin/pubsub_ethernet.h>
 #include <open62541/plugin/pubsub_udp.h>
 
-#define countof(a) (sizeof(a)/sizeof(*(a)))
-
 // global Id of coupler
 static int COUPLER_ID = 0;