--- OLD/xc/programs/Xserver/include/os.h	Thu Jan  1 00:00:00 1970
+++ NEW/xc/programs/Xserver/include/os.h	Thu Jan  1 00:00:00 1970
@@ -423,7 +423,7 @@
     char* /*f*/,
     ...
 #endif
-);
+) __attribute__((__noreturn__));
 
 extern void ErrorF(
 #if NeedVarargsPrototypes