This is one of results of last duplicate prototype sweep - ip_mforward()
used to be defined in both <netinet/ip_var.h> and <netinet/ip_mroute.h>.
Now it's only in <netinet/ip_mroute.h>, but that header has not been
included by ip_input.c.

This should help (I've already fixed the version in tree):

Index: ip_input.c
===================================================================
RCS file: /cvsroot/syssrc/sys/netinet/ip_input.c,v
retrieving revision 1.109
retrieving revision 1.110
diff -u -p -r1.109 -r1.110
--- ip_input.c  2000/03/30 13:24:59     1.109
+++ ip_input.c  2000/03/31 08:34:20     1.110
@@ -134,6 +134,7 @@
 #include <netinet/in_pcb.h>
 #include <netinet/in_var.h>
 #include <netinet/ip_var.h>
+#include <netinet/ip_mroute.h>
 #include <netinet/ip_icmp.h>
 /* just for gif_ttl */
 #include <netinet/in_gif.h>


Chan Yiu Wah wrote:
> cc  -O2 -Werror -Wall -Wmissing-prototypes -Wstrict-prototypes
> -Wpointer-arith -Wno-main -I. -I../../../../arch -I../../../.. -nostdinc
> -I../../../../../crypto-intl/sys -I../../../../../gnu/sys -DLKM
> -DDIAGNOSTIC -DEXT2FS_SYSTEM_FLAGS -DIPSEC_DEBUG -DMAXUSERS=32 -D_KERNEL
> -Di386  -c ../../../../netinet/ip_input.c
> cc1: warnings being treated as errors
> ../../../../netinet/ip_input.c: In function `ip_input':
> ../../../../netinet/ip_input.c:558: warning: implicit declaration of
> function `ip_mforward'
> *** Error code 1
> 
> Stop.
> 
> Anyone know how to fix it ? Thanks.
> 
> Clarence