From de05424ff692eb48a3c2ea574ec10ad5ea0e5bd0 Mon Sep 17 00:00:00 2001
From: Dirk Ziegelmeier <dirk@ziegelmeier.net>
Date: Fri, 10 Feb 2017 22:52:43 +0100
Subject: [PATCH] Fix build in IPv4 only case when source based routing is
 disabled

---
 src/core/udp.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/core/udp.c b/src/core/udp.c
index 25a04ade..4c52cbd8 100644
--- a/src/core/udp.c
+++ b/src/core/udp.c
@@ -515,6 +515,8 @@ udp_sendto_chksum(struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *dst_ip,
 #endif /* LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP */
   struct netif *netif;
   const ip_addr_t *src_ip_route;
+  
+  LWIP_UNUSED_ARG(src_ip_route); /* IPv4 only and no source based routing */
 
   if ((pcb == NULL) || (dst_ip == NULL) || !IP_ADDR_PCB_VERSION_MATCH(pcb, dst_ip)) {
     return ERR_VAL;