From dc7d7b0c51e05e2da15bb9ec33cf9c5385e4f3fc Mon Sep 17 00:00:00 2001
From: ru <ru@FreeBSD.org>
Date: Tue, 30 May 2006 19:18:01 +0000
Subject: [PATCH] Enable -Wundef warnings for kernel/module compiles.  From
 cpp.info:

`-Wundef'
     Warn whenever an identifier which is not a macro is encountered in
     an `#if' directive, outside of `defined'.  Such identifiers are
     replaced with zero.
---
 sys/conf/kern.mk | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sys/conf/kern.mk b/sys/conf/kern.mk
index 54c5905f0a6f..cea8af14a4a3 100644
--- a/sys/conf/kern.mk
+++ b/sys/conf/kern.mk
@@ -12,7 +12,10 @@ CWARNFLAGS=
 .else
 CWARNFLAGS?=	-Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes \
 		-Wmissing-prototypes -Wpointer-arith -Winline -Wcast-qual \
-		-fformat-extensions -std=c99
+		${_wundef} -fformat-extensions -std=c99
+.if !defined(NO_UNDEF)
+_wundef=	-Wundef
+.endif
 .endif
 #
 # The following flags are next up for working on: