From 17653702c753daa786698b4cdd67084472737d95 Mon Sep 17 00:00:00 2001
From: David Fuhrmann <dfuhrmann@videolan.org>
Date: Fri, 10 Oct 2014 11:47:10 +0200
Subject: [PATCH] m4: fix detection of supported "-Wxxx" flags with clang

Clang does not fail, but only prints a warning by default for unknown
-W options.
---
 m4/flags.m4 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/m4/flags.m4 b/m4/flags.m4
index 920fd45bdb..7dc19b7b64 100644
--- a/m4/flags.m4
+++ b/m4/flags.m4
@@ -13,7 +13,7 @@ AC_DEFUN([RDC_PROG_CC_FLAGS_IFELSE],
   CFLAGS_save="${CFLAGS}"
   as_ac_var=`echo "ac_cv_prog_cc_flags_$1" | $as_tr_sh`
   AC_CACHE_CHECK([if $CC accepts $1], [$as_ac_var], [
-    CFLAGS="${CFLAGS} $1"
+    CFLAGS="${CFLAGS} -Werror $1"
     AC_COMPILE_IFELSE([AC_LANG_PROGRAM()], [
       eval "$as_ac_var=yes"
     ],[