From bcf29faf2e5cab7ab836ff5147d2fd3a73ffc426 Mon Sep 17 00:00:00 2001
From: Ivan Maidanski <ivmai@mail.ru>
Date: Tue, 13 Dec 2011 10:36:24 +0400
Subject: [PATCH] configure: Do not pass '-Wextra' option to GCC if unsupported

* configure.ac (WEXTRA): New variable (set to "-Wextra" if the latter
is supported by GCC, otherwise to "-W").
* configure.ac (CFLAGS): Use WEXTRA variable.
---
 configure.ac | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 4a9fb7e..fe0fb20 100644
--- a/configure.ac
+++ b/configure.ac
@@ -38,8 +38,16 @@ if test "$GCC" = yes; then
       PICFLAG=-fPIC
       ;;
   esac
+
   # Output all warnings.
-  CFLAGS="-Wall -Wextra $CFLAGS"
+  AC_MSG_CHECKING(for gcc -Wextra)
+  old_CFLAGS="$CFLAGS"
+  CFLAGS="-Wextra $CFLAGS"
+  AC_TRY_COMPILE([],[], [ac_cv_cc_wextra=yes], [ac_cv_cc_wextra=no])
+  CFLAGS="$old_CFLAGS"
+  AC_MSG_RESULT($ac_cv_cc_wextra)
+  AS_IF([test "$ac_cv_cc_wextra" = yes], [WEXTRA="-Wextra"], [WEXTRA="-W"])
+  CFLAGS="-Wall $WEXTRA $CFLAGS"
 else
   case "$host" in
     *-*-hpux*)
-- 
2.50.1