From 09220190683cf9170953b09e82759d442dde95c0 Mon Sep 17 00:00:00 2001
From: BVK Chaitanya <bvk.groups@gmail.com>
Date: Mon, 5 Apr 2010 21:08:30 +0530
Subject: [PATCH] added flex version check in configure.ac

---
 configure.ac | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/configure.ac b/configure.ac
index 50edf645c..157a6114c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -170,11 +170,6 @@ if test "x$CMP" = x; then
   AC_MSG_ERROR([cmp is not found])
 fi
 
-AC_CHECK_PROGS([LEX], [flex])
-if test "x$LEX" = x; then
-  AC_MSG_ERROR([flex is not found])
-fi
-
 AC_CHECK_PROGS([YACC], [bison])
 if test "x$YACC" = x; then
   AC_MSG_ERROR([bison is not found])
@@ -188,10 +183,23 @@ for file in /usr/src/unifont.bdf /usr/share/fonts/X11/misc/unifont.pcf.gz /usr/s
 done
 
 AC_PROG_INSTALL
+AC_PROG_SED
 AC_PROG_AWK
+AC_PROG_LEX
 AC_PROG_MAKE_SET
 AC_PROG_MKDIR_P
 
+if test "x$LEX" = x; then
+  AC_MSG_ERROR([flex is not found])
+else
+  version=`$LEX --version 2>/dev/null | $SED -e 's/flex //' | $AWK 'BEGIN { FS = "."; } { printf "%d", ($1 * 100 + $2) * 100 + $3;}'`
+  if test -n "$version" -a test "$version" -ge 205035; then
+    :
+  else
+    AC_MSG_ERROR([flex is too old. GRUB requires 2.5.35 or above])
+  fi
+fi
+
 # These are not a "must".
 AC_PATH_PROG(RUBY, ruby)
 AC_PATH_PROG(MAKEINFO, makeinfo)