--- /dev/null
+# ===========================================================================
+# http://www.gnu.org/software/autoconf-archive/ax_prog_flex_version.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+# AX_PROG_FLEX_VERSION([VERSION],[ACTION-IF-TRUE],[ACTION-IF-FALSE])
+#
+# DESCRIPTION
+#
+# Makes sure that flex version is greater or equal to the version
+# indicated. If true the shell commands in ACTION-IF-TRUE are executed. If
+# not the shell commands in commands in ACTION-IF-TRUE are executed. If
+# not the shell commands in ACTION-IF-FALSE are run. Note if $FLEX is not
+# set (for example by running AC_CHECK_PROG or AC_PATH_PROG) the macro
+# will fail.
+#
+# Example:
+#
+# AC_PATH_PROG([FLEX],[flex])
+# AX_PROG_FLEX_VERSION([2.5.39],[ ... ],[ ... ])
+#
+# This will check to make sure that the flex you have is at least version
+# 2.5.39 or greater.
+#
+# NOTE: This macro uses the $FLEX variable to perform the check.
+#
+# LICENSE
+#
+# Copyright (c) 2015 Jonathan Rajotte-Julien <jonathan.rajotte-julien@efficios.com>
+#
+# Copying and distribution of this file, with or without modification, are
+# permitted in any medium without royalty provided the copyright notice
+# and this notice are preserved. This file is offered as-is, without any
+# warranty.
+
+#serial 1
+
+AC_DEFUN([AX_PROG_FLEX_VERSION],[
+ AC_REQUIRE([AC_PROG_SED])
+ AC_REQUIRE([AC_PROG_GREP])
+
+ AS_IF([test -n "$FLEX"],[
+ ax_flex_version="$1"
+
+ AC_MSG_CHECKING([for flex version])
+ changequote(<<,>>)
+ flex_version=`$FLEX --version 2>&1 \
+ | $SED -n -e '/flex /b inspect
+b
+: inspect
+s/.* (\{0,1\}\([0-9]*\.[0-9]*\.[0-9]*\))\{0,1\}.*/\1/;p'`
+ changequote([,])
+ AC_MSG_RESULT($flex_version)
+
+ AC_SUBST([FLEX_VERSION],[$flex_version])
+
+ AX_COMPARE_VERSION([$flex_version],[ge],[$ax_flex_version],[
+ :
+ $2
+ ],[
+ :
+ $3
+ ])
+ ],[
+ AC_MSG_WARN([could not find flex])
+ $3
+ ])
+])
AC_MSG_ERROR([[flex not found and is required when building from git.
Please install flex]])
fi
+ AC_PATH_PROG([FLEX],[flex])
+ AX_PROG_FLEX_VERSION([2.5.35], [],[
+ AC_MSG_ERROR([[Flex >= 2.5.35 is required when building from git]])
+ ])
fi
CFLAGS="-Wall $CFLAGS -g -fno-strict-aliasing"