AC_PROG_LIBTOOL
AC_PATH_PROG(LEX, flex)
-AC_SUBST(FLEX_PATH)
-
+#
+# Check whether Flex supports -R, so we can build reentrant scanners.
+#
+AC_MSG_CHECKING(whether Flex can generate reentrant scanners)
+if flex -R -t <<EOF >/dev/null 2>&1
+%%
+%%
+EOF
+then
+ AC_MSG_RESULT(yes)
+ AC_DEFINE(FLEX_REENTRANT_SCANNERS, 1, [Define if Flex can generate reentrant scanners])
+else
+ AC_MSG_RESULT(no)
+fi
#
# Try to add some additional gcc checks to CFLAGS