-if test ! -f "$srcdir/src/lib/lttng-ctl/filter/filter-lexer.c"; then
- if test x"$LEX" != "xflex"; then
- 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]])
+# export bison condition
+AM_CONDITIONAL([HAVE_BISON], [test "x$have_bison" = "xyes"])
+
+# check for flex
+have_flex=yes
+
+AS_IF([test "x$LEX" != "xflex"], [have_flex=no])
+AC_PATH_PROG([FLEX], [flex])
+AX_PROG_FLEX_VERSION([2.5.35], [], [have_flex=no])
+
+AS_IF([test "x$have_flex" = "xno"], [
+ AS_IF([test "x$in_git_repo" = "xyes"], [
+ AC_MSG_ERROR([Flex >= 2.5.35 is required when building from the Git repository.])
+ ], [
+ AC_MSG_WARN([
+Missing Flex >= 2.5.35. Note that the lexer files are already built in
+this distribution tarball, so Flex is only needed if you intend to
+modify their sources.
+ ])