parse-options: add parse_opt_unknown_cb()

Add a new callback function, parse_opt_unknown_cb(), which returns -2 to
indicate that the corresponding option is unknown. This can be used to
add "-h" documentation for an option that will be handled externally to
parse_options().

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/parse-options-cb.c b/parse-options-cb.c
index ba5acf3..9f2f9b3 100644
--- a/parse-options-cb.c
+++ b/parse-options-cb.c
@@ -154,6 +154,18 @@ int parse_opt_noop_cb(const struct option *opt, const char *arg, int unset)
 }
 
 /**
+ * Report that the option is unknown, so that other code can handle
+ * it. This can be used as a callback together with
+ * OPTION_LOWLEVEL_CALLBACK to allow an option to be documented in the
+ * "-h" output even if it's not being handled directly by
+ * parse_options().
+ */
+int parse_opt_unknown_cb(const struct option *opt, const char *arg, int unset)
+{
+	return -2;
+}
+
+/**
  * Recreates the command-line option in the strbuf.
  */
 static int recreate_opt(struct strbuf *sb, const struct option *opt,