parse-options: make resuming easier after PARSE_OPT_STOP_AT_NON_OPTION

Introduce a PARSE_OPT_NON_OPTION state, so parse_option_step()
callers can easily distinguish between non-options and other
reasons for option parsing termination (like "--").

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

parse-options.c

@@ -373,7 +373,7 @@ int parse_options_step(struct parse_opt_ctx_t *ctx,
 			if (parse_nodash_opt(ctx, arg, options) == 0)
 				continue;
 			if (ctx->flags & PARSE_OPT_STOP_AT_NON_OPTION)
-				break;
+				return PARSE_OPT_NON_OPTION;
 			ctx->out[ctx->cpidx++] = ctx->argv[0];
 			continue;
 		}
@@ -455,6 +455,7 @@ int parse_options(int argc, const char **argv, const char *prefix,
 	switch (parse_options_step(&ctx, options, usagestr)) {
 	case PARSE_OPT_HELP:
 		exit(129);
+	case PARSE_OPT_NON_OPTION:
 	case PARSE_OPT_DONE:
 		break;
 	default: /* PARSE_OPT_UNKNOWN */

parse-options.h

@@ -167,6 +167,7 @@ extern NORETURN void usage_msg_opt(const char *msg,
 enum {
 	PARSE_OPT_HELP = -1,
 	PARSE_OPT_DONE,
+	PARSE_OPT_NON_OPTION,
 	PARSE_OPT_UNKNOWN
 };