range-diff: use parse_options() instead of diff_opt_parse()

Diff's internal option parsing is now done with 'struct option', which
makes it possible to combine all diff options to range-diff and parse
everything all at once. Parsing code becomes simpler, and we get a
looong 'git range-diff -h'

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/range-diff.c

@@ -16,42 +16,27 @@ int cmd_range_diff(int argc, const char **argv, const char *prefix)
 	int creation_factor = RANGE_DIFF_CREATION_FACTOR_DEFAULT;
 	struct diff_options diffopt = { NULL };
 	int simple_color = -1;
-	struct option options[] = {
+	struct option range_diff_options[] = {
 		OPT_INTEGER(0, "creation-factor", &creation_factor,
 			    N_("Percentage by which creation is weighted")),
 		OPT_BOOL(0, "no-dual-color", &simple_color,
 			    N_("use simple diff colors")),
 		OPT_END()
 	};
-	int i, j, res = 0;
+	struct option *options;
+	int res = 0;
 	struct strbuf range1 = STRBUF_INIT, range2 = STRBUF_INIT;
 
 	git_config(git_diff_ui_config, NULL);
 
 	repo_diff_setup(the_repository, &diffopt);
 
+	options = parse_options_concat(range_diff_options, diffopt.parseopts);
 	argc = parse_options(argc, argv, NULL, options,
-			     builtin_range_diff_usage, PARSE_OPT_KEEP_UNKNOWN |
-			     PARSE_OPT_KEEP_DASHDASH | PARSE_OPT_KEEP_ARGV0);
-
-	for (i = j = 1; i < argc && strcmp("--", argv[i]); ) {
-		int c = diff_opt_parse(&diffopt, argv + i, argc - i, prefix);
-
-		if (!c)
-			argv[j++] = argv[i++];
-		else
-			i += c;
-	}
-	while (i < argc)
-		argv[j++] = argv[i++];
-	argc = j;
-	diff_setup_done(&diffopt);
-
-	/* Make sure that there are no unparsed options */
-	argc = parse_options(argc, argv, NULL,
-			     options + ARRAY_SIZE(options) - 1, /* OPT_END */
 			     builtin_range_diff_usage, 0);
 
+	diff_setup_done(&diffopt);
+
 	/* force color when --dual-color was used */
 	if (!simple_color)
 		diffopt.use_color = 1;
@@ -90,6 +75,7 @@ int cmd_range_diff(int argc, const char **argv, const char *prefix)
 		error(_("need two commit ranges"));
 		usage_with_options(builtin_range_diff_usage, options);
 	}
+	FREE_AND_NULL(options);
 
 	res = show_range_diff(range1.buf, range2.buf, creation_factor,
 			      simple_color < 1, &diffopt);