diff-parseopt: convert --no-prefix

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

diff.c

@@ -5022,6 +5022,18 @@ static int diff_opt_line_prefix(const struct option *opt,
 	return 0;
 }
 
+static int diff_opt_no_prefix(const struct option *opt,
+			      const char *optarg, int unset)
+{
+	struct diff_options *options = opt->value;
+
+	BUG_ON_OPT_NEG(unset);
+	BUG_ON_OPT_ARG(optarg);
+	options->a_prefix = "";
+	options->b_prefix = "";
+	return 0;
+}
+
 static enum parse_opt_result diff_opt_output(struct parse_opt_ctx_t *ctx,
 					     const struct option *opt,
 					     const char *arg, int unset)
@@ -5276,6 +5288,9 @@ static void prep_parse_options(struct diff_options *options)
 		OPT_CALLBACK_F(0, "line-prefix", options, N_("<prefix>"),
 			       N_("prepend an additional prefix to every line of output"),
 			       PARSE_OPT_NONEG, diff_opt_line_prefix),
+		OPT_CALLBACK_F(0, "no-prefix", options, NULL,
+			       N_("do not show any source or destination prefix"),
+			       PARSE_OPT_NONEG | PARSE_OPT_NOARG, diff_opt_no_prefix),
 		OPT_CALLBACK_F(0, "output-indicator-new",
 			       &options->output_indicators[OUTPUT_INDICATOR_NEW],
 			       N_("<char>"),
@@ -5468,8 +5483,6 @@ int diff_opt_parse(struct diff_options *options,
 	}
 
 	/* misc options */
-	else if (!strcmp(arg, "--no-prefix"))
-		options->a_prefix = options->b_prefix = "";
 	else if (opt_arg(arg, '\0', "inter-hunk-context",
 			 &options->interhunkcontext))
 		;