range-diff: relieve callers of low-level configuration burden

There are a number of very low-level configuration details which need to
be managed precisely to generate a proper range-diff. In particular,
'diff_options' output format, header suppression, indentation, and
dual-color mode must all be set appropriately to ensure proper behavior.

Handle these details locally in the libified range-diff back-end rather
than forcing each caller to have specialized knowledge of these
implementation details, and to avoid duplication as new callers are
added.

While at it, localize these tweaks to be active only while generating
the range-diff, so they don't clobber the caller-provided
'diff_options', which might be used beyond range-diff generation.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 4 insertions, 19 deletions

diff --git a/builtin/range-diff.c b/builtin/range-diff.c
index 006e7667263..cc06e86a721 100644
--- a/builtin/range-diff.c
+++ b/builtin/range-diff.c
@@ -11,11 +11,6 @@ N_("git range-diff [<options>] <base> <old-tip> <new-tip>"),
 NULL
 };
 
-static struct strbuf *output_prefix_cb(struct diff_options *opt, void *data)
-{
-	return data;
-}
-
 int cmd_range_diff(int argc, const char **argv, const char *prefix)
 {
 	int creation_factor = RANGE_DIFF_CREATION_FACTOR_DEFAULT;
@@ -29,17 +24,11 @@ int cmd_range_diff(int argc, const char **argv, const char *prefix)
 		OPT_END()
 	};
 	int i, j, res = 0;
-	struct strbuf four_spaces = STRBUF_INIT;
 	struct strbuf range1 = STRBUF_INIT, range2 = STRBUF_INIT;
 
 	git_config(git_diff_ui_config, NULL);
 
 	diff_setup(&diffopt);
-	diffopt.output_format = DIFF_FORMAT_PATCH;
-	diffopt.flags.suppress_diff_headers = 1;
-	diffopt.output_prefix = output_prefix_cb;
-	strbuf_addstr(&four_spaces, "    ");
-	diffopt.output_prefix_data = &four_spaces;
 
 	argc = parse_options(argc, argv, NULL, options,
 			     builtin_range_diff_usage, PARSE_OPT_KEEP_UNKNOWN |
@@ -63,12 +52,9 @@ int cmd_range_diff(int argc, const char **argv, const char *prefix)
 			     options + ARRAY_SIZE(options) - 1, /* OPT_END */
 			     builtin_range_diff_usage, 0);
 
-	if (simple_color < 1) {
-		if (!simple_color)
-			/* force color when --dual-color was used */
-			diffopt.use_color = 1;
-		diffopt.flags.dual_color_diffed_diffs = 1;
-	}
+	/* force color when --dual-color was used */
+	if (!simple_color)
+		diffopt.use_color = 1;
 
 	if (argc == 2) {
 		if (!strstr(argv[0], ".."))
@@ -106,11 +92,10 @@ int cmd_range_diff(int argc, const char **argv, const char *prefix)
 	}
 
 	res = show_range_diff(range1.buf, range2.buf, creation_factor,
-			      &diffopt);
+			      simple_color < 1, &diffopt);
 
 	strbuf_release(&range1);
 	strbuf_release(&range2);
-	strbuf_release(&four_spaces);
 
 	return res;
 }