pretty: avoid adding reset for %C(auto) if output is empty

We emit an escape sequence for resetting color and attribute for
%C(auto) to make sure automatic coloring is displayed as intended.
Stop doing that if the output strbuf is empty, i.e. when %C(auto)
appears at the start of the format string, because then there is no
need for a reset and we save a few bytes in the output.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/pretty.c b/pretty.c
index b86c5bb907..bad1bfb225 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1062,7 +1062,7 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 	case 'C':
 		if (starts_with(placeholder + 1, "(auto)")) {
 			c->auto_color = want_color(c->pretty_ctx->color);
-			if (c->auto_color)
+			if (c->auto_color && sb->len)
 				strbuf_addstr(sb, GIT_COLOR_RESET);
 			return 7; /* consumed 7 bytes, "C(auto)" */
 		} else {