reflog-walk: always make HEAD@{0} show indexed selectors

When we are showing reflog selectors during a walk, we infer
from context whether the user wanted to see the index in
each selector, or the reflog date. The current rules are:

  1. if the user asked for an explicit date format in the
     output, show the date

  2. if the user asked for ref@{now}, show the date

  3. if neither is true, show the index

However,  if we see "ref@{0}", that should be a strong clue
that the user wants to see the counted version. In fact, it
should be much stronger than the date format in (1). The
user may have been setting the date format to use in another
part of the output (e.g., in --format="%gd (%ad)", they may
have wanted to influence the author date).

This patch flips the rules to:

  1. if the user asked for ref@{0}, always show the index

  2. if the user asked for ref@{now}, always show the date

  3. otherwise, we have just "ref"; show them counted by
     default, but respect the presence of "--date" as a clue
     that the user wanted them date-based

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 10 insertions, 1 deletions

diff --git a/reflog-walk.c b/reflog-walk.c
index 80bffb0a00..b84e80f2ca 100644
--- a/reflog-walk.c
+++ b/reflog-walk.c
@@ -272,7 +272,8 @@ void get_reflog_selector(struct strbuf *sb,
 	}
 
 	strbuf_addf(sb, "%s@{", printed_ref);
-	if (commit_reflog->selector == SELECTOR_DATE || dmode) {
+	if (commit_reflog->selector == SELECTOR_DATE ||
+	    (commit_reflog->selector == SELECTOR_NONE && dmode)) {
 		info = &commit_reflog->reflogs->items[commit_reflog->recno+1];
 		strbuf_addstr(sb, show_date(info->timestamp, info->tz, dmode));
 	} else {
diff --git a/t/t1411-reflog-show.sh b/t/t1411-reflog-show.sh
index 88247f874e..7d9b5e33df 100755
--- a/t/t1411-reflog-show.sh
+++ b/t/t1411-reflog-show.sh
@@ -127,6 +127,14 @@ test_expect_success 'log.date does not invoke "--date" magic (format=%gd)' '
 	test_cmp expect actual
 '
 
+cat >expect <<'EOF'
+HEAD@{0}
+EOF
+test_expect_success '--date magic does not override explicit @{0} syntax' '
+	git log -g -1 --format=%gd --date=raw HEAD@{0} >actual &&
+	test_cmp expect actual
+'
+
 : >expect
 test_expect_success 'empty reflog file' '
 	git branch empty &&