log: respect date_mode_explicit with --format:%gd

When we show a reflog selector (e.g., via "git log -g"), we
perform some DWIM magic: while we normally show the entry's
index (e.g., HEAD@{1}), if the user has given us a date
with "--date", then we show a date-based select (e.g.,
HEAD@{yesterday}).

However, we don't want to trigger this magic if the
alternate date format we got was from the "log.date"
configuration; that is not sufficiently strong context for
us to invoke this particular magic. To fix this, commit
f4ea32f (improve reflog date/number heuristic, 2009-09-24)
introduced a "date_mode_explicit" flag in rev_info. This
flag is set only when we see a "--date" option on the
command line, and we a vanilla date to the reflog code if
the date was not explicit.

Later, commit 8f8f547 (Introduce new pretty formats %g[sdD]
for reflog information, 2009-10-19) added another way to
show selectors, and it did not respect the date_mode_explicit
flag from f4ea32f.

This patch propagates the date_mode_explicit flag to the
pretty-print code, which can then use it to pass the
appropriate date field to the reflog code. This brings the
behavior of "%gd" in line with the other formats, and means
that its output is independent of any user configuration.

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

builtin/rev-list.c

@@ -104,6 +104,7 @@ static void show_commit(struct commit *commit, void *data)
 		struct pretty_print_context ctx = {0};
 		ctx.abbrev = revs->abbrev;
 		ctx.date_mode = revs->date_mode;
+		ctx.date_mode_explicit = revs->date_mode_explicit;
 		ctx.fmt = revs->commit_format;
 		pretty_print_commit(&ctx, commit, &buf);
 		if (revs->graph) {

commit.h

@@ -82,6 +82,7 @@ struct pretty_print_context {
 	const char *after_subject;
 	int preserve_subject;
 	enum date_mode date_mode;
+	unsigned date_mode_explicit:1;
 	int need_8bit_cte;
 	int show_notes;
 	struct reflog_walk_info *reflog_info;

log-tree.c

@@ -511,6 +511,7 @@ void show_log(struct rev_info *opt)
 	if (ctx.need_8bit_cte >= 0)
 		ctx.need_8bit_cte = has_non_ascii(opt->add_signoff);
 	ctx.date_mode = opt->date_mode;
+	ctx.date_mode_explicit = opt->date_mode_explicit;
 	ctx.abbrev = opt->diffopt.abbrev;
 	ctx.after_subject = extra_headers;
 	ctx.preserve_subject = opt->preserve_subject;

pretty.c

@@ -956,7 +956,9 @@ static size_t format_commit_one(struct strbuf *sb, const char *placeholder,
 			if (c->pretty_ctx->reflog_info)
 				get_reflog_selector(sb,
 						    c->pretty_ctx->reflog_info,
-						    c->pretty_ctx->date_mode,
+						    c->pretty_ctx->date_mode_explicit ?
+						      c->pretty_ctx->date_mode :
+						      DATE_NORMAL,
 						    (placeholder[1] == 'd'));
 			return 2;
 		case 's':	/* reflog message */

t/t1411-reflog-show.sh

@@ -121,7 +121,7 @@ test_expect_success 'log.date does not invoke "--date" magic (oneline)' '
 cat >expect <<'EOF'
 HEAD@{0}
 EOF
-test_expect_failure 'log.date does not invoke "--date" magic (format=%gd)' '
+test_expect_success 'log.date does not invoke "--date" magic (format=%gd)' '
 	test_config log.date raw &&
 	git log -g -1 --format=%gd >actual &&
 	test_cmp expect actual