status: support --no-ahead-behind in long format

Teach long (normal) status format to respect the --no-ahead-behind
parameter and skip the possibly expensive ahead/behind computation
between the branch and the upstream.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/checkout.c

@@ -610,7 +610,7 @@ static void report_tracking(struct branch_info *new)
 	struct strbuf sb = STRBUF_INIT;
 	struct branch *branch = branch_get(new->name);
 
-	if (!format_tracking_info(branch, &sb))
+	if (!format_tracking_info(branch, &sb, AHEAD_BEHIND_FULL))
 		return;
 	fputs(sb.buf, stdout);
 	strbuf_release(&sb);

remote.c

@@ -2096,15 +2096,16 @@ int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs,
 /*
  * Return true when there is anything to report, otherwise false.
  */
-int format_tracking_info(struct branch *branch, struct strbuf *sb)
+int format_tracking_info(struct branch *branch, struct strbuf *sb,
+			 enum ahead_behind_flags abf)
 {
-	int ours, theirs;
+	int ours, theirs, sti;
 	const char *full_base;
 	char *base;
 	int upstream_is_gone = 0;
 
-	if (stat_tracking_info(branch, &ours, &theirs, &full_base,
-			       AHEAD_BEHIND_FULL) < 0) {
+	sti = stat_tracking_info(branch, &ours, &theirs, &full_base, abf);
+	if (sti < 0) {
 		if (!full_base)
 			return 0;
 		upstream_is_gone = 1;
@@ -2118,10 +2119,17 @@ int format_tracking_info(struct branch *branch, struct strbuf *sb)
 		if (advice_status_hints)
 			strbuf_addstr(sb,
 				_("  (use \"git branch --unset-upstream\" to fixup)\n"));
-	} else if (!ours && !theirs) {
+	} else if (!sti) {
 		strbuf_addf(sb,
 			_("Your branch is up to date with '%s'.\n"),
 			base);
+	} else if (abf == AHEAD_BEHIND_QUICK) {
+		strbuf_addf(sb,
+			    _("Your branch and '%s' refer to different commits.\n"),
+			    base);
+		if (advice_status_hints)
+			strbuf_addf(sb, _("  (use \"%s\" for details)\n"),
+				    "git status --ahead-behind");
 	} else if (!theirs) {
 		strbuf_addf(sb,
 			Q_("Your branch is ahead of '%s' by %d commit.\n",

remote.h

@@ -267,7 +267,8 @@ enum ahead_behind_flags {
 /* Reporting of tracking info */
 int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs,
 		       const char **upstream_name, enum ahead_behind_flags abf);
-int format_tracking_info(struct branch *branch, struct strbuf *sb);
+int format_tracking_info(struct branch *branch, struct strbuf *sb,
+			 enum ahead_behind_flags abf);
 
 struct ref *get_local_heads(void);
 /*

t/t6040-tracking-info.sh

@@ -159,6 +159,35 @@ test_expect_success 'status -s -b --no-ahead-behind (diverged from upstream)' '
 	test_i18ncmp expect actual
 '
 
+cat >expect <<\EOF
+On branch b1
+Your branch and 'origin/master' have diverged,
+and have 1 and 1 different commits each, respectively.
+EOF
+
+test_expect_success 'status --long --branch' '
+	(
+		cd test &&
+		git checkout b1 >/dev/null &&
+		git status --long -b | head -3
+	) >actual &&
+	test_i18ncmp expect actual
+'
+
+cat >expect <<\EOF
+On branch b1
+Your branch and 'origin/master' refer to different commits.
+EOF
+
+test_expect_success 'status --long --branch --no-ahead-behind' '
+	(
+		cd test &&
+		git checkout b1 >/dev/null &&
+		git status --long -b --no-ahead-behind | head -2
+	) >actual &&
+	test_i18ncmp expect actual
+'
+
 cat >expect <<\EOF
 ## b5...brokenbase [gone]
 EOF

wt-status.c

@@ -1011,7 +1011,7 @@ static void wt_longstatus_print_tracking(struct wt_status *s)
 	if (!skip_prefix(s->branch, "refs/heads/", &branch_name))
 		return;
 	branch = branch_get(branch_name);
-	if (!format_tracking_info(branch, &sb))
+	if (!format_tracking_info(branch, &sb, s->ahead_behind_flags))
 		return;
 
 	i = 0;