Merge branch 'jx/branch-vv-always-compare-with-upstream'

"git branch -v -v" (and "git status") did not distinguish among a
branch that does not build on any other branch, a branch that is in
sync with the branch it builds on, and a branch that is configured
to build on some other branch that no longer exists.

* jx/branch-vv-always-compare-with-upstream:
  status: always show tracking branch even no change
  branch: report invalid tracking branch as gone

4 files changed, 175 insertions, 48 deletions

diff --git a/builtin/branch.c b/builtin/branch.c
index 0903763702..ad0f86de54 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -423,19 +423,19 @@ static void fill_tracking_info(struct strbuf *stat, const char *branch_name,
 	char *ref = NULL;
 	struct branch *branch = branch_get(branch_name);
 	struct strbuf fancy = STRBUF_INIT;
+	int upstream_is_gone = 0;
 
-	if (!stat_tracking_info(branch, &ours, &theirs)) {
-		if (branch && branch->merge && branch->merge[0]->dst &&
-		    show_upstream_ref) {
-			ref = shorten_unambiguous_ref(branch->merge[0]->dst, 0);
-			if (want_color(branch_use_color))
-				strbuf_addf(stat, "[%s%s%s] ",
-						branch_get_color(BRANCH_COLOR_UPSTREAM),
-						ref, branch_get_color(BRANCH_COLOR_RESET));
-			else
-				strbuf_addf(stat, "[%s] ", ref);
-		}
+	switch (stat_tracking_info(branch, &ours, &theirs)) {
+	case 0:
+		/* no base */
 		return;
+	case -1:
+		/* with "gone" base */
+		upstream_is_gone = 1;
+		break;
+	default:
+		/* with base */
+		break;
 	}
 
 	if (show_upstream_ref) {
@@ -448,19 +448,25 @@ static void fill_tracking_info(struct strbuf *stat, const char *branch_name,
 			strbuf_addstr(&fancy, ref);
 	}
 
-	if (!ours) {
-		if (ref)
+	if (upstream_is_gone) {
+		if (show_upstream_ref)
+			strbuf_addf(stat, _("[%s: gone]"), fancy.buf);
+	} else if (!ours && !theirs) {
+		if (show_upstream_ref)
+			strbuf_addf(stat, _("[%s]"), fancy.buf);
+	} else if (!ours) {
+		if (show_upstream_ref)
 			strbuf_addf(stat, _("[%s: behind %d]"), fancy.buf, theirs);
 		else
 			strbuf_addf(stat, _("[behind %d]"), theirs);
 
 	} else if (!theirs) {
-		if (ref)
+		if (show_upstream_ref)
 			strbuf_addf(stat, _("[%s: ahead %d]"), fancy.buf, ours);
 		else
 			strbuf_addf(stat, _("[ahead %d]"), ours);
 	} else {
-		if (ref)
+		if (show_upstream_ref)
 			strbuf_addf(stat, _("[%s: ahead %d, behind %d]"),
 				    fancy.buf, ours, theirs);
 		else
diff --git a/remote.c b/remote.c
index 24334679e0..e9fedfa918 100644
--- a/remote.c
+++ b/remote.c
@@ -1729,7 +1729,11 @@ int ref_newer(const unsigned char *new_sha1, const unsigned char *old_sha1)
 }
 
 /*
- * Return true if there is anything to report, otherwise false.
+ * Compare a branch with its upstream, and save their differences (number
+ * of commits) in *num_ours and *num_theirs.
+ *
+ * Return 0 if branch has no upstream (no base), -1 if upstream is missing
+ * (with "gone" base), otherwise 1 (with base).
  */
 int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs)
 {
@@ -1740,34 +1744,30 @@ int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs)
 	const char *rev_argv[10], *base;
 	int rev_argc;
 
-	/*
-	 * Nothing to report unless we are marked to build on top of
-	 * somebody else.
-	 */
+	/* Cannot stat unless we are marked to build on top of somebody else. */
 	if (!branch ||
 	    !branch->merge || !branch->merge[0] || !branch->merge[0]->dst)
 		return 0;
 
-	/*
-	 * If what we used to build on no longer exists, there is
-	 * nothing to report.
-	 */
+	/* Cannot stat if what we used to build on no longer exists */
 	base = branch->merge[0]->dst;
 	if (read_ref(base, sha1))
-		return 0;
+		return -1;
 	theirs = lookup_commit_reference(sha1);
 	if (!theirs)
-		return 0;
+		return -1;
 
 	if (read_ref(branch->refname, sha1))
-		return 0;
+		return -1;
 	ours = lookup_commit_reference(sha1);
 	if (!ours)
-		return 0;
+		return -1;
 
 	/* are we the same? */
-	if (theirs == ours)
-		return 0;
+	if (theirs == ours) {
+		*num_theirs = *num_ours = 0;
+		return 1;
+	}
 
 	/* Run "rev-list --left-right ours...theirs" internally... */
 	rev_argc = 0;
@@ -1809,31 +1809,53 @@ int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs)
  */
 int format_tracking_info(struct branch *branch, struct strbuf *sb)
 {
-	int num_ours, num_theirs;
+	int ours, theirs;
 	const char *base;
+	int upstream_is_gone = 0;
 
-	if (!stat_tracking_info(branch, &num_ours, &num_theirs))
+	switch (stat_tracking_info(branch, &ours, &theirs)) {
+	case 0:
+		/* no base */
 		return 0;
+	case -1:
+		/* with "gone" base */
+		upstream_is_gone = 1;
+		break;
+	default:
+		/* with base */
+		break;
+	}
 
 	base = branch->merge[0]->dst;
 	base = shorten_unambiguous_ref(base, 0);
-	if (!num_theirs) {
+	if (upstream_is_gone) {
+		strbuf_addf(sb,
+			_("Your branch is based on '%s', but the upstream is gone.\n"),
+			base);
+		if (advice_status_hints)
+			strbuf_addf(sb,
+				_("  (use \"git branch --unset-upstream\" to fixup)\n"));
+	} else if (!ours && !theirs) {
+		strbuf_addf(sb,
+			_("Your branch is up-to-date with '%s'.\n"),
+			base);
+	} else if (!theirs) {
 		strbuf_addf(sb,
 			Q_("Your branch is ahead of '%s' by %d commit.\n",
 			   "Your branch is ahead of '%s' by %d commits.\n",
-			   num_ours),
-			base, num_ours);
+			   ours),
+			base, ours);
 		if (advice_status_hints)
 			strbuf_addf(sb,
 				_("  (use \"git push\" to publish your local commits)\n"));
-	} else if (!num_ours) {
+	} else if (!ours) {
 		strbuf_addf(sb,
 			Q_("Your branch is behind '%s' by %d commit, "
 			       "and can be fast-forwarded.\n",
 			   "Your branch is behind '%s' by %d commits, "
 			       "and can be fast-forwarded.\n",
-			   num_theirs),
-			base, num_theirs);
+			   theirs),
+			base, theirs);
 		if (advice_status_hints)
 			strbuf_addf(sb,
 				_("  (use \"git pull\" to update your local branch)\n"));
@@ -1845,8 +1867,8 @@ int format_tracking_info(struct branch *branch, struct strbuf *sb)
 			   "Your branch and '%s' have diverged,\n"
 			       "and have %d and %d different commits each, "
 			       "respectively.\n",
-			   num_theirs),
-			base, num_ours, num_theirs);
+			   theirs),
+			base, ours, theirs);
 		if (advice_status_hints)
 			strbuf_addf(sb,
 				_("  (use \"git pull\" to merge the remote branch into yours)\n"));
diff --git a/t/t6040-tracking-info.sh b/t/t6040-tracking-info.sh
index ec2b516c3f..ba26cfe923 100755
--- a/t/t6040-tracking-info.sh
+++ b/t/t6040-tracking-info.sh
@@ -28,10 +28,15 @@ test_expect_success setup '
 		git reset --hard HEAD^ &&
 		git checkout -b b4 origin &&
 		advance e &&
-		advance f
+		advance f &&
+		git checkout -b brokenbase origin &&
+		git checkout -b b5 --track brokenbase &&
+		advance g &&
+		git branch -d brokenbase &&
+		git checkout -b b6 origin
 	) &&
 	git checkout -b follower --track master &&
-	advance g
+	advance h
 '
 
 script='s/^..\(b.\)[	 0-9a-f]*\[\([^]]*\)\].*/\1 \2/p'
@@ -56,6 +61,8 @@ b1 origin/master: ahead 1, behind 1
 b2 origin/master: ahead 1, behind 1
 b3 origin/master: behind 1
 b4 origin/master: ahead 2
+b5 brokenbase: gone
+b6 origin/master
 EOF
 
 test_expect_success 'branch -vv' '
@@ -67,7 +74,7 @@ test_expect_success 'branch -vv' '
 	test_i18ncmp expect actual
 '
 
-test_expect_success 'checkout' '
+test_expect_success 'checkout (diverged from upstream)' '
 	(
 		cd test && git checkout b1
 	) >actual &&
@@ -80,7 +87,22 @@ test_expect_success 'checkout with local tracked branch' '
 	test_i18ngrep "is ahead of" actual
 '
 
-test_expect_success 'status' '
+test_expect_success 'checkout (upstream is gone)' '
+	(
+		cd test &&
+		git checkout b5
+	) >actual &&
+	test_i18ngrep "is based on .*, but the upstream is gone." actual
+'
+
+test_expect_success 'checkout (up-to-date with upstream)' '
+	(
+		cd test && git checkout b6
+	) >actual &&
+	test_i18ngrep "Your branch is up-to-date with .origin/master" actual
+'
+
+test_expect_success 'status (diverged from upstream)' '
 	(
 		cd test &&
 		git checkout b1 >/dev/null &&
@@ -90,6 +112,65 @@ test_expect_success 'status' '
 	test_i18ngrep "have 1 and 1 different" actual
 '
 
+test_expect_success 'status (upstream is gone)' '
+	(
+		cd test &&
+		git checkout b5 >/dev/null &&
+		# reports nothing to commit
+		test_must_fail git commit --dry-run
+	) >actual &&
+	test_i18ngrep "is based on .*, but the upstream is gone." actual
+'
+
+test_expect_success 'status (up-to-date with upstream)' '
+	(
+		cd test &&
+		git checkout b6 >/dev/null &&
+		# reports nothing to commit
+		test_must_fail git commit --dry-run
+	) >actual &&
+	test_i18ngrep "Your branch is up-to-date with .origin/master" actual
+'
+
+cat >expect <<\EOF
+## b1...origin/master [ahead 1, behind 1]
+EOF
+
+test_expect_success 'status -s -b (diverged from upstream)' '
+	(
+		cd test &&
+		git checkout b1 >/dev/null &&
+		git status -s -b | head -1
+	) >actual &&
+	test_i18ncmp expect actual
+'
+
+cat >expect <<\EOF
+## b5...brokenbase [gone]
+EOF
+
+test_expect_success 'status -s -b (upstream is gone)' '
+	(
+		cd test &&
+		git checkout b5 >/dev/null &&
+		git status -s -b | head -1
+	) >actual &&
+	test_i18ncmp expect actual
+'
+
+cat >expect <<\EOF
+## b6...origin/master
+EOF
+
+test_expect_success 'status -s -b (up-to-date with upstream)' '
+	(
+		cd test &&
+		git checkout b6 >/dev/null &&
+		git status -s -b | head -1
+	) >actual &&
+	test_i18ncmp expect actual
+'
+
 test_expect_success 'fail to track lightweight tags' '
 	git checkout master &&
 	git tag light &&
diff --git a/wt-status.c b/wt-status.c
index ff4b32426a..c8c2d77524 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -1363,6 +1363,7 @@ static void wt_shortstatus_print_tracking(struct wt_status *s)
 	const char *base;
 	const char *branch_name;
 	int num_ours, num_theirs;
+	int upstream_is_gone = 0;
 
 	color_fprintf(s->fp, color(WT_STATUS_HEADER, s), "## ");
 
@@ -1380,20 +1381,37 @@ static void wt_shortstatus_print_tracking(struct wt_status *s)
 	branch = branch_get(s->branch + 11);
 	if (s->is_initial)
 		color_fprintf(s->fp, header_color, _("Initial commit on "));
-	if (!stat_tracking_info(branch, &num_ours, &num_theirs)) {
-		color_fprintf(s->fp, branch_color_local, "%s", branch_name);
+
+	color_fprintf(s->fp, branch_color_local, "%s", branch_name);
+
+	switch (stat_tracking_info(branch, &num_ours, &num_theirs)) {
+	case 0:
+		/* no base */
 		fputc(s->null_termination ? '\0' : '\n', s->fp);
 		return;
+	case -1:
+		/* with "gone" base */
+		upstream_is_gone = 1;
+		break;
+	default:
+		/* with base */
+		break;
 	}
 
 	base = branch->merge[0]->dst;
 	base = shorten_unambiguous_ref(base, 0);
-	color_fprintf(s->fp, branch_color_local, "%s", branch_name);
 	color_fprintf(s->fp, header_color, "...");
 	color_fprintf(s->fp, branch_color_remote, "%s", base);
 
+	if (!upstream_is_gone && !num_ours && !num_theirs) {
+		fputc(s->null_termination ? '\0' : '\n', s->fp);
+		return;
+	}
+
 	color_fprintf(s->fp, header_color, " [");
-	if (!num_ours) {
+	if (upstream_is_gone) {
+		color_fprintf(s->fp, header_color, _("gone"));
+	} else if (!num_ours) {
 		color_fprintf(s->fp, header_color, _("behind "));
 		color_fprintf(s->fp, branch_color_remote, "%d", num_theirs);
 	} else if (!num_theirs) {