[PATCH] for-each-ref: add %(upstream:gone) to mark missing refs

["Øystein Walle" <oystwa@gmail.com>]

git branch -vv will show "gone" next to a remote tracking branch if it
does not exist. for-each-ref is suitable for parsing but had no way of
showing this information.

This introduces "%(upstream:gone)" to display "gone" in the formatted
output if the ref does not exist or an empty string otherwise, analogous
to git branch -vv.

Signed-off-by: Øystein Walle <oystwa@gmail.com>
---
 Documentation/git-for-each-ref.txt |  5 +++--
 ref-filter.c                       | 10 +++++++++-
 t/t6300-for-each-ref.sh            | 12 ++++++++++++
 3 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-for-each-ref.txt b/Documentation/git-for-each-ref.txt
index f57e69b..039a86b 100644
--- a/Documentation/git-for-each-ref.txt
+++ b/Documentation/git-for-each-ref.txt
@@ -114,8 +114,9 @@ upstream::
 	`refname` above.  Additionally respects `:track` to show
 	"[ahead N, behind M]" and `:trackshort` to show the terse
 	version: ">" (ahead), "<" (behind), "<>" (ahead and behind),
-	or "=" (in sync).  Has no effect if the ref does not have
-	tracking information associated with it.
+	or "=" (in sync) and `:gone` to show "gone" if the remote ref
+	does not exist, or an empty string if it does. Has no effect if
+	the ref does not have tracking information associated with it.
 
 push::
 	The name of a local ref which represents the `@{push}` location
diff --git a/ref-filter.c b/ref-filter.c
index bc551a7..5402052 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -37,7 +37,7 @@ static struct used_atom {
 	union {
 		char color[COLOR_MAXLEN];
 		struct align align;
-		enum { RR_NORMAL, RR_SHORTEN, RR_TRACK, RR_TRACKSHORT }
+		enum { RR_NORMAL, RR_SHORTEN, RR_TRACK, RR_TRACKSHORT, RR_GONE }
 			remote_ref;
 		struct {
 			enum { C_BARE, C_BODY, C_BODY_DEP, C_LINES, C_SIG, C_SUB } option;
@@ -67,6 +67,8 @@ static void remote_ref_atom_parser(struct used_atom *atom, const char *arg)
 		atom->u.remote_ref = RR_TRACK;
 	else if (!strcmp(arg, "trackshort"))
 		atom->u.remote_ref = RR_TRACKSHORT;
+	else if (!strcmp(arg, "gone"))
+		atom->u.remote_ref = RR_GONE;
 	else
 		die(_("unrecognized format: %%(%s)"), atom->name);
 }
@@ -923,6 +925,12 @@ static void fill_remote_ref_details(struct used_atom *atom, const char *refname,
 			*s = ">";
 		else
 			*s = "<>";
+	} else if (atom->u.remote_ref == RR_GONE) {
+		const char *upstream;
+		if (stat_tracking_info(branch, &num_ours, &num_theirs, &upstream) < 0)
+			*s = "gone";
+		else
+			*s = "";
 	} else /* RR_NORMAL */
 		*s = refname;
 }
diff --git a/t/t6300-for-each-ref.sh b/t/t6300-for-each-ref.sh
index 19a2823..1fc5d1d 100755
--- a/t/t6300-for-each-ref.sh
+++ b/t/t6300-for-each-ref.sh
@@ -383,6 +383,18 @@ test_expect_success 'Check that :track[short] works when upstream is invalid' '
 	test_cmp expected actual
 '
 
+test_expect_success 'Check that :gone produces expected results' '
+	cat >expected <<-\EOF &&
+gone
+	EOF
+	test_when_finished "git config branch.master.merge refs/heads/master" &&
+	git config branch.master.merge refs/heads/does-not-exist &&
+	git for-each-ref \
+		--format="%(upstream:gone)" \
+		refs/heads >actual &&
+	test_cmp expected actual
+'
+
 test_expect_success 'Check for invalid refname format' '
 	test_must_fail git for-each-ref --format="%(refname:INVALID)"
 '
-- 
2.9.2