This commit supply an option names `--oid-only` to let `git ls-tree`
only print out the OID of the object. `--oid-only` and `--name-only`
are mutually exclusive in use.

Signed-off-by: Teng Long <redacted>
---
 builtin/ls-tree.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/builtin/ls-tree.c b/builtin/ls-tree.c
index 3a442631c7..1f82229649 100644
--- a/builtin/ls-tree.c
+++ b/builtin/ls-tree.c

@@ -20,6 +20,7 @@ static int line_termination = '\n';
 #define LS_SHOW_TREES 4
 #define LS_NAME_ONLY 8
 #define LS_SHOW_SIZE 16
+#define LS_OID_ONLY 32
 static int abbrev;
 static int ls_options;
 static struct pathspec pathspec;

@@ -90,6 +91,14 @@ static int show_tree(const struct object_id *oid, struct strbuf *base,
 	else if (ls_options & LS_TREE_ONLY)
 		return 0;
 
+	if ((ls_options & LS_NAME_ONLY) && (ls_options & LS_OID_ONLY))
+		die(_("cannot specify --oid-only and --name-only at the same time"));