[PATCH 6/7] object_as_type: set commit index

[Jeff King <peff@peff.net>]

The point of the "index" field of struct commit is that
every allocated commit would have a uniquely allocated
value. It is supposed to be an invariant that whenever
object->type is set to OBJ_COMMIT, we have a unique index.

Commit 969eba6 (commit: push commit_index update into
alloc_commit_node, 2014-06-10) covered this case for
newly-allocated commits. However, we may also allocate an
OBJ_NONE object via lookup_unknown_object, and only later
convert it to a commit. We must make sure that we set the
commit index when we switch the type field.

Signed-off-by: Jeff King <peff@peff.net>
---
 object.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/object.c b/object.c
index b2319f6..69fbbbf 100644
--- a/object.c
+++ b/object.c
@@ -163,6 +163,8 @@ void *object_as_type(struct object *obj, enum object_type type, int quiet)
 	if (obj->type == type)
 		return obj;
 	else if (obj->type == OBJ_NONE) {
+		if (type == OBJ_COMMIT)
+			((struct commit *)obj)->index = alloc_commit_index();
 		obj->type = type;
 		return obj;
 	}
-- 
2.0.0.566.gfe3e6b2