Merge branch 'bw/object-id'

Conversion from uchar[20] to struct object_id continues.

* bw/object-id:
  receive-pack: don't access hash of NULL object_id pointer
  notes: don't access hash of NULL object_id pointer
  tree-diff: don't access hash of NULL object_id pointer

builtin/notes.c

@@ -456,7 +456,7 @@ static int add(int argc, const char **argv, const char *prefix)
 			oid_to_hex(&object));
 	}
 
-	prepare_note_data(&object, &d, note->hash);
+	prepare_note_data(&object, &d, note ? note->hash : NULL);
 	if (d.buf.len || allow_empty) {
 		write_note_data(&d, new_note.hash);
 		if (add_note(t, &object, &new_note, combine_notes_overwrite))

builtin/receive-pack.c

@@ -1138,7 +1138,7 @@ static const char *update(struct command *cmd, struct shallow_info *si)
 		}
 		if (ref_transaction_delete(transaction,
 					   namespaced_name,
-					   old_oid->hash,
+					   old_oid ? old_oid->hash : NULL,
 					   0, "push", &err)) {
 			rp_error("%s", err.buf);
 			strbuf_release(&err);

tree-diff.c

@@ -421,8 +421,9 @@ static struct combine_diff_path *ll_diff_tree_paths(
 	 *   diff_tree_oid(parent, commit) )
 	 */
 	for (i = 0; i < nparent; ++i)
-		tptree[i] = fill_tree_descriptor(&tp[i], parents_oid[i]->hash);
-	ttree = fill_tree_descriptor(&t, oid->hash);
+		tptree[i] = fill_tree_descriptor(&tp[i],
+				parents_oid[i] ? parents_oid[i]->hash : NULL);
+	ttree = fill_tree_descriptor(&t, oid ? oid->hash : NULL);
 
 	/* Enable recursion indefinitely */
 	opt->pathspec.recursive = DIFF_OPT_TST(opt, RECURSIVE);