- c->maybe_tree->object.oid.hash
 + get_commit_tree_oid(c)->hash
 
+// These excluded functions must access c->maybe_tree direcly.
 @@
+identifier f !~ "^(get_commit_tree|get_commit_tree_in_graph_one|load_tree_for_commit)$";
 expression c;
 @@
+  f(...) {<...
 - c->maybe_tree
 + get_commit_tree(c)
+  ...>}
 
 @@
 expression c;
 @@
 - get_commit_tree(c) = s
 + c->maybe_tree = s
-
-@@
-expression c;
-@@
-- return get_commit_tree(c);
-+ return c->maybe_tree;