The data held by an Rc doesn't have one owner. It would probably be pretty painstaking to do cyclic data structures with them correctly, differentiating between

The data held by an Rc doesn't have one owner. It would probably be pretty painstaking to do cyclic data structures with them correctly, differentiating between strong and weak Rc as appropriate, but probably doable. If you don't care about leaking memory, or if the graph is static, you don't even need to worry about that.