在函数参数中解构包含借位的结构

我正在尝试实现一个使用借用检查/生命周期的系统,以便为集合提供安全的自定义索引.请考虑以下代码:

struct Graph(i32);

struct Edge<'a>(&'a Graph, i32);

impl Graph {
    pub fn get_edge(&self) -> Edge {
        Edge(&self, 0)
    }

    pub fn split(&mut self, Edge(_, edge_id): Edge) {
        self.0 = self.0 + edge_id;
    }

    pub fn join(&mut self, Edge(_, edge0_id): Edge, Edge(_, edge1_id): Edge) {
        self.0 = self.0 + edge0_id + edge1_id;
    }
}


fn main() {
    let mut graph = Graph(0);
    let edge = graph.get_edge();
    graph.split(edge)
}

Edge当调用诸如split或join调用方法时,应删除对结构借用的图形的引用.这将满足API不变量,即在图形变异时必须销毁所有边缘索引.但是,编译器没有得到它.它失败的消息就像

error[E0502]: cannot borrow `graph` as mutable because it is also borrowed as immutable
  --> src/main.rs:23:5
   |
22 |     let edge = graph.get_edge();
   |                ----- immutable borrow occurs here
23 |     graph.split(edge)
   |     ^^^^^ mutable borrow occurs here
24 | }
   | - immutable borrow ends here