相关疑难解决方法(0)

我的这个片段没有通过借阅检查器:

use std::collections::HashMap;

enum Error {
    FunctionNotFound,
}

#[derive(Copy, Clone)]
struct Function<'a> {
    name: &'a str,
    code: &'a [u32],
}

struct Context<'a> {
    program: HashMap<&'a str, Function<'a>>,
    call_stack: Vec<Function<'a>>,
}

impl<'a> Context<'a> {
    fn get_function(&'a mut self, fun_name: &'a str) -> Result<Function<'a>, Error> {
        self.program
            .get(fun_name)
            .map(|f| *f)
            .ok_or(Error::FunctionNotFound)
    }

    fn call(&'a mut self, fun_name: &'a str) -> Result<(), Error> {
        let fun = try!(self.get_function(fun_name));

        self.call_stack.push(fun);

        Ok(())
    }
}

fn main() {}

error[E0499]: cannot borrow `self.call_stack` as mutable more than …