如何在访问其struct成员后传递self mutable引用？

Question

帮我将这个基本模式翻译成Rust。 Rust编译器抱怨所有权;它无法将self引用传递给close方法，因为对self.files的不可变引用仍然存在。

我感到困惑，因为HashMap::get正在竞争，而且它不是迭代器，所以更改files对象有什么问题？

use std::collections::HashMap;

struct File {
    ino: u64
}

struct Filesystem {
    files: HashMap<u64, File>
}

impl File {
    fn close(&self, fs: &mut Filesystem) {
        fs.files.remove(&self.ino);
    }
}

impl Filesystem {
    fn release(&mut self, ino: u64) {
        let file = self.files.get(&ino);
        if file.is_some() {
            file.unwrap().close(self)
        }
    }
}

fn main() {
    let mut fs = Filesystem { files: HashMap::new() };
    fs.release(1)
}

编译器错误是

error: cannot borrow `*self` as mutable because `self.files` is also borrowed as immutable [E0502]
            file.unwrap().close(self)
                                ^~~~
note: immutable borrow occurs here
        let file = self.files.get(&ino);
                   ^~~~~~~~~~
note: immutable borrow ends here
    }
    ^
help: run `rustc --explain E0502` to see a detailed explanation

我最终得到指针;它易于理解和快速。我没有看到RefCell的优点，因为无论如何都会在运行时遇到错误，所以它与使用不同消息的段错误相同。

use std::collections::HashMap;

struct File {
    ino: u64
}

struct Filesystem {
    files: HashMap<u64, File>
}

impl File {
    fn close(&self, fs: *mut Filesystem) {
        unsafe { (*fs).files.remove(&self.ino); }
    }
}

impl Filesystem {
    fn release(&mut self, ino: u64) {
        let p = self as *mut Filesystem;
        let file = self.files.get(&ino);
        if file.is_some() {
            file.unwrap().close(p)
        }
    }
}

fn main() {
    let mut fs = Filesystem { files: HashMap::new() };
    fs.release(1)
}