What is the proper way to use GhostCell and GhostToken?

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1

Hello.
In the past few days, I noticed that there is an alternative of RefCell in Rust to acquire the mutable reference of the immutable object, called GhostCell. The paper GhostCell: Separating Permissions from Data in Rust had proven the safety of this method.
However, I found it is difficult for me to use the GhostCell in the production because GhostCell requires:

The closure must be variant over the lifetimes.
None of the branded items can be returned by the closure.

This means that I cannot:

Create a GhostCell out of the closure. When I want to change its value, I create a closure by GhostToken and acquire the mutable reference in this closure.
Create a GhostCell in the closure and return it for other usages.

For example, if I have a vector in the reference counter, such as Rc::new(vec![1,2,3]), how can I acquire the mutable reference of vec![1,2,3]? I tried to create Rc::new(GhostCell::new(vec![1,2,3])) and acquire it mutable reference by GhostToken::new(|mut token|{...}), but the 'token' will escape the closure body, which is not allowed.

Could anyone tell me what is the proper way to use GhostCell? Thanks so much!

2

It could look something like this

use std::rc::Rc;
use ghost_cell::{GhostToken,GhostCell};
let val = GhostToken::new(|mut tok| {
    let cell = GhostCell::new(vec![1,2,3]);
    let rc = Rc::new(&cell);
    let rc2 = Rc::clone(&rc);
    rc.borrow_mut(&mut tok).push(4);
    rc2.borrow_mut(&mut tok).push(5);
    // Return vec
    cell.into_inner()
});
println!("{:?}",val)
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