有没有一种安全的方法可以从Rust的可变引用中临时检索一个拥有的值？

我正在使用两个独立的功能。

• 第一个获取结构的拥有实例，然后返回它。
• 第二个采用可变引用但需要使用第一个函数。

// This structure is not `Clone`.
struct MyStruct;

fn take_owned(s: MyStruct) -> MyStruct {
    // Do things
    s
}

fn take_mut(s: &mut MyStruct) {
    *s = take_owned(s /* problem */);
}

我想了一个解决方案，但我不确定它是否合理：

use std::ptr;

// Temporarily turns a mutable reference into an owned value.
fn mut_to_owned<F>(val: &mut MyStruct, f: F)
where
    F: FnOnce(MyStruct) -> MyStruct,
{
    // We're the only one able to access the data referenced by `val`.
    // This operation simply takes ownership of the value.
    let owned = unsafe { ptr::read(val) };

    // Do things to the owned value.
    let result = f(owned);

    // Give the ownership of the value back to its original owner.
    // From its point of view, nothing happened to the value because we have
    // an exclusive reference.
    unsafe { ptr::write(val, result) };
}

使用此功能，我可以做到：

fn take_mut(s: &mut MyStruct) {
    mut_to_owned(s, take_owned);
}

这段代码好听吗？如果没有，有没有办法安全地做到这一点？

回答