fn main() {
// block1: fails
{
let mut m = 10;
let n = {
let b = &&mut m;
&**b // just returning b fails
};
println!("{:?}", n);
}
// block2: passes
{
let mut m = 10;
let n = {
let b = &&m;
&**b // just returning b fails here too
};
println!("{:?}", n);
}
}
BLUT1
失败,错误为:
error[E0597]: borrowed value does not live long enough
--> src/main.rs:7:22
|
7 | let b = &&mut m;
| ^^^^^^ temporary value does not live long enough
8 | &**b // just returning b fails
9 | };
| - temporary value dropped here while still borrowed
...
12 | }
| - temporary value needs to live until here
假设内部不可变引用扩展到
方块2
范围,而在
BLUT1
,即使有外部引用,也始终删除内部可变引用?