有人能解释一下为什么以下代码会编译通过,但如果我注释掉其中一行,那么它就无法编译通过,即使代码本质上执行相同的操作?
struct OtherStruct {
x: i32,
}
struct Inner {
blah: i32,
vector: Vec<OtherStruct>
}
struct Outer {
inner: Inner,
}
impl Inner {
pub fn set_blah(&mut self, new_val : i32) {
self.blah = new_val;
}
}
fn main() {
let mut outer = Outer {
inner: Inner {
blah: 10,
vector: vec![
OtherStruct { x: 1 },
OtherStruct { x: 2 },
OtherStruct { x: 3 },
OtherStruct { x: 4 },
OtherStruct { x: 5 },
]
}
};
for item in outer.inner.vector.iter() {
println!("{}", item.x);
outer.inner.blah = 4;
//outer.inner.set_blah(6);
}
}
编译器错误如下:
|
34 | for item in outer.inner.vector.iter() {
| -------------------------
| |
| immutable borrow occurs here
| immutable borrow later used here
...
37 | outer.inner.set_blah(6);
| ^^^^^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
我能理解这个问题,但我想知道为什么我在不使用函数调用时仍然可以轻易实现它,毕竟同样会出现可变性问题?