Here's some code that I'm having trouble getting to compile:
struct HasVec {
vec: Vec<u8>,
}
fn get_or_make<'a>(container: &'a mut HasVec) -> &'a mut u8 {
let ref mut vec = container.vec;
{
for element in vec.iter_mut() {
if *element > 9 {
return element;
}
}
}
vec.push(10);
vec.last_mut().unwrap()
}
The output from the compiler is:
error[E0499]: cannot borrow `*vec` as mutable more than once at a time
|
8 | for element in vec.iter_mut() {
| --- first mutable borrow occurs here
...
14 | vec.push(10);
| ^^^ second mutable borrow occurs here
15 | vec.last_mut().unwrap()
16 | }
| - first borrow ends here
error[E0499]: cannot borrow `*vec` as mutable more than once at a time
|
8 | for element in vec.iter_mut() {
| --- first mutable borrow occurs here
...
15 | vec.last_mut().unwrap()
| ^^^ second mutable borrow occurs here
16 | }
| - first borrow ends here
error[E0499]: cannot borrow `*vec` as mutable more than once at a time
|
8 | for element in vec.iter_mut() {
| --- first mutable borrow occurs here
...
15 | vec.last_mut().unwrap()
| ^^^ second mutable borrow occurs here
16 | }
| - first borrow ends here
Isn't the borrow supposed to end at the end of the scope on line 13? I haven't found any way to refactor that code that will satisfy the borrow checker. Putting let ref mut vec = container.vec; inside of the code block with the for loop and another right after that block doesn't work and neither does accessing container.vec directly without a ref variable.
I'm using Rust 1.16.0.
