I have a problem with the borrow checker in the following scenario: First I store an immutable reference to a mutable variable x, which I later use elsewhere in my code. Now I come to a point where I want to change the value of x. Knowing that there is an immutable reference to it inside foo.bar, first I remove the reference by calling foo.bar.clear().
Now that there are no immutable borrows, I'd expect that I can mutate the object, but that's not case. I assume that the problem is that the compiler has no way of knowing that clear() drops the references inside foo.bar, but I'm clueless how to proceed in this situation.
Minimal example:
struct Foo<'a> {
bar: Vec<&'a i32>
}
fn main() {
let mut x = 42;
let mut foo = Foo { bar: vec![&x] };
// Do immutable stuff with foo.bar[0]... then:
foo.bar.clear();
x += 1;
foo.bar.push(&x);
println!("X is: {}", foo.bar[0]);
}
