1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
|
// Tests correct kind-checking of the reason stack closures without the :Copy
// bound must be noncopyable. For details see
// https://smallcultfollowing.com/babysteps/blog/2013/04/30/the-case-of-the-recurring-closure/
struct R<'a> {
// This struct is needed to create the
// otherwise infinite type of a fn that
// accepts itself as argument:
c: Box<dyn FnMut(&mut R, bool) + 'a>
}
fn innocent_looking_victim() {
let mut x = Some("hello".to_string());
conspirator(|f, writer| {
if writer {
x = None;
} else {
match x {
Some(ref msg) => {
(f.c)(f, true);
//~^ ERROR: cannot borrow `*f` as mutable more than once at a time
println!("{}", msg);
},
None => panic!("oops"),
}
}
})
}
fn conspirator<F>(mut f: F) where F: FnMut(&mut R, bool) {
let mut r = R {c: Box::new(f)};
f(&mut r, false) //~ ERROR borrow of moved value
}
fn main() { innocent_looking_victim() }
|
