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// edition:2021
// Test borrow checker when we precise capture when using boxes
struct MetaData { x: String, name: String }
struct Data { m: MetaData }
struct BoxedData(Box<Data>);
struct EvenMoreBoxedData(Box<BoxedData>);
// Check diagnostics when the same path is mutated both inside and outside the closure
fn box_1() {
let m = MetaData { x: format!("x"), name: format!("name") };
let d = Data { m };
let b = BoxedData(Box::new(d));
let mut e = EvenMoreBoxedData(Box::new(b));
let mut c = || {
e.0.0.m.x = format!("not-x");
};
e.0.0.m.x = format!("not-x");
//~^ ERROR: cannot assign to `e.0.0.m.x` because it is borrowed
c();
}
// Check diagnostics when a path is mutated inside a closure while attempting to read it outside
// the closure.
fn box_2() {
let m = MetaData { x: format!("x"), name: format!("name") };
let d = Data { m };
let b = BoxedData(Box::new(d));
let mut e = EvenMoreBoxedData(Box::new(b));
let mut c = || {
e.0.0.m.x = format!("not-x");
};
println!("{}", e.0.0.m.x);
//~^ ERROR: cannot borrow `e.0.0.m.x` as immutable because it is also borrowed as mutable
c();
}
// Check diagnostics when a path is read inside a closure while attempting to mutate it outside
// the closure.
fn box_3() {
let m = MetaData { x: format!("x"), name: format!("name") };
let d = Data { m };
let b = BoxedData(Box::new(d));
let mut e = EvenMoreBoxedData(Box::new(b));
let c = || {
println!("{}", e.0.0.m.x);
};
e.0.0.m.x = format!("not-x");
//~^ ERROR: cannot assign to `e.0.0.m.x` because it is borrowed
c();
}
fn main() {
box_1();
box_2();
box_3();
}
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