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