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//@ run-pass
//! Deref patterns on boxes are lowered using built-in derefs, rather than generic `Deref::deref`
//! and `DerefMut::deref_mut`. Test that they work as expected.
#![feature(deref_patterns)]
#![expect(incomplete_features)]
fn unbox_1<T>(b: Box<T>) -> T {
let deref!(x) = b;
x
}
fn unbox_2<T>(b: Box<(T,)>) -> T {
let (x,) = b;
x
}
fn unbox_separately<T>(b: Box<(T, T)>) -> (T, T) {
let (x, _) = b;
let (_, y) = b;
(x, y)
}
fn main() {
// test that deref patterns can move out of boxes
let b1 = Box::new(0);
let b2 = Box::new((0,));
assert_eq!(unbox_1(b1), unbox_2(b2));
let b3 = Box::new((1, 2));
assert_eq!(unbox_separately(b3), (1, 2));
// test that borrowing from a box also works
let mut b = "hi".to_owned().into_boxed_str();
let deref!(ref mut s) = b;
s.make_ascii_uppercase();
assert_eq!(&*b, "HI");
}
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