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b41d8bde00
This does not yet handle the case of mixed deref patterns with normal constructors; it'll ICE in `Constructor::is_covered_by`. That'll be fixed in a later commit.
38 lines
898 B
Rust
38 lines
898 B
Rust
//@ run-pass
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//! Deref patterns on boxes are lowered using built-in derefs, rather than generic `Deref::deref`
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//! and `DerefMut::deref_mut`. Test that they work as expected.
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#![feature(deref_patterns)]
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#![expect(incomplete_features)]
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fn unbox_1<T>(b: Box<T>) -> T {
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let deref!(x) = b;
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x
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}
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fn unbox_2<T>(b: Box<(T,)>) -> T {
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let (x,) = b;
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x
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}
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fn unbox_separately<T>(b: Box<(T, T)>) -> (T, T) {
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let (x, _) = b;
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let (_, y) = b;
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(x, y)
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}
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fn main() {
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// test that deref patterns can move out of boxes
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let b1 = Box::new(0);
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let b2 = Box::new((0,));
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assert_eq!(unbox_1(b1), unbox_2(b2));
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let b3 = Box::new((1, 2));
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assert_eq!(unbox_separately(b3), (1, 2));
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// test that borrowing from a box also works
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let mut b = "hi".to_owned().into_boxed_str();
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let deref!(ref mut s) = b;
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s.make_ascii_uppercase();
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assert_eq!(&*b, "HI");
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}
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