0eb3b110f0
This allows deref patterns to move out of boxes. Implementation-wise, I've opted to put the information of whether a deref pattern uses a built-in deref or a method call in the THIR. It'd be a bit less code to check `.is_box()` everywhere, but I think this way feels more robust (and we don't have a `mutability` field in the THIR that we ignore when the smart pointer's a box). I'm not sure about the naming (or using `ByRef`), though.
68 lines
1.6 KiB
Rust
68 lines
1.6 KiB
Rust
//@ run-pass
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#![feature(deref_patterns)]
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#![allow(incomplete_features)]
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use std::rc::Rc;
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struct NoCopy;
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fn main() {
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let b = Rc::new("aaa".to_string());
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let f = || {
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let deref!(ref s) = b else { unreachable!() };
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assert_eq!(s.len(), 3);
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};
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assert_eq!(b.len(), 3);
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f();
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let v = vec![1, 2, 3];
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let f = || {
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// this should count as a borrow of `v` as a whole
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let [.., x] = v else { unreachable!() };
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assert_eq!(x, 3);
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};
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assert_eq!(v, [1, 2, 3]);
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f();
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let mut b = "aaa".to_string();
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let mut f = || {
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let deref!(ref mut s) = b else { unreachable!() };
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s.make_ascii_uppercase();
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};
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f();
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assert_eq!(b, "AAA");
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let mut v = vec![1, 2, 3];
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let mut f = || {
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// this should count as a mutable borrow of `v` as a whole
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let [.., ref mut x] = v else { unreachable!() };
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*x = 4;
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};
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f();
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assert_eq!(v, [1, 2, 4]);
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let mut v = vec![1, 2, 3];
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let mut f = || {
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// here, `[.., x]` is adjusted by both an overloaded deref and a builtin deref
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let [.., x] = &mut v else { unreachable!() };
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*x = 4;
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};
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f();
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assert_eq!(v, [1, 2, 4]);
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let b = Box::new(NoCopy);
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let f = || {
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// this should move out of the box rather than borrow.
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let deref!(x) = b else { unreachable!() };
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drop::<NoCopy>(x);
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};
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f();
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let b = Box::new((NoCopy,));
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let f = || {
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// this should move out of the box rather than borrow.
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let (x,) = b else { unreachable!() };
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drop::<NoCopy>(x);
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};
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f();
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}
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