rust/tests/ui/moves/move-out-of-slice-1.rs

#![feature(box_patterns)]

struct A;

fn main() {
    let a: Box<[A]> = Box::new([A]);
    match a { //~ ERROR cannot move out of type `[A]`, a non-copy slice
        box [a] => {},
        _ => {}
    }
}
Stabilize slice patterns without `..` Merge `feature(advanced_slice_patterns)` into `feature(slice_patterns)` 2018-02-24 19:21:33 +00:00			`#![feature(box_patterns)]`
forbid moves out of slices The wording of RFC #495 enables moves out of slices. Unfortuantely, non-zeroing moves out of slices introduce a very annoying complication: as slices can vary in their length, indexes from the start and end may or may not overlap depending on the slice's exact length, which prevents assigning a particular drop flag for each individual element. For example, in the code ```Rust fn foo<T>(a: Box<[Box<[T]>]>, c: bool) -> T { match (a, c) { (box [box [t, ..], ..], true) => t, (box [.., box [.., t]], false) => t, _ => panic!() } } ``` If the condition is false, we have to drop the first element of `a`, unless `a` has size 1 in which case we drop all the elements of it but the last. If someone comes with a nice way of handling it, we can always re-allow moves out of slices. This is a [breaking-change], but it is behind the `slice_patterns` feature gate and was not allowed until recently. 2016-07-24 10:56:27 +00:00
			`struct A;`

			`fn main() {`
			`let a: Box<[A]> = Box::new([A]);`
update tests for migrate mode by default 2019-04-22 07:40:08 +00:00			match a { //~ ERROR cannot move out of type `[A]`, a non-copy slice
			`box [a] => {},`
forbid moves out of slices The wording of RFC #495 enables moves out of slices. Unfortuantely, non-zeroing moves out of slices introduce a very annoying complication: as slices can vary in their length, indexes from the start and end may or may not overlap depending on the slice's exact length, which prevents assigning a particular drop flag for each individual element. For example, in the code ```Rust fn foo<T>(a: Box<[Box<[T]>]>, c: bool) -> T { match (a, c) { (box [box [t, ..], ..], true) => t, (box [.., box [.., t]], false) => t, _ => panic!() } } ``` If the condition is false, we have to drop the first element of `a`, unless `a` has size 1 in which case we drop all the elements of it but the last. If someone comes with a nice way of handling it, we can always re-allow moves out of slices. This is a [breaking-change], but it is behind the `slice_patterns` feature gate and was not allowed until recently. 2016-07-24 10:56:27 +00:00			`_ => {}`
			`}`
			`}`