| // run-pass |
| // Test a very simple custom DST coercion. |
| |
| #![feature(unsize, coerce_unsized)] |
| |
| use std::ops::CoerceUnsized; |
| use std::marker::Unsize; |
| |
| struct Bar<T: ?Sized> { |
| x: *const T, |
| } |
| |
| impl<T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<Bar<U>> for Bar<T> {} |
| |
| trait Baz { |
| fn get(&self) -> i32; |
| } |
| |
| impl Baz for i32 { |
| fn get(&self) -> i32 { |
| *self |
| } |
| } |
| |
| fn main() { |
| // Arrays. |
| let a: Bar<[i32; 3]> = Bar { x: &[1, 2, 3] }; |
| // This is the actual coercion. |
| let b: Bar<[i32]> = a; |
| |
| unsafe { |
| assert_eq!((*b.x)[0], 1); |
| assert_eq!((*b.x)[1], 2); |
| assert_eq!((*b.x)[2], 3); |
| } |
| |
| // Trait objects. |
| let a: Bar<i32> = Bar { x: &42 }; |
| let b: Bar<dyn Baz> = a; |
| unsafe { |
| assert_eq!((*b.x).get(), 42); |
| } |
| } |