2 #![feature(coerce_unsized, unsize)]
4 use std::ops::CoerceUnsized;
5 use std::marker::Unsize;
7 fn identity_coercion(x: &(dyn Fn(u32)->u32 + Send)) -> &dyn Fn(u32)->u32 {
10 fn fn_coercions(f: &fn(u32) -> u32) ->
11 (unsafe fn(u32) -> u32,
12 &(dyn Fn(u32) -> u32+Send))
17 fn simple_array_coercion(x: &[u8; 3]) -> &[u8] { x }
19 fn square(a: u32) -> u32 { a * a }
21 #[derive(PartialEq,Eq)]
22 struct PtrWrapper<'a, T: 'a+?Sized>(u32, u32, (), &'a T);
23 impl<'a, T: ?Sized+Unsize<U>, U: ?Sized>
24 CoerceUnsized<PtrWrapper<'a, U>> for PtrWrapper<'a, T> {}
26 struct TrivPtrWrapper<'a, T: 'a+?Sized>(&'a T);
27 impl<'a, T: ?Sized+Unsize<U>, U: ?Sized>
28 CoerceUnsized<TrivPtrWrapper<'a, U>> for TrivPtrWrapper<'a, T> {}
30 fn coerce_ptr_wrapper(p: PtrWrapper<[u8; 3]>) -> PtrWrapper<[u8]> {
34 fn coerce_triv_ptr_wrapper(p: TrivPtrWrapper<[u8; 3]>) -> TrivPtrWrapper<[u8]> {
38 fn coerce_fat_ptr_wrapper(p: PtrWrapper<dyn Fn(u32) -> u32+Send>)
39 -> PtrWrapper<dyn Fn(u32) -> u32> {
43 fn coerce_ptr_wrapper_poly<'a, T, Trait: ?Sized>(p: PtrWrapper<'a, T>)
44 -> PtrWrapper<'a, Trait>
45 where PtrWrapper<'a, T>: CoerceUnsized<PtrWrapper<'a, Trait>>
52 let square_local : fn(u32) -> u32 = square;
53 let (f,g) = fn_coercions(&square_local);
54 assert_eq!(f as usize, square as usize);
56 assert_eq!(identity_coercion(g)(5), 25);
58 assert_eq!(simple_array_coercion(&a), &a);
59 let w = coerce_ptr_wrapper(PtrWrapper(2,3,(),&a));
60 assert!(w == PtrWrapper(2,3,(),&a) as PtrWrapper<[u8]>);
62 let w = coerce_triv_ptr_wrapper(TrivPtrWrapper(&a));
65 let z = coerce_fat_ptr_wrapper(PtrWrapper(2,3,(),&square_local));
66 assert_eq!((z.3)(6), 36);
68 let z: PtrWrapper<dyn Fn(u32) -> u32> =
69 coerce_ptr_wrapper_poly(PtrWrapper(2,3,(),&square_local));
70 assert_eq!((z.3)(6), 36);