1 #![feature(unsize, dispatch_from_dyn)]
2 
3 use std::{
4     ops::DispatchFromDyn,
5     marker::{Unsize, PhantomData},
6 };
7 
8 struct WrapperWithExtraField<T>(T, i32);
9 
10 impl<T, U> DispatchFromDyn<WrapperWithExtraField<U>> for WrapperWithExtraField<T>
11 where
12     T: DispatchFromDyn<U>,
13 {} //~^^^ ERROR [E0378]
14 
15 
16 struct MultiplePointers<T: ?Sized>{
17     ptr1: *const T,
18     ptr2: *const T,
19 }
20 
21 impl<T: ?Sized, U: ?Sized> DispatchFromDyn<MultiplePointers<U>> for MultiplePointers<T>
22 where
23     T: Unsize<U>,
24 {} //~^^^ ERROR [E0378]
25 
26 
27 struct NothingToCoerce<T: ?Sized> {
28     data: PhantomData<T>,
29 }
30 
31 impl<T: ?Sized, U: ?Sized> DispatchFromDyn<NothingToCoerce<T>> for NothingToCoerce<U> {}
32 //~^ ERROR [E0378]
33 
34 #[repr(C)]
35 struct HasReprC<T: ?Sized>(Box<T>);
36 
37 impl<T: ?Sized, U: ?Sized> DispatchFromDyn<HasReprC<U>> for HasReprC<T>
38 where
39     T: Unsize<U>,
40 {} //~^^^ ERROR [E0378]
41 
42 #[repr(align(64))]
43 struct OverAlignedZst;
44 struct OverAligned<T: ?Sized>(Box<T>, OverAlignedZst);
45 
46 impl<T: ?Sized, U: ?Sized> DispatchFromDyn<OverAligned<U>> for OverAligned<T>
47     where
48         T: Unsize<U>,
49 {} //~^^^ ERROR [E0378]
50 
main()51 fn main() {}
52