| // run-pass |
| #![feature(arbitrary_self_types, unsize, coerce_unsized, dispatch_from_dyn)] |
| #![feature(rustc_attrs)] |
| |
| use std::{ |
| ops::{Deref, CoerceUnsized, DispatchFromDyn}, |
| marker::Unsize, |
| }; |
| |
| struct Ptr<T: ?Sized>(Box<T>); |
| |
| impl<T: ?Sized> Deref for Ptr<T> { |
| type Target = T; |
| |
| fn deref(&self) -> &T { |
| &*self.0 |
| } |
| } |
| |
| impl<T: Unsize<U> + ?Sized, U: ?Sized> CoerceUnsized<Ptr<U>> for Ptr<T> {} |
| impl<T: Unsize<U> + ?Sized, U: ?Sized> DispatchFromDyn<Ptr<U>> for Ptr<T> {} |
| |
| struct Wrapper<T: ?Sized>(T); |
| |
| impl<T: ?Sized> Deref for Wrapper<T> { |
| type Target = T; |
| |
| fn deref(&self) -> &T { |
| &self.0 |
| } |
| } |
| |
| impl<T: CoerceUnsized<U>, U> CoerceUnsized<Wrapper<U>> for Wrapper<T> {} |
| impl<T: DispatchFromDyn<U>, U> DispatchFromDyn<Wrapper<U>> for Wrapper<T> {} |
| |
| |
| trait Trait { |
| // This method isn't object-safe yet. Unsized by-value `self` is object-safe (but not callable |
| // without unsized_locals), but wrappers arond `Self` currently are not. |
| // FIXME (mikeyhew) uncomment this when unsized rvalues object-safety is implemented |
| // fn wrapper(self: Wrapper<Self>) -> i32; |
| fn ptr_wrapper(self: Ptr<Wrapper<Self>>) -> i32; |
| fn wrapper_ptr(self: Wrapper<Ptr<Self>>) -> i32; |
| fn wrapper_ptr_wrapper(self: Wrapper<Ptr<Wrapper<Self>>>) -> i32; |
| } |
| |
| impl Trait for i32 { |
| fn ptr_wrapper(self: Ptr<Wrapper<Self>>) -> i32 { |
| **self |
| } |
| fn wrapper_ptr(self: Wrapper<Ptr<Self>>) -> i32 { |
| **self |
| } |
| fn wrapper_ptr_wrapper(self: Wrapper<Ptr<Wrapper<Self>>>) -> i32 { |
| ***self |
| } |
| } |
| |
| fn main() { |
| let pw = Ptr(Box::new(Wrapper(5))) as Ptr<Wrapper<dyn Trait>>; |
| assert_eq!(pw.ptr_wrapper(), 5); |
| |
| let wp = Wrapper(Ptr(Box::new(6))) as Wrapper<Ptr<dyn Trait>>; |
| assert_eq!(wp.wrapper_ptr(), 6); |
| |
| let wpw = Wrapper(Ptr(Box::new(Wrapper(7)))) as Wrapper<Ptr<Wrapper<dyn Trait>>>; |
| assert_eq!(wpw.wrapper_ptr_wrapper(), 7); |
| } |