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// 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);
}
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