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#![feature(unsize)]
use std::marker::Unsize;
pub trait CastTo<T: ?Sized>: Unsize<T> {
fn cast_to(&self) -> &T;
}
impl<T: ?Sized, U: ?Sized + Unsize<T>> CastTo<T> for U {
fn cast_to(&self) -> &T {
self
}
}
impl<T: ?Sized> Cast for T {}
pub trait Cast {
fn cast<T: ?Sized>(&self) -> &T
where
Self: CastTo<T>,
{
self
}
}
pub trait Foo: CastTo<[i32]> {}
impl Foo for [i32; 0] {}
fn main() {
let x: &dyn Foo = &[];
let x = x.cast::<[i32]>();
//~^ ERROR: the trait bound `dyn Foo: CastTo<[i32]>` is not satisfied
}
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