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#![crate_type = "lib"]
#![feature(specialization)]
#![feature(unsize, coerce_unsized)]
#![allow(incomplete_features)]
use std::ops::CoerceUnsized;
pub struct SmartassPtr<A: Smartass+?Sized>(A::Data);
pub trait Smartass {
type Data;
type Data2: CoerceUnsized<*const [u8]>;
}
pub trait MaybeDynCompatible {}
impl MaybeDynCompatible for () {}
impl<T> Smartass for T {
type Data = <Self as Smartass>::Data2;
default type Data2 = ();
//~^ ERROR: the trait bound `(): CoerceUnsized<*const [u8]>` is not satisfied
}
impl Smartass for () {
type Data2 = *const [u8; 1];
}
impl Smartass for dyn MaybeDynCompatible {
type Data = *const [u8];
type Data2 = *const [u8; 0];
}
impl<U: Smartass+?Sized, T: Smartass+?Sized> CoerceUnsized<SmartassPtr<T>> for SmartassPtr<U>
where <U as Smartass>::Data: std::ops::CoerceUnsized<<T as Smartass>::Data>
{}
pub fn conv(s: SmartassPtr<()>) -> SmartassPtr<dyn MaybeDynCompatible> {
s
}
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