Add test for issue-44861

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Yuki Okushi 2020-06-23 17:52:01 +09:00
parent 3b1c08c68c
commit bb882d74bd
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2 changed files with 52 additions and 0 deletions

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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 MaybeObjectSafe {}
impl MaybeObjectSafe for () {}
impl<T> Smartass for T {
type Data = <Self as Smartass>::Data2;
default type Data2 = ();
//~^ ERROR: the trait bound `(): std::ops::CoerceUnsized<*const [u8]>` is not satisfied
}
impl Smartass for () {
type Data2 = *const [u8; 1];
}
impl Smartass for dyn MaybeObjectSafe {
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 MaybeObjectSafe> {
s
}

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error[E0277]: the trait bound `(): std::ops::CoerceUnsized<*const [u8]>` is not satisfied
--> $DIR/issue-44861.rs:21:5
|
LL | type Data2: CoerceUnsized<*const [u8]>;
| --------------------------------------- required by `Smartass::Data2`
...
LL | default type Data2 = ();
| ^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::ops::CoerceUnsized<*const [u8]>` is not implemented for `()`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0277`.