mirror of
https://github.com/rust-lang/rust.git
synced 2024-11-23 15:23:46 +00:00
36 lines
651 B
Rust
36 lines
651 B
Rust
// revisions: current next
|
|
//[next] compile-flags: -Ztrait-solver=next
|
|
|
|
#![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
|
|
}
|