50 lines
1010 B
Rust
50 lines
1010 B
Rust
//@ compile-flags: -Z mir-opt-level=3
|
|
|
|
#![feature(type_alias_impl_trait, rustc_attrs)]
|
|
|
|
use std::marker::PhantomData;
|
|
|
|
trait MyIndex<T> {
|
|
type O;
|
|
fn my_index(self) -> Self::O;
|
|
}
|
|
trait MyFrom<T>: Sized {
|
|
type Error;
|
|
fn my_from(value: T) -> Result<Self, Self::Error>;
|
|
}
|
|
|
|
trait F {}
|
|
impl F for () {}
|
|
type DummyT<T> = impl F;
|
|
fn _dummy_t<T>() -> DummyT<T> {}
|
|
|
|
struct Phantom1<T>(PhantomData<T>);
|
|
struct Phantom2<T>(PhantomData<T>);
|
|
struct Scope<T>(Phantom2<DummyT<T>>);
|
|
|
|
impl<T> Scope<T> {
|
|
fn new() -> Self {
|
|
unimplemented!()
|
|
}
|
|
}
|
|
|
|
impl<T> MyFrom<Phantom2<T>> for Phantom1<T> {
|
|
type Error = ();
|
|
fn my_from(_: Phantom2<T>) -> Result<Self, Self::Error> {
|
|
unimplemented!()
|
|
}
|
|
}
|
|
|
|
impl<T: MyFrom<Phantom2<DummyT<U>>>, U> MyIndex<Phantom1<T>> for Scope<U> {
|
|
type O = T;
|
|
fn my_index(self) -> Self::O {
|
|
MyFrom::my_from(self.0).ok().unwrap()
|
|
}
|
|
}
|
|
|
|
#[rustc_error]
|
|
fn main() {
|
|
//~^ ERROR
|
|
let _pos: Phantom1<DummyT<()>> = Scope::new().my_index();
|
|
}
|