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