| // Test that coherence detects overlap when some of the types in the |
| // impls are projections of associated type. Issue #20624. |
| |
| use std::marker::PhantomData; |
| use std::ops::Deref; |
| |
| pub struct Cow<'a, B: ?Sized>(PhantomData<(&'a (),B)>); |
| |
| /// Trait for moving into a `Cow` |
| pub trait IntoCow<'a, B: ?Sized> { |
| /// Moves `self` into `Cow` |
| fn into_cow(self) -> Cow<'a, B>; |
| } |
| |
| impl<'a, B: ?Sized> IntoCow<'a, B> for <B as ToOwned>::Owned where B: ToOwned { |
| fn into_cow(self) -> Cow<'a, B> { |
| Cow(PhantomData) |
| } |
| } |
| |
| impl<'a, B: ?Sized> IntoCow<'a, B> for Cow<'a, B> where B: ToOwned { |
| //~^ ERROR E0119 |
| fn into_cow(self) -> Cow<'a, B> { |
| self |
| } |
| } |
| |
| impl<'a, B: ?Sized> IntoCow<'a, B> for &'a B where B: ToOwned { |
| //~^ ERROR E0119 |
| fn into_cow(self) -> Cow<'a, B> { |
| Cow(PhantomData) |
| } |
| } |
| |
| impl ToOwned for u8 { |
| type Owned = &'static u8; |
| fn to_owned(&self) -> &'static u8 { panic!() } |
| } |
| |
| /// A generalization of Clone to borrowed data. |
| pub trait ToOwned { |
| type Owned; |
| |
| /// Creates owned data from borrowed data, usually by copying. |
| fn to_owned(&self) -> Self::Owned; |
| } |
| |
| |
| fn main() {} |