1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
|
// 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() {}
|
