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#![feature(specialization)] //~ WARN the feature `specialization` is incomplete
// Regression test for a specialization-related ICE (#39448).
trait A: Sized {
fn foo(self, _: Self) -> Self {
self
}
}
impl A for u8 {}
impl A for u16 {}
impl FromA<u8> for u16 {
fn from(x: u8) -> u16 {
x as u16
}
}
trait FromA<T> {
fn from(t: T) -> Self;
}
impl<T: A, U: A + FromA<T>> FromA<T> for U {
//~^ ERROR cycle detected when computing whether impls specialize one another
default fn from(x: T) -> Self {
ToA::to(x)
}
}
trait ToA<T> {
fn to(self) -> T;
}
impl<T, U> ToA<U> for T
where
U: FromA<T>,
{
fn to(self) -> U {
U::from(self)
}
}
#[allow(dead_code)]
fn foo<T: A, U: A>(x: T, y: U) -> U {
x.foo(y.to()).to()
}
fn main() {
let z = foo(8u8, 1u16);
}
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