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trait Cycle: Sized {
type Next: Cycle<Next = Self>;
}
impl<T> Cycle for Box<T> {
type Next = Vec<T>;
}
impl<T> Cycle for Vec<T> {
type Next = Box<T>;
}
trait X<'a, T: Cycle + for<'b> X<'b, T>>
where
for<'b> <T as X<'b, T>>::U: Clone,
for<'b> T::Next: X<'b, T::Next>,
for<'b> <T::Next as X<'b, T::Next>>::U: Clone,
{
type U: ?Sized;
fn f(x: &<T as X<'_, T>>::U) {
<<T as X<'_, T>>::U>::clone(x);
}
}
impl<S, T> X<'_, Vec<T>> for S {
type U = str;
//~^ ERROR the trait bound `str: Clone` is not satisfied
}
impl<S, T> X<'_, Box<T>> for S {
type U = str;
//~^ ERROR the trait bound `str: Clone` is not satisfied
}
pub fn main() {
<i32 as X<Box<i32>>>::f("abc");
}
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