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//@ run-pass
#![allow(unused_imports)]
// Test for an ICE that occurred when a default method implementation
// was applied to a type that did not meet the prerequisites. The
// problem occurred specifically because normalizing
// `Self::Item::Target` was impossible in this case.
use std::boxed::Box;
use std::marker::Sized;
use std::clone::Clone;
use std::ops::Deref;
use std::option::Option;
use std::option::Option::{Some,None};
trait Iterator {
type Item;
fn next(&mut self) -> Option<Self::Item>;
fn clone_first(mut self) -> Option<<Self::Item as Deref>::Target> where //~ WARN method `clone_first` is never used
Self: Sized,
Self::Item: Deref,
<Self::Item as Deref>::Target: Clone,
{
self.next().map(|x| x.clone())
}
}
struct Counter {
value: i32
}
struct Token {
value: i32
}
impl Iterator for Counter {
type Item = Token;
fn next(&mut self) -> Option<Token> {
let x = self.value;
self.value += 1;
Some(Token { value: x })
}
}
fn main() {
let mut x: Box<dyn Iterator<Item=Token>> = Box::new(Counter { value: 22 });
assert_eq!(x.next().unwrap().value, 22);
}
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