| //@ 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); |
| } |
