59 lines
1.5 KiB
Rust
59 lines
1.5 KiB
Rust
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// Test for an ICE that occurred when a default method implementation
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// was applied to a type that did not meet the prerequisites. The
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// problem occurred specifically because normalizing
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// `Self::Item::Target` was impossible in this case.
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use std::boxed::Box;
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use std::marker::Sized;
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use std::clone::Clone;
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use std::ops::Deref;
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use std::option::Option;
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use std::option::Option::{Some,None};
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trait Iterator {
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type Item;
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fn next(&mut self) -> Option<Self::Item>;
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fn clone_first(mut self) -> Option<<Self::Item as Deref>::Target> where
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Self: Sized,
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Self::Item: Deref,
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<Self::Item as Deref>::Target: Clone,
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{
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self.next().map(|x| x.clone())
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}
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}
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struct Counter {
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value: i32
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}
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struct Token {
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value: i32
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}
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impl Iterator for Counter {
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type Item = Token;
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fn next(&mut self) -> Option<Token> {
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let x = self.value;
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self.value += 1;
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Some(Token { value: x })
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}
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}
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fn main() {
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let mut x: Box<Iterator<Item=Token>> = Box::new(Counter { value: 22 });
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assert_eq!(x.next().unwrap().value, 22);
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}
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