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1 | // Copyright 2014 The Rust Project Developers. See the COPYRIGHT |
2 | // file at the top-level directory of this distribution and at | |
3 | // http://rust-lang.org/COPYRIGHT. | |
4 | // | |
5 | // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | |
6 | // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | |
7 | // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | |
8 | // option. This file may not be copied, modified, or distributed | |
9 | // except according to those terms. | |
10 | ||
11 | // Test how resolving a projection interacts with inference. In this | |
12 | // case, we were eagerly unifying the type variable for the iterator | |
13 | // type with `I` from the where clause, ignoring the in-scope `impl` | |
14 | // for `ByRef`. The right answer was to consider the result ambiguous | |
15 | // until more type information was available. | |
16 | ||
1a4d82fc JJ |
17 | #![feature(lang_items, unboxed_closures)] |
18 | #![no_implicit_prelude] | |
19 | ||
20 | use std::marker::Sized; | |
21 | use std::option::Option::{None, Some, self}; | |
22 | ||
23 | trait Iterator { | |
24 | type Item; | |
25 | ||
26 | fn next(&mut self) -> Option<Self::Item>; | |
27 | } | |
28 | ||
29 | trait IteratorExt: Iterator + Sized { | |
30 | fn by_ref(&mut self) -> ByRef<Self> { | |
31 | ByRef(self) | |
32 | } | |
33 | } | |
34 | ||
35 | impl<I> IteratorExt for I where I: Iterator {} | |
36 | ||
37 | struct ByRef<'a, I: 'a + Iterator>(&'a mut I); | |
38 | ||
39 | impl<'a, I: Iterator> Iterator for ByRef<'a, I> { | |
40 | type Item = I::Item; | |
41 | ||
42 | fn next(&mut self) -> Option< <I as Iterator>::Item > { | |
43 | self.0.next() | |
44 | } | |
45 | } | |
46 | ||
47 | fn is_iterator_of<A, I: Iterator<Item=A>>(_: &I) {} | |
48 | ||
49 | fn test<A, I: Iterator<Item=A>>(mut it: I) { | |
50 | is_iterator_of::<A, _>(&it.by_ref()); | |
51 | } | |
52 | ||
53 | fn test2<A, I1: Iterator<Item=A>, I2: Iterator<Item=I1::Item>>(mut it: I2) { | |
54 | is_iterator_of::<A, _>(&it) | |
55 | } | |
56 | ||
57 | fn main() { } |