rollup merge of #20608: nikomatsakis/assoc-types-method-dispatch

This commit is contained in:
Alex Crichton 2015-01-05 18:56:45 -08:00
commit 563f6d8218
3 changed files with 153 additions and 13 deletions

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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// Test that we handle projection types which wind up important for
// resolving methods. This test was reduced from a larger example; the
// call to `foo()` at the end was failing to resolve because the
// winnowing stage of method resolution failed to handle an associated
// type projection.
#![feature(associated_types)]
trait Hasher {
type Output;
fn finish(&self) -> Self::Output;
}
trait Hash<H: Hasher> {
fn hash(&self, h: &mut H);
}
trait HashState {
type Wut: Hasher;
fn hasher(&self) -> Self::Wut;
}
struct SipHasher;
impl Hasher for SipHasher {
type Output = u64;
fn finish(&self) -> u64 { 4 }
}
impl Hash<SipHasher> for int {
fn hash(&self, h: &mut SipHasher) {}
}
struct SipState;
impl HashState for SipState {
type Wut = SipHasher;
fn hasher(&self) -> SipHasher { SipHasher }
}
struct Map<S> {
s: S,
}
impl<S> Map<S>
where S: HashState,
<S as HashState>::Wut: Hasher<Output=u64>,
{
fn foo<K>(&self, k: K) where K: Hash< <S as HashState>::Wut> {}
}
fn foo<K: Hash<SipHasher>>(map: &Map<SipState>) {
map.foo(22);
}
fn main() {}

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// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// Test that we can use method notation to call methods based on a
// where clause type, and not only type parameters.
trait Foo {
fn foo(&self) -> int;
}
impl Foo for Option<int>
{
fn foo(&self) -> int {
self.unwrap_or(22)
}
}
impl Foo for Option<uint>
{
fn foo(&self) -> int {
self.unwrap_or(22) as int
}
}
fn check<T>(x: Option<T>) -> (int, int)
where Option<T> : Foo
{
let y: Option<T> = None;
(x.foo(), y.foo())
}
fn main() {
assert_eq!(check(Some(23u)), (23i, 22i));
assert_eq!(check(Some(23i)), (23i, 22i));
}