8355389e3e
When deriving Hash, RustcEncodable and RustcDecodable, the syntax extension needs a type parameter to use in the inner method. They used to use __H, __S and __D respectively. If this conflicts with a type parameter already declared for the item, bad times result (see the test). There is no hygiene for type parameters, but this commit introduces a better heuristic by concatenating the names of all extant type parameters (and prepending __H).
47 lines
1.2 KiB
Rust
47 lines
1.2 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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#![feature(hash_default)]
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use std::hash::{Hash, SipHasher, Hasher};
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#[derive(Hash)]
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struct Person {
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id: usize,
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name: String,
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phone: usize,
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}
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// test for hygiene name collisions
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#[derive(Hash)] struct __H__H;
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#[derive(Hash)] enum Collision<__H> { __H { __H__H: __H } }
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fn hash<T: Hash>(t: &T) -> u64 {
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let mut s = SipHasher::new_with_keys(0, 0);
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t.hash(&mut s);
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s.finish()
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}
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fn main() {
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let person1 = Person {
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id: 5,
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name: "Janet".to_string(),
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phone: 555_666_7777
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};
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let person2 = Person {
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id: 5,
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name: "Bob".to_string(),
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phone: 555_666_7777
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};
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assert_eq!(hash(&person1), hash(&person1));
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assert!(hash(&person1) != hash(&person2));
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}
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