096a28607f
This change makes the compiler no longer infer whether types (structures
and enumerations) implement the `Copy` trait (and thus are implicitly
copyable). Rather, you must implement `Copy` yourself via `impl Copy for
MyType {}`.
A new warning has been added, `missing_copy_implementations`, to warn
you if a non-generic public type has been added that could have
implemented `Copy` but didn't.
For convenience, you may *temporarily* opt out of this behavior by using
`#![feature(opt_out_copy)]`. Note though that this feature gate will never be
accepted and will be removed by the time that 1.0 is released, so you should
transition your code away from using it.
This breaks code like:
#[deriving(Show)]
struct Point2D {
x: int,
y: int,
}
fn main() {
let mypoint = Point2D {
x: 1,
y: 1,
};
let otherpoint = mypoint;
println!("{}{}", mypoint, otherpoint);
}
Change this code to:
#[deriving(Show)]
struct Point2D {
x: int,
y: int,
}
impl Copy for Point2D {}
fn main() {
let mypoint = Point2D {
x: 1,
y: 1,
};
let otherpoint = mypoint;
println!("{}{}", mypoint, otherpoint);
}
This is the backwards-incompatible part of #13231.
Part of RFC #3.
[breaking-change]
98 lines
2.8 KiB
Rust
98 lines
2.8 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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//! An efficient hash map for node IDs
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#![allow(non_snake_case)]
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use std::collections::{HashMap, HashSet};
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use std::hash::{Hasher, Hash, Writer};
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use syntax::ast;
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pub type FnvHashMap<K, V> = HashMap<K, V, FnvHasher>;
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pub type FnvHashSet<V> = HashSet<V, FnvHasher>;
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pub type NodeMap<T> = FnvHashMap<ast::NodeId, T>;
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pub type DefIdMap<T> = FnvHashMap<ast::DefId, T>;
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pub type NodeSet = FnvHashSet<ast::NodeId>;
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pub type DefIdSet = FnvHashSet<ast::DefId>;
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// Hacks to get good names
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pub mod FnvHashMap {
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use std::hash::Hash;
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use std::collections::HashMap;
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pub fn new<K: Hash<super::FnvState> + Eq, V>() -> super::FnvHashMap<K, V> {
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HashMap::with_hasher(super::FnvHasher)
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}
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}
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pub mod FnvHashSet {
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use std::hash::Hash;
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use std::collections::HashSet;
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pub fn new<V: Hash<super::FnvState> + Eq>() -> super::FnvHashSet<V> {
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HashSet::with_hasher(super::FnvHasher)
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}
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}
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pub mod NodeMap {
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pub fn new<T>() -> super::NodeMap<T> {
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super::FnvHashMap::new()
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}
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}
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pub mod DefIdMap {
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pub fn new<T>() -> super::DefIdMap<T> {
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super::FnvHashMap::new()
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}
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}
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pub mod NodeSet {
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pub fn new() -> super::NodeSet {
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super::FnvHashSet::new()
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}
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}
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pub mod DefIdSet {
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pub fn new() -> super::DefIdSet {
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super::FnvHashSet::new()
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}
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}
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/// A speedy hash algorithm for node ids and def ids. The hashmap in
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/// libcollections by default uses SipHash which isn't quite as speedy as we
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/// want. In the compiler we're not really worried about DOS attempts, so we
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/// just default to a non-cryptographic hash.
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///
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/// This uses FNV hashing, as described here:
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/// http://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function
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#[deriving(Clone, Default)]
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pub struct FnvHasher;
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impl Copy for FnvHasher {}
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#[allow(missing_copy_implementations)]
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pub struct FnvState(u64);
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impl Hasher<FnvState> for FnvHasher {
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fn hash<Sized? T: Hash<FnvState>>(&self, t: &T) -> u64 {
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let mut state = FnvState(0xcbf29ce484222325);
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t.hash(&mut state);
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let FnvState(ret) = state;
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return ret;
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}
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}
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impl Writer for FnvState {
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fn write(&mut self, bytes: &[u8]) {
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let FnvState(mut hash) = *self;
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for byte in bytes.iter() {
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hash = hash ^ (*byte as u64);
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hash = hash * 0x100000001b3;
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}
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*self = FnvState(hash);
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}
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}
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