c61a0092bc
This is a [breaking-change]. The new rules require that, for an impl of a trait defined
in some other crate, two conditions must hold:
1. Some type must be local.
2. Every type parameter must appear "under" some local type.
Here are some examples that are legal:
```rust
struct MyStruct<T> { ... }
// Here `T` appears "under' `MyStruct`.
impl<T> Clone for MyStruct<T> { }
// Here `T` appears "under' `MyStruct` as well. Note that it also appears
// elsewhere.
impl<T> Iterator<T> for MyStruct<T> { }
```
Here is an illegal example:
```rust
// Here `U` does not appear "under" `MyStruct` or any other local type.
// We call `U` "uncovered".
impl<T,U> Iterator<U> for MyStruct<T> { }
```
There are a couple of ways to rewrite this last example so that it is
legal:
1. In some cases, the uncovered type parameter (here, `U`) should be converted
into an associated type. This is however a non-local change that requires access
to the original trait. Also, associated types are not fully baked.
2. Add `U` as a type parameter of `MyStruct`:
```rust
struct MyStruct<T,U> { ... }
impl<T,U> Iterator<U> for MyStruct<T,U> { }
```
3. Create a newtype wrapper for `U`
```rust
impl<T,U> Iterator<Wrapper<U>> for MyStruct<T,U> { }
```
Because associated types are not fully baked, which in the case of the
`Hash` trait makes adhering to this rule impossible, you can
temporarily disable this rule in your crate by using
`#![feature(old_orphan_check)]`. Note that the `old_orphan_check`
feature will be removed before 1.0 is released.
140 lines
3.2 KiB
Rust
140 lines
3.2 KiB
Rust
// Copyright 2012-2013 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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//! The Rust compiler.
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//!
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//! # Note
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//!
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//! This API is completely unstable and subject to change.
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#![crate_name = "rustc"]
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#![experimental]
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#![crate_type = "dylib"]
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#![crate_type = "rlib"]
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#![doc(html_logo_url = "http://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
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html_favicon_url = "http://www.rust-lang.org/favicon.ico",
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html_root_url = "http://doc.rust-lang.org/nightly/")]
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#![allow(unknown_features)]
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#![feature(default_type_params, globs, macro_rules, phase, quote)]
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#![feature(slicing_syntax, unsafe_destructor)]
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#![feature(rustc_diagnostic_macros)]
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#![feature(unboxed_closures)]
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#![feature(old_orphan_check)]
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extern crate arena;
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extern crate flate;
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extern crate getopts;
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extern crate graphviz;
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extern crate libc;
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extern crate rustc_llvm;
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extern crate rustc_back;
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extern crate serialize;
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extern crate rbml;
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extern crate collections;
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#[phase(plugin, link)] extern crate log;
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#[phase(plugin, link)] extern crate syntax;
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extern crate "serialize" as rustc_serialize; // used by deriving
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#[cfg(test)]
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extern crate test;
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pub use rustc_llvm as llvm;
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mod diagnostics;
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pub mod back {
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pub use rustc_back::abi;
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pub use rustc_back::archive;
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pub use rustc_back::arm;
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pub use rustc_back::mips;
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pub use rustc_back::mipsel;
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pub use rustc_back::rpath;
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pub use rustc_back::svh;
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pub use rustc_back::target_strs;
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pub use rustc_back::x86;
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pub use rustc_back::x86_64;
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}
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pub mod middle {
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pub mod astconv_util;
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pub mod astencode;
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pub mod cfg;
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pub mod check_const;
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pub mod check_static_recursion;
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pub mod check_loop;
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pub mod check_match;
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pub mod check_rvalues;
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pub mod check_static;
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pub mod const_eval;
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pub mod dataflow;
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pub mod dead;
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pub mod def;
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pub mod dependency_format;
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pub mod effect;
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pub mod entry;
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pub mod expr_use_visitor;
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pub mod fast_reject;
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pub mod graph;
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pub mod intrinsicck;
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pub mod infer;
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pub mod lang_items;
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pub mod liveness;
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pub mod mem_categorization;
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pub mod pat_util;
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pub mod privacy;
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pub mod reachable;
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pub mod region;
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pub mod recursion_limit;
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pub mod resolve_lifetime;
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pub mod stability;
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pub mod subst;
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pub mod traits;
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pub mod ty;
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pub mod ty_fold;
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pub mod ty_walk;
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pub mod weak_lang_items;
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}
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pub mod metadata;
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pub mod session;
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pub mod plugin;
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pub mod lint;
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pub mod util {
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pub use rustc_back::fs;
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pub use rustc_back::sha2;
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pub mod common;
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pub mod ppaux;
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pub mod nodemap;
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pub mod snapshot_vec;
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pub mod lev_distance;
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}
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pub mod lib {
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pub use llvm;
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}
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__build_diagnostic_array! { DIAGNOSTICS }
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// A private module so that macro-expanded idents like
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// `::rustc::lint::Lint` will also work in `rustc` itself.
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//
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// `libstd` uses the same trick.
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#[doc(hidden)]
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mod rustc {
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pub use lint;
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}
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