rust/tests/ui-fulldeps/deriving-encodable-decodable-box.rs

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// run-pass
#![allow(unused_imports)]
#![feature(rustc_private)]
Fix orphan checking (cc #19470). (This is not a complete fix of #19470 because of the backwards compatibility feature gate.) 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.
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extern crate rustc_macros;
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extern crate rustc_serialize;
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// Necessary to pull in object code as the rest of the rustc crates are shipped only as rmeta
// files.
#[allow(unused_extern_crates)]
extern crate rustc_driver;
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use rustc_macros::{Decodable, Encodable};
use rustc_serialize::opaque::{MemDecoder, MemEncoder};
Use delayed error handling for `Encodable` and `Encoder` infallible. There are two impls of the `Encoder` trait: `opaque::Encoder` and `opaque::FileEncoder`. The former encodes into memory and is infallible, the latter writes to file and is fallible. Currently, standard `Result`/`?`/`unwrap` error handling is used, but this is a bit verbose and has non-trivial cost, which is annoying given how rare failures are (especially in the infallible `opaque::Encoder` case). This commit changes how `Encoder` fallibility is handled. All the `emit_*` methods are now infallible. `opaque::Encoder` requires no great changes for this. `opaque::FileEncoder` now implements a delayed error handling strategy. If a failure occurs, it records this via the `res` field, and all subsequent encoding operations are skipped if `res` indicates an error has occurred. Once encoding is complete, the new `finish` method is called, which returns a `Result`. In other words, there is now a single `Result`-producing method instead of many of them. This has very little effect on how any file errors are reported if `opaque::FileEncoder` has any failures. Much of this commit is boring mechanical changes, removing `Result` return values and `?` or `unwrap` from expressions. The more interesting parts are as follows. - serialize.rs: The `Encoder` trait gains an `Ok` associated type. The `into_inner` method is changed into `finish`, which returns `Result<Vec<u8>, !>`. - opaque.rs: The `FileEncoder` adopts the delayed error handling strategy. Its `Ok` type is a `usize`, returning the number of bytes written, replacing previous uses of `FileEncoder::position`. - Various methods that take an encoder now consume it, rather than being passed a mutable reference, e.g. `serialize_query_result_cache`.
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use rustc_serialize::{Decodable, Encodable, Encoder};
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#[derive(Encodable, Decodable)]
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struct A {
foo: Box<[bool]>,
}
fn main() {
let obj = A { foo: Box::new([true, false]) };
Use delayed error handling for `Encodable` and `Encoder` infallible. There are two impls of the `Encoder` trait: `opaque::Encoder` and `opaque::FileEncoder`. The former encodes into memory and is infallible, the latter writes to file and is fallible. Currently, standard `Result`/`?`/`unwrap` error handling is used, but this is a bit verbose and has non-trivial cost, which is annoying given how rare failures are (especially in the infallible `opaque::Encoder` case). This commit changes how `Encoder` fallibility is handled. All the `emit_*` methods are now infallible. `opaque::Encoder` requires no great changes for this. `opaque::FileEncoder` now implements a delayed error handling strategy. If a failure occurs, it records this via the `res` field, and all subsequent encoding operations are skipped if `res` indicates an error has occurred. Once encoding is complete, the new `finish` method is called, which returns a `Result`. In other words, there is now a single `Result`-producing method instead of many of them. This has very little effect on how any file errors are reported if `opaque::FileEncoder` has any failures. Much of this commit is boring mechanical changes, removing `Result` return values and `?` or `unwrap` from expressions. The more interesting parts are as follows. - serialize.rs: The `Encoder` trait gains an `Ok` associated type. The `into_inner` method is changed into `finish`, which returns `Result<Vec<u8>, !>`. - opaque.rs: The `FileEncoder` adopts the delayed error handling strategy. Its `Ok` type is a `usize`, returning the number of bytes written, replacing previous uses of `FileEncoder::position`. - Various methods that take an encoder now consume it, rather than being passed a mutable reference, e.g. `serialize_query_result_cache`.
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let mut encoder = MemEncoder::new();
Use delayed error handling for `Encodable` and `Encoder` infallible. There are two impls of the `Encoder` trait: `opaque::Encoder` and `opaque::FileEncoder`. The former encodes into memory and is infallible, the latter writes to file and is fallible. Currently, standard `Result`/`?`/`unwrap` error handling is used, but this is a bit verbose and has non-trivial cost, which is annoying given how rare failures are (especially in the infallible `opaque::Encoder` case). This commit changes how `Encoder` fallibility is handled. All the `emit_*` methods are now infallible. `opaque::Encoder` requires no great changes for this. `opaque::FileEncoder` now implements a delayed error handling strategy. If a failure occurs, it records this via the `res` field, and all subsequent encoding operations are skipped if `res` indicates an error has occurred. Once encoding is complete, the new `finish` method is called, which returns a `Result`. In other words, there is now a single `Result`-producing method instead of many of them. This has very little effect on how any file errors are reported if `opaque::FileEncoder` has any failures. Much of this commit is boring mechanical changes, removing `Result` return values and `?` or `unwrap` from expressions. The more interesting parts are as follows. - serialize.rs: The `Encoder` trait gains an `Ok` associated type. The `into_inner` method is changed into `finish`, which returns `Result<Vec<u8>, !>`. - opaque.rs: The `FileEncoder` adopts the delayed error handling strategy. Its `Ok` type is a `usize`, returning the number of bytes written, replacing previous uses of `FileEncoder::position`. - Various methods that take an encoder now consume it, rather than being passed a mutable reference, e.g. `serialize_query_result_cache`.
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obj.encode(&mut encoder);
let data = encoder.finish();
Use delayed error handling for `Encodable` and `Encoder` infallible. There are two impls of the `Encoder` trait: `opaque::Encoder` and `opaque::FileEncoder`. The former encodes into memory and is infallible, the latter writes to file and is fallible. Currently, standard `Result`/`?`/`unwrap` error handling is used, but this is a bit verbose and has non-trivial cost, which is annoying given how rare failures are (especially in the infallible `opaque::Encoder` case). This commit changes how `Encoder` fallibility is handled. All the `emit_*` methods are now infallible. `opaque::Encoder` requires no great changes for this. `opaque::FileEncoder` now implements a delayed error handling strategy. If a failure occurs, it records this via the `res` field, and all subsequent encoding operations are skipped if `res` indicates an error has occurred. Once encoding is complete, the new `finish` method is called, which returns a `Result`. In other words, there is now a single `Result`-producing method instead of many of them. This has very little effect on how any file errors are reported if `opaque::FileEncoder` has any failures. Much of this commit is boring mechanical changes, removing `Result` return values and `?` or `unwrap` from expressions. The more interesting parts are as follows. - serialize.rs: The `Encoder` trait gains an `Ok` associated type. The `into_inner` method is changed into `finish`, which returns `Result<Vec<u8>, !>`. - opaque.rs: The `FileEncoder` adopts the delayed error handling strategy. Its `Ok` type is a `usize`, returning the number of bytes written, replacing previous uses of `FileEncoder::position`. - Various methods that take an encoder now consume it, rather than being passed a mutable reference, e.g. `serialize_query_result_cache`.
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let mut decoder = MemDecoder::new(&data, 0);
let obj2 = A::decode(&mut decoder);
Use delayed error handling for `Encodable` and `Encoder` infallible. There are two impls of the `Encoder` trait: `opaque::Encoder` and `opaque::FileEncoder`. The former encodes into memory and is infallible, the latter writes to file and is fallible. Currently, standard `Result`/`?`/`unwrap` error handling is used, but this is a bit verbose and has non-trivial cost, which is annoying given how rare failures are (especially in the infallible `opaque::Encoder` case). This commit changes how `Encoder` fallibility is handled. All the `emit_*` methods are now infallible. `opaque::Encoder` requires no great changes for this. `opaque::FileEncoder` now implements a delayed error handling strategy. If a failure occurs, it records this via the `res` field, and all subsequent encoding operations are skipped if `res` indicates an error has occurred. Once encoding is complete, the new `finish` method is called, which returns a `Result`. In other words, there is now a single `Result`-producing method instead of many of them. This has very little effect on how any file errors are reported if `opaque::FileEncoder` has any failures. Much of this commit is boring mechanical changes, removing `Result` return values and `?` or `unwrap` from expressions. The more interesting parts are as follows. - serialize.rs: The `Encoder` trait gains an `Ok` associated type. The `into_inner` method is changed into `finish`, which returns `Result<Vec<u8>, !>`. - opaque.rs: The `FileEncoder` adopts the delayed error handling strategy. Its `Ok` type is a `usize`, returning the number of bytes written, replacing previous uses of `FileEncoder::position`. - Various methods that take an encoder now consume it, rather than being passed a mutable reference, e.g. `serialize_query_result_cache`.
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assert_eq!(obj.foo, obj2.foo);
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}