This commit is an implementation of [RFC 565][rfc] which is a stabilization of
the `std::fmt` module and the implementations of various formatting traits.
Specifically, the following changes were performed:
[rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0565-show-string-guidelines.md
* The `Show` trait is now deprecated, it was renamed to `Debug`
* The `String` trait is now deprecated, it was renamed to `Display`
* Many `Debug` and `Display` implementations were audited in accordance with the
RFC and audited implementations now have the `#[stable]` attribute
* Integers and floats no longer print a suffix
* Smart pointers no longer print details that they are a smart pointer
* Paths with `Debug` are now quoted and escape characters
* The `unwrap` methods on `Result` now require `Display` instead of `Debug`
* The `Error` trait no longer has a `detail` method and now requires that
`Display` must be implemented. With the loss of `String`, this has moved into
libcore.
* `impl<E: Error> FromError<E> for Box<Error>` now exists
* `derive(Show)` has been renamed to `derive(Debug)`. This is not currently
warned about due to warnings being emitted on stage1+
While backwards compatibility is attempted to be maintained with a blanket
implementation of `Display` for the old `String` trait (and the same for
`Show`/`Debug`) this is still a breaking change due to primitives no longer
implementing `String` as well as modifications such as `unwrap` and the `Error`
trait. Most code is fairly straightforward to update with a rename or tweaks of
method calls.
[breaking-change]
Closes#21436
This gets rid of the 'experimental' level, removes the non-staged_api
case (i.e. stability levels for out-of-tree crates), and lets the
staged_api attributes use 'unstable' and 'deprecated' lints.
This makes the transition period to the full feature staging design
a bit nicer.
This partially implements the feature staging described in the
[release channel RFC][rc]. It does not yet fully conform to the RFC as
written, but does accomplish its goals sufficiently for the 1.0 alpha
release.
It has three primary user-visible effects:
* On the nightly channel, use of unstable APIs generates a warning.
* On the beta channel, use of unstable APIs generates a warning.
* On the beta channel, use of feature gates generates a warning.
Code that does not trigger these warnings is considered 'stable',
modulo pre-1.0 bugs.
Disabling the warnings for unstable APIs continues to be done in the
existing (i.e. old) style, via `#[allow(...)]`, not that specified in
the RFC. I deem this marginally acceptable since any code that must do
this is not using the stable dialect of Rust.
Use of feature gates is itself gated with the new 'unstable_features'
lint, on nightly set to 'allow', and on beta 'warn'.
The attribute scheme used here corresponds to an older version of the
RFC, with the `#[staged_api]` crate attribute toggling the staging
behavior of the stability attributes, but the user impact is only
in-tree so I'm not concerned about having to make design changes later
(and I may ultimately prefer the scheme here after all, with the
`#[staged_api]` crate attribute).
Since the Rust codebase itself makes use of unstable features the
compiler and build system to a midly elaborate dance to allow it to
bootstrap while disobeying these lints (which would otherwise be
errors because Rust builds with `-D warnings`).
This patch includes one significant hack that causes a
regression. Because the `format_args!` macro emits calls to unstable
APIs it would trigger the lint. I added a hack to the lint to make it
not trigger, but this in turn causes arguments to `println!` not to be
checked for feature gates. I don't presently understand macro
expansion well enough to fix. This is bug #20661.
Closes#16678
[rc]: https://github.com/rust-lang/rfcs/blob/master/text/0507-release-channels.md
This removes a large array of deprecated functionality, regardless of how
recently it was deprecated. The purpose of this commit is to clean out the
standard libraries and compiler for the upcoming alpha release.
Some notable compiler changes were to enable warnings for all now-deprecated
command line arguments (previously the deprecated versions were silently
accepted) as well as removing deriving(Zero) entirely (the trait was removed).
The distribution no longer contains the libtime or libregex_macros crates. Both
of these have been deprecated for some time and are available externally.
This commit is an implementation of [RFC 503][rfc] which is a stabilization
story for the prelude. Most of the RFC was directly applied, removing reexports.
Some reexports are kept around, however:
* `range` remains until range syntax has landed to reduce churn.
* `Path` and `GenericPath` remain until path reform lands. This is done to
prevent many imports of `GenericPath` which will soon be removed.
* All `io` traits remain until I/O reform lands so imports can be rewritten all
at once to `std::io::prelude::*`.
This is a breaking change because many prelude reexports have been removed, and
the RFC can be consulted for the exact list of removed reexports, as well as to
find the locations of where to import them.
[rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0503-prelude-stabilization.md
[breaking-change]
Closes#20068
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.
Added -Z print-region-graph debugging option; produces graphviz visualization of region inference constraint graph.
Optionally uses environment variables `RUST_REGION_GRAPH=<path_template>` and `RUST_REGION_GRAPH_NODE=<node-id>` to select which file to output to and which AST node to print.
Part of #18469
[breaking-change]
A receiver will only ever get a single auto-reference. Previously arrays and strings would get two, e.g., [T] would be auto-ref'ed to &&[T]. This is usually apparent when a trait is implemented for `&[T]` and has a method takes self by reference. The usual solution is to implement the trait for `[T]` (the DST form).
r? @nikomatsakis (or anyone else, really)
per rfc 459
cc https://github.com/rust-lang/rust/issues/19390
One question is: should we start by warning, and only switch to hard error later? I think we discussed something like this in the meeting.
r? @alexcrichton
Part of #18469
[breaking-change]
A receiver will only ever get a single auto-reference. Previously arrays and strings would get two, e.g., [T] would be auto-ref'ed to &&[T]. This is usually apparent when a trait is implemented for `&[T]` and has a method takes self by reference. The usual solution is to implement the trait for `[T]` (the DST form).
This commit collapses the various prelude traits for slices into just one trait:
* SlicePrelude/SliceAllocPrelude => SliceExt
* CloneSlicePrelude/CloneSliceAllocPrelude => CloneSliceExt
* OrdSlicePrelude/OrdSliceAllocPrelude => OrdSliceExt
* PartialEqSlicePrelude => PartialEqSliceExt
This continues the work @thestinger started in #18885 (which hasn't landed yet, so wait for that to land before landing this one). Instead of adding more methods to `BufReader`, this just allows a `&[u8]` to be used directly as a `Reader`. It also adds an impl of `Writer` for `&mut [u8]`.
