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Rust 1.0.0-alpha.2

Released on February 20, 2015

What's Changed

  • ~1300 changes, numerous bugfixes
  • Highlights
  • The various I/O modules were [overhauled][io-rfc] to reduce
  • The standard library now [participates in feature gating][feat],
  • Language
  • for loops [now operate on the IntoIterator trait][into],
  • Objects now have [default lifetime bounds][obj], so you don't
  • In types that implement Drop, [lifetimes must outlive the
  • The fully qualified ::X syntax lets you set the Self
  • References to types that implement Deref now [automatically
  • The explicit [closure kind syntax][close] (|&:|, |&mut:|,
  • [Self is a keyword][Self].
  • Libraries
  • The Show and String formatting traits [have been
  • Abstract [OS-specific string types][osstr], `std::ff::{OsString,
  • The boxed::into_raw and Box::from_raw functions [convert
  • Tooling
  • Certain long error messages of the form 'expected foo found bar'
  • On Unix Rust can be [uninstalled][un] by running
  • The #[rustc_on_unimplemented] attribute, requiring the
  • Misc
  • Rust is tested against a [LALR grammar][lalr], which parses
Full Changelog

* ~1300 changes, numerous bugfixes

* Highlights

* The various I/O modules were [overhauled][io-rfc] to reduce

unnecessary abstractions and provide better interoperation with

the underlying platform. The old io module remains temporarily

at std::old_io.

* The standard library now [participates in feature gating][feat],

so use of unstable libraries now requires a #![feature(...)]

attribute. The impact of this change is [described on the

forum][feat-forum]. [RFC][feat-rfc].

* Language

* for loops [now operate on the IntoIterator trait][into],

which eliminates the need to call .iter(), etc. to iterate

over collections. There are some new subtleties to remember

though regarding what sort of iterators various types yield, in

particular that for foo in bar { } yields values from a move

iterator, destroying the original collection. [RFC][into-rfc].

* Objects now have [default lifetime bounds][obj], so you don't

have to write Box when you don't care about

storing references. [RFC][obj-rfc].

* In types that implement Drop, [lifetimes must outlive the

value][drop]. This will soon make it possible to safely

implement Drop for types where #[unsafe_destructor] is now

required. Read the [gorgeous RFC][drop-rfc] for details.

* The fully qualified ::X syntax lets you set the Self

type for a trait method or associated type. [RFC][ufcs-rfc].

* References to types that implement Deref now [automatically

coerce to references][deref] to the dereferenced type U,

e.g. &T where T: Deref automatically coerces to &U. This

should eliminate many unsightly uses of &*, as when converting

from references to vectors into references to

slices. [RFC][deref-rfc].

* The explicit [closure kind syntax][close] (|&:|, |&mut:|,

|:|) is obsolete and closure kind is inferred from context.

* [Self is a keyword][Self].

* Libraries

* The Show and String formatting traits [have been

renamed][fmt] to Debug and Display to more clearly reflect

their related purposes. Automatically getting a string

conversion to use with format!("{:?}", something_to_debug) is

now written #[derive(Debug)].

* Abstract [OS-specific string types][osstr], std::ff::{OsString,

OsStr}, provide strings in platform-specific encodings for easier

interop with system APIs. [RFC][osstr-rfc].

* The boxed::into_raw and Box::from_raw functions [convert

between Box and *mut T][boxraw], a common pattern for

creating raw pointers.

* Tooling

* Certain long error messages of the form 'expected foo found bar'

are now [split neatly across multiple

lines][multiline]. Examples in the PR.

* On Unix Rust can be [uninstalled][un] by running

/usr/local/lib/rustlib/uninstall.sh.

* The #[rustc_on_unimplemented] attribute, requiring the

'on_unimplemented' feature, lets rustc [display custom error

messages when a trait is expected to be implemented for a type

but is not][onun].

* Misc

* Rust is tested against a [LALR grammar][lalr], which parses

almost all the Rust files that rustc does.

[boxraw]: https://github.com/rust-lang/rust/pull/21318

[close]: https://github.com/rust-lang/rust/pull/21843

[deref]: https://github.com/rust-lang/rust/pull/21351

[deref-rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0241-deref-conversions.md

[drop]: https://github.com/rust-lang/rust/pull/21972

[drop-rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0769-sound-generic-drop.md

[feat]: https://github.com/rust-lang/rust/pull/21248

[feat-forum]: https://users.rust-lang.org/t/psa-important-info-about-rustcs-new-feature-staging/82/5

[feat-rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0507-release-channels.md

[fmt]: https://github.com/rust-lang/rust/pull/21457

[into]: https://github.com/rust-lang/rust/pull/20790

[into-rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0235-collections-conventions.md#intoiterator-and-iterable

[io-rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0517-io-os-reform.md

[lalr]: https://github.com/rust-lang/rust/pull/21452

[multiline]: https://github.com/rust-lang/rust/pull/19870

[obj]: https://github.com/rust-lang/rust/pull/22230

[obj-rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0599-default-object-bound.md

[onun]: https://github.com/rust-lang/rust/pull/20889

[osstr]: https://github.com/rust-lang/rust/pull/21488

[osstr-rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0517-io-os-reform.md

[Self]: https://github.com/rust-lang/rust/pull/22158

[ufcs-rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0132-ufcs.md

[un]: https://github.com/rust-lang/rust/pull/22256