diff --git a/posts/2024-06-13-Rust-1.79.0.md b/posts/2024-06-13-Rust-1.79.0.md new file mode 100644 index 000000000..229f9f87f --- /dev/null +++ b/posts/2024-06-13-Rust-1.79.0.md @@ -0,0 +1,166 @@ +--- +layout: post +title: "Announcing Rust 1.79.0" +author: The Rust Release Team +release: true +--- + +The Rust team is happy to announce a new version of Rust, 1.79.0. Rust is a programming language empowering everyone to build reliable and efficient software. + +If you have a previous version of Rust installed via `rustup`, you can get 1.79.0 with: + +```console +$ rustup update stable +``` + +If you don't have it already, you can [get `rustup`](https://www.rust-lang.org/install.html) from the appropriate page on our website, and check out the [detailed release notes for 1.79.0](https://doc.rust-lang.org/nightly/releases.html#version-1790-2024-06-13). + +If you'd like to help us out by testing future releases, you might consider updating locally to use the beta channel (`rustup default beta`) or the nightly channel (`rustup default nightly`). Please [report](https://github.com/rust-lang/rust/issues/new/choose) any bugs you might come across! + +## What's in 1.79.0 stable + +### Inline `const` expressions + +`const { ... }` blocks are now stable in expression position, permitting +explicitly entering a const context without requiring extra declarations (e.g., +defining `const` items or associated constants on a trait). + +Unlike const items (`const ITEM: ... = ...`), inline consts are able to make +use of in-scope generics, and have their type inferred rather than written explicitly, making them particularly useful for inline code snippets. For example, a pattern like: + +```rust +const EMPTY: Option> = None; +let foo = [EMPTY; 100]; +``` + +can now be written like this: + +```rust +let foo = [const { None }; 100]; +``` + +Notably, this is also true of generic contexts, where previously a verbose trait declaration with an associated constant would be required: + +```rust +fn create_none_array() -> [Option; N] { + [const { None:: }; N] +} +``` + +This makes this code much more succinct and easier to read. + +See the [reference documentation](https://doc.rust-lang.org/nightly/reference/expressions/block-expr.html#const-blocks) for details. + +### Bounds in associated type position + +Rust 1.79 stabilizes the associated item bounds syntax, which allows us to put +bounds in associated type position within other bounds, i.e. +`T: Trait`. This avoids the need to provide an extra, +explicit generic type just to constrain the associated type. + +This feature allows specifying bounds in a few places that previously either +were not possible or imposed extra, unnecessary constraints on usage: + +* **`where` clauses** - in this position, this is equivalent to breaking up the bound into two (or more) `where` clauses. For example, `where T: Trait` is equivalent to `where T: Trait, ::Assoc: Bound`. +* **Supertraits** - a bound specified via the new syntax is implied when the trait is used, unlike where clauses. Sample syntax: `trait CopyIterator: Iterator {}`. +* **Associated type item bounds** - This allows constraining the *nested* rigid projections that are associated with a trait's associated types. e.g. `trait Trait { type Assoc: Trait2; }`. +* **opaque type bounds (RPIT, TAIT)** - This allows constraining associated types that are associated with the opaque type without having to *name* the opaque type. For example, `impl Iterator` defines an iterator whose item is `Copy` without having to actually name that item bound. + +See [the stabilization report](https://github.com/rust-lang/rust/pull/122055/#issue-2170532454) for more details. + +### Extending automatic temporary lifetime extension + +Temporaries which are immediately referenced in construction are now +automatically lifetime extended in `match` and `if` constructs. This has the +same behavior as lifetime extension for temporaries in block constructs. + +For example: + +```rust +let a = if true { + ..; + &temp() // used to error, but now gets lifetime extended +} else { + ..; + &temp() // used to error, but now gets lifetime extended +}; +``` + +and + +```rust +let a = match () { + _ => { + ..; + &temp() // used to error, but now gets lifetime extended + } +}; +``` + +are now consistent with prior behavior: + +```rust +let a = { + ..; + &temp() // lifetime is extended +}; +``` + +This behavior is backwards compatible since these programs used to fail compilation. + +### Frame pointers enabled in standard library builds + +The standard library distributed by the Rust project is now compiled with +`-Cforce-frame-pointers=yes`, enabling downstream users to more easily profile +their programs. Note that the standard library also continues to come up with +line-level debug info (e.g., DWARF), though that is [stripped by default] in Cargo's release profiles. + +[stripped by default]: https://blog.rust-lang.org/2024/03/21/Rust-1.77.0.html#enable-strip-in-release-profiles-by-default + +### Stabilized APIs + +- [`{integer}::unchecked_add`](https://doc.rust-lang.org/stable/core/primitive.i32.html#method.unchecked_add) +- [`{integer}::unchecked_mul`](https://doc.rust-lang.org/stable/core/primitive.i32.html#method.unchecked_mul) +- [`{integer}::unchecked_sub`](https://doc.rust-lang.org/stable/core/primitive.i32.html#method.unchecked_sub) +- [`<[T]>::split_at_unchecked`](https://doc.rust-lang.org/stable/core/primitive.slice.html#method.split_at_unchecked) +- [`<[T]>::split_at_mut_unchecked`](https://doc.rust-lang.org/stable/core/primitive.slice.html#method.split_at_mut_unchecked) +- [`<[u8]>::utf8_chunks`](https://doc.rust-lang.org/stable/core/primitive.slice.html#method.utf8_chunks) +- [`str::Utf8Chunks`](https://doc.rust-lang.org/stable/core/str/struct.Utf8Chunks.html) +- [`str::Utf8Chunk`](https://doc.rust-lang.org/stable/core/str/struct.Utf8Chunk.html) +- [`<*const T>::is_aligned`](https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.is_aligned) +- [`<*mut T>::is_aligned`](https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.is_aligned-1) +- [`NonNull::is_aligned`](https://doc.rust-lang.org/stable/core/ptr/struct.NonNull.html#method.is_aligned) +- [`<*const [T]>::len`](https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.len) +- [`<*mut [T]>::len`](https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.len-1) +- [`<*const [T]>::is_empty`](https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.is_empty) +- [`<*mut [T]>::is_empty`](https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.is_empty-1) +- [`NonNull::<[T]>::is_empty`](https://doc.rust-lang.org/stable/core/ptr/struct.NonNull.html#method.is_empty) +- [`CStr::count_bytes`](https://doc.rust-lang.org/stable/core/ffi/c_str/struct.CStr.html#method.count_bytes) +- [`io::Error::downcast`](https://doc.rust-lang.org/stable/std/io/struct.Error.html#method.downcast) +- [`num::NonZero`](https://doc.rust-lang.org/stable/core/num/struct.NonZero.html) +- [`path::absolute`](https://doc.rust-lang.org/stable/std/path/fn.absolute.html) +- [`proc_macro::Literal::byte_character`](https://doc.rust-lang.org/stable/proc_macro/struct.Literal.html#method.byte_character) +- [`proc_macro::Literal::c_string`](https://doc.rust-lang.org/stable/proc_macro/struct.Literal.html#method.c_string) + +These APIs are now stable in const contexts: + +- [`Atomic*::into_inner`](https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicUsize.html#method.into_inner) +- [`io::Cursor::new`](https://doc.rust-lang.org/stable/std/io/struct.Cursor.html#method.new) +- [`io::Cursor::get_ref`](https://doc.rust-lang.org/stable/std/io/struct.Cursor.html#method.get_ref) +- [`io::Cursor::position`](https://doc.rust-lang.org/stable/std/io/struct.Cursor.html#method.position) +- [`io::empty`](https://doc.rust-lang.org/stable/std/io/fn.empty.html) +- [`io::repeat`](https://doc.rust-lang.org/stable/std/io/fn.repeat.html) +- [`io::sink`](https://doc.rust-lang.org/stable/std/io/fn.sink.html) +- [`panic::Location::caller`](https://doc.rust-lang.org/stable/std/panic/struct.Location.html#method.caller) +- [`panic::Location::file`](https://doc.rust-lang.org/stable/std/panic/struct.Location.html#method.file) +- [`panic::Location::line`](https://doc.rust-lang.org/stable/std/panic/struct.Location.html#method.line) +- [`panic::Location::column`](https://doc.rust-lang.org/stable/std/panic/struct.Location.html#method.column) + + +### Other changes + +Check out everything that changed in [Rust](https://github.com/rust-lang/rust/releases/tag/1.79.0), [Cargo](https://github.com/rust-lang/cargo/blob/master/CHANGELOG.md#cargo-179-2024-06-13), and [Clippy](https://github.com/rust-lang/rust-clippy/blob/master/CHANGELOG.md#rust-179). + +## Contributors to 1.79.0 + +Many people came together to create Rust 1.79.0. We couldn't have done it without all of you. [Thanks!](https://thanks.rust-lang.org/rust/1.79.0/)