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| layout: post | ||
| title: "Announcing Rust 1.80.0" | ||
| author: The Rust Release Team | ||
| release: true | ||
| --- | ||
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| The Rust team is happy to announce a new version of Rust, 1.80.0. Rust is a programming language empowering everyone to build reliable and efficient software. | ||
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| If you have a previous version of Rust installed via `rustup`, you can get 1.80.0 with: | ||
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| ```console | ||
| $ rustup update stable | ||
| ``` | ||
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| 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 1.80.0](https://doc.rust-lang.org/nightly/releases.html#version-1800-2024-07-25). | ||
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| 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! | ||
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| ## What's in 1.80.0 stable | ||
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| ### `LazyCell` and `LazyLock` | ||
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| These "lazy" types delay the initialization of their data until first access. They are similar to the `OnceCell` and `OnceLock` types [stabilized in 1.70](https://blog.rust-lang.org/2023/06/01/Rust-1.70.0.html#oncecell-and-oncelock), but with the initialization function included in the type. | ||
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| `LazyLock` is the thread-safe option, making it suitable for places like `static` values. For example, both the `spawn` thread and the main `scope` will see the exact same duration below, since `LAZY_TIME` will be initialized once, by whichever ends up accessing the static first. Neither use has to know *how* to initialize it though, like you would with `OnceLock::get_or_init`. | ||
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| ```rust | ||
| use std::sync::LazyLock; | ||
| use std::time::Instant; | ||
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| static LAZY_TIME: LazyLock<Instant> = LazyLock::new(Instant::now); | ||
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| fn main() { | ||
| let start = Instant::now(); | ||
| std::thread::scope(|s| { | ||
| s.spawn(|| { | ||
| println!("Thread lazy time is {:?}", LAZY_TIME.duration_since(start)); | ||
| }); | ||
| println!("Main lazy time is {:?}", LAZY_TIME.duration_since(start)); | ||
| }); | ||
| } | ||
| ``` | ||
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| `LazyCell` does the same thing without thread synchronization, so it doesn't implement `Sync` needed for `static`, but it can still be used in `thread_local!` statics (with distinct initialization per thread). Either type can also be used in other data structures as well, depending on thread-safety needs, so lazy initialization is available everywhere! | ||
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| ### Checked `cfg` names and values | ||
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| In 1.79, `rustc` stabilized a [`--check-cfg` flag](https://doc.rust-lang.org/rustc/check-cfg.html), and now Cargo 1.80 is enabling those checks for all `cfg` names that it knows (in addition to those built-in to `rustc`). This includes feature names from `Cargo.toml` as well as new `cargo::rustc-check-cfg` output from build scripts. | ||
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| Check failures are reported by the `unexpected_cfgs` lint, which is meant to catch typos or other misconfiguration. For example, in a project with an optional `rayon` dependency, this code is configured for the wrong name: | ||
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| ```rust | ||
| fn main() { | ||
| println!("Hello, world!"); | ||
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| #[cfg(feature = "crayon")] | ||
| rayon::join( | ||
| || println!("Hello, Thing One!"), | ||
| || println!("Hello, Thing Two!"), | ||
| ); | ||
| } | ||
| ``` | ||
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| ```console | ||
| warning: unexpected `cfg` condition value: `crayon` | ||
| --> src/main.rs:4:11 | ||
| | | ||
| 4 | #[cfg(feature = "crayon")] | ||
| | ^^^^^^^^^^-------- | ||
| | | | ||
| | help: there is a expected value with a similar name: `"rayon"` | ||
| | | ||
| = note: expected values for `feature` are: `rayon` | ||
| = help: consider adding `crayon` as a feature in `Cargo.toml` | ||
| = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration | ||
| = note: `#[warn(unexpected_cfgs)]` on by default | ||
| ``` | ||
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| The same warning is reported regardless of whether the actual `rayon` feature is enabled or not. | ||
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| The `[lints]` table in the manifest can also be used to extend the known values for custom `cfg` options. | ||
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| ```toml | ||
| [lints.rust] | ||
| unexpected_cfgs = { level = "warn", check-cfg = ['cfg(foo, values("bar"))'] } | ||
| ``` | ||
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| ### Exclusive ranges in patterns | ||
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| Rust ranged patterns can now use exclusive endpoints, written `a..b` or `..b` similar to the `Range` and `RangeTo` expression types. For example, the following patterns can now use the same constants for the end of one pattern and the start of the next: | ||
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| ```rust | ||
| pub fn size_prefix(n: u32) -> &'static str { | ||
| const K: u32 = 10u32.pow(3); | ||
| const M: u32 = 10u32.pow(6); | ||
| const G: u32 = 10u32.pow(9); | ||
| match n { | ||
| ..K => "", | ||
| K..M => "k", | ||
| M..G => "M", | ||
| G.. => "G", | ||
| } | ||
| } | ||
| ``` | ||
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| Previously, only inclusive (`a..=b` or `..=b`) or open (`a..`) ranges were allowed in patterns, so code like this would require separate constants for inclusive endpoints like `K - 1`. | ||
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| Exclusive ranges have been implemented as an unstable feature for a long time, but the blocking concern was that they might add confusion and increase the chance of off-by-one errors in patterns. To that end, exhaustiveness checking has been enhanced to better detect gaps in pattern matching, and new lints `non_contiguous_range_endpoints` and `overlapping_range_endpoints` will help detect cases where you might want to switch exclusive patterns to inclusive, or vice versa. | ||
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| ### Stabilized APIs | ||
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| - [`impl Default for Rc<CStr>`](https://doc.rust-lang.org/stable/alloc/rc/struct.Rc.html#impl-Default-for-Rc%3CCStr%3E) | ||
| - [`impl Default for Rc<str>`](https://doc.rust-lang.org/stable/alloc/rc/struct.Rc.html#impl-Default-for-Rc%3Cstr%3E) | ||
| - [`impl Default for Rc<[T]>`](https://doc.rust-lang.org/stable/alloc/rc/struct.Rc.html#impl-Default-for-Rc%3C%5BT%5D%3E) | ||
| - [`impl Default for Arc<str>`](https://doc.rust-lang.org/stable/alloc/sync/struct.Arc.html#impl-Default-for-Arc%3Cstr%3E) | ||
| - [`impl Default for Arc<CStr>`](https://doc.rust-lang.org/stable/alloc/sync/struct.Arc.html#impl-Default-for-Arc%3CCStr%3E) | ||
| - [`impl Default for Arc<[T]>`](https://doc.rust-lang.org/stable/alloc/sync/struct.Arc.html#impl-Default-for-Arc%3C%5BT%5D%3E) | ||
| - [`impl IntoIterator for Box<[T]>`](https://doc.rust-lang.org/stable/alloc/boxed/struct.Box.html#impl-IntoIterator-for-Box%3C%5BI%5D,+A%3E) | ||
| - [`impl FromIterator<String> for Box<str>`](https://doc.rust-lang.org/stable/alloc/boxed/struct.Box.html#impl-FromIterator%3CString%3E-for-Box%3Cstr%3E) | ||
| - [`impl FromIterator<char> for Box<str>`](https://doc.rust-lang.org/stable/alloc/boxed/struct.Box.html#impl-FromIterator%3Cchar%3E-for-Box%3Cstr%3E) | ||
| - [`LazyCell`](https://doc.rust-lang.org/stable/core/cell/struct.LazyCell.html) | ||
| - [`LazyLock`](https://doc.rust-lang.org/stable/std/sync/struct.LazyLock.html) | ||
| - [`Duration::div_duration_f32`](https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.div_duration_f32) | ||
| - [`Duration::div_duration_f64`](https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.div_duration_f64) | ||
| - [`Option::take_if`](https://doc.rust-lang.org/stable/std/option/enum.Option.html#method.take_if) | ||
| - [`Seek::seek_relative`](https://doc.rust-lang.org/stable/std/io/trait.Seek.html#method.seek_relative) | ||
| - [`BinaryHeap::as_slice`](https://doc.rust-lang.org/stable/std/collections/struct.BinaryHeap.html#method.as_slice) | ||
| - [`NonNull::offset`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.offset) | ||
| - [`NonNull::byte_offset`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.byte_offset) | ||
| - [`NonNull::add`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.add) | ||
| - [`NonNull::byte_add`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.byte_add) | ||
| - [`NonNull::sub`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.sub) | ||
| - [`NonNull::byte_sub`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.byte_sub) | ||
| - [`NonNull::offset_from`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.offset_from) | ||
| - [`NonNull::byte_offset_from`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.byte_offset_from) | ||
| - [`NonNull::read`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.read) | ||
| - [`NonNull::read_volatile`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.read_volatile) | ||
| - [`NonNull::read_unaligned`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.read_unaligned) | ||
| - [`NonNull::write`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.write) | ||
| - [`NonNull::write_volatile`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.write_volatile) | ||
| - [`NonNull::write_unaligned`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.write_unaligned) | ||
| - [`NonNull::write_bytes`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.write_bytes) | ||
| - [`NonNull::copy_to`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.copy_to) | ||
| - [`NonNull::copy_to_nonoverlapping`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.copy_to_nonoverlapping) | ||
| - [`NonNull::copy_from`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.copy_from) | ||
| - [`NonNull::copy_from_nonoverlapping`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.copy_from_nonoverlapping) | ||
| - [`NonNull::replace`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.replace) | ||
| - [`NonNull::swap`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.swap) | ||
| - [`NonNull::drop_in_place`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.drop_in_place) | ||
| - [`NonNull::align_offset`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.align_offset) | ||
| - [`<[T]>::split_at_checked`](https://doc.rust-lang.org/stable/std/primitive.slice.html#method.split_at_checked) | ||
| - [`<[T]>::split_at_mut_checked`](https://doc.rust-lang.org/stable/std/primitive.slice.html#method.split_at_mut_checked) | ||
| - [`str::split_at_checked`](https://doc.rust-lang.org/stable/std/primitive.str.html#method.split_at_checked) | ||
| - [`str::split_at_mut_checked`](https://doc.rust-lang.org/stable/std/primitive.str.html#method.split_at_mut_checked) | ||
| - [`str::trim_ascii`](https://doc.rust-lang.org/stable/std/primitive.str.html#method.trim_ascii) | ||
| - [`str::trim_ascii_start`](https://doc.rust-lang.org/stable/std/primitive.str.html#method.trim_ascii_start) | ||
| - [`str::trim_ascii_end`](https://doc.rust-lang.org/stable/std/primitive.str.html#method.trim_ascii_end) | ||
| - [`<[u8]>::trim_ascii`](https://doc.rust-lang.org/stable/core/primitive.slice.html#method.trim_ascii) | ||
| - [`<[u8]>::trim_ascii_start`](https://doc.rust-lang.org/stable/core/primitive.slice.html#method.trim_ascii_start) | ||
| - [`<[u8]>::trim_ascii_end`](https://doc.rust-lang.org/stable/core/primitive.slice.html#method.trim_ascii_end) | ||
| - [`Ipv4Addr::BITS`](https://doc.rust-lang.org/stable/core/net/struct.Ipv4Addr.html#associatedconstant.BITS) | ||
| - [`Ipv4Addr::to_bits`](https://doc.rust-lang.org/stable/core/net/struct.Ipv4Addr.html#method.to_bits) | ||
| - [`Ipv4Addr::from_bits`](https://doc.rust-lang.org/stable/core/net/struct.Ipv4Addr.html#method.from_bits) | ||
| - [`Ipv6Addr::BITS`](https://doc.rust-lang.org/stable/core/net/struct.Ipv6Addr.html#associatedconstant.BITS) | ||
| - [`Ipv6Addr::to_bits`](https://doc.rust-lang.org/stable/core/net/struct.Ipv6Addr.html#method.to_bits) | ||
| - [`Ipv6Addr::from_bits`](https://doc.rust-lang.org/stable/core/net/struct.Ipv6Addr.html#method.from_bits) | ||
| - [`Vec::<[T; N]>::into_flattened`](https://doc.rust-lang.org/stable/alloc/vec/struct.Vec.html#method.into_flattened) | ||
| - [`<[[T; N]]>::as_flattened`](https://doc.rust-lang.org/stable/core/primitive.slice.html#method.as_flattened) | ||
| - [`<[[T; N]]>::as_flattened_mut`](https://doc.rust-lang.org/stable/core/primitive.slice.html#method.as_flattened_mut) | ||
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| These APIs are now stable in const contexts: | ||
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| - [`<[T]>::last_chunk`](https://doc.rust-lang.org/stable/core/primitive.slice.html#method.last_chunk) | ||
| - [`BinaryHeap::new`](https://doc.rust-lang.org/stable/std/collections/struct.BinaryHeap.html#method.new) | ||
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| ### Other changes | ||
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| Check out everything that changed in [Rust](https://github.com/rust-lang/rust/releases/tag/1.80.0), [Cargo](https://github.com/rust-lang/cargo/blob/master/CHANGELOG.md#cargo-180-2024-07-25), and [Clippy](https://github.com/rust-lang/rust-clippy/blob/master/CHANGELOG.md#rust-180). | ||
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| ## Contributors to 1.80.0 | ||
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| Many people came together to create Rust 1.80.0. We couldn't have done it without all of you. [Thanks!](https://thanks.rust-lang.org/rust/1.80.0/) |