1.28.0 blog post

Author: Mark-Simulacrum

_posts/2018-08-02-Rust-1.28.md

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+---
+layout: post
+title: "Announcing Rust 1.28"
+author: The Rust Core Team
+---
+
+The Rust team is happy to announce a new version of Rust, 1.28.0. Rust is a
+systems programming language focused on safety, speed, and concurrency.
+
+If you have a previous version of Rust installed via rustup, getting Rust
+1.28.0 is as easy as:
+
+```bash
+$ rustup update stable
+```
+
+If you don't have it already, you can [get `rustup`][install] from the
+appropriate page on our website, and check out the [detailed release notes for
+1.28.0][notes] on GitHub.
+
+[install]: https://www.rust-lang.org/install.html
+[notes]: https://github.com/rust-lang/rust/blob/master/RELEASES.md#version-1280-2018-08-02
+
+## What's in 1.28.0 stable
+
+### Global Allocators
+
+1.28.0 adds the `#[global_allocator]` attribute, which allows Rust programs to
+set their allocator, as well as define new allocators by implementing the
+[`GlobalAlloc`] trait.
+
+By default, Rust uses jemalloc on Linux systems, but this may not be ideal for
+specific use cases. The standard library provides a method for switching to the
+system allocator:
+
+```rust
+use std::alloc::System;
+
+#[global_allocator]
+static GLOBAL: System = System;
+
+fn main() {
+    let mut v = Vec::new();
+    // This will allocate memory using the system allocator.
+    v.push(1);
+}
+```
+
+However, sometimes you want to define a custom allocator for a given application
+domain. This is also relatively easy to do by implementing the `GlobalAlloc`
+trait. You can read more about how to do this in the [documentation].
+
+[`GlobalAlloc`]: https://doc.rust-lang.org/1.28.0/std/alloc/trait.GlobalAlloc.html
+[documentation]: https://doc.rust-lang.org/1.28.0/std/alloc/trait.GlobalAlloc.html
+
+### Library stabilizations
+
+Several new APIs were stabilized this release:
+
+- [`Iterator::step_by`]
+- [`Path::ancestors`]
+- [`SystemTime::UNIX_EPOCH`]
+- [`alloc::GlobalAlloc`]
+- [`alloc::Layout`]
+- [`alloc::LayoutErr`]
+- [`alloc::System`]
+- [`alloc::alloc`]
+- [`alloc::alloc_zeroed`]
+- [`alloc::dealloc`]
+- [`alloc::realloc`]
+- [`alloc::handle_alloc_error`]
+- [`btree_map::Entry::or_default`]
+- [`fmt::Alignment`]
+- [`hash_map::Entry::or_default`]
+- [`iter::repeat_with`]
+- [`num::NonZeroUsize`]
+- [`num::NonZeroU128`]
+- [`num::NonZeroU16`]
+- [`num::NonZeroU32`]
+- [`num::NonZeroU64`]
+- [`num::NonZeroU8`]
+- [`ops::RangeBounds`]
+- [`slice::SliceIndex`]
+- [`slice::from_mut`]
+- [`slice::from_ref`]
+- [`{Any + Send + Sync}::downcast_mut`]
+- [`{Any + Send + Sync}::downcast_ref`]
+- [`{Any + Send + Sync}::is`]
+
+See the [detailed release notes][notes] for more.
+
+[`Iterator::step_by`]: https://doc.rust-lang.org/std/iter/trait.Iterator.html#method.step_by
+[`Path::ancestors`]: https://doc.rust-lang.org/std/path/struct.Path.html#method.ancestors
+[`SystemTime::UNIX_EPOCH`]: https://doc.rust-lang.org/std/time/struct.SystemTime.html#associatedconstant.UNIX_EPOCH
+[`alloc::GlobalAlloc`]: https://doc.rust-lang.org/std/alloc/trait.GlobalAlloc.html
+[`alloc::Layout`]: https://doc.rust-lang.org/std/alloc/struct.Layout.html
+[`alloc::LayoutErr`]: https://doc.rust-lang.org/std/alloc/struct.LayoutErr.html
+[`alloc::System`]: https://doc.rust-lang.org/std/alloc/struct.System.html
+[`alloc::alloc`]: https://doc.rust-lang.org/std/alloc/fn.alloc.html
+[`alloc::alloc_zeroed`]: https://doc.rust-lang.org/std/alloc/fn.alloc_zeroed.html
+[`alloc::dealloc`]: https://doc.rust-lang.org/std/alloc/fn.dealloc.html
+[`alloc::realloc`]: https://doc.rust-lang.org/std/alloc/fn.realloc.html
+[`alloc::handle_alloc_error`]: https://doc.rust-lang.org/std/alloc/fn.handle_alloc_error.html
+[`btree_map::Entry::or_default`]: https://doc.rust-lang.org/std/collections/btree_map/enum.Entry.html#method.or_default
+[`fmt::Alignment`]: https://doc.rust-lang.org/std/fmt/enum.Alignment.html
+[`hash_map::Entry::or_default`]: https://doc.rust-lang.org/std/collections/btree_map/enum.Entry.html#method.or_default
+[`iter::repeat_with`]: https://doc.rust-lang.org/std/iter/fn.repeat_with.html
+[`num::NonZeroUsize`]: https://doc.rust-lang.org/std/num/struct.NonZeroUsize.html
+[`num::NonZeroU128`]: https://doc.rust-lang.org/std/num/struct.NonZeroU128.html
+[`num::NonZeroU16`]: https://doc.rust-lang.org/std/num/struct.NonZeroU16.html
+[`num::NonZeroU32`]: https://doc.rust-lang.org/std/num/struct.NonZeroU32.html
+[`num::NonZeroU64`]: https://doc.rust-lang.org/std/num/struct.NonZeroU64.html
+[`num::NonZeroU8`]: https://doc.rust-lang.org/std/num/struct.NonZeroU8.html
+[`ops::RangeBounds`]: https://doc.rust-lang.org/std/ops/trait.RangeBounds.html
+[`slice::SliceIndex`]: https://doc.rust-lang.org/std/slice/trait.SliceIndex.html
+[`slice::from_mut`]: https://doc.rust-lang.org/std/slice/fn.from_mut.html
+[`slice::from_ref`]: https://doc.rust-lang.org/std/slice/fn.from_ref.html
+[`{Any + Send + Sync}::downcast_mut`]: https://doc.rust-lang.org/std/any/trait.Any.html#method.downcast_mut-2
+[`{Any + Send + Sync}::downcast_ref`]: https://doc.rust-lang.org/std/any/trait.Any.html#method.downcast_ref-2
+[`{Any + Send + Sync}::is`]: https://doc.rust-lang.org/std/any/trait.Any.html#method.is-2
+
+### Cargo features
+
+[Cargo will now no longer allow you to publish crates with build scripts that
+modify the `src` directory.][cargo/5584] The `src` directory in a crate should be
+considered to be immutable.
+
+[cargo/5584]: https://github.com/rust-lang/cargo/pull/5584/
+
+## Contributors to 1.28.0
+
+Many people came together to create Rust 1.28. We couldn't have done it
+without all of you. [Thanks!](https://thanks.rust-lang.org/rust/1.28.0)