Merge pull request #849 from m-ou-se/release-1.53

Add blog post for the 1.53 release.

Author: Mark-Simulacrum

Diff for: posts/2021-06-17-Rust-1.53.0.md

@@ -0,0 +1,181 @@
+---
+layout: post
+title: "Announcing Rust 1.53.0"
+author: The Rust Release Team
+release: true
+---
+
+The Rust team is happy to announce a new version of Rust, 1.53.0. Rust is a
+programming language that is empowering everyone to build reliable and
+efficient software.
+
+If you have a previous version of Rust installed via rustup, getting Rust
+1.53.0 is as easy as:
+
+```console
+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 1.53.0][notes] on GitHub.
+
+[install]: https://www.rust-lang.org/install.html
+[notes]: https://github.com/rust-lang/rust/blob/master/RELEASES.md#version-1530-2021-06-17
+
+## What's in 1.53.0 stable
+
+This release contains several new language features and many new library features,
+including the long-awaited `IntoIterator` implementation for arrays.
+See the [detailed release notes](https://github.com/rust-lang/rust/blob/master/RELEASES.md#version-1530-2021-06-17)
+to learn about other changes not covered by this post.
+
+### IntoIterator for arrays
+
+This is the first Rust release in which arrays implement the `IntoIterator` trait.
+This means you can now iterate over arrays by value:
+
+```rust
+for i in [1, 2, 3] {
+    ..
+}
+```
+
+Previously, this was only possible by reference, using `&[1, 2, 3]` or `[1, 2, 3].iter()`.
+
+Similarly, you can now pass arrays to methods expecting a `T: IntoIterator`:
+
+```rust
+let set = BTreeSet::from_iter([1, 2, 3]);
+```
+
+```rust
+for (a, b) in some_iterator.chain([1]).zip([1, 2, 3]) {
+    ..
+}
+```
+
+This was not implemented before, due to backwards compatibility problems.
+Because `IntoIterator` was already implemented for references to arrays,
+`array.into_iter()` already compiled in earlier versions,
+resolving to `(&array).into_iter()`.
+
+As of this release, arrays implement `IntoIterator` with a small workaround to avoid breaking code.
+The compiler will continue to resolve `array.into_iter()` to `(&array).into_iter()`,
+as if the trait implementation does not exist.
+This only applies to the `.into_iter()` method call syntax, and does not
+affect any other syntax such as `for e in [1, 2, 3]`, `iter.zip([1, 2, 3])` or
+`IntoIterator::into_iter([1, 2, 3])`, which all compile fine.
+
+Since this special case for `.into_iter()` is only required to avoid breaking existing code,
+it is removed in the new edition, Rust 2021, which will be released later this year.
+See [the edition announcement](https://blog.rust-lang.org/2021/05/11/edition-2021.html#intoiterator-for-arrays)
+for more information.
+
+### Or patterns
+
+Pattern syntax has been extended to support `|` nested anywhere in the pattern.
+This enables you to write `Some(1 | 2)` instead of `Some(1) | Some(2)`.
+
+```rust
+match result {
+     Ok(Some(1 | 2)) => { .. }
+     Err(MyError { kind: FileNotFound | PermissionDenied, .. }) => { .. }
+     _ => { .. }
+}
+```
+
+### Unicode identifiers
+
+Identifiers can now contain non-ascii characters.
+All valid identifier characters in Unicode as defined in [UAX #31](https://unicode.org/reports/tr31/) can now be used.
+That includes characters from many different scripts and languages, but does not include emoji.
+
+For example:
+
+```rust
+const BLÅHAJ: &str = "🦈";
+
+struct 人 {
+    名字: String,
+}
+
+let α = 1;
+```
+
+The compiler will warn about about potentially confusing situations involving different scripts.
+For example, using identifiers that look very similar will result in a warning.
+
+```
+warning: identifier pair considered confusable between `ｓ` and `s`
+```
+
+### HEAD branch name support in Cargo
+
+Cargo no longer assumes the default `HEAD` of git repositories is named `master`.
+This means you no longer need to specify `branch = "main"` for git dependencies
+from a repository where the default branch is called `main`.
+
+### Stabilized APIs
+
+The following methods and trait implementations were stabilized.
+
+- [`array::from_ref`](https://doc.rust-lang.org/stable/std/array/fn.from_ref.html)
+- [`array::from_mut`](https://doc.rust-lang.org/stable/std/array/fn.from_mut.html)
+- [`AtomicBool::fetch_update`](https://doc.rust-lang.org/stable/std/sync/atomic/struct.AtomicBool.html#method.fetch_update)
+- [`AtomicPtr::fetch_update`](https://doc.rust-lang.org/stable/std/sync/atomic/struct.AtomicPtr.html#method.fetch_update)
+- [`BTreeSet::retain`](https://doc.rust-lang.org/stable/std/collections/struct.BTreeSet.html#method.retain)
+- [`BTreeMap::retain`](https://doc.rust-lang.org/stable/std/collections/struct.BTreeMap.html#method.retain)
+- [`BufReader::seek_relative`](https://doc.rust-lang.org/stable/std/io/struct.BufReader.html#method.seek_relative)
+- [`cmp::min_by`](https://doc.rust-lang.org/stable/std/cmp/fn.min_by.html)
+- [`cmp::min_by_key`](https://doc.rust-lang.org/stable/std/cmp/fn.min_by_key.html)
+- [`cmp::max_by`](https://doc.rust-lang.org/stable/std/cmp/fn.max_by.html)
+- [`cmp::max_by_key`](https://doc.rust-lang.org/stable/std/cmp/fn.max_by_key.html)
+- [`DebugStruct::finish_non_exhaustive`](https://doc.rust-lang.org/stable/std/fmt/struct.DebugStruct.html#method.finish_non_exhaustive)
+- [`Duration::ZERO`](https://doc.rust-lang.org/stable/std/time/struct.Duration.html#associatedconstant.ZERO)
+- [`Duration::MAX`](https://doc.rust-lang.org/stable/std/time/struct.Duration.html#associatedconstant.MAX)
+- [`Duration::is_zero`](https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.is_zero)
+- [`Duration::saturating_add`](https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.saturating_add)
+- [`Duration::saturating_sub`](https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.saturating_sub)
+- [`Duration::saturating_mul`](https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.saturating_mul)
+- [`f32::is_subnormal`](https://doc.rust-lang.org/stable/std/primitive.f32.html#method.is_subnormal)
+- [`f64::is_subnormal`](https://doc.rust-lang.org/stable/std/primitive.f64.html#method.is_subnormal)
+- [`IntoIterator for array`](https://doc.rust-lang.org/stable/std/primitive.array.html#impl-IntoIterator)
+- [`{integer}::BITS`](https://doc.rust-lang.org/stable/std/primitive.usize.html#associatedconstant.BITS)
+- [`io::Error::Unsupported`](https://doc.rust-lang.org/stable/std/io/enum.ErrorKind.html#variant.Unsupported)
+- [`NonZero*::leading_zeros`](https://doc.rust-lang.org/stable/std/num/struct.NonZeroU32.html#method.leading_zeros)
+- [`NonZero*::trailing_zeros`](https://doc.rust-lang.org/stable/std/num/struct.NonZeroU32.html#method.trailing_zeros)
+- [`Option::insert`](https://doc.rust-lang.org/stable/std/option/enum.Option.html#method.insert)
+- [`Ordering::is_eq`](https://doc.rust-lang.org/stable/std/cmp/enum.Ordering.html#method.is_eq)
+- [`Ordering::is_ne`](https://doc.rust-lang.org/stable/std/cmp/enum.Ordering.html#method.is_ne)
+- [`Ordering::is_lt`](https://doc.rust-lang.org/stable/std/cmp/enum.Ordering.html#method.is_lt)
+- [`Ordering::is_gt`](https://doc.rust-lang.org/stable/std/cmp/enum.Ordering.html#method.is_gt)
+- [`Ordering::is_le`](https://doc.rust-lang.org/stable/std/cmp/enum.Ordering.html#method.is_le)
+- [`Ordering::is_ge`](https://doc.rust-lang.org/stable/std/cmp/enum.Ordering.html#method.is_ge)
+- [`OsStr::make_ascii_lowercase`](https://doc.rust-lang.org/stable/std/ffi/struct.OsStr.html#method.make_ascii_lowercase)
+- [`OsStr::make_ascii_uppercase`](https://doc.rust-lang.org/stable/std/ffi/struct.OsStr.html#method.make_ascii_uppercase)
+- [`OsStr::to_ascii_lowercase`](https://doc.rust-lang.org/stable/std/ffi/struct.OsStr.html#method.to_ascii_lowercase)
+- [`OsStr::to_ascii_uppercase`](https://doc.rust-lang.org/stable/std/ffi/struct.OsStr.html#method.to_ascii_uppercase)
+- [`OsStr::is_ascii`](https://doc.rust-lang.org/stable/std/ffi/struct.OsStr.html#method.is_ascii)
+- [`OsStr::eq_ignore_ascii_case`](https://doc.rust-lang.org/stable/std/ffi/struct.OsStr.html#method.eq_ignore_ascii_case)
+- [`Peekable::peek_mut`](https://doc.rust-lang.org/stable/std/iter/struct.Peekable.html#method.peek_mut)
+- [`Rc::increment_strong_count`](https://doc.rust-lang.org/stable/std/rc/struct.Rc.html#method.increment_strong_count)
+- [`Rc::decrement_strong_count`](https://doc.rust-lang.org/stable/std/rc/struct.Rc.html#method.decrement_strong_count)
+- [`slice::IterMut::as_slice`](https://doc.rust-lang.org/stable/std/slice/struct.IterMut.html#method.as_slice)
+- [`AsRef<[T]> for slice::IterMut`](https://doc.rust-lang.org/stable/std/slice/struct.IterMut.html#impl-AsRef%3C%5BT%5D%3E)
+- [`impl SliceIndex for (Bound<usize>, Bound<usize>)`](https://doc.rust-lang.org/stable/std/primitive.tuple.html#impl-SliceIndex%3C%5BT%5D%3E)
+- [`Vec::extend_from_within`](https://doc.rust-lang.org/stable/std/vec/struct.Vec.html#method.extend_from_within)
+
+### Other changes
+
+There are other changes in the Rust 1.53.0 release:
+check out what changed in
+[Rust](https://github.com/rust-lang/rust/blob/master/RELEASES.md#version-1530-2021-06-17),
+[Cargo](https://github.com/rust-lang/cargo/blob/master/CHANGELOG.md#cargo-153-2021-06-17),
+and [Clippy](https://github.com/rust-lang/rust-clippy/blob/master/CHANGELOG.md#rust-153).
+
+### Contributors to 1.53.0
+
+Many people came together to create Rust 1.53.0.
+We couldn't have done it without all of you.
+[Thanks!](https://thanks.rust-lang.org/rust/1.53.0/)