Rust release · Nov 22, 2017

Rust 1.22: what's new, what was stabilized

Short answerRust 1.22 was released on Nov 22, 2017: 2 compatibility notes that can affect existing code. Point release: 1.22.1 (Nov 22, 2017).

Nov 22, 2017release date

0language stabilizations

0APIs stabilized

-new edition

← Rust 1.21 All versions Rust 1.23 →

Can it break my build?

The release lists these compatibility notes. Most only affect rare code, but read them before you raise your toolchain in CI:

[The minimum Android version that rustc can build for has been bumped
[Allowing T op= &T for numeric types has broken some type

Use it

rustup update stable        # get the newest release
rustup install 1.22          # or exactly this one
rustup override set 1.22     # pin a project to it

To require at least this version from users of your crate, set rust-version = "1.22" under [package] in Cargo.toml. Cargo then refuses to build it on older compilers with a clear message, and with resolver 3 (the default on the 2024 edition, Rust 1.85+) it also prefers dependency versions that support it.

Full release notes

Language

[non_snake_case lint now allows extern no-mangle functions][44966]
[Now accepts underscores in unicode escapes][43716]
[T op= &T now works for numeric types.][44287] eg. let mut x = 2; x += &8;
[types that impl Drop are now allowed in const and static types][44456]

Compiler

[rustc now defaults to having 16 codegen units at debug on supported platforms.][45064]
[rustc will no longer inline in codegen units when compiling for debug][45075] This should decrease compile times for debug builds.
[strict memory alignment now enabled on ARMv6][45094]
[Remove support for the PNaCl target le32-unknown-nacl][45041]

Libraries

[Allow atomic operations up to 32 bits on armv5te_unknown_linux_gnueabi][44978]
[Box<Error> now impls From<Cow<str>>][44466]
[std::mem::Discriminant is now guaranteed to be Send + Sync][45095]
[fs::copy now returns the length of the main stream on NTFS.][44895]
[Properly detect overflow in Instant += Duration.][44220]
[impl Hasher for {&mut Hasher, Box<Hasher>}][44015]
[impl fmt::Debug for SplitWhitespace.][44303]
[Option<T> now impls Try][42526] This allows for using ? with Option types.

Cargo

[Cargo will now build multi file examples in subdirectories of the examples folder that have a main.rs file.][cargo/4496]
[Changed [root] to [package] in Cargo.lock][cargo/4571] Packages with the old format will continue to work and can be updated with cargo update.
[Now supports vendoring git repositories][cargo/3992]

Misc

[libbacktrace is now available on Apple platforms.][44251]
[Stabilised the compile_fail attribute for code fences in doc-comments.][43949] This now lets you specify that a given code example will fail to compile.

Compatibility Notes

1.22.1 (Nov 22, 2017)

Update Cargo to fix an issue with macOS 10.13 "High Sierra"

Release notes from the Rust project's RELEASES.md (MIT or Apache-2.0); summaries above are ours.