Rust 1.40.0

Language

--------

- [You can now use tuple structs and tuple enum variant's constructors in

const contexts.][65188] e.g.

  pub struct Point(i32, i32);
const ORIGIN: Point = {
let constructor = Point;
constructor(0, 0)
};

- [You can now mark structs, enums, and enum variants with the #[non_exhaustive] attribute to

indicate that there may be variants or fields added in the future.][64639]

For example this requires adding a wild-card branch (_ => {}) to any match

statements on a non-exhaustive enum. [(RFC 2008)]

- [You can now use function-like procedural macros in extern blocks and in

type positions.][63931] e.g. type Generated = macro!();

- [Function-like and attribute procedural macros can now emit

macro_rules! items, so you can now have your macros generate macros.][64035]

- [The meta pattern matcher in macro_rules! now correctly matches the modern

attribute syntax.][63674] For example (#[$m:meta]) now matches #[attr],

#[attr{tokens}], #[attr[tokens]], and #[attr(tokens)].

Compiler

--------

- [Added tier 3 support\* for the

thumbv7neon-unknown-linux-musleabihf target.][66103]

- [Added tier 3 support for the

aarch64-unknown-none-softfloat target.][64589]

- [Added tier 3 support for the mips64-unknown-linux-muslabi64, and

mips64el-unknown-linux-muslabi64 targets.][65843]

\* Refer to Rust's [platform support page][platform-support-doc] for more

information on Rust's tiered platform support.

Libraries

---------

- [The is_power_of_two method on unsigned numeric types is now a const function.][65092]

Stabilized APIs

---------------

- [BTreeMap::get_key_value]

- [HashMap::get_key_value]

- [Option::as_deref_mut]

- [Option::as_deref]

- [Option::flatten]

- [UdpSocket::peer_addr]

- [f32::to_be_bytes]

- [f32::to_le_bytes]

- [f32::to_ne_bytes]

- [f64::to_be_bytes]

- [f64::to_le_bytes]

- [f64::to_ne_bytes]

- [f32::from_be_bytes]

- [f32::from_le_bytes]

- [f32::from_ne_bytes]

- [f64::from_be_bytes]

- [f64::from_le_bytes]

- [f64::from_ne_bytes]

- [mem::take]

- [slice::repeat]

- [todo!]

Cargo

-----

- [Cargo will now always display warnings, rather than only on

fresh builds.][cargo/7450]

- [Feature flags (except --all-features) passed to a virtual workspace will

now produce an error.][cargo/7507] Previously these flags were ignored.

- [You can now publish dev-dependencies without including

a version.][cargo/7333]

Misc

----

- [You can now specify the #[cfg(doctest)] attribute to include an item only

when running documentation tests with rustdoc.][63803]

Compatibility Notes

-------------------

- [As previously announced, any previous NLL warnings in the 2015 edition are

now hard errors.][64221]

- [The include! macro will now warn if it failed to include the

entire file.][64284] The include! macro unintentionally only includes the

first _expression_ in a file, and this can be unintuitive. This will become

either a hard error in a future release, or the behavior may be fixed to include all expressions as expected.

- [Using #[inline] on function prototypes and consts now emits a warning under

unused_attribute lint.][65294] Using #[inline] anywhere else inside traits

or extern blocks now correctly emits a hard error.

[65294]: https://github.com/rust-lang/rust/pull/65294/

[66103]: https://github.com/rust-lang/rust/pull/66103/

[65843]: https://github.com/rust-lang/rust/pull/65843/

[65188]: https://github.com/rust-lang/rust/pull/65188/

[65092]: https://github.com/rust-lang/rust/pull/65092/

[64589]: https://github.com/rust-lang/rust/pull/64589/

[64639]: https://github.com/rust-lang/rust/pull/64639/

[64221]: https://github.com/rust-lang/rust/pull/64221/

[64284]: https://github.com/rust-lang/rust/pull/64284/

[63931]: https://github.com/rust-lang/rust/pull/63931/

[64035]: https://github.com/rust-lang/rust/pull/64035/

[63674]: https://github.com/rust-lang/rust/pull/63674/

[63803]: https://github.com/rust-lang/rust/pull/63803/

[cargo/7450]: https://github.com/rust-lang/cargo/pull/7450/

[cargo/7507]: https://github.com/rust-lang/cargo/pull/7507/

[cargo/7333]: https://github.com/rust-lang/cargo/pull/7333/

[(rfc 2008)]: https://rust-lang.github.io/rfcs/2008-non-exhaustive.html

[f32::to_be_bytes]: https://doc.rust-lang.org/std/primitive.f32.html#method.to_be_bytes

[f32::to_le_bytes]: https://doc.rust-lang.org/std/primitive.f32.html#method.to_le_bytes

[f32::to_ne_bytes]: https://doc.rust-lang.org/std/primitive.f32.html#method.to_ne_bytes

[f64::to_be_bytes]: https://doc.rust-lang.org/std/primitive.f64.html#method.to_be_bytes

[f64::to_le_bytes]: https://doc.rust-lang.org/std/primitive.f64.html#method.to_le_bytes

[f64::to_ne_bytes]: https://doc.rust-lang.org/std/primitive.f64.html#method.to_ne_bytes

[f32::from_be_bytes]: https://doc.rust-lang.org/std/primitive.f32.html#method.from_be_bytes

[f32::from_le_bytes]: https://doc.rust-lang.org/std/primitive.f32.html#method.from_le_bytes

[f32::from_ne_bytes]: https://doc.rust-lang.org/std/primitive.f32.html#method.from_ne_bytes

[f64::from_be_bytes]: https://doc.rust-lang.org/std/primitive.f64.html#method.from_be_bytes

[f64::from_le_bytes]: https://doc.rust-lang.org/std/primitive.f64.html#method.from_le_bytes

[f64::from_ne_bytes]: https://doc.rust-lang.org/std/primitive.f64.html#method.from_ne_bytes

[option::flatten]: https://doc.rust-lang.org/std/option/enum.Option.html#method.flatten

[option::as_deref]: https://doc.rust-lang.org/std/option/enum.Option.html#method.as_deref

[option::as_deref_mut]: https://doc.rust-lang.org/std/option/enum.Option.html#method.as_deref_mut

[hashmap::get_key_value]: https://doc.rust-lang.org/std/collections/struct.HashMap.html#method.get_key_value

[btreemap::get_key_value]: https://doc.rust-lang.org/std/collections/struct.BTreeMap.html#method.get_key_value

[slice::repeat]: https://doc.rust-lang.org/std/primitive.slice.html#method.repeat

[mem::take]: https://doc.rust-lang.org/std/mem/fn.take.html

[udpsocket::peer_addr]: https://doc.rust-lang.org/std/net/struct.UdpSocket.html#method.peer_addr

[todo!]: https://doc.rust-lang.org/std/macro.todo.html