Rust 1.33.0

Language

--------

- [You can now use the cfg(target_vendor) attribute.][57465] E.g.

#[cfg(target_vendor="apple")] fn main() { println!("Hello Apple!"); }

- [Integer patterns such as in a match expression can now be exhaustive.][56362]

E.g. You can have match statement on a u8 that covers 0..=255 and

you would no longer be required to have a _ => unreachable!() case.

- [You can now have multiple patterns in if let and while let

expressions.][57532] You can do this with the same syntax as a match

expression. E.g.

  enum Creature {
Crab(String),
Lobster(String),
Person(String),
}
fn main() {
let state = Creature::Crab("Ferris");
if let Creature::Crab(name) | Creature::Person(name) = state {
println!("This creature's name is: {}", name);
}
}

- [You can now have irrefutable if let and while let patterns.][57535] Using

this feature will by default produce a warning as this behaviour can be

unintuitive. E.g. if let _ = 5 {}

- [You can now use let bindings, assignments, expression statements,

and irrefutable pattern destructuring in const functions.][57175]

- [You can now call unsafe const functions.][57067] E.g.

  const unsafe fn foo() -> i32 { 5 }
const fn bar() -> i32 {
unsafe { foo() }
}

- [You can now specify multiple attributes in a cfg_attr attribute.][57332]

E.g. #[cfg_attr(all(), must_use, optimize)]

- [You can now specify a specific alignment with the #[repr(packed)]

attribute.][57049] E.g. #[repr(packed(2))] struct Foo(i16, i32); is a struct

with an alignment of 2 bytes and a size of 6 bytes.

- [You can now import an item from a module as an _.][56303] This allows you to

import a trait's impls, and not have the name in the namespace. E.g.

  use std::io::Read as _;
// Allowed as there is only one Read in the module.
pub trait Read {}

- [You may now use Rc, Arc, and Pin as method receivers][56805].

Compiler

--------

- [You can now set a linker flavor for rustc with the -Clinker-flavor

command line argument.][56351]

- [The minimum required LLVM version has been bumped to 6.0.][56642]

- [Added support for the PowerPC64 architecture on FreeBSD.][57615]

- [The x86_64-fortanix-unknown-sgx target support has been upgraded to

tier 2 support.][57130] Visit the [platform support][platform-support] page for

information on Rust's platform support.

- [Added support for the thumbv7neon-linux-androideabi and

thumbv7neon-unknown-linux-gnueabihf targets.][56947]

- [Added support for the x86_64-unknown-uefi target.][56769]

Libraries

---------

- [The methods overflowing_{add, sub, mul, shl, shr} are now const

functions for all numeric types.][57566]

- [The methods rotate_left, rotate_right, and wrapping_{add, sub, mul, shl, shr}

are now const functions for all numeric types.][57105]

- [The methods is_positive and is_negative are now const functions for

all signed numeric types.][57105]

- [The get method for all NonZero types is now const.][57167]

- [The methods count_ones, count_zeros, leading_zeros, trailing_zeros,

swap_bytes, from_be, from_le, to_be, to_le are now const for all

numeric types.][57234]

- [Ipv4Addr::new is now a const function][57234]

Stabilized APIs

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

- [unix::FileExt::read_exact_at]

- [unix::FileExt::write_all_at]

- [Option::transpose]

- [Result::transpose]

- [convert::identity]

- [pin::Pin]

- [marker::Unpin]

- [marker::PhantomPinned]

- [Vec::resize_with]

- [VecDeque::resize_with]

- [Duration::as_millis]

- [Duration::as_micros]

- [Duration::as_nanos]

Cargo

-----

- [You can now publish crates that require a feature flag to compile with

cargo publish --features or cargo publish --all-features.][cargo/6453]

- [Cargo should now rebuild a crate if a file was modified during the initial

build.][cargo/6484]

Compatibility Notes

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

- The methods str::{trim_left, trim_right, trim_left_matches, trim_right_matches}

are now deprecated in the standard library, and their usage will now produce a warning.

Please use the str::{trim_start, trim_end, trim_start_matches, trim_end_matches}

methods instead.

- The Error::cause method has been deprecated in favor of Error::source which supports

downcasting.

- [Libtest no longer creates a new thread for each test when

--test-threads=1. It also runs the tests in deterministic order][56243]

[56243]: https://github.com/rust-lang/rust/pull/56243

[56303]: https://github.com/rust-lang/rust/pull/56303/

[56351]: https://github.com/rust-lang/rust/pull/56351/

[56362]: https://github.com/rust-lang/rust/pull/56362

[56642]: https://github.com/rust-lang/rust/pull/56642/

[56769]: https://github.com/rust-lang/rust/pull/56769/

[56805]: https://github.com/rust-lang/rust/pull/56805

[56947]: https://github.com/rust-lang/rust/pull/56947/

[57049]: https://github.com/rust-lang/rust/pull/57049/

[57067]: https://github.com/rust-lang/rust/pull/57067/

[57105]: https://github.com/rust-lang/rust/pull/57105

[57130]: https://github.com/rust-lang/rust/pull/57130/

[57167]: https://github.com/rust-lang/rust/pull/57167/

[57175]: https://github.com/rust-lang/rust/pull/57175/

[57234]: https://github.com/rust-lang/rust/pull/57234/

[57332]: https://github.com/rust-lang/rust/pull/57332/

[57465]: https://github.com/rust-lang/rust/pull/57465/

[57532]: https://github.com/rust-lang/rust/pull/57532/

[57535]: https://github.com/rust-lang/rust/pull/57535/

[57566]: https://github.com/rust-lang/rust/pull/57566/

[57615]: https://github.com/rust-lang/rust/pull/57615/

[cargo/6453]: https://github.com/rust-lang/cargo/pull/6453/

[cargo/6484]: https://github.com/rust-lang/cargo/pull/6484/

[unix::FileExt::read_exact_at]: https://doc.rust-lang.org/std/os/unix/fs/trait.FileExt.html#method.read_exact_at

[unix::FileExt::write_all_at]: https://doc.rust-lang.org/std/os/unix/fs/trait.FileExt.html#method.write_all_at

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

[Result::transpose]: https://doc.rust-lang.org/std/result/enum.Result.html#method.transpose

[convert::identity]: https://doc.rust-lang.org/std/convert/fn.identity.html

[pin::Pin]: https://doc.rust-lang.org/std/pin/struct.Pin.html

[marker::Unpin]: https://doc.rust-lang.org/stable/std/marker/trait.Unpin.html

[marker::PhantomPinned]: https://doc.rust-lang.org/nightly/std/marker/struct.PhantomPinned.html

[Vec::resize_with]: https://doc.rust-lang.org/std/vec/struct.Vec.html#method.resize_with

[VecDeque::resize_with]: https://doc.rust-lang.org/std/collections/struct.VecDeque.html#method.resize_with

[Duration::as_millis]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.as_millis

[Duration::as_micros]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.as_micros

[Duration::as_nanos]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.as_nanos

[platform-support]: https://forge.rust-lang.org/platform-support.html