1.33.0 #

Released on: 28 February, 2019
Branched from master on: 11 January, 2019

Language #

You can now use the cfg(target_vendor) attribute. E.g. #[cfg(target_vendor="apple")] fn main() { println!("Hello Apple!"); }
Integer patterns such as in a match expression can now be exhaustive. 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. 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. 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.

You can now call unsafe const functions. 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. E.g. #[cfg_attr(all(), must_use, optimize)]
You can now specify a specific alignment with the #[repr(packed)] attribute. 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 _. 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.

Compiler #

Libraries #

Stabilized APIs #

Cargo #

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