inline_const

The tracking issue for this feature is: #76001

This feature allows you to use inline constant expressions. For example, you can turn this code:

fn add_one(x: i32) -> i32 { x + 1 }
const MY_COMPUTATION: i32 = 1 + 2 * 3 / 4;

fn main() {
    let x = add_one(MY_COMPUTATION);
}

into this code:

#![feature(inline_const)]

fn add_one(x: i32) -> i32 { x + 1 }
fn main() {
    let x = add_one(const { 1 + 2 * 3 / 4 });
}

You can also use inline constant expressions in patterns:

#![allow(unused)]
#![feature(inline_const)]

fn main() {
const fn one() -> i32 { 1 }

let some_int = 3;
match some_int {
    const { 1 + 2 } => println!("Matched 1 + 2"),
    const { one() } => println!("Matched const fn returning 1"),
    _ => println!("Didn't match anything :("),
}
}