default_free_fn

The tracking issue for this feature is: #73014

Adds a free default() function to the std::default module. This function just forwards to Default::default(), but may remove repetition of the word "default" from the call site.

Here is an example:

#![feature(default_free_fn)]
use std::default::default;

#[derive(Default)]
struct AppConfig {
    foo: FooConfig,
    bar: BarConfig,
}

#[derive(Default)]
struct FooConfig {
    foo: i32,
}

#[derive(Default)]
struct BarConfig {
    bar: f32,
    baz: u8,
}

fn main() {
    let options = AppConfig {
        foo: default(),
        bar: BarConfig {
            bar: 10.1,
            ..default()
        },
    };
}