suggest struct constructor instead of mutable object + field mod

[oli-obk]

If you have a struct where all fields are public, then you should never do let mut a = A::default(); a.x = 42; but instead use a constructor with .. A::default() at the end:

#[derive(Default)]
struct A {
    i: i32,
    j: i64,
}

fn main() {
    let mut a: A = Default::default();
    a.i = 42;
}

fn should_be() {
    let a = A {
        i: 42,
        .. Default::default()
    };
}