Error code E0528

An array or slice pattern required more elements than were present in the matched array.

Example of erroneous code:

#![allow(unused)]
fn main() {
let r = &[1, 2];
match r {
    &[a, b, c, rest @ ..] => { // error: pattern requires at least 3
                               //        elements but array has 2
        println!("a={}, b={}, c={} rest={:?}", a, b, c, rest);
    }
}
}
ⓘ

Ensure that the matched array has at least as many elements as the pattern requires. You can match an arbitrary number of remaining elements with ..:

#![allow(unused)]
fn main() {
let r = &[1, 2, 3, 4, 5];
match r {
    &[a, b, c, rest @ ..] => { // ok!
        // prints `a=1, b=2, c=3 rest=[4, 5]`
        println!("a={}, b={}, c={} rest={:?}", a, b, c, rest);
    }
}
}