Error code E0730

An array without a fixed length was pattern-matched.

Erroneous code example:

#![allow(unused)] fn main() { fn is_123<const N: usize>(x: [u32; N]) -> bool { match x { [1, 2, ..] => true, // error: cannot pattern-match on an // array without a fixed length _ => false } } }

To fix this error, you have two solutions:

  1. Use an array with a fixed length.
  2. Use a slice.

Example with an array with a fixed length:

#![allow(unused)] fn main() { fn is_123(x: [u32; 3]) -> bool { // We use an array with a fixed size match x { [1, 2, ..] => true, // ok! _ => false } } }

Example with a slice:

#![allow(unused)] fn main() { fn is_123(x: &[u32]) -> bool { // We use a slice match x { [1, 2, ..] => true, // ok! _ => false } } }