[rustc.git] / src / librustc_error_codes / error_codes / E0730.md

An array without a fixed length was pattern-matched.

Example of erroneous code:

```compile_fail,E0730
#![feature(const_generics)]

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
    }
}
```

Ensure that the pattern is consistent with the size of the matched
array. Additional elements can be matched with `..`:

```
let r = &[1, 2, 3, 4];
match r {
    &[a, b, ..] => { // ok!
        println!("a={}, b={}", a, b);
    }
}
```
Commit	Line	Data
60c5eb7d XL	1	An array without a fixed length was pattern-matched.
	2
	3	Example of erroneous code:
	4
	5	```compile_fail,E0730
	6	#![feature(const_generics)]
	7
	8	fn is_123<const N: usize>(x: [u32; N]) -> bool {
	9	match x {
ba9703b0 XL	10	[1, 2, ..] => true, // error: cannot pattern-match on an
ba9703b0 XL	11	// array without a fixed length
60c5eb7d XL	12	_ => false
	13	}
	14	}
	15	```
	16
	17	Ensure that the pattern is consistent with the size of the matched
	18	array. Additional elements can be matched with `..`:
	19
	20	```
60c5eb7d XL	21	let r = &[1, 2, 3, 4];
	22	match r {
	23	&[a, b, ..] => { // ok!
	24	println!("a={}, b={}", a, b);
	25	}
	26	}
	27	```