[rustc.git] / compiler / rustc_error_codes / src / error_codes / E0579.md

A lower range wasn't less than the upper range.

Erroneous code example:

```compile_fail,E0579
#![feature(exclusive_range_pattern)]

fn main() {
    match 5u32 {
        // This range is ok, albeit pointless.
        1..2 => {}
        // This range is empty, and the compiler can tell.
        5..5 => {} // error!
    }
}
```

When matching against an exclusive range, the compiler verifies that the range
is non-empty. Exclusive range patterns include the start point but not the end
point, so this is equivalent to requiring the start of the range to be less
than the end of the range.
Commit	Line	Data
f9f354fc	1	A lower range wasn't less than the upper range.
60c5eb7d XL	2
	3	Erroneous code example:
	4
	5	```compile_fail,E0579
	6	#![feature(exclusive_range_pattern)]
	7
	8	fn main() {
	9	match 5u32 {
	10	// This range is ok, albeit pointless.
2b03887a	11	1..2 => {}
60c5eb7d	12	// This range is empty, and the compiler can tell.
2b03887a	13	5..5 => {} // error!
60c5eb7d XL	14	}
	15	}
	16	```
f9f354fc XL	17
	18	When matching against an exclusive range, the compiler verifies that the range
	19	is non-empty. Exclusive range patterns include the start point but not the end
	20	point, so this is equivalent to requiring the start of the range to be less
	21	than the end of the range.