prefer-length-over-count

Prefer stored array length over counting an unchanged iterator

Counting every value from an unchanged array iterator performs linear work to recover the array's stored length.
Instead, you SHOULD read length from the array directly.

- Category: performance
- Level: warning
- Fix: automatic
- Scope: module

Reported

function length(values: int32[]): isize {
    return values.iterator().count();
}
Accepted

function length(values: int32[]): isize {
    return values.length;
}
Prior art

- Clippy · itercount

language/linter/src/rules/performance/preferlengthovercount.rs:8