unused-peekable

Disallow peekable iterators that are never peeked

Wrapping an iterator with peekable adds buffered state when no use observes the next value.
Instead, you SHOULD use the original iterator until lookahead is required.

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

Reported

function consume(values: int32[]): void {
    const iterator = values.iterator().peekable();
    iterator.next();
}
Accepted

function consume(values: int32[]): void {
    const iterator = values.iterator();
    iterator.next();
}
Prior art

- Clippy · unusedpeekable

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