drain-collect

Disallow draining a collection only to collect the same elements again

Draining an entire collection and collecting it into the same representation allocates replacement storage.
Instead, you SHOULD call take to move out the existing collection and leave its default value.

take transfers the existing allocation to the returned collection, so the emptied source no longer retains its capacity.

- Category: performance
- Level: warning
- Fix: none
- Scope: module

Reported

function removeAll(values: &exclusive int32[]): int32[] {
    return values.drain().toArray();
}
Accepted

import { take } from "destack:memory";

function removeAll(values: &exclusive int32[]): int32[] {
    return take(values);
}
Prior art

- Clippy · draincollect

language/linter/src/rules/performance/draincollect.rs:6