Tracking Issue for `VecDeque::truncate_to_range`

Feature gate: #![feature(vec_deque_truncate_to_range)]

This is a tracking issue for adding truncate_to_range to VecDeque.

This function can truncate both ends of a VecDeque, keeping only the specified range in the middle. This operation is O(1) if there is no Drop code.

metrics.truncate_to_range(start..end);
// is equivalent to
metrics.truncate(end);
metrics.truncate_front(metrics.len() - start);

Public API

impl<T, A: Allocator> VecDeque<T, A> {
    pub fn truncate_to_range<R>(&mut self, range: R)
    where
        R: RangeBounds<usize>;
}

Steps / History

(Remember to update the S-tracking-* label when checking boxes.)

• ACP: https://github.com/rust-lang/libs-team/issues/785
• Implementation: https://github.com/rust-lang/rust/pull/156220
• Final comment period (FCP)^1
• Stabilization PR

Unresolved Questions

• Name. Should this be truncate_to_range, or retain_range?

Start with the VecDeque::truncate_to_range public API and the Steps / History checklist, then review the linked implementation PR 156220. The remaining work is to resolve the naming question and complete the final comment period and stabilization process.