FA-46638 / Bounded deques / Member archive

Empty deque borrow unnecessarily pins backing storage · case 03

Empty deque borrow unnecessarily pins backing storage.

Member previewVariant 3 · 3 implementations · 7 checks per implementation

Case contract

Borrow a valid logical subrange from a bounded ring as at most two physical spans. Reject negative or out-of-live-range requests. Borrow captures the current epoch and pins storage only for nonempty ranges.

Why this case matters

Controlled bounded deque implementation model with explicit storage and lifecycle observations.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
3	`[true, [], 3, 0, true]`	`[true, [], 3, 0, false]`	Failed

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