Compact retained elements directly in dedup_by - #5
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Summary
Move each surviving element directly into the next hole in
dedup_by, instead of swapping the discarded payload back in the other direction. We leave the initial unique prefix in place and drop duplicates as we find them. A guard restores the untouched tail if the predicate or a destructor panics.Across three Criterion benchmark pairs on x86_64 Linux, removing adjacent duplicates took 47–54% less time for 128-byte elements across inline and spilled vectors, and about 22% less for the large
u64case. The all-equal case just beyond the inline boundary showed no consistent improvement. These benchmarks used regular inputs without destructors.The added Criterion benchmarks were removed in a follow-up commit and remain in the PR history.