History-based Improvement of the Co-change Suggestion Capability of FLeCCS

FLeCCS is a technique that suggests code fragments likely to need a matching change (co-change candidates), based only on how similar two fragments look on the page. It never checks whether fragments have actually changed together in the past, so it misses real candidates that happen to be worded differently. This paper introduces RT-FLeCCS, which mines a system’s own revision history as method-level association rules using Tarmaq, keeps only the rules whose support and confidence clear chosen thresholds, and merges the result into FLeCCS’s suggestions. Across four open-source systems (774 to 1700 revisions each, in C and Java), RT-FLeCCS raises recall over plain FLeCCS by 53% to 170% and F-score by 33% to 90%, while giving up almost nothing in precision. A support threshold of 1 paired with a confidence threshold of 0.5 gives a reliable general-purpose setting across all four systems.