Formal models and scripts: hunspell

Tools: Python

These are the working models and scripts this part of the hunt used. Some encode the code as it is (a counterexample is the expected result), others a fixed or correct variant; read the header comment of each file. Paths inside them were replaced by placeholders such as $LUCENE (a Lucene checkout) and $WORK.

Findings

• Hunspell spell-checker: CHECKCOMPOUNDTRIPLE misses an x|xx triple letter (one letter before the boundary, two after) at the second and later boundaries of a compound, so words such as operabareeel (opera + bare|eel) are accepted (absolute break position compared with the tail's relative length) (finding LFV-373; repro · finding page)
• Hunspell spell-checker: a CHECKCOMPOUNDPATTERN simplified compound form (the optional replacement field) after the first compound part is checked from the start of the whole word, so valid compounds such as dampfschiffahrt (dampf + schiff|fahrt with 'ff f ff') are rejected and some words (schiffschiffahrt, or auu with 'u u u') make spell()/suggest() throw StackOverflowError (expandReplacement returns offset 0 over an array that still holds the earlier parts) (finding LFV-377; repro · finding page)
• Hunspell: a bracket or dot affix condition with fewer character patterns than the strip is checked against the wrong end of the strip (a suffix rule at the strip's start, a prefix rule at its end), so the rule never applies when it should, or always applies when it should not (finding LFV-374; repro · finding page)

Files

• affixcondition-short-condition-wrong-strip-end/model/affixcond_z3.py (used for LFV-374)
• compound-pattern-replacement-loses-offset/model/cmp.py (used for LFV-377)
• compound-triple-check-absolute-offset/model/cmp.py (used for LFV-373)

How to run

• Python: python3 <file>.py; scripts that import z3 need the z3-solver package.

Snapshot of 2026-11-03. AI-assisted; not yet triaged by a human Lucene committer. Feedback: open an issue in lucene-ai-bug-hunt.