WordBreakSpellChecker.suggestWordCombinations does not honour maxEvaluations: the counter is compared with == and the break leaves only the inner loop, so every later left term is still evaluated and a limit of 0 or less is ignored (the #12077 fix in 9.5.0 covered only suggestWordBreaks)

Finding LFV-519Area: suggest / spell (WordBreakSpellChecker word combinations)Priority: lowImpact: minorNovelty: new

AI-assisted finding, confirmed by automated checks, not yet triaged by a human Lucene committer. This site files nothing upstream.

What it shows

You call WordBreakSpellChecker.setMaxEvaluations(n), documented as 'the maximum number of word combinations to evaluate', and then suggestWordCombinations, and you expect at most n combined-term lookups and so at most n suggestions. Instead the limit cuts off only the rest of the one left term at which the counter first equals n, and every later left term is evaluated in full: with every 2-6 letter run of 'abcdef' indexed, the query [a, b, c, d, e, f], maxChanges=5 and maxEvaluations=1, 11 of the 15 combinations are evaluated and returned, and maxEvaluations=0 evaluates all 15. Nothing is thrown and the work stays bounded by the number of terms times maxChanges; only the configured cap is not applied.

The test shows that WordBreakSpellChecker.suggestWordCombinations ignores setMaxEvaluations(1) when maxChanges=2 (index {ab, bc, bcd}, terms [a, b, c, d]).

Expected vs actual

Expected at most 1 suggestion, because only 1 combination may be evaluated. Actual: 3 suggestions (ab, bc, bcd).

Files

src/org/apache/lucene/search/spell/TestWordBreakCombineMaxEvaluations.java (JUnit test)

Run it

Tested on Lucene main e1faeba08bde (2026-11-02): still reproduces.
Tested on Lucene main 645d4fe14a20 (2026-10-28): reproduced.
Recorded outcome of run 1 on Lucene main 645d4fe14a20: 1 test(s) run, 1 failed.
How to read the outcome: a failing test is the finding reproducing (the failure message states expected against actual).
Seeds: a rerun with the same seed replays the same random choices. Assertions off (-da -dsa -Dtests.asserts=false) is the production-like setting.

# Lucene checkout at the tested commit, built with: ./gradlew --no-daemon assemble   (JDK 25)
LUCENE=/path/to/lucene; V=12.0.0-SNAPSHOT
CP=$LUCENE/lucene/core/build/libs/lucene-core-$V.jar
CP=$CP:$LUCENE/lucene/codecs/build/libs/lucene-codecs-$V.jar
CP=$CP:$LUCENE/lucene/test-framework/build/libs/lucene-test-framework-$V.jar
CP=$CP:$LUCENE/lucene/analysis/common/build/libs/lucene-analysis-common-$V.jar
CP=$CP:$LUCENE/lucene/suggest/build/libs/lucene-suggest-$V.jar
CP=$CP:randomizedtesting-runner-2.9.2.jar:junit-4.13.2.jar:hamcrest-3.0.jar   # test-framework dependencies (Maven Central)
CP=$CP:junit-platform-console-standalone-6.1.3.jar   # JUnit Platform console launcher (Maven Central)

javac -d classes -cp "$CP" $(find src -name '*.java')

# run 1: assertions on, seed DEADBEEF
java -ea -esa --add-modules jdk.incubator.vector --enable-native-access=ALL-UNNAMED -Dtests.seed=DEADBEEF \
     -cp "classes:$CP" org.junit.platform.console.ConsoleLauncher \
     execute --select-class org.apache.lucene.search.spell.TestWordBreakCombineMaxEvaluations

Gradle alternative: copy the test into the matching module's src/test/ tree of the checkout and run ./gradlew -p lucene/<module> test --tests <class> -Ptests.seed=<seed> (add -Ptests.asserts=false for a run without assertions).

Feedback

Open an issue in lucene-ai-bug-hunt. Please do not open issues or pull requests in apache/lucene about this finding unless a Lucene committer agrees it should be filed.

Snapshot of 2026-11-04. AI-assisted; not yet triaged by a human Lucene committer. Feedback: open an issue in lucene-ai-bug-hunt.