MultiTermIntervalsSource.matches() checks the expansion limit with a post-increment ('count++ > maxExpansions'), so Weight#matches, and highlighting through it, accepts a document with exactly maxExpansions + 1 matching terms, where the javadoc and the search path (which uses '++count') reject it (IllegalStateException; IndexSearcher.TooManyClauses on main since #16899)
Finding LFV-462Area: queries / intervals (MultiTermIntervalsSource behind Intervals.prefix, wildcard, regexp, range, fuzzyTerm and multiterm; Weight#matches / IntervalsSource#matches)Priority: lowImpact: wrong errorNovelty: 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 build IntervalQuery("f", Intervals.prefix(new BytesRef("p"), 2)) over a document 'pa pb pc' (three terms match p*) and call Weight#matches for it, as a highlighter does. You expect the over-expansion exception (IllegalStateException; IndexSearcher.TooManyClauses on main since #16899), because the javadoc says the source throws if the prefix 'expands to more than maxExpansions terms', and searching the same query on the same segment does throw. Instead matches() tests 'count++ > maxExpansions' after adding each term, so it returns a Matches for exactly maxExpansions + 1 matching terms in the document and throws only at maxExpansions + 2; the same holds for wildcard, regexp, range, fuzzyTerm and multiterm.
The test shows that Weight#matches for IntervalQuery("f", Intervals.prefix(new BytesRef("p"), 2)) on one document pa pb pc (3 = maxExpansions + 1 matching terms) returns a Matches, while searching the same query throws (MultiTermIntervalsSource.matches() tests count++ > maxExpansions, the search path ++count).
Expected vs actual
Expected IndexSearcher.TooManyClauses (javadoc: thrown if the prefix expands to more than maxExpansions terms); actual: no exception (Expected exception TooManyClauses but no exception was thrown).
Files
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/queries/build/libs/lucene-queries-$V.jar
CP=$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.queries.intervals.TestMultiTermIntervalsMatchesLimitGradle 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.