Weight#matches of Intervals.atLeast, or iterating the Matches it returns, throws IllegalStateException (AssertionError with -ea) for a matching document once an Intervals.or(...) source has run out of intervals, so default UnifiedHighlighter highlighting of such a query fails

Finding LFV-806Area: queries / intervals (Intervals.atLeast Matches path: MinimumShouldMatchIntervalsSource, CachingMatchesIterator)Priority: mediumImpact: crashNovelty: known upstream

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

What it shows

You index 'a c b a' and ask Weight#matches, or the default UnifiedHighlighter, for Intervals.atLeast(2, term a, term b, or(term c, term d)); you expect the positions [0,1] [1,2] [2,3] that the query's own interval iterator returns and that the control atLeast(2, a, b, c) gives, and the snippet 'a c b a'. Instead iterating the Matches throws IllegalStateException (AssertionError with -ea) from DisjunctionIntervalIterator.currentOrd and the whole highlight call fails, also for the query text 'fn:atLeast(2 a b fn:or(c d))': atLeast's match callback asks every source for its sub-matches, including the or() source that has no interval left and that atLeast has already dropped. For some documents Weight#matches itself throws (atLeast(2, or(c, d), b, phrase(a, b)) on 'c a b').

Expected vs actual

Expected: You expect the positions [0,1] [1,2] [2,3] that the query's own interval iterator returns and that the control atLeast(2, a, b, c) gives, and the snippet 'a c b a'.
Actual: Iterating the Matches throws IllegalStateException (AssertionError with -ea) from DisjunctionIntervalIterator.currentOrd and the whole highlight call fails, also for the query text 'fn:atLeast(2 a b fn:or(c d))': atLeast's match callback asks every source for its sub-matches, including the or() source that has no interval left and that atLeast has already dropped.

Files

Run it

Tested on Lucene main e1faeba08bde (2026-11-02): still reproduces.
Tested on Lucene main a9779ef3c193 (2026-10-26): reproduced.
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/facet/build/libs/lucene-facet-$V.jar
CP=$CP:$LUCENE/lucene/highlighter/build/libs/lucene-highlighter-$V.jar
CP=$CP:$LUCENE/lucene/memory/build/libs/lucene-memory-$V.jar
CP=$CP:$LUCENE/lucene/queries/build/libs/lucene-queries-$V.jar
CP=$CP:$LUCENE/lucene/queryparser/build/libs/lucene-queryparser-$V.jar
CP=$CP:$LUCENE/lucene/sandbox/build/libs/lucene-sandbox-$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 off (production-like), seed DEADBEEF
java -da -dsa -Dtests.asserts=false --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.TestAtLeastMatchesExhaustedDisjunction \
       --select-class org.apache.lucene.queries.intervals.TestAtLeastMatchesReachability

The module(s) facet also need their third-party runtime jars; ./gradlew -p lucene/<module> dependencies lists them.

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.