Intervals.ordered(X, X) with two equal sub-sources that span several positions lets the two copies of X overlap, so ordered(phrase(a, a), phrase(a, a)) matches 'a a a' and ordered(unordered(a, b), unordered(a, b)) matches 'a b a' (one b), while the same query with an equivalent but unequal second source finds nothing

Finding LFV-807Area: queries / intervals (Intervals.ordered and unorderedNoOverlaps with equal consecutive sub-sources: OrderedIntervalsSource.deduplicate, RepeatingIntervalsSource)Priority: mediumImpact: silent wrong resultsNovelty: new

Finding page for LFV-807

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

What it shows

You ask for two occurrences of X in order with Intervals.ordered(X, X), for example X = unordered(a, b) ('a near b', twice) or X = phrase(a, a), and expect the usual ordered rule that the sub-intervals do not overlap (the fn:ordered documentation says 'Source intervals must not overlap'). Instead, because the two arguments are equal, OrderedIntervalsSource.build merges them into a RepeatingIntervalsSource, which joins consecutive intervals of a single sub-iterator without checking that they are disjoint, so ordered(unordered(a, b), unordered(a, b)) matches 'a b a', which has only one b, and ordered(phrase(a, a), phrase(a, a)) matches 'a a a'. The same query with an equivalent but unequal second source, ordered(X, or(X, a term that occurs nowhere)), correctly finds nothing, and so did Lucene 8.4.1.

The test shows that Intervals.ordered(phrase(a, a), phrase(a, a)) matches the document a a a, although its only two a a intervals, [0,1] and [1,2], overlap (the two equal sub-sources are merged into a RepeatingIntervalsSource).

Expected vs actual

Expected: 0 hits, as for any ordered query whose sub-intervals would have to overlap. Actual: 1 hit (expected:<0> but was:<1>).

Files

• src/org/apache/lucene/queries/intervals/TestOrderedRepeatedPhraseOverlap.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/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.TestOrderedRepeatedPhraseOverlap

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.