Intervals.ordered(a, a) and Intervals.unordered(a, a) report minExtent() 1, so the default disjunction rewrite under phrase/maxgaps leaves or(ordered(a, a), a) unsplit and phrase(x, or(ordered(a, a), a), c) misses 'x a a c'

Finding LFV-805Area: queries / intervals (RepeatingIntervalsSource.minExtent for ordered/unordered of equal sub-sources; Disjunctions rewrite under phrase/maxgaps)Priority: lowImpact: silent wrong resultsNovelty: new

Finding page for LFV-805

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

What it shows

You search with Intervals.phrase(x, Intervals.or(Intervals.ordered(a, a), a), c), meaning 'x, then either a a or a, then c', on the text 'x a a c' and expect a hit, because phrase(x, ordered(a, a), c) alone matches it and Intervals.or is documented to rewrite itself under gap-sensitive parents so that alternatives of different lengths are not lost. Instead it finds nothing: ordered(a, a) and unordered(a, a) are built as a RepeatingIntervalsSource whose minExtent() returns the minExtent of a single 'a' (1) instead of 2, the rewrite assumes that only single-position sources report 1 and so keeps or(ordered(a, a), a) as one OR, and inside that OR the interval of 'a a' contains the interval of a single 'a' and is minimized away. The same query with two different words, phrase(x, or(ordered(a, b), a), c) on 'x a b c', matches as expected.

The test shows that Intervals.unordered(a, a) reports minExtent() 1, so the default or() rewrite under phrase keeps or(unordered(a, a), a) as one OR and phrase(x, or(unordered(a, a), a), c) misses x a a c.

Expected vs actual

Expected: 1 hit (the alternative unordered(a, a) covers a a). Actual: 0 hits.

Files

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

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.