Tessellator: when three or more holes meet at one vertex P, maybeMergeHoleWithSharedVertices joins the hole whose left-most vertex is P to the first copy of P in ring order (since #15700) even when the hole lies outside that copy's wedge, so LatLonShape and XYShape reject a valid polygon with 'Unable to Tessellate shape' depending on the order of its holes; upstream's own LUCENE-9400 test polygon is rejected in 3 of its 6 hole orders (regression in 10.4.0)

Finding LFV-762Area: geo / Tessellator hole elimination (polygon indexing for LatLonShape and XYShape)Priority: lowImpact: crashNovelty: new

Finding page for LFV-762

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 valid polygon whose three holes meet only at one corner P, for example the triangle (0,0) (7,12) (12,2) with the holes A (8,8) (6,7) (7,6), B (9,3) (10,4) (7,6) and C (6,6) (6,4) (7,4) (7,6), which all touch at P=(7,6) (the Tessellator javadoc allows 'Holes may only touch at one vertex'), and you expect XYShape.createIndexableFields or LatLonShape.createIndexableFields to return its triangles, as 10.3.x does for every hole order. Since #15700 (first released in 10.4.0), once the first holes are joined at P the ring holds several copies of P, each bounding a different wedge around P, and when hole B (whose left-most vertex is P) is joined, the Tessellator takes the first copy of P in ring order, through an index comparison that depends on the input order of the holes, without checking that B lies in that copy's wedge. For the hole orders ABC, ACB and BAC this picks a wrong copy and both calls throw IllegalArgumentException 'Unable to Tessellate shape', and upstream's own LUCENE-9400 regression polygon (TestTessellator.testComplexPolygon41) is likewise rejected in 3 of its 6 hole orders.

The test shows that upstream's own LUCENE-9400 polygon (TestTessellator#testComplexPolygon41), with its third hole listed first, is rejected by LatLonShape.createIndexableFields, although the original hole order is accepted.

Expected vs actual

Expected the polygon to index as with the original hole order; actual IllegalArgumentException: Unable to Tessellate shape. Possible malformed shape detected. (-ea and -da).

Files

Run it

# 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=$CP:randomizedtesting-runner-2.9.2.jar:junit-4.13.2.jar:hamcrest-3.0.jar   # test-framework dependencies (Maven Central)
CP=$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.document.TestTessellatorThreeHolesSharedVertex

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 2026-11-03. AI-assisted; not yet triaged by a human Lucene committer. Feedback: open an issue in lucene-ai-bug-hunt.