SimplePatternTokenizer's String constructors do not determinize the regexp (and ignore determinizeWorkLimit), so valid patterns such as ab|ac or http|https throw 'please determinize the incoming automaton first'

Finding LFV-526Area: analysis-common / pattern tokenizers (SimplePatternTokenizer String constructors)Priority: mediumImpact: crashNovelty: known outside Lucene

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 a tokenizer with new SimplePatternTokenizer("ab|ac") (or the three-argument String constructor with a determinizeWorkLimit) and expect a working tokenizer for any valid RegExp, as the constructors' javadoc ('See RegExp for the accepted syntax'), the sibling SimplePatternSplitTokenizer and both factories give you. Instead the constructor throws IllegalArgumentException('please determinize the incoming automaton first'): it passes new RegExp(regexp).toAutomaton() unchanged to the Automaton constructor, which rejects non-deterministic automata, and since Lucene 10.0 (LUCENE-10010) RegExp no longer determinizes its result. The determinizeWorkLimit argument is never used.

Expected vs actual

• Expected: The test passes: it asserts the documented behaviour.
• Actual: The constructor throws IllegalArgumentException('please determinize the incoming automaton first'): it passes new RegExp(regexp).toAutomaton() unchanged to the Automaton constructor, which rejects non-deterministic automata, and since Lucene 10.0 (LUCENE-10010) RegExp no longer determinizes its result.

Files

• src/org/apache/lucene/analysis/pattern/TestSimplePatternTokenizerStringCtor.java (JUnit test)

Run it

• Tested on Lucene main e1faeba08bde (2026-11-02): still reproduces.
• Tested on Lucene main ea57360912ed (2026-10-24): 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/analysis/common/build/libs/lucene-analysis-common-$V.jar
CP=$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.analysis.pattern.TestSimplePatternTokenizerStringCtor

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.