SerbianAnalyzer.normalize only lower-cases and skips SerbianNormalizationFilter (Cyrillic to Latin, diacritics removed), so prefix, wildcard, fuzzy, regexp and range queries typed in Cyrillic or with č ć š ž đ miss the indexed terms

Finding LFV-534Area: analysis-common / language analyzers (SerbianAnalyzer.normalize, used by the query parsers for multi-term queries)Priority: mediumImpact: silent wrong resultsNovelty: new

Finding page for LFV-534

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 Serbian text with SerbianAnalyzer, which lower-cases, stems and then maps Cyrillic to Latin and removes diacritics (SerbianNormalizationFilter), so 'Београд' is stored as 'beograd' and 'Čačak' as 'cack', and you search with a prefix, wildcard, fuzzy, regexp or range query through a query parser, which passes the term through Analyzer.normalize, documented to give 'the representation that it would have in the index'. SerbianAnalyzer.normalize only lower-cases, so 'Беогр*' becomes the prefix 'беогр' and 'Čač*' becomes 'čač', and both find nothing while 'Beogr*' and 'Cac*' find the documents. Directly, normalize("Ђак") returns 'ђак' while the index holds 'djak', even with stemming switched off.

SerbianAnalyzer.normalize only lower-cases and skips SerbianNormalizationFilter, so it does not return the form the analyzer indexes (which the query parsers rely on for prefix, wildcard, fuzzy, regexp and range terms).

Expected vs actual

Expected: normalize("f", "Ђак") = djak (the indexed term); actual: ђак.

Files

• src/org/apache/lucene/analysis/sr/TestSerbianAnalyzerNormalize.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/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.sr.TestSerbianAnalyzerNormalize

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.