SmartChineseAnalyzer.normalize only lower-cases, but indexing folds full-width Latin letters and digits to half-width (in the tokenizer's SegTokenFilter), so full-width prefix, wildcard, regexp, range and fuzzy terms from the query parsers miss documents that the same word as a term query finds

Finding LFV-565Area: analysis-smartcn / language analyzers (SmartChineseAnalyzer normalization: Analyzer#normalize vs the width and case folding inside HMMChineseTokenizer's SegTokenFilter, used by the query parsers for multi-term queries)Priority: lowImpact: silent wrong resultsNovelty: new

Finding page for LFV-565

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 the text '我们使用Ｌｕｃｅｎｅ' (or '我们使用Lucene') with the stock SmartChineseAnalyzer and search with the classic QueryParser: the term query 'Ｌｕｃｅｎｅ' and the half-width prefix 'Luc*' find the document, so you expect the full-width prefix 'Ｌｕｃ*' to find it too. Instead it finds 0 documents, with no error: the tokenizer's SegTokenFilter folds full-width Latin letters and digits to half-width and lower-cases A-Z, so the index holds 'lucen', but SmartChineseAnalyzer.normalize, which the query parsers apply to prefix, wildcard, regexp, range and fuzzy terms, is only a LowerCaseFilter, so the query term stays full-width ('ｌｕｃ*'). Likewise Analyzer.normalize returns 'ａｂｃ' for 'ＡＢＣ' and '１２３' for '１２３' (the index holds 'abc' and '123') and 'é' for 'É' (the index keeps 'É').

The test shows that SmartChineseAnalyzer indexes the full-width word ＡＢＣ as abc, but normalize("f", "ＡＢＣ") (used by the query parsers for prefix, wildcard, regexp, range and fuzzy terms) keeps it full-width.

Expected vs actual

Expected: normalize returns the indexed term abc. Actual: ａｂｃ.

Files

• src/org/apache/lucene/analysis/cn/smart/TestSmartChineseNormalizeFullWidth.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/smartcn/build/libs/lucene-analysis-smartcn-$V.jar
CP=$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.cn.smart.TestSmartChineseNormalizeFullWidth

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.