Flexible query parser: IntervalQueryNode#toQueryString prints some fn: interval functions in a form the parser rejects or reads as a different query (fn:fuzzyTerm(abc) prints as fn:fuzzyTerm(abc 2128))
Finding LFV-748Area: queryparser / flexible StandardQueryParser interval function nodes (IntervalQueryNode#toQueryString; intervalfn FuzzyTerm, Wildcard and AnalyzedText toString)Priority: lowImpact: minorNovelty: new
AI-assisted finding, confirmed by automated checks, not yet triaged by a human Lucene committer. This site files nothing upstream.
What it shows
You parse fn:fuzzyTerm(abc), fn:wildcard(ab* 5) or fn:or("a:b" c) with the flexible syntax parser, print the node tree with toQueryString, and expect a string that StandardQueryParser reads back as the same query, as the flexible parser's package documentation promises ('a query string that can be parsed back by the original text parser'). Instead FuzzyTerm prints maxEdits and maxExpansions with no space between them (fn:fuzzyTerm(abc 2128), which re-parses as maxEdits 2128 and throws 'max edits must be 0..2'), Wildcard prints 'maxExpansions:5', a syntax error, and AnalyzedText quotes a literal only when it contains ASCII whitespace, so fn:or("a:b" c) prints the unparsable fn:or(a:b c). A quoted literal with the ideographic space U+3000 prints unquoted and re-parses, with no error, as two separate literals.
The test shows that QueryNode#toQueryString of the parsed fn:fuzzyTerm(abc) prints f:fn:fuzzyTerm(abc 2128) (maxEdits 2 and maxExpansions 128 with no space), which StandardQueryParser cannot parse back.
Expected vs actual
Expected: the printed text parses back to the same query. Actual: IllegalArgumentException: max edits must be 0..2, inclusive; got: 2128.
Files
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/facet/build/libs/lucene-facet-$V.jar
CP=$CP:$LUCENE/lucene/queries/build/libs/lucene-queries-$V.jar
CP=$CP:$LUCENE/lucene/queryparser/build/libs/lucene-queryparser-$V.jar
CP=$CP:$LUCENE/lucene/sandbox/build/libs/lucene-sandbox-$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.queryparser.flexible.standard.TestFuzzyTermToQueryStringThe module(s) facet also need their third-party runtime jars; ./gradlew -p lucene/<module> dependencies lists them.
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.