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SONARJAVA-6095 S1166 should not report on exceptions using unnamed variable _ #5436

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Merged
tomasz-tylenda-sonarsource merged 2 commits into from
Feb 5, 2026
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SONARJAVA-6095 S1166 should not report on exceptions using unnamed variable _ #5436

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SONARJAVA-6095 S1166 should not report when exception uses unnamed va…
tomasz-tylenda-sonarsource Feb 4, 2026
058eb63
Update rspec
tomasz-tylenda-sonarsource Feb 5, 2026
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3 changes: 3 additions & 0 deletions ...-checks-test-sources/default/src/main/java/checks/CatchUsesExceptionWithContextCheck.java
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Expand Up @@ -65,6 +65,9 @@ private void f(Exception x) {
System.out.println("" + e);
}
}
try {
} catch (Exception _) { // Compliant
}
}

private void g() {
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2 changes: 1 addition & 1 deletion java-checks/src/main/java/org/sonar/java/checks/CatchUsesExceptionWithContextCheck.java
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Expand Up @@ -170,7 +170,7 @@ public void visitLambdaExpression(LambdaExpressionTree lambdaExpressionTree) {

@Override
public void visitCatch(CatchTree tree) {
if (!isExcludedType(tree.parameter().type()) && !excludedCatchTrees.contains(tree)) {
if (!isExcludedType(tree.parameter().type()) && !excludedCatchTrees.contains(tree) && !tree.parameter().simpleName().isUnnamedVariable()) {
Symbol exception = tree.parameter().symbol();
usageStatusStack.addFirst(new UsageStatus(exception.usages()));
super.visitCatch(tree);
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10 changes: 10 additions & 0 deletions sonar-java-plugin/src/main/resources/org/sonar/l10n/java/rules/java/S1166.html
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Expand Up @@ -68,6 +68,16 @@ <h3>Exceptions</h3>
LOGGER.warn(message); // Compliant - exception message logged with some contextual information
}
</pre>
<p>Additionally, no issue will be raised if the exception parameter uses the unnamed variable <code>_</code>, which is available starting with Java
21. The unnamed variable makes it explicit that the exception is caught but not needed in the handler (see {rule:java:S7467}).</p>
<pre>
try {
/* ... */
} catch (Exception _) {
// Compliant - unnamed exception parameter is intentionally unused
return defaultValue;
}
</pre>
<h2>Resources</h2>
<ul>
<li> OWASP - <a href="https://owasp.org/Top10/A09_2021-Security_Logging_and_Monitoring_Failures/">Top 10 2021 Category A9 - Security Logging and
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