SONARJAVA-6842: Implement S9364: Local variables should not span switch case groups

[nathsou]

Summary

• Detect local variables declared directly in one colon-style switch case group and accessed from later groups.
• Report later cross-group accesses as secondary locations while avoiding arrow rules, nested declarations, and no-semantic false positives.
• Add focused statement, expression, boundary, and no-semantic tests plus generated rule metadata.

Links

• Jira: https://sonarsource.atlassian.net/browse/SONARJAVA-6842
• RSPEC PR: https://github.com/SonarSource/rspec/pull/7956

Test plan

• mvn -pl java-checks -am test -Dtest=LocalVariablesShouldNotSpanSwitchCaseGroupsCheckTest -Dsurefire.failIfNoSpecifiedTests=false

AI disclosure

• LLM model used for implementation: gpt-5.6-sol-medium

[hashicorp-vault-sonar-prod]

SONARJAVA-6842

[gitar-bot]

Code Review ✅ Approved 1 resolved / 1 findings

Implements rule S9364 to detect local variables spanning colon-style switch case groups, addressing the wrong secondary offset for 'outer' in the nested switch test. No issues found.

✅ 1 resolved

✅ Bug: Wrong secondary offset for 'outer' in nested switch test

📄 java-checks-test-sources/default/src/main/java/checks/LocalVariablesShouldNotSpanSwitchCaseGroupsCheckSample.java:144 📄 java-checks-test-sources/default/src/main/java/checks/LocalVariablesShouldNotSpanSwitchCaseGroupsCheckSample.java:149 📄 java-checks-test-sources/default/src/main/java/checks/LocalVariablesShouldNotSpanSwitchCaseGroupsCheckSample.java:150
The check reports the secondary location at the first access to the symbol in each later group (FirstSymbolAccessVisitor). For outer (declared line 144), the first access in the default group is outer = 1; on line 149, i.e. offset +5 — not +6, which points at line 150 (int nested = 0;, unrelated to outer). The secondary=+6 expectation on line 144 will not match the actual issue and the test should fail. Change it to secondary=+5.

Implementation Status ✅ 2 of 2 objectives covered

✅ SONARJAVA-6842 - 2 of 2 objectives covered

This PR implements rule S9364 to report local variable declarations in colon-style switch statements and expressions when accessed from later distinct case groups, using the declaration identifier as the primary location and the first access in each later case group as a secondary location with the specified message.

✅ 2 covered here

• ✅ Use the declaration identifier as the primary location and the first access in each later case group as a secondary location with the message 'Accessed from this later case group.'
• ✅ Implement rule S9364 to report local variable declarations in colon-style switch statements and expressions when accessed from a later distinct case group

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[sonarqube-next]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
0 Dependency risks
96.6% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube