[java] local can be final in switches: avoid redundant computation; test data for inc operation (IDEA-229646)

GitOrigin-RevId: d53e55409a8a74c3374356f4943335e676ea0b21

java/java-analysis-impl/src/com/intellij/codeInspection/localCanBeFinal/LocalCanBeFinal.java

@@ -126,6 +126,7 @@ public class LocalCanBeFinal extends AbstractBaseJavaLocalInspectionTool impleme
         }
         super.visitCodeBlock(block);
         Set<PsiVariable> declared = getDeclaredVariables(block);
+        if (declared.isEmpty()) return;
         PsiElement anchor = block;
         if (block.getParent() instanceof PsiSwitchBlock) {
           anchor = block.getParent();

java/java-tests/testData/inspection/localCanBeFinal/SwitchBranches.java

@@ -6,10 +6,12 @@ class Test {
         long <warning descr="Variable 'k' can have 'final' modifier">k</warning>;
         k = 0;
         long l = 0;
+        int m; m = 0;
         break;
       case 2:
         k = 2;
         l = 3;
+        <error descr="Variable 'm' might not have been initialized">m</error>++;
         break;
       default:
         break;

java/java-tests/testSrc/com/intellij/java/codeInspection/LocalCanBeFinalTest.java

@@ -44,7 +44,7 @@ public class LocalCanBeFinalTest extends LightJavaCodeInsightFixtureTestCase {
     myTool.REPORT_VARIABLES = true;
     doTest();
   }
-  public void testSwitchBraches() {
+  public void testSwitchBranches() {
     myTool.REPORT_PARAMETERS = false;
     myTool.REPORT_VARIABLES = true;
     doTest();