[java-inspections] DuplicateBranchesInSwitch: warn on empty cases if a quick-fix is available

IDEA-291071
IJ-CR-95239

GitOrigin-RevId: 2fa8efa7057f75609b59f843a6fd7539919a3150

java/java-impl-inspections/src/com/intellij/codeInspection/DuplicateBranchesInSwitchInspection.java

@@ -134,7 +134,9 @@ public final class DuplicateBranchesInSwitchInspection extends LocalInspectionTo
 
     private void highlightDuplicate(@NotNull BranchBase<?> duplicate, @NotNull BranchBase<?> original) {
       LocalQuickFix fix = isMergeCasesFixAvailable(duplicate, original) ? original.newMergeCasesFix() : null;
-      registerProblem(duplicate, duplicate.getCaseBranchMessage(), fix);
+      if (fix != null || !duplicate.isEmptyRuleBody()) {
+        registerProblem(duplicate, duplicate.getCaseBranchMessage(), fix);
+      }
     }
 
     private void highlightDefaultDuplicate(@NotNull BranchBase branch) {
@@ -166,7 +168,7 @@ public final class DuplicateBranchesInSwitchInspection extends LocalInspectionTo
       }
       PsiSwitchLabeledRuleStatement ruleStatement = (PsiSwitchLabeledRuleStatement)element;
       PsiStatement body = ruleStatement.getBody();
-      if (body != null && !(body instanceof PsiBlockStatement blockStatement && blockStatement.getCodeBlock().isEmpty())) {
+      if (body != null) {
         TryWithIdenticalCatchesInspection.collectCommentTexts(ruleStatement, commentTexts);
         Rule rule = new Rule(ruleStatement, body, ArrayUtilRt.toStringArray(commentTexts));
         commentTexts.clear();
@@ -571,6 +573,8 @@ public final class DuplicateBranchesInSwitchInspection extends LocalInspectionTo
 
     abstract LocalQuickFix newMergeWithDefaultFix();
 
+    abstract boolean isEmptyRuleBody();
+
     @Nullable
     Match match(BranchBase<?> other) {
       return getFinder().isDuplicate(other.myStatements[0], true);
@@ -729,6 +733,11 @@ public final class DuplicateBranchesInSwitchInspection extends LocalInspectionTo
       return new MergeWithDefaultBranchFix();
     }
 
+    @Override
+    boolean isEmptyRuleBody() {
+      return false;
+    }
+
     @Override
     LocalQuickFix newDeleteCaseFix() {
       return new DeleteRedundantBranchFix();
@@ -866,6 +875,11 @@ public final class DuplicateBranchesInSwitchInspection extends LocalInspectionTo
       return null;
     }
 
+    @Override
+    boolean isEmptyRuleBody() {
+      return myStatements[0] instanceof PsiBlockStatement blockStatement && blockStatement.getCodeBlock().isEmpty();
+    }
+
     @Override
     LocalQuickFix newDeleteCaseFix() {
       return new DeleteRedundantRuleFix();

java/java-tests/testData/inspection/duplicateBranchesInEnhancedSwitch/EmptyBodies.java

@@ -1,9 +0,0 @@
-class C {
-  void foo(int n) {
-    switch (n) {
-      case 1 -> {}
-      case 2 -> {}
-      case 3 -> {}
-    }
-  }
-}

java/java-tests/testData/inspection/duplicateBranchesInEnhancedSwitch/EmptyBodiesCanBeMerge.java

@@ -0,0 +1,9 @@
+class C {
+  void foo(int n) {
+    switch (n) {
+      case 1 -> {}
+      case 2 -> <weak_warning descr="Duplicate branch in 'switch'">{}</weak_warning>
+      case 3 -> <weak_warning descr="Duplicate branch in 'switch'">{}</weak_warning>
+    }
+  }
+}

java/java-tests/testData/inspection/duplicateBranchesInEnhancedSwitch/EmptyBodiesCannotBeMerge.java

@@ -0,0 +1,8 @@
+class C {
+  void foo(Object obj) {
+    switch (obj) {
+      case String s -> {}
+      case Object o -> {}
+    }
+  }
+}

java/java-tests/testSrc/com/intellij/java/codeInspection/DuplicateBranchesInEnhancedSwitchTest.kt

@@ -3,6 +3,7 @@ package com.intellij.java.codeInspection
 
 import com.intellij.JavaTestUtil
 import com.intellij.codeInspection.DuplicateBranchesInSwitchInspection
+import com.intellij.testFramework.LightProjectDescriptor
 import com.intellij.testFramework.fixtures.LightJavaCodeInsightFixtureTestCase
 
 /**
@@ -23,10 +24,15 @@ class DuplicateBranchesInEnhancedSwitchTest : LightJavaCodeInsightFixtureTestCas
   fun testCaseLabelsExpressionDefaultLast() = doTest()
   fun testCaseLabelsExpressionDifferentComments() = doTest()
   fun testCaseLabelsExpressionSameComments() = doTest()
-  fun testEmptyBodies() = doTest()
+  fun testEmptyBodiesCanBeMerge() = doTest()
+  fun testEmptyBodiesCannotBeMerge() = doTest()
 
   private fun doTest() {
     myFixture.enableInspections(DuplicateBranchesInSwitchInspection())
     myFixture.testHighlighting("${getTestName(false)}.java")
   }
+
+  override fun getProjectDescriptor(): LightProjectDescriptor {
+    return JAVA_17
+  }
 }