EnhancedSwitchBackwardMigrationInspection: insert break in statement switch, when may complete normally

java/java-impl/src/com/intellij/codeInspection/EnhancedSwitchBackwardMigrationInspection.java

@@ -210,12 +210,12 @@ public class EnhancedSwitchBackwardMigrationInspection extends AbstractBaseJavaL
       String caseValuesText = caseValues == null ? "" : ct.text(caseValues);
       PsiStatement body = rule.getBody();
       String finalBody;
-      if (!(body instanceof PsiBlockStatement) && body != null) {
+      if (body == null) {
+        finalBody = "";
+      } else if (!(body instanceof PsiBlockStatement)) {
         finalBody = generateExpressionBranch(body, ct);
       } else {
-        finalBody = StreamEx.of(ControlFlowUtils.unwrapBlock(body))
-          .map(el -> ct.text(el))
-          .joining("\n");
+        finalBody = generateBlockBranch(body, ct);
       }
       ct.grabComments(rule);
 
@@ -224,6 +224,12 @@ public class EnhancedSwitchBackwardMigrationInspection extends AbstractBaseJavaL
       return prefix + ":" + finalBody;
     }
 
+    String generateBlockBranch(@NotNull PsiStatement statement, CommentTracker ct) {
+      return StreamEx.of(ControlFlowUtils.unwrapBlock(statement))
+        .map(el -> ct.text(el))
+        .joining("\n");
+    }
+
     abstract void handleBreakInside(@NotNull PsiBreakStatement breakStatement, CommentTracker ct);
 
     abstract String generateExpressionBranch(@NotNull PsiStatement statement, CommentTracker ct);
@@ -290,5 +296,13 @@ public class EnhancedSwitchBackwardMigrationInspection extends AbstractBaseJavaL
     String generateExpressionBranch(@NotNull PsiStatement statement, CommentTracker ct) {
       return ct.text(statement) + "\nbreak;";
     }
+
+    @Override
+    String generateBlockBranch(@NotNull PsiStatement statement, CommentTracker ct) {
+      if (ControlFlowUtils.statementMayCompleteNormally(statement)) {
+        return super.generateBlockBranch(statement, ct) + "\nbreak;";
+      }
+      return super.generateBlockBranch(statement, ct);
+    }
   }
 }

java/java-tests/testData/inspection/switchExpressionBackwardMigration/afterSwitchStatements2.java

@@ -0,0 +1,19 @@
+// "Replace with old style 'switch' statement" "true"
+import java.util.*;
+
+public class Main {
+  void foo(E e) {
+      switch (e) {
+          case E1, E2:
+              System.out.println("oops");
+              break;
+          default:
+              System.out.println("impossible");
+              break;
+      }
+  }
+}
+
+enum E {
+  E1, E2;
+}

java/java-tests/testData/inspection/switchExpressionBackwardMigration/afterSwitchStatementsReturn.java

@@ -0,0 +1,19 @@
+// "Replace with old style 'switch' statement" "true"
+import java.util.*;
+
+public class Main {
+  void foo(E e) {
+      switch (e) {
+          case E1, E2:
+              System.out.println("oops");
+              break;
+          default:
+              System.out.println("impossible");
+              return;
+      }
+  }
+}
+
+enum E {
+  E1, E2;
+}

java/java-tests/testData/inspection/switchExpressionBackwardMigration/beforeSwitchStatements2.java

@@ -0,0 +1,19 @@
+// "Replace with old style 'switch' statement" "true"
+import java.util.*;
+
+public class Main {
+  void foo(E e) {
+    switch<caret> (e) {
+      case E1, E2 -> {
+        System.out.println("oops");
+      }
+      default -> {
+        System.out.println("impossible");
+      }
+    }
+  }
+}
+
+enum E {
+  E1, E2;
+}

java/java-tests/testData/inspection/switchExpressionBackwardMigration/beforeSwitchStatementsReturn.java

@@ -0,0 +1,20 @@
+// "Replace with old style 'switch' statement" "true"
+import java.util.*;
+
+public class Main {
+  void foo(E e) {
+    switch<caret> (e) {
+      case E1, E2 -> {
+        System.out.println("oops");
+      }
+      default -> {
+        System.out.println("impossible");
+        return;
+      }
+    }
+  }
+}
+
+enum E {
+  E1, E2;
+}