Java: report local class accessed from another switch branch (IDEA-113520)

GitOrigin-RevId: 7a467fc0cda90dc1944185e83607d8a7d2579cf4

java/java-analysis-impl/src/com/intellij/codeInsight/daemon/impl/analysis/HighlightUtil.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+// Copyright 2000-2024 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.codeInsight.daemon.impl.analysis;
 
 import com.intellij.codeInsight.CodeInsightUtilCore;
@@ -2444,6 +2444,30 @@ public final class HighlightUtil {
     return null;
   }
 
+  static HighlightInfo.Builder checkLocalClassReferencedFromAnotherSwitchBranch(@NotNull PsiJavaCodeReferenceElement ref,
+                                                                                @NotNull PsiClass aClass) {
+    if (!(aClass.getParent() instanceof PsiDeclarationStatement declarationStatement) ||
+        !(declarationStatement.getParent() instanceof PsiCodeBlock codeBlock) ||
+        !(codeBlock.getParent() instanceof PsiSwitchBlock)) {
+      return null;
+    }
+    boolean classSeen = false;
+    for (PsiStatement statement : codeBlock.getStatements()) {
+      if (classSeen) {
+        if (PsiTreeUtil.isAncestor(statement, ref, true)) break;
+        if (statement instanceof PsiSwitchLabelStatement) {
+          String description =
+            JavaErrorBundle.message("local.class.referenced.from.other.switch.branch", HighlightUtil.formatClass(aClass));
+          return HighlightInfo.newHighlightInfo(HighlightInfoType.WRONG_REF).range(ref).descriptionAndTooltip(description);
+        }
+      }
+      else if (statement == declarationStatement) {
+        classSeen = true;
+      }
+    }
+    return null;
+  }
+
   static void checkSwitchExpressionHasResult(@NotNull PsiSwitchExpression switchExpression,
                                              @NotNull Consumer<? super HighlightInfo.Builder> errorSink) {
     PsiCodeBlock switchBody = switchExpression.getBody();

java/java-analysis-impl/src/com/intellij/codeInsight/daemon/impl/analysis/HighlightVisitorImpl.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+// Copyright 2000-2024 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.codeInsight.daemon.impl.analysis;
 
 import com.intellij.codeHighlighting.Pass;
@@ -1204,6 +1204,9 @@ public class HighlightVisitorImpl extends JavaElementVisitor implements Highligh
     if (result != null) {
       PsiElement resolved = result.getElement();
       if (!hasErrorResults()) add(GenericsHighlightUtil.checkRawOnParameterizedType(ref, resolved));
+      if (!hasErrorResults() && resolved instanceof PsiClass aClass) {
+        add(HighlightUtil.checkLocalClassReferencedFromAnotherSwitchBranch(ref, aClass));
+      }
       if (!hasErrorResults() && resolved instanceof PsiModifierListOwner) {
         HighlightingFeature.checkPreviewFeature(ref, myPreviewFeatureVisitor);
       }

java/java-psi-impl/src/messages/JavaErrorBundle.properties

@@ -124,6 +124,7 @@ invalid.qualified.new=Invalid qualified new
 class.name.expected=Class name expected
 no.enclosing.instance.in.scope=No enclosing instance of type ''{0}'' is in scope
 is.not.an.enclosing.class=''{0}'' is not an enclosing class
+local.class.referenced.from.other.switch.branch=Local class ''{0}'' cannot be referenced from another switch branch
 cannot.be.referenced.from.static.context=''{0}'' cannot be referenced from a static context
 no.default.constructor.available=There is no parameterless constructor available in ''{0}''
 missing.return.statement=Missing return statement

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlighting/SwitchStatement.java

@@ -21,5 +21,12 @@ class SwitchStatement {
     switch (0) {
       <error descr="Statement must be prepended with case label">return;</error>
     }
+
+    switch (0) {
+      case 0:
+        class Local {}
+      case 1:
+        <error descr="Local class 'Local' cannot be referenced from another switch branch">Local</error> x = new <error descr="Local class 'Local' cannot be referenced from another switch branch">Local</error>();
+    }
   }
 }