[java] Disallow local sealed/non-sealed classes

This is apparently not valid.

pmd-java/etc/grammar/Java.jjt

@@ -619,7 +619,7 @@ public class JavaParser {
       return false;
   }
 
-  private boolean classModifierLookahead() {
+  private boolean classModifierForLocalTypesLookahead() {
       Token next = getToken(1);
       return next.kind == AT
         || next.kind == PUBLIC
@@ -628,9 +628,7 @@ public class JavaParser {
         || next.kind == ABSTRACT
         || next.kind == STATIC
         || next.kind == FINAL
-        || next.kind == STRICTFP
+        || next.kind == STRICTFP;
-        || isSealedClassSupported() && isKeyword("sealed")
-        || isSealedClassSupported() && isNonSealedModifier();
   }
 
   private boolean localTypeDeclLookahead() {
@@ -2144,7 +2142,7 @@ void BlockStatement():
         }
         ";"
     )
-| LOOKAHEAD({classModifierLookahead() || localTypeDeclLookahead()})
+| LOOKAHEAD({classModifierForLocalTypesLookahead() || localTypeDeclLookahead()})
     mods=Modifiers()
     LocalTypeDecl(mods)
 | LOOKAHEAD(Type() <IDENTIFIER>)

pmd-java/src/test/java/net/sourceforge/pmd/lang/java/ast/Java17TreeDumpTest.java

@@ -72,4 +72,8 @@ public class Java17TreeDumpTest extends BaseTreeDumpTest {
         java17p.parseResource("expression/Expr.java"); // make sure we can parse it with preview as well
     }
 
+    @Test
+    public void localVars() {
+        doTest("LocalVars");
+    }
 }

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/ast/jdkversiontests/java17/LocalVars.java

@@ -0,0 +1,15 @@
+/*
+ * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
+ */
+
+public class LocalVars {
+    
+    public void aMethod() {
+        String sealed = null;
+
+        sealed = this.getClass().getName();
+
+        // error: sealed or non-sealed local classes are not allowed
+        // sealed class LocalSealedClass {}
+    }
+}

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/ast/jdkversiontests/java17/LocalVars.txt

@@ -0,0 +1,39 @@
++- CompilationUnit[@PackageName = "", @declarationsAreInDefaultPackage = true]
+   +- TypeDeclaration[]
+      +- ClassOrInterfaceDeclaration[@Abstract = false, @BinaryName = "LocalVars", @Default = false, @Final = false, @Image = "LocalVars", @Interface = false, @Local = false, @Modifiers = 1, @Native = false, @Nested = false, @NonSealed = false, @PackagePrivate = false, @Private = false, @Protected = false, @Public = true, @Sealed = false, @SimpleName = "LocalVars", @Static = false, @Strictfp = false, @Synchronized = false, @Transient = false, @TypeKind = TypeKind.CLASS, @Volatile = false]
+         +- ClassOrInterfaceBody[@AnonymousInnerClass = false, @EnumChild = false]
+            +- ClassOrInterfaceBodyDeclaration[@AnonymousInnerClass = false, @EnumChild = false, @Kind = DeclarationKind.METHOD]
+               +- MethodDeclaration[@Abstract = false, @Arity = 0, @Default = false, @Final = false, @InterfaceMember = false, @Kind = MethodLikeKind.METHOD, @MethodName = "aMethod", @Modifiers = 1, @Name = "aMethod", @Native = false, @PackagePrivate = false, @Private = false, @Protected = false, @Public = true, @Static = false, @Strictfp = false, @Synchronized = false, @SyntacticallyAbstract = false, @SyntacticallyPublic = true, @Transient = false, @Void = true, @Volatile = false]
+                  +- ResultType[@Void = true, @returnsArray = false]
+                  +- MethodDeclarator[@Image = "aMethod", @ParameterCount = 0]
+                  |  +- FormalParameters[@ParameterCount = 0, @Size = 0]
+                  +- Block[@containsComment = true]
+                     +- BlockStatement[@Allocation = false]
+                     |  +- LocalVariableDeclaration[@Abstract = false, @Array = false, @ArrayDepth = 0, @Default = false, @Final = false, @Modifiers = 0, @Native = false, @PackagePrivate = true, @Private = false, @Protected = false, @Public = false, @Static = false, @Strictfp = false, @Synchronized = false, @Transient = false, @TypeInferred = false, @VariableName = "sealed", @Volatile = false]
+                     |     +- Type[@Array = false, @ArrayDepth = 0, @ArrayType = false, @TypeImage = "String"]
+                     |     |  +- ReferenceType[@Array = false, @ArrayDepth = 0]
+                     |     |     +- ClassOrInterfaceType[@AnonymousClass = false, @Array = false, @ArrayDepth = 0, @Image = "String", @ReferenceToClassSameCompilationUnit = false]
+                     |     +- VariableDeclarator[@Initializer = true, @Name = "sealed"]
+                     |        +- VariableDeclaratorId[@Array = false, @ArrayDepth = 0, @ArrayType = false, @ExceptionBlockParameter = false, @ExplicitReceiverParameter = false, @Field = false, @Final = false, @ForeachVariable = false, @FormalParameter = false, @Image = "sealed", @LambdaParameter = false, @LocalVariable = true, @Name = "sealed", @PatternBinding = false, @ResourceDeclaration = false, @TypeInferred = false, @VariableName = "sealed"]
+                     |        +- VariableInitializer[]
+                     |           +- Expression[@StandAlonePrimitive = false]
+                     |              +- PrimaryExpression[]
+                     |                 +- PrimaryPrefix[@SuperModifier = false, @ThisModifier = false]
+                     |                    +- Literal[@CharLiteral = false, @DoubleLiteral = false, @EscapedStringLiteral = null, @FloatLiteral = false, @IntLiteral = false, @LongLiteral = false, @SingleCharacterStringLiteral = false, @StringLiteral = false, @TextBlock = false, @TextBlockContent = null, @ValueAsDouble = NaN, @ValueAsFloat = NaN, @ValueAsInt = 0, @ValueAsLong = 0]
+                     |                       +- NullLiteral[]
+                     +- BlockStatement[@Allocation = false]
+                        +- Statement[]
+                           +- StatementExpression[]
+                              +- PrimaryExpression[]
+                              |  +- PrimaryPrefix[@SuperModifier = false, @ThisModifier = false]
+                              |     +- Name[@Image = "sealed"]
+                              +- AssignmentOperator[@Compound = false, @Image = "="]
+                              +- Expression[@StandAlonePrimitive = false]
+                                 +- PrimaryExpression[]
+                                    +- PrimaryPrefix[@SuperModifier = false, @ThisModifier = true]
+                                    +- PrimarySuffix[@ArgumentCount = -1, @Arguments = false, @ArrayDereference = false, @Image = "getClass"]
+                                    +- PrimarySuffix[@ArgumentCount = 0, @Arguments = true, @ArrayDereference = false]
+                                    |  +- Arguments[@ArgumentCount = 0, @Size = 0]
+                                    +- PrimarySuffix[@ArgumentCount = -1, @Arguments = false, @ArrayDereference = false, @Image = "getName"]
+                                    +- PrimarySuffix[@ArgumentCount = 0, @Arguments = true, @ArrayDereference = false]
+                                       +- Arguments[@ArgumentCount = 0, @Size = 0]