Fix error messages related to _

Signed-off-by: David Thompson <[email protected]>

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/core/compiler/IProblem.java

@@ -2564,4 +2564,10 @@ public interface IProblem {
 	 * @since 3.35
 	 */
 	int SyntheticAccessorNotEnclosingMethod = MethodRelated + 1990;
+
+	/**
+	 * @since 3.36
+	 * @noreference preview feature
+	 */
+	int FieldNameCannotBeUnderscore = PreviewRelated + 2000;
 }

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/AbstractVariableDeclaration.java

@@ -16,6 +16,7 @@
  *******************************************************************************/
 package org.eclipse.jdt.internal.compiler.ast;
 
+import org.eclipse.jdt.internal.compiler.classfmt.ClassFileConstants;
 import org.eclipse.jdt.internal.compiler.flow.FlowContext;
 import org.eclipse.jdt.internal.compiler.flow.FlowInfo;
 import org.eclipse.jdt.internal.compiler.lookup.BlockScope;
@@ -144,4 +145,15 @@ public void setDepth(int depth) {
 	public void setFieldIndex(int depth) {
 		// do nothing by default
 	}
+
+	/**
+	 * Returns true if this variable is an unnamed variable (_) and false otherwise.
+	 *
+	 * @param scope used to determine source level
+	 */
+	public boolean isUnnamed(BlockScope scope) {
+		return this.name.length == 1 && this.name[0] == '_'
+				&& scope.compilerOptions().sourceLevel >= ClassFileConstants.JDK21
+				&& scope.compilerOptions().enablePreviewFeatures;
+	}
 }

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/Argument.java

@@ -123,12 +123,14 @@ public TypeBinding bind(MethodScope scope, TypeBinding typeBinding, boolean used
 		if (existingVariable != null && existingVariable.isValidBinding()){
 			final boolean localExists = existingVariable instanceof LocalVariableBinding;
 			if (localExists && this.hiddenVariableDepth == 0) {
-				if ((this.bits & ASTNode.ShadowsOuterLocal) != 0 && scope.isLambdaSubscope()) {
-					scope.problemReporter().lambdaRedeclaresArgument(this);
-				} else if (scope.referenceContext instanceof CompactConstructorDeclaration) {
-					// skip error reporting - hidden params - already reported in record components
-				} else {
-					scope.problemReporter().redefineArgument(this);
+				if (!this.isUnnamed(scope)) {
+					if ((this.bits & ASTNode.ShadowsOuterLocal) != 0 && scope.isLambdaSubscope()) {
+						scope.problemReporter().lambdaRedeclaresArgument(this);
+					} else if (scope.referenceContext instanceof CompactConstructorDeclaration) {
+						// skip error reporting - hidden params - already reported in record components
+					} else {
+						scope.problemReporter().redefineArgument(this);
+					}
 				}
 			} else {
 				boolean isSpecialArgument = false;
@@ -234,7 +236,7 @@ public TypeBinding resolveForCatch(BlockScope scope) {
 			}
 		}
 		Binding existingVariable = scope.getBinding(this.name, Binding.VARIABLE, this, false /*do not resolve hidden field*/);
-		if (existingVariable != null && existingVariable.isValidBinding()){
+		if (existingVariable != null && existingVariable.isValidBinding() && !isUnnamed(scope)) {
 			if (existingVariable instanceof LocalVariableBinding && this.hiddenVariableDepth == 0) {
 				scope.problemReporter().redefineArgument(this);
 			} else {

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/FieldDeclaration.java

@@ -70,6 +70,9 @@ public FieldDeclaration(	char[] name, int sourceStart, int sourceEnd) {
 }
 
 public FlowInfo analyseCode(MethodScope initializationScope, FlowContext flowContext, FlowInfo flowInfo) {
+	if (this.isUnnamed(initializationScope)) {
+		initializationScope.problemReporter().fieldNameCannotBeUnderscore(this);
+	}
 	if (this.binding != null && !this.binding.isUsed() && this.binding.isOrEnclosedByPrivateType()) {
 		if (!initializationScope.referenceCompilationUnit().compilationResult.hasSyntaxError) {
 			if (!this.isARecordComponent) // record component used by implicit methods

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/LocalDeclaration.java

@@ -299,7 +299,7 @@ public void resolve(BlockScope scope, boolean isPatternVariable) {
 		}
 
 		Binding existingVariable = scope.getBinding(this.name, Binding.VARIABLE, this, false /*do not resolve hidden field*/);
-		if (existingVariable != null && existingVariable.isValidBinding()){
+		if (existingVariable != null && existingVariable.isValidBinding() && !this.isUnnamed(scope)) {
 			boolean localExists = existingVariable instanceof LocalVariableBinding;
 			if (localExists && (this.bits & ASTNode.ShadowsOuterLocal) != 0 && scope.isLambdaSubscope() && this.hiddenVariableDepth == 0) {
 				scope.problemReporter().lambdaRedeclaresLocal(this);

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/TypePattern.java

@@ -52,7 +52,7 @@ public void collectPatternVariablesToScope(LocalVariableBinding[] variables, Blo
 		if (this.resolvedType == null) {
 			this.resolveType(scope);
 		}
-		if (this.local != null && this.local.binding != null) {
+		if (this.local != null && this.local.binding != null && !this.local.isUnnamed(scope)) {
 			LocalVariableBinding binding = this.local.binding;
 			if (variables != null) {
 				for (LocalVariableBinding variable : variables) {

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/impl/JavaFeature.java

@@ -66,7 +66,7 @@ public enum JavaFeature {
 			new char[][] {},
 			false),
 	UNNAMMED_PATTERNS_AND_VARS(ClassFileConstants.JDK21,
-			Messages.bind(Messages.unnammed_patterns_and_vars),
+			Messages.bind(Messages.unnamed_patterns_and_vars),
 			new char[][] {},
 			true),
 	UNNAMMED_CLASSES_AND_INSTANCE_MAIN_METHODS(ClassFileConstants.JDK21,

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/lookup/BlockScope.java

@@ -289,7 +289,8 @@ void computeLocalVariablePositions(int ilocal, int initOffset, CodeStream codeSt
 			// do not report fake used variable
 			if (local.useFlag == LocalVariableBinding.UNUSED
 				&& (local.declaration != null) // unused (and non secret) local
-				&& ((local.declaration.bits & ASTNode.IsLocalDeclarationReachable) != 0)) { // declaration is reachable
+				&& ((local.declaration.bits & ASTNode.IsLocalDeclarationReachable) != 0) // declaration is reachable
+				&& !local.declaration.isUnnamed(local.declaringScope)) {
 
 				if (local.isCatchParameter()) {
 					problemReporter().unusedExceptionParameter(local.declaration); // report unused catch arguments

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/messages.properties

@@ -74,5 +74,5 @@ records = Records
 sealed_types = Sealed Types
 pattern_matching_switch = Pattern Matching in Switch
 record_patterns = Record Pattern
-unnammed_patterns_and_vars = Unnammed Patterns and Variables
+unnamed_patterns_and_vars = Unnamed Patterns and Variables
 unnamed_classes_and_instance_main_methods = Unnamed Classes and Instance Main Methods

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/parser/Parser.java

@@ -986,6 +986,7 @@ protected int actFromTokenOrSynthetic(int previousAct) {
 protected boolean parsingJava15Plus;
 protected boolean parsingJava17Plus;
 protected boolean parsingJava18Plus;
+protected boolean parsingJava21Plus;
 protected boolean previewEnabled;
 protected boolean parsingJava11Plus;
 protected int unstackedAct = ERROR_ACTION;
@@ -1017,6 +1018,7 @@ public Parser(ProblemReporter problemReporter, boolean optimizeStringLiterals) {
 	this.parsingJava15Plus = this.options.sourceLevel >= ClassFileConstants.JDK15;
 	this.parsingJava17Plus = this.options.sourceLevel >= ClassFileConstants.JDK17;
 	this.parsingJava18Plus = this.options.sourceLevel >= ClassFileConstants.JDK18;
+	this.parsingJava21Plus = this.options.sourceLevel >= ClassFileConstants.JDK21;
 	this.previewEnabled = this.options.sourceLevel == ClassFileConstants.getLatestJDKLevel() && this.options.enablePreviewFeatures;
 	this.astLengthStack = new int[50];
 	this.expressionLengthStack = new int[30];
@@ -7485,9 +7487,9 @@ protected void consumeRule(int act) {
 		    consumePatternListopt();
 			break;
 
-	    case 369 : if (DEBUG) { System.out.println("PushLeftBrace ::="); }  //$NON-NLS-1$
-			    consumePushLeftBrace();
-				break;
+    case 368 : if (DEBUG) { System.out.println("ComponentPatternList ::= ComponentPatternList COMMA..."); }  //$NON-NLS-1$
+		    consumePatternList();
+			break;
 
     case 370 : if (DEBUG) { System.out.println("TypePattern ::= Modifiersopt Type UNDERSCORE"); }  //$NON-NLS-1$
 		    consumeTypePattern();
@@ -9115,8 +9117,13 @@ protected void consumeLambdaHeader() {
 		if (argument.isReceiver()) {
 			problemReporter().illegalThis(argument);
 		}
-		if (argument.name.length == 1 && argument.name[0] == '_')
-			problemReporter().illegalUseOfUnderscoreAsAnIdentifier(argument.sourceStart, argument.sourceEnd, true); // true == lambdaParameter
+		if (this.parsingJava8Plus && !(this.parsingJava21Plus && this.previewEnabled) && argument.name.length == 1 && argument.name[0] == '_') {
+			if (this.parsingJava21Plus) {
+				problemReporter().validateJavaFeatureSupport(JavaFeature.UNNAMMED_PATTERNS_AND_VARS, argument.sourceStart, argument.sourceEnd);
+			} else {
+				problemReporter().illegalUseOfUnderscoreAsAnIdentifier(argument.sourceStart, argument.sourceEnd, true); // true == lambdaParameter
+			}
+		}
 	}
 	LambdaExpression lexp = (LambdaExpression) this.astStack[this.astPtr];
 	lexp.setArguments(arguments);
@@ -13944,8 +13951,12 @@ protected void pushIdentifier(char [] identifier, long position) {
 			stackLength);
 	}
 	this.identifierLengthStack[this.identifierLengthPtr] = 1;
-	if (this.parsingJava8Plus && identifier.length == 1 && identifier[0] == '_' && !this.processingLambdaParameterList) {
-		problemReporter().illegalUseOfUnderscoreAsAnIdentifier((int) (position >>> 32), (int) position, this.parsingJava9Plus);
+	if (this.parsingJava8Plus && !(this.parsingJava21Plus && this.previewEnabled) && identifier.length == 1 && identifier[0] == '_' && !this.processingLambdaParameterList) {
+		if (this.parsingJava21Plus) {
+			problemReporter().validateJavaFeatureSupport(JavaFeature.UNNAMMED_PATTERNS_AND_VARS, (int) (position >>> 32), (int) position);
+		} else {
+			problemReporter().illegalUseOfUnderscoreAsAnIdentifier((int) (position >>> 32), (int) position, this.parsingJava9Plus);
+		}
 	}
 }
 protected void pushIdentifier() {

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/problem/ProblemReporter.java

@@ -12466,6 +12466,14 @@ public void falseLiteralInGuard(Expression exp) {
 			exp.sourceStart,
 			exp.sourceEnd);
 }
+public void fieldNameCannotBeUnderscore(FieldDeclaration fieldDeclaration) {
+	this.handle(
+			IProblem.FieldNameCannotBeUnderscore,
+			NoArgument,
+			NoArgument,
+			fieldDeclaration.sourceStart,
+			fieldDeclaration.sourceEnd);
+}
 public boolean scheduleProblemForContext(Runnable problemComputation) {
 	if (this.referenceContext != null) {
 		CompilationResult result = this.referenceContext.compilationResult();

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/problem/messages.properties

@@ -1158,6 +1158,9 @@
 
 1990 = Access to {1}({2}) from the type {0} is emulated by a synthetic accessor method
 
+# Unnamed variables and patterns (preview in Java 21, set for release in Java 22)
+2000 = Field name cannot be '_'
+
 ### ELABORATIONS
 ## Access restrictions
 78592 = The type ''{1}'' is not API (restriction on classpath entry ''{0}'')

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/util/Messages.java

@@ -124,7 +124,7 @@ private Messages() {
 	public static String sealed_types;
 	public static String pattern_matching_switch;
 	public static String record_patterns;
-	public static String unnammed_patterns_and_vars;
+	public static String unnamed_patterns_and_vars;
 	public static String unnamed_classes_and_instance_main_methods;
 
 	static {

org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/CompilerInvocationTests.java

@@ -1328,6 +1328,7 @@ class ProblemAttributes {
 	    expectedProblemAttributes.put("ClassExtendFinalRecord", new ProblemAttributes(CategorizedProblem.CAT_TYPE));
 	    expectedProblemAttributes.put("RecordErasureIncompatibilityInCanonicalConstructor", new ProblemAttributes(CategorizedProblem.CAT_TYPE));
 	    expectedProblemAttributes.put("JavadocInvalidModule", new ProblemAttributes(CategorizedProblem.CAT_INTERNAL));
+	    expectedProblemAttributes.put("FieldNameCannotBeUnderscore", new ProblemAttributes(CategorizedProblem.CAT_PREVIEW_RELATED));
 	    StringBuffer failures = new StringBuffer();
 		StringBuffer correctResult = new StringBuffer(70000);
 		Field[] fields = (iProblemClass = IProblem.class).getFields();
@@ -2429,6 +2430,7 @@ class ProblemAttributes {
 	    expectedProblemAttributes.put("ClassExtendFinalRecord", SKIP);
 	    expectedProblemAttributes.put("RecordErasureIncompatibilityInCanonicalConstructor", SKIP);
 	    expectedProblemAttributes.put("JavadocInvalidModule", SKIP);
+	    expectedProblemAttributes.put("FieldNameCannotBeUnderscore", SKIP);
 
 	    Map constantNamesIndex = new HashMap();
 		Field[] fields = JavaCore.class.getFields();

org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/NegativeLambdaExpressionsTest.java

@@ -7371,6 +7371,10 @@ public void testIntersectionCast() {
 public void testUnderScoreParameter() {
 		String level = this.complianceLevel >= ClassFileConstants.JDK9 ? "ERROR" : "WARNING";
 		String errorMessage = this.complianceLevel >= ClassFileConstants.JDK9 ? "\'_\' is a keyword from source level 9 onwards, cannot be used as identifier\n" : "\'_\' should not be used as an identifier, since it is a reserved keyword from source level 1.8 on\n";
+		if (this.complianceLevel >= ClassFileConstants.JDK21) {
+			errorMessage = "Unnamed Patterns and Variables is a preview feature and disabled by default. Use --enable-preview to enable\n";
+		}
+		String otherErrorMessage = this.complianceLevel >= ClassFileConstants.JDK21 ? errorMessage : "\'_\' is a keyword from source level 9 onwards, cannot be used as identifier\n";
 		this.runNegativeTest(
 			new String[] {
 					"X.java",
@@ -7389,7 +7393,7 @@ public void testUnderScoreParameter() {
 			"1. ERROR in X.java (at line 6)\n" +
 			"	F f = (int _) -> {\n" +
 			"	           ^\n" +
-			"\'_\' is a keyword from source level 9 onwards, cannot be used as identifier\n" +
+			otherErrorMessage +
 			"----------\n" +
 			"2. "+ level +" in X.java (at line 8)\n" +
 			"	F f2 = _ -> {};\n" +
@@ -7399,7 +7403,7 @@ public void testUnderScoreParameter() {
 			"3. ERROR in X.java (at line 8)\n" +
 			"	F f2 = _ -> {};\n" +
 			"	       ^\n" +
-			"\'_\' is a keyword from source level 9 onwards, cannot be used as identifier\n" +
+			otherErrorMessage +
 			"----------\n"
 		);
 }