[23] JEP 455 - Exhaustiveness of Switch eclipse-jdt#2869

clarify code gen for BOXING_CONVERSION_AND_WIDENING_REFERENCE_CONVERSION
implement NARROWING_AND_UNBOXING_CONVERSION
+ InstanceOfExpression.generateTypeCheck()
+ TypePattern.generateTestingConversion()
specific correct error message for incompatible case constant
+ fix bogus expectation in existing tests

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

@@ -2690,4 +2690,10 @@ public interface IProblem {
 	 */
 	int WrongCaseType =  PreviewRelated + 2100;
 
+	/**
+	 * @since 3.39
+	 * @noreference preview feature
+	 */
+	int IncompatibleCaseType =  PreviewRelated + 2101;
+
 }

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

@@ -302,7 +302,7 @@ public Constant resolveConstantExpression(BlockScope scope,
 			throw new AssertionError("Unexpected control flow"); //$NON-NLS-1$
 		} else if (expression instanceof NullLiteral) {
 			if (!caseType.isCompatibleWith(switchType, scope)) {
-				scope.problemReporter().typeMismatchError(TypeBinding.NULL, switchType, expression, null);
+				scope.problemReporter().caseConstantIncompatible(TypeBinding.NULL, switchType, expression);
 			}
 			switchStatement.switchBits |= SwitchStatement.NullCase;
 			return IntConstant.fromValue(-1);
@@ -311,7 +311,7 @@ public Constant resolveConstantExpression(BlockScope scope,
 		} else {
 			if (switchStatement.isNonTraditional) {
 				if (switchType.isBaseType() && !expression.isConstantValueOfTypeAssignableToType(caseType, switchType)) {
-					scope.problemReporter().typeMismatchError(caseType, switchType, expression, null);
+					scope.problemReporter().caseConstantIncompatible(caseType, switchType, expression);
 					return Constant.NotAConstant;
 				}
 			}
@@ -354,7 +354,7 @@ public Constant resolveConstantExpression(BlockScope scope,
 		// constantExpression.computeConversion(scope, caseType, switchExpressionType); - do not report boxing/unboxing conversion
 		return expression.constant;
 	}
-	scope.problemReporter().typeMismatchError(expression.resolvedType, switchType, expression, switchStatement.expression);
+	scope.problemReporter().caseConstantIncompatible(expression.resolvedType, switchType, expression);
 	return Constant.NotAConstant;
 }
 

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

@@ -240,7 +240,10 @@ private void generateTypeCheck(BlockScope scope, CodeStream codeStream, BranchLa
 			break;
 //			TODO:	case WIDENING_REFERENCE_AND_UNBOXING_COVERSION:
 //			TODO:	case WIDENING_REFERENCE_AND_UNBOXING_COVERSION_AND_WIDENING_PRIMITIVE_CONVERSION:
-//			TODO:	case NARROWING_AND_UNBOXING_CONVERSION:
+		case NARROWING_AND_UNBOXING_CONVERSION:
+			TypeBinding boxType = scope.environment().computeBoxingType(this.type.resolvedType);
+			codeStream.instance_of(this.type, boxType);
+			break;
 		case UNBOXING_CONVERSION:
 		case UNBOXING_AND_WIDENING_PRIMITIVE_CONVERSION:
 			codeStream.ifnull(internalFalseLabel);

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

@@ -58,7 +58,7 @@ public enum PrimitiveConversionRoute {
 	}
 
 	protected TypeBinding outerExpressionType; // the expression type of the enclosing instanceof, switch or outer record pattern
-	
+
 	record TestContextRecord(TypeBinding left, TypeBinding right, PrimitiveConversionRoute route) {}
 
 	public Pattern getEnclosingPattern() {
@@ -247,6 +247,10 @@ public static PrimitiveConversionRoute findPrimitiveConversionRoute(TypeBinding
 					return PrimitiveConversionRoute.WIDENING_REFERENCE_AND_UNBOXING_COVERSION;
 				if (BaseTypeBinding.isWidening(destinationType.id, exprPrimId))
 					return PrimitiveConversionRoute.WIDENING_REFERENCE_AND_UNBOXING_COVERSION_AND_WIDENING_PRIMITIVE_CONVERSION;
+			} else if (destinationIsBaseType) {
+				TypeBinding boxedDestinationType = scope.environment().computeBoxingType(destinationType);
+				if (boxedDestinationType.isCompatibleWith(expressionType))
+					return PrimitiveConversionRoute.NARROWING_AND_UNBOXING_CONVERSION;
 			}
 		}
 		return PrimitiveConversionRoute.NO_CONVERSION_ROUTE;

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

@@ -138,14 +138,9 @@ public void generateTestingConversion(BlockScope scope, CodeStream codeStream) {
 				codeStream.generateImplicitConversion(this.implicitConversion);
 				break;
 			case BOXING_CONVERSION:
+			case BOXING_CONVERSION_AND_WIDENING_REFERENCE_CONVERSION: // widening needs no conversion :)
 				codeStream.generateBoxingConversion(provided.id);
 				break;
-			case BOXING_CONVERSION_AND_WIDENING_REFERENCE_CONVERSION:
-				int providedId = provided.id;
-				codeStream.generateBoxingConversion(providedId);
-				TypeBinding unboxedType = scope.environment().computeBoxingType(TypeBinding.wellKnownBaseType(providedId));
-				this.computeConversion(scope, lhs, unboxedType);
-				break;
 			case WIDENING_REFERENCE_AND_UNBOXING_COVERSION:
 				codeStream.generateUnboxingConversion(expected.id);
 				break;
@@ -155,7 +150,11 @@ public void generateTestingConversion(BlockScope scope, CodeStream codeStream) {
 				this.computeConversion(scope, TypeBinding.wellKnownBaseType(rhsUnboxed), expected);
 				codeStream.generateImplicitConversion(this.implicitConversion);
 				break;
-//				TODO:	case NARROWING_AND_UNBOXING_CONVERSION:
+			case NARROWING_AND_UNBOXING_CONVERSION:
+				TypeBinding boxType = scope.environment().computeBoxingType(expected);
+				codeStream.checkcast(boxType);
+				codeStream.generateUnboxingConversion(expected.id);
+				break;
 			case UNBOXING_CONVERSION:
 				codeStream.generateUnboxingConversion(expected.id);
 				break;

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

@@ -1668,6 +1668,14 @@ public void caseExpressionWrongType(Expression expression, TypeBinding switchBin
 		expression.sourceStart,
 		expression.sourceEnd);
 }
+public void caseConstantIncompatible(TypeBinding resolvedType, TypeBinding switchType, Expression expression) {
+	this.handle(
+			IProblem.IncompatibleCaseType,
+			new String[] {String.valueOf(resolvedType.readableName()), String.valueOf(switchType.readableName())},
+			new String[] {String.valueOf(resolvedType.shortReadableName()), String.valueOf(switchType.shortReadableName())},
+			expression.sourceStart,
+			expression.sourceEnd);
+}
 public void classExtendFinalClass(SourceTypeBinding type, TypeReference superclass, TypeBinding superTypeBinding) {
 	String name = new String(type.sourceName());
 	String superTypeFullName = new String(superTypeBinding.readableName());

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

@@ -1195,6 +1195,7 @@
 
 # JEP 455 Primitive Types in Patterns, instanceof, and switch (Preview)
 2100 = Case constants in a switch on ''{0}'' must have type ''{1}''
+2101 = Case constant of type {0} is incompatible with switch selector type {1}
 
 ### ELABORATIONS
 ## Access restrictions

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

@@ -2090,7 +2090,7 @@ public void test068() {
 			"6. ERROR in X.java (at line 9)\n" +
 			"	case \'a\' :   // case statement\n" +
 			"	     ^^^\n" +
-			"Type mismatch: cannot convert from char to Integer\n" +
+			"Case constant of type char is incompatible with switch selector type Integer\n" +
 			"----------\n");
 }
 // https://bugs.eclipse.org/bugs/show_bug.cgi?id=480989

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

@@ -4956,7 +4956,7 @@ public void test165() {
 		"4. ERROR in X.java (at line 8)\n" +
 		"	case s:\n" +
 		"	     ^\n" +
-		"Type mismatch: cannot convert from short to Integer\n" +
+		"Case constant of type short is incompatible with switch selector type Integer\n" +
 		"----------\n" +
 		"5. WARNING in X.java (at line 12)\n" +
 		"	Integer i2 = 10 ;\n" +
@@ -4976,7 +4976,7 @@ public void test165() {
 		"8. ERROR in X.java (at line 17)\n" +
 		"	case b:\n" +
 		"	     ^\n" +
-		"Type mismatch: cannot convert from byte to Integer\n" +
+		"Case constant of type byte is incompatible with switch selector type Integer\n" +
 		"----------\n" +
 		"9. WARNING in X.java (at line 21)\n" +
 		"	Integer i3 = 10 ;\n" +
@@ -4996,7 +4996,7 @@ public void test165() {
 		"12. ERROR in X.java (at line 26)\n" +
 		"	case c:\n" +
 		"	     ^\n" +
-		"Type mismatch: cannot convert from char to Integer\n" +
+		"Case constant of type char is incompatible with switch selector type Integer\n" +
 		"----------\n");
 }
 
@@ -5245,7 +5245,7 @@ public void test169() {
 			"7. ERROR in X.java (at line 7)\n" +
 			"	case 1:\n" +
 			"	     ^\n" +
-			"Type mismatch: cannot convert from int to T\n" +
+			"Case constant of type int is incompatible with switch selector type T\n" +
 			"----------\n" +
 			"8. WARNING in X.java (at line 12)\n" +
 			"	t = 5;\n" +
@@ -5287,7 +5287,7 @@ public void test169() {
 			"6. ERROR in X.java (at line 7)\n" +
 			"	case 1:\n" +
 			"	     ^\n" +
-			"Type mismatch: cannot convert from int to T\n" +
+			"Case constant of type int is incompatible with switch selector type T\n" +
 			"----------\n" +
 			"7. WARNING in X.java (at line 12)\n" +
 			"	t = 5;\n" +

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

@@ -615,6 +615,7 @@ class ProblemAttributes {
 		expectedProblemAttributes.put("ImportInternalNameProvided", DEPRECATED);
 		expectedProblemAttributes.put("ImportNotFound", new ProblemAttributes(CategorizedProblem.CAT_IMPORT));
 		expectedProblemAttributes.put("ImportNotVisible", DEPRECATED);
+		expectedProblemAttributes.put("IncompatibleCaseType", new ProblemAttributes(CategorizedProblem.CAT_PREVIEW_RELATED));
 		expectedProblemAttributes.put("IncompatibleExceptionInInheritedMethodThrowsClause", new ProblemAttributes(CategorizedProblem.CAT_MEMBER));
 		expectedProblemAttributes.put("IncompatibleExceptionInThrowsClause", new ProblemAttributes(CategorizedProblem.CAT_MEMBER));
 		expectedProblemAttributes.put("IncompatibleExceptionInThrowsClauseForNonInheritedInterfaceMethod", new ProblemAttributes(CategorizedProblem.CAT_NAME_SHADOWING_CONFLICT));
@@ -1744,6 +1745,7 @@ class ProblemAttributes {
 		expectedProblemAttributes.put("ImportInternalNameProvided", SKIP);
 		expectedProblemAttributes.put("ImportNotFound", SKIP);
 		expectedProblemAttributes.put("ImportNotVisible", SKIP);
+		expectedProblemAttributes.put("IncompatibleCaseType", SKIP);
 		expectedProblemAttributes.put("IncompatibleExceptionInInheritedMethodThrowsClause", SKIP);
 		expectedProblemAttributes.put("IncompatibleExceptionInThrowsClause", SKIP);
 		expectedProblemAttributes.put("IncompatibleExceptionInThrowsClauseForNonInheritedInterfaceMethod", new ProblemAttributes(JavaCore.COMPILER_PB_INCOMPATIBLE_NON_INHERITED_INTERFACE_METHOD));

org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/PatternMatching16Test.java

@@ -198,17 +198,24 @@ public void test003() {
 	}
 	public void test003a() {
 		Map<String, String> options = getCompilerOptions(true);
-		runNegativeTest(
+		String[] testFiles =
 				new String[] {
 						"X3.java",
 						"@SuppressWarnings(\"preview\")\n" +
 						"public class X3 {\n" +
 						"  public void foo(Number num) {\n" +
 						"		if (num instanceof int) {\n" +
+						"			System.out.print(\"int\");\n" +
 						"		}\n " +
 						"	}\n" +
+						"	public static void main(String... args) {\n" +
+						"		new X3().foo(3);" +
+						"	}\n" +
 						"}\n",
-				},
+				};
+		if (this.complianceLevel < ClassFileConstants.JDK23) {
+			runNegativeTest(
+				testFiles,
 				"----------\n" +
 				"1. ERROR in X3.java (at line 4)\n" +
 				"	if (num instanceof int) {\n" +
@@ -219,6 +226,9 @@ public void test003a() {
 				null,
 				true,
 				options);
+		} else {
+			runConformTest(testFiles, "int", options, new String[] {"--enable-preview"}, JavacTestOptions.DEFAULT);
+		}
 	}
 	public void test004() {
 		Map<String, String> options = getCompilerOptions(true);

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

@@ -1165,6 +1165,117 @@ public static PRIM switchPRIM(BOX in) {
 				"false|false|49|-1|1|-|49|-1|49|-1|49|-1|49.0|-1.0|49.0|-1.0|");
 	}
 
+	public void testPrimitivePatternInSwitch_narrowConst_NOK() {
+		StringBuilder methods = new StringBuilder();
+		StringBuilder calls = new StringBuilder();
+		String methodTmpl =
+				"""
+					public static PRIM switchPRIM(Object in) {
+						return switch (in) {
+							case MAX -> NEGVAL;
+							default -> MAX;
+						};
+					}
+				""";
+		String callTmpl =
+				"""
+						BOX vBOX = VAL;
+						System.out.print(X.switchPRIM(vBOX));
+						System.out.print('|');
+						vBOX = MAX;
+						System.out.print(X.switchPRIM(vBOX));
+						System.out.print('|');
+				""";
+		// for all primitive types:
+		for (int i = 0; i < PRIMITIVES.length; i++) {
+			methods.append(fillIn(methodTmpl, i));
+			calls.append(fillIn(callTmpl, i));
+		}
+		StringBuilder classX = new StringBuilder("public class X {\n");
+		classX.append(methods.toString());
+		classX.append("public static void main(String[] args) {\n");
+		classX.append(calls);
+		classX.append("}}\n");
+		runNegativeTest(new String[] { "X.java", classX.toString() },
+				"""
+				----------
+				1. ERROR in X.java (at line 4)
+					case true -> false;
+					     ^^^^
+				Case constant of type boolean is incompatible with switch selector type Object
+				----------
+				2. ERROR in X.java (at line 10)
+					case Byte.MAX_VALUE -> -1;
+					     ^^^^^^^^^^^^^^
+				Case constant of type byte is incompatible with switch selector type Object
+				----------
+				3. ERROR in X.java (at line 16)
+					case 'z' -> '-';
+					     ^^^
+				Case constant of type char is incompatible with switch selector type Object
+				----------
+				4. ERROR in X.java (at line 22)
+					case Short.MAX_VALUE -> -1;
+					     ^^^^^^^^^^^^^^^
+				Case constant of type short is incompatible with switch selector type Object
+				----------
+				5. ERROR in X.java (at line 28)
+					case Integer.MAX_VALUE -> -1;
+					     ^^^^^^^^^^^^^^^^^
+				Case constant of type int is incompatible with switch selector type Object
+				----------
+				6. ERROR in X.java (at line 34)
+					case Long.MAX_VALUE -> -1L;
+					     ^^^^^^^^^^^^^^
+				Case constant of type long is incompatible with switch selector type Object
+				----------
+				7. ERROR in X.java (at line 40)
+					case Float.MAX_VALUE -> -1.0f;
+					     ^^^^^^^^^^^^^^^
+				Case constant of type float is incompatible with switch selector type Object
+				----------
+				8. ERROR in X.java (at line 46)
+					case Double.MAX_VALUE -> -1.0d;
+					     ^^^^^^^^^^^^^^^^
+				Case constant of type double is incompatible with switch selector type Object
+				----------
+				""");
+	}
+
+	public void testPrimitivePatternInSwitch_narrowUnbox() {
+		StringBuilder methods = new StringBuilder();
+		StringBuilder calls = new StringBuilder();
+		String methodTmpl =
+				"""
+					public static PRIM switchPRIM(Object in) {
+						return switch (in) {
+							case PRIM v -> v;
+							default -> NEGVAL;
+						};
+					}
+				""";
+		String callTmpl =
+				"""
+						BOX vBOX = VAL;
+						System.out.print(X.switchPRIM(vBOX));
+						System.out.print('|');
+						System.out.print(X.switchPRIM(new Object()));
+						System.out.print('|');
+				""";
+		// for all primitive types:
+		for (int i = 0; i < PRIMITIVES.length; i++) {
+			methods.append(fillIn(methodTmpl, i));
+			calls.append(fillIn(callTmpl, i));
+		}
+		StringBuilder classX = new StringBuilder("public class X {\n");
+		classX.append(methods.toString());
+		classX.append("public static void main(String[] args) {\n");
+		classX.append(calls);
+		classX.append("}}\n");
+		runConformTest(new String[] { "X.java", classX.toString() },
+				"true|false|49|-1|1|-|49|-1|49|-1|49|-1|49.0|-1.0|49.0|-1.0|");
+	}
+
 	private void testPrimitivePatternInSwitch_from_unboxAndNarrow_NOK(String from, int idx, String expectedError) {
 		assert from.equals(BOXES[idx]) : "mismatching from vs idx";
 		StringBuilder methods = new StringBuilder();

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

@@ -204,7 +204,7 @@ public void testBug544073_004() {
 			"1. ERROR in X.java (at line 12)\n" +
 			"	case \"hello\" -> throw new java.io.IOException(\"hello\");\n" +
 			"	     ^^^^^^^\n" +
-			"Type mismatch: cannot convert from String to int\n" +
+			"Case constant of type String is incompatible with switch selector type int\n" +
 			"----------\n");
 	}
 	public void testBug544073_005() {
@@ -273,7 +273,7 @@ public void testBug544073_006() {
 			"2. ERROR in X.java (at line 13)\n" +
 			"	case \"hello\" -> throw new IOException(\"hello\");\n" +
 			"	     ^^^^^^^\n" +
-			"Type mismatch: cannot convert from String to int\n" +
+			"Case constant of type String is incompatible with switch selector type int\n" +
 			"----------\n");
 	}
 	/*
@@ -929,7 +929,7 @@ public void testBug544073_027() {
 				"1. ERROR in X.java (at line 9)\n" +
 				"	case \"2\": \n" +
 				"	     ^^^\n" +
-				"Type mismatch: cannot convert from String to int\n" +
+				"Case constant of type String is incompatible with switch selector type int\n" +
 				"----------\n";
 		this.runNegativeTest(
 				testFiles,
@@ -7677,7 +7677,7 @@ public static void main(String[] args) {
 						+ "1. ERROR in X.java (at line 8)\n"
 						+ "	case 1.0 -> System.out.println(d);\n"
 						+ "	     ^^^\n"
-						+ "Type mismatch: cannot convert from double to void\n"
+						+ "Case constant of type double is incompatible with switch selector type void\n"
 						+ "----------\n");
 	}
 	// https://github.com/eclipse-jdt/eclipse.jdt.core/issues/2382
@@ -7801,7 +7801,7 @@ public static void main(String[] args) {
 						"2. ERROR in X.java (at line 8)\n" +
 						"	case null -> System.out.println(d);\n" +
 						"	     ^^^^\n" +
-						"Type mismatch: cannot convert from null to void\n" +
+						"Case constant of type null is incompatible with switch selector type void\n" +
 						"----------\n");
 	}
 	// https://github.com/eclipse-jdt/eclipse.jdt.core/issues/2387