Add basic tests for Java 20, deactivate Java 19 preview tests

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

bcel-builder/src/main/java/org/aspectj/apache/bcel/Constants.java

@@ -102,8 +102,10 @@ public interface Constants {
 	short MINOR_18 = 0;
 	short MAJOR_19 = 63;
 	short MINOR_19 = 0;
-//	short MAJOR_20 = 64;
-//	short MINOR_20 = 0;
+	short MAJOR_20 = 64;
+	short MINOR_20 = 0;
+//	short MAJOR_21 = 65;
+//	short MINOR_21 = 0;
 
 	int PREVIEW_MINOR_VERSION = 65535;
 

taskdefs/src/main/java/org/aspectj/tools/ant/taskdefs/AjcTask.java

@@ -252,15 +252,15 @@ public class AjcTask extends MatchingTask {
 
 	static final String[] TARGET_INPUTS = new String[] {
 		"1.1", "1.2", "1.3", "1.4", "1.5", "1.6", "1.7", "1.8", "1.9", "9",
-		"10", "11", "12", "13", "14", "15", "16", "17", "18", "19"
+		"10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20"
 	};
 	static final String[] SOURCE_INPUTS = new String[] {
 		"1.3", "1.4", "1.5", "1.6", "1.7", "1.8", "1.9", "9",
-		"10", "11", "12", "13", "14", "15", "16", "17", "18", "19"
+		"10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20"
 	};
 	static final String[] COMPLIANCE_INPUTS = new String[] {
 		"-1.3", "-1.4", "-1.5", "-1.6", "-1.7", "-1.8", "-1.9", "-9",
-		"-10", "-11", "-12", "-13", "-14", "-15", "-16", "-17", "-18", "-19"
+		"-10", "-11", "-12", "-13", "-14", "-15", "-16", "-17", "-18", "-19", "-20"
 	};
 
 	private static final ICommandEditor COMMAND_EDITOR;

testing/src/test/java/org/aspectj/testing/XMLBasedAjcTestCaseForJava19Only.java

@@ -20,14 +20,13 @@ public abstract class XMLBasedAjcTestCaseForJava19Only extends XMLBasedAjcTestCa
 	@Override
 	public void setUp() throws Exception {
 		// Activate this block after upgrading to JDT Core Java 20
-		/*
 		throw new IllegalStateException(
 			"These tests need a Java 19 level AspectJ compiler " +
 				"(e.g. because they use version-specific preview features). " +
 				"This compiler does not support preview features of a previous version anymore."
 		);
-		*/
 		// Activate this block before upgrading to JDT Core Java 20
+		/*
 		if (!LangUtil.is19VMOrGreater() || LangUtil.is20VMOrGreater()) {
 			throw new IllegalStateException(
 				"These tests should be run on Java 19 only " +
@@ -35,6 +34,7 @@ public abstract class XMLBasedAjcTestCaseForJava19Only extends XMLBasedAjcTestCa
 			);
 		}
 		super.setUp();
+		*/
 	}
 
 }

testing/src/test/java/org/aspectj/testing/XMLBasedAjcTestCaseForJava20Only.java

@@ -0,0 +1,40 @@
+/* *******************************************************************
+ * Copyright (c) 2022 Contributors
+ * All rights reserved.
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Public License v 2.0
+ * which accompanies this distribution and is available at
+ * https://www.eclipse.org/org/documents/epl-2.0/EPL-2.0.txt
+ * ******************************************************************/
+package org.aspectj.testing;
+
+import org.aspectj.util.LangUtil;
+
+/**
+ * Makes sure tests are running on the right level of JDK.
+ *
+ * @author Alexander Kriegisch
+ */
+public abstract class XMLBasedAjcTestCaseForJava20Only extends XMLBasedAjcTestCase {
+
+	@Override
+	public void setUp() throws Exception {
+		// Activate this block after upgrading to JDT Core Java 21
+		/*
+		throw new IllegalStateException(
+			"These tests need a Java 20 level AspectJ compiler " +
+				"(e.g. because they use version-specific preview features). " +
+				"This compiler does not support preview features of a previous version anymore."
+		);
+		*/
+		// Activate this block before upgrading to JDT Core Java 21
+		if (!LangUtil.is20VMOrGreater() || LangUtil.is21VMOrGreater()) {
+			throw new IllegalStateException(
+				"These tests should be run on Java 20 only " +
+				"(e.g. because they use version-specific preview features)"
+			);
+		}
+		super.setUp();
+	}
+
+}

testing/src/test/java/org/aspectj/testing/XMLBasedAjcTestCaseForJava20OrLater.java

@@ -0,0 +1,27 @@
+/* *******************************************************************
+ * Copyright (c) 2022 Contributors
+ * All rights reserved.
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Public License v 2.0
+ * which accompanies this distribution and is available at
+ * https://www.eclipse.org/org/documents/epl-2.0/EPL-2.0.txt
+ * ******************************************************************/
+package org.aspectj.testing;
+
+import org.aspectj.util.LangUtil;
+
+/**
+ * Makes sure tests are running on the right level of JDK.
+ *
+ * @author Alexander Kriegisch
+ */
+public abstract class XMLBasedAjcTestCaseForJava20OrLater extends XMLBasedAjcTestCase {
+
+	@Override
+	public void setUp() throws Exception {
+		if (!LangUtil.is20VMOrGreater())
+			throw new IllegalStateException("These tests should be run on Java 20 or later");
+		super.setUp();
+	}
+
+}

tests/features1919/java19/RecordPatternsPreview1Error.java

@@ -1,5 +1,5 @@
 /**
- * This was not working as expected in ECJ after the initial Java 19 merge the JDT Core main line,
+ * This was not working as expected in ECJ after the initial Java 19 merge from the JDT Core main line,
  * see https://github.com/eclipse-jdt/eclipse.jdt.core/issues/450.
  */
 public class RecordPatternsPreview1Error {

tests/features1919/java19/RecordPatternsPreview1ExhaustivenessAspect.aj

@@ -5,17 +5,15 @@ public aspect RecordPatternsPreview1ExhaustivenessAspect {
     doSomething(p2);
   }
 
-  public static void doSomething(Pair pair) {
+  public static void doSomething(Pair<I> pair) {
     System.out.println(pair.toString().replaceAll("@[0-9a-f]+", "@000"));
   }
 
-  before(Pair pair) : execution(* doSomething(Pair)) && args(pair) {
+  before(Pair<I> pair) : execution(* doSomething(Pair)) && args(pair) {
     switch (pair) {
       case Pair<I>(I i, C c) -> System.out.println("x");
       case Pair<I>(I i, D d) -> System.out.println("y");
-      // TODO: Remove redundant default clause when https://github.com/eclipse-jdt/eclipse.jdt.core/issues/455
-      // has been fixed. But even with the default clause, it generates wrong byte code and throws runtime error:
-      // NoSuchMethodError: 'I Pair.x()'
+      // TODO: Remove redundant default clause when https://github.com/eclipse-jdt/eclipse.jdt.core/issues/455 has been fixed
       default -> System.out.println("z");
     }
 
@@ -23,9 +21,7 @@ public aspect RecordPatternsPreview1ExhaustivenessAspect {
       case Pair<I>(C c, I i) -> System.out.println("a");
       case Pair<I>(D d, C c) -> System.out.println("b");
       case Pair<I>(D d1, D d2) -> System.out.println("c");
-      // TODO: remove redundant default clause when https://github.com/eclipse-jdt/eclipse.jdt.core/issues/455
-      // has been fixed. But even with the default clause, it generates wrong byte code and throws runtime error:
-      // NoSuchMethodError: 'I Pair.x()'
+      // TODO: remove redundant default clause when https://github.com/eclipse-jdt/eclipse.jdt.core/issues/455 has been fixed
       default -> System.out.println("d");
     }
   }

tests/features1919/java19/RecordPatternsPreview1ExhaustivenessOK1.java

@@ -10,12 +10,16 @@ public class RecordPatternsPreview1ExhaustivenessOK1 {
     switch (p2) {
       case Pair<I>(I i, C c) -> System.out.println("x");
       case Pair<I>(I i, D d) -> System.out.println("y");
+      // TODO: Remove redundant default clause when https://github.com/eclipse-jdt/eclipse.jdt.core/issues/455 has been fixed
+      default -> System.out.println("z");
     }
 
     switch (p2) {
       case Pair<I>(C c, I i) -> System.out.println("a");
       case Pair<I>(D d, C c) -> System.out.println("b");
       case Pair<I>(D d1, D d2) -> System.out.println("c");
+      // TODO: remove redundant default clause when https://github.com/eclipse-jdt/eclipse.jdt.core/issues/455 has been fixed
+      default -> System.out.println("d");
     }
   }
 }

tests/features1920/java20/SwitchPatternPreview4Error.java

@@ -0,0 +1,37 @@
+/**
+ * This used to work up to preview 3 (Java 19), but no longer in preview 4 (Java 20).
+ * Now, the default case seems to need to be the last one in the list.
+ *
+ * Javac says 4x: "this case label is dominated by a preceding case label"
+ *
+ * ECJ/AJC says 11x: "This case label is dominated by one of the preceding case label" (yes, "label" singular)
+ * See https://github.com/eclipse-jdt/eclipse.jdt.core/issues/919.
+ */
+public class SwitchPatternPreview4Error {
+  static void defaultCanAppearBeforePattern(Integer i) {
+    switch (i) {
+      case null -> System.out.println("value unavailable: " + i);
+      case -1, 1 -> System.out.println("absolute value 1: " + i);
+      default -> System.out.println("other integer: " + i);
+      case Integer value when value > 0 -> System.out.println("positive integer: " + i);
+    }
+  }
+
+  static void defaultCanAppearBeforeNull(Integer i) {
+    switch (i) {
+      case -1, 1 -> System.out.println("absolute value 1: " + i);
+      default -> System.out.println("other integer: " + i);
+      case null -> System.out.println("value unavailable: " + i);
+      case Integer value when value > 0 -> System.out.println("positive integer: " + i);
+    }
+  }
+
+  static void defaultCanAppearBeforeConstantLabel(Integer i) {
+    switch (i) {
+      case null -> System.out.println("value unavailable: " + i);
+      default -> System.out.println("other integer: " + i);
+      case -1, 1 -> System.out.println("absolute value 1: " + i);
+      case Integer value when value > 0 -> System.out.println("positive integer: " + i);
+    }
+  }
+}

tests/features1920/java20/SwitchPatternPreview4OK.java

@@ -0,0 +1,147 @@
+import java.util.List;
+import java.util.Locale;
+
+/**
+ * Inspired by examples in https://openjdk.org/jeps/427
+ */
+public class SwitchPatternPreview4OK {
+  public static void main(String[] args) {
+
+    System.out.println(formatterPatternSwitch(null));
+    System.out.println(formatterPatternSwitch(123));
+    System.out.println(formatterPatternSwitch(999L));
+    System.out.println(formatterPatternSwitch(12.34));
+    System.out.println(formatterPatternSwitch("foo"));
+    System.out.println(formatterPatternSwitch(List.of(123, "foo", 999L, 12.34)));
+
+    System.out.println(testCircle(new Rectangle()));
+    System.out.println(testCircle(new Circle(5)));
+    System.out.println(testCircle(new Circle(6)));
+
+    System.out.println(testSealedCoverage(new A()));
+    System.out.println(testSealedCoverage(new B()));
+    System.out.println(testSealedCoverage(new C(5)));
+
+//    constantLabelMustAppearBeforePattern(-1);
+//    constantLabelMustAppearBeforePattern(0);
+//    constantLabelMustAppearBeforePattern(42);
+//    constantLabelMustAppearBeforePattern(-99);
+//    constantLabelMustAppearBeforePattern(Integer.valueOf(123));
+//    constantLabelMustAppearBeforePattern(null);
+
+    constantLabelMustAppearBeforePatternInteger(-1);
+    constantLabelMustAppearBeforePatternInteger(0);
+    constantLabelMustAppearBeforePatternInteger(42);
+    constantLabelMustAppearBeforePatternInteger(-99);
+    constantLabelMustAppearBeforePatternInteger(Integer.valueOf(123));
+    constantLabelMustAppearBeforePatternInteger(null);
+
+//    System.out.println(testGenericSealedExhaustive(new E<Integer>()));
+  }
+
+  static String formatterPatternSwitch(Object o) {
+    return switch (o) {
+      case null      -> "null";
+      case Integer i -> String.format("int %d", i);
+      case Long l    -> String.format("long %d", l);
+      case Double d  -> String.format(Locale.ENGLISH, "double %f", d);
+      case String s  -> String.format("String %s", s);
+      default        -> o.toString();
+    };
+  }
+
+  static class Shape {}
+  static class Rectangle extends Shape {}
+  static class Circle extends Shape {
+    private final double radius;
+    public Circle(double radius) { this.radius = radius; }
+    double calculateArea() { return Math.PI * radius * radius; }
+  }
+
+  static String testCircle(Shape s) {
+    return switch (s) {
+      case Circle c when (c.calculateArea() > 100) -> "Large circle";
+      case Circle c -> "Small circle";
+      default -> "Non-circle";
+    };
+  }
+
+  sealed interface S permits A, B, C {}
+  final static class A implements S {}
+  final static class B implements S {}
+  static record C(int i) implements S {}  // Implicitly final
+
+  static String testSealedCoverage(S s) {
+    return switch (s) {
+      case A a -> "Sealed sub-class A";
+      case B b -> "Sealed sub-class B";
+      case C c -> "Sealed sub-record C";
+    };
+  }
+
+  /**
+   * According to an example from JEP 420, this should work, but it does not, neither with Javac nor ECJ.
+   *
+   * See:
+   *   https://openjdk.java.net/jeps/420#1b--Dominance-of-pattern-labels
+   *   https://bugs.openjdk.java.net/browse/JDK-8273326
+   *   https://bugs.eclipse.org/bugs/show_bug.cgi?id=579355
+   *
+   * TODO: reactivate when implemented or move to preview 5 with Java 21, Eclipse 4.28.
+   */
+/*
+  static String constantLabelMustAppearBeforePattern(Object o) {
+    switch (o) {
+      case null -> System.out.println("value unavailable: " + o);
+      case -1, 1 -> System.out.println("special case:" + o);
+      case Integer value when value > 0 -> System.out.println("positive integer: " + o);
+      case Integer i -> System.out.println("other integer: " + o);
+      default -> System.out.println("non-integer: " + o);
+    }
+    return o == null ? "null" : o.toString();
+  }
+*/
+
+  static String constantLabelMustAppearBeforePatternInteger(Integer i) {
+    switch (i) {
+      case null -> System.out.println("value unavailable: " + i);
+      case -1, 1 -> System.out.println("absolute value 1: " + i);
+      case Integer value when value > 0 -> System.out.println("positive integer: " + i);
+      default -> System.out.println("other integer: " + i);
+    }
+    return i == null ? "null" : i.toString();
+  }
+
+  static void nullCanAppearAfterConstantLabel(Integer i) {
+    switch (i) {
+      case -1, 1 -> System.out.println("absolute value 1: " + i);
+      case null -> System.out.println("value unavailable: " + i);
+      case Integer value when value > 0 -> System.out.println("positive integer: " + i);
+      default -> System.out.println("other integer: " + i);
+    }
+  }
+
+  /**
+   * According to an example from JEP 420, this should work with preview 2 (Java 18), and it does with Javac,
+   * but not with ECJ for Java 18, 19 and 20.
+   *
+   * See:
+   *   https://openjdk.java.net/jeps/420#2--Exhaustiveness-of-switch-expressions-and-statements
+   *   https://bugs.eclipse.org/bugs/show_bug.cgi?id=579360
+   *   https://github.com/eclipse-jdt/eclipse.jdt.core/issues/587
+   *
+   * TODO: reactivate when implemented or move to preview 5 with Java 21.
+   */
+/*
+  sealed interface I<T> permits D, E {}
+  final static class D<X> implements I<String> {}
+  final static class E<Y> implements I<Y> {}
+
+  static int testGenericSealedExhaustive(I<Integer> i) {
+    return switch (i) {
+      // Exhaustive as no D case possible!
+      case E<Integer> bi -> 42;
+    };
+  }
+*/
+}

tests/src/test/java/org/aspectj/systemtest/ajc1919/AllTestsAspectJ1919.java

@@ -24,10 +24,11 @@ public class AllTestsAspectJ1919 {
 			suite.addTest(Ajc1919TestsJava.suite());
 		}
 		// Do not run tests using a previous compiler's preview features anymore. They would all fail.
-		// TODO: Comment out the following block when upgrading JDT Core to Java 20
+		/*
 		if (LangUtil.is19VMOrGreater() && !LangUtil.is20VMOrGreater()) {
 			suite.addTest(Java19PreviewFeaturesTests.suite());
 		}
+		*/
 		return suite;
 	}
 }

tests/src/test/java/org/aspectj/systemtest/ajc1920/Ajc1920TestsJava.java

@@ -0,0 +1,32 @@
+/*******************************************************************************
+ * Copyright (c) 2022 Contributors
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/org/documents/epl-2.0/EPL-2.0.txt
+ *******************************************************************************/
+package org.aspectj.systemtest.ajc1920;
+
+import junit.framework.Test;
+import org.aspectj.testing.XMLBasedAjcTestCase;
+import org.aspectj.testing.XMLBasedAjcTestCaseForJava20OrLater;
+
+/**
+ * @author Alexander Kriegisch
+ */
+public class Ajc1920TestsJava extends XMLBasedAjcTestCaseForJava20OrLater {
+
+  public void testDummyJava20() {
+    //runTest("dummy Java 20");
+  }
+
+  public static Test suite() {
+    return XMLBasedAjcTestCase.loadSuite(Ajc1920TestsJava.class);
+  }
+
+  @Override
+  protected java.net.URL getSpecFile() {
+    return getClassResource("ajc1920.xml");
+  }
+
+}

tests/src/test/java/org/aspectj/systemtest/ajc1920/AllTestsAspectJ1920.java

@@ -0,0 +1,33 @@
+/*******************************************************************************
+ * Copyright (c) 2022 Contributors
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/org/documents/epl-2.0/EPL-2.0.txt
+ *******************************************************************************/
+package org.aspectj.systemtest.ajc1920;
+
+import junit.framework.Test;
+import junit.framework.TestSuite;
+import org.aspectj.util.LangUtil;
+
+/**
+ * @author Alexander Kriegisch
+ */
+public class AllTestsAspectJ1920 {
+
+	public static Test suite() {
+		TestSuite suite = new TestSuite("AspectJ 1.9.20 tests");
+		suite.addTest(Bugs1920Tests.suite());
+		if (LangUtil.is20VMOrGreater()) {
+			suite.addTest(SanityTestsJava20.suite());
+			suite.addTest(Ajc1920TestsJava.suite());
+		}
+		// Do not run tests using a previous compiler's preview features anymore. They would all fail.
+		// TODO: Comment out the following block when upgrading JDT Core to Java 20
+		if (LangUtil.is20VMOrGreater() && !LangUtil.is21VMOrGreater()) {
+			suite.addTest(Java20PreviewFeaturesTests.suite());
+		}
+		return suite;
+	}
+}

tests/src/test/java/org/aspectj/systemtest/ajc1920/Bugs1920Tests.java

@@ -0,0 +1,31 @@
+/*******************************************************************************
+ * Copyright (c) 2022 Contributors
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/org/documents/epl-2.0/EPL-2.0.txt
+ *******************************************************************************/
+package org.aspectj.systemtest.ajc1920;
+
+import junit.framework.Test;
+import org.aspectj.testing.XMLBasedAjcTestCase;
+
+/**
+ * @author Alexander Kriegisch
+ */
+public class Bugs1920Tests extends XMLBasedAjcTestCase {
+
+  public void testDummyJava20() {
+    //runTest("dummy Java 20");
+  }
+
+  public static Test suite() {
+    return XMLBasedAjcTestCase.loadSuite(Bugs1920Tests.class);
+  }
+
+  @Override
+  protected java.net.URL getSpecFile() {
+    return getClassResource("ajc1920.xml");
+  }
+
+}

tests/src/test/java/org/aspectj/systemtest/ajc1920/Java20PreviewFeaturesTests.java

@@ -0,0 +1,103 @@
+/*******************************************************************************
+ * Copyright (c) 2022 Contributors
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/org/documents/epl-2.0/EPL-2.0.txt
+ *******************************************************************************/
+package org.aspectj.systemtest.ajc1920;
+
+import junit.framework.Test;
+import org.aspectj.apache.bcel.Constants;
+import org.aspectj.testing.XMLBasedAjcTestCase;
+import org.aspectj.testing.XMLBasedAjcTestCaseForJava20Only;
+
+/**
+ * @author Alexander Kriegisch
+ */
+public class Java20PreviewFeaturesTests extends XMLBasedAjcTestCaseForJava20Only {
+
+  public void testSwitchPatternMatchingPreview4Java() {
+    runTest("switch pattern matching preview 4 java");
+    checkVersion("SwitchPatternPreview4OK", Constants.MAJOR_20, Constants.PREVIEW_MINOR_VERSION);
+  }
+
+  public void testSwitchPatternMatchingPreview4Error() {
+    runTest("switch pattern matching preview 4 error");
+  }
+
+  public void testSwitchPatternMatchingPreview3Aspect() {
+    runTest("switch pattern matching preview 3 aspect");
+    checkVersion("SwitchPatternPreview3Aspect", Constants.MAJOR_20, Constants.PREVIEW_MINOR_VERSION);
+    checkVersion("Application", Constants.MAJOR_20, Constants.PREVIEW_MINOR_VERSION);
+    checkVersion("Shape", Constants.MAJOR_20, Constants.PREVIEW_MINOR_VERSION);
+    checkVersion("S", Constants.MAJOR_20, Constants.PREVIEW_MINOR_VERSION);
+  }
+
+  public void testSwitchPatternMatchingCaseLabelDominatedByPrecedingError() {
+    runTest("switch pattern matching error");
+  }
+
+  public void testSwitchPatternMatchingPreview3Error1() {
+    runTest("switch pattern matching preview 3 error 1");
+  }
+
+  public void testSwitchPatternMatchingPreview3Error2() {
+    runTest("switch pattern matching preview 3 error 2");
+  }
+
+  public void testRecordPatternsPreview1OK() {
+    // https://github.com/eclipse-jdt/eclipse.jdt.core/issues/450
+    runTest("record patterns");
+  }
+
+  public void testRecordPatternsPreview1Error() {
+    // https://github.com/eclipse-jdt/eclipse.jdt.core/issues/450 (fixed for preview 2 in Eclipse 2033-03, 4.27)
+    runTest("record patterns error");
+    checkVersion("RecordPatternsPreview1Error", Constants.MAJOR_20, Constants.PREVIEW_MINOR_VERSION);
+    checkVersion("Box", Constants.MAJOR_20, Constants.PREVIEW_MINOR_VERSION);
+  }
+
+  public void testRecordPatternsPreview1ExhaustivenessOK1() {
+    // Falsely throws 'An enhanced switch statement should be exhaustive; a default label expected' twice,
+    // see https://github.com/eclipse-jdt/eclipse.jdt.core/issues/455
+    // TODO: Remove redundant default clauses when fixed upstream
+    System.out.println("TODO: fully activate when https://github.com/eclipse-jdt/eclipse.jdt.core/issues/455 has been fixed");
+    runTest("record patterns exhaustiveness 1");
+  }
+
+  public void testRecordPatternsPreview1Aspect() {
+    runTest("record patterns aspect");
+  }
+
+  public void testRecordPatternsPreview1ExhaustivenessAspect() {
+    // Falsely throws 'An enhanced switch statement should be exhaustive; a default label expected' twice,
+    // see https://github.com/eclipse-jdt/eclipse.jdt.core/issues/455
+    // TODO: Remove redundant default clauses when fixed upstream
+    System.out.println("TODO: fully activate when https://github.com/eclipse-jdt/eclipse.jdt.core/issues/455 has been fixed");
+    runTest("record patterns exhaustiveness aspect");
+  }
+
+  public void testRecordPatternsPreview1ExhaustivenessError() {
+    // See https://github.com/eclipse-jdt/eclipse.jdt.core/issues/455
+    runTest("record patterns exhaustiveness error");
+  }
+
+  public void testRecordPatternsPreview1ExhaustivenessOK2() {
+    // Falsely throws 'An enhanced switch statement should be exhaustive; a default label expected',
+    // see https://github.com/eclipse-jdt/eclipse.jdt.core/issues/398
+    // TODO: activate when fixed
+    System.out.println("TODO: activate when https://github.com/eclipse-jdt/eclipse.jdt.core/issues/398 has been fixed");
+    //runTest("record patterns exhaustiveness 2");
+  }
+
+  public static Test suite() {
+    return XMLBasedAjcTestCase.loadSuite(Java20PreviewFeaturesTests.class);
+  }
+
+  @Override
+  protected java.net.URL getSpecFile() {
+    return getClassResource("ajc1920.xml");
+  }
+
+}

tests/src/test/java/org/aspectj/systemtest/ajc1920/SanityTestsJava20.java

@@ -0,0 +1,87 @@
+/*******************************************************************************
+ * Copyright (c) 2022 Contributors
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/org/documents/epl-2.0/EPL-2.0.txt
+ *******************************************************************************/
+package org.aspectj.systemtest.ajc1920;
+
+import junit.framework.Test;
+import org.aspectj.testing.XMLBasedAjcTestCase;
+import org.aspectj.testing.XMLBasedAjcTestCaseForJava20OrLater;
+
+/*
+ * Some very trivial tests that help verify things are OK.
+ * These are a copy of the earlier Sanity Tests created for 1.6 but these supply the -20 option
+ * to check code generation and modification with that version specified.
+ *
+ * @author Alexander Kriegisch
+ */
+public class SanityTestsJava20 extends XMLBasedAjcTestCaseForJava20OrLater {
+
+	public static final int bytecode_version_for_JDK_level = 64;
+
+	// Incredibly trivial test programs that check the compiler works at all (these are easy-ish to debug)
+	public void testSimpleJava_A() {
+		runTest("simple - a");
+	}
+
+	public void testSimpleJava_B() {
+		runTest("simple - b");
+	}
+
+	public void testSimpleCode_C() {
+		runTest("simple - c");
+	}
+
+	public void testSimpleCode_D() {
+		runTest("simple - d");
+	}
+
+	public void testSimpleCode_E() {
+		runTest("simple - e");
+	}
+
+	public void testSimpleCode_F() {
+		runTest("simple - f");
+	}
+
+	public void testSimpleCode_G() {
+		runTest("simple - g");
+	}
+
+	public void testSimpleCode_H() {
+		runTest("simple - h", true);
+	}
+
+	public void testSimpleCode_I() {
+		runTest("simple - i");
+	}
+
+	public void testVersionCorrect1() {
+		runTest("simple - j");
+		checkVersion("A", bytecode_version_for_JDK_level, 0);
+	}
+
+	public void testVersionCorrect2() {
+		runTest("simple - k");
+		checkVersion("A", bytecode_version_for_JDK_level, 0);
+	}
+
+	public void testVersionCorrect4() {
+		runTest("simple - m");
+		// Must be 49.0 when -1.5 is specified
+		checkVersion("A", 49, 0);
+	}
+
+	public static Test suite() {
+		return XMLBasedAjcTestCase.loadSuite(SanityTestsJava20.class);
+	}
+
+	@Override
+	protected java.net.URL getSpecFile() {
+		return getClassResource("sanity-tests-20.xml");
+	}
+
+}

tests/src/test/resources/org/aspectj/systemtest/ajc1920/ajc1920.xml

@@ -0,0 +1,179 @@
+<!DOCTYPE suite SYSTEM "../tests/ajcTestSuite.dtd"[]>
+
+<!--
+  Java 20: no new final language features, only preview/incubator ones:
+    - "JEP 432:	Record Patterns (Second Preview)" (###)
+    - "JEP 433:	Pattern Matching for switch (Fourth Preview)" (###)
+    - "JEP 429:	Scoped Values (Incubator)" (API only)
+    - "JEP 436:	Virtual Threads (Second Preview)" (API only)
+    - "JEP 437:	Structured Concurrency (Second Incubator)" (API only)
+-->
+<suite>
+
+	<!-- Java ?? final, Java 17, 18, 19, 20 preview -->
+	<ajc-test dir="features1920/java20" vm="20" title="switch pattern matching preview 4 java">
+		<compile files="SwitchPatternPreview4OK.java" options="--enable-preview -20" />
+		<run class="SwitchPatternPreview4OK" vmargs="--enable-preview">
+			<message></message>
+			<stdout>
+				<line text="null" />
+				<line text="int 123" />
+				<line text="long 999" />
+				<line text="double 12.340000" />
+				<line text="String foo" />
+				<line text="[123, foo, 999, 12.34]" />
+				<line text="Non-circle" />
+				<line text="Small circle" />
+				<line text="Large circle" />
+				<line text="Sealed sub-class A" />
+				<line text="Sealed sub-class B" />
+				<line text="Sealed sub-record C" />
+				<line text="absolute value 1: -1" />
+				<line text="other integer: 0" />
+				<line text="positive integer: 42" />
+				<line text="other integer: -99" />
+				<line text="positive integer: 123" />
+				<line text="value unavailable: null" />
+			</stdout>
+		</run>
+	</ajc-test>
+
+	<!-- Java ?? final, Java 17, 18, 19, 20 preview -->
+	<ajc-test dir="features1920/java20" vm="20" title="switch pattern matching preview 4 error">
+		<compile files="SwitchPatternPreview4Error.java" options="--enable-preview -20">
+			<!-- TODO: Add correct compiler error message, as soon as JDT Core supports it -->
+			<message kind="error" file="SwitchPatternPreview4Error.java" text="This case label is dominated by one of the preceding case label"/>
+		</compile>
+	</ajc-test>
+
+	<!-- Java ?? final, Java 17, 18, 19, 20 preview -->
+	<ajc-test dir="features1919/java19" vm="20" title="switch pattern matching preview 3 aspect">
+		<compile files="SwitchPatternPreview3Aspect.aj" options="--enable-preview -20" />
+		<run class="Application" vmargs="--enable-preview">
+			<stdout>
+				<line text="null" />
+				<line text="int 123" />
+				<line text="long 999" />
+				<line text="double 12.340000" />
+				<line text="String foo" />
+				<line text="[123, foo, 999, 12.34]" />
+				<line text="Non-circle" />
+				<line text="Small circle" />
+				<line text="Large circle" />
+				<line text="Sealed sub-class A" />
+				<line text="Sealed sub-class B" />
+				<line text="Sealed sub-record C" />
+				<line text="absolute value 1: -1" />
+				<line text="other integer: 0" />
+				<line text="positive integer: 42" />
+				<line text="other integer: -99" />
+				<line text="positive integer: 123" />
+				<line text="value unavailable: null" />
+			</stdout>
+		</run>
+	</ajc-test>
+
+	<!-- Java ?? final, Java 17, 18, 19, 20 preview -->
+	<ajc-test dir="features198/java17" vm="20" title="switch pattern matching error">
+		<compile files="SwitchPatternError.java" options="--enable-preview -20">
+			<!-- TODO: Add correct compiler error message, as soon as JDT Core supports it -->
+			<message kind="error" file="SwitchPatternError.java" text="This case label is dominated by one of the preceding case label"/>
+		</compile>
+	</ajc-test>
+
+	<!-- Java ?? final, Java 17, 18, 19, 20 preview -->
+	<ajc-test dir="features1919/java19" vm="20" title="switch pattern matching preview 3 error 1">
+		<compile files="SwitchPatternPreview3Error1.java" options="--enable-preview -20">
+			<!-- TODO: Add correct compiler error message, as soon as JDT Core supports it -->
+			<message kind="error" file="SwitchPatternPreview3Error1.java" text="This case label is dominated by one of the preceding case label"/>
+		</compile>
+	</ajc-test>
+
+	<!-- Java ?? final, Java 17, 18, 19, 20 preview -->
+	<ajc-test dir="features1919/java19" vm="20" title="switch pattern matching preview 3 error 2">
+		<compile files="SwitchPatternPreview3Error2.java" options="--enable-preview -20">
+			<!-- TODO: Add correct compiler error message, as soon as JDT Core supports it -->
+			<message kind="error" file="SwitchPatternPreview3Error2.java" text="This case label is dominated by one of the preceding case label"/>
+		</compile>
+	</ajc-test>
+
+	<!-- Java ?? final, Java 19, 20 preview -->
+	<ajc-test dir="features1919/java19" vm="20" title="record patterns">
+		<compile files="RecordPatternsPreview1OK.java" options="--enable-preview -20"/>
+	</ajc-test>
+
+	<!-- Java ?? final, Java 19, 20 preview -->
+	<ajc-test dir="features1919/java19" vm="20" title="record patterns error">
+		<compile files="RecordPatternsPreview1Error.java" options="--enable-preview -20">
+			<!-- https://github.com/eclipse-jdt/eclipse.jdt.core/issues/450 (fixed for preview 2 in Eclipse 2033-03, 4.27) -->
+			<!--
+			<message kind="error" file="RecordPatternsPreview1Error.java" text="Raw types are not allowed in record patterns"/>
+			<message kind="error" file="RecordPatternsPreview1Error.java" text="Raw types are not allowed in record patterns"/>
+			-->
+		</compile>
+		<run class="RecordPatternsPreview1Error" vmargs="--enable-preview">
+			<stdout>
+				<line text="I'm a box"/>
+				<line text="I'm a box"/>
+			</stdout>
+		</run>
+	</ajc-test>
+
+	<!-- Java ?? final, Java 19, 20 preview -->
+	<ajc-test dir="features1919/java19" vm="20" title="record patterns exhaustiveness 1">
+		<compile files="RecordPatternsPreview1ExhaustivenessOK1.java" options="--enable-preview -20"/>
+		<run class="RecordPatternsPreview1ExhaustivenessOK1" vmargs="--enable-preview">
+			<stdout>
+				<line text="y"/>
+				<line text="a"/>
+			</stdout>
+		</run>
+	</ajc-test>
+
+	<!-- Java ?? final, Java 19, 20 preview -->
+	<ajc-test dir="features1919/java19" vm="20" title="record patterns exhaustiveness aspect">
+		<compile files="RecordPatternsPreview1ExhaustivenessAspect.aj" options="--enable-preview -20"/>
+		<!-- TODO: Remove redundant default clauses when https://github.com/eclipse-jdt/eclipse.jdt.core/issues/455 has been fixed -->
+		<run class="RecordPatternsPreview1ExhaustivenessAspect" vmargs="--enable-preview">
+			<stdout>
+				<line text="y"/>
+				<line text="a"/>
+				<line text="Pair[x=C@000, y=D@000]"/>
+			</stdout>
+		</run>
+	</ajc-test>
+
+	<!-- Java ?? final, Java 19, 20 preview -->
+	<ajc-test dir="features1919/java19" vm="20" title="record patterns aspect">
+		<compile files="RecordPatternsPreview1Aspect.aj" options="--enable-preview -20"/>
+		<run class="RecordPatternsPreview1Aspect" vmargs="--enable-preview">
+			<stdout>
+				<line text="9"/>
+				<line text="14"/>
+				<line text="Doing something with Point[x=2, y=7]"/>
+				<line text="Upper-left color: RED"/>
+				<line text="Upper-left color: RED"/>
+				<line text="Upper-left x coordinate: 1"/>
+				<line text="Doing something with Rectangle[upperLeft=ColoredPoint[p=Point[x=1, y=6], c=RED], lowerRight=ColoredPoint[p=Point[x=4, y=6], c=BLUE]]"/>
+			</stdout>
+		</run>
+	</ajc-test>
+
+	<!-- Java ?? final, Java 19, 20 preview -->
+	<ajc-test dir="features1919/java19" vm="20" title="record patterns exhaustiveness error">
+		<compile files="RecordPatternsPreview1ExhaustivenessError.java" options="--enable-preview -20">
+			<message kind="error" file="RecordPatternsPreview1ExhaustivenessError.java" text="An enhanced switch statement should be exhaustive; a default label expected"/>
+		</compile>
+	</ajc-test>
+
+	<!-- Java ?? final, Java 19, 20 preview -->
+	<ajc-test dir="features1919/java19" vm="20" title="record patterns exhaustiveness 2">
+		<compile files="RecordPatternsPreview1ExhaustivenessOK2.java" options="--enable-preview -20"/>
+		<run class="RecordPatternsPreview1ExhaustivenessOK2" vmargs="--enable-preview">
+			<stdout>
+				<line text="Bob 12"/>
+			</stdout>
+		</run>
+	</ajc-test>
+
+</suite>

tests/src/test/resources/org/aspectj/systemtest/ajc1920/sanity-tests-20.xml

@@ -0,0 +1,70 @@
+<!DOCTYPE suite SYSTEM "../tests/ajcTestSuite.dtd"[]>
+
+<suite>
+
+    <!-- empty class -->
+    <ajc-test dir="bugs160/simplejava" title="simple - a">
+      <compile files="SimpleA.java" options="-20"/>
+    </ajc-test>
+
+    <!-- class with one method -->
+    <ajc-test dir="bugs160/simplejava" title="simple - b">
+      <compile files="SimpleB.java" options="-20"/>
+      <run class="SimpleB"/>
+    </ajc-test>
+
+    <!-- empty aspect -->
+    <ajc-test dir="bugs160/simplejava" title="simple - c">
+      <compile files="SimpleC.java" options="-20"/>
+    </ajc-test>
+
+    <!-- simple before -->
+    <ajc-test dir="bugs160/simplejava" title="simple - d">
+      <compile files="SimpleD.java" options="-20"/>
+    </ajc-test>
+
+    <!-- simple itd field -->
+    <ajc-test dir="bugs160/simplejava" title="simple - e">
+      <compile files="SimpleE.java" options="-20"/>
+    </ajc-test>
+
+    <!-- aspect with main calling a static method -->
+    <ajc-test dir="bugs160/simplejava" title="simple - f">
+      <compile files="SimpleF.java" options="-20"/>
+    </ajc-test>
+
+    <!-- pertarget -->
+    <ajc-test dir="bugs160/simplejava" title="simple - g">
+      <compile files="SimpleG.java" options="-20"/>
+    </ajc-test>
+
+    <!-- generic ctor itds -->
+    <ajc-test dir="bugs160/simplejava" title="simple - h">
+      <compile files="SimpleH.java" options="-20"/>
+    </ajc-test>
+
+    <!-- overriding generic itd methods -->
+    <ajc-test dir="bugs160/simplejava" title="simple - i">
+      <compile files="SimpleI.java" options="-20"/>
+    </ajc-test>
+
+    <!-- check class file version is 64.0 (Java 20) -->
+    <ajc-test dir="bugs160/simplejava" title="simple - j">
+      <compile files="SimpleJ.java" options="-20"/>
+    </ajc-test>
+
+    <!-- check class file version is 64.0 (Java 20) -->
+    <ajc-test dir="bugs160/simplejava" title="simple - k">
+      <compile files="SimpleJ.java" options="-source 20"/>
+    </ajc-test>
+
+    <!-- check class file version is 49.0 -->
+    <ajc-test dir="bugs160/simplejava" title="simple - m">
+      <compile files="SimpleJ.java" options="-1.5"/>
+    </ajc-test>
+
+    <ajc-test dir="bugs160/simplejava" title="simple - n">
+      <compile files="SimpleN.java" options="-20"/>
+    </ajc-test>
+
+</suite>

util/src/main/java/org/aspectj/util/LangUtil.java

@@ -187,6 +187,10 @@ public class LangUtil {
 		return 20 <= vmVersion;
 	}
 
+	public static boolean is21VMOrGreater() {
+		return 21 <= vmVersion;
+	}
+
 	/**
 	 * Shorthand for "if null, throw IllegalArgumentException"
 	 *