[JEP 488][Preview][Primitive Patterns] ECJ crashes compiling switch over

void typed selector expression

+ report error rather than crashing

Fixes eclipse-jdt#3369

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

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2023 IBM Corporation and others.
+ * Copyright (c) 2000, 2025 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -8,6 +8,10 @@
  *
  * SPDX-License-Identifier: EPL-2.0
  *
+ * This is an implementation of an early-draft specification developed under the Java
+ * Community Process (JCP) and is made available for testing and evaluation purposes
+ * only. The code is not compatible with any specification of the JCP.
+ *
  * Contributors:
  *     IBM Corporation - initial API and implementation
  *     Stephan Herrmann - Contributions for
@@ -552,6 +556,10 @@ public void resolve(BlockScope upperScope) {
 				this.expression.computeConversion(upperScope, expressionType, expressionType);
 				checkType: {
 					if (expressionType.isBaseType()) {
+						if (expressionType.id == TypeIds.T_void) {
+							upperScope.problemReporter().illegalVoidExpression(this.expression);
+							break checkType;
+						}
 						if (JavaFeature.PRIMITIVES_IN_PATTERNS.isSupported(compilerOptions)) {
 							upperScope.referenceContext().compilationResult().usesPreview = true;
 							this.isPrimitiveSwitch = true;

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

@@ -2701,4 +2701,45 @@ public static void main(String[] args) {
 			},
 			"Null");
 	}
+	public void testGH3369_statement() {
+		runNegativeTest(new String[] {
+				"X.java",
+				"""
+				public class X {
+					public static void main(String[] args) {
+						switch (main(null)) {
+
+						}
+					}
+				}
+				"""
+			},
+			"----------\n" +
+			"1. ERROR in X.java (at line 3)\n" +
+			"	switch (main(null)) {\n" +
+			"	        ^^^^^^^^^^\n" +
+			"Expression must return a value\n" +
+			"----------\n");
+	}
+	public void testGH3369_expression() {
+		runNegativeTest(new String[] {
+				"X.java",
+				"""
+				public class X {
+					int foo() {
+						return switch (bar()) {
+							default -> 1;
+						};
+					}
+					void bar() {}
+				}
+				"""
+			},
+			"----------\n" +
+			"1. ERROR in X.java (at line 3)\n" +
+			"	return switch (bar()) {\n" +
+			"	               ^^^^^\n" +
+			"Expression must return a value\n" +
+			"----------\n");
+	}
 }