8315735: VerifyError when switch statement used with synchronized block

Reviewed-by: vromero

Author: lahodaj

src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/Gen.java

@@ -1278,11 +1278,17 @@ private void doHandleSwitchExpression(JCSwitchExpression tree) {
     }
     //where:
         private boolean hasTry(JCSwitchExpression tree) {
-            boolean[] hasTry = new boolean[1];
-            new TreeScanner() {
+            class HasTryScanner extends TreeScanner {
+                private boolean hasTry;
+
                 @Override
                 public void visitTry(JCTry tree) {
-                    hasTry[0] = true;
+                    hasTry = true;
+                }
+
+                @Override
+                public void visitSynchronized(JCSynchronized tree) {
+                    hasTry = true;
                 }
 
                 @Override
@@ -1292,8 +1298,12 @@ public void visitClassDef(JCClassDecl tree) {
                 @Override
                 public void visitLambda(JCLambda tree) {
                 }
-            }.scan(tree);
-            return hasTry[0];
+            };
+
+            HasTryScanner hasTryScanner = new HasTryScanner();
+
+            hasTryScanner.scan(tree);
+            return hasTryScanner.hasTry;
         }
 
     private void handleSwitch(JCTree swtch, JCExpression selector, List<JCCase> cases,

test/langtools/tools/javac/switchexpr/ExpressionSwitchSynchronized.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * @test
+ * @bug 8315735
+ * @summary Verify valid classfile is produced when synchronized block is used
+ *          inside a switch expression.
+ * @compile ExpressionSwitchSynchronized.java
+ * @run main ExpressionSwitchSynchronized
+ */
+public class ExpressionSwitchSynchronized {
+
+    public static void main(String... args) {
+        int i1 = 2 + switch (args.length) {
+            default -> {
+                synchronized (args) {
+                    yield 1;
+                }
+            }
+        };
+        if (i1 != 3) {
+            throw new AssertionError("Incorrect value, got: " + i1 +
+                                     ", expected: " + 3);
+        }
+        int i2 = 2 + switch (args) {
+            case String[] a -> {
+                synchronized (args) {
+                    yield a.length + 1;
+                }
+            }
+        };
+        if (i2 != 3) {
+            throw new AssertionError("Incorrect value, got: " + i2 +
+                                     ", expected: " + 3);
+        }
+    }
+
+}