8268250: Class.arrayType() for a 255-d array throws undocumented IllegalArgumentException

Reviewed-by: sundar, alanb

src/java.base/share/classes/java/lang/Class.java

@@ -4485,12 +4485,21 @@ public final class Class<T> implements java.io.Serializable,
      * Returns a {@code Class} for an array type whose component type
      * is described by this {@linkplain Class}.
      *
+     * @throws UnsupportedOperationException if this component type is {@linkplain
+     *         Void#TYPE void} or if the number of dimensions of the resulting array
+     *         type would exceed 255.
      * @return a {@code Class} describing the array type
+     * @jvms 4.3.2 Field Descriptors
+     * @jvms 4.4.1 The {@code CONSTANT_Class_info} Structure
      * @since 12
      */
     @Override
     public Class<?> arrayType() {
-        return Array.newInstance(this, 0).getClass();
+        try {
+            return Array.newInstance(this, 0).getClass();
+        } catch (IllegalArgumentException iae) {
+            throw new UnsupportedOperationException(iae);
+        }
     }
 
     /**

test/jdk/java/lang/Class/ArrayType.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2021, 2022, 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 8268250
+ * @summary Check exceptional behavior of Class.arrayType
+ */
+
+import java.lang.reflect.*;
+import java.util.function.*;
+
+public class ArrayType {
+    public static void main(String... args) {
+        expectException(() -> Void.TYPE);
+        expectException(() -> Array.newInstance(int.class, new int[255])
+                        .getClass());
+    }
+
+    private static void expectException(Supplier<Class<?>> arrayTypeArg) {
+        try {
+            Class<?> arrayClazz = arrayTypeArg.get().arrayType();
+            throw new RuntimeException("Expected exception not thrown: " +
+                                       arrayClazz);
+        } catch (UnsupportedOperationException uoe) {
+            ; // Expected
+        }
+    }
+}