8202758: SIGSEGV calling Class.forName(String,Boolean,ClassLoader) with mocked loader

Check that the unnamed module for a given ClassLoader is an instance of java.lang.Module.

Reviewed-by: alanb, acorn, coleenp, dholmes, hseigel

test/hotspot/jtreg/runtime/modules/ClassLoaderNoUnnamedModuleTest.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2018, 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 8202758
+ * @summary Ensure that if the JVM encounters a ClassLoader whose unnamedModule field is not set an InternalError results.
+ * @modules java.base/jdk.internal.misc
+ * @library /test/lib
+ * @compile ClassLoaderNoUnnamedModule.java
+ * @run main/othervm ClassLoaderNoUnnamedModuleTest
+ */
+
+import jdk.test.lib.process.ProcessTools;
+import jdk.test.lib.process.OutputAnalyzer;
+
+public class ClassLoaderNoUnnamedModuleTest {
+    public static void main(String args[]) throws Throwable {
+        ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
+                               "--add-modules=java.base",
+                               "--add-exports=java.base/jdk.internal.misc=ALL-UNNAMED",
+                               "-XX:-CreateCoredumpOnCrash",
+                               "ClassLoaderNoUnnamedModule");
+        OutputAnalyzer oa = new OutputAnalyzer(pb.start());
+        oa.shouldContain("Internal Error");
+        oa.shouldContain("unnamed module");
+        oa.shouldContain("null or not an instance of java.lang.Module");
+    }
+}