--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/langtools/tools/javac/T6999210.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,125 @@
+/*
+ * Copyright (c) 2010, 2015, 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 6999210
+ * @summary javac should be able to warn of anomalous conditions in classfiles
+ * @modules jdk.compiler
+ */
+
+import java.io.*;
+import java.util.*;
+
+public class T6999210 {
+    public static void main(String... args) throws Exception {
+        new T6999210().run();
+    }
+
+    void run() throws Exception {
+        File srcDir = new File("src");
+        File classesDir = new File("classes");
+        classesDir.mkdirs();
+
+        File c_java = writeFile(srcDir, "C.java", "class C<T> { }");
+        compile("-d", classesDir.getPath(), c_java.getPath());
+        File c_class = new File(classesDir, "C.class");
+        setMajorVersion(c_class, 48);
+        File d_java = writeFile(srcDir, "D.java", "class D { C c; }");
+
+        // verify no warning if -Xlint:classfile not enabled
+        String out1 = compile(
+            "-d", classesDir.getPath(),
+            "-classpath", classesDir.getPath(),
+            d_java.getPath());
+        if (out1.length() > 0)
+            error("unexpected output from javac");
+
+        // sanity check of warning when -XDrawDiagnostics not used
+        String out2 = compile(
+            "-d", classesDir.getPath(),
+            "-classpath", classesDir.getPath(),
+            "-Xlint:classfile",
+            d_java.getPath());
+        if (!out2.contains("[classfile]"))
+            error("expected output \"[classfile]\" not found");
+
+        // check specific details, using -XDrawDiagnostics
+        String out3 = compile(
+            "-d", classesDir.getPath(),
+            "-classpath", classesDir.getPath(),
+            "-Xlint:classfile", "-XDrawDiagnostics",
+            d_java.getPath());
+        String expect = "C.class:-:-: compiler.warn.future.attr: Signature, 49, 0, 48, 0";
+        if (!out3.contains(expect))
+            error("expected output \"" + expect + "\" not found");
+
+        if (errors > 0)
+            throw new Exception(errors + " errors occurred");
+    }
+
+    String compile(String... args) throws Exception {
+        System.err.println("compile: " + Arrays.asList(args));
+        StringWriter sw = new StringWriter();
+        PrintWriter pw = new PrintWriter(sw);
+        int rc = com.sun.tools.javac.Main.compile(args, pw);
+        pw.close();
+        String out = sw.toString();
+        if (out.length() > 0)
+            System.err.println(out);
+        if (rc != 0)
+            throw new Exception("compilation failed, rc=" + rc);
+        return out;
+    }
+
+    void setMajorVersion(File f, int major) throws IOException {
+        int len = (int) f.length();
+        byte[] data = new byte[len];
+        try (DataInputStream in = new DataInputStream(new FileInputStream(f))) {
+            in.readFully(data);
+        }
+        // u4 magic
+        // u2 minor
+        data[6] = (byte) (major >> 8);
+        data[7] = (byte) (major & 0xff);
+        try (FileOutputStream out = new FileOutputStream(f)) {
+            out.write(data);
+        }
+    }
+
+    File writeFile(File dir, String path, String body) throws IOException {
+        File f = new File(dir, path);
+        f.getParentFile().mkdirs();
+        try (FileWriter out = new FileWriter(f)) {
+            out.write(body);
+        }
+        return f;
+    }
+
+    void error(String msg) {
+        System.err.println("Error: " + msg);
+        errors++;
+    }
+
+    int errors;
+}