--- /dev/null	2015-11-20 14:00:45.000000000 -0800
+++ new/jdk/test/java/lang/StackWalker/WalkFunction.java	2015-11-20 14:00:45.000000000 -0800
@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 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 8020968
+ * @summary Sanity test for Function wildcard signature
+ * @run main WalkFunction
+ */
+
+import java.lang.StackWalker.StackFrame;
+import java.util.Optional;
+import java.util.function.Function;
+import java.util.stream.Stream;
+
+public class WalkFunction {
+    private static final StackWalker walker = StackWalker.getInstance();
+
+    public static void main(String... args) throws Exception {
+        testFunctions();
+        testWildcards();
+        walker.walk(counter());
+        walker.walk(wildCounter());
+    }
+
+    private static void testFunctions() {
+        walker.walk(Stream::count);
+
+        try {
+            walker.walk(null);
+            throw new RuntimeException("NPE expected");
+        } catch (NullPointerException e) {}
+
+        Optional<StackFrame> result = walker.walk(WalkFunction::reduce);
+        if (!result.get().getClassName().equals(WalkFunction.class.getName())) {
+            throw new RuntimeException(result.get() + " expected: " + WalkFunction.class.getName());
+        }
+    }
+
+    static Optional<StackFrame> reduce(Stream<StackFrame> stream) {
+        return stream.reduce((r,f) -> r.getClassName().compareTo(f.getClassName()) > 0 ? f : r);
+    }
+
+    private static void testWildcards() {
+        Function<? super Stream<? extends  StackFrame>, Void> f1 = WalkFunction::function;
+        Function<? super Stream<? super StackFrame>, Void> f2 = WalkFunction::function;
+        Function<? super Stream<StackFrame>, Void> f3 = WalkFunction::function;
+        Function<Stream<? extends StackFrame>, Void> f4 = WalkFunction::function;
+        Function<Stream<? super StackFrame>, Void> f5 = WalkFunction::function;
+        Function<Stream<StackFrame>, Void> f6 = WalkFunction::function;
+        walker.walk(f1);
+        walker.walk(f2);
+        walker.walk(f3);
+        walker.walk(f4);
+        walker.walk(f5);
+        walker.walk(f6);
+    }
+
+    private static Void function(Stream<?> s) {
+        return null;
+    }
+
+    private static Function<Stream<?>, Long> wildCounter() {
+        return Stream::count;
+    }
+    private static <T> Function<Stream<T>, Long> counter() {
+        return Stream::count;
+    }
+}