8080641: JEP-JDK-8042880 : Implement new tests on Project Coin

A set of tests using t-w-r as variable in different positive and negative constructions

Reviewed-by: abuckley, darcy, jlahoda, sadayapalam

langtools/test/tools/javac/defaultMethods/private/PrivateGenerics.java

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+/*
+ * 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    8071453
+ * @summary Verify that generics work with private method in interface
+ */
+
+public class PrivateGenerics {
+
+    interface I<T> {
+        private T foo() { return null; };
+        default void m(T t) {
+            T t1 = t;
+            T t2 = foo();
+        }
+    }
+
+    interface J {
+        private <M> M foo() { return null; }
+        default <N> void m(N n) {
+            N n1 = n;
+            N n2 = foo();
+        }
+    }
+
+    public static void main(String[] args) {
+        I<String> i = new I<>() {};
+        i.m("string");
+        String s = i.foo();
+
+        J j = new J() {};
+        j.m("string");
+        s = j.foo();
+    }
+}