8010010: NPE generating serializedLambdaName for nested lambda

Reviewed-by: mcimadamore

langtools/src/share/classes/com/sun/tools/javac/comp/LambdaToMethod.java

@@ -1293,9 +1293,16 @@ public class LambdaToMethod extends TreeTranslator {
             return names.lambda.append(names.fromString("" + lambdaCount++));
         }
 
+        /**
+         * For a serializable lambda, generate a name which maximizes name
+         * stability across deserialization.
+         * @param owner
+         * @return Name to use for the synthetic lambda method name
+         */
         private Name serializedLambdaName(Symbol owner) {
             StringBuilder buf = new StringBuilder();
             buf.append(names.lambda);
+            // Append the name of the method enclosing the lambda.
             String methodName = owner.name.toString();
             if (methodName.equals("<clinit>"))
                 methodName = "static";
@@ -1303,9 +1310,18 @@ public class LambdaToMethod extends TreeTranslator {
                 methodName = "new";
             buf.append(methodName);
             buf.append('$');
+            // Append a hash of the enclosing method signature to differentiate
+            // overloaded enclosing methods.  For lambdas enclosed in lambdas,
+            // the generated lambda method will not have type yet, but the
+            // enclosing method's name will have been generated with this same
+            // method, so it will be unique and never be overloaded.
+            if (owner.type != null) {
                 int methTypeHash = methodSig(owner.type).hashCode();
                 buf.append(Integer.toHexString(methTypeHash));
+            }
             buf.append('$');
+            // The above appended name components may not be unique, append a
+            // count based on the above name components.
             String temp = buf.toString();
             Integer count = serializableLambdaCounts.get(temp);
             if (count == null) {

langtools/test/tools/javac/lambda/LambdaLambdaSerialized.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2013, 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 8010010
+@summary NPE generating serializedLambdaName for nested lambda
+*/
+
+import java.io.*;
+import java.util.Map;
+import java.util.HashMap;
+
+public class LambdaLambdaSerialized {
+
+    static int assertionCount = 0;
+
+    static void assertTrue(boolean cond) {
+        assertionCount++;
+        if (!cond)
+            throw new AssertionError();
+    }
+
+    public static void main(String[] args) throws Exception {
+        try {
+            // Write lambdas out
+            ByteArrayOutputStream baos = new ByteArrayOutputStream();
+            ObjectOutput out = new ObjectOutputStream(baos);
+            LSI<LSI<Map>> ssi = () -> (() -> new HashMap());
+            write(out, ssi );
+            out.flush();
+            out.close();
+
+            // Read them back
+            ByteArrayInputStream bais =
+                new ByteArrayInputStream(baos.toByteArray());
+            ObjectInputStream in = new ObjectInputStream(bais);
+            readAssert(in, "[X]");
+            in.close();
+        } catch (IOException e) {
+            e.printStackTrace();
+            throw e;
+        }
+    }
+
+    static void write(ObjectOutput out, LSI<LSI<Map>> lamb) throws IOException {
+        out.writeObject(lamb);
+    }
+
+    static void readAssert(ObjectInputStream in, String expected)  throws IOException, ClassNotFoundException {
+        LSI<LSI<Map>> ls = (LSI<LSI<Map>>) in.readObject();
+        Map result = ls.get().get();
+        System.out.printf("Result: %s\n", result);
+    }
+}
+
+interface LSI<T> extends Serializable {
+    T get();
+}