8061778: Wrong LineNumberTable for default constructors

Summary: Synthetic empty blocks generated by Lower are erroneously picked up by Gen
Reviewed-by: jjg

src/share/classes/com/sun/tools/javac/comp/Lower.java

@@ -2540,7 +2540,7 @@ public class Lower extends TreeTranslator {
         currentMethodSym = currentMethodSymPrev;
 
         // Return empty block {} as a placeholder for an inner class.
-        result = make_at(tree.pos()).Block(0, List.<JCStatement>nil());
+        result = make_at(tree.pos()).Block(SYNTHETIC, List.<JCStatement>nil());
     }
 
     /** Translate an enum class. */

src/share/classes/com/sun/tools/javac/jvm/Gen.java

@@ -486,7 +486,7 @@ public class Gen extends JCTree.Visitor {
                 JCBlock block = (JCBlock)def;
                 if ((block.flags & STATIC) != 0)
                     clinitCode.append(block);
-                else
+                else if ((block.flags & SYNTHETIC) == 0)
                     initCode.append(block);
                 break;
             case METHODDEF:

test/tools/javac/linenumbers/NestedLineNumberTest.java

+/*
+ * Copyright (c) 2014, 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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 8061778
+ * @summary  Wrong LineNumberTable for default constructors
+ */
+
+import com.sun.tools.classfile.ClassFile;
+import com.sun.tools.classfile.ConstantPoolException;
+import com.sun.tools.classfile.Method;
+import com.sun.tools.classfile.Attribute;
+import com.sun.tools.classfile.Code_attribute;
+import com.sun.tools.classfile.LineNumberTable_attribute;
+import com.sun.tools.classfile.LineNumberTable_attribute.Entry;
+
+import java.io.IOException;
+
+public class NestedLineNumberTest {
+
+    public static void main(String[] args) throws Exception {
+        Entry[] lines = findEntries();
+        if (lines == null || lines.length != 1) {
+            int found = lines == null ? 0 : lines.length;
+            error(String.format("LineNumberTable contains wrong number of entries - expected %d, found %d", 1, found));
+        }
+
+        int line = lines[0].line_number;
+        if (line != 78) {
+            error(String.format("LineNumberTable contains wrong line number - expected %d, found %d", 78, line));
+        }
+    }
+
+    static Entry[] findEntries() throws IOException, ConstantPoolException {
+        ClassFile self = ClassFile.read(NestedLineNumberTest.Test.class.getResourceAsStream("NestedLineNumberTest$Test.class"));
+        for (Method m : self.methods) {
+            if ("<init>".equals(m.getName(self.constant_pool))) {
+                Code_attribute code_attribute = (Code_attribute)m.attributes.get(Attribute.Code);
+                for (Attribute at : code_attribute.attributes) {
+                    if (Attribute.LineNumberTable.equals(at.getName(self.constant_pool))) {
+                        return ((LineNumberTable_attribute)at).line_number_table;
+                    }
+                }
+            }
+        }
+        return null;
+    }
+
+    static void error(String msg) {
+        throw new AssertionError(msg);
+    }
+
+    // The default constructor in this class should get only one LineNumberTable entry,
+    // pointing to the first line of the declaration of class Test.
+    static class Test {
+        static class Empty { }
+    }
+}