fix wrong comment; add test proving it's wrong; add mixed codec tests

lucene/core/src/java/org/apache/lucene/codecs/lucene60/Lucene60PointWriter.java

@@ -141,11 +141,17 @@ public class Lucene60PointWriter extends PointWriter implements Closeable {
             for(int i=0;i<mergeState.pointReaders.length;i++) {
               PointReader reader = mergeState.pointReaders[i];
 
-              Lucene60PointReader reader60 = (Lucene60PointReader) reader;
+              if (reader != null) {
-              if (reader60 != null) {
+
-                // TODO: I could just use the merged fieldInfo.number instead of resolving to this
+                // we confirmed this up above
-                // reader's FieldInfo, right?  Field numbers are always consistent across segments,
+                assert reader instanceof Lucene60PointReader;
-                // since when?
+                Lucene60PointReader reader60 = (Lucene60PointReader) reader;
+
+                // NOTE: we cannot just use the merged fieldInfo.number (instead of resolving to this
+                // reader's FieldInfo as we do below) because field numbers can easily be different
+                // when addIndexes(Directory...) copies over segments from another index:
+
+
                 FieldInfos readerFieldInfos = mergeState.fieldInfos[i];
                 FieldInfo readerFieldInfo = readerFieldInfos.fieldInfo(fieldInfo.name);
                 if (readerFieldInfo != null) {

lucene/core/src/java/org/apache/lucene/index/PointValues.java

@@ -1,9 +1,5 @@
 package org.apache.lucene.index;
 
-import java.io.IOException;
-
-import org.apache.lucene.util.bkd.BKDWriter;
-
 /*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
@@ -21,6 +17,10 @@ import org.apache.lucene.util.bkd.BKDWriter;
  * limitations under the License.
  */
 
+import java.io.IOException;
+
+import org.apache.lucene.util.bkd.BKDWriter;
+
 /** Allows recursively visiting point values indexed with {@link org.apache.lucene.document.IntPoint},
  *  {@link org.apache.lucene.document.FloatPoint}, {@link org.apache.lucene.document.LongPoint}, {@link org.apache.lucene.document.DoublePoint}
  *  or {@link org.apache.lucene.document.BinaryPoint}.

lucene/core/src/test/org/apache/lucene/index/TestPointValues.java

@@ -18,10 +18,11 @@ package org.apache.lucene.index;
  */
 
 import org.apache.lucene.analysis.MockAnalyzer;
+import org.apache.lucene.codecs.Codec;
 import org.apache.lucene.document.BinaryPoint;
-import org.apache.lucene.document.IntPoint;
 import org.apache.lucene.document.Document;
 import org.apache.lucene.document.Field;
+import org.apache.lucene.document.IntPoint;
 import org.apache.lucene.store.Directory;
 import org.apache.lucene.util.IOUtils;
 import org.apache.lucene.util.LuceneTestCase;
@@ -388,4 +389,50 @@ public class TestPointValues extends LuceneTestCase {
     w.close();
     dir.close();
   }
+
+  // Write point values, one segment with Lucene60, another with SimpleText, then forceMerge with SimpleText
+  public void testDifferentCodecs1() throws Exception {
+    Directory dir = newDirectory();
+    IndexWriterConfig iwc = new IndexWriterConfig(new MockAnalyzer(random()));
+    iwc.setCodec(Codec.forName("Lucene60"));
+    IndexWriter w = new IndexWriter(dir, iwc);
+    Document doc = new Document();
+    doc.add(new IntPoint("int", 1));
+    w.addDocument(doc);
+    w.close();
+    
+    iwc = new IndexWriterConfig(new MockAnalyzer(random()));
+    iwc.setCodec(Codec.forName("SimpleText"));
+    w = new IndexWriter(dir, iwc);
+    doc = new Document();
+    doc.add(new IntPoint("int", 1));
+    w.addDocument(doc);
+
+    w.forceMerge(1);
+    w.close();
+    dir.close();
+  }
+
+  // Write point values, one segment with Lucene60, another with SimpleText, then forceMerge with Lucene60
+  public void testDifferentCodecs2() throws Exception {
+    Directory dir = newDirectory();
+    IndexWriterConfig iwc = new IndexWriterConfig(new MockAnalyzer(random()));
+    iwc.setCodec(Codec.forName("SimpleText"));
+    IndexWriter w = new IndexWriter(dir, iwc);
+    Document doc = new Document();
+    doc.add(new IntPoint("int", 1));
+    w.addDocument(doc);
+    w.close();
+    
+    iwc = new IndexWriterConfig(new MockAnalyzer(random()));
+    iwc.setCodec(Codec.forName("Lucene60"));
+    w = new IndexWriter(dir, iwc);
+    doc = new Document();
+    doc.add(new IntPoint("int", 1));
+    w.addDocument(doc);
+
+    w.forceMerge(1);
+    w.close();
+    dir.close();
+  }
 }

lucene/test-framework/src/java/org/apache/lucene/index/BasePointFormatTestCase.java

@@ -1,5 +1,22 @@
 package org.apache.lucene.index;
 
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 import java.io.IOException;
 import java.math.BigInteger;
 import java.util.ArrayList;
@@ -17,6 +34,8 @@ import org.apache.lucene.document.NumericDocValuesField;
 import org.apache.lucene.document.StringField;
 import org.apache.lucene.index.PointValues.IntersectVisitor;
 import org.apache.lucene.index.PointValues.Relation;
+import org.apache.lucene.search.ExactPointQuery;
+import org.apache.lucene.search.IndexSearcher;
 import org.apache.lucene.store.Directory;
 import org.apache.lucene.store.MockDirectoryWrapper;
 import org.apache.lucene.util.Bits;
@@ -26,23 +45,6 @@ import org.apache.lucene.util.NumericUtils;
 import org.apache.lucene.util.StringHelper;
 import org.apache.lucene.util.TestUtil;
 
-/*
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements.  See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
 /**
  * Abstract class to do basic tests for a points format.
  * NOTE: This test focuses on the points impl, nothing else.
@@ -820,6 +822,44 @@ public abstract class BasePointFormatTestCase extends BaseIndexFileFormatTestCas
     }
   }
 
+  public void testAddIndexes() throws IOException {
+    Directory dir1 = newDirectory();
+    RandomIndexWriter w = new RandomIndexWriter(random(), dir1);
+    Document doc = new Document();
+    doc.add(new IntPoint("int1", 17));
+    w.addDocument(doc);
+    doc = new Document();
+    doc.add(new IntPoint("int2", 42));
+    w.addDocument(doc);
+    w.close();
+
+    // Different field number assigments:
+    Directory dir2 = newDirectory();
+    w = new RandomIndexWriter(random(), dir2);
+    doc = new Document();
+    doc.add(new IntPoint("int2", 42));
+    w.addDocument(doc);
+    doc = new Document();
+    doc.add(new IntPoint("int1", 17));
+    w.addDocument(doc);
+    w.close();
+
+    Directory dir = newDirectory();
+    w = new RandomIndexWriter(random(), dir);
+    w.addIndexes(new Directory[] {dir1, dir2});
+    w.forceMerge(1);
+
+    DirectoryReader r = w.getReader();
+    IndexSearcher s = newSearcher(r);
+    assertEquals(2, s.count(ExactPointQuery.new1DIntExact("int1", 17)));
+    assertEquals(2, s.count(ExactPointQuery.new1DIntExact("int2", 42)));
+    r.close();
+    w.close();
+    dir.close();
+    dir1.close();
+    dir2.close();
+  }
+
   private void switchIndex(RandomIndexWriter w, Directory dir, RandomIndexWriter saveW) throws IOException {
     if (random().nextBoolean()) {
       // Add via readers: