Index: lucene/CHANGES.txt
===================================================================
--- lucene/CHANGES.txt	(revision 1518581)
+++ lucene/CHANGES.txt	(working copy)
@@ -149,6 +149,9 @@
   implementing end() then be sure it calls super.end().  (Robert Muir,
   Mike McCandless)
 
+* LUCENE-5192: IndexWriter could allow adding same field name with different
+  DocValueTypes under some circumstances. (Shai Erera)
+
 API Changes
 
 * LUCENE-5094: Add ramBytesUsed() to MultiDocValues.OrdinalMap.
Index: lucene/core/src/java/org/apache/lucene/index/FieldInfos.java
===================================================================
--- lucene/core/src/java/org/apache/lucene/index/FieldInfos.java	(revision 1518581)
+++ lucene/core/src/java/org/apache/lucene/index/FieldInfos.java	(working copy)
@@ -288,6 +288,8 @@
 
         if (docValues != null) {
           fi.setDocValuesType(docValues);
+          // must also update docValuesType map so it's aware of this field's DocValueType 
+          globalFieldNumbers.docValuesType.put(name, docValues);
         }
 
         if (!fi.omitsNorms() && normType != null) {
Index: lucene/core/src/test/org/apache/lucene/index/TestDocValuesIndexing.java
===================================================================
--- lucene/core/src/test/org/apache/lucene/index/TestDocValuesIndexing.java	(revision 1518581)
+++ lucene/core/src/test/org/apache/lucene/index/TestDocValuesIndexing.java	(working copy)
@@ -26,9 +26,11 @@
 import org.apache.lucene.document.BinaryDocValuesField;
 import org.apache.lucene.document.Document;
 import org.apache.lucene.document.Field;
+import org.apache.lucene.document.Field.Store;
 import org.apache.lucene.document.NumericDocValuesField;
 import org.apache.lucene.document.SortedDocValuesField;
 import org.apache.lucene.document.SortedSetDocValuesField;
+import org.apache.lucene.document.StringField;
 import org.apache.lucene.document.TextField;
 import org.apache.lucene.search.FieldCache;
 import org.apache.lucene.store.Directory;
@@ -751,4 +753,30 @@
     dir.close();
   }
 
+  public void testSameFieldNameForPostingAndDocValue() throws Exception {
+    // LUCENE-5192: FieldInfos.Builder neglected to update
+    // globalFieldNumbers.docValuesType map if the field existed, resulting in
+    // potentially adding the same field with different DV types.
+    Directory dir = newDirectory();
+    IndexWriterConfig conf = newIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(random()));
+    IndexWriter writer = new IndexWriter(dir, conf);
+    
+    Document doc = new Document();
+    doc.add(new StringField("f", "mock-value", Store.NO));
+    doc.add(new NumericDocValuesField("f", 5));
+    writer.addDocument(doc);
+    writer.commit();
+    
+    doc = new Document();
+    doc.add(new BinaryDocValuesField("f", new BytesRef("mock")));
+    try {
+      writer.addDocument(doc);
+      fail("should not have succeeded to add a field with different DV type than what already exists");
+    } catch (IllegalArgumentException e) {
+      writer.rollback();
+    }
+    
+    dir.close();
+  }
+
 }