Merge pull request #2128 from dotnet-bot/from-tfs

Merge changes from TFS

Author: mellinoe

src/System.Xml.XmlSerializer/src/System/Xml/Serialization/XmlSerializer.cs

@@ -59,6 +59,7 @@ public class XmlSerializer
         private XmlMapping _mapping;
         private XmlDeserializationEvents _events = new XmlDeserializationEvents();
 #if NET_NATIVE
+        public string DefaultNamespace = null;
         private XmlSerializer innerSerializer;
         private readonly Type rootType;
 #endif
@@ -156,13 +157,7 @@ public XmlSerializer(Type type, string defaultNamespace)
                 throw new ArgumentNullException("type");
 
 #if NET_NATIVE
-            // The ctor is not supported, but we cannot throw PNSE unconditionally
-            // because the ctor is used by ctor(Type) which passes in a null defaultNamespace.
-            if (!string.IsNullOrEmpty(defaultNamespace))
-            {
-                throw new PlatformNotSupportedException();
-            }
-
+            this.DefaultNamespace = defaultNamespace;
             rootType = type;
 #endif
             _mapping = GetKnownMapping(type, defaultNamespace);
@@ -344,6 +339,11 @@ internal void Serialize(XmlWriter xmlWriter, object o, XmlSerializerNamespaces n
                         throw new InvalidOperationException(SR.Format(SR.Xml_MissingSerializationCodeException, this.rootType, typeof(XmlSerializer).Name));
                     }
 
+                    if (!string.IsNullOrEmpty(this.DefaultNamespace))
+                    {
+                        this.innerSerializer.DefaultNamespace = this.DefaultNamespace; 
+                    }
+                    
                     XmlSerializationWriter writer = this.innerSerializer.CreateWriter();
                     writer.Init(xmlWriter, namespaces == null || namespaces.Count == 0 ? DefaultNamespaces : namespaces, encodingStyle, id);
                     try
@@ -459,6 +459,11 @@ internal object Deserialize(XmlReader xmlReader, string encodingStyle, XmlDeseri
                         throw new InvalidOperationException(SR.Format(SR.Xml_MissingSerializationCodeException, this.rootType, typeof(XmlSerializer).Name));
                     }
 
+                    if (!string.IsNullOrEmpty(this.DefaultNamespace))
+                    {
+                        this.innerSerializer.DefaultNamespace = this.DefaultNamespace; 
+                    }
+
                     XmlSerializationReader reader = this.innerSerializer.CreateReader();
                     reader.Init(xmlReader, encodingStyle);
                     try