Fix for the XMLSerializer bug 18558

* Find the type map element that is the most-specific to the
  object in question, not the first type it is an instance of

Change-Id: I1867e790bf9f377ce0ae02871f4561b760e27624

2 files changed, 21 insertions, 7 deletions

diff --git a/mcs/class/System.XML/System.Xml.Serialization/XmlTypeMapMemberElement.cs b/mcs/class/System.XML/System.Xml.Serialization/XmlTypeMapMemberElement.cs
index f05ab6b2a01..072f9fee05c 100644
--- a/mcs/class/System.XML/System.Xml.Serialization/XmlTypeMapMemberElement.cs
+++ b/mcs/class/System.XML/System.Xml.Serialization/XmlTypeMapMemberElement.cs
@@ -83,9 +83,23 @@ namespace System.Xml.Serialization
 			else
 			{
 				if (memberValue == null)
-					return (XmlTypeMapElementInfo) _elementInfo[0];
-				foreach (XmlTypeMapElementInfo elem in _elementInfo)
-					if (elem.TypeData.Type.IsInstanceOfType (memberValue)) return elem;
+					return (XmlTypeMapElementInfo) _elementInfo [0];
+				else
+				{
+					XmlTypeMapElementInfo bestTypeElem = null;
+					// Select the most-specific type for the given memberValue
+					foreach (XmlTypeMapElementInfo elem in _elementInfo)
+					{
+						if (elem.TypeData.Type.IsInstanceOfType (memberValue))
+						{
+							if (bestTypeElem == null || elem.TypeData.Type.IsSubclassOf (bestTypeElem.TypeData.Type))
+							{
+								bestTypeElem = elem;
+							}
+						}
+					}
+					return bestTypeElem;
+				}
 			}
 			return null;
 		}
diff --git a/mcs/class/System.XML/Test/System.Xml.Serialization/XmlSerializerTests.cs b/mcs/class/System.XML/Test/System.Xml.Serialization/XmlSerializerTests.cs
index 19e7a9c21f4..1c81dd737f4 100644
--- a/mcs/class/System.XML/Test/System.Xml.Serialization/XmlSerializerTests.cs
+++ b/mcs/class/System.XML/Test/System.Xml.Serialization/XmlSerializerTests.cs
@@ -2864,21 +2864,21 @@ namespace MonoTests.System.XmlSerialization
 		#endregion //GenericsSeralizationTests
 		#region XmlInclude on abstract class tests (Bug #18558)
 		[Test]
-		public void TestSerializeIntermediateType()
+		public void TestSerializeIntermediateType ()
 		{
 			string expectedXml = "<ContainerTypeForTest xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\"><XmlIntermediateType intermediate=\"false\"/></ContainerTypeForTest>";
 			var obj = new ContainerTypeForTest();
-			obj.MemberToUseInclude = new IntermediateTypeForTest();
+			obj.MemberToUseInclude = new IntermediateTypeForTest ();
 			Serialize (obj);
 			Assert.AreEqual (Infoset (expectedXml), WriterText, "Serialized Output : " + WriterText);
 		}
 
 		[Test]
-		public void TestSerializeSecondType()
+		public void TestSerializeSecondType ()
 		{
 			string expectedXml = "<ContainerTypeForTest xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\"><XmlSecondType intermediate=\"false\"/></ContainerTypeForTest>";
 			var obj = new ContainerTypeForTest();
-			obj.MemberToUseInclude = new SecondDerivedTypeForTest();
+			obj.MemberToUseInclude = new SecondDerivedTypeForTest ();
 			Serialize (obj);
 			Assert.AreEqual (Infoset (expectedXml), WriterText, "Serialized Output : " + WriterText);
 		}