Support default value for time span (#18761)

* Support the defaultvalue in timespace. Use duration as the qualified name for timespan.

* Update based on the code review feedback.

* Add more default value scenario.

* Update verification

Author: huanwu

src/System.Private.Xml/src/System/Xml/Serialization/CodeGenerator.cs

@@ -845,8 +845,22 @@ internal void Ldc(object o)
                     case TypeCode.Empty:
                     case TypeCode.DBNull:
                     default:
-                        Debug.Assert(false, "UnknownConstantType");
-                        throw new NotSupportedException(SR.Format(SR.UnknownConstantType, valueType.AssemblyQualifiedName));
+                        if (valueType == typeof(TimeSpan))
+                        {
+                            ConstructorInfo TimeSpan_ctor = typeof(TimeSpan).GetConstructor(
+                            CodeGenerator.InstanceBindingFlags,
+                            null,
+                            new Type[] { typeof(Int64) },
+                            null
+                            );
+                            Ldc(((TimeSpan)o).Ticks); // ticks
+                            New(TimeSpan_ctor);
+                            break;
+                        }
+                        else
+                        {
+                            throw new NotSupportedException(SR.Format(SR.UnknownConstantType, valueType.AssemblyQualifiedName));
+                        }
                 }
             }
         }

src/System.Private.Xml/src/System/Xml/Serialization/Types.cs

@@ -538,7 +538,7 @@ static TypeScope()
 
             AddNonXsdPrimitive(typeof(Guid), "guid", UrtTypes.Namespace, "Guid", new XmlQualifiedName("string", XmlSchema.Namespace), new XmlSchemaFacet[] { guidPattern }, TypeFlags.CanBeAttributeValue | TypeFlags.CanBeElementValue | TypeFlags.XmlEncodingNotRequired | TypeFlags.IgnoreDefault);
             AddNonXsdPrimitive(typeof(char), "char", UrtTypes.Namespace, "Char", new XmlQualifiedName("unsignedShort", XmlSchema.Namespace), new XmlSchemaFacet[0], TypeFlags.CanBeAttributeValue | TypeFlags.CanBeElementValue | TypeFlags.HasCustomFormatter | TypeFlags.IgnoreDefault);
-            AddNonXsdPrimitive(typeof(TimeSpan), "TimeSpan", UrtTypes.Namespace, "TimeSpan", new XmlQualifiedName("string", XmlSchema.Namespace), new XmlSchemaFacet[0], TypeFlags.CanBeAttributeValue | TypeFlags.CanBeElementValue | TypeFlags.XmlEncodingNotRequired | TypeFlags.IgnoreDefault);
+            AddNonXsdPrimitive(typeof(TimeSpan), "TimeSpan", UrtTypes.Namespace, "TimeSpan", new XmlQualifiedName("duration", XmlSchema.Namespace), new XmlSchemaFacet[0], TypeFlags.CanBeAttributeValue | TypeFlags.CanBeElementValue | TypeFlags.XmlEncodingNotRequired);
 
             AddSoapEncodedTypes(Soap.Encoding);
 

src/System.Private.Xml/tests/XmlSerializer/XmlSerializerTests.cs

@@ -1658,6 +1658,18 @@ public static void Xml_TypeWithTimeSpanProperty()
         Assert.StrictEqual(obj.TimeSpanProperty, deserializedObj.TimeSpanProperty);
     }
 
+    [Fact]
+    public static void Xml_TypeWithDefaultTimeSpanProperty()
+    {
+        var obj = new TypeWithDefaultTimeSpanProperty { TimeSpanProperty2 = new TimeSpan(0, 1, 0) };
+        var deserializedObj = SerializeAndDeserialize(obj,
+@"<?xml version=""1.0""?>
+<TypeWithDefaultTimeSpanProperty xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"" xmlns:xsd=""http://www.w3.org/2001/XMLSchema""><TimeSpanProperty2>PT1M</TimeSpanProperty2></TypeWithDefaultTimeSpanProperty>");
+        Assert.NotNull(deserializedObj);
+        Assert.Equal(obj.TimeSpanProperty, deserializedObj.TimeSpanProperty);
+        Assert.Equal(obj.TimeSpanProperty2, deserializedObj.TimeSpanProperty2);
+    }
+
     [Fact]
     public static void Xml_TypeWithByteProperty()
     {

src/System.Runtime.Serialization.Xml/tests/SerializationTypes.cs

@@ -15,6 +15,7 @@
 using System.Xml.Serialization;
 using System.IO;
 using System.Text;
+using System.Reflection;
 
 namespace SerializationTypes
 {
@@ -3157,6 +3158,38 @@ public class TypeWithTimeSpanProperty
     public TimeSpan TimeSpanProperty;
 }
 
+public class TypeWithDefaultTimeSpanProperty
+{
+    public TypeWithDefaultTimeSpanProperty()
+    {
+        TimeSpanProperty = GetDefaultValue("TimeSpanProperty");
+        TimeSpanProperty2 = GetDefaultValue("TimeSpanProperty2");
+    }
+
+    [DefaultValue(typeof(TimeSpan), "00:01:00")]
+    public TimeSpan TimeSpanProperty { get; set; }
+
+    [DefaultValue(typeof(TimeSpan), "00:00:01")]
+    public TimeSpan TimeSpanProperty2 { get; set; }
+
+    public TimeSpan GetDefaultValue(string propertyName)
+    {
+        var property = this.GetType().GetProperty(propertyName);
+
+        var attribute = property.GetCustomAttribute(typeof(DefaultValueAttribute))
+                as DefaultValueAttribute;
+
+        if (attribute != null)
+        {
+            return (TimeSpan)attribute.Value;
+        }
+        else
+        {
+            return new TimeSpan(0, 0, 0);
+        }
+    }
+}
+
 public class TypeWithByteProperty
 {
     public byte ByteProperty;