Add DefaultOverload attribute to projected interface methods (#672)

* Add DefaultOverload attribute to projected interface methods as they are checked in authoring scenarios.

* Add other overload attribute.

src/Tests/AuthoringTest/Program.cs

@@ -1,5 +1,6 @@
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;
+using Microsoft.UI.Xaml.Markup;
 using System;
 using System.Collections;
 using System.Collections.Generic;
@@ -958,4 +959,23 @@ public IEnumerator GetEnumerator()
  return _enumerable.GetEnumerator();
  }
  }
+
+ public sealed class CustomXamlMetadataProvider : IXamlMetadataProvider
+ {
+ // Tests DefaultOverload attribute specified in projected interface.
+ public IXamlType GetXamlType(Type type)
+ {
+ throw new NotImplementedException();
+ }
+
+ public IXamlType GetXamlType(string fullName)
+ {
+ throw new NotImplementedException();
+ }
+
+ public XmlnsDefinition[] GetXmlnsDefinitions()
+ {
+ throw new NotImplementedException();
+ }
+ }
 }

src/cswinrt/code_writers.h

@@ -1303,7 +1303,7 @@ remove => %.% -= value;
  }
  }
  // Skip metadata attributes
- if (attribute_namespace == "Windows.Foundation.Metadata") continue;
+ if (attribute_namespace == "Windows.Foundation.Metadata" && attribute_name != "DefaultOverload" && attribute_name != "Overload") continue;
  attributes[attribute_full] = std::move(params);
  }
  if (auto&& usage = attributes.find("AttributeUsage"); usage != attributes.end())
@@ -2330,7 +2330,8 @@ private static global::System.Runtime.CompilerServices.ConditionalWeakTable<IWin
 
  method_signature signature{ method };
  w.write(R"(
-% %(%);)",
+%% %(%);)",
+ bind<write_custom_attributes>(method.CustomAttribute(), false),
  bind<write_projection_return_type>(signature),
  method.Name(),
  bind_list<write_projection_parameter>(", ", signature.params())