Support XmlnsDefinitionAttribute in "this" assembly

src/Controls/src/Build.Tasks/ModuleDefinitionExtensions.cs

@@ -254,7 +254,8 @@ public static TypeDefinition GetTypeDefinition(this ModuleDefinition module, Xam
 		{
 			return cache.GetOrAddTypeDefinition(module, type, x =>
 			{
-				var asm = module.Assembly.Name.Name == type.assemblyName
+				var assemblyName = module.Assembly.Name;
+				var asm = (assemblyName.Name == type.assemblyName || assemblyName.FullName == type.assemblyName)
 								? module.Assembly
 								: module.AssemblyResolver.Resolve(AssemblyNameReference.Parse(type.assemblyName));
 				var typeDef = asm.MainModule.GetType($"{type.clrNamespace}.{type.typeName}");

src/Controls/src/Build.Tasks/XmlTypeExtensions.cs

@@ -1,7 +1,6 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Xml;
-using Microsoft.Maui.Controls.Internals;
 using Microsoft.Maui.Controls.Xaml;
 using Mono.Cecil;
 using Mono.Cecil.Rocks;
@@ -10,6 +9,8 @@ namespace Microsoft.Maui.Controls.Build.Tasks
 {
 	static class XmlTypeExtensions
 	{
+		static readonly string _xmlnsDefinitionName = typeof(XmlnsDefinitionAttribute).FullName;
+
 		static IList<XmlnsDefinitionAttribute> GatherXmlnsDefinitionAttributes(ModuleDefinition module)
 		{
 			var xmlnsDefinitions = new List<XmlnsDefinitionAttribute>();
@@ -18,17 +19,11 @@ static IList<XmlnsDefinitionAttribute> GatherXmlnsDefinitionAttributes(ModuleDef
 			{
 				// Search for the attribute in the assemblies being
 				// referenced.
+				GatherXmlnsDefinitionAttributes(xmlnsDefinitions, module.Assembly);
 				foreach (var asmRef in module.AssemblyReferences)
 				{
 					var asmDef = module.AssemblyResolver.Resolve(asmRef);
-					foreach (var ca in asmDef.CustomAttributes)
-					{
-						if (ca.AttributeType.FullName == typeof(XmlnsDefinitionAttribute).FullName)
-						{
-							var attr = GetXmlnsDefinition(ca, asmDef);
-							xmlnsDefinitions.Add(attr);
-						}
-					}
+					GatherXmlnsDefinitionAttributes(xmlnsDefinitions, asmDef);
 				}
 			}
 			else
@@ -50,6 +45,18 @@ static IList<XmlnsDefinitionAttribute> GatherXmlnsDefinitionAttributes(ModuleDef
 			return xmlnsDefinitions;
 		}
 
+		static void GatherXmlnsDefinitionAttributes(List<XmlnsDefinitionAttribute> xmlnsDefinitions, AssemblyDefinition asmDef)
+		{
+			foreach (var ca in asmDef.CustomAttributes)
+			{
+				if (ca.AttributeType.FullName == _xmlnsDefinitionName)
+				{
+					var attr = GetXmlnsDefinition(ca, asmDef);
+					xmlnsDefinitions.Add(attr);
+				}
+			}
+		}
+
 		public static TypeReference GetTypeReference(XamlCache cache, string typeName, ModuleDefinition module, BaseNode node, bool expandToExtension = true)
 		{
 			try
@@ -97,7 +104,7 @@ public static TypeReference GetTypeReference(this XmlType xmlType, XamlCache cac
 			throw new BuildException(BuildExceptionCode.TypeResolution, xmlInfo, null, $"{xmlType.NamespaceUri}:{xmlType.Name}");
 		}
 
-		public static XmlnsDefinitionAttribute GetXmlnsDefinition(this CustomAttribute ca, AssemblyDefinition asmDef)
+		static XmlnsDefinitionAttribute GetXmlnsDefinition(this CustomAttribute ca, AssemblyDefinition asmDef)
 		{
 			var attr = new XmlnsDefinitionAttribute(
 							ca.ConstructorArguments[0].Value as string,

src/Controls/tests/Xaml.UnitTests/Issues/MauiXmlnsDef.xaml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             x:Class="Microsoft.Maui.Controls.Xaml.UnitTests.MauiXmlnsDef">
+  <StackLayout>
+    <!-- Following control is available via default xmlns -->
+    <MauiXmlnsDefControl/>
+  </StackLayout>
+</ContentPage>

src/Controls/tests/Xaml.UnitTests/Issues/MauiXmlnsDef.xaml.cs

@@ -0,0 +1,43 @@
+using Microsoft.Maui.ApplicationModel;
+using Microsoft.Maui.Controls.Core.UnitTests;
+using Microsoft.Maui.Dispatching;
+
+using Microsoft.Maui.UnitTests;
+using NUnit.Framework;
+
+
+namespace Microsoft.Maui.Controls.Xaml.UnitTests;
+[XamlCompilation(XamlCompilationOptions.Skip)]
+public partial class MauiXmlnsDef
+{
+	public MauiXmlnsDef()
+	{
+		InitializeComponent();
+	}
+
+	public MauiXmlnsDef(bool useCompiledXaml)
+	{
+		//this stub will be replaced at compile time
+	}
+
+	[TestFixture]
+	class Test
+	{
+		[SetUp]
+		public void Setup()
+		{
+			Application.SetCurrentApplication(new MockApplication());
+			DispatcherProvider.SetCurrent(new DispatcherProviderStub());
+		}
+
+		[TearDown] public void TearDown() => AppInfo.SetCurrent(null);
+
+		[Test]
+		public void XamlParseXmlnsDefinitionForThisAssembly([Values(false, true)] bool useCompiledXaml)
+		{
+			if (useCompiledXaml)
+				MockCompiler.Compile(typeof(MauiXmlnsDef));
+			new MauiXmlnsDef(useCompiledXaml);
+		}
+	}
+}

src/Controls/tests/Xaml.UnitTests/Issues/MauiXmlnsDefControl.cs

@@ -0,0 +1,6 @@
+using Microsoft.Maui.Controls;
+
+[assembly: XmlnsDefinition("http://schemas.microsoft.com/dotnet/2021/maui", "Microsoft.Maui.Controls.Xaml.UnitTests.XmlnsDef")]
+
+namespace Microsoft.Maui.Controls.Xaml.UnitTests.XmlnsDef;
+public class MauiXmlnsDefControl : Label { }