Fixed TemplatedParent issue

src/Markup/Avalonia.Markup.Xaml/Avalonia.Markup.Xaml.csproj

@@ -55,6 +55,7 @@
         <Compile Include="Templates\TemplateLoader.cs" />
         <Compile Include="Templates\TreeDataTemplate.cs" />
         <Compile Include="XamlIl\AvaloniaXamlIlRuntimeCompiler.cs" />
+        <Compile Include="XamlIl\CompilerExtensions\Transformers\AvaloniaBindingExtensionHackTransformer.cs" />
         <Compile Include="XamlIl\CompilerExtensions\Transformers\AvaloniaXamlIlAvaloniaPropertyResolver.cs" />
         <Compile Include="XamlIl\CompilerExtensions\Transformers\AvaloniaXamlIlConstructorServiceProviderTransformer.cs" />
         <Compile Include="XamlIl\CompilerExtensions\Transformers\AvaloniaXamlIlControlTemplateTargetTypeMetadataTransformer.cs" />

src/Markup/Avalonia.Markup.Xaml/XamlIl/CompilerExtensions/AvaloniaXamlIlCompiler.cs

@@ -32,6 +32,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
             Transformers.Insert(0, new XNameTransformer());
             Transformers.Insert(1, new IgnoredDirectivesTransformer());
             Transformers.Insert(2, _designTransformer = new AvaloniaXamlIlDesignPropertiesTransformer());
+            Transformers.Insert(3, new AvaloniaBindingExtensionHackTransformer());
             
             
             // Targeted

src/Markup/Avalonia.Markup.Xaml/XamlIl/CompilerExtensions/Transformers/AvaloniaBindingExtensionHackTransformer.cs

@@ -0,0 +1,20 @@
+using XamlIl.Ast;
+using XamlIl.Transform;
+
+namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
+{
+    class AvaloniaBindingExtensionHackTransformer : IXamlIlAstTransformer
+    {
+        public IXamlIlAstNode Transform(XamlIlAstTransformationContext context, IXamlIlAstNode node)
+        {
+            // Our code base expects XAML parser to prefer `FooExtension` to `Foo` even with `<Foo>` syntax
+            // This is the legacy of Portable.Xaml, so we emulate that behavior here
+
+            if (node is XamlIlAstXmlTypeReference tref
+                && tref.Name == "Binding"
+                && tref.XmlNamespace == "https://github.com/avaloniaui")
+                tref.IsMarkupExtension = true;
+            return node;
+        }
+    }
+}

src/Markup/Avalonia.Markup.Xaml/XamlIl/CompilerExtensions/Transformers/AvaloniaXamlIlAvaloniaPropertyResolver.cs

@@ -4,7 +4,7 @@ using XamlIl.Transform;
 
 namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
 {
-    public class AvaloniaXamlIlAvaloniaPropertyResolver : IXamlIlAstTransformer
+    class AvaloniaXamlIlAvaloniaPropertyResolver : IXamlIlAstTransformer
     {
         public IXamlIlAstNode Transform(XamlIlAstTransformationContext context, IXamlIlAstNode node)
         {

tests/Avalonia.Markup.Xaml.UnitTests/Xaml/XamlIlTests.cs

@@ -114,7 +114,7 @@ namespace Avalonia.Markup.Xaml.UnitTests
                     .VisualChildren.First()
                     .VisualChildren.First()
                     .VisualChildren.First();
-                Assert.Equal(Brushes.Red, canvas.Background);
+                Assert.Equal(Brushes.Red.Color, ((ISolidColorBrush)canvas.Background).Color);
             }
         }
     }
@@ -123,7 +123,7 @@ namespace Avalonia.Markup.Xaml.UnitTests
     {
         public object Convert(IList<object> values, Type targetType, object parameter, CultureInfo culture)
         {
-            return ((ISolidColorBrush)values[0]).Color;
+            return (values[0] as ISolidColorBrush)?.Color;
         }
     }