Make SourceMode internal since it doesn't need to be public.

src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/CompiledBindingExtension.cs

@@ -1,13 +1,10 @@
-extern alias Markup;
-using System;
+using System;
 using Avalonia.Data;
 using Avalonia.Controls;
 using Avalonia.Styling;
 using Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings;
 using Avalonia.Data.Core;
-
-using SourceMode = Markup::Avalonia.Markup.Parsers.SourceMode;
-using Avalonia.Data.Converters;
+using Avalonia.Markup.Parsers;
 
 namespace Avalonia.Markup.Xaml.MarkupExtensions
 {

src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/CompiledBindings/CompiledBindingPath.cs

@@ -1,10 +1,9 @@
-extern alias Markup;
-using System;
+using System;
 using System.Collections.Generic;
 using Avalonia.Data.Core;
 using Avalonia.Data.Core.Plugins;
+using Avalonia.Markup.Parsers;
 using Avalonia.Markup.Parsers.Nodes;
-using SourceMode = Markup::Avalonia.Markup.Parsers.SourceMode;
 
 namespace Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings
 {
@@ -56,7 +55,7 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings
             return pathRoot ?? new EmptyExpressionNode();
         }
 
-        public SourceMode SourceMode => _elements.Count > 0 && _elements[0] is IControlSourceBindingPathElement ? SourceMode.Control : SourceMode.Data;
+        internal SourceMode SourceMode => _elements.Count > 0 && _elements[0] is IControlSourceBindingPathElement ? SourceMode.Control : SourceMode.Data;
     }
 
     public class CompiledBindingPathBuilder

src/Markup/Avalonia.Markup/Markup/Parsers/BindingExpressionGrammar.cs

@@ -8,7 +8,7 @@ using System.Collections.Generic;
 
 namespace Avalonia.Markup.Parsers
 {
-    public enum SourceMode
+    internal enum SourceMode
     {
         Data,
         Control