almost working relative panel.

src/Avalonia.Controls/RelativePanel.AttachedProperties.cs

@@ -43,6 +43,7 @@ namespace Avalonia.Controls
         /// The RelativePanel.Above XAML attached property value of the specified object.
         /// (The element to position this element above.)
         /// </returns>        
+        [ResolveByName]
         public static object GetAbove(AvaloniaObject obj)
         {
             return (object)obj.GetValue(AboveProperty);
@@ -62,7 +63,7 @@ namespace Avalonia.Controls
         /// <summary>
         ///  Identifies the <see cref="RelativePanel.AboveProperty"/> XAML attached property.
         /// </summary>        
-        [ResolveByName]
+        
         public static readonly AttachedProperty<object> AboveProperty =
             AvaloniaProperty.RegisterAttached<Layoutable, object>("Above", typeof(RelativePanel));
 
@@ -108,6 +109,7 @@ namespace Avalonia.Controls
         /// The RelativePanel.AlignBottomWith XAML attached property value of the specified object.
         /// (The element to align this element's bottom edge with.)
         /// </returns>        
+        [ResolveByName]
         public static object GetAlignBottomWith(AvaloniaObject obj)
         {
             return (object)obj.GetValue(AlignBottomWithProperty);
@@ -126,7 +128,7 @@ namespace Avalonia.Controls
         /// <summary>
         ///  Identifies the <see cref="RelativePanel.AlignBottomWithProperty"/> XAML attached property.
         /// </summary>
-        [ResolveByName]
+        
         public static readonly AttachedProperty<object> AlignBottomWithProperty =
             AvaloniaProperty.RegisterAttached<Layoutable, object>("AlignBottomWith", typeof(RelativePanel));
 
@@ -171,6 +173,7 @@ namespace Avalonia.Controls
         /// The RelativePanel.AlignHorizontalCenterWith XAML attached property value of the
         /// specified object. (The element to align this element's horizontal center with.)
         /// </returns>        
+        [ResolveByName]
         public static object GetAlignHorizontalCenterWith(AvaloniaObject obj)
         {
             return (object)obj.GetValue(AlignHorizontalCenterWithProperty);
@@ -189,7 +192,7 @@ namespace Avalonia.Controls
         /// <summary>
         ///  Identifies the <see cref="RelativePanel.AlignHorizontalCenterWithProperty"/> XAML attached property.
         /// </summary>
-        [ResolveByName]
+        
         public static readonly AttachedProperty<object> AlignHorizontalCenterWithProperty =
             AvaloniaProperty.RegisterAttached<Layoutable, object>("AlignHorizontalCenterWith", typeof(object), typeof(RelativePanel));
 
@@ -235,6 +238,7 @@ namespace Avalonia.Controls
         /// The RelativePanel.AlignLeftWith XAML attached property value of the specified
         /// object. (The element to align this element's left edge with.)
         /// </returns>        
+        [ResolveByName]
         public static object GetAlignLeftWith(AvaloniaObject obj)
         {
             return (object)obj.GetValue(AlignLeftWithProperty);
@@ -253,7 +257,7 @@ namespace Avalonia.Controls
         /// <summary>
         ///  Identifies the <see cref="RelativePanel.AlignLeftWithProperty"/> XAML attached property.
         /// </summary>
-        [ResolveByName]
+        
         public static readonly AttachedProperty<object> AlignLeftWithProperty =
             AvaloniaProperty.RegisterAttached<RelativePanel, Layoutable, object>("AlignLeftWith");
 
@@ -299,6 +303,7 @@ namespace Avalonia.Controls
         /// The RelativePanel.AlignRightWith XAML attached property value of the specified
         /// object. (The element to align this element's right edge with.)
         /// </returns>        
+        [ResolveByName]
         public static object GetAlignRightWith(AvaloniaObject obj)
         {
             return (object)obj.GetValue(AlignRightWithProperty);
@@ -317,7 +322,7 @@ namespace Avalonia.Controls
         /// <summary>
         ///  Identifies the <see cref="RelativePanel.AlignRightWithProperty"/> XAML attached property.
         /// </summary>
-        [ResolveByName]
+        
         public static readonly AttachedProperty<object> AlignRightWithProperty =
             AvaloniaProperty.RegisterAttached<RelativePanel, Layoutable, object>("AlignRightWith");
 
@@ -359,6 +364,7 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="obj">The object from which the property value is read.</param>
         /// <returns>The value to set. (The element to align this element's top edge with.)</returns>        
+        [ResolveByName]
         public static object GetAlignTopWith(AvaloniaObject obj)
         {
             return (object)obj.GetValue(AlignTopWithProperty);
@@ -377,7 +383,7 @@ namespace Avalonia.Controls
         /// <summary>
         ///  Identifies the <see cref="RelativePanel.AlignTopWithProperty"/> XAML attached property.
         /// </summary>
-        [ResolveByName]
+        
         public static readonly AttachedProperty<object> AlignTopWithProperty =
             AvaloniaProperty.RegisterAttached<RelativePanel, Layoutable, object>("AlignTopWith");
 
@@ -419,6 +425,7 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="obj">The object from which the property value is read.</param>
         /// <returns>The value to set. (The element to align this element's vertical center with.)</returns>        
+        [ResolveByName]
         public static object GetAlignVerticalCenterWith(AvaloniaObject obj)
         {
             return (object)obj.GetValue(AlignVerticalCenterWithProperty);
@@ -429,7 +436,7 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="obj">The object to which the property value is written.</param>
         /// <param name="value">The value to set. (The element to align this element's horizontal center with.)</param>        
-        [ResolveByName]
+        
         public static void SetAlignVerticalCenterWith(AvaloniaObject obj, object value)
         {
             obj.SetValue(AlignVerticalCenterWithProperty, value);
@@ -448,7 +455,8 @@ namespace Avalonia.Controls
         /// <returns>
         /// The RelativePanel.Below XAML attached property value of the specified object.
         /// (The element to position this element below.)                                
-        /// </returns>        
+        /// </returns>       
+        [ResolveByName]
         public static object GetBelow(AvaloniaObject obj)
         {
             return (object)obj.GetValue(BelowProperty);
@@ -459,6 +467,7 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="obj">The object to which the property value is written.</param>
         /// <param name="value">The value to set. (The element to position this element below.)</param>
+        
         public static void SetBelow(AvaloniaObject obj, object value)
         {
             obj.SetValue(BelowProperty, value);
@@ -467,7 +476,7 @@ namespace Avalonia.Controls
         /// <summary>
         ///  Identifies the <see cref="RelativePanel.BelowProperty"/> XAML attached property.
         /// </summary>
-        [ResolveByName]
+        
         public static readonly AttachedProperty<object> BelowProperty =
             AvaloniaProperty.RegisterAttached<RelativePanel, Layoutable, object>("Below");
 
@@ -479,6 +488,7 @@ namespace Avalonia.Controls
         /// The RelativePanel.LeftOf XAML attached property value of the specified object.
         /// (The element to position this element to the left of.)                                 
         /// </returns>        
+        [ResolveByName]
         public static object GetLeftOf(AvaloniaObject obj)
         {
             return (object)obj.GetValue(LeftOfProperty);
@@ -497,7 +507,7 @@ namespace Avalonia.Controls
         /// <summary>
         ///  Identifies the <see cref="RelativePanel.LeftOfProperty"/> XAML attached property.
         /// </summary>
-        [ResolveByName]
+        
         public static readonly AttachedProperty<object> LeftOfProperty =
             AvaloniaProperty.RegisterAttached<RelativePanel, Layoutable, object>("LeftOf");
 
@@ -509,6 +519,7 @@ namespace Avalonia.Controls
         /// The RelativePanel.RightOf XAML attached property value of the specified object.
         /// (The element to position this element to the right of.)                                   
         /// </returns>        
+        [ResolveByName]
         public static object GetRightOf(AvaloniaObject obj)
         {
             return (object)obj.GetValue(RightOfProperty);
@@ -527,7 +538,7 @@ namespace Avalonia.Controls
         /// <summary>
         ///  Identifies the <see cref="RelativePanel.RightOfProperty"/> XAML attached property.
         /// </summary>
-        [ResolveByName]
+        
         public static readonly AttachedProperty<object> RightOfProperty =
             AvaloniaProperty.RegisterAttached<RelativePanel, Layoutable, object>("RightOf");
     }

src/Avalonia.Controls/RelativePanel.cs

@@ -410,6 +410,7 @@ namespace Avalonia.Controls
         private Layoutable GetDependencyElement(AvaloniaProperty property, AvaloniaObject child)
         {
             var dependency = child.GetValue(property);
+                        
             if (dependency == null)
                 return null;
             if (dependency is Layoutable)
@@ -419,6 +420,7 @@ namespace Avalonia.Controls
                 throw new ArgumentException(string.Format("RelativePanel error: Element does not exist in the current context", property.Name));
             }
 
+            return null;
             throw new ArgumentException("RelativePanel error: Value must be of type ILayoutable");
         }
     }

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

@@ -4,8 +4,13 @@ using Avalonia.Controls;
 namespace Avalonia.Markup.Xaml.MarkupExtensions
 {
     public class ResolveByNameExtension
-    {   
-        public string Name { get; set; }
+    {
+        public ResolveByNameExtension(string name)
+        {
+            Name = name;
+        }
+
+        public string Name { get; }
 
         public object ProvideValue(IServiceProvider serviceProvider)
         {

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

@@ -1,6 +1,9 @@
-using System.Linq;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
 using XamlX.Ast;
 using XamlX.Transform;
+using XamlX.TypeSystem;
 
 namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
 {
@@ -10,24 +13,35 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
         {
             if (node is XamlAstXamlPropertyValueNode propertyValueNode)
             {
-                foreach(var attribute in propertyValueNode.Property.GetClrProperty().CustomAttributes)
+
+                IEnumerable<IXamlCustomAttribute> attributes = propertyValueNode.Property.GetClrProperty().CustomAttributes;
+
+                if (propertyValueNode.Property is XamlAstClrProperty referenceNode &&
+                    referenceNode.Getter != null)
+                {
+                    attributes = attributes.Concat(referenceNode.Getter.CustomAttributes);
+                }
+
+                foreach (var attribute in attributes)
                 {
                     if (attribute.Type.FullName == "Avalonia.Controls.ResolveByNameAttribute")
                     {
                         if (propertyValueNode.Values.Count == 1 &&
                             propertyValueNode.Values.First() is XamlAstTextNode)
                         {
-                            propertyValueNode.Values[0] =
-                                new XamlAstObjectNode(
+                            if (XamlTransformHelpers.TryConvertMarkupExtension(context, new XamlAstObjectNode(
                                     propertyValueNode.Values[0],
                                     new XamlAstClrTypeReference(propertyValueNode.Values[0],
                                     context.GetAvaloniaTypes().ResolveByNameExtension, true))
-                                {
-                                    Arguments = new System.Collections.Generic.List<IXamlAstValueNode>
+                            {
+                                Arguments = new System.Collections.Generic.List<IXamlAstValueNode>
                                     {
                                         propertyValueNode.Values[0]
                                     }
-                                };
+                            }, out var extensionNode))
+                            {
+                                propertyValueNode.Values[0] = extensionNode;
+                            }
                         }
                         break;
                     }

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

@@ -174,6 +174,9 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
                     other is GetterMethod m && m.Name == Name && m.DeclaringType.Equals(DeclaringType);
                 public IXamlType ReturnType => Parent.PropertyType;
                 public IReadOnlyList<IXamlType> Parameters { get; }
+
+                public IReadOnlyList<IXamlCustomAttribute> CustomAttributes => DeclaringType.CustomAttributes;
+
                 public void EmitCall(IXamlILEmitter emitter)
                 {
                     var method = Parent._avaloniaObject

src/Markup/Avalonia.Markup.Xaml/XamlIl/xamlil.github

@@ -1 +1 @@
-Subproject commit 0028377ce7c7dc21f9fe71b45f62a95991b1ab58
+Subproject commit 7b8b3013bd42e1992838a525c991f44191da55be