feat: Add support for x:Name hot reload

Author: jeromelaban

src/Uno.UI.Tests/Windows_UI_Xaml_Markup/XamlReaderTests/Given_XamlReader.cs

@@ -1000,6 +1000,30 @@ public void When_ThemeResource_And_Setter_And_Theme_Changed()
 
 		}
 
+		[TestMethod]
+		public void When_xName_Reload()
+		{
+			var s = GetContent(nameof(When_xName_Reload));
+			var SUT = new When_xName_Reload();
+			Windows.UI.Xaml.Markup.XamlReader.LoadUsingComponent(s, SUT);
+
+			var Button1_field_private = SUT.FindName("Button1_field_private") as Button;
+			Assert.IsNotNull(Button1_field_private);
+			Assert.AreEqual(Button1_field_private, SUT.Button1_field_private_Getter);
+
+			var Button1_field_public = SUT.FindName("Button1_field_public") as Button;
+			Assert.IsNotNull(Button1_field_public);
+			Assert.AreEqual(Button1_field_public, SUT.Button1_field_public);
+
+			var Button2_property_private = SUT.FindName("Button2_property_private") as Button;
+			Assert.IsNotNull(Button2_property_private);
+			Assert.AreEqual(Button2_property_private, SUT.Button2_property_private_Getter);
+
+			var Button2_property_public = SUT.FindName("Button2_property_public") as Button;
+			Assert.IsNotNull(Button2_property_public);
+			Assert.AreEqual(Button2_property_public, SUT.Button2_property_public);
+		}
+
 		private string GetContent(string testName)
 		{
 			var assembly = this.GetType().Assembly;

src/Uno.UI.Tests/Windows_UI_Xaml_Markup/XamlReaderTests/When_xName_Reload.cs

@@ -0,0 +1,22 @@
+using System;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+
+namespace Uno.UI.Tests.Windows_UI_Xaml_Markup.XamlReaderTests
+{
+	public partial class When_xName_Reload : UserControl
+	{
+#pragma warning disable 649
+		private Button Button1_field_private;
+
+		public Button Button1_field_public;
+
+		private Button Button2_property_private { get; set; }
+
+		public Button Button2_property_public { get; set; }
+
+
+		public Button Button2_property_private_Getter => Button2_property_private;
+		public Button Button1_field_private_Getter => Button1_field_private;
+	}
+}

src/Uno.UI.Tests/Windows_UI_Xaml_Markup/XamlReaderTests/When_xName_Reload.xamltest

@@ -0,0 +1,12 @@
+<UserControl
+	x:Class="Uno.UI.Tests.Windows_UI_Xaml_Markup.XamlReaderTests.When_xName_Reload"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+>
+	<StackPanel >
+	  <Button x:Name="Button1_field_private" Content="Button 1" />
+	  <Button x:Name="Button2_property_private" Content="Button 2" />
+	  <Button x:Name="Button1_field_public" Content="Button 1" />
+	  <Button x:Name="Button2_property_public" Content="Button 2" />
+	</StackPanel>
+</UserControl>

src/Uno.UI/UI/Xaml/Markup/Reader/XamlObjectBuilder.cs

@@ -248,7 +248,11 @@ private string RewriteAttachedPropertyPath(string? value)
 			return value;
 		}
 
-		private void ProcessNamedMember(XamlObjectDefinition control, object instance, XamlMemberDefinition member, object rootInstance)
+		private void ProcessNamedMember(
+			XamlObjectDefinition control,
+			object instance,
+			XamlMemberDefinition member,
+			object rootInstance)
 		{
 			// Exclude attached properties, must be set in the extended apply section.
 			// If there is no type attached, this can be a binding.
@@ -356,6 +360,22 @@ private void ProcessNamedMember(XamlObjectDefinition control, object instance, X
 				{
 					GetPropertySetter(nameInfo).Invoke(instance, new[] { member.Value });
 				}
+
+				// Update x:Name generated fields, if any
+				if (rootInstance != null && member.Value is string nameValue)
+				{
+					var allMembers = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic;
+					var rootInstanceType = rootInstance.GetType();
+
+					if (TypeResolver.GetPropertyByName(rootInstanceType, nameValue, allMembers) is { } xNameProperty)
+					{
+						GetPropertySetter(xNameProperty).Invoke(rootInstance, new[] { instance });
+					}
+					else if (TypeResolver.GetFieldByName(rootInstanceType, nameValue, allMembers) is { } xNameField)
+					{
+						xNameField.SetValue(rootInstance, instance);
+					}
+				}
 			}
 		}
 

src/Uno.UI/UI/Xaml/Markup/Reader/XamlTypeResolver.cs

@@ -103,14 +103,26 @@ public bool IsInitializedCollection(PropertyInfo property)
             return false;
         }
 
-        public PropertyInfo? GetPropertyByName(XamlType declaringType, string propertyName) 
-            => GetPropertyByName(FindType(declaringType), propertyName);
+		public PropertyInfo? GetPropertyByName(XamlType declaringType, string propertyName, BindingFlags? flags = null)
+			=> GetPropertyByName(FindType(declaringType), propertyName, flags);
 
-        public PropertyInfo? FindContentProperty(Type? elementType)
+		public FieldInfo? GetFieldByName(XamlType declaringType, string propertyName, BindingFlags? flags = null)
+			=> GetFieldByName(FindType(declaringType), propertyName, flags);
+
+		public PropertyInfo? FindContentProperty(Type? elementType)
             => _findContentProperty(elementType);
 
-        private static PropertyInfo? GetPropertyByName(Type? type, string propertyName) 
-            => type?.GetProperties().FirstOrDefault(p => p.Name == propertyName);
+		public PropertyInfo? GetPropertyByName(Type? type, string propertyName, BindingFlags? flags = null)
+			=> (flags != null
+				? type?.GetProperties(flags.Value)
+				: type?.GetProperties()
+			).FirstOrDefault(p => p.Name == propertyName);
+
+		public FieldInfo? GetFieldByName(Type? type, string propertyName, BindingFlags? flags = null)
+			=> (flags != null
+				? type?.GetFields(flags.Value)
+				: type?.GetFields()
+			).FirstOrDefault(p => p.Name == propertyName);
 
 		public EventInfo? GetEventByName(XamlType declaringType, string eventName)
 			=> GetEventByName(FindType(declaringType), eventName);