[X] send tree changed events on parenting (#8760)

so thye will be triggered in all cases

Xamarin.Forms.Build.Tasks/SetPropertiesVisitor.cs

@@ -931,7 +931,7 @@ namespace Xamarin.Forms.Build.Tasks
 			yield return Create(Ldc_I4, lineInfo.LineNumber);				//lineNumber
 			yield return Create(Ldc_I4, lineInfo.LinePosition);             //linePosition
 
-			yield return Create(Call, module.ImportMethodReference(("Xamarin.Forms.Xaml", "Xamarin.Forms.Xaml.Diagnostics", "VisualDiagnostics"),
+			yield return Create(Call, module.ImportMethodReference(("Xamarin.Forms.Core", "Xamarin.Forms.Xaml.Diagnostics", "VisualDiagnostics"),
 																   methodName: "RegisterSourceInfo",
 																   parameterTypes: new[] {
 																	   ("mscorlib", "System", "Object"),

Xamarin.Forms.Core/Element.cs

@@ -5,6 +5,7 @@ using System.Collections.Specialized;
 using System.ComponentModel;
 using System.Runtime.CompilerServices;
 using Xamarin.Forms.Internals;
+using Xamarin.Forms.Xaml.Diagnostics;
 
 namespace Xamarin.Forms
 {
@@ -200,6 +201,8 @@ namespace Xamarin.Forms
 					SetInheritedBindingContext(this, null);
 				}
 
+				VisualDiagnostics.SendVisualTreeChanged(this, value);
+
 				OnParentSet();
 
 				OnPropertyChanged();

Xamarin.Forms.Core/Xamarin.Forms.Core.csproj

@@ -20,6 +20,9 @@
 		<PackageReference Include="System.Dynamic.Runtime" Version="4.3.0" />
 		<PackageReference Include="System.ValueTuple" Version="4.5.0" />
 	</ItemGroup>	
+	<ItemGroup>
+	  <Folder Include="Xaml\Diagnostics\" />
+	</ItemGroup>
 	<PropertyGroup>
     <GitInfoReportImportance>high</GitInfoReportImportance>
   </PropertyGroup>

Xamarin.Forms.Core/Xaml/Diagnostics/VisualDiagnostics.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
+
 using System;
 using System.ComponentModel;
 using System.Runtime.CompilerServices;
@@ -28,43 +29,6 @@ namespace Xamarin.Forms.Xaml.Diagnostics
 		public static XamlSourceInfo GetXamlSourceInfo(object obj) => sourceInfos.TryGetValue(obj, out var sourceinfo) ? sourceinfo : null;
 	}
 
-	public class XamlSourceInfo
-	{
-		public XamlSourceInfo(Uri sourceUri, int lineNumber, int linePosition)
-		{
-			SourceUri = sourceUri;
-			LineNumber = lineNumber;
-			LinePosition = linePosition;
-		}
-
-		public Uri SourceUri { get; }
-		public int LineNumber { get; }
-		public int LinePosition { get; }
-
-		public void Deconstruct(out Uri sourceUri, out int lineNumber, out int linePosition)
-		{
-			sourceUri = SourceUri;
-			lineNumber = LineNumber;
-			linePosition = LinePosition;
-		}
-	}
-
-	public class VisualTreeChangeEventArgs : EventArgs
-	{
-		public VisualTreeChangeEventArgs(object parent, object child, int childIndex, VisualTreeChangeType changeType)
-		{
-			Parent = parent;
-			Child = child;
-			ChildIndex = childIndex;
-			ChangeType = changeType;
-		}
-
-		public object Parent { get; }
-		public object Child { get; }
-		public int ChildIndex { get; }
-		public VisualTreeChangeType ChangeType { get; }
-	}
-
 	public enum VisualTreeChangeType
 	{
 		Add = 0,

Xamarin.Forms.Core/Xaml/Diagnostics/VisualTreeChangeEventArgs.cs

@@ -0,0 +1,23 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System;
+
+namespace Xamarin.Forms.Xaml.Diagnostics
+{
+	public class VisualTreeChangeEventArgs : EventArgs
+	{
+		public VisualTreeChangeEventArgs(object parent, object child, int childIndex, VisualTreeChangeType changeType)
+		{
+			Parent = parent;
+			Child = child;
+			ChildIndex = childIndex;
+			ChangeType = changeType;
+		}
+
+		public object Parent { get; }
+		public object Child { get; }
+		public int ChildIndex { get; }
+		public VisualTreeChangeType ChangeType { get; }
+	}
+}

Xamarin.Forms.Core/Xaml/Diagnostics/XamlSourceInfo.cs

@@ -0,0 +1,28 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System;
+
+namespace Xamarin.Forms.Xaml.Diagnostics
+{
+	public class XamlSourceInfo
+	{
+		public XamlSourceInfo(Uri sourceUri, int lineNumber, int linePosition)
+		{
+			SourceUri = sourceUri;
+			LineNumber = lineNumber;
+			LinePosition = linePosition;
+		}
+
+		public Uri SourceUri { get; }
+		public int LineNumber { get; }
+		public int LinePosition { get; }
+
+		public void Deconstruct(out Uri sourceUri, out int lineNumber, out int linePosition)
+		{
+			sourceUri = SourceUri;
+			lineNumber = LineNumber;
+			linePosition = LinePosition;
+		}
+	}
+}

Xamarin.Forms.Xaml/ApplyPropertiesVisitor.cs

@@ -346,28 +346,22 @@ namespace Xamarin.Forms.Xaml
 
 			//If it's a BindableProberty, SetValue
 			if (xpe == null && TrySetValue(xamlelement, property, attached, value, lineInfo, serviceProvider, out xpe)) {
-				if (!(node is ValueNode) && value != null && !value.GetType().GetTypeInfo().IsValueType && XamlFilePathAttribute.GetFilePathForObject(context.RootElement) is string path) {
+				if (!(node is ValueNode) && value != null && !value.GetType().GetTypeInfo().IsValueType && XamlFilePathAttribute.GetFilePathForObject(context.RootElement) is string path)
 					VisualDiagnostics.RegisterSourceInfo(value, new Uri(path, UriKind.Relative), ((IXmlLineInfo)node).LineNumber, ((IXmlLineInfo)node).LinePosition);
-					VisualDiagnostics.SendVisualTreeChanged(xamlelement, value);
-				}
 				return;
 			}
 
 			//If we can assign that value to a normal property, let's do it
 			if (xpe == null && TrySetProperty(xamlelement, localName, value, lineInfo, serviceProvider, context, out xpe)) {
-				if (!(node is ValueNode) && value != null && !value.GetType().GetTypeInfo().IsValueType && XamlFilePathAttribute.GetFilePathForObject(context.RootElement) is string path) {
+				if (!(node is ValueNode) && value != null && !value.GetType().GetTypeInfo().IsValueType && XamlFilePathAttribute.GetFilePathForObject(context.RootElement) is string path)
 					VisualDiagnostics.RegisterSourceInfo(value, new Uri(path, UriKind.Relative), ((IXmlLineInfo)node).LineNumber, ((IXmlLineInfo)node).LinePosition);
-					VisualDiagnostics.SendVisualTreeChanged(xamlelement, value);
-				}
 				return;
 			}
 
 			//If it's an already initialized property, add to it
 			if (xpe == null && TryAddToProperty(xamlelement, propertyName, value, xKey, lineInfo, serviceProvider, context, out xpe)) {
-				if (!(node is ValueNode) && value != null && !value.GetType().GetTypeInfo().IsValueType && XamlFilePathAttribute.GetFilePathForObject(context.RootElement) is string path) {
+				if (!(node is ValueNode) && value != null && !value.GetType().GetTypeInfo().IsValueType && XamlFilePathAttribute.GetFilePathForObject(context.RootElement) is string path)
 					VisualDiagnostics.RegisterSourceInfo(value, new Uri(path, UriKind.Relative), ((IXmlLineInfo)node).LineNumber, ((IXmlLineInfo)node).LinePosition);
-					VisualDiagnostics.SendVisualTreeChanged(xamlelement, value);
-				}
 				return;
 			}
 

Xamarin.Forms.Xaml/Properties/AssemblyInfo.cs

@@ -23,3 +23,8 @@ using Xamarin.Forms.Internals;
 #pragma warning disable CS0612 // Type or member is obsolete
 [assembly: TypeForwardedTo(typeof(Xamarin.Forms.Xaml.Internals.INameScopeProvider))]
 #pragma warning restore CS0612 // Type or member is obsolete
+
+[assembly: TypeForwardedTo(typeof(Xamarin.Forms.Xaml.Diagnostics.DebuggerHelper))]
+[assembly: TypeForwardedTo(typeof(Xamarin.Forms.Xaml.Diagnostics.VisualDiagnostics))]
+[assembly: TypeForwardedTo(typeof(Xamarin.Forms.Xaml.Diagnostics.VisualTreeChangeEventArgs))]
+[assembly: TypeForwardedTo(typeof(Xamarin.Forms.Xaml.Diagnostics.XamlSourceInfo))]