[XC] Compile TemplateBindingExtension

src/Controls/src/Build.Tasks/SetPropertiesVisitor.cs

@@ -291,11 +291,19 @@ internal static string GetContentProperty(XamlCache cache, TypeReference typeRef
 				if (!acceptEmptyServiceProvider && requireServiceAttribute == null)
 					context.LoggingHelper.LogWarningOrError(BuildExceptionCode.UnattributedMarkupType, context.XamlFilePath, node.LineNumber, node.LinePosition, 0, 0, vardefref.VariableDefinition.VariableType);
 
-				if (vardefref.VariableDefinition.VariableType.FullName == "Microsoft.Maui.Controls.Xaml.BindingExtension"
-					&& bpRef != null //do not compile bindings if we're not gonna SetBinding
-					)
-					foreach (var instruction in CompileBindingPath(node, context, vardefref.VariableDefinition))
-						yield return instruction;
+				if (bpRef is not null) // do not compile bindings if we're not gonna SetBinding
+				{
+					if (vardefref.VariableDefinition.VariableType.FullName == "Microsoft.Maui.Controls.Xaml.BindingExtension")
+					{
+						foreach (var instruction in CompileBindingPath(node, context, vardefref.VariableDefinition, ("Microsoft.Maui.Controls.Xaml", "Microsoft.Maui.Controls.Xaml", "BindingExtension")))
+							yield return instruction;
+					}
+					else if (vardefref.VariableDefinition.VariableType.FullName == "Microsoft.Maui.Controls.Xaml.TemplateBindingExtension")
+					{
+						foreach (var instruction in CompileBindingPath(node, context, vardefref.VariableDefinition, ("Microsoft.Maui.Controls.Xaml", "Microsoft.Maui.Controls.Xaml", "TemplateBindingExtension")))
+							yield return instruction;
+					}
+				}
 
 				var markExt = markupExtension.ResolveCached(context.Cache);
 				var provideValueInfo = markExt.Methods.First(md => md.Name == "ProvideValue");
@@ -383,7 +391,7 @@ internal static string GetContentProperty(XamlCache cache, TypeReference typeRef
 		}
 
 		//Once we get compiled IValueProvider, this will move to the BindingExpression
-		static IEnumerable<Instruction> CompileBindingPath(ElementNode node, ILContext context, VariableDefinition bindingExt)
+		static IEnumerable<Instruction> CompileBindingPath(ElementNode node, ILContext context, VariableDefinition bindingExt, (string, string, string) bindingExtensionType)
 		{
 			//TODO support casting operators
 			var module = context.Module;
@@ -480,8 +488,6 @@ static IEnumerable<Instruction> CompileBindingPath(ElementNode node, ILContext c
 				   && !md.HasCustomAttributes(module.ImportReference(context.Cache, ("mscorlib", "System", "ObsoleteAttribute")))));
 			var ctorinforef = ctorInfo.MakeGeneric(typedBindingRef, funcRef, actionRef, tupleRef);
 
-			var bindingExtensionType = ("Microsoft.Maui.Controls.Xaml", "Microsoft.Maui.Controls.Xaml", "BindingExtension");
-
 			foreach (var instruction in bindingExt.LoadAs(context.Cache, module.GetTypeDefinition(context.Cache, bindingExtensionType), module))
 				yield return instruction;
 			foreach (var instruction in CompiledBindingGetGetter(tSourceRef, tPropertyRef, properties, node, context))

src/Controls/src/Xaml/MarkupExtensions/TemplateBindingExtension.cs

@@ -1,5 +1,7 @@
 using System;
+using System.ComponentModel;
 using System.Diagnostics.CodeAnalysis;
+using Microsoft.Maui.Controls.Internals;
 
 namespace Microsoft.Maui.Controls.Xaml
 {
@@ -24,17 +26,33 @@ public TemplateBindingExtension()
 
 		public string StringFormat { get; set; }
 
+		[EditorBrowsable(EditorBrowsableState.Never)] public TypedBindingBase TypedBinding { get; set; }
+
 		BindingBase IMarkupExtension<BindingBase>.ProvideValue(IServiceProvider serviceProvider)
 		{
-			return new Binding
+			if (TypedBinding is null)
 			{
-				Source = RelativeBindingSource.TemplatedParent,
-				Path = Path,
-				Mode = Mode,
-				Converter = Converter,
-				ConverterParameter = ConverterParameter,
-				StringFormat = StringFormat
-			};
+#pragma warning disable IL2026 // Using member 'Microsoft.Maui.Controls.Binding.Binding(String, BindingMode, IValueConverter, Object, String, Object)' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. Using bindings with string paths is not trim safe. Use expression-based binding instead.
+				// This code is only reachable in XamlC compiled code when there is a missing x:DataType and the binding could not be compiled.
+				// In that case, we produce a warning that the binding could not be compiled.
+				return new Binding
+				{
+					Source = RelativeBindingSource.TemplatedParent,
+					Path = Path,
+					Mode = Mode,
+					Converter = Converter,
+					ConverterParameter = ConverterParameter,
+					StringFormat = StringFormat
+				};
+#pragma warning restore IL2026
+			}
+
+			TypedBinding.Mode = Mode;
+			TypedBinding.Converter = Converter;
+			TypedBinding.ConverterParameter = ConverterParameter;
+			TypedBinding.StringFormat = StringFormat;
+			TypedBinding.Source = RelativeBindingSource.TemplatedParent;
+			return TypedBinding;
 		}
 
 		object IMarkupExtension.ProvideValue(IServiceProvider serviceProvider)

src/Controls/src/Xaml/PublicAPI/net-android/PublicAPI.Shipped.txt

@@ -27,6 +27,8 @@
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TargetNullValue.set -> void
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TypedBinding.get -> Microsoft.Maui.Controls.Internals.TypedBindingBase
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TypedBinding.set -> void
+~Microsoft.Maui.Controls.Xaml.TemplateBindingExtension.TypedBinding.get -> Microsoft.Maui.Controls.Internals.TypedBindingBase
+~Microsoft.Maui.Controls.Xaml.TemplateBindingExtension.TypedBinding.set -> void
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.UpdateSourceEventName.get -> string
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.UpdateSourceEventName.set -> void
 ~Microsoft.Maui.Controls.Xaml.DataTemplateExtension.ProvideValue(System.IServiceProvider serviceProvider) -> Microsoft.Maui.Controls.DataTemplate

src/Controls/src/Xaml/PublicAPI/net-ios/PublicAPI.Shipped.txt

@@ -27,6 +27,8 @@
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TargetNullValue.set -> void
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TypedBinding.get -> Microsoft.Maui.Controls.Internals.TypedBindingBase
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TypedBinding.set -> void
+~Microsoft.Maui.Controls.Xaml.TemplateBindingExtension.TypedBinding.get -> Microsoft.Maui.Controls.Internals.TypedBindingBase
+~Microsoft.Maui.Controls.Xaml.TemplateBindingExtension.TypedBinding.set -> void
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.UpdateSourceEventName.get -> string
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.UpdateSourceEventName.set -> void
 ~Microsoft.Maui.Controls.Xaml.DataTemplateExtension.ProvideValue(System.IServiceProvider serviceProvider) -> Microsoft.Maui.Controls.DataTemplate

src/Controls/src/Xaml/PublicAPI/net-maccatalyst/PublicAPI.Shipped.txt

@@ -27,6 +27,8 @@
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TargetNullValue.set -> void
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TypedBinding.get -> Microsoft.Maui.Controls.Internals.TypedBindingBase
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TypedBinding.set -> void
+~Microsoft.Maui.Controls.Xaml.TemplateBindingExtension.TypedBinding.get -> Microsoft.Maui.Controls.Internals.TypedBindingBase
+~Microsoft.Maui.Controls.Xaml.TemplateBindingExtension.TypedBinding.set -> void
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.UpdateSourceEventName.get -> string
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.UpdateSourceEventName.set -> void
 ~Microsoft.Maui.Controls.Xaml.DataTemplateExtension.ProvideValue(System.IServiceProvider serviceProvider) -> Microsoft.Maui.Controls.DataTemplate

src/Controls/src/Xaml/PublicAPI/net-tizen/PublicAPI.Shipped.txt

@@ -27,6 +27,8 @@
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TargetNullValue.set -> void
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TypedBinding.get -> Microsoft.Maui.Controls.Internals.TypedBindingBase
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TypedBinding.set -> void
+~Microsoft.Maui.Controls.Xaml.TemplateBindingExtension.TypedBinding.get -> Microsoft.Maui.Controls.Internals.TypedBindingBase
+~Microsoft.Maui.Controls.Xaml.TemplateBindingExtension.TypedBinding.set -> void
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.UpdateSourceEventName.get -> string
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.UpdateSourceEventName.set -> void
 ~Microsoft.Maui.Controls.Xaml.DataTemplateExtension.ProvideValue(System.IServiceProvider serviceProvider) -> Microsoft.Maui.Controls.DataTemplate

src/Controls/src/Xaml/PublicAPI/net-windows/PublicAPI.Shipped.txt

@@ -27,6 +27,8 @@
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TargetNullValue.set -> void
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TypedBinding.get -> Microsoft.Maui.Controls.Internals.TypedBindingBase
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TypedBinding.set -> void
+~Microsoft.Maui.Controls.Xaml.TemplateBindingExtension.TypedBinding.get -> Microsoft.Maui.Controls.Internals.TypedBindingBase
+~Microsoft.Maui.Controls.Xaml.TemplateBindingExtension.TypedBinding.set -> void
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.UpdateSourceEventName.get -> string
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.UpdateSourceEventName.set -> void
 ~Microsoft.Maui.Controls.Xaml.DataTemplateExtension.ProvideValue(System.IServiceProvider serviceProvider) -> Microsoft.Maui.Controls.DataTemplate

src/Controls/src/Xaml/PublicAPI/net/PublicAPI.Shipped.txt

@@ -27,6 +27,8 @@
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TargetNullValue.set -> void
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TypedBinding.get -> Microsoft.Maui.Controls.Internals.TypedBindingBase
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TypedBinding.set -> void
+~Microsoft.Maui.Controls.Xaml.TemplateBindingExtension.TypedBinding.get -> Microsoft.Maui.Controls.Internals.TypedBindingBase
+~Microsoft.Maui.Controls.Xaml.TemplateBindingExtension.TypedBinding.set -> void
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.UpdateSourceEventName.get -> string
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.UpdateSourceEventName.set -> void
 ~Microsoft.Maui.Controls.Xaml.DataTemplateExtension.ProvideValue(System.IServiceProvider serviceProvider) -> Microsoft.Maui.Controls.DataTemplate

src/Controls/src/Xaml/PublicAPI/netstandard/PublicAPI.Shipped.txt

@@ -27,6 +27,8 @@
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TargetNullValue.set -> void
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TypedBinding.get -> Microsoft.Maui.Controls.Internals.TypedBindingBase
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.TypedBinding.set -> void
+~Microsoft.Maui.Controls.Xaml.TemplateBindingExtension.TypedBinding.get -> Microsoft.Maui.Controls.Internals.TypedBindingBase
+~Microsoft.Maui.Controls.Xaml.TemplateBindingExtension.TypedBinding.set -> void
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.UpdateSourceEventName.get -> string
 ~Microsoft.Maui.Controls.Xaml.BindingExtension.UpdateSourceEventName.set -> void
 ~Microsoft.Maui.Controls.Xaml.DataTemplateExtension.ProvideValue(System.IServiceProvider serviceProvider) -> Microsoft.Maui.Controls.DataTemplate

src/Controls/tests/Xaml.UnitTests/TemplateBindingsCompiler.xaml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ContentPage
+		xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+		xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+		xmlns:local="clr-namespace:Microsoft.Maui.Controls.Xaml.UnitTests"
+		x:Class="Microsoft.Maui.Controls.Xaml.UnitTests.TemplateBindingsCompiler" >
+	<ContentPage.Resources>
+		<ControlTemplate x:Key="MyCardTemplate">
+			<Label
+				x:Name="CardTitleLabel"
+				Text="{TemplateBinding CardTitle, x:DataType=local:TemplateBindingCompilerTestCardView}" />
+		</ControlTemplate>
+	</ContentPage.Resources>
+
+	<local:TemplateBindingCompilerTestCardView
+		x:Name="ContentView"
+		CardTitle="The title"
+		ControlTemplate="{StaticResource MyCardTemplate}" />
+</ContentPage>

src/Controls/tests/Xaml.UnitTests/TemplateBindingsCompiler.xaml.cs

@@ -0,0 +1,61 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Diagnostics;
+using System.Runtime.CompilerServices;
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Controls.Core.UnitTests;
+using Microsoft.Maui.Controls.Internals;
+using Microsoft.Maui.Dispatching;
+using Microsoft.Maui.UnitTests;
+using NUnit.Framework;
+
+namespace Microsoft.Maui.Controls.Xaml.UnitTests
+{
+	public partial class TemplateBindingsCompiler : ContentPage
+	{
+		public TemplateBindingsCompiler()
+		{
+			InitializeComponent();
+		}
+
+		public TemplateBindingsCompiler(bool useCompiledXaml)
+		{
+			//this stub will be replaced at compile time
+		}
+
+		[TestFixture]
+		public class Tests
+		{
+			[SetUp] public void Setup() => DispatcherProvider.SetCurrent(new DispatcherProviderStub());
+			[TearDown] public void TearDown() => DispatcherProvider.SetCurrent(null);
+
+			[TestCase(false)]
+			[TestCase(true)]
+			public void Test(bool useCompiledXaml)
+			{
+				var page = new TemplateBindingsCompiler(useCompiledXaml);
+				var label = (Label)page.ContentView.GetTemplateChild("CardTitleLabel");
+				Assert.AreEqual("The title", label?.Text);
+
+				if (useCompiledXaml)
+				{
+					var binding = label.GetContext(Label.TextProperty).Bindings.GetValue();
+					Assert.That(binding, Is.TypeOf<TypedBinding<TemplateBindingCompilerTestCardView, string>>());
+				}
+			}
+		}
+	}
+
+	public class TemplateBindingCompilerTestCardView : ContentView
+	{
+		public static readonly BindableProperty CardTitleProperty =
+			BindableProperty.Create(nameof(CardTitle), typeof(string), typeof(TemplateBindingCompilerTestCardView), string.Empty);
+
+		public string CardTitle
+		{
+			get => (string)GetValue(CardTitleProperty);
+			set => SetValue(CardTitleProperty, value);
+		}
+	}
+}