[X] resolve event handlers in base generic types (#6194)

* [XamlC] fix Debug harness generation code

* [X] resolve event handlers in base generic types

- fixes #6176

Xamarin.Forms.Build.Tasks/CreateObjectVisitor.cs

@@ -96,10 +96,10 @@ namespace Xamarin.Forms.Build.Tasks
 			MethodDefinition ctorInfo = null;
 
 			if (node.Properties.ContainsKey(XmlName.xArguments) && !node.Properties.ContainsKey(XmlName.xFactoryMethod)) {
-				factoryCtorInfo = typedef.AllMethods().FirstOrDefault(md => md.IsConstructor &&
-																			!md.IsStatic &&
-																			md.HasParameters &&
-																			md.MatchXArguments(node, typeref, Module, Context));
+				factoryCtorInfo = typedef.AllMethods().FirstOrDefault(md => md.methodDef.IsConstructor &&
+																			!md.methodDef.IsStatic &&
+																			md.methodDef.HasParameters &&
+																			md.methodDef.MatchXArguments(node, typeref, Module, Context)).methodDef;
 				if (factoryCtorInfo == null) {
 					throw new XamlParseException(
 						string.Format("No constructors found for {0} with matching x:Arguments", typedef.FullName), node);
@@ -109,10 +109,10 @@ namespace Xamarin.Forms.Build.Tasks
 					Context.IL.Append(PushCtorXArguments(factoryCtorInfo.ResolveGenericParameters(typeref, Module), node));
 			} else if (node.Properties.ContainsKey(XmlName.xFactoryMethod)) {
 				var factoryMethod = (string)(node.Properties [XmlName.xFactoryMethod] as ValueNode).Value;
-				factoryMethodInfo = typedef.AllMethods().FirstOrDefault(md => !md.IsConstructor &&
-																			  md.Name == factoryMethod &&
-																			  md.IsStatic &&
-																			  md.MatchXArguments(node, typeref, Module, Context));
+				factoryMethodInfo = typedef.AllMethods().FirstOrDefault(md => !md.methodDef.IsConstructor &&
+																			  md.methodDef.Name == factoryMethod &&
+																			  md.methodDef.IsStatic &&
+																			  md.methodDef.MatchXArguments(node, typeref, Module, Context)).methodDef;
 				if (factoryMethodInfo == null) {
 					throw new XamlParseException(
 						String.Format("No static method found for {0}::{1} ({2})", typedef.FullName, factoryMethod, null), node);

Xamarin.Forms.Build.Tasks/DebugXamlCTask.cs

@@ -113,8 +113,9 @@ namespace Xamarin.Forms.Build.Tasks
 						var br2 = Instruction.Create(OpCodes.Ldarg_0);
 						var ret = Instruction.Create(OpCodes.Ret);
 						il.Emit(OpCodes.Ldarg_0);
-						il.Emit(OpCodes.Callvirt,
-						        module.ImportReference(typeDef.BaseType.Resolve().GetConstructors().First(c => c.HasParameters == false)));
+						var baseCtor = module.ImportReference(typeDef.BaseType.Resolve().GetConstructors().First(c => c.HasParameters == false));
+						baseCtor = module.ImportReference(baseCtor.ResolveGenericParameters(typeDef.BaseType, module));
+						il.Emit(OpCodes.Callvirt, baseCtor);
 
 						il.Emit(OpCodes.Nop);
 						il.Emit(OpCodes.Ldarg_1);

Xamarin.Forms.Build.Tasks/MethodReferenceExtensions.cs

@@ -15,7 +15,7 @@ namespace Xamarin.Forms.Build.Tasks
 
 			var reference = new MethodReference(self.Name, ImportUnresolvedType(self.ReturnType, module))
 			{
-				DeclaringType = module.ImportReference(declaringTypeRef),
+				DeclaringType = declaringTypeRef,
 				HasThis = self.HasThis,
 				ExplicitThis = self.ExplicitThis,
 				CallingConvention = self.CallingConvention

Xamarin.Forms.Build.Tasks/NodeILExtensions.cs

@@ -169,7 +169,7 @@ namespace Xamarin.Forms.Build.Tasks
 						.Methods.FirstOrDefault(md => md.Name == "ConvertFromInvariantString" && md.Parameters.Count == 2)
 					: typeConverter.ResolveCached()
 						.AllMethods()
-						.FirstOrDefault(md => md.Name == "ConvertFromInvariantString" && md.Parameters.Count == 1);
+						.FirstOrDefault(md => md.methodDef.Name == "ConvertFromInvariantString" && md.methodDef.Parameters.Count == 1).methodDef;
 				var convertFromInvariantStringReference = module.ImportReference(convertFromInvariantStringDefinition);
 
 				yield return Instruction.Create(OpCodes.Newobj, typeConverterCtorRef);

Xamarin.Forms.Build.Tasks/SetPropertiesVisitor.cs

@@ -941,31 +941,34 @@ namespace Xamarin.Forms.Build.Tasks
 			while (declaringType.IsNested)
 				declaringType = declaringType.DeclaringType;
 			var handler = declaringType.AllMethods().FirstOrDefault(md => {
-				if (md.Name != value as string)
+				if (md.methodDef.Name != value as string)
 					return false;
 
 				//check if the handler signature matches the Invoke signature;
 				var invoke = module.ImportReference(eventinfo.EventType.ResolveCached().GetMethods().First(eventmd => eventmd.Name == "Invoke"));
 				invoke = invoke.ResolveGenericParameters(eventinfo.EventType, module);
-				if (!md.ReturnType.InheritsFromOrImplements(invoke.ReturnType) || invoke.Parameters.Count != md.Parameters.Count)
+				if (!md.methodDef.ReturnType.InheritsFromOrImplements(invoke.ReturnType) || invoke.Parameters.Count != md.methodDef.Parameters.Count)
 					return false;
 
 				if (!invoke.ContainsGenericParameter)
 					for (var i = 0; i < invoke.Parameters.Count;i++)
-						if (!invoke.Parameters[i].ParameterType.InheritsFromOrImplements(md.Parameters[i].ParameterType))
+						if (!invoke.Parameters[i].ParameterType.InheritsFromOrImplements(md.methodDef.Parameters[i].ParameterType))
 							return false;
 				//TODO check generic parameters if any
 
 				return true;
 			});
-			if (handler == null) 
+			MethodReference handlerRef = null;
+			if (handler.methodDef != null)
+				handlerRef = handler.methodDef.ResolveGenericParameters(handler.declTypeRef, module);
+			if (handler.methodDef == null) 
 				throw new XamlParseException($"EventHandler \"{value}\" with correct signature not found in type \"{declaringType}\"", iXmlLineInfo);
 
 			//FIXME: eventually get the right ctor instead fo the First() one, just in case another one could exists (not even sure it's possible).
 			var ctor = module.ImportReference(eventinfo.EventType.ResolveCached().GetConstructors().First());
 			ctor = ctor.ResolveGenericParameters(eventinfo.EventType, module);
 
-			if (handler.IsStatic) {
+			if (handler.methodDef.IsStatic) {
 				yield return Create(Ldnull);
 			} else {
 				if (context.Root is VariableDefinition)
@@ -978,11 +981,11 @@ namespace Xamarin.Forms.Build.Tasks
 					throw new InvalidProgramException();
 			}
 
-			if (handler.IsVirtual) {
+			if (handler.methodDef.IsVirtual) {
 				yield return Create(Ldarg_0);
-				yield return Create(Ldvirtftn, handler);
+				yield return Create(Ldvirtftn, handlerRef);
 			} else
-				yield return Create(Ldftn, handler);
+				yield return Create(Ldftn, handlerRef);
 
 			yield return Create(Newobj, module.ImportReference(ctor));
 			//Check if the handler has the same signature as the ctor (it should)

Xamarin.Forms.Build.Tasks/TypeDefinitionExtensions.cs

@@ -46,13 +46,14 @@ namespace Xamarin.Forms.Build.Tasks
 			return ctor;
 		}
 
-		public static IEnumerable<MethodDefinition> AllMethods(this TypeDefinition self)
+		public static IEnumerable<(MethodDefinition methodDef, TypeReference declTypeRef)> AllMethods(this TypeDefinition self)
 		{
-			while (self != null)
-			{
+			TypeReference selfTypeRef = self;
+			while (self != null) {
 				foreach (var md in self.Methods)
-					yield return md;
-				self = self.BaseType == null ? null : self.BaseType.ResolveCached();
+					yield return (md, selfTypeRef);
+				selfTypeRef = self.BaseType;
+				self = self.BaseType?.ResolveCached();
 			}
 		}
 	}

Xamarin.Forms.Xaml.UnitTests/Issues/Gh6176.xaml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<local:Gh6176Base
+        xmlns="http://xamarin.com/schemas/2014/forms"
+        xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+        xmlns:local="using:Xamarin.Forms.Xaml.UnitTests"
+        x:Class="Xamarin.Forms.Xaml.UnitTests.Gh6176"
+        x:TypeArguments="local:Gh6176VM">
+    <ContentPage.ToolbarItems>
+        <ToolbarItem Clicked="ShowMenu" />
+    </ContentPage.ToolbarItems>
+</local:Gh6176Base>

Xamarin.Forms.Xaml.UnitTests/Issues/Gh6176.xaml.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Collections.Generic;
+using NUnit.Framework;
+using Xamarin.Forms;
+using Xamarin.Forms.Core.UnitTests;
+
+namespace Xamarin.Forms.Xaml.UnitTests
+{
+	public class Gh6176VM
+	{
+	}
+
+	public class Gh6176Base<TVM> : ContentPage where TVM: class
+	{
+		public TVM ViewModel => BindingContext as TVM;
+		protected void ShowMenu(object sender, EventArgs e) { }
+	}
+
+	public partial class Gh6176
+	{
+		public Gh6176() => InitializeComponent();
+		public Gh6176(bool useCompiledXaml)
+		{
+			//this stub will be replaced at compile time
+		}
+
+		[TestFixture] class Tests
+		{
+			[SetUp] public void Setup() => Device.PlatformServices = new MockPlatformServices();
+			[TearDown] public void TearDown() => Device.PlatformServices = null;
+
+			[Test]
+			public void XamlCDoesntFail([Values(false, true)]bool useCompiledXaml)
+			{
+				var layout = new Gh6176(useCompiledXaml);
+			}
+		}
+	}
+}