[XamlC] fix the argument match check for events (#4134)

Well, it looks like the order of arguments of InheritOrImplements was
reversed... a totally fine and normal Friday so far

- fixes #4130

Xamarin.Forms.Build.Tasks/SetPropertiesVisitor.cs

@@ -879,8 +879,9 @@ namespace Xamarin.Forms.Build.Tasks
 				throw new XamlParseException($"Signature (number of arguments) of EventHandler \"{context.Body.Method.DeclaringType.FullName}.{value}\" doesn't match the event type", iXmlLineInfo);
 			if (!invoke.ContainsGenericParameter)
 				for (var i = 0; i < invoke.Parameters.Count;i++)
-					if (!handler.Parameters[i].ParameterType.InheritsFromOrImplements(invoke.Parameters[i].ParameterType))
+					if (!invoke.Parameters[i].ParameterType.InheritsFromOrImplements(handler.Parameters[i].ParameterType))
 						throw new XamlParseException($"Signature (parameter {i}) of EventHandler \"{context.Body.Method.DeclaringType.FullName}.{value}\" doesn't match the event type", iXmlLineInfo);
+			//TODO check generic parameters if any
 
 			if (handler.IsVirtual) {
 				yield return Create(Ldarg_0);

Xamarin.Forms.Xaml.UnitTests/Issues/Gh4130.xaml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ContentPage 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.Gh4130">
+	<ContentPage.Content>
+		<local:Gh4130Control TextChanged="OnTextChanged" />
+	</ContentPage.Content>
+</ContentPage>

Xamarin.Forms.Xaml.UnitTests/Issues/Gh4130.xaml.cs

@@ -0,0 +1,64 @@
+using System;
+using System.Collections.Generic;
+using NUnit.Framework;
+using Xamarin.Forms;
+using Xamarin.Forms.Core.UnitTests;
+
+namespace Xamarin.Forms.Xaml.UnitTests
+{
+	public class Gh4130Control:ContentView
+	{
+		public delegate void TextChangedEventHandler(object sender, TextChangedEventArgs args);
+#pragma warning disable 067
+		public event TextChangedEventHandler TextChanged;
+#pragma warning restore 067
+		public void FireEvent()
+		{
+			TextChanged?.Invoke(this, new TextChangedEventArgs(null, null));
+		}
+	}
+
+	public partial class Gh4130 : ContentPage
+	{
+		public Gh4130()
+		{
+			InitializeComponent();
+			var c = new Gh4130Control();
+		}
+
+		public Gh4130(bool useCompiledXaml)
+		{
+			//this stub will be replaced at compile time
+		}
+
+		void OnTextChanged(object sender, EventArgs e)
+		{
+			Assert.Pass();
+		}
+
+		[TestFixture]
+		class Tests
+		{
+			[SetUp]
+			public void Setup()
+			{
+				Device.PlatformServices = new MockPlatformServices();
+			}
+
+			[TearDown]
+			public void TearDown()
+			{
+				Device.PlatformServices = null;
+			}
+
+			[TestCase(false),TestCase(true)]
+			public void NonGenericEventHanlders(bool useCompiledXaml)
+			{
+				var layout = new Gh4130(useCompiledXaml);
+				var control = layout.Content as Gh4130Control;
+				control.FireEvent();
+				Assert.Fail();
+			}
+		}
+	}
+}

Xamarin.Forms.Xaml.UnitTests/Xamarin.Forms.Xaml.UnitTests.csproj

@@ -655,6 +655,9 @@
     <Compile Include="Issues\Gh4099.xaml.cs">
       <DependentUpon>Gh4099.xaml</DependentUpon>
     </Compile>
+    <Compile Include="Issues\Gh4130.xaml.cs">
+      <DependentUpon>Gh4130.xaml</DependentUpon>
+    </Compile>
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <PropertyGroup>
@@ -1207,6 +1210,10 @@
       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
       <SubType>Designer</SubType>
     </EmbeddedResource>
+    <EmbeddedResource Include="Issues\Gh4130.xaml">
+      <SubType>Designer</SubType>
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
   </ItemGroup>
   <ItemGroup>
     <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />