From 05154391fb39d430ae0c0df1344feea111ef54e4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jos=C3=A9=20Pedro?= <jpedrolmail@gmail.com>
Date: Tue, 14 Jul 2020 19:29:40 +0100
Subject: [PATCH] Fixed item type inference in compiled bindings.

---
 ...valoniaXamlIlDataContextTypeTransformer.cs | 29 +++++++++++--------
 1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/Transformers/AvaloniaXamlIlDataContextTypeTransformer.cs b/src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/Transformers/AvaloniaXamlIlDataContextTypeTransformer.cs
index 5a0d6bac8d..241976241f 100644
--- a/src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/Transformers/AvaloniaXamlIlDataContextTypeTransformer.cs
+++ b/src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/Transformers/AvaloniaXamlIlDataContextTypeTransformer.cs
@@ -1,11 +1,6 @@
-using System;
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
-using System.Text;
-using Avalonia.Markup.Parsers;
-using Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers;
-using Avalonia.Utilities;
 using XamlX;
 using XamlX.Ast;
 using XamlX.Transform;
@@ -129,12 +124,13 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
 
             if (itemsCollectionType != null)
             {
-                var elementType = itemsCollectionType
-                    .GetAllInterfaces()
-                    .FirstOrDefault(i =>
-                        i.GenericTypeDefinition?.Equals(context.Configuration.WellKnownTypes.IEnumerableT) == true)
-                    .GenericArguments[0];
-                return new AvaloniaXamlIlDataContextTypeMetadataNode(on, elementType);
+                foreach (var i in GetAllInterfacesIncludingSelf(itemsCollectionType))
+                {
+                    if (i.GenericTypeDefinition?.Equals(context.Configuration.WellKnownTypes.IEnumerableT) == true)
+                    {
+                        return new AvaloniaXamlIlDataContextTypeMetadataNode(on, i.GenericArguments[0]);
+                    }
+                }
             }
             // We can't infer the collection type and the currently calculated type is definitely wrong.
             // Notify the user that we were unable to infer the data context type if they use a compiled binding.
@@ -165,6 +161,15 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
 
             return new AvaloniaXamlIlUninferrableDataContextMetadataNode(on);
         }
+
+        private static IEnumerable<IXamlType> GetAllInterfacesIncludingSelf(IXamlType type)
+        {
+            if (type.IsInterface)
+                yield return type;
+
+            foreach (var i in type.GetAllInterfaces())
+                yield return i;
+        }
     }
 
     [DebuggerDisplay("DataType = {DataContextType}")]