Provide helper type instead of manually emitting closure type into assembly.

src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/CompiledBindings/PropertyInfoAccessorFactory.cs

@@ -22,6 +22,21 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings
             => new IndexerAccessor(target, property, argument);
     }
 
+    public class IndexerPropertyAccessorHelper
+    {
+        private readonly int _index;
+
+        public IndexerPropertyAccessorHelper(int index)
+        {
+            _index = index;
+        }
+
+        public IPropertyAccessor CreateAccessor(WeakReference target, IPropertyInfo property)
+        {
+            return PropertyInfoAccessorFactory.CreateIndexerPropertyAccessor(target, property, _index);
+        }
+    }
+
     internal class AvaloniaPropertyAccessor : PropertyAccessorBase
     {
         private readonly WeakReference<AvaloniaObject> _reference;

src/Markup/Avalonia.Markup.Xaml/XamlIl/CompilerExtensions/Transformers/AvaloniaXamlIlWellKnownTypes.cs

@@ -32,6 +32,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
         public IXamlIlType PropertyPathBuilder { get; }
         public IXamlIlType IPropertyAccessor { get; }
         public IXamlIlType PropertyInfoAccessorFactory { get; }
+        public IXamlIlType IndexerPropertyAccessorHelper { get; }
         public IXamlIlType CompiledBindingPathBuilder { get; }
         public IXamlIlType CompiledBindingPath { get; }
         public IXamlIlType CompiledBindingExtension { get; }
@@ -82,6 +83,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
             PropertyPathBuilder = cfg.TypeSystem.GetType("Avalonia.Data.Core.PropertyPathBuilder");
             IPropertyAccessor = cfg.TypeSystem.GetType("Avalonia.Data.Core.Plugins.IPropertyAccessor");
             PropertyInfoAccessorFactory = cfg.TypeSystem.GetType("Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings.PropertyInfoAccessorFactory");
+            IndexerPropertyAccessorHelper = cfg.TypeSystem.GetType("Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings.IndexerPropertyAccessorHelper");
             CompiledBindingPathBuilder = cfg.TypeSystem.GetType("Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings.CompiledBindingPathBuilder");
             CompiledBindingPath = cfg.TypeSystem.GetType("Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings.CompiledBindingPath");
             CompiledBindingExtension = cfg.TypeSystem.GetType("Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindingExtension");

src/Markup/Avalonia.Markup.Xaml/XamlIl/CompilerExtensions/XamlIlPropertyInfoAccessorFactoryEmitter.cs

@@ -11,12 +11,8 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
 {
     class XamlIlPropertyInfoAccessorFactoryEmitter
     {
-        private const string IndexerClosureFactoryMethodName = "CreateAccessor";
-        private readonly IXamlIlTypeBuilder _indexerClosureTypeBuilder;
-        private IXamlIlType _indexerClosureType;
         public XamlIlPropertyInfoAccessorFactoryEmitter(IXamlIlTypeBuilder indexerClosureType)
         {
-            _indexerClosureTypeBuilder = indexerClosureType;
         }
 
         public IXamlIlType EmitLoadInpcPropertyAccessorFactory(XamlIlEmitContext context, IXamlIlEmitter codeGen)
@@ -46,57 +42,16 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
 
         public IXamlIlType EmitLoadIndexerAccessorFactory(XamlIlEmitContext context, IXamlIlEmitter codeGen, IXamlIlAstValueNode value)
         {
+            const string IndexerClosureFactoryMethodName = "CreateAccessor";
             var intType = context.Configuration.TypeSystem.GetType("System.Int32");
-            if (_indexerClosureType is null)
+            var indexerClosureType = context.GetAvaloniaTypes().IndexerPropertyAccessorHelper;
-            {
-                _indexerClosureType = InitializeClosureType(context);
-            }
 
             context.Emit(value, codeGen, intType);
-            codeGen.Newobj(_indexerClosureType.FindConstructor(new List<IXamlIlType> { intType }));
+            codeGen.Newobj(indexerClosureType.FindConstructor(new List<IXamlIlType> { intType }));
-            EmitLoadPropertyAccessorFactory(context, codeGen, _indexerClosureType, IndexerClosureFactoryMethodName, isStatic: false);
+            EmitLoadPropertyAccessorFactory(context, codeGen, indexerClosureType, IndexerClosureFactoryMethodName, isStatic: false);
             return EmitCreateAccessorFactoryDelegate(context, codeGen);
         }
 
-        private IXamlIlType InitializeClosureType(XamlIlEmitContext context)
-        {
-            var types = context.GetAvaloniaTypes();
-            var intType = context.Configuration.TypeSystem.GetType("System.Int32");
-            var weakReferenceType = context.Configuration.TypeSystem.GetType("System.WeakReference");
-            var indexAccessorFactoryMethod = context.GetAvaloniaTypes().PropertyInfoAccessorFactory.GetMethod(
-                    new FindMethodMethodSignature(
-                        "CreateIndexerPropertyAccessor",
-                        types.IPropertyAccessor,
-                        weakReferenceType,
-                        types.IPropertyInfo,
-                        intType)
-                    {
-                        IsStatic = true
-                    });
-            var indexField = _indexerClosureTypeBuilder.DefineField(intType, "_index", false, false);
-            var ctor = _indexerClosureTypeBuilder.DefineConstructor(false, intType);
-            ctor.Generator
-                .Ldarg_0()
-                .Ldarg(1)
-                .Stfld(indexField)
-                .Ret();
-            _indexerClosureTypeBuilder.DefineMethod(
-                types.IPropertyAccessor,
-                new[] { weakReferenceType, types.IPropertyInfo },
-                IndexerClosureFactoryMethodName,
-                isPublic: true,
-                isStatic: false,
-                isInterfaceImpl: false)
-                .Generator
-                .Ldarg(1)
-                .Ldarg(2)
-                .LdThisFld(indexField)
-                .EmitCall(indexAccessorFactoryMethod)
-                .Ret();
-
-            return _indexerClosureTypeBuilder.CreateType();
-        }
-
         private IXamlIlType EmitCreateAccessorFactoryDelegate(XamlIlEmitContext context, IXamlIlEmitter codeGen)
         {
             var types = context.GetAvaloniaTypes();