Apply suggestions from Claude code review

ICSharpCode.Decompiler.Tests/TestCases/Pretty/ExtensionEverything.cs

@@ -90,12 +90,14 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			Point point = new Point(3, 4);
 			Console.WriteLine(point.X);
 			Console.WriteLine(point.Y);
+			// TODO implement use-site transformation
 			//Console.WriteLine(point.Magnitude);
 		}
 
 		public static void TestExtensionMethods()
 		{
 			List<string> collection = new List<string>();
+			// TODO implement use-site transformation
 			//Console.WriteLine(collection.IsEmpty);
 			collection.AddIfNotNull("Hello");
 			collection.AddIfNotNull(null);

ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs

@@ -955,8 +955,12 @@ namespace ICSharpCode.Decompiler.CSharp
 				foreach (var h in methods)
 				{
 					var m = metadata.GetMethodDefinition(h);
-					if (metadata.StringComparer.Equals(m.Name, name))
-						return h;
+					if (!metadata.StringComparer.Equals(m.Name, name))
+						continue;
+
+					// TODO : use SignatureBlobComparer to ensure that the correct method is resolved
+
+					return h;
 				}
 				return default;
 			}

ICSharpCode.Decompiler/TypeSystem/ExtensionInfo.cs

@@ -260,9 +260,11 @@ namespace ICSharpCode.Decompiler.TypeSystem
 			IEnumerable<IMember> GetMembers()
 			{
 				var markerType = marker.DeclaringTypeDefinition;
+				Debug.Assert(markerType != null, "Marker should always be contained in a type");
+
 				foreach (var info in extensionMemberMap.Values)
 				{
-					if (!markerType!.Equals(info.ExtensionMarkerType))
+					if (!markerType.Equals(info.ExtensionMarkerType))
 						continue;
 					var subst = new TypeParameterSubstitution(info.ExtensionGroupingTypeParameters, null);
 					if (info.ExtensionMember.IsAccessor)

ICSharpCode.Decompiler/TypeSystem/TypeSystemExtensions.cs

@@ -18,6 +18,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using System.Reflection.Metadata;
 
@@ -878,7 +879,8 @@ namespace ICSharpCode.Decompiler.TypeSystem
 			{
 				throw new ArgumentNullException(nameof(member));
 			}
-			var td = member.DeclaringTypeDefinition!;
+			var td = member.DeclaringTypeDefinition;
+			Debug.Assert(td != null, "IMember.DeclaringTypeDefinition should never be null");
 			return td.DeclaringTypeDefinition?.ExtensionInfo ?? td.DeclaringTypeDefinition?.DeclaringTypeDefinition?.ExtensionInfo;
 		}
 	}

ILSpy/TreeNodes/ExtensionTreeNode.cs

@@ -61,19 +61,20 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			return ((MetadataModule)ParentAssemblyNode.LoadedAssembly
 				.GetMetadataFileOrNull()
 				?.GetTypeSystemWithCurrentOptionsOrNull(SettingsService, AssemblyTreeModel.CurrentLanguageVersion)
-				?.MainModule)?.GetDefinition((SRM.TypeDefinitionHandle)MarkerMethod.DeclaringTypeDefinition.MetadataToken);
+				?.MainModule)?.GetDefinition((SRM.TypeDefinitionHandle)MarkerMethod.DeclaringTypeDefinition.MetadataToken)
+				?? MarkerMethod.DeclaringTypeDefinition;
 		}
 
 		protected override void LoadChildren()
 		{
 			var extensionInfo = ContainerTypeDefinition.ExtensionInfo;
-			var subst = new TypeParameterSubstitution(TypeParameters, null);
+			var members = extensionInfo.GetMembersOfGroup(MarkerMethod).ToList();
 
-			foreach (var property in extensionInfo.GetMembersOfGroup(MarkerMethod).OfType<IProperty>().OrderBy(p => p.Name, NaturalStringComparer.Instance))
+			foreach (var property in members.OfType<IProperty>().OrderBy(p => p.Name, NaturalStringComparer.Instance))
 			{
 				this.Children.Add(new PropertyTreeNode(property));
 			}
-			foreach (var method in extensionInfo.GetMembersOfGroup(MarkerMethod).OfType<IMethod>().OrderBy(m => m.Name, NaturalStringComparer.Instance))
+			foreach (var method in members.OfType<IMethod>().OrderBy(m => m.Name, NaturalStringComparer.Instance))
 			{
 				if (method.MetadataToken.IsNil)
 					continue;

ILSpy/TreeNodes/PropertyTreeNode.cs

@@ -17,6 +17,7 @@
 // DEALINGS IN THE SOFTWARE.
 
 using System;
+using System.Diagnostics;
 using System.Reflection.Metadata;
 using System.Windows.Media;
 
@@ -69,6 +70,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 		public static ImageSource GetIcon(IProperty property)
 		{
 			IMethod accessor = property.Getter ?? property.Setter;
+			Debug.Assert(accessor != null, "Property must have at least one accessor");
 			bool isExtension = property.ResolveExtensionInfo()?.InfoOfExtensionMember((IMethod)accessor.MemberDefinition) != null;
 			return Images.GetIcon(property.IsIndexer ? MemberIcon.Indexer : MemberIcon.Property,
 				Images.GetOverlayIcon(property.Accessibility), property.IsStatic, isExtension);

ILSpy/TreeNodes/TypeTreeNode.cs

@@ -97,7 +97,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			var extensionInfo = TypeDefinition.ExtensionInfo;
 			if (extensionInfo != null)
 			{
-				foreach (var extensionGroup in TypeDefinition.ExtensionInfo?.ExtensionGroups ?? [])
+				foreach (var extensionGroup in extensionInfo.ExtensionGroups)
 				{
 					this.Children.Add(new ExtensionTreeNode(TypeDefinition, extensionGroup, ParentAssemblyNode));
 				}