From a36c93514dda0d31f9ee3f8f27a5b5a5ccb16c9d Mon Sep 17 00:00:00 2001
From: Robert Xiao <nneonneo@gmail.com>
Date: Mon, 13 Apr 2020 01:31:52 -0700
Subject: [PATCH] Implement NestedTypes for generic instances

In the C# reflection API, DeclaredNestedTypes on concrete generic types
just returns the nested types of the type definition. Notably, type
parameters are not substituted, because nested types are not guaranteed
to use the same containing type's type parameters.
---
 Il2CppInspector.Common/Reflection/TypeInfo.cs | 23 +++++++++++++++----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/Il2CppInspector.Common/Reflection/TypeInfo.cs b/Il2CppInspector.Common/Reflection/TypeInfo.cs
index 3f42c74..9f2e89c 100644
--- a/Il2CppInspector.Common/Reflection/TypeInfo.cs
+++ b/Il2CppInspector.Common/Reflection/TypeInfo.cs
@@ -95,13 +95,26 @@ namespace Il2CppInspector.Reflection {
 
         public List<MemberInfo> DeclaredMembers => new IEnumerable<MemberInfo>[] {
             DeclaredConstructors, DeclaredEvents, DeclaredFields, DeclaredMethods,
-            DeclaredNestedTypes?.ToList() ?? new List<TypeInfo>(), DeclaredProperties
+            DeclaredNestedTypes, DeclaredProperties
         }.SelectMany(m => m).ToList();
 
         public List<MethodInfo> DeclaredMethods { get; } = new List<MethodInfo>();
 
-        private readonly int[] declaredNestedTypes;
-        public IEnumerable<TypeInfo> DeclaredNestedTypes => declaredNestedTypes.Select(x => Assembly.Model.TypesByDefinitionIndex[x]);
+        private readonly TypeRef[] declaredNestedTypes;
+        public IEnumerable<TypeInfo> DeclaredNestedTypes {
+            get {
+                if (declaredNestedTypes != null)
+                    return declaredNestedTypes.Select(x => x.Value);
+                /* Type parameters are not substituted into nested classes,
+                 * as nested classes aren't required to use the parameters
+                 * from the containing class.
+                 * This also matches the behaviour of the C# reflection API.
+                 */
+                if (genericTypeDefinition != null)
+                    return genericTypeDefinition.DeclaredNestedTypes;
+                return Enumerable.Empty<TypeInfo>();
+            }
+        }
 
         public List<PropertyInfo> DeclaredProperties { get; } = new List<PropertyInfo>();
 
@@ -656,9 +669,9 @@ namespace Il2CppInspector.Reflection {
                 implementedInterfaceReferences[i] = TypeRef.FromReferenceIndex(Assembly.Model, pkg.InterfaceUsageIndices[Definition.interfacesStart + i]);
 
             // Add all nested types
-            declaredNestedTypes = new int[Definition.nested_type_count];
+            declaredNestedTypes = new TypeRef[Definition.nested_type_count];
             for (var n = 0; n < Definition.nested_type_count; n++)
-                declaredNestedTypes[n] = pkg.NestedTypeIndices[Definition.nestedTypesStart + n];
+                declaredNestedTypes[n] = TypeRef.FromDefinitionIndex(Assembly.Model, pkg.NestedTypeIndices[Definition.nestedTypesStart + n]);
 
             // Add all fields
             for (var f = Definition.fieldStart; f < Definition.fieldStart + Definition.field_count; f++)