From 4ba48b9c75be65c3b77fd6d90126cd7434f4964f Mon Sep 17 00:00:00 2001
From: Robert Xiao <nneonneo@gmail.com>
Date: Mon, 20 Apr 2020 00:11:31 -0700
Subject: [PATCH] Add generics support to TypeInfo.GetVTable

This patch fixes TypeInfo.GetVTable so that it specializes the vtable
for generic type instances. Also fix a minor bug in PropertyInfo that
would pass null pointers to GetMethodByDefinition.
---
 .../Reflection/MethodBase.cs                  |  1 +
 .../Reflection/PropertyInfo.cs                |  6 ++--
 Il2CppInspector.Common/Reflection/TypeInfo.cs | 34 +++++++++++++------
 3 files changed, 29 insertions(+), 12 deletions(-)

diff --git a/Il2CppInspector.Common/Reflection/MethodBase.cs b/Il2CppInspector.Common/Reflection/MethodBase.cs
index 98e26a9..c860d1d 100644
--- a/Il2CppInspector.Common/Reflection/MethodBase.cs
+++ b/Il2CppInspector.Common/Reflection/MethodBase.cs
@@ -76,6 +76,7 @@ namespace Il2CppInspector.Reflection
                 return this;
             throw new InvalidOperationException("This method can only be called on generic methods");
         }
+        public MethodBase RootDefinition => rootDefinition;
 
         // See: https://docs.microsoft.com/en-us/dotnet/api/system.reflection.methodbase.isgenericmethod?view=netframework-4.8
         public bool IsGenericMethod { get; }
diff --git a/Il2CppInspector.Common/Reflection/PropertyInfo.cs b/Il2CppInspector.Common/Reflection/PropertyInfo.cs
index 4c770fb..4105aef 100644
--- a/Il2CppInspector.Common/Reflection/PropertyInfo.cs
+++ b/Il2CppInspector.Common/Reflection/PropertyInfo.cs
@@ -77,8 +77,10 @@ namespace Il2CppInspector.Reflection {
             rootDefinition = propertyDef;
 
             Name = propertyDef.Name;
-            GetMethod = declaringType.GetMethodByDefinition(propertyDef.GetMethod);
-            SetMethod = declaringType.GetMethodByDefinition(propertyDef.SetMethod);
+            if (propertyDef.GetMethod != null)
+                GetMethod = declaringType.GetMethodByDefinition(propertyDef.GetMethod);
+            if (propertyDef.SetMethod != null)
+                SetMethod = declaringType.GetMethodByDefinition(propertyDef.SetMethod);
         }
     }
 }
\ No newline at end of file
diff --git a/Il2CppInspector.Common/Reflection/TypeInfo.cs b/Il2CppInspector.Common/Reflection/TypeInfo.cs
index f60b0bc..387614c 100644
--- a/Il2CppInspector.Common/Reflection/TypeInfo.cs
+++ b/Il2CppInspector.Common/Reflection/TypeInfo.cs
@@ -210,7 +210,7 @@ namespace Il2CppInspector.Reflection
             if (genericTypeDefinition != null) {
                 var collection = genericTypeDefinition.DeclaredConstructors;
                 for (int i = 0; i < collection.Count; i++) {
-                    if (collection[i] == definition)
+                    if (collection[i].RootDefinition == definition.RootDefinition)
                         return DeclaredConstructors[i];
                 }
             }
@@ -222,7 +222,7 @@ namespace Il2CppInspector.Reflection
             if (genericTypeDefinition != null) {
                 var collection = genericTypeDefinition.DeclaredMethods;
                 for (int i = 0; i < collection.Count; i++) {
-                    if (collection[i] == definition)
+                    if (collection[i].RootDefinition == definition.RootDefinition)
                         return DeclaredMethods[i];
                 }
             }
@@ -250,15 +250,29 @@ namespace Il2CppInspector.Reflection
         public PropertyInfo GetProperty(string name) => DeclaredProperties.FirstOrDefault(p => p.Name == name);
 
         public MethodBase[] GetVTable() {
-            var definition = Definition;
-
-            MetadataUsage[] vt = Assembly.Model.Package.GetVTable(definition);
-            MethodBase[] res = new MethodBase[vt.Length];
-            for (int i = 0; i < vt.Length; i++) {
-                if (vt[i] != null)
-                    res[i] = Assembly.Model.GetMetadataUsageMethod(vt[i]);
+            if (Definition != null) {
+                MetadataUsage[] vt = Assembly.Model.Package.GetVTable(Definition);
+                MethodBase[] res = new MethodBase[vt.Length];
+                for (int i = 0; i < vt.Length; i++) {
+                    if (vt[i] != null)
+                        res[i] = Assembly.Model.GetMetadataUsageMethod(vt[i]);
+                }
+                return res;
+            } else if (genericTypeDefinition != null) {
+                MethodBase[] baseVt = genericTypeDefinition.GetVTable();
+                MethodBase[] res = new MethodBase[baseVt.Length];
+                for (int i = 0; i < baseVt.Length; i++) {
+                    if (baseVt[i] == null)
+                        continue;
+                    var declaringType = baseVt[i].DeclaringType.SubstituteGenericArguments(genericArguments);
+                    if (baseVt[i] is ConstructorInfo ci)
+                        res[i] = declaringType.GetConstructorByDefinition(ci);
+                    else
+                        res[i] = declaringType.GetMethodByDefinition((MethodInfo)baseVt[i]);
+                }
+                return res;
             }
-            return res;
+            return null;
         }
 
         // Method that the type is declared in if this is a type parameter of a generic method