Core: Fix exceptions in CustomAttributeTypeParameter for generics

Author: SamboyCoding

Cpp2IL.Core/Api/ICSharpSourceToken.cs

@@ -0,0 +1,9 @@
+namespace Cpp2IL.Core.Api;
+
+public interface ICSharpSourceToken
+{
+    /// <summary>
+    /// Returns a string of C# source code which would be equivalent to this token. For example, for types, this would be the type name, for generic types, the full type name with generic arguments, etc.
+    /// </summary>
+    public string GetCSharpSourceString();
+}

Cpp2IL.Core/Model/Contexts/GenericInstanceTypeAnalysisContext.cs

@@ -1,4 +1,5 @@
 using System.Linq;
+using System.Text;
 using Cpp2IL.Core.Utils;
 using LibCpp2IL.BinaryStructures;
 
@@ -16,4 +17,26 @@ public GenericInstanceTypeAnalysisContext(Il2CppType rawType, AssemblyAnalysisCo
 
         GenericArguments.AddRange(gClass.Context.ClassInst.Types.Select(referencedFrom.ResolveIl2CppType)!);
     }
-}
+
+    public override string GetCSharpSourceString()
+    {
+        var sb = new StringBuilder();
+
+        sb.Append(ElementType.GetCSharpSourceString());
+        sb.Append('<');
+        var first = true;
+        foreach (var genericArgument in GenericArguments)
+        {
+            if (!first)
+                sb.Append(", ");
+            else
+                first = false;
+
+            sb.Append(genericArgument.GetCSharpSourceString());
+        }
+        
+        sb.Append('>');
+        
+        return sb.ToString();
+    }
+}

Cpp2IL.Core/Model/Contexts/GenericParameterTypeAnalysisContext.cs

@@ -13,4 +13,4 @@ public GenericParameterTypeAnalysisContext(Il2CppType rawType, AssemblyAnalysisC
 
         GenericParameter = rawType.GetGenericParameterDef();
     }
-}
+}

Cpp2IL.Core/Model/Contexts/ReferencedTypeAnalysisContext.cs

@@ -46,4 +46,9 @@ public override string ToString()
     {
         return $"{DefaultName}";
     }
-}
+
+    public override string GetCSharpSourceString()
+    {
+        return Name;
+    }
+}

Cpp2IL.Core/Model/Contexts/TypeAnalysisContext.cs

@@ -3,6 +3,8 @@
 using System.IO;
 using System.Linq;
 using System.Reflection;
+using System.Text;
+using Cpp2IL.Core.Api;
 using Cpp2IL.Core.Utils;
 using LibCpp2IL.BinaryStructures;
 using LibCpp2IL.Metadata;
@@ -14,7 +16,7 @@ namespace Cpp2IL.Core.Model.Contexts;
 /// <summary>
 /// Represents one managed type in the application.
 /// </summary>
-public class TypeAnalysisContext : HasCustomAttributesAndName, ITypeInfoProvider
+public class TypeAnalysisContext : HasCustomAttributesAndName, ITypeInfoProvider, ICSharpSourceToken
 {
     /// <summary>
     /// The context for the assembly this type was defined in.
@@ -137,6 +139,19 @@ public TypeAnalysisContext(Il2CppTypeDefinition? il2CppTypeDefinition, AssemblyA
     public List<MethodAnalysisContext> GetConstructors() => Methods.Where(m => m.Definition!.Name == ".ctor").ToList();
 
     public override string ToString() => $"Type: {Definition?.FullName}";
+    public virtual string GetCSharpSourceString()
+    {
+        if (Definition != null)
+            return Definition.FullName!;
+
+        var ret = new StringBuilder();
+        if(OverrideNs != null)
+            ret.Append(OverrideNs).Append('.');
+        
+        ret.Append(Name);
+
+        return ret.ToString();
+    }
 
     #region StableNameDotNet implementation
 

Cpp2IL.Core/Model/CustomAttributes/CustomAttributeTypeParameter.cs

@@ -3,6 +3,7 @@
 using AsmResolver.DotNet.Signatures.Types;
 using Cpp2IL.Core.Extensions;
 using Cpp2IL.Core.Model.Contexts;
+using Cpp2IL.Core.Utils;
 using Cpp2IL.Core.Utils.AsmResolver;
 using LibCpp2IL;
 using LibCpp2IL.BinaryStructures;
@@ -43,7 +44,15 @@ public override string ToString()
 
         if (Type.Type.IsIl2CppPrimitive())
             return $"typeof({LibCpp2ILUtils.GetTypeName(Owner.Constructor.AppContext.Metadata, Owner.Constructor.AppContext.Binary, Type)}";
+
+        if (Type.Type is not Il2CppTypeEnum.IL2CPP_TYPE_CLASS and not Il2CppTypeEnum.IL2CPP_TYPE_VALUETYPE)
+        {
+            //Some sort of wrapper type, like a generic parameter or a generic instance.
+            var typeContext = Owner.Constructor.CustomAttributeAssembly.ResolveIl2CppType(Type);
+            return $"typeof({typeContext.GetCSharpSourceString()})";
+        }
 
+        //Basic class/struct
         return $"typeof({Type.AsClass().Name})";
     }
 

Cpp2IL.Core/Utils/Il2CppTypeToContext.cs

@@ -6,7 +6,7 @@
 
 namespace Cpp2IL.Core.Utils;
 
-internal static class Il2CppTypeToContext
+public static class Il2CppTypeToContext
 {
     private static TypeAnalysisContext GetPrimitive(this SystemTypesContext context, Il2CppTypeEnum type) => 
         type switch
@@ -54,4 +54,4 @@ private static TypeAnalysisContext GetPrimitive(this SystemTypesContext context,
 
         return new GenericParameterTypeAnalysisContext(type, context);
     }
-}
+}