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Fix duplicate types in generated assemblies on Unity 6.4+ #266

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Fix duplicate types in generated assemblies on Unity 6.4+ #266

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Fix duplicate types in generated assemblies on Unity 6.4+
acan1980728690 May 29, 2026
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acan1980728690 May 29, 2026
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38 changes: 28 additions & 10 deletions Il2CppInterop.Generator/Passes/Pass79UnstripTypes.cs
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Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
using AsmResolver;
using AsmResolver.DotNet;
using AsmResolver.DotNet.Signatures;
using AsmResolver.PE.DotNet.Metadata.Tables;
Expand Down Expand Up @@ -47,15 +48,20 @@ private static void ProcessType(AssemblyRewriteContext processedAssembly, TypeDe
if (unityType.BaseType != null && unityType.BaseType.FullName == "System.MulticastDelegate")
return;
var newModule = processedAssembly.NewAssembly.ManifestModule!;
var processedType = enclosingNewType == null
? processedAssembly.TryGetTypeByName(unityType.FullName)?.NewType
: enclosingNewType.NestedTypes.SingleOrDefault(it => it.Name == unityType.Name);
var processedType = processedAssembly.TryGetTypeByName(unityType.FullName)?.NewType;
var convertedTypeName = GetConvertedUnityTypeName(processedAssembly.GlobalContext, unityType);

// If the parent type does not exist in the rewritten assembly, this nested type cannot be emitted safely.
// Promoting it to a top-level type creates orphan compiler-generated types such as __O/__c.

@ds5678 ds5678 May 29, 2026

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That is so cursed that we were doing this before.

if ((unityType.DeclaringType is null) != (enclosingNewType is null))
return;

if (unityType.IsEnum)
{
if (processedType != null) return;

typesUnstripped++;
var clonedType = CloneEnum(unityType, imports);
var clonedType = CloneEnum(unityType, convertedTypeName, imports);
if (enclosingNewType == null)
{
newModule.TopLevelTypes.Add(clonedType);
Expand All @@ -74,7 +80,8 @@ private static void ProcessType(AssemblyRewriteContext processedAssembly, TypeDe
!unityType.HasGenericParameters()) // restore all types even if it would be not entirely correct
{
typesUnstripped++;
var clonedType = new TypeDefinition(unityType.Namespace, unityType.Name, ForcePublic(unityType.Attributes), unityType.BaseType == null ? null : newModule.DefaultImporter.ImportType(unityType.BaseType));
var clonedType = new TypeDefinition(unityType.Namespace, convertedTypeName, ForcePublic(unityType.Attributes),
unityType.BaseType == null ? null : newModule.DefaultImporter.ImportType(unityType.BaseType));
if (enclosingNewType == null)
{
newModule.TopLevelTypes.Add(clonedType);
Expand All @@ -100,9 +107,9 @@ private static void ProcessType(AssemblyRewriteContext processedAssembly, TypeDe
ProcessType(processedAssembly, nestedUnityType, processedType, imports, ref typesUnstripped);
}

private static TypeDefinition CloneEnum(TypeDefinition sourceEnum, RuntimeAssemblyReferences imports)
private static TypeDefinition CloneEnum(TypeDefinition sourceEnum, Utf8String convertedTypeName, RuntimeAssemblyReferences imports)
{
var newType = new TypeDefinition(sourceEnum.Namespace, sourceEnum.Name, ForcePublic(sourceEnum.Attributes),
var newType = new TypeDefinition(sourceEnum.Namespace, convertedTypeName, ForcePublic(sourceEnum.Attributes),
imports.Module.Enum().ToTypeDefOrRef());
foreach (var sourceEnumField in sourceEnum.Fields)
{
Expand Down Expand Up @@ -130,14 +137,25 @@ private static bool HasNonBlittableFields(TypeDefinition type)
if (!fieldDefinition.Signature!.FieldType.IsValueType())
return true;

if (fieldDefinition.Signature.FieldType.Namespace?.StartsWith("System") ?? false &&
HasNonBlittableFields(fieldDefinition.Signature.FieldType.Resolve()))
return true;
if (fieldDefinition.Signature.FieldType.Namespace?.StartsWith("System") ?? false)
{
var resolved = fieldDefinition.Signature.FieldType.Resolve();
if (resolved != null && HasNonBlittableFields(resolved))
return true;
}
Comment on lines +140 to +145

@ds5678 ds5678 May 29, 2026

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This is cursed, but it's not your fault. I see no reason for:

  • A System namespace check
  • Resolving a TypeSignature to a TypeDefinition, which removes the type arguments if the signature is a generic instance type

I'm not asking you to change anything, except maybe returning true for null resolved; I'm just saying that the preexisting code is extremely flawed.

}

return false;
}

private static Utf8String GetConvertedUnityTypeName(RewriteGlobalContext context, TypeDefinition unityType)
{
if (context.Options.PassthroughNames)
return unityType.Name ?? Utf8String.Empty;

return unityType.Name.MakeValidInSource();
}

private static TypeAttributes ForcePublic(TypeAttributes typeAttributes)
{
var visibility = typeAttributes & TypeAttributes.VisibilityMask;
Expand Down
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