From c79952a4d64c07f2a958499a7908d768d56857f0 Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Tue, 4 Jul 2023 17:57:59 +0200
Subject: [PATCH] Implement missing dotnet7 interop for field and stabilize
 interop

---
 .../Engine/Engine/NativeInterop.Marshallers.cs |  2 +-
 .../Engine/Engine/NativeInterop.Unmanaged.cs   | 18 +++++++++++++++++-
 Source/Engine/Engine/NativeInterop.cs          |  5 ++++-
 Source/Engine/Scripting/Runtime/DotNet.cpp     |  8 ++++----
 4 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/Source/Engine/Engine/NativeInterop.Marshallers.cs b/Source/Engine/Engine/NativeInterop.Marshallers.cs
index 0a23bfcbd..2e3bc9183 100644
--- a/Source/Engine/Engine/NativeInterop.Marshallers.cs
+++ b/Source/Engine/Engine/NativeInterop.Marshallers.cs
@@ -399,7 +399,7 @@ namespace FlaxEngine.Interop
                 }
                 numElements = managed.Length;
                 ManagedArray managedArray = ManagedArray.AllocatePooledArray<TUnmanagedElement>(managed.Length);
-                return (TUnmanagedElement*)ManagedHandle.ToIntPtr(managedArray, GCHandleType.Weak);
+                return (TUnmanagedElement*)ManagedHandle.ToIntPtr(managedArray, GCHandleType.Normal);
             }
 
             public static ReadOnlySpan<T> GetManagedValuesSource(T[] managed) => managed;
diff --git a/Source/Engine/Engine/NativeInterop.Unmanaged.cs b/Source/Engine/Engine/NativeInterop.Unmanaged.cs
index d4a8d44f8..bba9e3db8 100644
--- a/Source/Engine/Engine/NativeInterop.Unmanaged.cs
+++ b/Source/Engine/Engine/NativeInterop.Unmanaged.cs
@@ -770,6 +770,13 @@ namespace FlaxEngine.Interop
             field.field.SetValue(fieldOwner, value);
         }
 
+        [UnmanagedCallersOnly]
+        internal static int FieldGetOffset(ManagedHandle fieldHandle)
+        {
+            FieldHolder field = Unsafe.As<FieldHolder>(fieldHandle.Target);
+            return (int)Marshal.OffsetOf(field.field.DeclaringType, field.field.Name);
+        }
+
         [UnmanagedCallersOnly]
         internal static void FieldGetValue(ManagedHandle fieldOwnerHandle, ManagedHandle fieldHandle, IntPtr valuePtr)
         {
@@ -778,6 +785,15 @@ namespace FlaxEngine.Interop
             field.toNativeMarshaller(field.field, fieldOwner, valuePtr, out int fieldOffset);
         }
 
+        [UnmanagedCallersOnly]
+        internal static IntPtr FieldGetValueBoxed(ManagedHandle fieldOwnerHandle, ManagedHandle fieldHandle)
+        {
+            object fieldOwner = fieldOwnerHandle.Target;
+            FieldHolder field = Unsafe.As<FieldHolder>(fieldHandle.Target);
+            object fieldValue = field.field.GetValue(fieldOwner);
+            return Invoker.MarshalReturnValueGeneric(field.field.FieldType, fieldValue);
+        }
+
         [UnmanagedCallersOnly]
         internal static void WriteArrayReference(ManagedHandle arrayHandle, IntPtr valueHandle, int index)
         {
@@ -924,7 +940,7 @@ namespace FlaxEngine.Interop
             if (nativeType.IsClass)
                 size = sizeof(IntPtr);
             else
-                size = Marshal.SizeOf(nativeType);
+                size = GetTypeSize(type);
             return size;
         }
 
diff --git a/Source/Engine/Engine/NativeInterop.cs b/Source/Engine/Engine/NativeInterop.cs
index e82cb3858..acfd7181b 100644
--- a/Source/Engine/Engine/NativeInterop.cs
+++ b/Source/Engine/Engine/NativeInterop.cs
@@ -1095,7 +1095,10 @@ namespace FlaxEngine.Interop
             {
                 try
                 {
-                    size = Marshal.SizeOf(type);
+                    var marshalType = type;
+                    if (type.IsEnum)
+                        marshalType = type.GetEnumUnderlyingType();
+                    size = Marshal.SizeOf(marshalType);
                 }
                 catch
                 {
diff --git a/Source/Engine/Scripting/Runtime/DotNet.cpp b/Source/Engine/Scripting/Runtime/DotNet.cpp
index 246c1620f..8d75d7a95 100644
--- a/Source/Engine/Scripting/Runtime/DotNet.cpp
+++ b/Source/Engine/Scripting/Runtime/DotNet.cpp
@@ -1163,8 +1163,8 @@ MType* MField::GetType() const
 
 int32 MField::GetOffset() const
 {
-    MISSING_CODE("TODO: MField::GetOffset"); // TODO: MField::GetOffset
-    return 0;
+    static void* FieldGetOffsetPtr = GetStaticMethodPointer(TEXT("FieldGetOffset"));
+    return CallStaticMethod<int32, void*>(FieldGetOffsetPtr, _handle);
 }
 
 void MField::GetValue(MObject* instance, void* result) const
@@ -1175,8 +1175,8 @@ void MField::GetValue(MObject* instance, void* result) const
 
 MObject* MField::GetValueBoxed(MObject* instance) const
 {
-    MISSING_CODE("TODO: MField::GetValueBoxed"); // TODO: MField::GetValueBoxed
-    return nullptr;
+    static void* FieldGetValueBoxedPtr = GetStaticMethodPointer(TEXT("FieldGetValueBoxed"));
+    return CallStaticMethod<MObject*, void*, void*>(FieldGetValueBoxedPtr, instance, _handle);
 }
 
 void MField::SetValue(MObject* instance, void* value) const