Lib: Fix support for 2021.3.40+

Closes #317

Author: SamboyCoding

LibCpp2IL/BinaryStructures/Il2CppCodeRegistration.cs

@@ -34,7 +34,7 @@ public static int GetStructSize(bool isBinary32Bit, float metadataVersion)
         //unresolvedVirtualCallPointers
         size += 2 * ptrSize;
 
-        if (metadataVersion >= 29.1f)
+        if (metadataVersion is (> 29.1f and < 31f) or >= 31.1f)
             //unresolvedInstanceCallPointers and unresolvedStaticCallPointers
             size += 2 * ptrSize;
 
@@ -78,8 +78,8 @@ public static int GetStructSize(bool isBinary32Bit, float metadataVersion)
     public ulong unresolvedVirtualCallCount; //Renamed to unresolvedIndirectCallCount in v29.1
     public ulong unresolvedVirtualCallPointers;
 
-    [Version(Min = 29.1f)] public ulong unresolvedInstanceCallPointers;
-    [Version(Min = 29.1f)] public ulong unresolvedStaticCallPointers;
+    [Version(Min = 29.1f, Max=31f), Version(Min=31.1f)] public ulong unresolvedInstanceCallPointers;
+    [Version(Min = 29.1f, Max=31f), Version(Min=31.1f)] public ulong unresolvedStaticCallPointers;
 
     [Version(Min = 23)] public ulong interopDataCount;
     [Version(Min = 23)] public ulong interopData;
@@ -119,7 +119,7 @@ public override void Read(ClassReadingBinaryReader reader)
         unresolvedVirtualCallCount = reader.ReadNUint();
         unresolvedVirtualCallPointers = reader.ReadNUint();
 
-        if (IsAtLeast(29.1f))
+        if (IsAtLeast(29.1f) && IsNot(31f))
         {
             unresolvedInstanceCallPointers = reader.ReadNUint();
             unresolvedStaticCallPointers = reader.ReadNUint();

LibCpp2IL/Metadata/Il2CppMetadata.cs

@@ -116,7 +116,13 @@ public static Il2CppMetadata ReadFrom(byte[] bytes, UnityVersion unityVersion)
         {
             //2022.3.33 introduces v31. Unity why would you bump this on a minor version.
             //Adds one new field (return type token) to method def
-            actualVersion = 31;
+            //2023.1.40 backported the new field but NOT the changes from v29.1, so there's a 31.1 now.
+            if (unityVersion.GreaterThanOrEquals(2022, 3, 33, UnityVersionType.Final, 1))
+                //V31 with changes in codereg
+                actualVersion = 31.1f;
+            else
+                //v31 WITHOUT changes in codereg 
+                actualVersion = 31;
         }
         else actualVersion = version;