C#•2y ago

❔ IL weaving with Mono.Cecil in Unity isn't affecting Unity's assembly.

Hello, I wrote a simple program that finds methods decorated with an [Rpc] attributes, which works at finding them. Issue is when I try to weave Debug.Log("Hi"); into the method in which I'm not presented with any error but it fails. Code is below, any idea why this happens?

partial class Weaver
    {
        private static void RpcWeave(this MethodDefinition method)
        {
            Debug.Log($"RpcWeave called for method {method.Name}");
            if (method.Body == null)
            {
                Debug.Log("Method body is null");
                return;
            }

            if (method.Module == null)
            {
                Debug.Log("Method module is null");
                return;
            }

            // Get the reference to the UnityEngine.Debug class
            var debugType = method.Module.ImportReference(typeof(UnityEngine.Debug));
            if (debugType == null)
            {
                Debug.Log("Debug class not found");
                return;
            }

            // Get the reference to the Log method with a single string parameter
            var logMethod = method.Module.ImportReference(debugType.Resolve().Methods.FirstOrDefault(m =>
                m.Name == "Log" && m.Parameters.Count == 1 &&
                m.Parameters[0].ParameterType.FullName == typeof(object).FullName));

            // Check if the Log method was found
            if (logMethod == null)
            {
                Debug.Log("Log method not found");
                return;
            }

            ILProcessor weaver = method.Body.GetILProcessor();
            if (weaver == null)
            {
                Debug.Log("ILProcessor is null");
                return;
            }

            weaver.Emit(OpCodes.Ldstr, "Hi");
            weaver.Emit(OpCodes.Call, logMethod);
            weaver.Emit(OpCodes.Ret);
        }

    }

partial class Weaver
    {
        private static void RpcWeave(this MethodDefinition method)
        {
            Debug.Log($"RpcWeave called for method {method.Name}");
            if (method.Body == null)
            {
                Debug.Log("Method body is null");
                return;
            }

            if (method.Module == null)
            {
                Debug.Log("Method module is null");
                return;
            }

            // Get the reference to the UnityEngine.Debug class
            var debugType = method.Module.ImportReference(typeof(UnityEngine.Debug));
            if (debugType == null)
            {
                Debug.Log("Debug class not found");
                return;
            }

            // Get the reference to the Log method with a single string parameter
            var logMethod = method.Module.ImportReference(debugType.Resolve().Methods.FirstOrDefault(m =>
                m.Name == "Log" && m.Parameters.Count == 1 &&
                m.Parameters[0].ParameterType.FullName == typeof(object).FullName));

            // Check if the Log method was found
            if (logMethod == null)
            {
                Debug.Log("Log method not found");
                return;
            }

            ILProcessor weaver = method.Body.GetILProcessor();
            if (weaver == null)
            {
                Debug.Log("ILProcessor is null");
                return;
            }

            weaver.Emit(OpCodes.Ldstr, "Hi");
            weaver.Emit(OpCodes.Call, logMethod);
            weaver.Emit(OpCodes.Ret);
        }

    }

2 Replies

IcetrackOP•2y ago

This is how I'm testing it

public class NetworkBehaviourTest : NetworkBehaviour
    {
        private void Start()
        {
            TestGenerate();
        }

        [Rpc]
        private void TestGenerate()
        {
            Debug.Log("Method is called");
        }
    }

public class NetworkBehaviourTest : NetworkBehaviour
    {
        private void Start()
        {
            TestGenerate();
        }

        [Rpc]
        private void TestGenerate()
        {
            Debug.Log("Method is called");
        }
    }

"Hi" isn't printed so thats how I know weaving didn't work

Accord•2y ago

Looks like nothing has happened here. I will mark this as stale and this post will be archived until there is new activity.

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❔ IL weaving with Mono.Cecil in Unity isn't affecting Unity's assembly.