fix: generic arguments resolution (#2300)

* fix: generic arguments lookup

The weaver was not able to figure out the synclist type in code like this:

```cs
    public class SomeList<G, T> : SyncList<T> { }
    public class SomeListInt : SomeList<string, int> { }
```

This code fixes that problem, and greatly reduces the complexity
of argument lookup.

* linting

Assets/Mirror/Editor/Weaver/Extensions.cs

@@ -249,12 +249,12 @@ public static MethodDefinition GetMethodInBaseType(this TypeDefinition td, strin
         /// <param name="methodName"></param>
         /// <param name="stopAt"></param>
         /// <returns></returns>
-        public static bool HasMethodInBaseType(this TypeDefinition td, string methodName, TypeReference stopAt)
+        public static bool HasMethodInBaseType(this TypeDefinition td, string methodName, Type stopAt)
         {
             TypeDefinition typedef = td;
             while (typedef != null)
             {
-                if (typedef.FullName == stopAt.FullName)
+                if (typedef.Is(stopAt))
                     break;
 
                 foreach (MethodDefinition md in typedef.Methods)

Assets/Mirror/Editor/Weaver/Processors/GenericArgumentResolver.cs

@@ -1,107 +1,56 @@
-using System.Collections.Generic;
+using System;
 using Mono.CecilX;
 
 namespace Mirror.Weaver
 {
-    public class GenericArgumentResolver
+    public static class GenericArgumentResolver
     {
-        readonly Stack<TypeReference> stack = new Stack<TypeReference>();
-        readonly int maxGenericArgument;
+        static TypeReference[] GetGenericArguments(TypeReference tr, Type baseType, TypeReference[] genericArguments)
+        {
+            if (tr == null)
+                return null;
 
-        public GenericArgumentResolver(int maxGenericArgument)
-        {
-            this.maxGenericArgument = maxGenericArgument;
-        }
+            TypeReference[] resolvedArguments = new TypeReference[0];
 
-        public bool GetGenericFromBaseClass(TypeDefinition td, int genericArgument, TypeReference baseType, out TypeReference itemType)
+            if (tr is GenericInstanceType genericInstance)
             {
-            itemType = null;
-            if (GetGenericBaseType(td, baseType, out GenericInstanceType parent))
+                // this type is a generic instance,  for example List<int>
+                // however, the parameter may be generic itself,  for example:
+                // List<T>.  If T is a generic parameter,  then look it up in
+                // from the arguments we got.
+                resolvedArguments = genericInstance.GenericArguments.ToArray();
+
+                for (int i = 0; i< resolvedArguments.Length; i++)
                 {
-                TypeReference arg = parent.GenericArguments[genericArgument];
-                if (arg.IsGenericParameter)
+                    TypeReference argument = resolvedArguments[i];
+                    if (argument is GenericParameter genericArgument)
                     {
-                    itemType = FindParameterInStack(td, genericArgument);
+                        resolvedArguments[i] = genericArguments[genericArgument.Position];
                     }
-                else
-                {
-                    itemType = Weaver.CurrentAssembly.MainModule.ImportReference(arg);
                 }
             }
 
-            return itemType != null;
-        }
+            if (tr.Is(baseType))
+                return resolvedArguments;
 
-        TypeReference FindParameterInStack(TypeDefinition td, int genericArgument)
-        {
-            while (stack.Count > 0)
-            {
-                TypeReference next = stack.Pop();
+            if (tr.CanBeResolved())
+                return GetGenericArguments(tr.Resolve().BaseType, baseType, resolvedArguments);
 
-                if (!(next is GenericInstanceType genericType))
-                {
-                    // if type is not GenericInstanceType something has gone wrong
             return null;
         }
 
-                if (genericType.GenericArguments.Count < genericArgument)
+        /// <summary>
+        /// Find out what the arguments are to a generic base type
+        /// </summary>
+        /// <param name="td"></param>
+        /// <param name="baseType"></param>
+        /// <returns></returns>
+        public static TypeReference[] GetGenericArguments(TypeDefinition td, Type baseType)
         {
-                    // if less than `genericArgument` then we didnt find generic argument
+            if (td == null)
                 return null;
-                }
 
-                if (genericType.GenericArguments.Count > maxGenericArgument)
-                {
-                    // if greater than `genericArgument` it is hard to know which generic arg we want
-                    // See SyncListGenericInheritanceWithMultipleGeneric test
-                    Weaver.Error($"Type {td.Name} has too many generic arguments in base class {next}", td);
-                    return null;
-                }
-
-                TypeReference genericArg = genericType.GenericArguments[genericArgument];
-                if (!genericArg.IsGenericParameter)
-                {
-                    // if not generic, successfully found type
-                    return Weaver.CurrentAssembly.MainModule.ImportReference(genericArg);
-                }
-            }
-
-            // nothing left in stack, something went wrong
-            return null;
-        }
-
-        bool GetGenericBaseType(TypeDefinition td, TypeReference baseType, out GenericInstanceType found)
-        {
-            stack.Clear();
-            TypeReference parent = td.BaseType;
-            found = null;
-
-            while (parent != null)
-            {
-                string parentName = parent.FullName;
-
-                // strip generic <T> parameters from class name (if any)
-                parentName = Extensions.StripGenericParametersFromClassName(parentName);
-
-                if (parentName == baseType.FullName)
-                {
-                    found = parent as GenericInstanceType;
-                    break;
-                }
-
-                try
-                {
-                    stack.Push(parent);
-                    parent = parent.Resolve().BaseType;
-                }
-                catch (AssemblyResolutionException)
-                {
-                    // this can happen for plugins.
-                    break;
-                }
-            }
-
-            return found != null;
+            return GetGenericArguments(td.BaseType, baseType, new TypeReference[] { });
         }
     }
 }

Assets/Mirror/Editor/Weaver/Processors/SyncDictionaryProcessor.cs

@@ -13,22 +13,11 @@ static class SyncDictionaryProcessor
         /// <param name="td">The synclist class</param>
         public static void Process(TypeDefinition td)
         {
-            GenericArgumentResolver resolver = new GenericArgumentResolver(2);
-            TypeReference syncDictionaryType = WeaverTypes.Import(typeof(SyncDictionary<,>));
-
-            if (resolver.GetGenericFromBaseClass(td, 0, syncDictionaryType, out TypeReference keyType))
+            TypeReference []arguments = GenericArgumentResolver.GetGenericArguments(td, typeof(SyncDictionary<,>));
+            if (arguments != null)
             {
-                SyncObjectProcessor.GenerateSerialization(td, keyType, syncDictionaryType, "SerializeKey", "DeserializeKey");
-            }
-            else
-            {
-                Weaver.Error($"Could not find generic arguments for SyncDictionary in {td.Name}", td);
-                return;
-            }
-
-            if (resolver.GetGenericFromBaseClass(td, 1, syncDictionaryType, out TypeReference itemType))
-            {
-                SyncObjectProcessor.GenerateSerialization(td, itemType, syncDictionaryType, "SerializeItem", "DeserializeItem");
+                SyncObjectProcessor.GenerateSerialization(td, arguments[0], typeof(SyncDictionary<,>), "SerializeKey", "DeserializeKey");
+                SyncObjectProcessor.GenerateSerialization(td, arguments[1], typeof(SyncDictionary<,>), "SerializeItem", "DeserializeItem");
             }
             else
             {

Assets/Mirror/Editor/Weaver/Processors/SyncListProcessor.cs

@@ -1,3 +1,4 @@
+using System;
 using Mono.CecilX;
 
 namespace Mirror.Weaver
@@ -12,13 +13,12 @@ static class SyncListProcessor
         /// </summary>
         /// <param name="td">The synclist class</param>
         /// <param name="mirrorBaseType">the base SyncObject td inherits from</param>
-        public static void Process(TypeDefinition td, TypeReference mirrorBaseType)
+        public static void Process(TypeDefinition td, Type mirrorBaseType)
         {
-            GenericArgumentResolver resolver = new GenericArgumentResolver(1);
-
-            if (resolver.GetGenericFromBaseClass(td, 0, mirrorBaseType, out TypeReference itemType))
+            TypeReference [] arguments = GenericArgumentResolver.GetGenericArguments(td, mirrorBaseType);
+            if (arguments != null)
             {
-                SyncObjectProcessor.GenerateSerialization(td, itemType, mirrorBaseType, "SerializeItem", "DeserializeItem");
+                SyncObjectProcessor.GenerateSerialization(td, arguments[0], mirrorBaseType, "SerializeItem", "DeserializeItem");
             }
             else
             {

Assets/Mirror/Editor/Weaver/Processors/SyncObjectProcessor.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using Mono.CecilX;
 using Mono.CecilX.Cil;
@@ -48,7 +49,7 @@ public static List<FieldDefinition> FindSyncObjectsFields(TypeDefinition td)
         /// <param name="mirrorBaseType">the base SyncObject td inherits from</param>
         /// <param name="serializeMethod">The name of the serialize method</param>
         /// <param name="deserializeMethod">The name of the deserialize method</param>
-        public static void GenerateSerialization(TypeDefinition td, TypeReference itemType, TypeReference mirrorBaseType, string serializeMethod, string deserializeMethod)
+        public static void GenerateSerialization(TypeDefinition td, TypeReference itemType, Type mirrorBaseType, string serializeMethod, string deserializeMethod)
         {
             Weaver.DLog(td, "SyncObjectProcessor Start item:" + itemType.FullName);
 
@@ -65,7 +66,7 @@ public static void GenerateSerialization(TypeDefinition td, TypeReference itemTy
         }
 
         // serialization of individual element
-        static bool GenerateSerialization(string methodName, TypeDefinition td, TypeReference itemType, TypeReference mirrorBaseType)
+        static bool GenerateSerialization(string methodName, TypeDefinition td, TypeReference itemType, Type mirrorBaseType)
         {
             Weaver.DLog(td, "  GenerateSerialization");
             bool existing = td.HasMethodInBaseType(methodName, mirrorBaseType);
@@ -109,7 +110,7 @@ static bool GenerateSerialization(string methodName, TypeDefinition td, TypeRefe
             return true;
         }
 
-        static bool GenerateDeserialization(string methodName, TypeDefinition td, TypeReference itemType, TypeReference mirrorBaseType)
+        static bool GenerateDeserialization(string methodName, TypeDefinition td, TypeReference itemType, Type mirrorBaseType)
         {
             Weaver.DLog(td, "  GenerateDeserialization");
             bool existing = td.HasMethodInBaseType(methodName, mirrorBaseType);

Assets/Mirror/Editor/Weaver/Weaver.cs

@@ -210,12 +210,12 @@ static bool WeaveSyncObject(TypeDefinition td)
             {
                 if (td.IsDerivedFrom(typeof(SyncList<>)))
                 {
-                    SyncListProcessor.Process(td, WeaverTypes.Import(typeof(SyncList<>)));
+                    SyncListProcessor.Process(td, typeof(SyncList<>));
                     modified = true;
                 }
                 else if (td.IsDerivedFrom(typeof(SyncSet<>)))
                 {
-                    SyncListProcessor.Process(td, WeaverTypes.Import(typeof(SyncSet<>)));
+                    SyncListProcessor.Process(td, typeof(SyncSet<>));
                     modified = true;
                 }
                 else if (td.IsDerivedFrom(typeof(SyncDictionary<,>)))

Assets/Mirror/Tests/Editor/Weaver/WeaverSyncListTests.cs

@@ -31,8 +31,7 @@ public void SyncListGenericInheritance()
         [Test]
         public void SyncListGenericInheritanceWithMultipleGeneric()
         {
-            HasError("Could not find generic arguments for SyncList`1 in WeaverSyncListTests.SyncListGenericInheritanceWithMultipleGeneric.SyncListGenericInheritanceWithMultipleGeneric/SomeListInt",
-                "WeaverSyncListTests.SyncListGenericInheritanceWithMultipleGeneric.SyncListGenericInheritanceWithMultipleGeneric/SomeListInt");
+            IsSuccess();
         }
 
         [Test]

Assets/Mirror/Tests/Editor/Weaver/WeaverSyncListTests~/SyncListGenericInheritanceWithMultipleGeneric.cs

@@ -3,11 +3,8 @@
 namespace WeaverSyncListTests.SyncListGenericInheritanceWithMultipleGeneric
 {
     /*
-    This test will fail
-    It is hard to know which generic argument we want from `SomeList<string, int>`
-    So instead give a useful error for this edge case
+    This test should pass
     */
-
     class SyncListGenericInheritanceWithMultipleGeneric : NetworkBehaviour
     {
         readonly SomeListInt someList = new SomeListInt();