Fix a couple of semi-edge-cases (#199)

* Avoid throwing on IDisposable

* Avoid throwing in ProtoBufMarshallerFactory.CanSerialize

There is at least one situation where the underlying protobuf TypeModel
throws a NotSupportedException : when asking about an array of arrays.
While this seems doubtful (it should simply return false), it is easy
enough to prevent this from trashing the whole service.

* Remove remnant of old code

No longer any reason to handle delegates specifically : it will be done
naturally by the marshallerCache (and who knows, maybe it *can*
serialize some delegates !).
Moreover, this could misinterpret a signature as valid without parameter,
with somewhat weird consequences.

---------

Co-authored-by: Marc Gravell <[email protected]>

src/protobuf-net.Grpc/Configuration/ProtoBufMarshallerFactory.cs

@@ -1,4 +1,4 @@
-using ProtoBuf.Meta;
+using ProtoBuf.Meta;
 using System;
 using System.Buffers;
 using System.IO;
@@ -187,9 +187,19 @@ private T ContextualDeserialize<T>(global::Grpc.Core.DeserializationContext cont
         /// Indicates whether a type should be considered as a serializable data type
         /// </summary>
         protected internal override bool CanSerialize(Type type)
-            => HasSingle(Options.ContractTypesOnly)
-                ? _model.CanSerializeContractType(type)
-                : _model.CanSerialize(type);
+        {
+            try
+            {
+                return HasSingle(Options.ContractTypesOnly)
+                    ? _model.CanSerializeContractType(type)
+                    : _model.CanSerialize(type);
+            }
+            catch (NotSupportedException)
+            {
+                // a typical case is the use of jagged arrays
+                return false;
+            }
+        }
 
         /// <summary>
         /// Deserializes an object from a payload

src/protobuf-net.Grpc/Internal/ContractOperation.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Reflection;
 using Grpc.Core;
@@ -212,8 +212,6 @@ static TypeCategory GetCategory(MarshallerCache marshallerCache, Type type, IBin
                 if (genType == typeof(AsyncServerStreamingCall<>)) return TypeCategory.AsyncServerStreamingCall;
             }
 
-            if (typeof(Delegate).IsAssignableFrom(type)) return TypeCategory.None; // yeah, that's not going to happen
-
             if (marshallerCache.CanSerializeType(type)) return TypeCategory.Data;
             bindContext?.LogWarning("Type cannot be serialized; ignoring: {0}", type.FullName);
             return TypeCategory.Invalid;

src/protobuf-net.Grpc/Internal/ProxyEmitter.cs

@@ -1,4 +1,4 @@
-using Grpc.Core;
+using Grpc.Core;
 using ProtoBuf.Grpc.Client;
 using ProtoBuf.Grpc.Configuration;
 using System;
@@ -212,7 +212,12 @@ FieldBuilder Marshaller(Type forType)
                         var shallMethodBeImplemented = isService || isMethodInherited;
                         if (!(shallMethodBeImplemented && ContractOperation.TryIdentifySignature(iMethod, binderConfig, out var op, null)))
                         {
-                            il.ThrowException(typeof(NotSupportedException));
+                            // it is frequent for some infrastructure code to always call Dispose() on IDisposable,
+                            // for instance Asp.Net Core dependency injection, so we don't want to throw in this case
+                            if (iType == typeof(IDisposable) && iMethod.Name == nameof(IDisposable.Dispose))
+                                il.Emit(OpCodes.Ret);
+                            else
+                                il.ThrowException(typeof(NotSupportedException));
                             continue;
                         }