Merge pull request MessagePack-CSharp#1314 from AArnott/fix1308

Skip setting fields when the ctor already took the value

src/MessagePack.UnityClient/Assets/Scripts/MessagePack/Resolvers/DynamicObjectResolver.cs

@@ -953,7 +953,7 @@ private static void BuildDeserializeInternalAssignFieldFromLocalVariableStringKe
         {
             foreach (var item in infoList)
             {
-                if (item.MemberInfo == null || item.IsInitializedLocalVariable == null)
+                if (item.MemberInfo == null || item.IsInitializedLocalVariable == null || item.MemberInfo.IsWrittenByConstructor)
                 {
                     continue;
                 }
@@ -995,6 +995,11 @@ private static void BuildDeserializeInternalAssignFieldFromLocalVariableIntKey(O
                     continue;
                 }
 
+                if (item.MemberInfo.IsWrittenByConstructor)
+                {
+                    continue;
+                }
+
                 // if (length <= key) { goto MEMBER_ASSIGNMENT_DONE; }
                 il.EmitLdloc(localLength);
                 il.EmitLdc_I4(key);
@@ -1786,7 +1791,7 @@ EmittableMember CreateEmittableMember(MemberInfo m)
                         {
                             FieldInfo = field,
                             IsReadable = allowPrivate || field.IsPublic,
-                            IsWritable = (allowPrivate || field.IsPublic) && !field.IsInitOnly,
+                            IsWritable = allowPrivate || (field.IsPublic && !field.IsInitOnly),
                         };
                         break;
                     default:
@@ -2066,7 +2071,14 @@ EmittableMember CreateEmittableMember(MemberInfo m)
             }
 
             var shouldUseFormatterResolver = false;
-            var membersArray = members.Where(m => m.IsExplicitContract || constructorParameters.Any(p => p.MemberInfo.Equals(m)) || m.IsWritable).ToArray();
+
+            // Mark each member that will be set by way of the constructor.
+            foreach (var item in constructorParameters)
+            {
+                item.MemberInfo.IsWrittenByConstructor = true;
+            }
+
+            var membersArray = members.Where(m => m.IsExplicitContract || m.IsWrittenByConstructor || m.IsWritable).ToArray();
             foreach (var member in membersArray)
             {
                 if (IsOptimizeTargetType(member.Type))
@@ -2219,6 +2231,8 @@ public bool IsField
 
             public bool IsWritable { get; set; }
 
+            public bool IsWrittenByConstructor { get; set; }
+
             /// <summary>
             /// Gets a value indicating whether the property can only be set by an object initializer, a constructor, or another `init` member.
             /// </summary>

src/MessagePack.UnityClient/Assets/Scripts/Tests/ShareTests/DataContractTest.cs

@@ -10,13 +10,20 @@
 using System.Threading.Tasks;
 using MessagePack.Resolvers;
 using Xunit;
+using Xunit.Abstractions;
 
 namespace MessagePack.Tests
 {
 #if !ENABLE_IL2CPP
-
     public class DataContractTest
     {
+        private readonly ITestOutputHelper logger;
+
+        public DataContractTest(ITestOutputHelper logger)
+        {
+            this.logger = logger;
+        }
+
         [DataContract]
         public class MyClass
         {
@@ -67,6 +74,23 @@ public class ClassWithPublicMembersWithoutAttributes
             public int IgnoredField;
         }
 
+        [DataContract]
+        public class ClassWithPrivateReadonlyDictionary
+        {
+            [DataMember(Name = "Key", Order = 0, EmitDefaultValue = false)]
+            private readonly Guid? key;
+
+            [DataMember(Name = "Body", Order = 1, EmitDefaultValue = false)]
+            private readonly Dictionary<string, object> body = new Dictionary<string, object>();
+
+            public ClassWithPrivateReadonlyDictionary(Guid? key)
+            {
+                this.key = key;
+            }
+
+            internal Dictionary<string, object> GetBody() => this.body;
+        }
+
         [Fact]
         public void SerializeOrder()
         {
@@ -203,6 +227,32 @@ private static T DataContractSerializerRoundTrip<T>(T value)
             ms.Position = 0;
             return (T)dcs.ReadObject(ms);
         }
+
+        [Fact]
+        public void DeserializeTypeWithPrivateReadonlyDictionary()
+        {
+            var before = new ClassWithPrivateReadonlyDictionary(Guid.NewGuid());
+            before.GetBody()["name"] = "my name";
+            byte[] bytes = MessagePackSerializer.Serialize(before, StandardResolverAllowPrivate.Options);
+            string json = MessagePackSerializer.ConvertToJson(bytes); // just for check that json has _body' values.
+            this.logger.WriteLine(json);
+
+            var after = MessagePackSerializer.Deserialize<ClassWithPrivateReadonlyDictionary>(bytes, StandardResolverAllowPrivate.Options);
+            Assert.Equal("my name", after.GetBody()["name"]);
+        }
+
+        [Fact]
+        public void DeserializeTypeWithPrivateReadonlyDictionary_DCS()
+        {
+            var before = new ClassWithPrivateReadonlyDictionary(Guid.NewGuid());
+            before.GetBody()["name"] = "my name";
+            DataContractSerializer dcs = new DataContractSerializer(typeof(ClassWithPrivateReadonlyDictionary));
+            var ms = new MemoryStream();
+            dcs.WriteObject(ms, before);
+            ms.Position = 0;
+            var after = (ClassWithPrivateReadonlyDictionary)dcs.ReadObject(ms);
+            Assert.Equal("my name", after.GetBody()["name"]);
+        }
     }
 
 #endif