System.Text.Json is adding EqualityContract properties metadata for records

[Sergio0694]

Description

Possible regression from #58136, cc. @eiriktsarpalis.

"Records contains a property "EqualityContract" of type Type. This leads to the generator generating serializers for many of the reflection related types as for example Type, ConstructorInfo, MethodInfo, Assembly, Module, etc."

Reproduction Steps

Paste the following code:

public sealed record Test;

[JsonSerializable(typeof(Test))]
public sealed partial class MyTestContext : JsonSerializerContext
{
}

Expected behavior

The generated code for Test should not include the "EqualityContract" property.

Actual behavior

// <auto-generated/>

#nullable enable annotations
#nullable disable warnings

// Suppress warnings about [Obsolete] member usage in generated code.
#pragma warning disable CS0618

namespace MyTestProject
{
    public sealed partial class MyTestContext
    {
        private global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::MyTestProject.Test>? _Test;
        /// <summary>
        /// Defines the source generated JSON serialization contract metadata for a given type.
        /// </summary>
        public global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::MyTestProject.Test> Test
        {
            get => _Test ??= Create_Test(Options);
        }
        
        // Intentionally not a static method because we create a delegate to it. Invoking delegates to instance
        // methods is almost as fast as virtual calls. Static methods need to go through a shuffle thunk.
        private global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::MyTestProject.Test> Create_Test(global::System.Text.Json.JsonSerializerOptions options)
        {
            global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::MyTestProject.Test>? jsonTypeInfo = null;
            global::System.Text.Json.Serialization.JsonConverter? customConverter;
            if (options.Converters.Count > 0 && (customConverter = GetRuntimeProvidedCustomConverter(options, typeof(global::MyTestProject.Test))) != null)
            {
                jsonTypeInfo = global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateValueInfo<global::MyTestProject.Test>(options, customConverter);
            }
            else
            {
                global::System.Text.Json.Serialization.Metadata.JsonObjectInfoValues<global::MyTestProject.Test> objectInfo = new global::System.Text.Json.Serialization.Metadata.JsonObjectInfoValues<global::MyTestProject.Test>()
                {
                    ObjectCreator = static () => new global::MyTestProject.Test(),
                    ObjectWithParameterizedConstructorCreator = null,
                    PropertyMetadataInitializer = _ => TestPropInit(options),
                    ConstructorParameterMetadataInitializer = null,
                    NumberHandling = default,
                    SerializeHandler = TestSerializeHandler
                };
        
                jsonTypeInfo = global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateObjectInfo<global::MyTestProject.Test>(options, objectInfo);
            }
        
            return jsonTypeInfo;
        }
        
        private static global::System.Text.Json.Serialization.Metadata.JsonPropertyInfo[] TestPropInit(global::System.Text.Json.JsonSerializerOptions options)
        {
            global::System.Text.Json.Serialization.Metadata.JsonPropertyInfo[] properties = new global::System.Text.Json.Serialization.Metadata.JsonPropertyInfo[1];
        
            global::System.Text.Json.Serialization.Metadata.JsonPropertyInfoValues<global::System.Type> info0 = new global::System.Text.Json.Serialization.Metadata.JsonPropertyInfoValues<global::System.Type>()
            {
                IsProperty = true,
                IsPublic = false,
                IsVirtual = false,
                DeclaringType = typeof(global::MyTestProject.Test),
                Converter = null,
                Getter = null,
                Setter = null,
                IgnoreCondition = null,
                HasJsonInclude = false,
                IsExtensionData = false,
                NumberHandling = default,
                PropertyName = "EqualityContract",
                JsonPropertyName = null
            };
        
            global::System.Text.Json.Serialization.Metadata.JsonPropertyInfo propertyInfo0 = global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreatePropertyInfo<global::System.Type>(options, info0);
            properties[0] = propertyInfo0;
        
            return properties;
        }
        
        private void TestSerializeHandler(global::System.Text.Json.Utf8JsonWriter writer, global::MyTestProject.Test? value)
        {
            if (value == null)
            {
                writer.WriteNullValue();
                return;
            }
        
            writer.WriteStartObject();
        
            writer.WriteEndObject();
        }
    }
}

Regression?

Seems like it might be the case, yes. I'm using 7.0.0-rc.2.22472.3.

Known Workarounds

None.

Configuration

.NET Standard 2.0 class library, using System.Text.Json 7.0.0-rc.2.22472.3.

[ghost]

Tagging subscribers to this area: @dotnet/area-system-text-json, @gregsdennis
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

Possible regression from #58136, cc. @eiriktsarpalis.

"Records contains a property "EqualityContract" of type Type. This leads to the generator generating serializers for many of the reflection related types as for example Type, ConstructorInfo, MethodInfo, Assembly, Module, etc."

Reproduction Steps

Paste the following code:

public sealed record Test;

[JsonSerializable(typeof(Test))]
public sealed partial class DAJsonSerializerContext : JsonSerializerContext
{
}

### Expected behavior

The generated code for `Test` should not include the "EqualityContract" property.

### Actual behavior

```csharp
// <auto-generated/>

#nullable enable annotations
#nullable disable warnings

// Suppress warnings about [Obsolete] member usage in generated code.
#pragma warning disable CS0618

namespace MyTestProject
{
    public sealed partial class DAJsonSerializerContext
    {
        private global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::MyTestProject.Test>? _Test;
        /// <summary>
        /// Defines the source generated JSON serialization contract metadata for a given type.
        /// </summary>
        public global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::MyTestProject.Test> Test
        {
            get => _Test ??= Create_Test(Options);
        }
        
        // Intentionally not a static method because we create a delegate to it. Invoking delegates to instance
        // methods is almost as fast as virtual calls. Static methods need to go through a shuffle thunk.
        private global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::MyTestProject.Test> Create_Test(global::System.Text.Json.JsonSerializerOptions options)
        {
            global::System.Text.Json.Serialization.Metadata.JsonTypeInfo<global::MyTestProject.Test>? jsonTypeInfo = null;
            global::System.Text.Json.Serialization.JsonConverter? customConverter;
            if (options.Converters.Count > 0 && (customConverter = GetRuntimeProvidedCustomConverter(options, typeof(global::MyTestProject.Test))) != null)
            {
                jsonTypeInfo = global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateValueInfo<global::MyTestProject.Test>(options, customConverter);
            }
            else
            {
                global::System.Text.Json.Serialization.Metadata.JsonObjectInfoValues<global::MyTestProject.Test> objectInfo = new global::System.Text.Json.Serialization.Metadata.JsonObjectInfoValues<global::MyTestProject.Test>()
                {
                    ObjectCreator = static () => new global::MyTestProject.Test(),
                    ObjectWithParameterizedConstructorCreator = null,
                    PropertyMetadataInitializer = _ => TestPropInit(options),
                    ConstructorParameterMetadataInitializer = null,
                    NumberHandling = default,
                    SerializeHandler = TestSerializeHandler
                };
        
                jsonTypeInfo = global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreateObjectInfo<global::MyTestProject.Test>(options, objectInfo);
            }
        
            return jsonTypeInfo;
        }
        
        private static global::System.Text.Json.Serialization.Metadata.JsonPropertyInfo[] TestPropInit(global::System.Text.Json.JsonSerializerOptions options)
        {
            global::System.Text.Json.Serialization.Metadata.JsonPropertyInfo[] properties = new global::System.Text.Json.Serialization.Metadata.JsonPropertyInfo[1];
        
            global::System.Text.Json.Serialization.Metadata.JsonPropertyInfoValues<global::System.Type> info0 = new global::System.Text.Json.Serialization.Metadata.JsonPropertyInfoValues<global::System.Type>()
            {
                IsProperty = true,
                IsPublic = false,
                IsVirtual = false,
                DeclaringType = typeof(global::MyTestProject.Test),
                Converter = null,
                Getter = null,
                Setter = null,
                IgnoreCondition = null,
                HasJsonInclude = false,
                IsExtensionData = false,
                NumberHandling = default,
                PropertyName = "EqualityContract",
                JsonPropertyName = null
            };
        
            global::System.Text.Json.Serialization.Metadata.JsonPropertyInfo propertyInfo0 = global::System.Text.Json.Serialization.Metadata.JsonMetadataServices.CreatePropertyInfo<global::System.Type>(options, info0);
            properties[0] = propertyInfo0;
        
            return properties;
        }
        
        private void TestSerializeHandler(global::System.Text.Json.Utf8JsonWriter writer, global::MyTestProject.Test? value)
        {
            if (value == null)
            {
                writer.WriteNullValue();
                return;
            }
        
            writer.WriteStartObject();
        
            writer.WriteEndObject();
        }
    }
}

Regression?

Seems like it might be the case, yes. I'm using 7.0.0-rc.2.22472.3.

Known Workarounds

None.

Configuration

.NET Standard 2.0 class library, using System.Text.Json 7.0.0-rc.2.22472.3.

Other information

No response

Author:	Sergio0694
Assignees:	-
Labels:	area-System.Text.Json
Milestone:	-

[layomia]

I was able to repro. Just to explicitly state the distinction here vs #58136:

We do have a change where the "EqualityContract" property is included in the list of JsonPropertyInfoValues when creating JsonTypeInfo instances for record types, but unlike the other issue we are not generating metadata for System.Type's members. The change in generated output should have minimal impact to assembly size, and has no impact to actual JSON (de)serialization AFAICT. Thus I don't think it needs to be addressed for .NET 7.

cc @krwq @eiriktsarpalis do you know why this property is being added (say a side effect of contract generation changes in 7.0)?

[eiriktsarpalis]

I checked and it seems this property is also being added in .NET 6, so based on the feedback in #58136 there might have been a change/regression in .NET 6 GA. Further investigation is needed to determine if and why such a change was made.

[eiriktsarpalis]

Related to #66679, as they both seem to stem from us not honoring protected accessibility modifiers (EqualityContract is a compiler-generated protected property).

[Sergio0694]

@eiriktsarpalis Just for additional context, this is also one of the group of issues we're hitting in the Microsoft Store, should we add partner-impact here too so that they're all better classified with respect this? Thank you! 😄