ArgumentNullException in System.Text.Json.Serialization.Metadata.JsonTypeInfo

[JakenVeina]

Description

I am receiving an ArgumentNullException from JsonSerializer.Serialize<T>(Utf8JsonWriter, T value, JsonSerializerOptions options) that appears to be the result of a faulty null-check-override within JsonTypeInfo.

runtime/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Metadata/JsonTypeInfo.cs

Line 526 in 804a933

Name = reflectionInfo.Name!,

   at System.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
   at System.OrdinalIgnoreCaseComparer.GetHashCode(String obj)
   at System.Text.Json.Serialization.Metadata.JsonTypeInfo.ParameterLookupKey.GetHashCode()
   at System.Collections.Generic.Dictionary`2.FindValue(TKey key)
   at System.Collections.Generic.Dictionary`2.TryGetValue(TKey key, TValue& value)
   at System.Text.Json.Serialization.Metadata.JsonTypeInfo.InitializeConstructorParameters(ConstructorInfo constructorInfo)
   at System.Text.Json.Serialization.Metadata.JsonTypeInfo..ctor(Type type, JsonConverter converter, Type runtimeType, JsonSerializerOptions options)
   at System.Text.Json.JsonSerializerOptions.<RootBuiltInConvertersAndTypeInfoCreator>g__CreateJsonTypeInfo|107_0(Type type, JsonSerializerOptions options)
   at System.Text.Json.JsonSerializer.GetTypeInfo(Type runtimeType, JsonSerializerOptions options)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue& value, Type runtimeType, JsonSerializerOptions options)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue value, JsonSerializerOptions options)
   at Modix.Host.EntryPoint.EndpointWriteOnlyJsonConverter.Write(Utf8JsonWriter writer, Endpoint value, JsonSerializerOptions options) in D:\Projects\JakenVeina\MODiX\MODiX.Host\EntryPoint.cs:line 90

The null value in question is coming from System.Reflection.ParameterInfo.Name, retrieved from the constructor of System.Runtime.CompilerServices.NullableContextAttribute.

The NullableContextAttribute instance is coming from Microsoft.AspNetCore.Http.Endpoint which is being passed to Microsoft.Extensions.Logging.ILogger.Log calls as TState state.

NullableContextAttribute is an internal and compiler-generated type, so it's been proving difficult to implement a workaround where I just skip or customize serialization of the type. It also strikes me as a slight design defect that all this work is being done to analyze this type for deserialization, when I am only attempting to serialize it, and have no intention of ever deserializing it.

Configuration

.NET SDK 6.0.100-preview.7.21379.14
System.Text.Json 6.0.0-preview.7.21377.19

[eiriktsarpalis]

Hi @JakenVeina, would it be possible to provide a minimal app that reproduces the issue? Thanks.

[JakenVeina]

It looks like a "minimal" reproduction might not be possible. I have replicated the scenario in a simple console program, using the same runtime and package versions, and the exception does not occur. I.E...

JsonSerializer.Serialize(writer, value, options);

...where value is a NullableContextAttribute object, which, when reflected upon, produces a ParameterInfo object with a Name value of null. This line throws in the full solution, but not in the console program. The options object is not meaningfully different between the two. I noticed there's a decent amount of static caching of JsonTypeInfo objects going on, so perhaps that's somehow the culprit?

I will attempt to clone my full application and trim as much out of it as possible, without affecting the exception that throws.

[JakenVeina]

Here we go: https://github.com/JakenVeina/DotnetRuntimeIssue58690

I identified the issue with reproducing it locally: I was inadvertently calling .Serialize<Attribute>() instead of .Serialize(), resulting in the library reflecting upon System.Attribute instead of System.Runtime.CompilerServices.NullableContextAttribute.

[eiriktsarpalis]

I can reproduce. Minimal reproduction:

using System;
using System.Reflection;
using System.Text.Json;

Type type = Assembly.GetExecutingAssembly().GetType("System.Runtime.CompilerServices.NullableContextAttribute")!;
object value = Activator.CreateInstance(type, (byte)0)!;
JsonSerializer.Serialize(value);

// Force generation of a NullableContextAttribute in this assembly
static string? MethodWithNullableAnnotations() => throw new NotImplementedException();

Throws

Unhandled exception. System.ArgumentNullException: Value cannot be null. (Parameter 'obj')
   at System.OrdinalIgnoreCaseComparer.GetHashCode(String obj)
   at System.Text.Json.Serialization.Metadata.JsonTypeInfo.ParameterLookupKey.GetHashCode()
   at System.Collections.Generic.Dictionary`2.FindValue(TKey key)
   at System.Collections.Generic.Dictionary`2.TryGetValue(TKey key, TValue& value)
   at System.Text.Json.Serialization.Metadata.JsonTypeInfo.InitializeConstructorParameters(JsonParameterInfoValues[] jsonParameters)
   at System.Text.Json.Serialization.Metadata.JsonTypeInfo..ctor(Type type, JsonConverter converter, Type runtimeType, JsonSerializerOptions options)
   at System.Text.Json.JsonSerializerOptions.<InitializeForReflectionSerializer>g__CreateJsonTypeInfo|112_0(Type type, JsonSerializerOptions options)
   at System.Text.Json.JsonSerializerOptions.GetClassFromContextOrCreate(Type type)
   at System.Text.Json.JsonSerializerOptions.GetOrAddClass(Type type)
   at System.Text.Json.JsonSerializer.GetTypeInfo(JsonSerializerOptions options, Type runtimeType)
   at System.Text.Json.JsonSerializer.Serialize[TValue](TValue value, JsonSerializerOptions options)

I did not deduce the root cause -- for some reason attempting to replicate the implementation of NullableContextAttribute in source resulted in a different type of failure much later in the implementation. We should still investigate and at least attempt to fail more gracefully if this scenario cannot be supported.

This seems like a very niche use case. Moving to 7.0.0.

[eiriktsarpalis]

Moving to Future, as we won't have time to work on this in the .NET 7 timeframe.

[eiriktsarpalis]

Root cause appears to be IL #73188 (comment) containing parameters with stripped names. Given that the linker can trim parameter names to save size we might want to add detection logic for ParameterInfo with null Name properties (and either fail gracefully or use a placeholder name like ILSpy is doing).

[ghost]

Tagging subscribers to 'linkable-framework': @eerhardt, @vitek-karas, @LakshanF, @sbomer, @joperezr
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

I am receiving an ArgumentNullException from JsonSerializer.Serialize<T>(Utf8JsonWriter, T value, JsonSerializerOptions options) that appears to be the result of a faulty null-check-override within JsonTypeInfo.

runtime/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Metadata/JsonTypeInfo.cs

Line 526 in 804a933

Name = reflectionInfo.Name!,

   at System.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
   at System.OrdinalIgnoreCaseComparer.GetHashCode(String obj)
   at System.Text.Json.Serialization.Metadata.JsonTypeInfo.ParameterLookupKey.GetHashCode()
   at System.Collections.Generic.Dictionary`2.FindValue(TKey key)
   at System.Collections.Generic.Dictionary`2.TryGetValue(TKey key, TValue& value)
   at System.Text.Json.Serialization.Metadata.JsonTypeInfo.InitializeConstructorParameters(ConstructorInfo constructorInfo)
   at System.Text.Json.Serialization.Metadata.JsonTypeInfo..ctor(Type type, JsonConverter converter, Type runtimeType, JsonSerializerOptions options)
   at System.Text.Json.JsonSerializerOptions.<RootBuiltInConvertersAndTypeInfoCreator>g__CreateJsonTypeInfo|107_0(Type type, JsonSerializerOptions options)
   at System.Text.Json.JsonSerializer.GetTypeInfo(Type runtimeType, JsonSerializerOptions options)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue& value, Type runtimeType, JsonSerializerOptions options)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue value, JsonSerializerOptions options)
   at Modix.Host.EntryPoint.EndpointWriteOnlyJsonConverter.Write(Utf8JsonWriter writer, Endpoint value, JsonSerializerOptions options) in D:\Projects\JakenVeina\MODiX\MODiX.Host\EntryPoint.cs:line 90

The null value in question is coming from System.Reflection.ParameterInfo.Name, retrieved from the constructor of System.Runtime.CompilerServices.NullableContextAttribute.

The NullableContextAttribute instance is coming from Microsoft.AspNetCore.Http.Endpoint which is being passed to Microsoft.Extensions.Logging.ILogger.Log calls as TState state.

NullableContextAttribute is an internal and compiler-generated type, so it's been proving difficult to implement a workaround where I just skip or customize serialization of the type. It also strikes me as a slight design defect that all this work is being done to analyze this type for deserialization, when I am only attempting to serialize it, and have no intention of ever deserializing it.

Configuration

.NET SDK 6.0.100-preview.7.21379.14
System.Text.Json 6.0.0-preview.7.21377.19

Author:	JakenVeina
Assignees:	eiriktsarpalis
Labels:	bug, area-System.Text.Json, linkable-framework, Priority:3
Milestone:	7.0.0