System.Text.Json does not correctly handle nested inner types of a generic outer type.

[333fred]

Description

I'm seeing an ArgumentOutOfRange exception when attempting to use the System.Text.Json source generator in my project. This appears to be when a field or property of a type to be generated is of the form OuterType<T>.Inner.

Reproduction Steps

Attempt to compile the following code:

using System.Text.Json.Serialization;

public class Outer<T>
{
    public class Inner { }
}

public class C
{
    public Outer<int>.Inner I { get; set; }
}

[JsonSerializable(typeof(C))]
public partial class Context : JsonSerializerContext
{
}

Expected behavior

The code compiles.

Actual behavior

CSC : warning CS8785: Generator 'JsonSourceGenerator' failed to generate source. It will not contribute to the output and compilation errors may occur as a result. Exception was of type 'ArgumentOutOfRangeException' with message 'Length cannot be less than zero. (Parameter 'length')' [C:\Users\333fr\Documents\git\omnisharp-roslyn\src\OmniSharp.Abstractions\OmniSharp.Abstractions.csproj]

Followed by errors from lack of partial type implementation.

Regression?

No response

Known Workarounds

No response

Configuration

.NET 6.0.100.

Other information

No response

[ghost]

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Issue Details

---

Description

I'm seeing an ArgumentOutOfRange exception when attempting to use the System.Text.Json source generator in my project. This appears to be when a field or property of a type to be generated is of the form OuterType<T>.Inner.

Reproduction Steps

Attempt to compile the following code:

using System.Text.Json.Serialization;

public class Outer<T>
{
    public class Inner { }
}

public class C
{
    public Outer<int>.Inner I { get; set; }
}

[JsonSerializable(typeof(C))]
public partial class Context : JsonSerializerContext
{
    public static string Implicit => "World";
}

Expected behavior

The code compiles.

Actual behavior

CSC : warning CS8785: Generator 'JsonSourceGenerator' failed to generate source. It will not contribute to the output and compilation errors may occur as a result. Exception was of type 'ArgumentOutOfRangeException' with message 'Length cannot be less than zero. (Parameter 'length')' [C:\Users\333fr\Documents\git\omnisharp-roslyn\src\OmniSharp.Abstractions\OmniSharp.Abstractions.csproj]

Followed by errors from lack of partial type implementation.

Regression?

No response

Known Workarounds

No response

Configuration

.NET 6.0.100.

Other information

No response

Author:	333fred
Assignees:	-
Labels:	area-System.Text.Json, untriaged
Milestone:	-

[layomia]

This is a bug with correctly generating the full name of some generic types. The full name is used as part of generator's infrastructure for processing serializable types. This bug should be fixed and considered for 6.0 since we have no control of input object graphs and it would be difficult to communicate what's working vs not.

[layomia]

The fix for this issue should verify correctness for these scenarios:

• System.Text.Json SourceGenerator crashes if context is an inner class of a generic type #66881
• System.Text.Json SourceGenerator behaves oddly if context is generic #66880

We'll target 7.0 for a fix here. A community contribution/fix here is welcome.

[eiriktsarpalis]

Moving to .NET 8 milestone.

[krwq]

This is fixed with #71619