Source generator diagnostics are not showing up in VS Quick Info

Description

For this sample:

public class Outer
{
    internal class Inner
    {
        public string? Name { get; init; }
    }

    [JsonSerializable(typeof(Inner))]
    internal partial class InnerJsonContext : JsonSerializerContext
    { }
}

[JsonSerializable(typeof(Outer.Inner))]
public partial class OuterInnerJsonContext : JsonSerializerContext
{ }

The OuterInnerJsonContext is ok, but InnerJsonContext has 3 compiler errors:

• CS0534: ‘Outer.InnerJsonContext’ does not implement inherited abstract member ‘JsonSerializerContext.GeneratedSerializerOptions.get’
• CS0534: ‘Outer.InnerJsonContext’ does not implement inherited abstract member ‘JsonSerializerContext.GetTypeInfo(Type)’
• CS7036: There is no argument given that corresponds to the required formal parameter ‘options’ of ‘JsonSerializerContext.JsonSerializerContext(JsonSerializerOptions?)’

But my requirement is make the Inner class private, because it should be hidden. So the OuterInnerJsonContext is not applicable.

I have a repro in Outer.cs showing this issue. Uncomment to see the compiler errors.

Reproduction Steps

1. Clone repro, open with Visual Studio.
2. Open Net60Tests\Outer.cs
3. Build without error, tests pass.
4. Uncomment all, then 3 errors appear on InnerJsonContext.

Expected behavior

It compiles without errors, and tests pass.

Actual behavior

InnerJsonContext has 3 compiler errors:

• CS0534: ‘Outer.InnerJsonContext’ does not implement inherited abstract member ‘JsonSerializerContext.GeneratedSerializerOptions.get’
• CS0534: ‘Outer.InnerJsonContext’ does not implement inherited abstract member ‘JsonSerializerContext.GetTypeInfo(Type)’
• CS7036: There is no argument given that corresponds to the required formal parameter ‘options’ of ‘JsonSerializerContext.JsonSerializerContext(JsonSerializerOptions?)’

Regression?

Don’t know.

Known Workarounds

Make Inner class internal instead of private, then add OuterInnerJsonContext class outside of Outer class.

Configuration

.NET 6.0, Visual Studio 2022 17.1.0 Preview 1.0.

Other information

Don’t know.

[eiriktsarpalis]

You reproduction is also producing the following warning:

CSC : warning SYSLIB1032: Derived 'JsonSerializerContext' type 'InnerJsonContext' specifies JSON-serializable types. The type and all containing types must be made partial to kick off source generation.

And that is the root of your issue. While you have declared InnerJsonContext as partial its containing class is not partial. Once I mark Outer as partial the compiler errors go away.

[terrajobst]

You reproduction is also producing the following warning:

CSC : warning SYSLIB1032: Derived 'JsonSerializerContext' type 'InnerJsonContext' specifies JSON-serializable types. The type and all containing types must be made partial to kick off source generation.

And that is the root of your issue. While you have declared InnerJsonContext as partial its containing class is not partial. Once I mark Outer as partial the compiler errors go away.

Does this indicate that this should have really been an error?