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Showing content from https://github.com/dotnet/runtime/issues/84260 below:

JsonSerializer.Serialize overloads accepting `JsonSerializerContext` don't support unspeakable types. · Issue #84260 · dotnet/runtime · GitHub

When using the System.Text.Json source generator, attempting to serialize a compiler-generated instance of IAsyncEnumerable<T> throws an exception saying a TypeInfo could not be found.

using System.Text.Json;
using System.Text.Json.Serialization;

var stream = new MemoryStream();
var todos = GetTodosAsync(10);
await JsonSerializer.SerializeAsync(stream, todos, todos.GetType(), AppJsonSerializerContext.Default);

async IAsyncEnumerable<Todo> GetTodosAsync(int count)
{
    for (int i = 0; i < count; i++)
    {
        await Task.Delay(10);
        yield return new Todo { Id = i, Name = $"Todo {i}" };
    }
}

class Todo
{
    public int Id { get; set; }
    public string? Name { get; set; }
}

[JsonSerializable(typeof(IAsyncEnumerable<Todo>))]
internal partial class AppJsonSerializerContext : JsonSerializerContext
{

}

The result gets serialized.

An exception is thrown:

System.InvalidOperationException
  HResult=0x80131509
  Message=JsonTypeInfo metadata for type 'Program+<<<Main>$>g__GetTodosAsync|0_0>d' was not provided by TypeInfoResolver of type 'AppJsonSerializerContext'. If using source generation, ensure that all root types passed to the serializer have been annotated with 'JsonSerializableAttribute', along with any types that might be serialized polymorphically.
  Source=System.Text.Json
  StackTrace:
   at System.Text.Json.ThrowHelper.ThrowInvalidOperationException_NoMetadataForType(Type type, IJsonTypeInfoResolver resolver) in /_/src/libraries/System.Text.Json/src/System/Text/Json/ThrowHelper.Serialization.cs:line 743
   at System.Text.Json.JsonSerializer.GetTypeInfo(JsonSerializerContext context, Type inputType) in /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializer.Helpers.cs:line 50
   at System.Text.Json.JsonSerializer.Serialize(Object value, Type inputType, JsonSerializerContext context) in /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializer.Write.String.cs:line 152
   at Program.<Main>$(String[] args) in C:\Users\damia\source\repos\JsonAsyncEnumerable\JsonAsyncEnumerable\Program.cs:line 5

No, but this was expected to work after the recent changes to support unspeakable types in the JSON source generator.

None.

SDK version: 8.0.100-preview.3.23178.7
Runtime version: 8.0.0-preview.3.23174.8
OS: Windows 11 x64 22H2

No response

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