NDLRGEN002: Referenced assembly has internal plugin types but no type registry¶

Cause¶

A referenced assembly contains internal types that implement Needlr plugin interfaces (e.g., IServiceCollectionPlugin), but the assembly does not have a [GenerateTypeRegistry] attribute.

Rule Description¶

When using source generation, internal plugin types in referenced assemblies cannot be discovered by the host application's generator. This means internal plugins will silently fail to load at runtime.

This error proactively detects this misconfiguration at compile time, preventing runtime failures.

Plugin Interfaces Checked¶

The generator checks for internal types implementing any of these interfaces:

NexusLabs.Needlr.IServiceCollectionPlugin
NexusLabs.Needlr.IPostBuildServiceCollectionPlugin
NexusLabs.Needlr.IWebApplicationPlugin
NexusLabs.Needlr.IWebApplicationBuilderPlugin
NexusLabs.Needlr.SignalR.IHubRegistrationPlugin
NexusLabs.Needlr.SemanticKernel.IKernelBuilderPlugin

How to Fix¶

You have two options:

Option 1: Add [GenerateTypeRegistry] to the Plugin Assembly¶

Add the [GenerateTypeRegistry] attribute to the assembly containing the internal plugin:

// In the plugin assembly (e.g., MyPlugin project)
using NexusLabs.Needlr.Generators;

[assembly: GenerateTypeRegistry(IncludeNamespacePrefixes = new[] { "MyPlugin" })]

namespace MyPlugin
{
    internal class MyPlugin : IServiceCollectionPlugin
    {
        public void Configure(ServiceCollectionPluginOptions options) { }
    }
}

Option 2: Make the Plugin Type Public¶

If the plugin can be made public, change its accessibility:

namespace MyPlugin
{
    public class MyPlugin : IServiceCollectionPlugin
    {
        public void Configure(ServiceCollectionPluginOptions options) { }
    }
}

When to Suppress¶

Only suppress this error if you intentionally don't want the plugin to be discovered:

#pragma warning disable NDLRGEN002
// Intentionally keeping this plugin internal and unregistered
#pragma warning restore NDLRGEN002

Example¶

Code with Error¶

// HostApp project
using NexusLabs.Needlr.Generators;

[assembly: GenerateTypeRegistry]

// MyPlugin project (referenced by HostApp) - NO [GenerateTypeRegistry]
namespace MyPlugin
{
    internal class AuthenticationPlugin : IWebApplicationBuilderPlugin
    {
        public void Configure(WebApplicationBuilderPluginOptions options)
        {
            options.Builder.Services.AddAuthentication();
        }
    }
}

Result: NDLRGEN002 error - AuthenticationPlugin will not be discovered at runtime.

Fixed Code¶

// MyPlugin project - WITH [GenerateTypeRegistry]
using NexusLabs.Needlr.Generators;

[assembly: GenerateTypeRegistry(IncludeNamespacePrefixes = new[] { "MyPlugin" })]

namespace MyPlugin
{
    internal class AuthenticationPlugin : IWebApplicationBuilderPlugin
    {
        public void Configure(WebApplicationBuilderPluginOptions options)
        {
            options.Builder.Services.AddAuthentication();
        }
    }
}

Multi-Project Solutions¶

For solutions with many plugin projects, consider using MSBuild conventions to automatically add [GenerateTypeRegistry] to matching projects. See Advanced Usage - Multi-Project Solutions for details.