NDLRCOR010: IEnumerable has no discovered implementations¶

Cause¶

A constructor parameter of type IEnumerable<T> references an interface T that has no implementations discovered by source generation.

Rule Description¶

When using source generation with [assembly: GenerateTypeRegistry], Needlr scans your codebase to discover injectable types. This analyzer detects when an IEnumerable<T> dependency references an interface with no discovered implementations.

// ⚠️ NDLRCOR010: No implementations of IPlugin discovered
public class PluginHost(IEnumerable<IPlugin> plugins)
{
    // plugins will be empty unless registered via reflection
}

This is an informational diagnostic (not a warning or error) because:

Implementations may be registered via reflection at runtime
Implementations may come from a third-party library
Implementations may be registered manually in an IServiceCollectionPlugin
An empty collection is valid in some scenarios

How to Fix¶

Option 1: Add Implementations¶

Create classes that implement the interface:

public interface IPlugin { }

// ✅ These will be discovered and registered
public class LoggingPlugin : IPlugin { }
public class CachingPlugin : IPlugin { }
public class MetricsPlugin : IPlugin { }

Option 2: Ensure Namespace Matches¶

Make sure implementations are in a namespace matching your IncludeNamespacePrefixes:

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

namespace MyApp.Plugins  // ✅ Matches prefix
{
    public class MyPlugin : IPlugin { }
}

namespace ThirdParty.Plugins  // ❌ Won't be discovered
{
    public class ExternalPlugin : IPlugin { }
}

Option 3: Register Manually via Plugin¶

For external implementations:

public class ExternalPluginRegistration : IServiceCollectionPlugin
{
    public void Configure(IServiceCollection services)
    {
        services.AddSingleton<IPlugin, ThirdPartyPlugin>();
    }
}

Option 4: Suppress the Diagnostic¶

If empty collections are expected:

#pragma warning disable NDLRCOR010
public class PluginHost(IEnumerable<IOptionalPlugin> plugins)
#pragma warning restore NDLRCOR010
{
    // Empty collection is valid here
}

Or suppress project-wide in .editorconfig:

# .editorconfig
[*.cs]
dotnet_diagnostic.NDLRCOR010.severity = none

When This Analyzer Activates¶

This analyzer only runs when: 1. [assembly: GenerateTypeRegistry] is present 2. The IEnumerable<T> parameter uses an interface type (not a concrete class) 3. The interface is not a framework type (System., Microsoft.)

Severity Levels¶

Level	Meaning
`info` (default)	Informational hint in IDE
`warning`	Promote to build warning
`error`	Fail the build
`none`	Disable completely

Configure in .editorconfig:

# Promote to warning for stricter validation
dotnet_diagnostic.NDLRCOR010.severity = warning