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NDLRCOR004: Injectable type in global namespace may not be discovered

Cause

A type that appears to be designed for dependency injection is defined in the global namespace (no namespace declaration), but the assembly's [GenerateTypeRegistry] attribute has IncludeNamespacePrefixes set to values that don't include an empty string ("").

Rule Description

When using Needlr's source generation with namespace filtering, types in the global namespace are excluded by default. This is because:

  1. Namespace filtering is exact prefix matching: If you set IncludeNamespacePrefixes = new[] { "MyCompany" }, only types in namespaces starting with MyCompany. are included.

  2. Global namespace has no prefix: Types without a namespace declaration have no namespace to match against.

  3. Silent exclusion: Unlike a compile error, these types are silently skipped during type discovery.

This analyzer detects types that:

  • Are in the global namespace
  • Appear to be injectable (have DI attributes, implement interfaces, or have constructor dependencies)
  • Would be excluded by the current IncludeNamespacePrefixes configuration
// ⚠️ This triggers the warning
[assembly: GenerateTypeRegistry(IncludeNamespacePrefixes = new[] { "MyCompany" })]

public class AmplitudeConfiguration  // No namespace! Won't be discovered!
{
    public string ApiKey { get; set; }
}

How to Fix

Move the type into an appropriate namespace:

namespace MyCompany.Telemetry
{
    public class AmplitudeConfiguration
    {
        public string ApiKey { get; set; }
    }
}

Option 2: Include Global Namespace in Prefixes

Add an empty string "" to your IncludeNamespacePrefixes to explicitly include global namespace types:

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

This tells Needlr: "Include types in MyCompany.* namespaces AND types in the global namespace."

Option 3: Mark as Not Injectable

If the type shouldn't be registered with DI, add [DoNotInject] or [DoNotAutoRegister]:

[DoNotInject]
public class AmplitudeConfiguration { }

Impact if Ignored

If you ignore this warning:

  1. Runtime exception: Services depending on the undiscovered type will throw InvalidOperationException: 

    System.InvalidOperationException: No service for type 'AmplitudeConfiguration' has been registered.

  2. Silent failures: The application may start but fail when the missing type is first requested.

  3. Debugging difficulty: The root cause isn't obvious since there's no compile error.

Why This Happens

This commonly occurs when:

  1. MSBuild conventions auto-set prefixes: Some build configurations automatically set IncludeNamespacePrefixes based on the project name.

  2. Copy-paste errors: Types copied from examples or templates may lack namespace declarations.

  3. Migration from reflection: Reflection-based discovery scanned all types regardless of namespace. Source generation requires explicit configuration.

Detection Criteria

This analyzer reports a warning when ALL of these conditions are true:

  1. The type is in the global namespace
  2. The assembly has [GenerateTypeRegistry] with IncludeNamespacePrefixes set
  3. IncludeNamespacePrefixes doesn't include "" (empty string)
  4. The type is NOT marked with [DoNotInject] or [DoNotAutoRegister]

  5. The type appears injectable:

  6. Has a lifetime attribute ([Singleton], [Scoped], [Transient])

  7. Implements one or more interfaces
  8. Has a constructor with interface/abstract class parameters

When to Suppress

Suppress this warning if:

  • The type is intentionally not registered with DI
  • You're manually registering the type elsewhere
  • The type is only used as a data transfer object (DTO)
#pragma warning disable NDLRCOR004
public class MyGlobalType { }  // Not intended for DI
#pragma warning restore NDLRCOR004

Or in your project file: 

<NoWarn>$(NoWarn);NDLRCOR004</NoWarn>

See Also