Trimming & Native AOT Warnings (`[RequiresUnreferencedCode]`)

1Concept

Modern .NET trimmers strip unused metadata to produce small Native AOT binaries. Reflection patterns that inspect unreferenced types require `[RequiresUnreferencedCode]` and `[DynamicallyAccessedMembers]` annotations to prevent trimmer stripping.

2Architecture Diagram

Native AOT Compiler
       │
   Scans Code Graph ──> Unreferenced Type stripped to save binary size!
       │
   Caller attempts Reflection ──> Crashes at runtime if not annotated!

3Code Example

using System;
using System.Diagnostics.CodeAnalysis;

public class AotTrimmingDemo
{
    [RequiresUnreferencedCode("Uses reflection to serialize types dynamically.")]
    public static void SerializeDynamic(object data)
    {
        Console.WriteLine($"Serializing: {data.GetType().Name}");
    }

    public static void Main()
    {
        SerializeDynamic("SampleString");
    }
}

4Expected Output

Serializing: String

5Key Takeaways

• ✓Annotate dynamic reflection methods with `[RequiresUnreferencedCode]`.
• ✓Use `[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicProperties)]` on Type parameters.
• ✓Prefer Roslyn Source Generators to achieve 100% Native AOT compatibility.