C#•8mo ago

❔ Roslyn compilation error (dynamic keyword)

Hello everyone, I'm pretty new to C# and had to start using it due to my new job. In the project i'm working on we use quite a lot of autogenerated code that is compiled using roslyn. So I decided to look at it some more and try using it in a couple example projects. But I've encountered a problem compiling code in roslyn that uses dynamic objects. The following code gives the compile error:

using System;
using System.Reflection;
using System.Runtime.CompilerServices;
using System.Dynamic;

namespace Autogenerated;
public class _t1
{
    private dynamic _wrappedObject;
    public _t1(object wrappedObject)
    {
        _wrappedObject = wrappedObject;
    }
    public void Test()
    {
        _wrappedObject.Test();
    }
    public void Some()
    {
        _wrappedObject.Some();
    }
}

using System;
using System.Reflection;
using System.Runtime.CompilerServices;
using System.Dynamic;

namespace Autogenerated;
public class _t1
{
    private dynamic _wrappedObject;
    public _t1(object wrappedObject)
    {
        _wrappedObject = wrappedObject;
    }
    public void Test()
    {
        _wrappedObject.Test();
    }
    public void Some()
    {
        _wrappedObject.Some();
    }
}

And the error message is:

(9,13): error CS1980: Cannot define a class or member that utilizes 'dynamic' because the compiler required type 'System.Runtime.CompilerServices.DynamicAttribute' cannot be found. Are you missing a reference?

(9,13): error CS1980: Cannot define a class or member that utilizes 'dynamic' because the compiler required type 'System.Runtime.CompilerServices.DynamicAttribute' cannot be found. Are you missing a reference?

7 Replies

mtreit•8mo ago

That code compiles fine for me, you've got something else going on. What version of .NET are you targeting?

soziapath•8mo ago

It compiles fine itself, but as soon as I try compile it CSharpCompilation it fails. But home atm, but as soon as I am I can send the compilation code. I tried .NET 6, 7 and 8 with the same result. Just created a new program to test it, same thing:

using System;
using System.IO;
using System.Reflection;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.Emit;

class Program
{
  static void Main()
  {
    string sourceCode = @"
      using System;
      using System.Reflection;
      using System.Runtime.CompilerServices;

      namespace Autogenerated;
      public class _t1
      {
          private dynamic _wrappedObject;
          public _t1(object wrappedObject)
          {
              _wrappedObject = wrappedObject;
          }
          public void Test()
          {
              _wrappedObject.Test();
          }
          public void Some()
          {
              _wrappedObject.Some();
          }
      };";
    SyntaxTree syntaxTree = CSharpSyntaxTree.ParseText(sourceCode);

    string assemblyName = "MyAssembly.dll";
    MetadataReference[] references = new MetadataReference[]
    {
            MetadataReference.CreateFromFile(typeof(object).Assembly.Location),
            MetadataReference.CreateFromFile(typeof(Console).Assembly.Location),
    };

    CSharpCompilation compilation = CSharpCompilation.Create(assemblyName)
        .WithOptions(new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary))
        .AddReferences(references)
        .AddSyntaxTrees(syntaxTree);

    using (var ms = new MemoryStream())
    {
      EmitResult emitResult = compilation.Emit(ms);

      if (emitResult.Success)
      {
        ms.Seek(0, SeekOrigin.Begin);

        var assembly = Assembly.Load(ms.ToArray());
        Type programType = assembly.GetType("Program");
        MethodInfo mainMethod = programType.GetMethod("Main");
        mainMethod.Invoke(null, null);
      }
      else
      {
        foreach (var diagnostic in emitResult.Diagnostics)
        {
          Console.WriteLine(diagnostic);
        }
      }
    }
  }
}

using System;
using System.IO;
using System.Reflection;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.Emit;

class Program
{
  static void Main()
  {
    string sourceCode = @"
      using System;
      using System.Reflection;
      using System.Runtime.CompilerServices;

      namespace Autogenerated;
      public class _t1
      {
          private dynamic _wrappedObject;
          public _t1(object wrappedObject)
          {
              _wrappedObject = wrappedObject;
          }
          public void Test()
          {
              _wrappedObject.Test();
          }
          public void Some()
          {
              _wrappedObject.Some();
          }
      };";
    SyntaxTree syntaxTree = CSharpSyntaxTree.ParseText(sourceCode);

    string assemblyName = "MyAssembly.dll";
    MetadataReference[] references = new MetadataReference[]
    {
            MetadataReference.CreateFromFile(typeof(object).Assembly.Location),
            MetadataReference.CreateFromFile(typeof(Console).Assembly.Location),
    };

    CSharpCompilation compilation = CSharpCompilation.Create(assemblyName)
        .WithOptions(new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary))
        .AddReferences(references)
        .AddSyntaxTrees(syntaxTree);

    using (var ms = new MemoryStream())
    {
      EmitResult emitResult = compilation.Emit(ms);

      if (emitResult.Success)
      {
        ms.Seek(0, SeekOrigin.Begin);

        var assembly = Assembly.Load(ms.ToArray());
        Type programType = assembly.GetType("Program");
        MethodInfo mainMethod = programType.GetMethod("Main");
        mainMethod.Invoke(null, null);
      }
      else
      {
        foreach (var diagnostic in emitResult.Diagnostics)
        {
          Console.WriteLine(diagnostic);
        }
      }
    }
  }
}

Angius•8mo ago

Jesus, seeing this thread I thought it's an issue with source generators... turns out it's an issue with compiling a string...? Who-wee

soziapath•8mo ago

sorry to disappoint you...

Angius•8mo ago

Nah, I'm not disappointed, it's more like... seeing someone drive a car with square wheels lol, my condolences that you have to work with a codebase like that

soziapath•8mo ago

Yeah, it's not the nicest to work with, but at least it's paid well^^

Accord•8mo ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Roslyn compilation error (dynamic keyword)