Not getting a namespace/reference in CSharpCompilation .net Core

Question

I have a project that uses some dynamically compiled code and I am upgrading from .net framework to .net core 3.1.

I can't get a simple test case to include newtonsoft.json.dll and get the error "Type or namespace name 'Newtonsoft' could not be found. I had a similar problem when I first tried add the library, but got past it by using the currently loaded assemblies (Can't include Newtonsoft JSON in CSharpCodeProvider script). With "Core" I don't get errors about a library, but it doesn't know the type, like it didn't get loaded.

I tried both using the project libraries (commented out) and specifying them directly, but have the same issue. To recreate, make a new .netCore 3.1 console application called "TestScript" and install nuget packages "Microsoft.CodeAnalysis.CSharp.Scripting" v 3.7.0, "Newtonsoft.Json" v12.0.3 and use the following code.

using System;
using System.IO;
using System.Linq;
using System.Collections.Generic;
using System.Reflection;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using System.Diagnostics;
using Newtonsoft.Json.Linq;

namespace TestScript
{  
  class Program
  {
    public static void Example1()
    {
      var assemblyName = "UserScript";
      var code = @"namespace UserScript
                { 
                  using System;
                  using System.IO;
                  using System.Collections.Generic;
                  using Newtonsoft.Json.Linq;
                  public class RunScript
                  {
                    private const int x = 99;
                    public int Eval()
                    {
                      JObject j = new JObject();
                      return x; 
                    }
                  }
                }";

      SyntaxTree syntaxTree = CSharpSyntaxTree.ParseText(code);
      var references = new List<MetadataReference>();
      //Load project libraries
      //var assemblies = AppDomain.CurrentDomain
      //                .GetAssemblies()
      //                .Where(a => !a.IsDynamic)
      //                .Select(a => a.Location);
      //foreach (var item in assemblies)
      //{
      //  if (!item.Contains("xunit"))
      //    references.Add(MetadataReference.CreateFromFile(item));
      //}

      //or specify the libraries to load.

      var coreDir = Directory.GetParent(typeof(Enumerable).GetTypeInfo().Assembly.Location);
      var exeDir = Path.GetDirectoryName(Process.GetCurrentProcess().MainModule.FileName);
      references.Add(MetadataReference.CreateFromFile(typeof(Object).GetTypeInfo().Assembly.Location));
      references.Add(MetadataReference.CreateFromFile(typeof(Uri).GetTypeInfo().Assembly.Location));
      references.Add(MetadataReference.CreateFromFile(coreDir.FullName + Path.DirectorySeparatorChar + "mscorlib.dll"));
      references.Add(MetadataReference.CreateFromFile(coreDir.FullName + Path.DirectorySeparatorChar + "System.Runtime.dll"));
      if (File.Exists(exeDir + "\\Newtonsoft.Json.dll"))
        references.Add(MetadataReference.CreateFromFile(exeDir + "\\Newtonsoft.Json.dll"));
      else
        throw new Exception("Missing newtonsoft DLL");


      CSharpCompilation compilation = CSharpCompilation.Create(
          assemblyName,
          new[] { syntaxTree },
          new MetadataReference[]
          {
        MetadataReference.CreateFromFile(typeof(object).Assembly.Location)
          },
          new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary));

      using (var memoryStream = new MemoryStream())
      {
        var result = compilation.Emit(memoryStream);

        if (result.Success)
        {
          memoryStream.Seek(0, SeekOrigin.Begin);
          Assembly assembly = Assembly.Load(memoryStream.ToArray());

          Type testClassType = assembly.GetType("TestNamespace.TestClass");
          var addResult = (int)testClassType.GetMethod("Add").Invoke(null, new object[] { 3, 4 });
          Console.WriteLine(addResult);
        }
        else
        {
          Console.WriteLine("Failed to compile");
          for (var i = 0; i < result.Diagnostics.Length; i++)
          {
            Console.WriteLine(result.Diagnostics[i].ToString());
          }
        }
      }
    }
    static void Main(string[] args)
    {
      JObject j = null; //to make sure newtonsoft is included if loading current projects libraries

      Example1();
    }
  }
}

Answer 1

Your code should work fine if you don't forget to use the references list you've built up.

See test code on .NET Fiddle (link) - I used the AppDomain method there (one you commented out).

CSharpCompilation compilation = CSharpCompilation.Create(
    assemblyName,
    new[] { syntaxTree },
    references, //<-- you're missing this
    new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary));

Also, your invocations weren't actually calling the right Class and Method, which I guess you'll find out after you get past the compilation issues.

// Non-existent Type and Method...
Type testClassType = assembly.GetType("TestNamespace.TestClass");
var addResult = (int)testClassType.GetMethod("Add").Invoke(null, new object[] { 3, 4 });

Edit: Here's the full working code in case the Fiddle gets deleted:

public static void Main(string[] args)
{
    var j = new JObject(); // ensure assembly is available
    Example1();
}

public static void Example1()
{
    var assemblyName = "UserScript";
    var code = @"namespace UserScript { 
                  using Newtonsoft.Json;
                  public class RunScript {
                   public static string Eval() {
                    return JsonConvert.SerializeObject(new int[] {1,2,3,4});
                   }
                  }
                }";

    SyntaxTree syntaxTree = CSharpSyntaxTree.ParseText(code);
    
    //Load project libraries
    var references = AppDomain.CurrentDomain
        .GetAssemblies()
        .Where(a => !a.IsDynamic)
        .Select(a => a.Location)
        .Where(s => !string.IsNullOrEmpty(s))
        .Where(s => !s.Contains("xunit"))
        .Select(s => MetadataReference.CreateFromFile(s))
        .ToList()
        ;

    CSharpCompilation compilation = CSharpCompilation.Create(
        assemblyName,
        new[] { syntaxTree },
        references, //<-- you're missing this
        new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary));

    using (var memoryStream = new MemoryStream())
    {
        var result = compilation.Emit(memoryStream);

        if (result.Success)
        {
            memoryStream.Seek(0, SeekOrigin.Begin);
            Assembly assembly = Assembly.Load(memoryStream.ToArray());

            var testClassType = assembly.GetType("UserScript.RunScript");
            var invokeResult = (string)testClassType.GetMethod("Eval").Invoke(null, null);
            Console.WriteLine(invokeResult);
        }
        else
        {
            Console.WriteLine("Failed to compile");
            foreach (var diag in result.Diagnostics)
                Console.WriteLine(diag);
        }
    }
}