Using System.Dynamic in Roslyn

Question

I modified the example that comes with the new version of Roslyn that was released yesterday to use dynamic and ExpandoObject but I am getting a compiler error which I am not sure how to fix. The error is:

(7,21): error CS0656: Missing compiler required member 'Microsoft.CSharp.RuntimeBinder.CSharpArgumentInfo.Create'

Can you not use dynamics in the new compiler yet? How can I fix this? Here is the example that I updated:

[TestMethod]
public void EndToEndCompileAndRun()
{
    var text = @"using System.Dynamic;
    public class Calculator
    {
        public static object Evaluate()
        {
            dynamic x = new ExpandoObject();
            x.Result = 42;
            return x.Result;
        } 
    }";

    var tree = SyntaxFactory.ParseSyntaxTree(text);
    var compilation = CSharpCompilation.Create(
        "calc.dll",
        options: new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary),
        syntaxTrees: new[] {tree},
        references: new[] {new MetadataFileReference(typeof (object).Assembly.Location), new MetadataFileReference(typeof (ExpandoObject).Assembly.Location)});

    Assembly compiledAssembly;
    using (var stream = new MemoryStream())
    {
        var compileResult = compilation.Emit(stream);
        compiledAssembly = Assembly.Load(stream.GetBuffer());
    }

    Type calculator = compiledAssembly.GetType("Calculator");
    MethodInfo evaluate = calculator.GetMethod("Evaluate");
    string answer = evaluate.Invoke(null, null).ToString();

    Assert.AreEqual("42", answer);
}

Alberto · Accepted Answer · 2014-04-04 14:04:19Z

222

I think that you should reference the Microsoft.CSharp.dll assembly

answered Apr 4, 2014 at 14:04

Alberto

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7 Comments

khellang Over a year ago

Yep, this is somethings that's been required since dynamic was introduced.

kjbartel Over a year ago

And if Microsoft gave an error message which told you this is would make things so much easier.

Don Rolling Over a year ago

I don't know if this fixed the issue or not, but I added <add namespace="Microsoft.CSharp" /> into my Views/Web.config <namespaces> node. The compiler error is gone now.

Jon H Over a year ago

FWIW adding Microsoft.CSharp.dll means var scriptOptions = ScriptOptions.Default.WithReferences("Microsoft.CSharp") i.e. drop the dll. Stumped me for a few mins :)

NH. Over a year ago

@JonH so we should add that line to AssemblyInfo.cs or somewhere instead of referencing the dll?

|

Renzo Ciot · Accepted Answer · 2018-08-21 15:01:29Z

12

To make the code work in .Net Core 2.1 I had to add this references in the compilation:

var compilation = CSharpCompilation.Create(
    "calc.dll",
    options: new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary),
    syntaxTrees: new[] {tree},
    references: new[] {
        MetadataReference.CreateFromFile(typeof(object).Assembly.Location),
        MetadataReference.CreateFromFile(typeof(ExpandoObject).Assembly.Location),
        MetadataReference.CreateFromFile(Assembly.Load(new AssemblyName("Microsoft.CSharp")).Location),
        MetadataReference.CreateFromFile(Assembly.Load(new AssemblyName("netstandard")).Location),
        MetadataReference.CreateFromFile(Assembly.Load(new AssemblyName("mscorlib")).Location),
        MetadataReference.CreateFromFile(Assembly.Load(new AssemblyName("System.Runtime")).Location),            
    }
);

answered Aug 21, 2018 at 15:01

Renzo Ciot

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2 Comments

Simon Mourier Over a year ago

You can get away with System.Linq.Expressions, System.Private.CoreLib, System.Runtime and Microsoft.CSharp, all as strings

Feri Over a year ago

To make my code work in .net 3.1 the key point was MetadataReference.CreateFromFile(Assembly.Load(new AssemblyName("netstandard")).Location)

Simon_Weaver · Accepted Answer · 2019-02-22 19:20:08Z

7

ASP.NET MVC specific:

You can get this error in an MVC 6 controller if you forget to put [FromBody] in a POST method.

    [HttpPost("[action]")]
    public void RunReport([FromBody]dynamic report)
    {
        ...
    }

The .NETCore default project already includes Microsoft.CSharp reference but you get pretty much the same message.

With [FromBody] added you can now post JSON and then just dynamically access the properties :-)

edited Feb 22, 2019 at 19:20

answered Oct 30, 2016 at 3:00

Simon_Weaver

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2 Comments

t.j. Over a year ago

Figured it didn't apply to original question posted from 2014 (though wanted to acknowledge it was helpful.) Wasn't sure what SO etiquette dictated in such a situation.

Simon_Weaver Over a year ago

Fair point :) I just added it here because it seemed so obscure and this was a good match for that error

Community · Accepted Answer · 2017-05-23 11:47:16Z

4

You may also want to check the properties of all your project references. Make sure any reference is using .NET newer than 2.0. I have a project that was referencing another project in the same solution and had to rebuild the dependency using a newer .NET framework target.

See this post.

Also, don't forget to add the Microsoft.CSharp reference to you main project like @Alberto said.

edited May 23, 2017 at 11:47

CommunityBot

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answered Feb 26, 2016 at 19:57

A.Clymer

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Comments

Kolappan N · Accepted Answer · 2019-02-14 09:15:11Z

3

If your project is targeting .Net Core or .Net Standard, then instead of adding reference you can install the Microsoft.CSharp NuGet package to solve this error.

answered Feb 14, 2019 at 9:15

Kolappan N

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1 Comment

Goodies Over a year ago

The Microsoft CSharp has to be referenced by your Roslyn compiland. It is available, or it can be added as a normal reference to your caller project. Remember for Roslyn use set Copy Local = true in the properties of the reference, else your generated code cannot find it. Then add MetadataReference.CreateFromFile(Assembly.Load(new AssemblyName("Microsoft.CSharp")).Location) to the references[] to add it to your compiland.

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