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);
}

score 221 · Accepted Answer · answered Apr 04 '14 at 14:04

221

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

answered Apr 04 '14 at 14:04

Alberto

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3

Yep, this is somethings that's been required since `dynamic` was introduced. – khellang Apr 04 '14 at 14:06
19

And if Microsoft gave an error message which told you this is would make things so much easier. – kjbartel Sep 04 '15 at 01:30
1

I don't know if this fixed the issue or not, but I added into my Views/Web.config node. The compiler error is gone now. – Don Rolling Jan 12 '16 at 15:06
3

FWIW adding Microsoft.CSharp.dll means var scriptOptions = ScriptOptions.Default.WithReferences("Microsoft.CSharp") i.e. drop the dll. Stumped me for a few mins :) – Jon H Apr 06 '16 at 13:02
@JonH so we should add that line to AssemblyInfo.cs or somewhere **instead** of referencing the dll? – NH. Sep 22 '17 at 22:11
Exactly right. My issue was using this inside the Roslyn engine and what is referenced in the encompassing application isn't the same thing. – Jon H Sep 24 '17 at 07:16
I tried running the Rush code in a .net core 2.1 application console. I have added Microsoft.CSharp.dll reference in the project and also between the MetadataFileReference in the code, but I always get the same error. – Renzo Ciot Aug 21 '18 at 11:03

score 11 · Answer 2 · answered Aug 21 '18 at 15:01

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),            
    }
);

You can get away with System.Linq.Expressions, System.Private.CoreLib, System.Runtime and Microsoft.CSharp, all as strings — Simon Mourier, Aug 22 '18 at 13:15
To make my code work in .net 3.1 the key point was `MetadataReference.CreateFromFile(Assembly.Load(new AssemblyName("netstandard")).Location)` — Feri, Apr 27 '21 at 07:04

Simon_Weaver · Answer 3 · 2019-02-22T19:20:08.477

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 '19 at 19:20

answered Oct 30 '16 at 03:00

Simon_Weaver

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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. – t.j. Jan 03 '17 at 00:56
Fair point :) I just added it here because it seemed so obscure and this was a good match for that error – Simon_Weaver Jan 03 '17 at 00:58

score 4 · Answer 4 · edited May 23 '17 at 11:47

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 '17 at 11:47

Community

1
1

answered Feb 26 '16 at 19:57

A.Clymer

472
3
9

score 3 · Answer 5 · answered Feb 14 '19 at 09:15

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 '19 at 09:15

Kols

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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. – Goodies Nov 27 '20 at 13:38

Using System.Dynamic in Roslyn

5 Answers5

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