Publish to single file gives an empty Assembly.Location which crashes Roslyn Evaluator

[angrynik]

I'm running a .NET 7 WPF app with a reference to CSScriptLib nuget.

My project works great and scripts run right in debug mode. When I publish I get the error:

"Current version of Roslyn-based evaluator does not support referencing assemblies which are not loaded from the file location."

I publish to a single file which merges most of the referenced dlls into a single dll. Looks like this code in Evaluator.Roslyn.cs is having a problem with it:

        public override IEvaluator ReferenceAssembly(Assembly assembly)
        {
            //Microsoft.Net.Compilers.1.2.0 - beta
            if (assembly.Location.IsEmpty())

I checked this in my code when publishing both to many files and to a single file and in the latter case Location is empty.

            if (string.IsNullOrEmpty(typeof(IRunScriptAsync).Assembly.Location))
                throw new System.Exception("Assembly.Location is empty");

[oleg-shilo]

This error means that you are trying to reference (from the script) an assembly that has not been loaded to your app domain from the file but from memory. I guess this is what runtime does in the "single file" scenario.

It's not a problem for the host assembly execution, but it is a problem for Roslyn, which has the limitation that it cannot reference assemblies without a file.

If it is you who is calling ReferenceAssembly, then I suggest you try to reference the assembly from a file. Replace ReferenceAssembly(Assembly assembly) call with ReferenceAssembly(string assembly).

If it is CS-Script itself when loading domain assemblies, then you should disable referencing domain assemblies and reference them individually by file name. In this case, it will be that single file you built. Though I am not sure how you can find its path if Assembly.Location is empty.

[angrynik]

I think it's a Roslyn problem, this issue has gone nowhere for a few years:

dotnet/roslyn#50719

That page links to a workaround here: https://github.com/andersstorhaug/SingleFileScripting

I'm new to this so I don't know if that's something I can do myself, or if it could be used in cs-script ? For now I'm going to switch off single file output, and add a hundred dlls to my Wix installer.

[oleg-shilo]

I am not sure it is a real workaround.
We have the problem here that Roslyn scripts cannot reference loaded assemblies but only assembly files. The code there does not show the script that references any of such assemblies. It only references core assembly. You can do it with CS-Script too.
Your problem is more fundamental. After merging all your dependency assemblies in a single file it's no longer an assembly that can be referenced.

But... I will play a little with it today to confirm what I just described.

[oleg-shilo]

Looked at the sample more...
it might be the way out, actually.
give me some time, I think it is something that can be the way out for cs-script in this scenario.

[angrynik]

Thanks for looking, would be very nice....

[oleg-shilo]

I can confirm now that with that work around it is now possible to execute scripts from the host app built as a single self-contaied file. Thank you for sharing the info.

It will take a little time to properly integrate it and release the update. The future syntax will look like this:

var calc = CSScript.Evaluator.Execute("1 + 2");

or

var calc = CSScript.Evaluator
                   .Execute(@"using System;
                              public class Script
                              {
                                  public int Sum(int a, int b)
                                  {
                                      return a+b;
                                  }
                              }
                              return new Script();");

int sum = calc.Sum(1, 2);

[oleg-shilo]

Done.
Please update your nuget ref to v4.8.3.

var calc = CSScript.Evaluator
                   .Eval(@"using System;
                           public class Script
                           {
                               public int Sum(int a, int b)
                               {
                                   return a+b;
                               }
                           }
                           return new Script();");

int sum = calc.Sum(1, 2);
Console.WriteLine(sum);

The complete sample can be found here.

[angrynik]

Ok, awesome, I have refactored from LoadMethod to now use Eval, and it works great in debug mode. I publish to a single file and now I get:

CodeBase is not supported on assemblies loaded from a single-file bundle

I'm pretty sure my code is similar to your example, but with lots of "using " statements for other referenced assemblies.

[oleg-shilo]

I did test the code sample (https://github.com/oleg-shilo/cs-script/blob/master/src/CSScriptLib/src/Client.SingleFileBuild/Program.cs) after publishing so there is something new in your case.

Can you share the solution you are testing so I can have a look? A sanitized version of it.
Or a hello-world example that demonstrates the problem.

[angrynik]

Right, I added a class library with one class that runs a script.

namespace BreakLib;
public class BreakClass
{
    public static string RunScript()
    {
        var calc = CSScript.Evaluator
                           .Eval(@"using System;
                           public class Script
                           {
                               public int Sum(int a, int b)
                               {
                                   return a+b;
                               }
                           }
                           return new Script();");

        int sum = calc.Sum(1, 2);
        return $"sum is {sum}";
    }
}

Then I reference the project and call that method from the Client.SingleFileBuild sample.

...
...
var result = BreakLib.BreakClass.RunScript();
Console.WriteLine(result);

This is the setup I use, where the script runner is in a dedicated project and I call that from my apps.

[oleg-shilo]

I repeated the test. Seems to work as expected.
I have attached the test project
cs-script.#343.zip

[angrynik]

Hmmm. Can I ask how you publish? I do it through Visual Studio with these settings, and managed to crash this sample.