https://forum.unity.com/threads/bin-linux64-expected-by-runtime-compiler.510843/

Code (CSharp):

using System;
using System.CodeDom.Compiler;
using System.Linq;
using System.Reflection;
using System.Text;
using Microsoft.CSharp;
using UnityEngine;

public class RuntimeCompiler : MonoBehaviour
{
public void Start()
{
Debug.Log(CreateFunction().Invoke(null,new object[]{2,3}));
}

public static MethodInfo CreateFunction()
{
var code = @"
using UnityEngine;

public class Test
{
public static void Foo(int a, int b)
{
Debug.Log(""Hello, World!"" + a + """" + b);
}
}";

var param = new CompilerParameters();

// Add ALL of the assembly references
foreach (var assembly in AppDomain.CurrentDomain.GetAssemblies().Where(p => !p.IsDynamic))
{
param.ReferencedAssemblies.Add(assembly.Location);
}

// Add specific assembly references
param.ReferencedAssemblies.Add("System.dll");

// Generate a dll in memory
param.GenerateExecutable = false;
param.GenerateInMemory = true;

CSharpCodeProvider provider = new CSharpCodeProvider();
CompilerResults results = provider.CompileAssemblyFromSource(param, code);

if (results.Errors.Count > 0) {
var msg = new StringBuilder();
foreach (CompilerError error in results.Errors) {
msg.AppendFormat("Error ({0}): {1}\n",
error.ErrorNumber, error.ErrorText);
}
throw new Exception(msg.ToString());
}

Debug.Log(results.CompiledAssembly);

Type binaryFunction = results.CompiledAssembly.GetType("Test");
return binaryFunction.GetMethod("Foo");
}

}

Above is a simple example of a bug, where the .net compiler is looking for mono in a folder called bin-linux64 while the correct folder would be just bin.
It's fixed if you copy and paste
/opt/Unity/Editor/Data/MonoBleedingEdge/bin
and rename it to bin-linux64 .

Ran script under .Net 4.6 .