前几天对作了简单的重构，想提供C#脚本来定义Interception Policy，毫无疑问微软提供的编译平台Roslyn使C#脚本化提供了支持。但是没有想到随便尝试了一个简单的功能就出现了问题，我个人觉得这应该是Roslyn的Bug。但是Roslyn经历了这么多次版本的迭代还出现如此低级的错误，实在有点说不过去。

闲话少说，我们现在通过几行简单的代码来重现这个Bug。我们创建了一个.NET Core 2.1的控制台应用，并添加针对NuGet包”Microsoft.CodeAnalysis.CSharp.Scripting“（版本2.8.2）的依赖。如下所示的是.csproj的完整定义。

         
              
       
        Exe
               
       
        netcoreapp2.1
               
       
        App
               
       
        App
           
          
              
       
        7.3
           
          
              
           
      
     

接下来我们编写了一段简单的程序。如下面的代码片段所示，我们只是采用脚本的形式创建了一个Foo对象并利用它创建出Bar对象，然后调用后者的Print方法而已。

namespace Scripting{    public class Foo { }    public class Bar    {        public Foo Foo { get; }        public Bar(Foo foo) => Foo = foo;        public void Print() => Console.WriteLine(Foo);    }    class Program    {        static async Task Main(string[] args)        {            var options = ScriptOptions.Default                .AddReferences(typeof(Program).Assembly)                .AddImports("Scripting");            //Success            await CSharpScript               .Create("var bar = new Bar(new Foo());", options)               .ContinueWith("bar.Print()")               .RunAsync();        }    }}

这段代码是没有问题的，运行之后Print方法输出的结果可以正常出现在入下所示的控制台上。

接下来我们将“var bar = new Bar(new Foo());”这行代码按照如下的方式拆分成两行执行。

class Program{    static async Task Main(string[] args)    {        //Fail        await CSharpScript            .Create("var foo = new Foo();", options)            .ContinueWith("var bar = new Bar(foo);")            .ContinueWith("bar.Print()")            .RunAsync();    }}

在此运行该程序后出现如下所示的“Microsoft.CodeAnalysis.Scripting.CompilationErrorException”异常，并提示“cannot convert from 'Scripting.Foo [App, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]' to 'Scripting.Foo [c:\users\jinnan\Source\Repos\App\App\bin\Debug\netcoreapp2.1\App.dll]”。

如下所示的是完整的错误信息：

Unhandled Exception: Microsoft.CodeAnalysis.Scripting.CompilationErrorException: (1,19): error CS1503: Argument 1: cannot convert from 'Scripting.Foo [App, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]' to 'Scripting.Foo [c:\users\jinnan\Source\Repos\App\App\bin\Debug\netcoreapp2.1\App.dll]'   at Microsoft.CodeAnalysis.Scripting.ScriptBuilder.ThrowIfAnyCompilationErrors(DiagnosticBag diagnostics, DiagnosticFormatter formatter) in /_/src/Scripting/Core/ScriptBuilder.cs:line 104   at Microsoft.CodeAnalysis.Scripting.ScriptBuilder.CreateExecutor[T](ScriptCompiler compiler, Compilation compilation, Boolean emitDebugInformation, CancellationToken cancellationToken) in /_/src/Scripting/Core/ScriptBuilder.cs:line 89   at Microsoft.CodeAnalysis.Scripting.Script`1.GetExecutor(CancellationToken cancellationToken) in /_/src/Scripting/Core/Script.cs:line 359   at Microsoft.CodeAnalysis.Scripting.Script`1.CommonGetExecutor(CancellationToken cancellationToken) in /_/src/Scripting/Core/Script.cs:line 343   at Microsoft.CodeAnalysis.Scripting.Script`1.TryGetPrecedingExecutors(Script lastExecutedScriptInChainOpt, CancellationToken cancellationToken) in /_/src/Scripting/Core/Script.cs:line 407   at Microsoft.CodeAnalysis.Scripting.Script`1.GetPrecedingExecutors(CancellationToken cancellationToken) in /_/src/Scripting/Core/Script.cs:line 370   at Microsoft.CodeAnalysis.Scripting.Script`1.RunAsync(Object globals, Func`2 catchException, CancellationToken cancellationToken) in /_/src/Scripting/Core/Script.cs:line 459   at Scripting.Program.Main(String[] args) in c:\users\jinnan\Source\Repos\App\App\Program.cs:line 31   at Scripting.Program.
     
      (String[] args)
     

这是我提交的issue链接：