Roslyn - 从内存中的程序集创建MetadataReference

Question

使用ASP.NET 5应用程序(Visual Studio 2015 CTP5)和Microsoft.CodeAnalysis.CSharp.

如果我尝试创建MetadataReference到一个程序集,该程序集是解决方案的一部分,将其作为对CSharpCompilation.Create的引用传递,我得到一个System.ArgumentException,"空路径名称不合法".

// Throws exception
MetadataReference.CreateFromAssembly(typeof(this).Assembly);

// Doesn't throw exception
MetadataReference.CreateFromAssembly(typeof(Object).Assembly);

如果我检查程序集的Location属性,它是空的.我假设这与在ASP.NET 5中编译内存中应用程序的新方法有关,因此程序集不会存储在光盘上.

那么有没有办法将Roslyn的引用传递给没有Location属性的程序集,或者目前是不支持的？

编辑:@JaredPar - @SLaks已经突出显示它失败的确切位置,但这里是信息的完整堆栈跟踪.我之前在System.*程序集中创建了其他几个MetadataReferences,并且没有任何问题.

System.ArgumentException
Empty path name is not legal.
C:\Development\Incubator\net.framework\src\Webfuel.Services.Host\ScriptHelper\ScriptHelper.cs
Line 86:  
Line 87:              // Compile the code
Line 88:              var compilation = CSharpCompilation.Create(
Line 89:                  assemblyName,
Line 90:                  options: new CSharpCompilationOptions(outputKind: OutputKind.DynamicallyLinkedLibrary),
 at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, Win32Native.SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share) 
at System.IO.File.OpenRead(String path) 
at Microsoft.CodeAnalysis.InternalUtilities.FileStreamLightUp.OpenFileStream(String path) 
at Microsoft.CodeAnalysis.MetadataReference.CreateFromAssembly(Assembly assembly, MetadataReferenceProperties properties, DocumentationProvider documentation) 
at Microsoft.CodeAnalysis.MetadataReference.CreateFromAssembly(Assembly assembly) 
at Webfuel.Services.Host.ScriptHelper.CompileScriptImpl(String source) in C:\Development\Incubator\net.framework\src\Webfuel.Services.Host\ScriptHelper\ScriptHelper.cs:line 88 
at Webfuel.Services.Host.ScriptHelper.<>c__DisplayClass0.<CompileTemplate>b__3(String source) in C:\Development\Incubator\net.framework\src\Webfuel.Services.Host\ScriptHelper\ScriptHelper.cs:line 71 
at System.Collections.Concurrent.ConcurrentDictionary<TKey, TValue>.GetOrAdd(TKey key, Func<TKey, TValue> valueFactory) 
at Webfuel.Services.Host.ScriptHelper.CompileTemplate(String template) in C:\Development\Incubator\net.framework\src\Webfuel.Services.Host\ScriptHelper\ScriptHelper.cs:line 69 
at Webfuel.Services.Host.SandboxContext.<ExecuteTemplateAsync>d__1.MoveNext() in C:\Development\Incubator\net.framework\src\Webfuel.Services.Host\SandboxContext.cs:line 176 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter<TResult>.GetResult() 
at Webfuel.Services.Host.SandboxHost.<ExecuteTemplateAsync>d__1.MoveNext() in C:\Development\Incubator\net.framework\src\Webfuel.Services.Host\SandboxHost.cs:line 39 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter<TResult>.GetResult() 
at Webfuel.Services.Sandbox.SandboxService.<ExecuteTemplateAsync>d__1.MoveNext() in C:\Development\Incubator\net.framework\src\Webfuel.Services.Sandbox\SandboxService.cs:line 47 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter<TResult>.GetResult() 
at Webfuel.Services.Server.ServerService.<ProcessContentRequestAsync>d__1.MoveNext() in C:\Development\Incubator\net.framework\src\Webfuel.Services.Server\ServerService.cs:line 179 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter<TResult>.GetResult() 
at Webfuel.Services.Server.ServerService.<ProcessRequestAsync>d__1.MoveNext() in C:\Development\Incubator\net.framework\src\Webfuel.Services.Server\ServerService.cs:line 73 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter<TResult>.GetResult() 
at Webfuel.App.ServerMiddleware.<Invoke>d__1.MoveNext() in C:\Development\Incubator\net.framework\src\Webfuel.App\Startup.cs:line 89 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.GetResult() 
at Microsoft.AspNet.RequestContainer.ContainerMiddleware.<Invoke>d__1.MoveNext() 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.GetResult() 
at Microsoft.AspNet.Loader.IIS.KlrHttpApplication.<ProcessRequestAsyncImpl>d__1.MoveNext() 
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) 
at System.Runtime.CompilerServices.TaskAwaiter.GetResult() 
at Microsoft.AspNet.Loader.IIS.HttpApplicationBase.<InvokeProcessRequestAsyncImpl>d__1.MoveNext()

Answer 1

已经有一段时间了，但我确实在 github Roslyn 存储库上得到了一个答案，所以我会发布它，以防有人发现这个问题：

ASP.NET 5 为此提供了一个 API。您可以执行 Razor 的操作https://github.com/aspnet/Mvc/blob/dev/src/Microsoft.AspNet.Mvc.Razor/Compilation/RoslynCompilationService.cs#L132

这是在 Asp.Net 5 的 Beta1 左右，因此可能需要调整，但原理仍然相同 - 遵循 Asp.Net 本身通过IAssemblyLoadContextAccessor服务注入器将提供的 API 使用。

感谢大卫福勒

更新：此答案适用于 ASP.NET 5 Beta1。API 发生了很大变化，在 Core 1.0 中，您可以从静态成员访问 AssemblyLoadContext，而不是使用 IAssemblyLoadContextAccessor：

System.Runtime.Loader.AssemblyLoadContext.Default

然后您可以调用 LoadFromStream 从二进制图像加载程序集。这是我使用的代码的一个非常粗略的草图，并删除了一些不相关的部分：

        // Give the assembly a unique name
        var assemblyName = "Gen" + Guid.NewGuid().ToString().Replace("-", "") + ".dll";

        // Build the syntax tree
        var syntaxTree = CSharpSyntaxTree.ParseText(source);

        // Compile the code
        var compilation = CSharpCompilation.Create(
            assemblyName,
            options: new CSharpCompilationOptions(outputKind: OutputKind.DynamicallyLinkedLibrary),
            syntaxTrees: new List<SyntaxTree> { syntaxTree },
            references: GetMetadataReferences());

        // Emit the image of this assembly 
        byte[] image = null;
        using (var ms = new MemoryStream())
        {
            var emitResult = compilation.Emit(ms);
            if (!emitResult.Success)
            {
                throw new InvalidOperationException();
            }
            image = ms.ToArray();
        }

        Assembly assembly = null;

        // NETCORE
        using (var stream = new MemoryStream(image))
            assembly = System.Runtime.Loader.AssemblyLoadContext.Default.LoadFromStream(stream);

这不应该按原样运行，而只是给出主要步骤的想法。

此外，从仅内存程序集生成元数据引用的问题不再存在，因为这些在 Core 1.0 中不再存在，因此每个程序集都有一个 Location 属性。因此，获取这些引用的过程与 ASP.net 4 中的过程基本相同：

MetadataReference.CreateFromFile(Assembly.Load(new AssemblyName(assemblyName)).Location);