使用Roslyn单独编译类，并将它们组合在一个程序集中

Question

我有一组互不相交的动态编写的类，我想单独编译(并修复编译错误)。然后我想把它们组合到同一个程序集中。因为它们已经被编译了，所以我不想简单地将它们的语法树传递给汇编编译(以避免两次编译)。我试图将它们编译成netmodules，然后使用这些netmodule作为对程序集的引用，但得到的程序集没有所需的类型。

下面是我的测试代码(非常类似于Roslyn的CompilationEmitTests.MultipleNetmodulesWithPrivateImplementationDetails())

public static class Program
{

    public static void Main()
    {
        var s1 = @"public class A {internal object o1 = new { hello = 1, world = 2 }; public static string M1() {    return ""Hello, "";}}";
        var s2 = @"public class B : A{internal object o2 = new { hello = 1, world = 2 };public static string M2(){    return ""world!"";}}";
        var s3 = @"public class Program{public static void Main(){    System.Console.Write(A.M1());    System.Console.WriteLine(B.M2());}}";
        var comp1 = CreateCompilationWithMscorlib("a1", s1, compilerOptions: TestOptions.ReleaseModule);
        var ref1 = comp1.EmitToImageReference();

        var comp2 = CreateCompilationWithMscorlib("a2", s2, compilerOptions: TestOptions.ReleaseModule, references: new[] { ref1 });
        var ref2 = comp2.EmitToImageReference();

        var comp3 = CreateCompilationWithMscorlib("a3", s3, compilerOptions: TestOptions.ReleaseExe.WithModuleName("C"), references: new[] { ref1, ref2 });

        var ref3 = comp3.EmitToImageReference();

        IEnumerable<byte> result = comp3.EmitToArray();

        Assembly assembly = Assembly.Load(result.ToArray());

        Module module = assembly.GetModule("C");

        Type prog = module.GetType("Program");

        object instance = Activator.CreateInstance(prog);

        MethodInfo method = prog.GetMethod("Main");

        method.Invoke(null, null);
    }

    public static ImmutableArray<byte> ToImmutable(this MemoryStream stream)
    {
        return ImmutableArray.Create<byte>(stream.ToArray());
    }

    internal static ImmutableArray<byte> EmitToArray
    (
        this Compilation compilation,
        EmitOptions options = null,
        Stream pdbStream = null
    )
    {
        var stream = new MemoryStream();

        if (pdbStream == null && compilation.Options.OptimizationLevel == OptimizationLevel.Debug)
        {
            pdbStream = new MemoryStream();
        }

        var emitResult = compilation.Emit(
            peStream: stream,
            pdbStream: pdbStream,
            xmlDocumentationStream: null,
            win32Resources: null,
            manifestResources: null,
            options: options);

        return stream.ToImmutable();
    }
    public static MetadataReference EmitToImageReference(
        this Compilation comp
    )
    {
        var image = comp.EmitToArray();
        if (comp.Options.OutputKind == OutputKind.NetModule)
        {
            return ModuleMetadata.CreateFromImage(image).GetReference(display: comp.AssemblyName);
        }
        else
        {
            return AssemblyMetadata.CreateFromImage(image).GetReference(display: comp.AssemblyName);
        }
    }

    private static CSharpCompilation CreateCompilationWithMscorlib(string assemblyName, string code, CSharpCompilationOptions compilerOptions = null, IEnumerable<MetadataReference> references = null)
    {
        SourceText sourceText = SourceText.From(code, Encoding.UTF8);
        SyntaxTree syntaxTree = SyntaxFactory.ParseSyntaxTree(sourceText, null, "");

        MetadataReference mscoreLibReference = AssemblyMetadata.CreateFromFile(typeof(string).Assembly.Location).GetReference();

        IEnumerable<MetadataReference> allReferences = new MetadataReference[] { mscoreLibReference };

        if (references != null)
        {
            allReferences = allReferences.Concat(references);
        }

        CSharpCompilation compilation = CSharpCompilation.Create
        (
            assemblyName,
            new[] {syntaxTree},
            options : compilerOptions,
            references: allReferences
        );

        return compilation;
    }

}

Main()在静态方法Invoke()抛出异常，因为它找不到对A和B类的引用。

我做错了什么？

Answer 1

这是用户0xd4d在Github上发布的相同问题的答案。我测试了它的工作情况：

必须先调用LoadModule，然后才能访问网络模块

assembly.LoadModule("a1.netmodule", a1_netmodule_bytes);
assembly.LoadModule("a2.netmodule", a2_netmodule_bytes);

如果您已将它们全部保存到磁盘，则不需要执行此操作。

我仍然不明白他说如果我把它保存到磁盘，我就不需要这样做，这是什么意思。