Roslyn 似乎忽略了一些元数据引用

Question

在一些集成测试的准备阶段，我必须动态生成一些引用其他程序集的程序集并将它们刷新到磁盘。我猜这个任务的明显选择是 Roslyn。 Roslyn 编译成功完成并将发出的程序集保存到磁盘。当我使用 ILSPy 检查结果时，我发现一些程序集引用不包括在内。

虚拟类生成代码：

public static string GenerateEmptyPublicClass([NotNull] string @namespace, [NotNull] string className)
        {
            if (@namespace == null) throw new ArgumentNullException(nameof(@namespace));
            if (className == null) throw new ArgumentNullException(nameof(className));

            var classDeclaration = SyntaxFactory.ClassDeclaration(className).AddModifiers(SyntaxFactory.Token(SyntaxKind.PublicKeyword));
            var namespaceDeclaration = SyntaxFactory.NamespaceDeclaration(SyntaxFactory.ParseName(@namespace)).NormalizeWhitespace();
            namespaceDeclaration = namespaceDeclaration.AddMembers(classDeclaration);
            return namespaceDeclaration.NormalizeWhitespace().ToFullString();
        }

组装准备代码：

blic static void GenerateAssembly([NotNull] this string sourceCode, [NotNull] string assemblyFilePath,
            [NotNull] params string[] referencedAssemblyPaths)
        {
            if (sourceCode == null) throw new ArgumentNullException(nameof(sourceCode));
            if (assemblyFilePath == null) throw new ArgumentNullException(nameof(assemblyFilePath));

            var assemblyFileName = Path.GetFileName(assemblyFilePath);
            var outputDirectory = Path.GetDirectoryName(assemblyFilePath);
            Directory.CreateDirectory(outputDirectory);

            var syntaxTree = CSharpSyntaxTree.ParseText(sourceCode);
            var referencedAssemblyMetadata =
                referencedAssemblyPaths.Select(x => MetadataReference.CreateFromFile(x).WithProperties(new MetadataReferenceProperties()));
            var compilationOptions = new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary);
            var compilation = CSharpCompilation.Create(assemblyFileName, new[] {syntaxTree}, referencedAssemblyMetadata, compilationOptions);

            using (var fs = File.Create(assemblyFilePath))
            {
                var emitResult = compilation.Emit(fs);
                if (!emitResult.Success)
                {
                    var failures = emitResult.Diagnostics.Where(x => x.IsWarningAsError || x.Severity == DiagnosticSeverity.Error);
                    var errorReport = failures.Select(x => $"{x.Id}: {x.GetMessage()}, {x.Location}");
                    throw new InvalidOperationException($"Failed to compile source code {sourceCode}. Report: {errorReport}");
                }

                fs.Flush();
            }
        }

为简单起见，我想生成两个程序集：

• 唯一依赖于 netstandard.dll 的 B
• A 同时引用了 netstandard.dll 和 B

代码如下：

  var emptyClassSourceCode = RoslynAssemblyGenerator.GenerateEmptyPublicClass("DummyNamespace", "DummyClass");
            var standardAssemblyLocation = Path.Combine(Path.GetDirectoryName(Common.ExecutingAssemblyFullPath), "Resources", "netstandard.dll");

            // A references B
            var aPath = Path.Combine(AssemblyGenerationPath, "A.dll");
            var bPath = Path.Combine(AssemblyGenerationPath, "B.dll");
            emptyClassSourceCode.GenerateAssembly(bPath, standardAssemblyLocation);
            emptyClassSourceCode.GenerateAssembly(aPath, bPath, standardAssemblyLocation);

B按预期生成，但是A没有引用B：

无法弄清楚我错过了什么，为什么 A 没有引用 B。

Answer 1

正如评论中提到的 PetSerAl，为了引用程序集，我们不仅需要指明程序集位置，还需要实际使用它的元数据。