Cannot create MetadataReference from WebCIL

[wherewhere]

Version Used: Roslyn 4.12.0-3.final; .NET 8.0; Visual Studio 2022

Steps to Reproduce:

1. Create a MetadataReference from WebCIL file

   await using FileStream stream = File.OpenRead("System.Private.CoreLib.wasm");
   references = MetadataReference.CreateFromStream(stream);

2. Use this reference to create a Compilation

   SyntaxTree syntaxTree =
       SyntaxFactory.ParseSyntaxTree(
           "int a = 2;",
           new CSharpParseOptions(
               LanguageVersion.Preview,
               DocumentationMode.Parse,
               SourceCodeKind.Regular),
           null!);
   Compilation compilation =
       CSharpCompilation.Create(
           "SharpScript",
           [syntaxTree],
           [references],
           new CSharpCompilationOptions(
               OutputKind.ConsoleApplication,
               allowUnsafe: true,
               concurrentBuild: false));

3. Emit it

   await using MemoryStream assemblyStream = new();
   EmitResult emitResult = compilation.Emit(assemblyStream);
   if (emitResult.Success)
   {
       AssemblyLoadContext context = new("ExecutorContext", isCollectible: true);
       try
       {
           assemblyStream.Seek(0, SeekOrigin.Begin);
           Assembly assembly = context.LoadFromStream(assemblyStream);
           if (assembly.EntryPoint is MethodInfo main)
           {
               string[][]? _args = main.GetParameters().Length > 0 ? [Array.Empty<string>()] : null;
               object? @return = main.Invoke(null, _args);
               Console.WriteLine(@return);
           }
       }
       finally
       {
           context.Unload();
       }
   }
   else
   {
       foreach (Diagnostic diagnostic in emitResult.Diagnostics)
       {
           Console.WriteLine(diagnostic);
       }
   }

Expected Behavior:

Compiled succeed.

Actual Behavior:

Compiled failed.

warning CS8021: 找不到 RuntimeMetadataVersion 的值。找不到包含 System.Object 的程序集，或未通过选项为 RuntimeMetadataVersion 指定值。
error CS0009: 无法打开元数据文件“<内存中的程序集>”-- PE 映像不包含任何托管元数据。
(1,1): error CS0518: 预定义类型“System.Object”未定义或导入
error CS0518: 预定义类型“System.Void”未定义或导入
error CS0518: 预定义类型“System.String”未定义或导入
(1,1): error CS0518: 预定义类型“System.Int32”未定义或导入
(1,9): error CS0518: 预定义类型“System.Int32”未定义或导入
(1,1): error CS1729: “object”不包含采用 0 个参数的构造函数
error CS0518: 预定义类型“System.Attribute”未定义或导入
error CS0518: 预定义类型“System.Attribute”未定义或导入
error CS0518: 预定义类型“System.Int32”未定义或导入
error CS0656: 缺少编译器要求的成员“System.AttributeUsageAttribute..ctor”
error CS0656: 缺少编译器要求的成员“System.AttributeUsageAttribute.AllowMultiple”
error CS0656: 缺少编译器要求的成员“System.AttributeUsageAttribute.Inherited”

Similar issue: #74555

[jcouv update:] FWIW, here are the translated diagnostics:

warning CS8021: Value for RuntimeMetadataVersion not found. The assembly containing System.Object could not be found, or the value for RuntimeMetadataVersion was not specified via the option.
error CS0009: Unable to open metadata file '<内存中的程序集>'-- PE image does not contain any managed metadata.
(1,1): error CS0518: Predefined type 'System.Object' is not defined or imported
error CS0518: Predefined type "System.Void"' is not defined or imported
error CS0518: Predefined type &System.String"Undefined or imported
(1,1): error CS0518: Predefined type &System.Int32" not defined or imported
(1,9): error CS0518: Predefined type 'System.Int32' is not defined or imported
(1,1): error CS1729: 'object' does not contain constructor with 0 arguments
error CS0518: Predefined type "System.Attribute"' is not defined or imported
error CS0518: Predefined type "System.Attribute"' is not defined or imported
error CS0518: Predefined type "System.Int32" is not defined or imported
error CS0656: Member "System.AttributeUsageAttribute.. is missing compiler requirement ctor”
error CS0656: Member "System.AttributeUsageAttribute.AllowMultiple" is missing compiler requirement
error CS0656: Member "System.AttributeUsageAttribute.Inherited' is missing compiler requirement

[jjonescz]

MetadataReference expects PE file on its input. See also dotnet/runtime#103071. There are ways to convert from WebCIL to PE: https://github.com/StefH/ProtoBufJsonConverter/blob/fc0530d796ce1659cdf8e852970c1219c7296be8/src-webcil/MetadataReferenceService.BlazorWasm/WasmWebcil/WebcilConverterUtil.cs#L56

[wherewhere]

Thanks, it works fine.