Mono.ArgumentNullOrEmptyException When trying to write embedded symbols assembly to stream

[Tacodiva]

I want to write an AssemblyDefinition with symbols embedded to a stream. I am doing:

definition.Write(byteStream, new() {
    WriteSymbols = true
});

But this throws an exception:

Mono.ArgumentNullOrEmptyException: Argument null or empty (Parameter 'fileName')
   at Mono.Cecil.Mixin.CheckFileName(String fileName)
   at Mono.Cecil.Cil.EmbeddedPortablePdbWriterProvider.GetSymbolWriter(ModuleDefinition module, String fileName)
   at Mono.Cecil.Cil.DefaultSymbolWriterProvider.GetSymbolWriter(ModuleDefinition module, String fileName)
   at Mono.Cecil.ModuleWriter.GetSymbolWriter(ModuleDefinition module, String fq_name, ISymbolWriterProvider symbol_writer_provider, WriterParameters parameters)
   at Mono.Cecil.ModuleWriter.Write(ModuleDefinition module, Disposable`1 stream, WriterParameters parameters)
   at Mono.Cecil.ModuleWriter.WriteModule(ModuleDefinition module, Disposable`1 stream, WriterParameters parameters)
   at Mono.Cecil.ModuleDefinition.Write(Stream stream, WriterParameters parameters)
   at Mono.Cecil.AssemblyDefinition.Write(Stream stream, WriterParameters parameters)
   ...

---

I have not tested this, but I believe the call to CheckFileName in EmbeddedPortablePdbWriterProvider.GetSymbolWriter is not necessary, as I don't think the file name is used by EmbeddedPortablePdbWriter.

cecil/Mono.Cecil.Cil/PortablePdb.cs

Lines 485 to 493 in 56d4409

	public ISymbolWriter GetSymbolWriter (ModuleDefinition module, string fileName)
	{
	Mixin.CheckModule (module);
	Mixin.CheckFileName (fileName);
	var stream = new MemoryStream ();
	var pdb_writer = (PortablePdbWriter) new PortablePdbWriterProvider ().GetSymbolWriter (module, stream);
	return new EmbeddedPortablePdbWriter (stream, pdb_writer);
	}

Because of this check, it seems to be impossible to write embedded symbols without writing into a file.