Error DbiModuleDescriptorBuilder::commit(BinaryStreamWriter &ModiWriter,
                                         const msf::MSFLayout &MsfLayout,
                                         WritableBinaryStreamRef MsfBuffer) {
  // We write the Modi record to the `ModiWriter`, but we additionally write its
  // symbol stream to a brand new stream.
  if (auto EC = ModiWriter.writeObject(Layout))
    return EC;
  if (auto EC = ModiWriter.writeCString(ModuleName))
    return EC;
  if (auto EC = ModiWriter.writeCString(ObjFileName))
    return EC;
  if (auto EC = ModiWriter.padToAlignment(sizeof(uint32_t)))
    return EC;

  if (Layout.ModDiStream != kInvalidStreamIndex) {
    auto NS = WritableMappedBlockStream::createIndexedStream(
        MsfLayout, MsfBuffer, Layout.ModDiStream, MSF.getAllocator());
    WritableBinaryStreamRef Ref(*NS);
    BinaryStreamWriter SymbolWriter(Ref);
    // Write the symbols.
    if (auto EC =
            SymbolWriter.writeInteger<uint32_t>(COFF::DEBUG_SECTION_MAGIC))
      return EC;
    BinaryItemStream<CVSymbol> Records(llvm::support::endianness::little);
    Records.setItems(Symbols);
    BinaryStreamRef RecordsRef(Records);
    if (auto EC = SymbolWriter.writeStreamRef(RecordsRef))
      return EC;
    if (auto EC = SymbolWriter.padToAlignment(4))
      return EC;
    // TODO: Write C11 Line data
    assert(SymbolWriter.getOffset() % alignOf(CodeViewContainer::Pdb) == 0 &&
           "Invalid debug section alignment!");
    for (const auto &Builder : C13Builders) {
      assert(Builder && "Empty C13 Fragment Builder!");
      if (auto EC = Builder->commit(SymbolWriter))
        return EC;
    }

    // TODO: Figure out what GlobalRefs substream actually is and populate it.
    if (auto EC = SymbolWriter.writeInteger<uint32_t>(0))
      return EC;
    if (SymbolWriter.bytesRemaining() > 0)
      return make_error<RawError>(raw_error_code::stream_too_long);
  }
  return Error::success();
}