     if let enableBareSlashRegexLiteral = enableBareSlashRegexLiteral {
       swiftparse_parser_set_enable_bare_slash_regex_literal(c_parser, enableBareSlashRegexLiteral)
     }
+#endif
 
     let nodeHandler = { (cnode: CSyntaxNodePtr!) -> UnsafeMutableRawPointer in
       RawSyntax.getOpaqueFromCNode(cnode, in: sourceBuffer, arena: arena)

    let arena = SyntaxArena()
    let sourceBuffer = source.withUTF8 { arena.internSourceBuffer($0) }

    if let languageVersion = languageVersion {
      languageVersion.withCString { languageVersionCString in
        swiftparse_parser_set_language_version(c_parser, languageVersionCString)

      swiftparse_parser_set_diagnostic_handler(c_parser, diagHandler)
    }

    let c_top = sourceBuffer.withMemoryRebound(to: CChar.self) { sourceBuffer in
      return swiftparse_parse_string(c_parser, sourceBuffer.baseAddress, sourceBuffer.count)
    }
    let base = Syntax(raw: RawSyntax.fromOpaque(c_top!))
    guard let file = base.as(SourceFileSyntax.self) else {
      throw ParserError.invalidSyntaxData
