class RbSys::CargoBuilder

def maybe_resolve_ldflag_variable(input_arg, dest_dir)
  var_matches = input_arg.match(/\$\((\w+)\)/)
  return input_arg unless var_matches
  var_name = var_matches[1]
  return input_arg if var_name.nil? || var_name.chomp.empty?
  case var_name
  # On windows, it is assumed that mkmf has setup an exports file for the
  # extension, so we have to to create one ourselves.
  when "DEFFILE"
    write_deffile(dest_dir)
  else
    RbConfig::CONFIG[var_name]
  end
end