cp_parser_parameter_declaration_clause

[Sohail Somani]

The function cp_parser_parameter_declaration_clause says that it returns
NULL if the parameters are (...). However, there is a line of code that
is:

  /* Parse the parameter-declaration-list.  */
  parameters = cp_parser_parameter_declaration_list (parser, &is_error);
  /* If a parse error occurred while parsing the
     parameter-declaration-list, then the entire
     parameter-declaration-clause is erroneous.  */
  if (is_error)
    return NULL;

So how does one tell if this function has returned an error?

Thanks,

Sohail