Re: [RFA 2/2] C++-ify break-catch-throw

[Pedro Alves <palves@redhat.com>]

On 06/05/2017 11:21 AM, Pedro Alves wrote:
> On 06/04/2017 11:53 PM, Tom Tromey wrote:
>> @@ -452,17 +450,14 @@ catch_exception_command_1 (enum exception_event_kind ex_event,
>>  			   char *arg_entry,
>>  			   int tempflag, int from_tty)
>>  {
>> -  char *except_rx;
>>    const char *cond_string = NULL;
>> -  struct cleanup *cleanup;
>>    const char *arg = arg_entry;
>>  
>>    if (!arg)
>>      arg = "";
>>    arg = skip_spaces_const (arg);
>>  
>> -  except_rx = extract_exception_regexp (&arg);
>> -  cleanup = make_cleanup (xfree, except_rx);
>> +  std::string except_rx = extract_exception_regexp (&arg);
>>  
>>    cond_string = ep_parse_optional_if_clause (&arg);
>>  
>> @@ -474,10 +469,8 @@ catch_exception_command_1 (enum exception_event_kind ex_event,
>>        && ex_event != EX_EVENT_RETHROW)
>>      error (_("Unsupported or unknown exception event; cannot catch it"));
>>  
>> -  handle_gnu_v3_exceptions (tempflag, except_rx, cond_string,
>> +  handle_gnu_v3_exceptions (tempflag, std::move (except_rx), cond_string,
>>  			    ex_event, from_tty);
>> -
>> -  discard_cleanups (cleanup);
>>  }
> 
> Something looks suspicious to me -- compile_rx_or_error returns with
> an installed cleanup that calls regfree, and handle_gnu_v3_exceptions
> leaves it installed too.

Maybe the cleanest would be to add a wrapper around regex_t,
and replace compile_rx_or_error with a ctor that throws,
like:

class gdb_regex
{
public:
  // replaces old compile_rx_or_error
  gdb_regex (const char *rx, const char *message)
  {
    gdb_assert (rx != NULL);

    int code = regcomp (&m_pattern, rx, REG_NOSUB);
    if (code != 0)
      {
        gdb::unique_xmalloc_ptr<char> err
          = get_regcomp_error (code, &m_pattern);

        error (("%s: %s"), message, err.get ());
      }
  }
  ~gdb_regex ()
  {
    regfree (&m_pattern);
  }

  // add convenience methods as needed.

private:
  regex_t m_pattern;
};

and use it throughout.

Thanks,
Pedro Alves