Re: decode_variable's use of not_found_ptr

[Greg Law <greg at greglaw dot net>]

Dave Korn wrote:

> On 22 April 2006 09:06, Greg Law wrote:
>
>
>
>> but at the bottom of the function it says:
>>
>>
>>  if (not_found_ptr)
>>    *not_found_ptr = 1;
>>  throw_error (NOT_FOUND_ERROR, _("Function \"%s\" not defined."), copy);
>>
>>
>> Now, I must confess gdb's internal exception mechanism is deeply
>> mysterious to me, but that code looks to me like it doesn't do what the
>> comment claims.  i.e. if not_found_ptr is non-NULL, it still issues the
>> error message.
>>
>> What's wrong - my reading of the code, or the code?
>
>
>
>   Well, the code doesn't do what the comment says, that's true.  You 
can try
> putting an 'else' between those lines, but don't forget that you'll 
now have
> to add a return statement for when the error isn't thrown, and you'll 
have to
> return NULL since the lookup has failed, and there may be some call 
sites that
> aren't expecting to receive a NULL return because they've never had 
to before
> because the error was previously always being thrown, so there may be 
knock-on
> effects....


Can't return NULL as the function returns a structure by copy.

>
>   You could also try looking at the history of the file in CVS, see 
if that
> comment was ever accurate; it's the sort of error that can easily 
creep in
> during minor code tidyups.


Had a quick look at 6.3's code, and that is indeed different:

if (not_found_ptr)
  {
    *not_found_ptr = 1;
    /* The caller has indicated that it wishes quiet notification of any
     error where the function or file is not found.  A call to
     error_silent causes an error to occur, but it does not issue
     the supplied message.  The message can be manually output by
     the caller, if desired.  This is used, for example, when
     attempting to set breakpoints for functions in shared libraries
     that have not yet been loaded.  */
    error_silent ("Function \"%s\" not defined.", copy);
  }

For some reason the error_silent seems to have got chopped in version 
6.4.  I'll submit a problem report.

g