decode_variable's use of not_found_ptr

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

 >  >> 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?

I think this part is right and the clue is in the macro
NOT_FOUND_ERROR.

 > 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.

Looking at the Changelog error_silent has been deleted and
replaced with
throw_error.  I think the problem is elsewhere, in
break_command_1
in breakpoint.c maybe:

	case NOT_FOUND_ERROR:
	  /* If called to resolve pending breakpoint, just return
	     error code.  */
	  if (pending_bp)
	    return e.reason;

	  exception_print (gdb_stderr, e);

I guess that pending_bp is NULL in your case and you need to
debug GDB to see
why. 

It would probably also help (those more knowledgable than
me) if you said how
your GDB has been configured.

-- 
Nick                                           http://www.inet.net.n
z/~nickrob