Trivial fix in value_sub

[Daniel Jacobowitz]

On Wed, Apr 03, 2002 at 10:54:57PM -0500, Jim Blandy wrote:
> 
> Jim Ingham <jingham@apple.com> writes:
> > So... I don't think you should keep the size at 0.  This seems like
> > gdb is just silently ignoring the " -  x" part of what they typed, and
> > you should always be explicit about what you have done.  But if you
> > think an error is more appropriate, I am fine with that...
> 
> Oh, no, I didn't mean to suggest that zero was the right size to use;
> I agree with you completely that that would be pretty confusing.
> 
> Your story is pretty amazing --- I would never have guessed that
> people actually *use* the sizeof (struct incomplete) == 1 behavior!  I
> think it is much more common for people to be unaware that the type is
> incomplete; if this hunch is correct, then the behavior your toolbox
> folks love will be very confusing.  I think an error for arithmetic on
> any incomplete type other than (void *) is the right thing.

FWIW, I agree.  If we don't know what the size is, we should say so;
having the behavior change based on whether a version of the
implementation (which might have debug symbols) is loaded would be
baffling.

-- 
Daniel Jacobowitz                           Carnegie Mellon University
MontaVista Software                         Debian GNU/Linux Developer