Re: [Texmacs-dev] [PATCH] solves GCC 3.2 auto_save segfault for me...

[Igor V. Kovalenko]

Joris van der Hoeven wrote:
> > > +//void destroy_tree_rep (tree_rep* rep);
> > >  inline tree::tree (const tree& x): rep (x.rep) { rep->ref_count++; }
> > > -inline tree::~tree () {
> > > -  if ((--rep->ref_count)==0) destroy_tree_rep (rep); }
> > > +
> > > +inline tree::~tree ()
> > > +{
> > > +    if ((--rep->ref_count)==0) {
> > > +        //destroy_tree_rep (rep);
> > > +        delete rep;
> > > +        rep = NULL;
> > > +    }
> > > +}
> >
> > I am a bit confused by this. Is this necessary?
> > We should recursively delete the tree,
> > so it does not suffice to just delete the pointer...
>
>
> I see now; that is the purpose of the virtual destructor...
>
> But now I am again confused, because the old routine
> destroy_tree_rep should precisely do the same thing
> as the virtual destructor. Apparently, a string is sometimes
> not a string or a compound not a compound...
>
> By the way, what is the effect of "rep = NULL" ?
> This is the only real change I can see,
> but I do not see why this should stabilize the code.

BTW the real change is in removing destroy_tree_rep that dereferences a rep 
itself,
and in using the presumed automagic of virtual destructors to do the job.

Can you do the test: in internal deallocator poison the data freed but not 
deallocated
with some non-zero values, say, 0xdeadbeef or something, and see the effect?

--
Regards,
Igor V. Kovalenko    mailto: iko at crec dot mipt dot ru