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

[Joris van der Hoeven]

> I tested TeXmacs with the patch included and it seems to be stable now.
> Comments?

I also tested your patch now and, unfortunately,
I still get segfaults just after autosaving and typing a bit of text.

I also restudied the use of virtual destructors.
In fact, the current implementation is correct and best.
Indeed, you should not forget that a virtual destructor increases
the size of the data structure. Consequently, one should avoid
the use of it whenever possible.

>   struct concrete_struct {
>     int ref_count;
>     inline concrete_struct (): ref_count (1) { DEBUG(concrete_count++); }
> -  inline ~concrete_struct () { DEBUG(concrete_count--); }
> +  inline virtual ~concrete_struct () { DEBUG(concrete_count--); }
>   };

The classes concrete_struct and abstract_struct are really base classes
and *not* abstract classes: we never explicitly allocate a concrete_struct
or an abstract_struct. Moreover, the destructor does nothing when DEBUG
is inactive. We might just add "DEBUG(virtual)" to be extremely correct.

> +inline tree::~tree ()
> +{
> +    if ((--rep->ref_count)==0) {
> +        //destroy_tree_rep (rep);
> +        delete rep;
> +        rep = NULL;
> +    }
> +}

Again, the function destroy_tree_rep explicitly does the "delete rep"
depending on the kind of tree (string or compound). Indeed, this type
can be determined as a function of "op", so destroy_tree_rep plays
the rôle of a virtual destructor *without* the extra space overhead.
It may still be interesting though to add the line "rep = NULL"
to destroy_tree_rep.