Re: Regarding recent void * change

[Mikael Djurfeldt <mdj at mdj dot nada dot kth dot se>]

Telford Tendys <telford@eng.uts.edu.au> writes:

> > I'm afraid that there might exist architectures where dealing with
> > values which are invalid as pointers will yield a bus error.
> 
> This is a rather vague potentiality. I can think of early 68k machines
> where bus errors resulted from dereferenceing a pointer to an odd address
> but never from storing an odd number in an address register. Maybe it is
> possible to find an architecture whose address registers are so specialised
> that they cannot cope with some numbers but that would be a very unusual
> case and should not distort the core effort. The magic number for human
> perception is 95%, once something is true 95% of the time, it is true.

OK, good.

> > I think we generally should think more about how changes influence
> > Guile on other architectures than we have done recently.
> 
> Don't go looking for outlandish cases though. There are enough problems
> to solve right here and now without finding problems that may sometime
> happen perhaps.

I wouldn't have raised this question if I wasn't genuinely worried
about the consequences.  It is a good thing to think about
consequences when we alter the basic representation of Scheme objects.
But if people more knowledgeable about these things than me say it is
OK, I trust that.

I should say, though, that I *have* got bus error in one program when
I moved to a different architecture due to some similar situation
(that is not even dereferencing).