bug#8611: fixnum arithmetic should not wrap around

[Stefan Monnier]

>> Using floats has only been introduced in order to handle things like
>> file sizes larger than 4GB, i.e. the int-to-float conversion currently
>> only ever happens for values that come from some C function.
> Sorry, I don't follow.  The Lisp reader currently sees "536870912"
> and generates a float.  How is that "some C function"?

I guess "from outside of Elisp" is a better description than "from some
C function".  The Lisp reader brings values from outside Elisp
into Elisp.

> Would it be better to change Emacs to use bignums if available?

Maybe.  Other than Calc (and only if someone goes thorugh the trouble to
port it to the new bignum primitives), I can't think of too many
packages that would benefit, so it would seem to bring in a lot of extra
code and complexity for little pay off.

I guess Stephen could tell us if that is indeed (or not) what happen(s|ed)
with XEmacs's bignums.


        Stefan