Re: bignum branch

[Paul Eggert]

Eli Zaretskii wrote:
> But that problem will affect all platforms, wouldn't it?  Because GMP
> can only work with 'long', and I guess we don't want to rely on stuff
> like 'prtdiff_t' and 'intmax_t' being no wider than 'long'?  We'd need
> to convert the other types explicitly.

Yes, of course. However, the more of these types are wider than a GMP limb, the 
more problems we'll have.

There's another thing about debugging. This stuff is still uncertain. That is, 
there are no doubt bugs in the bignum branch in this area, and we don't know yet 
how significant these correctness problems will be. With that in mind, it would 
be useful to have avoid-libgmp options with our own GMP replacement that uses 
uintmax_t limbs (or 'unsigned int' limbs, for that matter) for debugging 
purposes, to help us debug the inevitable glitches that will arise due to 
libgmp's limbs being wrong for some types.

I looked into libgmp, and it appears that all we would need is a 2-line change 
to mini-gmp.h. This should not be hard to maintain ourselves, with the idea of 
propagating it upstream when we can.