Re: Using the GNU GMP Library for Bignums in Emacs

[Paul Eggert]

Tom Tromey wrote:
> On the other hand, I see that Guile is using the mpz API.  So, maybe in
> practice it is safe enough to just set custom allocation functions and
> let them throw.

Guile treats memory allocation failure like stack overflow, in the sense that it 
relies on undefined behavior in both cases, I guess on the theory that it's 
typically better to try to keep running (with undefined behavior) than to give 
up and exit right away. GNU Emacs already takes a similar attitude toward stack 
overflow, so perhaps it could do the same for memory exhaustion within mpz 
routines.  (Emacs could soften the blow by using a reserve, as I think it does 
already.)

With all that in mind, I guess it's OK to use the mpz API after all.

> one idea would be to put mini-gmp.c into the Emacs source tree, but
> only compile it if the real GMP library is not found.

That sounds like a good idea, given the above. We could also do this if the 
installed GMP library is too old for Emacs.