Using the GNU GMP Library for Bignums in Emacs

[Siraphob (Ben) Phipathananunth]

Emacs Calc was written many years ago, and as a result its current
implementation implements bignums purely in Emacs Lisp. Its bignum
operations also use a lot of hacks (such as performing carry
operations). Arbitrary precision arithmetic could be faster if Emacs
had GNU GMP linked to it, with the relevant Emacs Lisp functions added
in C.

What is the consensus on linking the GNU GMP library to Emacs so that
packages such as Emacs Calc (and others) could benefit from using
native types (i.e. "mpz_t") rather than reinventing the wheel?

The benefits of linking GNU GMP are clear. It would make it easier to
extend the math capabilities of Emacs, while making it faster and less
error-prone. However, the downsides, if any exist, should be discussed
as well, to gauge whether pursuing such a task would be fruitful.