On 64-bit Linux, uint64_t is unsigned long, but on 64-bit Apple ARM, uint64_t is unsigned long long. Regardless of platform, GMP's mp_limb_t is always defined as unsigned long. As a result, it is possible to freely assign between *uint64_t and *mp_limb_t when building for Linux, but not when building for Mac OS.

Building a circom-generated witness generator on MacOS will therefore produce a spew of errors when compiling fr.cpp, because it frequently attempts to pass in *uint64_t where GMP expects *mp_limb_t.

This can be resolved by changing the declared types in fr.hpp and fr.cpp from uint64_t to mp_limb_t, as shown in the attached files. The modified files will compile successfully on aarch64.

updated_witgen_fr.zip