I've added bug: 83903x86_64, armv6, armv7, aarch64 all seem fine on linux. I've been building with latest gmp (6.1.2), mpfr (4.0.0) and mpc (1.1.) across all my systems.
I observe isl was updated to 0.18 in the download_prerequisites script. Are the other's going to get updated before the 8.0.0 release?