MarsSeed [1] filed a deletion request for lib32-isl [2]:
Orphaned package, not needed anymore by anything in AUR.
Also its native-build counterpart has been adopted into Arch [core] and renamed to libisl, so now this package's name is not proper.
I recommend deletion.
[1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/lib32-isl/
Request #35945 has been Accepted by grawlinson [1]:
[Autogenerated] Accepted deletion for lib32-isl.
aur-requests@lists.archlinux.org