MarsSeed  filed a deletion request for lib32-isl :
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.
Request #35945 has been Accepted by grawlinson :
[Autogenerated] Accepted deletion for lib32-isl.