MarsSeed  filed a deletion request for isl17 :
This legacy version from 2016 has its source deleted (404).
But it seems it is not needed specifically by anything in AUR.
So I recommend to delete this if there are no objections.
(Also, the main isl package has been adopted from AUR to Arch [core] under the name 'libisl'. So all isl* packages on AUR should either be renamed in accordance, or deleted if not used.)
 https://aur.archlinux.org/account/MarsSeed/  https://aur.archlinux.org/pkgbase/isl17/
Request #35960 has been Accepted by grawlinson :
[Autogenerated] Accepted deletion for isl17.