MarsSeed [1] filed a deletion request for isl17 [2]:

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.)

[1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/isl17/