MarsSeed [1] filed a deletion request for autosubst-devel [2]: Broken, abandoned VCS pkg from 2017.
Also upstream no longer has devel branches - so the 'coq86-devel' branch the source URL points to doesn't exist. [a] [a]: https://github.com/coq-community/autosubst/branches [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/autosubst-devel/