inhzus [1] filed an orphan request for cppcoro-git [2]:
The package script is still under clang 8, so that users with clang 11
(which is installed by default) could not install it correctly. And
The maintainer has not resolved the issue mentioned in the comment
last June.
[1] https://aur.archlinux.org/account/inhzus/
[2] https://aur.archlinux.org/pkgbase/cppcoro-git/