MarsSeed [1] filed a deletion request for pypy-stm-hg [2]:

Broken VCS package from 2020.

Missing some maketime dependencies.

But it would also be pointless to fix this: source branch has not been developed since 2015. [a]

[a]: https://foss.heptapod.net/pypy/pypy/-/tree/branch/stmgc-c7

[1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/pypy-stm-hg/