The issue here is that upstream is effectively unmaintained so this version has patches for known bugs. (Patches have been submitted upstream with reproducers over the past decade, but upstream remains generally non-responsive unless cornered in the hallway at a conference.) These can be rebased on a new upstream version, but that takes some coordination and is normally done after upstream releases rather than random point commits. The workaround (if the bugs don't affect you) is to use parmetis-git. Unfortunately, extra/metis is now incompatible. One fix would be to create a new metis51 required by parmetis (and parmetis-mpich) though we'd either have to make it provide metis or change the library name, which I think also requires build system patches. I've been busy to implement (and test) that solution, but simply making parmetis track git without the PETSc team's patch suite will cause breakage. notify@aur.archlinux.org writes:

MarsSeed [1] filed an orphan request for parmetis [2]:

Please disown if not maintained. Reported failing to build since 2023-07-29, with solution provided.

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