(Reposting in plain text - so sorry - been using thunderbird which automatically does that for mail lists - now with it's impending demise I am trying other mailers - like evolution ... )
I've seen this behavior a couple of times now. Here's what happened today.
After installing systemd and libsystemd 230-4 (updating from 230-3). No errors reported. However computer refused to boot properly. Booting recovery and examining the logs showed that libsystemd.so was missing - complaint by udev.
/usr/lib/libsystemd.so was present as a link pointing to libsystemd.so.0.15.0 which was absent. running pacman -Qk libsystemd confirmed the problem file. reinstalling libsystemd from cache - in recovery chroot - gave a warning about the link and the the libraryfile something like - warning: could not get file information for /usr/lib/libsystemd.so and .same for .so.0.15.0 And indeed the file was still absent.
from same cachea rea I installed libsystemd and systemd 230-3 (i.e. downgrading) - this worked and the library is back now and I could boot with udev dying a squirrely death.
I have had same problem (missing files with no warnings) with other updates - last time was glibc - that was fun to fix ... konsole wont start without glibc
There were other less impactful ones in recent months - about time pacman 5 moved to testing - not saying its pacman itself - but something is amiss - could be hardware, kernel or ?? I have no errors in the log files. and do not see any issues from smartctl either.
In all cases pacman -Qk finds the problem - and in all cases there were no errors reported on initial install -and there were similar warnings as zbove on re-install of same package from cache file.
In every case there was a shared library with a sym link - and the actual library file was missing.
Any suggestions for tracking this down? I assume if the package file was corrupted pacman would complain and redownload - so I'm a bit stumped ...
thanks for any guidance.