So I was wrong and it turned out to be a mainline bug, but one that was only present on x86 32-bit. Here's the reports:
https://gitlab.com/nonguix/nonguix/-/issues/307 https://issues.guix.gnu.org/68429 https://github.com/catchorg/Catch2/issues/2796 -- Take it easy, Richard Sent Making my computer weirder one commit at a time.
