LLVM 19 is under preparation (18.1.7 is final), and a large number of
C++-using packages are failing to install with the current snapshot (and
have for a couple of months). Most of these are from a broken
StanHeaders headers, but others can be seen at
https://www.stats.ox.ac.uk/pub/bdr/clang19/ (which contains a
README.txt). Those new since 18.1.7 are
From Prof Bryan Ripley