Found the following significant warnings:
  clang-20: warning: /usr/local/clang20/include: 'linker' input unused [-Wunused-command-line-argument]
See ‘/data/gannet/ripley/R/packages/tests-clang/libdeflate.Rcheck/00install.out’ for details.
* used C compiler: ‘clang version 20.1.7’
Installation failed.
See ‘/data/gannet/ripley/R/packages/tests-devel/libdeflate.Rcheck/00install.out’ for details.