Clang: 9/2019, revised 4/2022 Clang, gfortran/dragonegg: The original wgrib2 support for Clang was for Ubuntu 12.04, using gfortran with dragonegg. When Ubuntu 12.04 lost support, dragonegg no longer worked (gcc v4 vs v10). As a result, support for clang+gfortran-dragonegg had ended. Clang, Flang and AOCC: When I last checked (2018), flang was available from github with compile directions. It was not simple to install. AMD released AOCC (AMD Optimizing C Compiler) suite which is based on clang and flang with optional optimizations for Zen 1 to Zen 3. The included wgrib2 makefile has been tested with AOCC and a Ryzen 5600G on Ubuntu 20.04LTS. AOCC uses modified versions of clang and flang (LLVM). AMD modifications get sent to LLVM for inclusion of future clang and flang versions. AOCC is quite easy to install if you have one of the supported systems. If you are using an old version of RedHat or Ubuntu, it is probably time to update to a newer version. AOCC will work on intel cpus. https://developer.amd.com/amd-aocc/ To compile with AOCC export CC=clang export FC=flang make To compile for Zen3 with AOCC export CC=clang export FC=flang export CFFLAGS=-march=znversion3 export FFLAGS=-march=znversion3 make AOCC: Jasper does not compile correctly. Use OpenJPEG to support jpeg2000. OpenJPEG requires Cmake USE_JASPER=0 USE_OPENJPEG=1 Netcdf4 does not compile correctly. Must use USE_NETCDF3=1 USE_NETCDF4=0 Shared libraries work on linux (Ubuntu 20.04LTS)