Clang: 9/2019 Clang, gfortran/dragonegg: The original wgrib2 support for Clang was for Ubuntu 12.04, using gfortran with dragonegg. Unfortunately dragonegg requires gcc 4.x and gcc is already up to gcc 10. As a result, support for clang+gfortran-dragonegg has ended. Clang, Flang and AOCC: When I last checked (2018), flang was available from github with compile directions. Not simple to install. AMD released AOCC (AMD Optimizing C Compiler) suite v2.0 which is based on clang/flang with optional optimizations for Zen and Zen 2. This wgrib2 makefile has been tested with AOCC and a Ryzen 3600 on a Ubuntu 18.04LTS. According to AMD release documentation, AOCC has been tested by AMD on REL 7.4, SLES 12 sp3, and Ubuntu 18.04LTS. AOCC requires linux with glibc 2.17+. AOCC is freely available, works on Intel and AMD x86 cpus, and the AMD modifications get sent to LLVM for inclusion in to clang/flang. IMHO, it is an easy to install clang/flang. (Sooner or later, flang will be easy to install.) https://developer.amd.com/amd-aocc/ To compile with AOCC export CC=clang export FC=flang make To compile for Zen2 with AOCC wgrib2 v2.0.9 export CC=clang export FC=flang (add more info here) make