I'd like to see if we could get support for a newer icecc_create_env. It appears our current version is from no later than 2018, and substantial improvements appear to have gone in during 2019, which in particular add support for clang built with shared libraries.

The main difficulty I encountered trying to pull something newer in was that current master copies of the script no longer appear to support an $out_file (it's easy enough to add back in, but isn't directly in the upstream).