What range of compilers should Fortran fpm support to build itself? Question is more regarding GCC version, but we could also discuss how Intel, PGI, NAG, ... compilers should work together with Fortran fpm. Of course this requirements for Fortran fpm becomes strict requirements for all dependencies used in Fortran fpm as well.

For example, if we want to distribute fpm with common toolchains like homebrew and conda-forge, we will have drastic limitations on the GCC version we can use:

• homebrew: GCC 5
• conda-forge: GCC 7.5

Supporting GCC 5 can be hard, because many features are missing. GCC 7.5 sounds reasonable to me, even if it means we might have to workaround some know ICE or bug at some point.