From August 18, 2020
I was using the Anaconda version of gfortran, and encountering problems with runtime libraries. I had used the standard MacOS C-compiler clang as an alias for my gcc, and clang lacks fortran support.
I switched to gcc-10 and gfortran-10, as of this date. The runtime library problems I had yesterday afternoon induced me to install a fresh compiler via the Fink project. http://www.finkproject.org I am still checking that things are working correctly -- Catalina messed up more of my computing environment than I knew.
some info on this issue from a real programmer is here
https://solarianprogrammer.com/2019/10/12/compiling-gcc-macos/
And my commands were
fink selfupdate
fink install gcc10
The fink command compiled the compilers from scratch, so it too a few hours on a 2019 MacBook Pro. Dont try this just before you need to carry your laptop someplace.
