The Modern Flang "f18" Compiler Is The Most Exciting Fortran Compiler Of Recent Times
This modern LLVM Fortran "Flang" compiler (based on the f18 code-base, not to be confused with the earlier Flang compiler) is quite promising for delivering a modern open-source Fortran experience being backed by Arm, AMD, and other vendors.
This modern Fortran compiler has been focused on Fortran 2018 compliance, is written using C++17 code, and fits well into the LLVM ecosystem with making use of features like the new MLIR intermediate representation.
The revised timeline for merging Flang into the LLVM source tree appears to be within the next month or two. But for getting the OpenMP features working well looks like it will take another year at least.
For those interested in Flang, Kiran Chandramohan of Arm talked about the Fortran compiler effort at last weekend's FOSDEM 2020 conference. There is the PDF slide deck for those wanting to learn more about this modern Fortran compiler for 2020 and beyond.