The legacy Flang and a new Flang. I don't know exactly the plans for the legacy Flang, but I assume the idea is to eventually use new Flang. The new Flang and LFortran where started at about the same time, they have a little bit different design. Both written in C++. LFortran has from the ground up written to be interactive (like Julia or Python), in addition to regular compilation to binaries. Some of the other goals of Flang and LFortran overlap.
I think it's good for Fortran to have at least two actively developed open source compilers.
https://fortran-lang.org/compilers/
The legacy Flang and a new Flang. I don't know exactly the plans for the legacy Flang, but I assume the idea is to eventually use new Flang. The new Flang and LFortran where started at about the same time, they have a little bit different design. Both written in C++. LFortran has from the ground up written to be interactive (like Julia or Python), in addition to regular compilation to binaries. Some of the other goals of Flang and LFortran overlap.
I think it's good for Fortran to have at least two actively developed open source compilers.