I'm replying here because I think it's part of this bug, but more severe in practice. It was evidently built with gfortran-10, but depends on gfortran-9, which doesn't recognize these arguments.
$ cat > a.f90 program main end ^D $ mpifort a.f90 f95: error: unrecognized command line option ‘-fallow-invalid-boz’ f95: error: unrecognized command line option ‘-fallow-argument-mismatch’; did you mean ‘-Wno-argument-mismatch’? This can be worked around if one has gfortran-10 installed: $ MPICH_CC=gfortran-10 mpifort a.f90 $ $ mpifort -show f95 -O2 -fdebug-prefix-map=/build/mpich-Aiaw9P/mpich-3.4~a2+really3.3.2=. -fstack-protector-strong -fallow-invalid-boz -fallow-argument-mismatch -Wl,-z,relro -I/usr/include/x86_64-linux-gnu/mpich -I/usr/include/x86_64-linux-gnu/mpich -L/usr/lib/x86_64-linux-gnu -lmpichfort -lmpich
