See the I/OI API Troubleshooting Page on gfortran versions 10 or later https://cjcoats.github.io/ioapi/ERRORS.html#gfort10:
These versiona of gfortran take a particularly idiosyncratic interpretation of the (latest) Fortran-2018 Standard.
As of July 12, 2020, the relevant ioapi/Makeinclude.${BIN} files have been modified to add Fortran compile-flag
-std=legacy
so that this interpretation does not cause a compile-error.
However, using this compiler version will cause the generation of a huge number of spurious warning-messages, as the compiler is still trying to enforce its version of the Fortran-2018 (not Fortran-90, not Fortran-95, not Fortran-2008) Standard.Thanks to Mrs. Indumathi S Iyer, (SO/D), BARC, for pointing out this compiler-problem and help with testing the fix.—CJC
See ioapi/Makeinclude.Linux2_x86_64gfort10