https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86566
--- Comment #3 from kargl at gcc dot gnu.org --- The proper way to preprocess Fortran code is with the Fortran compiler. You can and should use 'gfortran -cpp'. See the documentation that comes with your compiler. If you think you need to use gcc, then you must use the --tradition-cpp option. The Fortran concatenation operator // conflicts with modern C's comment delimiter //.
