[Bug fortran/93736] Add .f18 and .F18 file suffixes

[sgk at troutmask dot apl.washington.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93736

--- Comment #3 from Steve Kargl <sgk at troutmask dot apl.washington.edu> ---
On Thu, Feb 13, 2020 at 04:40:08PM +0000, thenlich at gcc dot gnu.org wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93736
> 
> --- Comment #2 from Thomas Henlich <thenlich at gcc dot gnu.org> ---
> I don't know why the Fortran compiler doesn't treat all files as free-form
> Fortran source files, unless they have a known extension indicating otherwise.

I suppose it has something to do with the fact that gfortran
will accept languages other than Fortran.

% gfortran9 -o z hello.c 
% ./z
hello

If you're really keen on the idea of adding yet another 
useless extension.  Look in gcc/fortran/lang-specs.h.

In 70 years, when F2090 is released, I'll let the next
generation deal with .F90 and .f90. :-)