[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 #5 from Steve Kargl <sgk at troutmask dot apl.washington.edu> ---
On Thu, Feb 13, 2020 at 05:59:18PM +0000, thenlich at gcc dot gnu.org wrote:
> 
> --- Comment #4 from Thomas Henlich <thenlich at gcc dot gnu.org> ---
> Additionally, we could also imply -std=f2018 with the .f18/.F18 suffix. That
> would make them more useful.
> 

That would be a POLA as neither f03 nor f08 imply -std=f2003 or
-std=f2008.  AFAIK, these were added as a simply mnemonic for
the programmer.  By default, we have -std=gnu, which is a garabage
consumer (meaning, here's some code, do whatever it takes to 
compile it).  I think that that was a mistake, but that ship
sailed 15+ years ago.