[Bug fortran/58001] Make it possible to silence "Extension: Tab character in format" warning

["sgk at troutmask dot apl.washington.edu" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58001

--- Comment #8 from Steve Kargl <sgk at troutmask dot apl.washington.edu> ---
On Tue, Jul 30, 2013 at 06:16:27PM +0000, dominiq at lps dot ens.fr wrote:
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58001
> 
> --- Comment #7 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
> > With -Wno-tabs, gfortran should report a warning for the
> > occurence of every tab used in the context of a character
> > from the Fortran character set.  Taking your code, which I've
> > deleted here, and replace all whitespace by tabs, I get the
> > expected number of warnings.  Historically, I wanted to use
> > -Wtabs as you expected, but there was too much wailing on 
> > the gfortran lists, so it was changed to -Wno-tabs with the
> > meaning that "no tabs are allowed" in the context of the
> > Fortran character set.  You'll notice that tabs within
> > a literal character string are not flagged.
> 
> I cannot understand the rationale of this choice, but I guess it's too late to
> change it!-(
> 
> > The history of -Wtabs verse -Wno-tabs can be found in the mailinglist
> > archive.
> 
> No interest to dig the archives on this issue.

http://gcc.gnu.org/ml/fortran/2006-03/msg00226.html