[Bug fortran/67987] ICE on declaring and initializing character with negative len

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67987

--- Comment #3 from Steve Kargl <sgk at troutmask dot apl.washington.edu> ---
On Fri, Oct 16, 2015 at 06:03:06PM +0000, kargl at gcc dot gnu.org wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67987
> 
> --- Comment #2 from kargl at gcc dot gnu.org ---
> (In reply to kargl from comment #1)
> > I have a patch that I'm testing.  For the code in the
> > intial report I get
> > 
> > troutmask:sgk[238] gfc6 -c g6.f90
> > g6.f90:2:15:
> > 
> >     character(-8) :: c = ' '
> >                1
> > Error: LEN at (1) must be greater than or equal to 0
> 
> Seems the patch causes a regression for char_length_2.f90.
> This test came in with the fix for PR fortran/31250, where
> negative length parameters are silently set to 0.  The 
> fix for this regression is in resolve.c.  Unfortnately, 
> this fix then exposes an issue with substring referecences.
> For "string"(1:-1), this should result in a 0 length string,
> but gfortran is setting the length to -1 in 
> gfc_resolve_substring_charlen.
> 

Go the substring issued ironed out.