[Bug fortran/125747] ICE in gfc_add_modify_loc, at fortran/trans.cc:229 since r16-5177

[kargl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125747

--- Comment #6 from Steve Kargl <kargl at gcc dot gnu.org> ---
(In reply to Harald Anlauf from comment #4)
> 
> I think we should not allow this extension for modern DO constructs.
>

I think it should be disallowed in FORALL as well.  The error
message in resolve.cc(gfc_resolve_iterator) is guarded with 
gfc_notify_std (GFC_STD_F95_DEL...).   F95 never allowed REAL 
iterators and FORALL was introduced in this standard.

F95, p.114

R750  forall-triplet-spec  is index-name = subscript : subscript [ : stride]
R617  subscript            is scalar-int-expr
R603  stride               is scalar-int-expr

If it breaks code in the wild, so what?  The code was never correct.