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From: "mikael at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug fortran/102043] Wrong array types used for negative stride
 accesses
Date: Fri, 12 Nov 2021 19:30:25 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102043

--- Comment #12 from Mikael Morin <mikael at gcc dot gnu.org> ---
(In reply to Thomas Koenig from comment #11)
> (In reply to Richard Biener from comment #10)
>=20
> > Is there any case where the frontend would make 'data' point into the
> > middle of the array and iteration over the array would end up accessing
> > elements on "both sides"?  Can somebody write a short testcase where th=
at
> > would happen?
>=20
> I've tried, but I have been unable to find such a test case, and
> I do not think this can (or should) happen.

I would say it can happen as things stand, when one dimension is accessed g=
oing
backward and another going forward.

program main
   implicit none
   integer, dimension :: a(4, 4)
   a =3D 0
   call s(a(4:1:-1,:))
   if (any(a /=3D 10)) stop 1
contains
  subroutine s(b)
    implicit none
    integer, dimension(:,:) :: b
    b =3D 10
  end subroutine s
end program main=