[Bug fortran/35721] ASSOCIATED returns false when strides confusing

["dick dot hendrickson at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #2 from dick dot hendrickson at gmail dot com  2008-03-28 00:57 -------
Subject: Re:  ASSOCIATED returns false when strides confusing

On 27 Mar 2008 18:27:44 -0000, burnus at gcc dot gnu dot org
<gcc-bugzilla@gcc.gnu.org> wrote:
>
>
>  ------- Comment #1 from burnus at gcc dot gnu dot org  2008-03-27 18:27 -------
>  Confirm. Note NAG f95 complains the program is invalid and I think it is right:
>
>  Error: Explicit interface required for MG0028 from TRY_MG0028 - argument TDA2R
>  (no. 1) is a TARGET
>
Yes, you (and NAG) are correct.  Originally, the subroutine was in a big module
and when I cut it out I did the quick and dirty thing of merely
calling it without
thinking.  For what it's worth, the other g compiler I tried this on
also got the wrong
answer and didn't complain about the interface.

Dick Hendrickson

>  But this does not solve the gfortran problem ;-)
>
>  From the standard: (v) applies here, but (vii) is analog - except that TARGET
>  is a pointer instead of a target.
>
>  "Case (v): If TARGET is present and is an array target, the result is true if
>  the target associated with POINTER and TARGET have the same shape, are neither
>  of size zero nor arrays whose elements are zero-sized storage sequences, and
>  occupy the same storage units in array element order. Otherwise, the result is
>  false. If POINTER is disassociated, the result is false."
>
>  gfortran is failing since in dimension 1 they have different strides:
>  Pointer:  2:1:-2  (namely: element 2)
>  Target:   2:2:1   (namely: element 2)
>
>  However, libgfortran/intrinsics/associated.c only checks whether the stride is
>  the same. Proposed patch:
>
>  Index: libgfortran/intrinsics/associated.c
>  ===================================================================
>  --- libgfortran/intrinsics/associated.c (Revision 133633)
>  +++ libgfortran/intrinsics/associated.c (Arbeitskopie)
>  @@ -48,10 +48,12 @@ associated (const gfc_array_void *pointe
>    rank = GFC_DESCRIPTOR_RANK (pointer);
>    for (n = 0; n < rank; n++)
>      {
>  -      if (pointer->dim[n].stride != target->dim[n].stride)
>  +      long extent;
>  +      extent = pointer->dim[n].ubound - pointer->dim[n].lbound;
>  +
>  +      if (extent != (target->dim[n].ubound - target->dim[n].lbound))
>          return 0;
>  -      if ((pointer->dim[n].ubound - pointer->dim[n].lbound)
>  -          != (target->dim[n].ubound - target->dim[n].lbound))
>  +      if (pointer->dim[n].stride != target->dim[n].stride && extent != 0)
>          return 0;
>        if (pointer->dim[n].ubound < pointer->dim[n].lbound)
>         return 0;
>
>
>  --
>
>  burnus at gcc dot gnu dot org changed:
>
>            What    |Removed                     |Added
>  ----------------------------------------------------------------------------
>                  CC|                            |burnus at gcc dot gnu dot
>                    |                            |org
>              Status|UNCONFIRMED                 |NEW
>      Ever Confirmed|0                           |1
>    Last reconfirmed|0000-00-00 00:00:00         |2008-03-27 18:27:43
>                date|                            |
>
>
>  http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35721
>
>  ------- You are receiving this mail because: -------
>  You reported the bug, or are watching the reporter.
>


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35721