[Bug fortran/52012] [4.6/4.7 Regression] Wrong-code with realloc on assignment and RESHAPE w/ ORDER=

["burnus at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52012

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.6/4.7 Regression]        |[4.6/4.7 Regression]
                   |Wrong-code with realloc on  |Wrong-code with realloc on
                   |assignment                  |assignment and RESHAPE w/
                   |                            |ORDER=

--- Comment #4 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-01-27 09:18:10 UTC ---
Up and including the RESHAPE call, everything looks fine. However, one then
updates the bounds as follows, which seems to fail.

If one does not use RESHAPE with the ORDER= argument, it works that the
"shape(a)" is used as argument to RESHAPE does not play a role.

          a.offset = 1;
          a.dim[0].lbound = 1;
          a.dim[0].ubound = a.dim[0].ubound + 1;
          a.offset = (a.dim[0].ubound - a.dim[0].lbound) + 1;
          a.dim[1].lbound = 1;
          a.dim[1].ubound = a.dim[1].ubound + 1;
          a.offset = (a.dim[1].ubound - a.dim[1].lbound) + 1;
          a.dim[2].lbound = 1;
          a.dim[2].ubound = a.dim[2].ubound + 1;
          a.offset = ~((a.dim[0].ubound - a.dim[0].lbound) + 1)
                   + ~(a.dim[1].ubound - a.dim[1].lbound);

 * * *

Additionally, the realloc on assignment may sets the wrong bounds if no
(re)allocation is needed. From trans-expr.c's fcncall_realloc_result:

  /* Now reset the bounds from zero based to unity based.  */

That's wrong. The lower bounds are remain the same, unless the RHS has a
different shape. Then, the LHS is reallocated with a lower bound of
lbound(RHS).

Thus, one expects "7 9 / 1 3" for the program below, but gfortran has "1 3  / 
1 3". Using for the RHS external functions, other expressions and variables
correctly keep the bounds, if no realloc happens.


integer, allocatable :: a(:), b(:)
allocate(b(3))
b = [1,2,3]

allocate (a(7:9))
a = reshape( b, shape=[size(b)])
print *, lbound(a), ubound(a) ! Expected: 7 9

deallocate (a)
a = reshape( b, shape=[size(b)])
print *, lbound(a), ubound(a) ! Expected: 1 3
end