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Subject: [Bug fortran/55072] New: [4.5/4.6/4.7/4.8 Regression] Missing internal_pack leads to wrong code with derived type
Date: Thu, 25 Oct 2012 09:22:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55072

             Bug #: 55072
           Summary: [4.5/4.6/4.7/4.8 Regression] Missing internal_pack
                    leads to wrong code with derived type
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: burnus@gcc.gnu.org


The following code should print (and does so with GCC 4.1, 4.3 and 4.4):
           1           9           3          11
           1           9           3          11
However, starting from GCC 4.5, it prints:
           1           9           3          11
           1           5           9          13

The reason is that the passed pointer is not packed but directly passed (with
array descriptor, which is not used):

  bar ((struct t[0:] *) p.data);

while gfortran 4.4 correctly uses:

    D.1575 = _gfortran_internal_pack (&p);
    bar (D.1575);


implicit none
type t
integer :: i
end type t
type(t), target :: tgt(4,4)
type(t), pointer :: p(:,:)
integer :: i,j,k

k = 1
do i = 1, 4
  do j = 1, 4
    tgt(i,j)%i = k
    k = k+1
  end do
end do

p => tgt(::2,::2)
print *,p%i
call bar(p)

contains

  subroutine bar(x)
    type(t) :: x(*)
    print *,x(1:4)%i
    if (any (x(1:4)%i /= [1, 9, 3, 11])) call abort()
  end subroutine
end