https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103434
Bug ID: 103434
Summary: Pointer subobject does not show to correct memory
location
Product: gcc
Version: 10.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: baradi09 at gmail dot com
Target Milestone: ---
Based on the discussion on FD
(https://fortran-lang.discourse.group/t/is-the-section-of-a-pointer-to-an-array-a-valid-pointer/2331),
I'd assume, that the following code is standard conforming. However, the result
with gfortran seems to be incorrect.
*** Code:
module test
implicit none
type :: pointer_wrapper
real, pointer :: ptr(:) => null()
end type pointer_wrapper
contains
subroutine store_pointer(wrapper, ptr)
type(pointer_wrapper), intent(out) :: wrapper
real, pointer, intent(in) :: ptr(:)
wrapper%ptr => ptr
end subroutine store_pointer
subroutine use_pointer(wrapper)
type(pointer_wrapper), intent(inout) :: wrapper
wrapper%ptr(:) = wrapper%ptr + 1.0
end subroutine use_pointer
end module test
program testprog
use test
implicit none
real, allocatable, target :: data(:,:)
real, pointer :: ptr(:,:)
type(pointer_wrapper) :: wrapper
integer :: ii
allocate(data(4, 2))
ptr => data(:,:)
data(:,:) = 0.0
do ii = 1, size(data, dim=2)
print *, "#", ii
print *, "BEFORE ", ii, maxval(ptr(:,ii))
call store_pointer(wrapper, ptr(:,ii))
print *, "BETWEEN", ii, maxval(ptr(:,ii))
call use_pointer(wrapper)
print *, "AFTER ", ii, maxval(ptr(:,ii))
end do
end program testprog
*** Output:
# 1
BEFORE 1 0.00000000
BETWEEN 1 0.00000000
AFTER 1 1.00000000
# 2
BEFORE 2 1.00000000
BETWEEN 2 1.00000000
AFTER 2 1.00000000
*** Expected output:
# 1
BEFORE 1 0.00000000
BETWEEN 1 0.00000000
AFTER 1 1.00000000
# 2
BEFORE 2 0.00000000
BETWEEN 2 0.00000000
AFTER 2 1.00000000
It seems, as if store_pointer would point to a memory location larger as it
should be, so that also data outside of the actual stride is modified. Intel
and NAG deliver the expected output.
