[Bug fortran/58310] New: Allocatable component arrays: Wrong code after calling a subroutine

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58310

            Bug ID: 58310
           Summary: Allocatable component arrays: Wrong code after calling
                    a subroutine
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
                CC: pault at gcc dot gnu.org

As reported by James Spencer at
https://groups.google.com/forum/#!topic/comp.lang.fortran/VuFvOsLs6hE

The call to the subroutine causes copy-in/copy-out - and that somehow causes
that that access to invalid memory.

(Side remark: I think the copy-in/copy-out is required as we do not have byte
strides, just element-based strides. See
http://gcc.gnu.org/wiki/ArrayDescriptorUpdate)



Output of the code below:

           1           1
           2           2
 in s1:            1           1
 in s1:            2           2
           0           0
    21884992           0
Program received signal SIGABRT: Process abort signal.



When run under valgrind, the output is correct - but one gets two errors: Once
directly after the subroutine call:

==21383== Invalid read of size 4
==21383==    at 0x4F15AB0: extract_int (write.c:440)
==21383==    by 0x4F17020: write_integer (write.c:1250)

And at the very end:
==21383== Invalid free() / delete / delete[] / realloc()




Here is the code which causes the problems with GCC 4.3 to GCC 4.9:

program p
    implicit none

    type x_t
        integer, allocatable :: v(:)
    end type x_t
    type y_t
        type(x_t) :: x
    end type y_t

    type(y_t), allocatable, target :: y(:)
    integer :: i
    integer, parameter :: N=2

    allocate(y(N))
    do i = 1,N
        allocate(y(i)%x%v(N))
        y(i)%x%v = i
    end do

    do i = 1,N
        write (6,*) y(i)%x%v
    end do

    call s1(y%x)

    do i = 1,N
        write (6,*) y(i)%x%v
    end do

    deallocate(y)
  contains
    subroutine s1(x)
      type(x_t), intent(inout) :: x(:)
      integer :: i
      do i = 1, size(x)
        print *, 'in s1: ', x(i)%v
      end do
    end subroutine s1
end program p