[Patch, fortran] PR34640 - ICE when assigning item of a derived-component to a pointer

[Thomas Koenig]

Hi Paul,

first, this patch looks really good - it certainly fixes a lot of the
ICEs.

I have a few points (a part already mentioned in private mail).

Consider the test case:

module x
   use iso_c_binding
   implicit none
   type foo
      complex :: c
      integer :: i
   end type foo
contains
   subroutine printit(c)
     complex, pointer, dimension(:) :: c
     integer :: i
     integer(kind=8) :: a
     a = transfer(c_loc(c(1)),a)
     print '(A,Z16)',"Adrress of first element is ", a
   end subroutine printit

   subroutine p2(c)
     complex, dimension(:), target :: c
     integer :: i
     integer(kind=8) :: a
     a = transfer(c_loc(c(1)),a)
     print '(A,Z16)',"Adrress of first element is ", a
   end subroutine p2

end module x

program main
   use x
   use iso_c_binding
   implicit none
   type(foo), dimension(5), target :: a
   integer :: i
   complex, dimension(:), pointer :: pc
   complex, dimension(4), target :: v
   integer(kind=8) :: s1, s2
   a%i = 0
   do i=1,5
      a(i)%c = cmplx(i**2,i)
   end do
   pc => a%c
   print *,"Pointer to complex passed to pointer argument:"
   call printit(pc)
   print *,"Pointer to complex passed to array argument"
   call p2(pc)
   s1 = transfer(c_loc(a(1)),s1)
   print '(A,Z16,/)',"Main program: Address of first element: ", s1

   pc => v
   print *,"Pointer to complex passed to pointer argument:"
   call printit(pc)
   print *,"Complex array passed to array argument"
   call p2(v)
   s1 = transfer(c_loc(v(1)),s1)
   print '(A,Z16)',"Address of first element: ", s1
end program main

This yields:

  Pointer to complex passed to pointer argument:
Adrress of first element is      10021C90FF0
  Pointer to complex passed to array argument
Adrress of first element is      10021C90FF0
Main program: Address of first element:     3FFFCEC599A4

  Pointer to complex passed to pointer argument:
Adrress of first element is      10021C90FF0
  Complex array passed to array argument
Adrress of first element is     3FFFCEC59A20
Address of first element:     3FFFCEC59A20

It appears that a temporary is created when passing
a pointer array to a pointer array dummy argument.
I think this would be wrong code, because the
subroutine could stash away the pointer and later
access data through it.

The same seems to happen when passing a pointer to
a normal argument - a temporary copy appears to be made.

While this code is correct, I am wodering if it
is intentional.  Is the span field in the array
descriptor used in the called subroutine?

Regards

	Thomas