[Bug fortran/66089] [6 Regression] elemental dependency mishandling when derived types are involved

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66089

--- Comment #10 from Mikael Morin <mikael at gcc dot gnu.org> ---
Here is a variant that fails similarly (even with the patch) with optional
arguments.

  type :: t
    integer :: c
  end type t

  type(t), dimension(5) :: a, b, c

  a = t(1)
  b = t(7)
  c = t(13)
  call do_bug(c, b)
  print *, c
  if (any(c%c /= 20)) call abort

contains

  elemental function plus(lhs, rhs)
    optional :: lhs
    type(t), intent(in) :: lhs, rhs
    type(t)             :: plus
    if (present(lhs)) then
      plus%c = lhs%c + rhs%c
    else
      plus%c = 0
    end if
  end function plus

  subroutine do_bug(lhs, rhs)
    type(t), intent(inout), optional :: lhs(5)
    type(t), intent(in) :: rhs(5)
    if (present(lhs)) then
      lhs = plus(lhs(1), rhs)
    end if
  end subroutine

end