parameter (n=20)
integer, pointer :: a(:)
integer, target :: t(n)
interface
  subroutine sub(a,b,n)
    integer, pointer :: a(:)
    integer, pointer :: b(:)
  end subroutine
end interface

a => t
a = (/ (i, i=1,n) /)
call sub(a,a,n)
....
end
subroutine sub(a,b,n)
 integer, pointer :: a(:)
 real, pointer :: b(:)
 integer i, mold

 forall (i=2:n)
   a(i) = transfer(b(i-1), mold)
编译器必须假设 a 和 b 可以重叠。