Re: Derived types and allocatable

I must be more tired than I thought.  The code I posted previously is
obviously wrong, in a couple 
of embarrassing ways, and the reason for the access violation is clear. 
What I meant to do is shown 
below.  This code executes fine.  I thought I was on the scent of the bug
in my real program, but I 
was confused.  The interesting thing (to me) here is that the assignment
cell2(i) = cell1(i) has the 
effect of allocating cell2(i)%cdata.  Should this be obvious?

program main
integer :: csize(2) = (/10,100/)
integer :: k, i
type cell_type
     integer :: ID
     real, allocatable :: cdata(:)
end type
type(cell_type), allocatable :: cell1(:),cell2(:)

allocate(cell1(2))
allocate(cell2(2))

do i = 1,2
     allocate(cell1(i)%cdata(csize(i)))
     do k = 1,csize(i)
         cell1(i)%cdata(k) = k
     enddo
enddo

do i = 1,2
     cell2(i) = cell1(i)     ! cell2(i)%cdata not allocated before this
     write(*,*) cell2(i)%cdata
enddo

do i = 1,2
     if (allocated(cell1(i)%cdata)) then
         deallocate(cell1(i)%cdata)
     endif
enddo
if (allocated(cell1)) then
     deallocate(cell1)
endif
do i = 1,2
     if (allocated(cell2(i)%cdata)) then
         write(*,*) 'deallocate cell2(i)%cdata: ',i
         deallocate(cell2(i)%cdata)
     endif
enddo
if (allocated(cell2)) then
     deallocate(cell2)
endif

end