finalization of function return type memory leak ?

Hi,

I have a memory leak with the return variable of a constructor. If the allocation is made out of the constructor then the component is automatically deallocated after. The following code show the behavior. If the class(*) is replace by an integer there is no memory leak. Of course if i write a final subroutine that deallocate it solves the issue, but then what is the exact rule for automatic finalization for derived type and extended derived type.

Thanks.

module tata
implicit none

type :: b_type
        class(*),allocatable :: b
        !integer ,allocatable :: b  !  NO LEAK with an integer
end type

        type,extends(b_type) :: intb
        end type
        interface intb
                module procedure :: intb_constructor
        end interface
contains
function intb_constructor(i) result(a)
        type(intb) :: a
        integer :: i
        allocate(a%b,source=i)
end function
end module

program foo
use tata
implicit none
type(intb) :: d,d2,c,c2
type(b_type) :: e1,e2
integer :: j
j=1
allocate(e1%b,source=j)
allocate(e2%b,source=j)

allocate(d%b,source=j)
allocate(d2%b,source=j)

c=intb(1)
c2=intb(3)


end program

==14632== 4 bytes in 1 blocks are definitely lost in loss record 7 of 9
==14632==    at 0x4C29F90: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==14632==    by 0x41C83F: for_allocate (in /home/patrice/Projects/fortran_rbtree/a.out)
==14632==    by 0x40368B: do_alloc_copy (in /home/patrice/Projects/fortran_rbtree/a.out)
==14632==    by 0x40441B: for_alloc_copy (in /home/patrice/Projects/fortran_rbtree/a.out)
==14632==    by 0x402A34: tata_mp_intb_constructor_ (finalbug.f90:17)
==14632==    by 0x402F0E: MAIN__ (finalbug.f90:34)
==14632==    by 0x4027CD: main (in /home/patrice/Projects/fortran_rbtree/a.out)
==14632==
==14632== 4 bytes in 1 blocks are definitely lost in loss record 8 of 9
==14632==    at 0x4C29F90: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==14632==    by 0x41C83F: for_allocate (in /home/patrice/Projects/fortran_rbtree/a.out)
==14632==    by 0x40368B: do_alloc_copy (in /home/patrice/Projects/fortran_rbtree/a.out)
==14632==    by 0x40441B: for_alloc_copy (in /home/patrice/Projects/fortran_rbtree/a.out)
==14632==    by 0x402A34: tata_mp_intb_constructor_ (finalbug.f90:17)
==14632==    by 0x40304D: MAIN__ (finalbug.f90:35)
==14632==    by 0x4027CD: main (in /home/patrice/Projects/fortran_rbtree/a.out)
==14632==
==14632== LEAK SUMMARY:
==14632==    definitely lost: 8 bytes in 2 blocks
==14632==    indirectly lost: 0 bytes in 0 blocks
==14632==      possibly lost: 0 bytes in 0 blocks
==14632==    still reachable: 56 bytes in 7 blocks
==14632==         suppressed: 0 bytes in 0 blocks