unlimited polymorphic parameter and transfer intrinsic

Trying to use polymorphism with the transfer intrinsic, I ran into a behaviour that I don't understand.

With the following test program, i get the following output :

storage req. size =           16

text = h!O�p!O��

If I replace "class default" with "class is (str)", I get the expected :

storage req. size =           16

text = hello !

Am I doing something wrong ?

Thanks !

Franck

module polymorphic

   character(len=1), private, dimension(:), allocatable :: storage

   type  str
       character(len=16) :: text
   end type str

contains
   subroutine store(arg)
      implicit none

      class(*), intent(in)      :: arg

      integer   :: i_size
      type(str) :: probe

      select type (arg)
!         class is (str)
         class default
            i_size = size(transfer(arg,storage))
            write (*,*) ' storage req. size = ',i_size
            allocate(storage(i_size))
            storage = transfer(arg,storage)

            probe = transfer(storage, probe)
            write (*,*) 'text = ', probe%text
     end select
   end subroutine store

end module polymorphic


program test_polymorphic
  use polymorphic

  type(str) :: input
  input%text = 'hello !'

  call store(input)

end program test_polymorphic