Polymorphic dummy argument not interoperable

I'm trying to do some black magic.....namely, I've created a C routine which performs a memset() on the array or structure passed to it:

typedef ptrdiff_t CFI_type_t;

typedef struct CFI_dim_t_
{
  CFI_index_t extent;
  CFI_index_t sm;
  CFI_index_t lower_bound;
} CFI_dim_t;

typedef struct CFI_cdesc_t_
{
  void *base_addr;
  size_t elem_len;
  int version;
  CFI_attribute_t attribute;
  CFI_rank_t rank;
  CFI_type_t type;
  // Begin Intel-specific fields - these are for
  // Intel compiler/library use only and should
  // not be modified
  intptr_t intel_flags;
  intptr_t intel_reserved1;
  intptr_t intel_reserved2;
  // End Intel-specific fields
  CFI_dim_t dim[];
} CFI_cdesc_t;

void fortran_init( CFI_cdesc_t *a ) {
  memset( a->base_addr, 0, a->elem_len );
  return;
}

My Fortran interface definition goes as such:

INTERFACE
  SUBROUTINE FORTRAN_INIT( A ) BIND(C, NAME='fortran_init')
    IMPLICIT    NONE
    CLASS (*), INTENT(IN)    :: A
  END SUBROUTINE FORTRAN_INIT
END INTERFACE

When I compile this using version 15.0.2, everything works fine, and the execution behaves as-expected (I can view all the descriptor properties in the debugger).  However, when I compile with the newest version of ifort, I get the following:

#8789: Polymorphic dummy argument to a BIND(C) procedure is not interoperable.

Should I be using a different prototype on the Fortran side to get the CFI_cdesc_t descriptor passed to it properly?

Thanks in advance.