Ifort compiler doesn't recognize interface in Fortran

Question

When I try to compile code under the statement with ifort it returns error as:

    error #8169: The specified interface is not declare

But it works perfectly on gfortran, for some reason I have to use intel compiler to compile this work. The language I am using is Fortran. The reason for this is that the 'ifort' compiler does not see the variables in Interface. So I develop a module called Var to do fix that. And Use it in every blocks. But it returns error:

This USE statement is not positioned correctly within the scoping unit.

The var module is like following:

MODULE VAR
      CHARACTER(50) :: callbackID
END MODULE

how can I fix the problem thanks alot! My compiler version is ifort 12.1.0

      MODULE DEMO
      USE VAR
      INTERFACE
        SUBROUTINE callback_prototype(callbackID)
            USE VAR
            CHARACTER(*) :: callbackID
        END SUBROUTINE callback_prototype
      END INTERFACE

      PROCEDURE( callback_prototype ), POINTER :: f_ptr => NULL()

      CONTAINS
      SUBROUTINE set_callback(func)
         IMPLICIT NONE
         EXTERNAL :: func

          f_ptr => func
          call HELLO
      END SUBROUTINE

      SUBROUTINE invoke_callback(callbackID)
          CHARACTER(*) :: callbackID
          if (associated(f_ptr)) call f_ptr(callbackID)
      END SUBROUTINE

      SUBROUTINE HELLO

      IMPLICIT NONE

      !dosomthing


      END SUBROUTINE
      END MODULE

Answer 1

The code as presented is not legal fortran. The use statement inside the interface body makes accessible a name that is the same as a dummy argument. This violates the scoping rules of the language.

The use statement inside the interface body would appear to be superfluous.

Answer 2

I don't see the reason why you want the use statement in the interface in the first place. Even the interface can be skipped, because you have the right procedure accessible:

PROCEDURE( invoke_callback ), POINTER :: f_ptr => NULL()