Intel Fortran does not compile this :(

gistfile1.f90

MODULE a
    IMPLICIT NONE
    INTEGER(4), PUBLIC :: x1
    INTEGER(4), PUBLIC :: x2
END MODULE a

MODULE a2
    IMPLICIT NONE
    INTEGER(4), PUBLIC :: x1
    INTEGER(4), PUBLIC :: x2
END MODULE a2

MODULE b
    USE a
    IMPLICIT NONE
    PRIVATE
    INTERFACE c
      MODULE PROCEDURE d
    END INTERFACE c
    PUBLIC :: c
  CONTAINS
    SUBROUTINE d(w)
        IMPLICIT NONE
        INTEGER(4), OPTIONAL :: w(x1:x2)

    END SUBROUTINE d

END MODULE b

MODULE main
    USE a2
    USE b
    IMPLICIT NONE
  CONTAINS
    SUBROUTINE foo()
        IMPLICIT NONE
        INTEGER(4) :: i

        CALL c()
        DO i = x1, x2, 1  ! <-- References to x1 and x2 fail
          CONTINUE
        END DO
    END SUBROUTINE foo

END MODULE main

Workaround, in line 32 replace

USE B

by

USE B, ONLY : C