[Bug fortran/59720] [OOP] class/extends, multiple generic assignment

["janus at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59720

--- Comment #6 from janus at gcc dot gnu.org ---
To add to this discussion, here are two examples from the F08 standard (section
C.9.6):


module fruits

  type :: fruit
  end type

  type, extends(fruit) :: apple
  end type

  type, extends(fruit) :: pear
  end type

  type, extends(pear) :: bosc
  end type

  INTERFACE BAD6 ! this interface is invalid !
    SUBROUTINE S6A(X,Y)
      import :: pear
      CLASS(PEAR) :: X,Y
    END SUBROUTINE S6A
    SUBROUTINE S6B(X,Y)
      import :: fruit, bosc
      CLASS(FRUIT) :: X
      CLASS(BOSC) :: Y
    END SUBROUTINE S6B
  END INTERFACE BAD6

  INTERFACE GOOD7
    SUBROUTINE S7A(X,Y,Z)
      import :: pear
      CLASS(PEAR) :: X,Y,Z
    END SUBROUTINE S7A
    SUBROUTINE S7B(X,Z,W)
      import :: fruit, bosc, apple
      CLASS(FRUIT) :: X
      CLASS(BOSC) :: Z
      CLASS(APPLE),OPTIONAL :: W
    END SUBROUTINE S7B
  END INTERFACE GOOD7

end


gfortran correctly rejects the first one and allows the second (both with and
without the patch in comment 2).

However, ifort 12.1 seems to accept both, which clearly violates the F08
standard. I also tried flags like -std03 and -std08, without any effect. Are
there other flags to force a more strict adherence to the standard?

Is anyone able to check other compilers?