J3/04-323

Date:    13 May 2004
To:      J3
From:    Richard Maine
Subject: Type-bound procedures and undefined association status

NUMBER:
TITLE: Type-bound procedures and undefined association status
KEYWORDS: Type-bound procedure, dynamic type
DEFECT TYPE:
STATUS: J3 consideration in progress

QUESTION: It appears that the dynamic type is undefined for
a pointer with undefined association status.  This impacts
type-bound procedures. Consider the following program.

  program undefined

    type :: t
    contains
      procedure :: nondeferred_proc => sub
    end type t
    type, extends(t) :: t2
    contains
      procedure :: nondeferred_proc => sub2
    end type t2

    class(t), pointer :: x

    call x%nondeferred_proc

  contains
    subroutine sub
      write (*,*) 'Hello.'
    end subroutine sub
    subroutine sub2
      write (*,*) 'Goodbye.'
    end subroutine sub2
  end program defer

Is this a valid program?  If not, what restriction of the
standard does it violate?  If so, what does it print.

Note that x%nondeferred_proc does not require the value of x (4.5.7)
and thus is not a reference to x (2.5.6).  Therefore, [83:23-24]
does not prohibit this.

If x were disassociated, its dynamic type would be t and the
interpretation of this would be reasonably clear.

However, the standard does not appear to specify the dynamic type
of x when its association status is undefined.  Nor can I find
any prohibition that applies to this case.

ANSWER:

Beat's me.  (This one really needs a better answer.)  :-(

EDITS:

SUBMITTED BY: Richard Maine

HISTORY: J3/04-323   m169 Submitted