J3/11-213
To: J3
From: Malcolm Cohen
Subject: Dummy procedure pointers and PRESENT
Date: 2011 June 29

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NUMBER: F03/0017
TITLE: Dummy procedure pointers and PRESENT
KEYWORDS: Dummy argument, procedure pointer, PRESENT
DEFECT TYPE: Interpretation
STATUS: J3 consideration in progress

QUESTION:

Does the following program conform to the Fortran standard?

  procedure(real), pointer :: F => null()
  call s ( f )
  contains
    subroutine S ( F )
      procedure(real), optional, pointer :: F
      print *, present(f)
    end subroutine S
  end

In the Fortran 2003 standard (ISO/IEC 1539-1:2004), the second
paragraph of 12.4.1.3 requires that if the dummy argument does not
have the POINTER attribute and the actual argument does, the actual
argument shall be associated.  It is not clear in 13.7.91 whether the
argument of PRESENT has or has not the POINTER attribute.

ANSWER:

The program is standard-conforming.

The Fortran 2008 standard states
  "Except in references to intrinsic inquiry functions, a pointer
   actual argument that corresponds to a nonoptional nonpointer dummy
   argument shall be pointer associated with a target."
(12.5.2.3 paragraph 1).

Since PRESENT is an intrinsic inquiry function, there is therefore no
requirement on its actual argument that if it is a pointer it shall be
associated.

EDIT:

None.

SUBMITTED BY: Van Snyder

HISTORY: 04-402    m170  F03/0017 submitted
         04-402r2  m170  Passed by J3 meeting
         05-146    m171  Failed J3 letter ballot #10
         11-nnn    m195  Revised answer.

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