ISO/IEC JTC1/SC22/WG5 N1463

SECOND REPORT OF THE INTERPRETATIONS SUBGROUP

NUMBER: 000091
TITLE: Definition of "present" is defective
KEYWORDS: present, dummy argument
DEFECT TYPE: Erratum
STATUS: Passed by J3 letter ballot

QUESTION:

Subclause 12.4.1.5 begins with a definition of the term "present":

"A dummy argument is present in an instance of a subprogram if it is
associated with an actual argument and the actual argument either is a
dummy argument that is present in the invoking subprogram or is not a
dummy argument of the invoking subprogram."

This seems to be defective in that if the actual argument is a dummy
argument that is accessed by host association, it is not a dummy
argument OF the invoking subprogram, and therefore although it may be
"not present" in the procedure of which it is a dummy argument, it is
nonetheless "present" in an internal procedure of that procedure.

Consider:

  module M
  contains
    subroutine S1 ( A )
      integer, optional :: A
      call S11
    contains
      subroutine S11
        call S12 ( A )
      end subroutine S11
      subroutine S12 ( B )
        integer, optional :: B
        if ( present(B) ) print *, 'B is present'
      end subroutine S12
    end subroutine S1
  end module M

  program P
    use M, only: S1
    call S1
  end program P

Should this print "B is present" as implied by the above analysis?

ANSWER:

No, the program should not print anything.

DISCUSSION:

The lack of consideration of host association in the cited text is
accidental; an edit is supplied to correct this oversight.

EDITS:

[202:43-45] Replace the first sentence of 12.4.1.5 by
"A dummy argument or an entity that is host associated with a dummy 
argument is not <<present>> if the dummy argument
(1) is not associated with an actual argument, or
(2) is associated with an actual argument that is not present.
Otherwise, it is present."

[299:4-6] Delete the glossary entry for <<present>>

SUBMITTED BY: Van Snyder

HISTORY: 01-134   m156 Submitted
         01-134r1 m156 Passed unanimously by J3 meeting
         01-224r1 m157 Passed by J3 letter ballot
         WG5-N1395     Failed WG5 letter ballot
         WG5-N1463     Accepted Kurt Hirchert's suggestion with minor edits
----------------------------------------------------------------------

NUMBER: JP-05
TITLE: Construction of array values
KEYWORDS:
DEFECT TYPE:
STATUS: J3 consideration in progress

QUESTION:
JP-5)
  4.5 Construction of array values,

  "The ac-do-variable of an ac-implied-do that is in another
   ac-implied-do shall not appear as the ac-do-variable of the
   containing ac-implied-do."

  This sentence should be a Constraint.

ANSWER:   No. The requirement should be made a constraint in the next
standard. It should remain a simple requirement in Fortran 95.

EDIT: None

SUBMITTED BY: Japan
HISTORY: 99-208             Submitted
         99-221             Classed as Fortran 95 Interpretation.
         WG5-N1411          Draft answer
         00-260      m154   Passed by J3 meeting
         00-329      m155   Failed J3 letter ballot
         WG5-N1463          Accepted Henry's and Jon's comments

-------------------------------------------------------------------------

NUMBER: JP-31
TITLE: Signs of literal constants
KEYWORDS:
DEFECT TYPE:
STATUS: J3 consideration in progress

QUESTION:
JP-31)
  The fourth sentence of 10.8 and sixth sentence of 10.9:

  "Each value is either a null value or one of the forms:
        c
        r*c
        r*
   where c is a literal constant or a nondelimited character constant
   and r is an unsigned, nonzero, integer literal constant."

  "a literal constant" should be "an optionally signed literal
  constant"

ANSWER: Add the phrase, "if integer or real" to that last phrase
        above.

EDIT:
[175:5]  Replace "constant or" by "constant, optionally signed if
         integer or real, or"
[178:40] Replace "constant and" by "constant, optionally signed if
         integer or real, and"

Note for F2000:  The phrase "literal constant" [73:34] in F95 is not
                 the BNF term <lit-constant> but F95 doesn't say if
                 "literal constant" is signed.

SUBMITTED BY: Japan
HISTORY: 99-208             Submitted
         99-221             Classed as Fortran 95 Interpretation.
         WG5-N1411          Draft answer
         00-260      m154   Passed by J3 meeting
         00-329      m155   Failed J3 letter ballot
         WG5-N1463          Update to edit