To: J3                                                       J3/10-134
From: Van Snyder
Subject: Interp F03/0138
Date: 2010 February 16

Interp F03/0138 as balloted
---------------------------

Interp F03/0138 failed WG5 letter ballot

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

NUMBER: F03/0138
TITLE: External <procedure-name> as <proc-target>
KEYWORDS: procedure name, procedure pointer, procedure pointer
assignmant
DEFECT TYPE: Erratum
STATUS: Passed by J3 letter ballot

QUESTION:

7.4.2 C727 says a "<procedure-name> [that is a <proc-target>] shall
be the name of an external ... procedure...."

To be passed as an actual argument, a procedure needs to have the
EXTERNAL attribute, but there appears to be no such requirement for
being a target in a procedure pointer assignment.

(1) Is the following example standard-conforming?

  PROGRAM example1
  PROCEDURE(),POINTER :: p
  PROCEDURE(REAL),POINTER :: q
  p => x
  CALL x
  q => y
  PRINT *,y(5)
  CALL p
  PRINT *,q(5)
  END
  SUBROUTINE x
  PRINT *,'ok so far'
  END
  FUNCTION y(n)
  y = SQRT(REAL(n))
  END

(2) If example1 is standard-conforming, is this example conforming?

  MODULE exmod
    PROCEDURE(),POINTER :: p
  CONTAINS
    SUBROUTINE test
      CALL p
    END SUBROUTINE
  END
  PROGRAM example2
    USE exmod
    p => x
    CALL test
  END
  SUBROUTINE x
    PRINT *,'ok'
  END

ANSWER:

(1) Yes, this example is conforming.  As correctly noted, there is no
    requirement for the EXTERNAL attribute in a procedure pointer
    assignment, and both X and Y are known within the main program
    to be external procedures.

(2) This example was not intended to be conforming.  An edit is
    provided to clarify this.

EDIT:

[144:5-6] In 7.4.2 Pointer assignment, constraint C727,
   Change "an external, module," to "a module",
   Change "or a procedure pointer" to
     "a procedure pointer, or an external procedure that is accessed by
      USE or host association and is referenced in the scoping unit as a
      procedure, or that has the EXTERNAL attribute".

This makes the revised constraint

"C727 (R742) A <procedure-name> shall be the name of a module or dummy
  procedure, a specific intrinsic function listed in 13.6 and not marked
  with a bullet ($\bullet$), a procedure pointer, or an external
  procedure that is accessed by USE or host association and is
  referenced in the scoping unit as a procedure, or that has the
  EXTERNAL attribute."

SUBMITTED BY: Van Snyder

HISTORY: 09-281    m189  F03/0138 submitted - Passed by J3 meeting
         09-xxx    m190  Passed by J3 letter ballot #19 09-292

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

Edits for 09-007r3
------------------

[159:1-2] In 7.2.2.2 Syntax of the pointer assignment statement,
constraint C730
   Change "external, internal," to "internal",
   Change "a procedure pointer" to
     "a procedure pointer, an external procedure that is accessed by USE
      or host association and is referenced in the scoping unit as a
      procedure or that has the EXTERNAL attribute".

This makes the revised constraint

"C730 (R740) A <procedure-name> shall be the name of an internal,
  module, or dummy procedure, a procedure pointer, an external procedure
  that is accessed by USE or host association and is referenced in the
  scoping unit as a procedure or that has the EXTERNAL attribute, or a
  specific intrinsic function listed in 13.6 and not marked with a
  bullet ($\bullet$)."

{Notice that "internal" had been added in 09-007r3.}