J3/07-172

Date: 2007 February 15
To:      J3
From:    Stan Whitlock
Subject: Defined operations/assignments and VOLATILE/ASYNCHRONOUS

NUMBER: F03/00088
TITLE: Defined operations/assignments and VOLATILE/ASYNCHRONOUS
KEYWORDS: Defined operations, defined assignment, VOLATILE,
          ASYNCHRONOUS
DEFECT TYPE: Interpretation
STATUS: J3 consideration in progress

PROBLEM:

  Fortran 2008 Unresolved Technical issue 097 asked a question that
  also affects Fortran 2003.  Consider this example:

          INTERFACE ASSIGNMENT(=)
             SUBROUTINE s(a,b)
                 REAL,INTENT(OUT),VOLATILE :: a(*)
                 REAL,INTENT(IN) :: b(:)
             END SUBROUTINE
          END
          REAL,POINTER :: p(:),q(:)
          ...
          CALL s(p,q)    ! Violation of constraint C1233 [271:9-11],
                         !  associating P with A
          p = q          ! No constraint violation because <actual-arg>
                         !  syntax is not being used

QUESTION:

  Did Fortran 2003 intend to enforce constraints on <actual-arg> in
  defined assignment?

ANSWER:

 Yes, the <actual-arg> constraints and restrictions should be enforced
 in defined assignment and in defined operator evaluation.

 Edits are provided below to do this.

EDITS:

  [262:16] add at the end of the paragraph
   " All restrictions and constraints that apply to actual arguments
    in a reference to the function also apply to the corresponding
    operands in the expression as if they were used as actual arguments."

  [263:12] insert after "the second argument."
   " All restrictions and constraints that apply to actual arguments
    in a reference to the subroutine also apply to the left-hand-side
    and to the right-hand-side enclosed in parenthesis as if they were
    used as actual arguments."

SUBMITTED BY: Stan Whitlock

HISTORY: J3/07-172  m179 Submitted {see 07-171 for F08 fix}