J3/10-174
To: J3
From: Malcolm Cohen
Subject: Interp: dummy args of impure elemental procedure.
Date: 2010 June 02

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NUMBER:
TITLE: Dummy arguments of impure elemental procedures.
KEYWORDS: IMPURE, ELEMENTAL, INTENT
DEFECT TYPE: Erratum
STATUS: J3 consideration in progress

QUESTION:

Consider
  IMPURE ELEMENTAL SUBROUTINE swap1(a,b)
    REAL,INTENT(INOUT) :: a,b
    c = a
    a = b
    b = c
  END SUBROUTINE
  IMPURE ELEMENTAL SUBROUTINE swap2(a,b)
    REAL :: a,b
    c = a
    a = b
    b = c
  END SUBROUTINE

  ...
  REAL x,y(10)
  ...
  CALL swap1(x,y)   ! (a)
  CALL swap2(x,y)   ! (b)

The rules for arguments of elemental subroutines means that CALL (a)
is not standard-conforming.  However, since there are no rules
requiring declaration of INTENT (that being for PURE only), CALL (b)
is apparently standard-conforming.

Was this intended to be standard-conforming, and what should the
effect be?

ANSWER:

This was not intended to be standard-conforming.  Omission of the
requirement for INTENT specification was inadvertant.  An edit is
supplied to correct this oversight.

EDITS to 10-007:

[314:7] Insert new constraint at the end of 12.8.1
  "C1290a The <specification-part> of an impure elemental subprogram
          shall specify the intents of all of its dummy arguments that
          do not have the VALUE attribute."

ALTERNATIVE EDIT:

[314:7] Insert new constraint at the end of 12.8.1
  "C1290a The <specification-part> of an elemental subprogram shall
          specify the intents of all of its dummy arguments that do
          not have the VALUE attribute."

{This version has marginally simpler wording, at the cost of
 partly covering the same restriction as C1277.}

SUBMITTED BY: Malcolm Cohen

HISTORY: 10-174   m192 Submitted

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