From owner-sc22wg5@open-std.org Wed Mar 17 09:19:09 2010 Return-Path: X-Original-To: sc22wg5-dom8 Delivered-To: sc22wg5-dom8@www2.open-std.org Received: by www2.open-std.org (Postfix, from userid 521) id 08DC8C178DF; Wed, 17 Mar 2010 09:19:09 +0100 (CET) X-Original-To: sc22wg5@open-std.org Delivered-To: sc22wg5@open-std.org Received: from ns.nag-j.co.jp (218-42-159-107.cust.bit-drive.ne.jp [218.42.159.107]) by www2.open-std.org (Postfix) with ESMTP id 1FF84C178D9 for ; Wed, 17 Mar 2010 09:19:05 +0100 (CET) Received: from 218-42-159-108.cust.bit-drive.ne.jp ([218.42.159.108] helo=Marucomputer) by ns.nag-j.co.jp with smtp (Exim 4.50) id 1NroSs-0000N3-CG for sc22wg5@open-std.org; Wed, 17 Mar 2010 17:18:54 +0900 Message-ID: <369D1B0CF1534CCE8FF9F7EB3F117D0E@Marucomputer> From: "Malcolm Cohen" To: "WG5" Subject: What shall we do with the broken feature? Date: Wed, 17 Mar 2010 17:19:29 +0900 Organization: =?iso-2022-jp?B?GyRCRnxLXBsoQk5BRw==?= MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-2022-jp"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 14.0.8089.726 X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8089.726 Sender: owner-sc22wg5@open-std.org Precedence: bulk The facility of being able to pass a null pointer or unallocated allocatable to an optional nonpointer nonallocatable dummy argument and have that treated as being an absent dummy argument is broken as follows. (i) All of the optional DIM arguments to the intrinsic functions that change the rank are qualified with "The corresponding actual argument shall not be an optional dummy argument.". Previously it was not permitted to pass a null pointer here, now it is permitted and gives a runtime-varying rank depending on the association status of the pointer. E.g. PRODUCT(matrix,pointer_to_dim) is rank 1 if pointer_to_dim is associated and rank 0 if it is not. 20 functions have a prohibition against optional dummy arguments, but in several of those it is an unnecessary prohibition so fewer than 20 would be necessarily affected. (ii) This feature appears to change the results of ASSOCIATED when TARGET is a null pointer. This does not appear on the surface to be fixable other than by specifying that the feature does not apply to this particular intrinsic function, which might be confusing. (iii) Minor: The performance of a few intrinsic functions such as MAX when some arguments are pointers is adversely affected. (iv) Nitpick: the description in the Introduction omits the unallocated allocatable case. How should we address the problem? (1) fix the DIS by deleting the feature (I don't think we have a mandate for that though); (2) fix the DIS by changing the wording; (2) leave it to be fixed later via interpretation processing (other than the nitpick which should be done anyway). Comments? Cheers, -- ................................Malcolm Cohen, Nihon NAG, Tokyo.