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From: Mikael Morin <morin-mikael@orange.fr>
To: Thomas Koenig <tkoenig@netcologne.de>, Harald Anlauf <anlauf@gmx.de>
Cc: Mikael Morin <mikael@gcc.gnu.org>,
	gcc-patches@gcc.gnu.org, fortran@gcc.gnu.org
Subject: Re: [PATCH 09/10] fortran: Support clobbering of variable subreferences [PR88364]
Date: Tue, 20 Sep 2022 10:46:41 +0200	[thread overview]
Message-ID: <c18761e2-215a-8149-ff6e-00691536321e@orange.fr> (raw)
In-Reply-To: <10fc2a82-e23e-b488-66e3-9ef7c9e5d4ed@netcologne.de>

Le 20/09/2022 à 08:54, Thomas Koenig a écrit :
> 
> On 19.09.22 22:50, Mikael Morin wrote:
>> Le 19/09/2022 à 21:46, Harald Anlauf a écrit :
>>>
>>> Assumed size (*) is just a contiguous hunk of memory of possibly
>>> unknown size, which can be zero.  So you couldn't set a clobber
>>> for the a(1) actual argument.
>>>
>> Couldn't you clobber A entirely?  If no element of B is initialized in 
>> SUB, well, A has undefined values on return from SUB.  That's how 
>> INTENT(OUT) works.
> 
> Yes, I think so - you are passing the starting element of an array
> to an assumed-size array via storage association rules.
> 
> It has to be an explicit interface, of course, otherwise it is
> unclear if an array or an array element is passed.
> 

I have looked for the relevant excerpts from the standard.
 From 15.5.2.11 (sequence association):

> If the dummy argument is not of type character
> with default or C character kind, and the actual argument is an array element designator, the element sequence
> consists of that array element and each element that follows it in array element order.

> If the dummy argument is
> assumed-size, the number of elements in the dummy argument is exactly the number of elements in the element
> sequence.

So the dummy size, even if not known to the programmer, is clearly 
defined (to the full array size in your example).

  reply	other threads:[~2022-09-20  8:46 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-16 20:24 [PATCH 00/10] fortran: clobber fixes [PR41453] Mikael Morin
2022-09-16 20:24 ` [PATCH 01/10] fortran: Move the clobber generation code Mikael Morin
2022-09-16 20:24 ` [PATCH 02/10] fortran: Fix invalid function decl clobber ICE [PR105012] Mikael Morin
2022-09-16 20:24 ` [PATCH 03/10] fortran: Move clobbers after evaluation of all arguments [PR106817] Mikael Morin
2022-09-16 20:24 ` [PATCH 04/10] fortran: Support clobbering with implicit interfaces [PR105012] Mikael Morin
2022-09-16 20:24 ` [PATCH 05/10] fortran: Support clobbering of reference variables [PR41453] Mikael Morin
2022-09-16 20:24 ` [PATCH 06/10] fortran: Support clobbering of SAVE variables [PR87395] Mikael Morin
2022-09-16 20:24 ` [PATCH 07/10] fortran: Support clobbering of ASSOCIATE variables [PR87397] Mikael Morin
2022-09-16 20:24 ` [PATCH 08/10] fortran: Support clobbering of allocatables and pointers [PR41453] Mikael Morin
2022-09-16 20:24 ` [PATCH 09/10] fortran: Support clobbering of variable subreferences [PR88364] Mikael Morin
2022-09-17 17:03   ` Thomas Koenig
2022-09-17 19:33     ` Mikael Morin
2022-09-17 19:49       ` Bernhard Reutner-Fischer
2022-09-17 19:50       ` Mikael Morin
2022-09-17 21:24         ` Bernhard Reutner-Fischer
2022-09-18  6:12       ` Richard Biener
2022-09-18  9:10         ` Mikael Morin
2022-09-18 10:23           ` Thomas Koenig
2022-09-18 18:32             ` Harald Anlauf
2022-09-18 20:55               ` Mikael Morin
2022-09-19  7:11                 ` Mikael Morin
2022-09-19 19:46                 ` Harald Anlauf
2022-09-19 20:50                   ` Mikael Morin
2022-09-20  6:54                     ` Thomas Koenig
2022-09-20  8:46                       ` Mikael Morin [this message]
2022-09-20 21:08                     ` Harald Anlauf
2022-09-20 21:08                       ` Harald Anlauf
2022-09-21  9:57                       ` Thomas Koenig
2022-09-21 18:56                         ` Mikael Morin
2022-09-21 19:12                           ` Harald Anlauf
2022-09-21 19:12                             ` Harald Anlauf
2022-09-18 20:43             ` Mikael Morin
2022-09-18 10:48           ` Richard Biener
2022-09-19  7:31             ` Mikael Morin
2022-09-19  7:58               ` Richard Biener
2022-09-16 20:24 ` [PATCH 10/10] fortran: Support clobbering of derived types [PR41453] Mikael Morin

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