This is the mail archive of the fortran@gcc.gnu.org mailing list for the GNU Fortran project.

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]
Other format:	[Raw text]

Re: Adding UNION/MAP -- Feedback and tips pls!

From: "N.M. Maclaren" <nmm1 at cam dot ac dot uk>
To: gcc at gcc dot gnu dot org, "fortran at gcc dot gnu dot org" <fortran at gcc dot gnu dot org>
Date: 06 Mar 2013 19:46:58 +0000
Subject: Re: Adding UNION/MAP -- Feedback and tips pls!
References: <51314549.6080902@earthlink.net> <Prayer.1.3.5.1303020815470.18790@hermes-1.csi.cam.ac.uk> <CAGkQGiL7Qg0RAqJrT5i4LDzjnsr3jQ42Ws2BQFDpPUHyQe3+WQ@mail.gmail.com> <CAKwh3qgyS0nRcGSE5UT+DN+11kjYRE9Vu7SsQ_AGPtuD7VV4dA@mail.gmail.com> <Prayer.1.3.5.1303021519480.2329@hermes-1.csi.cam.ac.uk> <CAAKgPaHZwaoSBVg-hNZxan-uAtnmEBjPxyv9iuh=xdOshFp1uQ@mail.gmail.com> <Prayer.1.3.5.1303041813340.19357@hermes-1.csi.cam.ac.uk> <CAAKgPaGtNQoA=2h+5Z8DmvgsEBKUKX78Ojwi_SY2RG8hUcksOg@mail.gmail.com> <Prayer.1.3.5.1303042034040.18634@hermes-1.csi.cam.ac.uk> <51378C6D.5060609@netcologne.de> <CA+=Sn1kGyBabx+JgrPFJQ6GKU+PbfagygG16=oAhC6qyW1b7Rg@mail.gmail.com>

On Mar 6 2013, Andrew Pinski wrote:


Except GCC implements C's unions as allowing to do type punning as an
extension and as far as GCC is concerned that is not going to change
any time soon.
This is a documented exception to the aliasing/type punning rules.


The problem is that this is worse than type punning, because it also
allows the preservation of data.  Does the extension guarantee that,
or would it need a change to at least the documentation?


Regards,
Nick Maclaren.

Follow-Ups:
- Re: Adding UNION/MAP -- Feedback and tips pls!
  - From: Joseph S. Myers
- Re: Adding UNION/MAP -- Feedback and tips pls!
  - From: Ian Lance Taylor

References:
- Re: Adding UNION/MAP -- Feedback and tips pls!
  - From: W Spector
- Re: Adding UNION/MAP -- Feedback and tips pls!
  - From: N.M. Maclaren
- Re: Adding UNION/MAP -- Feedback and tips pls!
  - From: Paul Richard Thomas
- Re: Adding UNION/MAP -- Feedback and tips pls!
  - From: Janus Weil
- Re: Adding UNION/MAP -- Feedback and tips pls!
  - From: N.M. Maclaren
- Re: Adding UNION/MAP -- Feedback and tips pls!
  - From: Russell Brennan
- Re: Adding UNION/MAP -- Feedback and tips pls!
  - From: N.M. Maclaren
- Re: Adding UNION/MAP -- Feedback and tips pls!
  - From: Russell Brennan
- Re: Adding UNION/MAP -- Feedback and tips pls!
  - From: N.M. Maclaren
- Re: Adding UNION/MAP -- Feedback and tips pls!
  - From: Thomas Koenig
- Re: Adding UNION/MAP -- Feedback and tips pls!
  - From: Andrew Pinski

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]