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| From | James Kuyper <jameskuyper@verizon.net> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Objective C |
| Date | 2015-11-27 12:38 -0500 |
| Organization | Self |
| Message-ID | <56589500.3090306@verizon.net> (permalink) |
| References | (11 earlier) <m4k05bdossoe7criehdedlhgfpv1lml9rp@4ax.com> <ln7flb8u7t.fsf@kst-u.example.com> <n2qvdu$gqi$1@dont-email.me> <lnegfi6gyc.fsf@kst-u.example.com> <5658851e.13360281@news.xs4all.nl> |
On 11/27/2015 11:42 AM, Richard Bos wrote: ... > It sounds too much like saying that it's not dangerous to cross the > highway on foot. What's dangerous is getting hit by a truck! If only you > can prove that there will be no truck coming, you'll be just fine. Well, > yes, but I'd still prefer children to be taught not to run across the > highway, or any other road. > Similarly, it's true that accessing a different union member does not > _in itself_ have undefined behaviour. It's also true that there are > cases (including common ones) where you can prove that the result is > also defined. Nevertheless, it's still true that the _general_ result of > re-interpreting bytes does have undefined behaviour unless explicit > proof to the contrary in that particular case exists. > > In other words: accessing different union members does not have > undefined behaviour, but the general case does _cause_ undefined > behaviour further down the line. Exceptions exist and may be many, but > (except for unsigned char) are themselves unportable. Virtually every case where someone deliberately writes such code corresponds to a legitimate exception. No one writes such code unless they have some expectations about what should happen, and those expectations don't come out of nowhere: there are usually systems where those expectations are valid (though it's not at all uncommon for the writer of code to think that such systems are more nearly universal than they actually are). That's what I meant by saying it "corresponds to a legitimate exception" rather than "is a legitimate exception". If the writer expected the code to work in a wider domain than is actually justified, it's not a legitimate exception. However, if you restrict the use of such code to those platforms where those expectations are valid, the implementation-defined representations of the two types combine with 6.5.2.3p3 to fully justify relying upon those expectations in that restricted domain.
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Objective C Alla _ <modelling.data@gmail.com> - 2015-11-10 09:10 -0800
Re: Objective C "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-10 09:16 -0800
Re: Objective C Richard Heathfield <rjh@cpax.org.uk> - 2015-11-10 17:17 +0000
Re: Objective C Keith Thompson <kst-u@mib.org> - 2015-11-10 09:32 -0800
Re: Objective C Mark Storkamp <mstorkamp@yahoo.com> - 2015-11-10 11:38 -0600
Re: Objective C James Kuyper <jameskuyper@verizon.net> - 2015-11-10 12:36 -0500
Re: Objective C Alla _ <modelling.data@gmail.com> - 2015-11-10 11:15 -0800
Re: Objective C Richard Heathfield <rjh@cpax.org.uk> - 2015-11-10 21:51 +0000
Re: Objective C Alla _ <modelling.data@gmail.com> - 2015-11-10 23:13 -0800
Re: Objective C supercat@casperkitty.com - 2015-11-13 16:01 -0800
Re: Objective C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-14 01:07 +0000
Re: Objective C supercat@casperkitty.com - 2015-11-14 06:26 -0800
Re: Objective C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-14 22:22 +0000
Re: Objective C supercat@casperkitty.com - 2015-11-14 15:46 -0800
Re: Objective C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-15 01:47 +0000
Re: Objective C BartC <bc@freeuk.com> - 2015-11-15 10:43 +0000
Re: Objective C supercat@casperkitty.com - 2015-11-15 13:19 -0800
Re: Objective C Keith Thompson <kst-u@mib.org> - 2015-11-14 15:43 -0800
Re: Objective C David Brown <david.brown@hesbynett.no> - 2015-11-15 23:50 +0100
Re: Objective C gazelle@shell.xmission.com (Kenny McCormack) - 2015-11-16 00:05 +0000
Re: Objective C supercat@casperkitty.com - 2015-11-15 19:10 -0800
Re: Objective C David Brown <david.brown@hesbynett.no> - 2015-11-16 09:11 +0100
Re: Objective C supercat@casperkitty.com - 2015-11-16 11:57 -0800
Re: Objective C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-16 20:38 +0000
Re: Objective C supercat@casperkitty.com - 2015-11-16 13:20 -0800
Re: Objective C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-16 22:28 +0000
Re: Objective C supercat@casperkitty.com - 2015-11-16 15:33 -0800
Re: Objective C supercat@casperkitty.com - 2015-11-16 15:56 -0800
Re: Objective C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-17 01:43 +0000
Re: Objective C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-17 01:21 +0000
Re: Objective C supercat@casperkitty.com - 2015-11-16 18:11 -0800
Re: Objective C supercat@casperkitty.com - 2015-11-16 20:12 -0800
Re: Objective C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-19 00:59 +0000
Re: Objective C supercat@casperkitty.com - 2015-11-18 22:46 -0800
Re: Objective C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-19 14:25 +0000
Re: Objective C supercat@casperkitty.com - 2015-11-19 07:58 -0800
Re: Objective C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-19 22:13 +0000
Re: Objective C supercat@casperkitty.com - 2015-11-19 15:29 -0800
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-27 08:44 -0800
Re: Objective C glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-17 01:26 +0000
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-16 21:48 -0600
Re: Objective C supercat@casperkitty.com - 2015-11-16 20:27 -0800
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-17 13:58 -0600
Re: Objective C supercat@casperkitty.com - 2015-11-17 12:28 -0800
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-18 13:00 -0600
Re: Objective C supercat@casperkitty.com - 2015-11-18 12:31 -0800
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-18 16:43 -0600
Re: Objective C supercat@casperkitty.com - 2015-11-18 15:57 -0800
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-19 19:09 -0600
Re: Objective C supercat@casperkitty.com - 2015-11-19 19:05 -0800
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-20 15:00 -0600
Re: Objective C supercat@casperkitty.com - 2015-11-20 15:30 -0800
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-22 17:11 -0600
Re: Objective C supercat@casperkitty.com - 2015-11-22 15:53 -0800
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-23 13:51 -0600
Re: Objective C raltbos@xs4all.nl (Richard Bos) - 2015-11-24 12:00 +0000
Re: Objective C David Brown <david.brown@hesbynett.no> - 2015-11-17 10:26 +0100
Re: Objective C supercat@casperkitty.com - 2015-11-17 06:20 -0800
Re: Objective C David Brown <david.brown@hesbynett.no> - 2015-11-17 16:41 +0100
Re: Objective C supercat@casperkitty.com - 2015-11-17 12:08 -0800
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-17 16:27 -0600
Re: Objective C supercat@casperkitty.com - 2015-11-17 14:55 -0800
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-18 13:59 -0600
Re: Objective C supercat@casperkitty.com - 2015-11-18 13:06 -0800
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-24 14:24 -0600
Re: Objective C supercat@casperkitty.com - 2015-11-24 15:11 -0800
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-26 17:02 -0600
Re: Objective C supercat@casperkitty.com - 2015-11-27 07:26 -0800
Re: Objective C supercat@casperkitty.com - 2015-11-18 21:56 -0800
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-22 02:17 -0600
Re: Objective C supercat@casperkitty.com - 2015-11-22 07:16 -0800
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-26 17:11 -0600
Re: Objective C Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-11-22 19:09 +0000
Re: Objective C Robert Wessel <robertwessel2@yahoo.com> - 2015-11-17 23:28 -0600
Re: Objective C David Brown <david.brown@hesbynett.no> - 2015-11-18 15:33 +0100
Re: Objective C supercat@casperkitty.com - 2015-11-18 23:06 -0800
Re: Objective C David Brown <david.brown@hesbynett.no> - 2015-11-19 09:12 +0100
Re: Objective C supercat@casperkitty.com - 2015-11-19 09:25 -0800
Re: Objective C David Brown <david.brown@hesbynett.no> - 2015-11-19 21:06 +0100
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-20 13:49 -0800
Re: Objective C Robert Wessel <robertwessel2@yahoo.com> - 2015-11-21 05:01 -0600
Re: Objective C Robert Wessel <robertwessel2@yahoo.com> - 2015-11-21 05:09 -0600
Re: Objective C Keith Thompson <kst-u@mib.org> - 2015-11-21 03:31 -0800
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-21 17:43 -0600
Re: Objective C Keith Thompson <kst-u@mib.org> - 2015-11-21 16:00 -0800
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-22 01:12 -0600
Re: Objective C raltbos@xs4all.nl (Richard Bos) - 2015-11-27 16:42 +0000
Re: Objective C James Kuyper <jameskuyper@verizon.net> - 2015-11-27 12:38 -0500
Re: Objective C supercat@casperkitty.com - 2015-11-27 11:09 -0800
Re: Objective C James Kuyper <jameskuyper@verizon.net> - 2015-11-21 19:06 -0500
Re: Objective C supercat@casperkitty.com - 2015-11-21 17:00 -0800
Re: Objective C glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-22 14:44 +0000
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-22 01:55 -0600
Re: Objective C Keith Thompson <kst-u@mib.org> - 2015-11-22 00:03 -0800
Re: Objective C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-22 10:18 +0000
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-23 03:21 -0800
Re: Objective C James Kuyper <jameskuyper@verizon.net> - 2015-11-22 10:53 -0500
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-22 20:28 -0600
Re: Objective C supercat@casperkitty.com - 2015-11-22 18:52 -0800
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-23 11:58 -0600
Re: Objective C supercat@casperkitty.com - 2015-11-23 15:24 -0800
Re: Objective C James Kuyper <jameskuyper@verizon.net> - 2015-11-23 09:46 -0500
Re: Objective C Keith Thompson <kst-u@mib.org> - 2015-11-23 08:13 -0800
Re: Objective C James Kuyper <jameskuyper@verizon.net> - 2015-11-23 12:04 -0500
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-23 11:52 -0600
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-23 16:05 -0800
Re: Objective C supercat@casperkitty.com - 2015-11-24 09:09 -0800
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-12-08 08:48 -0800
Re: Objective C Keith Thompson <kst-u@mib.org> - 2015-12-08 10:40 -0800
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-12-09 12:34 -0800
Re: Objective C supercat@casperkitty.com - 2015-12-08 10:50 -0800
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-12-09 12:42 -0800
Re: Objective C supercat@casperkitty.com - 2015-12-09 13:38 -0800
Re: Objective C raltbos@xs4all.nl (Richard Bos) - 2015-12-10 19:54 +0000
Re: Objective C David Thompson <dave.thompson2@verizon.net> - 2015-12-06 08:02 -0500
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-22 14:36 -0800
Re: Objective C Robert Wessel <robertwessel2@yahoo.com> - 2015-11-23 00:41 -0600
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-23 07:39 -0800
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-22 14:23 -0800
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-17 10:24 -0800
Re: Objective C David Brown <david.brown@hesbynett.no> - 2015-11-18 15:40 +0100
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-20 16:02 -0800
Re: Objective C David Brown <david.brown@hesbynett.no> - 2015-11-21 15:53 +0100
Re: Objective C supercat@casperkitty.com - 2015-11-21 08:58 -0800
Re: Objective C David Brown <david.brown@hesbynett.no> - 2015-11-22 22:14 +0100
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-23 03:39 -0800
Re: Objective C raltbos@xs4all.nl (Richard Bos) - 2015-11-23 13:24 +0000
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-26 09:39 -0800
Re: Objective C Robert Wessel <robertwessel2@yahoo.com> - 2015-11-26 13:16 -0600
Re: Objective C supercat@casperkitty.com - 2015-11-26 12:25 -0800
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-27 14:34 -0800
Re: Objective C Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-26 12:39 -0800
Re: Objective C raltbos@xs4all.nl (Richard Bos) - 2015-11-27 16:43 +0000
Re: Objective C Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-27 09:29 -0800
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-27 14:18 -0800
Re: Objective C glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-23 22:35 +0000
Re: Objective C James Kuyper <jameskuyper@verizon.net> - 2015-11-23 17:40 -0500
Re: Objective C glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-24 05:35 +0000
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-25 12:15 -0800
Re: Objective C glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-25 22:49 +0000
Re: Objective C raltbos@xs4all.nl (Richard Bos) - 2015-11-27 16:44 +0000
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-27 14:03 -0800
Re: Objective C Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-11-29 09:29 +0000
Re: Objective C Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-11-22 19:01 +0000
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-23 07:31 -0800
Re: Objective C Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-23 07:43 -0800
Re: Objective C Keith Thompson <kst-u@mib.org> - 2015-11-23 08:17 -0800
Re: Objective C David Brown <david.brown@hesbynett.no> - 2015-11-23 17:34 +0100
Re: Objective C Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-11-23 22:02 +0000
Re: Objective C David Brown <david.brown@hesbynett.no> - 2015-11-24 10:12 +0100
Re: Objective C Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-27 08:39 -0800
Re: Objective C Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-11-14 18:24 +0000
Re: Objective C Keith Thompson <kst-u@mib.org> - 2015-11-14 12:23 -0800
Re: Objective C Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-14 12:36 -0800
Re: Objective C Keith Thompson <kst-u@mib.org> - 2015-11-14 13:13 -0800
Re: Objective C Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-14 14:04 -0800
Re: Objective C Keith Thompson <kst-u@mib.org> - 2015-11-14 14:15 -0800
Re: Objective C Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-14 14:29 -0800
Re: Objective C Keith Thompson <kst-u@mib.org> - 2015-11-14 15:39 -0800
Re: Objective C Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-14 16:37 -0800
Re: Objective C Ian Collins <ian-news@hotmail.com> - 2015-11-15 13:46 +1300
Re: Objective C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-15 02:06 +0000
Re: Objective C Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-15 03:25 -0800
Re: Objective C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-15 12:56 +0000
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-15 07:53 -0600
Re: Objective C Stephen Sprunk <stephen@sprunk.org> - 2015-11-15 07:19 -0600
Re: Objective C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-15 13:29 +0000
Re: Objective C Keith Thompson <kst-u@mib.org> - 2015-11-15 10:56 -0800
Re: Objective C supercat@casperkitty.com - 2015-11-15 14:35 -0800
Re: Objective C Keith Thompson <kst-u@mib.org> - 2015-11-15 16:52 -0800
Re: Objective C supercat@casperkitty.com - 2015-11-15 19:49 -0800
Re: Objective C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-16 11:02 +0000
Re: Objective C Keith Thompson <kst-u@mib.org> - 2015-11-16 10:36 -0800
Re: Objective C David Thompson <dave.thompson2@verizon.net> - 2015-12-06 08:03 -0500
Re: Objective C Melzzzzz <mel@zzzzz.com> - 2015-11-16 02:01 +0100
Re: Objective C supercat@casperkitty.com - 2015-11-15 19:34 -0800
Re: Objective C Chad <cdalten@gmail.com> - 2015-11-15 19:54 -0800
Re: Objective C raltbos@xs4all.nl (Richard Bos) - 2015-11-17 22:36 +0000
Re: Objective C supercat@casperkitty.com - 2015-11-17 15:27 -0800
Re: Objective C Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-17 21:15 -0800
Re: Objective C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-14 22:08 +0000
Re: Objective C fir <profesor.fir@gmail.com> - 2015-11-27 14:36 -0800
Re: Objective C David Brown <david.brown@hesbynett.no> - 2015-11-10 19:03 +0100
Re: Objective C Keith Thompson <kst-u@mib.org> - 2015-11-10 10:50 -0800
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