From: Richard Stallman <rms@gnu.org>
To: mrs@wrs.com
Cc: gcc@gcc.gnu.org, jbuck@synopsys.COM
Subject: Re: type based aliasing again
Date: Thu, 30 Sep 1999 18:02:00 -0000 [thread overview]
Message-ID: <199909100634.CAA01815@psilocin.gnu.org> (raw)
Message-ID: <19990930180200.QZQ4Gw_ttgdRyip60ckVUbqEA_ZeuwCuNKicNx9PYfI@z> (raw)
In-Reply-To: <199909090211.TAA03202@kankakee.wrs.com>
My comment is similar to Mark's comment. Documentation, what can we
document as working?
We should not even try to document that these cases work.
Documentation is what we do when we add a feature.
I am not proposing this as a feature, just as a way to avoid evitable
trouble for users. We should not even try to document a class of
cases that are "supposed" to work, because I'm not saying these
are "supposed" to work. We should just let them work.
Anway, more questions from me than answers... Off hand though, if we
can make the compiler generate `right' code in more cases, even if the
users code is wrong, I think we should probably do it.
In C, we cannot divide all user code into "right" and "wrong" in this
kind of simple way, and certainly not based on the ISO standard. That
standard is just the decisions of a certain committee (which I was a
member of) about what cases conforming compilers should commit to
support. We must not let ourselves start thinking that C code is
"wrong", just because it is not conforming ISO C code.
C programs use many cases that are not conforming, but do work. This
will be true for as long as C is used, because changing it would
require major changes in the C language.
From time to time, there is a real *need* to make some of these cases
stop working, for the sake of some benefit that users want. When this
happens, we should do it; the user community will accept it, because
they will see that it is being done for their sake. Some will
grumble, but the users who appreciate the benefits will convince them.
But when there is no *need* to break these cases, when we can keep
them working fairly easily, we should keep them working. If we break
them unnecessarily, we invite the legitimate anger of the users.
next prev parent reply other threads:[~1999-09-30 18:02 UTC|newest]
Thread overview: 408+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-09-08 19:13 Mike Stump
1999-09-08 19:31 ` Joe Buck
1999-09-30 18:02 ` Joe Buck
1999-09-09 7:12 ` Marc Espie
1999-09-09 20:35 ` Jeffrey A Law
1999-09-10 12:29 ` Sudish Joseph
1999-09-30 18:02 ` Sudish Joseph
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Marc Espie
1999-09-09 23:25 ` Richard Stallman [this message]
1999-09-08 18:11 ` Joe Buck
1999-09-08 18:43 ` Mark Mitchell
1999-09-08 19:25 ` Joe Buck
1999-09-08 19:51 ` David Edelsohn
1999-09-30 18:02 ` David Edelsohn
1999-09-30 18:02 ` Joe Buck
1999-09-08 19:44 ` Joe Buck
1999-09-08 20:26 ` Mark Mitchell
1999-09-08 20:43 ` Joe Buck
1999-09-08 21:45 ` Mark Mitchell
1999-09-08 22:04 ` Joe Buck
1999-09-08 22:25 ` Mark Mitchell
1999-09-30 18:02 ` Mark Mitchell
1999-09-09 2:08 ` Jeffrey A Law
1999-09-09 10:51 ` Joe Buck
1999-09-09 16:51 ` John Vickers
1999-09-09 17:04 ` Joe Buck
1999-09-09 17:12 ` John Vickers
1999-09-30 18:02 ` John Vickers
1999-09-30 18:02 ` Joe Buck
1999-09-30 18:02 ` John Vickers
1999-09-15 2:07 ` Jeffrey A Law
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Joe Buck
1999-09-09 23:26 ` Richard Stallman
1999-09-09 23:38 ` Jeffrey A Law
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Richard Stallman
1999-09-09 23:26 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Jeffrey A Law
1999-09-09 23:25 ` Richard Stallman
1999-09-10 0:06 ` Mark Mitchell
1999-09-10 0:13 ` Joe Buck
1999-09-30 18:02 ` Joe Buck
1999-09-11 0:17 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Mark Mitchell
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Joe Buck
1999-09-08 23:20 ` Richard Henderson
1999-09-08 23:41 ` Mark Mitchell
1999-09-08 23:44 ` Richard Henderson
1999-09-08 23:51 ` Mark Mitchell
1999-09-30 18:02 ` Mark Mitchell
1999-09-09 2:45 ` Jeffrey A Law
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Richard Henderson
1999-09-30 18:02 ` Mark Mitchell
1999-09-30 18:02 ` Richard Henderson
1999-09-30 18:02 ` Mark Mitchell
1999-09-30 18:02 ` Joe Buck
1999-09-08 21:33 ` Joe Buck
1999-09-08 21:56 ` Mark Mitchell
1999-09-30 18:02 ` Mark Mitchell
1999-09-09 1:38 ` Martin v. Loewis
1999-09-30 18:02 ` Martin v. Loewis
1999-09-09 23:25 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Joe Buck
1999-09-09 2:20 ` Jeffrey A Law
1999-09-09 7:58 ` craig
1999-09-09 10:36 ` Joe Buck
1999-09-09 10:55 ` Mark Mitchell
1999-09-11 0:15 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Mark Mitchell
1999-09-09 11:51 ` craig
1999-09-09 12:45 ` Joe Buck
1999-09-30 18:02 ` Joe Buck
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Joe Buck
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Jeffrey A Law
1999-09-09 23:26 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Mark Mitchell
1999-09-30 18:02 ` Joe Buck
1999-09-09 23:25 ` Richard Stallman
1999-09-10 0:03 ` Mark Mitchell
1999-09-10 0:23 ` Joe Buck
1999-09-11 0:17 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Joe Buck
1999-09-11 0:17 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Mark Mitchell
1999-09-10 14:29 ` Marc Lehmann
1999-09-30 18:02 ` Marc Lehmann
1999-09-15 2:05 ` Jeffrey A Law
1999-09-15 7:55 ` Nick Ing-Simmons
1999-09-30 18:02 ` Nick Ing-Simmons
1999-09-15 23:14 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Mark Mitchell
1999-09-08 20:44 ` Joe Buck
1999-09-30 18:02 ` Joe Buck
1999-09-14 3:04 ` Alexandre Oliva
1999-09-14 5:34 ` Bernd Schmidt
1999-09-14 5:45 ` Alexandre Oliva
1999-09-14 5:52 ` Bernd Schmidt
1999-09-30 18:02 ` Bernd Schmidt
1999-09-21 1:16 ` Rask Ingemann Lambertsen
1999-09-21 2:02 ` Jamie Lokier
1999-09-30 18:02 ` Jamie Lokier
1999-09-30 18:02 ` Rask Ingemann Lambertsen
1999-09-30 18:02 ` Alexandre Oliva
1999-09-14 9:31 ` Andi Kleen
1999-09-30 18:02 ` Andi Kleen
1999-09-30 18:02 ` Bernd Schmidt
1999-09-14 22:22 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Alexandre Oliva
1999-09-30 18:02 ` Joe Buck
1999-09-10 0:11 ` Joe Buck
1999-09-10 8:43 ` craig
1999-09-10 18:25 ` Jonathan Larmour
1999-09-11 3:50 ` craig
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Jonathan Larmour
1999-09-11 0:15 ` Richard Stallman
1999-09-11 3:51 ` craig
1999-09-12 0:51 ` Richard Stallman
1999-09-12 8:54 ` craig
1999-09-13 0:47 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` craig
1999-09-11 0:14 ` Richard Stallman
1999-09-11 15:20 ` Mark Mitchell
1999-09-11 18:04 ` David Edelsohn
1999-09-11 18:20 ` Mark Mitchell
1999-09-11 23:40 ` Sudish Joseph
1999-09-30 18:02 ` Sudish Joseph
1999-09-12 8:16 ` Robert Lipe
1999-09-30 18:02 ` Robert Lipe
1999-09-30 18:02 ` Mark Mitchell
1999-09-13 0:47 ` Richard Stallman
1999-09-15 2:06 ` Jeffrey A Law
1999-09-15 8:02 ` Nick Ing-Simmons
1999-09-15 9:20 ` Jeffrey A Law
1999-09-15 9:31 ` David Edelsohn
1999-09-15 10:02 ` craig
1999-09-16 23:13 ` Richard Stallman
1999-09-17 1:51 ` craig
1999-09-17 22:16 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` David Edelsohn
1999-09-15 9:56 ` Nick Ing-Simmons
1999-09-15 10:08 ` craig
1999-09-15 10:48 ` Nick Ing-Simmons
1999-09-15 14:32 ` craig
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Nick Ing-Simmons
1999-09-16 10:54 ` Andi Kleen
1999-09-16 12:08 ` Joern Rennecke
1999-09-16 12:18 ` Mark Mitchell
1999-09-17 7:07 ` __typealias qualifier (was Re: type based aliasing again) patl
1999-09-17 8:32 ` Mark Mitchell
1999-09-30 18:02 ` Mark Mitchell
1999-09-30 18:02 ` Patrick J. LoPresti
1999-09-30 18:02 ` type based aliasing again Mark Mitchell
1999-09-30 18:02 ` Joern Rennecke
1999-09-16 14:29 ` craig
1999-09-16 22:19 ` Andi Kleen
1999-09-30 18:02 ` Andi Kleen
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Andi Kleen
1999-09-16 23:13 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Nick Ing-Simmons
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Nick Ing-Simmons
1999-09-15 23:14 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` David Edelsohn
1999-09-12 9:45 ` Jonathan Larmour
1999-09-30 18:02 ` Jonathan Larmour
1999-09-13 0:47 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-13 4:05 ` Richard Earnshaw
1999-09-15 2:05 ` Jeffrey A Law
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Richard Earnshaw
1999-09-30 18:02 ` Mark Mitchell
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Joe Buck
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Mike Stump
1999-09-09 14:26 Mike Stump
1999-09-09 14:38 ` Mark Mitchell
1999-09-11 0:16 ` Richard Stallman
1999-09-15 2:07 ` Jeffrey A Law
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Mark Mitchell
1999-09-30 18:02 ` Mike Stump
1999-09-09 15:40 Claus Fischer
1999-09-09 15:57 ` David Starner
1999-09-09 16:24 ` Claus Fischer
1999-09-09 16:55 ` Joe Buck
1999-09-09 17:31 ` Claus Fischer
1999-09-30 18:02 ` Claus Fischer
1999-09-30 18:02 ` Joe Buck
1999-09-10 8:42 ` craig
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Claus Fischer
1999-09-30 18:02 ` David Starner
1999-09-09 16:37 ` Jeffrey A Law
1999-09-09 17:15 ` Claus Fischer
1999-09-30 18:02 ` Claus Fischer
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Claus Fischer
1999-09-09 21:54 Alex Rosenberg
1999-09-30 18:02 ` Alex Rosenberg
1999-09-10 8:43 craig
1999-09-12 0:49 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` craig
1999-09-11 18:21 Phil Edwards
1999-09-30 18:02 ` Phil Edwards
1999-09-11 21:48 N8TM
1999-09-30 18:02 ` N8TM
[not found] <9377.936981585@upchuck.cygnus.com>
1999-09-12 0:52 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-12 11:20 Josh Stern
1999-09-30 18:02 ` Josh Stern
1999-09-13 10:55 R. Kelley Cook
1999-09-13 13:22 ` craig
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` R. Kelley Cook
1999-09-13 16:34 Mike Stump
1999-09-14 22:20 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Mike Stump
1999-09-13 21:45 N8TM
1999-09-14 4:01 ` Marc Espie
1999-09-14 9:56 ` David Edelsohn
1999-09-14 10:10 ` Richard Earnshaw
1999-09-14 10:31 ` Nick Ing-Simmons
1999-09-14 10:52 ` David Edelsohn
1999-09-14 11:11 ` craig
1999-09-14 14:44 ` David Edelsohn
1999-09-30 18:02 ` David Edelsohn
1999-09-14 15:06 ` David Edelsohn
1999-09-14 17:35 ` Marc Lehmann
1999-09-30 18:02 ` Marc Lehmann
1999-09-14 23:41 ` craig
1999-09-15 8:28 ` Marc Lehmann
1999-09-30 18:02 ` Marc Lehmann
1999-09-15 9:19 ` David Edelsohn
1999-09-15 9:59 ` Nick Ing-Simmons
1999-09-15 15:33 ` David Edelsohn
1999-09-30 18:02 ` David Edelsohn
1999-09-30 18:02 ` Nick Ing-Simmons
1999-09-15 10:01 ` craig
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` David Edelsohn
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` David Edelsohn
1999-09-30 18:02 ` craig
1999-09-14 11:58 ` Gerald Pfeifer
1999-09-30 18:02 ` Gerald Pfeifer
1999-09-30 18:02 ` David Edelsohn
1999-09-14 11:01 ` craig
1999-09-14 11:14 ` craig
1999-09-30 18:02 ` craig
1999-09-14 11:39 ` Mark Mitchell
1999-09-14 14:48 ` Toon Moene
1999-09-14 15:00 ` David Edelsohn
1999-09-14 16:01 ` Toon Moene
1999-09-14 16:15 ` David Edelsohn
1999-09-14 16:43 ` Mark Mitchell
1999-09-30 18:02 ` Mark Mitchell
1999-09-14 17:39 ` Marc Lehmann
1999-09-30 18:02 ` Marc Lehmann
1999-09-30 18:02 ` David Edelsohn
1999-09-14 16:19 ` dvv
1999-09-14 17:38 ` Michael Meissner
1999-09-30 18:02 ` Michael Meissner
1999-09-30 18:02 ` Dima Volodin
1999-09-30 18:02 ` Toon Moene
1999-09-30 18:02 ` David Edelsohn
1999-09-14 15:08 ` Mark Mitchell
1999-09-30 18:02 ` Mark Mitchell
1999-09-30 18:02 ` Toon Moene
1999-09-30 18:02 ` Mark Mitchell
1999-09-30 18:02 ` craig
1999-09-14 23:46 ` Geoff Keating
1999-09-15 7:47 ` Nick Ing-Simmons
1999-09-30 18:02 ` Nick Ing-Simmons
1999-09-30 18:02 ` Geoff Keating
1999-09-30 18:02 ` Nick Ing-Simmons
1999-09-30 18:02 ` Richard Earnshaw
1999-09-14 17:22 ` Marc Lehmann
1999-09-30 18:02 ` Marc Lehmann
1999-09-30 18:02 ` David Edelsohn
1999-09-14 17:23 ` Marc Lehmann
1999-09-15 1:59 ` Marc Espie
1999-09-15 8:28 ` Marc Lehmann
1999-09-30 18:02 ` Marc Lehmann
1999-09-30 18:02 ` Marc Espie
1999-09-30 18:02 ` Marc Lehmann
1999-09-15 2:01 ` Jeffrey A Law
1999-09-30 18:02 ` Jeffrey A Law
1999-09-30 18:02 ` Marc Espie
1999-09-30 18:02 ` N8TM
1999-09-14 6:46 Marcel Cox
1999-09-14 6:50 ` Bernd Schmidt
1999-09-14 7:14 ` Marcel Cox
1999-09-14 8:45 ` Jamie Lokier
1999-09-30 18:02 ` Jamie Lokier
1999-09-30 18:02 ` Marcel Cox
1999-09-30 18:02 ` Bernd Schmidt
1999-09-30 18:02 ` Marcel Cox
1999-09-15 7:02 David Ronis
1999-09-30 18:02 ` David Ronis
1999-09-15 8:27 Kaveh R. Ghazi
1999-09-15 8:57 ` Nathan Sidwell
1999-09-30 18:02 ` Nathan Sidwell
1999-09-30 18:02 ` Kaveh R. Ghazi
1999-09-15 11:42 Michael J. Bedy
1999-09-15 14:32 ` craig
1999-09-16 23:14 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Michael J. Bedy
1999-09-15 21:47 Florin Mateoc
1999-09-16 2:18 ` craig
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` Florin Mateoc
[not found] <Pine.SO4.4.05.9909160153420.23533-100000@tamarack.cs.mtu.edu>
1999-09-16 2:19 ` craig
1999-09-30 18:02 ` craig
1999-09-16 6:12 Artem Hodyush
1999-09-16 23:15 ` Richard Stallman
1999-09-16 23:38 ` Gabriel Dos_Reis
1999-09-17 22:16 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Gabriel Dos_Reis
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Artem Hodyush
[not found] <199909161750.LAA12073@basho.fc.hp.com>
1999-09-16 14:29 ` craig
1999-09-20 15:17 ` John W. Stevens
1999-09-30 18:02 ` John W. Stevens
1999-09-30 18:02 ` craig
1999-09-17 9:02 Harvey J. Stein
1999-09-30 18:02 ` Harvey J. Stein
1999-09-18 2:51 Ross Morgan-Linial
[not found] ` <19990918151905.F1650@cerebro.laendle>
1999-09-18 22:18 ` Ross Morgan-Linial
1999-09-30 18:02 ` Ross Morgan-Linial
1999-09-30 18:02 ` Ross Morgan-Linial
1999-09-18 3:25 Artem Hodyush
1999-09-18 11:29 ` Russ Allbery
1999-09-20 5:54 ` Joern Rennecke
1999-09-30 18:02 ` Joern Rennecke
1999-09-30 18:02 ` Russ Allbery
1999-09-19 13:54 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-21 8:50 ` Harvey J. Stein
1999-09-30 18:02 ` Harvey J. Stein
1999-09-30 18:02 ` Artem Hodyush
1999-09-18 7:30 Stephen L Moshier
1999-09-30 18:02 ` Stephen L Moshier
1999-09-18 8:33 N8TM
1999-09-30 18:02 ` N8TM
1999-09-21 8:48 Harvey J. Stein
1999-09-22 12:15 ` Richard Stallman
1999-09-22 13:08 ` Harvey J. Stein
1999-09-24 23:37 ` Richard Stallman
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Harvey J. Stein
1999-09-30 18:02 ` Richard Stallman
1999-09-30 18:02 ` Harvey J. Stein
[not found] <19990921182843.25292.qmail@deer>
1999-09-21 15:47 ` John W. Stevens
1999-09-21 16:15 ` craig
1999-09-21 20:37 ` David Edelsohn
1999-09-30 18:02 ` David Edelsohn
1999-09-23 9:06 ` John W. Stevens
1999-09-23 11:06 ` craig
1999-09-30 18:02 ` craig
1999-09-30 18:02 ` John W. Stevens
1999-09-30 18:02 ` craig
1999-09-27 6:56 ` Rask Ingemann Lambertsen
1999-09-27 8:32 ` Joe Buck
1999-09-30 18:02 ` Joe Buck
1999-09-30 18:02 ` Rask Ingemann Lambertsen
1999-09-30 18:02 ` John W. Stevens
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