Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c > #20514

Re: List of undefined behaviour and other sneeky bugs

Show all headers | View raw

Tim Rentsch <txr@alumni.caltech.edu> writes:

> Ben Pfaff <blp@cs.stanford.edu> writes:
>
>> John Reye <jononanon@googlemail.com> writes:
>>
>>> On May 3, 11:05 pm, Ben Pfaff <b...@cs.stanford.edu> wrote:
>>> So if you use a particular union access member... for a particular
>>> union in memory, then you should always access that particular union-
>>> variable, with the same member?
>>>
>>> Is that the only intended use?
>>
>> I believe that is the intention.  I couldn't find relevant text
>> in the Rationale.
>
> If you read the Defect Report (sorry, I don't know the
> number offhand) that prompted the famous "type punning"
> footnote, I think you'll find that the type punning use
> cases were expected and intended all along, eg, even in
> C89/C90.  I presume they were important to make defined
> because a significant amount of pre-ANSI C code relied
> on them working.

Either I didn't know about that defect report or I'd forgotten
it.  Thanks for the correction.

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

List of undefined behaviour and other sneeky bugs John Reye <jononanon@googlemail.com> - 2012-05-03 10:04 -0700
  Re: List of undefined behaviour and other sneeky bugs jt@toerring.de (Jens Thoms Toerring) - 2012-05-03 17:38 +0000
    Re: List of undefined behaviour and other sneeky bugs John Reye <jononanon@googlemail.com> - 2012-05-03 10:50 -0700
      Re: List of undefined behaviour and other sneeky bugs Ben Pfaff <blp@cs.stanford.edu> - 2012-05-03 11:09 -0700
        Re: List of undefined behaviour and other sneeky bugs John Reye <jononanon@googlemail.com> - 2012-05-03 11:18 -0700
          Re: List of undefined behaviour and other sneeky bugs Ben Pfaff <blp@cs.stanford.edu> - 2012-05-03 11:24 -0700
            Re: List of undefined behaviour and other sneeky bugs John Reye <jononanon@googlemail.com> - 2012-05-03 11:35 -0700
              Re: List of undefined behaviour and other sneeky bugs John Reye <jononanon@googlemail.com> - 2012-05-03 11:56 -0700
              Re: List of undefined behaviour and other sneeky bugs Ben Pfaff <blp@cs.stanford.edu> - 2012-05-03 12:16 -0700
                Re: List of undefined behaviour and other sneeky bugs John Reye <jononanon@googlemail.com> - 2012-05-03 12:20 -0700
                Re: List of undefined behaviour and other sneeky bugs Keith Thompson <kst-u@mib.org> - 2012-05-03 12:39 -0700
          Re: List of undefined behaviour and other sneeky bugs Tim Rentsch <txr@alumni.caltech.edu> - 2012-05-07 17:51 -0700
            Re: List of undefined behaviour and other sneeky bugs "Joachim Schmitz" <nospam.jojo@schmitz-digital.de> - 2012-05-08 09:10 +0200
              Re: List of undefined behaviour and other sneeky bugs Tim Rentsch <txr@alumni.caltech.edu> - 2012-05-08 05:31 -0700
      Re: List of undefined behaviour and other sneeky bugs jt@toerring.de (Jens Thoms Toerring) - 2012-05-03 18:11 +0000
        Re: List of undefined behaviour and other sneeky bugs John Reye <jononanon@googlemail.com> - 2012-05-03 11:29 -0700
          Re: List of undefined behaviour and other sneeky bugs jt@toerring.de (Jens Thoms Toerring) - 2012-05-03 19:19 +0000
            Re: List of undefined behaviour and other sneeky bugs John Reye <jononanon@googlemail.com> - 2012-05-03 13:31 -0700
              Re: List of undefined behaviour and other sneeky bugs John Reye <jononanon@googlemail.com> - 2012-05-03 14:18 -0700
                Re: List of undefined behaviour and other sneeky bugs John Reye <jononanon@googlemail.com> - 2012-05-03 15:20 -0700
            Re: List of undefined behaviour and other sneeky bugs Nobody <nobody@nowhere.com> - 2012-05-04 01:47 +0100
      Re: List of undefined behaviour and other sneeky bugs Tim Rentsch <txr@alumni.caltech.edu> - 2012-05-07 17:47 -0700
    Re: List of undefined behaviour and other sneeky bugs Tim Rentsch <txr@alumni.caltech.edu> - 2012-05-07 17:45 -0700
      Re: List of undefined behaviour and other sneeky bugs nick_keighley_nospam@hotmail.com - 2012-05-08 00:43 -0700
        Re: List of undefined behaviour and other sneeky bugs Tim Rentsch <txr@alumni.caltech.edu> - 2012-05-08 06:17 -0700
  Re: List of undefined behaviour and other sneeky bugs Keith Thompson <kst-u@mib.org> - 2012-05-03 12:46 -0700
    Re: List of undefined behaviour and other sneeky bugs John Reye <jononanon@googlemail.com> - 2012-05-03 13:35 -0700
      Re: List of undefined behaviour and other sneeky bugs Ben Pfaff <blp@cs.stanford.edu> - 2012-05-03 14:05 -0700
        Re: List of undefined behaviour and other sneeky bugs John Reye <jononanon@googlemail.com> - 2012-05-03 14:11 -0700
          Re: List of undefined behaviour and other sneeky bugs Ben Pfaff <blp@cs.stanford.edu> - 2012-05-03 15:02 -0700
            Re: List of undefined behaviour and other sneeky bugs Tim Rentsch <txr@alumni.caltech.edu> - 2012-05-07 18:10 -0700
              Re: List of undefined behaviour and other sneeky bugs nick_keighley_nospam@hotmail.com - 2012-05-08 00:49 -0700
                Re: List of undefined behaviour and other sneeky bugs James Kuyper <jameskuyper@verizon.net> - 2012-05-08 06:37 -0400
                Re: List of undefined behaviour and other sneeky bugs Tim Rentsch <txr@alumni.caltech.edu> - 2012-05-08 07:49 -0700
                Re: List of undefined behaviour and other sneeky bugs Tim Rentsch <txr@alumni.caltech.edu> - 2012-05-08 07:25 -0700
              Re: List of undefined behaviour and other sneeky bugs Ben Pfaff <blp@cs.stanford.edu> - 2012-05-08 09:46 -0700
          Re: List of undefined behaviour and other sneeky bugs James Kuyper <jameskuyper@verizon.net> - 2012-05-03 18:24 -0400
            Re: List of undefined behaviour and other sneeky bugs Tim Rentsch <txr@alumni.caltech.edu> - 2012-05-07 18:24 -0700
      Re: List of undefined behaviour and other sneeky bugs jt@toerring.de (Jens Thoms Toerring) - 2012-05-03 21:17 +0000
        Re: List of undefined behaviour and other sneeky bugs Tim Rentsch <txr@alumni.caltech.edu> - 2012-05-07 18:28 -0700
      Re: List of undefined behaviour and other sneeky bugs Keith Thompson <kst-u@mib.org> - 2012-05-03 15:54 -0700
      Re: List of undefined behaviour and other sneeky bugs Old Wolf <oldwolf@inspire.net.nz> - 2012-05-06 22:32 -0700
        Re: List of undefined behaviour and other sneeky bugs Jens Gustedt <jens.gustedt@loria.fr> - 2012-05-07 08:26 +0200
        Re: List of undefined behaviour and other sneeky bugs Tim Rentsch <txr@alumni.caltech.edu> - 2012-05-07 18:31 -0700
    Re: List of undefined behaviour and other sneeky bugs Jens Gustedt <jens.gustedt@loria.fr> - 2012-05-03 23:18 +0200
      Re: List of undefined behaviour and other sneeky bugs Keith Thompson <kst-u@mib.org> - 2012-05-03 15:58 -0700
  Re: List of undefined behaviour and other sneeky bugs pete <pfiland@mindspring.com> - 2012-05-04 00:25 -0400
    Re: List of undefined behaviour and other sneeky bugs John Reye <jononanon@googlemail.com> - 2012-05-03 22:28 -0700
      Re: List of undefined behaviour and other sneeky bugs James Kuyper <jameskuyper@verizon.net> - 2012-05-04 07:33 -0400
        Re: List of undefined behaviour and other sneeky bugs Tim Rentsch <txr@alumni.caltech.edu> - 2012-05-07 19:20 -0700
      Re: List of undefined behaviour and other sneeky bugs Tim Rentsch <txr@alumni.caltech.edu> - 2012-05-07 18:50 -0700
    Re: List of undefined behaviour and other sneeky bugs Tim Rentsch <txr@alumni.caltech.edu> - 2012-05-07 18:42 -0700
      Re: List of undefined behaviour and other sneeky bugs pete <pfiland@mindspring.com> - 2012-05-07 23:45 -0400
        Re: List of undefined behaviour and other sneeky bugs Tim Rentsch <txr@alumni.caltech.edu> - 2012-05-07 23:01 -0700
          Re: List of undefined behaviour and other sneeky bugs pete <pfiland@mindspring.com> - 2012-05-08 06:28 -0400
            Re: List of undefined behaviour and other sneeky bugs pete <pfiland@mindspring.com> - 2012-05-08 06:37 -0400
              Re: List of undefined behaviour and other sneeky bugs Tim Rentsch <txr@alumni.caltech.edu> - 2012-05-08 06:19 -0700

csiph-web