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Re: Help on this typedef

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On Saturday, May 20, 2017 at 9:47:02 AM UTC-5, james...@verizon.net wrote:
> I should answer it directly. First of all, your list of the various
> possibilities did not include the one possibility that actually applied.

I'd say #2 would seem to match the case you describe; if the Standard
were adequately clear on a subject, it should be possible to answer
any questions about its meaning merely by citing and quoting the relevant
portions; if a question that would need to be answered, cannot be answered
merely by quoting the Standard, I would regard that as indicative of a
defect which should be corrected by, at minimum, adding a footnote to
future standards that would clarify the issue.

Also, who writes the answers to DRs?  Are they voted upon by the Committee as
a whole?  There are certain places where the Standard appears to deliberately
avoid clarifying examples that are so obviously essential that the only
plausible explanations are either that the Committee was being absurdly dumb
or else no consensus could be reached as to whether they should be defined
or not.  For example, under 6.5.2.3, there should be an example where structs
containing a Common Initial Sequence are accessed via pointers of their
respective types, at places where a complete union definition containing
both structures is visible.  I personally think the language is quite clear
as saying such behavior is defined (saying CIS members may be inspected
"anywhere that a declaration of the complete type of the union is visible"
would be redundant if such inspection had to be done through lvalues of
union type, since such accesses can't possibly be made anywhere else) but
compiler writers don't follow that.

> Secondly, committee resolutions never take the form of advice for implementors
> about how to deal with the issue raised by the DR - they either express what the
> committee believes is the correct interpretation of the words as they are
> currently written (in which cases implementors who wish to conform to the
> standard should modify their implementation, if necessary, to match that
> interpretation), or they recommend that the words be changed (in which case
> implementors have the option of anticipating the correction by implementing it
> as an extension now, or waiting until the correction has been approved before
> implementing it as a conformance requirement).

There are a number places where it would make sense for 99.9% of
implementations to behave the same way, and to allow programmers to
exploit that if they don't need to support the unusual 0.1%.  The
Standard leaves such behaviors Undefined so as to avoid forbidding
implementations from doing some other sensible behavior, sometimes
even when an earlier standard defined the behavior (e.g. -1<<1).

What's really needed, but what the Standard has avoided for some (likely
political) reasons, would be an effort to recognize behaviors that are
commonplace but not universal.  Ironically, I suspect it's politically
easier to recognize a behavior that's supported by 50% of implementations
than one that's supported by 99%, since the latter would be seen as
marginalizing the 1%.

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Help on this typedef fl <rxjwg98@gmail.com> - 2017-05-10 19:12 -0700
  Re: Help on this typedef Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-05-10 21:06 -0600
  Re: Help on this typedef Keith Thompson <kst-u@mib.org> - 2017-05-10 20:11 -0700
    Re: Help on this typedef David Brown <david.brown@hesbynett.no> - 2017-05-11 10:03 +0200
      Re: Help on this typedef supercat@casperkitty.com - 2017-05-11 08:35 -0700
        Re: Help on this typedef David Brown <david.brown@hesbynett.no> - 2017-05-12 10:34 +0200
          Re: Help on this typedef joel.rees@gmail.com - 2017-05-12 06:01 -0700
          Re: Help on this typedef Keith Thompson <kst-u@mib.org> - 2017-05-12 09:38 -0700
        Re: Help on this typedef joel.rees@gmail.com - 2017-05-12 05:08 -0700
          Re: Help on this typedef Tim Rentsch <txr@alumni.caltech.edu> - 2017-05-13 14:25 -0700
            Re: Help on this typedef joel.rees@gmail.com - 2017-05-14 23:36 -0700
              Re: Help on this typedef Tim Rentsch <txr@alumni.caltech.edu> - 2017-05-15 07:23 -0700
                Re: Help on this typedef joel.rees@gmail.com - 2017-05-18 07:40 -0700
                Re: Help on this typedef Keith Thompson <kst-u@mib.org> - 2017-05-18 09:35 -0700
                Re: Help on this typedef supercat@casperkitty.com - 2017-05-18 10:59 -0700
                Re: Help on this typedef joel.rees@gmail.com - 2017-05-18 23:40 -0700
                Re: Help on this typedef jadill33@gmail.com - 2017-05-19 08:12 -0700
                Re: Help on this typedef supercat@casperkitty.com - 2017-05-19 08:41 -0700
                Re: Help on this typedef jadill33@gmail.com - 2017-05-19 09:41 -0700
                Re: Help on this typedef Keith Thompson <kst-u@mib.org> - 2017-05-19 09:34 -0700
                Re: Help on this typedef supercat@casperkitty.com - 2017-05-19 10:18 -0700
                Re: Help on this typedef Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-19 21:35 +0100
                Re: Help on this typedef supercat@casperkitty.com - 2017-05-19 14:16 -0700
                Re: Help on this typedef Ike Naar <ike@iceland.freeshell.org> - 2017-05-19 21:15 +0000
                Re: Help on this typedef Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-19 23:54 +0100
                Re: Help on this typedef Keith Thompson <kst-u@mib.org> - 2017-05-19 14:25 -0700
                Re: Help on this typedef supercat@casperkitty.com - 2017-05-19 15:18 -0700
                Re: Help on this typedef Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-19 23:52 +0100
                Re: Help on this typedef Keith Thompson <kst-u@mib.org> - 2017-05-19 16:42 -0700
                Re: Help on this typedef Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-20 01:16 +0100
                Re: Help on this typedef Tim Rentsch <txr@alumni.caltech.edu> - 2017-05-20 01:58 -0700
                Re: Help on this typedef joel.rees@gmail.com - 2017-05-20 02:25 -0700
                Re: Help on this typedef joel.rees@gmail.com - 2017-05-19 22:09 -0700
                Re: Help on this typedef supercat@casperkitty.com - 2017-05-19 23:23 -0700
                Re: Help on this typedef "James R. Kuyper" <jameskuyper@verizon.net> - 2017-05-19 13:33 -0400
                Re: Help on this typedef supercat@casperkitty.com - 2017-05-19 13:44 -0700
                Re: Help on this typedef jameskuyper@verizon.net - 2017-05-19 19:20 -0700
                Re: Help on this typedef supercat@casperkitty.com - 2017-05-19 23:30 -0700
                Re: Help on this typedef jameskuyper@verizon.net - 2017-05-20 07:20 -0700
                Re: Help on this typedef jameskuyper@verizon.net - 2017-05-20 07:46 -0700
                Re: Help on this typedef supercat@casperkitty.com - 2017-05-22 10:50 -0700
                Re: Help on this typedef "James R. Kuyper" <jameskuyper@verizon.net> - 2017-05-18 12:37 -0400
                Re: Help on this typedef Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-18 20:02 +0100
                Re: Help on this typedef joel.rees@gmail.com - 2017-05-19 00:20 -0700
                Re: Help on this typedef Keith Thompson <kst-u@mib.org> - 2017-05-19 09:51 -0700
                Re: Help on this typedef supercat@casperkitty.com - 2017-05-19 10:31 -0700
                Re: Help on this typedef Ike Naar <ike@iceland.freeshell.org> - 2017-05-19 19:48 +0000
                Re: Help on this typedef Tim Rentsch <txr@alumni.caltech.edu> - 2017-05-20 08:47 -0700
        Re: Help on this typedef "Patrick.Schluter" <Patrick.Schluter@free.fr> - 2017-05-27 18:50 +0200
  Re: Help on this typedef joel.rees@gmail.com - 2017-05-12 06:17 -0700
    Re: Help on this typedef supercat@casperkitty.com - 2017-05-12 08:46 -0700
      Re: Help on this typedef joel.rees@gmail.com - 2017-05-12 18:11 -0700
        Re: Help on this typedef Keith Thompson <kst-u@mib.org> - 2017-05-12 18:37 -0700
          Re: Help on this typedef Tim Rentsch <txr@alumni.caltech.edu> - 2017-05-13 09:44 -0700
            Re: Help on this typedef Keith Thompson <kst-u@mib.org> - 2017-05-13 13:47 -0700
              Re: Help on this typedef Robert Wessel <robertwessel2@yahoo.com> - 2017-05-14 00:28 -0500
              Re: Help on this typedef Tim Rentsch <txr@alumni.caltech.edu> - 2017-05-14 13:39 -0700
                Re: Help on this typedef raltbos@xs4all.nl (Richard Bos) - 2017-05-15 13:02 +0000
                Re: Help on this typedef Tim Rentsch <txr@alumni.caltech.edu> - 2017-05-15 07:30 -0700
        Re: Help on this typedef supercat@casperkitty.com - 2017-05-12 20:45 -0700
        Re: Help on this typedef Tim Rentsch <txr@alumni.caltech.edu> - 2017-05-13 09:57 -0700
        Re: Help on this typedef Philip Lantz <prl@canterey.us> - 2017-05-13 12:07 -0700
        Re: Help on this typedef David Brown <david.brown@hesbynett.no> - 2017-05-14 15:34 +0200
      Re: Help on this typedef Tim Rentsch <txr@alumni.caltech.edu> - 2017-05-14 12:48 -0700
        Re: Help on this typedef supercat@casperkitty.com - 2017-05-15 07:39 -0700
          Re: Help on this typedef Tim Rentsch <txr@alumni.caltech.edu> - 2017-05-24 08:23 -0700
            Re: Help on this typedef supercat@casperkitty.com - 2017-05-24 09:17 -0700
              Re: Help on this typedef Tim Rentsch <txr@alumni.caltech.edu> - 2017-05-27 06:15 -0700

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