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Re: ridiculous warning or not?

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Tim Rentsch <txr@alumni.caltech.edu> writes:
> Keith Thompson <kst-u@mib.org> writes:
>> Tim Rentsch <txr@alumni.caltech.edu> writes:
>> [...]
>>> I understand that you would like how the Standard is read to be
>>> the same in comp.lang.c and comp.std.c.  For now, though, let me
>>> suggest that conversations about that are better in comp.std.c,
>>> and for purposes of comp.lang.c it's better to read the Standard
>>> how you think the committee reads it or expects it will be read.
>>> Does that all make sense?
>>
>> Yes, more or less.  In this particular case, though, there's a rule
>> that's only stated in an example, and that IMHO is not supported
>> by the normative text (though it could be with a small tweak).
>> Furthermore, it's a rule that doesn't make a whole lot of sense
>> to me.  This raised, at least for me, a serious question about what
>>
>>     int i[];
>>
>> as an external definition with no later completion of the type
>> actually *means*, and whether it's even valid.  It raises issues both
>> about the text of the standard (clearly appropriate for comp.std.c),
>> and about the semantics of the language defined by the standard
>> (clearly appropriate for comp.lang.c).
>
> Oh, that may be a difference between us.  As far as I'm concerned,
> what happens in this case is both defined enough and clear enough
> (for purposes of comp.lang.c) so that there's no question about
> what's supposed to happen.  I agree that the Standard could do a
> better job of expressing this, but not so much that anyone who
> wants to understand what semantics are dictated is likely to be
> misled.  Let me ask it as a question:  how likely is it (in your
> opinion) that someone reading the Standard will reach a wrong
> conclusion about what the behavior should be in such cases?

Very likely, IMHO.

The wording in question is N1570 6.9.2p5, a non-normative example:

    EXAMPLE 2 If at the end of the translation unit containing

        int i[];

    the array i still has incomplete type, the implicit initializer
    causes it to have one element, which is set to zero on program
    startup.

In the absence of that example, it would never have occurred to me that
the array i has one element.  If I thought about it, I'd probably
conclude that it's equivalent to

    int i[] = 0;

("with an initializer equal to 0", 6.9.2p2), and therefore a constraint
violation, or at least undefined behavior.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
    Will write code for food.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

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Thread

ridiculous warning or not? kerravon <kerravon@w3.to> - 2012-08-20 02:41 -0700
  Re: ridiculous warning or not? Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-20 07:55 -0400
  Re: ridiculous warning or not? army1987 <army1987@ask-for-it.invalid> - 2012-08-20 19:11 +0000
  Re: ridiculous warning or not? Kenneth Brody <kenbrody@spamcop.net> - 2012-08-20 16:09 -0400
    Re: ridiculous warning or not? Tim Rentsch <txr@alumni.caltech.edu> - 2012-09-07 07:29 -0700
  Re: ridiculous warning or not? Andrew Cooper <amc96@cam.ac.uk> - 2012-08-21 00:36 +0100
  Re: ridiculous warning or not? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-08-21 01:41 +0100
    Re: ridiculous warning or not? Keith Thompson <kst-u@mib.org> - 2012-08-20 18:59 -0700
      Re: ridiculous warning or not? Tim Rentsch <txr@alumni.caltech.edu> - 2012-09-07 08:03 -0700
        Re: ridiculous warning or not? Keith Thompson <kst-u@mib.org> - 2012-09-07 14:37 -0700
          Re: ridiculous warning or not? Tim Rentsch <txr@alumni.caltech.edu> - 2012-09-07 19:17 -0700
            Re: ridiculous warning or not? Keith Thompson <kst-u@mib.org> - 2012-09-07 19:56 -0700
              Re: ridiculous warning or not? Tim Rentsch <txr@alumni.caltech.edu> - 2012-09-08 06:30 -0700
    Re: ridiculous warning or not? Tim Rentsch <txr@alumni.caltech.edu> - 2012-09-07 07:57 -0700
      Re: ridiculous warning or not? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-09-08 00:25 +0100
        Re: ridiculous warning or not? Tim Rentsch <txr@alumni.caltech.edu> - 2012-09-07 18:58 -0700
          Re: ridiculous warning or not? Keith Thompson <kst-u@mib.org> - 2012-09-07 19:26 -0700
            Re: ridiculous warning or not? Tim Rentsch <txr@alumni.caltech.edu> - 2012-09-08 06:26 -0700
              Re: ridiculous warning or not? Keith Thompson <kst-u@mib.org> - 2012-09-08 11:33 -0700
                Re: ridiculous warning or not? Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-17 14:39 -0800
                Re: ridiculous warning or not? Keith Thompson <kst-u@mib.org> - 2012-12-17 15:56 -0800
                Re: ridiculous warning or not? Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-20 10:31 -0800
                Re: ridiculous warning or not? Keith Thompson <kst-u@mib.org> - 2012-12-20 16:57 -0800
                Re: ridiculous warning or not? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-21 03:11 +0000
                Re: ridiculous warning or not? Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-21 09:06 -0800
          Re: ridiculous warning or not? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-09-08 03:42 +0100
            Re: ridiculous warning or not? Tim Rentsch <txr@alumni.caltech.edu> - 2012-09-08 06:01 -0700
              Re: ridiculous warning or not? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-09-08 14:45 +0100
                Re: ridiculous warning or not? Keith Thompson <kst-u@mib.org> - 2012-09-08 11:28 -0700
                Re: ridiculous warning or not? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-09-08 22:53 +0100
  Re: ridiculous warning or not? kerravon <kerravon@w3.to> - 2012-08-21 03:25 -0700
    Re: ridiculous warning or not? 88888 Dihedral <dihedral88888@googlemail.com> - 2012-08-21 11:20 -0700
      Re: ridiculous warning or not? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-08-21 21:07 +0100
        Re: ridiculous warning or not? 88888 Dihedral <dihedral88888@googlemail.com> - 2012-08-21 14:39 -0700
          Re: ridiculous warning or not? Ike Naar <ike@iceland.freeshell.org> - 2012-08-21 22:09 +0000
            Re: ridiculous warning or not? 88888 Dihedral <dihedral88888@googlemail.com> - 2012-08-21 15:13 -0700
              Re: ridiculous warning or not? Fred K <fred.l.kleinschmidt@gmail.com> - 2012-08-22 07:17 -0700

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