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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:
>>> 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.  [snip elaboration]
>
> Yes but the example is there!  That's really the point of
> what I'm saying:  given that the example _is_ there, I think
> it's highly unlikely that anyone will be misled about what
> the Standard expects should happen.  Right?  Or do you think
> they won't notice or won't understand the example?

Sure, the example is clear enough.

I just don't think that the assertion in the example follows,
or *should* follow, from the normative text.  And I wouldn't want
to rely on what it says, both because if I want a 1-element array
it's easy enough to replace "[]" by "[1]", and because I wouldn't be
astonished if some compiler, following just the normative wording,
didn't implement it that way.

-- 
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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