Re: Variables allocated on stack

From	Keith Thompson <kst-u@mib.org>
Newsgroups	comp.lang.c
Subject	Re: Variables allocated on stack
Date	2012-01-25 12:23 -0800
Organization	None to speak of
Message-ID	<ln4nvj5y5f.fsf@nuthaus.mib.org> (permalink)
References	(11 earlier) <u2e9q8-cc3.ln1@voyager.wichi.de.vu> <lnehwrsrxw.fsf@nuthaus.mib.org> <gp0iq8-af4.ln1@voyager.wichi.de.vu> <lnk46hqzqi.fsf@nuthaus.mib.org> <kfnr4yo7wqp.fsf@x-alumni2.alumni.caltech.edu>

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Tim Rentsch <txr@alumni.caltech.edu> writes:
> Keith Thompson <kst-u@mib.org> writes:
[...]
>> I've argued that a program using "int main()", as opposed to "int
>> main(void)", has undefined behavior, since "int main()" is not one of
>> the forms permitted by C99 5.1.2.2.1 (nor is it quite equivalent to
>> either of them).  [snip]
>
> It is equivalent in the sense that the Standard uses the
> term.  Obviously so, since otherwise every single K&R-era
> program that had 'int main(){ ... }' would have undefined
> behavior under ANSI/ISO C;  surely that point was considered
> by the standard committee.

I'm uncomfortable with conclusions reached by first assuming that the
standard doesn't break pre-ANSI code, and interpreting the wording based
on that assumption.

I can accept, based on your argument, that "int main()" is *intended* to
be valid.  I don't agree that the current wording in the standard
actually *says* that it's valid.  The only basis for assuming that
"equivalent" has the meaning you say it does is that Bad Things Happen
if it doesn't.

Someone reading the current ISO C standard with no knowledge of pre-ANSI
C would have no basis to assume that "int main()" is valid.

These two programs differ only in how they define main, and they clearly
are not equivalent; the first violates a constraint, while the second
does not.

int main(void) {
    if (0) return main(42);
}

int main() {
    if (0) return main(42);
}

I believe this was an oversight by the authors of the standard (one that
isn't corrected in C11, unless they did something after N1570).

-- 
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"

Thread

Variables allocated on stack Bogdan <cristeab@gmail.com> - 2011-11-24 13:28 -0800
  Re: Variables allocated on stack Ian Collins <ian-news@hotmail.com> - 2011-11-25 10:40 +1300
  Re: Variables allocated on stack jacob navia <jacob@spamsink.net> - 2011-11-24 23:30 +0100
    Re: Variables allocated on stack Quentin Pope <qp19433@hotmail.NOSPAM.com> - 2011-12-02 22:33 +0000
      Re: Variables allocated on stack jacob navia <jacob@spamsink.net> - 2011-12-03 00:54 +0100
      Re: Variables allocated on stack Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-12-02 23:33 -0800
        Re: Variables allocated on stack Keith Thompson <kst-u@mib.org> - 2011-12-03 02:25 -0800
  Re: Variables allocated on stack jt@toerring.de (Jens Thoms Toerring) - 2011-11-24 23:37 +0000
  Re: Variables allocated on stack Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-11-25 01:53 -0800
    Re: Variables allocated on stack "BartC" <bc@freeuk.com> - 2011-11-25 11:05 +0000
      Re: Variables allocated on stack jacob navia <jacob@spamsink.net> - 2011-11-25 12:11 +0100
        Re: Variables allocated on stack "BartC" <bc@freeuk.com> - 2011-11-25 11:40 +0000
          Re: Variables allocated on stack jacob navia <jacob@spamsink.net> - 2011-11-25 12:52 +0100
            Re: Variables allocated on stack Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-11-27 02:31 -0800
              Re: Variables allocated on stack jacob navia <jacob@spamsink.net> - 2011-11-27 13:28 +0100
              Re: Variables allocated on stack André Gillibert <MetaEntropy.removeThis@gmail.com> - 2011-11-27 13:44 +0100
                Re: Variables allocated on stack jacob navia <jacob@spamsink.net> - 2011-11-27 15:44 +0100
                Re: Variables allocated on stack André Gillibert <MetaEntropy.removeThis@gmail.com> - 2011-11-27 17:34 +0100
                Re: Variables allocated on stack jacob navia <jacob@spamsink.net> - 2011-11-27 18:28 +0100
                Re: Variables allocated on stack Ian Collins <ian-news@hotmail.com> - 2011-11-28 07:48 +1300
                Re: Variables allocated on stack gwowen <gwowen@gmail.com> - 2011-11-29 01:11 -0800
                Re: Variables allocated on stack jacob navia <jacob@spamsink.net> - 2011-11-29 17:02 +0100
          Re: Variables allocated on stack Seebs <usenet-nospam@seebs.net> - 2011-11-26 07:21 +0000
            Re: Variables allocated on stack "BartC" <bc@freeuk.com> - 2011-11-26 11:07 +0000
              Re: Variables allocated on stack Markus Wichmann <nullplan@gmx.net> - 2011-11-26 21:16 +0100
                Re: Variables allocated on stack "BartC" <bc@freeuk.com> - 2011-11-26 23:00 +0000
                Re: Variables allocated on stack Ian Collins <ian-news@hotmail.com> - 2011-11-27 12:12 +1300
                Re: Variables allocated on stack "BartC" <bc@freeuk.com> - 2011-11-26 23:35 +0000
                Re: Variables allocated on stack Ian Collins <ian-news@hotmail.com> - 2011-11-27 12:48 +1300
                Re: Variables allocated on stack Markus Wichmann <nullplan@gmx.net> - 2011-11-27 10:56 +0100
                Re: Variables allocated on stack Keith Thompson <kst-u@mib.org> - 2011-11-28 16:17 -0800
                Re: Variables allocated on stack Markus Wichmann <nullplan@gmx.net> - 2011-11-30 17:04 +0100
                Re: Variables allocated on stack Keith Thompson <kst-u@mib.org> - 2011-11-30 09:36 -0800
                Re: Variables allocated on stack Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-25 05:11 -0800
                Re: Variables allocated on stack Keith Thompson <kst-u@mib.org> - 2012-01-25 12:23 -0800
                Re: Variables allocated on stack Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-31 19:11 -0800
                Re: Variables allocated on stack Ian Collins <ian-news@hotmail.com> - 2011-11-27 13:06 +1300
                Re: Variables allocated on stack André Gillibert <MetaEntropy.removeThis@gmail.com> - 2011-11-27 11:20 +0100
                Re: Variables allocated on stack David Thompson <dave.thompson2@verizon.net> - 2012-01-19 02:43 -0500
              Re: Variables allocated on stack Seebs <usenet-nospam@seebs.net> - 2011-11-28 08:32 +0000
    Re: Variables allocated on stack Bogdan <cristeab@gmail.com> - 2011-11-26 01:18 -0800
      Re: Variables allocated on stack Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-11-26 08:36 -0500
  Re: Variables allocated on stack Seebs <usenet-nospam@seebs.net> - 2011-11-26 07:21 +0000
  Re: Variables allocated on stack Noob <root@127.0.0.1> - 2011-11-29 11:51 +0100

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