Re: I am learning C: a little problem with a simple source code

From	Tim Rentsch <txr@alumni.caltech.edu>
Newsgroups	comp.lang.c
Subject	Re: I am learning C: a little problem with a simple source code
Date	2012-01-24 22:55 -0800
Organization	A noiseless patient Spider
Message-ID	<kfn39b4b79x.fsf@x-alumni2.alumni.caltech.edu> (permalink)
References	(2 earlier) <1c44f3e8-d55a-40ea-b89d-9772b6cdf183@gy7g2000vbb.googlegroups.com> <lnhb2ni4v5.fsf@nuthaus.mib.org> <j8r5ph$5pg$3@news.xmission.com> <j8r85n$rvp$1@dont-email.me> <ln1utqi694.fsf@nuthaus.mib.org>

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Keith Thompson <kst-u@mib.org> writes:

> [snip preliminary]
>
> My own preference would have been to make defining "main" incorrectly
> a constraint violation, not undefined behavior.  [snip elaboration]

Personally I think this is a bad idea, both for practical
reasons and principled ones.

The principle-motivated reason is this:  making something
a constraint violation is a bad idea unless it's really
clear that it never makes sense under any circumstances.
There are plenty of gray areas (the definition of main()
being one) where it often makes sense to give a diagnostic
but the decision to do so is better left to the implementation
as a QOI concern.

The practical reasons are these.  First, an implementation may
not always know exactly which forms of main() might happen to
work on a particular target platform (and there certainly are
compilers that support multiple-but-still-similar target
platforms).  Second, mandating ever more cases of required
diagnostics only increases the incentive for an implementation
to have its default mode be a non-conforming one.  Requiring
a diagnostic for the UB forms of main() may win a small battle
but lose a larger and much more important battle.  The risk
(large) is not worth the return (small).

Thread

I am learning C: a little problem with a simple source code zemir <zemir_fp@libero.it> - 2011-11-01 08:27 -0700
  Re: I am learning C: a little problem with a simple source code Mark Bluemel <mark_bluemel@pobox.com> - 2011-11-01 15:49 +0000
  Re: I am learning C: a little problem with a simple source code nroberts <roberts.noah@gmail.com> - 2011-11-01 08:52 -0700
  Re: I am learning C: a little problem with a simple source code jt@toerring.de (Jens Thoms Toerring) - 2011-11-01 16:22 +0000
  Re: I am learning C: a little problem with a simple source code Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-11-01 09:31 -0700
    Re: I am learning C: a little problem with a simple source code Ike Naar <ike@sverige.freeshell.org> - 2011-11-01 16:57 +0000
      Re: I am learning C: a little problem with a simple source code zemir <zemir_fp@libero.it> - 2011-11-01 11:51 -0700
        Re: I am learning C: a little problem with a simple source code James Kuyper <jameskuyper@verizon.net> - 2011-11-01 15:04 -0400
          Re: I am learning C: a little problem with a simple source code Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-11-01 20:21 +0000
            Re: I am learning C: a little problem with a simple source code jacob navia <jacob@spamsink.net> - 2011-11-01 21:41 +0100
        Re: I am learning C: a little problem with a simple source code Ian Collins <ian-news@hotmail.com> - 2011-11-02 08:06 +1300
          Re: I am learning C: a little problem with a simple source code zemir <zemir_fp@libero.it> - 2011-11-01 13:17 -0700
            Re: I am learning C: a little problem with a simple source code James Kuyper <jameskuyper@verizon.net> - 2011-11-01 16:24 -0400
              Re: I am learning C: a little problem with a simple source code zemir <zemir_fp@libero.it> - 2011-11-01 13:27 -0700
                Re: I am learning C: a little problem with a simple source code Keith Thompson <kst-u@mib.org> - 2011-11-01 20:24 -0700
                Re: I am learning C: a little problem with a simple source code gazelle@shell.xmission.com (Kenny McCormack) - 2011-11-02 10:24 +0000
                Re: I am learning C: a little problem with a simple source code "BartC" <bc@freeuk.com> - 2011-11-02 11:04 +0000
                Re: I am learning C: a little problem with a simple source code James Kuyper <jameskuyper@verizon.net> - 2011-11-02 07:41 -0400
                Re: I am learning C: a little problem with a simple source code Seebs <usenet-nospam@seebs.net> - 2011-11-02 18:00 +0000
                Re: I am learning C: a little problem with a simple source code Keith Thompson <kst-u@mib.org> - 2011-11-02 14:06 -0700
                Re: I am learning C: a little problem with a simple source code John Bode <jfbode1029@gmail.com> - 2011-11-03 15:05 -0700
                Re: I am learning C: a little problem with a simple source code Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 22:55 -0800
                Re: I am learning C: a little problem with a simple source code jgk@panix.com (Joe keane) - 2012-01-26 15:59 +0000
                Re: I am learning C: a little problem with a simple source code Fritz Wuehler <fritz@spamexpire-201201.rodent.frell.theremailer.net> - 2012-01-27 20:28 +0100
                Re: I am learning C: a little problem with a simple source code Markus Wichmann <nullplan@gmx.net> - 2012-01-28 14:11 +0100
                Re: I am learning C: a little problem with a simple source code Shao Miller <sha0.miller@gmail.com> - 2012-01-29 09:34 -0500
                Re: I am learning C: a little problem with a simple source code Markus Wichmann <nullplan@gmx.net> - 2012-01-30 13:38 +0100
                Re: I am learning C: a little problem with a simple source code Shao Miller <sha0.miller@gmail.com> - 2012-01-30 12:10 -0500
                Re: I am learning C: a little problem with a simple source code Zoltan Kocsi <zoltan@bendor.com.au> - 2012-01-29 08:55 +1100
                Re: I am learning C: a little problem with a simple source code Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-31 21:48 -0800
                Re: I am learning C: a little problem with a simple source code Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-31 21:46 -0800
                Re: I am learning C: a little problem with a simple source code Keith Thompson <kst-u@mib.org> - 2012-01-31 22:30 -0800
                Re: I am learning C: a little problem with a simple source code Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-08 10:11 -0800
                Re: I am learning C: a little problem with a simple source code Keith Thompson <kst-u@mib.org> - 2012-03-08 13:51 -0800
                Re: I am learning C: a little problem with a simple source code Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-09 12:51 -0800
                Re: I am learning C: a little problem with a simple source code Keith Thompson <kst-u@mib.org> - 2012-03-09 13:36 -0800
                Re: I am learning C: a little problem with a simple source code jacob navia <jacob@spamsink.net> - 2012-03-09 23:50 +0100
                Re: I am learning C: a little problem with a simple source code Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-09 15:01 -0800
                Re: I am learning C: a little problem with a simple source code Keith Thompson <kst-u@mib.org> - 2012-03-09 16:21 -0800
                Re: I am learning C: a little problem with a simple source code gazelle@shell.xmission.com (Kenny McCormack) - 2012-03-10 00:57 +0000
                Re: I am learning C: a little problem with a simple source code jacob navia <jacob@spamsink.net> - 2012-03-10 13:37 +0100
                Re: I am learning C: a little problem with a simple source code gazelle@shell.xmission.com (Kenny McCormack) - 2012-03-10 13:58 +0000
                Re: I am learning C: a little problem with a simple source code Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-10 12:24 -0800
                Re: I am learning C: a little problem with a simple source code Keith Thompson <kst-u@mib.org> - 2012-03-10 14:16 -0800
                Re: I am learning C: a little problem with a simple source code Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-11 12:50 -0700
                Re: I am learning C: a little problem with a simple source code Philip Lantz <prl@canterey.us> - 2012-03-11 00:57 -0800
                Re: I am learning C: a little problem with a simple source code Keith Thompson <kst-u@mib.org> - 2012-03-11 03:20 -0700
                Re: I am learning C: a little problem with a simple source code Philip Lantz <prl@canterey.us> - 2012-03-12 02:10 -0700
                Re: I am learning C: a little problem with a simple source code Keith Thompson <kst-u@mib.org> - 2012-03-12 10:49 -0700
                Re: I am learning C: a little problem with a simple source code Philip Lantz <prl@canterey.us> - 2012-03-14 01:16 -0700
                Re: I am learning C: a little problem with a simple source code Robert Miles <milesrf@Usenet-News.net> - 2012-04-15 06:53 -0500
                Re: I am learning C: a little problem with a simple source code Nomen Nescio <nobody@dizum.com> - 2012-04-15 19:45 +0200
                Re: I am learning C: a little problem with a simple source code Philip Lantz <prl@canterey.us> - 2012-04-15 15:06 -0700
                Re: I am learning C: a little problem with a simple source code 88888 Dihedral <dihedral88888@googlemail.com> - 2012-04-16 10:56 -0700
                Re: I am learning C: a little problem with a simple source code Ian Collins <ian-news@hotmail.com> - 2011-11-03 10:19 +1300
                Re: I am learning C: a little problem with a simple source code Seebs <usenet-nospam@seebs.net> - 2011-11-02 21:10 +0000
                Re: I am learning C: a little problem with a simple source code Kaz Kylheku <kaz@kylheku.com> - 2011-11-03 05:13 +0000
              Re: I am learning C: a little problem with a simple source code zemir <zemir_fp@libero.it> - 2011-11-01 13:29 -0700
            Re: I am learning C: a little problem with a simple source code Seebs <usenet-nospam@seebs.net> - 2011-11-01 21:44 +0000
              Re: I am learning C: a little problem with a simple source code Bill Reid <hormelfree@gmail.com> - 2011-11-03 06:33 -0700
                Re: I am learning C: a little problem with a simple source code Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-11-03 07:05 -0700
                Re: I am learning C: a little problem with a simple source code Bill Reid <hormelfree@gmail.com> - 2011-11-03 15:32 -0700
                Re: I am learning C: a little problem with a simple source code Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-11-04 01:44 -0700
                Re: I am learning C: a little problem with a simple source code Bill Reid <hormelfree@gmail.com> - 2011-11-04 07:30 -0700
                Re: I am learning C: a little problem with a simple source code John Gordon <gordon@panix.com> - 2011-11-04 16:03 +0000
                Re: I am learning C: a little problem with a simple source code Bill Reid <hormelfree@gmail.com> - 2011-11-04 09:20 -0700
                Re: I am learning C: a little problem with a simple source code John Gordon <gordon@panix.com> - 2011-11-04 16:45 +0000
                Re: I am learning C: a little problem with a simple source code Bill Reid <hormelfree@gmail.com> - 2011-11-04 11:59 -0700
                Re: I am learning C: a little problem with a simple source code John Gordon <gordon@panix.com> - 2011-11-04 19:32 +0000
                Re: I am learning C: a little problem with a simple source code Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-11-05 04:07 -0700
                Re: I am learning C: a little problem with a simple source code John Gordon <gordon@panix.com> - 2011-11-04 16:54 +0000
                Re: I am learning C: a little problem with a simple source code Bill Reid <hormelfree@gmail.com> - 2011-11-04 11:58 -0700
                Re: I am learning C: a little problem with a simple source code "io_x" <a@b.c.invalid> - 2011-11-04 18:25 +0100
                Re: I am learning C: a little problem with a simple source code gordonb.e1fpi@burditt.org (Gordon Burditt) - 2011-11-04 13:50 -0500
                Re: I am learning C: a little problem with a simple source code Pasquale Frega <zemir_fp@libero.it> - 2011-11-04 11:57 -0700
                Re: I am learning C: a little problem with a simple source code Keith Thompson <kst-u@mib.org> - 2011-11-04 14:44 -0700
                Re: I am learning C: a little problem with a simple source code "osmium" <r124c4u102@comcast.net> - 2011-11-04 14:03 -0500
                Re: I am learning C: a little problem with a simple source code Kaz Kylheku <kaz@kylheku.com> - 2011-11-04 21:37 +0000
                Re: I am learning C: a little problem with a simple source code Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-11-06 12:20 +0200
                Re: I am learning C: a little problem with a simple source code Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-11-04 08:32 -0700
                Re: I am learning C: a little problem with a simple source code Bill Reid <hormelfree@gmail.com> - 2011-11-04 09:04 -0700
                Re: I am learning C: a little problem with a simple source code Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-11-04 10:28 -0700
                Re: I am learning C: a little problem with a simple source code Seebs <usenet-nospam@seebs.net> - 2011-11-03 18:35 +0000
                Re: I am learning C: a little problem with a simple source code Pasquale Frega <zemir_fp@libero.it> - 2011-11-03 14:50 -0700
                Re: I am learning C: a little problem with a simple source code Keith Thompson <kst-u@mib.org> - 2011-11-03 15:59 -0700
                Re: I am learning C: a little problem with a simple source code Pasquale Frega <zemir_fp@libero.it> - 2011-11-04 12:00 -0700
                Re: I am learning C: a little problem with a simple source code "io_x" <a@b.c.invalid> - 2011-11-04 20:58 +0100
                Re: I am learning C: a little problem with a simple source code "io_x" <a@b.c.invalid> - 2011-11-04 21:13 +0100
                Re: I am learning C: a little problem with a simple source code Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-11-04 01:56 -0700
                Re: I am learning C: a little problem with a simple source code Pasquale Frega <zemir_fp@libero.it> - 2011-11-04 12:12 -0700
                Re: I am learning C: a little problem with a simple source code Ian Collins <ian-news@hotmail.com> - 2011-11-05 10:09 +1300
                Re: I am learning C: a little problem with a simple source code Bill Reid <hormelfree@gmail.com> - 2011-11-03 15:32 -0700
                Re: I am learning C: a little problem with a simple source code Seebs <usenet-nospam@seebs.net> - 2011-11-03 22:53 +0000
                Re: I am learning C: a little problem with a simple source code Bill Reid <hormelfree@gmail.com> - 2011-11-03 17:57 -0700
                Re: I am learning C: a little problem with a simple source code Robert Wessel <robertwessel2@yahoo.com> - 2011-11-03 21:35 -0500
                Re: I am learning C: a little problem with a simple source code Seebs <usenet-nospam@seebs.net> - 2011-11-04 03:31 +0000
                Re: I am learning C: a little problem with a simple source code Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-11-04 02:25 -0700
                Re: I am learning C: a little problem with a simple source code Kulin Remailer <remailer@reece.net.au> - 2011-11-03 22:47 +0000
                Re: I am learning C: a little problem with a simple source code Bill Reid <hormelfree@gmail.com> - 2011-11-03 16:14 -0700
                Re: I am learning C: a little problem with a simple source code Robert Wessel <robertwessel2@yahoo.com> - 2011-11-03 21:55 -0500
                Re: I am learning C: a little problem with a simple source code Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-11-04 08:10 -0700
                Re: I am learning C: a little problem with a simple source code ImpalerCore <jadill33@gmail.com> - 2011-11-04 14:21 -0700
                Re: I am learning C: a little problem with a simple source code Robert Wessel <robertwessel2@yahoo.com> - 2011-11-04 16:31 -0500
                Re: I am learning C: a little problem with a simple source code Ian Collins <ian-news@hotmail.com> - 2011-11-05 10:41 +1300
                Re: I am learning C: a little problem with a simple source code Seebs <usenet-nospam@seebs.net> - 2011-11-04 21:38 +0000
                Re: I am learning C: a little problem with a simple source code Robert Wessel <robertwessel2@yahoo.com> - 2011-11-04 22:18 -0500
                Re: I am learning C: a little problem with a simple source code Lew Pitcher <lpitcher@teksavvy.com> - 2011-11-05 11:11 -0400
                Re: I am learning C: a little problem with a simple source code Lew Pitcher <lpitcher@teksavvy.com> - 2011-11-05 11:13 -0400
                Re: I am learning C: a little problem with a simple source code Robert Wessel <robertwessel2@yahoo.com> - 2011-11-05 23:35 -0500
                Re: I am learning C: a little problem with a simple source code Seebs <usenet-nospam@seebs.net> - 2011-11-06 07:40 +0000
                Re: I am learning C: a little problem with a simple source code James Kuyper <jameskuyper@verizon.net> - 2011-11-04 18:15 -0400
                Re: I am learning C: a little problem with a simple source code ImpalerCore <jadill33@gmail.com> - 2011-11-04 20:00 -0700
                Re: I am learning C: a little problem with a simple source code James Kuyper <jameskuyper@verizon.net> - 2011-11-04 23:19 -0400
                Re: I am learning C: a little problem with a simple source code ImpalerCore <jadill33@gmail.com> - 2011-11-04 20:33 -0700
                Re: I am learning C: a little problem with a simple source code Kaz Kylheku <kaz@kylheku.com> - 2011-11-05 03:52 +0000
                Re: I am learning C: a little problem with a simple source code Ian Collins <ian-news@hotmail.com> - 2011-11-05 17:01 +1300
                Re: I am learning C: a little problem with a simple source code ImpalerCore <jadill33@gmail.com> - 2011-11-04 21:48 -0700
          Re: I am learning C: a little problem with a simple source code zemir <zemir_fp@libero.it> - 2011-11-01 13:19 -0700
            Re: I am learning C: a little problem with a simple source code Ian Collins <ian-news@hotmail.com> - 2011-11-02 09:26 +1300
          Re: I am learning C: a little problem with a simple source code zemir <zemir_fp@libero.it> - 2011-11-01 13:23 -0700
            Re: I am learning C: a little problem with a simple source code Ian Collins <ian-news@hotmail.com> - 2011-11-02 09:27 +1300
              Re: I am learning C: a little problem with a simple source code zemir <zemir_fp@libero.it> - 2011-11-01 13:31 -0700
        Re: I am learning C: a little problem with a simple source code jt@toerring.de (Jens Thoms Toerring) - 2011-11-01 22:48 +0000
          Re: I am learning C: a little problem with a simple source code Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 23:09 -0800
        Re: I am learning C: a little problem with a simple source code gordonb.prbii@burditt.org (Gordon Burditt) - 2011-11-01 21:24 -0500
        Re: I am learning C: a little problem with a simple source code Dann Corbit <dcorbit@connx.com> - 2011-11-02 21:03 -0700
          Re: I am learning C: a little problem with a simple source code Ike Naar <ike@sverige.freeshell.org> - 2011-11-03 06:39 +0000
          Re: I am learning C: a little problem with a simple source code Barry Schwarz <schwarzb@dqel.com> - 2011-11-03 18:33 -0700
            Re: I am learning C: a little problem with a simple source code Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-11-04 03:03 -0700
              Re: I am learning C: a little problem with a simple source code "io_x" <a@b.c.invalid> - 2011-11-04 11:40 +0100
              Re: I am learning C: a little problem with a simple source code Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-11-04 11:36 +0000
                Re: I am learning C: a little problem with a simple source code Kaz Kylheku <kaz@kylheku.com> - 2011-11-04 15:58 +0000
          Re: I am learning C: a little problem with a simple source code "io_x" <a@b.c.invalid> - 2011-11-04 07:24 +0100
            Re: I am learning C: a little problem with a simple source code "io_x" <a@b.c.invalid> - 2011-11-04 10:28 +0100
              Re: I am learning C: a little problem with a simple source code "io_x" <a@b.c.invalid> - 2011-11-04 16:02 +0100
                Re: I am learning C: a little problem with a simple source code "io_x" <a@b.c.invalid> - 2011-11-04 16:20 +0100
                Re: I am learning C: a little problem with a simple source code "io_x" <a@b.c.invalid> - 2011-11-04 16:39 +0100
            Re: I am learning C: a little problem with a simple source code "io_x" <a@b.c.invalid> - 2011-11-06 18:07 +0100
              Re: I am learning C: a little problem with a simple source code Barry Schwarz <schwarzb@dqel.com> - 2011-11-06 09:59 -0800
                Re: I am learning C: a little problem with a simple source code "io_x" <a@b.c.invalid> - 2011-11-06 19:23 +0100
                Re: I am learning C: a little problem with a simple source code James Kuyper <jameskuyper@verizon.net> - 2011-11-06 15:23 -0500
      Re: I am learning C: a little problem with a simple source code zemir <zemir_fp@libero.it> - 2011-11-01 11:52 -0700
        Re: I am learning C: a little problem with a simple source code "BartC" <bc@freeuk.com> - 2011-11-01 23:02 +0000
  Re: I am learning C: a little problem with a simple source code Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-11-02 03:53 -0700
    Re: I am learning C: a little problem with a simple source code James Kuyper <jameskuyper@verizon.net> - 2011-11-02 08:03 -0400
      Re: I am learning C: a little problem with a simple source code Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-11-02 06:11 -0700

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