Re: terminal designed for C

From	James Kuyper <jameskuyper@verizon.net>
Newsgroups	comp.lang.c
Subject	Re: terminal designed for C
Date	2012-12-17 15:51 -0500
Organization	A noiseless patient Spider
Message-ID	<50CF85CF.1050101@verizon.net> (permalink)
References	(14 earlier) <dda13ffb-bf74-4a34-95df-8042c4f7bf5f@googlegroups.com> <k6fi5e$c6r$1@dont-email.me> <lnzk38s3vm.fsf@nuthaus.mib.org> <kfn38z4ikg5.fsf@x-alumni2.alumni.caltech.edu> <ln7gogifvk.fsf@nuthaus.mib.org>

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On 12/17/2012 03:27 PM, Keith Thompson wrote:
> Tim Rentsch <txr@alumni.caltech.edu> writes:
>> Keith Thompson <kst-u@mib.org> writes:
>>> James Kuyper <jameskuyper@verizon.net> writes:
...
>>>> No, that isn't the case. A C99 compiler need not conform to C90, and
>>>> need not even have a option to do so. It may even be impossible to
>>>> conform to both simultaneously, though I'd have to think about that for
>>>> a while to be sure.
>>>
>>> Hmm.  I think it would be possible for a compiler to conform to both C90
>>> and C99, though it would be ugly.  [snip elaboration]
>>
>> Can't be done, because there are programs that are well-defined
>> in both languages but have different semantics in the two cases.
> 
> I'd be interested in seeing an example.

Reviewing the list of changes from C90 in paragraph 5 of the Forward to
n1256.pdf, it seems as though most of the differences took the form of
giving defined behavior to code that was a syntax error, a constraint
violation, or had undefined behavior in C90. In a few cases the opposite
occurred. None of those cases is a barrier to simultaneous conformance:
give the constructs the meaning required by one version of the standard,
after generating the diagnostic (if any) required by the other version.

It requires more knowledge than I possess about C90 to determine whether
any of these cases would actually prevent simultaneous conformance:

Is there any context where UCNs are allowed in C99, where they would
also have been permitted in C90 with a conflicting interpretation?

It merely says that the integer constant type rules and the promotion
rules change. Is there any case where those changes could not be
rendered invisible by suitable choices for the values of *_MAX from
<limits.h>?

Thread

terminal designed for C kerravon <kerravon@w3.to> - 2012-10-22 21:19 -0700
  Re: terminal designed for C Robert Wessel <robertwessel2@yahoo.com> - 2012-10-22 23:34 -0500
    Re: terminal designed for C kerravon <kerravon@w3.to> - 2012-10-22 21:56 -0700
  Re: terminal designed for C Sjouke Burry <s@b> - 2012-10-23 14:42 +0000
    Re: terminal designed for C Keith Thompson <kst-u@mib.org> - 2012-10-23 13:06 -0700
      Re: terminal designed for C kerravon <kerravon@w3.to> - 2012-10-23 15:46 -0700
        Re: terminal designed for C Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-10-23 20:29 -0400
          Re: terminal designed for C Lew Pitcher <lpitcher@teksavvy.com> - 2012-10-23 21:26 -0400
          Re: terminal designed for C kerravon <kerravon@w3.to> - 2012-10-24 02:59 -0700
            Re: terminal designed for C Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-10-24 14:15 -0400
            Re: terminal designed for C Lew Pitcher <lpitcher@teksavvy.com> - 2012-10-24 17:23 -0400
  Re: terminal designed for C Lew Pitcher <lpitcher@teksavvy.com> - 2012-10-23 18:55 -0400
    Re: terminal designed for C Keith Thompson <kst-u@mib.org> - 2012-10-23 19:56 -0700
    Re: terminal designed for C kerravon <kerravon@w3.to> - 2012-10-24 16:10 -0700
      Re: terminal designed for C Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-10-24 20:15 -0400
      Re: terminal designed for C Lew Pitcher <lpitcher@teksavvy.com> - 2012-10-24 21:13 -0400
        Re: terminal designed for C kerravon <kerravon@w3.to> - 2012-10-24 21:09 -0700
          Re: terminal designed for C "BartC" <bc@freeuk.com> - 2012-10-25 11:29 +0100
            Re: terminal designed for C kerravon <kerravon@w3.to> - 2012-10-25 03:51 -0700
          Re: terminal designed for C James Kuyper <jameskuyper@verizon.net> - 2012-10-25 08:49 -0400
          Re: terminal designed for C Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-10-25 09:04 -0400
            Re: terminal designed for C kerravon <kerravon@w3.to> - 2012-10-25 14:11 -0700
              Re: terminal designed for C Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-10-25 17:29 -0400
                Re: terminal designed for C kerravon <kerravon@w3.to> - 2012-10-26 03:33 -0700
                Re: terminal designed for C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-10-26 12:35 +0100
                Re: terminal designed for C kerravon <kerravon@w3.to> - 2012-10-26 15:46 -0700
                Re: terminal designed for C Keith Thompson <kst-u@mib.org> - 2012-10-26 17:11 -0700
                Re: terminal designed for C kerravon <kerravon@w3.to> - 2012-10-26 17:27 -0700
                Re: terminal designed for C Ian Collins <ian-news@hotmail.com> - 2012-10-27 13:39 +1300
                Re: terminal designed for C kerravon <kerravon@w3.to> - 2012-10-26 18:30 -0700
                Re: terminal designed for C James Kuyper <jameskuyper@verizon.net> - 2012-10-26 22:50 -0400
                Re: terminal designed for C Keith Thompson <kst-u@mib.org> - 2012-10-27 01:42 -0700
                Re: terminal designed for C James Kuyper <jameskuyper@verizon.net> - 2012-10-27 19:18 -0400
                Re: terminal designed for C Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-17 10:48 -0800
                Re: terminal designed for C Keith Thompson <kst-u@mib.org> - 2012-12-17 12:27 -0800
                Re: terminal designed for C James Kuyper <jameskuyper@verizon.net> - 2012-12-17 15:51 -0500
                Re: terminal designed for C Keith Thompson <kst-u@mib.org> - 2012-12-17 13:35 -0800
                Re: terminal designed for C James Kuyper <jameskuyper@verizon.net> - 2012-12-17 16:48 -0500
                Re: terminal designed for C Robert Wessel <robertwessel2@yahoo.com> - 2012-12-17 14:53 -0600
                Re: terminal designed for C Keith Thompson <kst-u@mib.org> - 2012-12-17 13:20 -0800
                Re: terminal designed for C Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-20 10:19 -0800
                Re: terminal designed for C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-10-27 02:35 +0100
                Re: terminal designed for C kerravon <kerravon@w3.to> - 2012-10-26 18:58 -0700
                Re: terminal designed for C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-10-27 05:01 +0100
                Re: terminal designed for C Robert Wessel <robertwessel2@yahoo.com> - 2012-10-27 00:56 -0500
                Re: terminal designed for C James Kuyper <jameskuyper@verizon.net> - 2012-10-26 09:03 -0400
                Re: terminal designed for C Keith Thompson <kst-u@mib.org> - 2012-10-26 11:13 -0700
                Re: terminal designed for C kerravon <kerravon@w3.to> - 2012-10-26 15:15 -0700
            Re: terminal designed for C lawrence.jones@siemens.com - 2012-11-12 18:08 -0500
  Re: terminal designed for C falk@rahul.net (Edward A. Falk) - 2012-10-24 17:29 +0000
  Re: terminal designed for C Keith Thompson <kst-u@mib.org> - 2012-10-24 11:55 -0700

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