Re: VAX

From	Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups	comp.lang.c
Subject	Re: VAX
Date	2026-01-06 21:33 -0800
Organization	A noiseless patient Spider
Message-ID	<868qeaq963.fsf@linuxsc.com> (permalink)
References	(16 earlier) <6859dc0d-f3b5-481b-8ffb-b4c0a722412e@alumni.caltech.edu> <20250804224049.00006937@yahoo.com> <20250805140933.174@kylheku.com> <106vtsh$2uli0$1@dont-email.me> <878qjw6ub8.fsf@example.invalid>

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Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:

> James Kuyper <jameskuyper@alumni.caltech.edu> writes:
>
>> On 2025-08-05 17:13, Kaz Kylheku wrote:
>>
>>> On 2025-08-04, Michael S <already5chosen@yahoo.com> wrote:
>>>
>>>> On Mon, 4 Aug 2025 15:25:54 -0400
>>>> James Kuyper <jameskuyper@alumni.caltech.edu> wrote:
>>
>> ...
>>
>>>>> If _BitInt is accepted by older versions of gcc, that means it
>>>>> was supported as a fully-conforming extension to C. Allowing
>>>>> implementations to support extensions in a fully-conforming
>>>>> manner is one of the main purposes for which the standard
>>>>> reserves identifiers.  If you thought that gcc was too
>>>>> conservative to support extensions, you must be thinking of the
>>>>> wrong organization.
>>>>
>>>> I know that gcc supports extensions.
>>>> I also know that gcc didn't support *this particular extension*
>>>> up until quite recently.
>>>
>>> I think what James means is that GCC supports, as an extension,
>>> the use of any _[A-Z].* identifier whatsoever that it has not
>>> claimed for its purposes.
>>
>> No, I meant very specifically that if, as reported, _BitInt was
>> supported even in earlier versions, then it was supported as an
>> extension.
>
> gcc 13.4.0 does not recognize _BitInt at all.
>
> gcc 14.2.0 handles _BitInt as a language feature in C23 mode,
> and as an "extension" in pre-C23 modes.
>
> It warns about _BitInt with "-std=c17 -pedantic", but not with
> just "-std=c17".  I think I would have preferred a warning with
> "-std=c17", but it doesn't bother me.  There's no mention of _BitInt
> as an extension or feature in the documentation.  An implementation
> is required to document the implementation-defined value of
> BITINT_MAXWIDTH, so that's a conformance issue.  In pre-C23 mode,
> since it's not documented, support for _BitInt is not formally an
> "extension";  it's an allowed behavior in the presence of code that
> has undefined behavior due to its use of a reserved identifier.
> (This is a picky language-lawyerly interpretation.)

To clarify the last part, undefined behavior is allowed only
because a diagnostic was generated.  If there were no diagnostic
then it would have to be documented as an extension, otherwise
the implementation would not be conforming.

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Re: VAX Michael S <already5chosen@yahoo.com> - 2025-08-04 18:28 +0300
  Re: VAX Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-08-04 09:53 -0700
    Re: VAX Michael S <already5chosen@yahoo.com> - 2025-08-04 22:03 +0300
      Re: VAX James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-08-04 15:25 -0400
        Re: VAX Michael S <already5chosen@yahoo.com> - 2025-08-04 22:40 +0300
          Re: VAX "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2025-08-04 12:44 -0700
          Re: VAX Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-08-04 22:21 -0700
            Re: VAX Kaz Kylheku <643-408-1753@kylheku.com> - 2025-08-05 21:25 +0000
              Re: VAX Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-08-05 19:14 -0700
                Re: VAX Kaz Kylheku <643-408-1753@kylheku.com> - 2025-08-06 04:31 +0000
                Re: VAX Michael S <already5chosen@yahoo.com> - 2025-08-06 11:48 +0300
              Re: VAX James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-08-06 11:56 -0400
                Re: VAX Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-12-15 11:51 -0800
          Re: VAX Kaz Kylheku <643-408-1753@kylheku.com> - 2025-08-05 21:13 +0000
            Re: VAX James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-08-06 11:54 -0400
              Re: VAX Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-08-06 13:58 -0700
                Re: VAX Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-01-06 21:33 -0800
      Re: VAX Kaz Kylheku <643-408-1753@kylheku.com> - 2025-08-05 21:08 +0000
        Re: VAX Jakob Bohm <egenagwemdimtapsar@jbohm.dk> - 2025-08-17 20:18 +0200
          Re: VAX Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-08-17 22:18 -0700
            Re: VAX Richard Heathfield <rjh@cpax.org.uk> - 2025-08-18 08:02 +0100
            Re: VAX David Brown <david.brown@hesbynett.no> - 2025-08-18 11:34 +0200
              Re: VAX Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-08-18 21:57 -0700
    Re: VAX Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-01-06 21:14 -0800

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