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Re: pointers

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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:
>>> supercat@casperkitty.com writes:
>>>> The Standard does [say] that no conforming extension should alter
>>>> the effect of a strictly-conforming program, but many of the
>>>> "Common Extensions" listed in the annex would do precisely that.
>>>
>>> That depends on how the extension is implemented, doesn't it?  Or
>>> are you saying that some of the listed common extensions would be
>>> impossible to implement without changing some strictly conforming
>>> programs?  If so, which of the listed extensions fall into that
>>> category?
>>
>> The "fortran" and "asm" keywords, if they're treated as keywords in
>> all contexts, would clearly break strictly conforming programs that
>> use them as identifiers (J.5.9, J.5.10).
>
> Sure.  If treated as keywords in the same way that regular C
> keywords are treated, then yes.  If instead they were treated as
> some form of optional, context-dependent keywords, then they
> wouldn't necessarily intrude on the strictly-conformingness
> property - right?

Of course, but that's not what I was referring to -- which is why I
wrote "*if* they're treated as keywords in all contexts".

My point is that J.5 lists "common extensions"; it does not limit itself
to *conforming* extensions.  And non-conforming extensions are in fact
common.  For example, gcc with default options (which is known to be
non-conforming) reports a syntax error on `int asm;`.

That's clearly the kind of thing J.5p1 is talking about, extensions that
"render an implementation nonconforming".

>> Likewise for predefined
>> macro names using unreserved identifers (J.5.12).
>
> In this case too I believe it is possible to implement some form
> of "weak" macro definitions that would not intrude on the
> strictly-conformingness property.  I admit that it's harder to do
> that with macros than the previous case.  But there is another
> point worth mentioning here:  the offending macro definitions may
> be in force only when the compilation is already in some sort of
> non-conforming mode.  In gcc, for example, there are predefined
> macros such as 'unix', but these predefined macros go away when
> an option like -std=c99 or -ansi is used.  So the objection is
> very likely not strictly correct, but even in cases where it
> applies it seems to be vastly overblown.

Annex J is not normative anyway, and J.5 in particular veers into
discussing non-conforming implementations (which, to be overly pedantic,
aren't really C implementations at all).  I'm not sure what's being
"vastly oveblown", or who is overblowing it.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

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pointers asetofsymbols@gmail.com - 2016-10-23 08:11 -0700
  Re: pointers Richard Heathfield <rjh@cpax.org.uk> - 2016-10-23 16:26 +0100
    Re: pointers asetofsymbols@gmail.com - 2016-10-23 10:35 -0700
      Re: pointers Ike Naar <ike@iceland.freeshell.org> - 2016-10-23 17:47 +0000
        Re: pointers asetofsymbols@gmail.com - 2016-10-25 12:55 -0700
      Re: pointers "James R. Kuyper" <jameskuyper@verizon.net> - 2016-10-23 13:58 -0400
        Re: pointers BartC <bc@freeuk.com> - 2016-10-24 00:55 +0100
          Re: pointers Keith Thompson <kst-u@mib.org> - 2016-10-23 17:27 -0700
            Re: pointers BartC <bc@freeuk.com> - 2016-10-24 11:53 +0100
              Re: pointers supercat@casperkitty.com - 2016-10-24 07:29 -0700
                Re: pointers Keith Thompson <kst-u@mib.org> - 2016-10-24 08:55 -0700
                Re: pointers Tim Rentsch <txr@alumni.caltech.edu> - 2016-10-24 14:02 -0700
                Re: pointers Keith Thompson <kst-u@mib.org> - 2016-10-24 14:42 -0700
                Re: pointers Tim Rentsch <txr@alumni.caltech.edu> - 2016-10-25 08:56 -0700
                Re: pointers Keith Thompson <kst-u@mib.org> - 2016-10-25 12:17 -0700
                Re: pointers Tim Rentsch <txr@alumni.caltech.edu> - 2016-10-26 06:37 -0700
              Re: pointers Keith Thompson <kst-u@mib.org> - 2016-10-24 08:49 -0700
                Re: pointers BartC <bc@freeuk.com> - 2016-10-24 17:25 +0100
                Re: pointers Keith Thompson <kst-u@mib.org> - 2016-10-24 09:52 -0700
                Re: pointers BartC <bc@freeuk.com> - 2016-10-24 18:15 +0100
                Re: pointers Keith Thompson <kst-u@mib.org> - 2016-10-24 12:20 -0700
                Re: pointers BartC <bc@freeuk.com> - 2016-10-24 20:58 +0100
                Re: pointers Keith Thompson <kst-u@mib.org> - 2016-10-24 13:16 -0700
                Re: pointers BartC <bc@freeuk.com> - 2016-10-24 23:53 +0100
                Re: pointers Keith Thompson <kst-u@mib.org> - 2016-10-25 13:38 -0700
                Re: pointers BartC <bc@freeuk.com> - 2016-10-25 23:06 +0100
                Re: pointers Keith Thompson <kst-u@mib.org> - 2016-10-25 15:39 -0700
                Re: pointers BartC <bc@freeuk.com> - 2016-10-26 00:26 +0100
                Re: pointers Keith Thompson <kst-u@mib.org> - 2016-10-25 16:44 -0700
                Re: pointers BartC <bc@freeuk.com> - 2016-10-26 01:02 +0100
                Re: pointers Keith Thompson <kst-u@mib.org> - 2016-10-25 17:35 -0700
                Re: pointers Ike Naar <ike@iceland.freeshell.org> - 2016-10-26 06:27 +0000
                Re: pointers BartC <bc@freeuk.com> - 2016-10-26 12:47 +0100
                Re: pointers Keith Thompson <kst-u@mib.org> - 2016-10-26 09:05 -0700
                Re: pointers BartC <bc@freeuk.com> - 2016-10-26 18:46 +0100
                Re: pointers supercat@casperkitty.com - 2016-10-26 11:44 -0700
                Re: pointers BartC <bc@freeuk.com> - 2016-10-26 20:12 +0100
                Re: pointers BartC <bc@freeuk.com> - 2016-10-26 20:30 +0100
                Re: pointers supercat@casperkitty.com - 2016-10-26 13:02 -0700
                Re: pointers Keith Thompson <kst-u@mib.org> - 2016-10-26 11:52 -0700
                Re: pointers Ike Naar <ike@iceland.freeshell.org> - 2016-10-26 19:11 +0000
                Re: pointers BartC <bc@freeuk.com> - 2016-10-26 21:25 +0100
                Re: pointers "James R. Kuyper" <jameskuyper@verizon.net> - 2016-10-25 18:56 -0400
                Re: pointers "James R. Kuyper" <jameskuyper@verizon.net> - 2016-10-25 19:12 -0400
                Re: pointers Keith Thompson <kst-u@mib.org> - 2016-10-25 16:31 -0700
                Re: pointers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-24 21:36 +0100
                Re: pointers BartC <bc@freeuk.com> - 2016-10-25 16:54 +0100
                Re: pointers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-25 19:09 +0100
                Re: pointers supercat@casperkitty.com - 2016-10-24 11:33 -0700
                Re: pointers Keith Thompson <kst-u@mib.org> - 2016-10-24 12:22 -0700
          Re: pointers James Kuyper <jameskuyper@verizon.net> - 2016-10-24 10:23 -0400
  Re: pointers "James R. Kuyper" <jameskuyper@verizon.net> - 2016-10-23 12:31 -0400
    Re: pointers Richard Heathfield <rjh@cpax.org.uk> - 2016-10-23 17:38 +0100
  Re: pointers Lorinczy Zsigmond <zsiga@nospam.for.me> - 2016-10-24 14:02 +0200
  Re: pointers John Bode <jfbode1029@gmail.com> - 2016-10-24 13:34 -0700

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