In article <F3uXb.19485$hR.557901@bgtnsc05-news.ops.worldnet.att.net>,
Andrew Koenig <ark@acm.org> writes
>"Gennaro Prota" <gennaro_prota@yahoo.com> wrote in message
>news:ut6s20dk9n2vir774arg0a58nbr86084v7@4ax.com...
>
>> PROPOSED RESOLUTION: I think it would be better to drop the footnote
>> #64 (and thus the special case for ICEs), for two reasons:
>>
>> a) it's not normative anyway; so I doubt anyone is relying on the
>> guarantee it hints at, unless that guarantee is given elsewhere in a
>> normative part
>
>Footnotes are normative.

Not be standard ISO rules, footnotes, examples and notes are
non-normative.


--
Francis Glassborow      ACCU
Author of 'You Can Do It!' see http://www.spellen.org/youcandoit
For project ideas and contributions: http://www.spellen.org/youcandoit/projects

---
[ comp.std.c++ is moderated.  To submit articles, try just posting with ]
[ your news-reader.  If that fails, use mailto:std-c++@ncar.ucar.edu    ]
[              --- Please see the FAQ before posting. ---               ]
[ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html                       ]

On Sun, 15 Feb 2004 21:32:46 +0000 (UTC), francis@robinton.demon.co.uk
(Francis Glassborow) wrote:

>Not be standard ISO rules, footnotes, examples and notes are
>non-normative.

IIUC any ISO standard must conform to

  http://anubis.dkuug.dk/JTC1/SC22/WG9/isodir3.pdf


However Andrew Koenig's comment worries me a bit, because it may mean
some of the authors of the C++ standard could have thought to express
a requirement whereas readers (implementers) will not consider it to
be such.


Genny.

---
[ comp.std.c++ is moderated.  To submit articles, try just posting with ]
[ your news-reader.  If that fails, use mailto:std-c++@ncar.ucar.edu    ]
[              --- Please see the FAQ before posting. ---               ]
[ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html                       ]

In article <c5tv209dv1t5gudd6b4pkv84k8v6mdkplv@4ax.com>, Gennaro Prota
<gennaro_prota@yahoo.com> writes
>On Sun, 15 Feb 2004 21:32:46 +0000 (UTC), francis@robinton.demon.co.uk
>(Francis Glassborow) wrote:
>
>>Not be standard ISO rules, footnotes, examples and notes are
>>non-normative.
>
>IIUC any ISO standard must conform to
>
>  http://anubis.dkuug.dk/JTC1/SC22/WG9/isodir3.pdf
>
>
>However Andrew Koenig's comment worries me a bit, because it may mean
>some of the authors of the C++ standard could have thought to express
>a requirement whereas readers (implementers) will not consider it to
>be such.

I am pretty sure that Andy just misspoke because I know that he is more
familiar than most with the document at the link above.



--
Francis Glassborow      ACCU
Author of 'You Can Do It!' see http://www.spellen.org/youcandoit
For project ideas and contributions: http://www.spellen.org/youcandoit/projects

---
[ comp.std.c++ is moderated.  To submit articles, try just posting with ]
[ your news-reader.  If that fails, use mailto:std-c++@ncar.ucar.edu    ]
[              --- Please see the FAQ before posting. ---               ]
[ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html                       ]

> >Footnotes are normative.
>
> Not be standard ISO rules, footnotes, examples and notes are
> non-normative.

I'm sorry -- you're right; I misread the table in the ISO Drafting
Directives.

There's a section marked "Normative General [elements in a standard]" that
includes "footnotes" as one of those elements.  However, "Footnotes"
(actually "Footnote(s)") is in italic type, and a footnote mentions that
text in italic type represents informative elements.

Which raises the question:  If that information is in a footnote, isn't it
just informative?

Fortunately, the directives do answer that question, in subclause 6.5.2, in
which they say clearly that footnotes must not contain requirements.  I
don't know why I missed that the first time.  Sigh.

---
[ comp.std.c++ is moderated.  To submit articles, try just posting with ]
[ your news-reader.  If that fails, use mailto:std-c++@ncar.ucar.edu    ]
[              --- Please see the FAQ before posting. ---               ]
[ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html                       ]

[ note: Forwarded to C++ Committeel -sdc ]

Is reinterpret_cast<T*>(null_pointer_constant) guaranteed to yield the
null pointer value of type T*?

I think a committee clarification is needed. Here's why: 5.2.10
[expr.reinterpret.cast] par. 8 talks of "null pointer value", not
"null pointer constant", so it would seem that

  reinterpret_cast<T*>(0)

is a normal int->T* conversion, with an implementation-defined result.

However a little note to 5.2.10 [expr.reinterpret.cast] par. 5 says:

  Converting an integral constant expression (5.19) with value zero
  always yields a null pointer (4.10), but converting other
  expressions that happen to have value zero need not yield a null
  pointer.

Where is this supported in normative text? It seems that either the
footnote or paragraph 8 doesn't reflect the intent.


PROPOSED RESOLUTION: I think it would be better to drop the footnote
#64 (and thus the special case for ICEs), for two reasons:

a) it's not normative anyway; so I doubt anyone is relying on the
guarantee it hints at, unless that guarantee is given elsewhere in a
normative part

b) users expect reinterpret_casts to be almost always implementation
dependent, so this special case is a surprise. After all, if one wants
a null pointer there's static_cast. And if one wants reinterpret_cast
semantics the special case requires doing some explicit cheat, such as
using a non-const variable as intermediary:

  int v = 0;
  reinterpret_cast<T*>(v); // implementation defined

  reinterpret_cast<T*>(0); // null pointer value of type T*
  const int w = 0;
  reinterpret_cast<T*>(w); // null pointer value of type T*


It seems that not only that's providing a duplicate functionality, but
also at the cost to hide what seems the more natural one.


Genny.



[ comp.std.c++ is moderated.  To submit articles, try just posting with ]
[ your news-reader.  If that fails, use mailto:std-c++@ncar.ucar.edu    ]
[              --- Please see the FAQ before posting. ---               ]
[ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html                       ]

"Gennaro Prota" <gennaro_prota@yahoo.com> wrote in message
news:ut6s20dk9n2vir774arg0a58nbr86084v7@4ax.com...

> PROPOSED RESOLUTION: I think it would be better to drop the footnote
> #64 (and thus the special case for ICEs), for two reasons:
>
> a) it's not normative anyway; so I doubt anyone is relying on the
> guarantee it hints at, unless that guarantee is given elsewhere in a
> normative part

Footnotes are normative.

---
[ comp.std.c++ is moderated.  To submit articles, try just posting with ]
[ your news-reader.  If that fails, use mailto:std-c++@ncar.ucar.edu    ]
[              --- Please see the FAQ before posting. ---               ]
[ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html                       ]