Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c > #384077

Re: Casting the return value of ...

Path csiph.com!news.swapon.de!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups comp.lang.c
Subject Re: Casting the return value of ...
Date Thu, 28 Mar 2024 15:37:22 -0700
Organization None to speak of
Lines 44
Message-ID <877chmt23h.fsf@nosuchdomain.example.com> (permalink)
References <uu416t$33u55$1@news.xmission.com> <20240328105203.773@kylheku.com> <87frwatadu.fsf@nosuchdomain.example.com> <uu4k1c$3pq71$1@dont-email.me> <87bk6yt68v.fsf@nosuchdomain.example.com> <20240328142950.542@kylheku.com>
MIME-Version 1.0
Content-Type text/plain
Injection-Date Thu, 28 Mar 2024 22:37:26 +0100 (CET)
Injection-Info dont-email.me; posting-host="2dfbf40368bf600f73fcb17ce635941b"; logging-data="4051192"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX188lkDH6aStEoLMJHydXngX"
User-Agent Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux)
Cancel-Lock sha1:pl94fXoV0akPKONf2HCdTiEslbQ= sha1:a+AonyASiQGcWoDVgufEgLRBYTc=
Xref csiph.com comp.lang.c:384077

Show key headers only | View raw

Kaz Kylheku <433-929-6894@kylheku.com> writes:
> On 2024-03-28, Keith Thompson <Keith.S.Thompson+u@gmail.com> wrote:
>> The warnings I get from gcc are:
>>
>> warning: ISO C forbids conversion of function pointer to object pointer type [-Wpedantic]
>> warning: ISO C forbids conversion of object pointer to function pointer type [-Wpedantic]
>>
>> With -pedantic-errors, these become fatal errors.
>>
>> I disagree with gcc.  ISO C doesn't define the behavior, but it doesn't
>> forbid the conversion.
>
> It's never good for a diagnostic to be stating a blatant falsehood,
> regardless of whether the presence of the diagnostic is a good idea
> or not.
[...]
> I'm actually opening a GCC bugzilla about this right now.

I should have remembered that I reported this as a bug in 2017:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83584

That bug report was closed (inappropriately IMHO) as a duplicate of

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=11234

A commenter on bug #83584 cites the C99 Rationale:
"Even with an explicit cast, it is invalid to convert a function pointer
to an object pointer or a pointer to void, or vice versa."

It's not clear what "invalid" means in that context, and in any case the
Rationale is not normative.

N1570 Annex J 5.7 mentions casting between object pointers and function
pointers as a common extension.

Kaz, I see you've submitted
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114526
which has (inappropriately IMHO) been closed as a duplicate of #11234.

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Medtronic
void Void(void) { Void(); } /* The recursive call of the void */

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Casting the return value of ... gazelle@shell.xmission.com (Kenny McCormack) - 2024-03-28 15:09 +0000
  Re: Casting the return value of ... Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-28 18:16 +0000
    Re: Casting the return value of ... scott@slp53.sl.home (Scott Lurndal) - 2024-03-28 18:53 +0000
      Re: Casting the return value of ... Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-30 10:33 -0700
        Re: Casting the return value of ... scott@slp53.sl.home (Scott Lurndal) - 2024-03-30 19:29 +0000
          Re: Casting the return value of ... Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-03-30 23:05 +0000
            Re: Casting the return value of ... scott@slp53.sl.home (Scott Lurndal) - 2024-03-30 23:25 +0000
            Re: Casting the return value of ... David Brown <david.brown@hesbynett.no> - 2024-03-31 15:44 +0200
            Re: Casting the return value of ... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-03-31 13:15 -0700
          Re: Casting the return value of ... Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-04-08 23:01 -0700
            Re: Casting the return value of ... David Brown <david.brown@hesbynett.no> - 2024-04-09 10:03 +0200
    Re: Casting the return value of ... Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-28 12:38 -0700
      Re: Casting the return value of ... bart <bc@freeuk.com> - 2024-03-28 20:30 +0000
        Re: Casting the return value of ... Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-28 14:07 -0700
          Re: Casting the return value of ... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-03-28 14:15 -0700
          Re: Casting the return value of ... Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-28 21:44 +0000
            Re: Casting the return value of ... Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-28 22:01 +0000
              Re: Casting the return value of ... Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-28 22:33 +0000
                Re: Casting the return value of ... Michael S <already5chosen@yahoo.com> - 2024-03-29 15:53 +0200
                gcc Bugzilla search (was: Casting the return value of ...) Michael S <already5chosen@yahoo.com> - 2024-03-29 16:01 +0200
                Re: gcc Bugzilla search David Brown <david.brown@hesbynett.no> - 2024-03-29 17:00 +0100
            Re: Casting the return value of ... Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-28 15:37 -0700
            Re: Casting the return value of ... Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-06-07 21:23 -0700
          Re: Casting the return value of ... David Brown <david.brown@hesbynett.no> - 2024-03-29 14:06 +0100
            Re: Casting the return value of ... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-03-29 15:46 -0700
        Re: Casting the return value of ... David Brown <david.brown@hesbynett.no> - 2024-03-29 13:58 +0100
          Re: Casting the return value of ... bart <bc@freeuk.com> - 2024-03-29 13:32 +0000
            Re: Casting the return value of ... David Brown <david.brown@hesbynett.no> - 2024-03-29 17:10 +0100
            Re: Casting the return value of ... Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-30 02:32 -0700
              Re: Casting the return value of ... bart <bc@freeuk.com> - 2024-03-30 11:14 +0000
                Re: Casting the return value of ... Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-04-08 23:41 -0700
  Re: Casting the return value of ... Andrey Tarasevich <andreytarasevich@hotmail.com> - 2024-03-28 21:41 -0700
    Re: Casting the return value of ... Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-28 22:02 -0700
  Re: Casting the return value of ... Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-29 15:52 -0700

csiph-web