Re: function declaration without args no longer works

From	John Forkosh <forkosh@panix.com>
Newsgroups	comp.lang.c
Subject	Re: function declaration without args no longer works
Date	2026-04-26 16:50 +0000
Organization	PANIX Public Access Internet and UNIX, NYC
Message-ID	<10slfog$f5i$1@reader1.panix.com> (permalink)
References	<10sl5na$5ov$1@reader1.panix.com> <10slbcn$1lho0$3@dont-email.me>

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David Brown <david.brown@hesbynett.no> wrote:
> 
> Prior to C23, declaring "int typer();" was accepted as a "non-prototype" 
> function declaration that gives the return type of the function, but 
> says nothing about the type or number of the arguments.  It has been an 
> obsolescent feature (that is to say, a feature that is expected to be 
> removed in a future version of the standard) since C89.  That is to say, 
> it has been a bad idea to declare "int typer();" this way for the last 
> 25 years.
> 
> In C23, the standards committee /finally/ removed non-prototype function 
> declarations from the language.  Now "int typer();" specifically means 
> that "typer" takes no arguments - it has the same meaning as "int 
> typer(void);".
> 
> gcc 15 now makes C23 (more specifically, gnu23 - C23 with gcc 
> extensions) the default standard for compiling C.
> 
> Personally, I don't thing the C standards committee handled this very 
> well.  I think as soon as C++ standardised no arguments to mean the same 
> as "(void)", the C standards committee should have made "int typer();" 
> declarations a constraint error - requiring "int typer(...);" for 
> unspecified arguments.  Compilers would have continued to accept it, 
> hopefully requiring a flag to prevent warnings or errors, giving people 
> time to modernise their code (as they have done for other outdated K&R C 
> syntaxes).  Allowing "int typer();" again with the meaning of "no 
> arguments", like in C++, could have come later - say, C11.  That would 
> have avoided people getting the kind of issues you are seeing - they 
> would not have written code like that in the first place.
> 
> As for what you should do now, there are two clear options.  One is to 
> update your code to C23 standards (following the suggestion from C90 
> onwards).  That would be the best result, but is likely to be 
> impractical.  The alternative is to do as I believe one should always do 
> when compiling C - specify the standard you want on the gcc command line 
> or CFLAGS.  Use "gcc -std=c17", "gcc -std=gnu99", or whatever suits your 
> code.

Thanks for the detailed reply, David. And I'm pretty sure you're right
that if gcc had issued warnings about that, then I'd likely have changed
my coding habits accordingly. 
-- 
John Forkosh

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function declaration without args no longer works John Forkosh <forkosh@panix.com> - 2026-04-26 13:59 +0000
  Re: function declaration without args no longer works Michael Bäuerle <michael.baeuerle@gmx.net> - 2026-04-26 16:24 +0200
    Re: function declaration without args no longer works John Forkosh <forkosh@panix.com> - 2026-04-26 16:29 +0000
      Re: function declaration without args no longer works John Forkosh <forkosh@panix.com> - 2026-05-04 19:36 +0000
        Re: function declaration without args no longer works Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-05-05 00:15 -0700
          Re: function declaration without args no longer works John Forkosh <forkosh@panix.com> - 2026-05-05 09:10 +0000
            Re: function declaration without args no longer works David Brown <david.brown@hesbynett.no> - 2026-05-05 11:17 +0200
              Re: function declaration without args no longer works John Forkosh <forkosh@panix.com> - 2026-05-05 11:07 +0000
            Re: function declaration without args no longer works Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-05-05 02:24 -0700
              Re: function declaration without args no longer works John Forkosh <forkosh@panix.com> - 2026-05-05 11:20 +0000
              Re: function declaration without args no longer works cross@spitfire.i.gajendra.net (Dan Cross) - 2026-05-05 18:09 +0000
                Re: function declaration without args no longer works John Forkosh <forkosh@panix.com> - 2026-05-07 12:52 +0000
                Re: function declaration without args no longer works cross@spitfire.i.gajendra.net (Dan Cross) - 2026-05-07 14:51 +0000
              Re: function declaration without args no longer works Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-05-06 11:41 +0200
            Re: function declaration without args no longer works Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-05-05 10:03 -0700
              Re: function declaration without args no longer works John Forkosh <forkosh@panix.com> - 2026-05-07 12:35 +0000
                Re: function declaration without args no longer works Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-05-08 07:36 -0700
                Re: function declaration without args no longer works antispam@fricas.org (Waldek Hebisch) - 2026-05-08 18:39 +0000
  Re: function declaration without args no longer works richard@cogsci.ed.ac.uk (Richard Tobin) - 2026-04-26 14:32 +0000
    Re: function declaration without args no longer works John Forkosh <forkosh@panix.com> - 2026-04-26 16:35 +0000
    Re: function declaration without args no longer works Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-29 16:43 -0700
      Re: function declaration without args no longer works David Brown <david.brown@hesbynett.no> - 2026-04-30 08:39 +0200
  Re: function declaration without args no longer works Michael S <already5chosen@yahoo.com> - 2026-04-26 17:50 +0300
    Re: function declaration without args no longer works John Forkosh <forkosh@panix.com> - 2026-04-26 16:39 +0000
      Re: function declaration without args no longer works Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-27 00:30 +0000
        Re: function declaration without args no longer works David Brown <david.brown@hesbynett.no> - 2026-04-27 08:30 +0200
          Re: function declaration without args no longer works John Forkosh <forkosh@panix.com> - 2026-04-28 07:02 +0000
            Re: function declaration without args no longer works David Brown <david.brown@hesbynett.no> - 2026-04-28 10:16 +0200
              Re: function declaration without args no longer works antispam@fricas.org (Waldek Hebisch) - 2026-04-28 15:33 +0000
                Re: function declaration without args no longer works David Brown <david.brown@hesbynett.no> - 2026-04-28 20:24 +0200
                Re: function declaration without args no longer works antispam@fricas.org (Waldek Hebisch) - 2026-04-28 20:22 +0000
              Re: function declaration without args no longer works John Forkosh <forkosh@panix.com> - 2026-04-29 06:22 +0000
                Re: function declaration without args no longer works David Brown <david.brown@hesbynett.no> - 2026-04-29 09:15 +0200
                Re: function declaration without args no longer works Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-29 10:06 +0200
                Re: function declaration without args no longer works Michael S <already5chosen@yahoo.com> - 2026-04-29 11:25 +0300
                Re: function declaration without args no longer works David Brown <david.brown@hesbynett.no> - 2026-04-29 11:26 +0200
                Re: function declaration without args no longer works James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-04-29 20:07 -0400
                Re: function declaration without args no longer works Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-30 00:14 +0000
                Re: function declaration without args no longer works "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-04-29 17:57 -0700
                Re: function declaration without args no longer works Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-30 03:09 +0200
                Re: function declaration without args no longer works Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-30 00:48 -0700
                Re: function declaration without args no longer works "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-04-30 20:18 -0700
                Re: function declaration without args no longer works Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-01 04:12 +0000
                Re: function declaration without args no longer works "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-04-30 23:29 -0700
                Re: function declaration without args no longer works Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-05-01 19:31 +0200
                Re: function declaration without args no longer works James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-05-01 13:49 -0400
                Re: function declaration without args no longer works "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-05-01 12:49 -0700
                Re: function declaration without args no longer works Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-01 22:31 +0000
                Re: function declaration without args no longer works Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-02 00:13 +0000
                Re: function declaration without args no longer works "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-05-01 19:27 -0700
                Re: function declaration without args no longer works "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-05-01 19:28 -0700
                Re: function declaration without args no longer works Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-02 03:07 +0000
                Re: function declaration without args no longer works scott@slp53.sl.home (Scott Lurndal) - 2026-05-02 16:16 +0000
                Re: function declaration without args no longer works Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-30 01:39 +0000
                Re: function declaration without args no longer works Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-30 00:38 -0700
                Re: function declaration without args no longer works Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-30 03:07 -0700
                Re: function declaration without args no longer works Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-30 05:54 -0700
                Re: function declaration without args no longer works Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-30 14:32 -0700
                Re: function declaration without args no longer works James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-04-30 09:45 -0400
                Re: function declaration without args no longer works Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-30 12:48 -0700
                Re: function declaration without args no longer works Bart <bc@freeuk.com> - 2026-04-29 11:05 +0100
                Re: function declaration without args no longer works Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-29 16:32 -0700
                Re: function declaration without args no longer works Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-30 01:22 -0700
                Re: function declaration without args no longer works John Forkosh <forkosh@panix.com> - 2026-04-29 10:42 +0000
                Re: function declaration without args no longer works Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-29 14:31 -0700
                Re: function declaration without args no longer works David Brown <david.brown@hesbynett.no> - 2026-04-30 08:42 +0200
                Re: function declaration without args no longer works John Forkosh <forkosh@panix.com> - 2026-04-30 13:17 +0000
                Re: function declaration without args no longer works Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-30 14:40 -0700
                Re: function declaration without args no longer works Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-30 22:14 +0000
                Re: function declaration without args no longer works cross@spitfire.i.gajendra.net (Dan Cross) - 2026-04-29 18:55 +0000
                Re: function declaration without args no longer works Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-29 21:19 +0000
                Re: function declaration without args no longer works Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-29 16:46 -0700
            Re: function declaration without args no longer works Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-28 14:25 +0200
              Re: function declaration without args no longer works cross@spitfire.i.gajendra.net (Dan Cross) - 2026-04-28 13:13 +0000
                Re: function declaration without args no longer works David Brown <david.brown@hesbynett.no> - 2026-04-28 15:48 +0200
                Re: function declaration without args no longer works Bart <bc@freeuk.com> - 2026-04-28 15:05 +0100
                Re: function declaration without args no longer works David Brown <david.brown@hesbynett.no> - 2026-04-28 16:37 +0200
                Re: function declaration without args no longer works Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-28 14:02 -0700
                Re: function declaration without args no longer works David Brown <david.brown@hesbynett.no> - 2026-04-29 09:29 +0200
                Re: function declaration without args no longer works Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-29 02:49 -0700
                Re: function declaration without args no longer works James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-04-29 20:06 -0400
                Re: function declaration without args no longer works Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-29 17:13 -0700
                Re: function declaration without args no longer works Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-30 00:45 +0000
                Re: function declaration without args no longer works James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-04-29 21:11 -0400
                Re: function declaration without args no longer works Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-30 01:40 +0000
                Re: function declaration without args no longer works Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-29 20:09 -0700
                Re: function declaration without args no longer works scott@slp53.sl.home (Scott Lurndal) - 2026-04-30 14:57 +0000
                Re: function declaration without args no longer works cross@spitfire.i.gajendra.net (Dan Cross) - 2026-04-30 15:07 +0000
                Re: function declaration without args no longer works Bart <bc@freeuk.com> - 2026-04-30 16:20 +0100
                Re: function declaration without args no longer works cross@spitfire.i.gajendra.net (Dan Cross) - 2026-04-30 16:10 +0000
                Re: function declaration without args no longer works Bart <bc@freeuk.com> - 2026-04-30 17:48 +0100
                Re: function declaration without args no longer works David Brown <david.brown@hesbynett.no> - 2026-04-30 22:31 +0200
                Re: function declaration without args no longer works Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-30 22:18 +0000
                Re: function declaration without args no longer works Bart <bc@freeuk.com> - 2026-05-01 00:25 +0100
                Re: function declaration without args no longer works cross@spitfire.i.gajendra.net (Dan Cross) - 2026-05-01 00:08 +0000
                Re: function declaration without args no longer works Bart <bc@freeuk.com> - 2026-05-01 01:24 +0100
                Re: function declaration without args no longer works Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-30 17:46 -0700
                Re: function declaration without args no longer works cross@spitfire.i.gajendra.net (Dan Cross) - 2026-05-01 01:55 +0000
                Re: function declaration without args no longer works Bart <bc@freeuk.com> - 2026-05-01 10:48 +0100
                Re: function declaration without args no longer works cross@spitfire.i.gajendra.net (Dan Cross) - 2026-05-01 11:20 +0000
                Re: function declaration without args no longer works "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-04-30 20:23 -0700
                Re: function declaration without args no longer works David Brown <david.brown@hesbynett.no> - 2026-05-01 10:32 +0200
                Re: function declaration without args no longer works Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-30 14:43 -0700
                Re: function declaration without args no longer works cross@spitfire.i.gajendra.net (Dan Cross) - 2026-04-30 22:34 +0000
                Re: function declaration without args no longer works James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-05-01 13:32 -0400
                Re: function declaration without args no longer works scott@slp53.sl.home (Scott Lurndal) - 2026-05-01 18:12 +0000
                Re: function declaration without args no longer works Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-30 03:50 +0200
                Re: function declaration without args no longer works David Brown <david.brown@hesbynett.no> - 2026-04-30 08:52 +0200
                Re: function declaration without args no longer works "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-04-28 14:56 -0700
                Re: function declaration without args no longer works Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-28 15:41 -0700
                Re: function declaration without args no longer works Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-29 21:20 +0000
                Re: function declaration without args no longer works Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-28 17:14 +0200
                Re: function declaration without args no longer works David Brown <david.brown@hesbynett.no> - 2026-04-28 17:31 +0200
                Re: function declaration without args no longer works cross@spitfire.i.gajendra.net (Dan Cross) - 2026-04-28 19:06 +0000
                Re: function declaration without args no longer works David Brown <david.brown@hesbynett.no> - 2026-04-28 21:44 +0200
                Re: function declaration without args no longer works Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-28 17:06 +0200
                Re: function declaration without args no longer works cross@spitfire.i.gajendra.net (Dan Cross) - 2026-04-28 19:23 +0000
  Re: function declaration without args no longer works David Brown <david.brown@hesbynett.no> - 2026-04-26 17:35 +0200
    Re: function declaration without args no longer works John Forkosh <forkosh@panix.com> - 2026-04-26 16:50 +0000
    Re: function declaration without args no longer works Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-26 15:52 -0700
  Re: function declaration without args no longer works Andrey Tarasevich <noone@noone.net> - 2026-04-26 08:38 -0700
    Re: function declaration without args no longer works John Forkosh <forkosh@panix.com> - 2026-04-26 16:56 +0000

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