From owner-freebsd-hackers  Wed May 21 12:21:06 1997
Return-Path: <owner-hackers>
Received: (from root@localhost)
          by hub.freebsd.org (8.8.5/8.8.5) id MAA29856
          for hackers-outgoing; Wed, 21 May 1997 12:21:06 -0700 (PDT)
Received: from awfulhak.demon.co.uk (awfulhak.demon.co.uk [158.152.17.1])
          by hub.freebsd.org (8.8.5/8.8.5) with ESMTP id MAA29827
          for <hackers@FreeBSD.ORG>; Wed, 21 May 1997 12:20:40 -0700 (PDT)
Received: from awfulhak.demon.co.uk (localhost [127.0.0.1])
	by awfulhak.demon.co.uk (8.8.5/8.8.5) with ESMTP id UAA18664;
	Wed, 21 May 1997 20:14:47 +0100 (BST)
Message-Id: <199705211914.UAA18664@awfulhak.demon.co.uk>
X-Mailer: exmh version 1.6.9 8/22/96
To: Michael Smith <msmith@atrad.adelaide.edu.au>
cc: jgrosch@superior.mooseriver.com, hackers@FreeBSD.ORG
Subject: Re: Porting question 
In-reply-to: Your message of "Wed, 21 May 1997 15:33:07 +0930."
             <199705210603.PAA09769@genesis.atrad.adelaide.edu.au> 
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Date: Wed, 21 May 1997 20:14:47 +0100
From: Brian Somers <brian@awfulhak.org>
Sender: owner-hackers@FreeBSD.ORG
X-Loop: FreeBSD.org
Precedence: bulk

> Josef Grosch stands accused of saying:
> > I know this issue has been beat to death several times before BUT.....
> > 
> > I am porting a piece of code to FreeBSD and gcc bitches about this;
> > 
> >     extern char* sys_errlist[];
> > 
> > Now the fast way to handle this is;
> > 
> >     #ifndef  __FreeBSD__
> >     extern char* sys_errlist[];
> >     #endif
> > 
> > But this is very non-portable.  Any suggestions as the correct way to
> > handle this would be helpful.
> 
> Traditional is 
> 
> #ifndef HAVE_SYS_ERRLIST
> extern char* sys_errlist[];
> #endif
> 
> or, if you can guarantee that <sys/param.h> has been included, you can
> test the BSD macro.

Hmm, of course you mean extern const char * const sys_errlist[].  If
this prototype is used, it doesn't matter if you've included stdio.

If it conflicts with anything, that something is broken - a poor
reason for breaking your own code IMO.

Maybe gcc should allow the "strengthening" of a prototype - so
saying

    extern char *sys_errlist[];
    extern const char *sys_errlist[];
    extern const char * const sys_errlist[];

is ok (probably warned about under -pedantic or with its own -W),
but

    extern const char *sys_errlist[];
    extern char *sys_errlist[];

is an error.  That way, people can successfully "overload"
include files with others that say "#include "/usr/include/..."
(there's a #include_next or something somewhere in gcc too isn't
there) and then "fix" things like this (rather than having to
#define them away before #including the file).

Look at it like defaulting arguments in C++ - you can get stricter
everytime you prototype a function.

> > Josef Grosch           | Another day closer to a |    FreeBSD 2.2.1
> 
> -- 
> ]] Mike Smith, Software Engineer        msmith@gsoft.com.au             [[
> ]] Genesis Software                     genesis@gsoft.com.au            [[
> ]] High-speed data acquisition and      (GSM mobile)     0411-222-496   [[
> ]] realtime instrument control.         (ph)          +61-8-8267-3493   [[
> ]] Unix hardware collector.             "Where are your PEZ?" The Tick  [[

-- 
Brian <brian@awfulhak.org>, <brian@freebsd.org>
      <http://www.awfulhak.org>
Don't _EVER_ lose your sense of humour....