Path: utzoo!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!mcgill-vision!snorkelwacker!mit-eddie!wuarchive!udel!haven!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.std.c
Subject: Re: prototypes required ?
Keywords: printf stdargs prototypes
Message-ID: <14195@smoke.BRL.MIL>
Date: 19 Oct 90 15:09:27 GMT
References: <4026@otis.oakhill.UUCP> <14164@smoke.BRL.MIL> <2150@lupine.NCD.COM>
Organization: U.S. Army Ballistic Research Laboratory, APG, MD.
Lines: 33

In article <2150@lupine.NCD.COM> rfg@NCD.COM (Ron Guilmette) writes:
>Now please excuse my almost total ignorance regarding the x3j11 requirements
>regarding the contents of include files, but I don't immediately see where
>(in 4.9.1) it says (explicitly) what function are required to be declared
>within <stdio.h>.  Are all of the function listed in 4.9.4 thru 4.9.10
>required to have declarations within <stdio.h>?  If so, are they required
>to have prototyped declarations?  Non-prototyped?  Either?

Section 4.1.2.1 says: "Each header declares or defines all identifiers
listed in its associated section, ..."  While it does not explicitly
require that prototypes be used, a strictly conforming program must
assume that the standard headers might use prototypes.  Otherwise, it
would be depending on undefined behavior.

Of course it is expected that high-quality implementations WOULD use
prototypes in the standard headers, because that would produce better
diagnostic capabilities due to being able to check argument types.

>... put a declaration like the following in it:
>	int vfprintf (FILE *, const char *, void *);
>I tried changing the last formal type to (a more correct) `va_list', ...

<stdio.h> must not rely on the inclusion of <stdarg.h> nor include
<stdarg.h> itself.  The v*() declarations in <stdio.h> should have
the appropriate type directly used in the declaration (i.e. not via
a typedef), or else they should use an implementation-reserved
identifier for the typedef.  For example:
	/* <stdio.h> example implementation (partial) */
	#include <sys/cdefs>	/* defines __va_list etc. */
	/* [FILE defined here] */
	int vfprintf(FILE *, const char *, __va_list);
With this technique, the same file (<sys/cdefs>) can be used in the
implementation of both <stdio.h> and <stdarg.h>.