Date: Sat, 2 Feb 2002 01:31:23 +1100 (EST) From: Bruce Evans <bde@zeta.org.au> To: Juha Juntunen <estabur@hotmail.com> Cc: <arch@FreeBSD.ORG> Subject: Re: __P macro question Message-ID: <20020202012011.U3304-100000@gamplex.bde.org> In-Reply-To: <F81KDSpCW4uFWjkOTGk0000065d@hotmail.com>
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On Fri, 1 Feb 2002, Juha Juntunen wrote:
> >>>static int sendfile __P((struct printer *pp, int type, char *file,
> >>> int format));
> >>>
> >>>for a procedure declaration of:
> >>> static int
> >>> sendfile(pp, type, file, format)
> >>> struct printer *pp;
> >>> int type;
> >>> char *file;
> >>> char format;
> >>> {
> >>
> >>That's *EXCATLY* why I'm converting the old, but still legal in c89,
> >>style to new style. You get warnings that you didn't get before.
> >
> >The compiler is broken, if it accepts the second when the
> >first prototype is in scope.
> >
> >It's a broken compiler, period.
>
> How is the compiler broken, question mark.
>
> Are you perhaps objecting to the type of the last parameter
> ("int format" vs "char format")? Please see Ansi Classic, chapter
> "3.5.4.3 Function declarators (including prototypes)", in particular
> page 69 lines 19-22. In C99, 6.7.5.3 paragraph #11 seems to apply
> similarly.
Right. I don't trust anyone who is not familiar with this point to
globally remove __P.
People removing __P should also be familiar with the gcc conterpoint:
void foo(char); /* Wrong; should be "void foo(int);". */
void foo(c) char c; {}
gives undefined behaviour in Standard C, but gcc defines its behaviour
to be do-what-naive-programmer-expects. This is only safe provided the
wrong prototype for foo() is always in scope before foo() is called;
otherwise foo() is sometimes passed an int and sometimes a char, but
foo() expects to be passed either an int or a char depending on whether
the wrong prototype is in scope for the function body.
Bruce
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