Date: Sat, 2 Feb 2002 03:22:55 +1100 (EST) From: Bruce Evans <bde@zeta.org.au> To: Mark Murray <mark@grondar.za> Cc: Juha Juntunen <estabur@hotmail.com>, <arch@FreeBSD.ORG> Subject: Re: __P macro question Message-ID: <20020202031144.N3615-100000@gamplex.bde.org> In-Reply-To: <200202011438.g11EbxE98677@greenpeace.grondar.org>
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On Fri, 1 Feb 2002, Mark Murray wrote:
> > ...
> > 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.
>
> So, does this not effectively make a rule, "You will _always_ properly
> prototype functions, and make sure that these proper prototypes are in
> scope before you use (and define) the functions."?
Not quite. You can use lint to find arg mismatches. Even the 90%-finished
lint in FreeBSD is effective compared with unavailable link-time checkers.
Bruce
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