From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH net-2.6.24] introduce MAC_FMT/MAC_ARG
Date: Mon, 27 Aug 2007 14:11:50 -0700 (PDT)
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From: Joe Perches <joe@perches.com>
Date: Mon, 27 Aug 2007 13:57:42 -0700

> On Mon, 2007-08-27 at 13:41 -0700, David Miller wrote:
> > From: Johannes Berg <johannes@sipsolutions.net>
> > Date: Mon, 27 Aug 2007 12:54:09 +0200
> > > #define MAC_FMT "%s"
> > > #define MAC_ARG(a) ({char __buf[18]; print_mac(a, __buf); __buf;})
> 
> > I don't think this works.
> 
> $ cat test_fmt.c
> #include <stdio.h>
> #include <stdlib.h>

You're just getting lucky in this test case.

The language does not allow what you are doing, so you're
playing with fire.