From: Joe Perches <joe@perches.com>
To: Andrew Morton <akpm@linux-foundation.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Kees Cook <keescook@chromium.org>,
Martin Kletzander <mkletzan@redhat.com>,
Andy Shevchenko <andy.shevchenko@gmail.com>,
Maurizio Lombardi <mlombard@redhat.com>,
Tejun Heo <tj@kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 04/14] lib/vsprintf.c: expand field_width to 24 bits
Date: Thu, 03 Dec 2015 16:03:02 -0800 [thread overview]
Message-ID: <1449187382.17296.16.camel@perches.com> (raw)
In-Reply-To: <20151203153407.85761faeab07e7c2fed84e81@linux-foundation.org>
On Thu, 2015-12-03 at 15:34 -0800, Andrew Morton wrote:
> I've been fiddling with a BUILD_BUG_ON which works outside functions
> using gcc's __COUNTER__ - something like
>
> #define BBO(expr) typedef char __bbo##__COUNTER__[1-2*(!!expr)]
nit: you need another parenthesis around expr
> BBO(1 == 1);
> BBO(2 == 2);
>
> but that comes out as
>
> typedef char __bbo__COUNTER__[1-2*(!!1 == 1)];
> typedef char __bbo__COUNTER__[1-2*(!!2 == 2)];
>
> instead of
>
> typedef char __bbo0[1-2*(!!1 == 1)];
> typedef char __bbo1[1-2*(!!2 == 2)];
>
> There's some trick here but I've forgotten what it is.
I believe it's something like:
#define __stringify_2(a, b) a##b
#define __stringify2(a, b) __stringify_2(a, b)
#define BBO(expr) typedef char __stringify2(bbo, __COUNTER__)[1 - 2*(!!(expr))]
next prev parent reply other threads:[~2015-12-04 0:03 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-03 20:50 [PATCH v3 00/14] printf stuff for 4.5 Rasmus Villemoes
2015-12-03 20:51 ` [PATCH v3 01/14] lib/vsprintf.c: pull out padding code from dentry_name() Rasmus Villemoes
2015-12-03 20:51 ` [PATCH v3 02/14] lib/vsprintf.c: move string() below widen_string() Rasmus Villemoes
2015-12-03 20:51 ` [PATCH v3 03/14] lib/vsprintf.c: eliminate potential race in string() Rasmus Villemoes
2015-12-03 20:51 ` [PATCH v3 04/14] lib/vsprintf.c: expand field_width to 24 bits Rasmus Villemoes
2015-12-03 20:54 ` Joe Perches
2015-12-03 21:28 ` Andy Shevchenko
2015-12-03 23:34 ` Andrew Morton
2015-12-04 0:03 ` Joe Perches [this message]
2015-12-04 8:59 ` Rasmus Villemoes
2015-12-04 9:02 ` Rasmus Villemoes
2015-12-03 23:41 ` Joe Perches
2015-12-03 20:51 ` [PATCH v3 05/14] lib/vsprintf.c: help gcc make number() smaller Rasmus Villemoes
2015-12-03 20:51 ` [PATCH v3 06/14] lib/vsprintf.c: warn about too large precisions and field widths Rasmus Villemoes
2015-12-03 20:51 ` [PATCH v3 07/14] lib/kasprintf.c: add sanity check to kvasprintf Rasmus Villemoes
2015-12-03 20:51 ` [PATCH v3 08/14] lib/test_printf.c: don't BUG Rasmus Villemoes
2015-12-03 20:51 ` [PATCH v3 09/14] lib/test_printf.c: check for out-of-bound writes Rasmus Villemoes
2015-12-03 20:51 ` [PATCH v3 10/14] lib/test_printf.c: test precision quirks Rasmus Villemoes
2015-12-03 20:51 ` [PATCH v3 11/14] lib/test_printf.c: add a few number() tests Rasmus Villemoes
2015-12-03 20:51 ` [PATCH v3 12/14] lib/test_printf.c: account for kvasprintf tests Rasmus Villemoes
2015-12-03 20:51 ` [PATCH v3 13/14] lib/test_printf.c: add test for large bitmaps Rasmus Villemoes
2015-12-03 20:51 ` [PATCH v3 14/14] lib/test_printf.c: test dentry printing Rasmus Villemoes
2015-12-04 0:19 ` Andrew Morton
2015-12-04 8:16 ` Rasmus Villemoes
2015-12-04 8:46 ` Andrew Morton
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