lkml.org 
[lkml]   [2006]   [Aug]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: do { } while (0) question
Peter Zijlstra wrote:
> On Tue, 2006-08-01 at 02:03 -0700, Hua Zhong wrote:
>>> #if KILLER == 1
>>> #define MACRO
>>> #else
>>> #define MACRO do { } while (0)
>>> #endif
>>>
>>> {
>>> if (some_condition)
>>> MACRO
>>>
>>> if_this_is_not_called_you_loose_your_data();
>>> }
>>>
>>> How do you want to define KILLER, 0 or 1? I personally choose 0.
>> Really? Does it compile?
>
> No, and that is the whole point.
>
> The empty 'do {} while (0)' makes the missing semicolon a syntax error.

Bulls^WNope, it was a bad example (we don't want to break the compilation, just
not want to emit a warn or an err).

I can't emit an error with the thing like that, only a warning, but we are not
using -Werror to get err from a warn. Thing such this would emit empty-statement
warn if define KILLER as 1:
#if KILLER == 1
#define MACRO
#else
#define MACRO do { } while (0)
#endif

{
if (some_condition)
MACRO;
else
do_something();
}

regards,
--
<a href="http://www.fi.muni.cz/~xslaby/">Jiri Slaby</a>
faculty of informatics, masaryk university, brno, cz
e-mail: jirislaby gmail com, gpg pubkey fingerprint:
B674 9967 0407 CE62 ACC8 22A0 32CC 55C3 39D4 7A7E
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-08-01 11:49    [W:0.111 / U:0.064 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site