Messages in this thread | | | Date | Tue, 01 Aug 2006 11:45:53 +0159 | From | Jiri Slaby <> | Subject | Re: do { } while (0) question |
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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/
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