On Sun, 2015-05-24 at 09:27 +0200, Nicholas Mc Guire wrote: > On Sat, 23 May 2015, Steven Rostedt wrote: [] > > > - return sum; > > > + return !!sum; > > > > Hmm I wonder if gcc is smart enough to do the above without the need > > for !!? That is, will it turn to !! because the return of the function > > is bool, or does gcc complain about it not being bool without the !!? > > Not a criticism of the patch, just a curiosity. > > > gcc will not complain if you assign a unsigned long to a boolean > as I understand it it is a macro and is not doing any type > checking/promotion at all - so anything can be assigned to a bool > without warning (including double and pointers). > The !! will though always make the type compatible with int so it is > a well defined type atleast as far as __builtin_types_compatible_p() > goes, and !! also makes static code checkers happy (that are maybe not > as smart as gcc) and it does make the intent of sum being treated > as boolean here clear.
6.3.1.2 Boolean type When any scalar value is converted to _Bool, the result is 0 if the value compares equal to 0; otherwise, the result is 1. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
