http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60619
--- Comment #2 from Alexander Kleinsorge <aleks at physik dot tu-berlin.de> --- (In reply to Andrew Pinski from comment #1) > Well your option violates C promotion rules. Basically the warning is there > as some folks don't understand how promotion works in C when it comes to > comparing unsigned and signed integers against each other. > > For equals, most of the time you want bytewise comparison; that is the > implicate cast does not change the bits. While your switch does change the > bits. I understand the promotion rules. Nobody is forced to used this new switch. It gives the fast possibility to see the code as it is written from math perspective. e.g. (-1 != 0xffFFffFFu) even if both bit representation is ~0 What happens in reallity (not enough programming time): (s != u) ==> ((unsigned)s != u) , the typecast is inserted to avoid the warning, not because it is really meant! This could fasten some cases. The sign-warning could still be there (as without new switch). Alex
