Messages in this thread | | | Subject | Re: [PATCH] Make is_signed_type() simpler | From | Rasmus Villemoes <> | Date | Mon, 30 Sep 2019 08:16:48 +0200 |
| |
On 29/09/2019 23.09, Alexey Dobriyan wrote: > On Sun, Sep 29, 2019 at 10:21:48PM +0200, Rasmus Villemoes wrote: >> On 29/09/2019 22.06, Alexey Dobriyan wrote: >>> * Simply compare -1 with 0, >>> * Drop unnecessary parenthesis sets >>> >>> -#define is_signed_type(type) (((type)(-1)) < (type)1) >>> +#define is_signed_type(type) ((type)-1 < 0) >> >> NAK. I wrote it that way to avoid -Wtautological-compare when type is >> unsigned. > > Was is W=1? > > godbolt doesn't show it with just -Wall > > https://godbolt.org/z/kCA7mm > > And the warning which found i915 case is -Wextra not -Wtautological-compare. >
Yeah, it's usually disabled/not enabled in the kernel. I did most of the prototyping/testing in userspace with my default Cflags, and decided to keep it this way in case somebody copy-pastes it to a code base that does enable -Wtautological-compare. I see it's been copy-pasted to tools/, who knows what they do. IMO, "it may be copy-pasted" would not be valid reason for a transform the other way, but I really don't see a reason for changing it now. Especially since it seems to require some tree-wide adaptation.
Rasmus
| |