Messages in this thread | | | From | Bjørn Mork <> | Subject | Re: [PATCH] checkpatch: Warn on comparisons to true and false | Date | Thu, 11 Apr 2013 13:56:54 +0200 |
| |
Dave Jones <davej@redhat.com> writes: > On Wed, Apr 10, 2013 at 03:57:51PM -0700, Andrew Morton wrote: > > On Tue, 09 Apr 2013 20:17:14 -0700 Joe Perches <joe@perches.com> wrote: > > > > > Comparisons of A to true and false are better written > > > as A and !A. > > > > > > Bleat a message on use. > > > > hm. I'm counting around 1,100 instances of "== true" and "== false". > > > > That's a lot of people to shout at. Is it really worthwhile? > > "foo==true" is a bit of a waste of space but I can't say that I find it > > terribly offensive. > > It would be interesting to see how many people have historically screwed > up and used (!a) when they mean (a) and vice versa, versus spelling > it out longform. I'd be surprised if the results weren't skewed > in favour of the more verbose form.
You have to consider that it is still possible to reverse the operator even if spelling it out, so you don't really gain anything:
bjorn@nemi:/usr/local/src/git/linux$ git grep -E '!=\s*(true|false)'|wc -l 63
and since most of these compare to true, they are also at risk wrt integers:
bjorn@nemi:/usr/local/src/git/linux$ git grep -E '!=\s*true'|wc -l 54
Based on a quick look at a few of these I guess they are mostly OK, testing against bool values. But I felt I had to share this little gem which showed up in drivers/gpu/drm/exynos/exynos_drm_vidi.c:
static int vidi_power_on(struct vidi_context *ctx, bool enable) { struct exynos_drm_subdrv *subdrv = &ctx->subdrv; struct device *dev = subdrv->dev;
DRM_DEBUG_KMS("%s\n", __FILE__);
if (enable != false && enable != true) return -EINVAL; ..
That's taking failsafe to the next step :)
Bjørn -- 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/
| |