Re: [PATCH 0/3] ASoC: Clean-up W=1 build warnings​ - part3

[Pierre-Louis Bossart]

On 7/7/20 2:39 PM, Jerome Brunet wrote:
> 
> On Tue 07 Jul 2020 at 21:23, Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com> wrote:
> 
>> This is a much smaller set of cleanups, all related to warnings thrown
>> by the use of GENMASK() with an unsigned variable. I just made the
>> warning go away but I wonder if there's a better fix in the definition
>> of GENMASK() itself?
> 
> Looking at the patch I was going to ask the same thing.
> It does not make much sense to me to force GENMASK arguments to be
> integer (instead of unsigned integer) to then check there are positive ...

Agree, it's just that the following macro isn't exactly simple to change:

#define GENMASK_INPUT_CHECK(h, l) \
	(BUILD_BUG_ON_ZERO(__builtin_choose_expr( \
		__builtin_constant_p((l) > (h)), (l) > (h), 0)))

I couldn't find a means to avoid the comparison.

I just realized this is a fairly recent addition in 295bcca84916 
('linux/bits.h: add compile time sanity check of GENMASK inputs'), 
adding the author Rikard Falkeborn in CC:

include/linux/bits.h:26:28: warning: comparison of unsigned expression < 
0 is always false [-Wtype-limits]
    26 |   __builtin_constant_p((l) > (h)), (l) > (h), 0)))