Re: [PATCH] iio: bmi323: mark bmi323_ext_reg_savestate as maybe unused

[Su Hui]

On 2024/10/12 17:11, Julia Lawall wrote:
> On Sat, 12 Oct 2024, Su Hui wrote:
>
> > When running 'make CC=clang drivers/iio/imu/bmi323/bmi323_core.o', there
> > is a clang warning as follows:
> >
> > drivers/iio/imu/bmi323/bmi323_core.c:133:27: error:
> > variable 'bmi323_ext_reg_savestate' is not needed and will not be emitted
> > [-Werror,-Wunneeded-internal-declaration]
> >    133 | static const unsigned int bmi323_ext_reg_savestate[] = {
> >        |                           ^~~~~~~~~~~~~~~~~~~~~~~~
> > 1 error generated.
> >
> > Mark bmi323_ext_reg_savestate as __maybe_unused to silent this warning.
> Why might it be unused?

We only use the size of 'bmi323_ext_reg_savestate[]' not it's value, as 
shown below :

$ git grep  bmi323_ext_reg_savest drivers/iio/imu/
drivers/iio/imu/bmi323/bmi323_core.c:static const unsigned int 
bmi323_ext_reg_savestate[] = {
drivers/iio/imu/bmi323/bmi323_core.c:   unsigned int 
ext_reg_settings[ARRAY_SIZE(bmi323_ext_reg_savestate)];
drivers/iio/imu/bmi323/bmi323_core.c:   for (unsigned int i = 0; i < 
ARRAY_SIZE(bmi323_ext_reg_savestate); i++) {
drivers/iio/imu/bmi323/bmi323_core.c:   for (unsigned int i = 0; i < 
ARRAY_SIZE(bmi323_ext_reg_savestate); i++) {

And I find some solutions use __maybe_unused to silent this warning. 
Like this one:
3034983db355 ("drm/amdgpu: Mark mmhub_v1_8_mmea_err_status_reg as 
__maybe_unused")

Mark this variable to __maybe_unused is  to eliminate clang's warning.
Perhaps it is also possible to mark it as _used:).

Su Hui