Re: [PATCH v2 2/6] iio: adc: ad4130: Fix comparison of channel setups

[David Lechner <dlechner@baylibre.com>]

On 2/18/25 12:31 PM, Uwe Kleine-König wrote:
> Checking the binary representation of two structs (of the same type)
> for equality doesn't have the same semantic as comparing all members for
> equality. The former might find a difference where the latter doesn't in
> the presence of padding or when ambiguous types like float or bool are
> involved. (Floats typically have different representations for single
> values, like -0.0 vs +0.0, or 0.5 * 2² vs 0.25 * 2³. The type bool has
> at least 8 bits and the raw values 1 and 2 (probably) both evaluate to
> true, but memcmp finds a difference.)
> 
> When searching for a channel that already has the configuration we need,
> the comparison by member is the one that is needed.
> 
> Convert the comparison accordingly to compare the members one after
> another. Also add a BUILD_BUG guard to (somewhat) ensure that when

Now it is static_assert instead of BUILD_BUG.

> struct ad4130_setup_info is expanded, the comparison is adapted, too.
> 
> Fixes: 62094060cf3a ("iio: adc: ad4130: add AD4130 driver")
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
> ---