On Fri, Dec 5, 2025 at 1:53 PM Jorge Marques [off-list ref] wrote:

On Fri, Dec 05, 2025 at 12:21:31AM +0200, Andy Shevchenko wrote:

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On Thu, Dec 4, 2025 at 11:38 PM Jorge Marques [off-list ref] wrote:

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On Thu, Nov 27, 2025 at 11:20:54AM +0200, Andy Shevchenko wrote:

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On Wed, Nov 26, 2025 at 04:55:41PM +0100, Jorge Marques wrote:

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On Mon, Nov 24, 2025 at 12:40:37PM +0200, Andy Shevchenko wrote:

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On Mon, Nov 24, 2025 at 10:18:08AM +0100, Jorge Marques wrote:

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+       return reg_val == AD4062_GP_STATIC_HIGH ? 1 : 0;

  return !!(reg_val == AD4062_GP_STATIC_HIGH);

also will work.

    return reg_val == AD4062_GP_STATIC_HIGH;

Hmm... This will include implicit bool->int. The !! guarantees values 0 or 1,
but I don't remember about implicit bool->int case.

quoted

I don't think the implicit bool->int is an issue, grepping `return .* == .*;`
matches a few methods that return int.

Yes, the Q here is the value of true _always_ be promoted to 1?

The relational operator result has type int (c99 6.5.9 Equality
operators); and when any scalar value is converted to _Bool, the result
is 0 if the value compares equal to 0; otherwise, the result is 1 (c99
6.3.1.2).
https://www.dii.uchile.cl/~daespino/files/Iso_C_1999_definition.pdf

Okay, thanks for checking this!
So, let's go with a simplified variant then.

No conversion warnings even when forcing _Bool type.
There are many usages like this, for example:

drivers/iio/accel/adxl313_core.c @ int adxl313_is_act_inact_ac()
drivers/iio/light/opt4060.c @ int opt4060_read_event_config()
drivers/iio/light/tsl2772.c @ int tsl2772_device_id_verify()
lib/zstd/compress/zstd_fast.c @ int ZSTD_match4Found_branch()

I cannot find many legitimate usage of relational operator with the
double negation.
  git ls-files | xargs grep -s 'return !!' | grep '=='

-- 
With Best Regards,
Andy Shevchenko