RE: [PATCH 01/10] compiler.h: add statically_false()

[David Laight <David.Laight@ACULAB.COM>]

From: Vincent Mailhol
> Sent: 02 December 2024 17:33
> 
> From: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
> 
> For completion, add statically_false() which is the equivalent of
> statically_true() except that it will return true only if the input is
> known to be false at compile time.

This is pretty much pointless.
It is just as easy to invert the condition at the call site.

	David

> 
> The == operator is used instead of the ! negation to prevent a
> -Wint-in-bool-context compiler warning when the argument is not a
> boolean. For example:
> 
>   statically_false(var * 0)
> 
> Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
> ---
>  include/linux/compiler.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/include/linux/compiler.h b/include/linux/compiler.h
> index 469a64dd6495fefab2c85ffc279568a657b72660..a2a56a50dd85227a4fdc62236a2710ca37c5ba52 100644
> --- a/include/linux/compiler.h
> +++ b/include/linux/compiler.h
> @@ -314,6 +314,7 @@ static inline void *offset_to_ptr(const int *off)
>   * values to determine that the condition is statically true.
>   */
>  #define statically_true(x) (__builtin_constant_p(x) && (x))
> +#define statically_false(x) (__builtin_constant_p(x) && (x) == 0)
> 
>  /*
>   * This is needed in functions which generate the stack canary, see
> 
> --
> 2.45.2
> 
> 

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