Re: [PATCH] eal: silence -Wconstant-logical-operand in RTE_IS_POWER_OF_2

[Bruce Richardson <bruce.richardson@intel.com>]

On Mon, May 18, 2026 at 09:33:31AM -0700, Stephen Hemminger wrote:
> Newer GCC warns when a non-boolean constant is an operand of &&, which
> trips whenever RTE_IS_POWER_OF_2 is used in a static_assert with a
> power-of-two literal. Make the zero check explicit.
> 
> Fixes: 7c872b96983a ("hash: validate hash bucket entries while compiling")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>

One further suggestion below, since you are changing this.
> ---
>  lib/eal/include/rte_bitops.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/eal/include/rte_bitops.h b/lib/eal/include/rte_bitops.h
> index aa6ac73abb..d2719ecd5e 100644
> --- a/lib/eal/include/rte_bitops.h
> +++ b/lib/eal/include/rte_bitops.h
> @@ -1299,7 +1299,7 @@ rte_fls_u64(uint64_t x)
>  /**
>   * Macro to return 1 if n is a power of 2, 0 otherwise
>   */
> -#define RTE_IS_POWER_OF_2(n) ((n) && !(((n) - 1) & (n)))
> +#define RTE_IS_POWER_OF_2(n) ((n) != 0 && !(((n) - 1) & (n)))
>  

I'd also suggest changing the second part of the && to match, changing the
"!" for explicit "== 0":

#define RTE_IS_POWER_OF_2(n) ((n) != 0 && (((n) - 1) & (n)) == 0)

>  /**
>   * Returns true if n is a power of 2
> -- 
> 2.53.0
>