On Fri, Feb 7, 2020 at 12:13 PM Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
>
> In addition to this patch I've tried:
> +#define __const_ilog2(n, unique_n) ({ \
> + typeof(n) unique_n = (n); \
Yeah, as you found out, this doesn't work for the case of having
global initializers or things like array sizes.
Which people do do - often nor directly, but through various size macros.
It's annoying, but one of the failures of C is having a nice form of
compile-time constant handling where you can do slightly smarter
arithmetic. The definition of a "const expression" is very very
limited, and hurts us exactly for the array declaration and constant
initializer case.
Oh well.
Linus
