On Mon, Apr 22, 2019 at 11:11:47PM +0200, U.Mutlu wrote:
> is there a way to suppress a gcc compiler warning locally inside a macro
> code?
>
> #include <stddef.h> // size_t
> #include <strings.h> // ffs()
>
> #define bitsizeof(type, member) \
> ({ type t; \
> t.member = ~0u; /* compiler warning -Woverflow happens */ \
> const size_t rc = ffs(t.member + 1); \
> !rc ? sizeof(unsigned) * 8 : rc - 1; \
> })
~0U does not work correctly for types bigger than int (but neither will
ffs, or that sizeof, and that 8 is not very portable either).
If you write -1 instead, everything just works.
Segher
