Segher Boessenkool wrote on 04/23/2019 06:02 PM:
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.
Ok, now using -1 for ~0u, and CHAR_BIT for 8. But what's your objection regarding sizeof? Thx
