Hi Jeff, On Fri, Mar 9, 2018 at 2:24 PM, Jeffrey Walton <noloader@xxxxxxxxx> wrote: > On Fri, Mar 9, 2018 at 8:16 AM, Himanshu Jha > <himanshujha199640@xxxxxxxxx> wrote: >> Hello everyone, >> >> >> I just compiled the kernel by passing "-Wformat-signedness" flag >> >> https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html >> >> -Wformat-signedness: >> If -Wformat is specified, also warn if the format string requires an >> unsigned argument and the argument is signed and vice versa. >> >> Now, the C standard says: >> >> "If a conversion specification is invalid, the behavior is undefined. >> If any argument is >> not the correct type for the corresponding conversion specification, the >> behavior is *undefined*." >> >> For eg: >> >> drivers/iio/trigger/stm32-timer-trigger.c:228:24: warning: format ‘%d’ >> expects argument of type ‘int’, but argument 3 has type ‘unsigned int’ >> [-Wformat=] >> return sprintf(buf, "%d\n", (unsigned int)freq); >> ~^ ~~~~~~~~~~~~~~~~~~ >> %d >> >> What is the rationale for not including/using this flag in the >> HOSTCFLAGS in the Makefile ? > > In the past, it was posited the toolchain should be smart enough to > know when the programmer intended/needed a signed value versus an > unsigned one. Also see > http://linux.derkeiler.com/Mailing-Lists/Kernel/2006-11/msg08325.html. I am not sure this is best example why this flag is not used anymore. I can see that type-limits is being used. It is even a -Werror=type-limits when compiling with W=1. Anyway I see your point, just that the example may be a bit out dated. -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
