On Thu, Feb 28, 2019 at 3:05 PM Joe Perches <joe@xxxxxxxxxxx> wrote: > > On Thu, 2019-02-28 at 14:23 -0800, Jon Flatley wrote: > > Thanks for the patch and comments. > > > > On Thu, Feb 28, 2019 at 1:53 PM Joe Perches <joe@xxxxxxxxxxx> wrote: > > > On Thu, 2019-02-28 at 12:24 +0000, Louis Taylor wrote: > > > > When compiling with -Wformat, clang warns: > > > > ./include/linux/usb/wusb.h:245:5: warning: format specifies type > > > > 'unsigned short' but the argument has type 'u8' (aka 'unsigned char') > > > > [-Wformat] > > > > ckhdid->data[0], ckhdid->data[1], > > > > ^~~~~~~~~~~~~~~ > > > > > > I think the message is somewhat misguided as all the > > > vararg arguments have implicit integer promotions. > > > > That's a fair point, but Clang checks the arguments against their > > format specifier before they're promoted when using -Wformat. > > Perhaps clang could be a bit more verbose if > checking signed types emitted as unsigned or > unsigned types emitted as signed instead. It is a little strange that clang warns when the length specifier doesn't match but not when an unsigned specifier is used for a signed value and vice versa. > > > When > > considering integer promotions it's difficult to say if this is > > "wrong", > > I didn't write "wrong", I wrote misguided. Apologies for my poor wording. I meant "wrong" in the sense that it's unclear if an improper length specifier is deserving of a warning. After all GCC doesn't warn for incorrect length specifiers, and as you pointed out Clang doesn't pay attention to if the specifier expects a signed or unsigned value. Cheers, Jon
