On Thu, Feb 7, 2019 at 9:24 AM Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> wrote: > > On Thu, Feb 7, 2019 at 3:03 AM Nathan Chancellor > <natechancellor@xxxxxxxxx> wrote: > > > > On Wed, Feb 06, 2019 at 09:36:55AM -0800, Nick Desaulniers wrote: > > > On Wed, Feb 6, 2019 at 9:32 AM Jon Flatley <jflat@xxxxxxxxxxxx> wrote: > > > > > > > > On Wed, Feb 6, 2019 at 8:45 AM Nathan Chancellor > > > > <natechancellor@xxxxxxxxx> wrote: > > > > > > > > > > On Tue, Feb 05, 2019 at 05:26:05PM +0900, Masahiro Yamada wrote: > > > > > > On Sat, Feb 2, 2019 at 6:10 AM <jflat@xxxxxxxxxxxx> wrote: > > > > > > > > > > > > > > From: Jon Flatley <jflat@xxxxxxxxxxxx> > > > > > > > > > > > > > > gcc produces format warnings that clang suppresses. To keep behavior > > > > > > > consistent between gcc and clang, don't suppress format warnings in > > > > > > > clang. > > > > > > > > > > > > > > Signed-off-by: Jon Flatley <jflat@xxxxxxxxxxxx> > > > > > > > --- > > > > > > > > > > > > Applied to linux-kbuild. > > > > > > Thanks. > > > > > > > > > > > > > > > > > > > > > > Hi Jon and Masahiro, > > > > > > > > > > Just as a heads up, this introduces a ton of warnings (duh). Isn't the > > > > > typical plan behind turning on warnings that were disabled to build with > > > > > 'W=', fix them all, then turn them on so as not to pollute the build? > > > > > > > > > > Log file: https://gist.github.com/443db156e56cd3c0f6b21d9d77728d80 > > > > > > Oh boy, that's a lot. Too many to fix quickly IMO. > > > > > > > > > > > > > Note a big chunk of them come from one scnprintf call in > > > > > include/linux/usb/wusb.h but still, there are many other warnings that > > > > > make quite a bit of noise. Some seem relatively easy to fix, which I > > > > > suppose I will try to tackle soon. > > > > > > > > > > Thanks, > > > > > Nathan > > > > > > > > > > > > > Hi Nathan, > > > > > > > > This was definitely not my intention. > > > > I noticed the added warnings this morning and was considering calling > > > > for a revert on this patch. > > > > > > > > The intent was to match the behavior of gcc, as it has -Wformat enabled. > > > > It was rather naive of me to assume the behavior of -Wformat would be > > > > the same in both gcc and clang. > > > > Indeed, it seems gcc is more permissive about what format > > > > substitutions it allows. > > > > > > > > My guess is that it has something to do with how the compilers > > internally handle certain specifier promotions (GCC probably just > > silently ignores the 'h' part of the specifier whereas Clang warns) but > > I didn't do any actual research into the matter. Probably should before > > looking into all of the warnings :) > > > > > > For example passing int to the "%hu" format specifier is fine in gcc > > > > under -Wformat but produces a warning in clang. > > > > Maybe this was the motivation for adding -Wno-format to clang in the > > > > first place. > > > > > > Sorry, I'm late to this thread. What is it reverting; who authored > > > the original patch? Was it mka@xxxxxxxxxxxx? > > > > > > > This patch is turning on '-Wformat' for Clang, which was disabled in > > commit 3d3d6b847420 ("kbuild: LLVMLinux: Adapt warnings for compilation > > with clang"). > > > > > > This difference is puzzling to me, and I wonder if it's by design. > > > > > > Probably; internally let's sync up with the Clang devs to understand > > > this difference more. > > > > > > > Yes, I do think it would be a good idea to turn this on eventually but > > it'd be wise to understand why Clang emits a warning but GCC doesn't. > > > > > > > > > > Considering the whole point of this patch was to sync up this behavior > > > > between gcc and clang I am OK with reverting this. > > > > > > Is this patch in -next, or has it already hit mainline? I think it's > > > better to revert, then start upstreaming fixes, then re-land it once > > > we're warning free. > > > > > > > It's in linux-kbuild/kbuild, it hasn't hit -next yet. > > > Right, it is just staying in my branch. > I will drop it. > > > I should have tested this carefully. Sorry. BTW, it would be nice if kbuild test robot could test building with clang ... -- Best Regards Masahiro Yamada
