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    SubjectRe: [PATCH] kbuild, LLVMLinux: Don't suppress format warnings
    On Wed, Feb 6, 2019 at 9:32 AM Jon Flatley <jflat@chromium.org> wrote:
    >
    > On Wed, Feb 6, 2019 at 8:45 AM Nathan Chancellor
    > <natechancellor@gmail.com> wrote:
    > >
    > > On Tue, Feb 05, 2019 at 05:26:05PM +0900, Masahiro Yamada wrote:
    > > > On Sat, Feb 2, 2019 at 6:10 AM <jflat@chromium.org> wrote:
    > > > >
    > > > > From: Jon Flatley <jflat@chromium.org>
    > > > >
    > > > > 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@chromium.org>
    > > > > ---
    > > >
    > > > 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.
    >
    > 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@chromium.org?

    > 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.

    >
    > 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.

    --
    Thanks,
    ~Nick Desaulniers

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