linux-kernel - Re: mainline build failure for arm64 allmodconfig with clang

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Message-ID: <CAKwvOdkUc=8DD938in5PMeGYAn3PEWp4E_W8qEHq_y7Smy8+mQ@mail.gmail.com>
Date:   Thu, 11 Aug 2022 15:04:29 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Joe Perches <joe@...ches.com>,
        Nathan Chancellor <nathan@...nel.org>,
        "Sudip Mukherjee (Codethink)" <sudipm.mukherjee@...il.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux <llvm@...ts.linux.dev>,
        Justin Stitt <justinstitt@...gle.com>
Subject: Re: mainline build failure for arm64 allmodconfig with clang

On Thu, Aug 11, 2022 at 12:35 PM Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
> On Thu, Aug 11, 2022 at 11:39 AM Nick Desaulniers
> <ndesaulniers@...gle.com> wrote:
> >
> > Generally, printing an int with %hhu may truncate depending on the
> > value of the int.
>
> Yes.
>
> HOWEVER.
>
> That truncation is *LITERALLY THE MAIN REASON TO EVER USE %hhu IN THE
> FIRST PLACE*.
>
> See the issue?
>
> Warning about "this may truncate bits" when the main reason to use
> that format string in the first place is said bit truncation is kind
> of stupid, isn't it?

Yeah, I guess adding a truncate to the caller is kind of unnecessary
if you're still going to use %hhd anyways.  What are your thoughts on
this bug I've filed?
https://github.com/llvm/llvm-project/issues/57102

-- 
Thanks,
~Nick Desaulniers