Re: mainline build failure for arm64 allmodconfig with clang

From: Nick Desaulniers <ndesaulniers@google.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Joe Perches <joe@perches.com>,
	Nathan Chancellor <nathan@kernel.org>,
	 "Sudip Mukherjee (Codethink)" <sudipm.mukherjee@gmail.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	 Michal Marek <michal.lkml@markovi.net>,
	linux-kbuild@vger.kernel.org,  linux-kernel@vger.kernel.org,
	clang-built-linux <llvm@lists.linux.dev>,
	 Justin Stitt <justinstitt@google.com>
Subject: Re: mainline build failure for arm64 allmodconfig with clang
Date: Thu, 11 Aug 2022 15:04:29 -0700	[thread overview]
Message-ID: <CAKwvOdkUc=8DD938in5PMeGYAn3PEWp4E_W8qEHq_y7Smy8+mQ@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=wgJA=e-CLcvU5LRKu0bMLeAewXtOM6as1hFVeQAVkMPbg@mail.gmail.com>

On Thu, Aug 11, 2022 at 12:35 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Thu, Aug 11, 2022 at 11:39 AM Nick Desaulniers
> <ndesaulniers@google.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