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From:   Masahiro Yamada <yamada.masahiro@socionext.com>
Date:   Mon, 19 Nov 2018 19:34:45 +0900
Message-ID: <CAK7LNASrWhSbP7=g-iMvEdr48ZLCp+dhgpSUkURC+r1XZiM16Q@mail.gmail.com>
Subject: Re: [PATCH v2 2/2] build_bug.h: remove all dummy BUILD_BUG_ON stubs
 for sparse
To:     Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Kees Cook <keescook@chromium.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Sat, Nov 17, 2018 at 9:33 AM Luc Van Oostenryck
<luc.vanoostenryck@gmail.com> wrote:
>
> On Fri, Nov 16, 2018 at 03:27:25PM +0900, Masahiro Yamada wrote:
> > The introduction of these dummy BUILD_BUG_ON stubs dates back to
> > commit 903c0c7cdc21 ("sparse: define dummy BUILD_BUG_ON definition
> > for sparse"). At that time, BUILD_BUG_ON() was implemented with the
> > negative array trick, which Sparse complains about even if the
> > condition can be optimized and evaluated to 0 at compile-time.
>
> OK, but from what I understand, the motivation for commit 903c0c7cdc21
> was not to avoid false warnings but to avoid having twice the same
> warnings: "... So it causes sparse to detect an error too. This
> reduces sparse's usefulness.").

In fact, Sparse was producing false positives.

I mentioned this in the commit message of v3.


> I'm not opposed to this patch (on the contrary, I think it's better
> to have exactly the same code for GCC than for sparse) but I think
> that your commit message need to be adjusted.
>
> Kind regards,
> -- Luc


-- 
Best Regards
Masahiro Yamada