linux-kernel - Re: [PATCH v2 2/2] build_bug.h: remove all dummy BUILD_BUG

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Message-ID: <20181117003109.jdac5rmjdmpmino7@ltop.local>
Date:   Sat, 17 Nov 2018 01:31:10 +0100
From:   Luc Van Oostenryck <luc.vanoostenryck@...il.com>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        Kees Cook <keescook@...omium.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Miguel Ojeda <miguel.ojeda.sandonis@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] build_bug.h: remove all dummy BUILD_BUG_ON stubs
 for sparse

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.").

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