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Message-ID: <20170525055207.udcphnshuzl2gkps@gmail.com>
Date: Thu, 25 May 2017 07:52:07 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Matthias Kaehlcke <mka@...omium.org>
Cc: David Rientjes <rientjes@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Christoph Lameter <cl@...ux.com>,
Pekka Enberg <penberg@...nel.org>,
Joonsoo Kim <iamjoonsoo.kim@....com>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org,
Douglas Anderson <dianders@...omium.org>,
Mark Brown <broonie@...nel.org>,
David Miller <davem@...emloft.net>
Subject: Re: [patch] compiler, clang: suppress warning for unused static
inline functions
* Matthias Kaehlcke <mka@...omium.org> wrote:
> El Wed, May 24, 2017 at 02:01:15PM -0700 David Rientjes ha dit:
>
> > GCC explicitly does not warn for unused static inline functions for
> > -Wunused-function. The manual states:
> >
> > Warn whenever a static function is declared but not defined or
> > a non-inline static function is unused.
> >
> > Clang does warn for static inline functions that are unused.
> >
> > It turns out that suppressing the warnings avoids potentially complex
> > #ifdef directives, which also reduces LOC.
> >
> > Supress the warning for clang.
> >
> > Signed-off-by: David Rientjes <rientjes@...gle.com>
> > ---
>
> As expressed earlier in other threads, I don't think gcc's behavior is
> preferable in this case. The warning on static inline functions (only
> in .c files) allows to detect truly unused code. About 50% of the
> warnings I have looked into so far fall into this category.
>
> In my opinion it is more valuable to detect dead code than not having
> a few more __maybe_unused attributes (there aren't really that many
> instances, at least with x86 and arm64 defconfig). In most cases it is
> not necessary to use #ifdef, it is an option which is preferred by
> some maintainers. The reduced LOC is arguable, since dectecting dead
> code allows to remove it.
Static inline functions in headers are often not dead code.
Thanks,
Ingo
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