Re: [patch] compiler, clang: suppress warning for unused static inline functions

[Matthias Kaehlcke]

El Thu, May 25, 2017 at 07:52:07AM +0200 Ingo Molnar ha dit:

> 
> * Matthias Kaehlcke <mka@xxxxxxxxxxxx> 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@xxxxxxxxxx>
> > > ---
> > 
> > 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.

Sure, there is no intention to delete these and clang doesn't raise
warnings about unused static inline functions in headers.