Re: Fwd: [PATCH] Turn off -Wmaybe-uninitialized when building with -Os

[Russell King - ARM Linux <linux@arm.linux.org.uk>]

On Fri, Mar 15, 2013 at 02:55:38PM +0000, Arnd Bergmann wrote:
> I forgot to put the linux-kbuild list on Cc, that is probably the
> best place to discuss this patch.
> 
> ----------  Forwarded Message  ----------
> 
> Subject: [PATCH] Turn off -Wmaybe-uninitialized when building with -Os
> Date: Thursday 14 March 2013
> From: Arnd Bergmann <arnd@arndb.de>
> To: linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
> 
> gcc-4.7 and higher add a lot of false positive warnings about
> potential uses of uninitialized warnings, but only when optimizing
> for size (-Os). This is the default when building allyesconfig,
> which turns on CONFIG_CC_OPTIMIZE_FOR_SIZE.
> 
> In order to avoid getting a lot of patches that initialize such
> variables and accidentally hide real errors along the way, let's
> just turn off this warning on the respective gcc versions
> when building with size optimizations. The -Wmaybe-uninitialized
> option was introduced in the same gcc version (4.7) that is now
> causing the false positives, so there is no effect on older compilers.
> 
> A side effect is that when building with CONFIG_CC_OPTIMIZE_FOR_SIZE,
> we might now see /fewer/ warnings about possibly uninitialized
> warnings than with -O2, but that is still much better than seeing
> warnings known to be bogus.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Cc: stable@vger.kernel.org
> --
> I'd like to merge this for 3.9 and also for the stable kernels,
> if people agree this is a good idea.

I think I replied to your previous version recently asking whether
this affects real uninitialized variables too.