Extcon build failure in next

[arnd@arndb.de (Arnd Bergmann)]

On Thursday, June 30, 2016 4:49:12 AM CEST Tony Lindgren wrote:
> > > Also I'm seeing:
> > > 
> > > drivers/extcon/extcon.c: In function 'extcon_register_notifier':
> > > drivers/extcon/extcon.c:455:6: warning: 'idx' may be used uninitialized in this function [-Wmaybe-uninitialized]
> > >    if (idx >= 0) {
> > >          ^
> > 
> > I don't see this one. Which compiler version do you use?
> 
> Looks like I'm currently using older arm-none-linux-gnueabi-gcc
> (Sourcery CodeBench Lite 2014.05-29) 4.8.3 20140320 (prerelease).
> I think the Debian compiler was not working few months ago and
> I changed to something I had around.
> 
> Looks like the warning does not appear with arm-linux-gnueabihf-gcc
> (Debian 6.1.1-3) 6.1.1 20160511.

You are certainly not the only one using gcc-4.7 or gcc-4.8, but
they are known to produce more false postive -Wmaybe-uninitialized
warnings and 4.9 or higher. I usually send patches for these warnings
when gcc-6 finds them, and I have recently sent patches for all
the warnings I got in allmodconfig with 4.9, but have no plans to
do that for the older compilers.

I wonder whether we should just disable this warning with gcc-4.8
by adding $(call cc-ifversion, -eq, 0408, -Wno-maybe-uninitialized)
to the command line. However, gcc-4.7 does not let you turn off
the warning at all, so the use of that is fairly limited.

	Arnd