gcc 4.9 build warnings (was: Re: next build: 2674 warnings 1 failures (next/next-20141022))

[Russell King - ARM Linux]

On Fri, Oct 24, 2014 at 02:47:29PM -0700, Olof Johansson wrote:
> On Thu, Oct 23, 2014 at 3:26 PM, Russell King - ARM Linux
> <linux at arm.linux.org.uk> wrote:
> > On Thu, Oct 23, 2014 at 10:31:07PM +0200, Arnd Bergmann wrote:
> >> On Thursday 23 October 2014 17:12:20 Russell King - ARM Linux wrote:
> >> >
> >> > > I haven't found the code in gcc that performs the type check for
> >> > > printf, but I've found a comment about that code intentionally
> >> > > resolving the type (printing 'unsigned int') when the typedef
> >> > > does not match the expected type.
> >> >
> >> > If I had a copy of the GCC 4.9 source locally, I'd dig into it too and
> >> > try to work out what's going on.  My gut feeling is that it's a bug in
> >> > GCC rather than something which the kernel is doing wrong.
> >> >
> >>
> >> I suspect it has something to do with the way that Olof's gcc is built,
> >> since it doesn't happen for me using the same kernel source and gcc-4.9.1
> >> or 4.10-prerelease.
> >>
> >> The fact that it doesn't define __linux__ means that it must be configured
> >> in some other way than what I do or what I get from the distros.
> >
> > Hmm, which may mean that it does expect "unsigned long" for size_t.
> >
> > Olof, please can you try this fragment:
> >
> > typedef __SIZE_TYPE__ gcc_size_t;
> > #include <stdio.h>
> > int main() { size_t size = 1; printf("%zu\n", size); return 0; }
> >
> > with "arm-linux-gcc -E -o - test.c | grep size_t" and check what the
> > actual typedefs passed to the compiler proper are?  Thanks.
> 
> 
> Since it's a baremetal compiler, there's no stdio.h. Anyway, taking
> out the include line:
> 
> typedef unsigned int gcc_size_t;
> int main() { size_t size = 1; printf("%zu\n", size); return 0; }
> 
> 
> I guess I should just look at building a full compiler set instead of
> this silliness. On the other hand, it's good to get it exposed I
> suppose.

In which case, use #include <stddef.h> which should be provided by
the compiler.

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