Re: [linux-next:master 9529/10007] mm/hugetlb.c:1591:9: warning: no previous prototype for function 'hugetlb_basepage_index'

[Nathan Chancellor <nathan@kernel.org>]

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On Tue, Jun 15, 2021 at 05:03:40PM +0100, Matthew Wilcox wrote:
> On Tue, Jun 15, 2021 at 11:58:36PM +0800, kernel test robot wrote:
> >         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm64 
> > 
> > If you fix the issue, kindly add following tag as appropriate
> > Reported-by: kernel test robot <lkp@intel.com>
> > 
> > All warnings (new ones prefixed by >>):
> > 
> > >> mm/hugetlb.c:1591:9: warning: no previous prototype for function 'hugetlb_basepage_index' [-Wmissing-prototypes]
> >    pgoff_t hugetlb_basepage_index(struct page *page)
> 
> So clang requires the prototype to still be in scope, while gcc doesn't.
> Does one of our clangers want to file a bug about that?

I see the exact same warning with GCC 11.1.0:

$ curl -LSs https://lore.kernel.org/linux-mm/202106152328.Mh5S48hE-lkp(a)intel.com/2-a.bin | gzip -d > .config

$ make -skj"$(nproc)" ARCH=arm64 CROSS_COMPILE=aarch64-linux- W=1 olddefconfig mm/hugetlb.c
mm/hugetlb.c:1591:9: warning: no previous prototype for 'hugetlb_basepage_index' [-Wmissing-prototypes]
 1591 | pgoff_t hugetlb_basepage_index(struct page *page)
      |         ^~~~~~~~~~~~~~~~~~~~~~

Cheers,
Nathan