Re: [btrfs:pr/1157 91/97] fs/btrfs/messages.h:181:29: error: expected ')' before '__VA_OPT__'

[David Sterba <dsterba@suse.cz>]

On Thu, Apr 24, 2025 at 08:25:52AM +0200, David Sterba wrote:
> On Thu, Apr 24, 2025 at 02:19:12PM +0800, kernel test robot wrote:
> > tree:   https://github.com/btrfs/linux.git pr/1157
> > head:   10c06ead9f79886df92197deb8d5c7bc37d52971
> > commit: 3050d7e09e5d7781bd9cfd8a27fc3d942afcd15c [91/97] btrfs: enhance ASSERT() to take optional format string
> > config: arm-randconfig-001-20250424 (https://download.01.org/0day-ci/archive/20250424/202504241458.DGT7MuTv-lkp@intel.com/config)
> > compiler: arm-linux-gnueabi-gcc (GCC) 7.5.0
> > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250424/202504241458.DGT7MuTv-lkp@intel.com/reproduce)
> > 
> > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > the same patch/commit), kindly add following tags
> > | Reported-by: kernel test robot <lkp@intel.com>
> > | Closes: https://lore.kernel.org/oe-kbuild-all/202504241458.DGT7MuTv-lkp@intel.com/
> > 
> > All errors (new ones prefixed by >>):
> > 
> >    In file included from fs/btrfs/ctree.c:11:0:
> >    fs/btrfs/compression.h: In function 'btrfs_calc_input_length':
> > >> fs/btrfs/messages.h:181:29: error: expected ')' before '__VA_OPT__'
> >     #define __REST_ARGS(_, ...) __VA_OPT__(,) __VA_ARGS__
> >                                 ^
> 
> I don't understand what's the problem, it's gcc 7.5 on arm, can it be
> lack of support for __VA_OPT__? I'm not sure if the other syntax would
> work here, ##__VA_ARGS__ .

godbolt.org confirms it's lack of gcc support < 8, current minimum is
5.1 so I'll fix it with the gcc variadic macro extension that I wanted
to avoid originally.