[abelloni:rtc-next 7/14] drivers/rtc/rtc-renesas-rtca3.c:233:9: warning: result of comparison of constant 65535 with expression of type 'typeof (_Generic((mask), char: (unsigned char)0, unsigned char: (unsigned char)0, signed char: (unsigned char)0, unsigned short: (unsigned shor...

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux.git rtc-next
head:   041ca8884410a4f70b40521f34258c7b773ea5c2
commit: 2098bb8ac5f5a66b1a0e02512ae11b6208936c92 [7/14] rtc: renesas-rtca3: Factor out year decoding helper
config: riscv-allyesconfig (https://download.01.org/0day-ci/archive/20260623/202606230130.jmcAMnJP-lkp@intel.com/config)
compiler: clang version 23.0.0git (https://github.com/llvm/llvm-project a9b492db3d50683e446cd1a5c9ffaf4e92cb77a7)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260623/202606230130.jmcAMnJP-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/202606230130.jmcAMnJP-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/rtc/rtc-renesas-rtca3.c:233:9: warning: result of comparison of constant 65535 with expression of type 'typeof (_Generic((mask), char: (unsigned char)0, unsigned char: (unsigned char)0, signed char: (unsigned char)0, unsigned short: (unsigned short)0, short: (unsigned short)0, unsigned int: (unsigned int)0, int: (unsigned int)0, unsigned long: (unsigned long)0, long: (unsigned long)0, unsigned long long: (unsigned long long)0, long long: (unsigned long long)0, default: (mask)))' (aka 'unsigned char') is always false [-Wtautological-constant-out-of-range-compare]
     233 |         u8 y = FIELD_GET(mask, year);
         |                ^~~~~~~~~~~~~~~~~~~~~
   include/linux/bitfield.h:177:3: note: expanded from macro 'FIELD_GET'
     177 |                 __BF_FIELD_CHECK_REG(_mask, _reg, "FIELD_GET: ");       \
         |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/bitfield.h:79:50: note: expanded from macro '__BF_FIELD_CHECK_REG'
      79 |         BUILD_BUG_ON_MSG(__bf_cast_unsigned(mask, mask) >               \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
      80 |                          __bf_cast_unsigned(reg, ~0ull),                \
         |                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      81 |                          pfx "type of reg too small for mask")
         |                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/build_bug.h:40:58: note: expanded from macro 'BUILD_BUG_ON_MSG'
      40 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
         |                                     ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~
   include/linux/compiler_types.h:699:22: note: expanded from macro 'compiletime_assert'
     699 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
         |         ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/compiler_types.h:687:23: note: expanded from macro '_compiletime_assert'
     687 |         __compiletime_assert(condition, msg, prefix, suffix)
         |         ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/compiler_types.h:679:9: note: expanded from macro '__compiletime_assert'
     679 |                 if (!(condition))                                       \
         |                       ^~~~~~~~~
   1 warning generated.


vim +233 drivers/rtc/rtc-renesas-rtca3.c

   230	
   231	static u32 rtca3_decode_year(u8 mask, u16 year)
   232	{
 > 233		u8 y = FIELD_GET(mask, year);
   234		u32 century = bcd2bin((y == 0x99) ? 0x19 : 0x20);
   235	
   236		return (century * 100 + bcd2bin(y)) - 1900;
   237	}
   238	

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