[linux-next:master 9303/13299] arch/m68k/include/asm/raw_io.h:20:18: warning: array subscript 0 is outside array bounds of 'const volatile u8[0]' {aka 'const volatile unsigned char[]'}

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

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   2dac75696c6da3c848daa118a729827541c89d33
commit: c7db3832ff19a9a1116c1b3d435c9db165a2f2f8 [9303/13299] m68k: io: Mark mmio read addresses as const
config: m68k-allyesconfig (https://download.01.org/0day-ci/archive/20231019/202310190741.mbPtQRpD-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231019/202310190741.mbPtQRpD-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/202310190741.mbPtQRpD-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from arch/m68k/include/asm/io_mm.h:25,
                    from arch/m68k/include/asm/io.h:8,
                    from include/linux/io.h:13,
                    from drivers/hwmon/pc87427.c:31:
   drivers/hwmon/pc87427.c: In function 'pc87427_readall_pwm':
>> arch/m68k/include/asm/raw_io.h:20:18: warning: array subscript 0 is outside array bounds of 'const volatile u8[0]' {aka 'const volatile unsigned char[]'} [-Warray-bounds=]
      20 |     ({ u8 __v = (*(__force const volatile u8 *) (unsigned long)(addr)); __v; })
         |                 ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   arch/m68k/include/asm/io_mm.h:345:62: note: in expansion of macro 'in_8'
     345 | #define inb(port)       ((port) < 1024 ? isa_rom_inb(port) : in_8(port))
         |                                                              ^~~~
   drivers/hwmon/pc87427.c:244:32: note: in expansion of macro 'inb'
     244 |         data->pwm_enable[nr] = inb(iobase + PC87427_REG_PWM_ENABLE);
         |                                ^~~
   cc1: note: source object is likely at address zero


vim +20 arch/m68k/include/asm/raw_io.h

    15	
    16	/* ++roman: The assignments to temp. vars avoid that gcc sometimes generates
    17	 * two accesses to memory, which may be undesirable for some devices.
    18	 */
    19	#define in_8(addr) \
  > 20	    ({ u8 __v = (*(__force const volatile u8 *) (unsigned long)(addr)); __v; })
    21	#define in_be16(addr) \
    22	    ({ u16 __v = (*(__force const volatile u16 *) (unsigned long)(addr)); __v; })
    23	#define in_be32(addr) \
    24	    ({ u32 __v = (*(__force const volatile u32 *) (unsigned long)(addr)); __v; })
    25	#define in_le16(addr) \
    26	    ({ u16 __v = le16_to_cpu(*(__force const volatile __le16 *) (unsigned long)(addr)); __v; })
    27	#define in_le32(addr) \
    28	    ({ u32 __v = le32_to_cpu(*(__force const volatile __le32 *) (unsigned long)(addr)); __v; })
    29	

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