[frank-w-bpi-r2-4.14:7.2-rc 213/213] drivers/net/phy/as21xx_1.9.2/as21xx_bbu_api/as21xx_debugfs.c:52:2: error: call to undeclared library function 'strncpy' with type 'char *(char *, const char *, __size_t)' (aka 'char *(char *, const char *, unsigned long)'); ISO C99 and later do not suppor...

[frank-w-bpi-r2-4.14:7.2-rc 213/213] drivers/net/phy/as21xx_1.9.2/as21xx_bbu_api/as21xx_debugfs.c:52:2: error: call to undeclared library function 'strncpy' with type 'char *(char *, const char *, __size_t)' (aka 'char *(char *, const char *, unsigned long)'); ISO C99 and later do not suppor...

[kernel test robot]

tree:   https://github.com/frank-w/BPI-R2-4.14 7.2-rc
head:   8f1ae3a99f8f4bbde9c6a17df87b4585fc4eb674
commit: 2cb20c86841cfe9fb52a28ab7025aca03c73bb73 [213/213] net: phy: as21xxx: update driver to v1.9.2
config: s390-allmodconfig (https://download.01.org/0day-ci/archive/20260901/202609010140.6ybLjc5l-lkp@intel.com/config)
compiler: clang version 24.0.0git (https://github.com/llvm/llvm-project 316b0edee400b3ef72ed0a082dae9bd337ac01a0)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260901/202609010140.6ybLjc5l-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/202609010140.6ybLjc5l-lkp@intel.com/

All errors (new ones prefixed by >>):

>> drivers/net/phy/as21xx_1.9.2/as21xx_bbu_api/as21xx_debugfs.c:52:2: error: call to undeclared library function 'strncpy' with type 'char *(char *, const char *, __size_t)' (aka 'char *(char *, const char *, unsigned long)'); ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
      52 |         strncpy(buffer, input, sizeof(buffer));
         |         ^
   drivers/net/phy/as21xx_1.9.2/as21xx_bbu_api/as21xx_debugfs.c:52:2: note: include the header <string.h> or explicitly provide a declaration for 'strncpy'
   1 error generated.


vim +52 drivers/net/phy/as21xx_1.9.2/as21xx_bbu_api/as21xx_debugfs.c

    38	
    39	/******************************************************************************
    40	 * Static Function
    41	 *****************************************************************************/
    42	static int parse_cmd_args(const char *input, struct parsed_cmd *result, int max_args)
    43	{
    44		char buffer[MAX_BUF];
    45		char *token, *ptr;
    46		int count = 0;
    47		size_t len;
    48	
    49		if (!input || !result || max_args > MAX_ARGS)
    50			return -EINVAL;
    51	
  > 52		strncpy(buffer, input, sizeof(buffer));
    53		buffer[sizeof(buffer) - 1] = '\0';
    54	
    55		// clear '\n'
    56		len = strlen(buffer);
    57		if (len > 0 && buffer[len - 1] == '\n')
    58			buffer[len - 1] = '\0';
    59	
    60		ptr = buffer;
    61	
    62		token = strsep(&ptr, " ");
    63		while (token && *token == '\0')
    64			token = strsep(&ptr, " ");
    65	
    66		if (!token)
    67			return -EINVAL;
    68	
    69		strncpy(result->cmd, token, sizeof(result->cmd) - 1);
    70		result->cmd[sizeof(result->cmd) - 1] = '\0';
    71	
    72		while ((token = strsep(&ptr, " ")) != NULL && count < max_args) {
    73			if (*token == '\0')
    74				continue;
    75	
    76			if (kstrtol(token, 0, &result->args[count]) != 0)
    77				return -EINVAL;
    78	
    79			count++;
    80		}
    81	
    82		result->argc = count;
    83		return 0;
    84	}
    85	

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https://github.com/intel/lkp-tests/wiki