In file included from logfiles.c:22:
In function ‘split_string’,
    inlined from ‘split_filename’ at logfiles.c:204:17,
    inlined from ‘make_logfile_list’ at logfiles.c:1687:25,
    inlined from ‘process_logrt’ at logfiles.c:3007:24:
../../../include/log.h:69:4: warning: ‘%s’ directive argument is null [-Wformat-overflow=]
   69 |    __zbx_zabbix_log(level, __VA_ARGS__);      \
      |    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
logfiles.c:94:2: note: in expansion of macro ‘zabbix_log’
   94 |  zabbix_log(LOG_LEVEL_DEBUG, "End of %s():%s part1:'%s' part2:'%s'", __func__, zbx_result_string(ret),
      |  ^~~~~~~~~~
logfiles.c: In function ‘process_logrt’:
logfiles.c:94:53: note: format string is defined here
   94 |  zabbix_log(LOG_LEVEL_DEBUG, "End of %s():%s part1:'%s' part2:'%s'", __func__, zbx_result_string(ret),
      |                                                     ^~
In file included from logfiles.c:22:
In function ‘split_filename’,
    inlined from ‘make_logfile_list’ at logfiles.c:1687:25,
    inlined from ‘process_logrt’ at logfiles.c:3007:24:
../../../include/log.h:69:4: warning: ‘%s’ directive argument is null [-Wformat-overflow=]
   69 |    __zbx_zabbix_log(level, __VA_ARGS__);      \
      |    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
logfiles.c:229:2: note: in expansion of macro ‘zabbix_log’
  229 |  zabbix_log(LOG_LEVEL_DEBUG, "End of %s():%s directory:'%s' filename_regexp:'%s'", __func__,
      |  ^~~~~~~~~~
logfiles.c: In function ‘process_logrt’:
logfiles.c:229:57: note: format string is defined here
  229 |  zabbix_log(LOG_LEVEL_DEBUG, "End of %s():%s directory:'%s' filename_regexp:'%s'", __func__,
      |                                                         ^~

$ gcc --version
gcc (Ubuntu 9.3.0-10ubuntu2) 9.3.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.