/in/foo.cc: In function 'int main()':
/in/foo.cc:141:30: warning: passing NULL to non-pointer argument 2 of 'void* memset(void*, int, size_t)' [-Wconversion-null]
  141 |                 memset(link, NULL, sizeof(link));
      |                              ^~~~
In file included from /usr/include/c++/12/cstring:42,
                 from /in/foo.cc:5:
/usr/include/string.h:61:37: note:   declared here
   61 | extern void *memset (void *__s, int __c, size_t __n) __THROW __nonnull ((1));
      |                                 ~~~~^~~