1.C

malets@ub:~$ cat 1.C
#include <cstdlib>

struct C {
  int *ptr;

  int& operator*() {
    return *ptr;
  }
};

int main(void) {
  C o = {NULL};
  return &*o == NULL;
}
malets@ub:~$ clang++ -fsanitize=undefined -o 1 1.C && ./1
==397678==WARNING: Trying to symbolize code, but external symbolizer is not initialized!
1.C:7:12: runtime error: reference binding to null pointer of type 'int'
malets@ub:~$