foo.cc: In function ‘int main()’:
foo.cc:18:19: warning: ‘x2’ may be used uninitialized [-Wmaybe-uninitialized]
   18 |                 x2+=x1*i;
      |                 ~~^~~~~~
foo.cc:6:18: note: ‘x2’ was declared here
    6 |         int x,x1,x2,i=1;
      |                  ^~