foo.cc: In constructor ‘Vector3::Vector3()’:
foo.cc:10:21: warning: unused variable ‘x’ [-Wunused-variable]
   10 |                 int x = 0;
      |                     ^
foo.cc:11:21: warning: unused variable ‘y’ [-Wunused-variable]
   11 |                 int y = 0;
      |                     ^
foo.cc:12:21: warning: unused variable ‘z’ [-Wunused-variable]
   12 |                 int z = 0;
      |                     ^