/in/foo.cc: In function 'int main()':
/in/foo.cc:8:7: warning: operation on 'a' may be undefined [-Wsequence-point]
    8 |     a = ++a;
      |     ~~^~~~~
/in/foo.cc:8:7: warning: operation on 'a' may be undefined [-Wsequence-point]
/in/foo.cc:9:7: warning: operation on 'b' may be undefined [-Wsequence-point]
    9 |     b = ++b;
      |     ~~^~~~~
/in/foo.cc:9:7: warning: operation on 'b' may be undefined [-Wsequence-point]