/in/foo.c: In function 'main':
/in/foo.c:8:9: error: 'aa' undeclared (first use in this function); did you mean 'a'?
    8 |         aa=a;
      |         ^~
      |         a
/in/foo.c:8:9: note: each undeclared identifier is reported only once for each function it appears in