5 return x1 + x2 + x3; /* 1. uses x3 before definition */
15 return x1; /* 2, 3, 4. bad --- x1 not defined, x2, x3 not defined */
21 loc = x1; /* 5. x1 not defined */
22 loc = g(); /* 6. bad --- x1, x2 not defined before call (defines x2 and x3) */
27 loc = x3; /* 7. x3 not defined */
37 return 12; /* 8. returns with x3 not defined */
42 /* No errors to report. Previously,
43 [9, 10. returns with x2 and x3 undefined (x1 IS defined on all branches!)]
44 but this is not correct; all branches that can reach the return do define