/in/foo.c: In function 'main':
/in/foo.c:6:8: warning: unused variable 'b' [-Wunused-variable]
  int a,b,i;
        ^
/in/foo.c: In function 'fib':
/in/foo.c:19:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  for (i=2;i<=sqrt(a);i++)
  ^~~
/in/foo.c:22:3: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'for'
   return 1;
   ^~~~~~