foo.cc: In function ‘long long int l(int)’:
foo.cc:12:17: error: ‘a’ was not declared in this scope
   12 |                 a=b;
      |                 ^
foo.cc:13:19: error: ‘c’ was not declared in this scope
   13 |                 b=c;
      |                   ^
foo.cc:14:19: error: ‘d’ was not declared in this scope
   14 |                 c=d;
      |                   ^
foo.cc:16:16: error: ‘c’ was not declared in this scope
   16 |         return c;
      |                ^