/in/foo.cc: In function 'void work(int)':
/in/foo.cc:18:16: warning: unused variable 'x1' [-Wunused-variable]
     double p,q,x1,x2,y1,y2;
                ^~
/in/foo.cc:18:19: warning: unused variable 'x2' [-Wunused-variable]
     double p,q,x1,x2,y1,y2;
                   ^~
/in/foo.cc:18:22: warning: unused variable 'y1' [-Wunused-variable]
     double p,q,x1,x2,y1,y2;
                      ^~
/in/foo.cc:18:25: warning: unused variable 'y2' [-Wunused-variable]
     double p,q,x1,x2,y1,y2;
                         ^~
/in/foo.cc: In function 'int ext(int)':
/in/foo.cc:14:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^