foo.cc: In function 'int gys(int, int)':
foo.cc:8:5: warning: this 'else' clause does not guard... [-Wmisleading-indentation]
     else;
     ^~~~
foo.cc:9:9: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'else'
         return gys(Q,P%Q);
         ^~~~~~