foo.cc: In function 'int X(int, int)':
foo.cc:14:1: warning: control reaches end of non-void function [-Wreturn-type]
   14 | }
      | ^
foo.cc: In function 'int Y(int, int)':
foo.cc:23:1: warning: control reaches end of non-void function [-Wreturn-type]
   23 | }
      | ^
foo.cc:15:5: warning: infinite recursion detected [-Winfinite-recursion]
   15 | int Y(int x, int y)
      |     ^
foo.cc:21:25: note: recursive call
   21 |                 return Y(x + 1, y);
      |                        ~^~~~~~~~~~

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