/in/p2.cpp: In function 'opaque_list* filter_odd(list_t)':
/in/p2.cpp:47:32: warning: no return statement in function returning non-void [-Wreturn-type]
 list_t filter_odd(list_t list){};
                                ^
/in/p2.cpp: In function 'opaque_list* filter_even(list_t)':
/in/p2.cpp:49:33: warning: no return statement in function returning non-void [-Wreturn-type]
 list_t filter_even(list_t list){};
                                 ^
/in/p2.cpp: In function 'opaque_list* filter(list_t, bool (*)(int))':
/in/p2.cpp:51:45: warning: no return statement in function returning non-void [-Wreturn-type]
 list_t filter(list_t list, bool (*fn)(int)){};
                                             ^
/in/p2.cpp: In function 'int depth(tree_t)':
/in/p2.cpp:78:24: warning: no return statement in function returning non-void [-Wreturn-type]
 int depth(tree_t tree){};
                        ^
/in/p2.cpp: In function 'int tree_min(tree_t)':
/in/p2.cpp:80:27: warning: no return statement in function returning non-void [-Wreturn-type]
 int tree_min(tree_t tree){};
                           ^
/in/p2.cpp: In function 'bool tree_hasPathSum(tree_t, int)':
/in/p2.cpp:89:44: warning: no return statement in function returning non-void [-Wreturn-type]
 bool tree_hasPathSum(tree_t tree, int sum){};
                                            ^
/in/p2.cpp: In function 'opaque_tree* insert_tree(int, tree_t)':
/in/p2.cpp:111:42: warning: no return statement in function returning non-void [-Wreturn-type]
 tree_t insert_tree(int elt, tree_t tree){};
                                          ^