/in/p2.cpp:347:1: warning: multi-line comment [-Wcomment]
 // / \
 ^
/in/p2.cpp:350:1: warning: multi-line comment [-Wcomment]
 // / \ / \
 ^
/in/p2.cpp:352:1: warning: multi-line comment [-Wcomment]
 // / \ / \
 ^
/in/p2.cpp:354:1: warning: multi-line comment [-Wcomment]
 // / \ / \
 ^
/in/p2.cpp:452:1: warning: multi-line comment [-Wcomment]
 //     / \
 ^
/in/p2.cpp:455:1: warning: multi-line comment [-Wcomment]
 //  / \   / \
 ^
/in/p2.cpp:457:1: warning: multi-line comment [-Wcomment]
 //    / \
 ^
/in/p2.cpp:513:1: warning: multi-line comment [-Wcomment]
 //             / \
 ^
/in/p2.cpp:516:1: warning: multi-line comment [-Wcomment]
 //          / \   / \
 ^
/in/p2.cpp:518:1: warning: multi-line comment [-Wcomment]
 //        / \ / \
 ^
/in/p2.cpp:611:1: warning: multi-line comment [-Wcomment]
 //                 / \
 ^
/in/p2.cpp:614:1: warning: multi-line comment [-Wcomment]
 //              / \   / \
 ^
/in/p2.cpp:616:1: warning: multi-line comment [-Wcomment]
 //                / \
 ^
/in/p2.cpp:620:1: warning: multi-line comment [-Wcomment]
 //                 / \
 ^
/in/p2.cpp:623:1: warning: multi-line comment [-Wcomment]
 //              / \   / \
 ^
/in/p2.cpp:625:1: warning: multi-line comment [-Wcomment]
 //            / \ / \
 ^
/in/p2.cpp: In function 'int sumHelper(list_t, int)':
/in/p2.cpp:37:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/in/p2.cpp: In function 'int productHelper(list_t, int)':
/in/p2.cpp:54:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/in/p2.cpp: In function 'opaque_list* filter_oddHelper(list_t, list_t)':
/in/p2.cpp:157:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/in/p2.cpp: In function 'opaque_list* filter_evenHelper(list_t, list_t)':
/in/p2.cpp:181:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/in/p2.cpp: In function 'opaque_list* filterHelper(list_t, bool (*)(int), list_t)':
/in/p2.cpp:202:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/in/p2.cpp: In function 'int tree_sumHelper(tree_t, int, int)':
/in/p2.cpp:292:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/in/p2.cpp: In function 'int tree_minHelper(tree_t, int)':
/in/p2.cpp:375:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/in/p2.cpp: In function 'bool covered_byHelper(tree_t, tree_t)':
/in/p2.cpp:547:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/tmp/cchwphsB.o: In function `main':
driver.cpp:(.text.startup+0x0): multiple definition of `main'
/tmp/ccS5FQ3s.o:p2.cpp:(.text.startup+0x0): first defined here
collect2: error: ld returned 1 exit status