C++ Debugging: Doubly Linked List

A small C++ doubly linked list implementation lives in src/. It compiles. Most of it works. Two of its behaviours are wrong, and the symptoms you see in tests/test_dll.cpp will not always point you straight at the lines that have to change -- the file that prints the failure is not always the file that owns the bug. Find the defects, fix them, and make every test in tests/test_dll.cpp pass. The list operations that must work after the fix: push_front, push_back -- add a node…