I thought I understood this.

What this C++ memory-management interview question tests

This is a practical code-review question designed to assess whether you understand the semantics and common pitfalls of std::shared_ptr in modern C++. Rather than asking you to write from scratch, it presents a real scenario and asks you to spot the issue — a pattern that mirrors actual code review in trading and systems teams.

The question rewards deep understanding of reference counting, object lifetime, move semantics, and circular-reference traps. A strong answer requires you to reason about when shared ownership is appropriate, how reference counts behave, and what kinds of bugs emerge when smart pointers are used carelessly. You'll need to explain not just what is wrong, but why it matters and what the consequences are.

• Reference counting and cycle detection
• Ownership semantics and move vs. copy
• When shared_ptr is the right tool (and when it isn't)
• Common misuse patterns in real codebases