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What this C++ language-knowledge question tests

This is a hard C++ question that probes deep familiarity with the language's scoping rules, object lifetime, and how references interact with temporary values. It rewards careful reading of code semantics over guesswork, and is the type of question that separates candidates who have worked extensively in C++ from those who rely on surface-level intuition.

To solve it, you need to trace through the execution carefully, paying close attention to variable scope, constructor and destructor timing, and the validity of references or pointers after certain operations. These are precisely the pitfalls that lead to subtle bugs in production systems, especially in latency-sensitive environments where memory safety and predictable behaviour are critical.

• Object lifetime and scope rules
• Reference binding and dangling references
• Constructor and destructor invocation order
• Temporary object semantics