Two Handles, Three Calls

What this C++ language-knowledge question tests

This is a medium-difficulty question that probes your understanding of C++ object semantics, particularly how copy constructors, move semantics, and temporary object lifetime interact in a single expression. It's the kind of question interviewers ask to separate candidates who have read the standard from those who have only used the language casually.

To answer correctly, you need to trace through the order of constructor and destructor calls as the compiler evaluates the expression, paying close attention to which objects are temporaries, when they are materialized, and when they are destroyed. The answer hinges on understanding the precise rules governing temporary lifetime extension and the timing of cleanup.

• Copy constructor vs. move constructor semantics
• Temporary object creation and destruction order
• Return value optimization and elision rules
• Reference binding and lifetime extension