What this C++ operator overloading question tests
This is a medium-difficulty question on C++ operator overloading and function resolution. It challenges your understanding of how the compiler selects between overloaded operators, how member functions and free functions interact, and the sometimes counterintuitive precedence rules that govern the lookup and binding process.
To solve problems like this, you need to reason carefully about which overload the compiler will choose given the types involved, the order in which lookup happens (unqualified name lookup, argument-dependent lookup), and whether member functions take precedence over free functions. The question rewards precision: a small difference in operator signature or argument count can completely change the result.
- Member function vs. free function overload resolution
- Implicit conversions and their role in overload selection
- Operator precedence and associativity
- Unqualified name lookup and ADL (argument-dependent lookup)