Understanding C++ variant behavior and type matching
This is a medium-difficulty C++ question that tests your grasp of std::variant semantics, particularly how the standard library resolves type conversions and selects the active member. It's the kind of detail-oriented question that surfaces in coding interviews at firms where precision around language features matters.
To reason through problems like this, you need to understand variant initialization rules, implicit conversions, and how the compiler picks among multiple candidate types when a value is assigned. The question rewards careful attention to the C++ standard's overload resolution and type-matching hierarchy, rather than guessing at output.
- std::variant construction and type deduction
- Implicit conversion rules in template contexts
- Overload resolution and best-fit semantics
- Active member tracking and visitation