Calling with No Arguments

What this C++ language-knowledge question tests

This is a hard C++ question that probes deep familiarity with function overloading, default arguments, and the subtle rules governing function resolution in the standard library. It rewards candidates who think carefully about how the compiler disambiguates between candidate functions and applies type conversions.

To solve problems like this, you need to trace through the overload resolution process: which functions are viable candidates, how does the compiler rank them by conversion cost, and what happens when multiple candidates have the same rank? The question also tests your understanding of edge cases in template instantiation and how the standard library's generic functions interact with user-defined code.

• Function overload resolution and candidate ranking
• Default arguments and function signatures
• Implicit type conversions and conversion sequences
• Template specialization and instantiation