Function GetSize

01.16-constexprFunctionInConcept0/main.cpp:8–11

#A A helper function with a default parameter

// #A A helper function with a default parameter
constexpr auto GetSize(const auto& t = {})
{
  return t.size();  // #B Call the size function of the container
}

// #C A concept which uses T.size
template<typename T, size_t N>