Can't assign string literal to boxed std::string vector

Question

This is a simplified version of my type system:

#include 
#include 

template
class Box {
public:
    Box(const T&a         


        

Answer 1

c currently need 2 implicit user conversions (const char [N] -> std::string -> String) whereas only one is allowed.

You may add template constructor to Box

template
class Box {
public:
    Box() = default;
    Box(const Box&) = default;
    Box(Box&&) default;
    ~Box() = default;

    Box& operator=(const Box&) = default;
    Box& operator=(Box&&) = default;

    template ::value
                               && (!std::is_same>::value
                                  || sizeof...(Us) != 0)>* = nullptr>
    Box(U0&& u0, Us&&... us) : _value(std::forward(u0), std::forward(us)...) {}
private:
    T _value;
    /* ... */
};

Demo Demo2