Challenge: adding new method overloads when existing consumers use {} with args

[David Hurka]

On Saturday, July 23, 2022 8:26:47 PM CEST David Hurka wrote:
> > Had not yet thought about this challenge myself before, so curious what
> > people think can be done here?
> 
> Would it work to make foo(B) less tasty for implicit conversion with
> std::variant (or another small wrapper)?
> 
> ```
> class C
> {
> public:
>     void foo(A a);
>     /** @since ... */
>     void foo(std::variant<B> b);
> };
> ```
> 
> My assumption is that std::variant requires a “user-defined conversion” [1],
> and therefore an explicitly provided B object can be implicitly converted
> to a std::variant<B>, but the ambiguous {} can’t.

[1] https://en.cppreference.com/w/cpp/language/implicit_conversion#Order_of_the_conversions