simple way to convert parameter pack to array at compile time

Question

is there a simple way to create an std::array from a parameter pack at compile time?

constexpr auto array = to_array<int>(1, 2, 3, 'a', 5.5f);

there are existing solutions:

• helper functions & classes with recursion: not intuitive, difficult to read and not very modern
• C++20's std::to_array({...}): sadly it only works when all argument types are equal

what would be a clean way to implement this?

Answer 1

What about simply

template <typename T, typename... Args>
constexpr std::array<T, sizeof...(Args)> to_array (Args && ... args)
 { return {{ std::forward<Args>(args)... }}; }

?

Or, maybe, if you want to add the static_cast

template <typename T, typename... Args>
constexpr std::array<T, sizeof...(Args)> to_array (Args && ... args)
 { return {{ static_cast<T>(std::forward<Args>(args))... }}; }

and using CTAD and auto return placeholder, you can reduce a little the typewriting

template <typename T, typename... Args>
constexpr auto to_array (Args && ... args)
 { return std::array{ static_cast<T>(std::forward<Args>(args))... }; }