::is_static_castable

#include <type_traits>

namespace details {

  template<typename From, typename To>
  using static_cast_expression = std::void_t<decltype(static_cast<To>(std::declval<From>()))>;

  template<typename From, typename To, typename = std::void_t<>>
  struct is_static_castable : std::false_type { };

  template<typename From, typename To>
  struct is_static_castable<From, To, static_cast_expression<From, To>> : std::true_type { };

}

template<typename From, typename To>
struct is_static_castable : details::is_static_castable<From, To>::type { };

template<typename From, typename To>
constexpr bool is_static_castable_v = is_static_castable<From, To>::value;