How to implement in_place_type_t<T> and in_place_type<T>.

If set to 1, the <utility> header is included, and std::in_place_type_t<T> is aliased into OUTCOME_V2_NAMESPACE::in_place_type_t<T> along with std::in_place_type<T>.

If set to 0, a local emulation is used.

Overridable: Define before inclusion.

Default: If the current compiler implements C++ 17 or later, if unset this macro is defaulted to 1, otherwise it is defaulted to 0.

Header: <outcome/config.hpp>