BOOST_OUTCOME_USE_STD_IS_NOTHROW_SWAPPABLE
Whether to implement is_nothrow_swappable<T> as std::is_nothrow_swappable<T>,
or else use a local emulation.
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: <boost/outcome/config.hpp>



