...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Adapt a completion token to specify that the completion handler should capture error_code values to a variable.
template< typename CompletionToken> constexpr redirect_error_t< decay_t< CompletionToken > > operator()( CompletionToken && completion_token) const;