This implementation of try_operation_return_as(expr) returns whatever the input type’s .as_failure() member function returns. basic_result and basic_outcome provide such a member function, see auto as_failure() const &.

Requires: That the expression std::declval<T>().as_failure() is a valid expression.

Namespace: BOOST_OUTCOME_V2_NAMESPACE

Header: <boost/outcome/try.hpp>