const error_type &error() const &
Wide contract const lvalue reference observer of the stored error. NoValuePolicy::wide_error_check()
is first invoked, then the reference to the error is returned. As a valid default constructed error is always present, no undefined behaviour occurs if NoValuePolicy::wide_error_check()
returns.
Note that if error_type
is void
, only a const
overload returning void
is present.
Requires: Always available.
Complexity: Depends on NoValuePolicy::wide_error_check()
.
Guarantees: None.