Return the output from free function auto failure(T &&, ...) containing a move from any errored and/or excepted state, thus leaving the outcome’s error and exception values in a moved-from state. Depending on the choice of error_type and/or exception_type, this function may therefore be destructive. The error and exception states are accessed using error_type &&assume_error() && noexcept and exception_type &&assume_exception() && noexcept .

Requires: Always available.

Complexity: Whatever that of error_type’s and/or exception_type’s move constructor is.

Guarantees: None.