27 Input/output library [input.output]

27.10 Synchronized output streams [syncstream]

27.10.3 Class template basic_­osyncstream [syncstream.osyncstream] Assignment [syncstream.osyncstream.assign]

basic_osyncstream& operator=(basic_osyncstream&& rhs) noexcept;
Effects: First, calls emit().
If an exception is thrown from emit(), that exception is caught and ignored.
Move assigns sb from rhs.sb.
This disassociates rhs from its wrapped stream buffer ensuring destruction of rhs produces no output.
end note
Ensures: nullptr == rhs.get_­wrapped() is true.
get_­wrapped() returns the value previously returned by rhs.get_­wrapped().