cpp/io/basic syncbuf/operator=

First, calls to transmit all pending output (and delayed flush, if any) to the wrapped stream.

Then performs move-assignment by moving all contents from, including the temporary storage, the wrapped stream pointer, policy, and all other state (such as the mutex pointer). After move, is not associated with a stream, and. The put area member pointers of the base class std of are guaranteed to be null. Destroying a moved-from will not produce any output.

If is, then the allocator is unchanged. Otherwise, after move-assignment, equals.