basic_filebuf();

basic_filebuf( const std::basic_filebuf& rhs ) = delete;

basic_filebuf( std::basic_filebuf&& rhs );

1) Constructs a std::basic_filebuf object, initializing the base class by calling the default constructor of std::basic_streambuf. The created basic_filebuf is not associated with a file, and is_open() returns false.

2) The copy constructor is deleted; std::basic_filebuf is not CopyConstructible

3) Move-constructs a std::basic_filebuf object by moving all contents from another std::basic_filebuf object rhs, including the buffers, the associated file, the locale, the openmode, the is_open variable, and all other state. After move, rhs is not associated with a file and rhs.is_open() == false. The member pointers of the base class std::basic_streambuf of rhs and of the base class of *this are guaranteed to point to different buffers (unless null).