Move-assign a stream descriptor from another.

basic_stream_descriptor & operator=(
    basic_stream_descriptor && other);
  » more...

Move-assign a posix::basic_stream_descriptor from a descriptor of another executor type.

template<
    typename Executor1>
constraint< is_convertible< Executor1, Executor >::value, basic_stream_descriptor & >::type operator=(
    basic_stream_descriptor< Executor1 > && other);
  » more...