void clear() noexcept;
path& make_preferred();
path p("foo/bar"); std::cout << p << '\n'; p.make_preferred(); std::cout << p << '\n';
"foo/bar" "foo/bar"
"foo/bar" "foo\bar"
path& remove_filename();
path& replace_filename(const path& replacement);
path& replace_extension(const path& replacement = path());
void swap(path& rhs) noexcept;