#include <platformstl/filesystem/readdir_sequence.hpp>
The class is only defined in the platformstl when the platform is not UNIX, in which case it uses the services of another file-system enumeration type, e.g. winstl::basic_findfile_sequence. For UNIX compilation, it resolves to unixstl::readdir_sequence, relying on Intersecting Conformance of the resolved platform-specific types.