The notional class template platformstl::basic_current_directory used to be a placeholder for the appropriate type for the given platform, relying on Intersecting Conformance of the resolved platform-specific types.
When compiling on UNIX platforms, the platformstl::basic_current_directory type would have resolved to the unixstl::basic_current_directory class. On Windows platforms it would have resolved to the winstl::basic_current_directory class.
However, with version 1.9, the current_directory family of types now uses the Special String Instance pattern, so there is no longer a basic_current_directory. Rather, there are the unixstl::current_directory_a and unixstl::current_directory, and winstl::current_directory_a, winstl::current_directory_w, and winstl::current_directory specialisations. For platform independence, use platformstl::current_directory_a and platformstl::current_directory.