-/// @param result Set to the extension of \a path.
-/// @results errc::success if result has been successfully set, otherwise a
-/// platform specific error_code.
-error_code extension(const StringRef &path, StringRef &result);
+/// @result The extension of \a path.
+const StringRef extension(StringRef path);
+
+/// @brief Check whether the given char is a path separator on the host OS.
+///
+/// @param value a character
+/// @result true if \a value is a path separator character on the host OS
+bool is_separator(char value);
+
+/// @brief Get the typical temporary directory for the system, e.g.,
+/// "/var/tmp" or "C:/TEMP"
+///
+/// @param erasedOnReboot Whether to favor a path that is erased on reboot
+/// rather than one that potentially persists longer. This parameter will be
+/// ignored if the user or system has set the typical environment variable
+/// (e.g., TEMP on Windows, TMPDIR on *nix) to specify a temporary directory.
+///
+/// @param result Holds the resulting path name.
+void system_temp_directory(bool erasedOnReboot, SmallVectorImpl<char> &result);