+/// @brief Get the user's cache directory.
+///
+/// Expect the resulting path to be a directory shared with other
+/// applications/services used by the user. Params \p Path1 to \p Path3 can be
+/// used to append additional directory names to the resulting path. Recommended
+/// pattern is <user_cache_directory>/<vendor>/<application>.
+///
+/// @param Result Holds the resulting path.
+/// @param Path1 Additional path to be appended to the user's cache directory
+/// path. "" can be used to append nothing.
+/// @param Path2 Second additional path to be appended.
+/// @param Path3 Third additional path to be appended.
+/// @result True if a cache directory path is set, false otherwise.
+bool user_cache_directory(SmallVectorImpl<char> &Result, const Twine &Path1,
+ const Twine &Path2 = "", const Twine &Path3 = "");
+