FcBool FcDirSave (FcFontSet *set, FcStrSet *dirs, const FcChar8 *dir);
This function now does nothing aside from returning FcFalse. It used to creates the per-directory cache file for dir and populates it with the fonts in set and subdirectories in dirs. All of this functionality is now automatically managed by FcDirCacheLoad and FcDirCacheRead.
Fontconfig version 2.5.0