#include <fontconfig.h>
FcBool FcConfigSubstituteWithPat (FcConfig *config, FcPattern *p, FcPattern *p_pat, FcMatchKindkind);
Performs the sequence of pattern modification operations, if kind is FcMatchPattern, then those tagged as pattern operations are applied, else if kind is FcMatchFont, those tagged as font operations are applied and p_pat is used for <test> elements with target=pattern.
Fontconfig version 2.3.2